United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S2-88/004 Mar. 1988
&ERA Project Summary
Control Technology Overview
Report: CFC-11 Emissions from
Flexible Polyurethane Foam
Manufacturing
R. W. Farmer and T. P. Nelson
An engineering evaluation of techni-
cal options to reduce chlorofluorocar-
bon (CFC) emissions from flexible
slabstock and molded polyurethane
foam manufacturing plants was per-
formed. Included in the technical
options examined were recovery and
recycle of CFC-11, alternative chem-
icals and processes, and substitute
products. Two possible emission con-
trol methods were studied in detail:
substitution of methylene chloride as
the auxiliary foam blowing agent and
carbon adsorption/recycle of ex-
hausted CFC-11 vapors. Promising
near-term control options identified for
slabstock production were methylene
chloride substitution for CFC-11, and
establishment of a minimum foam
density to reduce the amount of aux-
iliary blowing agent used. For molded
polyurethane foam production, use of
chemical systems which eliminate the
need for auxiliary blowing agents
appeared to be a near-term option.
Possible longer-term options included
carbon adsorption with CFC-11 recov-
ery, development of chemical systems
requiring little or no auxiliary blowing
agents for slabstock production, and
commercialization of new alternative
blowing agents. Each of the longer-
term options has in common a need for
additional information to adequately
define the optimal implementation
strategy.
This Project Summary was devel-
oped by EPA's Air and Energy Engi-
neering Research Laboratory, Research
Triangle Park, NC, to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report
ordering information at back).
Introduction
Over the past decade, potential deple-
tion of stratospheric ozone through the
action of fully halogenated chlorofluoro-
carbons (CFCs) has been the subject of
extensive study. This phenomenon
involves complicated chemical interac-
tions that are driven by ultraviolet (UV)
radiation and occur in the upper atmos-
phere. Not only are the interactions
extremely complex, but direct observa-
tions of them are difficult.
An important aspect of the strato-
spheric ozone depletion issue is the lag
time between emission of CFCs into the
environment and their ultimate arrival in
the upper atmosphere. Since fully hal-
ogenated CFCs are not readily decom-
posed in the troposphere, they remain
stable for the long time required for
transport to the stratosphere. Because of
this extended transport period, effects of
current emissions are not manifested
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until several decades later. Once in the
stratosphere, these compounds can be
acted upon by UV radiation of the proper
wavelengths to release chlorine species
that in turn contribute to destruction of
ozone. Depletion of the earth's protective
layer of stratospheric ozone is predicted
to result in increased biologically dam-
aging UV radiation's reaching the earth's
surface.
CFCs are widely used in several
industries including flexible polyure-
thane foam manufacturing. In that
industry, CFC-11 (fluorotrichlorome-
thane) is used as a physical blowing
agent to reduce foam density and
increase softness. Another key role of the
CFC-11 is to dissipate heat generated by
the polyurethane formation reactions
thereby controlling foam temperature
during formation and curing.
Emissions of CFC-11 from the flexible
foam manufacturing process are charac-
terized as being prompt; i.e., all of the
gas is released during, or soon after,
foam formation. It is estimated that
flexible foam production accounts for
about 30% of the cumulative CFC-11
which has been released into the
atmosphere.
The objective of this project was to
evaluate technical options to reduce
emissions of CFC-11 from flexible foam
plants. In this overview study, the depth
of technical evaluation was limited, in
some cases, by the information available
on each technology. However, two pos-
sible emission control methods were
extensively studied: substitution of
methylene chloride for CFC-11 as an
auxiliary blowing agent and carbon
adsorption/recycle of exhausted CFC-11
vapors. Also, an important component of
this study was to summarize recent
innovations in foam technology which
have the potential to reduce or eliminate
CFC-11 use.
Accomplishments/Results
Control methods under the heading of
capture/destruction or capture/recycle
techniques include carbon adsorption of
CFC-11, thermal or catalytic incineration,
liquid absorption, and direct vapor
condensation. Pilot tests have shown
that carbon adsorption may be feasible
for CFC-11 control. However, a number
of technical issues have not been satis-
factorily resolved, including fouling of the
carbon bed by isocyanate residue, quality
of recycled CFC, and disposal of used
carbon and steam condensate. The
remaining control methods in this cate-
gory presently suffer from either high
cost or a preponderance of negative
technical factors which would prevent
their application for flexible foam plants.
The cost effectiveness of carbon
adsorption/recycle was found to be
highly variable, depending on the CFC-
11 market price, recovery efficiency,
facility size, and required capital invest-
ment. It is felt that this control method
is more applicable to slabstock facilities
than molded foam plants due to poten-
tially more efficient capture of released
blowing agent from the slabstock pro-
cess. High capital costs are a substantial
barrier to implementation, because the
competitive nature of the foam business
makes it difficult for producers to commit
large sums of capital. It would also be
difficult to offset annualized operating
costs through the recovery credit for
recycled CFC-11 unless the price of CFC-
11 were to increase substantially.
The near-term possibility of methylene
chloride conversion as a CFC-11 control
measure is excellent, since most slab-
stock producers now employ this tech-
nology. It is estimated that as much as
70% of all flexible slabstock foam could
be produced using this alternative blow-
ing agent. Full conversion to methylene
chloride generally requires some expen-
diture for foam reformulation and plant
modification such as improved ventila-
tion in foam curing areas. These costs
and the increased difficulty in producing
quality low density, soft foams with
methylene chloride are potential imped-
iments for such conversion. Therefore,
it is possible that a fraction of the low
density foam market would disappear if
CFC-11 were no longer available. There
is also a strong preference on the part
of some producers to avoid methylene
chloride owing to its own current reg-
ulatory uncertainty.
Alternative CFCs having ozone deple-
tion potentials lower than CFC-11 are a
promising long-term control method.
Two primary candidates are CFC-123 and
CFC-141 b. CFC-123 appears to be both
reasonably safe and technically feasible;
however, CFC-123 production costs are
expected to be higher than for CFC-11
resulting in a bulk sales price roughly two
to four times that of CFC-11. Also, there
is no commercial scale production of
CFC-123 in the U.S. at the present time.
Safety considerations are the major
drawback of CFC-141 b in foam blowing
applications. Flexible foam blowing
agents should have lowflammability and
low toxicity, since their vapors are
usually present in detectable concentral
tions in the plant environment. Toxico-
logical testing on CFC-141 b has not been
completed; but current reports indicate
that the compound is a "weak mutagen."
In addition, CFC-141 b is reportedly more
flammable than other substitute flexible
foam blowing agents. Chemical produc-
ers have indicated that, without market
incentives to produce CFC-123 or CFC-
141 b, commercialization is unlikely and
that even if initiated, from 5 to 7 years
would be required for the chemical to be
commercially available.
Several recent innovations in the area
of molded polyurethane foam chemical
systems could ultimately reduce or
eliminate the need for auxiliary blowing
agents for these foams. In general, these
newer systems utilize established HR
(high-resilience) auxiliary blowing agent
technology, but permit foam production
without CFC-11. These systems employ
either conventional toluene diisocyanate
(TDI) reagents, or a class of isocyanates
referred to as MDI (methylene diphenyl
isocyanate) compounds, and families of
more reactive polyols. It is not currently
possible to economically achieve U.S.
auto seat specifications using so-called
"water-blown" MDI-based formulations.
But, TID-based water-blown systems are
available that can produce all currently
used molded foam grades. Only slightly
increased raw material costs are antic-
ipated for these systems.
New chemical systems have also beer
introduced which would permit produc-
tion of softer slabstock foams without the
use of auxiliary blowing agents, but such
systems have yet to be able to produce
the super-soft, low density foams. These
systems employ more reactive, anc
generally more expensive, polyols, and/
or polyol blends.
Another slabstock process which coulc
reduce the need for CFC-11 blowinc
agent has been developed in Belgium
and is currently licensed by Innocherr
S.A. in Switzerland. This process, knowr
as the "AB Process," is claimed to b«
applicable to a range of slabstock grades
and some molded foam components, anc
substitutes formic acid for some of th(
water in the foam formulation. Th<
chemical reactions release twice th<
volume of blowing gas as with conven
tional chemistry, but the additional gas
released is CO. Since CO is a recognize(
toxic gas, extra monitoring and safef
precautions are necessary. Further
handling of the concentrated formic aci<
involves special ventilation requirement!
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and materials of construction. There
have been no reported full-scale appli-
cations, but some testing of this process
has been carried out in Europe.
In addition to the technological con-
trols discussed above, several product
substitutes could be used in place of
polyurethane foam for certain applica-
tions. Given appropriate market condi-
tions, materials such as jute, cotton
batting, and latex foam could once again
command a portion of the cushioning
market that they once enjoyed prior to
the development of flexible polyurethane
foam. Replacement of polyurethane
foams by such materials would likely
occur only if CFC-11 and methylene
chloride emissions were both regulated,
thus increasing the costs of the low
density polyurethane foam grades.
R. W. Farmer and T. P. Nelson are with Radian Corp., Austin, TX 78720.
N. Dean Smith is the EPA Project Officer (see below).
The complete report, entitled "Control Technology Overview Report: CHC-11
Emissions from Flexible Polyurethane Foam Manufacturing," (Order No. PB
88-160 387/AS; Cost: $25 95, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park. NC 27711
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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