EPA/ 600/2-88^003
January 1988
- 16-037*
CONTROL TECHNOLOGY OVERVIEW REPORT:
CFC EMISSIONS FROM RIGID
FOAM MANUFACTURING
by:
K.P. Wert, T.P. Nelson, and J.D. Quass
Radian Corporation
Austin, Texas 78720
EPA Contract No. 68-02-3994
Work Assignment 66
EPA Project Officer:
N. Dean Smith
Air and Energy Engineering Research Laboratory
Office of Environmental Engineering and Technology Demonstration
Research Triangle Park. NC 27711
AIR AND ENERGY ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NC 27711
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverie before completing)
i. REPORT NO
EPA/600/2-88/003
2.
ECIPIENT'S ACCESSION-NO.... _ „-.__
PBS 8 1608797AS
4. TITLE AND SUBTITLE
Control Technology Overview Report: CFC Emis-
sions from Rigid Foam Manufacturing
5. REPORT DATE
January 1988
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
K. P. Wert, T. P. Nelson, and J. D. Quass
B. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
Radian Corporation
P.O. Box 9948
Austin, Texas 78720
11. CONTRACT/GRANT NO.
68-02-3994, Task 66
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Task Final; 3/86 - 11/86
14. SPONSORING AGENCY CODE
EPA/600/13
is. SUPPLEMENTARY NOTES AEERL project officer is N. Dean Smith. Mail Drop 62B. 919 /
541-2708.
is. ABSTRACT
repOrt estimates total chlorofluorocarbon (CFC) emissions from the
various rigid foam manufacturing processes and from the foam products themselves.
and examines potential methods for reducing these emissions. Options studied in-
clude replacement of CFC- blown products with alternative products not requiring
CFCs, replacement of ozone- depleting CFCs with other chemicals less likely to des-
troy stratospheric ozone, and recovery/recycle of CFCs released during manufac-
turing processes. In the production of rigid cellular foams, CFCs are used as physi-
cal blowing agents to reduce foam density and impart thermal insulating properties.
Such rigid foams include polyurethane, polyisocyanurate. polystyrene, polyethylene,
polypropylene, polyvinyl chloride, and phenolic foams. Uses of these foams include
building insulation, packaging materials, and single- service dinner-ware. Depletion
of stratospheric ozone through action of halocarbons, particularly CFCs^ has been
the subject of extensive, study and wide debate. Although many uncertainties remain,
current scientific evidence strongly suggests that anthropogenic CFCs could contri-
bute to depletion of the stratospheric ozone layer as was first postulated in 1974.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Croup
Pollution
Foam Rubber
Manufacturing
Halohydrocarbons
Ozone
Pollution Control
Stationary Sources
Rigid Foams
Chlorofluorocarbons
Stratospheric Ozone
13B
UJ
05C
07 C
07B
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
199
20. SECURITY CLASS (Ttiispagt)
Unclassified
22. PRICE
EPA Perm 2220-1 (t-73)
-------
NOTICE
This document has been reviewed in accordance with
U.S. Environmental Protection Agency policy and
approved for publication. Mention of trade names
or commercial products does not constitute endorse-
ment or recommendation for use.
11
-------
ABSTRACT
Over the past decade, depletion of stratospheric ozone through the action
of fully-halogenated hydrocarbons (halocarbons) has been the subject of
extensive study and wide debate. Current evidence suggests that such man-made
halocarbons could contribute to depletion of the stratospheric ozone layer,
although many scientific uncertainties remain. A family of halocarbons known
as chlorofluorocarbons (CFCs) are the primary suspects in ozone depletion
theory.
In the production of rigid polymer foams, CFCs are used as physical
blowing agents. Rigid plastic foams include polyurethane, polystyrene,
polyethylene, polypropylene, polyvinyl chloride, and phenolic foams.
This report estimates the total CFC emissions from various types of rigid
foams, with emphasis on polyurethane and polystyrene foams, and suggests
methods for reducing these emissions. A potential method for reducing CFC
emissions would be substitution of CFC-blown rigid foams with non-CFC
containing products. A second method involves replacing ozone depleting CFC
blowing agents with low ozone depleting blowing agents. A final alternative
would be to capture CFCs emitted during the manufacturing process. The
effectiveness of each of these alternatives is discussed.
iii
-------
CONTENTS
Section
1. Project Description 1
Background ...... 1
Project Objectives 4
2. Summary of Results 6
Rigid Polyurethane and Polyisocyanurate Foams 6
Nonpolyurethane Foams 14
Controls Likely to be Adopted by Industry 23
3. Industry and Emission Profile 39
Overview of Rigid Foam Manufacture 39
Rigid Foam Industry Profile 45
CFC Emissions Characteristics 64
Characterization of World CFC Emissions from Rigid Foams . . 72
4i Description of Current Process Technology 74
Rigid Polyurethane Foam Production 74
Rigid Polystyrene Foam Production . . 82
5. Control/Recycle Technologies for CFC-12 in Polystyrene Foam Sheet
Manufacturing 87
Carbon Adsorption and Steam Desorption Systems . 87
Incineration of Plant Exhaust 110
6. Hydrocarbons as Polystyrene Foam Sheet Blowing Agents 112
Plant Equipment and Operation Modifications 113
Control Effectiveness 114
Cost of Control 115
Health and Safety Factors 121
Current Status 121
Economic Factors 123
Barriers to Implementation 124
7. Alternative CFC Blowing Agents 126
Rigid Polyurethane Foam Blowing Agents 127
Polystyrene Foam Blowing Agents 136
Polyolefin and Phenolic Foam Blowing Agents 145
8. Substitutes for Current Rigid Foam Products 153
Alternatives to CFC Blown Rigid Polyurethane Foam Products . 153
Alternatives to CFC Blown Polystyrene Foam Products .... 172
Alternatives to Other CFC Blown Foam Products 180
Preceding page blank
-------
CONTENTS (Continued)
Section Page
9. Additional CFC Control Methods 182
Recovery of CFC-11 Upon Product Disposal 182
Use of Non-CFC, Non-Hydrocarbon Blowing Agents for
Nonpolyurethane Foams ..... 184
REFERENCES 186
FIGURES
Number Page
4-1 Laminated foam boardstock 75
4—2 Foam injection operation 77
4—3 Sprayed-foam operations 79
4-4 Rigid polyur ethane bun stock foam line 81
4-5 Flow diagram of a typical polystyrene foam sheet manufacturing
process 84
5—1 Schematic flow diagram of typical carbon adsorption/
solvent recycle process 89
5-2 Schematic flow diagram for polystyrene foam sheet model plant . . 98
5-3 Proposed CFC-12 carbon adsorption/recovery system for a
polystyrene foam sheet extrusion plant 101
5-4 CFC-12 adsorption on BPL* activated carbon 102
8-1 Typical residential wall construction. Basic wall with
siding (top). Basic wall with brick veneer (bottom) 162
8-2 Insulative contribution of individual wall components 163
8-3 R-values per inch for various materials (at 24°C (75°F) mean
temperature) 164
8-4 Equivalent thicknesses for various materials (at 24°C (75°F)
mean temperature) 167
-------
TABLES
Number Page
2-1 Summary of Alternative Products as CFC Emission Control
Options in Rigid Polyurethane Foam Manufacture 9
2-2 Summary of Low Ozone Depleting CFCs as a CFC-11 Emissions
Control Option in Rigid Polyurethane Foam Manufacture 13
2-3 Summary of Alternative Blowing Agents for CFC-12 Emissions
Control in Polystyrene Foam Sheet Manufacture 16
2-4 Summary of Add-on CFC Emissions Control Options in
Polystyrene Foam Sheet Manufacture 19
2-5 Summary of Alternative Products as CFC Emission Control
Options in Polystyrene Foam Manufacture 20
2-6 Controls Likely to be Adopted for Rigid Polyurethane Foam
Bunstock and Laminated Board 25
2-7 Controls Likely to be Adopted for Rigid Polyurethane Poured
and Sprayed Foams 27
2-8 Controls Likely to be Adopted for Rigid Extruded Polystyrene Foam
Boardstock 32
2-9 Controls Likely to be Adopted for Rigid Extruded Polystyrene
Foam Sheet 33
2-10 Controls Likely to be Adopted for Other Rigid Nonpolyurethane
Foams 35
3-1 Nonpolyurethane Foams and Corresponding CFC Blowing Agents and
Mixtures 46
3-2 Historical and Projected United States Rigid Polyurethane Foam
Production: 1955 - 2015 47
3-3 Major Producers of Rigid Polyurethane Foam Products 48
3-4 Major Suppliers of Polyurethane Liquid Foam Systems 52
3-5 1985 Rigid PU Foam Production and CFC Consumption in the U.S. . . 55
vii
-------
TABLES (Continued)
Number Page
3-6 Polystyrene Foam Sheet, Film, Board, and Block Producers Including
Extruders 56
3-7 1985 Estimated Consumption of CFC Blowing Agents for the
Manufacture of Polystyrene Foam 62
3-8 Estimated CFC Non-Weighted Consumption & Emissions from Rigid
PU Foam Production in the U.S 66
3-9 Estimated CFC-11 and CFC-12 Emissions From Manufacture and
Use of Rigid Polyurethane Foams in the U.S 69
3-10 Estimated Half-Lives of CFC in Rigid Nonpolyurethane Foam ... 68
3-11 Estimated CFC-12 Emissions From Manufacture and Use of Extruded
PS-Foam Boardstock in the U.S 71
4-1 Summary of CFC Emission Sources and Example Distribution in
Polystyrene Foam Manufacturing 85
5-1 CFC Emission Sources in PS-Foam Sheet Manufacture 91
5-2 Model Polystyrene Extruded Foam Sheet Plant Operating Parameters. 97
5-3 Polystyrene/CFC Material Balance 100
5-4 Carbon Adsorption System Design Parameters 104
5-5 Estimated Capital Costs for Equipping a PS-Foam Sheet Extrusion
Plant with a CFC-12 Carbon Adsorption System 106
5-6 Estimated Annual Operating and Maintenance Costs for Equipping
a PS-Foam Sheet Extrusion Plant with a CFC-12 Carbon Adsorption
System 107
6-1 Model Polystyrene Extruded Foam Sheet Plant Operating
Parameters 116
6-2 Estimated Capital Costs for Equipping a PS-Foam Sheet Extrusion
Plant with a Pentane Blowing Agent System 117
6-3 Estimated Operating and Maintenance Costs for Equipping a PS-Foam
Sheet Extrusion Plant with a Pentane Blowing Agent System .... 118
viii
-------
TABLES (Continued)
Number Page
6-4 Estimated Capital Costs for a PS-Foam Sheet Extrusion Plant
with a Carbon Adsorption System for Pentane Recovery 119
6-5 Estimated Operating and Maintenance Costs for Equipping a
PS-Foam Sheet Extrusion Plant with a Pentane Carbon Adsorption
System 120
6-6 Physical Properties of CFC-12 and Hydrocarbon Blowing Agents . . 122
7-1 Evaluation Factors for Substitute Rigid Polyurethane Foam
Blowing Agents 135
7-2 Evaluation Factors for Substitute Polystyrene Foam Blowing
Agents 144
7-3 Evaluation Factors for Substitute Polyolefin Foam Blowing Agents. 151
7-4 Evaluation Factors for Substitute Rigid Phenolic Foam Blowing
Agents 152
8-1 1985 Market Distribution for Polyurethane and Poly-
isocyanurate Insulation Foams 155
8-2 Potential Substitutes for Rigid PU Foam Products 156
8-3 Non-Residential Roofing Insulation Market 158
8-4 Estimated Energy Losses From Using Alternative Insulation in
Industrial and Commercial Roofing 161
8-5 Estimated Relative Material and Energy Costs for Substitute
Sheathings 166
8-6 Contribution to Total Insulation System Made by PU Foams in
Various Applications 169
8-7 Relative Costs of Alternative Refrigerator Insulations 170
8-8 Potential Substitutes for PS-Foam Products 174
8-9 Retail Costs 'for a Variety of Single Service Plates 177
8-10 1985 Market Distribution for Extruded Polystyrene Insulation
Foams 179
-------
SECTION 1
PROJECT DESCRIPTION
BACKGROUND
Over the past decade, depletion of stratospheric ozone through the action
of fully-halogenated hydrocarbons (halocarbons) has been the subject of
extensive study and wide debate. This phenomenon involves a complicated set
of interactions that are driven by ultraviolet radiation and occur within the
upper atmosphere. Not only are the interactions extremely complex, but direct
observations of them are difficult. Current evidence suggests that man-made
halocarbons could contribute to depletion of the stratospheric ozone layer,
although many scientific uncertainties remain.
A family of halocarbons known as chlorofluorocarbons (CFCs) are the
primary suspects in the* ozone depletion theory. Since they are stable, CFCs
have a long life in the atmosphere and are not readily decomposed by the
levels of ultraviolet radiation present in the lower atmosphere. Once a CFC
molecule has been transported into the stratosphere, it can be acted upon by
the higher intensity ultraviolet radiation releasing halogen atoms which
catalyze the breakdown of ozone to diatomic oxygen. Such depletion of the
protective layer of stratospheric ozone would result in increased ultraviolet
radiation to earth which may cause adverse effects including increases in
melanoma cancer, reduce crop yields, photochemical degradation of plastics,
and changes in the global climate.
An important aspect of the ozone depletion problem is the lag time
between the manufacture of CFCs and their ultimate arrival in the upper
atmosphere. During this lag time which lasts from several to hundreds of
years, the CFCs move through a series of reservoirs. The first major
-------
reservoir consists of newly manufactured CFCs being held in storage. Here,
they are retained for a period which is on the order of months. Next may be
a reservoir of CFCs which are "banked" in the end-use product. The retention
time here can be brief, or in products such as rigid polyurethane foams, the
holdup time can last for hundreds of years. Finally, cumulative emissions of
CFCs from all sources have created a lower atmospheric reservoir from which
CFCs continuously diffuse into the upper atmosphere. The significance of this
lag time is that there can be a considerable delay between the release of CFCs
and the occurrence of ozone depletion which they might cause. Therefore, even
if all controllable emissions are reduced promptly, the emissions from
uncontrollable sources will continue for some time into the future.
CFCs are widely used in several industries including rigid foam manufac-
turing. In that industry, CFC-11 (fluorotrichloromethane) and CFC-12
(dichlorodifluoromethane), CFC-113 (trichlorotrifluoroethane), and CFC-114
(dichlorotetrafluoroethane) are used as physical blowing agents to reduce foam
density and impart thermal insulating properties. CFC-11 is the primary
blowing agent for rigid polyurethane and polyisocyanurate foams. The exotherm
from the polymerization reaction causes volatilization of the CFC, and the
vapor is trapped within the cellular matrix of the polymer foam. The cellular
structure provides the foam with its rigidity, and the CFC-11 vapor trapped
within the cells gives these foams their exceptional thermal insulating
properties. For nonpolyurethane foams such as extruded polystyrene (PS) foam,
CFCs are also used as a primary blowing agent. CFC-12 is the predominant
blowing agent used in extruded CFC-blown PS foams. The main function of these
CFCs is to produce numerous small closed cells which reduce the foam's density
while providing good structural strength. The amount of blowing agent in a
given formulation depends on the property specifications of the product.
The CFC-11 in rigid polyurethane and polyisocyanurate foams is character-
ized as being banked, i.e., the CFC gas is sealed in the foam's closed cells
with a half life of approximately 100 years. From these cells, the blowing
agent slowly diffuses over a period of centuries. Therefore, the quantity of
-------
banked CFC-11 grows rapidly with each year's foam production, and essentially
serves as an uncontrollable source of emissions. Historically, some
polyurethane foams have been blown with CFC-12 as an auxiliary to CFC-11.
However, the use of CFC-12 has experienced a substantial decline and current
use is limited primarily to poured polyurethane foams. For the purposes of
this report, it is assumed that CFC-12 also has a half-life in these foams of
about 100 years (47). Similarly, the CFC-12 used to blow polystyrene
boardstock is banked. This blowing agent's estimated half-life in this
product is 40 years, so there is also a steady increase in size of this CFC-12
bank as long as the use of PS boardstock increases. Worldwide data compiled
by the Chemical Manufacturers Association shows that of the nearly 1.2 million
metric tons of CFC-11 used in rigid closed cell foams since the mid-1950s,
about 53 percent is currently banked in the foam. Of the 244 thousand metric
tons of CFC-12 used in closed cell foams, about six percent is currently
banked (1).
Additionally, the CFC-11 and CFC-113 used to blow phenolic foam is also
characterized as being banked. However, since CFCs are essentially insoluble
in phenolic foam, the CFC gas is sealed in the foam's closed cells for the
life of the foam.
Emissions of CFC-12 blowing agent from the extruded polystyrene foam
sheet (as compared to PS foam board) manufacturing process are characterized
as being prompt, i.e., the CFC gas is released during, or soon after, foam
formation. Therefore, in this industry the quantity of CFC-12 emitted
annually essentially equals the amount consumed annually. This contrasts with
the CFC banking which occurs with rigid polyurethane and polystyrene
boardstock foams.
Emissions of CFC from polyolefin (i.e., polyethylene and polypropylene)
and polyvinyl chloride foams are also characterized as being prompt. These
emissions may consist of CFC-11, CFC-12, CFC-114, or a mixture depending on
-------
the foam type and thickness. Thus, like PS foam sheet, the quantity of CFC
emitted annually essentially equals the amount consumed annually.
Chlorofluorocarbon use in the rigid foam industry is increasing in the
United States and worldwide. In 1985 in the US, approximately 43,000 metric
tons of CFC-11 and 7,000 metric tons of CFC-12 were used to manufacture rigid
polyurethane foams. For the same year, the consumption of CFC-12 in poly-
styrene foams was roughly 9,200 metric tons. Additionally in 1985, a total of
approximately 5,000 metric tons of CFCs (comprised of CFC-11, CFC-12, and
CFC-114) were used for polyolefin foams and an additional 1,400 metric tons of
CFCs (comprised of CFC-11 and CFC-113) were used for phenolic foam. It is
estimated that in 1985 the rigid foam industry accounted for 51 percent of
total domestic consumption of CFC-11 and 11 percent of the total domestic
CFC-12 consumption (2).
PROJECT OBJECTIVES
The primary objective of this study was to evaluate technical options to
reduce emissions of CFCs associated with rigid polyurethane and polystyrene
foam processes and products. In this study, the following emission controls
were emphasized: hydrocarbon blowing agents for PS foams, recovery and
recycle of CFC—12 in PS foam manufacturing, and alternatives to CFC blown
rigid foam products. Technical options to reduce CFC emissions from
polyolefin, PVC, and phenolic foam processes and products were also evaluated.
An in-depth evaluation of the factors involved in these CFC controls was
performed. These factors include estimated emissions of CFCs from various
foam production processes and end-uses, and the availability of controls for
these sources. For all control technologies, engineering and economic aspects
have been examined, as well as barriers to control implementation. The
relative effectiveness of each control technique was examined. A profile of
the rigid foam industry including number and location of active firms, process
technology, and projected growth, has also been prepared.
-------
Based on these evaluations, promising controls were identified for the
various foam categories. For each of these, a more detailed evaluation was
performed which addressed the key technical factors, safety, economics,
current status, and control cost effectiveness. The effectiveness of control
consists of both the degree to which emissions can be curtailed, or controlled
CFG emission, and the costs per unit averted.
-------
SECTION ?.
SUMMARY OF RESULTS
In the production of rigid foams. CFCs are used as physical blowing
agents. The action of these blowing agents generates numerous small closed
cells in the foam thereby providing structural strength and low density. In
insulating applications, the CFCs are also desirable due to their good thermal
insulating properties. For rigid polyurethane foams, the most commonly used
blowing agent is CFC-11. For CFC-blown polystyrene foams, the predominate
blowing agent is CFC-12, while mixtures of CFC-11/12/114 are used for
polyolefin foams and mixtures of CFC-11/113 are used for phenolic foam.
RIGID POLYURETHANE AND POLYISOCYANURATE FOAMS
Since their introduction in the early 1940s, rigid polyurethane foams
have experienced tremendous growth in both production and applications. Fire
retardant polyisocyanurate foams which are based on a chemistry similar to
that of polyurethane foams, have played a major part in this growth. Because
of the similarities in chemistry, processing, and product applications, this
report will use the word polyurethane (PU) to refer to both polyurethane and
polyisocyanurate. The superior insulating characteristics of PU foams have
allowed them to be used in a variety of insulating applications ranging from
household appliances to large commercial buildings. In 1985, rigid poly-
urethane foam production in the U.S. reached approximately 336,000 metric
tons. Approximately 90 percent of this production is used as thermal
insulation. The remainder is used in packaging, flotation devices, and a
variety of other applications.
In general, rigid polyurethane foam production can be divided into four
types of processes: laminated foam panels, poured/injected foams, sprayed
foams, and bunstock. Further, the consumption of rigid polyurethane foams can
-------
be broken down into seven application areas. These are: building insulation.
refrigerated appliance insulation, industrial insulation, packaging,
transportation insulation, and other miscellaneous applications.
CFC-11 is the primary blowing agent for rigid polyurethane foam manufac-
ture. A smaller amount of CFC—12 is used particularly in pour—in-place
applications. In 1985, the estimated total U.S. consumption of CFC-11 and
CFC-12 for rigid PU foam manufacture was 43,000 and 7,000 metric tons, respec-
tively.
Rigid polyurethane foams have a very low permeability; therefore, the
CFCs used in their manufacture are trapped and held for a very long period of
time. The half life of CFC-11 in rigid polyurethane foam is estimated to be
in excess of 100 years. This means that with each year's production, a
growing reservoir or bank of CFC-11 is being formed. This bank serves as a
very large and virtually uncontrollable source of CFC emissions. It is
estimated that currently, for U.S. production, tiearly 461,000 metric tons of
CFC-11 and 74,000 metric tons of CFC-12 are banked in rigid polyurethane foam.
Further, if the use of these foams continues to grow as it has in the past,
the quantity of banked CFCs will have tripled to 1.4 million metric tons of
CFC-11 and 228,000 metric tons of CFC-12 by the year 2000.
Because the rigid polyurethane holds the CFCs tightly, the emissions of
CFCs during foam production are low. For 1985, the estimated foam production
emission rates for CFC-11 and CFC-12 for all PU foams were 3,900 and 2,300
metric tons, respectively. The remaining CFC emissions for 1985 come from
in-use emissions from the product. For CFC-11 and CFC-12, these emissions
come from a slowly emitting bank and result in 2,900 and 500 metric tons of
emissions, respectively. Therefore, the 1985 total CFC-11 and CFC-12 emis-
sions for rigid polyurethane foam are 6,800 and 2,800 metric tons, respect-
ively.
-------
Polyurethane Foam Product Substitutes
Because rigid FU manufacturing emissions are relatively small and in-use
emissions occur slowly over an extremely long time period, it is difficult to
effectively control these emissions. However, one option which can provide a'
reduction in future CFC emissions, is to switch to substitute products which
contain either smaller quantities of CFCs or none at all. Table 2-1 summa-
rizes the aspects of various substitutes. A majority of rigid polyurethane
foam is used as insulation for commercial and residential buildings. In this
application, FU foams are found in a wide variety of specific uses and instal-
lation configurations. Because of this, applicability and selection of a
substitute will be dependant upon the particular insulation project. Among
the various properties which are characteristic of rigid FU foams, perhaps the
most important are unequaled insulation efficiency per unit thickness, fire
retardancy, structural rigidity, and ease of installation.
In cases where substitute insulation materials of equivalent thickness
are used for FU foam, the probable result will be higher energy costs. Use of
thicker substitute insulation or alternative construction methods can prevent
increased energy costs, but often only under penalty of higher installation
and material costs. Many states have enacted building codes which specify
minimum insulation efficiencies for the walls, ceilings, and other components
of residential and commercial buildings. Because these standards have been
set with CFC-blown insulation in mind, the specifications cannot always be met
with alternative materials in conventional design and construction.
Additional regulations or specifications concerning fire retardancy and
mechanical strength can preclude the use of substitute materials without
design modifications.
Industrial and commercial roofing comprises nearly 65 percent of the
rigid polyurethane and polyisocyanurate insulation foam market. There are a
number of non-CFC containing materials which are also used in this application
area, but each has limitations with respect to its insulating properties, fire
-------
TABLE 2-1. SUMMARY OF ALTERNATIVE PRODUCTS AS CFG EMISSION CONTROL OPTIONS IN RIGID POLYURETHANE
FOAM MANUFACTURE
= ..
Applications
Industrial Roof/Ceilingt
Industrial Halls:
Commercial Roof /Ceiling:
Commercial Ha' 'si
Commercial Floors!
Alternatives
Fiberglass
Perlite
Expanded PS
Extruded PS
Fiber board
Cellular Glass
Insulating Concrete
Fiberglass
Rock Wool
Perlite
Vermiculite
Insulating Concrete
Fiberglass
Perlite
Expanded PS
Extruded PS
Fiberboard
Cellular Glass
Insulating Concrete
Fiberglass
Rock Wool
Perlite
Vermiculite
Expanded PS
Extruded PS
Fiberboard
Cellular Glass
Fiberglass
Rock Wool
Expanded PS
Extruded PS
CFC X
Emission
Reduction
Potential
100
100
100
40
100
100
100
100
100
100
100
100
100
100
100
40
100
100
100
100
100
100
100
100
40
100
100
100
100
100
40
Relative _
Control
Materials
Savings
Low
High
Low
Medium
Low
Low
High
Low
Medium
Low
High
Low
Medium
Low
High
Low
Costs
Energy
Costs
Low
High
Medium
High
High
High
Low
Medium
High
High
High
Low
High
Medium
LOW
High
High
High
Low
Medium
High
High
Medium
Low
High
High
Low
Medium
Medium
I —..
Control
Applicability
Dependent upon
application
Dependent upon
application.
but generally
good.
Dependent upon
application
Dependent upon
application,
but generally
good.
Dependent upon
application.
Availability
All alternatives
currently
available.
All alternatives
currently
available.
All alternatives
currently
available.
All alternatives
currently
available.
All alternatives
currently
available.
Barriers to
Implementation
Higher energy
costs or
higher
construction
costs for
building.
Higher energy
costs or
higher
construction
costs for
building.
Higher energy
costs or
higher
construction
costs for
building.
Higher energy
costs or
higher
construction
costs for
building.
Higher energy
costs or
higher
construction
costs for
building.
-------
TABLE 2-1 (Continued)
Application*
Residential Roof /Ceiling I
Residential Walla:
Alternative Insulating
Technologies!
Residential Floors:
Refrigeration Insulation:
Packaging
CFC X
Em is 8 ion
Relative
Control Costs
Reduction Materials Energy
Alternatives Potential Savings Costa
Fiberglass
Rock Wool
Cellulose
fiberglass Board
Expanded PS
Extruded PS
Fiberboard
Per lite Board
Cellular Glass
Gypium
Plywood
Foil Faced Laminated Board
Insulating Brick
Thicker Halls/Fiberglass
Batts
Fiberglass
Rock Wool
Foil Faced Laminated Board
EPS
Extruded PS
Fiberglass
EPS Foam Peanuts or Blocks
Plastic Film Bubble Wrap
Wood Shavings
100
100
100
100
100
40
100
too
100
100
100
100
100
100
100
100
100
100
40
100
100
100
100
Low
Low
High
Low
Medium
High
High
Low
Medium
Low
Low
Low
Medium
Medium
Medium
Low
Low
Low
Low
Low
Medium
Medium
Low
Medium
Low
High
High
High
High
High
High
Low
Low
Low
Medium
High
Low
Low
Medium
NA
NA
NA
Control
Applicability
Dependent upon
application.
Dependent upon
application, but
generally good.
Dependent upon
application, but
generally good.
Dependent
upon appli-
cation.
Can be generally
interchanged
Can be generally
interchanged
Availability
All alternatives
currently
available.
All alternatives
currently
available.
Insulation brick
not currently
available in
U.S.. fiber-
glass is
available.
All alternatives
currently
available.
All materials
currently
available
All materials
currently
available
Barriers to
Implementation
Higher energy
costs or
higher
construction
coats for
building.
Higher energy
costs or
higher
construction
costs for
building.
Possible
higher
construction
costs.
Higher energy
costs or
higher
construction
costs for
building.
Higher manu-
facturing
costs
No apparent
barriers
"Control costs are broken into two groups: (1) material savings—because all alternative products have a lower cost than PU products;
(2) energy cost—because all alternative products have a lower insulating efficiency per unit thickness than PU products.
-------
retardancy, mechanical strength or ease of installation which might restrict
its utility as a substitute in a particular installation. Because of the
complexity of the roofing market, choice of an alternative will require
evaluation on a case by case basis. Also, since polyurethane and poly-
isocyanurate foams have the highest insulation value per unit thickness, use
of an equal thickness of the alternative insulations discussed in this report
will cause an approximately 30 to 60 percent increase in energy costs. If
greater thicknesses of an alternative insulation material are used, the added
energy costs can be eliminated; however this can substantially increase the
capital and installation costs.
In residential wall sheathing applications which comprise about 20
percent of the PU insulation market, probably one of the best near term
alternatives to rigid PU foam is expandable polystyrene bead board. This
material is roughly 43 percent less expensive than polyurethane insulation
board and for an equivalent thickness, has about half the insulative capacity.
Using expandable PS bead board, the total wall insulation system would have
about 15 percent higher energy losses. Other substitute materials include:
extruded polystyrene board, fiberglass board, various fiber boards, plywood,
gypsum, and laminated paper board. With the exception of the extruded poly-
styrene board, all of these alternatives offer 100 percent reduction in CFC-11
emissions. Because extruded polystyrene board does use some CFCs, it offers
approximately a 40 percent CFC-11 emission reduction potential.
For insulation of refrigerated appliances and transport vehicles, the
best alternatives are expandable bead polystyrene, extruded polystyrene, and
fiberglass. Again, these alternatives will require thicker walls, or there
will be higher energy losses. An added drawback to these alternatives is
higher manufacturing costs. Polyurethane foams may simply be injected as
liquids into the cavity of a refrigerated appliance, yet the alternatives must
be manually cut and placed into the cabinets.
11
-------
A novel approach to increased energy efficiency and reduce CFC
consumption in a home appliance is the use of a vacuum board. The vacuum
board is a relatively thin product which has e high R-value per inch (30 to
35) created by a vacuum contained in the board. Three different models of
vacuum board have been tested by the U.S. DOE. Of these products, the
Japanese board appears to be the most advanced and has been used commercially.
However, the use of vacuum boards in Japan is decreasing because of problems
with leakage. The vacuum board is composed of fine silica powder (lOOu)
sealed in an evacuated impermeable bag. The bag is adhered to one side of the
wall cavity, and then polyurethane foam is poured around it. One problem with
this technique has been that the CFCs in the foam have bled into the
"impermeable" bags. The result is a substantial loss in the insulating
Duality of the board. In the U.S., General Electric is currently doing
research, development, and testing on their own patented vacuum board
technology.
In packaging applications, the thermal insulating characteristics of
polyurethane foams are usually not important and a variety of alternatives
exist. Included in these are non CFC blown loose-fill expanded polystyrene,
expandable bead polystyrene foam blocks, shredded and wadded paper, cellulose
wadding, die—cut cardboard, and wood shavings. All of these alternatives
offer 100 percent reduction in CFC-11 emissions.
CFC Blowing Agent Substitutes
Use of low ozone depleting CFCs as blowing agents is another possibility
for reducing CFC emissions from rigid polyurethane foams. For rigid
polyurethane foam, the potential alternative CFCs include CFC-123 and
CFC-141b. These were selected on the basis of having chemical and physical
properties similar to those of CFC-11; however, each has potential drawbacks
which are discussed in this report. Table 2-2 gives a summary of this
option. Because these alternative CFCs are not commercially available,
i
implementation of this control technology would be a longer term solution.
12
-------
TABLE 2-2. SUMMARY OF LOW OZONE DEPLETING CFCS AS A CFC-11 EMISSIONS
CONTROL OPTION IN RIGID POLYURETHANE FOAM MANUFACTURE
Factor
Lower Ozone Depleting
CFC Compounds
Percent Emissions Reduction
Control Cost ($/mt)
Control Applicability
Availability and Status
Barriers to Implementation
Nearly 100 percent depending
on substitute.
High or unknown, possibly in-
crease blowing agent cost 5-10
times.
Good, if substitute chemical
is deemed to have acceptable
properties.
Poor, possible candidate CFCs
are not commercially available.
High cost, or not available;
some chemicals toxic or
flammable; long development
time.
13
-------
An additional option exists for reducing CFC-11 use in pour-in-place
appliance insulation foams. These foams which are used in appliances such as
refrigerators, are commonly produced with a blowing agent composed of both
CFC-11 and CO.. The COo is produced when water added to the formulation
mixture reacts with the isocyanate. Many pour-in-place foam systems already
have 10 to 15 percent of the CFC-11 replaced by water-generated CO.. An
additional 15 to 18 percent of the CFC-11 can be replaced using more water.
The drawbacks and limitations of this option are discussed in this report.
NONPOLYURETHANE FOAMS
Nonpolyurethane foams include polystyrene, polyethylene, polypropylene.
polyvinyl chloride and phenolic foams. This report focuses primarily on
extruded polystyrene foams due to the market size and relative consumption and
emissions of CFCs during the manufacture and use of these foams. Since their
introduction, these foams have seen rapid growth as new applications were
discovered, and there is yet a large potential for expansion into new areas.
The other nonpolyurethane foams are not dealt with extensively in this report
because limited information is available owing to limited size of some of the
foam markets and the relative number of producers (i. e.. much of the
information is proprietary).
Rigid Polystyrene Foams
Polystyrene is extruded into both sheet and board profiles. Extruded PS
sheet is a thermoformable material which is used to make a variety of single
service and packaging items such as stock food and produce trays, egg cartons.
hinged carry-out containers, plates, cups, and bowls. Over 80 percent of the
total extruded PS foam made (blown with CFCs or hydrocarbons) is manufactured
as sheets. Extruded PS board is used as an insulation material much in the
same way as foamed polyurethane insulation.
14
-------
In 1985, the total U.S. production of extruded polystyrene boardstock was
nearly 49,000 metric tons. In the same year, the total U.S. production of CFC
blown polystyrene extruded sheet was approximately 104,100 metric tons. The
total U.S. consumption of CFC-12 to form the PS products was 9,200 metric
tons. Because the blowing agent is able to permeate through the foam rela-
tively quickly, the CFC-12 from sheet manufacture is emitted early in the
product's shelf life. On the other hand, because polystyrene board is thick,
the CFCs are retained for a longer period of time resulting in banking of the
CFC-12. The estimated half-life for the CFCs in polystyrene board is 40 years
(5).
Because the CFC half-life in polystyrene board is relatively long, the
same concern with banked CFCs applies to this foam as does apply to rigid
polyurethane foams. However, the amount of CFCs which are banked is much
smaller. It is estimated that currently nearly 27,000 metric tons of CFC-12
are banked in polystyrene foam board. This bank is estimated to roughly
triple to 90,000 metric tons by the year 2000. The emissions from the CFC-12
bank for PS foam will continue to grow as long as the use of PS boardstock
grows.
For the U. S., the 1985 CFC-12 emissions for rigid polystyrene foams were
estimated at 4,300 metric tons. Of this total. 3,700 metric tons were emitted
from PS foam sheet manufacturing and thermoforming, and 600 metric tons were
emitted from the PS extruded board manufacturing process and bank.
Blowing Agent Substitutes—
For polystyrene foam sheet, the use of low ozone depleting blowing agents
can reduce the emission of ozone depleting CFC-12. The use of low ozone
depleting blowing agents includes using non-fully halogenated CFCs, hydrocar-
bons, and inert gases. Table 2-3 summarizes the aspects of various alterna-
tive blowing agents.
15
-------
POLYSTYRENE FOAM SHEET MANUFACTURE
Factor
Pentane
Substitution
Pentane
Substitution With
Carbon Adsorption
Depleting
CFC Compounds
CFC/HC and
CFC/C02 Blends
Percent Emissions 100
Reduction
Control Cost $238/mtf
($/mt)
Control
Applicability
Availability and
Status
Barriers to
Implementation
100
$305/mt'
Good
Good
Excellent* is
currently widely
used
Pentane emissions
may require
add-on controls
for VOC emission
control;
reformulation and
equipment
conversion costs;
increased fire
hazards
Excellent.
widely used
High capital
expense;
ventilation
modification
needed; waste
disposal
92-100 15-30
High or unknown. Low
possibly increase
blowing agent
cost 5-10 times
Good, if
Substitute
chemical has
correct
properties
Poor, possible
candidate CFCs
are not
commercially
available
High cost, or not
available; some
chemicals toxic
or flammable;
long development
time
Good
Good
Reformulation and
conversion cost;
more difficult
process and
quality control
a
Specific control costs based on model plant calculations. Fire insurance costs not included.
-------
One option that offers considerable promise in reducing CFC-12 emissions
in the manufacture of polystyrene sheet is substitution of the CFCs with a
hydrocarbon blowing agent. Currently, hydrocarbons such as n-pentane, iso-
pentane or n-butane are viable candidates for replacing CFC-12 in polystyrene
foam sheet production. These options can eliminate use of CFC-12 in this
application, thereby providing 100 percent reduction in emissions of this
ozone depleting compound. However, the resulting pentane emissions, if not
controlled, may contribute to ground level atmospheric pollution.
When polystyrene foams were first introduced in the mid-1960s, they were
blown almost exclusively with pentane. However, the fire hazards associated
with pentane have caused a gradual conversion to CFC-12 as a blowing agent.
In spite of the trend away from using hydrocarbons, it is possible to make
virtually all thermoformable polystyrene foam sheet using a hydrocarbon such
as pentane as a blowing agent.
"Converting a plant so that it may use pentane rather than CFC-12 as a
blowing agent would require modifications including new tanks, pumps and
associated piping, explosion-proof electrical equipment, a modified
ventilation system, and an improved fire protection system. The capital cost
involved in these modifications could possibly be offset by the fact that
pentane is I/A to 1/5 the cost of CFC-12 and 20 percent less pentane is
required to blow the same quantity of foam.
With pentanes, there may be additional costs associated with add-on
controls to reduce total VOC emissions. Pentane is regulated as a ground
level ozone precursor, and therefore, will require some type of control in
ozone nonattainment areas. Because of its reactivity, ground level ozone is
considered to be a pollutant and will react long before it could travel to the
upper atmosphere. Table 2-3 points out the costs and availability of pentane
with an add-on VOC control device.
17
-------
Use of alternate lower ozone depleting CFCs is also a potential method
for reducing CFC-12 emissions from rigid polystyrene manufacturing. Candidate
substitute CFCs include CFC-22. CFC-124, FC-134a, and CFC-142b. Both CFC-124
and FC-134a are promising as substitutes for CFC-12; however* they are not yet
commercially available. CFC-22 and CFC-142b are available, but they have
physical properties which might make them unsuitable for extruded polystyrene
insulation board. However, they might prove satisfactory as polystyrene foam
sheet blowing agents. Since much polystyrene foam sheet is used for packaging
products which come into contact with food, thorough tozicity testing and FDA
approval would be required for the new blowing agent. Implementation of this
alternative is expected to be an option available in the longer term.
Finally. CO. is used to reduce but not eliminate the use of CFC-12 in PS
foam manufacturing. This technology is currently available and can reduce
emissions by 15 to 25 percent. In addition, blends of CFC and hydrocarbons
can also be used to reduce CFC emissions.
Add-On Controls for CFC Reduction—
Add-on CFC control possibilities are recovery and recycle of CFC-12
through the use of a carbon adsorption system, or destruction of CFCs through
incineration. A carbon adsorption and recovery system would require a sub-
stantial capital investment, but this cost could be partially offset if the
recovered CFC-12 could be reused. An incineration system, on the other hand,
would have generally high operating costs with no potential recovery credit.
Table 2-4 summarizes the important factors concerning these two options.
Polystyrene Foam Product Substitutes—
The only other currently available CFC control technique for CFCs from
polystyrene foam sheet is substitution with products which do not contain
CFCs. Table 2-5 summarizes the aspects of substitution with various non-CFC
containing products. Most polystyrene foam sheet products serve essentially
the same purpose as the materials they have replaced. Indeed, in many appli-
cations, polystyrene foam and its competitors can be found in use
18
-------
TABLE 2-4. SUMMARY OF ADD-ON CFC EMISSIONS CONTROL OPTIONS IN POLYSTYRENE
FOAM SHEET MANUFACTURE
Factor
Carbon Adsorption
With Recycle
Incineration,
Thermal or Catalytic
Percent emission
reduction
40
30-60
Control cost ($/mt)
$ 55/mta and offers a
potential recovery
credit
Very high, no
recovery credit
Control applicability Good
Poor
Availability and
status
Good, established
technology.
Fair, established
technology.
Barriers to
implementation
High capital expense;
ventilation modifi-
cation needed;
waste disposal.
Very high operating
and capital cost.
Specific control costs based on model plant calculations.
19
-------
TABLE 2-5. SUMMARY OF ALTERNATIVE PRODUCTS AS CFC EMISSION CONTROL OPTIONS IN
POLYSTYRENE FOAM MANUFACTURE
Application
Tharnoformed Sheet
Stock Food Tray it
Egg Carton* t
Single Servict Goods:
Paper. Cupa, and Bowl a:
Hinged Containarat
Altarnativaa
Hydrocarbon Blown PS
Solid Plastic Trayi
Plaatic Pil« Wrap
Plaatie Bag*
Coatad Paper Traya
Butchar Papar
Controlled AtBoaphera
Packaging
Hydrocarbon Blown PS
Papar
Hydrocarbon Blown PS
EPS
Papar
Solid Plaatie
Hydrocarbon Blown PS
Paparboard Container*
Solid Plaatie Containara
Papar Wrap*
Foil Wrapa
Plaatic Hrapa
Combination Laminated Wraps
Parcant
Emiaaion
Reduction
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
Control
Coat
Low
Medium
Low
Low
Low
Low
Medium
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Control
Applicability
Excel lent
Excellent
Excellent
Excellent
Excellent
Excellent
Good
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Availability
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Developmental
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Barriara to
Implementation
Coat, aesthetic*
and preferencea
of consumer
Nona
None
Consumer
Preference
Aesthetics
Consumer
Preference
Board Stockt
Insulation Sheathing
-See Polyurethane Insulation
Sheathing Alternatives in
Table 2-1
-------
side-by-side. An example is PS and paper egg cartons which can both be found
in many stores.
Other product substitutes include different types of materials. Perhaps
the best product substitutes for CFC blown polystyrene foam products are
hydrocarbon blown polystyrene foam products. Hydrocarbon blown foam is
virtually identical to CFC blown foam; however, some end-users still request
CFC-blown foam only. For stock food trays, some of the alternatives are solid
plastic trays, plastic film wraps, plastic bags, coated paper trays and
alternative technologies such as controlled atmosphere packaging. For egg
cartons, the best substitute materials are hydrocarbon blown polystyrene foam
and paper fiber. For single service goods, the alternatives include hydrocar-
bon blown polystyrene, expandable bead polystyrene, paper, solid plastic,
paperboard, and various laminated foil and paper products. All of the substi-
tutes for polystyrene foam sheet products provide a 100 percent reduction in
CFC emissions.
Polystyrene Boardstock CFC Control Alternatives—
Since polystyrene board is used as an insulation material, the best
approach to controlling the CFC emissions associated with this product is
substitution with materials which do not contain CFCs. The discussion of
insulation material replacements for polyurethane foams also applies here, and
again, probably one of the best alternatives is expandable polystyrene bead
board. The table (Table 2-1) of PU foam board substitutes can be reviewed for
other alternatives.
Other Nonpolyurethane Foams
Other nonpolyurethane foams include polyolefin (i.e., polyethylene and
polypropylene), polyvinyl chloride, and phenolic foams.
21
-------
Polyolefin Foams—
Folyolefin foams are extruded into two types: plank and sheet. These
foams are used primarily for cushion and protective packaging. In 1985.
approximately 22,000 metric tons (48.5 million pounds) of polyolefin foam were
produced (12). Of this, polyethylene plank accounts for approximately 40
percent (49). In the same year, a total of approximately 5,000 MT (11 million
pounds) of CFCs (a mixture of CFC-11, CFC-12, and/or CFC-114) were used as
blowing agent. Because the blowing agent is able to permeate through the foam
relatively quickly, the CFCs are emitted during manufacture or within a year
thereafter. As such, annual CFC emissions are assumed to equal annual CFC
consumption.
For polyolefin foam, the use of low ozone depleting blowing agents can
reduce the emission of ozone depleting CFCs. However, because of the required
cushioning properties of these foams, the gas pressure within the cells must
remain constant to provide dimensional stability. As such, alternative
blowing agents must escape the product at essentially the same rate as that of
established blowing agents. Potential substitutes include CFC-142b and
CFC-124. However, they have not been tested and are expected to be long term
options at best.
Finally, a wide variety of packaging alternatives such as non-CFC blown
expanded polystyrene, shredded and wadded paper, cellulose wadding, die-cut
cardboard, wood shavings, pre-foamed expanded polystyrene packing blocks and
plastic film bubble wrap can be used as alternatives to polyolefin foams in
some instances. However, protective packaging is a complex and diverse
market. For one time, special packaging or for a delicate packaging
requirement, alternative materials may not be able to provide adequate
protection. This is especially true in applications where polyethylene plank
is used since it represents one of the most cost effective, highest
performance materials used in cushion packaging.
22
-------
Phenolic Foam—
In the past, phenolic foam was used in the United States primarily as a
base material for floral arrangements. However, the introduction of phenolic
foam in thermal insulation applications in 1981 has resulted in an increase in
the production of phenolic foam in recent years. In 1985, approximately
10,000 MT (22 million pounds) of phenolic foam were produced (12). In that
same year, a total of approximately 1,400 MT (3 million pounds) of CFCs
(comprised of CFC-11 and CFC-113) were used as blowing agents. Phenolic foam
currently holds an 8 percent share of the total roofing and sheathing
insulation market (50).
Like PU foam, phenolic foam retains most of the CFCs used as blowing
agent and the emissions of CFCs during foam manufacture are low. In addition,
the foam retains the CFCs for the duration of its useful life.
Since phenolic foam is used as an insulation material, the best approach
to controlling the CFC emissions associated with this product is substitution
with materials which do not contain CFCs. The discussion of insulation
material replacements for polyurethane foams also applies here. Table 2-1 of
PU foam board substitutes can be reviewed for other alternatives.
The use of low ozone depleting CFCs as blowing agents is another
possibility for reducing CFC emission from phenolic foam. The potential
alternatives include CFC-123 and CFC-141b. Because these alternative CFCs are
not commercially available and thus have not been tested, implementation of
this control would be a longer term solution.
CONTROLS LIKELY TO BE ADOPTED BY INDUSTRY
In meeting potential future CFC regulations, the various industry
segments will use a combination of control options. This will depend on the
overall emission reduction potential versus cost, the impact on the foam
industry and end-use markets, and ease of implementation of the control
options. Based on this analysis, the more favorable options have been
23
-------
identified for each application of rigid polyurethane and polystyrene foams
and are presented in Tables 2-6 through 2-9. In addition. Table 2-10 presents
controls likely to be adopted for other nonpolyurethane foams including
polyolefin. polyvinyl chloride, and phenolic foams.
Rigid Polyurethane Foam Bun stock and Laminated Board
Table 2-6 lists control options which industry might adopt in response to
CFC regulations. However, the actual practice of choosing an insulation
material is a complex issue involving a number of considerations such as the
design of the structure to be insulated, requirements of the builder or
customer, construction codes, regional climate, and material availability and
cost.
Since rigid polyurethane insulating foams exist in a competitive building
materials market, any short-term regulation would cause the other insulating
materials to gain a larger share of the market. It is expected that use of
thick fiberglass batts in building walls and some industrial tanks will
replace some of the use of rigid PU foam insulation with little, if any affect
on the R-value of the system. Other insulation materials will also be used in
greater thicknesses (especially in roofing applications) as substitutes for
rigid PU foam. The degree to which these product substitutes displace rigid
PU foam insulation will depend heavily upon the stringency and timing of the
regulation.
Other chemical substitutes will become available as mid- to long-term
control options. It is likely that manufacturers of rigid PU bunstock and
laminated board will prefer use of CFC-123 as a long-term alternative blowing
agent. It is non-flammable, giving it an advantage over CFC-lAlb in building
and industrial insulation applications even though CFC-lAlb may become
available sooner. It is anticipated that foam manufacturers wiTl be able to
produce -a foam with CFC-123, but it will be more expensive and have a slightly
lower insulating ability per unit thickness. If rigid PU foam bunstock and
laminated boardstock are manufactured with this chemical substitute, they will
be less cost competitive with other building materials. Some displacement by
alternative insulation materials would naturally occur.
24
-------
TABLE 2-6. CONTROLS LIKELY TO BE ADOPTED FOR RIGID POLYURETHANE
FOAM BUNSTOCK AND LAMINATED BOARD
Control Availability
Thick Fiberglass Batts/Thick Walls ST
Conventional Stud Spacing
Thick Fiberglass Batts/Thick Walls ST
Wide Stud Spacing
Thick Fiberglass Batts - Industrial ST
Insulation Systems
Other Insulation Materials/ ST
Conventional Thickness
Other Insulation Materials/ ST
Equivalent Insulating Capacity
CFC-123 LT
*ST = Short Term, LT = Long Term
25
-------
Add-on engineering controls are not considered as options likely to be
adopted because of their high cost, low emission reduction potential and
because they may not be useful in a scenario which involves large-scale
replacement by product and chemical substitutes.
Rigid Polyurethane Poured and Sprayed Foams
Table 2-7 lists control options which industry might respond to future
CFC regulation.
Building and Industrial Insulation—
Since rigid polyurethane insulating foams exist in a competitive building
materials market, any short-term regulation would cause the other insulating
materials to gain a larger share of the market. It is expected that use of
thick fiberglass batts on building walls and some industrial tanks will
replace some of the use of rigid FU foam insulation with little, if any,
affect on the R-value of the system. Other insulation materials will also be
used in greater thicknesses especially in roofing applications as substitutes
for rigid FU foam. Rigid FU poured and sprayed foams will probably continue
to be used for special cavity fill or coverage of complex surfaces due to the
lack of available alternatives for these uses.
A short-term control option which may have some limited effectiveness is
using CFC-22 instead of CFC-12 as a frothing agent. Although the use of
CFC-12 as a frothing agent has been declining in recent years special
applications still requiring a frothing agent can reduce use of CFC-12 by
replacement with CFC-22 which has a lower ozone depletion potential. In the
long term, however. FC-134a has been proposed as a better frothing agent
substitute for CFC-12.
Other chemical substitutes will become available as mid- to long-term
control options. It is likely that manufacturers of rigid FU poured and
sprayed foams for building and industrial insulation will prefer use of
26
-------
TABLE 2-7. CONTROLS LIKELY TO BE ADOPTED FOR RIGID POLYURETHANE
POURED AND SPRAYED FOAMS
Control Availability*
Building and Industrial Insulation
Thick Fiberglass Batts/ ST
Thick Walls
Thick Fiberglass Batts/ ST
Industrial Insulating Systems
Alternative Insulating Materials/ ST
Conventional Thickness
Alternative Insulating Materials/ ST
Equivalent Insulating Capacity
CFC-ll/CFC-22 ST
CFC-ll/FC-134a LT
CFC-123 LT
Packaging
Expanded Polystyrene (EPS) Bead
Other Packaging Materials
E20 Only
CFC-123
Refrigerated Appliance Insulation
CFC-11/H20
CFC-ll/CFC-22
CFC-ll/FC-134a
CFC-141b
CFC-123
Refrigerated Transport
CFC-ll/CFC-22
CFC-ll/FC-134a
CFC-141b
CFC-123
ST
ST
ST
LT
ST
ST
LT
LT
LT
ST
LT
LT
*ST = Short Term, MT = Mid Term, LT = Long Term
27
-------
CFC-123 as a long-term alternative blowing agent. It is non-flammable, which
gives it an advantage over CFC-141b in building and industrial insulation
applications, even though CFC-141b might become available sooner. It is
anticipated that foam manufacturers will be able to produce a foam with
CFC-123 but it will be more expensive and have a slightly lower insulating
ability per unit thickness. If rigid PU poured and sprayed foams are
manufactured with this chemical substitute, they will be less cost competitive
with other building materials. Some displacement by alternative insulation
materials would naturally occur.
Packaging—
The packaging market is also a very cost competitive market, hence any
short-term regulation would cause other packaging materials to gain a larger
share of the market. EPS bead can be molded into shapes similar to rigid PU
poured packaging. Other packaging materials such as plastic film bubble wrap
can be used to provide other desirable properties.
Still, rigid PU foam packaging will be desirable for special packaging
uses. Manufacturers will have the option of using less CFC-11 and using more
water in the foam formulation. This causes production of additional CO. which
acts as the substitute blowing agent. In fact, it may be possible to replace
100 percent of the CFC by using enough water (49).
Other chemical substitutes will become available as mid- to long-term
control options. It is possible that manufacturers of rigid PU foam packaging
will use CFC-141b as a blowing agent, since it has potential to become
available earlier than CFC-123. This presupposes, however, that toxicity
testing results show no harmful effects or that they are not a concern to the
application. The fact that the chemical is slightly flammable should not
restrict its use as a packaging material. CFC-141b and CFC-123 are expected
to be more expensive than CFC-11, hence, packaging blown with CFC-141b or
CFC-123 will be less cost competitive with other packaging materials. Some
displacement by alternative packaging materials would naturally occur.
28
-------
Refrigerated Appliance Insulation—
Alternative insulation materials were not considered as viable control
options in this application since a major change to currently available
materials which are less insulating per unit thickness (e.g.. fiberglass
batts) is contrary to the aims of current research. Refrigeration unit
manufacturers would revert to this control approach only if the more
technically favorable alternatives were unavailable.
In the short term, one control option is to use more water in the foam
formulation thereby increasing the production of CO-, to reduce the use of
CFC-11 as a blowing agent for rigid PU poured foam. Since CO has a higher
thermal conductivity than CFC-11, an increase in foam density is required to
regain some of the insulating efficiency lost.
However, emphasis on new materials and designs for refrigeration systems
including higher grade insulation has resulted from more stringent appliance
energy standards set by the federal government. Researchers are already
devising ways to increase the efficiency of refrigeration units in order to
conserve energy. New materials such as vacuum board panels are being
considered, as well as new cabinet designs. It is likely that new materials
or system designs will play an important role in the refrigeration insulation
options of the future, even in the absence of CFC regulation.
Another short-term control option which may have some limited
effectiveness is using CFC-22 instead of CFC-12 as a. frothing agent.
Apparently use of CFC=12 as a frothing agent has been declining in recent
years due to formulation development (49). Special applications still
requiring a frothing agent, however, can reduce use of CFC-12 by replacement
with CFC-22 which has an ozone depletion potential that is lower than that of
CFC-12. In the long term, however, FC-134a has been proposed as a better
frothing agent substitute for CFC-12.
29
-------
Other chemical substitutes will become available as mid- to long-term
control options. These include CFC-123 and CFC-141b. The fact that CFC-141b
is slightly flammable and potentially toxic may restrict it use in this
application. These CFCs are expected to be more expensive than CFC-11;
however, the total cost of the insulation is only a small fraction of the cost
of the refrigeration unit.
Refrigerated Transport—
Alternative insulation materials were not considered as control options
due to loss in volume and weight carrying capacities that transporters would
endure, and because installation techniques of alternative materials will be
laborious and costly. The transportation industry would begin to use
fiberglass batts or other materials instead of rigid PU foam only if very
stringent regulation is imposed immediately.
A short-term control option which may have some limited effectiveness is
the use of CFC-22 instead of CFC-12 as a frothing agent. Although the use of
CFC-12 as a frothing agent has been declining in recent years, special
applications still requiring a frothing agent can reduce the use of CFC-12 by
replacement with CFC-22. In the long term, however, FC—134a has been proposed
as a better frothing agent substitute for CFC-12.
Chemical substitutes which will became available mid- to long-term are
CFC-123 and CFC-141b and may be the best option for this application. It is
expected to be less expensive and should be available sooner than the
nonflammable CFC-123. The flammability of CFC-141b should not be a major
concern in refrigerated transport insulation applications. It is anticipated
that manufacturers would be able to produce a foam with CFC-141b or CFC-123
that has a slightly lower insulating ability and would be about twice the cost
30
-------
of foam blown with CFC-11. Only a slight increase in thickness would be
needed to produce a foam with equivalent insulating capacity, resulting in
very little interior volume loss and increased weight. Again, the increased
cost will be minor compared to the cost of the entire refrigerated transport
unit.
Rigid Polystyrene Foam Boardstock
Table 2-8 lists control options which industry might adopt in response to
future CFC regulation.
Likely short-term control options are product substitutes and alternative
wall/roof construction. Use of other insulation products which do not contain
CFCs is possible because a wide variety of substitutes is currently available
at competitive prices in the market place. However, if such conversions
occur, higher costs may be encountered due to either energy losses or
increased construction costs to prevent additional energy losses.
In the long-term a likely control option is a chemical substitute such as
FC-134a or CFC-141b. These two chemical substitutes were identified as
possible candidates, but current information indicates that there has been
only a limited amount of application testing of the alternatives. Therefore,
it is expected that additional development and testing of the potential
chemical substitute is needed. At present, FC-134a may be the preferred
long-term option (49), since it has been reported that CFC-141b is slightly
flammable.
Rigid Polystyrene Foam Sheet
Table 2-9 lists control options which industry might adopt in response to
future CFC regulation.
31
-------
TABLE 2-8. CONTROLS LIKELY TO BE ADOPTED FOR RIGID EXTRUDED POLYSTYRENE
FOAM BOARDSTOCK
Control Availability*
Thick Fiberglass Batts/Thick Walls
Conventional Stud Spacing ST
Thick Fiberglass Batts/Thick Walls
Wide Stud Spacing ST
Other Insulation Materials with
Equivalent Insulation Capacity ST
Other Insulation Materials with
Conventional Thickness ST
FC-134a LT
*ST = Short Term, LT = Long Term
32
-------
TABLE 2-9. CONTROLS LIKELY TO BE ADOPTED FOR RIGID EXTRUDED POLYSTYRENE
FOAM SHEET
Control Availability*
Substitutes for Egg Cartons ST
Substitutes for Single Service Plates, Cup, etc. ST
Substitutes for Hinged Containers ST
Substitutes for Stock Food Trays ST
Hydrocarbons without Carbon Adsorption ST
Pentane without Carbon Adsorption ST
CFC-124 LT
FC-134a LT
CFC-22 KT
*ST = Short Term, LT = Long Term
33
-------
In the short term, the use of substitute products is the control option
which would most likely occur. There are a large number of potential product
substitutes for foamed polystyrene sheet food packaging such as: paper.
cardboard, plastic film, paper-backed metal foils, and composite wrappings.
All of these materials are currently used in most of the market segments that
use foamed polystyrene sheet. Technical factors such as thermal insulating
value and product protection deserve consideration, but usually the choice for
a particular material depends on aesthetic preference.
For FS foam sheet manufacturers who currently use CFCs, an option which
could be favorable is conversion to substitute blowing agents such as pentane
and other hydrocarbons. It is possible that these chemical substitutes will
be viewed unfavorably by some producers because of concerns about fire
hazards, volatile organic emissions, and foam processability and quality.
In the long term, it is possible that alternate CFC blowing agents will
gain a substantial market share. From a technical standpoint, this will occur
if these CFC substitutes offer comparable ease of processing and foam quality.
Economically, it is probable that these new CFCs will be more expensive than
currently used blowing agents.
Other Nonpolyurethane Foams
Other nonpolyurethane foams include polyolefin (i.e., polyethylene and
polypropylene), polyvinyl chloride, and phenolic foams. Table 2-10 presents
likely control options the industry will adopt for the various foam categories
to meet future CFC regulations.
34
-------
TABLE 2-10. CONTROLS LIKELY TO BE ADOPTED FOR OTHER RIGID NONPOLYURETHANE
FOAMS
Control Availability*
Polyethylene Foam
Alternate Packaging Materials ST
Rubber or Plastic Gaskets ST
Rubber or Plastic Flotation Devices ST
CFC-124 LT
Polypropylene Foam
Carbon Adsorption ST
Alternate Packaging Materials ST
CFC-124 LT
Polyvinyl Chloride Foam
Rubber or Plastic Gaskets ST
Rubber or Plastic Flotation Devices ST
CFC-124 LT
Phenolic Foam
Thick Fiberglass Batts/Thick Walls ST
Conventional Stud Spacing
Thick Fiberglass Batts/Thick Walls ST
Wide Stud Spacing
Other Insulation Materials—
Equivalent Insulation Capacity ST
Other Insulation Materials—
Conventional Thickness ST
CFC-123 LT
*ST = Short Term, LT = Long Term
35
-------
Polyethylene Foam—
Likely short-term control options for polyethylene foam include product
substitutes such as other low density flotation materials, or rubber gaskets.
This is also true for packaging. Many product substitutes are currently
available for packaging material including water-blown polyurethane foam,
expanded polystyrene (EPS) beads, and paper-based cushioning.
In the long-term, likely control options are CFG type chemical
substitutes. Several chemical substitutes were identified as possible
candidates: CFC-124a, CFC-142b, or CFC-22/142b blends. However, there has
been only a limited amount of performance testing. Therefore, it is expected
that further testing of the chemical substitute is needed. Overall economics
may determine if use of a more expensive blowing agent is practicable.
Polypropylene Foam—
Polypropylene foam is a unique CFC application in that a carbon
adsorption system was designed into the first commercial-scale plant for
economic reasons. This system is currently realizing an overall CFC recovery
of greater than 80 percent as a result of the unique processing conditions
(51). Further reduction of CFCs in the short term could be achieved through
the use of product substitutes since several product substitutes are currently
available for packaging material.
In the long-term, likely control options are CFC type chemical
substitutes. Several chemical substitutes were identified as possible
candidates: CFC-124a, CFC-142b, or CFC-22/142b blends. However, there has
been only a limited amount of performance testing. Therefore, it is expected
that further testing of the chemical substitute is needed. Overall economics
may determine if use of a more expensive blowing agent is practicable.
36
-------
Polyvinyl Chloride Foam—
A likely short-term control option for polyvinyl chloride foam is a
product substitute made from rubber or plastics. For both gaskets and
flotation devices PVC foam is a relatively new material that was not available
a few years ago. Product substitutes are currently available for both
applications. Since PVC foam serves a relatively limited, but specialized
market, product substitutes could be readily adopted by consumers.
In the long-term, a likely control option is a CFC-type chemical
substitute, such as CFC-124. Several chemical substitutes were identified as
possible candidates and CFC-124 is felt to be a technically feasible
substitute, based on its physical properties. However, current information
indicates that there has been only a limited amount of application testing
with the alternative CFCs although chemical blowing agents have been used
previously. Since the quality of the foam product depends on the substitute
as a blowing agent, it is expected that testing of a potential substitute is
needed.
Phenolic Foam—
Likely short-term control options for this application are product
substitutes and alternative wall/roof construction. Since phenolic foam
insulation is relatively new and equivalent thermal insulation systems are
available, a large change in the availability or cost of phenolic foam should
not cause technical problems in the building trade.
At least two chemical substitutes, CFC-123 and CFC-141b were identified
as possible long-term options, but current information indicates that there
has been only a limited amount of application testing of the alternatives.
From a technical standpoint, this application is concerned with effects on
37
-------
insulating performance and safety of a potential substitute blowing agent.
Therefore, it is expected that testing of chemical substitutes is needed. At
present, CFC-123 may be the preferred long-term option since it has been
reported that CFC-141b is slightly flammable.
38
-------
SECTION 3
INDUSTRY AND EMISSION PROFILE
OVERVIEW OF RIGID FOAM MANUFACTURE
Rigid foams are used in numerous applications ranging from building
insulation to egg cartons. The majority of rigid foams are polyurethane (PU)
(including polyisocyanurate) and polystyrene (PS). Less prevalent are the
phenolic, polyolefin, and other thermoplastic foams; these are not discussed
in detail in this report. Common to all foams is a cellular structure which
is created by the presence of an expanding gas in the polymerizing mixture or
polymer melt. The expanding gas, or blowing agent, is either the product of a
chemical reaction in the polymerizing mixture, or is an inert substance which
is added to the reaction mixture. This substance can be a gas, or it can be a
liquid which will vaporize to generate a gas. Frequently, in the manufacture
of rigid foams, the blowing agents used are chlorofluorocarbons (CFCs).
Background on Polyurethane and Polyisocyanurate Foam Production
Polyurethane foams are addition polymers produced by the chemical reac-
tion of an isocyanate and a polyol. Similarly, polyisocyanurate foams are
produced from an is ocy amir ate and a polyol. Because of the similarities of
polyisocyanurates and polyurethanes, the term rigid polyurethane (PU) foam
will, for the purposes of this report, refer to both polyisocyanurate and
polyurethane foam.
Ninety percent of rigid polyurethane foam is used as insulation
materials, while the remainder is used as materials for packaging and flota-
tion.
39
-------
The production of rigid polyurethane foams usually involves one of four
processing operations: laminated foam core panel manufacture, poured foam
production, sprayed foam application, or bunstock production. Building
insulation is by far the largest consumption category for these foams,
accounting for 57 percent of the total rigid polyurethane production. By
production method. 90 percent of the total polyurethane foams produced is
divided almost evenly among laminated, poured, and sprayed foams. Bunstock
accounts for the remaining ten percent. The CFC content for polyurethane
foams varies with the production method, but generally falls in the five to
twenty weight percent range. CFC-11 is the most commonly used blowing agent.
However, CFC-12 is also used in addition to CFC-11 to a limited extent for
poured foams. CFC-12 is used for low temperature spraying and for frothing in
pour-in-place applications. The low boiling point of CFC-12 causes the
reacting polymer mixture to expand to a consistency similar to that of shaving
cream. This allows injection of the foam into panels and other closed
containers with a minimum of pressure buildup. Laminated board production
relies on the adhesive characteristics of polyurethane. Laminates are
commonly produced with surface skins of metal, paperboard, fabric, or plastic
film (6). Poured foam technology is used to produce foams inside of an
enclosed area such as a refrigerator housing or a building wall space. Here,
the foam components are mixed and poured as a liquid into a cavity where
foaming subsequently takes place. Sprayed foam technology is similar to that
of poured foam. Here, the liquid foam mixture is sprayed onto the surface to
be insulated such as pipework or a storage tank. Bunstock operations produce
a very large block of foam which may be cut and formed into desired products.
In the early 1940s, rigid polyurethane foams were produced on a small
scale, but by the end of the 1940s, the primary chemicals used to produce
polyurethanes—isocyanates and polyols—became available on an industrial
scale. The discovery of the superior insulating characteristics of these
foams allowed them to be used in a variety of insulation applications
including the lining of refrigerators and freezers, industrial equipment
(tanks and piping), and transportation equipment (tank trucks, railcars.
40
-------
etc.). Since the early 1960s, rigid polyurethane foams have experienced
continuous and rapid growth as a result of several breakthroughs. These
include: 1) the introduction of blowing agents such as CFC-11 and CFC-12;
2) the development of polymeric methylene diphenyl diisocyanate (MDI) which
improved the foam properties and simplified processing; and 3) the development
of surfactants which helped to control cell size, configuration, and uni-
formity.
Increased pressure has been applied to the building materials industry to
manufacture products with superior fire retardancy characteristics. This has
led to the growth in consumption of polyisocyanurate foams* These foams are
closely related to polyurethane foam, but they are more fire retardant. They
are chemically stable up to 150°C (302°F). Isocyanurate rigid foams have
processing limitations that compromise their use as spray and pour-in-place
foams. However, their fast reactivity and high viscosity are ideal for
continuous laminated panel and board production.
The physical structural properties of rigid polyurethane foams are a
function of foam density. CFC blown rigid polyurethane insulation foams
usually have densities ranging between 0.032 and 0.048 g/cc (2 to 3 Ib/cu.
ft.). Approximately 8 to 16 percent fluorocarbon blowing agent is required in
the reactant formulation to produce rigid polyurethane foam in this density
range. In insulation applications, the most important property for rigid
polyurethane foams is the thermal. conductivity (often expressed as the U
factor or the K factor). The U (or K) factor is greatly influenced by the
blowing agent, cell size, cell contents, and foam density (7). Thermal
2
conductivity is expressed in units of W/m-K (Btu-in/hr-ft -°F). In the
construction industry, insulation materials are frequently characterized by
their R-value. The R-value expresses the thermal resistivity or insulating
efficiency of a material. A large R-value indicates a good insulating
ability, and polyurethane foams are among the best insulators with an R-value
of 7.2/inch. This value is simply the inverse of the thermal conductivity
41
-------
value (U-factor or K-factor); therefore, the units expressing the R-value are
m-K/W (hr-f t2°F/Btu-in).
Background on Nonpolyurethane Foam Production
There are several nonpolyurethane rigid foams which are blown with CFC
blowing agents. The most important types from the standpoint of CFC emissions
have been the polystyrene, polyolefin. phenolic and FVC foams. A common
feature of all these foams is that new uses for them are continuously being
discovered. There is yet a large potential for expansion of these
nonpolyurethane foams into new product areas. Also, many of the product areas
that have been recently developed have not fully penetrated the market. For
these reasons, growth in the use of CFC-12 and the other fluorocarbon blowing
agents is expected for manufacturing of nonpolyurethane foams.
The qualities which have made these foams superior to the products which
they have replaced include:
• water-resistance,
• thermal insulation,
• low density,
• shock resistance,
• noise resistance,
• static electricity resistance, and
• competitive cost.
42
-------
Non-polyurethane foams of primary interest in this report are polystyrene
foams. These foams are produced by an extrusion process. In this process,
polystyrene resin is melted in an extruder, and a CFC or hydrocarbon blowing
agent is injected into this polymer melt. The blowing agent dissolves into
the molten polymer, and when the melt leaves the extruder, the blowing agent
flashes causing the plastic to foam. The extruder die configuration
determines the shape of the foam. For foam sheet production, the die is
annular, and the resulting tube of foam is slit to form two sheets.
Polystyrene foam board, however, is simply extruded through a die with a
straight slit. Typically polystyrene foams are produced with initial blowing
agent contents ranging from five to twenty percent by weight. In PS foam
sheet, the CFC content typically ranges between 5 and 10 weight percent. The
most commonly used blowing agents are hydrocarbons and CFC-12. Polystyrene
sheet, which is used to manufacture packaging items such as meat trays,
carry-out food trays, and egg cartons, is generally blown to a density of
0.048 to 0.16 g/cc (3 to 10 lb/ft3) (8).
Polyolefin and PVC foams are also produced by an extrusion process
similar to that used for polystyrene foam. The most commonly used blowing
agents are CFC-11, CFC-12, CFC-114. or a mixture. These foams are produced
with initial blowing agent concentrations ranging from approximately 15 to 20
percent by weight for polyethylene and PVC foams to as much as 50 percent for
•3
polypropylene foams. Densities of about 0.016 to 0.14 g/cc (1 to 9 lb/ft )
are typical of polyolefin foams which are used for cushioning and wrapping
(9).
In addition, phenolic resin foams are produced by a process similar to
that used in the production of laminated FU foam. The blowing agent consists
of CFC-11. CFC-114, or a mixture. Initial blowing agent concentrations range
from 10 to 15 percent by weight depending on the CFC used. Like polyurethane
foams, phenolic foams are used in insulating applications since they have an
R-value of 8.3 per inch.
43
-------
Blowing Agents
The cellular structure of rigid plastic foams is produced by the action
of a blowing agent. There are both chemical and physical blowing agents.
Chemical blowing agents undergo a chemical reaction liberating a gas causing
the polymer to foam. Physical blowing agents, which do not react chemically,
include compressed gases and volatile liquids. Gaseous blowing agents, which
are injected into the polymerizing mixture or the polymer melt, include
nitrogen and carbon dioxide. Liquid blowing agents include CFCs, chlorinated
hydrocarbons, and aliphatic hydrocarbons. These are also injected into the
polymerizing mixture or the polymer melt. Liquid blowing agents used in the
manufacture of rigid foams are available as polyol blends supplied by the
chemical suppliers or are available as a commodity chemical for blending with
the other chemicals at the point of manufacture of the foam.
Polyurethane and polyisocyanurate insulation foams are generated through
the action of a physical blowing agent (CFC-11). Some processes also use
CFC-12 as a supplementary blowing agent, but its use is declining. Foaming
occurs when the heat of the polymerization reaction vaporizes the CFC-11.
The use of a CFC blowing agent generates a cellular structure in the polymer-
izing liquid re act ant mixture. In rigid PU foams, the extensive cross-linking
between the polymer chains essentially freezes this cellular structure,
trapping the blowing agent inside. The closed cells give the foam a rigid,
yet light-weight structure, and the CFCs trapped in the numerous tiny closed
cells provide superior insulating properties.
Historically, many of the extruded polystyrene foam products have been
blown with hydrocarbons such as n-pentane and isopentane, and to a lesser
extent, butane. A variety of CFCs have been used either alone as the primary
blowing agent, or in a mixture with other CFCs or pentanes. Besides n-pentane
and isopentane, CFC-12 is the most commonly used blowing agent for the
nonpolyurethane foams. Additionally, gases such as carbon dioxide are often
used in conjunction with hydrocarbons and CFCs. Smaller quantities of CFC-11,
44
-------
CFC-11A, CFC-113. and CFC-115 are also used (5). Table 3-1 lists the various
foam products and the types of blowing agents which are used to manufacture
them.
RIGID FOAM INDUSTRY PROFILE
Polyurethane Foams
In 1985, rigid polyurethane foam production in the U.S. reached
approximately 336 thousand metric tons (741 million pounds) (3). That
represents an average increase of 7.5 percent per year since 1975 when the
estimated production was 154 to 174 thousand metric tons (340 to 383 million
pounds) (10). Table 3-2 shows the historical and projected production for
rigid polyurethane foam in the U.S. Approximately 90% of all rigid
polyurethane foam is used as thermal insulation (11). The primary producers
of rigid polyurethane foams include Celotex, Rmax Inc.. Apache Building
Products Co., Atlas Roofing. Manville Corporation and Thermal Systems
Incorporated. There are at least 28 major suppliers of polyurethane
spray/pour systems. The largest of these are Olin, Brin-Mont Chemicals. Inc..
General Latex. Reichold. Isocyanate Products. Inc.. and Stepan. Tables 3-3
and 3-4 list the major producers of polyurethane foam and liquid foam systems,
respectively.
In general, rigid polyurethane foam production can be divided into four
types of processes: laminated foam core panel, poured/injected foams, sprayed
foams, and bunstock. The typical CFC-11 content in the chemical formulation
for bunstock and laminated foam is 14 percent, but it is 12 percent for poured
or sprayed systems. CFC-12 is used in conjunction with CFC-11 for poured and
sprayed systems, and its typical formulation content is 5 percent and 1
percent, respectively.
The consumption of rigid polyurethane foam can be broken down into
roughly seven applications areas. These include: building insulation, home
45
-------
TABLE 3-1. NONPOLYURETBANE FOAMS AND CORRESPONDING CFC BLOWING
AGENTS AND MIXTURES
Foam Type
Blowing Agent
Polystyrene
Polyethylene
Polypropylene
Phenolics
Polyvinylchloride
Pentane
Butane
CFC-11
CFC-12
CFC-12
CFC-114
CFC-115
CFC-11
CFC-114
CFC-11
CFC-113
CFC-11
CFC-12
Source: (5)
46
-------
TABLE 3-2. HISTORICAL AND PROJECTED UNITED STATES RIGID POLYURETHANE
FOAM PRODUCTION: 1955 - 2015
Year
1955
1960
1965
1970
1975
1980
1985
1990*
1995
2000
2005
2010
2015
(1000 metric
0
5
41
95
154
244
336
476
596
748
879
1034
1216
Rigid PU Foam Production
ton/year) (10 Ibs/yr)
0
10
90
210
340
550
741
1049
1314
1649
1938
2280
2680
^Projected values obtained from summing the medium growth projected figures of
each rigid urethane foam category.
Sources: (2,3)
47
-------
TABLE 3-3. MAJOR PRODUCERS OF RIGID POLYURETHANE FOAM PRODUCTS
Company
Plant Location
Product
RIGID BUN, BOARD. AND LAMINATES
American Western
Atlas Roofing
The Celotez Corporation
Building Productions Div.
Carpenter Insulation
Dyplast
Elliott Co. of Indianapolis. Inc.
Elfoam Ufetbane Division
General Plastic
Homasote Company
Manville Building Materials Corp.
NRG Barriers, Inc.
Polymer Building Systems, Inc.
Rmaz, Inc.
Fontana, CA
Mesa. KL
Camp Hill. PA
LaGrange, GA
Moline. IL
Belvedere, IL
Linden. NJ
Jackson, MS
Conyers, GA
Charleston. IL
Elizabethtown. KY
Pennsauken, NJ
Texarkana, AR
Trace, CA
Elkhart, IN
Temple, TX
Miami, FL
Anderson, SC
Indianap olis, IN
Tacoma. WA
Trenton, NJ
Rockdale, IL
Jamesburg. NJ
Sanford, ME
Hazleton, PA
Riverside, CA
Greenville. SC
Reno. NV
Richardson. TX
Laminates
Laminates
Laminates
Laminates
Bunstock
Bunstock
Laminate
Bunstock
Bunstock
Laminates
Laminates
Laminates
Laminates
Laminates
(Continued)
48
-------
TABLE 3-3 (Continued)
Company
Plant Location
Product
Resco (AM. West.)
Temple-East ex. Inc.
Thermal Systems
The Dow Chemical Co.
Wintec
Admiral
Amana
General Electric
Sanyo
Whirlpool
White
Consolidated
Denver, CO
Mesa, AZ
Diboll, TX
Salt Lake City, UT
Denver, CO
Covington, KY
Dallas, TX
Jacksonville, FL
Springfield, MA
Columbus, OH
La Porte, TX
Bremen, IN
Gallesburg. IL
Williston, SC
Chesapeake, VA
Amana, IA
Decatur, AL
Louisville, KY
Bloomington, IN
Cicero, IL
San Diego, CA
Ft. Smith, AR
Evansville, IL
St. Cloud, MN
Laminates
Laminates
Laminates
Bunst ock
Laminates
Refrig.
Freezers
Refrig.
Refrig./
Freezers
Refrig.
Refrig.
Refrig./
Freezers
Freezers
(Continued)
-------
TABLE 3-3 (Continued)
Company
Plant Location
Cal-Style Furniture Mfg. Co.
Cosco Home Products
Craddock Finishing Corp*
Decor Originals
Jasper Corporation
Paeco Industries. Inc.
Prestige Furniture Co.
Thomasville Furniture Industries
FLOTATION
Emerson & Cuming
Faron Molding Division
OMC Stern Drive
Compton, CA
Columbus, IN
Evansville. IN
Conover, NC
Jasper. IN
Toms River. NJ
Newton, NC
Thomasville, NC
Canton, MA
Brooklyn, NY
Waukegan, IL
Product
SMALL INSULATED CHESTS. COOLERS. AND BOTTLES
Aladdin Industries Nashville, TN
The Coleman Co.. Inc. Wichita, KS
Gott Corporation Winfield, KS
Headway Chemical Co. New York, NY
King— Seeley Thermos Co. Macomb, IL
CHAIR SHELLS. FURNITURE. AND HIGH DENSITY RIGID PARTS
(Continued)
50
-------
TABLE 3-3 (Continued)
Company
Plant Location
Product
Peterson Brothers Boat Works
Robinson Industries. Inc.
Samson Ocean Systems, Inc.
TRANSPORTATION
ACF Industries, Inc.
F/G Products. Inc.
Fruehauf Corporation
Fruit Growers Express Co.
Kentucky Manufacturing
Timpte, Inc.
PACKAGING
Acer Industries. Inc.
Airtex Industries, Inc.
Leggett & Platt. Inc.
Sealed Air Corporation
Perry Chemical & Mfg. Co.
Strux Corporation
Voplex Corporation
Shell Lake. WI
Coleman, MI
Waltham. MA
Milton, PA
Rice Lake, WI
Detroit. MI
Alexandria, VA
Louisville, KY
Denver, CO
Toroson, MD
Minneapolis, MN
High Point. NC
Danbury, CT
Lafayette, IN
Lindenhurst, NY
Rochester, NY
Source: (12)
51
-------
TABLE 3-4. MAJOR SUPPLIERS OF POLYURETHANE LIQUID FOAM SYSTEMS
Company
Plant Location
BASF Wyandotte Corporation
Brin-Mont Chemicals, Inc.
Gallery Chemical Co.
Chemetics Systems, Inc.
Cook Paint & Varnish Co.
E. R. Carpenter Company, Inc.
Flexible Products Company
Foam Enterprises
Foamseal Inc.
Freeman Chemical Company
Frostee Foam
General Latex and Chemical Corporation
Insta-Foam Products, Inc.
Isocyanate Products, Inc.
Marchem Corporation
Mobay Chemical Corporation
North Carolina Foam Industries. Inc.
01in Corporation
Troy, MI
Greensboro, NC
Riverside, CA
Gallery.PA
Compton. CA
Kansas City. MO
Richmond, VA
Marietta, GA
Minneapolis. MN
Oxford, MI
Port Washington, WI
Antioch, IL
Ashland. OH
Billerica, MA
Cucamonga, CA
Charlotte. NC
Dalton, GA
Joliet. IL
New Castle. DE
Maryland Heights, MO
New Martinsville. WV
Mt. Airy. NC
Benicia, CA
Brook Park, OH
(Continued)
52
-------
TABLE 3-4 (Continued)
Company
Plant Location
PPG Industries
Polyblends, Inc.
Polymer Chemical Corporation
Polymer Development Laboratories. Inc.
Polythane Systems, Inc.
Reichhold Chemicals. Inc.
Renosol Corporation
H.H. Robertson Co.
Freeman Chemical Corporation, subsidiary
Stepan Chemical Company
Industrial Chemical Division
The Dow Chemical Company
Springdale. PA
Livonia, MI
Santa Fe Springs. CA
Huntington Beach. CA
Newburgh. NY
Spring. TX
Azusa. CA
Carteret. NJ
Ferndale. MI
Tacoma. WA
Ann Arbor. MI
Burlington, IA
Chatham, 7A
Saukville, WI
Millsdale, IL
Columbus. OH
Houston, TX
Source: (12}
53
-------
and commercial refrigeration insulation, industrial insulation, packaging.
transportation insulation, and other applications. Table 3-5 shows the
application areas and CFC consumption for 1985.
Building construction insulation is the largest market for rigid
polyurethane foams. This insulation is primarily board and laminated board
products for insulating roofs, walls, and doors in residential, commercial.
and industrial buildings. But as flame retardant properties have improved,
construction applications for rigid foam have broadened. Rigid polyurethane
foam also finds wide use in commercial and household refrigeration
applications. This market uses mostly liquid foam systems for pour-in-place
applications. Consumption of rigid foam in the transportation area is mainly
for insulation of trucks and railroad tank and freight cars. A smaller amount
is used for sprayed insulation of industrial storage tanks, pipes and ducts.
Additional uses include insulation for travel trailers and motor homes.
Packaging applications of rigid foam include foamed-in-place packaging for
industrial equipment or scientific instruments. Rigid foams are also used as
marine flotation devices and consumer items such as portable coolers (6).
The consumption of rigid polyurethane foams in each of these areas is
given as follows. In 1985, the production of insulation for buildings (191
thousand metric tons) accounted for nearly 57 percent of the total rigid
polyurethane foam produced. Refrigeration insulation, the second largest user
of rigid polyurethane foams, accounted for only 16 percent of total
production. The remaining insulation categories, industrial and
transportation, each consumed roughly nine percent of total production. The
remaining rigid polyurethane foam consumption areas are packaging, and others
such as marine flotation. Packaging used about six percent of the total
production. The remaining one percent of rigid polyurethane foam production
went into various applications such as flotation.
54
-------
TABLE 3-5. 1985 RIGID PU FOAM PRODUCTION AND CFC CONSUMPTION IN THE U.S.
(1000 mt)
en
Ul
Building Insulation
Refrigeration Insulation
Transportation Insulation
Industrial Insulation
Packaging
Other
Total
1985
Rigid PU
Production
191
54
29
27
20
15
336
Estimated Production by Each
Bunstock
19.1
0.0
0.0
1.4
0.0
3.6
24.0
Laminated
91.4
0.0
0.0
0.0
0.0
3.6
95.1
Poured
19.1
54.4
19.8
3.0
20.0
3.6
119.8
Method
Sprayed
61.0
0.0
9.7
22.9
0.0
3.6
97.2
Total
CFC Consumption
CFC-11
25.1
6.5
3.5
3.3
2.4
1.9
42.7
CFC-12
1.6
2.7
1.1
0.4
1.0
0.2
7.0
Sources: (3,10.13).
-------
TABLE 3-6. POLYSTYRENE FOAM SHEET, FILM. BOARD AND BLOCK PRODUCERS INCLUDING
EXTRUDERS
Company
Plant Location
Airlite Plastics Co.
Albany International
Alcoa Building Products, Inc.
Alsco Arco Building Products
American Excelsior Company
Amoco
Amotex Plastics
Amxco, Inc.
Atlas Industries
Bird. Inc., Vinyl Products Group
Burton Packaging Co., Inc.
Cellar Corporation
Commodore Plastics
Creative Industries
Crystal X Corporation
Dart Container Corporation
Denver Plastics, Inc.
Dipak Mfg. Co., Inc.
Dixie/Marathon
Omaha, KB
Agawam, MA
Pittsburgh, PA
Akron. OH
Arlington, TX
Chippawa, Falls, WI
Beech Island, SC
Lamirada, CA
Winchester. VA
Nashville. TN
Arlington, TX
Ayer, MA
Bardstown, KY
Maspeth, NY
Reedsburg, WI
Holcomb. NY
Chicago, IL
Darby, PA
Mason, MI
Leola, PA
Horse Cave, KY
Lavonia, GA
Plant City, FL
Waxahachie, TX
Corona, CA
Tumwater, WA
Aurora, IL
Lodi, CA
Hudson. CO
Westport, NY
Baltimore, MD
St. Louis. MO
(Continued)
56
-------
TABLE 3-6 (Continued)
Company
Plant Location
The Dow Chemical Co., U.S.A.
Drew Foam Companies* Inc.
Dyrelite Corporation
EFP Corporation
Erie Foam Products, Inc.
FPI
Falcon Mfg, Inc.
Foamade Industries
Foam Fabricators, Inc.
Foam Holders and Specialties
Free-Flow Packaging Corp.
Frostee Foam, Inc.
Genpak
The Oilman Brothers Co.
Glendale Plastic^
Gotham Chicago Corp.
W.R. Grace & Co.
Midland. MI
Allyn's Poinyt, CT
Magnolia, AH
Torranee, CA
Hanging Rock, OH
Joilet, IL
Seattle. WA
Pevely, MO
Carte ret, NJ
Monticello, AR
New Bedford. MA
Elkhart, IN
Erie, PA
Vicksburg, MS
Byron Center, MI
Auburn Hills, MI
St. Louis, MO
Melrose Park, IL
New Albany, IN
Compton, CA
El Dorado Springs, MO
Erie. PA
Bloomsburg, PA
Cerritos, CA
Redwood City, CA
Antioch, IL
Montgomery. AL
Longview. TX
Los Angeles. CA
Middletown, NY
Manchaug, MA
Oilman. CT
Ludlow. MA
Chicago. IL .
Reading. PA
Indianapolis, IN
(Continued)
57
-------
TABLE 3-6 (Continued)
Company
Plant Location
Handi-Kup Co.
Holland Industries. Inc.
Huntsman Container
Hydra-Matic Packing Co.. Inc.
Kalamazoo Plastics
Keyes Fibre/Dolco
Lifoam
The Lin Mfg. Co.
Linpac (Florida Container)
MacDonald Plastics
Manchaug Corporation
Mars Cup Company. Inc.
Master Containers, Inc.
Mobil Chemical Co.
Monsanto Company
Morval-Durofoam Limited
Nyman
Olsonite Corporation
Owens-Illinois
Pac-Lite Products, Inc.
Pelafoam, Inc.
Pioneer Plastics
Plasteel Corp.
Plastica Company, Inc.
Corte Madera. CA
Gilman, IA
Bethayres. FA
Kalamazoo, MI
Decatur, IN
Lawrenceville. GA
Pico Rivera, CA
Wenatchee, WA
Dallas, TX
Baltimore. MD
Clinton, OK
Scabring, FL
Wilson, NC
New Baltimore. MI
Manchaug, MA
Huntington Station, NY
Mulberry, FL
Canandaigua, NY
Covington, GA
Frankfurt, IL
Temple. TX
Bakersfield, CA
St. Louis, MO
Kitchener, Ontario,
Canada
East Providence, RI
Detroit, MI
Toledo, OH
Marine City, MI
Richmond, CA
Bedford, IL
Inkster, MI
Hatfield, PA
(Continued)
58
-------
TABLE 3-6 (Continued)
Company
Plant Location
The Flastifoam Corp.
Plasti-Kraft Corp.
Plastilite Corp.
Plastronic Packaging Corporation
Poly Foam, Inc.
Polyfoam Packers, Corp.
Poly Molding Corp.
Preferred Plastics, Inc.
Radva Plastics Corporation
Rector Insulations
SF Products, Inc.
Shelmark Industries, Inc.
Solo Cup
Snow Foam Products, Inc.
Sonoco Products Co.
M.H. Stallman Co.
Sweetheart Plastics, Inc.
Tekni-Plez
Tempo Plastic Co., Inc.
Tex Styrene
Thompson Industries
Toyad Corporation
Rockville, CT
Ozona, FL
Omaha. NB
Stevensville, MI
Sparta, WI
St. Charles, IL
El Paso, TX
Grand Prairie, TX
Minneapolis, MN
Lester Prairie, MN
Wheeling, IL
Haskell, NJ
Putnam, CT
Norristown, PA
Mt. Vernon, NY
Memphis, TN
North Kansas City, MO
Jackson, MS
Columbus, OH
El Monte, CA
Hartsville, SC
Providence, RI
Wilmington, MA
Owings Mills, MD
Chicago, IL
Conyers, GA
Dallas, TX
Los Angeles, CA
Burbank, CA
New Brighton, MN
Phoeniz, AZ
Latrobe, PA
(Continued)
59
-------
TABLE 3-6 (Continued)
Company
Plant Location
Tuscarora Plastics. Inc.
UC Industries. Inc.
U.S. Mineral Products Co.
Western Foampak
Wilshire Foam Products. Inc.
New Brighton, PA
Parsippany. NJ
Tallmage, OH
Rockford, IL
Stanhope. NJ
Oelwein. IA
Greensboro. NC
Malverne. AR
Fresno. CA
Yakima. WA
Carson. CA
Source: (12)
60
-------
Nonpolyurethane Foams
Nonpolyurethane extruded foam products include polystyrene sheet and
film, polystyrene boardstock, polyethylene plank and sheet, polypropylene foam
sheet, and FVC foam. Nonpolyurethane foams also include phenolic resin foams.
Polystyrene sheet is normally thermoformed into common food packaging
items such as egg cartons, meat and produce trays, and fast-food containers.
Polystyrene foam sheet with laminated faces has also been used as a corrugated
cardboard substitute for poster boards used in the graphic arts industry.
Polystyrene film has a non-slip surface which is useful for wrapping material
and food tray lining. Polystyrene foam boardstock, especially when foamed
with chlorofluorocarbon blowing agents, is used as a construction insulation
material (14).
In their 1980 report, Rand cited a publication which listed 105 producers
of polystyrene sheet, film and block (13). Three companies produce a majority
of the polystyrene foam manufactured in the United States. These are Mobil
Chemical Company, Amoco, and W.R. Grace Formpac Division. Table 3-6 lists the
major polystyrene foam manufacturers. In the past year, the 13 largest
PS—foam producing companies have installed as many as 75 new PS-foam lines to
meet increasing demands. Sources have indicated that at least 70 to 75
percent of the PS foam produced is made using non-CFC blowing agents (18,23).
The top three producers (Mobil, Grace, and Amoco) generate an estimated 70 to
90 percent of all PS foams—using primarily hydrocarbon blowing agents (23).
However, data from Rand indicates that the fraction of PS foam sheet blown
with pentane decreased rapidly in the 1970s from 45 to 50 percent in 1973 to
about 35 percent in 1977 (13). For purposes of this report. Radian is using
70 percent as the current fraction of PS foam sheet produced with hydrocar-
bons. Among the list of major foam producers who use CFC blowing agents are
Mobil Chemical Co., Huntsman Container Corporation, W.R. Grace Co., Dow
Chemical U.S.A., and Owens-Illinois. Table 3-7 shows estimates of total CFC
blowing agent consumption derived from sales data for polystyrene foams (3,9).
61
-------
TABLE 3-7. 1985 ESTIMATED CONSUMPTION OF CFC BLOWING AGENTS FOR THE
MANUFACTURE OF POLYSTYRENE FOAM (1.000 mt)
Boardstock
Sheet
Stock Food Trays
Egg Cartons
Single Service
Plates, Cups, etc.
Hinged Containers
Other Foam Sheet
Total Sheet
Totals
Total
Product
49.1
77.1
36.3
53.9
28.6
12.2
208.2
257.3
% of
Product
Blown
With
CFCs
100%
50%
50%
50%
50%
50%
Product
Using
CFCs
49.1
38.6
18.2
27.0
14.3
6.1
104.1
153.2
Foam
Formulation
% CFC
Content
6%
6%
6%
6%
6%
6%
Estimated
CFC-12
Consumed
2.95
2.31
1.09
1.62
0.86
0.37
6.25
9.20
Source: (3,23)
62
-------
Of all the rigid nonpolyurethane foam products, polystyrene foam sheet
products consume the largest quantity of CFC blowing agents. The manufacture
of these products (i.e., the food trays, egg cartons and single service
products) required approximately 3,800 metric tons (8.3 million pounds) of
CFCs in 1985. Extruded polystyrene boardstock consumed roughly 3.000 metric
tons of CFC blowing agents in 1985.
Polyolefin foams can be broken down into two types: plank and sheet. In
1985. approximately 22,000 metric tons (48.5 million pounds) of polyolefin
foam were produced (12). Of this, polyethylene plank accounts for
approximately 40 percent (49). Plank refers to foam 2.5 (1 inch) thick up to
10.1 cm (4 inches) thick. The end uses of plank consist of cushion packaging,
70 percent; construction, 6 percent; sports and leisure, 12 percent; and
returnable dunnage, 12 percent (49). A significant end use of PE plank is the
military, which accounts for approximately 30 percent of cushion packaging.
This is due primarily to the multiple drop protection and high load bearing
ability PE foam offers. The primary manufacturers are: The Dow Chemical
Company, Sentinel Foam Products, and Valcour, Incorporated. These companies
produce about 80 percent of PE plank.
Polyethylene and polypropylene foam sheet account for the remaining 60
percent of the polyolefin foam market (49). Foam sheet is normally 1.3 cm
(1/2 inch) thick or less with most material being 0.3 cm (1/8 inch) or less.
Approximately 99 percent of polyolefin foam sheet is used for surface
production/packaging with the remaining 1 percent for sports and leisure
applications (49). The primary manufacturers of PE sheet are: Sealed Air
Corporation, Sentinel Foam Products, Richter Manufacturing Corporation, and
Valcour,Incorporated. These companies produce about 80 percent of PE sheet.
Ametek Incorporated is the sole producer of PP foam sheet.
In the past, phenolic foam was used in the United States primarily as a
base material for floral arrangements. However, the introduction of phenolic
foam in thermal insulation applications several years ago, especially
63
-------
following the development of closed-cell phenolic foam in 1981 by Koppers
Company has results in an increase in the production of phenolic foam in
recent years. Koppers Company has a patented process for producing
closed-cell phenolic foam insulation.
Building construction insulation accounts for the majority of the
phenolic foam market. This arises since closed-cell phenolic foam provides
hetter insulating value than many other materials with an R-value of 8.3 per
inch (50). In addition, phenolic foam maintains its R-value over the entire
life of the foam (50). Application of phenolic foam include frame wall
sheathing and under-roof insulation. In 1985, approximately 10,000 metric
tons (22 million pounds) of phenolic foam were produced (12). Of this,
approximately 60 percent was used as roofing insulation and the remaining 40
percent as sheathing (12).
Finally, polyvinyl chloride foam is used in a variety of applications
including: gasket and sealing materials, athletic padding, flotation devices,
and pipe insulation. Greater durability, ease of use, and lower cost have
resulted in the replacement of rubber with PVC foam in many sealant and gasket
applications. Moisture resistance and low density also make PVC foam suitable
for use in flotation applications such as life jackets and buoys.
CFC EMISSIONS CHARACTERISTICS
The CFC emissions characteristics of rigid foams can be conveniently
divided into production, in—use, or disposal emissions.
Production Emissions
Polyurethane Foam—
The primary characteristic of rigid polyurethane foams is that the
blowing agents are trapped in the finished foam's closed cells with only a
64
-------
minor amount of the blowing agent escaping during production. There is varied
information on how much CFC is lost during foam production. In general, only
a small amount is lost during the polymerization phase. This amount depends
upon the foam's stability during rise, the percentage and type of CFCs used,
the mayinmm temperature within the foam, and the extent of mechanical rupture
of foam cells after curing the foam. Table 3-8 shows the estimated CFC
emissions associated with each of the production methods.
Nonpolyurethane Foams—-
There are several sources of CFC emissions during nonpolyurethane foam
manufacturing processes. A typical polystyrene sheet extrusion process will
experience blowing agent losses of approximately 60 percent of the total
consumed (5,16). These losses occur during extrusion, curing, thermofonning,
and scrap reprocessing. Emissions from manufacture of polystyrene boardstock
were assumed to be approximately 5 percent of the CFC consumed (13). However,
based on current information, these emissions may be as high as 15 percent
(49).
Emissions of CFCs from a typical plant which manufactures polyolefin or
FVC foam originate from the extrusion process and from foam storage, while
those from phenolic foam are similar to PU foam in that only a small amount of
the blowing agent is lost during foam production. Variation in emissions can
be caused by the degree to which the CFC is premixed in the extruder, the
difference in temperature profile of the extruder, the die shape, the sheet
thickness, and specific operating conditions.
In-Use Emissions
Polyurethane Foam—
Prior to the banning of aerosol propellant CFCs and the upsurge in
production of rigid insulation foams, the predominant uses of CFC-11 led to
immediate release of the chemical to the atmosphere. However, its use in
closed cell foams is changing the emissions scenario to one in which there is
an accumulation of the blowing agent and a steady very long term release.
Informal estimates from DuPont suggest that the half lives of CFCs in
65
-------
TABLE 3-8. ESTIMATED CFG NON-WEIGHTED CONSUMPTION i EMISSIONS FROM RIGID PU FOAM PRODUCTION
IN THE U.S. (1000 mt)
o>
X CFC Content in the
Fonulaticn
X of Total CEC Bttitted
During Production
Building iMulatiai
Refrigerated Insulation
Industrial Insulation
Packaging
Transportation
Other
Total
1985
Rigid PU
Product im
191
54
27
20
29
_4
336
EatiBBtad (ZO-U Conunad
Bunatodk
14.0
2.7
0.0
0.2
0.0
0.0
0.5
3.4
Ijndneted
14.0
12.8
0.0
0.0
0.0
0.0 •
0.5
13.3
Found
12.0
2.3
6.5
0.4
2.4
2.4
0.4
14.4
Spayed
12.0
7.3
0.0
2.7
0.0
1.2
0.4
11.7
Eatiatted
OO-12 Ganauaed
Poured
5.0
1.0
2.7
0.1
1.0
1.0
0.2
6.0
&«*^M«^M|
upoiyad
1.0
0.6
0.0
0.2
0.0
0.1
0.0
1.0
Ertinted 00-11 BdMiaM
Bunatock
19.0
0.5
0.0
0.0
0.0
0.0
fill
0.6
Laadnated
2.5
0.3
0.0
0.0
0.0
0.0
0.0
0.3
Found
11.2
0.3
0.7
0.0
0.3
0.3
0.0
1.6
fl|>uiyvd
10.0
0.7
0.0
0.3
0.0
0.1
0.0
1.2
Brtinted 00-12
BdMiena
PoUTBd
36.2
0.3
1.0
0.1
0.4
0.4
cayed
20.0
0.1
0.0
0.0
0.0
0.0
0.0
0.2
Source: (3,10.13).
-------
one-inch-thick unclad rigid polyurethane foam range from 75 to 150 years
(16,5). The future emissions of CFC-11 will therefore lag behind the cumula-
tive production and sales. This creates a situation in which it is impossible
to immediately control or reduce the emissions of CFC-11 to the atmosphere,
should such an action be desired. Additionally, the uncertainties in estimat-
ing the annual release will be greatly increased.
One study examined the CFC-11 emissions characteristics of four different
types of foam insulation (4). The four foams selected were representative of
much of the closed cell polyurethane foams used for insulation. The manu-
facturers of the foam claimed that the fraction of CFC-11 in the foams was
about 15 percent by weight. Measurements taken by the experimenters, however,
indicated that the CFC-11 content was approximately 8 to 12 percent by weight.
Each sample piece was cut to a one foot by one foot square and placed into a
specially designed apparatus which would measure the concentration of CFC-11
in an air stream which was swept over the sample. The experimental results
indicated that release of blowing agent from the foam samples is characterized
by a pattern consisting of three phases. The first is quick release followed
by a transition phase and finally a period of steady release. During the
first phase which will last about two months, the release rate is relatively
large but decreases rapidly; therefore, in the long run, this period does not
account for much of the cumulative emissions of the blowing agent. Several
months later following the transition period, the rate of release of CFC-11
becomes nearly constant and this last phase represents the long term behavior
of the foam.
The main result of this study is that, in undisturbed and intact foams,
the CFC-11 remains in the foam for a very long time with a half life of
perhaps 100 or more years. One sample actually indicated a CFC half life of
320 years. Therefore, a small percentage of the total CFC-11 used in a given
year for rigid polyurethane foam production will be released quickly into the
atmosphere; the remaining CFC is held in a slow-leaking reservoir. The total
67
-------
quantity of this "banked" CFC-11 increases each year, and may eventually
become a large and almost uncontrollable source of CFC (4).
Table 3-9 shows, for the years between 1955 and 2015, estimated annual
CFC emissions from rigid polyurethane foam assuming a CFC content of 13
percent CFC-11 and two percent CFC-12 with CFC half lives of 100 years for
both CFC-11 and CFC-12. These results are rough estimates because of the
uncertainties in the assumptions, but they do indicate the potential for
tremendous growth of the banked CFCs. In 1985* approximately 461,000 metric
tons of CFC-11 and 74,000 metric tons of CFC-12 were banked in PU foams.
Assuming moderate growth rates in the various consumption areas, the bank
should triple in size, by the year 2000, to over 1.4 million metric tons of
CFC-11 and 228.000 metric tons of CFC-12.
Nonpolyurethane Foam—
Because CFC-12 and the other CFC blowing agents are able to permeate
through the polystyrene, polyolefin, and PVC foams relatively quickly, the CFC
which remains in the cells after manufacture (40 percent of the total consumed
during PS foam sheet production) is emitted early in the product's shelf-life.
DuPont has estimated half—lives of blowing agents in several of the
nonpolyurethane foam products (5). These estimates are reproduced in Table
3-10. In each case, the half life of the CFC is sufficiently small that none
remains upon disposal of a rigid nonpolyurethane product, except in the case
of thick cross-section insulating board.
TABLE 3-10. ESTIMATED HALF-LIVES OF CFC IN RIGID NONPOLYURETHANE FOAM
Foam Type
Polystyrene Sheet
Polystyrene Board
Polyethylene (CFC-12)
Polyethylene (CFC-114)
Polyvinyl chloride
Approximate Half-Life in Product
1.5 months
40 years
1 week
4 weeks
1 week
Depends on dimension of product.
Source: (5, 43)
68
-------
,a
TABLE 3-9. ESTIMATED CFC-11 AND CFC-12 EMISSIONS" FROM MANUFACTURE AND USE OF RIGID
POLYURETHANE FOAMS IN THE U.S. (1.000 mt/yr)
en
vo
Year
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
2015
Rigid
PU Prod.
0
5
41
95
ISA
244
336
476
596
748
879
1034
1216
Annual
Use
0
1
5
12
20
31
43
61
76
95
112
132
155
Cumulat.
Use
0
1
15
64
160
303
485
749
1097
1532
2057
2674
3400
Cumulat .
Banked
0
1
15
62
155
291
461
706
1025
1420
1890
2434
3068
CPC-ll
Cumulat.
Emitted
0
0
0
1
5
12
24
43
72
112
168
240
333
CPC-12
Annual Emissions
Bank
0.0
0.0
0.1
0.3
0.9
1.8
2.9
4.5
6.6
9.2
12.4
16.0
20.3
Mfg.
0
0
0
1
2
3
4
5
7
9
10
12
14
Total
0
0
1
1
3
5
7
10
13
18
23
28
34
Annual
Use
0
0
1
2
3
5
7
10
12
15
18
21
25
Cuaulat. Cumulat.
Use Banked
0
0
2
10
26
49
78
120
176
246
330
429
546
0
0
2
10
25
47
74
113
165
228
303
391
492
Cumulat .
Emitted
0
0
0
0
1
2
4
7
11
18
27
39
53
Annual Emissions
Bank
0.0
0.0
0.0
0.1
0.2
0.3
0.5
0.7
1.1
1.5
2.0
2.6
3.3
Mfg.
0
0
0
1
1
2
2
3
4
5
6
7
8
Total
0
0
0
1
1
2
3
4
5
7
8
10
12
"Estimated emission values are non-weighted.
Source) (3.10,13)
-------
Therefore, the only nonpolyurethane products which banks CEC emissions
over a one year period are polystyrene boardstock and phenolic foam. The
other nonpolyurethane foam products lose all of their CFCs within one year.
In—use emissions from polystyrene boardstock in a given year are the sum of
emissions from the newly made boardstock plus the banked emissions from
boardstock made in previous years. Two-inch (5.1 cm) thick PS boardstock has
a 40-year half-life emitting 2 percent of its CFC content within one year.
Table 3-11 estimates the projected emissions from PS boardstock assuming 6
weight percent CFC-12 content and a 40 year CFC half-life.
Disposal Emissions
Polyure thane Foam—
Generally. CFCs are banked in rigid polyurethane foams. For undisturbed
foams, leakage of CFC from the closed cells is a very slow process; the CFC
half-life may be 100 years or more. Thus, the life of the CFCs in the foam is
essentially equal to the life of the product containing the foam; disposal
emissions will only occur when the foams are crushed or burned. Since a
majority of foams are used in the construction industry (57 percent in 1985).
the CFCs will remain in the foams until the homes or buildings burn down or
are demolished. It may be possible, however, to remove the foams (much in the
way that asbestos products are removed from a building) prior to demolition,
and transport them to a CFC recovery facility.
The second largest consumption area for rigid foams (16 percent in 1985)
is refrigeration insulations. A Rand report (16) estimates that a refrig-
erator lasts about 10 to 15 years and contains about 1-1/2 pounds of CFC in
its foam. Typically, after the unit has been disposed of, its motor, com-
pressor, and tubing are removed for scrap, and the housing is then sent to a
landfill dump where it is crushed (releasing the CFCs) and buried. In other
scenarios, the unit is buried intact or abandoned and left to deteriorate.
Here again, it may be technically possible to collect old refrigerators and
remove them to a CFC recovery facility.
70
-------
TABLE 3-11. ESTIMATED CFC-12 EMISSIONS FROM MANUFACTURE AND USE OF EXTRUDED PS-FOAM
BOARDSTOCK IN THE U.S. (1,000 mt/yr)
Year
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
2015
PS-Foamed
Board
Prod.
4
6
9
14
18
32
49
72
92
118
140
166
197
CFC-12
In Foam
0.2
0.4
0.6
0.8
1.1
1.9
2.9
4.3
5.5
7.1
8.4
9.9
11.8
Cumulat.
Use
0
2
4
8
13
21
32
51
76
108
147
193
248
Cumulat.
Banked
0
2
4
7
11
18
27
43
64
90
120
155
196
CFC-12
Cumulat.
Emitted
0
0
0
1
1
3
4
7
12
18
27
38
53
Annual
Product
0.0
0.0
0.1
0.1
0.2
0.3
0.4
0.7
1.0
1.4
2.0
2.5
3.2
Emissions
Mfg.
0.0
6.0
0.0
0.0
0.1
0.1
0.1
0.2
0.3
0.4
0.4
0.5
0.6
Total
0.0
0.0
0.1
0.2
0.2
0.4
0.6
0.9
1.3
1.8
2.4
3.0
3.8
Non-weighted
Source: (3)
-------
Nonpolyurethane Foams—
Similar to rigid PU foams. PS boardstock and phenolic foam insulation can
retain a substantial amount of its blowing agents until the time of disposal.
The half life of CFCs in PS foam is dependent upon the foam's thickness and
density; this can range from 5 years for 0.033 g/cc (2 lb/ft3). 1.3 cm (1/2
inch) thick foam, to 250 years for 0.048 g/cc (3 lb/ft3), 7.6 cm (3 inch)
thick foam (43). PS foam sheet, on the other hand, has a half life on the
order of 1.5 months, and there would be a negligible amount of CFCs retained
in the foam sheet products upon disposal. The same would be true for
polyolefin and PVC foams which also have a half-life less than one month.
CHARACTERIZATION OF WORLD CFC EMISSIONS FROM RIGID FOAMS
Consumption of CFCs for the manufacture of rigid foams as a percentage of
total CFCs appears to be relatively similar for the U.S. and the rest of the
world (2). The estimated 1985 consumption of CFC-11 for rigid foams in the
world is 133,000 metric tons and for CFC-12 is 53,000 metric tons.
Since the mid 1950s approximately 1.2 million metric tons of CFC-11 and
244.000 metric tons of CFC-12 have been consumed in the worldwide production
of rigid foams (1). The accumulated consumption of CFC-11 for rigid foams
accounts for roughly 20 percent of the total CFC-11 ever produced. About 53
percent of the CFC-11 consumed for rigid foams is banked in these foams.
Similarly, the accumulated consumption of CFC-12 in the production of rigid
foams is about three percent of the total CFC-12 ever produced. Six percent
of the cumulative CFC-12 used in rigid foam production is banked.
The emissions cf CFCs from rigid foam occur from the manufacturing
operations and from the CFCs banked in the product. In 1985, the CFC-11
emissions from manufacturing accounted for approximately 10 percent of the
consumption or 13,300 metric tons. For the same year, the CFC-12 emissions
from manufacturing are estimated at 90 percent of the total world consumption
or 47,700 metric tons.
72
-------
The CFC-11 emissions from the bank are estimated at 0.5 percent of the
total CFC-11 and 2 percent of the total CFC-12 in the bank. Therefore, the
1985 world CFC-11 emissions from the bank are approximately 3,400 metric tons
and the CFC-12 emissions from the bank are approximately 400 metric tons.
The 1985 total world CFC-11 and CFC-12 emissions from rigid foam manufac-
turing are 16,700 metric tons and 48,100 metric tons, respectively.
73
-------
SECTION 4
DESCRIPTION OF CURRENT PROCESS TECHNOLOGY
RIGID POLYURETHANE FOAM PRODUCTION
Polyurethane foams are cellular plastics, generally produced by the
reaction of a polyol and a polyisocyanate in the presence of a blowing agent,
a catalyst, a surfactant and other specialty additives such as flame
retardants. The most commonly used isocyanates in polyurethane foam
manufacture are toluene diisocyanate (TDI) and polymeric methylene diphenyl
dilsocyanate (MDI). Most rigid polyurethane foam is made using PMDI.
Typically the ingredients are blended continuously in a high speed mixer and
discharged while the mixture polymerizes and expands. The blowing agent is
blended into the polyol, or it is metered as a separate stream to the mixing
heads of the foam machine. Rigid foams have a wide range of densities,
formulations, and uses. In general, rigid polyurethane foam production can be
divided into four types of processes: laminated foam core panel manufacture.
poured foam production, sprayed foam application, and bunstock production.
The following paragraphs describe these processes.
Laminated Boardstock
Rigid polyurethane laminated boardstock production is similar to flexible
foam bunstock production. In this process, the liquid polyol and isocyanate
mixture is poured as a thin layer onto a facing material which is moving
continuously on a conveyor. A short distance beyond the point of foam appli-
cation, an upper facing material is applied to the top of the expanding foam
mixture. Film facing materials include asphalt or tar paper, aluminum, steel,
fiberboard, or gypsum. As it moves along the conveyor, the foam expands to a
thickness controlled by nip rollers and upper and lower conveyers. Figure 4-1
presents a schematic of a typical laminated boardstock operation.
74
-------
A - Polyol Mixture
B - Isocyanate Mixture
1) agitated material tanks; 2) metering pumps; 3) traversing mix-head; A) top facing roll; 5) bottom
facing material; 6) adjustable nip rollers; 7) oven and conveyer; 8) expanding foam and adjustable
panels; 9) transverse cutter; 10) cut foam.
Figure 4-1. Laminated foam boardstock line.
-------
Laminated board stock production emits relatively small quantities of
CFCs. The emissions occurring during initial mixing of foam ingredients are
roughly one percent. The losses occurring as the foam is dispensed is
approximately 1.5 percent, bringing the total manufacturing emissions to 2.5
percent of the initial charge (10).
For laminated rigid polyurethane foams, a large percentage of the CFC
blowing agent is trapped in the foam for up to hundreds of years. The
relatively small quantities of CFCs emitted during the manufacturing steps
could possibly be controlled through add-on controls such as carbon
adsorption. However, control of in-use, or product emissions would require a
different approach. Using lower ozone depleting blowing agents or replacing
the foam products with non-CFC containing materials are two approaches to
emissions control. Laminated foams are used as sheathing insulation for
buildings and homes. They have high insulating efficiencies and replacing
them with alternative non-CFC sheathing materials would require greater
thicknesses to obtain equivalent insulation. Alternative sheathing materials
include expandable polystyrene (EPS) board, extruded PS board, fiberboard, and
others. The very long half life of CFCs in rigid polyurethane foams causes
mich of the CFC to be retained in the foam even at the end of the foam's
useful life. This gives rise to the possibility of recovering blowing agent
from discarded foam products. This would require initiation of a foam scrap
collection program in which collected foam would be transported to a facility
the foam would be crushed and the CFCs adsorbed on carbon beds.
?our-in-place/ Injected Foams
The pour-in-place or injected foam process involves pouring or injecting
ihe liquid polyurethane mixture into spaces within rigid structures such as
refrigerator walls, refrigerated tanks, and building walls. Foaming pro-
gresses in place to fill all crevices and form a continuous mold. The final
product is a continuous foam structure with excellent insulating properties.
figure 4-2 shows the equipment used in a foam injection operation.
76
-------
A - Polyol Mixture
B - Isocyanate Mixture
$
o
1) agitated material tanks; 2) metering pumps; 3) mix-head/injector; A) refrigerator housing; 5)
vent holes.
Figure 4-2. Foam injection operation.
-------
Pour/inject ion systems have widely varying emission rates. This is
because of the variety of cavities into which the foams are poured. These
systems also employ CFC-12 as a frothing agent (17). The rigid polyurethane
foam is ejected from a frothing device pre-expanded about 20 to 30 percent and
has the consistency much like an aerosol foam. It is estimated that, for a
typical freezer insulating operation, 10 percent of the CFC-11 and 35 to 85
percent of the CFC-12 is emitted (9,10). An additional one percent of CFC-11
and one percent of CFC-12 is lost in mixing and handling. The frothing
process is in decline because of advances in poured-in-place formulations
(18).
For poured foams, carbon adsorption could be used to collect CFCs emitted
during both manufacture and disposal of the product. Reduction of in—use
emissions would require using alternate, low ozone depleting blowing agents or
non-CFC containing products. Before the introduction of polyurethanes, re-
frigerated appliances were insulated with glass fiber insulation. However, an
emphasis on new materials and designs for refrigeration systems including
higher grade insulation has resulted from more stringent appliance energy
standards. Thus, it is likely new materials or system designs will play an
important role in the refrigeration insulation options for the future.
Sprayed Foams
Rigid polyurethane foam may also be produced by spraying the liquid
chemical mix directly from the mixing head onto the surfaces requiring insula-
tion. Sprayed foams are often used for on-site application of rigid thermal
insulation. Typical surfaces which require a foam spray include storage
tanks, piping, or roofs. As with pouring operations, froth spraying has
become a convenient method of achieving the desired density and skin thick-
ness. Figure 4-3 shows setup and use of a typical foam sprayer.
The mixing and handling emissions of CFCs is spraying operations are as
low as 0.5 percent of the total used in formulation. This is because the
78
-------
VO
A - Polyol Mixture
B - Isocyanate Mixture
1) material tanks, 2) metering pumps, 3) mixhead/sprayer.
Figure 4-3. Sprayed-foam operations.
-------
pray system uses a liquid mixture which is usually prepared by a supply
lompany. These suppliers prepare mixtures in large volumes allowing tighter
:ontrol of CFG emissions.
Spraying losses are dependent upon the conditions during the spraying
.pe rat ion. It is estimated that 10 percent of the CFC-11 and 20 to 90 percent
>f the CFC-12 are emitted during spraying (9.10.22). Because the CFC-12 is
tsed as a frothing agent, its emissions are expected to he relatively high.
The nature of the sprayed foam operation all hut eliminates the possi-
>ility of emissions recovery during spraying. Additionally, disposal recovery
'ould he severely limited because removal of sprayed-on foams from their
:ubstrate would most likely rupture the foam cells and release the CFCs. The
>rimary control options would be using alternative blowing agents or non-CFC
jis ulation.
Sunstock Foams
Rigid polyurethane foam bunstock is manufactured on both a small and
-arge scale. The manufacturing facility for rigid PU foam bunstock is very
similar to that for flexible PU foam bunstock manufacture. In this process, a
.iquid polyol mixture is poured as a thin layer onto a continuously moving
:onveyor where it expands to form a continuous block, or bun, of foam.
Adjustable top panels control bun height. After oven curing, the foam may be
sliced to specific thicknesses by a variety of sawing methods. The slices are
:hen either cut into flat boards or profiled for such applications as pipe
Insulation. Figure 4-4 shows the layout of a typical bunstock production
init. Improvements in laminate technology have led to the decline in bunstock
aanufacturing.
A majority of the CFC emissions from the manufacture of bunstock occur as
=he foam is being dispensed onto the moving conveyer. This loss amounts to 13
percent of the CFCs initially included in the foam ingredients (10). An
80
-------
A
/7\
B
CO
A - Polyol Mixture
B - Isocyanate Mixture
1) agitated material tanks; 2) metering pumps; 3) traversing mix-head; 4) top paper roll; 5) exhaust
hood; 6) bottom paper roll; 7) conveyer; 8) expanding foam; 9) transverse cutter; 10) cut foam bun;
11) adjustable top panels.
Figure 4-4. RiRid polyurethane bunstock foam line.
-------
additional five percent is lost as the closed cells are broken in the cutting
and trimming operations. The emissions occurring during initial mixture of
foam ingredients are roughly one percent bringing the total emissions to 19
percent of the initial charge.
The CFC control options for bunstock foams are the same as those for
laminated sheet foams. Carbon adsorption could be used to reduce manufactur-
ing and disposal emissions. Reduction of product emissions would require
alternate blowing agents or non-CFC insulation materials.
RIGID POLYSTYRENE FOAM PRODUCTION
Polystyrene foam is formed by one of two general methods. It is either
extruded into sheet, film, or boardstock; or it is formed from expandable
beads.
Extruded Polystyrene
In the extrusion process, polystyrene resin is mixed with additives and
melted to a low viscosity in a two-stage screw extruder. The fluorocarbon (or
hydrocarbon) blowing agent is injected under high pressure into the extruder,
where it is dispersed in the polymer melt. This mixture is cooled and forced
through a die under controlled pressure (14). The die can be of several
shapes; a round die forms rod-shaped foam, a slit die is used to form a block
or slab, and an annular-shaped die is used to form a tube which is slit to
make foam sheets. As the molten polymer exits the die, the dissolved blowing
agent vaporizes causing the plastic to foam. The final stages involve
cooling, shaping, cutting, or winding the foam into the desired form. Ex-
truded foam is normally aged 24 hours prior to thermoforming the final pro-
duct. Approximately 80 percent of all extruded PS foam produced consists of
foam sheet. This material is thermoformed into a variety of products in-
cluding single service items (such as plates, bowls, and cups) fast food
cartons, egg cartons, and meat trays. The remaining 20 percent of PS foam
82
-------
production is primarily boardstock which is not thermoformed. This material
is most commonly used as a construction insulation material.
The thermoforming step of most PS foam sheet manufacturing processes
generates a substantial, amount of foam scrap. In some cases, 30 to 40 percent
of the extruder feed will eventually become scrap pieces. Because this
occurs, manufacturing processes commonly include a grinding and repelletizing
step after the final cutting and thermoforming steps. The recovered scrap
foam pellets are recycled to the extruder feed. The typical extruder feed
mixture is 65% virgin PS and 35% recycled PS. A flow diagram of an extruded
polystyrene sheet manufacturing process using scrap recovery is shown in
Figure 4-5.
In polystyrene-foam manufacture. CFCs are emitted at various points in
the process. Table 4—1 summarizes the emissions generated in each phase of
sheet and boardstock manufacturing. As can be seen from the table, the
relatively thin extruded sheet has much more prompt emissions of CFCs which
occur during the extrusion and thermoforming operations. However, based on
recent information, the emissions from extrusion, aging, and thermoforming may
be roughly equal (52). In addition, these emissions may be lower and
considered fugitive rather than being controllable as indicated in Table 4-1,
with a high percentage of CFCs leaving the plant with the finished product
(52). Boardstock, on the other hand, is much thicker and holds the majority
of CFC in the foam cells as a bank of CFC.
Expandable Polystyrene
The majority of polystyrene foam is extruded; however, a great deal of
molded foam products are manufactured from expandable polystyrene (EPS) beads.
Insulating materials, packaging, drinking cups, ice chests, and flotation
material are typical EPS foam products. The beads are formed during the
manufacture of the polystyrene itself, in the suspension polymerization phase
(19). The blowing agents, primarily pentane, are incorporated directly into
the beads.
83
-------
CFG • 12
VIRGIN
POLYSTYRENE J—
RESIN
SCRAP REStN
STORAGE SILOS
oo
SCRAP RESIN
P REPELLETIZER
(OPTIONAL)
POTENTIAL CFC RECOVERY POINTS
A OUTSIDE AND INSIDE EXTRUDED BUBBLE
B THERMOFORMINQ MOLDS
C REPELLETIZER EXTRUDER VENT
D EXHAUST FROM PNEUMATIC TRANSFER
OF REQROUND SCRAP FILM TO 6IUOS
NOTE:
1 CFC CAPTURE SYSTEM IS NOT EXISTING.
NEED TO BE DEVELOPED.
Figure 4-5. Flow diagram of a typical polystyrene foam sheet manufacturing process,
-------
TABLE 4-1. SUMMARY OF CFC EMISSION SOURCES AND EXAMPLE DISTRIBUTION
IN POLYSTYRENE FOAM MANUFACTURING
Percent Percent
From From
Extruded Extruded
Sheet Boardstock
Manufacturing Losses
Extrusion Losses
Intermediate Storage
Thermoforming
Regrinding Scrap
Reextruding Scrap
Prompt Foam Cell Losses
(within first year)
Banked Emissions
34 5
4 0
5
15
1 — —
41 2
0 93
100.0 100.0
Source: (18,32)
Note: These estimates may vary among producers based on blowing agent content
and process conditions.
85
-------
The foaming process begins as the beads are heated with steam and par-
tially expanded. The pliable beads are then transferred to molding stations
and stored for approximately 6 to 24 hours while the beads cool and reach an
equilibrium. Finally, the beads are conveyed to the mold, usually by air,
where they expand to their final form. The preexpanded polystyrene bead is
heated in the mold by steam through perforations in the mold, or by means of
steam probes. During this final expansion, the beads melt together slightly
which allows them to adhere to each other, while at the same time, a smooth
outer skin is formed along the mold walls. Once the polystyrene bead has
expanded to nearly fill the mold, the steam is stopped and the beads expand to
their final size.
In addition to the use of pentane as a blowing agent, a mixture of CFCs
and hydrocarbons are also used as blowing agents by several expandable PS foam
manufacturers to produce expandable PS foam loose fill packaging (49). These
products are produced by two methods: 1) pressurized extrusion of a high
density pellet which is later expanded or 2) extrusion with expansion at the
extruder die.
86
-------
SECTION 5
CONTROL/RECYCLE TECHNOLOGIES FOR CFC-12
IN POLYSTYRENE FOAM SHEET MANUFACTURING
A possible approach to reducing CFC-12 emissions in the manufacture of
polystyrene foam sheet is to apply capture/recovery or destruction systems as
an add-on to the foam process. Such systems can be categorized as follows:
• carbon adsorption with CFC-12 recovery;
• direct flame or catalytic incineration of CFC-12 in plant
exhausts;
• absorption (liquid scrubbing) with CFC-12 recovery; and
• vapor condensation and recovery.
The following discussion will stress application of adsorption recovery, al-
though some discussion of other alternatives is warranted to point out the
difficulties of applying these technologies to CFC-12 emission control.
CARBON ADSORPTION AND STEAM DESORPTION SYSTEMS
Activated carbon adsorption has been applied commercially for recovery of
expensive solvents for many years. Such systems have potential for applica-
tion to CFC-12 capture and recovery. However, the use of carbon adsorption
and CFC-12 recovery has not been implemented commercially for the manufacture
of polystyrene sheet. The probable main reason for this is the high capital
expenditure required for the adsorption/regeneration/recovery hardware, as
compared to the relatively low total value of the recovered CFC-12.
87
-------
Process Engineering and Operating Factors
The physical principle applied in adsorption/recycle processes is based
on the adsorptive affinity of an activated carbon surface for organic
molecules, such as CFC—12. These compounds are preferentially separated from
a gas stream and retained on the surface of activated carbon particles. In
practice, a large volume of carbon particles are contained within a vessel,
referred to as the adsorbent bed, to provide a large carbon surface area. The
CFC-12 molecules are retained, or adsorbed, on the carbon and then are re-
leased, or desorbed. when the carbon particles are heated. Steam is generally
used to heat the carbon particles and displace the desorbed organic material.
By condensing this stream, the organic material can be separated from the
steam condensate (decanted), recovered, and reused.
A schematic illustrating the main features of this process appears in
Figure 5-1. At least two adsorbent bed vessels in parallel, each containing
activated carbon particles, are required to provide alternating cycles of
adsorption and regeneration. A boiler and/or other heating equipment is used
to provide stream and/or heated air for bed regeneration. Usually, the regen-
eration stream is arranged to flow countercurrent to the direction of the
treated air stream (although co-current regeneration is sometimes used). A
cool or chilled water condenser* is included to condense the mixture of steam
and CFC—12 after desorption from the carbon beds. Finally, a decanter unit
separates the two phases, returning the reclaimed CFC-12 phase to the foam
line CFC feed tank, or to further purification if needed.
A number of key engineering factors can be identified in applying an
adsorption process to recovery of CFC-12 in PS foam plants. The most impor-
tant of these are:
• reducing the volume (flow rate) of air to be treated,
• design of an efficient regeneration/condensation unit,
88
-------
Exhaust from
Tunnel
00
Adsorber No. 1
/////////////
Adsorber No. 2
«i!
Steam
Rngeneralor
Steam
Exhaust Gas
to Atmosphere
«i!
t
t
f
Feed Water to
Steam Regenerator
Cooling Water
I
I
I
1
i
i
Condensale
X
Decanter
to Storage
Figure 5-1. Schematic flow diagram of typical carbon adsorption/solvent
recycle process.
-------
• possible corrosion problems due to decomposition of the
CFC, and
• uniformity and quality of the reclaimed CFC-12.
In addition, if trace contaminants, such as resin fines or residual styrene
monomer, exist in the exhaust gas streams, pretreatment of the gas stream
before the carbon beds will be required.
In general, the capital costs of the CFC-12 vapor collection system and
the carbon adsorption system are proportional to the volume flow of air to be
treated. The distribution of CFC-12 emissions with the process also affects
the efficiency of recovery. Emissions characteristics may differ widely be-
tween various foam processes. Table 5-1 summarizes typical emission distribu-
tions for a PS-foam sheet process. For most existing PS foam processes, the
exhaust concentration .of CFC-12 is relatively low. As shown in Table 5-1,
CFC-12 concentrations are 1000 ppm or less in all areas of the facility.
Effective design of a carbon adsorption/recovery system must therefore
incorporate ventilation designs which reduce volume and minimize dilution of
the emitted CFC-12.
Proposed equipment modifications that would minimize air flow and deliver
the highest possible concentration of CFC-12 to the carbon adsorber involve
thorough enclosure of the largest CFC emissions sources to reduce the volume
of ventilation air. Any smaller sources, such as the scrap extruder, which
already have high CFC concentrations in their exhausts, can also be combined
and routed to a recovery device.
Another possible means of decreasing the total air flow to the carbon
adsorbers is to cascade the dilute exhaust from one zone or collection station
to another with a higher CFC concentration. Also, air curtains can be incor-
porated in the overall system to help contain emissions within the work area,
and subsequently, the bulk of the air would be exhausted from around the
90
-------
TABLE 5-1. CFG EMISSION SOURCES IN PS-FOAM SHEET MANUFACTURE
Operation
Extrusion
Rolled Film Storage
Thermoformer
Regrinding Scrap
Re extruding Scrap
Final Product
Emissions
(% of CFC Fed)
34
4
5
15
1
41
CFC-12
Concentration (ppm)
200a
35
75
85b
1000C
Source: (32)
a Measured at slitter.
Measured at storage silo vents.
Measured at extruder vent.
Note: These estimates may vary among producers based on blowing agent content
and process conditions. Based on recent data, the emissions may be
lower, with the extrusion, intermediate storage, and thermoforming
emissions being roughly equal and considered fugitive rather than
controllable (52).
91
-------
rocess CFG sources. Such an elaborate flow scheme is not incorporated in the
esign and cost analysis discussed in this report, but is suggested here to
.ndicate the potential for enhanced overall emission control.
Regeneration of the carbon beds can be accomplished by purging with
.ow—pressure steam. Generally, the purge steam is applied in the opposite
low direction to the CFC-laden exhaust gas. An alternative procedure would
>e to regenerate the beds using a heated inert gas stream (such as air or
litrogen) rather than steam. After steam regeneration, it is desirable to dry
:he carbon bed, using ambient air. This feature is common to many existing
:ull-scale solvent recovery systems, and if omitted, the bed capacity will be
idversely affected.
Corrosion problems with CFC-12 are typically less severe than are regu-
-arly encountered in halocarbon solvent recovery systems. Although CFC-12 is
relatively stable, when it comes into contact with elevated temperature sur-
faces, the molecules may crack, or decompose, to hydrofluoric acid (HF) and/or
lydrochloric acid (HC1). These compounds are particularly corrosive to duct
7ork. For this reason, it is generally recommended that adsorbent bed vessels
>e constructed of corrosion resistant materials (10).
Quality and uniformity of the reclaimed CFC-12 is an important issue in
:he economic feasibility of recovery systems because of the potential operat-
ing cost credit for recovered blowing agent. It is possible that the CFC-12
recovered by carbon adsorption would not require repurification before reuse,
and therefore would be a cost credit. However, additional onsite processing
Including drying and distillation, may be required to produce an acceptable
oroduct. Additionally, if the material can not be reused, it would have to be
sold to a recovery or disposal company, resulting in an added cost.
92
-------
Control Costs and Effectiveness
From a technical standpoint, there are two key factors that determine the
effectiveness of carbon adsorption control of CFC-12 emissions at a particular
facility. These are the efficiency of CFC-12 emission capture and the removal
efficiency of the activated carbon bed. The emissions would be collected from
the process exhaust and plant ventilation gas streams. Local collection effi-
ciencies within the plant limit the fraction of emissions that can be con-
trolled. The effectiveness of emission control would vary from plant to
plant, but it is estimated that for a typical two extruder, four thermoformer
plant, roughly 42 percent of the CFC-12 emissions could be recovered. This
estimate is discussed further in the following subsections of this report.
The cost effectiveness of this control method can be expressed as the
dollar cost per unit CFC-12 emission averted. Control expenditures consist of
the annualized capital recovery and operating costs less the credit obtained
for reclaimed blowing agent. In an analysis of a CFC-12 carbon adsorption/
recovery system for a two extruder plant, the cost of CFC control is estimated
to be $0.72 per kilogram ($0.33/lb) of CFC-12 controlled. If the recovered
CFC-12 is reusable the control cost could be much lower or even generate an
overall credit.
Clearly, significant increases in CFC-12 price and/or recovery efficiency
would provide economic incentive for implementation of control by fearners, and
would also speed recovery of the investment. It is apparent that optimal
design of the ventilation system for high capture efficiency with minimal
capital cost is advantageous. Pilot plant studies would be useful to syste-
matically define the critical design parameters in achieving high recovery
efficiency at lowest system cost.
93
-------
Safety and Environmental Factors
There are no apparent effects on the health and safety of workers in the
polystyrene foam industry connected with use of carbon adsorption/recovery
technology.
Wastes from the carbon adsorption process consist of spent carbon and
aqueous condensate. Recycle of steam condensate from the CFC-12 recovery
operation is feasible, although it may be advisable to include a purification
step or purge stream in the recycle loop to avoid recycling of organic impuri-
ties. Disposal of condensate is also possible providing local and Federal
regulations allow it. If distillation is used, residues from purification of
the reclaimed blowing agent may represent another potential disposal cost.
No studies to date have examined the impact of waste disposal associated
with carbon adsorption in CFC-12 recovery applications. It is likely that
spent carbon could be disposed of by incineration in the process steam boilers
at the foam plant. It may also be possible to thermally regenerate the spent
carbon in order to avoid high replacement costs. Land disposal of the acti-
vated carbon waste may not be possible due to the current EPA ban on chlori-
lated wastes.
Current Status
To date there has been no commercial scale carbon adsorption and recovery
system in continuous operation at a polystyrene foam facility. Additionally,
:here has been no research to technical development in the area of CFC-12
:arbon adsorption for polystyrene foam sheet extrusion facilities. The fact
:hat nearly 60 percent of the CFC-12 used for blowing this foam is lost in the
>rocessing area indicates the potential for raw material cost savings. The
•rimary barrier to adaptation of this technology appears to be the capital
.nvestment involved and no regulatory incentive for control.
94
-------
Economic Factors
The chief economic factor in implementation of carbon adsorption for
control of CFC-12 emissions from rigid polystyrene foam sheet plants is the
producer's ability to recover the capital expenditure, and remain competitive.
The polystyrene foam industry is sufficiently mature and competitive that
individual producers must seek to minimize costs, even on a short term basis.
To remain competitive, small foamers might find it difficult, if not impos-
sible, to pass along capital recovery costs; it is these smaller plants for
which the credit for reclaimed blowing agent is smallest in comparison to the
necessary capital investment.
While the capital expense of retrofitting a plant for a carbon adsorption
system might be a barrier for medium and small foamers, actual overall annual
savings may be experienced due to reduced blowing agent consumption. In prac-
tice, the economics will vary considerably from plant to plant because of the
wide variety of processing facility configurations and sizes. Also, in order
to gain the benefit of the CFC recovery, the foamer must have the ability to
generate the capital for the recovery system. A typical facility will require
at least several hundred thousand dollars for this system.
For foam processors who are currently using CFC blowing agents, there is
the alternative of using hydrocarbon blowing agents. Although the hydro-
carbons are cheaper, the foamer may be hesitant to switch to hydrocarbons
because of fire hazards. Additionally, small foamers may not be able to se-
cure proper insurance for their operations. Many larger firms that use hydro-
carbons are self insured. Finally, even if the foamer chose to switch to
hydrocarbons over carbon adsorption with CFC-12, the foamer may still be re-
quired to control hydrocarbon emissions as a result of current VOC emissions
regulations. The VOC control technology is carbon adsorption or incineration.
95
-------
Engineering and Cost Analyses
It is anticipated that the greatest potential for economical capture and
recovery of CFC-12 emissions in extruded PS foam plants exists at the foam
artruder, scrap silo vents, and scrap repelletizer vent. While additional
laterial could he collected by using extensive plant ventilation schemes, the
ligher capital expenditure may1not be justified, since the incremental in-
:rease in recovery would be low.
For this study, calculations are performed for a model plant which con-
sists of two extruders and four thermofoamers. This represents a typical
?S—sheet facility. The total production of thermoformable foam sheet would be
f.100 metric tons (9 million pounds) per year. At 6 percent blowing agent
:ontent in the initial foam formulation, this plant would use about 245 metric
rons of CFC-12 per year. This example facility will be used to assess the
economic feasibility of CFC-12 capture and recovery using carbon adsorption.
The important parameters characterizing the example foam plant used in
:his engineering analysis are summarized in Table 5-2. These parameters are
•epresentative of a mediun to small sized facility, and the production rates
ire typical for these plants. As mentioned earlier, the areas showing the
>est potential for CFC recovery are the extruder, the scrap silo vents, and
:he scrap repelletizer. These sources represent 50 percent of the total emis-
sions (because 40 percent of the emissions are from the product) and 85 per-
:ent of the manufacturing emissions* The exhaust system capture efficiency is
iStimated to be about 88 percent for the CFC emissions from the controlled
:ources. Further activated carbon adsorption beds can be designed to adsorb
.t least 95 percent of the CFC-12 present in the exhaust air stream. There-
ore, the system's net capture efficiency would be about 42 percent of the
IFC-12 consumed. This is approximately 102 metric tons of CFC-12 per year.
Figure 5—2 shows a schematic flow diagram for the model plant. The flow
liagram shows all raw material addition points and CFC emission sources.
96
-------
TABLE 5-2. MODEL POLYSTYRENE EXTRUDED FOAM SHEET PLANT
OPERATING PARAMETERS
Annual Production, mt (Ibs.)
Production Rate, kg/hr (Ib/hr)
Number of Extruders
Foam Sheet Web Width, m (ft)
Extrudate Velocity, m/min (ft/min)
Typical Initial Foam Formulation
Polystyrene
Blowing Agent
Additives
Number of Thermoformers
Percent Scrap in Feed
4,100 (9 million)
680 (1500)
2 ® 340 kg/hr (2 @ 750 Ib/hr)
1.2 (4)
0.6 (2)
CFC-12 Blown
93Z w
6Z w
1% w
4
35
97
-------
VO
00
Figure 5-2. Schematic flow diagram for polystyrene foam sheet model plant.
(Streams 6, 14, 15 sent to carbon adsorption system)
-------
Table 5-3 contains a material balance for the model plant showing the flow
rates of polystyrene and CFC-12 through the various processing steps. From
the material balance, the total CFC amount sent to the carbon adsorber is 0.30
kg/min., while the total exhaust flowrate is 55 nr/min. (approximately 2000
cfm).
Figure 5-3 depicts the proposed carbon adsorption/recovery system for
CFC-12. Two beds in parallel are required for the design throughput; one bed
operates in adsorption mode while the other is being regenerated. Steam for
desorption and bed regeneration is provided by a boiler unit. The regenera-
tion steam is routed through the beds countercurrent to the direction of
treated air flow (for more efficient desorption), and then through a
water-cooled condenser. The condensed steam and CFC-12 vapor are separated in
knockout vessel. The condensate is recycled to the boiler feedwater makeup
line, and the CFC-12 vapor passes on to a compression system. In the compres-
sion step, the CFC is passed through a drier, and then compressed to a liquid.
The liquid is then cooled and, depending upon its purity, either recycled to
the CFC-12 feed storage tank, or sent to disposal tanks.
Carbon Bed Design—
Based on the performance of carbon adsorption systems in other service,
carbon bed recovery efficiencies in excess of 95 percent can be easily at-
tained. For the example system, the removal rate of CFC-12 from the air
stream is 0.29 kg/min (0.63 Ib/min) and the exhaust air flow is 0.91 Nm3/s
(1,900 scfm), which is assumed to enter the bed at about 21°C (70°F). Adsorp-
tion capacity for a given activated carbon as a function of temperature and
CFC concentration in the gas stream can be determined from experimentally
derived relationships referred to as isotherms. The CFC-12 isotherms for
Calgon BFL® activated carbon used in the example system appear in Figure 5-4.
Using the available isotherm data, a realistic design basis can be de-
rived from CFC-12 adsorption beds. At a concentration of 1070 ppm, the CFC-12
partial pressure is 0.72 Fa (0.015 psia) based on a bed temperature of 21°C
99
-------
TABLE 5-3. POLYSTYRENE/CFG MATERIAL BALANCE
SUMBNaoe
PS. kg/min
CTC, kg/idn
CTC Capture Eff.. X
CTC Collected, kg/Bin
Bctaurt Flow. Bf/ain
. cfa
Bdieurt CTC Gone,, g/n
•~* mu
O • H""
0
1
Fnch
PS
Feed
7.37
—
—
—
—
—
—
—
2
Regrind
PS
Feed
3.97
0.027
__
—
—
—
—
—
Cabined*
PS
Feed
5.67
0.014
—
—
—
—
—
—
4 5
Bctnided
CRT PS
Feed Shett
— 5.67
0.327 0.225
_ _
— —
— —
— —
— —
— —
6
Bctnxter*
tbdmiam
—
0.116
88
0.102
16
565
6.38
1250
7
PS
Fran toll
Storage
11.3
0.422
—
—
—
—
—
—
8
ac
FroBRall
—
0.0272
0
—
—
—
—
—
9 10 11
Ihnw ttmoD- QTC
CuiiBd CUIB Ibamfom
Product Hwto tOmiam
7.37 3.97 —
0.252 0.136 0.034
_ — o
— — —
_ _ _
— — —
_ _ _
— — —
12 13 14
Product Scnp
«•»•••*** I^UfcBJ* GBUMmMMmM
— 3.97 —
0.252 0.0337 0.102
0 — 88
— — 0.0898
— — 17.0
— — 600
— — 5.28
- — 1030
15
Pellet iwr
Britticoa
—
0.0068
88
0.0060
5.66
200
1.06
207
*Repreaent« 1/2 total amount.
-------
CFC RICH EXHAUST
GAS FROM FOAM
PROCESS AREAS
MAKE-UP
WATER
CFC CLEAN
EXHAUST GAS
CFC -12
CONDENSATE
KNOCKOUT
TANK
DRYER
COMPRESSOR
CONDENSER
REFRIG.
RECOVERED CFC
TO STORAGE
OR DISPOSAL
SLOWDOWN
Figure 5-3. Proposed CFC-12 carbon adsorption/recovery system for a polystyrene
foam sheet extrusion plant.
-------
100
0001
.001
.01 O.I
PARTIAL PRESSURE OF CFC-12, PS IA
10
1C
Figure 5-4, CFC-12 adsorption on BPL© activated carbon.
Source: (54)
-------
(70°F). For these conditions the BPL* carbon adsorption capacity can be esti-
mated to be about 10 weight percent. An appropriate design rule is that the
working bed capacity is one half of this value, or 5 weight percent. This
allows for residual CFC-12 remaining in the bed after each regeneration cycle,
(i.e., the CFC heel) and for the loss of carbon capacity due to contamination.
3 3
Typically, packed carbon particles have a density of 490 kg/m (30 Ib/ft );
therefore, each cubic meter of bed volume will adsorb 24.5 kg of CFC-12 (1.5
Ib. CFC-12/ft3).
To provide the required capacity without excessive bed size, the system
includes two carbon beds in parallel, one bed being on-line (adsorbing) with
the remaining bed being regenerated. Beds of the size and type for this
service require about one hour for steaming and one hour for cooling,
therefore, each bed would be on-line adsorbing for two hours and off-line
regenerating for two hours.
q
For air flows in the range of 0.91 Nm /s (1,900 scfm), carbon adsorption
beds are usually loaded in large horizontal steel tanks, at a depth of about
0.6 to 1.8 meters (2 to 6 feet). To achieve 95 percent recovery in the bed, a
reasonable maximum gas velocity is 0.38 meters/sec (75 fpm). Also, since the
cost of operating the exhaust fans is dependent on the pressure drop across
the beds, a more shallow bed is preferred. Therefore, a bed cross-section of
2 2
2.3 m (25 ft ) was selected for the example design. This results in a bed
depth of about 0.6 meters, and the superficial gas velocity would be approxi-
mately 0.38 meters/sec (75 fpm).
Since the expected recovery rate is 0.29 kg/min (0.63 Ib/min), each bed
is sized to adsorb 17.4 kg (37.8 Ibs) of CFC-12 during each two hour on-line
period. This requires about 721 kg (1590 Ibs) of carbon per bed, which would
3 3
occupy a volume of 1.5 m (53 ft ). For two beds the total quantity of
activated carbon purchased would be 1,442 kg (3,180 Ibs). Table 5-4
summarizes the carbon adsorption system's design parameters.
103
-------
TABLE 5-4. CARBON ADSORPTION SYSTEM DESIGN PARAMETERS
Total Gas Flowrate. m /min (cfm) 54.6 (1,900)
Gas Temperature. °C (°F) 21 (70)
CFC Loading inlet, kg/min (Ib/min) 0.300 (0.661)
CFC Concentration, g/m (ppmv) 5.49 (1070)
CFC Partial Pressure. Pa (psia) 0.77 (0.016)
Number of Beds 2
Superficial-Velocity, m/sec (fpm) 0.38 (75)
Bed area, 01 (fO 2.32 (25)
Carbon depth, m (ftl - 0.64 (2.1)
Carbon density g/cm (Ib/ft ) 0.47 (30)
Carbon working capacity for CFC-12. kg CFC/kg carbon 0.05
Carbon bed CFC removal efficiency. Z 95
Total carbon per bed. kg (Ib) 721 (1,590)
Adsorption time per cycle, min 120
Regeneration time per cycle, min 60
Cool down per cycle, min 60
Steam requirement per regeneration, kg/kg carbon 0.3
Total stream use per cycle, kg (Ibs) 216 (477)
104
-------
Carbon Bed Regeneration—
To desorb the CFC-12. and regenerate the carbon beds, three options are
available. One is to circulate a hot. inert gas through the bed to supply the
heat of desorption. Second, the hot inert gas can be combined with a reduced
pressure atmosphere in the absorber, created by a vacuum pump, to obtain high-
er recovery efficiencies. Finally, the procedure used more often and that
selected for this example, is to flow superheated, low-pressure steam upward
through the bed counter-current to the flow of CFC-laden exhaust gases during
adsorption, to strip off the CFC-12. The CFC-12 rich steam is then routed to
a water cooled heat exchanger to condense the steam.
The steam required to regenerate the beds was estimated to be 216 kg (477
Ibs) per cycle, based on a typical factor of 0.3 kg steam per kg of carbon.
Therefore, a steam supply of at least 250 kg/hr (550 Ib/hr) is required.
Capital Costs—
Total capital cost estimates for the model plant retrofit carbon adsorp-
tion/recovery system for CFC-12 are presented in Table 5-5. These figures
were developed by applying generally accepted installation and indirect cost
factors to the total purchased equipment costs. The total capital investment
for a two-bed carbon adsorption system is estimated to be $227,000. These
costs are based on first-half 1985 dollars and are assumed accurate within +/-
30 percent. Indirect capital costs account for about 35 percent of these
totals. The largest components of the purchased equipment costs are the
carbon adsorber beds and associated process equipment, and the CFC-12
compression and purification system. This latter item may not be required for
most plants. The capital costs for retrofit installations can be expected to
vary significantly, due to different plant configurations.
Annualized Operating Costs and Cost Effectiveness—
Annualized costs for operating a CFC-12 system were developed for the
model plant. These costs, and the bases used, are summarized in Table 5-6.
105
-------
TABLE 5-5. ESTIMATED CAPITAL COSTS FOR EQUIPPING A PS-FOAM SHEET EXTRUSION
PLANT WITH A CFC-12 CARBON ADSORPTION SYSTEM
Cost
($1.000)
Direct Capital
Adsorber (beds, condenser, fan, decanter, 80
control system)
Compressor System 50
Ventilation System 10
TOTAL DIRECT CAPITAL 140
Indirect Capital (Z of direct capital)
Engineering and Supervision at 10% 14
Miscellaneous Field Construction Expenses at 5% 7
Contractor Fees at 10% 14
Contingencies at 20% 28
Startup Expenses at 2% 3
Interest During Construction at 102 14
TOTAL INDIRECT CAPITAL 80
TOTAL DEPRECIABLE CAPITAL 220
Working Capital* 7
TOTAL CAPITAL INVESTMENT 227
aEstimated at 25 percent of the total direct operating and maintenance costs.
106
-------
TABLE 5-6. ESTIMATED ANNUAL OPERATING AND MAINTENANCE COSTS FOR EQUIPPING A
PS-FOAM SHEET EXTRUSION PLANT WITH A CFC-12 CARBON ADSORPTION
SYSTEM
Cost
Direct Operating and Maintenance Costs ($1,000)
Operating Labora at $13.00/hr 6
Maintenance" 4
Electricity 2
Steam 12
Process Water 2
Cooling Water __1
TOTAL DIRECT COSTS 27
Indirect Costs
Capital Recovery Factor0 37
Overheads'1 2
G&Ae A
Insurance and Property Taxes* _5
TOTAL INDIRECT COSTS 48
TOTAL OPERATING AND MAINTENANCE EXPENSES 75
CREDIT FOR RECOVERED CFC-12 (167)
OPERATING CREDIT (93)
alncludes operating labor and supervision.
''Includes maintenance labor, materials, and supervision and is estimated at 3
percent of the direct capital costs.
cEstimated at 16.275 percent of the total capital investment.
^Estimated at 38 percent of labor expenses.
Estimated at 50 percent of operating labor and 25 percent of the maintenance.
fEstimated at 2 percent of the total capital investment.
107
-------
The various categories of direct and indirect operating expenses assoc—
ated with the carbon adsorption/recovery system were estimated in terms of
irst—half 1985 dollars. Maintenance and operating costs and steam consump-
ion are the largest direct operating cost items, and these costs would in-
rease with foam output. Capital recovery, calculated for 10-year service
ife and 10 percent interest* is by far the largest single fixed cost item.
ccounting for about 50 percent of the annualized operating costs.
Also to be considered in evaluations of net operating costs and cost
ffectiveness is the credit for reclaimed blowing agent. The value of CFC-12
ecovered may vary depending upon its quality and the process requirements.
nder the most ideal situations, assuming 100 percent use of recovered CFC-12,
he model plant would save about $167,000 per year. If this material had to
e shipped off site for disposal by incineration, the added cost could be as
igh as $60,000 per year (based on $150 per barrel disposal cost).
The control cost effectiveness of a retrofitted capture and recovery
ystem for CFC-12 can be expressed as the cost (or credit) per unit weight of
FC-12 recovered, or alternatively, as the cost (or credit) per unit of CFC-12
mission averted. The cost effectiveness of a recovery system for a PS foam
lant is not only a function of the efficiency of the control system itself,
ut is dependent on the mass flow of CFC-12. For the model plant, the esti-
ated cost per unit of CFC-12 emission averted is $724 per metric ton ($650
er ton) of CFC-12 controlled or $0.72/kg ($0.33/lb). If credit is given for
he recovered CFC-12, the control cost actually becomes a credit of $912 per
etric ton ($827/ton) of CFC-12 controlled. This is equivalent to a credit of
0.91/kg ($0.41/lb) of CFC-12 emissions averted. If off-site disposal of the
aste CFC is required, the control cost will increase to $1,311 per metric ton
$1,190 per ton).
108
-------
Barriers to Implementation and Time Frame
Capture and recovery of bloving agent emissions from extruded polystyrene
foam plants using carbon adsorption represents a technically viable option for
substantially reducing CFC-12 emissions. The main barrier to implementation
is the high capital expense associated with retrofit of suitable control sys-
tems to existing foam plants.
In terms of cost effectiveness to the foam producer, installation of
carbon adsorption systems can currently be justified for perhaps a substantial
number of foam plants. This is mainly because the credit for reclaimed CFC-12
is sufficient to yield a reasonable payout period for the initial system in-
vestment. For smaller plants, or those with somewhat lower annual production,
the original investment may not be completely recoverable. Availability of
capital presents a serious problem for many small and moderate size foam
producing firms. The uncertainty of many foam producers concerning their
future market position could preclude commitment of capital that may take
years to recover.
An appropriate time frame for implementing this control technique would
be highly dependent on the structure of economic incentives or reimbursements
for plant retrofits. One way to affect this would be to cause the market
price for CFC-12 to increase markedly, thus increasing the raw material credit
for recovery, and penalizing firms for continued purchase of fresh material.
Other alternatives include tax advantages or accelerated equipment deprecia-
tion schedules.
Presuming that economic barriers could be made less prohibitive, it
should be possible to retrofit and bring control systems on-line for most
PS-foam facilities within five to seven years. This includes some time for
experimental evaluation of important design and environmental factors, as well
as additional pilot scale and full scale demonstrations.
109
-------
It is also possible that the realignment in the foam industry caused by
ae high cost of controlling blowing agent emissions will stimulate research
nvestment. Such efforts could result in the introduction of new foam pro ri-
ots and/or processes to the foam market.
NCINERATION OF PLANT EXHAUST
Destruction of chlorofluorocarbon emissions by thermal or catalytic in-
ineration is a physically possible control option. However, several crucial
robiems can be identified that limit its consideration as a technically
ractical control method. Since CFC-12 is nonflammable, high incineration
emperatures are necessary to cause thermal cracking. Also, a large volume of
xhaust air must be treated to effectively control blowing agent emissions.
his results in an excessively large fuel usage cost.
In general, nonflammable CFC compounds are not easily destroyed through
onventional incineration techniques. Although CFC—12 decomposes above 540°C
1000°F), this is only true in a reducing atmosphere, such as a fuel-rich
lame. The resulting gases contain hydrochloric (HC1) and hydrofluoric (HF)
.cids. These are secondary pollutants which are highly corrosive, and would
.ave to be scrubbed from the flame exhaust. Tests by DuPont indicated that
uch fuel—rich flames can destroy over 99 percent of the chlorofluorocarbons
•resent in typical process streams (32).
Catalytic incineration mechanisms include disproportionation of CFC-12 in
:he presence of aluaintm chloride (Aid.,) to form carbon tetrachloride (Cd^)
,nd carbon tetrafluoride (CF^). This is a relatively exotic and expensive
irocess. Under oxygen-free conditions, finely divided metallic iron at very
ligh temperatures will react with chlorofluorocarbons to form metal halides
.32). Aside from the extremely high energy costs, this latter process would
require expensive treatment of the high—volume exhaust to remove oxygen.
110
-------
It is possible to thermally crack CFC-12 at temperatures above 760°C
(1400°F), but there are no published data which characterize the residual
products of the cracking reactions. This process would require large kiln-
like equipment to treat most or all of the exhaust stream. A proposed alter-
native to direct flame incineration would be the use of a heated sand bed or
fluidized bed. No tests of such a process for CFC destruction have been re-
ported.
Each of these proposed incineration destruction techniques involve very
energy intensive processing of large volumes of exhaust air. While these
methods may very effectively destroy CFC—12, the costs would be extremely
prohibitive. Host or all of the input energy for thermal processes would be
wasted, since the flexible foam production process could not utilize the waste
heat. Because of the preponderance of negative factors, incineration tech-
niques were not pursued further in this study.
Ill
-------
SECTION 6
HYDROCARBONS AS POLYSTYRENE FOAM SHEET BLOWING AGENTS
One option that offers considerable promise in reducing CFC-12 emissions
.n the manufacture of polystyrene foam is substitution of the chlorofluoro-
:arbon with a non-ozone depleting blowing agent. Use of alternative blowing
.gents would eliminate, or significantly reduce the CFC emission associated
•ith a given PS foam operation. Currently, hydrocarbons such as n-pentane.
sopentane, or n—butane are viable candidates for replacing CFC-12 in PS foam
reduction. These options can eliminate the use of CFC-12 in this application
hereby providing 100 percent reduction in emissions of this ozone depleting
ompound.
Polystyrene foam is extruded into both board and sheet profiles. Because
jctruded PS foam board is used as an insulation material, the use of hydrocar-
ons as blowing agents would reduce the board's insulating effectiveness, and,
herefore, would not be a desirable substitute. However, with PS foam sheet,
ydrocarbons are excellent candidates for use as substitute blowing agents.
hen PS foams were first introduced in the mid-1960s, they were blown almost
xclusively with pentane. But by the late 1960s, the industry began a gradual
onversion to CFC-12 as a blowing agent. This was due primarily to the fire
azards associated.with pentane. The trend towards using nonflammable CFC-12
.s a PS foam blowing agent has continued to present, and now only the very
arge, self insurable, companies such as Mobil, tt.R. Grace, and Amoco are
till using hydrocarbons. While these companies have historically been able
o produce foamed polystyrene products safely and competitively, local ordi-
ances regulating volatile organic compound (VOC) emissions have created
ncentives for even these large companies to convert some of their facilities
ran hydrocarbons to CFCs.
112
-------
In spite of the trend away from, using hydrocarbons, it is possible to
make all thennoformable polystyrene foam sheet using a hydrocarbon such as
pentane as a blowing agent. The following paragraphs discuss the various
aspects of converting a medium sized polystyrene foam sheet manufacturing
plant from CFC-12 to pentane.
PLANT EQUIPMENT AND OPERATION MODIFICATIONS
One of the primary concerns with using pentane as a blowing agent is its
flammability. This concern is reflected in most of the changes which would
have to be made to convert a plant using CFC blowing agents into one using
pentane. Another important issue is any state, or local ordinances which
regulate volatile organic compound (VOC) emissions. Presence of VOC regula-
tions in a given area might require that a plant using pentane be equipped
with an add-on control system which allows for recovery or destruction of the
pentane. Concern over the uncertainty of future VOC regulation by states and
localities probably contributes to companies' hesitation about seriously
considering conversion to hydrocarbon blowing agents.
Some of the required facility modifications when converting from CFC-12
to pentane include: purchase and placement of the pentane tanks and their
associated pimps, piping, and instrumentation; altering wiring to insure that
electrical connections and devices would be explosion proof; purchase of non-
electric foam transport vehicles; installation of static electric discharge
devices in areas such as the film roll-up and unrolling stations; installing a
ventilation system for reducing pentane concentrations; and installing a fire
protection system (20,21). Since the CFC injection port on the extruder can
also be used for pentane injection, no major changes to the extruder would be
required (22).
In addition to modifications in the process and plant facilities, conver-
sion to pentane might require changes in plant operation. One facility
converted to pentane for a three year period in all of its PS foam sheet
113
-------
lanufacturing facilities. They found that the hazards of using pentane
-equired up to a 30 percent reduction in production operating speeds. (20).
iowever, another source indicated that no change in operation rates would be
lecessary (22).
X)NTROL EFFECTIVENESS
An advantage of pentane substitution in polystyrene foam sheet production
.s that significant reductions in CFC emissions could be realized over the
tear-term. Because pentane has been used widely in FS foam sheet
.anufacturing, the availability of this control technology is excellent. A
ubstantial number of people in the PS foam sheet industry have experience in
he use of pentane or other hydrocarbon blowing agents, and this reservoir of
jcpertise should ease the process of converting to hydrocarbons.
In terms of quantities of PS foam sheet produced, roughly 50 percent of
olystyrene foam sheet is currently blown with hydrocarbons. However, only a
ew of the largest companies produce this hydrocarbon-blown foam, and it is
robable that the numerous medium and small sized companies use CFC-12. The
rimary reason for this is that only the large companies can afford to provide
heir own fire insurance as well as extensive fire protection equipment and
•ersonnel training.
There is considerable disagreement between CFC-12 users and hydrocarbon
sers concerning the benefits of their particular blowing agent. Therefore,
here is a degree of inertia among foamers to continue using the blowing agent
hat they have been using. Companies using either blowing agent have made
onflicting claims of higher production rates, lower scrap rates, and less
xpensive product. The main objection to switching from CFC-12 to pentane is
he cost of modifications required to provide the facility with fire protec-
ion. This includes explosion-proofing all electrical equipment as well as
nstalling a fire extinguishing system (20,22,23,24,25). Further study of the
ost of fire protection in PS foam sheet plants is warranted.
114
-------
COST OF CONTROL
To examine the cost of converting a facility from CFC-12 to pentane, two
basic scenarios are examined: (1) substitution with no pentane recovery, and
(2) substitution with a pentane carbon adsorption system. Table 6-1 shows the
model plant characteristics and production parameters used to assess costs in
this study. Briefly, the plant consists of two extruders and four thermo-
formers. Each extruder produces 340 Kg/hr (750 Ibs/hr) of PS foam sheet, and
the total production is A100 metric tons per year (9.0 million Ibs/yr).
The estimated cost for controlling CFC-12 emissions through substitution
with pentane is strongly affected by the savings acquired through the use of a
smaller quantity of a cheaper blowing agent. Savings occur because pentane
costs roughly 77 percent less than CFC-12, and approximately 20 percent less
blowing agent is required per pound of foam product.
Table 6-2 shows the estimated capital cost to convert the model A, 100
metric tons per year CFC-12 polystyrene foam sheet facility to a pentane using
facility. The majority of the estimated $977,000 modifications are associated
with fire and explosion protection devices. Table 6-3 presents the operating
and maintenance costs for the same facility. The capital costs are annualized
with a capital recovery factor. Assuming a credit for the blowing agent cost
differential and the reduced scrap, the realized net annual operating and
maintenance costs are $33.000.
These costs are adversely affected if regulations require the addition of
a carbon adsorption system for pentane recovery. Table 6-A details the
capital cost of a carbon adsorption system designed for the model facility.
This system is similar to the one described in Section 5 and would, be used to
capture pentane emissions from the extruder and from the regrinder and regrind
storage. The estimated total annual cost for the carbon adsorption system is
$86,000 (see Table 6-5) which is equivalent to a cost of approximately
$0.6A/kg ($0.29/lb) of CFC-12 emission averted. The annualized costs for the
115
-------
TABLE 6-1. MODEL POLYSTYRENE EXTRUDED FOAM SHEET PLANT
OPERATING PARAMETERS
Annual Production, mt (Ibs.)
Production Rate, kg/hr (Ib/hr)
Number of Extruders
Foam Sheet Web Width, a (ft)
Extrudate Velocity, m/min (ft/min)
Typical Initial Foam Formulation
Polystyrene
Blowing Agent
Additives
Number of Thermoformers
Percent scrap in Feed
4.100
680
2 S 340 kg/hr
each
1.2
0.6
CFC-12 Blown
93% w
6Z w
1Z w
4
35
(9 million)
(1500)
(2 S 750 Ib/hr)
each
(4)
(2)
Pentane-Blown
94Z w
5Z w
1Z w
4
25
116
-------
TABLE 6-2. ESTIMATED CAPITAL COSTS FOR EQUIPPING A PS-FOAM SHEET EXTRUSION
PLANT WITH A PENTANE BLOWING AGENT SYSTEM
(Cost in $1,000. mid-1985)
Cost
Direct Capital
Pentane Tank & Piping 42
Explosion Proof Wiring 195
3 Non-electric Foam Transport Vehicles 45
Ventilation System 471
Fire Protection System 210
TOTAL DEPRECIABLE CAPITAL3 963
Working Capitalb 15
TOTAL CAPITAL INVESTMENT 978
a Installed cost which includes indirect costs of engineering, supervision,
construction fees, interest during construction and contingencies.
Estimated at 25 percent of the total direct operating and maintenance costs.
117
-------
TABLE 6-3. ESTIMATED OPERATING AND MAINTENANCE COSTS FOR EQUIPPING A
PS-FOAM SHEET EXTRUSION PLANT WITH A PENTANE BLOWING AGENT
SYSTEM (Cost in $1.000. mid-1985)
Cost
Added Direct Operating and Maintenance Costs
Operating Labor8 at $13.00/hr 30
Maintenance 29
TOTAL DIRECT COSTS 59
Indirect Costs
Capital Recovery Factor0 159
Overheads 11
22
Insurance and Property Taxes 20
TOTAL INDIRECT COSTS 212
CREDITS
Bloving Agent Differential (162)
Scrap Reduction (28% of Total Direct and Indirect Costs) (76)
TOTAL OPERATING AND MAINTENANCE EXPENSES WITH CREDITS 33
^Includes operating labor and supervision.
Includes maintenance labor, materials, and supervision and is estimated at 3
percent of the direct capital costs.
^Estimated at 16.275 percent of tbe total capital investment.
estimated at 38 percent of labor expenses.
^Estimated at 50 percent of operating labor and 25 percent of tbe maintenance.
Estimated at 2 percent of the total capital investment.
118
-------
TABLE 6-4. ESTIMATED CAPITAL COSTS FOR A PS-FOAM SHEET EXTRUSION
PLANT WITH A CARBON ADSORPTION SYSTEM FOR PENTANE RECOVERY
(Cost in $1,000, mid-1985)
Cost
Direct Capital
Adsorbers
Organics Purification 170
Ventilation System
TOTAL DIRECT CAPITAL 170
Indirect Capital (% of direct capital)
Engineering and Supervision at 10% 17
Misc. Field Construction Expenses at 5% 9
Contractor Fees at 102 17
Contingencies at 20% 34
Startup Expenses at 2% 3
Interest During Construction at 10% jj
TOTAL INDIRECT CAPITAL 97
TOTAL DEPRECIABLE CAPITAL 267
Working Capital3 8
TOTAL CAPITAL INVESTMENT 275
aEstimated at 25 percent of the total direct operating and maintenance costs.
119
-------
TABLE 6-5. ESTIMATED OPERATING AND MAINTENANCE COSTS FOR EQUIPPING A PS-FOAM
SHEET EXTRUSION PLANT WITH A PENTANE CARBON ADSORPTION SYSTEM
(Cost in $1.000. mid-1985)
Cost
Direct Operating and Maintenance Costs
Operating Labor* at $13.00/hr. 6
Maintenance 5
Electricity 12
Steam 4
Process water 2
Cooling water __1
TOTAL DIRECT COSTS 30
Indirect Costs
Capital Recovery Factor0 45
Overheads'1 2
G&Ae
Insurance and Property Taxes —
TOTAL INDIRECT COSTS 56
TOTAL OPERATING AND MAINTENANCE EXPENSES 86
flncludes operating labor and supervision.
Includes maintenance labor, materials, and supervision and is estimated at 3
percent of the direct capital costs.
^Estimated at 16.275 percent of the total capital investment.
^Estimated at 38 percent of labor expenses.
jtimated at 50 percent of operating labor and 25 percent of the maintenance.
Jtimated at 2 percent of the total capital investment.
120
-------
carbon adsorption system do not include a credit for the recovered pentane.
The pentane could be reused as a blowing agent if the quality of the recovered
product is adequate. If not, the pentane could be burned in an on-site boiler
or be disposed off-site at an added cost. Another possibility not examined in
this report, but warranting further study is incineration of the pentane
contained in the plant exhaust.
HEALTH AND SAFETY FACTORS
Pentanes are only slightly toxic and are classified as simple asphyxiants
and anesthetics. The TLV for the time-weighted average eight hour exposure to
pentanes is 600 ppm or 1800 mg/m3 (51 mg/SCF); the short-term (15 minute)
3
exposure limit is 750 ppm or 2250 mg/m (64 mg/SCF). The major safety risk of
pentanes is their high flammability which is due in part to their volatility.
Adequate ventilation and isolation from sources of heat and ignition are
necessary to minimize the risk of fire and explosion.
n—Butane is a colorless, flammable, nontoxic gas. It is classified as a
simple asphyxiant and an irritant. At high concentrations, it is an anes-
thetic, and will cause drowsiness in a short time in concentrations of one
volume percent. Two hour exposures at concentrations of up to five volume
percent cause no apparent injuries. The recommended TLV is 600 ppm. Like the
pentanes, n-butane is extremely flammable and precautions should be taken to
prevent fire and explosion. Table 6-6 provides the various health effect.
chemical, and physical property data for CFC-12. n-pentane, isopentane, and
n—butane.
CURRENT STATUS
Originally, all PS foams were blown exclusively with pentane. However.
partly because of the fire hazards associated with pentane, a conversion to
CFC-12 began in about 1967. The extent to which this conversion has pro-
gressed is subject to differing estimates. A 1980 Rand report indicates that
121
-------
TABLE 6-6. PHYSICAL PROPERTIES OF CFC-12 AND HYDROCARBON BLOWING AGENTS
CFC-12 n-Pentane Isopentane n-Butane
Formula
MW 120.91 72.15 72.17 58.12
Boiling Point (°C) -29.8 36.1 27.8 -1
Fusion Point (°C) -158 -130 -159.9 -138
Specific Gravity (g/cc) 1.311 0.626 0.6201 0.584
Vapor Density (air = 1) 4.2 2.48 2.6 2.0
Vapor Pressure (atm) 5ei6°C 0.526ei8.5°C 1S280C 3.5@38°C
Ignition Temperature C°C) NA 260 420 NA
Flashpoint (°C) non-flammable -40 -57 -73
Upper Explosion Limit. % NA 7.8 8.3 8.5
Lover Explosion Limit. % NA 1.5 1.4 1.9
Price
(rail car quantities). $/lb 0.74 0.17 0.18 NA
OSHA PEL (ppm) 1000 1000 — —
TLV (ppm) 1000 600 600 600
NA = Not. available.
Source: (27,28.29,30,31)
122
-------
by 1973, only 45 to 50 percent of the PS foams produced were blown with
pentane. The same report shows that this market share dwindled further to 35
percent by 1977 (13). Recent communications with industry, however, have
indicated that a very large share of the blowing agents used for PS foam sheet
are hydrocarbons (18,23,26).
Because pentane is flammable and there are concerns with VOC emissions
regulations, many polystyrene-foam extrusion plants have been converted from
using hydrocarbon blowing agents to using CFC blowing agents. Contacts with
industry have indicated that very few plants have been converted from CFC to
pentane. However, several industry contacts indicated that the three major
polystyrene foam extruders (Mobil, Amoco, and Grace) still use large quanti-
ties of the hydrocarbon blowing agents isopentane, butane, and n-pentane,
respectively. These three companies alone are estimated to produce 70 to 90
percent of all polystyrene foam sheet (21,22,26). If this is so, then it is
probable that a majority of the polystyrene-foam blowing agent market is still
held by hydrocarbons. The fact that a large fraction of the PS foam produced
is blown with hydrocarbons illustrates the viability of pentane blowing
agents, flammability notwithstanding.
ECONOMIC FACTORS
There are many economic factors that can influence the selection of a
particular PS foam blowing agent. While foam quality is of importance,
evidence indicates that foams produced with hydrocarbons are sufficiently
similar in quality to those foamed with CFC-12. The blowing agent of choice
for small and medium producers is CFC-12 because of the fire hazards of
hydrocarbons. These hazards not only drive up the cost of insuring the
facility, they mandate the expensive plant retrofitting discussed earlier in
this section.
Several important economic considerations regarding the control of CFC-12
emissions by hydrocarbons such as pentane can be identified. These include:
123
-------
• net raw material cost savings,
• extrusion and thennoforming production rates,
• costs for additional plant ventilation,
• costs for carbon adsorption to control pentane emissions, and
• personnel requirements and additional training.
Jfhile all of these considerations are more or less interrelated with the
specific characteristics of a given foam manufacturing plant, there are two
additional considerations over which the foam manufacturer has no control.
Ihese are the cost of pentane and the special needs and requirements of the
foam end-use markets. A dramatic rise in the cost of pentane relative to
3FC-12 would decrease the economic incentive for a conversion. Also, a
specific end user might specify CFC-12 as a blowing agent because of their
^articular needs. This would also be a disincentive for conversion to pen-
:ane.
Contact with industry has made it evident that both foam producers using
2FC-12 and those using hydrocarbons feel that they cannot convert their
acility and still manufacture foams economically. However, since foams are
>roduced economically and competitively with both types of blowing agent it
••eerns possible that a conversion could be made.
ARRIERS TO IMPLEMENTATION
From an overall perspective of the United States foam market, there
ppear to be no extreme technical or economic barriers to near-term impleman-
ation of pentane substitution as a means of controlling CFC-12 emissions. An
sception would be in localities where VOC regulations would prohibit or limit
he use of hydrocarbons. Future voluntary substitution of pentane will
robably not occur given current market conditions, because manufacturers may
124
-------
not be willing to use flammable pentane blowing agents, and they may be
skeptical about possible cost savings from switching to pentane. Also, there
may be potential market decline because end-users may be unwilling to use
pentane blown product.
125
-------
SECTION 7
ALTERNATIVE CFC BLOWING AGENTS
The two characteristics of chlorofluorocarbons that can cause depletion
f atmospheric ozone are their high stability and the presence of chlorine in
he CFC molecule. Therefore, the ozone depletion potential of this particular
lass of chemicals can be neutralized by making the CFC molecule marginally
ess stable, so that it would not survive long enough to reach the upper
tmosphere. Conversely, it should not be so uns.table as to degrade in the
over atmosphere and contribute to smog. Hydrocarbon-containing CFC compounds
ave been identified as having satisfactory intermediate stability because
hey degrade to a large extent in the troposphere through reaction with
ydroxyl radicals.
Alternatively, if chlorine could be reduced or omitted from the molecule
he resulting species could not release the chlorine radicals that are hypoth-
sized to react with the stratospheric ozone. Fluorocarbon compounds, which
o not contain chlorine, may be suitable substitutes for blowing agents such
s CFC-11 and CFC-12, since the chain reaction involved in the ozone depletion
s more quickly terminated.
An ideal potential replacement for CFC blowing agents needs to have the
oilowing characteristics:
• Product, safety, and toxicity performances competitive
with that of commercial CFCs;
• Reduced or eliminated ozone depletion potential;
• Cost effectiveness with respect to its value and use; and
126
-------
• Commercial manufacturing process which is available or can
be developed.
Additionally, the CFC substitute should have the same physical foaming
parameters as CFC-11 and CFC-12. These include boiling point, thermal con-
ductivity, gas efficiency, diffusion rate from product, and solubility in
formulation and product.
Polyurethane and polyisocyanurate insulation foams are generated through
the action of a physical blowing agent (CFC-11). Some processes also use
CFC-12 as a supplementary blowing agent, but its use is declining. Foaming
occurs when the heat of the polymerization reaction vaporizes the CFC-11. The
use of CFC blowing agents creates a closed cell structure. The closed cells
give the foam a rigid, yet light-weight structure, and the CFCs trapped in the
numerous tiny closed cells provide superior insulating properties.
Historically, much of the extruded polystyrene and other nonpolyurethane
foam products have been blown with hydrocarbons such as n-pentane and
isopentane, and to a lesser extent, butane. A variety of CFCs have been used
either alone as the primary blowing agent, or in a mixture with other CFCs or
pent an es. Besides n-pentane and isopentane. CFC-12 is the most commonly used
blowing agent for the nonpolyurethane foams. Additionally, gases such as
carbon dioxide are sometimes used in conjunction with hydrocarbons and CFCs.
Smaller quantities of CFC-11. CFC-114. CFC-113. and CFC-115 are also used (5).
RIGID POLYURETHANE FOAM BLOWING AGENTS
For polyurethane foams, the most commonly used CFC blowing agent is
CFC-11. It has a variety of chemical and physical properties which make it
desirable as a blowing agent, and a potential substitute would need to have
similar properties in order to serve suitably as a replacement. Since the
purpose of seeking alternatives to CFC-11 is mainly to reduce the potential
for harming the earth's ozone layer, the first criteria for judging the
127
-------
uitability of an alternate is its ozone depletion factor. This factor
ndicates the potential for ozone depletion relative to that of CFC-11 (with
n ozone depletion factor of 1.0).
Since a majority of the blowing agent used in rigid polyurethane foam
anufacture is trapped in cells and banked for extremely long periods of time,
ubstitution with low ozone—depleting compounds is an action which would have
ong-term effects on the fate of stratospheric ozone. However, before a
ubstitute blowing agent can begin to reduce the potential threat to the ozone
ayer, it must be widely accepted and adopted for use by the rigid
olyurethane foam industry. This acceptance is dependent upon the alternate's
osts and its performance during processing as well as in the final foam
roduct.
recessing Considerations
One of the primary characteristics of a physical blowing agent is its
elative stability. For purposes of consistent product quality, it is essen-
ial that the blowing agent does not react with any of the foam ingredients.
t is equally important that the blowing agent does not decompose spontan-
eously (44) and, in the case of insulating foams, the foam must retain its
FC-11 to maintain the advantageous thermal properties for long periods of
ime.
Thermal properties are also important during foam processing. A blowing
gent with a low boiling point and a high latent heat of vaporization acts as
heat sink and protects the foam from high temperatures which can be gener-
ted by the exothermic polymerization reaction. Some polyurethane foams can
corch, melt, or burn if temperatures become too high. Unlike polyurethane
cams, the chemical structure of polyisocyanurate foams makes them quite
esistant to scorching and burning.
128
-------
To be effective as a blowing agent, a compound must have an appropriate
vapor pressure in the foam ingredient solution. The vapor pressure can be
predicted from the boiling point and the solvent power of the candidate. If
the boiling point is too high or the solvent power too strong, the blowing
agent will tend to remain in the polymer, making the product soft or even
soggy. Conversely, a very low boiling point will cause the blowing agent to
vaporize before the foam polymer is rigid, which will result in collapsed
cells. The blowing agent should not boil from solution below about 30°C
(86°F) and must boil before reaching 60 to 80°C (140 to 176°F) (44).
The quantity of blowing agent required to make a given foam is primarily
a function of the agent molecular weight and gas efficiency (44). For a
blowing agent, the gas efficiency equals the contribution to cell volume
divided by the ideal gas volume resulting from complete vaporization of the
blowing agent. A good rigid foam blowing agent will have a gas efficiency
greater than 90 percent.
For rigid polyurethane foams, a large majority of the blowing agent is
incorporated into the foam. Additionally, the blowing agent trapped in the
foam cells tends to escape very slowly (depending upon its diffusivity through
the polymer) from the foam product. Therefore, in the manufacturing plant,
the limited amounts of blowing agents which would be released during
processing could be removed by proper ventilation. The only possible
exception is in processing operations where large amounts of foam are cut or
handled in such a way as to release significant amounts of the blowing agents.
For this reason, the toxicity and flammability of a blowing agent are
relatively minor concerns from the standpoint of the health and safety of the
foam workers. However, since these foams are used as insulation materials in
such applications as refrigerators and houses, toxicity and flammability are
of concern. In the home environment, exposure levels are much lower than
those in industrial settings because of the long-term chronic exposure which
would occur in the household.
129
-------
Product Considerations
A large majority of rigid polyurethane foams are used as insulation
naterials. Their effectiveness as insulation is dependent upon the insulating
abilities of the gas in the foam cells, the polyurethane matrix which cost-
prises the cell walls, and on the density of the foam. However, the polymer
in the cell walls comprises only a small fraction of the foams total volume;
therefore, the insulating properties of the cell gases are of critical impor-
tance. The insulating ability of a blowing agent is a function of both its
thermal conductivity and its retention in the foam. To be effective as a
rigid—polyurethane insulating-foam blowing agent, a compound must have both a
Low thermal conductivity and a low diffusivity. The influx of air into the
foam cells is also an important factor in reducing the insulating properties.
sut it is independent of the nature of the blowing agent.
Loss of the foam's insulating ability may disrupt the building trade
narket. refrigeration appliance trade, and refrigerated transport. Some
Building codes rely on the existence of rigid polyurethane sheathing materials
for standards related to insulation requirements. Some states, such as
3alifornia, have promulgated laws requiring increased energy efficiency in
aome refrigeration appliances. Without the insulating capability possible
*ith the present rigid polyurethane foams, walls of refrigerators may have to
DC thickened to accommodate more insulation material. Interior capacity would
ae reduced due to space restrictions on exterior dimensions. A similar
scenario might result in the refrigerated transport industry, where reduced
Interior capacity would result in higher transport costs.
Implementation
Two final considerations are the implementation time frame and the
xLowing agent cost. These are probably the most difficult to predict because
Doth are heavily dependent upon the manufacturer of the potential compound.
iowever, the time frame for adaptation by the foam producers is more easily
130
-------
predicted. In general, if a new blowing agent meets the processing and
product standards of the foam manufacturing industry, it can be adopted with
little delay; however, if it fails to meet these standards, it will be quickly
rejected. Three alternative CFCs have been identified as potential replace-
ments for the CFC-11 used in rigid polyurethane foams. These are CFC-123,
CFC-133a, and CFC-141b.
CFC-123
CFC-123 (2,2-dichloro-l,1,1-trifluoroethane) is a promising candidate
substitute for CFC-11 as a rigid polyurethane blowing agent. However, it is a
newer chlorofluorocarbon which is not currently available in commercial
quantities. This compound is expected to have a low ozone depletion factor.
Some development work will probably be required by the polyol manufacturers to
compensate for the increased solvent power of the alternative CFCs. There are
already suitable polyols, at least on an experimental basis, so this should
take little time. No change in the isocyanate is required.
The performance of CFC-123 during foam processing, is very similar to
that of CFC-11. The boiling point of CFC-123 is 28°C (82°F), which is within
the acceptable range for a rigid polyurethane foam blowing agent. Its solvent
action on polyurethane, like that of CFC-11, is moderate. Its molecular
weight is 152.9, and its gas efficiency is 95 percent of the theoretical
3
value. The quantity of CFC-123 required to blow a 0.033 g/cc (2 Ib/ft )
poured foam is 27 parts per 100 parts polyol. Sprayed foams require up to 50
parts per 100 parts polyol. This is more than double the 22 parts per 100
parts polyol required of CFC-11.
Because its thermal conductivity is 20 percent higher than that of
CFC-11, the insulating properties of polyurethane foams blown with CFC-123
would be somewhat less satisfactory. However, the diffusion rate for this CFC
is slow; therefore, the foam's insulation properties should degrade no faster
than those of CFC-11 blown foams. In tests for acute and short term toxicity,
131
-------
DuPont has found CFC-123 to have a low toxicity. Further, this blowing agent
is rated as nonflammable.
Some limited testing of CFC-123 as a blowing agent for rigid polyurethane
foams has revealed both positive and negative results. As expected, CFC-123
exhibited good miscibility with polyols, while having an acceptable boiling
point for foam production. However, the degree of flowability of the foam
produced using CFC-123 was very poor. This may prohibit foams blown with
CFC-123 from being considered alternatives for rigid foams which are poured or
sprayed. It was also concluded during testing that foams produced with
CFC-123 had an unacceptably high initial thermal conductivity. Clearly, more
comprehensive testing of CFC-123 and mixtures including other CFCs will be
necessary to establish the extent of potential application of CFC-123 as an
alternative blowing agent.
CFC-141b
CFC-lAlb (1,1-dichloro-l-fluoroethane) is another potential replacement
for CFC-11 as a rigid polyurethane foam blowing agent. A manufacturing
process does exist for CFC-lAlb, though it is considered developmental (46).
Its ozone depletion factor is expected to be low. However, this blowing agent
has some drawbacks with respect to its processing and product performance.
tfhile its boiling point of 32°C (93°F) is within the desirable range, its
solvent action is rated as high, so there is the possibility that CFC-lAlb
might cause the foams to be soft. Its molecular weight is 117.0, and its gas
efficiency is 95 percent of the theoretical value. The quantity of CFC-lAlb
required to blow a 0.033 g/cc (2 Ib/ft ) foam is 20 parts per 100 parts
polyol. This is about 2 parts/100 parts polyol less than is required of
3FC-11.
The thermal conductivity of CFC-lAlb is 18 percent higher than that of
3FC-11. so the foams produced with CFC-lAlb would have lower thermal effi-
ciency. However, this blowing agent's low diffusivity through polyurethane is
132
-------
similar to that of CFC-11; therefore, long term deterioration of insulating
efficiency of CFC-141b blown foams should occur no faster than for foams blown
with CFC-11.
The primary problem with CFC-141b is its uncertain toxicity and flamma-
bility. This CFC is considered to be a weak mutagen. As mentioned earlier,
most of the blowing agent is trapped in the foam for an extended period of
time; therefore, toxicity concerns would arise during mixing and handling of
the blowing agent or during foam cutting operations where large quantities of
foam cells are being ruptured. CFC-lAlb is flammable, however, the flame is
weak and easily suppressed, so explosion is unlikely. The small flammability
potential may not be a problem during manufacturing, but the flammability of
the product itself is a concern to manufacturers. Rigid polyurethane and
polyisocyanurate foams have been considered exceptional in their ability to
retard flame. Use of a flammable blowing agent would defeat this advantage.
CFC-133a
The last, and probably least desirable of the three rigid polyurethane
foam blowing agents under consideration in this report is CFC-133a
(l-chloro-2,2,2-trifluoroethane). No commercial manufacturing process for
this blowing agent is currently available in the U.S. although CFC-133a has
been commercially produced as a chemical intermediate in the U.K. for several
years (46). Its ozone depletion factor is expected to be low. However, this
alternative also has limitations which adversely affect its suitability as a
rigid polyurethane foam blowing agent.
The boiling point of CFC-133a is 6.1°C (43°F), and it has a strong
solvent action on polyurethane. From a processing standpoint, these two
factors could cause the foam product to be inferior or completely unsuitable.
The low boiling point would tend to cause the blowing agent to foam prior to
completion of polymerization which could result in a collapsed foam. The
solvent action could cause the agent to remain within the polymer matrix.
133
-------
thereby producing a softening effect. Further. CFC-133a has a gas efficiency
of only 90 percent. This is five percent lower than that of CFC-11; however.
o
the quantity of CFC-133a required to blow a 0.033 g/cc (2 Ib/ft ) foam is 21
parts per 100 parts polyol. This is about 1 part/100 parts polyol less than
is required of CFC-11.
The thermal conductivity of CFC-133a is 22 percent higher than that of
CFC-11, so the foams produced with CFC-133a would have lower thermal effi-
ciency. However, this blowing agent's low diffusivity through polyurethane is
similar to that of CFC-11; therefore, long term deterioration of insulating
efficiency of CFC-133a blown foams should occur no faster than for foams blown
with CFC-11. During limited testing of foams blown with CFC-133a, insulating
ability was found to be satisfactory; however, it was slightly lower than that
of CFC-11 blown foams. In contrast to CFC-123. the flow characteristics of
foams blown with CFC-133a were acceptable.
The major drawback to use of CFC-133a as a rigid polyurethane foam
blowing agent is its relatively high toxicity. This CFC is considered to be
embryotoxic. Toxicity concerns would be greatest during mixing and handling
of the blowing agent or during foam cutting operations where large quantities
of foam cells are being ruptured. This blowing agent is considered to be
nonflammable.
Conclusions for Rigid Polyurethane Foam Blowing Agents
To evaluate the suitability of a potential blowing agent for rigid
polyurethane foams, a number of physical and chemical characteristics need to
be considered. Table 7-1 summarizes the various characteristics of the CFCs
which were considered as alternative blowing agents.
CFC-123 is probably a good alternative to CFC-11 as a rigid polyurethane
blowing agent. The processing and product characteristics of this alternative
closely resemble those of CFC-11, yet the ozone depletion factor of CFC-123 is
134
-------
TABLE 7-1. EVALUATION FACTORS FOR SUBSTITUTE RIGID POLYURETHANE FOAM BLOWING AGENTS
u>
Ul
Alternative CFC Blowing Agents
Factors
Reactivity with Ingredients
Stability
Boiling Point, °C (°F)
Solvent Power
Gas Efficiency (% of theory)
Molecular Weight
Quantity for 0.033 g/cc (2 Ib/ft
Foam (parts/100 parts polyol)
Thermal Conductivity W/m-°C
(Btu/hr-ft-°F)
Diffusivity Through Polymer
Toxicity
Flammability
Ozone Depletion Factor
CFC-11
None
Stable
23.8 (74.8)
Moderate
95
137.4
22
0.0078
(0.0045)
Low
Low
Non-
flammable
1.0
CFC-123
None
Stable
28 (82.4)
Moderate
95
152.9
27
0.0093
(0.0054)
Low
Low
Non-
flammable
Low
CFC-141b
None
Stable
32 (89.6)
Strong
95
117.0
20
0.0092
(0.0053)
Low
Potentially
Mutagenic
Slightly
flammable
Low
CFC-133a
None
Stable
6.1 (43.0)
Strong
90
118.5
21
0.0095
(0.0055)
Low
Embryotoxic
Non-
flammable
Low
Note that only the Ames test results have reported this result. Further testing is required before
conclusions can be drawn.
These estimates are made qualitatively relative to CFC-11.
"Use of CFC blowing agent in sprayed applications can be nearly double these
amounts due to higher foam manufacturing losses.
-------
ixpected to be much lower than that of CFC-11. One disadvantage of using
TC-123 is that the foam has a slightly lower insulating ability. The other
JLternatives, CFC-141b and CFC-133a. may not be suitable blowing agents
•ecause of their toxicity and their strong solvent action. An additional
irawback to CFC-133a is its low boiling point which could compromise foam
uality. In general, the economic competitiveness of foams blown with more
ixpensive substitute CFCs would have to be examined relative to possible
J-ternative insulation products such as fiberglass board or expandable poly-
:tyrene bead board.
Once a suitable alternative agent is available, development work will
>robably be required by the polyol manufacturers to compensate for the in-
xeased solvent power of the alternative CFCs. There are already suitable
>olyols, at least on an experimental basis, which can increase cros si inking
lensity and offset some problems. No change in the isocyanate is required and
10 significant equipment changes are necessary. Bench-scale experimentation.
is ing very modest amounts of blowing agent means that industry evaluations can
>e done on pilot plant quantities and need not await full commercial produc-
ion. In rigid insulating foams, the manufacturer would need considerable
:ime to evaluate the aging properties of the product. A total of two years in
tddition to blowing agent development are predicted for product development.
•OLYSTYKENE FOAM BLOWING AGENTS
Extruded thermoplastic foams, such as polystyrene foams, use a variety of
•lowing agents including both hydrocarbons and chlorofluorocarbons. For
>olystyrene foamed sheet products, the most commonly used hydrocarbon blowing
igent is pentane and the most commonly used chlorof luorocarbon is CFC-12.
'olystyrene boardstock products are blown almost exclusively with CFC-12.
ince hydrocarbons, such as pentane, are not suspected to be depleters of
:tratospheric ozone, this section will focus on substitutes for CFC-12. A
-ariety of chemical and physical properties have made this compound desirable
is a blowing agent for polystyrene foams, and a potential substitute
136
-------
would need to have similar properties in order to serve suitably as a replace-
ment. This is especially important for polystyrene boardstock products,
which, like rigid polyurethane boardstock products, depend upon CFCs for
superior insulating properties.
Unlike rigid polyurethane foams, most polystyrene foams do not retain
their blowing agents for an extended period of time. Faster diffusion of CFC
occurs primarily because the polystyrene foam products are thinner (e.g.,
sheet and film less than 2.5 cm (1 inch) thick). For the most part, any
blowing agent incorporated into polystyrene foam sheet during manufacture will
be emitted within a year. On the other hand, polystyrene boardstock, which
may be as thick as 5.1 cm (2 inches) or more, will retain CFC-12 much longer.
The half-life of CFC-12 in such products has been estimated to extend greater
than 40 years.
Because of prompt emissions from the sheet products, use of low ozone
depleting CFCs as blowing agent substitutes for CFC-12 can provide short term
reductions in the potential threat to the stratospheric ozone layer. However,
the substitute must be widely accepted and adopted for use by the polystyrene
foam industry. This acceptance is dependent upon the alternate's cost, per-
formance during processing, and ability to produce a quality final product.
Processing Considerations
The blowing agent for polystyrene foam should be chemically stable under
the conditions present during polystyrene manufacturing. For purposes of
consistent product quality, it is essential that the blowing agent does not
react with any of the foam ingredients. It is equally important that the
blowing agent is not easily thermally decomposed (44).
To be effective as a blowing agent, a compound must have an appropriate
vapor pressure in the molten resin at the point of extrusion. In most cases,
this vapor pressure should be at least 670 psia. This limits blowing agents
137
-------
or most resins to those with boiling points between -40°C to +50°C (-40°F to
122°F). If the boiling point is too low, the blowing agent would not be an
asily compressed vapor; therefore, it would be difficult to meter into the
jctruder. Conversely, if the boiling point is too high, the vapor bubbles
ill expand too slowly or not at all.
Because polystyrene sheet thermoforming operations require the presence
>f a blowing agent in the foam, the permeability of the blowing agent through
he polymer is an important factor. Permeability is a function of the blowing
.gent's diffusivity through the polymer, its solubility in the polymer, aging
haracteristics, and rate of air infusion. If either the diffusivity or the
olubility is too high, thermoforming will be difficult, because there will
ot be enough blowing agent retained in the foam cells. High solubility
.nd/or diffusivity would also make potential substitutes unsuitable for
anufacture of polystyrene insulating boardstock. If the CFC escapes through
he foam cells, the valuable insulating properties would be lost. In fact,
ecause most of the blowing agent should be retained in the foam for the
ntire life of the project (i.e., 50 years or more), diffusion rates should be
exy small to ensure long-term product performance.
The quantity of blowing agent required to make a given foam is a function
f the agent's molecular weight and gas efficiency (44). For a blowing agent,
he gas efficiency equals the contribution to cell volume divided by the ideal
as volume. A good blowing agent for polystyrene foam will have a gas effi-
iency greater than 90 percent.
Because a majority of the blowing agent is emitted in foam extrusion and
heet thermofozming plants, the primary fire hazards associated with the use
f a flammable (i.e.. hydrocarbon) blowing agent are encountered in the sheet
anufacturing facilities. In fact, the flammability of the foam product is
.ore a function of the flammability of the polymer than that of the blowing
.gent trapped in the foam cells (45). Although it is certainly preferable
hat a blowing agent be nonflammable, it is possible to safely manufacture
138
-------
foams with a flammable blowing agent given proper equipment and sufficiently
trained personnel. This is supported by the fact that some major producers of
thermoformable polystyrene foam sheet use hydrocarbons as their primary
blowing agents. Hydrocarbons are many times more flammable than the
alternative CFCs discussed in this section.
Product Considerations
Most polystyrene foam sheet is used for packaging or serving food prod-
ucts. Meat trays, egg cartons, hamburger shells, and disposable plates are
examples of this application. Because some blowing agent is retained in the
final foam product and these products come in intimate contact with food-
stuffs, the FDA must approve any new chemical which would be used as a blowing
agent. Prior to such approval, a candidate substitute blowing agent would
have to undergo extensive toxicity testing, and even a slight degree of
toxicity would probably jeopardize the acceptance of a potential alternative
CFC (45).
Polystyrene foam boardstock is used primarily as an insulating material
for residential and commercial structures. In these applications, polystyrene
boardstock has the advantage of high insulating quality (per thickness) due to
the CFC vapor trapped in the cells. Of course, an alternative blowing agent
with lower insulating capability (i.e.. higher thermal conductivity) could be
used, but the material's competitive advantage would be lessened in the
building materials market. Thus, an optimum substitute would possess
insulating qualities similar to or better than those of CFC-12.
Impl ement at i on
Two final considerations are the implementation time frame and the blow-
ing agent cost. These are probably the most difficult to predict because both
are heavily dependant upon regulatory considerations and the chemical manufac-
tures' willingness to produce new blowing agents. However, the time frame for
139
-------
adaptation by the foam producers is more easily predicted. Because full-scale
experimentation is costly and requires full-scale production equipment and
large quantities of raw materials, the evaluation by industry of alternative
polystyrene blowing agents will be dependent on the availability of the alter-
native agent. Four alternative CFCs have been identified as potential
replacements for the CFC-12 used in polystyrene foams. These are CFC-22,
CFC-124. FC-l34a. and CFC-l42b.
CFC-22
A currently available chemical which might successfully be used as a
polystyrene foam blowing agent is CFC-22. Its boiling point is -40.8°C
(-41.4°F), which is quite low. but may be acceptable. Substances with boiling
points much lower than -40°C (-40°F) may be difficult to meter into the
extruder, because they are difficult to compress to a liquid state. Test
results reporting the amount of CFC-22 required to blow polystyrene foam, and
the gas efficiency were not found. It does, however, have a low ozone
depletion factor.
The solvent power of CFC-22 is quite low. but its diffusivity through
polymer materials is high. This coupled with the fact that its thermal
conductivity is 9 percent higher than CFC-12 make CFC-22 a poor choice as a
blowing agent for polystyrene boardstock insulating foam. The high diffus-
ivity of CFC-22 may make thermoforming difficult also. It does have the
advantage of being a safe chemical; both non-toxic and non-flammable.
SFC-124
The chemical and physical properties of CFC-124 (2-chloro-l.1,1,2-
:etrafluoroethane) indicate that it might be a suitable replacement for CFC-12
as a polystyrene foam blowing agent. However, it is a new chlorofluorocarbon
for which a manufacturing process has not yet been developed. This compound
is expected to have a low ozone depletion factor. The boiling point of this
140
-------
CFC is -11°C (12.2°F) which is within the acceptable range for a polystyrene
blowing agent. Its solvent power and diffusivity are both low, so there
should be retention of the agent in the foam cells. The molecular weight of
this CFC is 136.5, and its gas efficiency is 90 percent of the theoretical
value. The quantity of CFC-124 required to blow a 5 Ib/ft foam is 6 parts
per 100 parts resin. This is about 20 percent more CFC required by weight
than is required with a CFC-12 formulation.
Because the thermal conductivity of CFC-124 is six percent higher than
that of CFC-12. the insulating properties of polystyrene foams blown with
CFC-124 will be less satisfactory. This may not be a factor for most
polystyrene sheet foam because insulation is not critical; however, this may
make it less attractive as a boardstock blowing agent. Additionally, the
diffusion rate for this CFC is slow; therefore, the foam's insulation proper-
ties should degrade no faster than those of CFC-12 blown foams. In tests for
acute and short term toxicity. DuPont has found CFC-124 to have a low tox-
icity. Further, this blowing agent is rated as nonflammable.
FC134a
FC-134a (1.1,1,2-tetrafluoroethane) is another chemical with properties
which appear to make it a potentially viable candidate for replacing CFC-12 as
a polystyrene foam blowing agent. Because this compound contains no chlorine,
its estimated ozone depletion factor is zero. Its boiling point is within the
required range at -26.3°C (-15.3°F), and its solvent power and diffusivity are
both acceptably low. The molecular weight of FC-134a is 102.0. and its gas
efficiency is 95 percent of the theoretical value. The quantity of FC-134a
required to blow a 0.08 g/cc (5 Ib/ft ) foam is 4.2 parts per 100 parts resin.
This is about 0.8 parts per 100 parts resin less than is required of CFC-12.
The thermal conductivity of this compound is 14 percent lower than that
of CFC-12, so foams blown with FC-134a would have superior insulating charac-
teristics to those blown with CFC-12. Additionally, the diffusion rate for
141
-------
this FC is slow through polystyrene; therefore, the foam's insulation proper-
ties should degrade no faster than those of CFC-12 blown foams (2). These two
characteristics make it especially suited to replace CFC-12 as a blowing agent
for polystyrene foam boardstock. Tozicity testing for this compound is
incomplete, but in tests for flammability, this blowing agent has been rated
as nonflammable.
CFC-142b Alone or Mixture with CFC-22
Other proposed substitutes include use of CFC-l42b, either alone or in a
mixture with CFC-22. CFC-142b is currently manufactured and sold in a 60/40
mixture with CFC-22 as an aerosol propellent. Less is sold as pure CFC-142b
because of its flammability. Technical feasibility as a blowing agent is not
completely known, however, some formulations may be cost-effective alterna-
tives to CFC-12. Concerns include strong solvent action and rapid diffusion
of CFC-22. For CFC-142b. the ozone depletion factor is expected to be low.
Its boiling point is -9.2°C (15.4°F). but is has a moderate solvent power and
diffusivity which might compromise the foam's thermoformability. The molecu-
lar weight of this CFC is 100.5, and its gas efficiency is 80 percent of the
theoretical value. The quantity of CFC-142b required to blow a 0.08 g/cc (5
o
Lb/ft ) foam is 5 parts per 100 parts resin. This is equivalent to the
quantity of CFC-12 which would be required.
The thermal conductivity of CFC-142b is 15 percent higher than that of
3FC-12, so the insulating characteristics of foams blown with CFC-142b would
ae inferior to those of foams blown with CFC-12. Additionally, the diffusion
rate for this CFC is moderate; therefore, the foam's insulation properties
7ould probably degrade faster than those of CFC—12 blown foams. In tests for
icute and short term toxicity, DuPont has found CFC-142b to be a weak mutagen.
Further, this blowing agent is rated as slightly flammable. Its flammability
.imits in air range from 6.9 weight percent to 15.5 weight percent.
142
-------
Though both CFC-22 and CFC-142b appear to have properties which are less
than satisfactory for blowing polystyrene foam, together in a mixture the
properties of one chemical may compensate for those of the other. For in-
stance. CFC-142b is flammable, but adding a sufficient quantity of CFC-22
forms a non-flammable mixture. Also, CFC-142b is less diffusive through
polymer than CFC-22 and may alleviate problems with thermoforming. Both have
relatively high thermal conductivity; therefore, a mixture of CFC-142b and
CFC-22 would still be a less desirable choice as a blowing agent for
polystyrene foam boardstock used as insulation.
Innovative Blowing Agent Blends
Most of the alternative blowing agent chemicals discussed so far have
drawbacks associated with them: alternative CFCs are relatively expensive and
could adversely affect foam quality, and hydrocarbons can increase fire
hazards in the manufacturing plant. A promising approach to reducing these
drawbacks is the use of a blend of a less ozone-depleting CFC with a
hydrocarbon. The benefit of this blend would be that the hydrocarbon could
possibly prevent the CFC from adversely affecting the foam quality, and the
CFC could reduce the emitted concentrations, hence the fire hazards of the
hydrocarbon. The optimum chemicals and relative concentrations would have to
be established through research and testing. Operating costs for this option
are apparently minimal, however, FDA approval will be needed for food
packaging.
Conclusions for Polystyrene Foam Blowing Agents
To evaluate the suitability of a potential blowing agent for polystyrene
foams, a number of physical and chemical characteristics need to be consi-
dered. Table 7—2 summarizes the various characteristics of the CFCs which
were considered as alternative blowing agents.
143
-------
1KBLC. /-/.
DU.DO.LJ.J.UIU I uij i o JL j. i\m«u
Factors
Reactivity with Ingredients
Stability
Boiling Point. °C (»F)
Solvent Power
Gas Efficiency (% of theory)
Molecular Weight
3 3
Quantity for 0.08 g/cm (5 Ib/ft )
Foam (parts/100 parts resin)
Thermal Conductivity W/m-°C
(Btu/hr-ft-°F)
Diffusivity Through Polymer
Toxic ity
0
Flammability
Ozone Depletion Factor
CFC-12
None
Stable
-29.8
(-21.6)
Low
—
120.9
5
0.0097
(0.0056)
Low
Low
Non-
flammable
0.86
Alternative CFG Blowing Agents
CFC-22
None
Stable
-40.8
(-41.4)
Low
—
86.5
—
0.0105
(0.0061)
High
Low
Non-
flammable
0.05
CFG- 124
None
Stable
-11
(12.2)
Low
90
136.5
6
0.0102
(0.0059)
Low
Low
Non-
flammable
Low
FG-134a
None
Stable
-26.3
(-15.3)
Low
95
102.0
4.2
0.0083
(0.0048)
Low
Incomplete
Non-
flammable
0.0
CFC-142b
None
Stable
-9.2
(15.4)
Moderate
80
100.5
5
0.0111
(0.0064)
Moderate
Low
Slightly
flammable
Low
These estimates are made qualitatively relative to CFC-12.
-------
Both CFC-124 and FC-134a appear to be viable as candidates for replacing
CFC-12 as a polystyrene foam blowing agent. With respect to the desired
chemical and physical properties, FC-134a is equivalent or superior to
CFC-124. However, cost comparisons are not yet possible, and toxicity testing
is incomplete for FC-134a. Even a slight toxicity could jeopardize its
potential as a blowing agent.
Both CFC-22 and CFC-142b considered alone as blowing agents for polysty-
rene foam appear to be less promising. The low boiling point and high dif-
fusivity of CFC-22 may cause problems in both the manufacturing process and
produce a product of inferior quality. CFC-142b has a high thermal conductiv-
ity, making it a poor choice for blowing insulating foams, but its main draw-
back is its slight flammability. Both chemicals are currently available and
are sold together as a mixture. There is potential that a non-flammable mix-
ture of these chemicals may be suitable for use as a polystyrene foam sheet
blowing agent.
Finally, a mixture of CFC-22 and hydrocarbons appears to be an additional
blowing agent alternative. The benefit of this blend would be that the
hydrocarbon could possibly prevent the CFC foam adversely affecting the foam
quality, and the CFC could reduce the emitted concentrations, hence the fire
hazards of hydrocarbons.
POLYOLEFIN AND PHENOLIC FOAM BLOWING AGENTS
Extruded thermoplastic foams such as polyolefin foams, (i.e.,
polyethylene, polypropylene, etc.) use a variety of chlorofluorocarbon blowing
agents including CFC-11, CFC-12, CFC-114, and CFC-115. The polyolefin foam
industry also employs mixtures of these CFCs as blowing agents. The most
common blowing agent is a mixture of CFC-12/114. A variety of chemical and
physical properties makes these compounds desirable as blowing agents for
polyolefin foams. For instance, since the diffusion rate of CFC-114 out of
these foams is close to the diffusion rate of air in, the foams maintain
145
-------
structural stability. A potential substitute would need to have similar
diffusion properties in order to serve suitably as a replacement.
Like polystyrene foams, polyolefin foam sheet products tend to emit most
}f their blowing agents during, or soon after, manufacture. The boardstock
products tend to retain blowing agents. Use of low ozone depleting CFCs as
jlowing agent substitutes in polyolefin foam sheet products can provide short
:erm reductions in the potential threat to the stratospheric ozone layer.
iowever, before a substitute blowing agent can begin to reduce the potential
ihreat to the ozone layer, it must be widely accepted and adopted for use by
:he polyolefin foam industry. This acceptance is dependent upon the alter-
late's cost and its performance during processing as well as in the final foam
product.
Phenolic foams are blown using CFC-11 and CFC-113. A variety of chemical
ind physical properties make these CFCs desirable as a blowing agent for
ihenolic foam, and a potential substitute would have to have similar
properties since phenolic foam depends upon CFCs for superior insulating
properties. Like polyurethane and polystyrene boardstock, phenolic foams
retain the CFC for a long period of time.
Processing Considerations
Polyolefin foams are typically used in cushioning and wrapping applica-
:ions. For these foams, the criteria for judging potential substitute blowing
igents are similar to those described for polystyrene foam except that solvent
if facts are much less important and diffusion losses can be much more signifi-
:ant. Aging or diffusion additives are generally used to adjust CFC emission
rate to the air infiltration rate. Even with CFC-12 substantial losses result
.n a partially collapsed foam which must be stored until it reezpands.
iecause the CFC emission rates from thin polyolefin foam sheet are high.
Blowing agent flammability is a greater concern than it is with polystyrene
146
-------
foams. Likewise toxicity is a concern because of the potential for worker
exposure.
Polyolefin foams include several types of polymers and therefore differ-
ent blowing agents may be best suitable for certain polyolefin foam types.
Also, the final product may dictate the choice of blowing agent (e.g., CFC-11A
is required for thick polyolefin profiles).
For phenolic foams, processing considerations are similar to those of
polyurethane and polystyrene insulating foams.
Product Considerations
Because a large majority of polyolefin foams are thin sheet products, the
blowing agent is emitted early in the foam's life, and makes no significant
contribution to the properties of the foam product.
Phenolic foam, on the other hand, is used as an insulating material. In
this application, phenolic foam has the advantage of high insulating quality
(per thickness) due to the CFC vapor trapped in the cells. Thus, an optimum
substitute would possess insulating qualities similar to or better than those
presently achieved with CFC-11 and CFC-113.
Implementation
Two final considerations are the implementation time frame and the
blowing agent cost. These are probably the most difficult to predict because
both are heavily dependent upon the manufacturer of the potential alternative.
However, the time frame for adaptation by the foam producers is more easily
predicted. Because experimentation requires full-scale production equipment
and large quantities of raw materials, the evaluation by industry of alterna-
tive polyolefin blowing agents will be dependent on the availability of
alternate CFCs. CFC-12A and CFC-142b have been identified as potential new
147
-------
CFG replacements for the CFCs currently used in polyolefin foams. CFC-123 and
CFC-141b have been identified as potential replacements for the CFCs currently
used in phenolic foams.
CTC-12A
CFC-124 is a potentially suitable replacement for CFC-12 as a polyolefin
foam blowing agent. However, it is a new chlorofluorocarbon for which a
manufacturing process has not yet been developed. This compound is expected
to have a low ozone depletion factor. The boiling point of this CFC is -11°C
(12.2°F) which is within the acceptable range for a polyolefin blowing agent.
Its diffusivity through these foams is high, so there could be problems with
collapsed foams.
The molecular weight of this CFC is 136.5, and its gas efficiency is 65
percent of the theoretical value. The quantity of CFC-124 required to blow a
o
0.018 g/cc (1.1 Ib/ft ) foam sheet, 0.08 cm (1/32 in.) thickness, is 40 parts
per 100 parts resin. This is about five parts per 100 parts resin less than
is required of CFC-12. In tests for acute and short term toxicity, DuPont has
found CFC—124 to have a low toricity. Further, this blowing agent is rated as
nonflammable.
3FC-142b
The discussion of the properties of CFC-142b provided relative to poly-
styrene foams is applicable also to polyolefin foams with the following
jxceptions. Since polyolefin foams are typically not used as insulating
aaterials. the high thermal conductivity is not an issue. As previously
lentioned. the diffusivity of the CFC will be higher than the polyolefin
laterial, which could potentially cause processing problems, (i.e., sagging).
igain, the slight flammability of the chemical must be considered with respect
:o the particular polyolefin foam manufacturing process and product being
148
-------
made. Since the CFC is not retained in thin polyolefin sheet products, this
is more of a processing (worker safety) concern.
CFC-123
CFC-123 may prove to be a good blowing agent for phenolic foam although
it has a higher thermal conductivity (less insulating value) and is expected
to cost more than CFC-11 (44). However, the diffusion rate for this CFC is
slow; therefore, the foam's insulation properties should degrade no faster
than those of CFC-11 blown foams. Chemical manufacturers and rigid insulation
foam manufacturers have both recently renewed efforts to study application of
this compound.
CFC-141b
Like CFC-123, CFC-141b may prove to be a good blowing agent, but it has
the disadvantages of higher thermal conductivity, increased toxicity, and
slight flammability (44).
Conclusions for Polyolefin and Phenolic Foam Blowing Agents
CFC-124 appears to be a suitable substitute blowing agent for polyolefin
foams due to the favorable chemical and physical characteristics. CFC-142b
may also be an acceptable blowing agent substitute if its diffusive nature is
not extreme enough to cause sagging of the product. Also, the issue of its
flammability must be addressed with respect to the particular polyolefin
process in which it is to be used. Table 7-3 summarizes the various charac-
teristics of the CFCs which were considered as alternative blowing agents.
Based on similar substitutes proposed for other rigid foams blown with
CFC-li, potential CFC substitutes are CFC-123 and CFC-141b. Table 7-4
summarizes the various characteristics of the CFCs which were considered as
alternative blowing agents. One disadvantage of using CFC-123 is that the
149
-------
foam has a lower insulating ability. In addition, CFC-lAlb may not be
suitable because of its toxicity. In general, the economic competitiveness of
foams blown with more expensive CFCs would have to be examined relative to
possible alternative insulation products.
150
-------
TABLE 7-3. EVALUATION FACTORS FOR SUBSTITUTE POLYOLEFIN FOAM BLOWING AGENTS
Current CFC Blowing Agents
Factors
Reactivity with Ingredients
Stability
Boiling Point, °C (°F)
Gas Efficiency (% of theory)
Molecular Weight
3
Quantity for 0.018 g/cm
(1.1 Ib/ft ) Foam (parts/
100 parts resin)
Diffusivity Through Polymer
Toxicity
CFC- 11
None
Stable
23.8
(74.8)
—
137.4
,
—
Low
a
Flaminability Non-
flammable
CFC- 12
None
Stable
-29.8
(-21.6)
51
120.9
45
High
Low
Non-
flammable
CFC- 114
None
Stable
3.8
(38.8)
84
170.9
39
Low
Low
Non-
flammable
CFC-115
None
Stable
-38.7
(-37.7)
85
154.5
___ l
Low
Low
Non-
flammable
Alternative CFC
Blowing Agents
CFC- 124
None
Stable
-12
(10.4)
65
136.5
40
High
Low
Non-
flammable
CFC-142b
None
Stable
-9.2
(15.4)
80
100.5
_
High
Low
Slightly
flammable
These estimates are made qualitatively relative to CFC-11 and CFC-12.
-------
TABLE 7-4. EVALUATION fc'AUTORS bUK
tuv^iu rnc,nuiuxu
to
Alternative
CFC Blowing Agents
Factors
Reactivity with Ingredients
Stability
Boiling Point, °C (°F)
Solvent Power
Molecular Weight
Thermal Conductivity
W/m-°C (Btu/hr-ft-'F)
Diffusivity Through Polymer
Toxic ity8
Flamiaability
Ozone Depletion Factor
Cost ($/kg)
CFC- 11
None
Stable
23.8 (74.8)
Moderate
137.4
0.0078
(0.0045)
Low
Low
Non-
flammable
1.0
1.40
CFC- 113
None
Stable
47.6 (117.7)
187.4
0.0076
(0.0044)
Low
Low
Non
flammable
Low
2.06
CFC- 123
None
Stable
28 (62.4)
Moderate
152.9
0.0093
(0.0054)
Low
Low
Non-
flammable
Low
4.14
CFC-141b
None
Stable
32 (89.6)
Strong
117.0
0.0092
(0.0053)
Low
Potentially
Mutagenic
Slightly
flammable
Low
3.31
Source: (44)
Jl
Note that only the Ames test results have reported this result.
conclusions can be drawn.
Further testing is required before
These estimates are made qualitatively relative to CFC-11.
-------
SECTION 8 .
SUBSTITUTES FOR CURRENT RIGID FOAM PRODUCTS
ALTERNATIVES TO CFC BLOWN RIGID POLYURETHANE FOAM PRODUCTS
A majority of rigid polyurethane foam products are used as insulation in
various applications. These include: industrial, commercial, and residential
building insulation; refrigerated appliance insulation; industrial insulation;
and insulation for refrigerated transport vehicles. Packaging is an addi-
tional use of rigid polyurethane foams. In each application area, there are
alternative materials which can serve as substitutes for urethanes. However,
the unique properties of rigid polyurethane foams often make them more de-
sirable and less expensive than potential substitutes. This is especially so
with insulation foams where any alternative material would cause substantial
increases in energy costs or construction costs.
/•
Low thermal conductivity and good mechanical properties are the primary
advantages that rigid polyurethane foam has over other insulation materials.
Polyisocyanurate foams have the added benefit of excellent fire resistance.
Other advantages include:
• Ease of production and simplified designs,
• Low density,
• Less required thickness,
• Reduced waste materials, and
• Resistance to moisture.
153
-------
The most common use of polyurethane board is commercial and industrial
roofing, but these foams are also used extensively in residential sheathing
ind roofing. Table 8-1 shows the market distribution for PU foam insulation.
loofing and sheathing as well as some industrial pipe and storage tank insula-
:ion applications offer the best possibilities for substitution of either
Alternative materials or insulation systems. Alternatives include materials
aade with little or no CFCs. Table 8-2 lists specific alternatives to
)olyurethane foam products in several application areas and the CFC emission
reduction potential. The following sections discuss the applicability of
various substitutes for rigid polyurethane foam products.
Alternative Industrial and Cfi^^ercial Roofing Insulations
A large majority of the PU insulation produced is used in industrial and
commercial roofing. Before the mid-1970s, however, this was not the case.
Then, most roofs consisted of hot-mopped asphalt or coal-tar pitch, and often
10 insulation was used. When insulation was desired, the available materials
/ere primarily fiberboard, perlite, fiberglass, and cellular glass. Increas-
_ng energy costs and advances in technology have stimulated development of
jnproved roofing methods, and there is currently available a tremendous
variety of membrane materials, insulation products, and applications tech-
liques. Rigid PU foams are used mainly in three general types of industrial
md commercial roofing: built-up roof (BUR), modified bitumen and elastomeric
ystems. Table 8-3 shows the use distribution of insulation products in the
roofing industry.
Traditionally, built-up roofing membrane has been used to protect the
lat and nearly-flat roofs found in industrial and commercial construction.
>UR uses layers of felts (paper, glass fiber, polyester, or asbestos) alter-
lated with layers of hot-applied or cold-applied bituminous materials (asphalt
>r coal-tar based). The surface layer is also embedded in a heavy coat of
isphalt or coal-tar pitch. This top layer is usually covered with gravel, but
lay be left smooth. Typical BUR systems are installed in different ways
154
-------
TABLE 8-1. 1985 MAEKET DISTRIBUTION FOR POLYURETHANE AND
POLYISOCYANURATE INSULATION FOAMS
Market
Market Distribution
(Percent)
Industrial and Commercial Roofing
New Residential
Retrofit Residential
Masonry Wall
Metal Buildings
Farm Buildings
Non-Residential Retrofit
Miscellaneous
65
22
3
3
3
3
1
<1
100
Source: (48)
155
-------
TABLE 8-2. POTENTIAL SUBSTITUTES FOR RIGID PU FOAM PRODUCTS
Applications
Alternatives
CFC Emission
Reduction Potential
Industrial Roof/Ceiling:
Industrial Walls:
Commercial Roof/Ceiling:
Commercial Walls:
Fiberglass
Perlite
Expanded PS
Extruded PS
Fiberboard
Cellular Glass
Insulating Concrete
Fiberglass
Rock Wool
Perlite
Vermiculite
Insulating Concrete
Fiberglass
Rock Wool
Cellulose
Perlite
Expanded PS
Extruded PS
Fiberboard
Cellular Glass
Insulating Concrete
Fiberglass
Rock Wool
Perlite
Vermiculite
Expanded PS
Extruded PS
Fiberboard
Cellular Glass
100%
100%
100%
40%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
40%
100%
100%
100%
100%
100%
100%
100%
100%
40%
100%
100%
(Continued)
-------
TABLE 8-2 (Continued)
Applications
Alternatives
CFG Emission
Reduction Potential
Commercial Floors:
Residential Roof/Ceiling:
Residential Walls:
Cn
Residential Floors:
Refrigeration Insulation:
Packaging Materials:
Fiberglass
Rock Wool
Expanded PS
Extruded PS
Fiberglass
Rock Wool
Cellulose
Fiberglass
Rock Wool
Expanded PS
Extruded PS
Fiberboard
Cellular Glass
Gypsum
Plywood
Foil Faced Laminated Board
Fiberglass
Rock Wool
Foil Faced Laminated Board
Expandable PS Bead
Extruded PS Board
Fiberglass
EPS Foam Peanuts or Blocks
Plastic Film Bubble Wrap
Polyolefin Foam Sheet or Blocks
Wood Shavings
100%
100%
100%
40%
100%
100%
100%
100%
100%
100%
40%
100%
100%
100%
100%
100%
100%
100%
100%
100%
40%
100%
100%
100%
100%
100%
-------
TABLE 8-3. NON-RESIDENTIAL ROOFING INSOLATION MARKET (1986 TOTAL =
3900 MILLION BOARD FEET)
Material
Poly is ocy anurate
Perlite
Expanded PS
Extruded PS
Fiberglass
Fiberboard
Composite
Polyurethane
Phenolic
Other
Total
Total
Market
Share (Z)
32
13
12
10
10
9
8
4
2
<±
100
Built-up
Roofing (Z)
33
19
—
9
15
8
11
3
<1
1
100
Modified
Bitumen (Z)
33
19
—
9
14
9
10
3
<1
<1
100
Single-Ply
Sheets (Z)
31
6
26
11
4
9
5
5
3
<1
100
Source: (48)
158
-------
consisting of: membrane adhered to deck without insulation; insulation adhered
to deck with membrane applied to insulation; base sheet adhered to deck,
insulation over base sheet, and top membrane over insulation; and membrane
adhered to deck with insulation applied over the membrane.
Modified bitumen systems are similar to BUR systems except that the
individual plies are factory laminated and the modified bitumen is applied in
one layer. The composite modified bitumen sheets can be either self-adhesive
or heat applied.
The third major roofing method is known as elastomeric roofing. This
technology uses a single ply of thermoplastic or thermosetting synthetic
membrane. There are four major methods by which elastomeric systems are
installed: loose laid and ballasted, partially adhered (with adhesive or
asphalt), fully adhered, and mechanically fastened. As with BUR and modified
bitumen systems, the insulation can be placed either above or below the roof
membrane.
It is evident that there is available a tremendous variety of roofing
systems and installation methods are available. Because of this, the utility
of an insulation material must be considered on a case by case basis.
Extruded and expanded PS foam are good examples of alternatives which are
suitable in some applications and not in others. The relatively low melting
point and low solvent resistance of PS foam may prevent its use in hot applied
BUR and modified bitumen systems as well as in fully adhered elastomeric
systems where solvent adhesives are used. However, with the proper
construction configuration, this can be overcome. Additionally, PS foam
cannot pass Factory Mutual and Underwriters Laboratories fire resistance
requirements without the use of underlay or overlay boards (usually perlite or
fiberboard) or both.
In the different types of industrial and commercial roofing, the poly-
urethane or polyisocyanurate insulation provides over 90 percent of the roof's
159
-------
insulation. This is because the other components (membrane and bitumen or
adhesive) are thin and have relatively low thermal resistances. Therefore,
the use of alternative materials can cause higher energy costs unless a
greater thickness of the alternative is used. Table 8-4 shows the energy
losses which would be incurred from using equivalent thicknesses of alterna-
tive insulation materials.
Alternative Residential Building Insulation
In the residential building insulation market rigid FU laminated
boardstock insulation is used primarily as an insulative sheathing material.
It is usually placed on the exterior side of a building's wall studs or
supports. The sheathing material is then covered by the building's exterior
finish such as brick, stone, stucco veneer, or siding made of wood or metal.
Figure 8-1 shows the configuration of a typical residential wall.
Other applications for FU foam boardstock include insulating underlayment
beneath roof shingles, sub-slab insulation, slab or basement perimeter insula-
tion, and ceiling insulation. The insulating sheathing adds to the insulative
capacity of the insulation which has been placed between the studs (usually
fiberglass batts), but the primary purpose of this sheathing is to insulate
over the studs. Because wooden or metal studs are poor insulators, and they
comprise up to 20 percent of a building's exterior wall surface, using in-
sulative sheathing can provide considerable heating and air conditioning
energy savings. Figure 8-2 illustrates the insulative contribution of each
element of a typical residential wall.
There are numerous alternatives to FU sheathing, but no other non-CFC
blown sheathing material has as high an insulative efficiency (R-value per
inch of thickness). Figure 8-3 compares the relative insulative capacities of
several common sheathing materials including polyurethane foam, polystyrene
foam, expandable polystyrene foam, phenolic foam, fiberboard, plywood, gypsum,
and foil laminated paper board. Other sheathing materials include insulating
160
-------
TABLE 8-4. ESTIMATED ENERGY LOSSES FROM USING ALTERNATIVE INSULATION
IN INDUSTRIAL AND COMMERCIAL ROOFING
Board
Insulation Material
Phenolic Foam
PU Foam
Fiberglass Board
Cellular Glass
Perlite
Expanded PS Foam (EPS)
Extruded PS Foam
Fiberboard
R-Value
Per Inch
8.3
7.2
4.4
2.9
2.8
3.9
5.1
2.8
Percent
Increase In
Energy Lossesa
-
0
35
54
55
41
26
55
Assuming insulation comprises 90 percent of the roof's total insulation
value.
161
-------
FOIL • FACED
FOAM SHEATHING
UNPAGED GLASS
FIBER BATT
EXTERIOR _S\
SIDING
GYPSUM BOARD
POLYETHYLENE
VAPOR HETARDER
FOUNDATION
WALL
FOIL-FACED
FOAM SHEATHING
UNPAGED GLASS
FIBER BATT
METAL TIE
FASTEN TO STUD'
BRICK VENEER
GYPSUM BOARD
POLYETHYLENE
VAPOR RETARDER
FOUNDATION
WALL
I
S
Q
Figure 8-1.
Typical residential wall construction. Basic wall with
siding (top). Basic vail with brick veneer (bottom).
162
-------
3/8'—BJ
Inside
Air Film
Gypsum
Drywall-
Vapor
Retarder
• 3 -1 / 2" •
•3/4-HPJ 1/2' Ul
•PU
Sheathing
•Wood
Siding
•Outside
Air Film
086-W63A
Inside surface film
Gypsum board
6-mil vapor retarder
2x4 wood framing
R-13 glass fiber batt
PU foam sheathing
Lapped wood siding
Outside surface film
R-Value
R-Values
Through
Frame
0.68
0.45
4.35
R-Values
Through
Wall
0.68
0.45
—
5.40
0.81
0.17
13.00
5.40
0.81
0.17
11.86
20.51
Total Wall U-Valve = 20Z/11.86 + 802/20.51 = 0.0559
Total Wall R-Valve =17.9
Figure 8-2. Insulative contribution of individual wall components.
163
-------
o
3
a:
Phenolic
Extruded Fiberglass
PS Board
Board
f———T
Fiberboard Plywood
Gypsum Laminated
Paper
Board
Figure 8-3. R-values per inch for various materials (at 24°C (75°F) mean temperature).
-------
boards made from corkboard. fiberglass, perlite. or vegetable fibers (36).
Since the primary purpose of FU sheathing is to insulate the wall, it is
convenient to compare alternatives according to their insulative abilities as
well as their cost. However, other factors which might need to be considered
in a given situation are: local codes and restrictions on certain materials,
availability, flammability, vapor retardancy, durability, and installation
costs. Table 8-5 shows the estimated material and energy costs associated
with using alternative sheathing materials. Most sheathing products have
lower material costs, but their use generally results in higher energy losses,
hence higher heating and cooling costs.
Another way to investigate alternatives to PU insulation sheathing is to
compare options on a basis of a fixed value for the walls total insulative
capacity. Since FU foam sheathing has the highest R-value, per unit thickness
of all non-CFC blown alternatives, most alternatives will require greater
total wall thicknesses. This might mean using greater thicknesses of the
sheathings discussed earlier. Figure 8-4 shows the thickness of various
sheathing materials required to equal the R-value of 3/4 inch thick PU
sheathing (R-5.4).
Another option is to increase the thickness of the fiberglass batts used
between the wall studs. This would require use of thicker studs, possibly
changing the wall's construction and cost. The wall shown in Figure 8-2 has a
total wall R-value of approximately 18. To obtain the same wall R-value
without sheathing or any sort of external thermal barrier would require
fiberglass batts and wall studs which are 6.5 inches thick. This is nearly
double the width of the standard 2x4 wall stud.
Another possibility is using alternative construction materials. An
example is Klimanorm®, a lightweight building block recently introduced to the
US from West Germany. Block-type residential and commercial construction is
common in Europe. This quartz sand/lime agglomerate block replaces all of the
major components in a standard wall: sheetrock, stud frame, fiberglass batts.
165
-------
TABLE 8-5. ESTIMATED RELATIVE MATERIAL AND ENERGY COSTS FOR
SUBSTITUTE SHEATHINGS
Sheathing Material
Phenolic Foam
Laminated PU Board
Extruded PS Board
EPS Board
Fiberglass Board
Fiberboard
Plywood
Gypsum (exterior)
Laminated Paper Board
Building Felt
Thickness
(inches)
0.75
0.75
0.75
0.75
1.0
0.5
0.5
0.5
0.5
—
2 Material
Cost Savings
-
0
11
43
-46
24
12
29
22
90
Estimated
R-Value
(75 °F)
6.2
5.4
3.8
2.9
4.4
1.3
0.6
0.5
0.3
0.2
% Increase in
Wall Energy
Losses (75°F;
—
0
10
15
6
25
30
30
31
32
166
-------
c
O
s
u
5
s
o
2
8 -
7 -
6 -
5 -
4 -
3 -
2 -
1 H
o
Phenolic PU Extruded Fiberglass
PS Board
Board
I
EPS
Flberboard Plywood
l I
Gypsum Laminated
Paper Board
Figure 8-4. Equivalent thickness for various materials (at 24°C (75 F) mean
temperature). All values are relative to 0.75 inch laminated PU board.
-------
and sheathing. Depending on the wall thickness, this material gives wall
R-values of R-22 to R-30 (37).
Other Building and Industrial Insulation
Industrial and commercial roofing insulation as well as residential
insulation comprise nearly 90 percent of the polyurethane and polyisocyanurate
foam building insulation market. The remaining 10 percent is used in a
variety of applications such as commercial cavity walls, curtain walls,
commercial metal buildings, farm buildings, and cold storage facilities. The
contributions which FU foam makes to total insulation value of each of these
installations are shown in Table 8-6. In addition, FU sprayed foams are often
used in industrial applications such as storage tank and pipe insulation. The
use of suitable alternatives in these applications would incur energy losses
proportional to those shown in the previous sections unless greater
thicknesses are used.
Alternative Refrigerated Appliance Insulation
Currently, rigid FU foam insulation is used in a majority of refrig-
erators and freezers. In 1982, polyurethanes held approximately 65 to 75
percent of the refrigeration insulation market (16). This market share is
expected to increase further as demand for higher energy efficiency appliances
grows. California and several other states have, or will have, laws requiring
appliances be more energy efficient in the near future. These laws, if imple-
mented, argue against many of the available insulating materials, or, con-
versely, will result in thicker walled appliances with significant loss in
usable capacity. The advantages of FU in this application area are:
• Its high R-value allowing thinner walled appliances,
• Ability to be used in pour—in-place applications.
168
-------
TABLE 8-6. CONTRIBUTION TO TOTAL INSULATION SYSTEM MADE BY
PU FOAMS IN VARIOUS APPLICATIONS
Contribution
Application To Total Insulation
Commercial Cavity Wall 76%
Commercial Curtain Wall 42%
Commercial Metal Buildings 90%
Farm Buildings 90%
Cold Storage Buildings 95%
169
-------
• Structural strength contributed to the appliance, and
• Moisture resistance.
In the past, refrigeration appliances were insulated exclusively with
iberglass. Presently, only 20 to 30 percent of the refrigeration insulation
ised is fiberglass (16). Based on current trends, refrigeration unit
lanufacturers would revert to the use of fiberglass only if there were no
?ther technically feasible alternatives.
From the manufacturing standpoint, the increased labor cost of installing
fiberglass insulation balances against the higher material costs for foam
Insulation (16). However, for a given wall thickness the fiberglass insulated
anit will necessarily consume more energy. The same holds true for other
potential alternatives such as extruded PS board or expandable bead PS board.
Table 8-7 shows the relative costs associated with alternative insulation
naterials for a typical refrigerator. Expandable PS and extruded PS board
Doth are more difficult to install than fiberglass. However, they have better
insulation properties.
TABLE 8-7. RELATIVE COSTS OF ALTERNATIVE REFRIGERATOR INSOLATIONS3
Rigid Extruded Expanded
PU Foam PS Foam PS Foam Fiberglass
Material Cost
Labor Cost
Energy Cost
1
1
1
1
4
1.4
1
4
1.9
1/3
3
2.3
Assuming no change in the dimensions of the appliance cabinet.
Source: (16)
170
-------
Changing to an alternative insulation requires balancing the manufactur-
ing costs against the energy costs. Using an alternative insulation without
altering the appliance's wall thickness reduces the material costs, minimizes
the increase in labor costs, allows the manufacturer to use an existing
appliance line, and does not alter the cold storage volume available to the
customer. However, the customer will pay more in energy costs because the
unit is not as well insulated. On the other hand, if the wall thickness is
increased to provide equal insulation, the energy costs will be the same, but
the manufacturer must redesign and retool for an entirely new appliance. In
addition, a complete redesign may be required since FU foam provides 80—90
percent of the structural support in present-day appliances.
As a result of more stringent appliance energy standards, an emphasis has
been placed on new materials and designs for refrigeration systems. Re-
searchers are currently devising ways to increase the efficiency of re-
frigeration units to conserve energy. New materials such as vacuum board
panels are being considered, as well as new cabinet designs.
S
Alternative Transportation Insulation
In the transportation business, poured and sprayed FU foams serve as
insulation for refrigerated truck trailers, rail cars, tank cars, barges and
ships. Since these are essentially mobile refrigerators, much of the
discussion of refrigeration insulation applies here. Polyurethane foams
endure very well the vibration and shocks associated with transportation, and
they also contribute structural support by adhering to the walls. The
alternatives such as fiberglass, EPS, or extruded PS will require thicker
walls or higher refrigeration costs. Additionally, fiberglass batts will tend
to collapse due to vibration and absorb H_0 if walls are damaged (16).
If the thickness of the walls is increased, then the space available for
freight decreases, and the weight of the vehicle increases. Otherwise, the
wall thickness can be maintained and the cooling costs are higher. Both
options result in a net increase in transportation costs, and switching to an
alternative such as extruded or expandable polystyrene will require optimiza-
tion to minimize the increased cost.
171
-------
Alternative Packaging Materials
In packaging applications, pour—in-place polyurethane foams are widely
used. Their ability to fill non-uniformly shaped voids, ease of use,
availability in a range of compressive strengths, light weight, and creep
resistance make them suitable for a wide range of packaging applications.
A unique use for these foams is for one-time packaging or for packaging
of odd shaped.items which require rigid support. For these applications,
alternative materials such as preformed rigid packaging might be expensive or
provide inferior protection.
For regularly shaped items or items not requiring rigid support, there is
a wide variety of packaging alternatives such as non-CFC blown loose-fill
expanded polystyrene, shredded and wadded paper, cellulose wadding, die-cut
cardboard, wood shavings, pre-formed expanded polystyrene packing blocks, and
plastic film bubble wrap.
Packaging is a custom operation and the packaging material chosen re-
flects the specific needs of the packer. However, the ease of use of poured
foam systems has probably encouraged use in "non-essential" applications where
other packing materials would be just as suitable, albeit at possibly higher
aaterial or labor costs.
ALTERNATIVES TO CFC BLOWN POLYSTYRENE FOAM PRODUCTS
Since the 1960s, polystyrene foam sheet products have gradually replaced
competing products fabricated from traditional materials. The benefits of
polystyrene foams such as light weight, strength, ease of forming, moisture
resistance, low cost, and thermal insulation properties have spurred this
growth. Not only are foam producers increasing service to existing markets,
:hey are working to penetrate new areas such as salad trays for self-service
supermarket salad bars, pizza boxes, ice cream containers, and reheatable
packages for use in microwave ovens (9). With few exceptions, the polystyrene
172
-------
foam serves essentially the same purpose as the material it replaced. Indeed,
in many applications, polystyrene and its competitor can be found in use
side-by-side. An example is egg cartons. In many stores one can find both
paper and polystyrene egg cartons in the same display case.
A distinction should be drawn here between CFC blown polystyrene foam
sheet and non-CFC blown PS foam sheet. CFC blown foams comprise only 50
percent of the PS foam sheet market, and the remainder of the market is held
predominantly by hydrocarbon blown foams. Therefore, in considering
alternatives to CFC blown PS foam sheet, a suitable substitute is foam
produced with hydrocarbons. In each application of polystyrene foam
materials, there can be found a variety of suitable substitutes. These
application areas include: stock food trays; egg cartons; single service
plates, cups, and bowls; hinged containers; and insulation board. Table 8-8
lists specific alternatives to CFC-blown polystyrene foam products in several
application areas.
r<
The following sections discuss the applicability of various substitutes
for CFC blown polystyrene foam products. Since it is not known to what extent
specific PS-foam sheet products are blown with hydrocarbons, this discussion
will simply examine suitable replacements for the foam products regardless of
the blowing agent used to fabricate them.
Stock Food Trays
Polystyrene sheet has found wide use as a packaging tray for meats and
produce. Because it is stiff, light weight, and waterproof, polystyrene foam
trays are particularly well suited for packaging flaccid and irregularly
shaped meats. In the past, stock food trays were composed of paper fiber
materials which became soggy and weak and they absorbed the juices from the
meat. However, currently available plastic laminated paper products should
not have this drawback. Solid plastic trays can also serve the same purpose,
but they are heavier (using more plastic) at an equivalent strength to foams.
173
-------
Application
Alternatives
Thennoformed Sheet:
Stock Food Trays
Egg Cartons
Single Service Goods:
Plates. Cups, and Bowls
Hinged Containers
Board Stock:
Insulation Sheathing
Hydrocarbon Blown PS
Solid Plastic Trays
Plastic Film Wrap
Plastic Bags
Coated Paper Trays
Butcher Paper
Controlled Atmosphere
Packaging
Hydrocarbon Blown PS
Paper
Hydrocarbon Blown PS
EPS
Paper
Solid Plastic
Hydrocarbon Blown PS
Paperboard Containers
Solid Plastic Containers
Paper Wraps
Foil Wraps
Plastic Wraps
Combination Laminated Wraps
-See Polyurethane Insulation
Sheathing Alternatives-
CFC Emission
Reduction Potential
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
-------
Other potential replacements for foamed polystyrene stock food trays are
plastic film wrap, heat sealed plastic bags, or butcher paper (though it
prevents viewing of the product).
There is a trend in the fresh food packaging industry which might eventu-
ally lead to a great reduction in the use of polystyrene foam stock food
trays. This trend is towards a new packaging method called controlled atmos-
phere packaging (CAP). In CAP, the product such as a cut of red- meat is
sealed along with an inert atmosphere in a plastic tray. The tray and its lid
are composed of a barrier plastic which prevents exchange of gases. The
result is a greatly extended shelf life. Another possible benefit of this
technology is that it would allow centralized packaging. This could provide
substantial savings over the current in—store preparation and wrapping methods
which employ polystyrene foam trays and plastic wrapping film. In a recent
trial of CAP red meat packaging in 86 of its stores, Kroger Company, a
Cincinnati-based supermarket chain said that it achieved a six to ten cent per
pound overall cost savings (40).
Egg Cartons
Retail egg packaging, once the exclusive domain of paper fiber egg
cartons, has seen a large increase in the use of polystyrene foam egg cartons.
Interestingly, paper egg cartons whose market share with the major grocery
chains had fallen as low as 5.5 percent, have recently seen a comeback. The
current market share for paper cartons is estimated at 65 percent. Although
the cost of each of the cartons is roughly equivalent, the reason for this
turnaround is increased aggressiveness by the paper industry. Armed with
research results showing that paper egg cartons incur one-third the egg
breakage of plastic cartons, the marketers of paper cartons have been working
to regain more of this market. While the makers of polystyrene foam materials
stress visual appeal and moisture resistance, the paper industry's research
indicates that the customers' only real concern when buying eggs is that none
of them be broken (41).
175
-------
'lates. Cups, and Bowls
Polystyrene-foam plates, cups, and bowls consume one-third of all the
ixtruded PS-foam sheet produced. All of these products have viable paper or
>lastic alternatives which are currently available and competing in the
larketplace with PS—foam products. The major benefits of extruded PS foam are
.ts high strength to weight ratio, thermal insulating properties, and low
:ost.
In the plate market, PS-foam products compete against both the inexpen-
;ive common paper plate and the thicker more expensive paper plates such as
3iinet* dinnerware. Laminated paper plates and solid plastic plates are also
:ompeting in the market place. Table 8-9 compares retail costs for a variety
>f single—service plates. One company, James River Corporation, markets under
:heir Dixie Division both coated paper and polystyrene—foam plates at very
limilar prices. This indicates the suitability of paper as a replacement
laterial. Just as with disposable plates, the disposable bowl market is
.ivided among paper, laminated paper, foamed polystyrene, and solid plastic
•roducts.
The major contender for replacing extruded polystyrene foam cups is
ixpandable bead polystyrene cups. These cups are readily available and have a
arge share of the disposable cup market. Like PS-foam sheet cups, they have
pod insulation properties as well as being lightweight and sturdy. Where
hermally insulating cups are not required, there are available a number of
olid plastic cups as well as paper cups.
inged Containers
The hinged polystyrene-foam take—out tray was pioneered by McDonald's
orporation and is now widely used throughout the food industry. These
ontainers have seen a tremendous growth, and innovative applications such as
'cDonald's McD.L.T.• will add to this trend. McDonald's aggressive
176
-------
TABLE 8-9. RETAIL COSTS FOR A VARIETY OF SINGLE SERVICE PLATES
Manufacturer
Retail Cost (c/Plate)
Brand Name
PS-Foam Solid Plastic
Paper
Mobil
James River Corp.
Keyes Fiber
Solo Plastic Cup Co.
Generic
Hefty* (plain)
(Printed)
Dixie* (Printed)
Chinet* (Printed)
Solo* (Printed)
Paper (Plain)
2.5
4.5
3.4
5.6
3.3
5.5
—
1,3
177
-------
advertising campaign for the McD.L.T.® is essentially based on the thermal
insulating properties of polystyrene foam and on the package's design which
allows separation of a hamburger's hot and cold elements.
Some of the advantages provided by hinged polystyrene-foam containers are
thermal insulation, time savings for food service employees, impermeability to
moisture, strength, light weight, and visual appeal. These containers have
good visual appeal because they can be colored and printed, and they do not
become soggy and wrinkled as would a paper wrap.
Substitutes for these hinged trays include: non-CFC blown PS foam trays;
paperboard and solid plastic containers: as well as laminated paper, plastic,
and foil wraps. All of these substitutes are widely used in take-out food
applications. Burger King serves a number of its sandwich products in plastic
laminated paper boxes which somewhat resemble the PS-foam enclosures. Some of
their sandwiches are also wrapped in paper. Other fast food chains, such as
Arby's or Wendy's, serve their sandwich products wrapped in a foil-laminated
paper sheet. All of these products seem to provide the same essential func-
tion, so companies have chosen between them on a basis of cost, aesthetics,
and marketing potential.
Printed or decorated polystyrene-foam hamburger containers are roughly
equivalent in price to their counterpart laminated paperboard boxes. However,
both of these options are more expensive than simple foil-laminated paper
sheet wraps (42).
Insulation Board
Extruded FS foam board functions primarily as an insulation material.
Like rigid polyurethane foam insulation, PS-foam is used as frame wall sheath-
ing, foundation sheathing, and over or under roof insulation. Table 8-10
shows the market distribution for PS foam insulation. The relatively high
moisture resistance of PS foam gives it added usefulness for below grade
178
-------
TABLE 8-10. 1985 MARKET DISTRIBUTION FOR EXTRUDED POLYSYTRENE
INSULATION FOAMS
Market
Market Distribution
(Percent)
Industrial and Commercial Roofing
New Residential
Retrofit Residential
Masonry Wall
Farm Buildings
Non-Residential Retrofit
Miscellaneous
35
24
10
25
2
3
1
100
Source: (48)
179
-------
insulation applications for basements, foundations, and earth—sheltered homes.
Materials which compete with PS foam in the insulation market are: fiber-
glass, fiberboards, expandable polystyrene foam (EPS), and rigid polyurethane
foams.
The alternatives to rigid polyurethane foams which were discussed earlier
in this section also apply to extruded PS foams. Again, options involve
tradeoffs between energy, materials, and labor costs. This is because, with
the exception of rigid polyurethane and phenolic foams, alternatives to
extruded PS foams have relatively inferior insulating properties.
One candidate for replacement of extruded PS foam is expanded polystyrene
board. This substitute already competes in the insulation market and uses no
CFCs. Its thermal resistance per inch of thickness is approximately 24
percent lower than that of extruded PS foam, but when installed as sheathing
in a wall system, for example, the total wall R-factor would be only five
percent lower than that of a similar wall system using an equal thickness of
extruded PS foam sheathing. A further illustration of the potential for
substituting EPS for extruded PS insulation is that one-inch-thick EPS has an
R-factor of about 3.8, and three-fourths-inch thick extruded PS has an
R-factor of about 3.8. Therefore, at a slight increase in material cost,
there is equivalent energy and labor costs with 100 percent reduction in CFG
emissions.
ALTERNATIVES TO OTHER CFC BLOWN FOAM PRODUCTS
Phenolic foam is used primarily as an insulation material. Like rigid
polyurethane foam insulation, phenolic foam is used as frame wall sheathing
and over or under roof insulation. Phenolic foam currently hold an 8 percent
share of the total roofing and sheathing insulation market (50). The
alternatives to rigid polyurethane foams which were discussed earlier in the
section also.apply to phenolic foam.
180
-------
Polyolefin foams are used primarily for cushion packaging and surface
protection. This market is a complex and diverse one where selection of the
material of choice is often difficult. For one-time packaging or for a
delicate packaging requirement, alternative materials may not be able to
provide adequate protection. This is especially true where polyethylene foam
plank is used since it represents one of the highest performance materials
used in cushion packaging.
In other instances, a wide variety of packaging alternatives such as
non-CFC blown expandable PS foam, wood shavings, pre-fearned expanded
polystyrene packing blocks, and plastic film bubble wrap can be used as
alternatives to polyolefin foams.
Although polyolefin foams are one of the most costly packaging materials
used, on a volume basis, the physical attributes of these foams often make
them the most cost effective when all possible factors are considered.
181
-------
SECTION 9
ADDITIONAL CFC CONTROL METHODS
There are alternative methods for reducing the CFC emissions associated
with rigid polymer foams. These methods are either developmental or require
further investigation to assess their suitability. For rigid polyurethane
foams, one CFC reduction approach which warrants further research is the
recovery of CFCs from foam-containing products prior to their disposal. For
nonpolyurethane foams a CFC emission control technology which has potential is
the use of blowing agents which are neither CFCs nor hydrocarbons.
RECOVERY OF CFC-11 UPON PRODUCT DISPOSAL
In rigid polyurethane foams, CFCs have a very low diffusion rate; there-
fore, the blowing agents are banked for extremely long periods of time. This
fact gives rise to the possibility of recovering the CFCs at the time of
disposal of the foam containing product. Application areas in which it might
be possible to recover CFCs upon foam disposal include refrigerated transport
vehicle insulation, building and home insulation, and refrigerated appliance
insulation. While it may be possible to recover CFC-11 from these insulation
foams, it is probably not economical as long as the value of CFC-11 is less
than one dollar per pound.
Refrigerated transport vehicles such as ship and barge containers, truck
trailers, tank trucks, tank cars, and boxcars probably offer the best opportu-
nity for CFC recovery. When a particular transport vehicle reaches the end of
its useful service life, it could be transported to a recycling facility which
would be capable of processing both the scrap metal and the CFC-containing
foam insulation. At the recycling facility, the foam would be pulverized to
release the blowing agent which would then be recovered in a carbon adsorption
system.
182
-------
The economics of recovery or destruction of the 18 to 36 kg (40 to 80
pounds) of CFCs in these vehicles would benefit from the simultaneous recovery
of recyclable scrap metal. The ownership of these types of vehicles is
somewhat consolidated (more so than for privately owned refrigerators), so
collection of the units is relatively simple. Also, the vehicles are mobile
and can be moved easily to a central recovery facility.
Another area in which there is some potential for disposal recovery is
demolition of commercial and residential buildings which are insulated with
polyurethane foam. The recovery method here would be similar to that in which
asbestos-containing materials are removed from buildings which are being torn
down. The polyurethane foam sheathing and roofing would be removed with care
being taken not to cause excessive damage to the foam, and then it could be
transported to a facility in which the CFCs would be released by crushing the
foam and then recovered through carbon adsorption.
The economics for this method of CFC-11 emission control would be less
favorable than for transportation insulation because of the added labor and
transportation costs. The insulation foam used in a 2000 square foot home
would contain approximately 23 kg (50 pounds) of CFC-11, while a large
building or apartment complex would contain much more. Also, the
applicability of this method has two major limitations. First, the buildings
would have to be dismantled piecemeal rather than demolished, and second, most
structures which contain polyurethane insulating foams are relatively new, and
are therefore still serving a useful purpose.
Another possibility for disposal recovery of CFCs is refrigerated appli-
ances. Typically, these appliances have lives of nearly 15 years, and at the
end of their useful life, are disposed of in a variety ways. Often, old units
are buried or left to decay at a dump site. In other cases, the merchant who
supplies a new appliance will take the old unit to a salvager who removes the
refrigeration equipment (motor, compressor, condenser, and evaporator) for
their scrap value. The cabinet is then compacted and buried in a landfill.
183
-------
A typical refrigerator contains less than two pounds of CFC-11 in its
insulation foam; therefore, for a recovery operation to be efficient, large
numbers of refrigeration units would have to be collected centrally and
crushed in a compactsr which is equipped with a carbon adsorption recovery
unit. Because of the costs which would be incurred in transporting these
appliances to a central recovery facility, this control does not appear to be
economically feasible.
USE 01 NON-CFC, NON-HYDROCARBON BLOWING AGENTS FOR NONPOLYURETHANE FOAMS
Nonpolyurethane foams emit most of their CFCs prior to disposal;
therefore, reduction of emissions from the product and the manufacturing
process is the best approach to CFC emission control. This can be
accomplished through the use of non-CFC containing blowing agents. The use of
hydrocarbon blowing agents is discussed in Section 6 of this report; however.
this technology presents fire hazards and is vulnerable to regulations on VOC
emissions. Carbon dioxide and nitrogen are potential blowing agents which
might reduce both CFC and VOC emissions.
These gases are auxiliary blowing agents which may be used with either
CFCs or hydrocarbons for nonpolyurethane foam manufacturing. The result is a
reduction in use, and therefore a reduction of emissions, of CFCs or
hydrocarbons. There is also a cost savings because these gases are
considerably .cheaper than the blowing agents they substitute. Carbon dioxide
(about $0.10/lb). for example, may be blended in concentrations up to 15 to 25
percent with CFC-12 ($0.74/lb) when used with a system using about five to
seven percent CFC. It is reported that European processors have used blowing
agent blends containing up to 30 percent CO.. jn addition to lower costs.
another benefit contributed by CO- is an improvement in surface sheen.
Currently, solubility problems prevent the use of 100 percent CO. as a
blowing agent for low density foams. Carbon dioxide has a low solubility in
the molten polymer resin, and the miscibility of CFC helps to solubilize the
184
-------
CO„ in the polymer melt. Also, because carbon dioxide has less of a
plasticizing effect than CFC, higher extruder temperatures are required for
operation.
185
-------
REFERENCES
1. Production Sales, and Calculated Releases of CFC-11 and CFC-12 Through
1984. Chemical Manufacturers Associations (CMA), Washington, B.C.,
October 1985.
2. Hamitt, J.K., et al. Product Uses and Market Trends for Potential Ozone
Depleting Substances 1985 - 2000. Rand Corporation, May 1986.
3. Annual Consumption Report. Modern Plastics, p. 64, January 1986.
4. Khalil, M.A.K., and R.A. Rasmussen. The Release of Trichloro-
fluoromethane from Rigid Polyurethane Foams. JAPCA Volume 36, n2
(February 1986).
5. E.I. DuPont de Nemours & Company. Freon Products Division. Nonaerosol
Propellant Uses of Fully Halogenated Halocarbons. Information Requested
by the Environmental Protection Agency, March 15, 1978.
6. Parkinson, D.B., and A. Miller. Integrated Solvents Analysis: Blowing
Agents. Prepared by SRI International for the U.S. Environmental
Protection Agency, Contract 68-02-3976, January 1986.
7. Kirk Othmer Encyclopedia of Chemistry Technology, John Wiley and Sons,
Third Edition, 1978, Volume 23.
8. Nissel, F.R. Extruding Thermoplastic Foams. Modern Plastics
Encyclopedia 1985-1986, p. 236.
9. Smoluk, George R. PE, PS Foam Sheet Add Multi-Market Appeal.
Modern Plastics, Volume 63, No. 5, pp. 72-74, May 1986.
10. Lapp, Thomas W., Ralph R. Wilkinson, Howard Gadverry, and Thomas Weast.
Chemical Technology and Economics in Environmental Perspectives, Task
III, Chlorofluorocarbon Emission Control in Selected End-Use
Applications, Final Report, Report No. EPA 560/1-76-009, November 1976.
11. FUR Dynamics. Modern Plastics. January 1986. pp. 57-6S.
12. U.S. Foamed Plastics Markets and Directory. Technomic Publishing
Company.
13. Palmer, Adele R., William E. Mooz, Timothy H. Quinn, and Kathleen A.
Wolf. Economic Implications of Regulating Chlorofluorocarbon Emissions
from Nonaerosol Applications. Rand Corporation. June 1980.
186
-------
14. Gordon, J.B. Foam Processing - Expandable Foam Molding. Modern Plastics
Encyclopedia, 1986-1986, pp. 233-235.
15. Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley and Sons,
Third Edition, 1978. Volume 13.
16. Mooz, W.E., et al. Technical Options for Reducing Chlorofluorocarbon
Emissions. Rand Corporation, March 1982.
17. Peach, Norman. Plastic Foams: Options, Methods, and Materials.
Plastics Engineering, August 1981, pp. 19-24.
18. Letter Report. James G. Burt to Radian Corporation - Austin, Texas,
August 19, 1986.
19. Clarkson, B.C. Reduction of Vented Pentane Emissions During the
Production of Expandable Polystyrene. The Chemical Engineer, February
1980. pp. 111. 114.
20. Sweetheart Plastics. Testimony submitted to the U.S. Food and Drug
Administration. February 22. 1976.
21. Personal Communication with Phillips Chemical Company, March 15, 1981.
22. Personal Communication with Tuxis Corporation, August 28, 1986.
23. Personal Communication with Mobil Chemical, August 1986.
24. Personal Communication with Genpak, August 29, 1986.
25. Personal Communication with Florida Containers, February 2, 1981.
26. Personal Communication with W.R. Grace Company, September 8, 1986.
27. Radian Corporation Chemical Containment Laboratory, Material Safety
Database, August 1986.
28. Material Safety Data Sheet: n-Pentane. Phillips 66 Company, August
1985.
29. Material Safety Data Sheet: Isopentane. Phillips 66 Company, March
1986.
30. Material Safety Data Sheet: n-Butane. Phillips 66 Company, November
1985.
31. Material Safety Data Sheet: Freon® 12. E.I. DuPont de Nemours &
Company, October 1985.
187
-------
32. Radian Corporation. Technical Note: Proposed Conceptual Design to
Control Chlorofluorocarbon Emissions from Flexible Polyurethane Slabstock
Manufacture. June 1981.
33. A Search for Alternatives to the Current commercial Chlorofluorocarbons.
Presented by DuPont Chemical Company at the EPA Workshop on Demand and
Control Technologies, March 6-7, 1986, Washington D.C.
34. The DuPont Development Program on Alternatives to Commercial Chloro-
fluorocarbons. Presented by DuPont Chemical Company to U.S. EPA, March
1980.
35. Hydrogen-Containing Chlorofluorocarbons. No. 14623, Research Disclosure,
Kenneth Mason Publications, LTD., Homewell Havant, United Kingdom, 1978.
36. Insulation. Consumer Protection Division. Attorney General, State of
Texas, Austin. Texas.
37. Klimanorm. Product information pamphlet. Madison Interests. Austin,
Texas. 1986.
38. Celotex® - Professional Builder's Manual. Product Information Pamphlet,
the Celotex Corporation. 1986.
39. Styrofoam® - Specifications and Applications. Product Information
Pamphlet, The Dow Chemical Company, 1986.
40. Sueller, J.A. Smart films give a big lift to controlled atmosphere
packaging. Modern Plastics, McGraw-Hill Publishing, Volume 63, N. 8, pp.
58-59, August 1986.
41. Personal Communication with Packaging Corporation of America, August
1986.
42. Personal Communication with Genpack Corporation, August 1986.
43. Norton, F.J. Diffusion of Chlorofluorocarbon Gases in Polymer Films and
Foams. Journal of Cellular Plastics, 18 (5), pp. 300-315 (1982).
44. Written communication with J.G. Burt (consultant), September 25, 1986.
45. Personal communication with Mobil Chemical Company. Plastics Division,
September 26, 1986.
46. Protection Against Depletion of Stratospheric Ozone by Chloro-
fluorocarbons. National Academy of Sciences. Washington, D.C.. 1979.
47. Letter Report, Farber Associates to Radian Corporation, Austin, TX,
January 1987.
188
-------
48. Written communication from Jim Walters Corporation Research, January
1987.
49. Personal communication with Dow Chemical U.S.A.. Granville, OH and
Freeport. TX, August 1987.
50. Personal communication with Koppers, Inc., Oak Creek, WI» August 1987.
51. E.I. DuPont de Nemours & Company, Plastic Products and Resin Department,
Microfoam Polypropylene Foam, Information Requested by the Environmental
Protection Agency, March 1978.
52. Personal communication with Mobil Chemical, Temple, TX, August 1987.
53. Chemical Prices, Chemical Marketing Reporter, Schnell Publishing Company,
September 1. 1986.
54. Carbon Adsorption Isotherms for CFC Compounds, Calgon Corporation,
Pittsburgh, PA, 1986.
189
------- |