Barbara Decaire

Blowing Agents: The Next Generation

The most promising long term replacements for the HCFC blowing agents are likely to be the HFCs. Although other chemicals such as fluoroethers are feasible, much less is known concerning their toxicological and chemical stability properties. Amongst the HFCs two general options are possible: liquid blowing agents and gaseous blowing agents. Gaseous HFCs which are already commercially available or are likely to become available in the near future include HFCs 152a, 134a, 32, 125 and 143a. These gases are not as efficient thermal insulators as HCFC-141b or HCFC-22. Nor are they as soluble in polyols on a theoretical substitution basis as HCFC-22, which may have some effect on foam processing characteristics. Although a large number of HFC liquids are known, many of them are impractical because of high molecular weights or are flammable