EPH 430/K94/028
MONTREAL PROTOCOL
ON SUBSTANCES THAT DEPLETE
THE OZONE LAYER
NEP
1994 Report of the
Flexible and Rigid Foams
Technical Options Committee
1995 Assessment
Ms. 94-8640
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UNEP
1994 Report of the
Flexible and Rigid Foams
Technical Options Committee
1995 Assessment
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Montreal Protocol
On Substances that Deplete the Ozone Layer
UNEP
1994 Report of the
Flexible and Rigid Foams
Technical Options Committee
1995 Assessment
The text of this report is composed in Courier.
Composition and co-ordination: Jean Lupinacci
Sally Rand (Co-chairs TOC)
Layout: Jean Lupinacci
Sally Rand
Reprinting: UNEP Nairobi, Ozone Secretariat
Date: 30 November 1994
No copyright involved.
Printed in Kenya; 1994.
ISBN 92-807-1453-8
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1994 Report of tie
Flexible and Rigid Foams
Technical Options Committee
for the
1995 Assessment
of the
U N E P
MONTREAL PROTOCOL
ON SUBSTANCES THAT
THE OZONE LAYER
pursuant to
Article 6
of the Montreal Protocol;
Decision IV/13 (1993)
by the Parties to the Montreal Protocol
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Disclaimer
The United Nations Environment Programme (UNEP), the Technology and Economics
Assessment Panel co-chairs and members, the Technical and Economics Options Committees
chairs and members and the companies and organisations that employ them do not endorse the
performance, worker safety, or environmental acceptability of any of the technical options
discussed. Every industrial operation requires consideration of worker safety and proper disposal
of contaminants and waste products. Moreover, as work continues -including additional toxicity
testing and evaluation- more information on health, environmental and safety effects of
alternatives and replacements will become available for use in selecting among the options
discussed in this document.
UNEP, the Technology and Economics Assessment Panel co-chaiss and members, and the
Technical and Economics Options- Committees chairs and members, in furnishing or distributing
this information, do not mike any warranty or representation, either express or implied, with
respect to the accuracy, completeness or utility; nor do they assume any liability of any kind
whatsoever resulting from the use or reliance upon, any information, material, or procedure
contained herein, including but not limited to any claims regarding health, safety, environmental
effects or fate, efficacy, or performance, made by the source of information.
Mention of any company, association, or product in this document is for information purposes
'only and does not constitute a recommendation of any such company, association, or product,
either express or implied by UNEP, the Technology and Economics Assessment Panel co-chairs
and members, and the Technical and Economics Options Committees chairs and members or the
companies ot organisations that employ them.
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ACKNOWLEDGEMENTS
The UNEP Foam Technical Options Committee acknowledges the outstanding
contributions from all of the persons, organizations, associations and corporations from
around the world participating in this technical review. Without their efforts and expertise
this report would not have been possible. A special note of thanks is directed to the many
members of Society of the Plastics Industry (SPI) and SPI of Canada, Polyisocyanurate
Insulation Manufacturers Association (PIMA), European Isocyanate Producers Association
(ISOPA), Canadian Flexible Foam Manufacturers Association (CFFMA), British Rubber
Manufacturers Association (BRMA), European Flexible Foam Manufacturers Association
(EUROPUR), European Extruded Polystyrene Foam Manufacturers Association (EXIBA),
European Phenolic Manufacturers Association (EPMA), India Polyurethane Council, Japan's
Urethane Foam Manufacturers Association, Japan Electrical Manufacturers Association
(JEMA), and others.
Committee members and members of these associations worked together under tight
deadlines to provide data, technical input and guidance, chapter drafts, and detailed reviews.
Many gave much of their personal time to contribute significantly to the content of the
report. Whilst the list of contributors to this report is very long, the committee would like to
extend sincere thanks for all their support and guidance.
Special thanks to the Dow Europe S.A. and for SPI for their gracious hospitality in
hosting committee meetings.
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Principal Authors
Chanter Two
Chanter Three
Chapter Four
ChapterFive
Chapter Six
Developing Country Perspective
Polyurethane
Appliance
Other Appliance
Boardstock
Sandwich Panels
Spray
Other Rigid Foam
Flexible Foam
Integral Skin
Phenolic
Extruded Polystyrene
Polyolefin
M. Saragapani
Mike Jeffs
ODS Consumption Data
Bob Johnson
Mike Jeffs
Mike Jeffs
Mike Jeffs
Mike Jeffs
Marion Axmith
Gert Baumann
Craig Barkhouse
Ted Biermann
Paul Ashford
Godfrey Abbott
John Minsker
Mike Jeffs
Gert Baumann
Mike Cartmell
Fran Lichtenberg
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Table of Contents
EXECUTIVE SUMMARY , ES - 1
CHAPTER THE USE OF CFCS IN THE PRODUCTION
OF FOAM PLASTICS I - 1
Introduction 1-1
Global Consumption of CFCs in Foam Plastic Products ......1-5
Technical Options to Reduce CFCs in Foam
Plastic Products .1-5
Alternative Blowing Agents 1-5
Process Modifications and Technological Alternatives 1-6
Product Substitution or Not-In-Kind I - 6
Evaluation of CFC Alternatives 1-7
Issues Affecting the Phaseout of CFCs ............1-8
CHAPTER TWO: DEVELOPING COUNTRY PERSPECTIVE II - 1
Introduction and Summary 0 - 1
Foamed Plastic Markets in Developing Countries II - 2
Provision of Technology - Imported and Indigenous II - 3
Health, Safety and Environmental Considerations .................. II - 4
Information Sources and Other Considerations . II - 4
CHAPTER POLYURETHANE FOAMS III - 1
RIGID DOMESTIC REFRIGERATOR AND INSULATION .... Ill - 1
Products and Applications Ill - 1
Production Process Ill - 2
Global Consumption of CFCs HI - 2
Global Consumptions of HCFCs HI - 3
Technical Options to Reduce Ozone Depleting Compounds . Ill - 3
Recovery/Recycling/Destruction . HI - 6
Product Substitution Ill - 7
Conclusions Ill - 8
OTHER APPLIANCES Ill - 8
Products and Applications . . Ill - 8
Production Process Ill - 8
Global Consumption of CFCs Ill - 9
Global Consumptions of HCFCs Ill - 9
Technical Options to Replace CFCs ..................... HI - 10
Recovery/Recycling/Destruction Ill - 11
Conclusions Ill - 11
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Table of Contents (continued)
.Rage
CONSTRUCTION - BOARDSTQCK/FLEXIBLE-FACED
LAMINATION Ill - 12
Products and Applications HI - 12
Production Process Ill - 12
Global Consumption of CFCs Ill - 13
Global Consumptions of HCFCs Ill - 14
Technical Options to Reduce Ozone
Depleting Compounds HI - 15
Recovery/Recycling/Destruction Ill - 16
Product Substitution Ill - 16
Conclusions Ill - 17
CONSTRUCTION AND TRANSPORT: SANDWICH PANELS 10-17
Products and Applications Ill - 17
Production Process HI - 18
Global Consumption of CFCs Ill - 18
Global Consumptions of HCFCs Ill - 19
Technical Options to Reduce CFC Consumption . Ill - 19
Recovery/Recycling/Destruction HI - 21
Product Substitution Ill - 21
Conclusions Ill - 21
SPRAY POLYURETHANE FOAM INSULATION HI - 22
Products and Applications HI - 22
Production Process .111-22
Global Consumption of CFCs HI - 22
Global Consumptions of HCFCs HI - 23
Technical Options to Reduce Ozone
Depleting Compounds . HI - 24
Conclusions . Ill - 24
OTHER RIGID POLYURETHANE FOAM APPLICATIONS HI - 24
Slabstock Ill - 25
Product Applications . HI - 25
Production Process HI - 25
Technical Options for Reducing CFC
Consumption Ill - 25
Conclusions Ill - 26
Pipe-In-Pipe/Preformed Pipe , III - 27
Products and Applications Ill - 27
Production Process Ill - 27
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Table of Contents (continued)
Page
Technical Options to Reduce CFC
Consumption Ill - 27
Conclusions Ill - 28
One Component Polyurethane Foam Ill - 28
Products and Applications Ill - 28
Production Process Ill - 29
Technical Options to Reduce CFC
Consumption Ill - 29
Conclusions Ill - 30
Global Consumption of CFCs Ill - 30
Global Consumption of HCFCs Ill - 31
FLEXIBLE POLYURETHANE FOAMS .f . , , 111 - 31
Products and Applications Ill - 31
Production Process Ill - 32
Global Consumption of CFCs and HCFCs Ill - 35
Technical Options to Reduce CFC Consumption Ill - 36
Product Substitutes Ill - 43
Conclusions , Ill - 44
INTEGRAL SKIN AND MISCELLANEOUS FOAMS HI - 44
Products and Applications Ill - 44
Production Process Ill - 45
Global Consumption of CFCs and HCFCs Ill - 46
Technical Options to Reduce Ozone
Depleting Compounds Ill - 46
Product Substitution Ill - 47
Conclusions Ill - 47
CHAPTER FOUR: PHENOLIC FOAMS IV - 1
Products and Applications IV - 1
Production Process IV - 2
Global Consumption of CFCs IV - 3
Global Consumptions of HCFCs IV - 3
Technical Options to Reduce Ozone Depleting Compounds IV - 4
Recovery/Recycling/Destruction IV - 6
Product Substitution IV - 6
Conclusions IV - 7
CHAPTER FIVE: EXTRUDED POLYSTYRENE V - 1
EXTRUDED POLYSTYRENE SHEET V - 1
Products and Applications V - 1
iii
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Table of Contents (continued)
Page
Production Process V - 2
Global Consumption of CFCs V - 2
Technical Options for Blowing Agents V - 3
Conclusions V - 6
EXTRUDED POLYSTYRENE INSULATION BOARD . V - 6
Products and Applications V - 6
Production Process V - 7
Global Consumption of CFCs and HCFCs V - 8
Technical Options to Reduce CFCs V - 9
Recovery/Recycling/Destruction V - 13
Product Substitutes V - 14
Phaseout Schedule V - 14
Conclusions V - 15
CHAPTER SIX: POLYOLEFIN VI - 1
Products and Applications VI - 1
Production Process VI - 2
Global Consumption of CFCs VI - 3
Global Consumption of HCFCs and Projected Growth VI - 3
Technical Options to Reduce Ozone Depleting
Compounds VI - 3
Recovery/Recycling/Destruction VI - 6
Product Substitution VI - 7
Conclusions I VI - 7
APPENDIX A: UNEP FOAMS TECHNICAL OPTIONS COMMITTEE
IV
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List of Tables
Table ES-1. Major Applications and Types of Foams . ES - 2
Table ES-2. Table 1-2. CFC Alternatives Available to the Foam Industry ES - 6
Table 1-1. Status of Evaluation of CFC Alternatives for Foams 1-2
Table 1-2. CFC Alternatives Available to the Foam Industry 1-9
Table III-l. Global CFC Consumption for Refrigerator
and Freezer Insulation in 1993 Ill - 2
Table III-2. Global HCFC Consumption for Refrigerator
and Freezer Insulation in 1993 Ill - 3
Table III-3. Energy Performance of Blowing Agents Ill - 6
Table HI-4. Global CFC Consumption for Other Appliances in 1993 Ill - 9
Table IH-S. Global HCFC Consumption for Other Appliances in 1993 Ill - 9
Table III-6. Global CFC Consumption in Construction -
Boardstoek/Flexible-Faced Lamination 10-13
Table HI-7. Global HCFC Consumption for Construction -
Boardstock/Flexible-Faced Lamination Ill - 14
Table III-8. Global CFC Consumption for Sandwich Panels in 1990 and 1993 ... Ill - 18
Table HI-9. Global HCFC Consumption for Sandwich Panels in 1993 HI - 19
Table 111-10. Global CFC Consumption for Spray Foam in 1990 and 1993 Ill - 23
Table III-l 1. Global HCFC Consumption for Spray Foam in 1993 Ill - 23
Table 10-12. Global CFC Consumption for Other Rigid Foam
in 1990 and 1993 Ill - 30
Table 10-13. Global HCFC Consumption for Other Rigid Foam in 1993 Ill - 31
Table 10-14. Global CFC Consumption in Flexible Foam in 1986, 1990
and 1993 Ill - 35
Table 111-15. Global HCFC Consumption in Flexible Foam in 1986, 1990
and 1993 Ill - 36
Table IV-1. Global CFC Consumption for Phenolic Foams in 1986, 1990
and 1993 IV - 3
Table IV-2. Qlobal HCFC Consumption for Phenolic Foams in 1986, 1990
and 1993 IV - 4
List of Figures
Figure ES-1. CFC Consumption by Foam Sector: 1986, 1990, 1993 . ES - 4
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1994 VNEP FIMXIBLE AND RIGID FOAMS
TECHNICAL OPTIONS REPORT
EXECUTIVE SUMMARY
Key Conclusions
In 1993, the foam plastics industry reduced CFC consumption by 50% since
1986, despite a 45% increase in the size of the foam market over that period.
Zero OOP alternatives are the substitutes of choice in many applications
including packaging, cushioning and certain rigid thermal insulation foams.
In several markets and for certain applications HCFCs are necessary for rigid
thermal insulating foams and automotive integral skin foams until zero OOP
solutions are proven including high energy efficiency or properties required for
safety.
* CFC phaseout for developing countries is technically feasible around the year
2000 provided that Multilateral Fund projects are implemented without delay.
The main zero ODP solutions still to be proven are liquid MFCs. In addition,
broader qualification of hydrocarbons is also required. This situation is likely
to be resolved around the year 2000.
* ' Once zero ODP solutions have been proven, and are commercially available,
the implementation can be relatively rapid (3-5 years) for foam manufacturing
in developed countries. v
Full recovery and recycling of CFCs from the existing stock of foam is
logistically and technically difficult.
Summary of CFC Reduction in Foams Sector Since 1986
Historically, the fully halogenated chlorofluorocarbons (CFCs) used by the foam plastics
manufacturing industry have been extremely varied. An assortment of CFCs, such as CFC-
11, CFC-12, CFC-113 and CFC-114, and methyl chloroform, have been used in numerous
foam plastic product applications. The types and major applications of foams which used
CFCs are summarised in Table ES-1.
ES-1
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Table ES-1 Major Applications and Types of Foam Which Used CFCs
INSULATION
CUSHIONING
SAFETY
Polystyrons
Construction
I Boardstook
Polyalefm
Pipe
Rigid Potyurethane
Boardstock/FItxibli Faced
Laminates
Sandwich Panels
Spray / Pour-in-Plaoe
Slabstock
Pipe-m-Pipe
Phenolic
Bourdstock
Pipe
Appliance
Rigid Polyurethane
Refrigerators/Freezers
Picnic Boxes/Other
Rigid Polyurethane
Sandwich Panels
Transport
Polystyrene
Sandwich Panels
Slabstock
flexible Polyurethane
Automotive Interiors
Carpet Underlay
Furniture
Bedding
Moulded
Flexible Polyurethane
Furniture
Automotive Cushioning
Auto Bumper Systems
Moulded
Polyolefin
Integral Skin
Polyurethane
Sheet
Polyolafin
Flotation - Lite Vests
Polyolefm
Flotation
Board
Polystyrene
Flotation
PACKAGING
Sheet
Non-Insulation Rigid
Polystyrene
Polyoleftn
Single Service Uses
Food Packaging
Misc. Packaging
Furniture
Cushion Packaging
Polyurethane
Moulded Poiyolaftn
Boardstook Polyolefin
Cushion Packaging
Cushion Packaging
[ Auto Bumper Systems
Steering Wheels/Headrests
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This report details the available technical options that can be implemented by each foam type
to eliminate CFC usage as of 1994. Updates on the progress of each product in reducing
CFC consumption since 1986 (summarised in Figure ES-1) are also provided.
It should be noted that specific technical options and the extent of CFC reduction achieved to
date vary depending upon the foam application, market sector and applicable energy
efficiency requirements. Consequently, key factors affecting the total elimination of ozone
depleting substances from the foam plastics manufacturing industry are also discussed.
Overall, significant progress has been made in phasing-out CFCs in the foams sector. The
foam plastics industry has reduced total CFC consumption by 50% since 1986, from 267,000
tonnes in 1986 to 133,000 tonnes in 1993. Globally, CFC consumption has either been
reduced or eliminated in every market sector since 1986, despite a 45% increase in the size
of the industry over the last eight years.
Reductions have been achieved by CFC conservation, product reformulation, direct
substitution of CFCs with other blowing agents, not-in-kind substitutes or the use of new
manufacturing technologies. In general, the greatest reductions in CFC consumption have
been achieved by developed nations. For the developed countries the transition out of Annex
A, Group I substances will essentially be completed in 1994, except limited use for rigid
polyurethane foams for home appliance insulation. As discussed later, developing countries
also are working to achieve similar CFC reductions and may not require the additional time
to phaseout that the Montreal Protocol allows.
There was only one essential use nomination in the sector for 1996 relating to CFC use for
analytical/laboratory uses in alternative blowing agent research. The Foams Technical
Options Committee, the Technology and Economic Assessment Panel and the Open-Ended
Working Group were unable to recommend this nomination to the Parties of the Protocol.
The Parties decided at their October 1994 meeting not to grant an essential use for foams.
Given the availability of CFC substitutes for blowing agents, few or no additional essential
use nominations are anticipated in the foam plastics sector.
HCFCs are the major current alternative for rigid thermal insulation foam and certain other
applications. It is estimated that 60,000 tonnes of HCFCs were used in 1993. The 1993
CFC and HCFC use estimates fail to reflect the current progress being made by the foam
industry to eliminate CFCs. The real transition year for phasing out CFCs in the foam
sector is 1994.
Phaseout Status in Developed Countries
Packaging foams have completed the phaseout of CFCs. However, in developing
countries there is still over 12,000 tonnes of CFCs used for extruded polystyrene
packaging products despite the widescale availability of alternatives.
ES-3
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Figure ES-1 CFC Consumption by Foam Sector
(tonnes)
1986
(267,400)
Polyurethane (209,4
Phenolic (1,400)
f «nid»d Polystyr*n* (37,600)
Polyotafln (16,090)
1990
(174,160)
Polyurethanc (147.100)
PlMitoUe (2,700)
Extruded Poly«tyr»n» (12,000)
(12,350)
1993
(133,250)
Polyurethane (117,300)
Phanoltc (S50)
Extruded Poly»tyr«n« (14,400)
Polyotofln (900)
ES-4
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Elimination of CFCs in cushioning foams nears completion. By end of 1994
worldwide use of CFCs in this application will have been eliminated. Continued use
of CFCs are likely in developing countries and Eastern Europe.
Rigid thermal insulation foam has reduced CFC use by 45% in 1993. By the end
of 1994, CFC use will be essentially phased out, with limited use in the appliance
foam sector until mid-1995.
Automotive Foams for Safety (Integral Skin) is near complete in phasing out
CFCs. Foams used for automotive safety will have virtually eliminated CFCs by the
end of 1994.
Although significant progress has been made in the replacement of CFCs in foam
manufacture, no single solution has emerged from the transition process. Choices must be
retained to allow optimal solutions for given applications, producer-specific and country-
specific circumstances. Table ES-2 outlines currently available and long-term alternatives
undergoing testing.
Zero-ODP Alternatives
Zero-ODP alternatives are currently the substitutes of choice in many foam types and
applications. The major zero-ODP applications are:
polystyrene, polyolefm and polyurethane for packaging with CO2 (injected and
water), hydrocarbons and HFC-152a;
flexible polyurethane for cushioning with methylene chloride, CO2 (water and
injected), hydrocarbons, acetone and alternative technologies;
polyurethane and polystyrene rigid insulation foams where energy efficiency
and fire safety requirements can be met with hydrocarbons, and CO2 (water
and injected);
polyurethane integral skin for non-autornotive safety applications with CO2
(water), HFC-134a and hydrocarbons.
Transitional Substances
In several markets and for certain applications HCFCs are necessary for rigid thermal
insulating foams and automotive safety integral skin foams until other long term zero-ODP
solutions are proven. Given the availability of zero-ODP substitutes for other foam
applications, it is unlikely that there will be expanding use of HCFCs in developing or
developed countries beyond the insulation or safety foam applications.
ES-5
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Table ES-2. CFC Alternatives Available to the Foam Industry
Foam Type
yurethane:
id: Domestic
Refrigerators
and Freezers
Other
Appliances
Bonrdstock/
Flexible-Faced
Lamination
Sandwich
Panels
Spray
Siahstock
Pipe
tible; Slab
Moulded
gral Skin
nolic
ruded Polystyrene:
Sheets
Boardstocfc
yolefm
CFC Alternatives
Current
Reduced CFC-11, cyclopentane, HCFC-i41b
Reduced CFC-I1, HCFC-141b, HCFC-22,
HCFC-22/HCFC-142h Wend, pentane, COZ
(water)
HCFC-I41b, pentanes, HCFC-22
Reduced CFC-11, HCFC-141b, HCFC-22,
HCFC-22/HCFC-142b blend, pentane, HFC-
134a
Reduced CFC-11, CO2 (water), HCFC-141b
Reduced CFC-11, pentanes, HCFC-141b
COj (water), HCFC-22, HCFC-22/HCFC-142b
blends, HCFC-141b, pentanes
Extended-range polyols, CO2 (water and
injected), softening agents, methylene chloride,
methyl chloroform, acetone, AB Technology,
increased density, HCFC-141b, pentane, MDI
Technology, alternative technologies (E-Max,
accelerated cooling, variable pressure)
Increased density, methyl chloroform, extended
range polyols, CO2 (water), HCFC-I4Ih
HCFC-22, hydrocarbons, COZ (water), HFC-
134a, pentanes, HCFC-141b
HCFC-141b, hydrocarbons, LBL2,
HCFC-22/HCFC-I42b blends
HCFC-22, hydrocarbons, CO, (injected), HFC-
152a
HCFC-22, HCFC-142b, CO2 (injected)
Hydrocarbons, HCFC-22, HCFC-142b, CO2
(injected), HFC-152a
Long Term
HFCs (-245, -356, -365), vacuum panels,
hydrocarbons
HFCs (-245, -356, -365), pentanes, CO,
(water), AB Technology
HFCs (-245, -356, -365), pentanes
HFC (-245, -356, -365), pentanes, COj
(water)
HFCs (-245, -356, -365), CO2 (water)
HFCs (-245, -356, -365), CO2 (water or
injected)
HFCs (-245, -356, -365), 100% CC^ (water)
CO2 (injected), alternative technologies
Extended range polyols, CO2 (water)
COj (water), HFCs (-245, -356, -365)
HFCs (-245, -356, -365), hydrocarbons
CO, (injected), hydrocarbons, atmospheric
gases, HFCs (-134a, -152a)
HFCs (-134a, -152a), CO2 (injected)
Hydrocarbons, CO2 (injected)
ES-6
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The selection of an HCFC depends on the foam type and application. The major HCFC
applications are:
Rigid polyurethane for appliance and construction with preferred use of HCFC-14 Ib
. and minor use of HCFC-22/-142b blends;
Integral skin polyurethane for interior automotive safety components with use of
HCFC-22;
Extruded polystyrene board for construction with preferred use of HCFC-142b and
some use of HCFC-22;
Phenolic foam for building and pipe insulation with use of HCFC-141b; and
Polyolefin foam for pipe insulation with use of HCFC-142b.
In 1993, it was estimated that 60,000 tonnes of HCFCs were used to help achieve the CFC
reductions of 50% since 1986.
Developing Countries
Technology needs of developing countries are similar to those in developed countries except
that climatic conditions can be severe and enterprises may be small.
Ozone depleting substances used in the foams sector are often devoted toward fulfilling basic
societal needs such as food preservation.
The strong growth of industry in many countries makes a CFC phaseout in as short a time as
is practicable, for example about 2000, a high priority so as to not increase significantly
atmospheric chlorine loading. Achieving a phaseout target year of about 2000 depends on:
quick development of country programmes,
rapid generation of individual enterprise projects which are as cost effective as
possible so as to make best use of the MLF,
avoiding the use of intermediate technologies which can result in costly
replacement,
making most efficient use of national institutes,
using local alternatives where possible and provided that they are of acceptable
quality,
ensuring the support of governments,
availability of sufficient experts to speed training and technology transfer, and
availability of equipment to handle flammable and low boiling blowing agents.
ODS replacement programmes, however, should not compromise health or safety.
ES-7
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Long Term Zero-ODP Alternatives
The main zero-ODP solutions still to be proven are liquid HFC isomers. Th'ere also needs to
be a broader qualification of hydrocarbons. This situation is likely to be resolved around
2000. In addition to technical feasibility, qualification of these blowing agents at a minimum
includes:
Safety Uncertainties associated with the toxicity of new substitute blowing agents
and exposure to possible decomposition products formed in foams must be narrowed
to ensure worker and consumer safety. Safe handling procedures required for
substitutes of varying degrees of flammability must also be evaluated.
Environment Risks to the environment must be controllable to meet local, regional
and national standards. Environmental issues include restrictions on the emissions of
volatile organic compounds, such as hydrocarbons, and global warming concerns.
Rroduct Performance Thermal insulation and safety products must meet market
and regulatory requirements including building and fire codes, consumer/market
needs, and energy efficiency requirements. This is particularly important if
hydrocarbons are to qualify for all products in all regions.
Cost and Availability of Alternatives Substitutes must be sufficiently available and
affordable to allow for an orderly transition and to allow for products to be
manufactured and sold competitively.
National & Regional Legislation (new or proposed) -- Transition efforts will be
affected by differing national and regional legislation regulating the use of various
substitutes. Legislative diversity and inconsistency can create obstacles that impede
the implementation of substitutes particularly for companies serving multinational
markets.
Once these zero-ODP alternatives have been proven, and are commercially available, then
full implementation can be relatively rapid (3-5 years) for the foams sector.
Regovery/^tyc/Kng/Destruction
Full recovery and recycling of CFCs from the existing stock of foam is logistieaUy and
technically difficult. Where the foam can be separated from other materials, destruction of
CFC and HCFC by the incineration of the foam (a destruction technology approved by
UNEP) is currently the most effective option.
ES-8
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Chapter One
THE USE OF CFCS IN THE PRODUCTION OF FOAM PLASTICS
This report describes the use of chlorofluorocarbons (CFCs) in the production of foam
plastics and foam plastic products. Prepared by the United Nations Environmental
Programme (UNEP) Foam Technical Options Committee (Committee members are listed in
Appendix A), this report also discusses alternatives to reduce CFC use, and includes a
compilation of the Committee's findings to date.
Foam plastics that are made with CFCs and discussed in this report include:
polyurethane;
phenolic;
extruded polystyrene; and
polyolefin (polyethylene and polypropylene).
Foam plastics made with blowing agents other than CFCs are mentioned only where they
may be product substitutes or where they may clarify the scope of a particular section.
Expanded polystyrene and polyvinyl chloride foams are examples of plastic foams which are
not made with CFCs.
In this report, a chapter is devoted to each of the four foam types made with CFCs. Each
chapter discusses the various types and applications of the foam, the production process, the
use of CFCs during production, and alternatives for reducing CFC use in foam
manufacturing.
Introduction
Foam plastics can be classified on the basis of composition, chemical and physical
characteristics, the manufacturing processes, or product applications, as shown in Table 1-1.
The major applications for foam plastics include thermal insulation, packaging, and
cushioning.
1-1
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Table 1-1 Major Applications and Types of Foam Which Used CFCs
INSULATION
CUSHIONING
SAFETY
Polystyrene
Boardstoek
Construction
Polyolefm
Pipe
Rigid 3olyur«thano
Boardsteck/Flexibl« Faced
Laminates
Sandwich Panels
Spray / Pouwn-Raoe
Slabstock
Pipe-m-Pipe
Phenolic
Boardstock
Pipe
Appliance
Rigid Polyurethane
Refrigerators/Freezers
Picnte Boxes/Other
Transport
I Sandwich Panels
Polystyrene
| Sandwich Panels
Slabstock
Flexible Polyurothano
Automotive Interiors
Carpet Underlay
Furniture
Bedding
Moulded
Flexible Polyurothane
Furniture
Automotive Cushioning
Auto Bumper Systems
Moulded
Polyolefin
Integral Skin
Polyyrethane
Sheet
Polyolefin
Flotation - Life Vests
Polyolefin
Flotation
Board
Polystyrene
Flotation
PACKAGING
Sheet
Non-Insulation Rigid
Polystyrene
Polyolefm
Single Service Uses
Food Packaging
Misc. Packaging
Furniture
Cushion Packaging
Polyurothane
Moulded Polyolefm
Boardstock Polyolefin
Cushion Packaging |
Cushion Packaging
I Auto Bumper Systems
Steering Wheels/Headrests
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Foam plastics are produced by using gas or volatile liquid "blowing agents" to create bubbles
or "cells" in the plastic structure. Thermoset foam plastics (polyurethane and phenolic) are
made by introducing a volatile liquid blowing agent into liquid precursors. During the
exothermic reaction between precursor chemicals to form a plastic, the liquid blowing agent
volatises to a gas, forming bubbles which create a cellular structure when the plastic hardens.
In contrast, thermoplastic foams (polystyrene and oolyolefm) are produced by injecting a gas
blowing agent into a molten plastic resin.
In some foam plastics, the resulting cells are closed, trapping the blowing agent inside, while
in others, the cells are produced open and the blowing agent escapes.
A number of materials can be used as blowing agents, among them carbon dioxide,
hydrocarbons, chlorofluorocarbons (CFCs), and hydroehlorofluorocarbons (HCFCs). To be
considered a good blowing agent, it is required that they:
* do not react with the plastic;
be sufficiently soluble in the liquid plastic, but insoluble in the solid plastic;
and
* possess suitable boiling points and vapour pressures.
For some foam plastic products (particularly the closed-cell foams), additional blowing agent
properties are required to produce specific end-product characteristics or to facilitate the
manufacturing process. Product examples include:
» closed-cell insulating foams that require a blowing agent with low thermal
conductivity to provide its high thermal insulation efficiency;
* some thermosetting foams (especially the low-density, open-celled flexible
polyurethane foams) that rely on blowing agents to absorb some of the heat
released during production;
extruded thermoplastic foams that rely on the blowing agent to absorb some of
the heat of the molten polymer; and
» resilient closed-cell foams (especially polyolefins) that require the blowing
agent to provide dimensional stability during the air-aging period.
In addition, a non-flammable blowing agent is usually desired because it helps improve the
safety of the foam manufacturing environment and enhances the fire performance
characteristics of the end product.
Since they met these requirements and were, until recently, relatively inexpensive, CFCs had
been widely used as blowing agents for foam plastics. Historically, the foam plastics
industry used the following CFCs:
CFC-11 and CFC-113 for thermosetting foams since these blowing agents are
liquid chemicals; and
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* CFC-12 and CFC-114 for thermoplastic foams since these blowing agents are
lower boiling point gases.
This report discusses a second group of blowing agents; partially-halogenated
chlorofluoroearbons (HCFCs). Featuring at least one hydrogen atom in the molecule and a
carbon-hydrogen bond, HCFCs are less chemically stable than CFCs and tend to break down
in the lower atmosphere. Consequently, HCFCs' ability to migrate to the stratosphere and to
decompose into ozone-damaging chlorine is much lower than CFCs. Chemicals in this group
include:
» HCFC-22;
» HCFC-142b;
» HCFC-141b; and
' HCFC-123.
Currently, HCFC-22, HCFC-142b and HCFC-141b are commercially available. HCFC-123
has completed toxicity testing, but it is not commercially available to the foam insulation
market. HCFCs are becoming the predominant alternative to replace CFCs in most
polyurethane, extruded polystyrene boardstock and phenolic rigid thermal insulating
applications.
Because HCFCs contain chlorine and contribute to ozone depletion, they are considered
transitional substances. In 1992, Parties to the Montreal Protocol signed the Copenhagen
Amendment which agrees to phaseout allowable HCFC consumption between 1996 and 2030.
The international HCFC phaseout does not include chemical specific reductions, but some
individual countries have developed domestic regulations which phase out individual
chemicals. For instance in Europe in the United States, HCFC-141b is scheduled for
phaseout in 2003, and HCFC-22 and HCFC-142b is scheduled for phaseout in 2010. In
some European countries, HCFCs are being proposed for phaseout.
In many applications, such as packaging and cushioning foams, most if not all use of HCFCs
are being eliminated. However, major research efforts are underway to find long term
substitutes to eliminate the need for HCFCs in necessary applications such as rigid thermal
insulation and foams for automotive safety. Much of this effort involves replacement of
HCFCs with other blowing agents, such as hydrocarbons or HFCs.
Blowing agents used in foam products are released to the atmosphere at different rates,
depending upon the foam type and the molecular weight of the blowing agent. For most
open-cell foams, a large portion of the blowing agent is released during the manufacturing
process.
In contrast, closed-cell foams retain most of their blowing agent during the manufacturing
process. In insulation foam products, most often, the blowing agent is released either during
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fabrication, which may break some closed cells, or gradually over the useful life and disposal
of the product. Depending upon the type of blowing agent used, it will dissipate from the
foam at differing rates. This is a main issue regarding the long term aging of insulation
foams, which need to retain the blowing agent within the cell walls of the foam to achieve
the desired and continued insulating value.
Replacing CFCs with HCFCs will provide some foam plastic sectors an important
transitional period, while manufacturers, raw material suppliers, governments and other
researchers work towards developing long-term solutions. Long-term candidates for some
current uses are HFCs (partially halogenated fluorocarbons), hydrocarbons or alternative
processes and blowing agents.
Global Consumption of CFCs in Foam Plastic Products
The foam plastics industry used approximately 133,000 tonnes of CFCs worldwide in 1993 to
manufacture all types of foam plastic products. This represents a 50 percent reduction
compared to the 267,000 tonnes consumed worldwide in 1986. The majority of CFC use in
developed countries will be out by the end of 1994, with the exception of a few remaining
uses of CFCs in appliance foam.
Technical Options to Reduce CFCs in Foam Plastic Products
There are three potential methods for reducing the use of CFCs in the production of foam
plastic products:
» substituting alternative blowing agents for the fully-halogenated CFCs;
» modifying present production processes or using alternative technologies; and
* substituting foam p'astic products with alternative products, sometimes referred
to as Not-In-Kind (NIK) substitutes.
These technical options are briefly described here and are discussed in more detail in the
body of the report.
Alternative Blowing Agents
The use of alternative blowing agents, such as HCFCs, hydrocarbons, HFCs and inert gases,
have been identified as a way to eliminate CFCs. Alternative blowing agents are chemicals
with many characteristics similar to CFCs, but often have significantly lower atmospheric
lifetimes and, consequently, a much lower potential for depleting ozone (HCFCs), or no
potential at all, such as hydrocarbons or HFCs,
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Process Modifications and Technological Alternatives
Process modifications and technological alternatives include methods for reducing CFC
emissions either by preventing the release of CFCs into the atmosphere during foam
production or by reducing or eliminating the need for CFCs.
One method of capturing CFCs and HCFCs during the production process is carbon
adsorption. Recovery technologies, however, are more effective for open-cell foams, such as
flexible polyurethane foam, because of the relatively high percentage of CFCs released
during the manufacturing process. In contrast, carbon adsorption is less effective for closed-
cell foams, such as rigid polyurethane and extruded polystyrene, because of the relatively
small percentage of CFCs released during production.
Process modifications can also take the form of new chemical systems that expand the
present range of foam plastics requiring smaller amounts of CFCs. For example, the use of
increased levels of water in the chemical reaction modifies the existing foam production
process for polyurethane foams. Changes in polyols and other chemicals used in the foaming
part of the production process could also reduce or, in favourable cases, eliminate the need
for CFCs in both rigid and flexible polyurethane foam.
New equipment is also being designed and adapted which can reduce the quantity or
necessity of blowing agent. For instance, in flexible foam, variable pressure foam equipment
acts to simulate "altitude" effects by allowing lower density foams to be manufactured
without an auxiliary Wowing agent.
Product Substitution or Not-In-Kind
Product substitutes currently compete in all subsectors of the foam market, with the possible
.exception of appliance insulation. The appliance manufacturing production system is based
on direct automated injection of polyurethane foam raw materials between the inner and outer
shell of the appliance cabinet, which facilitates the manufacturing process. The foam-in-
place technology -utilised is a major factor in the structural integrity of the appliance cabinet.
In some uses of flexible slabstock foam, notably the outer layers of furniture cushions and
mattress ticking backing (quilting foam), fibrefill materials such as polyester batting are
competitive with flexible foam. These materials have the potential to replace at least some
portion of slabstock foam, principally the supersoft foams in some markets. Fire
performance requirements may be limitations in some applications.
Whilst products such as paper, cardboard and expanded polystyrene can be used in many
packaging applications, there are a number of special applications (such as electronic
equipment packaging) where protective foam products are the most cost effective choice.
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Polyurethane, extruded polystyrene and polyolefin packaging materials offer better moisture
barrier protection, increased durability and better cushioning protection than more
conventional materials.
Foam insulation use in buildings has significantly increased because of its high energy
efficiency combined with other physical properties, including excellent combustibility test
performance, waterproof characteristics, low density, thin profile and ease of handling.
Some polyurethane foam insulation products can be sprayed or poured in-situ. Non-foam
plastic insulation products can achieve some of these properties, but not all. In all instances,
the substitution of other products would require increases in the thickness of the product to
provide equivalent energy efficiency. These insulation products may become more
competitive if the choice of alternative blowing agents reduces the thermal conductivity of the
foam insulation.
Building design constraints, local building code requirements, and construction costs dictate
the choice of insulation material. Because of these factors, it is difficult to generalise the
potential substitution of non-foam insulation for foam insulations currently containing CFCs.
In some instances, there are substitute products available which can provide acceptable
performance. For some applications, however, there is no obvious alternative which would
not involve considerable changes in design and construction practice or loss of energy
efficiency (Curwell, 1988).
Evaluation of CFC Alternatives
The technical options for reducing or eliminating CFC use in foam are dependent upon each
foam type, since each has a distinct set of process and product application needs. Within
foam types, options can vary regionally depending upon various factors, including regional
product mix, climate; political factors, environmental regulations, product specifications and
energy efficiency requirements. Discussion of technical options, CFC reductions and the
status of evaluating alternatives will be divided into the following categories:
* Current an alternative which currently has application in a specific end use;
however, in some instances, all classification criterion may not be satisfied for
all world regions and product types; or
Long Term - an alternative which requires longer term research to determine
whether it can be implemented or is no longer considered an option. These
options are usually considered for implementation after 1997.
HCFCs are examples of current alternatives being used in the foam industry. They are
mostly being applied as alternatives in insulation products. Although considered transitional
alternatives due to ozone depletion concerns, they are generally available in commercial
quantities. Toxicity evaluations have been completed and they have been proven to be
technically viable. Conversions to replace CFCs began as early as 1989 in the extruded
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polystyrene boardstock industry and in other foam insulation sectors, conversions are either
fully underway or complete.
Hydrocarbons are alternatives that are currently being used in a number of foam applications,
including cyclopentane as foam blowing agent in appliance foam, and various forms of
pentane in extruded polystyrene, phenolic and other polyurethane applications. But whilst
hydrocarbons are commercially available and used in some regions and applications, they are
still undergoing development testing and would not be able to be introduced immediately in
all markets and for all products.
HFCs are also used to replace CFCs and HCFCs in some limited applications, such as HFC-
152a in extruded polystyrene and polyolefin packaging foams. While HFCs may be
considered a current alternative in these applications, it would not be able to be applied to
other foam products. In general HFCs are seen as potential long term options in insulation
applications.
Table 1-2 summarises the various CFC alternatives available to the foam plastics industry.
Reductions in CFC use will be achieved by using a combination of chemical substitutes,
process modifications or technological alternatives, and product substitutes.
Issues Affecting the Phaseout of CFCs
The scheduled reductions of CFCs, which is described in this report for the foam plastic
industry, assumes worldwide availability of substitutes and no future regulations that could
restrict the ability of substitutes from being adopted on either a global or regional basis.
Some of the key factors affecting further reductions in CFC and HCFC use include: safety
issues, environmental concerns, product performance, availability of alternatives and national
and regional legislation. These issues will be discussed further in the appropriate chapters of
the report.
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Table 1-2. CFC Alternatives Available to the Foam Industry
Foam Type
Polyurethane:
Rigid: Domestic
Refrigerators and
Freezers
Other
Appliances
Boardstock/
Flexible-Faced
Lamination
Sandwich
Panels
Spray
Slabstock
Pipe
Hexible: Slab
Moulded
ntegral Skin
'henohc
Extruded Polystyrene:
Sheets
Boardstock
'olyolefin
CFC Alternatives
Current
Reduced CFC-11, cyelopentane, HCFC-141b
Reduced CFC-11, HCFC-141b, HCFC-22,
HCFC-22/HCFC-142b blend, pentane, CO2
(water)
HCFC-l41b, pentanes, HCFC-22
Reduced CFC-11, HCFC-14lb, HCFC-22,
HCFC-22/HCFC-142b blend, pentane, HFC-
I34a
Reduced CFC-11, CO, (water), HCFC-141b
Reduced CFC-11, pentanes, HCFC-141b
CO2 (water), HCFC-22, HCFC-22/HCFC-142b
blends, HCFC-I41b, pentanes
Extended-range polyols, CO2 (water and
injected), softening agents, methylene chloride,
methyl chloroform, acetone, AB Technology,
increased density, HCFC-141b, pentane, MDI
Technology, alternative technologies (E-Max,
accelerated cooling, variable pressure)
Increased density, methyl chloroform, extended
range polyols, CO, (water), HCFC-141b
HCFC-22, hydrocarbons, CO2 (water).
HFC-134a, pentane!,, HCFC-141b
HCFC-141b, hydrocarbons, LBL2 (2-
chloropropane), HCFC-22/HCFC-142b blends
HCFC-22, hydrocarbons, CO2 (in|ected),
HFC-152a
HCFC-22, HCFC-142b, CO, (injected)
Hydrocarbons, HCFC-22, HCFC-142b, CO,
(injected), HFC-152a
Long Term
HFCs (-245, -356, -365), vacuum panels,
hydrocarbons
HFCs (-245, -356, -365), pentanes, CO,
(water), AB Technology
HFCs (-245, -356, -365), pentanes
HFC (-245, -356, -365), pentanes, CO2
(water)
HFCs (-245, -356, -365), COa (water)
HFCs (-245, -356, -365), CO2 (water or
injected)
HFCs (-245, -356, -365), 100% COj (water)
CO2 (injected), alternative technologies
Extended range polyols, CO2 (water)
CO2 (water), HFCs (-245, -356, -365)
HFCs (-245, -356, -365), hydrocarbons
CO2 (injected), hydrocarbons, atmospheric
gases, HFCs (-134a, -152a)
HFCs (-I34a, -152a), CO2 (injected)
Hydrocarbons, CO2 (injected)
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Chapter Two
DEVELOPING COUNTRY PERSPECTIVE
Introduction and Summary
This chapter covers issues relating to the phaseout of CFCs used in the production of foamed
plastics in developing countries as defined under Article 5-1 of the Montreal Protocol.
Under the existing provisions of the Protocol, the developing countries are allowed to use
CFCs up to 2010 and there are no controls on HCFCs. Nevertheless, the foam
manufacturers in developing countries have expressed a strong desire to transion to more
ozone benign, contemporary technology for both domestic markets and to serve export
markets where the norm is CFC-free products. There are also a number of foams projects
submitted to the Multilateral Fund (MLF) which use non-ozone-depleting substances.
A timely conversion to CFC-free technology is especially important because the economies of
many developing countries are exhibiting extremely rapid growth, particularly in the foam
plastic-related sectors. If CFC use were to expand at similar rates for an extended period
then the positive phase out efforts achieved by developed countries could be negated.
An evaluation of technology and circumstances in developing countries indicate that CFC
phaseout in foam plastics is technically feasible around 2000. Achievement of this objective
will depend on :
Rapid development of country programmes,
Rapid generation of individual enterprise projects which are as cost effective as
possible so as to make best use of the MLF,
Avoiding the use of intermediate technologies which can result in costly
replacement,
Effective use of national institutes,
Using local alternatives where possible and provided that they are of
acceptable quality,
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' Ensuring the support of governments,
* Availability of sufficient experts to speed training and technology transfer, and
* Availability of equipment including that to handle flammable and low boiling
blowing agents.
This accelerated programme, however, should not compromise health or safety.
This chapter discusses the issues concerning the phaseout of CFCs in all the foam plastics
sectors in developing countries.
jfaamed Plastic Markets in Developing Countries
Developing countries manufacture foam plastics in all the sectors which historically used
CFCs. In most countries foam production and CFC usage per capita is low. However, in
some cases CFC use growing rapidly, at up to 20 % per annum.
Polyolefin and polystyrene foams are widely used for packaging applications (including food
packaging). Transition away from CFCs, mostly to zero OOP alternatives such as
hydrocarbons, is underway in projects financed by the MLF. However, over 12,000 tonnes
of CFC-12 are still used in extruded polystyrene food packaging products, despite the
availability of zero ODP alternatives.
Production levels of extruded polystyrene boards and phenolic insulating foams is
comparatively low. Phenolic foam production with CFCs is currently confined to India.
The demand for these products will grow as industrialisation intensifies and energy saving
measures are introduced in buildings.
Rigid polyurethane foams are widely produced in developing countries. The main
application is insulation for domestic refrigerators and freezers with production of these
articles expanding to meet domestic market demand. This is an application where foam
assists in meeting a basic societal need that of food preservation and supply. Other major
applications include commercial appliances, insulated panels and spray foam. There is
currently little or no production of boardstock/flexible faced lamination in developing
countries.
The CFC phaseout options for rigid polyurethane insulation varies, however, many are
switching to zero ODP technologies. A number of enterprises are following the European
technology trend to pentane in appliance foams. Whilst this gives a long term solution it
places a heavy emphasis on appropriate equipment replacement and safety training and
procedures. Energy efficiency is also an important consideration in developing countries,
and substitution to zero-OOP chemicals can reduce efficiency if there is no compensation for
generally higher thermal conduction.
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The polyurethane flexible foam sector is large and, in many cases, well advanced in its plans
to phase out the use of CFCs. The main option chosen to replace CFC-11 in slabstock is
methylene chloride, which means the provision of adequate health and safety precautions.
Some of the many developments in alternative equipment will also be used. Moulded
flexible foams are mainly converting to all CO, (water) blowing and integral skin foams to a
variety of solutions which include HCFCs
The Provision of Technology - Imported and Indigenous
The majority of developing countries will be relying on imported technology. This will be
provided mainly by multinational chemical suppliers who have the capability to oeliver
technology on a global basis. The competition between the chemical suppliers will help to
ensure that developing country enterprises are offered contemporary technology.
A second source of technology transfer is transplants of developed country enterprises. This
is particularly true of the Asia Pacific region where there are many enterprises partly owned
by Japanese companies.
Another important technology conduit is the foam machinery companies, many of whom
operate on a global basis. They have a key role in equipping the developing country
enterprises with state-of-the-art equipment and in training the operatives in its safe use. The
ability of these machinery companies to meet demands over the next five years will be a
critical factor in successfully meeting an accelerated phaseout of CFCs in the foams sector.
Some large developing countries, particularly China and India, have an infrastructure which
allows the development of indigenous technologies. They have the necessary technological
institutes to research technology which can support local raw material manufacturers. For
example, institutes have developed the technology and manufacture polyol formulations for
rigid polyurethane foam. Large institutes can also verify replacement technologies.
In addition, Brazil, China and India have local production of CFCs and emerging production
capability for HCFCs. CFC phaseout in some of the foam sectors may have to consider
options which may differ from the dominant choices in developed countries to take account
of national manufacturing strategies and the economics accruing from using local rather than
imported blowing agents.
Enterprises should also be aware of the need for blowing agent alternatives of the correct,
foam blowing, quality.
Technology Choices
The technological requirements of developing countries are no different to those in developed
countries. For example, to reduce climate change and conserve electricity, the foams used in
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domestic refrigerators should have the best practicable thermal insulation in line with
technology being applied in developed countries.
Developing country enterprises should also choose from a range of technologies to help
ensure that the market needs (including climatic) are met.
Another key consideration is to look look for technologies which, if possible, achieve the
transition to zero ODP technology in one step. This can save the time and capital expense of
a multistage strategy and reduce the demand on the MLF. However, this may not be
possible in all cases. Care should be taken in avoiding equipment redundancies involved
with the intermediate step or steps. Cases where a one step strategy may not be applicable
depends on exports to developed countries where a transitional technology is the norm.
Health. Safety and Environmental Considerations
Al! CFC phaseout projects should ensure that the best health and safety practises are
transferred to the developing country enterprises. The projects should always have an
adequate provision for training of operators and mandate that post implementation audits are
carried out on a regular basis. Examples of substitutes with associated risks are flammable
blowing agents and non-ozone depleting chlorinated chemicals such as methylene chloride.
Care should be taken to ensure health and safety standards are met.
Provision should also be made to ensure that regulatory limits restricting the emissions of
volatile organic compounds which contribute to the formation of ground-level ozone (smog)
are met. The global warming potential of alternatives should also be taken into account
when choices are being made.
Information Sources and Other Considerations
Developing country enterprises are being informed of the need to phase out CFCs and of the
options to achieve this by a number of institutions. An important mechanism is via UNEP
with its range of workshops and its 1994 publication of a catalogue of foam technologies.
A final important factor is national government commitment to the CFC phaseout and to the
affected enterprises. This commitment should include the rapid development of country
programmes and the availability of expertise from both developed and developing country
sources in the next few critical years.
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Chapter Three
POLYURETHANE FOAMS
Polyurethane foams are generally based on the exothermic reaction of isocyanates and
polyols. By itself, the polymerisation reaction produces a solid polyurethane. During a
process known as foam blowing, polyurethane foams are made by forming gas bubbles in the
polymerising mixture. The "blowing agent" can be either a gas chemically formed by water
or formic acid reacting with the isocyanate, or a physical blowing agent such as low boiling
inert organic compounds separately introduced into the reaction.
Used in a large variety of products, polyurethane foams can be classified into three major
categories: rigid, flexible and integral skin. Product applications include insulating materials
for buildings and appliances, cushioning products for furnishings and automobiles, packaging
for protection of high-value products, and automobile bumpers and instrument panels.
CFCs, particularly CFC-11, have been used to produce all of these foam products. In 1990,
147,100 tonnes of CFCs were used in the manufacture of polyurethane foams, reduced from
209,400 tonnes in 1986. For 1993, CFC use for polyurethane foam production was
estimated at approximately 117,300 tonnes, a 44% reduction compared to the 1986
consumption figure. Polyruethane foams accounted for approximately 88% of the total
amount of CFCs used in all foam plastic production in 1993.
Each type of polyurethane foam, its use of CFCs, and the technical options available to
reduce CFC consumption are discussed below.
RIGID DOMESTIC REFRIGERATOR AND FREEZER INSl
Products and Applications
Rigid polyurethane foams continue to be the dominant insulation used in refrigerators and
freezers. In these products the foam serves as a key element in the structure of the appliance,
as well as a very effective insulation. The foam must have adequate compressive and flexural
strength to ensure the integrity of the product under extreme temperature conditions during
shipping, as well as heavy loading during usage of the appliance. It must maintain both its
insulation effectiveness and structural properties throughout the design life of the product. Using
CFCs, foam manufacturers were successful in developing formulations which met all of these
requirements. As substitutes are developed, care must be taken to ensure that properties are not
compromised to the extent that the overall performance of the appliance is degraded.
Although the basic requirements for refrigerator/freezer foam insulation are similar for most
manufacturers, unique manufacturing facilities, local market conditions and regulatory
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requirements result in a situation where unique requirements exist for specific markets. For
example, the importance of energy consumption in the US and Japanese markets has influenced
manufacturers to use formulations with higher levels of CFCs to achieve lower conductivities
than are required in the European market.
Production Process
Liquid chemicals are injected between the outer shell and the interior liner of an appliance
cabinet where they react, flow and expand to form rigid polyurethane foam throughout the
cavity. Substantial fixtures are provided to support the walls which are under pressure from the
foam. Typically, a few percent of the blowing agent escapes from the chemical mixture and is
vented during the foaming process. Production systems do not readily lend themselves to
recovery of this lost blowing agent, so it has generally been vented directly to the atmosphere.
Over time, foam suppliers have developed formulations (using CFCs) which have properties
(viscosity, reaction speed, exotherm, etc.) that meet the needs of production processes. With
any new blowing agent, these properties must be maintained iff order to produce quality products
and control costs.
Global Consumption of CFCs in Rigid Insulation for Refrigerators and Freezers
The global usage of CFCs in refrigerator and freezer foam in 1993 is estimated to have been
32,100 tonnes. By 1993, many appliance manufacturers had already implemented major
reductions in CFC-11 content where conditions allowed. However, in some markets such as the
US, other factors, including energy regulations, safety concerns, and the need to develop plastic
Hners resistant to attack from the new blowing agents have limited the industry's ability to
rapidly reduce consumption.
The phase-out of CFCs accelerated in some markets during 1994. It is estimated that by the
first of January, 1995 the phase-out of CFC-11 will be essentially complete in the
European and US markets.
Table III-l. Estimated Global CFC Consumption for Refrigerator and Freezer Insulation
in 1993
Region Tonnes 1993
North America 8,600
Western Europe 4,400
Eastern Europe 2,800
Middle East/Africa 2,200
Central/South America 1,900
Japan 2,300
Asia Pacific 9,900
Total World 32,100
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Global Consumption of HCFCs in Rigid Insulation for Refrigerators and
Freezers
In 1993 the consumption of HCFCs in appliances was relatively low. A variety of chemicals,
including HCFC-141b, HCFC-142b, HCFC-22, and HCFC-22/HCFC-1425 mixture were being
used. However, conversion to these chemicals was generally still in the developmental phase.
During 1994 the conversion to HCFC-141b accelerated in the US market. It is estimated that by
the first of January, 1995 over 95% of the CFC-11 usage will have been converted to HCFCs so
that the annual rate of use of HCFCs in refrigerator and freezer foam will grow to
approximately 9,000 tonnes in that market. Over 95% of HCFC use is HCFC-141b. HCFCs
are little used in the European market.
Table III-2. Estimated Global HCFC Consumption for Domestic Refrigerator and Freezer
Insulation in 1993
Region Tonnes 1993
North America " 0
Western Europe 1,200
Eastern Europe 0
Middle East/Africa 0
Central/South America 0
Japan 100
Asia Pacific 100
Total World 1,400
Technical Options to Reduce Ozone Depleting Compounds
Current Options
Reduced OOP Options
Because the availability and performance characteristics of zero ODP options are
inadequate to meet the needs of all markets, it is common practice (in some areas) to utilize
options which reduce ODP as transition technologies until suitable zero ODP options are
available.
Reduced CFC-11 technology is well proven, with use in Western Europe and elsewhere
since 1989. This option allows immediate adoption in developing countries with little or
no equipment modification. It is applicable where low or zero ODP materials are not
readily available or implementable.
HCFC-141b has been proven in production and is now (1994) in wide use in the United
States. It is also used to a significant extent in some? other countries such as Japan. It
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gives the best insulation value of any of the presently available alternative technologies.
Energy consumption increase relative to CFC-11 foam is typically about 2 or 3% when
comparing formulations using relatively high percentages of blowing agent (e.g.
formulations used in North America). Care must be taken to prevent solvent attack by
the HCFC-141b on plastic liners through selection of the liner materials, foam
formulation and control of foam flow conditions. Generally, foam densities must be
increased approximately 10% (relative to CFC-11 formulations) to provide adequate
structural strength and optimum thermal conductivity. However, equipment modifications
required to use this blowing agent are minimal. HCFC-141b is slightly flammable, and
has a lower recommended occupational exposure limit than does CFC-11, so some added
ventilation may be necessary.
HCFC-22 has been used as a replacement blowing agent by some companies which have
"froth foaming" equipment. However, it has not been widely used because of the need
for equipment changes, poorer energy performance than HCFC-141b, and questions about
ageing rates.
HCFC-22/HCFC-142b mixtures have been used to some extent in Europe and Japan as
a transitional technology. Energy consumption is degraded by 5% to 10% relative to
CFC-11 foam. Equipment modifications are required in order to introduce liquified high
pressure blowing agent to the polyol formulation.
Zero OOP Options
Because of the need to eventually phase out HCFCs, attention is now being focused on
zero ODP options as the next generation blowing agent in all markets. Significant
progress has been made. These materials are generally not yet fully proven, e.g. ageing
and toxicological studies are incomplete, but some show considerable promise for the
future. Current options include the following:
Hydrofluorocarbons (HFCs) have been extensively studied as potential alternatives to the
HCFCs as replacement materials. They have the advantage of having zero ODP. Many
are also non-flammable. Negatives include the fact that they may contribute to global
wanning.
The only HFC that has experienced significant use to date is HFC-134a. It has been
used as a replacement blowing agent by a number of appliance manufactures, mostly in
Europe. It has a relatively high thermal conductivity and poor solubility in polyols.
Together, these result in product energy consumption increases of up to 5% relative to
"reduced CFC" foam products such as those used in Europe. Equipment modifications
are required in order to handle the high pressure blowing agent. It is more compatible
with plastic liners than is HCFC-141b. However, due to its inferior energy performance
and the required equipment changes, it has not been used in markets with rigorous energy
standards.
HI-4
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Hydrocarbons, most of which are readily available as bulk chemicals (although not
necessarily in all markets in the purity required for appliance foam), have the advantage
of being low cost and halogen free, with both zero OOP and near-zero GWP
characteristics. However, hydrocarbons are flammable, have relatively high thermal
conductivity, and contribute to the formation of ground-level ozone. There is also a
need for development to qualify this technology for additional markets.
Cyclopentane has the lowest thermal conductivity of the pentanes. It is already being
widely used in the appliance industry in Europe, and to some extent in Japan, Australia
and some other countries. Much of the European industry has moved directly from
"reduced CFC-11" formulations to cyclopentane, although many factories first converted
to one of the other options. Attack on plastic liners is minor with this blowing agent.
Therefore, little or no modification to materials is required. Density increases of about
10% (relative to CFC-11 foams) are required in order to provide a dimensionally stable
foam.
From an energy consumption standpoint cyclopemane performs better than HFC-134a and
other hydrocarbons. With current formulations there is an increase of up to 5% relative
to European reduced CFC-11 and up to a 12% increase compared to US technology with
higher levels of blowing agent. Switching from HCFC-141b to cyclopentane as a
blowing agent and using current formulations would result in approximately a 10%
increase in energy consumption for a typical North American refrigerator.
Handling hydrocarbons as blowing agents in the factory can be done safely if appropriate
safety measures are applied. However, significant investment in plant modifications may
be necessary, including provisions for improved ventilation, explosion-proofing, alarm
systems, and scrubbing exhaust streams. The extent of plant modifications required may
vary significantly, depending on local codes and regulations. For some foam products,
burn test standards on finished products must be met, and in some cases the use of
hydrocarbons may be limited by product safety requirements.
Long Term
AH of the zero ODP options are long term alternatives as well.
Several liquid (at room temperature) HFCs are being studied as potential replacements for the
HCFCs. These studies are concentrated on finding alternatives with energy and safety
characteristics comparable to HCFC-141b. Several candidates, including isomers of HFC-24S,
HFC-356, and HFC-365 are currently being evaluated. Non of these HFCs are commercially
available, and even experimental quantities are difficult to secure.
Improved pentane technologies are being developed to reduce foam density and to reduce the
increase in thermal conductivity with current formulations.
Ill-5
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In the United States, the refrigerator/freezer industry, along with its suppliers, is conducting a
coordinated program to evaluate the most promising candidates for the next generation blowing
agent A similar program is underway in Japan. Several HFCs are being considered, along
with cyclopentane and wil! be evaluated to determine their performance, including insulation
value and structural characteristics of the foam, In some markets, it may be necessary to
conduct additional lexicological studies before determining that any of the candidates for next
generation blowing agents can be approved for use in refrigerator/freezer foams.
Significant quantities of material are required in order to do all of the toxicity and application
testing to qualify any new material as a substitute blowing agent. Also, suppliers require time to
build manufacturing facilities to produce any new chemical after the decision to commercialize it
has been made. Therefore, it is unlikely that commercial quantities of any of the new HFCs will
be available, until around the year 2000. Table IH-3 summarizes the relative effectiveness of
some candidate zero OOP blowing agents (relative to CFC-1I) in foam insulation value.
Table III-3 Energy Performance of Blowing Agents
k-factor (@10°C)* Increased Energy
(mW/nfk) Consumption (%)
CFC-11 (US) 16 - 18 0
CFC-11 (European) . 18.5 - 19.5 8.5
Cyclopentane 19.5 -20.5 12
HCFC-141b 17-18 2
HFC-356mff 19.0 - 20.2* 3,7
HFC-245fa** " 18.0 - 18.5* NA
* Some data are analytically extrapolated to 10°C from test results at 23°C to provide a
comparison at a common temperature,
** Data for HFC~245fa is from "panels" and is not directly comparable to data for the other
blowing agents (from sections cut from refrigerators).
NA: not available
Recoyery/Recycling/Destruction
There is some activity (considerable in Europe) in attempting to recover or destroy blowing
agents when disposing of appliances. Operations include dismantling and partial recovery of
CFC-11 from the foam. Separation of the foam from the other materials is technically difficult.
It is estimated that at least one-third of the CFC-11 is dissolved in the plastic matrix and cannot
be recovered with available technology. Therefore, the most effective method to destroy CFC-
11 in the existing stock of foam is to burn the foam in a suitably designed incinerator.
When considering reeovery/recyermg of products made with alternate blowing agents, there is
some concern about safety issues when using equipment designed for non-flammable materials if
flammable blowing agents are present.
Ill-6
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Product Substitution
The most promising candidate for product substitution in the appliance foam area is the use of
vacuum panels to replace, or partially replace, polyurethane foam. A variety of designs are
currently under development. Generally they con;ist of a panel with an impermeable
barrier/container enclosing a low-conductivity filler material under vacuum. Filler materials that
have been used in panels which have been produced commercially include precipitated silica,
perlite, diatomaceous earth, and fiberglass. Barriers have generally been made from laminated
polymeric materials, frequently with metallic coatings or layers, or from thin sheets of stainless
steel. Other technologies which are being investigated include ceramic spacers, aerogels,
hydrogels, and open-cell rigid foam as filler materials, and glass as a barrier material. Vacuum
requirements range from "soft" vacuums of approximately 50 mbar for aerogel tiles to "hard"
vacuums of less than .001 mbar for ceramic spacers.
There has already been some movement to utilize vacuum panels as supplements to foam
insulation in appliances. This has generally been done in order to achieve certain targets for
energy consumption or to provide maximum storage space in a given size product. In the
United States two manufacturers have used powder-filled flat vacuum panels in refrigerators,
although relatively small production volumes were involved. Although these applications have
been discontinued, development activity is continuing and one company has announced its
intention to use larger quantities in the near future. In Europe there are three companies which
reportedly produce at least one model containing vacuum panels. In Japan there is one company
which currently produces products with vacuum panels. Another company had previously
produced at least one model with powder-filled vacuum panels, but discontinued production due
to high costs.
The energy consumption of refrigerators with vacuum panels varies, depending on such factors
as the area of coverage, the effective thermal conductivity and thickness of the panels, the
thickness of the product walls, and the quality of the foam surrounding the panels. Test results
on products have varied from a savings of 25% on a freezer using a reduced CFC-11 foam in
conjunction with the vacuum panels to a "break even" situation where a CO2 blown foam was
used in conjunction with vacuum panels, replacing CFC-11 blown foam in a refrigerator. In
general, vacuum panels are more effective when applied to relatively thin-walled European-style
cabinets than when applied to larger US models with thicker walls.
It should be noted, however, that the use of vacuum panels does not (with current design
practices) significantly affect the amount or quality of the insulating foam required in a
refrigerator or freezer. The volume occupied by the panels is relatively small, foam flow
patterns and density are altered when using panels, and a high quality foam is required to avoid
"edge effects" which would negate the value of the panels.
HI-7
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Conclusions
Several options exist to phase-out CFCs in rigid polyurethane foam for refrigerators and
freezers. Many of these, including some zero-ODP options have now been implemented
extensively in developed countries and are being implemented in some developing countries,
Factors which must be considered in choosing a biowing agent include energy consumption,
safety (factory and customer), VOC emissions, product reliability, foam structural
characteristics, cost, ozone depletion, and global warming. It is important that the next
generation of blowing agents deliver the best overall performance in balancing these
considerations. Some of the candidate HFC blowing agents have better thermal properties than
cyclopentane, are not flammable, and are not VOCs. However, time will be required to allow
adequate testing and development if they are to be given proper consideration.
APPLIANCES
Products and Applications
This category encompasses all "appliance" applications other man domestic refrigerators and
freezers. The main applications are :
* Water Heaters Where foam insulation leads to a significant saving in energy
consumption, particularly in designs where the space for insulation is limited,
* Commercial Refrigerators and Freezers Which are typically much larger then
domestic units and includes open top display units.
* Picnic.Bpxes (Coolers) With a premium on insulation value and strong
lightweight structures.
* Flasks and Thermoware Several types of articles require the same
characteristics as picnic boxes.
* .Refrjgeiated^gontaineis (Reefers) A very stringent application with emphasis on
durability and minimum wall thickness whilst maintaining insulation value.
Production Process
All the listed applications are produced by direct pour or injection of the foam chemicals
between the inner and outer surfaces of the article. Most are held in moulds or jigs during the
foaming process. Refrigerated containers are also produced by foaming section by section into a
large pre-assembled jigged structure.
Ill-8
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Global Consumption of CFCs in Other Appliances
Many producers in Europe and North America phased out of the use of CFC 11 during 1993.
In developing countries, several producers are developing phase out plans. Consumption on a
regional basis is given in Table III-4.
Table ffl-4. Estimated Global CFC Consumption for Other Appliances in 1993
Region Tonnes 1993
North America 5,200
Western Europe 3,500
Eastern Europe 400
Middle East/Africa 200
Central/South America 200
Japan 800
Asia Pacific 2,100
Total World 12,400
Global Consumption of HCFCs in Other Appliances
Producers in North America, Western Europe and Japan are using a variety of HCFCs including
HCFC-141b, HCFC-22 and the blend of HCFC-22/HCFC-142b.
Table II1-5. Estimated Global HCFC Consumption for Other Appliances in 1993
Region Tonnes 1993
North America 1,200
Western Europe 800
Eastern Europe 0
Middle East/Africa 0
Central/South America 0
Japan 0
Asia Pacific 100
Total World 2,100
III-9
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Technical Options to Replace CFCs in Other Appliances
Current
Reduced ...CFC-1.1 Technology
Reduced CFC-11 formulations are suitable for all the applications and are a useful
intermediate step in developing countries if a full replacement technology cannot readily
be implemented. In most developed countries this technology has been replaced by
HCFCs or another alternative.
HCFC-141b
This option has been chosen by several producers, particularly those manufacturing
commercial refrigerators and freezers and refrigerated containers. This option offers the
lowest thermal conductivity of any of the current alternatives and is particularly suited to
these applications where internal volume is at a premium. Even so, there is an increase
in thermal conductivity of up to 5% which is partly compensated for by improved foam
structure/quality. For the lower density foams of about 30-32 kg/m3 density (with CFC
11) there is a need to increase density by up to 10% to ensure foam stability because of
the softening effect of HCFC 141b on the foam matrix.
Plant modifications are generally not extensive since the flainmability of HCFC 141b is
only slight and are normally confined to ensuring adequate ventilation,
HCPC-22
This option has been used by a few producers and is particularly suitable for applications,
such as thermoware, where the best possible insulation value is not of the greatest
importance. Unless it is supplied in a pre-blended form, equipment modifications are
necessary to introduce the blowing agent under pressure into the polyol formulation.
HCFC-22/HCPC-142b
This blend is suitable for all applications with the exception of refrigerated containers
because thermal conductivity is too high. As with HCFC 22 equipment modifications
may be necessary to introduce the blowing agent under pressure into the polyol
formulation.
Pjntane
Pentane isomers and cyelopentane are being used by some producers of water heaters and
commercial appliances in Europe. Extensive plant, equipment and procedural
modifications are necessary to ensure safe operations.
HI - 10
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CO-, (water blown)
Full CO2 blowing is being used by some water heater producers where the
space/thickness for insulation compensate for the loss of insulation efficiency which may
be of the order of 50% over the lifetime of the product where gaseous diffusion can take
place.
Long Term
Liquid MFCs
A series of MFCs which are liquid at ambient temperatures are being developed as
candidate replacement for HCFCs. The main products are HFC 245 isomers, HFC 356
mff and HFC 365. In addition to toxicity the key parameter will be their cost
effectiveness, in particular, the combination of their cost coupled with the thermal
conductivity of the resulting foams. An additional issue is their global warming potential.
It is unlikely that these products will be commercially available before about 2000.
Pentane
Pentane technology is still under development and it is likely that it will increase in
importance as a zero OOP option,
CO, (water blown)
It is expected that improved CO2 technology will be developed for this application in the
longer term.
Recoverv/Recvcle/Destruction
Many of the same considerations applicable for domestic refrigerator and freezer appliances
apply to this sector. There are considerable difficulties to separate the foam from the other
materials used in the construction of the article. The mosi effective solution is to destroy the
CFC (and the foam) in a suitably equipped incineration / energy recovery plant.
Conclusions
The producers and their suppliers have developed a variety of solutions to fully replace CFCs.
Several of these are HCFCs and if all the attributes of the foams, particularly energy saving, are
to be retained then sufficient time, up to about the year 2000, should be allowed to develop a
range of effective replacements for all HCFCs.
Ill- 11
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CONSTRUCTION - BQARDSTOCK/FLEXIBLE-FACED LAMINATION
Products and Applications
Polyurethane (PUR) and polyisocyanurate (PIR) foam can be continuously laminated to various
facing materials, such as aluminum foil, paper, glass roofing felts, and plasterboard. These
products are primarily used as insulation in buildings, with some also used as tank and solar
collector insulation.
In buildings, the largest use is in commercial roof insulation. Other uses include insulation for
walls, cavities, internal linings (including agricultural buildings), exterior ventilated facades
(Europe) and sheathing for residential construction (North America).
Rigid laminated PUR and PIR foams have penetrated many building,insulation markets because
these products offer the following properties:
* Low thermal conductivity High values of energy efficiency can be achieved by
using comparatively thin layers of foam insulation. Laminated foams with
impermeable facers offer the highest degree of long-term insulation value. The
low thermal conductivity was originally derived from the fine, closed-cell
polymer structure combined with CFC-11 as the main blowing agent. Retention
of low thermal conductivity is a key concern when considering alternatives.
* Fire performance - PIR and fire retarded PUR foams provide excellent fire test
results under a variety of test procedures;
Compressive strength This property is very important in roofing applications
because of the construction and maintenance traffic that a roof system, including
the insulation, must bear;
Ease of processing One advantage of the product is its ease of manufacturing
combined with its excellent adhesion to a whole range of facing materials; and,
« Ease of use and handling Laminated products are lightweight, offered in a
variety of thicknesses, provide excellent structural rigidity, and, in the case of PIR
when used on roofs, can be sealed with hot bitumen and be used without
separation technology.
Production Process
There are two principal types of continuous laminating machines:
HI - 12
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The continuous horizontal laminator used to produce products with two flexible
facers, e.g., aluminum foil, paper or roofing felt; one flexible facer and one rigid
facer; and,
The inverse laminator variation used to produce one rigid facing in sheet form.
The chemical components are metered and mixed from the mixing head onto the
pressure conveyor where external heat may be applied to promote faster curing
before the foam is moved to the cut-off saw area. This product can also be
produced using slabstock production methods.
The two main centres of manufacture are Europe and North America. In Europe, mostly PUR
foam is used with added fire retardant to obtain the desired fire properties and the term flexible
faced lamination is commonly used. In North America, boardstock is a PIR product and no fire
retardants are normally used. There is little production by this technique in developing
countries.
Global Consumption of CFCs in Construction - Boardstock/Flexible-Faced
Lamination
The estimated consumption of CFCs for lamination foams in 1993 compared to 1990 is shown in
Table IH-6. Several European producers switched out of CFC-11 beginning from 1992 and
conversion will be completed by the end of 1994. North American manufacturers eliminated the
use of CFCs by the end of 1993.
Table IH-6. Estimated Global CFC Consumption for Construction - Boardstock/Flexible-
Faced Foam in 1986, 1990 and 1993
Region
North America
Western Europe
Eastern Europe
Middle East/ Africa
Central/South America
Japan
Asia Pacific
Tonnes
1986
21,700
17,100
4,000
1,800
0
2,600
3,800
Tonnes
1990
22,700
10,600
1,200
100
600
2,600
500
Tonnes
1993
14,000
9,200
100
800
0
600
0
Total World
51,000
38,300
24,700
HI - 13
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Overall, CFCs have been used because of their ability to physically form the foam as well as to
remain in the foam cells and provide good insulating performance. They are also used because
they are inert chemicals which do not react with the other chemicals used to manufacture the
foams. In addition, they are non-flammable, relatively non-toxic, efficient, and have suitable
boiling points and have low solubility in the subsequent polyurethane polymer, but they do
dissolve in and reduce the viscosity of the polyol component. Without CFCs in the production
process, the high viscosity polyol component would make the blending, pumping, and production
methods presently used extremely difficult to operate.
Global Consumption ofHCFCs in Construction - Boardstock/Hexible-Faced
Lamination
In the US, PIR boardstock switched to HCFC 141b or in some cases blends of HCFC-141b with
small amounts of HCFC-22. HCFC-141b is the blowing agent which most closely matches the
characteristics of CFC 11, especially in terms of thermal conductivity. In Europe, producers of
flexible-faced laminate foams have chosen either iso or n-pentane or have preferred to use
HCFC 141b for an interim period. In Japan, where overall production is much lower, HCFC
14 Ib is the preferred option.
Table HI-7. Estimated Global HCFC Consumption in
Construction - Boardstock/Flexible-Faced Lamination Foam in 1993
North America 6,500
Western Europe 1,500
Eastern Europe 0
Middle East/Africa 0
Central/South America 0
Japan 500
Asia Pacific 0
Total World 8,500
III - 14
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Options to Replace CFCs in ConstructJon-Boardstock/Flexible-Faeed Lamination
Current
HCPC-141b
This option is in use by all US producers, in Japan and by many European producers. It
offers most of the advantages of CFC 11. However, the higher conductivity of the gas
may give an increase in both initial and aged thermal conductivity up to 5 % compared to
CFC 11-based foams. In addition, an increase in foam density up to 10% may be
necessary to ensure that the product is dimensionally stable.
Pentane
The n and iso isomers of pentane have been used in several European countries storting
in 1992 to answer a demand for zero OOP products. More recently there has been some
minor use of cyclopentane. Their use entails extensive modifications to the production
equipment and the factory area plus suitable operating procedures because of the highly
flammable nature of pentane.
Relative to European CFC reduced formulations the thermal conductivity is increased by
up to 10%, both initial and aged. The result is that some important product categories
cannot be produced.
Most European fire codes can be met but with major increases in fire retardant levels.
This results in a net cost increase despite the lower cost of the n and iso isomers
compared to CFC-11. Large scale fire tests with these products have shown comparable
behaviour to CFC 11-based products,
Evaluations of this option in US boardstock systems shows that all required fire tests
cannot, as yet, be met by current technology.
Pentane is also a VOC and its use in several countries, particularly the US, could be
inhibited.
Previously Considered Options
Reduced CFC-11
This technology was used for an interim period both in Europe and North America.
HCFC-22/HCFC-142b blends
These options, although evaluated, were not adopted as HCFC-141b and the pentane
isomers were preferred.
Ill - 15
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(water blown)
There has been some minor production with 100% CO2 (water) blowing but the predicted
deficiency of an increase in aged thermal conductivity of more than 50% and a density
increase of about 15% showed that current technology is not viable.
Long Term
Liquid MFCs
A series of MFCs which are liquid at ambient temperatures are being developed as
candidate zero OOP replacements for HCFC-141b. The main products are HFC-245
isomers, HFC-356 mffm and HFC-365, In addition to toxicity the key parameter will be
their cost effectiveness, in particular, the combination of their cost coupled with tfie
thermal conductivity of the resulting foams. An additional issue is their global warming
potential. It is unlikely that these products will be commercially available before about
2000.
Pentane
The applicability of this option may increase with further development, particularly with
respect to the flammability performance versus US fire codes and initial thermal
conductivity.
Extensive studies have shown that in an aged foam about one third of the CFC-1 1 is dissolved in
he plastic matrix. This means that it is not technically feasible to recover this fraction even if
Jhe balance could be recovered for recycling by a technique such as crushing die foam to break
.he cells.
Consequently, the most effective method to destroy the CFC-1 1 in the existing stock of foam is
,o burn the foam in a suitably equipped incinerator which can convert the calorific value of the
foam into energy.
In practise, the foam product could not be separated from other building materials such as felt.
Ihis reinforces the choice of incineration/energy recovery as the best option.
Product Substitution
Many other products are currently available for use as building insulation materials. These
Droduets include expanded polystyrene, fibreboard, fibrous glass (mineral fibre) and cellular
glass and have always competed for market shares with PUR and PIR products.
HI - 16
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It is extremely difficult to predict the likely movements in market shares arising from the change
to CFC-free formulations since there are other equally germaine issues affecting product
selection.
Direct substitution of foams is specifically difficult because, when a substitution is made, the
alternative material will have a higher thermal conductivity (lower insulation value) per unit
thickness.
Additional difficulties exist in building and industrial applications where there is a need for
waterproof characteristics, building code compliance and insurance requirements, combustibility
requirements, or building design constraints. In these instances, it is not always easy to
substitute directly. If a substitution was made, it would require considerable changes in design
and construction practice which will result in an increase in construction cost.
Substitute insulation products may become more competitive if the choice of alternative blowing
agent reduces the thermal conductivity or substantially increases the cost of the foam insulation.
Conclusions
The producers have mostly replaced CFCs in their products and the most commonly used
alternatives are HCFC-141b and the pentane isomers. Replacements for HCFC-141b such as
liquid MFCs are under development and, coupled with refined technology based on pentane
isomers, are expected to be available by the year 2000. If phaseout schedules for HCFCs are
accelerated much beyond the current timetable there is likely to be a considerable environmental
penalty in energy consumption.
The most effective means of disposing of CFCs in foam is by incineration / energy recovery.
CONSTRUCTION AND TRANSPORT: SANDWICH PANELS
Products and Applications
Sandwich panels have foam cores between rigid facings. The facings are often profiled to
increase rigidity. Facing materials are typically steel, aluminum or glass fiber reinforced plastic
sheet,
The panels are increasingly being used in the construction industry for applications such as:
« cold stores; for frozen and fresh food storage;
» doors: entrance and garage;
* retail stores: including the cold rooms for food storage within them; and
« factories: particularly where hygienic and controlled environments are required
such as in electronics, Pharmaceuticals, and food processing.
Ill - 17
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The panels are also used in the transport industry for the manufacture of insulated trucks and
reefers.
In all applications, the insulating property of the foam is used in conjunction with its strength
and self-adhesive capability. The panels are components of high quality modular construction
techniques and their use is growing rapidly in developed and developing countries.
Production Processes
The panel thickness, depending on application, varies from 30 to 200 mm and products over the
sntire range can be made by either continuous or discontinuous processes,
Continuous Process
The continuous process uses a horizontal laminator similar to that used for the production of
aoardstock/iflexible-faced laminates. However, additional equipment is installed to convert coiled
sheet steel to profiled facings which are fed into the laminator.'
Discontinuous Process
In the discontinuous process, pre-profiled or flat facings are assembled, with appropriate spacers,
in single- or multi-daylight or in oyster presses. The foam is injected at multiple ports or a
lance withdrawal technique is used,
Global Consumption of CFCs in Construction and Transport - Sandwich Panels
Many producers in Europe and North America switched out of using CFC-11 during the course
af 1993 and will complete the conversion during the course of 1994. Producers in developing
countries are generally at the stage of formulating their phaseout plans. The estimated
consumption of CFCs for sandwich panels in 1993 was 18,800 compared to 24,100 tonnes used
in 1990. Consumption on a regional basis is provided in Table 10-8.
Table IH-8. Estimated Global CFC Consumption for Sandwich Panels in 1990 and 1993
Region
North America
Western Europe
Eastern Europe
Middle East/ Africa
Central/South America
Japan
Asia Pacific
Tonnes
1990
5,900
9,500
1,600
800
500
3,800
2,000
Tonnes
1993
3,200
9,900
600
1,100
800
400
2,800
Total World 24,100 18,800
III - 18
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Global Consumption of HCFCs in Construction and Transport - Sandwich
Panels
Although total HCFC consumption is low, producers are switching into a variety of
replacements including HCFC-141b, HCFC-22/PCFC-142b blends and HCFC-22. There is a
comparatively minor usage of pentane isomers in Europe.
Table ffl-9. Estimated Global HCFC Consumption for Sandwich Panels in 1993
. Tonnes
Region
North America 3,400
Western Europe 2,800
Eastern Europe 0
Middle East/ Africa 100
Central/South America 0
Japan 200
Asia Pacific 0
Total World 6,500
Technical Options to Replace CFC Consumption
Current
Reduced CFC Technology
Reduced CFC 11 formulations have been used as an interim stage by several producers
but mostly have been superseded by CFC-free options in developed countries. Some
developing country producers have also adopted this technology as an intermediate step.
Product characteristics are retained except for an increase in thermal conductivity of
about 5%.
HCFC-141b i
This option has been chosen by most producers. The product characteristics have been
fully maintained. An increase in foam density has been required in some cases,
particularly in instances where the core density is less than J40 kg/m3, to offset the
softening effect of HCFC 141b on the foam matrix. /
III - 19
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The plant modifications are generally not extensive and are usually confined to ensuring
that ventilation is adequate. The foam formulations have been modified to satisfy
national fire codes.
HCFC-22
Some producers, using both continuous and discontinuous techniques, have used this
option since 1992. Equipment modifications are necessary to introduce the blowing agent
as a liquid, under pressure, into the polyol formulation.
Because of the impermeable nature of the generally steel facers, the comparatively rapid
diffusion of HCFC-22 out of the foam matrix does not cause a problem for most
applications.
HCFC-22/HCFC-142b
This option is used by several manufacturers using both continuous and discontinuous
production methods. As with HCFC-22, a pressurised introduction system is necessary
with this low boiling blowing agent blend.
The use of the blend ratio 40:60 HCFC-22:HCFC-142b eliminates the flammable nature
of HCFC-142b whilst its presence compensates for the comparatively rapid diffusion of
HCFC-22.
Pentane
Some producers in Europe are switching to the n or iso isomers or to cyclopentane to
obtain a zero ODP product. Their use may result in an increase of thermal conductivity
of up to 5 percent. Extensive and expensive modifications are required to the equipment,
factory area and operating procedures because of the highly flammable nature.
Formulations also have to be adjusted to meet applicable fire codes.
In addition, pentane is a VOC and its wide scale use may be limited.
HFC-134a
Formulations based on HFC 134a are in use for the production of sandwich panels by the
discontinuous technique. The formulations can be supplied in a pre-blended form which
obviates the need for modifications to add it as a liquid under pressure to the polyol
formulations. There is a thermal conductivity increase of about 10% compared to CFC
11-based foams.
CO? (water blown)
There is minor use of this option, particularly in applications where optimum thermal
insulation is not a high priority.
Ill - 20
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Long Term
Liquid MFCs
A series of MFCs which are liquid at airbient temperatures are being developed as
candidate replacement for HCFCs. The main products are HFC 245 isomers, HFC-
356mff and HFC-365. In addition to toxicity the key parameter will be their cost
effectiveness, in particular, the combination of their cost coupled with the thermal
conductivity of the resulting foams. An additional issue is their global warming potential.
It is unlikely that these products will be commercially available before about 2000.
Pentane
Pentane technology is still under development and it is likely that it will increase in
importance as a zero OOP option.
CO? (water blown)
It is expected that improved CO2 technology will be developed in the longer term for
such applications as doors.
Recoverv/Recvcle/Destruction
As with boardstock/flexible-faced lamination, it is not technically feasible to recover and then
recycle all the CFC-11 from the existing stock of foams. After separating the foam from the
rigid and generally non-combustible facers, the most effective method to destroy the CFC-11 is
to burn the foam in a suitably equipped incinerator which can convert the calorific value of the
foam into energy.
Product Substitution
Many of the considerations listed for boardstock/flexible-faced laminates are equally applicable
for sandwich panels. However, direct substitution of polyurethane foam in structural
applications is less likely since the polyurethane foam contributes significantly to the overall
properties of the panel in a manner which fibrous products, for example, cannot match.
Conclusions
The producers have mostly replaced CFCs in their products and the most commonly used
alternatives are HCFC-141b and HCFC-22/HCFC-142b and the pentane isomers. Replacements
for HCFC-141b and HCFC-22/HCFC-142b such as liquid HFCs are under development and,
coupled with refined technology based on CO2 (water), pentane isomers and HFC-134a, are
expected to be available by about the year 2000. If phaseout schedules for HCFCs are
HI - 21
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accelerated much beyond the current timetable there is likely to be a considerable environmental
penalty in energy consumption.
The most effective means of disposing of CFCs is by incineration/energy recovery.
SPMAY POLYUKETHANE FOAM INSULATION
Sprayed foams are used for in situ application of rigid thermal insulation. Their major use is in
roofing applications, especially in North America. Worldwide, sprayed foams are used for
residential and commercial buildings, industrial storage tanks, piping and ductwork, and
refrigerated transport trailers and tanks. Spray foam is applied by contractors in the field in
accordance with the instructions of manufacturers of spray foam systems.
Production Process
Spray foam is applied using a hand-held pressurized spray gun, in which separate polyol and
isocyanate liquids are metered under pressure, mixed and then dispensed. Different formulations
or processing parameters impart specific properties to the foam, such as increased compressive
strength, good dimensional stability at high heat and humidity, and greater high temperature
stability. The ability of the formulator to adjust foam properties is beneficial, considering the
foam is applied in a variety of climatic conditions.
The foam is sprayed directly from the mixing head onto the substrate. This method of
application facilitates coverage of large and complex surfaces. For those applications where a
thick layer of foam is needed, multiple thin layers of foam, of not less than 10 mm, are applied
to create the thick layer. The sprayed foam needs to be highly reactive, especially for adhering
to vertical surfaces during application. Pipes can also be insulated with spray foam by using a
fixed spray gun and rotating and traversing me pipe.
Globed Consumption of CFCs in Spray Foam
Several users switched away from CFC-1 1 during 1993, The estimated consumption of CFCs
for spray foams in 1993 was 11,000 tonnes compared with 12,800 tonnes used in 1990.
Consumption on a regional basis is provided in Table 01-10.
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Table IH-10. Estimated Global CFC Consumption for Spray Foam in 1990 and 1993
Region
North America
Western Europe
Eastern Europe
Middle East/ Africa
Central/South America
Japan
Asia Pacific
Total World
Tonnes
1990
6,000
1,500
500
500
500
2,300
1,500
12,800
Tonnes
1993
4,100
1,900
100
1,200
100
2,400
1,200
11,000
Global Consumption ofHCFCs in Spray Foam
Several users switched to HCFC-141b during 1993, but the biggest transition year was
1994.
Table HM1. Estimated Global HCFC Consumption for Spray Foam to 1993
Region Tonnes
1993
North America 800
Western Europe 200
Eastern Europe 0
Middle East/Africa 0
Central/South America 0
Japan 1,300
Asia Pacific 0
Total World 2,300
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Technical Options to Reduce CFC Consumption
Current
HCFC-141b
HCFC-141b is a proven technology in wide use. In most instances, this is combined with
small amounts of water to generate CO2, The benefits of CFC 11-based spray foam are
retained. No machinery modifications are required.
,dQ2 (water blown)
One hundred percent CO2 blowing is a proven technology but is not in wide use because
of the increase in thermal conductivity of the foam. Currently, the mechanical properties
of foam blown with 100% CO2 are similar to those based on CFC-11. Thermal
conductivity has increased by 20-25% in initial value to more than 50% in aged value.
Foam density has to be increased by 20-30%.
Long Term
A series of MFCs, which are liquid at ambient temperatures, are being developed as candidate
replacements for HCFCs. These include isomers of HFC-245, HFC-356 and HFC-365. Issues
include toxicity, global warming potential and cost effectiveness, in particular, cost combined
with thermal conductivity of the resulting foams. AH evaluations are at an early stage and these
products will not be commercially available before about 2000. Hydrocarbons may not be a
viable choice for spray foam due to flammability concerns. As a result, future developments for
spray foam may go in the direction of CO2 or water based foams due to the projected cost of
HFCs.
Conclusions
Due to the requirements of spray foams, HCFC-141b is the key alternate at least until about the
year 2000. AH evaluations of HFCs are in the early sages and foams blown with 100% CQj
have an initial increase in thermal conductivity of 20-25%.
RIGID POLYURETHANE FOAM APPLICATIONS
Other rigid polyurethane foam applications include slabstock, pipe-in-pipe, and one component
foams.
In this section, Global Consumption could not be broken out by individual application and is,
therefore, shown at the end of this section.
Ill - 24
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Slabstock
Product Applications
Rigid polyurethane slabstoek is used as insulation for pipes and storage tanks, as insulation
boards in construction, and can be the insulating material for refrigerated transport containers.
Rigid slabstock can be fabricated into a variety of product shapes and forms.
Production Process
Rigid slabstock is produced using either the discontinuous or the continuous manufacturing
process. Traditionally, CFC-11 has served in both processes as the blowing agent, although
water and/or CFC-12 are sometimes incorporated into the foam mixture. During 1993, partial
conversion to alternate blowing agents took place.
Discontinuous Process
In the discontinuous method, the chemical components of a slow-reacting foam system are
weighed and hand or machine-mixed, after which they are poured into a wooden or cardboard
mould. Fitted on top of the foam, a floating lid rises with the expansion of the foam. The lid
serves to level the top surface of the foam block that is being produced. The output of the
discontinuous method can be increased by using mechanical stirrers and agitators to replace the
hand-mixing stage, or by machines that both mix and dispense the foam reaction mixture into the
mould.
Continuous Process
In the continuous process, the foam reaction mixture is dispensed continuously into a trough
lined with paper or polyethylene film and located on a moving conveyor belt. The foam expands
as it moves forward on the conveyor belt. Some belts are fitted with equipment that produces a
foam with a flat top surface, similar to the floating lid used in the discontinuous process.
In production by either method, the foam rises due to the expansion of the blowing agent and
cures. Then it is cut into sections for use in the applications and products listed above. In
general, rigid slabstock has neither a facer nor an impermeable liner attached to it.
Technical Options for Reducing CFC Consumption
Current
Immediate and short term options for slabstock are very similar to those for flexible-faced
iaminates/boardstock.
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Reduced CFC-11 Technology
Reducing the amount of CFC-11 in the foam formulation is feasible and has been
introduced by some slabstock producers. However the higher exotherm is a critical
problem in slabstock foams and limits the reductions which can be achieved,
In addition, an increase in the thermal conductivity of the foam, up to 10%, may occur
.when using reduced CFC-11 formulations and their long-term thermal ageing
characteristics may be negatively affected.
HCFC-141b
HCEC-141b is widely used by both the continuous and discontinuous slabstock producers.
The resulting foams exhibit properties which are very similar to those based on CFC-11
and have the best thermal properties. North American producers converted totally to
HCFC-141b.
Pentanes
In Europe some percentage of the slabstock production was converted to n~, iso-, or
cyclopentane as blowing agent, especially in countries or markets where HCFC-141b is
considered environmentally unacceptable, Cyclopentane is used in cases where thermal
insulation properties are specified by government codes because c-pentane yields the
highest insulation values of the pentanes.
Safety precautions are necessary for the production, foam storage area and for foam
fabrication due to the flammability characteristics of pentane.
Work is still in progress to develop formulations for highly combustion resistant foams.
Long Term
A range of liquid MFCs are being developed for commercialisation later in the decade. These
include isomers of HFC 245, HFC 356 and HFC 365, Issues which must be resolved include
toxicify and potential environmental effects such as global warming. All evaluations are at an
early phase. Where open-celled foam is an acceptable product improved all CO2 (water) blown
foam formulations may represent an option.
Conclusions
The use of pentane will require major capital investment in safety-related improvements which
may be difficult to justify for small, discontinuous slabstock producers.
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Open-celled, CO2 (water) blown foams may be an option where thermal insulation is of lesser
concern, but further process development is required. These foam will not be acceptable for all
current applications.
PIPE-IN-PIPE/PREFORMED PIPE
Products and Applications
Foam-insulated pipe-in-pipe sections typically have an inner steel pipe which is surrounded with
foam insulation which, in turn, is protected by a plastic outer skin. These pipes are installed
underground and are used to transport hot water from a central boiler to surrounding dwellings.
Similar pipes and others insulated with preformed pipe sections are used in production units and
chemical plants for the transport of hot or cold fluids. Large diameter insulated pipes may have
post-applied elastomeric or bituminous coatings to provide a permanent water barrier.
Production Processes
Pipe-in-pipe sections are produced by injecting the foam chemicals into the cavity between the
inner and outer pipes. Preformed pipes are produced by pouring or injecting the foam chemicals
into half-section moulds.
i
Continuous processes have been introduced in which the foam is injected onto the inner pipe,
cured and the outer plastic cover is then extruded onto the foam through an annular die.
Technical Options to Reduce CFC Consumption
Current
CO, (water blown)
Several European pipe-in-pipe producers converted some portion of their product line to
all CO2 (water blown) technology. Key considerations for this option include:
The pipe-in-pipe construction minimises ageing of the foam thermal
conductivity; and,
* A zero ODP option was preferred or required in Scandinavia, which has a
significant share of the world market for this application.
Appropriate certifications for these products were obtained. Other portions of this
market, however, required better thermal insulation values and/or physical properties,
which could not be achieved with all CO2 (water blown) foam.
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HCFC-Ulb
HCFC-141b is in use in Europe and especially in North America for this application and
offers the highest thermal insulation values.
Cvclopentane
latest developments have shown that eyelopentane can be used in this application and
some European companies have introduced pipe-in-pipe products or are shortly doing so.
Insulation values are reported to be comparable to HCFC-141b blown foams in this
application.
A modification of this technology is the use of a hydrocarbon/noble gas blend.
Long Term
Further development work and capital investment will be required for the widespread acceptance
of pentanes.
*.
CO2 (water) technology will be a viable alternative in the pipe-in-pipe market, provided further
improvements will be made.
No development efforts for MFCs are currently known.
Conclusions
The large scale industrial production of pipe-in-pipe insulation in few production sites will make
it likely that pentanes will be become the preferred blowing agents. HCFC-141b may be
replaced before the year 1998.
Producers who select CO2 (water) as the blowing agent must make system design changes to
compensate for the inherently lower insulation value.
ONE COMPONENT POLJUSETHANE FOAM
Products and Applications
One component foams are used by both the building industry and the do-it-yourself market in a
variety of applications. These include draft-proofing around pipes, cable runs, doors, and
windows; sealing doors and window frames; and joining insulating panels, rooting boards, and
pipe insulation. One component foams are preferred because they are portable and easy to
apply, and offer both thermal and sound insulation properties.
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Production Process
One component foams are polymeric MDI-based prepolymer compositions that historically
contained dissolved CFC-12. CFC-12, which has a lower boiling point than CFC-11, has been
used because it acts as a propellant and because u produced "frothed" foam, thereby preventing
the material from flowing away from the site of its application. Additionally, one component
foams do not generate enough heat to volatilise CFC-11.
One component foams are supplied in pressurized cylinders and aerosol cans fitted with a nozzle
through which a thin strip of material is extruded. After application, the foam expands at room
temperature and cures by reacting with moisture in the air. This characteristic is unique to one
component foams. The foam continues to cure internally after becoming dry to the touch as
moisture from the air diffuses into the foam. The total time needed for foam cure depends on
temperature and relative humidity.
Technical Options to Reduce CFC Consumption
Current
HCFC-22 or HCFC-22/HCFC-142b blends
HCFC-22 or HCFC-22/HCFC-142b blends can produce one component foam with
characteristics similar to foams containing CFC-12. Manufacturers have introduced these
blends into product formulations.
Propane or Butane
Hydrocarbons, such as butane or propane, have been introduced by many one component
foam manufacturers because they have zero OOP, Changes were required in the foam
packaging plants because of the flammability of die blowing agent/propellant.
Dimethyl Ether (DME)
DME is currently being used as the sole blowing agent or in combination with the above.
However, its flammability also may require changes of the filling equipment and plants.
Long Term
Hydrocarbons, possibly in combination with DME, will also be long-term alternatives. HFC-
152a will be evaluated but formulation changes are required to accommodate this HFC. Water
to generate CO2 cannot be used in this application.
Ill - 29
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Conclusions
The need for intermediate and long-term strategies depend more on application needs and
product characteristics than on environmental issues, because of the availability of zero OOP
options.
The search for long-term options will be dictated by blowing agent solubility characteristics.
Prospective replacements can include many low boiling compounds, such as HFC-152a.
Global Consumption of CFCs in Other RigM Polvurethane Foam Applications
The estimated consumption of CFCs for other rigid polyurethane foams was 7,000 tonnes
compared with 11,300 tonnes in 1990. Consumption on a regional basis is provided in Table
IH-12. The data are reported in aggregate for all sub-sectors (i.e., slabstock, pipe-in-pipe, and
one component foam) because data for the individual applications are not available. For
slabstock significant reductions in use of CFC-11 occurred in 1993. Several European
manufacturers have completed the switch away from CFC-11 for pipe-in-pipe. Most European
manufacturers no longer use CFC-12, following national regulations in several countries,
especially for one component foam. In North America, the conversion was generally to HCFC-
141b for slabstock and pipe insulation and to hydrocarbons and dimethyl ether (DME) for one
component foams.
Table HI-12. Estimated Global CFC Consumption for Other Rigid Polyurethane Foam
Applications in 1990 and 1993
Region
North America
Western Europe
Eastern Europe
Middle East/ Africa
Central/South America
Japan
Asia Pacific
Tonnes
1990
1,300
7,700
1,000
200
200
400
500
Tonnes
1993
2,000
2,500
300
200
100
0
1,900
Total World 11,300 7,000
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Global Consumption ofHCFCs in Other Rizid P&lvuretkane Foam Applications
Table 111-13. Estimated Global HCFC Consumption for
Other Rigid Polyurethane Foam Applications in 1993
. Tonnes
Region
North America 800
Western Europe 1,000
Eastern Europe 0
Middle East/Africa 0
Central/South America 0
Japan 0
Asia Pacific 0
Total World 1,800
Products and Applications
Slabstock Foams
Polyurethane flexible slabstock foams include both polyether and polyester-based foams used to
produce foam cushioning products of varying densities and firmness, in each of the generic
categories; conventional, high-resilience (HR), and combustion modified high resilience
(CMHR).
-%
Slabstock foams are widely used in furniture, bedding, carpet underlay, and automotive interiors
(both cushioning and sound dampening). Many specialty foams are used for technical
applications such as air filters, fuel cells, and anti-static packaging. Available in a range of
densities and firmness, the foams are produced in large blocks which are cut for use in
individual application.
In applications requiring combustion modified foams to meet fire safety standards, the foams
include melamine, graphite, chlorinated phosphoric esters, or alumina trihydrate to improve the
foam's flammability performance. Greater amounts of auxiliary blowing agents are normally
used in these foams to offset the increased hardness and density resulting from the introduction
of these solid additives.
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Combustion modified foams are mainly used in upholstered furniture and bedding applications.
In some countries, they are used principally in prisons, institutions and mass transit; however, in
other countries, such as the UK, their use is compulsory for all domestic applications of
upholstered furniture and bedding. Most of the technical options available for flexible slabstock
foams can be used in combustion modified foams as well, except where noted.
Moulded Foams
The most significant use of flexible moulded polyurethane foam is in the automotive field for
seat cushions, back cushions, armrests, and headrests. Flexible moulded foams are used in
seating applications for other transportation, such as trains, buses, and airplanes. A specialty
market is the sound dampening in cars by backfoaming of the carpet and/or firewall insulators
(shared with slabstock). Together, these uses account for at least 90% of the flexible moulded
foams used worldwide. The other 10 percent of moulded foams is used for non-automotive or
furniture applications.
ProductionProcess
Continuous Processes
TraditionalgbbstockMethod
In a typical continuous slabstock foam production line, the slabstock foam is produced on
an enclosed continuous conveyor belt, called a "foam tunnel", that can be over 60 metres
long.
Liquid chemicals are metered to a mixing head. Feed formulation varies for different
foam grades and between different foam producers.
The metered stream from the mixing head is dispensed to a nozzle with a traversing
pattern across the width of the initial inclined portion of the conveyor belt: this is termed
the "lay down*. The conveyor belt is lined with paper or polyethylene film to make a
"U" shaped retainer for the rising foam mass as it descends the slope.
As the polymerisation reactions proceed and cells form, the foam rises and the blowing
agents are volatilised due to internal heat generation. Within six metres of the lay down,
the foam mass generally reaches its point of maximum expansion.
The foam can be as high as 1 to 1.25 metres and up to 2.5 metres wide. From its
maximum expansion, the foam starts to release its blowing agents and some unreacted
chemicals. A ventilated tunnel, typically covering the first section of the conveyor
system, exhausts these emissions and thereby controls workplace concentrations.
The continuous slab of foam moves through the production tunnel to a cut-off saw which
slices it into blocks for curing and storage. These blocks can be as short as 1 meter or as
III - 32
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long as 60 metres. The exothermic chemical reaction continues within the foam mass
while in the curing area. The natural insulating qualities of the foam maintain the heat
for a period of several hours. Slowly, the heat dissipates while air penetrates the block
and replaces the blowing agent.
The traditional traversing slabstock process is less economical than newer methods;
consequently, the use of this process is on the decline. In addition, processing is
generally more critical, and the introduction of'CFC alternatives is more problematic.
However, the process is still the primary choice for polyester foams and many other
specialty products where cell size and cell uniformity are critical.
Maxfoam/Varimax
Developed in the early 1970s, the Maxfoam/Varimax process differs from the traditional
method in lay down and foam expansion. The metering from the mixing head is
discharged directly into the bottom of a trough, which is nearly level with the ultimate
height of the foam slab.
The rising foam mass expands and spills over the front edge of the trough and is drawn
away on a series of sloped fall plates. This slope is kept similar in shape to the rise
profile of the foam, thus allowing a downward expansion, giving the resulting foam slab
a nearly rectangular shape.
Currently the process of choice for most manufacturers, the Maxfoam/Varimax process
for flexible foam production is less complicated and more efficient that conventional
foaming (higher blocks, more density control and .firmness control).
Vertifoam
The Vertifoam process produces foam vertically rather than horizontally. This results in
full-sized .blocks at a far lower foam chemical throughput rate and a slower production
rate than conventional equipment. This more controllable rate is suited to small to
medium manufacturers, since it allows efficient operation from 500 to 3,000 tonnes per
year.
In addition, the foam blocks produced are accurately shaped and trimming losses are low.
All the skins on Vertifoam blocks are thinner and less dense than conventional blocks and
have none of the heavy top and bottom skin. These thin skins allow rapid diffusion for
cooling or recovery. Both square blocks and round blocks can be produced.
The Vertifoam process differs substantially from conventional horizontal foam machines
that need high chemical throughput rates to produce large foam blocks. The high
chemical throughput rates of conventional foam machines result in high capital costs and
large heating and ventilation requirements.
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The reductions in floor area achieved with the Vertifoam process are very substantial
up to 85% reduction has been reported. The lower chemical throughput of the process
means that a large reduction in the extraction system is possible, which in turn means
heating and ventilation costs are reduced
In countries where legislation may in the future require blowing agent recovery and/or
fume scrubbing, the low air extraction rate substantially reduces the capital and running
costs of recycling and/or scrubbing equipment.
Discontinuous Processes
Box Foam
In many developing countries where manpower is abundant, two pre-batched liquid
components are mixed together and then literally poured into a lined box, which then
expands an cures into a final block.
Moulded Foams
In the production of moulded flexible foams, chemicals are dispensed (usually a pre-
blended two component system) to an open mould of a desired shape and size. Following
mould cleaning and application of a release agent, the moulds are filled, sometimes
manually, and then closed.
As the foam reactions occur within the mould, the polymer forms and simultaneously
expends to fill the mould cavity. Many moulded products are manually flexed and/or
crushed by rollers upon removal from the mould, which opens the remaining cells. In
some cases, the newly-demouided part is heat-treated to further cure and harden the skin.
Generally, within the automotive field, flexible moulded foam can be produced by either
"hot cure" (approximately one third of production) or "cold cure" (approximately two-
thirds of production) on a worldwide basis. Hot cure foam production is used exclusively
for automotive seating and headrests. Cold cure moulded foams are used in both
automotive (seating, headrests, carpet ticking backing) and non-automotive (furniture)
uses.
CFC-11 has typically been used in supersoft grades (for back cushions) and in the low-
density grades (25 kg/m3). In 1986, approximately 10% of all moulded foam production
used CFC-11 in manufacture. In formulations using high resilience foam, auxiliary
blowing agents are essentially phased out.
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Global Consumption of CFCs and HCFCs in flexible Polvurethane Foam
Slabstock Foam CFC Consumption
Approximately 46,750 tonnes of CFC-II was used worldwide in 1986 in the production of
flexible slabstock foam. At the time, this figure represented 17% to 18% of all CFCs used in
the production of plastic products. The use of CFC-11 in the production of flexible foams has
declined substantially worldwide since 1986. The estimated consumption of CFC's for flexible
polyurethane slabstock had dropped to 12,450 tonnes in 1990 and 9,250 tonnes in 1993.
The complete elimination of CFCs in flexible foams has already been achieved in North America
and will also be eliminated in Western Europe by Jan 1, 1995. There has been tremendous
marketing/consumer pressure on the flex foam industry to supply and promote the product as
"CFC-Free".
Moulded Foam CFC Consumption
In 1986, approximately 13,700 tonnes of CFC-11 were used in the production of flexible
moulded foam worldwide. In 1990, it was estimated that 1,500 tonnes were used. In 1993,
consumption had dropped to approximately 550 tonnes (mostly In Egypt, India, Indonesia,
Malaysia, China, the'Philippines, and Argentina).
There has been a trend towards using less CFC-11 in moulded foam applications as automobile
manufacturers increase densities of the foam seats. In moulded foams, however, the CFCs are
used not only for density reduction, but also for flowability of the foam system in the moulds.
Table IJ1-14. Estimated Global CFC Consumption in Flexible Polyurethane Foam
in 1986, 1990 and 1993
Region
Slabstock
North America
Western Europe
Eastern Europe
Middle East/ Africa
Central/South America
Japan
Asia Pacific
Total Slabstock
Total Moulded
Total World
Tonnes
1986
11,150
10,800
4,400
6,200
5,300
2,000
6,900
46,750
13.700
60,450
Tonnes
1990
1,350
5,900
800
1,200
1,000
900
1,300
12,450
1.500
13,950
Tonnes
1993
25
3,000
1,600
225
500
100
3,250
8,700
550
9,250
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Table HI-15. Estimated Global IICFC Consumption for
Flexible Polyurethane Foam in 1993
. Tonnes
Region
Slabstock
North America 110
Western Europe 100
Eastern Europe 50
Middle East/Africa 0
Central/South America 0
Japan 10
Asia Pacific 0
Total Slabstock 270
Total Moulded 0
Total World 270
Technical Options to Reduce CFC Consumption
Fhe flexible foam industry and its suppliers have been for more than seven years involved in
jfforts to reduce or to eliminate the use of CFCs in their manufacturing processes.
\ flood of technologies have been proposed over these years, allowing the industry to make
significant progress in the phase-out of CFCs. Today, the use of CFCs in flexible PUR has
>ecn virtually eliminated in developed countries and many developing countries have made great
strides towards the same goal. The first projects completed through the Multilateral Fund
'MLF) of the Montreal Protocol, a fund that financially supports ODS phaseout in eligible
developing countries, have been flexible foam operations.
in general, the following standards of acceptance are applied to proposed replacement
:echnologies:
« proven technology,
« commercially available,
acceptable processing,
« sufficiently safe,
« environmentally acceptable,
economically viable.
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The standard blowing agent for flexible polyurethane foam is carbon dioxide, generated from the
reaction between water and toluene diisocyanate (TDI). Auxiliary blowing agents (ABAs) are
used because there are limits on the foam properties that can be achieved with chemically
generated carbon dioxide as the sole blowing agent and because of the exothermic nature of the
water/TDI reaction. Excessive heat can lead to scorch or even auto-ignition of the foam during
the manufacturing process and subsequent curing.
The uses of ABAs are to:
soften the foam
decrease the reaction temperature,
decrease the foam density.
CFCs have for years functioned as the ABAs of choice. In view of the function of an ABA, it is
clear that an ideal alternative should allow for the same or better
hardness variations,
decrease of the exotherm,
density range.
Traditionally, densities of molded foams have been higher than slabstock foams, reducing the
function of ABAs in molding to softening alone. This has greatly facilitated the application of
CFC-free options, and substantially eliminated the use of ABAs in this category throughout the
world.
Options to reduce/eliminate CFCs in flexible PUF can be categorized as follows:
conservation,
alternative blowing agents,
chemical modifications,
alternative manufacturing technologies,
product substitution (not-in-kind).
Conservation
Conservation techniques are those technologies and procedures, understood to reduce the use of
CFCs through best management practices, reformulation and recovery/recycling.
Proper housekeeping and prudent formulation management, can save a plant up to 10% of its use
of CFCs. Some recommendations:
Use closed loop unloading systems,
« Do not flush with CFCs,
« Avoid the use of CFCs for viscosity adjustments,
Minimize the TDI index.
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Recycling/recovery is practiced in several plants in Europe on industrial scale. The ABA is first
adsorbed to activated charcoal, and subsequently desorbed through steam or nitrogen
regeneration. A precondition is a reduction of the process ventilation, which can lead to
exposure problems for production workers. Recovery of curing emissions is hardly feasible,
reducing the obtainable overall efficiency to less than 50%. Investment and operational costs are
high.
Alternative Auxiliary Blowing Agents
Methvlene Chloride (MO
Methylene chloride's combination of properties, such "as a low boiling point, relative
inertness, relatively low toxicity and virtually non-flammability have led to its use as an
auxiliary blowing agent in the foam industry. Its low photochemical ozone creation
potential (PCOP) and lack of ozone depletion potential (OOP) has increased its use
dramatically in the recent years, making it a significant CFC-replaeement in the
manufacture of polyurethane foam. MC's volatility can trigger, however, high
concentrations in the production area, requiring careful handling to avoid over exposure.
Local and regional health and environmental regulations pertaining to the use of MC vary
and may affect the use of this auxiliary blowing agent.
MC is currently the preferred replacement technology in North America, the UK and
many developing countries. Recent regulations may limit in the future the allowable MC
emissions in the US, which could reduce the application to an interim technology in that
country.
MC is capable to replace CFCs without any significant limitations, at lower costs. TTie
"learning curve", however, can be considerable as the process is less forgiving. Also,
contamination of MC with iron can cause severe scorching. It is recommended to use
only "Urethane Grade" MC. Because of its higher heat capacity it is less successfully
used in moulded PUR.
Methvlchloroform (MCF)
MCF can be used in situations where the use of MC is restricted. However, MCF is
classified as an ozone depleting substance (ODS), and subject to the same phase-out date
as CFCs. It is therefore at most an interim solution. Costs are higher than MC, and
processing is more difficult, related to the higher heat capacity of MCF.
MCF for flex foam blowing is not permitted in specific regions such as Europe and
Canada.
HI - 38
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HCFCs
HCFC-141b is technically viable alternative for flexible foam, but is an ozone depleting
substance, and therefore at best an interim solution. HCFC-123 is not commercially
available as a blowing agent for foams. Several countries have ruled out the use of
HCFCs in flexible PUR as it is believed that sufficient other "environmentally more
acceptable" options are available.
Acetone
Acetone has been proven fully capable in replacing CFC-11. Precautions must be taken
in view of its flammability. Only about 60% is needed compared to CFC-11. Capital
outlays and license fees may put the costs close or equal to those of MC.
AB Technology
This technology utilizes the reaction between TDI and formic acid to create an ABA,
consisting of equal amounts of CO and CO2. As this reaction is exothermic, a complete
replacement of CFCs is not feasible. Substantial equipment adjustments are needed and
monitoring of CO is highly recommended. This technology is used in a few European
plants, but has found no acceptance elsewhere, due to safety concerns and limited
applicability.
Pentane
At least one company in the US is reported to use pentane as an ABA. The
flammability of pentane requires extensive safety precautions similar to the use of
hydrocarbons in extruded polystyrene/polyethylene and acetone in flexible PUF. Only
about 70% is needed compared with CFC-11.
CarDio Process
The introduction of additional carbon dioxide gas in the foam system during or prior to
the mixing of the chemical compounds has been subject of investigation for quite some
time. One equipment manufacturer has recently (fall 1993) introduced the so called
"CarDio" Technology. In this process ABAs are replaced by physically introduced CO2.
The use of CO2 poses several challenges to the system:
The introduction of sufficient CO2 in the system to allow even the lowest
densities;
Control of the frothing that will occur upon exit of the reaction mixture from the
mixing head. This is related to the rapid expansion of CO2, which has a very low
boiling point, under non pressurized conditions;
HI - 39
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* How to combine the modifications needed to accommodate the frothing with the
manufacture of foam types that need no ABAs and consequently do not froth.
Designers of the CarDio system claim to have these challenges mastered. Currently six
industrial production facilities have been completed (November 1994). And four
additional units are planned for 1995, At this moment, the technology has to be labelled
as "in the process to be industrialized". Its attraction as being cost-effective (CO2 is low
priced and less is needed) and environmentally acceptable (obtained from natural sources,
no OOP, low GWP) has captured the interest of the foam producing community.
Chemical Modifications
Chemical modifications have been so far successfully applied in foam softening, but fell short in
density reduction.
§xtended,langeJPojypls
These polyols are able to provide a larger range of foam hardness, and, in that way, able
to partially replace CFC-11 as a softening agent. Some extended range polyols also
allow the use of lower TDI indexes, and will therefore lower the exotherm. This allows
in addition a reduction of the foam density. However, a complete replacement of
CFC-11, while maintaining the full production range is not (yet) possible. Additional
metering systems and tanks are needed, and the price of an extended range polyol is
higher than conventional polyol. Extended range polyols are often used in conjunction
with special additives (see next paragraph). Extended range high resilience (HR) polyols
are particularly successfully applied in moulded applications.
Softening Additives
Several additives have been developed to modify the chemistry of the flexible PUF
production process. These additives are currently predominantly softening technologies,
and do not allow densities under 21 kg/in3. Some additives can be used in addition with
extended range poiyols and reduced TDI index. In this way, the higher hardness range
from the polyol, the integral building properties of the additive and the reduction of the
exotherm from the index reduction provide together a system that may be able in the near
future to provide the full range of density and hardness while maintaining acceptable
physical properties.
Water Blown "MDI" Technology
Water blown MDI technology is widespread in the manufacture of moulded flexible foam
because of MDI's properties of inherent softness and lower exotherm, which allows
higher water formulations.
HI - 40
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Also, several chemical suppliers offer MDI-based flexible PUR systems for slabstock.
Some interesting environmental features are:
no need for auxiliary blowing agents to achieve
softness,
significant lower isocyanate emissions,
rapid curing,
lower exotherm, allowing higher water formulations.
This technology is not yet capable of producing very low densities without sacrifices to
physical performance, and is therefore limited in its application.
Alternative Manufacturing Technologies
Several technologies have recently surfaced, that could be classified as "mechanical" replacement
technologies for the use of CFCs in flexible PUR, predominantly slabstock. Many of the
common replacement technologies are:
environmentally challenged (methylene chloride,
methyl chloroform, acetone, pentane, HCFCs), or
not capable to a full replacement (extended range polyols, additives).
Also, regulations in many countries have intensified the focus on emissions from auxiliary
blowing agents, and the need to control these. This, in turn, brings up the problem of the
fugitive emissions. Fugitive emissions are 45% to 70% of the total emissions from the
manufacture of flexible PUF. Capture and treatment of these emissions in a traditional plant
setting seems technically challenging, and most likely cost prohibitive. Traditional technologies,
such as:
incineration,
liquid adsorption, or
carbon adsorption
are ill suited for the treatment of low concentration, high volume areas like the storage and
curing rooms, from which these emissions typically originate.
The "mechanical" technologies allow the integration of the curing area in the emission control,
or allow even to eliminate the use of auxiliary blowing agents altogether.
E-MAX
The E-Max process combines the production and curing steps by encapsulating the
developing bunstock in a mold as the foaming mixture is introduced to the foam line.
The foam mold allows all emissions from the process to be captured and collected,
utilizing only relatively low air flows. There is currently one full scale production
III - 41
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facility in the US. On pilot scale, 85% recovery of ABA has been reported. On
industrial scale, recovery of MC in the same range (80-90%) and reduction of TDI
emissions to non-measurable levels are reported. The costs are, however, high;
retrofitting is not possible and the enclosure of the lay-down and expansion process
complicates process control. The fact that no more facilities are constructed indicates the
process is not economically attractive.
Accelerated[Cooling Systems
The heat generated from the reaction between water and TDI limits the use of chemically
generated CO2 as sole blowing agent. Accelerated dissipation of this energy would allow
to increase the amount of CO2 that can be chemically generated up to a level that would
even allow complete elimination of the use of an auxiliary blowing agent for the purpose
of density reduction.
Accelerated cooling in itself is not patentable and several companies operate some kind of
5n house design of this technology. UNDP and The World Bank offer a design including
a full set of drawings for box-foam producers ("UniCure"), that can be manufactured
locally as part of a project covered by the MLF. Projects for about 90 of such units are
in the mean time approved through collective projects in Indonesia, Malaysia and The
Philippines, and expected to be installed in early 1995.
There are also several proprietary systems on me market that apply this technology in
several variations, sometimes including treatment of process emissions, such as:
ENVIRO-CURE
The Enyiro-Cure process is designed to eliminate the need of an auxiliary blowing agent
for cooling purposes and, for that matter, for density reduction. The remaining function
of an auxiliary blowing agentsoftening of the foamcan relatively easily be substituted
by chemical softening techniques. Enviro-Cure achieves this through an enclosed
conditioning area, designed to rapidly cool foam blocks through a closed loop air stream.
Emissions are in this way re-introduced in the foam that functions as an emission filter.
The process is very suitable to the Vertifoam process (because of its inherently thin
skins). One unit has been recently installed at a Varimax plant. One unit is currently
under construction in China financed by the MLF. The process is patented, and subject
to a license fee.
The economic consequences of the utilization of this process depend on local conditions.
In regions where proposed regulations may well forbid the use of auxiliary blowing
agents altogether, significant potential savings can be obtained compared to the alternative
of raising the density. Compared to the use of MC, the process will generate higher
chemical costs, in addition to capital and operating costs, but provides space savings
related to the elimination of the need for a curing area,
III - 42
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The feedback from future licensees will be needed to allow for a complete evaluation of
the merits of this process.
RAPID CURE Process
Similar to the Enviro-Cure process, the "Papid Cooling" process is designed to
completely eliminate the need of auxiliary blowing agents, without sacrificing quality or
product range. To achieve this, a two stage cooling device is directly attached to the
foam production tunnel, replacing the conventional curing/cooling area.
Significant reformulation is required to implement softening techniques and to make up
for reduced crosslinking, related to the elimination of unreacted TDI in die initial phase
of the cooling. The "Rapid Cure* process is patented, and requires license fees. The
chemical costs are reported to be very close to those of methylene chloride blown foams.
Capital cost are highly dependant on local lay-outs.
The process is so far applied in one facility in the US. Another unit is recently ordered
as part of an MLF sponsored project in Egypt.
Variable Pressure Systems
It is well known that the blowing efficiency increases with decreased atmospheric
pressure. This allows at higher altitudes the manufacture of lower density foams with
less, or no, auxiliary blowing agents through a higher effectiveness of the water/TDI
generated CO2. This principle can be applied at lower altitudes by encapsulation of the
foam production line and subsequent reduction of the process pressure. Conversely, the
increase of pressure reduces the effectiveness of the water/TDI induced gas generation
and in this way allows the generation of higher urea levels (a by product of this reaction).
Currently two companies offer non-ODS technology based on variable pressure:
The "VPF" Technology targets continuous foam production lines. Two production
units, utilizing this principle, have been in operation for over a year, with good
results. At least one other installation is under construction. The technology is
patented and marketed through a licensing system. The capital equipment
requirements for VPF are high - approx 3 to 5 million $US.
The "CEF" (Controlled Environment Foaming) Technology targets the "Box"
Foam market following essentially the same technology, but is drastically in
reduced complexity. The technology has just been recently presented publicly and
commercial installations are not yet in production.
Product Substitutes
There are no indications that the elimination of CFCs in flexible PUR has caused any
substitution of this material in its main applications (comfort in automotive, bedding and
furniture) where it has achieved high and ever increasing market penetration. Flexible PUR has
III - 43
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other properties that are under scrutiny such as its flammability. This is a perceived threat to its
viability in certain high risk applications and a more realistic potential reason for substitution
than relative small or non-existing price increases related to the replacement of CFCs,
Substitution rates could be different in technical applications such as acoustics, filtering,
gasketing, packaging etc, where flexible PUP had a much lower degree of penetration.
However, in this area ABAs never played a very significant role in the production process and
CFC replacement will therefore be a minor issue. Conversely, the development of variable
pressure foams may make flexible PUF more competitive in packaging foams through the
possible introduction of a higher polyurea content.
The largest not-in-kind product substitute for flexible PUR is polyester fibre-fill. It is currently
used as an outer "wrap* over flexible PUR to give soft initial feeling. Complete substitution of
polyester fibre for flexible PUR can successfully be used in low-stress applications such as
furniture backs or outside facings, however, it has limited use in high-stress applications such as
seats because of its high compression set properties.
Conclusions
* CFC-11 has been or will be eliminated from flexible slab and moulded foam by
January 1, 1995 in all of the major developed countries;
The main technical alternative at this time is methylene chloride, however, its
future is uncertain because of tightening emission requirements;
* Emerging emission regulations will put significant pressure on the future use of
auxiliary blowing agents entirely in question, with the notable exception of
injected CO2;
* Without ABAs, the flexible foam industry would mainly use various chemical and
process options;
At this time, there is no clear "best-choice" and several options may be used;
« There remains ongoing developments and other alternatives may emerge; and
Large scale product substitution for flexible polyurethane foam is unlikely.
INTEGRAL SKIN AND MISCELLANEOUS FOAMS
Products and Applications
This section includes the many types of polyurethane foams which do not fall into the rigid or
flexible category. The list of applications is long and varied.
Integral skin and miscellaneous polyurethane foams include;
111-44
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Integral Skin
flexible (or semi-rigid) integral skin foams for steering wheels, headrests,
armrests, shoe soles, beer barrels, etc;
rigid integral skin foams for computer cabinets, skis, and tennis rackets;
RIM
microcellular high-density foam for exterior body parts of automobiles;
Non-Insulation Rigid
low-density packaging foam;
floatation foam;
floral foams; and,
energy absorbing foams for side impact in automobiles.
The principal benefits of polyurethane use for these applications are performance, ease of
processing, and cost. CFCs have essentially been eliminated in these foams in most developed
countries.
Production Process
Integral skin foams are molded foams, manufactured either by injection into closed vented molds
(i.e. steering wheels) or by pouring into open molds (i.e. skin soles). These foams are
characterized by a high density outer skin and a low density, softer core. The density gradation
results from (a) blowing agent condensation at the mold surface compacting the cells of the
urethane foam, and (b) overpacking of the mold.
Microcellular high density foams (RIM) are manufactured via injection into closed molds, in
many cases using large presses to maintain clamping pressure and produce parts within
dimensional tolerances. The microcells form air nucleation and also from small amounts of CO2
(resulting in most cases from residual water).
Non insulation critical rigid foams are manufactured via a variety of processes including spray,
molding or rigid slabstock, using conventional or high pressure urethane dispensing equipment.
Most integral skin and miscellaneous foams are open cell, where the blowing agents used in
manufacture are emitted to the atmosphere during the foaming reaction or soon thereafter. Rigid
integral skin and flotation foams are closed cell, but low thermal conductivity is unnecessary in
these products.
Ill - 45
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Global Consumption of CFCs and HCFCs in Integral Skin and Miscellaneous Foams
According to global estimates, 2000 tonnes of CFCs were used in integral skin and
miscellaneous polyurethane foam manufacturing in 1993. This estimate represents less than 1 %
of CFCs used in all foam production. In 1990, global estimates placed CFC use at between
7,400 and 9,900 tonnes in these applications.
According to global estimates, 300 tonnes of HCFCs were used in integral skin and
miscellaneous polyurethane foam manufacturing in 1993. This estimate represents 0.5% of
HCFCs used in all foam production.
:i Qfftjjms,JteM^!ice CFCs wjbttegnd Skin and Miscellameousi Foams
Current
Integraljkin
For flexible (semi-rigid) integral skin foam applications deemed automotive safety related
(e.g. steering wheels), most polyurethane systems currently utilize HCFC-22, or to a
lesser extent HCFC-141b, as the blowing agent. This results in a well defined skin, with
good overall physical properties. The skin is relatively thick and its surface is smooth
and paintable. Some conversion to all water blown systems has occurred in North
America and Asia. Some moulders in Europe and Canada are producing integral skin
foams for armrests using pentane as blowing agent to form the skin.
In North America and Asia, all flexible (semi-rigid) integral skin foams, other than for
automotive safely applications and been converted to zero OOP blowing technology (no
CFCs or HCFCs). Most applications have been converted to all H2O or HFC-134a
blowing technology. In Europe, the situation is similar, although HCFC-22 is still being
used but is expected to be phased out shortly.
Rigid integral foams have essentially all been converted to water blown systems, although
some HCFC-141b is still being used in Asia.
Non-Insulation Rigid Foams
All open cell rigid foams (e.g. packaging, floral and energy absorbing foams) have been
converted to CO2 (water blown) technology (zero OOP).
Closed cell rigid foams used for flotation currently utilize mostly systems with HCFC-
22/H2O blowing technology. However, this business is converting to proven zero OOP
technology HFC-134a for pressurized dispensing systems and H2O/CO2 for
conventional systems.
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Long Term
For flexible integral skin foams used in automotive safety related equipment, development efforts
are continuing down several pathways including HFC-134a, all H2O, molecular sieve and
pentane. The molecular sieve technology has been introduced in Europe and involves H2O
trapped in a microporous structure being released via heat of reaction during the foaming
process. With the isocyanate no longer available for reaction, the H2O vapor condenses at the
mold surface forming a thin skin.
AH H2O blown systems are anticipated to be the future for manufacturing the non-automotive
safety related integral skin foams. Development efforts are being concentrated on improving
foam physical properties (such as abrasion resistance for all H2O blown shoe soles foams using
polyether polyols).
Product Substitution
In a few applications, where a very pronounced skin is deemed necessary, an alternative is to
use H2O blown flexible foam behind poly vinyl chloride (PVC). This approach is being used
presently in some applications such as arm rests for furniture and tractor seats.
Conclusions
For the most part, technology is in place to enable manufacture of integral skin and
miscellaneous foams using zero OOP technology. The remaining area still needing development
is flexible integral skin for automotive safety. In this case, some conversion to zero ODP (HFC-
134a and all water blown) has already taken place. Several alternative technical options have
been identified and are being pursued in product development to enable full conversion to zero
ODP.
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Chapter Four
PHENOLIC FOAMS
Products and Applications
Phenolic foams still represent well under 5 % of the foamed insulants used world-wide,
However, their excellent generic fire properties (particularly their extremely low smoke
emissions) are establishing the products in many applications previously served by other
insulation products. Evidence of this fact is revealed by the growth in their use since 1986
despite strong recessionary factors in some regions over recent years. With increasing
concern over fire safety world-wide, this growth is anticipated to continue making the
inclusion of phenolic foams in this report a necessary step despite their relatively low current
base.
The prime cause of growth has been the availability of processes to produce closed-ceH
products to compete with other foam equivalents. The requirement for high thermal
efficiency naturally drove the phenolic foam industry towards CFCs during the early to mid
1980s and several such technologies were developed around that time.
Phenolic foam products have gained acceptance in many types of pubHc and commercial
building. There is a small but significant level of substitution against fibrous products where
cleanliness and moisture resistance can be offered without unnecessary loss of fire
performance. This is typical in the building services sector (Heating & Ventilation), where
insulation is often exposed. Pipe laggings are an example.
However, by far the greatest proportion of substitution which has occurred against other
foam products is in the flexibly faced laminate sectoralbeit that market acceptance is
varying considerably by region. This latter fact has caused some North American producers
to reconsider their positions in recent times. In Europe, such laminates are widely used for
wall and roofing applications, particularly within the growing single-ply roofing market and,
not surprisingly, designers and builders are seeking the most fire-safe products for this
purpose. Cost usually rules against phenolic foams when considered for the domestic
environment.
More recently, activity has increased in the use of phenolic foams in rigid faced panelling for
doors and partitions. Closed-cell foam technology has been equally applicable for these
applications,
IV-1
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There is still some residual usage of open-celled phenolic foam for specific market
requirements. A prime example of this is its use for floral arrangements. The unique
wetting properties of this particular product make it virtually irreplaceable. However, these
properties are not reliant on the use of CFCs and most production had already switched to
hydrocarbons on the basis of cost.
More orthodox open-celled phenolic foams are still used in some countries, most notably the
former Soviet Union, as prime insulation. As these foams exhibit poorer insulation
characteristics than those made from the more recently developed closed-cell technologies
outlined above, there has been pressure to transfer these technologies under licence or other
co-operative agreement.
Production Processes
Discontinuous Processes
Several discontinuous processes have been developed for closed-cell foams, but undoubtedly
the most prevalent is the Block or Bun process. This has been particularly dominant in
Europe where the process lends itself to the varied requirements of Building Services market.
Complex computer-controlled cutting equipment optimises yields from blocks when cutting
pipe sections. Despite this, yields can be as low as 50% for the more awkward shapes.
Other discontinuous processes include the manufacture of rigid faced panels by injection
(normally referred to as "pour-in-place"). Multi-daylight and oyster-press routes have been
followed, but investment in these more recent sectors has only re-emerged following the
development of thermally efficient CFC-free technology.
Most, if not all, discontinuous processes have used CFC-11 and/or CFC-113 to obtain their
high thermal efficiencies historically. Accordingly, most plant technologies, and their
associated installed units, are unable to handle low boiling blowing agents. Additionally, few
plants are flame-proofed. These factors have inhibited the move to alternative blowing
agents, particularly the low boiling HCFCs and MFCs. Furthermore, it has to be said that
appropriate plant and process technologies for this purpose are likely to be difficult to
achieve and, therefore, still seem some way off.
Continuous Processes
Within the range of continuous processes, lamination with flexible facings has been the major
development over the last five years. There has been less focus on rigid faced lamination
and continuous block to date, although these may follow as and when CFC-free technologies
become available. The machines used for continuous lamination are, in the main, more
capable of processing low boiling blowing agents and, accordingly, CFC-114 has been a
common constituent within several technologies historically. It should be stressed that it is
IV-2
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the process rather than the machinery per se which facilitates the use of these materials.
Therefore, it is unlikely that much of the associated technology will be transferable to the
discontinuous operations.
Global Consumption of CFCs in Phenolic Foams
The progress in reduction of CFC consumption within the phenolic foam sector has been
steady since the last review in 1991. As will be seen in Section 4.5, technologies now exist
to replace CFCs in virtually every application. However, progress on phase-out has been
hampered in some regions by the continuing availability of CFCs at low price. Without
fiscal instruments or end-use controls in-place, some markets have continued to opt for the
lowest cost/lowest risk option. As availability of CFCs declines over the next 12-18 months
it is anticipated that there will be a rapid further reduction in use in those regions where it
has not already occurred:
Table 4.1 Estimated Global CFC Consumption for Phenolic Foams (Tonnes)
Region 1986 1990 1993
North America
Western Europe
Japan
Former USSR / Eastern Europe
Rest of World
700
400
300
0
0
1,500
700
400
NIL
100
Total 1,400 2,700 628
Global Consumption ofHCFCs in Phenolic Foams
In most cases where phenolic foams are being used as insulation, HCFCs have been the
preferred substitute. Accordingly, the growth in HCFC use shown in table 4.2 below
reflects, to a degree, the reduction in CFCs also achieved. The potential use of
hydrocarbons may influence this pattern in due course, but for the reasons given in Section
4.5 this is not imminent. Similarly, the introduction of MFCs could have an impact on
HCFC use towards the end of the century.
*
On this basis, consumption of HCFCs is expected to grow to a level of at least 2,500 tonnes
by 1998 and this may be increased further if phenolic foam continues to make market share
gains at the expense of other insulants.
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Table 4.2 Estimated Global HCFC Consumption for Phenolic Foams (Tonnes)
Region 1986 1990 1993
North America
Western Europe
Japan
Former USSR / Eastern Europe
Rest of World
0
0
0
0
0
75
50
10
0
0
Total 0 130 610
Technical Options to Reduce Ozone Depleting Compounds in Phenolic .Foams
The phenolic foam industry worldwide continues to be extremely active in seeking alternative
blowing agents for its products. As mentioned in the 1991 report, spending in excess of five
million US dollars (estimated to be 5 per cent of annual turnover) has been undertaken in
seeking solutions. The industry has undoubtedly benefitted from having technology
development teams already in place as a consequence of the relatively recent emergence of
the "base" technologies.
Current
Hydrocarbons (open-celled foams)
Achieving high thermal efficiencies is important to the growth of phenolic foam use
worldwide. In this context, open-cell pentane blown foams have not impacted the
market substantially, being 60 percent less efficient than their CFC-containing
counter-parts. In most cases, they have been superseded by HCFC-blown foams
except where zero-ODP options are essential.
Hydrocarbons (closed cell foams)
2-chloropropane continues to be of interest in certain quarters and the commercial
adoption of this technology for phenolic foam is understood to have been achieved by
at least one company in Europe. However, the material's finite ODP would appear to
rule it out as a long term solution.
HCFCs
*
The emergence of HCFC-141b as a readily available alternative has substantially
influenced the phase-out rate of CFC use in the industry. Most processes worldwide
have been able to accommodate the blowing agent, albeit with the use of additional
cell-modifiers in many cases.
IV-4
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Previous TOC reports have referred to the limitation of discontinuous processes with
respect to the blowing agent boiling points they can accommodate. For this reason,
HCFC-141b has been the only viable alternative despite its slightly higher OOP.
Continuous processes, on the other hand, are more versatile in this regard and can use
blowing agents such as HCFC-142b and FCFC-22. However, it has been found that
the emission levels experienced on many of these processes using such low-boiling
HCFCs are significant enough to have greater impact on the environment than the use
of higher-boiling alternative.
At first sight this would appear to be the outcome of poor process engineering.
However, the reality is that the emulsion-based technology, on which all phenolic
foams rely, often requires highly sophisticated techniques for distribution of material
on to the process conveyor. These techniques can cause blowing agent losses well in
excess of those normally anticipated with solution-based technology.
Longer Term
Hydrocarbons (closed-cell foams)
Further progress has been made with closed-cell foam technologies using
hydrocarbons since the last Technical Options Review in 1991. At least two
discontinuous technologies now exist and it is likely that similar chemical solutions
could be transferred to continuous processes if other factors allowed.
The major problem with the commercialisation of these technologies has been the
characterisation of end-product fire performance. As the distinctive value of phenolic
foams to the insulation industry lies in their inherent fire and smoke properties, such
uncertainty about fire performance is a debilitating problem.
Work with the UK Government has been initiated to establish comparisons with more
traditional CFC-blown systems but the magnitude of this task should not be under-
estimated in view of the variety of end-products and applications to be considered.
In view of these uncertainties, it has proved difficult to verify technologies on
continuous processes, since significant plant investment is required to handle
hydrocarbons safely in most installations.
The two factors working against the use of HFCs in phenolic foams historically have
been:
(i) The impact of the price of HFCs on the cost base of foams (the
IV-5
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sensitivity is high), and
(ii) The lack of ambient boiling MFCs for discontinuous processes.
Since the 1991 Review, HFC manufacturers have been addressing the needs of the
foam blowing industry in a more focused way. Several MFCs have emerged with
potential of being used in both continuous and discontinuous processes. These include
isomers of HFCs 245, 356 & 365, However, full lexicological testing will be
required on these before they can be introduced commercially and progress is
therefore likely to be hampered until 1998 or 1999.
Pricing issues will also remain a key factor in the final acceptance of such solutions.
Recovery/Recycle/Destruction
Closed-cell phenolic foams undergo similar emission processes to other closed-cell, CFC-
blown rigid foam boardstock; small amounts of CFCs are emitted during the production
process, while the remaining CFCs, stored in the foam cells, are released very slowly over
the life of the foam, owing to extremely low gas permeability.
Theoretically, emissions during manufacture could be collected by carbon adsorption
techniques, but in practice the actual process efficiencies would be extremely low. In
contrast, the significant cutting tosses associated with some discontinuous processes have
offered an ideal opportunity for recovery and recycling. However, despite considerable
efforts, the efficiency of recovery by carbon adsorption has not exceeded 50%.
In spite of this, the technology may continue to have benefits for the recovery of HCFCs and
HFCs in future.
The use of material recovered from other processes has also been investigated and, for the
most part, this has proved successful. With respect to destruction processes, incineration
techniques are being investigated in Europe under the European Union's Demolition Waste
Directive. Whilst phenolic foam has not been specifically characterised as yet, this method
of destruction could prove an effective source of energy recovery.
Product Substitutes
Phenolic foams are noted for their excellent thermal efficiencies and outstanding fire
performance. These factors, together with their cleanliness, moisture resistance, space-
saving and integrity must all be taken into account when considering product substitution. In
view of this wide range of product benefits, it is difficult to generalise about alternatives. If
they exist at all, they are likely to be very market specific. Little actual substitution has
taken place to date.
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Conclusions
From a technical viewpoint, the phenolic foam industry is now in a position to phase-out of
CFCs. In this regard, the industry has undoubtedly benefited from having technology
development teams already in place as a consequence of the relatively recent emergence of
the "base" technologies.
The prime replacement blowing agent to date has been HCFC-141b although some low-
boiling blowing agents (HCFCs-142b and -22) have also been used in continuous processes.
Although hydrocarbon-based technologies exist there is some concern about their early
introduction. This arises from the potential impact on end-product fire performance which
is, as yet, unquantified.
In practice, the phase-out of CFC use has been limited by commercial and liability
considerations which have arisen in the recessionary market environment worldwide. This
trend has been exacerbated in Europe by the availability of CFCs on a wider basis and at
lower prices than had originally been anticipated. Notwithstanding this, the rapid reduction
in allowable CFCs in Europe and North America through 1994/95 will drive change
effectively.
In the longer term, HFCs offer the potential of replacing HCFCs as the major blowing agents
for the industry but clearly the issue of global warming needs to be dealt with intelligently to
avoid losing the opportunity of improving energy efficiency and reducing carbon dioxide
emissions by this route.
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Chapter Five
EXTRUDED POLYSTYRENE
EXTRUDED POLYSTYRENE SHEET
Products and Applications
t
Extruded polystyrene foam sheet is a thermoformable material used primarily to manufacture
food service and food packaging products, such as hinged carry-out containers, single-service
plates, cups, egg cartons and food trays. Other applications include dunnage, laminated
sheets, and wrap-around labels.
Food Service and Packaging
Food service applications for extruded polystyrene foam sheet include the manufacture of
cups, plates, bowls, and hinged-lid containers, while food packaging applications include the
production of meat trays, egg cartons, and produce trays. In 1986, food service and
packaging applications consumed about 83 % of the CFCs used for rigid polystyrene foam
packaging.
CFCs were attractive blowing agents for some foam food service products because they
contributed to the products' ability to insulate food and beverages at the proper temperature
and to provide appropriate moisture resistance. In food packaging, CFCs also contributed to
the products* moisture resistance; therefore, the end products eliminate the need for frequent
in-store rewrapping.
Dunnage
Dunnage is loose fill packaging materials such as foam "peanuts," pellets, and chips. This
foam is used to protect products during transit and, thus, reduce the amount of breakage.
Foam dunnage is reusable, sanitary, lightweight, and moisture resistant.
Laminated Foam Sheets
Laminated foam sheets are used as art board and in insulated packages. Providing aesthetic
versatility when used art board, laminated foam sheet is rigid yet lightweight, and readily
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accepts printing inks. In insulated packaging applications, laminated foam sheets are
lightweight, rigid and moisture resistant, in addition to providing thermal insulation.
rocess
Extruded polystyrene foam sheet is produced by a process that mixes polystyrene resin with
additives and melts the mixture to a low viscosity in a two-stage screw extruder. During the
process, blowing agents are injected into the extruder under high pressure and dispersed into
the polymer melt.
Then, this mixture is cooled and forced through a die under controlled pressure. As the
molten polymer exists the die, the dissolved blowing agent vaporises and expands. This
reaction causes the plastic to foam. An annular die is used to form a tube, which is
subsequently slit to make foam sheets.
Final production stages involve cooling, shaping, cutting or winding the foam into the
desired form. Extruded foam sheet is normally aged two to four days prior to
thermoforming into the desired form. Approximately 80% of the extruded polystyrene foam
sheet produced consists of foam sheet that is thermoformed into a variety of products.
The thermoforming step typically generates a substantial amount of foam scrap. In some
cases, 30% to 40% of the extruder feed becomes scrap. Manufacturing processes commonly
include grinding and repelletising steps after final cutting and thermoforming.
The pelletised foam scrap recovered from thermoforming is recycled back to the extruder
feed. The typical extruder feed mixture is 65 % virgin polystyrene and 35 % recycled
polystyrene.
Global Consumption of CFCs in Extruded Polystyrene Sheet
In Western Europe, North America, Japan and Australia the food service products and
meat/poultry trays are no longer produced with CFGs or HCFCs except for one or two
isolated manufacturers.
Most of the packaging manufacturers have converted their production to hydrocarbon
blowing agents, particularly pentane and butane combinations with smaller amounts of
HCFC-22, HFC-152a and CO2.
Alternative blowing agents to CFCs such as HCFC-141b, HFC-134a and HFC-152a have
been evaluated and sometimes even used in production. Although these products offer
advantages in environmental performance, disadvantages such as reduced processability, lack
of generally accepted approvals for food contact and price made most of the industry decide
to go to hydrocarbons,
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The converters of laminated foam sheet have also changed over to hydrocarbons.
Without exception it is fair to say that hydrocarbons are the standard of the industry today
and that halogenated products as blowing agents for the production of polystyrene foam sheet
have been phased out, at least in the developed world.
In 1993 it is estimated that the global consumption of CFC's in the extruded polystyrene
sheet industry was of the order of 12,200 tonnes. Of this some 87% was estimated to have
taken place in countries operating under Article 5.1. The 1991 UNEP Foams Technical
Options Report mistakenly stated that the CFC phase-out was taking place globally. The
1994 report, however, has uncovered a significant use of CFCs in this application in
developing countries. Taking the 1986 base of around 20,000 tonnes the 1993 figure
nevertheless represents a reduction of around 40 %.
The alternative technologies of hydrocarbon and CO2 are readily available and transferable.
Several developing countries have indicated that they plan conversion out of CFC's in 1995.
There are proven technologies available to replace CFCs and, provided capital can be
secured, could occur much faster than the 10 year grace period allowed under the Protocol.
Estimates for global consumption of HCFC's are just over 280 ODP-tonnes for 1993, the
bulk of which took place in North America.
Technical Options for Blowing Agents in Extruded Polystyrene Foam Sheet
To be an effective blowing agent for extruded polystyrene sheet used for packaging,
substances must satisfy certain technical criteria:
* solubility - there must be adequate solubility in the molten resin and low
solubility in the extruded foam products;
* safety - substitutes must be low in toxicity and their flammability
characteristics must also be considered;
stability - high thermal and chemical stability is required in the manufacturing
process;
diffusivity - low diffusivity is necessary for post-expansion; and
environmental acceptability
The solubility of the blowing agent in the molten polymer is a critical property. If the
blowing agent separates from the polymer matrix, gas pockets will form.
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Stringent requirements for food packaging also pose challenges as manufacturers seek new
blowing agents. In many countries, the use of any substance used to manufacture a product
for food applications requires regulatory clearance.
Current Options
Hydrocarbons
Hydrocarbons are the blowing agent used today sometimes in combination with CO2
for cost reduction reasons.
Hydrocarbons are also an immediately available option. N-pentane, butane,
isopentane and isobutane are readily available petroleum products. Several
manufacturers are already using hydrocarbons alone or in combination with carbon
dioxide or HCFC-22.
On a cost per unit weight basis, pentane and butane are the cheapest available blowing
agents for foam sheet food service and packaging applications. They offer excellent
solubility properties, better plasticising properties, and the required diffusivity.
Polystyrene foam packaging products made with hydrocarbons offer a similar high
quality as those made with CFCs. Many companies in Europe and the Far East
currently use hydrocarbons or are converting from CFCs to hydrocarbons. The
primary concerns associated with the use of hydrocarbons are VOC emissions and
flammability.
Regarding emissions, hydrocarbons are photochemically reactive volatile organic
compounds (VOCs) that contribute to ground level ozone pollution. Emissions may
be reduced through the use of recovery and reuse technology, incinerators, or
catalytic converters. In addition, manufacturers using hydrocarbons must obtain
permits for their facilities and meet allowable local emission limits. In some
countries, such as the United States, obtaining permits for facilities can be difficult or
even impossible in high pollution areas and thus, the hydrocarbon solution can be of
real concern.
Consequently, in areas where hydrocarbon emissions are restricted, additional
investments could be as high as US$1 million to install equipment to comply with air
pollution regulations and worker safety. Either destruction of the blowing agents via
incineration or recovery of the blowing agents via carbon adsorption is required.
Modifications required to ensure worker safety include anti-static guards, spark
arresters, and ventilation equipment to diffuse heavy hydrocarbon vapours, as well as
employee retraining. Actual conversion costs will vary depending upon plant size,
plant locations and emission control requirements.
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Operating costs for using hydrocarbons, however, are lower than those for CFCs. In
fact, it is estimated that manufacturers can expect a payback around 18 months on the
capital investment necessary to meet flammability and emissions criteria,
HCFC-22
In many cases HCFC-22 has been used for a short while, since it offered an improved
environmental performance versus CFC-12 and CFC-11 and allowed rapid conversion
without major plant modifications, HCFC-22 has been used as an interim solution in
the search for alternative blowing agents until more suitable options are developed and
implemented,
HFC-134a and HFC-152a
Both products have had attention as possible replacements for CFC-12 in polystyrene
foam sheet applications.
HFC-134a has been investigated as a possible replacement blowing agent. Its
inflammability and its VOC exempt status in the US are considered advantageous.
No regulatory approval for food contact, difficult processing and high cost are the
reasons for lack of commercial use.
The use of HFC-152a in this application is limited to the US. It has better processing
characteristics than HFC-134a and carbon dioxide but not as good as hydrocarbons,
Its flammability characteristics are similar to those of hydrocarbons but in the US it is
VOC exempt which has led to its use as an alternative to hydrocarbons where
recovery and incineration would have had to be installed. It is sometimes used in
combination with other zero-ODP options.
Long Term Options
The direction the foam industry will take in the long term regarding blowing agents is
towards atmospheric gases such as CO2, nitrogen and water. The time frame of
implementation is uncertain since significant hurdles in processing need to be overcome and
acceptance by market is necessary because of differences in the physical appearance of the
trays.
Today technology using 100% CO2 as a blowing agent has been implemented by a few
pioneers in the market. In the US two converters are fully commercial in food service
applications with 100% CO2. In Brazil the whole product range has converted to 100% CO2.
In Europe two manufacturers are in the process of converting their production to 100%
With 100% CO2 the processing window is narrowed compared to CFCs and hydrocarbons.
Due to the low molecular weight of CO2 only small quantities are needed. The balance of
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properties of density, aesthetics and processability differ significantly from the blowing
agents mentioned above. A cost effective solution can be defined, but is dependent on
market acceptance. Some manufacturers have difficulties in producing the full product range
with CO2 alone.
Nitrogen has been evaluated and is used commercially for thin gauge/high density labels.
Other applications are not feasible due to the limitations in thickness and density which can
be produced.
The long term developments are those which facilitate the use of atmospheric gases as
blowing agents. Hardware developments such as die and screw designs are taking place.
Also new or improved technologies are being evaluated. On the other hand polystyrene resin
or additive developments may allow the use of atmospheric gases. These kinds of
developments may take several years before break through and commercialisation is
achieved,
Conclusions
Since 1986 manufacturers of extruded polystyrene foam sheet in the packaging market have
moved away from fully halogenated CFCs, Today's market standard for blowing agents are
hydrocarbons (although alternatives such as HCFC-22, HFC-152a and COj are currently
being used but to a much lesser extent). Except for one or two converters every
manufacturer has converted to hydrocarbons in Europe often at high investment cost.
The ultimate direction for the foam industry with regards to blowing agents will be
atmospheric gases, which will require a significant effort from the whole industry. Globally
mere are now 6 manufacturers out of about one hundred using 100 % CO2 as blowing agent.
There are no technical obstacles to phasing out CFCs faster than the 10 year grace period
allowed in Article 5 countries because zero-ODP technology based on hydrocarbons and COj
is readily available and transferable from the developed world.
EXTRUDED POLYSTYRENE INSULATION BOARD
Products and Applications
Polystyrene foam boardstock was invented in Sweden in the early 1940s but was further
developed to the extrusion process in the United States. It is a rigid foam with a fine closed-
cell structure. The original blowing agent was methyl chloride, not CFCs. Extruded
polystyrene foam insulation made with CFC-12 was introduced to the market in the early
1960s.
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Globally, approximately 90 % of extruded polystyrene rigid foam boards are ysed for thermal
insulation purposes. The cellular products consist almost entirely of polymer and blowing
agent. The type of blowing agent used determines the character of the cellular structure
formed during the manufacturing process. There are two main types of foam boards
available:
* boards with a smooth skin covering the two principal heat transfer suriaces,
the main application of the self-skinned material includes insulation for roofs,
floors, and walls in dwellings, commercial and agricultural buildings. In some
northern countries, another major application is the protection of roads, airport
runways and railways against frost-heave by laying the insulation boards in the
earth below the pavement and rail permanent way;
* boards with a planed or cut cell surface that provides grip for plaster,
adhesive, and pour-in-concrete the main application for this product includes
wall insulation of concrete buildings, tile and plaster backing, core material for
sandwich panel construction, and low temperature space. There are a number
of small specialty applications in most geographical markets as well.
High moisture resistance combined with mechanical strength makes extruded polystyrene
insulation both an economical and practical material for below-ground building applications,
such as basements, foundations and earth-sheltered homes, and inverted roof applications,
where the waterproofing membrane is below the insulation material.
Other properties of extruded polystyrene foam include:
» low-thermal conductivity;
» resistance to freeze-thaw deterioration; l
« excellent compressive strength and dimensional stability (low shrinkage); and
» good handling properties, including low toxicity and low insulating gas
diffusion loss with time.
Production Process
The manufacturing of extruded polystyrene foani board for insulation purposes involves an
extrusion process similar to that described for sheet. Polystyrene resin is mixed with
additives, then continuously fed into an extruder where it is melted. Blowing agent,
continuously injected under high pressure, is dispersed in the resin to form a foamable gel.
The gel is then cooled and extruded through a rectangular cross section die where the
blowing agent volatises, causing the plastic to assume a foam structure.
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After the foam has been formed, it is transported away by a continuous conveyer belt and cut
into appropriate lengths and widths. This cutting section can also include equipment to
remove the skin (i.e., make planed boards). Internally generated scrap is recycled within the
plant. In order to be recycled the scrap has to be reground with consequential release of cell
gases.
In closed-cell insulation foams, such as extruded polystyrene, the blowing agent performs
two functions:
« It makes the gel foam, and
* it contributes insulation value to the foam.
The blowing agent which stays in the foam to provide insulation value, the primary blowing
agent, is sometimes called the insulating gas. A second, or auxiliary, blowing agent is
sometimes used to support the foaming process; another proprietary technology uses vacuum
foaming. In all processes the primary blowing agent must be present to provide
characteristic high level insulation performance.
Extruded polystyrene foam insulation board production units operate in North America,
Japan, South Korea, Egypt, Israel, Saudi Arabia, Kuwait and all countries in western Europe
except Luxembourg, Ireland, Portugal, Denmark and Switzerland. In eastern Europe at least
one plant is operating in Hungary.
It is believed that no production currently exists in other countries of Eastern Europe,
Australasia, the former Soviet Union, Central and South America and Central and South
Asia,
Global Consumption of CFCs and HCFCs in Extruded Polystyrene Insulation
Board
Approximately 17,600 tonnes of CFC-12 were used worldwide in 1986 in the manufacture of
extruded polystyrene foam insulation board. At that time, extruded polystyrene insulation
boards consumed approximately 7% of all CFCs used in foam applications. In spite of
market size increases ranging from 30% to over 80% in the three main producing areas of
North America, Japan and Western Europe, CFC-12 consumption had decreased to 12,000
tonnes by 1990.
This trend has accelerated such that by the beginning of 1994 in these three main producing
areas the phase out of CFC's was complete; 1993 was thus a year of major conversion effort
with 1993 consumption of CFC's was 2,215 ODP-tonnes.
CFC-12 consumption by the world!s extruded polystyrene insulation industry has decreased
.by 87% from 1986 to 1993. Taking the 12,000 tonnes in 1990 as a base the 1993 represents
a further reduction of 81 % in only 3 years.
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This consumption data is a combination of accurate input received on a confidential basis
from all producers in North America, Japan and all but two of the producers in the European
Union, and industry estimates for other producers.
The 1993 consumption of HCFCs was 1,804 OOP-weighted tonnes. This is approximately
30,100 tonnes of HCFCs.
Thus, consumption of weighted ozone depleting substances by the world's extruded
polystyrene insulation industry has decreased by 77% from 1986 to 1993.
Technical Options to Reduce Ozone Depleting Compounds in Extruded
Polystyrene Insulation Board
Current Options
Blowing Agent Requirements
A blowing agent is usually a volatile, chemically stable compound, and by its introduction
into the molten polymer, it reduces the density of the product by the formation of a myriad
of closed cells within its structure.
Until the late 1980s, CFC-12 was the traditionally preferred blowing agent for extruded
polystyrene insulation boards because of its attractive properties:
low toxicity
non-flammability
good solubility in polystyrene
compatible boiling point (- 30 °C) and vapour pressure for extrusion
process
very low diffusivity through polystyrene
low thermal conductivity
chemical inertness; and
thermal stability at process conditions.
At the time of writing of the first UNEP Foams Technical Options report (June 1989), the
worldwide extruded polystyrene boardstock industry established that by the end of 1993
CFC-12 use could, from a purely technical viewpoint, cease completely.
There were two substitute materials identified to successfully replace CFC-12, given
sufficient time for thorough product research and development efforts for various applications
and manufacturing processes. These replacement candidates were HCFC-142b and HCFC-
22.
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HCFC-22 and HCFC-142b
The availability of HCFC-22 did not present any problems, but that of HCFC-142b,
the key insulating gas and blowing agent, did. HCFC-22, however, has a relatively
high permeation rate out of polystyrene and does not provide the long-term insulation
value required and is therefore considered a secondary blowing agent. HCFC-142b is
clearly the preferred primary blowing agent.
Conversion to HCFC-142b, either alone or in combination with other auxiliary
blowing agents including HCFC-22, meant not only considerable investment in
manufacturing ancillary equipment, product reformulation, and performance
evaluation, but also in cost.
Blowing agents are a significant part of the total cost of the product. There is
however no premium price to be obtained for more environmentally benign products
in the market.
Approximately 75% to 85% of the HCFC-142b used in the manufacture of extruded
polystyrene insulation is retained in the foam after production. The remaining blowing
agent is primarily tost via foam forming and shaping processes during production,
HCFC-142b is the blowing agent/insulating gas providing the product with its low
overall thermal conductivity.
As the insulating gas, it performs two main functions;
« it promotes the physical processes necessary to make the foam; and
» it provides thermal properties that improve the insulation performance
(especially long-term) in the boards.
The blowing agent function is often supplemented by auxiliary blowing agents such as CO2,
methyl chloride (Japan), ethyl chloride (Japan, Canada, USA) and hydrocarbons (butane and
pentane). These compounds do not provide long term insulation value and are used solely as
blowing agents to achieve low product densities.
The foam insulation manufacturer must make critical blowing agent and process modification
choices to provide the best products for particular market applications. Different producers
in the same or different markets may malce different choices. In fact, not all alternatives
may be usable in each process of a particular manufacturer.
Long Term Options
Insulating gases (i,e. retained in foam, contributing to thermal insulation performance)
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The 1991 Report identifies HCFC-124 as a potential substitute for CFC-12. Due to
its limited commercial availability and ozone depletion it is no longer being evaluated
for use in the extruded polystyrene insulation market,
HFC-134a
The PAFT testing programme has been satisfactorily completed. Ample amounts are
now commercially available but the price is still unattractively high for significant
quantities to be consumed in this industry where blowing agents represent an
important share of production costs.
HFC-134a offers the following properties:
« ' thermal conductivity that is approximately 35% higher than H&FC-
142b;
a boiling point of-26" C;
* low permeability through polystyrene; it is believed to be similar to
HCFC-142b;
* non-flammability; and
« a zero ozone depletion potential.
Another major drawback already identified is the poor solubility of HFC-134a in
organic materials including polystyrene polymer. This causes severe processing
difficulties and it is also questionable whether the insulation value achieved previously
could be matched using HFC-134a alone.
Combined with its price, the above two factors virtually rule out any widespread use
of HFC-134a in extruded polystyrene foam at this time,
Non-iasulatin% gases (rapid diffusion out of foam, not contributing to thermal insulation)
HFC-152a
HFC-152a is an existing compound whose lexicological properties are known.
Supplementary studies are not excluded, however, ,
One production unit operates on a commercial scale in the United States. Investment
plans for a semi-industrial scale plant in France have also been announced.
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HFC-152a has the following "properties:
since it has a high permeability through polystyrene, similar to HCFC-
22, the 30% higher thermal conductivity titan that of HCFC-142b really
does not apply;
a boiling point of -25' C;
» a flammability range in air that is 3.7% to 18% whilst the minimum
ignition energy has been reported to be almost identical to that of
hydrocarbons. (The value for HCFC-142b is two orders of magnitude
higher); and
* a zero ozone depletion potential,
Bearing in mind the above properties and notwithstanding the fact that HFC-152a has
been used in extruded polystyrene (XPS) sheet manufacture it does not seem likely
that it will be used as a sole blowing agent for XPS boardstock. However, in
combination with other substances, its use cannot be ruled out.
Hydrocarbons, primarily butanes and pentanes, can be used to foam polystyrene.
They have been used for many years in the manufacture of extruded sheet polystyrene
foam packaging products in Europe, North America and Japan. Hydrocarbons are
readily available and are relatively inexpensive compared with other blowing agent
alternatives,
Extruded polystyrene boards can be satisfactorily produced with hydrocarbons alone,
However hydrocarbons exhibit the following sometimes disqualifying disadvantages:
* hydrocarbons are flammable their safe handling and processing
require that appropriate safety measures and significant capital
investment be taken in the manufacturing plants, as well as in the
distribution chain;
hydrocarbon use can be subject to local air pollution regulations -- these
regulations limit the emissions of volatile organic compounds, which
contribute to tropospheric ozone (smog) formation;
» any appreciable amount of hydrocarbon retained in the foam seriously
affects the performance of the product when subjected to even small-
scale fire tests which, in many countries, are mandatory for
construction materials; and
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consequently the practical level of hydrocarbon blowing agent
is comparatively low.
Alcohols
Ethanol, lite the hydrocarbons mentioned above can be used to make XPS boards. It
is readily available, inexpensive and has zero ODP but shares many of the
disadvantages of hydrocarbons:
it is flammable;
it is a volatile organic compound; and
* it has a high solubility in the polymer. Experience shows that ethanol
cannot be used alone if foam collapse is to be avoided.
Ethanol diffuses rapidly out of the foam and therefore does not contribute to the
insulation properties of the product. In at least one company in Europe ethanol is an
established auxiliary blowing agent.
Atmospheric Gases
Where insulation performance is less critical but still important and where market
forces are demanding it 100 % CO2 technology has been introduced in Germany and
northern Europe on a limited basis for extruded polystyrene board insulation products.
Zero ODP products not using 100% CO2 but CO2 in combination with one or more of
the above mentioned options are also commercially available on a limited basis in the
same geographic area.
Recovery/Recycle/Destruction
At present, there are no recovery processes known to be in use in extruded polystyrene
boardstock facilities. There are several reasons why this option has not been considered
technically and economically feasible in the past.
An estimated 75% to 85% of the HCFC/CFC-blowing agents are trapped within the cells of
the finished product. Thus, only 15 % to 25 % of the blowing agents consumed are available
for capture.
Currently, it appears that carbon adsorption and molecular sieves offer the best possible
capture technology. Several technical problems will need to be overcome first to successfully
recover HCFCs . These problems include:
Collection blowing agent emissions occur at several points in the process. A
large portion of the plant air must be collected in order to capture most of the
HCFCs;
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« Capture plant air streams are quite dilute, making efficient adsorption on
carbon more difficult. The use of auxiliary blowing agents can interfere with
the efficient capture of the HCFCs , Contaminants in the plant air stream can
interfere with the adsorption capacity and lifetime of the carbon bed and
molecular sieve; and
» Recovery/ Destruction HCFCs used in the manufecture of extruded
polystyrene foam boardstock have low boiling points and thus complicate the
separation from water (ice formation) and other contaminants in the air stream.
Proven technology for destruction of CFC's/HCFC's in foams is incineration.
Suitably equipped municipal solid waste incinerators are UNEP approved
destruction technology for QDS in foams.
Product Substitutes
Foam insulation provides high energy efficiency combined with other physical properties.
These include excellent fire-test performance, waterproof characteristics, low density, thin
profile, and ease of handling. Other insulating products, such as expandable polystyrene
bead board, cellular glass board, perlite board, fibreboard and gypsum board, can provide
some of these properties, but not all. Consequently, these substitute products may not be
considered alternatives for all applications of extruded polystyrene insulation foam,
When a substitution is made, the alternative material will often have a higher thermal
conductivity per, unit thickness, and hence will not insulate as efficiently as the foarn
insulation of equal thickness blown with HCFC-142b . It is necessary to increase the
thickness of the alternatives to compensate for lower insulating values. Here either the
economic impact or the capacity to comply with demands on physical dimensions required by
the application in question may be decisive factors. If a less efficient insulation configuration
is selected, energy consumption increases with subsequent increases in fossil fuel
consumption. CO2 emissions will rise with a recognisable impact on global warming,
The main difficulties in using alternative insulating products are in applications where the
waterproof characteristic of foam insulants is a major advantage. In these uses, which are
typically applications of extruded polystyrene insulation foam, there is no obvious alternative
without considerable changes in design and construction practice (Curwell and March,
Hazardous Building Materials 1986).
Phaseout Schedule
Based on the available alternative blowing agents, the extruded polystyrene foam board
industry has, in the developed world, completed, as expected, the phase out of CFC's by end
of 1993. '
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Conclusions
HCFC-1425 (alone or in combination with HCFC-22) represents the most practical option to
CFC-12 in extruded polystyrene board insulation,
Although unproven, recapture and recovery technology is being actively investigated to solve
several technical problems. About 15% to 25% of the initial HCFC charge is released
during manufacturing process.
Government support and encouragement are essential in non-Party and developing countries
to ensure a timely exit from CFC's.
Conversion to HCFCs will maintain the long-term insulation performance of extruded
polystyrene boardstock, but some other product properties may be negatively affected. Using
HCFCs achieves at least a 90% reduction in ozone depletion potential and at least an 85%
reduction in greenhouse potential from this industry segment.
Successful conversion to other alternatives requires considerable technology, which means
that smaller manufacturers will have greater resource difficulties.
It is recognised that there will be an ultimate need to use zero ODP insulating gases in
applications where high thermal performance is required.
Some substitution to non-insulating gases is occurring where either superior thermal
performance is not the most critical factor or market forces demand this type of product or
both.
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Chapter Six
POLYOLEFIN FOAMS
Products and Applications
The general category of polyolefin foams includes products made from either polyethylene or
polypropylene resins. These general foam types sometimes include other olefinic
constituents, such as ethylene/vinyl acetate or ethylene/acrylic acid copolymer resins, as
modifiers. Several different manufacturing processes are used for polyolefin foams, which
result in different product forms.
One type of processing, which involves the crosslinMng of extruded resin sheet and its
subsequent expansion, uses only decomposable blowing agents, such as azodicarbonamide,
and, as such, this process will not be considered further here. These products have different
properties and are typically more expensive than polyolefin foams manufactured with CFCs,
They are not generally considered to be substitutes for most non-crosslinked polyolefin foam
applications.
Polyethylene and, more recently, polypropylene resins are used in expandable bead products,
which may be subsequently shape-moulded. These foam products are used primarily as
moulded cushion packaging and automotive bumper systems. CFC-11 and CFC-12 were
previously used as blowing agents. All bead producers now use hydrocarbons or carbon
dioxide. Consequently, no further comments will be made regarding these products.
Both polyethylene and polypropylene resins are extruded into sheet products. These sheet
products are commonly used as protective packaging for furniture, electronic devices, and
other goods. Other applications include flotation devices (such as life vests), construction
materials, and gaskets. CFC-11, CFC-12, and CFC-114 have historically been used for most
of these sheet products.
Polyethylene resins are used in the manufacture of extruded plank products. Their most
frequent application is designed cushion packaging of electronic or other high-value goods.
Some plank products are also used in military packaging., flotation, construction, aircraft
seating and other applications. CFC-12 and CFC-114 were generally used in the
manufacture of plank products.
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Polyolefin foam is also extruded in an annular shape (tubing) for use as thermal imulation
Applications include residential hot and cold water pipe insulation and similar near-
ambient and cold temperature applications. Historically CFC-12 or CFC-1 14 were used as
blowing agents.
In most polyolefin foam applications, products are used because of specific properties. The
most important of these properties is the material's ability to provide insulation from
mechanical, vibrational, thermal and/or other en% ironmental stresses.
A good example is the packaging of military hardware. Items, such as missiles deployed on
land, sea or air are shipped from the manufacturer, through the distribution system, to the
ultimate field unit. The package is specifically designed to insulate the device, containing
both explosives and sophisticated computer and guidance hardware, from a broad range of
possible conditions. These include the mechanical and vibrational stresses due to rough
handling and transportation under rugged conditions, moisture and humidity, sand and dirt in
temperatures varying from arctic to equatorial extremes. The package can be made entirely
of polyolefin foam with only straps to secure it or may consist of foam inserts inside a
container. Similar considerations apply to civilian consumer applications, although often
under less severe conditions.
An additional benefit of these resilient materials is their reusability. In many applications,
the packaging materials may be returned to the manufacturer to package new goods without
degradation of performance. This multiple reuse is a good example of the proper use of
plastic materials to conserve raw materials. In addition, fabrication trim scrap is often
returned to the foam producer for reuse in the process.
Production Processes
In the case of extruded products, the resin is melted and mixed with the blowing agent(s).
The resin and blowing agent are then passed through a die, where the product rapidly
expands and cools. For sheet products, a circular, annular die is used to form a thin-walled
hollow cylinder of foam. This foam tube is subsequently slit to produce a flat sheet that can
then be rolled for storage or shipment. Sheet products are normally no thicker than 13 mm,
and most are no thicker than 6 mm.
Pipe insulation also uses an annular die but one producing a reasonably small diameter,
relatively thick-walled foam product. The inside diameter of the tubing ranges from 6 mm to
125 mm with wall thicknesses of 5 to 50 mm.
Typically, plank products are made using a specific die, which produces the particular cross-
section desired. Each cross-section requires a different die. The plank is then cut to length
and, if necessary, the edges are trimmed. Plank products can be from 12 to over 100 mm
thick, and are made up to 1200 mm wide. They are occasionally made in circular or other
non-rectangular cross-sections. One process injects the foaming materials into a closed
cavity to help dimension the product.
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All three foam types are closed cell products. Thus, most of their blowing agents are
initially trapped within the foam. With very thin sheet products, a significant portion of the
blowing agent may be lost at or near the die. For extruded plank, tubing and thicker sheet
products, very little is lost at the die although some will be lost in trimming operations,
which open the cells.
Global Consumption of CFCs in Polyolefin Foams
For 1993 the total consumption of CFCs by this industry segment has been estimated to be
910 tonnes. This is a decrease of 93% from that previously reported for 1990 and 95% from
1986. It is possible that additional CFC usage may have occurred in 1993 since gathering
consumption statistics in developing countries is extremely difficult.
Rapid progress continues to be made in eliminating the use of CFCs in all product types.
Many extruded products have been converted to HCFC-22, HCFC-142b, HFC-152a,
hydrocarbons and/or carbon dioxide. All manufacturers of mouldable bead products have
converted to hydrocarbons and/or carbon dioxide combined with pre-expansion. By the end
of 1994, virtually all remaining CFC use in polyolefin foams, estimated at 600 OOP tonnes
per annum, will be in developing countries.
Global Consumption ofHCFCs and Projected Growth
An estimated 250 OOP tonnes of HCFCs were used in 1993 in this industry segment. Many
manufacturers, who had previously switched to HCFCs, have now converted to zero ODP
substances. Most commonly, these are hydrocarbons or hydrocarbon/HFC-152a blends. The
Clean Air Act Amendments of 1990 in the USA bans the use of all ODSs in all foams except
those used for thermal insulation or automotive safety cushioning. This eliminated all use of
HCFCs in polyolefin foams, except for pipe insulation, beginning January 1, 1994. Many
European countries, including the European Union, are restricting use of HCFCs in similar
products. Most developing country producers will be switching directly from CFCs to zero
ODP options with the assistance of multilateral funding support. An estimated 180 ODP
tonnes per annum of HCFCs will be in use by this industry segment at the end of 1994.
Technical Options to Reduce Owm Depleting Compounds in Polyolefin
Foams
One of the primary criteria in blowing agent selection is the ability to match the diffusion
rate of blowing agents out of the foam with the diffusion rate of air into it. This match is
necessary because the polyolefin resins are resilient. If the diffusion rates are not sufficiently
matched, the foam will either shrink or grow while aging. This is unacceptable in all three
product types. Permeability modifiers can sometimes be used to help match these diffusion
rates where they are reasonably close but not acceptably so.
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Current Options
The threat of early elimination of HCFCs was the cause of great concern for some industry
segments where no clear alternative existed. Indeed, it actually retarded the conversion from
CFCs to HCFCs, producing an overall negative environmental impact, since the potential
cost and the strain on resources of two rapid conversions is a heavy burden on many
manufacturers in highly competitive markets.
Reduced OOP
HCFC-22
HCFC-22 has a very low boiling point and, consequently, a high vapour pressure.
This characteristic limits its use to the manufacture of some thin sheet products.
Thicker sheet and plank products are extremely difficult to make with HCFC-22.
HCFC-142b
HCFC~142b has been the preferred alternative for thicker sheet, pipe insulation and
plank products. It has a minimal flammability which does not affect the fire safety of
the material produced with this blowing agent. The permeation rate through
polyethylene is close enough to air to provide a dimensionally stable foam through use
of permeability modifying additives.
/
Sometimes "HCFC-142b is used with HCFC-22 to make a non-flammable blowing
agent mixture, which is often used to manufacture pipe insulation products.
Zero OOP
Hydrocarbons are flammable. For example, isobutane flammability limits are about
1.8 to 8.4 volume percent in air with an extremely low energy of ignition. This
situation requires the careful consideration of equipment and procedures in
manufacturing, storage, handling, and shipping as well as local regulations and the
possible effects on customers. Some mouldable bead product suppliers use
hydrocarbons in a closed pre-expansion process which captures essentially all of the
gas.
In addition, in the United States, such hydrocarbons are classified as volatile organic
compounds (VOCst considered to be precursors to ground level ozone or "smog")
and, therefore, are subject to regulations limiting plant emissions. Some European
countries are considering similar regulations. Because the hydrocarbons would be
released in very dilute concentrations from storage areas, collection of these gases
could be inefficient and prohibitively costly (see Recovery/Recycle section below).
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In some instances, significant plant modifications are required to handle these blowing
agents. In others, the manufacturer may be unable to use flammable blowing agents
for safety and handling reasons or because of local air pollution or flammability
regulations.
Some manufacturers have converted, or expecl to convert, from CFCs to
hydrocarbons.
HFC-152a
By itself, HFC-152a is difficult to use in making large cross-section polyolefin foams.
Consequently, it is used primarily in combination with hydrocarbons. Whilst the
lower flammability limit of HFC-152a is higher than isobutane (3.7% vs. 1.8%), it
has a similar low energy of ignition and must be handled much like the hydrocarbons.
It is not considered to be a VOC in the US and can thus be used to meet plant
emission requirements.
HFC-134a
HFC-134a is even more difficult to use than HFC-152a. However, its zero ODP
value and lack of flammability has led to some use, primarily in Japan where it is
used in conjunction with other blowing agents such as isobutane or ethyl chloride.
The present cost of HFC-134a is prohibitive for many producers.
Long Term Options
Since all polyolefin foams, with the exception of pipe insulation (because of fire safety
reasons when installed in buildings), can convert to one of the current zero ODP options, the
long term options will be preferred primarily for characteristics other than zero ODP.
Flammability or environmental concerns with some of the current options may lead to a later
conversion to one of the materials below.
Carbon Dioxide and Other Inorganic Gases
Carbon dioxide (CO2), nitrogen and other inorganic gases have very low solubility in
the resins and may be of only limited use in extruded foams of these types. In
addition, process pressures will be very high, perhaps beyond the capability of some
processes without significant or prohibitive capital expenditure. These volatile gases
are, however, being used in some mouldable bead products where the process
pressure problem can been overcome. Carbon dioxide diffuses rapidly out of
polyolefin foams and could cause massive dimensional stability problems without
some, as yet unidentified, enabling technology.
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In making any conversion, a manufacturer must weigh the costs and benefits of the
conversion. Necessary capital expenditures, raw material cost and availability,
environmental considerations, conversion efficiency, achievable range of foam
products and foam properties must all be considered. Few generalisations can be
made except that any of the above can greatly affect the ability to succeed in these
highly competitive markets. Likewise, PO one solution will be applicable to all
producers since various specific factors listed above may affect the viability of a
particular option for that manufacturer,
jiecovery/Recycle/Destructum
Recovery feasibility is primarily a function of product thickness and type. Some mouldable
bead product suppliers use hydrocarbons in a closed pre-expansion process which captures
essentially all of the gas. In extruded foams the permeation rate of blowing agents out of the
foam is inversely proportional to the square of the product thickness. In very thin products,
a major portion of the blowing agent is expelled at or near the die and can be captured fairly
easily. One producer of very thin polypropylene foam sheet products is currently capturing
and recovering blowing agents at better than 95 percent efficiency.
For thicker sheet, tubing, and all plank products, collection of the blowing agents to any
significant extent is often difficult and, consequently, very expensive. In these cases, the
blowing agent captured within the cell walls of the foam leaks slowly over a period of days,
weeks, or months and is lost during warehousing, shipment, and even use of the foam. This
implies that a large volume of air with very dilute gas concentrations must be collected and
only a portion of the blowing agent will be recovered prior to shipment.
When air streams containing organic vapours are captured, the contaminant can be removed
by carbon adsorption. The efficiency of such operations depends on the concentration of
vapours in the air (higher concentrations generally mean greater efficiency). Except in the
case of very thin foams, which lose a large quantity of blowing agent near the die, these air
streams are quite dilute. This characteristic dramatically increases the cost and difficulty of
efficiently recovering organic blowing agents. In addition, foam plant ambient air has a
significant level of moisture. This complication hinders the recovery of blowing agents with
low boiling points (ice formation).
In the case of hydrocarbons, the gas in the air stream can be removed by incineration.
However, because the gas concentration is very dilute, additional fuel must be added to
sustain combustion. This is not only an added operational expense but of questionable
environmental value.
Where a manufacturer has a need for steam, the air stream can be used as the air supply for
the boiler. However, large quantities of air must be processed to remove the hydrocarbons
and may be in excess of the demand for steam, and thus an added cost to the business.
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Product Substitution
In many applications of polyolefin foams, products are used because of their specific
properties. Whilst materials such as paper, cardboard, and expanded polystyrene can be used
in some packaging applications, they are not effective substitutes in most applications of
polyolefin foams. However, because most polyolefin foam segments have already, or are
nearly, converted into zero ODP alternatives, there is little need for product substitution to
eliminate stratospheric ozone depletion concerns. All moyldabie bead producers have
eliminated use of ozone depleting substances.
Conclusions
For calendar 1993, approximately 95% of CFC usage had been eliminated in polyolefin
foams compared to the 1986 base (910 tonnes vs 19000 tonnes). Some use of HCFCs also
existed and is estimated at 250 ODP tonnes. By the end of 1994 it is estimated that 96%
conversion had occurred for a further reduction to an annualised rate of 780 ODP tonnes
(CFCs: 600; HCFCs: 180). At that time, all remaining CFC usage is expected to be in
developing countries. Several MLF projects are in development to address this use. In
general, this industry segment is rapidly moving out of all ODSs.
Some options might be useful in foam sheet products alone. This is because the loss of
blowing agents is strongly related to product thickness and so aging time for very thin
products might be acceptably short.
A number of different processes are employed in the manufacture of polyolefin products, and
the resultant foams are used in a variety of applications, primarily in protective cushion and
military packaging, flotation, pipe insulation, and construction. The most important property
of these foams is their energy absorbing characteristics which allow insulation of items from
mechanical, vibrational, thermal and/or environmental stresses. Many polyolefin foams are
used for their specific performance characteristics, thus limiting the economic viability of
substitution of other products. The rapid movement of this industry segment out of ODSs
minimises the need for product substitution.
Due to the performance demands of the applications, the resulting foam properties of these
substitutes do not differ greatly from those of the current products. It is necessary for the
manufacturer to adjust his formulation and processing conditions, however. This affects
costs and increases the difficulty of making a conversion. Possible interferences with
additives used for anti-static, flame retardant, coloring or other purposes may be an
additional barrier to use of some alternatives in specific products. For all of the above
reasons, a manufacturer must select the best option for his business. No one solution is
expected to be optimum for all producers in an industry segment.
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Because these foam products are made in a variety of shapes and for different applications, it
may take an extended period of time for a manufacturer to make a complete conversion of an
entire product line. Most of these foams are performance products which must maintain
specific properties to be useful in each application. This will require extensive product
development and testing by both the manufacturer and customer prior to plant conversion.
The uncertainty about the long term viabiUtj of HCFCs in this application slowed the
conversion out of CFCs, particularly in developing countries. Similar concerns with some of
the currently available options could have a similar effect in the future.
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Appendix A
UNEP FOAMS TECHNICAL OPTIONS COMMITTEE
Committee Member
Affiliation
Country
Mr. Godfrey Abbott
Mr. Paul Ashford
Ms. Lorraine Aulisio
Ms. Marion Axmith
Mr. Craig Barkhouse
Dr. Gert Baumann
Dr. Ted Biermann
Mr. Michael J. Cartmell
Mr. John Clinton
Mr. Hubert Creyf
Mr. Shi Jia Fan
Dr. Alan Fine
Mr. Ryoichi Fujimoto
Mr. Reg Hurd
Dr. Mike Jeffs
Dr. Robert Johnson
Ms. Fran W. Lichtenberg
Mr. Yehia Lotfi
Ms. Jean Lupinacci
Mr. John Minsker
Ms. Sally Rand
Mr. M. Sarangapani
Mr. Muneharu Sanoh
Dr. Ian R. Shank!and
Mr. Sodario Souto
Mr. Bert Veenendaal
Dr. Udo Wenning
Mr. Takao Yamamoto
Dow Europe/Exiba
BP Chemicals Ltd./EPFA
Celotex Corporation/PIMA
The Society of the Plastics Industry, Inc.
Foamex Canada/CFFMA
Miles Inc.
BASF Corporation
1C! Polyurethanes
Barriers/PIMA
Rectieel/Europur
Qindao Haier Group Company
U.S. Environmental Protection Agency
Hitachi Ltd.
British Rubber Manufacturers Association
ICI Polyurethanes
Whirlpool
The Society of the Plastics Industry, Inc.
Technocom
U.S. Environmental Protection Agency
Dow Chemical
U.S. Environmental Protection Agency
Polyurethane Council of India
The Japanese Electrical Manufacturers
Association
AlliedSignal
Brastemp S.A.
RAPPA Inc.
Bosch-Seimens Hausgerate GMBH
Japan Urethane Foam Industrial Association
Switzerland
United Kingdom
United States
Canada
Canada
United States
United States
United States
United States
Belgium
China
United States
Japan
United Kingdom
Belgium
United States
United States
Egypt
United States - Chair
United States
United States
India
Japan
United States
Brasil
United States
Germany
Japan
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&EPA
United States
Environmental Protection Agency
(6205J)
Washington, DC 20460
Olficial Business
Penalty for Private Use
$300
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