Halon 1211 (CF2ClBr)
Table 1.5 The Annual Estimated Volatile Emissions from U.S. Flexible Polyurethane Foam Industry in 1992
Function (tons per year) CH2Cl2 CH3Cl3 TDI/MDI Naphtha CFC-11
Blowing Agent 16,968
Chemical Storage 49
Rebond operation 11
Equipment cleaning 440
Blowing agent 60
Mold Release 10,000
Chemical Storage 43
Molded Foam V
Based on the USEPA report EPA 625/R-96/005 September 1996.
polyols and isocyanates, acting as an additional blowing agent and also removing excess heat that can scorch the foam. Molded foams typically do not use ABAs but integral skin foams rely on their use.
The current practice in industry has changed markedly from that in pre-Montreal Protocol days, and most of the VOCs included in the Table 1.5 have been practically eliminated. CFC-11 has been replaced by either liquid carbon dioxide or by newer classes of relatively safer blowing agents (such as HFAs) that perform equally well though at a slightly higher cost. Water-based release agents and less volatile solvents have replaced most of the naphtha-type agents that contributed to high VOC emissions. The use of high-pressure mix heads by industry also contributed to the conservation of solvents as these did not need to be flushed as with low-pressure mix heads. The subject of foams and the chemistry of blowing agents will be treated in greater detail in Chapter 2.
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