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 amounts of other organic compounds as co-blowing agenrts, the the saturated vapour pressure of said co-blowing agents in bar at Tuse (v.p.) complying with the following equation (I) <IMAGE> (I) wherein C is the mole % of said co-blowing agent in gaseous form on the total blowing agent mixture in the gaseous phase after foaming and Tuse is the temperature in DEG K. at which the foam is used.