process for preparing rigid polyurethane foams or urethane modified polyisocyanurate, rigid polyurethane foam or urethane modified polyisocyanurate, isocyanate-reactive polyfunctional composition, and reaction system for preparing rigid polyurethane or polyisocyanurate foam modified with urethane

摘要

process for the preparation of rigid polyurethane foams or urethane-modified polyisocyanurate from polyisocyanates and isocyanate-reactive polyfunctional compounds in the presence of blowing agents in which the isocyanate-reactive polyfunctional compounds comprise an unmodified or modified novolac polyol and a polyether polyol with a hydroxyl index between 50 and 650 mg koh / g obtained by reacting a first polyfunctional initiator with ethylene oxide and, subsequently, with propylene oxide, where the degree of propoxylation is between 0.33 and 2 moles of propylene oxide per active hydrogen atom in the initiator and in which the molar ratio of ethylene oxide to propylene oxide in said polyether polyol is at least 2.