Process for preparing smoke-retardant polyisocyanurate foam

摘要

In a process for preparing a smoke-retardant polyisocyanurate foam by reacting an organic polyisocyanate in the presence of a blowing agent and an isocyanate-trimerization catalyst, the improvement comprising conducting the reaction by adding 0.5 to 6 wt. % as Si to the total components of the foam of an organosilicone surfactant having a Si content of 4-22%, and selected from an organopolysiloxane-poly-oxyalkylene copolymer, polyvinylsilane having polyoxyalkylene side chain or modified products thereof wherein the mole % of the ethylene oxide units of the polyoxyalkylene moiety of the organosilicone surfactant is greater than 40 mole % based on the total number of ethylene oxide and propylene oxide units in said polyoxyalkylene moiety.