PROCESS FOR RIGID POLYURETHANE FOAMS

摘要

Process for the preparation of a rigid polyurethane or urethane-modified polyisocyanurate foam in the presence of a blowing agent mixture comprising cyclopentane and a certain amount of other organic compounds as co-blowing agents, the saturated vapour pressure of said co-blowing agents in bar at T use (v.p.) complying with die following equation (I): v.p. .gtoreq. 0.7 bar .times. T use/298 .degree.K x C/100 wherein C is the mole % of said co-blowing agent in gaseous form on the total blowing age nt mixture in the gaseous phase after foaming and T use is the temperature in .degree.K at which the foam is used.