Low friability polyisocyanurate foams

摘要

Covers novel urethane-modified polyisocyanurate rigid foams comprising a reaction product obtained by bringing together in the presence of a blowing agent, an aromatic polyisocyanate, an isocyanurate group formation catalyst and a polyol comprising an alkylene oxide adduct of a novolak resin containing 5-25 weight percent of free phenol or substituted phenol based on the weight of said resin. Said foams are particularly characterized by their low friability, good flammability resistance and excellent thermal stability.