Preparation of polyurethane rigid foams

Abstract

A process for producing polyurethane rigid foams comprises reacting a) organic polyisocyanates b) relatively high molecular weight compounds containing at least two respective hydrogen atoms and, if desired, c) low molecular weight chain extenders and/or crosslinkers in the presence of d) blowing agents e) catalysts and, if desired, f) auxiliaries and additives, wherein the relatively high molecular weight compounds containing at least two reactive hydrogen atoms comprise a mixture of a1) one or more high-functional, polyether alcohols having functionalities of from 6 to 8 and mean equivalent masses of from 125 to 200, a2) one or more polyether alcohols based on aliphatic amines having functionalities of from 3 to 4 and mean equivalent masses of from 70 to 130, a3) one or more low-functional polyether alcohols having functionalities of from 2 to 3 and mean equivalent masses of from 67 to 250, and a4) an OH-containing fatty acid ester.

Dependencies are inferred from the claim text.