United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
EPA/625/R-96/005
September 1996
Manual
Best Management
Practices for Pollution
Prevention in the
Slabstock and Molded
Flexible Polyurethane Foam
Industry
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EPA/625/R-96/005
September 1996
Manual
Best Management Practices for Pollution Prevention in the
Slabstock and Molded Flexible Polyurethane Foam Industry
US. Environmental Protection Agency
Office of Research and Development
National Risk Management Research Laboratory
Cincinnati, Ohio
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DISCLAIMER
The U.S. Environmental Protection Agency through its Office of Research and Development
funded and managed the research described here under Contract #68-3-0315 to Eastern Research Group,
Inc. It has been subjected to the Agency's peer and administrative review and has been approved for
publication as an EPA document. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
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FOREWORD
The U.S. Environmental Protection Agency is charged by Congress with protecting the Nation's
land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to
formulate and implement actions leading to a compatible balance between human activities and the ability
of natural systems to support and nurture life. To meet this mandate, EPA's research program is providing
data and technical support for solving environmental problems today and building a science knowledge
base necessary to manage our ecological resources wisely, understand how pollutants affect our health,
and prevent or reduce environmental risks in the future.
The National Risk Management Research Laboratory is the Agency's center for investigation of
technological and management approaches for reducing risks from threats to human health and the
environment. The focus of the Laboratory's research program is on methods for the prevention and control
of pollution to air, land, water and subsurface resources; protection of water quality in public water systems;
remediation of contaminated sites and ground water; and prevention and control of indoor air pollution. The
goal of this research effort is to catalyze development and implementation of innovative, cost-effective
environmental technologies; develop scientific and engineering information needed by EPA to support
regulatory and policy implementation of environmental regulations and strategies.
This publication has been produced as part of the Laboratory's strategic long-term research plan.
It is published and made available by EPA's Office of Research and Development to assist the user
community and to link researchers with their clients.
This manual, Best Management Practices for Pollution Prevention in the Slabstock and Molded
Flexible Polyurethane Foam Industry, funded through the Center for Environmental Research Information,
is a pollution prevention guidance manual for processes and waste reduction in the slabstock and molded
flexible polyurethane foam industry.
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
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ABSTRACT
The 1990 Clean Air Act Amendments require EPA to develop standards for major emission
sources of 189 hazardous air pollutants (HAPs). EPA has identified the flexible polyurethane foam industry
as a large emitter of HAPs and has slated the industry for regulation under Tile III, with standards
scheduled to be promulgated no later than November 15, 1997.
This manual presents pollution prevention options for the two major sectors of the flexible
polyurethane foam industry: slabstock and molded foam production. Designed for use by both
polyurethane foam manufacturers and regulatory personnel, it:
• Provides an overview of the flexible foam industry and chemistry of foam production,
common to both slabstock and molded industry segments.
• Details manufacturing processes and potential P2 measures for slabstock and molded
foam production.
• Details pollution prevention opportunities for operations that are common to both.
• Provides worksheets for pollution prevention measures, emission and cost calculations,
and lists additional resources.
This manual will be useful for those interested and/or involved in the industry: facility managers,
regulators and environmental managers and engineers.
This report was submitted in fulfillment of Contract #68-3-0315 by Eastern Research Group, Inc.
under the sponsorship of the U.S. Environmental Protection Agency. This report covers a period from April,
1994, to September, 1996, and work was completed as of September 30,1996.
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Contents
Page
Foreword iii
Abstract iv
Figures viii
Tables ix
Conversion Factors x
Acknowledgments xi
Chapter 1 Introduction 1
1.1 Overview of Pollution Prevention 1
1.2 Pollution Prevention and Flexible Polyurethane Foam Production 1
1.3 References 2
Chapter 2 Flexible Polyurethane Foam Industry Profile 3
2.1 Industry Description 3
2.2 Foam Grades and Applications 3
2.3 Foam Quality Measurements 4
2.4 Chemistry of Polyurethane Foam Production 4
2.4.1 Key Ingredients. 4
2.4.2 Foam-Producing Reactions. 5
2.4.3 Blowing Agents 5
2.5 Current Environmental Releases 6
2.6 References 7
Chapter 3 Pollution Prevention in Slabstock Foam Manufacture 9
3.1 Slabstock Foam Production 9
3.1.1 Typical Horizontal Foam Production Line. 9
3.1.2 Variations on the Horizontal Foam Production Line. 10
3.1.3 Foam Blowing and Use of Auxiliary Blowing Agents 12
3.1.4 Foam Curing and Storage 13
3.1.5 Foam Fabrication 13
3.1.6 Rebond Operation. 13
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Contents (continued)
Page
3.2 Methods for Reducing Auxiliary Blowing Agent Emissions 13
3.2.1 Overview of Releases. 13
3.2.2 Production of Water-Blown Foams. 13
3.2.3 Liquid CO2 Blowing Technology. 17
3.2.4 Reduced Pressure Foaming. 17
3.2.5 Alternative Blowing Technology 18
3.2.6 Add-On Emission Control Equipment for Reclaiming Auxiliary 18
Blowing Agents
3.2.7 Alternative Auxiliary Blowing Agents. 20
3.2.8 Comparison and Cost Information for Auxiliary Blowing Agent Emission
Reduction Measures 20
3.3 Methods for Reducing Toluene Diisocyanate Emissions, 20
3.3.1 Impact of Process and Formulation Changes on Toluene
Diisocyanate Emissions. 20
3.3.2 Add-On Controls for Toluene Diisocyanate Emissions 20
3.4 Reducing Releases From Foam Fabrication, Chemical Storage and Handling,
and Cleaning 20
3.5 References 21
Chapter 4 Pollution Prevention in Molded Foam Manufacture 23
4.1 Molded Foam Production 23
4.1.1 Molded Foam Process Equipment. 23
4.1.2 Molding Process Cycle. 23
4.1.3 Molding Process Variations. 24
4.1.4 Cell Opening. 25
4.1.5 Repair Operations. 25
4.2 Overview of Releases. 25
4.3 Methods for Reducing Releases From Mix-Head Flushing. 25
4.3.1 High Pressure Mix Heads. 26
4.3.2 Self-Cleaning Mix Heads 26
4.3.3 Nonhazardous Flushing Agents 26
4.3.4 Solvent Recovery 26
4.3.5 Comparison and Cost Information for Measures To Reduce Mix Head
Flushing Emissions 26
4.4 Methods for Reducing Releases of Mold Release Agent 27
4.4.1 Naphtha-Based Mold Release Agents 27
4.4.2 Reduced VOC Mold Release Agents. 27
4.4.3 Water-Based Mold Release Agents 27
vi
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Contents (continued)
Page
4.4.4 Electrostatic Spray Guns 27
4.4.5 Comparison and Cost Information for Measures To Reduce Mold Release
Agent Emissions 27
4.5 Methods for Reducing or Mitigating Releases of Auxiliary Blowing Agents 27
4.5.2 HFA-134a 28
4.5.2 Pentane 28
4.5.3 Water Blowing 28
4.6 Methods for Reducing Releases From Foam Repair, Chemical Storage and
Handling, and Cleaning Processes 28
4.7 References 28
Chapter 5 Pollution Prevention in Adhesive Usage, Chemical Storage and Handling, and
Equipment Cleaning 31
5.1 Reducing Emissions From Adhesives 31
5.1.1 Hot-Melt Adhesives 31
5.1.2 Water-Based Adhesives 31
5.1.3 Two-Component Water-Based Adhesives 32
5.1.4 Costs for Alternative Adhesives 32
5.2 Reducing Releases From Chemical Storage and Handling 32
5.3 Reducing Releases From Equipment Cleaning 32
5.3.1 Steam Cleaning 32
5.3.2 Solvent Substitution 33
5.3.3 Solvent Recovery 33
5.4 References 33
Appendix A Pollution Prevention Worksheets for Polyurethane Foam Manufacturing 35
Appendix B Further Information 41
VII
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Figures
Figure Page
2-1 Reactants typically used in the production of polyurethane foam 4
2-2 Polyurethane foam production reactions -5
3-1 Typical slabstock production line for flexible polyurethane foam 10
3-2 Maxfoam production process 11
3-3 Vertifoam foam production process 12
3-4 Methylene chloride use rates for different foam grades. 12
3-5 Foam production as a function of density grade. 14
3-6 EnviroCure foam production process. 16
4-I Typical molded foam production line -24
VIII
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Tables
Table Page
2-1 Summary of 1992 Emissions From Flexible Polyurethane Foam Production 6
3-I Summary of 1992 Emissions From Polyurethane Foam Production 14
3-2 Summary of Alternative Foam Softening Additives and Systems 15
3-3 Summary of Costs and Requirements for Measures To Reduce HAP Emissions 21
4-I Summary of 1992 Emissions From Molded Flexible Polyurethane Foam Production 25
4-2 Summary of Costs To Reduce Mix-Head Flushing Releases 27
4-3 Summary of Costs To Reduce Emissions From Mold Release Agents 28
5-I Summary of Costs of Alternative Adhesive Systems 32
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Conversion Factors
Units of measurement used throughout this document can be converted to SI units using the following
conversion factors:
To convert... to... multiply by...
cubic feet cubic meters 2.831685 x10~2
degrees Fahrenheit degrees Celsius t°c = (t°F - 32)/1.8
feet meters 0.3048
inches centimeters 2.54
pounds kilograms 0.45354237
pounds per cubic foot kilograms per cubic meter 16.0184634
pounds per cubic foot kiloPascals 6.895
square inches square inches 6.4516
tons metric tons 0.90718474
U.S. gallons liters 3.785
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A cknowledgments
This report is based on information gathered by EC/R Incorporated of Durham, North Carolina, on
emissions and potential emission control measures as part of a U.S. Environmental Protection
Agency (EPA) Emission Standards Division effort to develop background information on hazardous
air pollutant emissions. The report also draws heavily on emission control assessments prepared
by the Polyurethane Foam Association and the Center for Emission Control, as well as product
literature from several foam chemical and equipment suppliers.
Doug Williams of EPA's Office of Research and Development, Center for Environmental Research
Information, was responsible for the preparation and review of this document. William Battye, P.E.,
of EC/R served as the document's author under contract with Eastern Research Group, Inc. (ERG),
Lexington, Massachusetts. Jeff Cantin was ERG's project manager for the task. ERG also edited the
document and prepared it for publication. David Svendsgaard of the Emission Standards Division
provided review and technical guidance, and Amanda Williams and Philip Norwood of EC/R
contributed additional information.
Special thanks go to the following industry representatives who carefully reviewed the document:
• Dr. Douglas Sullivan, Hickory Springs Manufacturing
. Dr. Herman Stone, General Foam Corporation
. Mr. Robert Heller, Future Foam Corporation
. Mr. James Mclntyre, McNair & Sanford
. Mr. Lou Peters, Polyurethane Foam Association
XI
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Chapter 1
Introduction
This manual presents pollution prevention options for
the two major sectors of the flexible polyurethane foam
industry: slabstock foam production and molded foam
production. Designed for use by both polyurethane foam
manufacturers and regulatory personnel, the manual is
organized as follows:
• Chapter 2 gives an overview of the flexible foam
industry and the chemistry of foam production, which
is common to both the slabstock and molded industry
segments.
• Chapter 3 discusses manufacturing processes and
potential pollution prevention measures for slabstock
foam production.
• Chapter 4 discusses manufacturing processes and
potential pollution prevention measures for molded
foam production.
• Chapter 5 discusses pollution prevention opportuni-
ties for operations that are common to both slabstock
and molded foam plants.
• Appendix A contains worksheets for pollution preven-
tion measures and emission and cost calculations.
• Appendix B lists additional resources.
1.1 Overview of Pollution Prevention
In the Pollution Prevention Act of 1990, Congress estab-
lished a national policy that pollution should be pre-
vented or reduced at the source whenever feasible, and
pollutants that cannot be prevented should be recycled
in an environmentally safe manner, Source reduction, a
key component of pollution prevention, includes equip-
ment or technology modifications, process or procedure
modifications, reformulation or redesign of products,
substitution of raw materials, and improvements in
housekeeping, maintenance, training, or inventory
control.
In accordance with the Pollution Prevention Act, the U.S.
Environmental Protection Agency (EPA) is seeking to
integrate pollution prevention concepts throughout its
activities. Pollution prevention can be applied to nearly
all areas of environmental management, including air
pollution emissions, releases to surface water or publicly
owned wastewater treatment works, and pollutants
managed by land disposal.
1.2 Pollution Prevention and Flexible
Polyurethane Foam Production
The 1990 Clean Air Act Amendments require EPA to
develop standards for major emission sources of 189
hazardous air pollutants (HAPs). EPA has identified the
flexible polyurethane foam industry as a large emitter of
HAPs and has slated the industry for regulation under
Title III, with standards scheduled to be promulgated no
later than November 15, 1997.
The flexible polyurethane foam industry reported total
annual HAP emissions of almost 19,000 tons in a recent
survey conducted by EPA's Emission Standards Divi-
sion (1).1 This total includes about 15,000 tons of
methylene chloride, which is over 10 percent of total
nationwide emissions of this HAP (2). Much of the
methylene chloride emitted from the foam industry
arises from the use of the chemical as an auxiliary
blowing agent in the slabstock process. In addition to
HAP emissions, nonhazardous volatile organic com-
pound (VOC) emissions from the molded foam sector
may amount to an additional 10,000 tons per year (3).
Although these VOC emissions are not regulated as
HAPs under Title III, they contribute to smog problems
in urban areas and therefore may be regulated under
Title I of the Clean Air Act.
Because of difficulties in capturing and treating emis-
sions from flexible polyurethane foam production, pollu-
tion prevention strategies tend to be more cost effective
than add-on controls. Any analyses of control strategies,
however, must consider impacts on product properties
and product quality. The industry has expressed con-
cern that if the physical properties and production costs
of the foam produced with pollution prevention meas-
ures are not comparable with those of the current prod-
ucts, the industry runs a substantial risk of losing market
share (i.e., consumers might switch to substitute prod-
ucts); as a result, the industry would suffer adverse
1 Williams, A. 1994. Updated estimate of HAP emissions from slabstock
foam production. Personal communication from A. Williams, EC/R Inc.,
to Lou Peters, Polyurethane Foam Association. February 8.
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economic impacts. Therefore, the industry and its equip-
ment and chemical suppliers have been developing and
implementing chemical and equipment modifications to
reduce emissions without detrimental impacts on prod-
uct quality.
This work began when chlorofluorocarbons (CFCs)
were implicated in the destruction of the stratospheric
ozone layer. The Montreal Protocol on Substances That
Deplete the Ozone Layer, signed in 1987, phased out
the use of CFCs. Until then, trichlorofluoromethane
(CFC-11) had been the most important auxiliary blowing
agent used in the flexible polyurethane foam industry.
Although the slabstock industry had made a partial
switch to methylene chloride for economic reasons well
before the Montreal Protocol, a universal switch to
methylene chloride had not occurred because CFC-11
was easier to use. After the Montreal Protocol, the slab-
stock industry switched completely to methylene chlo-
ride and other substitutes. The slabstock industry also
recognized the need to reduce emissions of any auxil-
iary blowing agent whenever possible, which led to ex-
ploration of numerous source reduction measures
based on chemical and equipment modifications.
The trade association for the flexible polyurethane foam
industry, the Polyurethane Foam Association (PFA), has
been particularly active in publishing and making avail-
able information on source reduction measures (4, 5).
In addition, both the PFA and the Polyurethanes Division
of the Society for the Plastics Industries hold annual
conferences to discuss source reduction developments.
1.3 References
1. Norwood, L.P., A. Williams, and W. Battye. 1994. Summary of
flexible polyurethane foam information collection requests (ICRs).
Presented at a meeting of the U.S. Environmental Protection
Agency and the Polyurethane Foam Association. February 2.
2. U.S. EPA. 1993. Locating and estimating air emissions from
sources of methylene chloride. EPA/454/R-93/006. Research Tri-
angle Park, NC (February).
3. Whitfield, K. 1994. Some characterization and emissions esti-
mates for mold release agents and roofing applications. Prepared
by Southern Research Institute for the US. Environmental Protec-
tion Agency, Research Triangle Park, NC.
4. U.S. EPA/PFA. 1991. Handbook for reducing and eliminating chlo-
rofluorocarbons in flexible polyurethane foams, 21A-4002. Joint
project of the U.S. Environmental Protection Agency and the Poly-
urethane Foam Association, Washington, DC.
5. PFA. 1993. Flexible polyurethane foam (slabstock): Assessment
of manufacturing emission issues and control technology. Wayne,
NJ: Polyurethane Foam Association.
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Chapter 2
Flexible Polyurethane Foam Industry Profile
2.1 Industry Description
The term "polyurethane" applies to a general class of
polymers in which molecular chain segments are bound
together with urethane linkages (FVNH-COO-Fy.
Polyurethanes are used to produce an extremely wide
range of products, including solid plastics, adhesives,
coatings, rigid foams, and flexible foams. Flexible foams
represent by far the largest application for polyure-
thanes, accounting for over half of the total U.S. produc-
tion of polyurethanes (1). Flexible polyurethane foam is
used in furniture, bedding, automobile seats and cush-
ions, packaging materials, carpet cushions, and many
other applications (1).
The flexible polyurethane foam industry falls under
standard industrial classification (SIC) code 3086, "Plas-
tics Foam Products," which includes other manufactur-
ers of plastic foams such as polystyrene foam and rigid
polyurethanes. The flexible polyurethane foam industry
is divided into two major sectors: those producing slab-
stock foam and those producing molded foam. In addi-
tion, products produced by the slabstock sector can be
subdivided further into various "foam grades." These
grades are defined by foam density and firmness. Slab-
stock foam represents about 75 percent of the flexible
polyurethane foam industry.
The slabstock process is a continuous process that
produces a series of large "buns," named for their re-
semblance to long, rectangular loaves of bread. Buns
range in size from 50 to over 5,000 cubic feet. After they
cure, the buns are cut into shapes, some of which are
then glued to other pieces of foam or to other materials.
The cutting, shaping, and gluing steps are termed "fab-
rication" operations. Either the slabstock plant or the
foam purchaser may perform these operations. The
largest uses of slabstock foams are in furniture, carpet
cushions, and bedding (1).
In molded foam production, foam polymerization occurs
in a mold the shape of the desired product. This mini-
mizes the need for fabrication, although cutting and
gluing operations are often required. Molded foam
is used primarily in the transportation market, for car
seats and energy-absorbing trim panels (1). Other uses
include furniture, bedding, packaging materials, toys,
and novelty items.
Usually, a company produces either slabstock or molded
foams, although a few companies produce both prod-
ucts. Almost all producers of slabstock foam belong to
the Polyurethane Foam Association (PFA). This trade
group has no members that exclusively produce molded
foams. The Society of the Plastics Industries, Polyure-
thane Division (SPI), represents suppliers of raw mate-
rials to slabstock and molded foam producers.
Total slabstock foam production in 1993 was greater
than 600,000 tons. At the end of 1993, 25 companies
were engaged in slabstock foam production, operating
about 78 foam plants. Three large companies account
for over half of the total U.S. production (2). In addition,
the slabstock industry is currently undergoing a further
consolidation through corporate mergers and acquisitions.
Molded foam production is more difficult to quantify
because many small plants produce this material. The
SPI reported production of molded foam at 215,000 tons
in 1989. Estimated production in 1993 was about
175,000 tons. A recent survey of the foam industry by
the U.S. Environmental Protection Agency's (EPA's)
Emission Standards Division (ESD) identified 49 plants
producing molded foam; however, these plants ac-
counted for only about half of the molded foam produc-
tion reported by SPI in 1989. Molded foam producers
tend to be either very large, with over 1,500 employees,
or very small, with fewer than 100 employees (2). In the
EPA/ESD survey, almost half of the 49 plants surveyed
reported production rates less than 500 tons per year.
2.2 Foam Grades and Applications
Flexible polyurethane foam is produced in many grades.
Foam grades are almost always identified by density
and firmness, as well as by chemical type: polyether,
polyester, high resiliency (HR), flame retardant (FR), or
some other identifier. Flexible polyurethane foam grades
of identical density and firmness made by varying
chemical or mechanical techniques do not necessarily
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have the same strength, durability, or other quality prop-
erties. The best way to determine comparability of qual-
ity properties is through in-use testing. This is of extreme
importance as foams based on new chemistry or new
manufacturing techniques become available in the mar-
ketplace.
Foam densities range from less than 1 to more than 6
pounds per cubic foot. Higher density foams are typi-
cally more durable than lower density foams because
they contain more mass of polymer per unit volume (3).
The higher density foams, however, require more raw
material and hence have higher production costs.
The firmness of a foam defines its load-bearing ability.
The most common measure of firmness is the indention
force deflection (IFD). IFD is the force required to indent
a 50-square-inch section of a larger sample to a prede-
termined percent indentation. Most commonly, this is 25
percent of a 4-inch thick sample. Foam IFD can range
from 10 pounds for soft foams to over 100 pounds for
extra-firm foams (both at 25 percent).
Different grades of foam have different primary applica-
tions, although the relationship between grade and ap-
plication is not strict. For instance, the density of foam
used for seat cushioning can range from 1 to 3 pounds
per cubic foot, depending on quality and other specifi-
cations. In general, lower density and softer foams are
used for backs and armrests in upholstered furniture.
Low density, stiff foams are well suited for packaging.
Foams with higher densities are used for higher quality
seat cushions, bedding, and carpet cushions.
In addition to density and IFD grades, polyurethane
foam grades are specified based on additives that are
used to achieve specific properties. Some additives are
inert materials that become incorporated in the foam
polymer matrix. Others are actually incorporated into the
polyurethane polymer chains or increase cross-linking
between polymer chains. The most important of these
additives are combustion modifiers. Combustion modifi-
ers operate by several different mechanisms; some sim-
ply provide a heat sink, others give off incombustible
gases when heated, and still others actually modify the
foam's mechanism of combustion (4).
2.3 Foam Quality Measurements
Physical properties measured as indicators of foam
quality include resilience, hysteresis, dynamic fatigue,
air flow, tensile strength, elongation, and tear strength.
Resilience is determined by a ball rebound test. Com-
pression set is a laboratory test used to determine the
ability of a foam to return to its original shape after being
compressed under specific laboratory conditions.
2.4 Chemistry of Polyurethane Foam
Production
2.4.1 Key Ingredients
The reaction of three key ingredients produces flexible
polyurethane foam: a polyol, a diisocyanate, and water.
Figure 2-I illustrates the chemical structure of the poly-
ols and diisocyanates. Other ingredients are often
added to modify the polymer, and catalysts are used to
balance the principal foam production reactions. The
amount of each ingredient used in a foam formulation
varies depending on the grade of foam desired. Foam
formulations are generally denoted in terms of the num-
ber of parts (by weight) of diisocyanate, water, and other
components used per 100 parts polyol.
The polyol essentially forms the starting point for the
foam polymer. A polyol is an organic polymer charac-
terized by more than one terminal hydroxyl (OH) group.
In flexible foams, the most commonly used polyols are
trifunctional, with three terminal hydroxyl groups. Both
polyether and polyester polyols are used in the produc-
tion of slabstock foams, but polyether polyols are the
most common and are used exclusively in molded
foam production. Polyether polyols are produced by
the polymerization of ethylene oxide and propylene oxide,
starting with glycerine. The molecular weight of polyols
used in foam production ranges from about 1,500 to
NCO
OCN
NCO (2,4)
Toluene Diisocyanates
NCO
NCO
(2,6)
NCO
Polymeric Methylene Diphenyl Diisocyanates
{-c,
LR
H2-C-O-
1
HO-I-CH-CHJ-O-C-H
n '
Polyether Polyol
("R" is a methyl group or hydrogen)
-OH
n
Figure 2-I. Reactants typically used in the production of poly-
urethane foam.
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about 6,000. Polyols may be modified with other poly-
mers using a grafting process. The majority of slabstock
foam is made using 3,000 molecular weight polyol.
The second key ingredient in foam formulation, diisocy-
anate, links polyol molecules to produce the foam poly-
mer. The diisocyanates used in flexible foam production
are primarily toluene diisocyanate (TDI) and, less often,
polymeric methylene diphenyl diisocyanate (MDI). Typi-
cally, TDI used in foam manufacture is a mixture of the
2,4- and 2,6-isomers, at a typical ratio of 80 percent to
20. TDI is used primarily in slabstock production, and
polymeric MDI is used primarily in molded foam produc-
tion. Neither slabstock producers nor molded foam pro-
ducers use one diisocyanate to the exclusion of another.
2.4.2 Foam-Producing Reactions
Both the polyol and the diisocyanate are liquids at room
conditions prior to the foam-producing reaction. When
they are mixed with water under carefully controlled
conditions, two key reactions occur. These reactions are
illustrated in Figure 2-2.
The faster reaction is that of the diisocyanate with
water. This reaction has two important results: it
produces polymer chains coupled by "urea" link-
ages (-R-NH(C=O)NH-R-), and it liberates carbon di-
oxide (CO,), which serves as a "blowing agent" to
expand the reacting polymer mass. (Foam blowing
agents are discussed further in the next section.)
The second key reaction is that of the polyol with unre-
acted isocyanate groups at the ends of urea chains,
produced during the faster isocyanate-water reaction.
The polyol-isocyanate reaction produces the charac-
teristic "urethane" linkage from which the term "polyure-
thane" is derived (R^NH-COO-Ra), where RT is the
urea chain segment and R2 is the polyol. Other ingredi-
ents used as polymer chain modifiers also react with the
isocyanate.
These reactions proceed quickly at the outset of the foam
production process. C02 generated in the isocyanate re-
action causes the foam to expand to its full volume within
minutes after the ingredients are mixed and poured. Re-
action rates must be balanced so that the polymer is strong
enough at this point to maintain its shape. Reactions of
isocyanate groups with water and polyol, however, con-
tinue after the foam reaches full volume.
Any isocyanate groups that do not react with water,
polyol, or chain-modifying ingredients can form cross-
linkages by reacting with hydrogen atoms at midchain
urea or urethane groups (replacing amine hydrogens).
These cross-link reactions are part of the foam curing
process and affect the strength and elasticity of the foam
polymer. Therefore, the amount of diisocyanate relative
to other ingredients in the formulation is an important
parameter in determining foam properties.
{R}-N=C=O + H2O -»{R}-NH2 + CO, T
Reaction of Diisocyanate With Water
H H
{R}-NH2 + {R1 }-N=C=O->{R}-N N-{R1}
Reaction of Diisocyanate With Amine
{R}-N=C=O + {P}-OH->{R}-NH-C
CMP)
Reaction of Diisocyanate With Polyol
Figure 2-2. Polyurethane foam production reactions.
The isocyanate "index" determines the relative amount
of isocyanate; this index is defined as the ratio, ex-
pressed in percent, of the number of moles of isocy-
anate groups to the number of moles of other chemical
groups that react with isocyanate. An index of 105 indi-
cates a 5-percent excess of isocyanate, while an index
of 95 indicates a 5-percent shortfall of isocyanate. An
isocyanate index of 100 reflects balanced stoichiometry.
All of the above reactions are exothermic, especially the
reaction of isocyanate with water. This causes the tem-
perature of the foam to rise to between 250°F and 350°F.
Maximum temperature is reached 30 minutes to 1 hour
after the mixing of foam ingredients; the temperature
slowly declines as the ambient air interchanges with the
gases in the foam cells. Full curing of the foam may
require up to 48 hours (4).
2.4.3 Blowing Agents
Flexible polyurethane foam production is a carefully bal-
anced chemical reaction that simultaneously combines
in situ polymer formation with gaseous expansion of the
nucleated polymer. Drainage from the cell windows in
the rising foam mass forms the support struts, and at a
crucial point the windows break open, releasing the
entrapped blowing agent and thus leaving the open
cellular strut structure as the final foam product. The
primary blowing agent is CO2 from the water/diisocy-
anate reaction. Auxiliary blowing agents (ABAs) can be
used to supplement the action of the primary CO2 blow-
ing agent.
Many grades of foam are produced using only CO2 gas
as the blowing agent. Increasing the amount of water in
-------
a formulation generally produces a lower density foam
because this increases the production of CO2 blowing
agent. There is a practical limit, however, to the amount
of water that can be used. First, an increased amount of
water causes the number of urea linkages in the final
polymer to increase; these linkages tend to make the
polymer stiffer because they undergo hydrogen bond-
ing. Increased stiffness is also noted from the urea
structure that is rigid and tends to be crystalline. Second,
the isocyanate-water reaction is extremely exothermic;
therefore, too much water can cause high temperatures
that can scorch the foam or even cause it to ignite.
As a result, some grades of foam require the use of an
ABA. The ABA is mixed as a liquid with the foam reac-
tants when the reactant mixture is first poured. As the
exothermic polymerization reactions raise the tempera-
ture of the polymer mass, the ABA vaporizes, supple-
menting the blowing action of CO2. ABA vaporization
also removes excess heat from the foam, reducing the
potential for scorching or autoignition.
The amount of ABA required depends on the grade of
foam being produced and the ABA used. ABAs are most
important for low density and soft foams. For low density
foams, ABAs are used in conjunction with water blowing
to avoid overheating. In the case of soft foams, ABAs
provide blowing action without increasing the foam's
stiffness. ABAs are used most frequently in slabstock
foam production.
Several chemicals have been used as ABAs in slab-
stock foam production, but methylene chloride (CH2CI2)
is by far the most widely used chemical for this applica-
tion. Nearly 17,000 tons of methylene chloride were
used for slabstock ABA applications in 1992. The sec-
ond most frequently used ABA in 1992 was 1 ,1,1 -trichlo-
roethane (TCA or methyl chloroform), at about 2,000
tons. Trichlorofluoromethane (CFC-11) is used as a
blowing agent for integral skin molded foams (4).
ABA gases are difficult to capture as they emanate from
polyurethane foam during production and curing. During
production, ventilation rates are high, yielding a low
concentration stream. During curing, the foam is gener-
ally left in an open warehouse, and the ABA is released
slowly over a 24-hour period; therefore, the concentra-
tion of ABA in the warehouse is low. ABA gases are thus
simply vented to the atmosphere, either through root
exhausts or through fugitive means, at almost all foam
plants in the United States.
Releases of ABAs to the atmosphere are substantial—
almost 20,000 tons in 1992. Because of the difficulties
of using add-on controls to treat ABA emissions, foam
producers, equipment vendors, and foam chemical sup-
pliers have been exploring pollution prevention methods
for reducing or eliminating ABA use. These include al-
ternative foam production technologies, mechanical
cooling methods, and alternative chemical formulations.
In their evaluations of technologies to reduce or elimi-
nate ABAs, however, foam producers are sensitive to
any potential degradation in foam quality and increases
in manufacturing costs.
2.5 Current Environmental Releases
Emissions to the atmosphere constitute the major envi-
ronmental release from flexible polyurethane foam
manufacturing. The bulk of emissions results from ABA
use, mainly in the manufacture of slabstock foam. Sub-
stantial emissions also result, however, from the use of
organic solvents in adhesives and equipment cleaning
operations. Table 2-I summarizes emissions from differ-
ent operations in slabstock and molded foam production
and fabrication. The emissions reported for hazardous
air pollutants in Table 2-1 are based on a recent survey
of these emissions by EPA/ESD (2).1 Emissions are
based on sales figures and company reports to EPA's
Toxics Release Inventory (5). The volatile organic com-
pound (VOC) emissions are mainly related to the
Table 2-1. Summary of 1992 Emissions From Flexible Polyure-
thane Foam Production
Emission Source
Slabstock foam
Blowing agent
Total
Emissions
(tons/year)
16,968
Primary Chemicals
Methylene chloride,
Fabrication 1,401
Chemical storage and 49
handling
Rebond operations 11
Slabstock foam total 18,430
Molded foam
Equipment flushing 440
and cleaning
Blowing agent 60
Mold release 10,000
Chemical storage and 43
handling
Other 17
Molded foam total 10,560
TOTAL 28,990
methyl chloroform
Methyl chloroform
Methylene chloride,
TDI
Methylene chloride,
TDI
Methylene chloride
CFC-11 (for integral
skin foams)
Naphtha solvent
TDI and MDI
1 Williams, A. 1994. Updated estimate of HAP emissions from slabstock
foam production. Personal communication from A. Williams, EC/R Inc.,
to Lou Peters, Polyurethane Foam Association. February 8.
-------
molded foam process and the use of mold release
agents that contain high levels of VOC solvents.
There are no process wastewater discharges from this
industry; the water used in the foam reaction is entirely
consumed in that reaction. Water is used in some cases
for noncontact cooling of foam reactants, but no dis-
charges are reported from these systems.
Little solid waste is generated by either slabstock or
molded foam production because most scrap is used in
"rebond" operations. For this process, slabstock foam
producers recycle scrap from cutting and fabrication
operations. The scrap is chopped into small pieces, then
reconstituted with a polyuretnane adhesive to produce
an aggregate polyurethane foam product widely used in
the production of carpet cushions. About 27 percent of
slabstock foam facilities include rebond operations, and
some rebond operations are free-standing. These facili-
ties also acquire bales of scrap from plants that do not
have rebond operations.
Slabstock foam production lines occasionally produce
bad batches, which are unsuitable even for rebonding.
This material must be treated as a hazardous waste
under the Resource Conservation and Recovery Act
(RCRA) if it contains unreacted isocyanate. In addition,
equipment cleaning operations at both slabstock and
molded foam plants produce some solvent waste
subject to RCRA regulations. These wastes are gener-
ally shipped off site for treatment or disposal. Polyethyl-
ene coated paper and polyethylene film are used to
continuously line the foam machine conveyor during
production. These liners are stripped off after the foam
has traversed the length of the foam tunnel or after the
foam bun has cured. These materials are discarded as
nonhazardous waste.
In all, the polyurethane foam industry (including both
flexible and rigid foam manufacturing) reported ship-
ment of wastes containing 353 tons of toxic chemicals
to offsite waste treatment facilities in 1992. This figure
includes 222 tons of methylene chloride, 104 tons of
methyl chloroform, 21 tons of TDI, and 6 tons of poly-
meric MDI (5). The methylene chloride and methyl chlo-
roform wastes are spent chemicals, typically shipped in
drums. TDI and MDI wastes may include contaminated
raw materials or may be present in off-specification foam
product.
2.6 References
1. SPI. 1990. End-use market survey on the polyurethane industry in
the U.S. and Canada. New York, NY: Society of the Plastics In-
dustries, Polyurethanes Division.
2. Norwood, L.P., A. Williams, and W. Battye. 1994. Summary of
flexible polyurethane foam information collection requests (ICRs).
Presented at a meeting of the U.S. Environmental Protection
Agency and the Polyurethane Foam Association. February 2.
3. Kreter, RE. 1985. Polyurethane foam physical properties as a
function of foam density, in: Proceedings of the Society of the
Plastics Industries, 32nd Annual Technical/Marketing Conference.
New York, NY: Society of the Plastics Industries, Polyurethanes
Division, pp. 129-133.
4. Woods, G. 1987. The ICI polyurethanes book. New York, NY: ICI
Polyurethanes and John Wiley & Sons.
5. U.S. EPA. 1992. Toxics Release Inventory. Washington, DC: Office
of Toxic Substances.
-------
Chapter 3
Pollution Prevention in Slabstock Foam Manufacture
Slabstock foam accounts for about 75 percent of the
flexible polyurethane foam produced in the United
States (1). Slabstock foam production is a continuous
process that produces long, rectangular or cylindrical
"buns" of foam. These are cut and shaped into the
desired configuration. The largest markets for Slabstock
foam products are in furniture, bedding, automobile
seats and cushions, packaging materials, and carpet
cushions.
This section reviews Slabstock foam production proc-
esses, identifies and quantifies the extent of emissions
of pollutants, and describes pollution prevention options
that can be implemented to reduce these emissions. A
major focus of this section is on alternative auxiliary
blowing agents (ABAs), or technologies that facilitate
the use of alternative ABAs. In addition to ABA substitu-
tion, the section also covers the following pollution pre-
vention options:
. Add-on controls for capturing and reclaiming ABAs.
• Control of toluene diisocyanate (TDI) emissions.
• Reducing releases during chemical handling, stor-
age, foam fabrication, and equipment cleaning.
3.1 Slabstock Foam Production
Ingredients in Slabstock foam production include diiso-
cyanates, polyol, water, ABA, catalysts, and any fillers,
chain modifying agents, or other additives. TDI is the
most widely used diisocyanate, although polymeric
methylene diphenyl diisocyanate (MDI) is used for some
grades of foam. The most widely used ABA is methylene
chloride. Methylene chloride and other solvents are also
used to clean equipment and to form adhesives for foam
fabrication operations.
3.1.1 Typical Horizon tal Foam Production
Line
The predominant commercial process for Slabstock
foam manufacture involves a continuous horizontal
foam machine with a one-shot mixing system for the
foam ingredients (see Figure 3-I). In the "one-shot"
system, the raw materials are continuously metered to
a single mix head that typically accommodates six or
more separate streams (2). The mixed raw material
stream is dispensed to the foam line, which is essentially
an enclosed conveyor system. The conveyor is 6 to
8 feet wide and up to 200 feet long, and moves at about
15 feet per minute (3-5). The initial section of the ma-
chine typically slopes downward so the foam does not
fall backward as it rises.
The conveyor is housed in a foam machine tunnel,
which is ventilated to the outside to remove the blowing
agents and other gases that may be given off in the foam
reaction. The foam tunnel generally is open at the be-
ginning of the foam conveyor so that operators can
monitor the initial foam rise. A roller system applies a
plastic or paper lining sheet to the top of the conveyor,
and the liquid raw material feed is dispensed onto this
moving sheet. Roller systems also apply plastic or paper
liners along the sides of the conveyor.
Reactions between the raw materials (discussed in
Chapter 2) produce a polyurethane polymer, as well as
blowing gases that form bubbles in the polymer. Within
a few seconds after leaving the mix head, the raw
materials begin to "cream." The cream stage marks the
beginning of the foam-producing reactions and an in-
crease in the viscosity of the reacting mass. This is
followed by the rise stage, in which the blowing agent
causes the foam to rise to its full height. The foam
polymer also begins to gel at or very close to the end of
the rise.
The foam reaches its full height in 1 to 2 minutes, or about
25 feet down the conveyor. Full height is typically 2 to 4
feet, depending on the pour rate and the characteristics
(especially density) of the foam being produced. After 5 to
10 minutes, polymerization reactions have progressed far
enough for the foam to be cut and handled (6).
The foam is cut by a "flying saw," which moves in
tandem with the conveyor while the cut is being made
to ensure a straight cut. The length of a bun ranges from
less than 5 feet to as long as 200 feet. Each freshly cut
bun is removed from the conveyor and transferred to a
curing area.
Once the foam line starts up, it typically operates for 1
hour or longer, usually producing 10 or more buns with-
-------
\ x"\ s
Polyol
TDI
MeCI
or
Other
ABA
r
Console
Water
Surfactant
Catalyst
To Sales -
Trimming and
Fabrication
1' v?"~,l I , I
^ I '*?-'! I-"' '1
Bun Curing and Storage
1 - Chemical storage
2 - Multiple-stream metering and mixing head
3 -Traversing dispersing head (if used)
4 - Feed trough (Maxfoam)
5 - Conveyer enclosure with
exhaust fans and stacks
6 -Top surface wrapping rolls (optional)
7 -Side paper takeoff rolls
8 - Bottom liner paper roll
9 - Bun saw exhaust hood
10 - Bun saw and operator station
Figure 3-1. Typical slabstock production line for flexible polyurethane foam.
out any breaks in the raw material feed stream. An
operating cycle of the foam line is called a "pour."
Changing the raw material mixture can produce different
grades of foam in a single pour. Most plants have com-
puterized controls at the mix head metering system that
allow the raw material mixture to be changed at precise
intervals (3-5). The width of the rectangular bun can be
varied throughout the length of the pour to yield the
optimum size for fabrication requirements.
3.12 Variations on the Horizontal Foam
Production Line
Since the development of the slabstock process, foam
producers have been modifying the foam equipment in
an effort to produce a more uniform, flat-top bun, thereby
minimizing waste and raw material consumption. Al-
though the industry's goal in these modifications is proc-
ess optimization, the changes also should be viewed as
pollution prevention measures. The process optimiza-
tion measures serve to reduce both the amount of solid
waste generated and the amount of blowing agent that
is used (and subsequently released to the atmosphere).
The basic slabstock foam production line can vary in
several ways. First, the mix head is classified as either
low pressure or high pressure. In a low-pressure sys-
tem, a high-shear stirrer within the mix head combines
the raw materials. In a high-pressure system, the raw
materials are metered to the mix head at a pressure of
300 to 3,000 pounds per square inch, gauge (psig).
Although the mix head contains a small stirrer, impinge-
10
-------
ment of the high-pressure streams within the mix head
mainly accomplishes mixing (6).
The method used to dispense the mixed raw material
stream to the conveyor also varies. In older processes,
the mix head nozzle directly dispenses raw material to
the conveyor system. The mix head traverses the con-
veyor, spreading a uniform 1- to 2-inch layer of liquid
ingredients that are in early stages of reaction.
Most plants in the United States have adopted a vari-
ation on the raw material dispensing technique called
the Maxfoam process, illustrated in Figure 3-2 (7). In the
Maxfoam process, the feed stream flows from the mix
head to a trough located at the beginning of the ma-
chine. As the feed begins to cream and foam in the
trough, it spills over onto the conveyor. This system
produces a flatter bun, which reduces the amount of
scrap foam.
Even with the trough feed system, however, the bun is
not perfectly flat; the center tends to rise higher because
of friction along the sides. Some process variations have
been developed to mitigate this effect. For example, in
the Draka-Petzetakis process, the side wall liners are
forcibly lifted to produce a more even block profile.
Mixhead
Another modification of the basic slabstock foam pro-
duction line, the Planibloc-Hennecke process, employs
a liner, which is applied to the top of the bun to control
the bun profile (8).
Some round foaming machines have also been devel-
oped to produce cylindrical foam blocks (8). Round
foaming processes typically use moving, conveyor-
mounted molds. Different methods are used to distribute
the raw material mixture in the mold and to shape the
rising foam into a cylinder. A peeling process is used to
fabricate a thin sheet of foam from these cylinders. In
this operation, the roll is positioned in contact with a thin
knife blade, which runs parallel to the cylinder's axis.
The cylinder is then turned and accurately adjusted
toward the blade to continuously remove a uniform thin
sheet. This sheet can be nearly as thin as 0.030 inches.
Horizontal foam production lines generally are operated
at high production rates. The Vertifoam process, devel-
oped in England in the early 1980s, operates at lower
production rates than typical horizontal processes. In
the Vertifoam process, illustrated in Figure 3-3, the raw
material mixture is placed at the bottom of a vertical
expansion chamber. The sides of the chamber are lined
with long sheets of either paper or plastic, which are
Figure 3-2. Maxfoam production process.
11
-------
Foam Block—
lo Curing Area
Foam Cutting Saw
Liner Takeoff
Liner Feed
Raw Material Feed
Figure 3-3. Vertifoam foam production process.
drawn upward by roller systems. The foam expands
upward in the chamber and is cured enough to be cut
by the time it reaches the chamber top. As it leaves the
top of the chamber, the foam is cut horizontally into
blocks up to 10 feet long.
A modification of the Vertifoam process, called the Hy-
percure or Enviro-Cure process, potentially allows the
capture and recovery of blowing agent. Currently, no
installations in the United States operate in this mode.
This process and other modifications of the basic hori-
zontal foaming process that allow ABA recovery or re-
duce ABA use are described later in this section.
3.1.3 Foam Blowing and Use of Auxiliary
Blowing Agents
Carbon dioxide (CO,) gas liberated in the diisocyanate-
water reaction serves as a blowing agent to produce foam
(see Section 2.3). Many grades of slabstock foam, how-
ever, require the use of an ABA. The ABA is mixed with the
foam reactants as a liquid when the reactant mixture is
first poured. As the exothermic polymerization reactions
raise the temperature of the polymer mass, the ABA
vaporizes.
ABAs serve two functions. First, they supplement the
blowing action of CO2 from the water-diisocyanate reac-
tion. In vaporizing, ABAs also remove excess heat from
the foam polymerization reactions.
ABA gases are difficult to capture during production and
curing because of the low concentration of emissions.
This use of ABA represents the largest opportunity for
pollution prevention in the slabstock industry.
Figure 3-4 shows typical ABA use rates for different grades
of foam. These values are derived from a recent survey of
slabstock foam producers carried out by the U.S. Environ-
mental Protection Agency's Emission Standards Division
(EPA/ESD). ABA use ranges from 0 to over 20 pounds per
100 pounds of polyol (pph). The average ABA use for all
grades of foam is about 5 pph. Low density, soft foams
require the highest ABA use rate.
Until the mid-l 980s, trichlorofluoromethane (CFC-11)
was the preferred ABA for polyurethane foam produc-
tion. CFC-11 is a potential stratospheric ozone depleting
agent, and the slabstock industry achieved better than
99 percent reduction in its use by the end of 1992.
60
50
vt j n
T3 40
c
30
20
10
0 pph
0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2
Density (pounds per cubic foot)
Figure 3-4. Methylene chloride use rates for different foam
grades. Contours represent methylene chloride use
in pounds per hundred pounds polyol (pph). Con-
tour locations are approximate.
12
-------
CFC-11 has been replaced largely by methylene chloride,
currently the largest-volume ABA for slabstock foam pro-
duction. Methylene chloride has been classified by EPA as
a category B2 carcinogen (a "probable human carcino-
gen"). As a result, several states regulate methylene chlo-
ride as a toxic chemical. In addition, methylene chloride has
been listed as a hazardous air pollutant (HAP) under
Title III of the 1990 Clean Air Act Amendments.
TCA is used as an ABA in areas where methylene
chloride is regulated by state air toxics programs; how-
ever, TCA is also listed as a HAP under Title III of the
Clean Air Act Amendments. Acetone is used as an ABA
in some instances where state air toxics programs limit
methylene chloride use.
3.1.4 Foam Curing and Storage
Conveyors or overhead cranes move the foam buns
from the production line to a curing area. The curing area
is ventilated to remove ABA, which continues to ema-
nate from the curing bun. Typically, buns are cured for
about 24 hours prior to fabrication or shipping. Buns may
be transferred from the curing area to a separate stor-
age area prior to shipping or fabrication; when fully
cured, they may be stacked four to five buns deep.
3.1.5 Foam Fabrication
Fabrication is the conversion of large slabstock foam
buns into the sizes and shapes that customers order. A
machine known as a slitter cuts the large bun into slabs
of the desired thickness. Vertical bandsaws or hand-
cutting techniques are used to convert these slabs into
furniture components.
Many of the cushions supplied to the furniture industry
are composites of two or more materials. One of the
more common materials used with foam is polyester
fiberfill. This spun product is applied to the cushion to
provide cover fillout, initial softness, and, in some in-
stances, compliance with United Furniture Action Council
(UFAC) voluntary guidelines. Solvent-based adhesives
are used to attach these materials to the foam pieces at
glue stations. The glue stations are generally equipped
with local ventilation to remove the solvent vapors ema-
nating from the adhesives. The use of solvent-based
adhesives represents another major opportunity for pol-
lution prevention, accounting for 1,401 tons of HAP
emissions per year, Water-based adhesives, hot melt
adhesives, and other measures for reducing solvent
emissions are discussed in Chapter 5.
3.1.6 Rebond Operation
Slabstock foam production generates up to about 12
percent of waste offcut material (8). Foam producers
recycle this scrap in the rebond operation. About 27
percent of US. foam plants have onsite rebond opera-
tions (9); in addition, some rebond facilities are free-
standing. Plants operating rebond facilities also receive
baled scrap from other plants and fabricating facilities,
and even from other countries. Rebond foam is widely
used for carpet cushions.
In the rebond operation, scrap foam is first reduced to
3/8- to 3/4-inch crumbs in a granulator or beetling mill.
The crumb material is then loaded into a blender, where
it is coated with a prepolymer binder of polyol and TDI.
This coated mixture is then charged to either a cylindri-
cal or rectangular mold, where it is compressed and
treated with steam. The steam reacts with the prepo-
lymer to produce a polyurethane polymer, which binds
the foam crumbs together (8).
The rebond product is removed from the mold and al-
lowed to cool and set for about 24 hours. The molded
product is then peeled to produce a long, thin sheet of
material up to 9/1 6 of an inch thick. This sheet is usually
laminated on one side with a covering material and then
rolled for shipment (4).
3.2 Methods for Reducing Auxiliary
Blowing Agent Releases
3.2.7 Overview of Releases
Table 3-I summarizes emissions from different slab-
stock foam production processes.' The bulk of emis-
sions from the industry result from ABA use. About 40 to
75 percent of ABA emissions emanate from the foam
machine tunnel itself, with the balance emitted from
curing and storage areas (2, 10). Emissions also result
from the use of organic solvents in adhesives in the
fabrication process, as well as from equipment cleaning
operations.
3.2.2 Production of Water-Blown Foams
The blowing action of CO2 gas in foam production is
called "water blowing" because CO2 arises from the
reaction between water and diisocyanate groups.
Higher density, moderate indentation force deflection
(IFD) foams can be produced using C02 as the sole
blowing agent (see Figure 3-4). Because higher density
foams use more polymer material per unit volume, how-
ever, they are more expensive to produce than low
density foams. Figure 3-5 shows 1992 production vol-
umes for different foam density grades, illustrating the
importance of low density foams.
For any particular grade of foam, there is range of
possible "mixes" of water blowing and ABA blowing.
Therefore, ABA usage can be reduced at some plants
1 Williams, A. 1994. Updated estimate of HAP emissions from slab-
stock foam production. Personal communication from A. Williams,
EC/R Inc., to Lou Peters, Polyurethane Foam Association. February 8.
13
-------
Table 3-1. Summary of 1992 Emissions From Polyurethane Foam Production
Emission
Source
Foam
production
Fabrication
Chemical
storage and
handling
Rebond
operations
Total
Total
Emissions
(tons/yr)
16,968
1,401
49
11
18,429
Methylene
Chloride
14,757
41
26
10
14,835
TCA
2,102
1,332
10
0
3,445
Propylene
Oxide
101
0
0
0
101
TDI
6
0
10
1
17
Methyl
Ethyl
Ketone
0
10
0
0
10
Glycol
Ethers
0
10
1
0
11
Other
HAPs
2
7
1
1
11
10
0.
a
:tK- v*:
120 1.40 1.60 180 2.00
Foam Density (pounds per cubic foot)
2.20 2.40
Figure 3-5. Foam production as a function of density grade, 1992. (Values are approximate.)
by altering the foam formulation and increasing the amount
of water blowing; this generally involves reducing the
isocyanate index. As noted in Chapter 2, the amount of
water blowing that can be used is limited. Formulation
changes, however, can reduce ABA usage by 10 per-
cent on average (11). These changes can be imple-
mented at little or no cost; therefore, many plants have
already made these changes.
Foam softening agents and quick-cooling technologies
can increase the amount of water that a given formulation
can incorporate. These technologies are discussed below.
3.2.2.1 Foam Softening Additives and Systems
Additional water in a formulation reduces ABA use but
also produces a stiffer foam by increasing the number
of urea polymer linkages and, hence, the number of
sites available for hydrogen bonding. Softening ingredi-
ents can counteract the influence of these additional
urea linkages. Thus, these ingredients can be used as
a pollution prevention measure to reduce or eliminate
the use of ABAs in many grades of foam.
Softening systems can be used without substantial add-
on equipment. In some cases, there may be a small cost
to install additional chemical piping (12). Additional
chemical costs may be substantial for some foam
grades, however. Estimates of the additional chemical
costs range from $2,500 to $25,000 per ton of blowing
agent saved (2, 9, 13).
Softening ingredients include polymer chain modifiers,
stabilizing additives, and specialty polyols; the specialty
polyols may replace all or part of the polyol used in the
foam formulation, Softening ingredients generally are
used in conjunction with changes in foam chemistry,
such as a reduced isocyanate index and special cata-
lysts. Special surfactants may also be used to control
cell structure.
A variety of softening agents and systems are available
from a number of different suppliers of foam chemicals.
14
-------
Table 3-2 summarizes currently available softening ad-
ditives and systems. For each system, the table gives
applicable density and firmness ranges, and the name
of the company licensing or selling the ingredients. As
the table shows, systems are available to cover the full
range of IFD grades without using ABAs, while achiev-
ing densities as low as 1.5 pounds per cubic foot. Lower
densities can also be achieved for medium and firmer
grades of foam.
Table 3-2. Summary of Alternative Foam Softening Additives
and Systems (7, 14-16)
Description
Density Firmness Source or
Limit Grades Licensing
(pcf) (IFD-25) Company
High resiliance systems
Ultracel 1.3
Resteasy Plus 1.5
All
Medium,
firm
Extended range polyols3 1.3b >15C
VORANOL 3583
XUS15216.01
XUS15241 .00
XZ94532.00
CP 1421
X282229.00
ARCO Chemical
BASF
Corporation
Dow Chemical
USA
Dow Chemical
Europe
Dow Chemical
Pacific
ARCOL F-1500
ARCOL DP-1022
Additives
Ortegol310 1.5
Geolite 1 .0
Enichem modifiers 1.1
>10C
>20C
>20C
ARCO Chemical
Goldschmidt
Chemical Corp.
OSi Specialties
Enichem
In general, these specialty polyols are tailored for specific applica-
tions. No particular product can be used to produce all foam grades.
Rather, different polyols are best suited for different foam grades.
Densities as low as 1 .1 pounds per cubic foot can be achieved with
some sacrifices in other foam properties.
°The minimum IFD achievable for these systems depends on the
density of foam being produced. The noted IFD minimum cannot
generally be achieved concurrently with the density minimum.
Research is ongoing into systems that can produce
lower density and softer foams than those shown in
Table 3-2. (Interim results of this research are frequently
reported at conferences organized by both the Society
of the Plastics Industries and the Polyurethane Foam
Association.) For example, Dow Chemical reported in
1994 on ongoing research into a chemical system that
would produce low density, soft foams in the range of
1.2 pounds per cubic foot with an IFD of 20 (17). In
addition, several companies are researching the pros-
pect of eliminating ABAs from all grades of foam by
combining foam softening technologies and mechanical
cooling technologies, discussed below.
3.2.2.2 Mechanical Cooling Technologies
Mechanical cooling systems force air through a slab-
stock foam block after the block has left the foam tunnel.
These technologies initially were developed to acceler-
ate the foam curing process, thus reducing warehouse
space requirements (18, 19). Forced cooling coupled
with water blowing, however, can also reduce or elimi-
nate the need for ABAs in the production of low density
foams. Cooling of the foam block is one of the key
functions of ABAs, and forced cooling can replace ABAs
in this role.
Mechanical cooling has been used to produce low den-
sity foams over a wide range of IFD grades without
ABAs (18-21). There are some adverse effects on foam
properties, however, when mechanical cooling is used
in conjunction with a high degree of water blowing. A
particular drawback has been lower resilience and
higher compression set.2 Densities as low as 0.95
pounds per cubic foot and IFDs (25 percent) as low as
14 have been achieved concurrently (21). Mechanical
cooling also has the added benefit of producing foam
blocks with more uniform properties than standard cur-
ing methods produce. This results from the more uni-
form block temperature profile.
Some complications are associated with the mechanical
cooling process. First, mechanically cooled foams gen-
erally require substantial formulation changes from tra-
ditional ABA-cooled foams because the forced cooling
cuts short some of the foam curing reactions. These
changes may necessitate some development costs.
Second, equipment costs are substantial, from
$500,000 to $2 million (7, 13). Finally, when low density
foams are produced without ABAs, the reliability of
the mechanical cooling system becomes critical. As
previously discussed, foam polymerization reactions
typically raise the temperature of the foam block to
between 250°F and 350°F. Low density foams using a
substantial amount of water blowing raise the block
temperature even higher. Cooling system failure could
result in scorching of the foam blocks or ignition, in some
circumstances.
At least three companies are investigating variations in
mechanical cooling technologies on a commercial scale.
These processes are discussed below.
Crain Enviro-Cure Process
The Enviro-Cure process is illustrated in Figure 3-6 (22,
23). The process equipment consists of an enclosure
with conveyor and ventilation systems designed to han-
dle cut foam blocks. Blocks from the foam production
line are allowed to cure for a predetermined delay pe-
' Peters, L.H. 1994. Personal communication from Lou Peters, Poly-
urethane Foam Association, to J. Cantin, Eastern Research Group,
Inc. November 17.
15
-------
Exhaust Gases
Recirculated Air
Fresh Conditioned Air
Figure 3-6. Enviro-Cure foam production process.
riod, which is essential to allow the blocks to stabilize.
The length of this period is also important: if the block is
cooled too early, the polymer will not be strong enough
to produce a serviceable foam; too long a delay before
cooling can scorch the block.
Following the curing period, foam blocks are conveyed
end to end into the Enviro-Cure enclosure. The con-
veyor is a specially designed slat conveyor system with
gaskets along the sides. This design allows air to be
pulled from the bottom of the blocks. As each block
enters the enclosure, its sides are lined with plastic. A
ventilation system in the enclosure draws air through the
blocks, producing the desired cooling effect.
The Enviro-Cure ventilation system draws air from be-
neath the blocks in three stages. Air from the first and
third stages is exhausted to the atmosphere. Some of
the air drawn from the second stage is recirculated to
the top of the enclosure, while some is exhausted.
Chilled ambient air is mixed with the recirculated air and
introduced to the top of the enclosure. Regulating the
relative amounts of fresh and recirculated air controls
the temperature of air passing through the foam.
Grain Industries has used the Enviro-Cure process with
both Maxfoam and Vertifoam production lines. When
Enviro-Cure is used with Maxfoam equipment, the skin
must be removed from the top and bottom of the Max-
foam block. This is unnecessary with Vertifoam lines;
foams produced by Vertifoam equipment have little or
no skin because it is peeled off when the polyethylene
liner film is removed.
The Enviro-Cure process is licensed by Grain Industries
of Fort Smith, Arkansas. The equipment is manufactured
by Cannon USA, of Mars, Pennsylvania.
General Foam Rapid Cure Process
The Rapid Cure cooling process has been used on a
commercial scale with a Maxfoam production line (19).
The process can be used in configurations before or
after the foam line cutoff saw. In either case, the foam
must first undergo surface preparation, in which surface
skins are removed and other steps are taken to ensure
uniform airflow through the foam.
After surface preparation, the foam is passed over a
number of cooling stages. In each cooling stage, gas is
drawn from the foam into a collection chamber located
below the foam conveyor. This causes air to flow through
the foam, displacing CO2 from the water blowing re-
action and cooling the foam polymer matrix.
Air and displaced gases drawn from the foam in the
initial cooling stages are routed to a carbon adsorption
system. The carbon removes contaminants such as
antioxidants and diisocyanates, which are volatilized at
the high initial foam temperatures. Air drawn through the
foam in the later cooling stages is released to the atmos-
phere without treatment. These cooling stages reduce
the foam temperature to 150°F or lower.
General Foam has been testing the Rapid Cure system
on a commercial scale for more than a year (18). The
company holds three patents on the system, as well as
several pending patent applications.
16
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Trinity Quick Cure Process
The Trinity Quick Cure process consists mainly of an
enclosure equipped with a ventilation system. The first
step of the process is to prepare the surfaces on the two
sides of the bun by slitting the sides with razor knives.
The bun is then conveyed into the enclosure and pushed
up against blower inlets located on one side of the
enclosure. The ventilation system is then used to create
suction at these inlets, drawing air through the foam.
This air is conditioned and returned to the other side of
the bun, along with some fresh makeup air (24).
The primary objectives of the Trinity Quick Cure process
are to shorten processing time, to produce a more uni-
form profile of IFD, and to improve compression set
properties (24). The process has the added benefit of
reducing blowing agent requirements. Trinity is reluctant
to use the process to eliminate blowing agent for low
density foams, however, because of the high internal
foam temperatures that would be produced and the fire
hazard that would ensue if the cooling system failed.
3.2.3 Liquid C02 Blowing Technology
As discussed above, many foam manufacturers are ex-
ploring formulation changes and technologies that would
allow increased use of the water-diisocyanate reaction
to generate additional CO2 blowing agent. A new tech-
nology has recently been developed for introducing liq-
uid C02 into the foam feed stream. In this process,
called the CarDio process, the carbon dioxide liquid is
added to the polyol stream before reaching the mix
head. The CO2 evaporates, serving as a blowing agent.
In its overall function, liquid CO2 has some parallels with
methylene chloride and other chemicals used as ABAs.
C02 differs radically from "standard" ABAs, however, in
that it has a much lower boiling point. ABAs are liquid at
standard foam pouring temperatures and pressures,
and evaporate as polymerization reactions raise the
temperature of the foam mass. C02 is a vapor under
standard pouring conditions. In fact, to remain liquid at
pouring temperatures, CO2 must be kept under a pres-
sure of about 60 atmospheres. Thus, it vaporizes
quickly, generating a rapidly expanding froth when the
foam feed stream leaves the pouring nozzle.
The CarDio process controls this tendency toward rapid
expansion through a special "laydown" device. The lay-
down device follows the mix head and deposits a homo-
geneous reacting mixture on the fall plate. The design
of the laydown device results in a progressive release
of blowing agent in the reacting foam mass. This pre-
vents local concentrations of free gas that could cause
pinholes, or "chimneys," in the foam (25).
CarDio technology can be retrofit to an existing horizontal
foam line with the installation of the following equipment:
• CO2 metering pump assembly with a mass flowmeter,
as well as pipe work, valves, and controls.
• Polyol booster pump assembly.
• Premixing unit for CO2 and polyol.
. CarDio mixing head and flushing system.
• CarDio laydown device.
Retrofit costs have been estimated at $470,000 (13).
The CarDio process is built and licensed in the United
States by Cannon USA, a manufacturer of foam equip-
ment headquartered in Mars, Pennsylvania. The proc-
ess has been demonstrated on a commercial scale at a
plant in Italy. Although no U.S. plants are using the
CarDio system as of this writing, a few plants are ex-
pected to install the system for pollution prevention over
the next 6 months.
3.2.4 Reduced Pressure Foaming
Lower barometric pressures tend to increase blowing
efficiency and therefore to produce lower foam densi-
ties, if all other factors are equal. In fact, operators of
plants located above sea level correlate their use of
water and ABA with their elevation because of the re-
duced barometric pressure (7).
Efforts have been made recently to reduce or eliminate
the need for ABAs with enclosed foam pouring systems
that produce foams at a reduced pressure. At least two
companies have developed and patented technology for
reduced pressure foaming.
3.2.4.1 Variable Pressure Foaming Process
The variable pressure foaming (VPF) process can be used
to produce slabstock foams at pressures either lower or
higher than atmospheric (26). The VPF process is pat-
ented by Prefoam. The basic VPF process is very similar
to the standard horizontal foam line; it differs in that a
totally enclosed chamber replaces the open foam tunnel.
Foam chemicals are pumped into the enclosed chamber
and deposited onto a conveyor system, as in the stand-
ard Maxfoam process. The pressure in the chamber is
regulated by a fan, which draws air and CO2 blowing
gases from the chamber and through a carbon adsorber.
The foam travels down the conveyor and is cut with an
automatic cutoff saw. Following the cutoff saw, the foam
block enters a second airlock chamber, which is main-
tained at the same pressure as the initial foaming cham-
ber. The airlock chamber is opened to the atmosphere,
and the foam block is removed. The airlock is then
closed again and evacuated. During this time, foaming
continues in the first chamber.
The VPF process is expected to allow production of all
commercial grades of foam without the use of ABAs.
17
-------
The process has been used on a commercial scale in
the Netherlands and was recently installed in a commer-
cial facility in the United States. The U.S. process, how-
ever, has not been in place long enough to assess its
commercial viability. The main drawback of the process
is a high initial capital cost, estimated at $4 million to $5
million (13).
3.2.4.2 Controlled Environment Foaming
Process
The Foam 1 Company of Woodland, California, has
developed a process called controlled environment
foaming (CEF). Equipment for the process is manufac-
tured by the Edge Sweets Company of Grand Rapids,
Michigan. The process is essentially a batch process, in
which slabstock foam is actually produced in molds (27).
In its current embodiment, CEF process equipment con-
sists of two molds and a containment vessel that accom-
modates one mold at a time. The containment vessel is
connected to a carbon adsorber and a vacuum system.
In the CEF process cycle, one of the molds is placed
inside the containment vessel, and the vessel is partially
evacuated. Foam raw materials are poured into the
mold, and the foam is allowed to form. The pressure in
the containment vessel may be adjusted during the
reaction. When the foam is fully formed, the full mold is
removed from the vessel and replaced with the empty
mold. The foam is then removed from the first mold,
which is prepared for the next cycle.
The CEF process is expected to allow production of all
commercial grades of foam without the use of ABAs; in
fact, a paper on the process indicates that it can achieve
densities as low as 0.55 pounds per cubic foot (at
7 pounds IFD) without ABAs (27). Retrofit costs are
estimated at about $340,000 (13). The main drawback
of the process is that, as a batch process, its production
rate is considerably less than standard foam lines.
Again, the process has not been in use long enough to
assess its potential for commercial success.
3.2.5 Alternative B/owing Technology
The alternative blowing (AB) system is based on the
substitution of formic acid for some of the water in the
foam formulation. Formic acid reacts with diisocyanates
as follows:
HCOOH + 2 R NCO->R-NH-C-NH-R + CO2 + CO
II
0
Urea Linkage
This reaction produces a urea polymer linkage as in the
standard diisocyanate-water reaction. Both carbon mon-
oxide (CO) and C02 are produced (one mole each), how-
ever, whereas the diisocyanate-water reaction produces
only C02. Thus, the formic acid reaction doubles the
amount of gas generated.
Although not currently in use in the United States, the
AB system is licensed in the United States under the
tradename TEGO AB-M30 by Goldschmidt Chemical
Corporation of Hopewell, Virginia. AB-M30 is a mixture
of formic acid and formic acid salts. The system also
requires a proprietary amine catalyst (15).
The CO gas generated in the AB reaction is poisonous,
and care must be taken to ensure operator safety. Ex-
isting ventilation systems are generally adequate to re-
move CO from the foam tunnel itself. Additional
ventilation is generally required at the cutoff saw, how-
ever, as well as in foam cure and storage areas (7).
Goldschmidt also recommends the use of CO monitors
to ensure safety (15). Retrofit costs are not available.
Corrosion problems are associated with the use of
HCOOH. The use of formic acid salts lessens these
problems somewhat, but they still must be considered.
The AB system can yield a foam density as low as 1
pounds per cubic foot at an IFD (25 percent) of 40
without any ABA. At a density of 1.3 pounds per cubic
foot, an IFD of 30 can be achieved without any ABA (16).
Problems with compression set have been reported,
however, for very low density foams produced by the AB
system without ABAs (7).
When used in conjunction with ABAs, the AB system can
reduce ABA use by 33 to 66 percent (7). The AB system
can also be used in conjunction with quick cooling sys-
tems to achieve foam densities under 1 pound per cubic
foot (15). Foam producers are reluctant to rely on cool-
ing systems in place of ABAs, however, because of the
potential fire hazard.
3.2.6 Add-On Emission Control Equipment
for Reclaiming Auxiliary Blowing
Agents
3.2.6.1 Application of Carbon Adsorption to
Conventional Foam Processes
Carbon adsorption removes organic compounds from a
wide variety of air emission streams. In a carbon adsorp-
tion system, exhaust gases are passed through a bed
of activated carbon granules, and organic compounds
are adsorbed onto the surface of the carbon granules.
When the carbon is saturated, the captured organics are
desorbed, usually using steam. Carbon adsorption sys-
tems usually consist of two beds used in tandem. While
one bed is working, the second is being desorbed and
prepared for the next cycle.
Over the past several years, foam producers, equipment
manufacturers, and EPA have studied carbon adsorp-
tion as a means for reducing ABA emissions. In particu-
lar, EPA conducted a detailed feasibility assessment of
18
-------
carbon adsorption and other potential controls for foam-
ing operations (2). At least one plant is using carbon
adsorption with a conventional Maxfoam line.3 The sys-
tem has not been in place long enough, however, to
judge its long-term performance.
Most foam producers have considered such systems
impractical for a number of reasons. First, a carbon
adsorption system for the foam machine tunnel would
require a substantial initial capital outlay, estimated at
$530,000 (2). In addition, only about 50 percent of
the ABA emissions emanate from the foam tunnel.
The balance of the ABA is emitted from the cutting,
transport, curing, and storage areas at very low concen-
trations. Further, the foam machine tunnel is typically
only operated for a few hours a day. Finally, diisocyanate
emissions from the foaming operation would have a
tendency to poison the activated carbon. Therefore, a
sacrificial prefilter would need to be in place before the
carbon filter.
3.2.6.2 E-Max Enclosed Process With Carbon
Adsorption
In the E-Max process, the foam pouring operation is
carried out in a long, enclosed mold. The purpose of the
enclosed mold is to facilitate the capture and control of
emissions. The mold is exhausted to a sacrificial prefilter
followed by a carbon adsorber.
The E-Max process is patented by Unifoam of Switzer-
land. Equipment is manufactured by Periphlex in the
United States. One commercial-scale plant was operat-
ing in 1992 in the United States (7).
3.2.6.3 Application of Carbon Adsorption to
Forced Cooling Systems and Other
Systems
Carbon adsorption has been applied to exhaust streams
from the initial cooling stages of the Rapid Cure forced
cooling process. In addition, the Grain Enviro-Cure cool-
ing process can be equipped with carbon adsorption
(21). The carbon adsorption systems are designed to
remove contaminants such as diisocyanates and pre-
servatives that are volatilized from the hot foam during
the initial stage of the cooling process. Carbon adsor-
bers applied to these processes would also reduce
emissions of ABAs, if ABAs are used. Both of these
processes are expected to eliminate the need for ABAs.
ABAs are still needed for some low density grades of
foam, however, to obtain the desired foam properties.
Williams, A. 1994. Personal communication from A. Williams, EC/R
Inc., to W. Janicek, Flexible Foam Products, Terrel, TX. May 17.
Both the VPF and CEF reduced pressure processes are
also designed to be vented to carbon adsorption sys-
tems. The carbon adsorbers remove contaminants that
are vaporized from the foam under reduced pressure.
Both VPF and CEF are expected to operate without
ABAs, but the adsorption systems would reduce emis-
sions of ABAs if any were used.
3.2.6.4 Other Potential Add-On Control Systems
In addition to carbon adsorption, EPA assessed several
other potential add-on control technologies for ABAs
from foam production (2). These technologies included
incineration, conventional refrigerated vapor condensa-
tion, Brayton-cycle vapor condensation, and liquid ab-
sorption. Combustion of ABAs in an incinerator was
comparable with carbon adsorption in cost and effective-
ness. The other techniques were found to be inferior to
incineration and carbon adsorption.
Several other innovative control technologies have been
developed in recent years that have not been evaluated
for this industry. These include Photocatalytic destruc-
tion, biofiltration, and membrane separation.
3.2.7 Alternative Auxiliary Blowing Agents
Because of air toxics rules, the phaseout of chlorofluoro-
carbons (CFCs), and the listing of methylene chloride
and TCA as HAPs, foam producers have been exploring
nontoxic, non-ozone-depleting blowing agents. Acetone
is an alternative ABA that is currently being used suc-
cessfully on a commercial scale. Hydrochlorofluorocar-
bons (HCFCs) have received attention as potential
substitutes for CFCs in many applications, including
foam blowing. HCFCs are banned, however, for use in
flexible polyurethane foam.
3.2.7.1 Acetone
Acetone is currently being used on a commercial scale
in slabstock production and is suitable for all commercial
grades of foam. Acetone has some advantages over
methylene chloride: it is less expensive, and it has a higher
blowing efficiency than methylene chloride. Fifty percent
less acetone (by weight) is needed to produce a given
amount of foam, all other factors being equal.
The main drawback of acetone for foam blowing is its
flammability. (Flammability limits for acetone in air are
2.6 to 12.8 percent.) Methylene chloride and the other
ABAs discussed above are nonflammable. Therefore,
the substitution of acetone as a blowing agent generally
requires equipment modification to prevent fire hazards.
Modifications include:
• Improvement of the foam tunnel to create total
enclosure.
19
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. Use of explosion-proof lighting.
. Movement of motors to outside the tunnel, or substi-
tution of explosion-proof equipment.
• Increased tunnel ventilation.
• Installation of backup systems for tunnel ventilation.
Retrofit costs for a typical foam line are estimated at
$200,000. Once the system is installed, however,
chemical costs for acetone are lower than for methylene
chloride. As a result, the annualized cost of using ace-
tone is estimated at only about $12 per ton of emission
reduction (13).
Acetone blowing technology is licensed by Hickory
Springs Manufacturing Corporation of Hickory, North
Carolina.
One company also uses alkanes (C5 and higher) as
a substitute blowing agent for methylene chloride. Al-
though this would greatly reduce HAP emissions, the
alkanes may contain some n-hexane and i-octane,
which are listed as HAPs. No details are available on
the composition of the blowing agent, nor are details
available on necessary process changes. The technical
issues associated with this blowing agent, however, are
expected to be similar to issues associated with acetone.
3.2.8 Comparison and Cost Information for
Auxiliary Blowing Agenf Emission
Reduction Measures
Table 3-3 summarizes technologies that can be used to
reduce ABA emissions. The table gives approximate
emission reductions (in percent), as well as capital costs
and estimated cost-effectiveness values. Cost effective-
ness is given in terms of dollars per ton of emissions
reduced and is defined as the total annual operating cost
divided by the magnitude of the projected reduction in
emissions or total releases. The table also gives a quali-
tative comparison of retrofit equipment requirements,
chemical costs, and other potential problems associated
with the control measures.
3.3 Methods for Reducing Toluene
Diisocyanate Emissions
Diisocyanate is a key ingredient in foam production
reactions, in the formation of CO2 blowing agent as well
as in the formation of urea urethane polymer linkages.
Table 3-3. Summary of Costs and Requirements for Measures To Reduce HAP Emissions
Option
Water blowing
Foam softening systems
Potential
Emission
Reduction
(%)"
100
Approximate
Capital Cost
0
15-60°
cost
Effectiveness
($/ton)
1, 900-35 ,000b
32,000d
Equipment
Needed
None
1 ,790d-25,000b
Additional
Chemical
Cost?
Substantial
Minor
Other
Problems
Fire hazard
Yes
(high resilience systems,
extended-range polyols,
other additives)
Mechanical cooling
Mechanical cooling with
foam softening
Liquid COg blowing
Reduced pressure
foaming-VPF
Reduced pressure
foaming— CEF
AB technology
Add-on controls
Alternative ABAs — Acetone
85-906
100
100
100
100
-50f
-50
100e
500,000*-
2 million"
500,000f-
2 milliond
470,000d
4-5 million"
340,000d
NA
2,900-4,300b
200,000d
1,635d
NA
(263)d
1,660d
(161)d
NA
Substantial
(180)d
Substantial
Substantial
Yes
Substantial
Moderate
Minor
No
Some
No
Yes
No
No
No
Some
No
Fire-equipment
failure, degraded
foam properties
Development
needed
Complexity
Production rate
limited
Corrosion
Flammability
NA = not available.
() = cost savings.
These savings are not additive if two or more options are used simultaneously.
Farmer et al. (2); SRRP (12).
°SRRP(12).
° U.S. EPA (14).
8 CEC (11); acetone is still released, but levels are reduced 45 percent from methylene chloride emission levels.
' U.S. EPA/PFA (7).
20
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TDI is the primary diisocyanate used in slabstock foam
production.
Most of the TDI used in foam production is consumed
during the polymerization reactions; however, TDI has
been detected in emissions from foam production. One
study performed in Germany in 1980, commonly known
in the foam industry as the Stuttgart study, measured
TDI emissions at 0.1 pounds per ton of TDI used (28).
This amounts to about 0.04 pounds of TDI per ton of
foam produced. The Stuttgart study appears to overes-
timate emissions from today's slabstock industry in the
United States because of the vastly different production
equipment now in use.
TDI is highly toxic, producing headaches, nausea, and
vomiting at concentrations as low as 0.1 ppm and more
serious effects at higher concentrations (10). In addition,
TDI has been listed as a HAP under the Clean Air Act
Amendments.
3.3.1 Impact of Process and Formulation
Changes on Toluene Diisocyanate
Emissions
Because of the high reactivity of TDI, the bulk of emis-
sions probably originates during the early stage of the
foam reaction. Modern production methods, such as
Maxfoam and Vertifoam, have lower TDI emissions than
earlier equipment (10), probably because they have
more efficient systems for dispensing raw materials. In
addition, TDI emissions are reduced at lower TDI indi-
ces. As a result of equipment and formulation changes,
the PFA believes that emissions of TDI currently are
about 40 percent less than in the 1970s (10).
Diisocyanate emissions are also reduced when MDI is
used in place of TDI. Polymeric MDI is used in the
production of molded foam, often in mixtures with TDI.
The vapor pressure of MDI is about one-twentieth that
of TDI. As a result, the amount of MDI volatilized in the
foaming reaction is expected to be less than the amount
of TDI volatilized.
3.3.2 Add-On Controls for Toluene
Diisocyanate Emissions
Scrubbers have been installed to control TDI emissions
on a small number of commercial slabstock foam facili-
ties in Great Britain, Canada, and the United States.
Efficiencies of these systems range from 65 to 99.9 per-
cent (10). One problem with these systems is that C02
builds up in the scrubber liquor as a result of the reaction
of isocyanate with water, reducing system efficiency.
Efficiency can be improved through the use of a sacrifi-
cial prefilter made of polyurethane foam or another high
surface area material. All filtration media present a haz-
ardous waste concern, which increases the overall pol-
lution impact and affects industry economics.
3-4 Reducing Releases From Foam
Fabrication, Chemical Storage and
Handling, and Cleaning
Emissions from fabrication result from the use of
solvent-based adhesives in fabrication operations. The
solvent carrier evaporates to the air as the adhesive
dries. Section 5.1 presents information on alternative
adhesive systems that can be used to reduce emissions
from repair operations.
Sections 5.2 and 5.3 discuss methods for reducing re-
leases from chemical storage and handling, and from
solvent cleaning.
3.5 References
1. SPI. 1990. End-use market survey on the polyurethane industry
in the U.S. and Canada. New York, NY: Society of the Plastics
Industries, Polyurethanes Division.
2. Farmer, R.W., T.P. Nelson, and C.O. Reuter. 1987. Preliminary
control concepts for methylene chloride emissions from flexible
polyurethane foam manufacturing. Draft report prepared by Ra-
dian Corp., Austin, TX, for the U.S. Environmental Protection
Agency, Research Triangle Park, NC.
3. Norwood, L.P., and A. Williams. 1994. Site visit report (nonconfi-
dential version), Hickory Springs, Conover, NC. January 14.
4. Williams, A., and L.P. Norwood. 1994. Site visit report (nonconfi-
dential version), Foamex LP, Morristown, TN. January 18.
5. Williams, A., and L.P. Norwood. 1994. Site visit report (nonconfi-
dential version), Trinity American, High Point, NC. January 19.
6. Herrington, Ft., and K. Hock, eds. 1991. Flexible polyurethane
foams. Midland, Ml: Dow Chemical Company.
7. U.S. EPA/PFA. 1991. Handbook for reducing and eliminating
chlorofluorocarbons in flexible polyurethane foams, 21A-4002.
Joint project of the U.S. Environmental Protection Agency and
the Polyurethane Foam Association, Washington, DC.
8. Woods, G. 1987. The ICI polyurethanes book. New York, NY: ICI
Polyurethanes and John Wiley & Sons.
9. Norwood, L.P, A. Williams, and W. Battye. 1994. Summary of
flexible polyurethane foam information collection requests (ICRs).
Presented at a meeting of the U.S. Environmental Protection
Agency and the Polyurethane Foam Association. February 2.
10. PFA. 1993. Flexible polyurethane foam (slabstock): Assessment
of manufacturing emission issues and control technology. Wayne,
NJ: Polyurethane Foam Association.
11. CEC. 1991. Flexible polyurethane foam manufacture: An assess-
ment of emission control options. Washington, DC: Center for
Emissions Control.
12. SRRP. 1992. Source reduction and recycling of halogenated sol-
vents in the flexible foam industry. Report on research performed
by the Source Reduction Research Partnership for the Metropoli-
tan Water District of Southern California and the Environmental
Defense Fund (EOF).
13. U.S. EPA. 1995 Flexible polyurethane foam: Emission analysis.
EPA/453/D-95/004. Research Triangle Park, NC (May).
14. ARCO Chemical. 1994. Product literature. Hinsdale, IL.
15. Goldschmidt Chemical Corp. 1994. Product literature. Hopewell,
VA.
21
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16. Sam, P.O., D. Stefani, and G.F. Lunardon 1993. Anovel approach
to the production of low density, CFC-free flexible polyurethane
foams. In: Proceedings of the Society of the Plastics Industries
Polyurethanes World Conference. New York, NY: Society of the
Plastics Industries, Polyurethanes Division, pp. 305-310.
17. Skorpenske, R.G., R. Soils, S.A. Moy, E.P. Wiltz, CD. McAfee,
and K. Brunner. 1993. Novel technology for the manufacture of
all-water-blown flexible slabstock foam. In: Proceedings of the
Society of Plastic Industries Polyurethanes World Conference.
New York, NY: Society of Plastics Industries, Polyurethanes Di-
vision, pp. 66-73.
18. Stone, H., E. Reinink, S. Lichvan, W. Carlson, and C. Sikorsky.
1993. The rapid cure process: Industrial experience, engineering
and formulation principles, In: Proceedings of the Society of the
Plastic Industries Polyurethanes World Conference. New York,
NY: Society of Plastics Industries, Inc., Polyurethanes Division.
pp. 270-278.
19. Stone, H. 1992. Low density foams without auxiliary blowing
agents for use with standard foam machines. In: Proceedings of
the Polyurethane Foam Association Meeting. Wayne, NJ: Poly
urethane Foam Association. October.
20 McAfee, CD., E.P. Wiltz, R.G. Skorpenske, D.H. Ridgway, and
J.V. McClusky. 1993. Understanding the fundamentals of forced
cooling in the production of blowing agent free flexible slabstock
polyurethane foams. In: Proceedings of the Society of Plastics
Industries Polyurethanes World Conference. New York, NY: So-
ciety of Plastics Industries, Polyurethanes Division, pp. 279-287.
21. Collins, B., and C. Fawley. 1993. Cannon Enviro-Cure equipment
applied to the Vertifoam and Maxfoam processes. In: Proceed-
ings of the Society of Plastics Industries Polyurethanes World
Conference. New York, NY Society of Plastics Industries, Poly-
urethanes Division, pp. 176-1 83.
22 Ricciardi M.A., and D.G. Dai. 1992. Grain Industries Enviro-Cure
technology applied to the Vertifoam and Maxfoam processes. In:
Proceedings of the Polyurethane Foam Association Meeting.
Wayne, NJ: Polyurethane Foam Association. October.
23 Ricciardi, M.A., and D.G. Dai. 1992. Three-stage cooling of po-
rous materials. U.S. Patent No. 5,171,756.
24 Drye, J.L., and G.C. Cavenaugh. 1993. Posttreatment of polyure-
thane foam. U.S. Patent No. 5,188,792.
25 Florentini, C., et al. 1992. Auxiliary blowing agent substitution in slab-
stock foams. In: Proceedings of the Polyurethane Foam Association
Meeting. Wayne, NJ: Polyurethane Foam Association. October.
26 Spellmon, L.J. 1993. Alternative manufacturing technologies:
Variable pressure foaming. Personal communication from L.J.
Spellmon, Foamex, to B.C. Jordan, U.S. Environmental Protec-
tion Agency, Research Triangle Park, NC. October 25.
27 Carson, S. 1993. Controlled environment foaming: Manufacturing
a new generation of polyurethane foam. Prepared for the Foam
1 Company, Woodland, CA.
ss Tu, D., and R. Fetsch. 1980. Emission of air contaminating
harmful substances during the manufacture and processing of
polyurethane products. Stuttgart, Germany: University of
Stuttgart.
22
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Chapter 4
Pollution Prevention in Molded Foam Manufacture
Molded foam accounts for about 25 percent of the flex-
ible polyurethane produced in the United States (1). In
molded foam production, the foam polymerization reac-
tion occurs in a closed mold in the shape of the desired
product. The largest market for molded foam products
is the transportation industry, which uses molded foam
for seat cushions and interior trim (e.g., sound-absorb-
ing trim). Molded foam is also used in furniture, bedding,
packaging materials, toys, and novelty items.
This chapter reviews molded foam production proc-
esses, identifies and quantifies the extent of emissions
of pollutants, and describes pollution prevention options
that can be implemented to reduce these emissions.
The principle pollution prevention techniques available
for molded foam include:
• Alternative mix head technology (high pressure and
self-cleaning mix heads).
• Nonhazardous flushing agents.
• Recovery of solvent-based mix head flush.
• Alternative mold release agents (naphtha-based and
reduced-VOC mold release agents).
• Electrostatic spray guns for applying mold release
agents.
• Alternative auxiliary blowing agents (HFA-134a, pen-
tane, water blowing)
4.1 Molded Foam Production
4.1.1 Molded Foam Process Equipment
Figure 4-I illustrates a typical molded foam production
line. The production line includes multiple molds, each
consisting of top and bottom sections joined by hinges.
The molds are mounted on a circular or oval track. Both
the molds and the track can vary broadly in size. Mold
sizes range from less than a foot (e.g., for novelty items)
to several feet (e.g., for mattresses). The track can
range from a small carousel with fewer than 10 molds
to a large "racetrack" with as many as 75 to 100 molds.
The molds travel around the track, and the necessary
process operations are performed at fixed stations.
The raw material injection station is particularly impor-
tant. Raw materials, including polyol, diisocyanate,
water, catalyst, and surfactant are all pumped to a com-
mon mix head in predetermined amounts. Many of the
ingredients are premixed to minimize the streams being
fed to the head and to ensure precise measurement.
The mix head injects a precisely measured "shot" of raw
material into each mold. The industry used two types of
mix heads: high pressure and low pressure. In a high
pressure system, impingement of the high pressure
streams within the mix head mixes the raw materials.
The low pressure system relies on a rotating mixer
within the mix head to blend the raw materials.
Low and high pressure mix heads have different clean-
ing requirements that result in dramatic differences be-
tween the two mix heads in overall emissions. Low
pressure mix heads must be cleaned either after each
shot or once every several shots to prevent clogging.
Flushing with a solvent, generally methylene chloride,
cleans the mix head. The volume of solvent used in
mix-head flushing is substantial, about 440 tons nation-
wide. High pressure mix heads do not need to be
flushed and thus can be viewed as a pollution prevention
measure for mix-head flushing.
After the mix head charges the raw materials, the molds
generally are heated to accelerate foam curing reac-
tions. Heating can be accomplished by pumping hot
water through tubes in the body of the mold or by
passing the mold through a curing oven. The amount of
heating required depends on the specific process.
Other operations include the application of mold release
agent, closing and opening of the mold, removal of the
molded product, and mold cleaning. A mixture of manual
and automated equipment is used for these operations,
with the degree of automation depending on the age and
size of the production line. The following section de-
scribes a typical molding cycle.
4.12 Molding Process Cycle
The first step in the molding cycle is the application of
mold release agent, a substance applied to the mold to
facilitate removal of the foam product. The mold release
agent is typically a wax in a solvent carrier, either a
23
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Mold Closing
Curing Oven
Polyol,
Diisocyanate,
Water,
Catalyst, and
Surfactant
Raw Chemical
Dispensing
Application of Release Agent
Mold Conditioning
t
Mold Opening and Emptying
Cell Crushing
Product
Figure 4-1. Typical molded foam production line.
Foam
chlorinated solvent or a naphtha petroleum solvent. The
carrier evaporates, leaving the wax behind to prevent
sticking. Mold release agent may be applied by a spray
or a brush.
After the mold release agent is applied, any special
components to be molded into the foam are placed in
the mold; these include covers, springs, or reinforcing
materials. The mold may then be preheated prior to the
addition of raw materials to accelerate evaporation of
the solvent carrier for the release agent.
As noted above, the mix head measures and pours a
predetermined shot of raw materials into the mold. The
mold is then closed. Polymerization and the gas forming
reaction occur simultaneously, producing a foam prod-
uct that fills the mold. (Foam forming and foam blowing
reactions are discussed in detail in Chapter 2.) Most
molded foams are produced without auxiliary blowing
agents (ABAs), using only the blowing action of carb-
on dioxide (CO,) gas from the water-diisocyanate re-
action (2-6).
The mold is heated to accelerate curing reactions in the
foam polymer. After curing, the molds are opened, and
the product is removed. The mold is then cleaned and
Foam Repair
Potential
Emission Point
returned to the circuit. The entire cycle takes approxi-
mately 10 minutes.
4,1.3 Molding Process Variations
Molded foam process operations are divided into two ma-
jor categories: hot-cure processes and high resilience
(HR) processes. Hot-cure processes require higher tem-
peratures for foam curing. HR processes use higher reac-
tivity ingredients so that less external heating is needed.
HR technology is more prevalent in the United States
because of its lower energy requirements (7).
There are several ways to increase reactivity in the foam
formulation. One way is to use a higher reactivity polyol,
such as an ethylene-oxide-capped (EtO-capped) polyol
or a copolymer "graft" polyol (7). Another way to in-
crease reactivity is to use polymeric methylene diphenyl
diisocyanate (MDI) instead of toluene diisocyanate
(TDI). Higher catalyst concentrations can also be used.
An important molded foam variation is integral skin
foam, also known as self-skinning foam. Integral skin
foam is a foam with a dense, tough outer surface. The
skin is produced by overpacking the mold and using an
ABA, usually trichlorofluoromethane (CFC-11). (Unlike
24
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other types of molded foams, integral skin foams require
an ABA.) The temperature gradient between the center
of the foam mass and the relatively cooler surface of the
mold causes the ABA to condense on the mold wall,
driving skin formation. Integral skin foams are used in
such products as steering wheels and footwear (8).
4.1.4 Cell Opening
Most grades of molded foam, especially those formed
from more reactive raw materials, have closed cells
when they are initially removed from the mold. To pre-
vent shrinkage, the cells are opened by mechanical or
physical processes. At this point, CO2 and any ABA are
released to the atmosphere.
The most common method for opening the foam cells is
to "crush" the foam by passing it through a set of rollers.
Another method for opening the cells is to subject the
foam to reduced pressure in a vacuum chamber. In
some cases, cells can also be opened by timing the
release of internal pressure from the mold (7, 9).
4.1.5 Repair Operations
After a foam piece is removed from the mold and its cells
are opened, it generally is trimmed and inspected for
tears or holes, Any tears and holes are repaired. Repair
operations are carried out at glue stations, which may
be equipped with local ventilation systems to remove
solvent vapors emanating from the glue.
4.2 Overview of Releases
Table 4-I summarizes emissions from different operations
in molded foam production. The table divides emissions
into hazardous air pollutants (HAPs), which are listed
under Title III of the Clean Air Act; volatile organic com-
pounds (VOCs), which participate in reactions to form
urban smog; and chlorofluorocarbons (CFCs), which are
regulated because of stratospheric ozone depletion.
Mold release agents account for all of the known VOC
emissions and about 5 percent of HAP emissions from
molded foam production. The bulk of HAP emissions—
almost 75 percent-results from mix-head flushing, pri-
marily with methylene chloride. ABA emissions are
significant but not nearly as important as in slabstock
foam production. In molded foam production, ABA use
generally is confined to the production of integral skin
foams. The primary blowing agent has been CFC-11,
but its use has been almost completely phased out. As
a result, foam producers have been exploring a variety
of substitutes, including HAP blowing agents, VOC
blowing agents (e.g., pentane), and water blowing.
4.3 Methods for Reducing Releases
From Mix-Head Flushing
As shown in Table 4-1, about 75 percent of emissions
from molded foam production result from mix-head
flushing, with over 95 percent of these emissions from
methylene chloride.
During mix-head flushing, the flushing agent generally
is discharged through the head into an open barrel that
sits beside the mold track; emissions come from the
open barrel. One plant estimates that about 70 percent
of the methylene chloride used for mix-head flushing
evaporates. The balance of the flushing agent remaining
Table 4-1. Summary of 1992 Emissions From Molded Flexible Polyurethane Foam Production
Emissions (tons/year)
Emission Source
Mix head flushing
ABA use
Mold release and demolding
Repair and fabrication
Chemical handling and storage
Other"
Total
HAPs8
440a
NAb
21 a
58a
43a
17a
579a
VOCs CFCs
NA
NAb 60b
10,000°
NA
NA
NA
NA 60b
Comments
HAP emission breakdown is 95% methylene chloride,
3% methanol, and 2% TCA
CFC-11b
VOC emissions are mainly naphtha solvents; HAP
emissions are mainly methylene chloride
HAP emissions are 96% methyl chloroform
NA = not available
a Estimates are derived from a HAP emission survey of the flexible polyurethane foam industry by EPA/ESD (10). Plants included in the survey
accounted for about 46 percent of molded foam production (1). Results have been scaled to cover the balance of the industry.
b CFC-11, used as a blowing agent for integral skin foams, is being phased out under the Montreal Protocol. Producers are exploring various
avenues for replacing CFCs in integral skin foams, including VOC blowing agents, HAP blowing agents, and water-blowing; although HAPs
are likely to be regulated, they are not currently being phased out.
c Based on a survey of mold release agent use, which measured emissions at about 29,000 tons for rigid and flexible molded polyurethane
foams (11). This combined figure was apportioned using production data to derive an emissions estimate for flexible molded foams.
Includes in-mold product coating and equipment cleaning.
25
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in the barrel is ultimately covered and shipped off for
treatment as a hazardous waste.
Several technologies are available to reduce or elimi-
nate methylene chloride emissions from mix head
flushing. These include high-pressure mix heads, self-
cleaning mix heads, nonhazardous flushing agents, and
solvent recovery.
4.3.1 High Pressure Mix Heads
High pressure mix heads do not require flushing be-
cause they contain no moving parts. Rather, the mix
heads are designed so that the various inlet streams mix
together when they impinge on one another at high
pressure. Thus, replacing a low pressure mix head with
a high pressure system can eliminate emissions from
mix-head flushing. For an existing molded foam line,
replacing a low pressure mix head with a high pressure
system would also require that metering pumps and
controls be replaced.
High pressure systems have already replaced low pres-
sure mix heads in many molded foam plants. These
systems cannot be used for all applications, however.
For instance, the flow rate for high pressure systems is
too high to produce small items. The cost of installing a
high pressure mix head and ancillary equipment ranges
from $75,000 to $200,000, depending on the size and
throughput of the process line (12).
Four manufacturers of high pressure mixing equipment
have been identified: Krauss Maffei Corporation of
Florence, Kentucky; Cannon USA of Mars, Pennsylva-
nia; Hennecke Machinery of Lawrence, Pennsylvania;
and Admiral Corporation of Akron, Ohio.
4.3.2 Self-Cleaning Mix Heads
Another alternative to mix-head flushing is a self-cleaning
mix head, which uses a tapered mixing screw in a
tapered chamber. The screw rotates rapidly to mix the
raw materials. For cleaning, the screw is rotated at a
faster rate to expel residues from the mixing chamber (13).
This technology is only applicable for molded foam lines
that manufacture small parts. The throughput for the
head ranges from 2 to 16 pounds per minute.' The cost
of retrofitting a self-cleaning mix head to an existing
process line has been estimated at $30,000 (12).2 The
system is sold in the United States by Klockner Ferro-
matik Desma of Erlanger, Kentucky.
1 Lewis, G.D. 1995 Personal communication from George D. Lewis,
Klockner Ferromatik Desma, to David Svendsgaard, U.S. Environ-
mental Protection Agency. January 5.
2 See footnote 1, above.
4.3.3 Nonhazardous Flushing Agents
Substitution of a nonhazardous flushing agent also re-
duces release of methylene chloride from mix-head
flushing. Several alternative flushing agents are avail-
able, many of which are nonvolatile as well as non-HAP
For example, polyol can be used, or any of the nonhaz-
ardous flushing agents based on d-limonene, cyclic am-
ide, ethyl ester, glutarate ester, and other esters.
In general, alternative flushing agents are more expen-
sive than methylene chloride. In drum quantity,
methylene chloride costs about $3.20 per gallon, while
costs of nonhazardous flushes range from $7 to $25 per
gallon (12). These fluxes can be used multiple times,
however, and higher purchase costs are also counter-
balanced by a savings in disposal costs. In addition,
the cost of flushing agents can be reduced substantially
by distilling and reusing the flushing agent.3 Spent
methylene chloride flushing agent must be treated as a
hazardous waste under the Resource Conservation and
Recovery Act (RCRA), while the nonhazardous solvent
residues can be treated simply as solid wastes,
Nonhazardous flushing agents are available from many
vendors. In selecting a flushing agent, the user must
check the solvent's performance with seals and o-rings.
The U.S. Environmental Protection Agency (EPA) and
other federal agencies have developed a number of
electronic databases to assist solvent users in identify-
ing nonhazardous substitutes. These are discussed in
Appendix B.
4.3.4 Solvent Recovery
As noted above, the mix head flush stream is generally
captured in a barrel located near the mold track. Overall
release of methylene chloride from mix-head flushing
can be reduced by immediately reclaiming the spent
flushing agent; this is done by distilling the methylene
chloride at 200°F to 250°F. Solvent vapors are con-
densed and reused. Solids from the still (still bottoms)
remain a hazardous waste, but the waste volume is
greatly reduced by recovering the solvent. Still bottoms
can be either landfilled or incinerated.
The reclaiming operation can occur either on site or at
a separate facility. Many companies contract to collect
drums of spent solvent, distill the contents, and return
reclaimed solvent to the client company. Generally, this
recovery operation can be performed with no sacrifice
in product quality.
Esemplare, P. 1995. Personal communication from Pat Esemplare,
Dynaloy, Inc., to Amanda Williams, EC/R, Inc. January 17.
26
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4.3.5 Comparison and Cost Information for
Measures To Reduce Mix Head
Flushing Emissions
Table 4-2 summarizes available cost data for the vari-
ous technologies that reduce releases from mix-head
flushing. The table gives capital costs and estimated
cost-effectiveness values. Cost-effectiveness is given in
terms of dollars per ton of emissions reduced and is
defined as the total annual operating cost divided by the
magnitude of the projected reduction in emissions or
total releases.
Table 4-2. Summary of Costs To Reduce Mix-Head Flushing
Release
Technology
High-pressure mix
heads
Self-cleaning mix
heads
Nonhazardous
flushing agents
Reclaiming of spent
flushing agents
Total Capital
Investment
per Molded
Foam Line ($)
75,000-
200,000a
-40,000a
0
9,000b
Estimated Cost
Effectiveness
($/ton of pollutant
reduction)'
773
(502)
(79)
(177)
( ) = overall savings (due to reduced chemical costs).
aU.S. EPA (12).
b SRRP (2).
4.4 Methods for Reducing Releases of
Mold Release Agents
1 ,1 ,1-Trichloroethane (TCA) and methylene chloride
have been widely used as mold release agent carriers.
Because both of these solvents have been listed as
HAPs under Title III of the Clean Air Act Amendments,
molded foam manufacturers recently have been select-
ing nonhazardous carriers. Some of these are naphtha-
based, reduced-VOC, or water-based carriers.
4.4.1 Naphtha-Based Mold Release Agents
Naphtha is a petroleum distillate consisting mainly of
aliphatic hydrocarbons. These hydrocarbons evaporate
during the molding process the same way the chlorin-
ated mold release carriers do.
Naphtha-based carriers contain no HAPs. Neverthe-
less, they consist of reactive VOCs, which participate in
the formation of photochemical smog. Thus, the use of
naphtha-based mold release agents reduces HAP emis-
sions but not VOC emissions.
4.4.2 Reduced-VOC Mold Release Agents
Reduced-VOC mold release agents are high-solids,
solvent-based formulations (14). Because of their
higher solids content, less solvent carrier is required
per mold cycle. This can reduce VOC emissions as
much as 80 percent.
The cost of a typical reduced-VOC mold release agent
is $9.31 per gallon, about twice the cost per gallon of a
standard solvent-based mold release agent. This cost
is partially offset, however, because the reduced-VOC
agent can be used in smaller quantities. No equipment
changes are necessary, and no significant operator re-
training is necessary to use these formulations (12).
4.4.3 Water-Based Mold Release Agents
Concerns over emissions from HAP-based and naphtha-
based mold release agents have prompted the develop-
ment of some water-based mold release agents (15),
which have been used successfully at molded foam
production plants. Unlike naphtha-based and reduced-
VOC mold release agents, water-based agents elimi-
nate mold release emissions (16, 17).
The cost of the typical water-based mold release agent
is $5 to $6 per gallon.4 This is about 5 to 30 percent more
than the cost of a solvent-based agent. In addition,
several factors complicate the use of water-based mold
release agents. First, the selection of a water-based
agent is specific to each particular application. Consid-
erable time and many trials may be needed before the
correct product and temperature are found. Second,
mold release spray machine operators may require
some retraining. Finally, additional drying time may be
needed for the mold release agent, or the temperature
of the mold may have to be increased to speed drying.
4.4.4 Electrostatic Spray Guns
Electrostatic spray guns have recently been developed
for painting and other surface coating operations. These
are designed to reduce coating consumption by reduc-
ing the amount of "overspray," or coating that does not
adhere to the target surface. In reducing overspray,
these systems also reduce solvent consumption, and
hence emissions. Electrostatic spray systems have
been used in the foam industry to apply mold release
agents, reducing solvent emissions by 20 percent.
4.4.5 Comparison and Cost information for
Measures To Reduce Mold Release
Agent Emissions
Table 4-3 summarizes available cost data for the various
technologies that reduce emissions from mold release
agents. The table gives capital costs and estimated
cost-effectiveness values in terms of dollars per ton of
emissions reduced.
4 Santo, R. 1995. Personal communication from Robert Santo, Air
Products and Chemicals, to David Svendsgaard, U.S. Environmental
Protection Agency. January 16.
27
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Table 4-3. Summary of Costs To Reduce Emissions From
Mold Release Agents (12)
Technology
Total Captlal
Investment
per Molded
Foam Line ($)
Estimated Cost
Effectiveness
($/ton of pollutant
reduction)
Naphtha-based release
agents
Reduced-VOC release
agents
Water-based release
agents
Alternative application
methods
0
NA
3,359
452
433
NA
NA = not available
4.5
Methods for Reducing or Mitigating
Releases of Auxiliary Blowing Agents
Although ABA use has been phased out in the manufac-
ture of most molded foam, ABAs are still generally used
to manufacture integral skin foams. The primary ABA
historically used in this process was CFC-11. As a result,
foam manufacturers have put considerable effort into
finding a substitute. Methylene chloride, which has re-
placed CFC-11 in most slabstock ABA applications, has
not proved adequate for integral skin foam production.
BASF has recently been researching CFC-11 substitutes
for integral foam processes. Three substitutes have been
explored: HFA-134a (1,1 ,1,2-tetrafluoroethane), pen-
tane, and water blowing. All three substitutes have pro-
duced integral foams of acceptable quality (18). The
following subsections discuss specific requirements and
the effects of these substitutions.
4.5.1 HFA- 134a
HFA-134a contains no chlorine and therefore is not
believed to participate in stratospheric ozone depletion
reactions. Therefore, unlike other CFC substitutes such
as hydrochlorofluorocarbons (HCFCs), HFA-134a prob-
ably will not be regulated by future updates of the Mont-
real Protocol.
The main disadvantage of HFA-134a is its cost com-
pared with other blowing agents. In addition, HFA-134a
has a low boiling point and is not as soluble as CFC-11
in polyurethane systems; therefore, HFA-134a use re-
quires special processing.
4.5.2 Pentane
Pentane is not an ozone-depleting agent; it is a VOC,
however. Therefore, substituting pentane for CFC-11
decreases emissions of ozone-depleting compounds
while increasing emissions of VOCs.
4.5.3 Water Blowing
Historically, manufacturers have not had success in pro-
ducing integral skin foams with water-blown systems.
Skin formation is driven by condensation of the blowing
agent on the mold wall, and this condensation does not
occur with CO2. In addition, the urea linkages formed in
the water-isocyanate reaction are detrimental to the
physical properties of the foam core.
BASF overcame both of these problems by using addi-
tives in the formulation (16). Microcellular thermoplastic
beads were added to enhance skin definition. In addi-
tion, a prepolymer additive was used to counteract the
impact of urea linkages.
4.6 Methods for Reducing Releases
From Foam Repair, Chemical
Storage and Handling, and Cleaning
Processes
Emissions from foam repair operations result from the
use of solvent-based adhesives. The solvent carrier
evaporates to the air as the adhesive dries. Section 5-I
presents information on alternative adhesive systems
that can be used to reduce emissions from repair opera-
tions.
Sections 5-2 and 5-3 discuss methods for reducing
releases from both chemical storage and handling and
from solvent cleaning.
4.7 References
1. SPI. 1990. End-use market survey on the polyurethane industry
in the U.S. and Canada. New York, NY: Society of the Plastics
Industries, Polyurethanes Division.
2. SRRP. 1992. Source reduction and recycling of halogenated sol-
vents in the flexible foam industry. Report on research performed
by the Source Reduction Research Partnership for the Metropoli-
tan Water District of Southern California and the Environmental
Defense Fund (EOF).
3. Hayashida, S., A. Horie, Y. Yamagucki, and H. Morita. 1989.
Polyol for CFC-free hot molded foam using high mold tempera-
ture process. In: Proceedings of the Society of the Plastics In-
dustries Annual Polyurethanes World Conference. New York, NY:
Society of the Plastics Industries, Polyurethanes Division, pp.
575-578.
4. Motte, P. 1989. CFC-free flexible molded foams with improved
physical properties. In: Proceedings of the Society of the Plastics
Industries Annual Polyurethanes World Conference. New York,
NY: Society of the Plastics Industries, Polyurethanes Division, pp.
2-8.
5. Westfall, P.M. and J.L. Lambach. 1989. Hyperlite: High perform-
ance low density molded foam technology without CFCs. In: Pro-
ceedings of the Society of the Plastics Industries Annual
Polyurethanes World Conference. New York, NY: Society of the
Plastics Industries, Polyurethanes Division, pp. 9-I 5.
6. Lunardon, G.F., B. Gallo, and M. Brocci. 1989. Production of soft
block foams and TDI-based cold cure-molded foams with no use
of CFCs. In: Proceedings of the Society of the Plastics Industries
Annual Polyurethanes World Conference. New York, NY: Society
of the Plastics Industries, Polyurethanes Division, pp. 239-245.
28
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7. Herrington, R. and K. Hock, eds. 1991. Flexible polyurethane
foams. Midland, Ml: Dow Chemical Company.
a. Woods, G. 1987. The ICI polyurethanes book. New York, NY: ICI
Polyurethanes and John Wiley & Sons.
9. Cavender, K.D. 1985. Novel cell opening technology for HR
molded foam. In: Proceedings of the Society of the Plastics In-
dustries 28th Annual Technical/Marketing Conference. New York,
NY: Society of the Plastics Industries, Polyurethanes Division.
pp. 314-318.
10. Norwood, L.P., A. Williams, and W. Battye. 1994. Summary of
flexible polyurethane foam information collection requests (ICRs).
Presented at a meeting of the US. Environmental Protection
Agency and the Polyurethane Foam Association. February 2.
11. Whitfield. K. 1994. Some characterization and emissions esti-
mates for mold release agents and roofing applications. Prepared
by Southern Research institute for the U.S. Environmental Pro-
tection Agency, Research Triangle Park, NC.
12. U.S. EPA. 1995. Flexible polyurethane foam: Emission reduction
technologies cost analysis. EPA/453/D-95/004. Research Triangle
Park, NC (May).
13. Lewis, G.D. 1993. Solvent free mechanical mixing. In: Proceed-
ings of the Society of the Plastics Industries Annual Polyure-
thanes World Conference. New York, NY: Society of the Plastics
Industries, Polyurethanes Division, pp. 171-175.
14. Air Products. 1994. PURA sprayable concentrate release agents.
Polyurethane Additives Product Bulletin.
15. Fountas, G.N. 1990. Water-based release agents offer solution
to processors' CFC problems. Elastomerics. December.
16. Air Products. 1994. PURA water-based release agents. Polyure-
thane Additives Product Bulletin.
17. Chem-Trend, Inc. 1994. RCTW-1151, release blend in water,
Material Safety Data Sheet.
18. Valoppi, V.L., R.P. Harrison, and C.J. Reichel. 1993. Non-ozone
blowing agents for integral skin foam. In: Proceedings of the
Society of the Plastics Industries Annual Polyurethanes World
Conference. New York, NY: Society of the Plastics Industries,
Polyurethanes Division, pp. 420-424.
29
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Chapter 5
Pollution Prevention in Adhesive Usage, Chemical Storage and Handling,
and Equipment Cleaning
This chapter discusses methods for reducing emissions
from operations that are common to both slabstock and
molded foam production. These operations include
adhesives application (Section 5.1), chemical storage
and cleaning (Section 5.2), and equipment cleaning
(Section 5.3).
5.1 Reducing Emissions From
Adhesives
Adhesives are used in both slabstock and molded foam
plants. In slabstock facilities, adhesives are used in
fabrication operations to glue foam pieces to one an-
other and to other materials. In molded foam plants,
adhesives are used primarily to repair pieces that are
found to be damaged when they are removed from the
mold.
Adhesives used in the foam industry are mainly solvent-
based systems, with about 20 to 40 percent solids. The
bulk of the solvent carrier evaporates as the adhesive
dries. Adhesives generally are applied at gluing stations
by spraying with low pressure guns. At larger facilities,
glue stations are equipped with local ventilation systems
to remove solvent vapors.
Until 1993, 1,1,1-trichloroethane (TCA) was the most
prevalent solvent used in foam adhesives, accounting
for more than 90 percent of adhesive solvent use.
Methylene chloride accounted for most of the remaining
10 percent. Total adhesive solvent emissions from foam
fabrication were estimated at about 1,400 tons per year
in 1993 (see Tables 3-I and 4-I). Adhesives suppliers,
however, have moved strongly to methylene chloride in
1994.
TCA use is being phased out under the Montreal Proto-
col for stratospheric ozone-depleting agents. In addition,
because TCA, methylene chloride, and other adhesive
solvents have been listed as hazardous air pollutants
(HAPs) under Title III of the Clean Air Act Amendments,
adhesive manufacturers have been working to develop
alternatives to solvent-based systems. Three of these
alternatives are discussed in the following sections.
5.1.1 Hot-Melt Adhesives
Hot-melt adhesives are solids that can be melted and
sprayed like solvent-based adhesives. Hot-melt adhe-
sives contain no HAPs; however, small amounts of low
molecular-weight hydrocarbons may be emitted when
the adhesive is melted. These volatile organic com-
pounds (VOCs) can participate in the formation of urban
smog.
Major equipment changes are not necessary for a switch
to hot-melt adhesives; the main change is the addition
of a melt tank at a cost of under $7,000. New spray guns
and heated lines are also needed, which increase the
cost of this approach. Hot-melt adhesives, however, are
considerably more expensive than solvent-based adhe-
sives. A typical hot melt adhesive costs about $20.30 per
gallon, compared with about $8.50 per gallon for a
TCA-based adhesive (1).
Operational hurdles are also associated with hot-melt
adhesives. First, hot adhesives may present a burn
hazard to glue station workers. Second, the "tack time"
of hot-melt adhesives is very short. This is both an
advantage and a disadvantage; although it allows faster
production cycles, the adhesive may cease to be sticky
before the assembly is complete. Tack time depends on
the adhesive used, and adhesives with extended tack
times can be obtained from some manufacturers. Some
trials may be needed, however, before the most appro-
priate product is identified for a specific application. An
additional problem noted with hot-melt adhesives is that
they tend to produce hard seams, which is unacceptable
in a soft, flexible foam product.
5.1.2 Water-Based Adhesives
Some water-based adhesives are available that contain
no HAPs or VOCs (2). Thus, substituting water-based
adhesives for solvent-based systems can eliminate both
HAP and VOC emissions from adhesive solvents.
Water-based system substitution requires little modifica-
tion to existing spray equipment. The cost of water-
based adhesives is actually somewhat lower than the
cost of solvent-based adhesives (about $7 per gallon).
31
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A major drawback to water-based systems is their
slower drying time, which makes water-based systems
impractical for some applications. In some cases, an
external heat source is required to accelerate drying.
The tack time of water-based adhesives can also be a
problem in the fabrication process. A higher volume of
water-based adhesive is generally needed to achieve
the glue capability of a solvent-based adhesive, which
effects any economic comparison.
Water-based adhesives are available from many ven-
dors The US. Environmental Protection Agency (EPA)
and other federal agencies have developed a number of
electronic databases to assist solvent users in identify-
ing nonhazardous and water-based substitutes. These
are discussed in Appendix B.
5.1.3 Two-Component Water-Based
Adhesives
There is a water-based adhesive variation that involves
a two-component system: a water-based latex adhesive
and a mild citric acid solution (3). These components are
mixed when the adhesive is sprayed, causing the latex
to coagulate. The adhesive dries almost instantly, and
cleans up with soap and water. In addition, little adhe-
sive penetrates into the surfaces being joined.
The cost of a two-component water-based adhesive is
about $8 per gallon, slightly less than a TCA-based
adhesive (1). Special spray guns are needed, however,
for the two-component water-based process at a cost of
about $2,000 to $3,000 per glue station. In addition,
operators may need training in the use of the two-com-
ponent system. There are also some limitations on the
products to which the adhesive can be applied, in that
both of the surfaces being joined must be porous.
5.14 Costs for Alternative Adhesives
Table 5-1 summarizes available cost data for the various
technologies that reduce emissions from adhesive us-
age in the foam industry. The table provides capital costs
and estimated cost-effectiveness values. Cost-effective-
ness is presented in terms of dollars per ton of emis-
sions reduced and is defined as the total annual
operating cost divided by the magnitude of the projected
reduction in emissions or total releases.
5.2 Reducing Releases From Chemical
Storage and Handling
In general, the larger-volume raw materials are received
by either rail car or tank truck and are stored in fixed-roof
tanks. These include toluene diisocyanate (TDi), poiyoi,
and methylene chloride. Smaller-volume ingredients
typically are received and stored in drums or totes.
Table 5-1. Summary of Costs of Alternative Adhesive
Systems (1)
Technology
Hot-melt
adhesives
Water-base
adhesives
Two-component
water-based
adhesives
Total
Captial
Investment
per Glue
Station ($)
3,000
Negligible
2,000-3,000
Estimated
Effectiveness
Cost
($/ton of
pollutant reduction)
Slab-stock
Plant
2,264
(365)
200
Molded
Plant
3,217
(380)
900
( ) = overall savings (due to reduce chemical costs).
Special precautions generally are taken in the handling
of TDI because of its toxicity and reactivity with water.
Generally, TDI is unloaded to storage tanks using a
vapor-balanced system; that is, the vapors displaced by
liquid flowing into the empty storage tank are piped back
to the rail car or tank truck. This eliminates "working
loss" emissions from the storage tank.
Measures may also be taken to mitigate the impact of
tank "breathing," which occurs when the tank contents
expand and contract with diurnal temperature changes.
TDI tanks are often located indoors (although they are
vented outdoors) to reduce diurnal temperature
changes. The tank vents generally are equipped with
either a carbon filter or an oil trap to prevent water vapor
from entering the tank as it breathes. If a carbon filter is
used, adsorption on the carbon also controls breathing
losses of TDI vapor.
5.3 Reducing Releases From Equipment
Cleaning
Small amounts of methylene chloride and other solvents
are used as cleaners at flexible foam plants. The sol-
vents are used to rinse or soak equipment such as mix
heads, hoses, and foam troughs. Generally, much of the
solvent that is used to clean equipment ultimately
evaporates and is therefore emitted to the atmosphere.
Any spent methylene chloride that is collected must be
disposed of as hazardous waste under the Resource
Conservation and Recovery Act (RCRA).
Three alternatives were identified to reduce or mitigate
emissions and hazardous waste generation from sol-
vent equipment cleaning: steam cleaning, substitution of
nonhazardous solvents, and solvent recovery.
5.3.1 Steam Cleaning
Some slabstock foam plants use steam to flush and
clean hoses, mix heads, and other foam-pouring equip-
ment. Steam eliminates emissions from the evaporation
of cleaning solvents. One potential problem with this
32
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control measure is the potential burn hazard it presents
for workers using the steam system. In addition, gener-
ating the steam increases energy requirements. Resid-
ual water could be a problem because it is an integral
part of foam chemistry and could cause major and dra-
matic effects.
The cost of steam cleaning depends on the source of
steam. In many cases, other operations at the plant may
supply a ready source of low pressure steam. Alterna-
tively, gas-fire mobile steam generators can be used.
The initial cost of these units has been estimated at
$3,000 to $5,000(1).
5.3.2 Solvent Substitution
Substituting a nonhazardous solvent can also mitigate
releases of methylene chloride and other HAPs from
equipment cleaning. Several nonhazardous cleaning
solvents can be used for foam equipment and are based
on d-limonene, cyclic amide, ethyl ester, glutarate ester,
and other esters. While they eliminate HAP emissions,
these solvent substitutes still contain VOCs. They have
lower evaporation rates than methylene chloride, how-
ever, and they can be reclaimed and reused.
In general, the alternative solvents are more expensive
than methylene chloride. In drum quantities, methylene
chloride costs about $3.20 per gallon, while costs for
nonhazardous solvents range from $6 to $25 per gallon
(1). The nonhazardous solvents, however, can be
reused up to three times (1). Higher purchase costs are
also partially balanced by a savings in disposal costs,
because the spent solvent materials can be treated as
simple solid wastes rather than hazardous wastes.
Vendors of nonhazardous urethane solvents include Dy-
naloy of Hanover, New Jersey (Dynaflush); Huron Tech-
nologies of Ann Arbor, Michigan; Urethane Technologies
of Santa Ana, California; Florida Chemical of Lake Al-
fred, Florida; and ISP of Wayne, New Jersey (Foam
Flush).
5.3.3 Solvent Recovery
Another method of reducing both the emissions and the
wastes that solvent cleaning operations produce is to
collect and reclaim used solvents. The reclaiming opera-
tion typically involves distillation of the spent solvent.
Solvent vapors are condensed and reused, and still
bottoms can either be landfilled or incinerated. The re-
claiming operation can be performed on site, or many
companies contract to collect drums of spent solvent,
distill the contents, and return reclaimed solvent to the
client company.
The capital cost of a batch still to recover solvents at a
foam plant has been estimated at about $9,000 (4).
Once purchased, the unit is expected to produce a cost
savings (taking into account capital recovery costs) by
reducing fresh solvent and waste disposal costs (4).
5.4 References
1. U.S. EPA., 1995. Flexible polyurethane foam: Emission reduction
technologies cost analysis. EPA/453/D-95/004. Research Triangle
Park, NC (May).
2. Mid-West Industrial Chemical Co. 1993. 13-124-4 latex adhesive:
Material safety data sheet. St. Louis, MO.
3. H.B. Fuller Co. 1994. Technical data sheet: Product N. WC-0686-
A-770, two component water-based adhesive. St. Paul, MN.
4. SRRP. 1992. Source reduction and recycling of halogenated sol-
vents in the flexible foam industry. Report on research performed
by the Source Reduction Research Partnership for the Metropoli-
tan Water District of Southern California and the Environmental
Defense Fund (EOF).
33
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Appendix A
Pollution Prevention Worksheets for Polyurethane Foam Manufacturing
35
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IFirm
Site
Date
Pollution Prevention Assessment
Proj. No.
Prepared by
Checked by
Sheet of Page
of
WORKSHEET
1
POLLUTION PREVENTION
Blowing Agent -
Emission Factor Calculation
STEP 1: CALCULATION OF TOTAL WEIGHT PER HUNDRED PARTS POLYOL
Ingredient
Polyo!
Isocyanate
Water
Auxiliary blowing agent
Cross-linking agents,
chain modifiers, and
other additives
Catalysts and
surfactants
Others
TOTAL WEIGHT PER
100 PARTS POLYOL
Amount used
(pphp)
100
Auxiliary blowing agent
(pphp)
Total weight per
100 parts polyol
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Product
weight
factor
-1.44
0
STEP 2: CALCULATION OF EMISSION FACTORS
2,000
Ib/ton
2,000
Product weight
contribution
100
Pounds of ABA emitted
per ton of foam
Auxiliary blowing agent
(pphp)
Total weight per
100 parts polyol
X
Density
(Ib/ft3)
Pounds of ABA emitted
per cubic foot
pphp = parts per hundred parts polyol
36
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:jrm Pollution Prevention Assessment Prepared by I
Site Checked by
Date Proj. No. Sheet of Paae of
WORKSHEET POLLUTION PREVENTION
2 Blowing Agent -
Worksheet for Calculating
Formulation Costs for Pollution
Prevention Options
| CURRENT FORMULATION ,
Ingredient
Amount cost cost
used {$/ (WOO Ib
Ingredient (pphp) Ib) polyol)
Polyol 100x
Isocyanate x =
Water x
ABA x
Others x =
x =
x =
x =
x =
TOTALS
Ingre- cost
dients
total
Total Foam
ingredients - ABA - Water x Con- = produced
(pphp) (pphp) (pphp) stant (pphp)
- ( x ) =
cost Foam
($/1 00 Ib •*• produced •+• Density = cost
polyol) (pphp) (Ib/ft3) ($/ft3)
— -i- =
ALTERNATE FORMULATION }
Ingredient
Amount cost cost
used ($/ ($/100 Ib
Ingredient (pphp) Ib) polyol)
Polyol 100x
Isocyanate x =
Water X
ABA X
Others X
x =
x =
x =
x =
TOTALS
Ingre- Cost total
dients
total
Total Foam
ingredients - ABA - Water x Con- = produced
(pphp) (pphp) (pphp) stant (pphp)
- ( x | =
cost Foam
($/100 Ib •+• produced •+• Density = cost
polyol) (pphp) (Ib/ft3) ($/ft3)
pphp = parts per hundred parts polyol
37
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Firm
Site
Date
Pollution Prevention Assessment
Proj. No.
Prepared by
Checked by
Sheet of Page
of
WORKSHEET
3a
OPTION GENERATION
Slabstock Production
Meeting Format
Meeting Coordinator
Meeting Participants
Suggested Pollution Prevention Option
Currently
Done Y/N?
Rationale/Remarks on Option
Auxiliary Blowing Agents
Formulation changes to reduce ABAs
Foam softeners to reduce water foam effects
Mechanical cooling technology
Liquid C02 blowing
Reduced pressure foaming
Add-on controls
Alternative nonhazardous ABAs
Adhesives
Hot melt adhesives
Water-based adhesives
Hydrofuse
Equipment Cleaning
Steam cleaning
Nonhazardous solvent substitution
Solvent recovery
38
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Firm
Site
Date
Pollution Prevention Assessment
Proj. No.
Prepared By
Checked By
Sheet of Page
of
WORKSHEET
3b
OPTION GENERATION
Molded Foam Production
Meeting Format
Meeting Coordinator
Meeting Participants
Suggested Pollution Prevention Option
Currently
Done Y/N?
Rationale/Remarks on Option
Mix Head Flushing
High-pressure mix head
Self-cleaning mix head
Nonhazardous flushing agents
Reduced pressure foaming
Solvent recovery
Mold Release Agents
Water-based agents
Electrostatic spray guns
Reduced VOC agents
Nonhazardous agents
CFC ABAs
'Water blowing
Hydrofluorocarbons
Pentane
.Adhesives
Hot melt adhesives
Water-based adhesives
Hydrofuse
Equipment Cleaning
Steam cleaning
Nonhazardous solvent substitution
Solvent recovery
39
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Appendix B
Further Information
Trade Associations
Polyurethane Foam Association
P.O. Box 1459
Wayne, NJ 07474-I 459
(201)633-9044
The Society of the Plastics Industries
Polyurethane Division
355 Lexington Avenue
New York, NY 10017
(212) 351-5425
Publications
Slabstock Foam
CEC. 1991. Flexible polyurethane foam manufacture—
An assessment of emission control options. Washing-
ton, DC: Center for Emissions Control.
U.S. EPA/PFA. 1991. Handbook for reducing and elimi-
nating chlorofluorocarbons in flexible polyurethane
foams, 21A-4002. A joint project of the U.S. Environ-
mental Protection Agency and the Polyurethane Foam
Association, Washington, DC.
Herrington, R., and K. Hock, eds. 1991. Flexible polyure-
thane foams. Midland, Ml: The Dow Chemical Company.
Polyurethane industry directory and buyer's guide.
1994. Saco, ME: Larson Publishing.
PFA. 1993. Flexible polyurethane foam (slabstock)—As-
sessment of manufacturing emission issues and control
technology. Wayne, NJ: Polyurethane Foam Association.
PFA. 1992, 1993, 1994. Proceedings of the Technical
Program. Wayne, NJ: Polyurethane Foam Association.
May and October.
SPI. Annual. Proceedings of the SPI Polyurethanes
World Conference. The Society of the Plastics Indus-
tries, Polyurethanes Division.
SRRP, 1992. Source reduction and recycling of halogen-
ated solvents in the flexible foam Industry. A report on
research performed by the Source Reduction Research
Partnership for the Metropolitan Water District of Southern
California and the Environmental Defense Fund (EDF).
Urethanes Technology (journal). Akron, OH: Grain Com-
munications, Ltd. (216) 836-9180.
Woods, G. 1987. The ICI polyurethanes book. New
York, NY: ICI Polyurethanes and John Wiley & Sons.
Pollution Prevention-General
U.S. EPA. 1993. A primer for financial analysis of pollu-
tion prevention projects. EPA/600/R-93/059.*
Adhesives
Source Reduction Research Partnership (SRRP).
Source reduction and recycling of halogenated solvents
in the adhesives industry-Technical support document.
Equipment Cleaning
U.S. EPA. 1993. Alternatives to chlorinated solvents for
cleaning and degreasing. EPA/625/R-93/016.*
U.S. EPA. 1993. Cleaning and degreasing process
changes. EPA/625/R-93/017.*
Source Reduction Research Partnership (SRRP).
Source reduction and recycling of halogenated solvents
in parts cleaning-Technical support document.
Add-On Controls
U.S. EPA. 1991. Control technologies for hazardous air
pollutants. EPA/625/6-91/014.*
On-Line and Off-Line Computer-Based
Technical Assistance
Reluctance to switch over to a new cleaning technology
may stem from concern over cleaning performance, as
well as from uncertainty in choosing an alternative from
the large number of cleaning technologies and products
now available. Users may be intimidated by the list of
options and wonder how to begin selecting an alterna-
tive. Although trade journals provide technical literature
* Available from the EPA Office of Research and Development Publi-
cations, National Risk Management Research Laboratory, Center for
Environmental Research Information, 26 W. Martin Luther King Dr.,
Cincinnati, OH 45268; (513) 569-7562.
41
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on alternative cleaning technologies, the subject may
not be presented in a systematic form that facilitates
making detailed comparisons among ail the different
attributes. To assist in making knowledgeable decisions,
several online and offline computer databases are avail-
able that provide information searching in various ways.
ATTIC
The ATTIC network is maintained by the Technical Sup-
port Branch of EPA's Risk Reduction Engineering Labo-
ratory (RREL). This network has four online databases
that can be searched by external users.
• The ATTIC database contains abstracts and bibliog-
raphic citations to technical reports, bulletins, and
other publications produced by EPA, other federal
and state agencies, and industry dealing with tech-
nologies for treatment of hazardous wastes. Perform-
ance and cost data, quality assurance information,
and a contact name and phone number are given for
the technologies.
• The Risk Reduction Engineering Laboratory (RREL)
Treatability Database provides information about con-
taminants physicochemical properties, environmental
data, treatment technologies, contaminant concentra-
tion, media or matrix, performance, and quality as-
surance.
• The Technical Assistance Directory lists experts from
government, universities, and consulting firms who
can provide guidance on technical issues or policy
questions.
• A Calendar of Events list provides information on
conferences, seminars, and workshops on treatment
of hazardous wastes. International as well as U.S.
events are covered.
There is no charge for the ATTIC service. It is available
via modem over standard telephone lines. The phone
number for the ATTIC modem contact is (301) 670-3808
(300-2400 baud), and the modem settings are no parity,
8 data bits, 1 stop bit, and full duplex. The user's manual
also is available from EPA.
PIES
PIES is a bulletin board system that links to several
databases and provides massaging capabilities and
forums on various topics related to pollution preven-
tion. Through its link to the United Nation's Interna-
tional Cleaner Production Information Clearinghouse,
it provides a communication link with international
users. PIES is part of the Pollution Prevention Infor-
mation Center (PPIC), which is supported by EPA's
Off ice of Environmental Engineering and Technology
Demonstration and Office of Pollution Prevention and Tox-
ics. PIES contains information about the following topics:
• Current events and recent publications relating to pol-
lution prevention
• Summaries of federal, state, and corporate pollution
prevention programs
• Case studies and general publications.
Searches can be performed by keywords related to
specific contaminants, pollution prevention technolo-
gies, or industries. The phone number for dial-up access
is (703) 506-1025; qualified state and local officials can
obtain a toll-free number by calling the PPIC at (703)
821-4800. Modem settings are 2400 baud, no parity, 8
data bits, 1 stop bit, and full duplex.,
SAGE
SAGE has a question-and-answer format that lets the
user input basic cleaning parameters about the parts to
be cleaned and about the desired process outcome.*
The user-provided information is then applied, internally,
to the SAGE database, which derives recommendations
for chemical and process alternatives. Based on the
information given, the alternatives are assigned a rela-
tive score that allows them to be compared. A brief
summary of each recommendation can be presented on
the screen. Other information, such as a representative
MSDS and case studies, also is included.
SAGE is available through the Control Technology Cen-
ter (CTC) of the EPA Air and Energy Engineering Re-
search Laboratory (AEERL). A system operator at the
CTC can be reached by calling (919) 541-0800. The
SAGE software can be transferred on an electronic
bulletin board system in a file named SAGE.ZIP. The
bulletin board can be reached at (919) 541-5742 (9600
baud, no parity, 8 data bits, 1 stop bit).
Solvent Utilization Handbook
The U.S. Department of Energy (DOE) has supported a
solvent alternative utilization study through the Idaho
National Engineering Laboratory. As a result, a program
was established to develop an online electronic Solvent
Utilization Handbook. The handbook helps users ac-
complish the following tasks:
. Identify solvents that are not restricted for use at DOE
Defense Programs, U.S. Department of Defense
(DoD) facilities, and private business.
"Monroe, K.R., and E.A. Hill. 1993. SAGE (Solvent Alternatives
Guide): Computer assisted guidance for solvent replacement. In:
Proceedings of the 1993 International CFC and Halon Alternatives
Conference. Washington, DC: Alliance for Responsible CFC Policy.
pp. 431-439.
42
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Evaluate their cleaning performance needs.
For more information, contact:
• Identify potential problems, such as corrosivity, flam-
mability (flash point), and hazardous material content
(OSHA and NIOSH exposure limits).
• Evaluate potential concerns for air emissions.
• Decide whether solvent recovery and recycling are
feasible.
• Determine whether the solvents are biodegradable.
The information provided in this database is based on
results of actual experiments that included 16 different
contaminants on 26 metal alloys. The database is acces-
sible through Internet or by using a telephone modem.
Further information can be obtained from the Idaho Na-
tional Engineering Laboratory by calling (208) 526-7834.
Solvent Database
The National Center for Manufacturing Sciences
(NCMS) is developing an electronic Solvent Database
that provides information on environmental fate, health
and safety data, regulatory status, chemical and physi-
cal properties, and product suppliers. The database in-
cludes more than 320 pure solvents and trade name
mixtures. A relational search capability enables users to
identify potential alternative solvents by specifying
search criteria. For example, solvent alternatives can be
selected by minimum flash point or by a particular regu-
latory issue. Product performance data are not included
in the current version.
The NCMS Solvent Database will be a stand-alone
application that nuns on the DOS platform. It will be
distributed on floppy disks. The cost of the software has
not been released. For further information contact Mike
Wixom, Project Manager, Environmentally Conscious
Manufacturing, NCMS; telephone (313) 9954910.
Waste Reduction Technical/Financial/
Assistance Programs
The EPA Pollution Prevention Information Clearing-
house (PPIC) was established to help reduce industrial
pollutants through technology transfer, education, and
public awareness. PPIC collects and disseminates tech-
nical and other information on pollution prevention
through a telephone hotline and an electronic informa-
tion exchange network. Indexed bibliographies and ab-
stracts of reports, publications, and case studies about
pollution prevention are available. PPIC also lists a cal-
endar of pertinent conferences and seminars; informa-
tion about activities abroad and a directory of waste
exchanges. Its Pollution Prevention Information Ex-
change System (PIES) can be accessed electronically
24 hours a day without fees.
PIES Technical Assistance
Science Applications International Corp.
8400 Westpark Drive
McLean, VA 22102
(703) 821-4800
or
U.S. Environmental Protection Agency
401 M Street SW.
Washington, DC 20460
Myles E. Morse
Off ice of Environmental Engineering and
Technology Demonstration
(202) 475-7161
Priscilla Flattery
Pollution Prevention Off ice
(202) 245-3557
Jhe EPA's Office of Solid Waste and Emergency Re-
sponse has a telephone call-in service to answer ques-
tions regarding RCRA and Super-fund (CERCLA). The
telephone numbers are:
(800) 424-9346 (outside the District of Columbia)
(202) 382-3000 (in the District of Columbia)
State Pollution Prevention Programs
The following state programs offer technical and/or fi-
nancial assistance for waste minimization and treatment.
Alabama
Hazardous Material Management and Resources
Recovery Program
University of Alabama
P.O. Box 6373
Tuscaloosa, AL 35487-6373
(205) 348-8401
Alaska
Alaska Health Project
Waste Reduction Assistance Program
431 West Seventh Avenue, Suite 101
Anchorage, AK 99501
(907) 276-2864
Arkansas
Arkansas Industrial Development Commission
One State Capitol Mall
Little Rock, AR 72201
(501) 371-1 370
43
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California
Illinois
Alternative Technology Division
Toxic Substances Control Program
California State Department of Health Services
714-744 p street
Sacramento, CA 94234-7320
(916) 324-1807
Connecticut
Connecticut Hazardous Waste Management Service
Suite 360
900 Asylum Avenue
Hartford, CT 06105
(203) 244-2007
Florida
Waste Reduction Assistance Program
Florida Department of Environmental Regulation
2600 Blair Stone Road
Tallahassee, FL 32399-2400
(904) 488-0300
Georgia
Hazardous Waste Technical Assistance Program
Georgia Institute of Technology
Georgia Technical Research Institute
Environmental Health and Safety Division
O'Keefe Building, Room 027
Atlanta, GA 30332
(404) 894-3806
Environmental Protection Division
Georgia Department of Natural Resources
Floyd Towers East, Suite 1154
205 Butter Street
Atlanta, GA 30334
(404) 656-2833
Guam
Solid and Hazardous Waste Management Program
Guam Environmental Protection Agency
ITCE E. Harmon Plaza, Complex Unit D-107
130 Rojas Street
Harmon, Guam 96911
(671) 646-8863
Hazardous Waste Research and Information Center
Illinois Department of Energy and Natural Resources
I East Hazelwood Drive
Champaign, IL61820
(217) 333-8940
Illinois Waste Elimination Research Center
Pritzker Department of Environmental Engineering
Alumni Building, Room 102
Illinois Institute of Technology
3200 South Federal Street
Chicago, IL 60616
(313) 567-3535
Indiana
Environmental Management and Education Program
Young Graduate House, Room 120
Purdue University
West Lafayette, IN 47907
(317) 494-5036
Indiana Department of Environmental Management
Office of Technical Assistance
P.O. Box 6015
105 South Meridian Street
Indianapolis, IN 46206-6015
(317) 232-8172
Iowa
Center for Industrial Research and Service
205 Engineering Annex
Iowa State University
Ames, IA 50011
(515) 294-3420
Iowa Department of Natural Resources
Air Quality and Solid Waste Protection Bureau
Wallace State Office Building
900 East Grand Avenue
Des Moines, IA 50319-0034
(515) 281-8690
Kansas
Bureau of Waste Management
Department of Health and Environment
Forbesfield, Building 730
Topeka, KS 66620
(913) 269-I 607
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Kentucky
Division of Waste Management
Natural Resources and Environmental Protection Cabinet
18 Reilly Road
Frankfort, KY 40601
(502) 564-6716
Louisiana
Department of Environmental Quality
Office of Solid and Hazardous Waste
P.O. Box 44307
Baton Rouge, LA 70804
(504) 342-I 354
Maryland
Maryland Hazardous Waste Facilities Siting Board
60 West Street, Suite 200 A
Annapolis, MD 21401
(301) 974-3432
Maryland Environmental Service
2020 Industrial Drive
Annapolis, MD 21401
(301) 269-3291
(800) 492-9188 (in Maryland)
Massachusetts
Off ice of Technical Assistance
Executive Office of Environmental Affairs
100 Cambridge Street, Room 1094
Boston, MA 02202
(617) 727-3260
Source Reduction Program
Massachusetts Department of Environmental
Protection
1 Winter Street
Boston, MA 02108
(617) 292-5982
Michigan
Resource Recovery Section
Department of Natural Resources
P.O. Box 30028
Lansing, Ml 48909
(517) 373-0540
Minnesota
Minnesota Pollution Control Agency
Solid and Hazardous Waste Division
520 Lafayette Road
St. Paul, MN 55155
(612) 296-6300
Minnesota Technical Assistance Program
1313 5th Street SE., Suite 207
Minneapolis, MN 55414
(612) 627-4555
(800) 247-0015 (Minnesota)
Missouri
State Environmental Improvement and Energy
Resources Agency
P.O. Box 744
Jefferson City, MO 65102
(314) 751-4919
New Hampshire
New Hampshire Department of Environmental
Sciences
Waste Management Division
6 Hazen Drive
Concord, NH 03301-6509
(603) 271-2901
New Jersey
New Jersey Hazardous Waste Facilities
Siting Commission
Room 614
28 West State Street
Trenton, NJ 08608
(609) 292-I 459
(609) 292-I 026
Hazardous Waste Advisement Program
Bureau of Regulation and Classification
New Jersey Department of Environmental Protection
401 East State Street
Trenton, NJ 08625
(609) 292-8341
Risk Reduction Unit
Office of Science and Research
New Jersey Department of Environmental Protection
401 East State Street
Trenton, NJ 08625
(609) 984-6070
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New York
Oregon
New York State Environmental Facilities Corporation
50 Wolf Road
Albany, NY 12205
(518) 457-3273
North Carolina
Pollution Prevention Pays Program
Department of Natural Resources and
Community Development
P.O. Box 27687
512 North Salisbury Street
Raleigh, NC 27611
(919) 733-7015
Governor's Waste Management Board
325 North Salisbury Street
Raleigh, NC 27611
(919) 733-9020
Technical Assistance Unit
Solid and Hazardous Waste Management Branch
North Carolina Department of Human Resources
P.O. Box 2091
306 North Wilmington S.
Raleigh, NC 27602
(919) 733-2178
Ohio
Division of Solid and Hazardous Waste Management
Ohio Environmental Protection Agency
P.O. Box 1049
1800 WaterMark Drive
Columbus, OH 43266-I 049
(614) 481-7200
Ohio Technology Transfer Organization
Suite 200
65 East State Street
Columbus, OH 43266-0330
(614) 466-4286
Oklahoma
Industrial Waste Elimination Program
Oklahoma State Department of Health
P.O. Box 53551
Oklahoma City, OK 73152
(405) 271-7353
Oregon Hazardous Waste Reduction Program
Department of Environmental Quality
811 Southwest Sixth Avenue
Portland, OR 97204
(503) 229-5913
Pennsylvania
Pennsylvania Technical Assistance Program
501 F. Orvis Keller Building
University Park, PA 16802
(814) 865-0427
Center of Hazardous Material Research
320 William Pitt Way
Pittsburgh, PA 15238
(412) 826-5320
Bureau of Waste Management
Pennsylvania Department of Environmental Resources
P.O. Box 2063
Fulton Building
3rd and Locust Streets
Harrisburg, PA 17120
(717) 787-6239
Rhode Island
Office of Environmental Coordination
Department of Environmental Management
83 Park Street
Providence, Rl 02903
(401) 277-3434
(800) 253-2674 (in Rhode Island only)
Ocean State Cleanup and Recycling Program
Rhode Island Department of Environmental
Management
9 Hayes Street
Providence, Rl 02908-5003
(401) 277-3434
(800) 253-2674 (in Rhode Island)
Center for Environmental Studies
Brown University
P.O. Box 1943
135 Angell Street
Providence, Rl 02912
(401) 863-3449
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Tennessee
Center for Industrial Services
102 Alumni Hall
University of Tennessee
Knoxville, TN 37996
(615)974-2456
Virginia
Office of Policy and Planning
Virginia Department of Waste Management
11th Floor, Monroe Building
101 North 14th Street
Richmond, VA 23219
(804) 225-2667
Washington
Hazardous Waste Section
Mail Stop PV-11
Washington Department of Ecology
Olympia, WA 98504.8711
(206) 459-6322
Wisconsin
Bureau of Solid Waste Management
Wisconsin Department of Natural Resources
P.O. BOA-7921
101 South Webster Street
Madison, Wl 53707
(608) 267-3763
Wyoming
Solid Waste Management Program
Wyoming Department of Environmental Quality
Hechler Building, 4th Floor, West Wing
122 West 25th Street
Cheyenne, WY 82002
Waste Exchanges
Alberta Waste Materials Exchange
Mr. William C. Kay
Alberta Research Council
P.O. BOA-8330
Postal Station F
Edmonton, Alberta
CANADA T6H 5X2
(403) 450-5408
British Columbia Waste Exchange
Ms. Judy Toth
2150 Maple Street
Vancouver, BC
CANADA V6J 3T3
(604)731-7222
California Waste Exchange
Mr. Robert McCormick
Department of Health Services
Toxic Substances Control Program
Alternative Technology Division
P.O. BOA-942732
Sacramento, CA 94234-7320
(916) 324-1807
Canadian Chemical Exchange
Mr. Philippe LaRoche
P.O. BOA-I 135
Ste-Adele, Quebec
CANADA JOR ILO
(514)229-6511
Canadian Waste Materials Exchange
ORTECH International
Dr. Robert Laughlin
2395 Speakman Drive
Mississauga, Ontario
CANADA LSK IBS
(416) 822-4111, Ext. 265
FAX: (416) 823-1446
Enstar Corporation
Mr. J.T. Engster
P.O. Box 189
Latham, NY 12110
(518)785-0470
Great Lakes Regional Waste Exchange
400 Ann Street, NW., Suite 201A
Grand Rapids, Ml 49505
(616)363-3262
Indiana Waste Exchange
Dr. Lynn A. Corson
Purdue University School of Civil Engineering
Civil Engineering Building
West Lafayette, IN 47907
(317) 494-5036
Industrial Materials Exchange
Mr. Jerry Henderson
172 20th Avenue
Seattle, WA 98122
(206) 296-4633
FAX: (206) 296-0188
Industrial Materials Exchange Service
Ms. Diane Shockey
P.O. Box 19276
Springfield, IL 62794-9276
(217) 782-0450
FAX: (217) 524-4193
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Industrial Waste Information Exchange
Mr. William E. Payne
New Jersey Chamber of Commerce
S Commerce Street
Newark, NJ 07102
(201) 623-7070
Manitoba Waste Exchange
Mr. James Ferguson
c/o Biomass Energy Institute, Inc.
1329 Niakwa Road
Winnipeg, Manitoba
CANADA R2J 3T4
(204) 257-3891
Montana Industrial Waste Exchange
Mr. Don Ingles
Montana Chamber of Commerce
P.O. Box1730
Helena, MT 59624
(406) 442-2405
New Hampshire Waste Exchange
Mr. Gary J. Olson
c/o NHRRA
P.O. Box 721
Concord, NH 03301
(603) 224-6996
Northeast Industrial Waste Exchange, Inc.
Mr. Lewis Cutler
90 Presidential Plaza, Suite 122
Syracuse, NY 13202
(315) 422-6572
FAX: (315) 422-9051
Ontario Waste Exchange
ORTECH International
Ms. Linda Varangu
2395 Speakman Drive
Mississauga, Ontario
CANADA LSK1B3
(416 822-4111, Ext. 512
FAX: (416) 823-1446
Pacific Materials Exchange
Mr. Bob Smee
South 3707 Godfrey Boulevard
Spokane, WA 99204
(509) 623-4244
Peel Regional Waste Exchange
Mr. Glen Milbury
Regional Municipality of Peel
10 Peel Center Drive
Brampton, Ontario
CANADA L6T 4B9
(416) 791-9400
RENEW
Ms. Hope Castillo
Texas Water Commission
P.O. Box 13087
Austin, TX 7871 I-3087
(512) 463-7773
FAX: (512) 463-8317
San Francisco Waste Exchange
Ms. Portia Sinnott
2524 Benvenue #35
Berkeley, CA 94704
(415) 548-6659
Southeast Waste Exchange
Ms. Marie L. May
Urban Institute
UNCC Station
Charlotte, NC 28223
(704) 547-2307
Southern Waste Information Exchange
Mr. Eugene B. Jones
P.O. Box 960
Tallahassee, FL 32302
(800) 441 -SWIX (7949)
(904) 644-5516
FAX: (904) 574-6704
Tennessee Waste Exchange
Ms. Patti Christian
226 Capital Boulevard, Suite 800
Nashville, TN 37202
(615) 256-5141
FAX: (615) 256-6726
Wastelink, Division of Tencon, Inc.
Ms. Mary E. Malotke
140 Wooster Pike
Milford, OH45150
(513) 248-0012
FAX: (513) 248-1094
EPA Regional Offices
Region 1 (VT, NH, ME, MA, CT, Rl)
John F. Kennedy Federal Building
Boston, MA 02203
(617) 565-3715
Region 2 (NY, NJ)
26 Federal Plaza
New York, NY 10278
(212) 264-2525
Region 3 (PA, DE, MD, WV, VA)
841 Chestnut Street
Philadelphia, PA 19107
(215) 597-9800
48
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Region 4 (KY, IN, NC, SC, GA, FL, AL, MS)
345 Courtland Street, NE
Atlanta, GA 30365
404) 347-4727
Region 5 (Wl, MN, Ml, IL, IN, OH)
230 South Dearborn Street
Chicago, IL 60604
(312) 353-2000
Region 6 (NM, OK, AR, LA, TX)
1445 Ross Avenue
Dallas, TX 75202
(214) 655-6444
Region 7 (NE, KS, MO, IA)
756 Minnesota Avenue
Kansas City, KS 66101
(913) 236-2800
Region 8 (MT, ND, SD, WY, UT, CO)
999 18th Street
Denver, CO 80202-2405
(303) 293-I 603
Region 9 (CA, NV, AZ, HI)
75 Hawthorne Street
San Francisco, CA 94105
(415) 744-I 305
Region 10 (AK, WA, OR)
1200 Sixth Avenue
Seattle, WA 98101
(206) 442-5810
'U.S. Government Printing Office: 1997 - 549-001/60123
49
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United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
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