PROCESS FOR THE PRODUCTION OF POLYURETHANE ELASTIC MOULDINGS WHICH HAVE A COMPACT SURFACE

摘要

1,209,297. Polyurethane foams. FARBENFABBIKEN BAYER A.G. 28 April, 1969 [7 May, 1968], No. 21495/69. Headings C3C and C3R. . Polyurethane foams which have a compact, i.e. non-cellular surface, are prepared by reacting under compression in a mould a compound containing reactive hydrogen atoms with a polyisocyanate in the presence of a blowing agent which is a mixture of a halogenated hydrocarbon and a hydrate of an organic compound which splits off the water of hydration at temperatures above 40‹ C. The reactive hydrogen containing compound is most suitably a polyalkylene glycol ether and the polyisocyanate may be a carbodiimide modified diphenylmethane - 4,41 - diisocyanate, a prepolymer obtained by reacting a polyol with diphenylmethane - 4,41- diisocyanate or toluylene - 2,4 - or - 2,6 - diisocyanates or a poly - phenylpolymethylene polyisocyanate. Preferred compounds which split off water of hydration are hydrates of ethylene glycol of the formulae C 2 H 6 O 2 .2H 2 O or 3C 2 H 6 O 2 .2H 2 O or chloral hydrate.