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 ------- 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! ------- 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 ------- United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 IS •"" f*~SFr" j\ ,.. ,. ,. j! Otln I. j* ^ j ,•*' \I"L.I\'LT>' t u.o.ruOiisJ S HAIi26'3B j qt-E I fj •? Official Business Penalty for Private Use $300 EPA/600/S2-88/004 \ „ n XVHlvi CHICAGO ------- |