c/EPA
United States
Environmental Protection
Agency
Air And
Radiation
(ANR-445)
21A-4002
April 1991
Handbook For Reducing And
Eliminating Chlorofluorocarbons
hi Flexible Polyurethane Foams
•-•ft
EPA
21A-
4002
ncy land 111
ates Enviranfhental Pi^»ctfon
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in
Flexible Polyurethane Foams
A Joint Project of the
United States Environmental Protection Agency
and the
Polyurethane Foam Association
Guide for Responsible
Replacement of Chlorofluorocarbons
United States Environmental Protection Agency
Office of Air and Radiation
401 M Street, S.W. (ANR445)
Washington, D.C. 20460
April 1991
-< THIS DOCUMENT HAS BEEN REVIEWED IN ACCORDANCE WITH UNITED STATES ENVIRONMENTAL
- PROTECTION AGENCY POLICY, AND APPROVED FOR PUBLICATION. MENTION OF TRADE NAMES OR
e COMMERCIAL PRODUCTS DOES NOT CONSTITUTE ENDORSEMENT OR RECOMMENDATION FOR USE.
-------
We would like to thank the
Polyurethane Foam Association
for all their help in
producing this handbook.
-------
Handbook for Reducing and Eliminating
Chlorof lourocarbons in Flexible Polyurethane Foams
April 1991
PREFACE v
CHAPTER ONE: INTRODUCTION 1
1.1 Background 1
1.2 Ozone-Depleting Substances 1
1.3 Regulatory Action 2
1.4 The Flexible Polyurethane Foam Industry 3
CHAPTER TWO: PROCESS CHARACTERISTICS 5
2.1 Methods of Manufacturing 5
2.2 Basic Chemistry and Foam Process 5
CHAPTER THREE: PROCESS VARIABLES 9
3.1 Equipment 9
3.1.1 Traditional Slabstock Method 9
3.1.1.1 Maxfoam 11
3.1.1.2 E-Max 12
3.1.1.3 Vertifoam 12
3.1.1.4 Hypercure/Envirocure 12
3.1.1.5 "Golden Bucket" 12
3.1.2 Molded Foam 13
3.2 Chemicals 13
3.3 Ambient Conditions 13
3.3.1 Relative humidity/absolute moisture 15
3.3.2 Barometric Pressure 15
3.4 Process/Curing Conditions 15
3.5 Market Environment 15
CHAPTER FOUR: ALTERNATIVES 17
4.1 Conservation 17
4.1.1 Good Housekeeping Practices 17
4.1.2 Reformulation 17
4.1.3 Safety Standards 17
4.1.4 Recovery and Recycling 18
4.1.4.1 Principles of Activated Carbon Adsorption 19
4.1.4.2 Recycling Systems 20
4.1.4.2.1 ....E-Max Foam Systems 20
4.1.4.2.2 ....Hypercure/Envirocure 20
4.1.4.2.3 ....Add-On Recycling Systems 21
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
April 1991
(Contents, continued)
4.2 Alternative Auxiliary Blowing Agents 21
4.2.1 Methylene Chloride 21
4.2.2 Methyl Chloroform 23
4.2.3 HCFCs 25
4.2.4 Acetone 26
4.2.5 AB Technology 28
4.2.6 Other Alternatives 30
4.3 Alternative Paths to Foam Softening 30
4.3.1 Modified HR Forms 30
4.3.1.1 Ultracel™ Technology 30
4.3.1.2 Resteasy Plus™ 31
4.3.2 Extended Range Conventional Polyols 33
4.3.3 ORTEGOL™310 34
4.3.4 Geolite™ Technology 35
4.3.5 Unilink™ 35
4.4 Summary 36
CHAPTER FIVE: METHODOLOGY FOR SELECTION 39
REFERENCES 43
FIGURES
1 Ozone Depletion 1
2 How Ozone is Destroyed 2
3 Typical Slabstock Production Line for Flexible Polyurethane Foam 10
4 Maxfoam Foam Production Process 11
5 Humidity Effects 14
6 Altitude Effects 14
7 Methodology for Selection of Alternative Technology: Preparation/Selection 41
8 Methodology for Selection of Alternative Technology 42
TABLES
1 Typical Physical Properties of Alternative Fluorocarbons 27
2 Flexible Polyurethane Foam Options 37
Publisher's Note: Pages 8 and 38 are designated as blank pages in this publication.
Page Hi
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Preface
Trichlorofluoromethane (CFC-11) has been a widely used aux-
iliary blowing agent in the manufacturing process of flexible
polyurethane foam. CFC-11's appeal has resulted from a combi-
nation of physical properties, such as its low boiling point,
appropriate vapor pressure, and low toxicity. In addition, CFC-
11 is non-flammable, economically attractive, and has a mini-
mal effect upon foam production practices.
The consumption of CFC-11 has been rapidly reduced in the
United States as a result of both the Montreal Protocol require-
ments (calling for the phaseout of CFCs by the year 2000), and
the imposition of taxes on CFCs, which makes it economically
prohibitive for most companies. Some of the properties that
made CFC-11 a preferred blowing agent in the industry also
cause environmental problems. CFCs do not decompose until
they reach the upper atmosphere (the stratosphere) and, once in
the stratosphere, they do decompose under the influence of
ultraviolet light and release chlorine. It has been scientifically
determined that chlorine depletes the stratospheric ozone layer
which shields the earth, humans and other planetary life from
harmful ultraviolet-B (UV-B) radiation.
Because of these environmental effects, the global community
has called for a phaseout of CFCs and other ozone-depleting
chemicals by the year 2000. The polyurethane flexible foam
industry in the United States has proposed the elimination of
the use of CFC-11 before the year 2000. EUROPUR and the
British Rubber Manufacturers Association have called for a mid
1990s phaseout. In 1986, 45% of all flexible foam in the United
States was made using CFC-11; in 1990, that figure has been
lowered to less than 10%.
This handbook introduces various technologies and techniques
used internationally for reducing and eliminating the use of
CFC-11 in the manufacture of flexible polyurethane foam. It
also provides historical information about manufacturing meth-
ods, as well as descriptions of future technologies that will alter
the basic foam chemistry or production process in order to
achieve a desirable product that can be finished without the
need for CFCs. This publication serves as a guide for identifying
and selecting appropriate alternatives. As the flexible foam
industry makes its transition from the use of CFC-11 to alterna-
tives, worldwide support will ensure its success. Worldwide
cooperation, dedication and commitment to reducing the use of
CFC-11 in the flexible foam industry will ensure a smooth
transition to CFC alternatives.
Page v
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BACKGROUND
1.1
FIGURE 1
The upper atmosphere of the earth contains a layer that is
relatively rich in ozone (O3). This layer is known as the strato-
sphere. Ozone from the stratosphere acts as a shield for the
earth's surface against harmful quantities of solar ultraviolet
(UV) radiation. In 1974, Molina and Rowland theorized that
stratospheric ozone is destroyed by the chlorine in chlorofluoro-
carbons entering the atmosphere; as a result, increased quanti-
ties of ultraviolet light reach the earth's surface. Other scien-
tific research findings since 1974 have confirmed that bromine
and chlorine from halons, chlorofluorocarbons, and other com-
pounds are all contributing to the depletion of the earth's
natural shield. Figure 1 illustrates the relationship between
CFCs and the ozone layer.
Since stratospheric ozone screens out ultraviolet-B (UV-B)
rays, depletion of the ozone layer would leave the earth's surface
and inhabitants vulnerable to long-term increases in skin can-
cer and cataracts, suppression of the human immune system,
damage to crops and natural ecosystems, and damage to plas-
tics. In 1987, the United States Environmental Protection Agency
(EPA) estimated that if the depletion of ozone continued, there
could be over 150 million additional cases of skin cancer in the
United States alone, resulting
in 3.2 million deaths for the
population alive today and
those born before 2075. Re-
searchers are also examining
the relationship that ozone
depletion may have with global
warming.
OZONE-DEPLETING
SUBSTANCES
1.2
Chlorofluorocarbons
(CFCs)—chemical compounds
that are highly stable, non-
toxic, and non-flammable—
currently function as refriger-
ants in refrigerators, freezers,
and air-conditioners; aerosol
propellants; cleaning solvents
for precision and metal clean-
ing and hospital sterilization;
and blowing agents in rigid,
flexible, and integral skin
Ozone Depletion
-------
Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
How Ozone is Destroyed
Ultraviolet Light
Chlorine Atom
Chlorine Free Oxygen Atom
Monoxide _ A
0»^
Chlorofluorocarbon
Molecule
In the upper atmosphere, ultraviolet
light breaks off a chlorine atom
from a Chlorofluorocarbon
molecule.
Ozone Molecule Oxygen Molecule
The chlorine attacks an ozone
molecule breaking it apart. An
ordinary oxygen molecule and a
molecule of chlorine monoxide are
formed.
A free oxygen atom breaks up the
chlorine monoxide. The chlorine is
free to repeat the process.
FIGURE 2
REGULATORY
ACTION
1.3
foams. Some of the same characteristics that make CFCs excel-
lent chemicals for use in foam-blowing make them dangerous to
the ozone layer. Because CFCs are so stable, they do not break
up easily and have long atmospheric lifetimes. As a result, CFCs
slowly migrate into the stratosphere where they disintegrate
and release chlorine; in turn, the chlorine reacts with the ozone
and destroys it. (See Figure 2)
Other ozone-depleting chemicals include methyl chloroform,
carbon tetrachloride, halons, and hydrochlorofluorocarbons
(HCFCs). Halons are a group of fire-suppressing chemicals that
contain bromine—a chemical which is several times more effec-
tive than chlorine at ozone depletion. HCFCs are partially
halogenated (non-metallic) CFCs. The added hydrogen mol-
ecule weakens the molecular structure of CFCs and allows them
to break up before reaching the stratosphere. In this way,
HCFCs contribute less than other fully halogenated CFCs to the
amount of chlorine loading near the ozone layer.
In 1978, the United States Government banned the use of
CFCs in non-essential aerosol products because of concern over
ozone depletion, and the country reduced CFC consumption by
50 percent. Several other countries—including Canada, Swe-
den, Denmark, Finland, Norway, Austria, Switzerland, the UK,
and New Zealand—have followed the United States by banning
non-essential aerosols. By 1982, even despite this control, the
global production of CFCs continued to increase. In response to
the threat of ozone depletion, the United Nations Environment
Programme (UNEP) developed an international framework to
control substances that deplete ozone, known as the 1985 Vienna
Convention to Protect the Ozone Layer. The Vienna Convention
led to the adoption of an international treaty called the Montreal
Protocol on Substances that Deplete the Ozone Layer.
Page 2
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One: Introduction
THE FLEXIBLE
POLYURETHANE
FOAM INDUSTRY
1.4
The Montreal Protocol became effective on January 1, 1989.
Today, over 70 nations, representing over 90% of the world's
CFG and halon production, have ratified the Montreal Protocol.
This Protocol is designed to protect the stratospheric ozone
layer by controlling the production of ozone-depleting chemi-
cals. Currently, production of CFC-11, -12, -113, -114, and -115,
halons, and carbon tetrachloride are to be phased out by 2000.
Methyl chloroform is to be phased out by 2005. The Parties
signed a declaration to monitor and possibly control HCFCs in
the future. The Protocol control measures are scheduled to be
reassessed every four years to ensure the restrictions will pro-
tect the ozone layer.
The U.S. Congress, through recent amendments to the Clean
Air Act, has taken domestic action by requiring a phaseout of
methyl chloroform by the year 2002. The Clean Air Act will also
place restrictions on HCFC production by 2015 with a phaseout
scheduled for 2030.
In addition to controls placed on ozone-depleting substances,
the United States has imposed a fee on the chemicals controlled
under the 1989 Protocol and a fee on imports of products made
with or containing these chemicals. These taxes will increase
the cost of using CFCs and halons. Recycled chemicals are
exempt from the tax.
Since its commercial introduction in the late 1940s, flexible
polyurethane foam has become an important cushioning mate-
rial throughout the world. Flexible polyurethane slabstock foam
products are used in a variety of finished products, including
furniture, beds, carpet underlay, and automobiles. Flexible
polyurethane molded foam products are used primarily as auto-
mobile seat cushions and seat backs and as components in
specialty furniture.
CFC-11 Phaseout
CFC-11 must be phased out as an auxiliary blowing agent in
flexible polyurethane foam manufacturing by the year 2000.
However, phasing out any auxiliary blowing agent can diminish
the manufacturer's operating latitude. Without alternatives,
this narrowed latitude can mean a potential reduced availabil-
ity of many types of flexible polyurethane foam, such as low
density foams [below 21 kg/m3 ] and soft foams [below 133 New-
tons (N) Indentation Force Deflection (IFD) at 25% deflection].
The biggest challenge facing the flexible polyurethane foam
industry is to develop cost-effective alternatives for super-soft
and low density foams. Without effective alternatives, manu-
facturers of flexible polyurethane foam could lose their markets.
End users might switch from flexible foam to competitive
cushioning products, based on economic considerations.
Page3
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
Manufacturers of flexible foam have a variety of alternatives
to CFC-11. Among these alternatives, a combination of options
is ideal. To achieve the right combination, manufacturers must
consider the following factors unique to their operations: prod-
uct mix, production equipment, manufacturing environment
and regulatory constraints. Also, the opportunity for additional
innovative technology may yield new alternative practices within
the next few years.
This handbook serves as a guide to phasing out CFCs in the
flexible polyurethane foam industry. It describes all the options
currently (1990) identified as potential alternatives to CFC-11
blowing agents. Options will include substitute auxiliary blowing
agents and process modifications. To assist in achieving a
successful reduction, and complete elimination, of CFCs in the
foam industry, this book includes a methodology for the selec-
tion of alternative technologies. The methodology should be
used as a tool for manufacturers to carefully analyze their
current use of CFC-11, consider their individual product mix,
and evaluate the advantages and disadvantages of using the
various alternatives described here.
In assessing the alternatives to CFC-11, many unique circum-
stances may arise. Consult the section on contacts for further,
more specific information.
The authors have designed this publication knowing that each
manufacturer's circumstances are unique. By following the
suggestions outlined in the handbook, manufacturers of flexible
foam can confidently and thoroughly consider all aspects of the
evaluation process. The authors hope that the end result of this
evaluation process is the selection and implementation of the
best possible alternative to CFCs at the most economically
feasible cost.
Page 4
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Process Characteristics
METHODS OF
MANUFACTURING
2.1
BASIC CHEMISTRY
AND FOAM
PROCESS
2.2
In this chapter, the basic methods, chemistry and process of
flexible polyurethane foam manufacturing will be reviewed.
The two basic methods for manufacturing flexible polyure-
thane foam are the slabstock (bun, block)—for larger volume—
and molded foam—for smaller volume. The process common to
both methods is a closely controlled chemical reaction during
which the formation of the polymeric product is simultaneously
expanded with a self-generated (C02) blowing agent. About 60%
of slabstock foam manufactured in the United States uses an
auxiliary blowing agent.
Flexible polyurethane foam is made by the intense, vigorous
mechanical mixing of either polyether or polyester polyols with
a diisocyanate in carefully controlled ratios along with water,
catalysts and surfactants. The resultant polymeric network is
expanded with the carbon dioxide formed in the reaction between
the water and the diisocyanate. The carefully balanced polymer-
ization and simultaneous expansion yields the foam product.
This basic process, from the mixing of the liquid chemicals to the
formation of fully expanded foam, occurs in less than three
minutes. This procedure can be augmented with auxiliary
blowing agents which use the exothermic heat of chemical
reaction for vaporization.
The process described above is common to both manufacturing
methods—slabstock and molded foam. The difference between
the two manufacturing methods is that the slabstock method is
a continuous process at operating rates up to 300 kg per minute
which can be run for several hours. By contrast, the molding
method is an intermittent, batch process that features operat-
ing rates from 20-200 kg per minute but operates for only
seconds at a time. With this procedure, the foam is formed in 1-
10 kg pieces.
Foam manufacturers control and aid the chemical reaction by
the use of catalysts and surfactants, and by temperature con-
trol. Foam properties and characteristics can be further altered
by the addition of colorants, combustion modifiers, fillers and
auxiliary blowing agents.
Auxiliary blowing agents are used because there are limits on
the foam properties that can be achieved with CO2 as the sole
blowing agent and because of the nature of the exothermic
reaction of isocyanate with water. This reaction can cause the
foam to scorch or to auto-ignite in the manufacturing and curing
areas.
PageS
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
Carbon dioxide serves to expand the forming polymer network
and to provide the foaming action. The greater the volume of the
carbon dioxide formed, the more expanded is the polymer net-
work and the lower is the resultant density. However, this
increased carbon dioxide formation occurs at the expense of
creating larger amounts of hard segment urea areas and in-
creased firmness in the foam.
The lower density limit achieved with CO2as the sole blowing
agent is approximately 21 kg/m3. The extreme exotherm devel-
oped by using more water to generate greater quantities of CO2
will invariably cause the foam to scorch or to auto-ignite while
in the foam curing area. Therefore, the auxiliary blowing agent
is used to reduce the heat formation and to provide the extra gas
volume to achieve density levels as low as 14.5 kg/m3.
As stated earlier, hard urea segments develop in the foam
polymer network as a byproduct of the water and diisocyanate
exothermic reaction (which forms the CO2). This urea formation
establishes a natural limit to the softness of the foam. As the
water level is increased to release more CO2 and to produce a
lower density foam, the hardness of the foam is automatically
increased. In order to make foams that are less than approxi-
mately 133 Newtons IFD at 25% IFD, one can use an auxiliary
blowing agent in addition to CO2. This procedure provides the
needed gas to expand the polymer network while avoiding the
formation of urea hard segments.
Auxiliary blowing agents were not used to produce flexible
polyurethane foam until the early 1960s. During this period, the
natural limit on foam density at approximately 21 kg/m3 was
accepted and variations on foam hardness were obtained by
manipulating polymer morphology through polyol molecular
weight.
The introduction of CFC-11 as an auxiliary blowing agent in
the early 1960s provided an important manufacturing tool that
permitted a tremendous increase in the spectrum of foam physi-
cal properties including density and firmness. CFC-11 proved to
be the ideal auxiliary blowing agent.
CFC-11, being a liquid at initial mixing temperatures and
inert to the polyol, diisocyanate, water, catalysts and surfac-
tants, quickly converted to gaseous form as the exotherm of the
water, diisocyanate reaction was initiated. The heat of vapor-
ization of the CFC-11 provided the desirable cooling effect upon
the exothermic reaction. As the foam reached full expansion,
the foam cells drained and released their contained gas (CO2
and CFC-11) to the atmosphere. The non-solubility of the CFC-
11 was extremely important at this stage of the chemical pro-
Page6
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Two: Process Characteristics
cess as it allowed quick release of the auxiliary blowing agent.
The relatively low price of CFC-11 provided yet another impor-
tant incentive for its use. The non-flammability and low order of
toxicity of CFC-11 were further reasons for its acceptance.
By the early 1970s, it was discovered that methylene chloride
also had utility as an auxiliary blowing agent. Both CFC-11 and
methylene chloride were used and shared the market. It has
been reliably estimated that by 1986 CFC-11 totalled 80% of the
global market. Methylene chloride was predominantly used in
the U.S. market (65%). The molded foam method, when it
includes auxiliary blowing agents, uses CFC-11 exclusively.
Methylene chloride was not acceptable in the molded foam area
because of the inherent solubility of the methylene chloride in
the polymer network.
Page?
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Three: Process
EQUIPMENT
3.1
Traditional
slabstock method
3.1.1
Prior to considering process changes to facilitate the reduc-
tion and elimination of the use of CFC-11, flexible polyurethane
foam manufacturers should adequately acquaint themselves
with the manufacturing process and the variables that are
affecting it.
The choice of the manufacturing process and foaming equip-
ment are crucial factors in determining the feasibility of CFC-
11 alternatives. It is important to consider the type of chemicals
—or the limitation of their availability—and the ambient condi-
tions of climate and altitude. The primary and secondary pro-
cess conditions, such as reaction temperature and curing tem-
perature, are also of extreme importance. Lastly, the market
requirements to which manufacturers are subjected will influ-
ence their final selection.
The traditional slabstock foaming process (See Figure 3) will
be discussed in detail in Section 3.1.1. Other slabstock processes
which are generally modifications to the traditional method,
will also be described. Molded foam will be discussed in Section
3.1.2.
Mixed liquid chemicals are metered to a mixing head. The
discharge stream from this mixing head is dispensed with a
traversing pattern across the width of an inclined conveyor belt:
this is the "lay down." The conveyor belt is lined with polyeth-
ylene paper or polyethylene film to make a "U" shaped retainer
for the rising foam mass as it descends the initial sloped (3-5
degrees) conveyor belt section. Within 6 meters of the lay down,
the foam mass has usually reached its point of maximum ex-
pansion. Friction slows expansion at the sides producing a
domed slab. Mitigation technologies that strive for a more or
less rectangular block include the "Planiblock" system and the
"Draka-Petzetakis" system.
The foam can be as high as 1 to 1.25 meters and up to 2.5
meters wide. From its maximum expansion, the foam starts to
release its blowing agents and some unreacted chemicals. A
ventilated tunnel, typically covering the first section of the
conveyor system, exhausts these emissions and thereby controls
workplace concentrations.
Page 9
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
Typical Slabstock Production Line for
Flexible Polyurethane Foam
Polyol
TDI
CFC-11
or
MeCI
.-[ Console [
Water
Surfactant
Catalyst
To Sales •*
1 Chemical storage
2 Multiple-stream metering and mixing head
3 Traversing dispersing head (if used)
4 Feed trough (Max-Foam®)
5 Conveyor enclosure with
exhaust fans and stacks
6 Top surface wrapping rolls (optional)
7 Side paper take-off rolls
8 Bottom liner paper roll
9 Bun saw exhaust hood
10 Bun saw and operator station
FIGURE 3
The continuous slab of foam moves through the production
tunnel to a cut-off saw which slices it into blocks for curing and
storage. These blocks can be as short as 1 meter and as long as
60 meters. The exothermic chemical reaction continues within
the foam mass while in the curing area. The natural insulating
qualities of the foam maintain the heat for a period of several
hours. Slowly, the heat dissipates while the air penetrates the
block and replaces the residual blowing agent.
It is estimated that roughly 40 percent of the blowing agent is
emitted in the foam tunnel. Another 40 percent escapes in the
curing area, with the remainder emitted during cut-off and
transportation from tunnel to curing.
Page 10
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Three: Process Variables
Maxfoam
3.1.1.1
The conventional slabstock process is less economical than
methods developed later; consequently, it is on the decline. In
addition, processing is generally more critical, and the intro-
duction of CFC-replacements is, therefore, more problematic.
However, the process is still the primary choice for polyester
foams and many other specialty products.
Developed in the early 1970s, the Maxfoam process differs
from the traditional method in lay down and foam expansion
(See Figure 4). The discharge from the mixing head is moved
directly into a trough which is level with the ultimate height of
the foam slab. The rising foam mass expands and spills over the
front edge of the trough and is drawn away on a sloped fall plate.
This slope is kept similar in shape to the rise profile of the foam,
FIGURE 4
Conveyor
Mixhead
Maxfoam Foam Production Process
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
E-Max
3.1.1.2
Vertifoam
3.1.1.3
Hypercure/Envirocure
3.1.1.4
"Golden Bucket"
3.1.1.5
thus allowing a downward expansion. The resulting foam slab is
nearly rectangular in shape. The mechanical manipulation used
in the traditional method to make up for the side wall friction is
not needed.
The Maxfoam process of flexible foam production is less com-
plicated, less critical, and more efficient than conventional
foaming, and consequently, is currently the equipment of choice
for most manufacturers.
E-Max is a direct modification of Maxfoam which offers the
manufacturer better environmental control. Foam is poured in
long (60 meter) molds in which the foam cures. This is an
intermittent production process. Emissions are extracted from
the mold and can be treated prior to release. This system, which
allows recovery of significant amounts of auxiliary blowing
agent, will be discussed in Chapter 4.
The Vertifoam process was developed in the early 1980s in
England. This procedure controls foam expansion in four direc-
tions as opposed to the three directional control found in Maxfoam
and conventional flexible foam production. Because of this four-
directional control, Vertifoam could be called a "continuous
molding" process.
Mixed liquid chemicals are dispensed into the bottom of a
trough. The expanding foam mass is moved vertically in a four-
sided lined conveyor system, initially shaped to allow expansion
of the foam. The fully expanded foam is cut horizontally into
blocks of up to 3 meters long and moved to a curing area.
Vertifoam machinery is smaller than that of conventional or
Maxfoam, yet the foam produced is the same size as that coming
from a horizontal line—except for a limitation in bun length.
Vertifoam's process, because of its four-sided enclosure and
the vertical process direction, is somewhat more critical and
less forgiving that Maxfoam. The manufacturer would need a
thorough understanding of this process before introducing a
CFC-11 alternative.
Hypercure is a modification of the Vertifoam process which
allows for full environmental control and the recovery of blow-
ing agents. It will be discussed in Chapter 4.
The Golden Bucket process, also called single block, discon-
tinuous block or batch process, manufactures one block at a
time. Mixed liquid chemicals are dispensed into the bottom of a
lined open-top box. The expanding foam mass rises in the box
and usually results in a crowned block. This effect can be
mitigated by a floating top panel, which forces linear expansion,
but can also cause densification. The individual blocks are
moved to a curing area.
Page 12
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Three: Process Variables
Molded Foam
3.1.2
CHEMICALS
3.2
AMBIENT
CONDITIONS
3.3
Conventional (Hot Cure): Mixed liquid chemicals are dis-
pensed into the bottom cavity of a shaped mold. The lid is closed
and the mold is subjected to intense heat. The finished item is
removed from the mold after cooling and no further curing of the
item is necessary.
High Resilience (Cold Cure): Mixed liquid chemicals are dis-
pensed into the bottom cavity of a shaped mold. The lid is closed
and the mold is subjected to moderate heat. The alteration of the
basic chemistry permits the use of the lower heat levels, thus
the term—cold cure. After cooling, the finished item is removed
from the mold and no further curing is necessary.
The chemicals chosen—or available—also affect foam process-
ing and have an effect on CFC reduction and replacement
attempts. The process latitude is primarily dependent upon the
right selection of chemicals; the polyol choice is determined by
the physical properties demanded of the foam in the market
place.
Detailed recommendations will vary with local products. The
following suggestions may aid in the selection of chemicals as
alternatives to CFC-11.
When selecting CFC-11 Alternatives:
1. Assure a suitable anti-oxidant package in the
polyol. Avoiding scorch and auto-ignition be-
comes crucial as curing temperatures rise.
2. Select raw materials that provide the great-
est latitude:
* Use higher molecular weight polyols;
« Use low active silieones;
• Use additives sparingly, as most restrict
process latitude;
» Choose a catalyst which is related to the
equipment and replacement technology
selected,
For the best results, solicit the advice of raw material suppli-
ers and their evaluations on bench scale and pilot levels.
Climatic conditions in a facility can significantly impact the
density and firmness of the foam produced. Formulation adjust-
ments are often necessary on a seasonal or even daily basis to
compensate for load, density and processing changes due to
variations in weather. Foam manufacturing plants need to run
formulations tailored to their conditions of climate and altitude.
They can take advantage of these influences to minimize the use
of CFCs and other auxiliary blowing agents.
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
Humidity Effects
IFD vs. Absolute Humidity
Constant Formulation
IFD (Ibs)
48-
46-
44-
42-
411-
>.
^x,^
^\
w 1 1 1 1 1 1 1 1 1 1 1 1
0 20 40 60 80 100 120
Grains Moisture/Lb Dry Air
Source: Foamex, 1990
FIGURE 5
Altitude Effects
Blow Index vs. Altitude
Constant Formulation
Blow Index • Parts Water + Parts CFC/10
4
3.5-
3-
2.5-
2_
^^^^^
^^-
* I 1 1 1 1 1 1 1
012345678
Feet Above Sea Level (thousands)
Source: Foamex, 1990
FIGURE 6
Page 14
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Three: Process Variables
Relative humidity/
absolute moisture
3.3.1
Barometric pressure
3.3.2
PROCESS/CURING
CONDITIONS
3.4
MARKET
ENVIRONMENT
3.5
Increases in the absolute moisture content of the ambient air
around the foam, during rise and cure, reduce the firmness that
is produced. Absolute moisture content increases with rises in
temperature and relative humidity. Generally, the IFD will
decrease by about 1 percent for each increase of 10 grains of
moisture per pound of dry air. It has been commonplace to
increase the TDI index by one unit for each two or three Newtons
of load loss to maintain firmness under humid conditions. The
graph (Figure 5) demonstrates this loss of hardness. Reducing
the amount of auxiliary blowing agent and increasing the water
in the formulation could achieve the same result in grades that
do not require an auxiliary blowing agent for cooling.
Lower barometric pressure during foam rise results in lower
foam density and reduced firmness. These changes are attrib-
uted to increased blowing efficiency under these conditions.
Barometric pressure fluctuates with weather conditions, but a
larger and more predictable impact is seen with the altitude of
the foam plant. For each 100-meter increase in altitude, the
average barometric pressure decreases by about 1 centimeter of
mercury (Hg). (Refer to Figure 6) This change results in a
density decrease of about 3% and in a firmness decrease of about
6%. Typically, TDI index is increased to correct for loss in
hardness. Tin catalyst should be decreased. To correct for den-
sity changes, the auxiliary blowing agent can be reduced while
maintaining TDI index and water levels.
Curing conditions also need to be considered when reducing or
changing the auxiliary blowing agent. It is very important to
know the product temperature during processing and curing.
1. Curing temperature is directly related to raw material tem-
peratures.
2. Curing temperature is related to bun size and curing method
(rack, top curing, floor curing, etc).
3. Curing temperature is related to scorching and potential
auto-ignition.
Knowing curing temperatures is essential for adopting a CFC-
11 reduction plan while assuring safety and securing the most
economical approach possible.
The demands of the local end use markets for the flexible
polyurethane foam will have an impact upon the choices con-
sidered by the foam manufacturer to replace CFC-11 as an
auxiliary blowing agent.
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
The lack of competitive cushioning products in the market
place will permit the sale of flexible polyurethane foam at a
density that does not demand the use of auxiliary blowing
agents. This would be the simplest approach to reducing the use
of CFG-11. However, if local market economics demand that
foam must be available at densities lower than 21 kg/m3, then
the use of an alternative auxiliary blowing agent must be
explored.
The demands of the market place may require that soft foams
be available. If this demand is not coupled with a simultaneous
stipulation that the foam density also be lower than 21 kg/m3,
then the CFG-11 can be readily replaced by other alternatives.
However, if the market requires both low density and softness,
auxiliary blowing agents must be considered.
Reducing CFC-11 use affords the industry the time to make
changes in the market place. The opportunity to supply the
highest quality foam product that the local market economics
will tolerate should be the manufacturer's goal.
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„„
Four
CONSERVATION
4.1
Good housekeeping
practices
4.1.1
Reformulation
4.1.2
Safety standards
4.1.3
With a phaseout of CFC-11 production by the year 2000, it will
be necessary to find ways for foam manufacturers to keep their
process efficient and competitive.
Conservation is always a good manufacturing practice. Con-
servation in flexible foam manufacturing means employing those
processes and practices that require less use of an auxiliary
blowing agent. Conservation can be practiced by improving
housekeeping practices, by reformulation, and by recycling.
Conservation starts with proper housekeeping practices. Here
are some guidelines:
1. Inspect the storage tanks, piping and metering units for
leaks.
2. Unload only with a closed loop system.
3. Never use CPC-11 for flushing the mixing head and trough
nor for cleaning machine parts.
Conservation means careful handling of CFC-11 all through
the foam manufacturing process. It means knowing where CFC-
11 emissions can occur—on the foam line, along the transfer
conveyors, and in the curing area—and how to cut down on those
emissions.
Reformulation is a way of obtaining quick and significant
reductions in CFC-11 use. Formulations should be reviewed and
modified to allow for the lowest amount of auxiliary blowing
agent use to obtain the desired physical properties. Foam line
chemists frequently develop certain techniques of formulating
that may work well for a specific purpose but may not be needed.
The TDI index is kept high for processing convenience. Elimina-
tion of those practices have already saved many foam manufac-
turers up to 10% of total CFC-11 use.
Safety standards should never be compromised. The elimina-
tion of fire hazards and prevention of exposure to hazardous
chemicals should be the first priority. The following recommen-
dations have proven to support plant safety:
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
FIRE SAFETY
Keep curing temperatures below 160 C (320 F).
Remove starts, stops, and changeovers to a safe place. They have a high
potential for auto-ignition.
Check on explosion limits of alternative blowing agents. Insure that equip-
ment has appropriate explosion-proof motors.
Have an established, rehearsed "Hot Bun" procedure with the foam crew to
assure prompt and appropriate action in case of an "off-ratio" product.
PROTECTION TO EXPOSURE
Assure that Permissible Exposure Limits (PELs) are not exceeded under
standard process conditions.
Provide proper personnel protection for start-ups and emergencies.
Install continuous air monitoring, or perform personal or area monitoring on
a regular basis. ' ;
Recovery and The most significant contribution to conservation can be
recycling achieved through reclamation of the blowing agent. CFC-11 is
... becoming more costly: the more a foam manufacturer can obtain
from each pound of CFC-11, the better the investment. An
efficient recovery process able to capture and recycle auxiliary
blowing agents used in the foam reaction may offer time to find
alternatives. Recycling also may make using other auxiliary
blowing agents more economically attractive. The principle of
recovery and recycling is as follows:
Emissions of an auxiliary blowing agent are led through an
adsorption bed. The adsorbed compound is subsequently
stripped by hot gas or vapor, followed by cooling and, if
necessary, separated.
The following systems are available: E-Max, Hypercure, and
Add-On systems to existing equipment.
Regardless of the foam process employed—vertical or horizon-
tal—it is imperative that manufacturers know where auxiliary
blowing agent emissions occur. Best estimates at present
indicate that about 40% is lost on the foam line, 20% at the cutoff
saw and on the transfer conveyor, and the remaining 40% is
Page 18
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Four: Alternatives
Principles of
Activated Carbon
Adsorption
4.1.4.1
being slowly lost during the 12 hours or so that foam blocks
remain in a curing area. CFC-11 can be captured on both
horizontal and vertical foam lines through activated carbon
adsorption. The 40% of emissions from the foam production line
are the most readily captured materials.
The principle of organic solvents adsorption on activated
carbon is well known. It has been used in gas masks, industrial
filters, and for the recovery and recycling of many types of
solvents. Over the last few years carbon adsorption has been
studied as a means to recover and recycle CFC-11 and other
blowing agents from polyurethane foam processes.
Basically, extracted air from the foam process is passed through
activated carbon beds. CFC-11 is adsorbed by the carbon bed
until it becomes fully saturated. The air emerging from the bed
will be essentially clear of CFC-11 since it will have been
removed through carbon adsorption. When the carbon bed be-
comes saturated no further adsorption can occur and CFC-11 is
emitted into the air. The CFC-11 presence is immediately de-
tected by instruments and the extracted air is switched to
another carbon bed.
There are different types of carbon beds and designs which can
be used to adsorb CFC-11 or other types of solvents. The ad-
sorption efficiency of activated carbon is related to its high
surface area. The larger the surface area, the higher the adsorp-
tion efficiency. The amount of CFC-11 or solvent that a given
quantity of carbon can adsorb will depend on the type and grade
of carbon and the concentration of solvent in the air to which the
carbon is exposed. The concentration/adsorption efficiency rela-
tionship is normally expressed as adsorption isotherms.
When a saturated carbon bed is full of CFC-11 or any other
blowing agent, it is ready for desorption. There are a number of
methods for stripping CFC-11 from the activated carbon while
getting efficient, inexpensive carbon bed regeneration. These
methods include:
1. Steam Regeneration;
2. Reversed Brayton Heat Cycle Regeneration; and
3. Nitrogen based Carbon Bed Regeneration.
Without considerable design changes it is not feasible to
adsorb more than about 40% of the auxiliary blowing agent.
Carbon bed adsorption technology has demonstrated a recovery
rate of more than 90% of the adsorbed material. However, the
location of the emissions, as well as the emission rates from the
production and curing of flexible slabstock, are imposing prob-
lems on vapor collection and concentration.
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
Recycling systems
4.1.4.2
E-Max foam systems
4.1.4.2.1
Hypercure/Envirocure
4.1.4.2.2
Recently, there has been consideration given to using a totally
encapsulated foaming line and transfer conveyor in conven-
tional horizontal foam lines. About 60% of CFC-11 emissions
could be recovered on the foam line and the transfer conveyor.
The remaining 40% of CFC-11 emitted during the cure process
continues to present a difficult problem.
The E-Max Process was first presented at the 1987 Polyure-
thane World Conference in Aachen, Germany. Intellectual owner
is Unifoam, Switzerland, who has patented this process world-
wide. Laader-Berg, Norway and Periflex, USA have developed
suitable equipment technology.
Briefly described under section 3.4.1, the process is a blend of
Maxfoam (slabstock) technology. Foam is poured by the Maxfoam
Process in a slab-sized mold and closed immediately afterward.
The mold is connected to a closed loop exhaust system, including
both a sacrificial prefilter and a carbon adsorption unit. This
system traps all emissions and allows subsequent recovery of
the blowing agent.
Because the production of a mold of foam is essentially iden-
tical to a run of slabstock foam, and the yield of a run is directly
related to the run length, the metering technology is of extreme
importance, and should approach those of the molding technol-
ogy in precision and directness. E-Max is an intermittent pro-
duction process.
Although a successful recovery rate of 85% for CFC-11 was
achieved on pilot scale, it should be improved on industrial
scale. Periflex is currently constructing a full size unit that will
be operational and open for demonstration in the second quarter
of 1991.
Hypercure is an add-on technology to the Vertifoam process.
Developed by Hyman, Great Britain, the technology was first
described in 1986 during a conference of the Society of Plastics
Industry.
The Vertifoam technology produces a foam block with a thin,
porous skin, allowing CFCs to be emitted at a faster rate than
traditional or Maxfoam processes. This feature was used as the
base for the so called "rapid cure" system: under continuous
controlled conditions, foam blocks are quickly cooled to ambient
or safe handling temperature. This also provides an opportu-
nity to terminate unreacted isocyanates under controlled con-
ditions, as well as concentrate auxiliary blowing agents for
efficient recovery.
Page 20
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Four: Alternatives
Add-on
recycling systems
4.1.4.2.3
ALTERNATIVE
AUXILIARY
BLOWING AGENTS
4.2
Methylene chloride
4.2.1
The cooling and stripping effect is obtained by forcing air
recirculation through the foam. The system includes a carbon
adsorption system, allowing for the recovery of 85 to 90% of the
total auxiliary blowing agent used.
Add-on recycling for flexible foam was first described in 1985.
Now, several pilot plants have shown its feasibility for Tradi-
tional and Maxfoam equipment, and machine suppliers all over
the world are offering equipment that is suitable for connection
to existing foaming units. These systems are very effective in
the recovery of blowing agents from the process exhaust, but at
best are unproven in their efficiency on emissions from the
curing area. With only about 40% of the auxiliary blowing agent
emitted during production, recapture of only about 35-40% of
the original input is to be expected. Encapturement of the air,
although theoretically possible, has shown to be technically
difficult, cost prohibitive, and less efficient.
However, the ongoing development in this area, combined
with future broader regulations on air emissions, may turn the
tide in favor of this type of conservation.
A technology using the reversed "Braysorb Cycle" may reduce
the need for extensive and expensive carbon beds (Nucon, Co-
lumbus, Ohio). Other adsorbents (DOW), may prove to be more
effective on dilute vapor concentration.
In an era where emissions are subject to scrutiny, and where
conservation efforts are increasingly significant, recovery and
recycling deserve continuing attention.
Alternative blowing agents to CFC-11 include: methylene
chloride, methyl chloroform, HCFCs, acetone, and carbon mon-
oxide (CO), generated through a formic acid reaction via the
"AB" process. These alternatives—assuming all other factors,
such as toxicity and environmental hazards, are satisfactory—
hold some promise for reducing CFC-11 use in flexible polyure-
thane foam manufacturing.
General description
Methylene chloride is a widely used chemical solvent with a
diverse number of applications including use as an auxiliary
blowing agent for flexible slabstock polyurethane foam. Substi-
tuting methylene chloride for CFC-11 is an immediate technical
and commercial option.
Methylene chloride has been used successfully for many years
in the production of flexible slabstock foam. In the U.S., greater
than 70% of the auxiliary blowing agent currently used is
methylene chloride. The cost of methylene chloride is signifi-
cantly less than CFC-11.
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
Methylene chloride has negligible ozone depletion potential,
contribution to acid rain, smog, and global warming. However,
its classification as a "probable human carcinogen" by the U.S.
Environmental Protection Agency (EPA) and others has led to
some restrictions on its use. In many instances, this solvent may
provide the most expeditious manner for eliminating the use of
CFC-11 and come closest to being the one alternative to CFC-11.
However, it is recognized that specific reasons exist in some
geographic areas to mitigate against the use of methylene
chloride. Therefore, manufacturers of flexible polyurethane
foam must find the best alternative for their specific needs and
requirements economically, geographically, and legally.
Principles
Like CFC-11, methylene chloride functions as an auxiliary
blowing agent. It vaporizes from the heat of reaction in the
slabstock foam. This vaporization removes heat from the foam.
The agent increases expansion of the foaming mass to lower the
density and soften the foam. The differences between CFC-11
and methylene chloride include molecular weight and blowing
efficiency, differences which lead to a methylene chloride use
level, in most formulations, of 85% of the CFC-11 use level
replaced.
Remaining within the applicable regulations for methylene
chloride exposure in the workplace is a primary consideration,
as it is for handling all chemicals. However, foam plants are
ventilated to manage TDI exposure; experience has shown that
further modifications for handling methylene chloride vapors
are minor.
Ranges and limits
Methylene chloride can be used worldwide to manufacture all
grades of foam, including supersofts, high resilience (HR), and
combustion modified high resilience (CMHR). Methylene chlo-
ride is routinely used in all types of flexible slabstock foam
production equipment. Supersofts or foams below about TON,
IFD AT 25% using relatively high levels of methylene chloride,
however, have a more narrow processing latitude.
The health effects of methylene chloride have been studied
extensively. Laboratory results have shown an increased inci-
dence of lung and liver cancer in mice, but not in rats or
hamsters. Two epidemiology studies of workers exposed to the
chemical over an extended time have shown no increased overall
risk of cancer. EPA has classified methylene chloride as cat-
egory B2 or a "probable human carcinogen." As a result of this
and other similar agency classifications, there are many local
Page 22
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Four: Alternatives
and national regulations for work place exposure and the emis-
sion of methylene chloride. Foam manufacturers considering a
switch to methylene chloride must first consider the regulatory
impact on a specific plant location.
Changes Required
Because the allowable exposure levels for methylene chloride
are lower than CFC-11, some increase in ventilation may be
required in a plant making a conversion. This has not been
found to be a problem on most foam lines where large volumes
of air are being removed already to control TDI exposure. In the
bun storage room, methylene chloride concentrations are some-
times higher near floor level.
Switching from CFC-11 to methylene chloride requires an
increase in tin catalyst to prevent splits. This tin increase is
usually associated with either a lowering of the amine catalyst
or a switching of amines in instances where processing param-
eters are critical. Except for these minor differences and some
adjustments, methylene chloride can be used as a substitute for
CFC-11.
Availability
Methylene Chloride is available from:
Dow Chemical Co.
LCP Chemicals, Inc.
Occidental Chemical Corp.
Vulcan Materials
ICI, Inc.
Methyl chloroform General description
4.2.2 Methyl chloroform, or 1,1,1-trichloroethane, is a widely used
chemical solvent with a diverse number of applications. It was
recently introduced as an auxiliary blowing agent for flexible
slabstock polyurethane foam. The diversity of state and local
regulations pertaining to the use of CFC-11 and other auxiliary
blowing agents lead to a search for short term alternatives that
could be used with relative simplicity. As flexible slabstock
producers move away from CFC-11 and in areas where methyl-
ene chloride use is not possible, methyl chloroform has provided
a viable solution. Today greater than 10% of the auxiliary
blowing agent used in flexible slabstock in the U.S. is methyl
chloroform. Its ozone depletion potential is 0.1 compared to 1.0
for CFC-11, however, the large global use of methyl chloroform
as a cleaning solvent has lead to a phaseout by the year 2005
under the Montreal Protocol. This technology is, therefore, a
short term bridge from CFC-11 to other solutions.
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
Principles
As an auxiliary blowing agent, methyl chloroform functions in
the same manner as CFC-11. Like CFC-11, methyl chloroform
vaporizes from the heat of reaction in the slabstock foam. The
vaporized blowing agent increases the expansion of the foaming
mass and thereby lowers the density and softens the foam.
Because of differences between CFC-11 and methyl chloroform
molecular weight and blowing efficiency, commercial grades of
foam use 33% more methyl chloroform, by weight, than CFC-11.
Remaining within the applicable regulations for methyl chlo-
roform exposure in the workplace is a primary consideration—
as it is for handling all chemicals. Foam plants are ventilated to
manage TDI exposure, and experience has shown that further
plant modifications for handling methyl chloroform vapors are
negligible. Certainly, no increase in ventilation is expected if
methylene chloride was used previously.
Ranges and limits
Methyl chloroform is used commercially in the U.S to produce
a wide variety of foam grades. Currently at use levels above 20
parts by weight in supersoft grades (below 70N, IFD at 25%), the
processing is difficult, yet possible, if the catalyst adjustments
discussed above are used. In addition, because of the higher
boiling point of methyl chloroform, processing improves in
warmer climates or by using warmer components.
Due to the high volumes used globally and its potential to
contribute to ozone depletion, methyl chloroform has been added
to the list of ozone depleting substances under the Montreal
Protocol, where reductions start in 1995 with a phaseout by
2005. In the U.S., the Clean Air Act and domestic regulations
will require a methyl chloroform phaseout by the year 2002.
Changes required
Since the allowable exposure levels for methyl chloroform are
lower than CFC-11, some increase in ventilation may be re-
quired in a plant making a conversion. This has not been a
problem on most foam lines where large volumes of air are being
removed already to control TDI exposure. In the bun storage
room, methyl chloroform concentrations are sometimes higher
near floor level and require added ventilation.
When switching from CFC-11 to methyl chloroform, an in-
crease in tin catalyst is required. Also, adjustments to—or a
different choice of—amine catalyst will be needed to rebalance
the blowing/gelling reaction. With low density, soft foams
raising the temperature of the polyol, TDI, and methyl chloro-
form to 96°F (35°C) improves the blowing effectiveness of the
Page 24
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Four: Alternatives
methyl chloroform. Except for these minor differences and some
adjustments, methyl chloroform can be used as a substitute for
CFC-11.
Availability
Methyl Chloroform or 1,1,1-trichloroethane is available from
the following companies:
• Dow Chemical Co.
• PPG Industries
• Vulcan Materials
HCFCs General Description
4,2.3 The hydrochlorofluorocarbons, or HCFCs, are a family of
compounds composed of carbon, hydrogen, chlorine and fluo-
rine. The presence of hydrogen in the molecular structures of
HCFCs makes them less stable than fully-halogenated CFCs.
HCFCs are largely broken down in the lower atmosphere, or
troposphere, so that only a fraction of HCFCs emitted will
migrate to the stratosphere. Accordingly, HCFCs have lower
ozone depletion potentials than CFCs. Two HCFCs, HCFC-123
and HCFC-141b, have physical properties similar to those of
CFC-11 and can replace CFC-11 as auxiliary blowing agents in
the production of flexible polyurethane foam. Their ozone
depletion potentials are 0.02 and 0.12 respectively, as compared
to an ODP of 1.0 for CFC-11.
Because of the chlorine contained in these compounds, addi-
tional limits may be imposed on the HCFCs by subsequent
updates of the Montreal Protocol. In the United States, a ban on
non-essential use of HCFCs may become effective at approxi-
mately the same time HCFCs become commercially available in
large quantities.
Principles
Laboratory and plant-scale evaluations of HCFC-123 and
HCFC-141b suggest they can fully replace CFC-11 in flexible
polyurethane foam with only minor adjustments to formula-
tions.
Ranges and limits
HCFC-123 and -141b can be used in virtually all grades of
foam currently blown with CFC-11.
Changes required
Based on currently available information, the changes in foam
processing will be similar to those required for conversion from
CFC-11 to methylene chloride or methyl chloroform. Compat-
ibility of HCFC-123 and 141b with components like seals and
gaskets should always be verified.
Page 25
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
Availability
Toxicity testing of HCFC-123 and HCFC-141b is in progress
under the auspices of the Program for Alternative Fluorocarbon
Toxicity Testing (PAFT) panels with an expected completion
date in 1993. Preliminary results indicate a low order of acute
toxicity and suggest that both compounds can be used in general
industrial areas provided that recommended industrial hygiene
practices are observed. It is likely, however, that the recom-
mended occupational exposure limits for HCFC-123 and HCFC-
141b will be lower than that established for CFC-11.
Both HCFC-123 and HCFC-141b are expected to be in com-
mercial production during 1991-1993. The extent that the HCFCs
will function as replacements for CFC-11 will be dependent on
future regulations and cost considerations. Some of the compa-
nies expected to supply HCFCs include Allied-Signal, ICI,
DuPont and Atochem North America.
Acetone General description
4.2.4 Acetone is widely used as a chemical solvent for a diverse
number of applications. Its low toxicity coupled with high heat
of vaporization led to its recent use as a replacement for CFC-
11 in producing flexible slabstock polyurethane foam. The cost
of Acetone is significantly less than CFC-11.
Acetone has negligible ozone depletion potential, contribution
to acid rain, smog and global warming. However, its relatively
high flammability requires that special precautions must be
taken when acetone is used as an auxiliary blowing agent to
produce flexible slabstock foam.
Principles
Acetone functions in the same manner as other auxiliary
blowing agents such as CFC-11. Like CFC-11, acetone vaporizes
from the heat of reaction in producing a slabstock foam. As the
acetone vaporizes, it increases the expansion of the foaming
mass. The vaporization process helps to cool the foam. Because
of acetone's low molecular weight and high heat of vaporization,
only half as much acetone is required as CFC-11 to achieve the
same relative performance. This relationship is consistent over
the entire range of commercial foam grades.
Ranges and Limits
All flexible polyurethane foam grades produced using CFCs
can be produced using acetone as the auxiliary blowing agent.
Changes Required
Precautions must be taken because of the flammability of
acetone. While typical ventilation required to protect workers
from exposure to TDI emissions during foam production is
Page 26
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Four: Alternatives
TABLE 1
Typical Physical Properties of Alternative Fluorocarbons
Formulation
Molecular Formula
Molecular Weight
Normal Boiling Point (°F>
Vapor Pressure @ 70CF, PSIA
Liquid Density @ 7Q*F, g/cc
Heat of Vaporization, BTU/mole
Vapor Thermal Conductivity
(BTU in./hr.fP>F)
Flame Limits, Volume % In Air
CFC-11
CCLF
137.37
74.9
13.34
1.48
23.47
0.0571
None
HCFC-123
CHOMPS
152.91 3
82,2
11.39
1.47
24.93
0.0722
None
HCFC-141b
CCL/CH.,
i 116.95
1 89,7
10.02
1.24
24.52
0.0696
;7,6-17.7
sufficient to preclude vapor concentrations above its lower ex-
plosive limit (L.E.L.) of 2.6%, ignition sources must be elimi-
nated from the foam tunnel and foam curing area. Some addi-
tional air circulation may be needed near floor-level in the
curing area. To avoid vapor buildup to explosive levels in case of
power failure, a back-up electrical generator should be available.
Availability
Commercially available from many sources, including those
listed as follows:
Allied Signal, Inc.
Airstech Chemical Corporation
Captree Chemical Corporation
Dow Chemical Corporation
General Chemical Corporation
Georgia Gulf Corporation
Hastings Plastics Company
Kem Chemical Corporation
Mallinckrodt, Inc.
Olin Hunt Specialty Products
Primachem, Inc.
Rascher & Betzold, Inc.
Shell Chemical Company
Texaco Chemical Company
Union Carbide Corporation
Unocal Chemicals Division
Veckridge Chemical Company
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
AB technology
4.2.5
Additional information concerning the use of acetone as an
auxiliary blowing agent and the licensing of the technology can
be obtained from Hickory Springs Manufacturing Company,
Hickory, NO, USA.
General description
This technology employs a mixture of formic acid and amine
formates in conjunction with water as the blowing agent for
producing flexible polyurethane foam. No CFCs or other auxil-
iary blowing agents are used for most conventional foam grades
above about 21 kg/m3 while reduced CFG levels may be used in
many lower density grades. Equipment and procedural modifi-
cations are generally required to store and handle the acid
mixture and to insure that the carbon monoxide produced dur-
ing foam production does not exceed threshold levels.
Principles
The key to this technology is the formic acid and amine
formate blowing agent. The AB process is based on using the
reaction of formic acid with an isocyanate in addition to the
water/isocyanate reaction normally used to generate gas for the
expansion of foam. The formic acid reaction doubles the quan-
tity of gas generated in the reaction of isocyanate with water.
Since this reaction yields two moles of blowing gas (CO and CO2)
instead of one, it is more efficient than water as a blowing agent.
In fact, this additional gas formation reduces the need for inert
blowing agents, such as CFC-11.
The equation shown below indicates that only half the amount
of urea groups are formed for a given volume of gas. The AB
foams are therefore softer than all water-blown foams. This
reaction results in foam softening. Low density firm grades will
generally require the continued use of some auxiliary blowing
agent for cooling since poor compression sets have limited the
volume of formic acid or salts which can be used. A special
amine catalyst and surfactant are recommended for use in the
AB technology.
H-O-H +
water
HCOOH +
formic acid
2NCO »
isocyanate
2NCO »
isocyanate
•NH-CO-NH +
urea group
•NH-CO-NH +
urea group
C02
gas
co?
gas
+ CO
: gas
Page 28
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Four: Alternatives
Ranges and limits
There is a limitation on the lowest attainable foam density
because the reaction with formic acid, as with water, is exother-
mic and care is necessary to avoid scorch or fire risk. Initial data
suggests that the densities achievable may be slightly depen-
dent upon the process machinery. Foams with densities ranging
from 17 kg/m3 to 22 kg/m3 have been achieved by some manu-
facturers without the use of CFC-11 or other auxiliary blowing
agents.
To make firm foam of a density of 15 kg/m3 using AB tech-
nology, between 5 and 10 parts of CFC-11 are necessary com-
pared to the usage of approximately 15 parts of CFC-11 with
conventional foam technology. The specific reduction possible
will depend upon the product being manufactured. However,
manufacturers using the AB process have not detected any
significant difference in product quality. AB technology is not
limited to combinations with CFC-11 but will work with other
auxiliary blowing agents, as well.
Changes required
The modified AB process being offered uses a mixture of
formic acid and amine formates that requires care in handling.
It has a pH of 3 and requires vessels, pumps, and pipework to be
made from acid-resistant steel or appropriate plastic.
As the chemical blowing agent, the AB process generates 50
percent carbon monoxide. Care must be taken to ensure the
safety of operators. Carbon monoxide is highly toxic and is an
accumulative poison. In many countries, the permissible levels
of exposure are 50 ppm or below for an 8-hour exposure, with
short-term ten-minute levels of 400 ppm or below.
The carbon monoxide concentrations do not represent a major
problem in the main conveyor section of a flexible foam slabs tock
machine where the ventilation is of high efficiency to maintain
safe working levels of TDI. Concentrations of CO in this section
of the conveyor can be a few hundred ppm; in the cure room,
however, CO must be ventilated to maintain safe work levels.
A substantial percentage of the CO is emitted at the cut-off
saw, foam cure, and storage areas, where ventilation is not as
efficient as on the foam line itself. Additional ventilation would
need to be installed in most factories. Ideally mechanical
handling into large open-sided storage areas is the solution, but
for many plants the climate of the area and limitations imposed
by plant layout prohibit this solution.
Page 29
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
Other alternatives
4.2.6
ALTERNATIVE
PATHS TO FOAM
SOFTENING
4.3
Modified HR Foams
4.3.1
Ultracel™ technology
4.3.1.1
UltraceP1 is a trademark ol AC
West Virginia Polyol Company
Automatic analytical monitoring equipment for CO is essen-
tial both for fixed area monitoring and portable monitoring.
Availability
This technology is offered under a licensing agreement from
The Goldschmidt AG, Essen West Germany.
There have been several attempts to make more efficient use
of the primary blowing agent for flexible foam, which is carbon
dioxide. The efforts include the increase of blowing efficiency
by reduced processing pressure and by the saturation of each
material by CO2 prior to processing. Currently, none of the
methods have exceeded the pilot stage, and therefore can not be
considered existing alternatives.
Foam softening technology, in contrast to foam density reduc-
tion technology, has improved. Almost all foam softening
mechanisms involve alteration of the basic foam chemistry
process. The wide range of foam softening alternatives avail-
able is thoroughly reviewed in this manual.
Mechanical devices help auxiliary blowing agents achieve
both density reduction and softening in the foam product made
by the slabstock manufacturing method. The mechanical ap-
proach could permit the use of auxiliary blowing agents that
might be banned by virtue of other regulatory limitations. Such
mechanical devices which aid in the manufacture of flexible
polyurethane foam, the reduction of auxiliary blowing agent
emissions, and ultimately, the capture and recycling of those
emissions, are also reviewed in the Handbook.
There is no one absolute alternative to the use of CFC-11 as an
auxiliary blowing agent. This does not diminish the necessity of
replacing the use of CFC-11, nor does it make the task any
easier. It does require that each individual situation be re-
viewed and a unique course of action, suited to that situation, be
pursued.
General Description
Modified HR Systems allow the production of a wide range of
densities and IFDs without the use of blowing agents.
Ultracel™ slabstock technology can be used in essentially all
standard firmness grades of flexible polyurethane foam. Al-
though similar to previous high resilience slabstock technolo-
gies, Ultracel™ yields foams with high resilience, good comfort,
recovery and durability over a broader load and density range.
Ultracel™ CM foams can meet the new stringent combustibility
standards. This foam is used in furniture, mattresses, automo-
tive seating, carpet underlay and other applications calling for
heavy or moderate duty performance.
Page 30
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Four: Alternatives
Resteasy Plus™
4.3.1.2
Resteasy Plus™ is a trademark
of BASF, Inc.
Principles
Foam softening is achieved through the increased use of a
foam modifying/stabilizing agent (typically diethanolamine), a
reduction in the isocyanate index, and cell structure control.
Ultracel™ chemical intermediates (polymer polyol, surfactant
and amine catalyst) provide processing stability over the
broadened formulating range and improve the performance
properties of the foams. A high load polymer polyol is added to
produce higher firmness grades.
Ranges and limits
The lowest foam density achievable with the Ultracel™
technology without employing auxiliary blowing agents is lim-
ited to about 21 kg/m3 due to foam exotherm considerations.
Supersoft to high load grades can be produced as well as HR and
Combustion Modified HR (CMHR) grades.
Changes Required
Ultracel™ foam can be processed on all types of standard foam
equipment with minimal modifications. Most facilities may
need to provide tankage for the Ultracel™ intermediates.
Availability
Ultracel™ technology is available under licensing agreement
from AC West Virginia Polyol Company.
General description
Resteasy Plus™ technology was developed for slabstock foams
with a full range of firmness grades and no auxiliary blowing
agents. Supersoft to firm carpet underlay foams are produced
with high resilience foams having a much broader range of
firmness and improved performance properties. These foams
exhibit excellent resilience, durability and comfort properties
and can be formulated to meet combustibility requirements for
furniture, bedding and carpet underlay applications.
Principles
Resteasy™ polyols in optimized high resilience formulations
allow low isocyanate index to produce soft grades of foam with
excellent processing latitude and properties. These polyols also
produce medium firmness grades to meet most furniture and
bedding applications by formulation adjustments. Very firm
grades of foam for carpet underlay are produced with a high load
polymer polyol in the formulation.
flanges and Limits
The foams are produced at densities of 24 kg/m3 or higher at
all firmness grades and without auxiliary blowing agents. Pro-
duction of lower densities are possible but core discoloration
will occur in large production buns due to the high bun exotherms.
Page 31
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
Changes Required
Resteasy Plus™ has been produced on all types of production
slabstock machines. Facilities with high resilience foams do not
require any changes and can use most types of auxiliary compo-
nents. Other facilities may need to provide additional tankage.
Availability
Resteasy Plus™ polyols and technology is available from BASF
Corporation, U.S.A.
Extended range General description
conventional polyols The extended range conventional polyols do not function as
43 2 auxiliary blowing agents in flexible slabstock foam and do not
by themselves lower density. These polyols do, however, lower
the foam hardness. Therefore, compared to a CFC-11 blown
foam the water level must be increased to lower the density
when using extended range polyols. These polyols are either
used to replace the current conventional polyol or are blended
with it. At this writing there is no commercial extended range
conventional polyol which will allow the total elimination of
CFC-11 from all grades of conventional foam. Some products
allow a 6 to 8 parts CFC-11 reduction by weight. Others allow
the total elimination of CFC-11 from supersofts but are not
capable of making the intermediate grades of foam.
Principles
Extended range conventional polyols are used as total or
partial replacement of the polyol used to make a given foam
grade. The extended range polyol and water are used to match
the hardness of the original formulation after reducing or
eliminating CFC-11. There are two types of extended range
polyols in commercial use today:
1. Polyols whose functionality, molecular weight, or effect on
polymer morphology lead to the production of softer foam.
These polyols are run at normal processing conditions and
TDI indexes. Most of these polyols allow the production of an
equivalent foam with 4 to 8 parts less CFC-11. Due to
exotherm limitations, lower density foams without CFC-11
are not possible.
2. Polyols whose reactivity allow the production of foams at
lower than normal index lead to the production of softer
foam. These polyols, when run at low index, decrease the
foam hardness while lowering foam exotherm temperatures,
allowing higher water levels and lower densities to be pro-
duced. Some of these polyols allow the production of low
density supersoft foam (16 kg/m3, 70 N, IFD at 25%) with no
CFC-11 while others allow the production of higher density
intermediate hardness grades, (125 N IFD) with no CFC-11.
Page 32
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Four: Alternatives
Ortegol™3lO
4.3.3
Ortegof™ is a registered
trademark of the
Gold schmidt AG.
When needed these extended range conventional polyols can
be used in conjunction with alternative blowing agents and with
softening additives such as ORTEGOL™ 310.
Ranges and limits
There are extended range conventional polyols available com-
mercially which allow the production of the majority of the foam
grades with the possible exception of very low density, (less than
21 kg/m3), and intermediate hardness (125 N IFD). Currently,
no one polyol covers all foam grades. Each has limitations in
blend level, index, or water level which restricts its use.
Changes required
The changes necessary to use a specific polyol or system of
polyols will depend upon the polyurethane foam manufacturers
selection of polyols and upon the physical availability of bulk
storage and metering systems. The chemical changes needed
will generally be recommended by polyol manufacturers. The
mechanical changes will depend upon how many polyols and/or
additives are needed to make the range of products desired in
the local market. Tanks and metering systems will have to be
installed if existing systems can not be made available.
Availability
Extended range conventional polyols available are:
VORANOL 3583 polyol, Dow Chemical, U.S.A. (VORANOL is
a registered trademark of the Dow Chemical Co.)
XUS15216.01 polyol, Dow Chemical, U.S.A.
XUS15241.00 polyol, Dow Chemical, U.S.A
XZ94532.00 polyol, Dow Chemical, Europe
CP 1421 polyol, Dow Chemical, Europe
XZ82229.00 polyol, Dow Chemical, Pacific
THANOL F-1500, Arco Chemical (THANOL is a registered
trademark of Arco Chemical).
General description
Ortegol™ 310 is not an auxiliary blowing agent and does not
lower density. It does, however, lower the foam hardness.
Therefore, compared to a CFC-11 blown foam, the water level
and, correspondingly the parts of TDI, must be increased to
lower the density when using Ortegol™ 310. It is used as an
additive at levels up to approximately one part by weight and
will allow the reduction of 6 to 8 parts CFC-11. This reduction
Page 33
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
does not allow the total elimination of CFC-11 in all cases but
Ortegol™ 310 can be used in combination with CFC-11, or other
auxiliary blowing agents.
Principles
Ortegol™ 310 is an additive that can be used in flexible
slabstock formulations in the range of 1.0 part by weight of
polyol. At this level the hardness of the foam is reduced by
approximately 15 to 35%. Ortegol™ 310 is a reactive additive in
a water solution so that formulations need to be adjusted for the
TDI demand and the added water. Ortegol™ 310 can be used to
match the foam hardness in the formulations where CFC-11 is
reduced or eliminated. The density must be adjusted by in-
creased water as Ortegol™ 310 does not effect that character-
istic. By adding 1.0 part Ortegol™ 310 and increasing the H2O
level 0.8 parts an equivalent foam can be made with 8 parts less
CFC-11. Only minor adjustments need to be made in formula-
tion when processing foam inside it's use range. In an average
U.S. foam plant the use of Ortegol™ 310 can result in a 50%
overall reduction in CFC-11 consumption. Ortegol™ 310 may be
used in conjunction with extended IFD range conventional
polyols to achieve further reductions.
Ranges and limits
In higher density foam grades the primary function of CFC-11
is to soften foam. In lower density grades the CFC-11 plays a
key role in cooling the foam made with high water and the
resulting high exotherm. The range of grades made with
Ortegol™ 310 and no CFC-11 is therefore limited by the degree
of softening available and the fact that no cooling comes from
it's use. In foam grades above 21 kg/m3 and 110N, IFD (at 25%
Deflection) the use of Ortegol™ 310 can eliminate the use of
CFC-11. For IFD's below that, some CFC-11 will still be needed
to achieve the target hardness. In grades below 21 kg/m3 some
CFC-11 will still be needed to cool the foam exotherm. The
developer, Goldschmidt, AG recommends that when using
Ortegol™ 310 that the TDI index be maintained below 110.
Changes required
The use of Ortegol™ 310 will require a separate delivery stream
for bringing the additive to the mix head. Some plants have the
required extra additive stream, others will have to purchase
and install the equipment.
The use of Ortegol™ 310 will require reformulation of the
foam grades using CFC-11 with added water and lower CFC-11.
As with any significant change in technology, a learning curve
will be required to fine tune the formulations for individual
plant locations.
Page 34
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Four: Alternatives
Geolite™ technology
4.3.4
Geolite™ /* a registered
trademark of Union Carbide
Corporation
Unilink«4200
4.3.5
Unlllnk* Is a registered
trademark of UOP
Availability
Ortegol™ 310 is available from:
Goldschmidt Chemical Corp, Hopewell, Virginia, U.S.A
The Goldschmidt AG, Essen, West Germany.
General description
Geolite™ slabstock foam technology can be used to produce
polyurethane foam grades without auxiliary blowing agents. It
can also be used in conjunction with reduced levels of methylene
chloride or methyl chloroform to fully replace CFCs in many
other grades. Foam processing and performance properties are
similar to conventional flexible foam manufactured with full
levels of CFCs or other auxiliary blowing agents.
Principles
The key to the Geolite™ technology is a proprietary chemical
modifier which acts to soften the foam and enable processing at
lower isocyanate indexes (thus providing additional softening).
The modifier can be employed with most conventional foam
systems that are currently being used and typically does not
require the use of any other specific chemical intermediates.
Ranges and limits
Geolite™ can fully replace CFCs in the production of foams
having densities above about 21 kg/m3 and 25% IFDs down to
about 116 N. It can partially replace CFCs or other auxiliary
blowing agents in the production of softer grades and lower
density soft grades.
Changes required
Geolite™ foams can be produced on all standard foam produc-
tion equipment. No equipment modifications are usually re-
quired though a small tank and metering pump are recom-
mended.
Aval lability
Geolite™ is available from Union Carbide Corporation.
General description
Unilink® 4200 is a low viscosity, liquid aromatic secondary
diamine which is used as a chain extender in polyurethane
foams. It is non-volatile and does not contribute to the blowing
action of the foam. It does, however, capture more of the CO2
generated in the water/isocyanate reaction making more effi-
cient use of the blowing agent. This improvement in efficiency is
also observed when Unilink* 4200 is used with auxiliary blow-
ing agents including CFCs and HCFCs.
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
Principles
Unilink* 4200 is a blowing efficiency enhancer. That is, the
addition of Unilink* 4200 produces a lower density foam at the
same water level. At recommended use levels of 5 php, Unilink*
4200 may reduce the density of a TDI foam by 5-15%, and of an
MDI foam by 15-30%.
Unilink* 4200 also alters the morphology of the polyurethane
polymer structure. In MDI foams the hardness of the foam will
be reduced by 30-50%. At 5 php, Unilink* 4200 has been shown
to replace 12 php of CFC-11 resulting in MDI molded foams of
equal density, hardness and strength. In TDI foams, Unilink*
4200 will increase the foam hardness. Unilink* 4200 can be used
in conjunction with chemical softening agents to give TDI foams
of both lower density and lower hardness.
Ranges and limits
The recommended use level of Unilink* 4200 is between 3 and
5 php. This level results in the best balance among density and
hardness reduction, and strength properties. Higher levels may
result in poor compression sets.
Unilink® 4200 works best at replacing CFCs in MDI molded
foams, resulting in both lower hardness and density. In TDI
foams, Unilink* 4200 is effective at lowering the foam density,
but increases the hardness of the foam. Unilink* 4200 may be
used with other chemical softening agents to achieve both lower
density and hardness.
Changes required
Unilink* 4200 can be used on all conventional production
equipment.
Availability
Unilink* 4200 is available from:
UOP, Des Plaines, Illinois 60017
SUMMARY A summary of alternatives for the flexible foam producer
4 4 discussed in this chapter is outlined in the attached matrix
(Table 2). Since no one technology currently solves all of the
problems with replacing CFC-11, it is critical that the alterna-
tive selected is reviewed, in detail, with a supplier to ensure the
specific advantages and disadvantages of the alternative tech-
nology adequately addresses the polyurethane foam
manufacturer's production needs. Following the guidelines in
Chapter 5 can help manufacturers narrow their choices, to
ensure the appropriate alternative for an individual product
mix and foaming environment.
Page 36
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Four: Alternatives
TABLE 2
Flexible Polyurethane Foam Options
Options
Methylene
Chloride
Methyl
Chloroform
HCFCs
Acetone
AB
Technology
Modified HR
Foam
Ultracel™
RestEasy Plus™
Ortegol™310
Extended
Range
Polyol
Geolite™
Technology
CFC
Replacement
100%
100%
100%
100%
Up to 100%
50%
Variable
50% avg
Variable
Variable
OOP
0.10
HCFC141b = .12
HCFC123 = .02
Density Range
Applicable
Same as CFC
range
Same as CFC
range
Same as CFC
range
Same as CFC
range
17kg/m3"
ISkg/m3
21kg/m3
>21 kg/m3
Density range**/"*
Density range**/***
>2t kg/m3
>21 kg/m3
Density range**/***
Equipment
Modifications
Minimal
Improved
ventilation
None
Improved
ventilation,
remove spark
sources
Non-corrosive
equipment,
improved
ventilation
Minimal
None
Extra Tankage
likely
None
License
Needed?
No
Not at
this time
No
Yes
Yes
Yes
No
No
Yes
Limitations/
Concerns
Local regulatory
constraints
Phase-out by 2002
Not yet
commercially
produced;
increased price;
probable
phase-out
Flammability of
acetone
Corrosive
chemistry; Carbon
Monoxide
emissions
Primarily for
high
performance
grade
Foam softener
only
No one polyol
system covers all
foam grades,
mainly for foam
softening
Mainly used for
foam softening
* Processing at high levels of auxiliary blowing agent difficult
** Maximum replacement approximately 7 php CFC-11.
*** Not applicable in cases where the auxiliary blowing agent is used to reduce the exotherm.
Page 37
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ive:Me
Once the manufacturing facility is ready to make a selection
of alternative (replacement) technology, a structured process
should be followed to ensure that the most efficient and appli-
cable selection is made for a particular set of circumstances. It
should be remembered that the purpose of an auxiliary blowing
agent, in the flexible foam manufacturing process is:
-to lower reaction exotherm
-to soften the foam
-to reduce density
The choice of alternative technology should accomplish these
objectives while maintaining acceptable physical properties.
Safety is a primary concern when choosing an alternative to
CFCs in any process (Chapter 4). Factors such as toxicity to
humans, and fire or explosion characteristics must be studied
and considered. At no time should employees of facilities be
placed in danger by a chemical in the work place.
Figure 7 depicts the sequence of steps that should be followed
when choosing an alternative technology. Figure 8 shows steps
to be followed in analyzing an option for effectiveness.
The first step is to review current practices and housekeeping
to eliminate unnecessary use of auxiliary blowing agent (Chap-
ter 4). The next step is to list all available alternatives in order
to know what field the selection is to be made from. This list
should include alternative auxiliary blowing agents, chemical
modifications, recycling and re-use. A careful review of market
requirements will help a great deal in selection, as those re-
quirements will determine the level of alternative technology
necessary (Chapter 3). At the same time, a review of manufac-
turing and process capabilities in relation to product mix should
be conducted. In addition, a review of regulatory and safety
issues affecting all options is appropriate.
Once all reviews are complete, a list of alternatives should be
developed based on all considerations (the technical analysis)
(Chapter 4). Initially, a cost analysis should be done for each
option to determine the economic feasibility. The cost will vary
considerably depending on location. The analysis should include
all costs of conversion including capital outlay and operating
expenses, as well as product cost, if applicable, control technology
(processing and emission), and any additional processing costs
(licensing fees, etc.).
Page 39
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
Based on all these factors, a primary selection of alternative
technologies can be made. Once the selection has been made, the
program proceeds to the action phase.
Adequate support must be assured from a technical stand-
point, which generally includes technical service support from
suppliers, licensing groups, and perhaps equipment manufac-
turers. At the same time, regulatory approvals must be ob-
tained, if necessary. Once assistance is lined up and regulatory
approvals are granted, the test program is outlined.
A good scientific approach to trials leads to logical, support-
able conclusions which are essential to success. Trials take
place with the assistance of technical support personnel. An
evaluation, based on pre-planned parameters, is done to deter-
mine the success of the trial. If the trial is successful, the
conversion should begin. If it is unsuccessful, a thorough inves-
tigation of the failure mode should lead to conclusions about
whether to reevaluate the same option, or to make a secondary
selection of alternative technology. If another selection is made,
the action phase is repeated for the new alternative. If this step
by step methodology is followed, a smooth, orderly, tran-
sition to a new technology can be assured.
Finally, manufacturers can be confident that all aspects have
been considered, and that the final result is truly the best
alternative for each unique set of circumstances, at the most
economically feasible costs.
Page 40
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Five: Methodology for Selection
FIGURE 7
Methodology for Selection of Alternative Technology
Preparation/Selection
/^Perform Housekeeping*^
I Practice good conservation 1
V - check for leaks in storage tanks, I
piping and metering units ^^^
List Alternatives
- methylene chloride
- methyl chloroform
- HCFCs
- Acetone
- AB Technology
- Modified HR Technology
- Extended Range....
conventional polyols
- OrtegolSlO
- Geolite technology
,- Unilink
Review Requirements
/ Market Requirements
/ - determine what the local
\ end-use market needs; consider
\ foam softness and density
Process and Manufacturing
Environment
Consider:
- temperature
- barometric pressure
- altitude
Regulatory
• local, state or federal regulations
may deter use of certain blowing
agents
Safety
- eliminate fire hazards
- protect against exposure
to hazardous chemicals
Technical Analysis
determine range and limitations
Economic Analysis
Evaluate costs of conversion
- capital outlay
- operating expenses
- product costs
- control technology
- other processing costs
- licensing costs
Page 41
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Handbook for Reducing and Eliminating
Chlorofluorocarbons in Flexible Polyurethane Foams
FIGURES
Methodology for Selection of Alternative Technology
Primary
Choice
_L
Assure
Technical
Assistance
Obtain
Regulatory
Approval
SetUp
Test
Program
Make
Next
Choice
Solve
Problem?
Failure
Mode
Convert All
Formulations to
New Technology
Page 42
-------
References
Almqvist, K.A, CFCElimination in Flexible Molded PU-Foam
for Furniture and Automotive Applications, POLYURETHANES
90, Proceedings of the SPI-33rd Annual Technical/Marketing
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Andrechak, J. A., and D.B. Parrish, Flexible Polyurethane Foam
Density Reduction without Benefit of Chlorofluorocarbons,
POLYURETHANES 88, Proceedings of the SPI-31st Annual
Technical/Marketing Conference, October 18-21, 1988, Phila-
delphia, PA.
Creazzo, J.A., P.L. Bartlett and M.R. Ascough,7Yie Dupont
Program on Alternative Blowing Agents for Polyurethane Foams-
Recent Develpoments, POLYURETHANES 88, Proceedings of
the SPI-31st Annual Technical/Marketing Conference, October
18-21, 1988, Philadelphia, PA.
Crooker, R.M., and M.Y. Elsheikh, Accelerated Aging Study of
HCFC 141b in Polyurethane Premixes, POLYURETHANES 88,
Proceedings of the SPI-31st Annual Technical/Marketing Con-
ference, October 18-21, 1988, Philadelphia, PA.
Den Boer, J. and P. Marie, A Novel Approach for the Produc-
tion of CFC Free Soft Flexible Slabstock Foams at 20-30 kglm3
Foam Density, POLYURETHANES 90, Proceedings of the SPI-
33rd Annual Technical/Marketing Conference, Sept. 30-Oct. 3,
1990, Orlando, FL.
Dishart, K. T., J.A. Creazzo and M.R. Ascough, The DuPont
Program on Fluorocarbon Alternative Blowing Agents for Poly-
urethane Foams, POLYURETHANES WORLD CONGRESS 1987:
50 YEARS OF POLYURETHANES, Proceedings of the FSK/SPI,
September 29-October 2, 1987, Aachen, Germany.
Dwyer, F.J., L.M. Zwolinski, and J.M. Garman, Storage Sta-
bility of CFC IPolyol Premixes, POLYURETHANES: EXPLOR-
ING NEW HORIZONS, Proceedings of the SPI-30th Annual
Technical Marketing Conference, October 15-17,1986, Toronto,
Canada.
Hennington, R.M., V. Zellmer, and M. Klincke, Soft Flexible
Polyurethane Foam without Auxiliary Blowing Agents, POLY-
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Handbook for Reducing and Eliminating
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Hicks, J.S., A.K. Schrock, M.K. Hunter, F.E. Parks, E.P.
Wiltz, and D.B. Parrish, Polyol Technologies to Reduce or
Eliminate Use of CFCs in Flexible Slabstock Foams, POLY-
URETHANES 90, Proceedings of the SPI-33rd Annual Techni-
cal/Marketing Conference, Sept. 30-Oct. 3, 1990, Orlando, FL.
House, D.W., R.V. Scott, and M.J. Gattuso, A New Replace-
ment for Chlorofluorocarbons in MDI-Based Polyurethane Foams,
POLYURETHANES 90, Proceedings of the SPI-33rd Annual
Technical/Marketing Conference, Sept 30-Oct. 3,1990, Orlando,
FL.
Knopeck, G.M., L.M. Zwolinski, and R. Selznick, An Evalua-
tion of Carbon Adsorption for Emissions Control and CFC-11
Recovery in Polyurethane Foam Processes, POLYURETHANES
88, Proceedings of the SPI-31st Annual Technical/Marketing
Conference, October 18-21, 1988, Philadelphia, PA.
Lambach, J.L. and W.A. Gill, Hot Foam Replacement with Non-
CFCHR Foam, POLYURETHANES 90, Proceedings of the SPI-
33rd Annual Technical/Marketing Conference, Sept. 30-Oct.
3, 1990, Orlando, FL.
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