Integral-skin polyurethane foams and process therefor

Abstract

The instant invention relates to a process for the production of polyurethane foams by reacting polyisocyanates with polyhydroxyl compounds of a specified molecular weight range in the presence of blowing agents and chain lengthening or cross-linking agents and optionally in the presence of catalysts, foam stabilizers and other additives generally known. The improvement resides in (a) the polyisocyanates used containing aliphatically and/or cycloaliphatically bound isocyanate groups; (b) the polyhydroxyl compounds used containing ether groups; and (c) the chain lengthening or cross-linking agents comprising at least in part a member selected from the group consisting of a monoalkoxylated hydrazine, a dialkoxylated hydrazine, a reaction product of a monoalkoxylated or dialkoxylated hydrazine with an aliphatic monoisocyanate in a molar ratio of 1:1. The reaction is carried out in the presence of additional chain lengthening agents having a specified molecular weight. The present invention also relates to polyurethane foams obtained by this process.

Dependencies are inferred from the claim text.