A closed cell phenolic foam

摘要

A closed cell phenolic foam is formed from a phenolic resin, a blowing agent such as HCFC141b, a catalyst and less than 2.5% by weight relative to the resin of at least one hydrofluoroether or an azeotrope formulation thereof. 1-methoxy-nonafluorobutane and especially an azeotrope formulation thereof with trans-1,2-dichloroethylene are preferred hydrofluoroethers. The phenolic foam has a stable closed cell content of greater than 90% and a stable thermal conductivity.