Blowing agents are one of the integral parts of a polyurethane foam.
Foam generation can be achieved by an external blowing agent such as a
low boiling liquid which evaporates during urethane formation, by a
gas dissolved under pressure or by chemical reaction. Fluorocarbons
are the most common blowing agents used in polyurethane foams.
They offer the advantage of being non flammable, having excellent
thermal characteristic and the right boiling point. Over time the
fluorocarbon gas diffuses out of the foam and enters the atmosphere. Fluorocarbons
have been found responsible for their ozone depletion potential. The
EPA has regulated the use of fluorocarbons in foams and has
established suitable alternate
replacements. For Europe consult this site.
Please consult this site for the latest approved
blowing agent for a certain application. In the long run all fluorocarbons
and other blowing agents will be replaced with carbon dioxide as a