CATALYST FOR POLYISOCYANURATE FOAMS MADE WITH ALTERNATIVE BLOWING AGENTS

摘要

Rigid, closed cell polyisocyanurate foams are prepared by reacting together a polyisocyanate and a polyester polyol or a mixture of a polyester polyol and at least one other isocyanate-reactive compound in the presence of (a) a hydrogen-containing blowing agent or a mixture of a hydrogen-containing blowing agent and at least one coblowing agent and (b) a catalyst mixture comprising (i) a carboxylate salt of an alkali metal or an alkaline earth metal or mixtures thereof, (ii) a tertiary amine, and (iii) a quaternary ammonium carboxylate salt, wherein the equivalent ratio of carboxylate metal salt: tertiary amine is a value less than about 2:1, and the quaternary ammonium carboxylate salt is present in an amount which enhances the char structure of polyisocyanurate foams made with the catalyst mixture and subjected to flammability char tests.