GB967444A - A process for the preparation of polyurethanes - Google Patents

Abstract

Polyurethanes are prepared by mixing together at least two hydroxyl containing compounds, which are defined as polyalkylene polyols, polyesters, polyether-esters, polyesteramides or the reaction products of amines or alkanolamines and an epoxide and/or polyepoxide, one hydroxyl-containing compound having an average molecular weight above 1,000 and the other having an average molecular weight below 1,000, with a stoicheiometric excess of an organic polyisocyanate or organic polyisothiocyanate to give a prepolymer and by reacting the prepolymer with an hydroxyl-containing compound as hereinbefore defined having an average molecular weight above 1,000. Water may be present during the formation of the prepolymer and other active hydrogen containing materials e.g. water, glycols, primary amines, secondary amines, dicarboxylic acids, hydroxyamines, hydroxycarboxylic acids and aminocarboxylic acids. Many hydroxyl-containing compounds or the starting materials from which they may be made are specified or exemplified. Many organic polyisocyanates or polyisothocyanates are specified including dimeric compounds and the reaction products of organic polyisocyanates or isothiocyanates with phenols or aliphatic polyhydroxy compounds. In the examples polymethane foams are prepared by producing a prepolymer and reacting it with the hydroxyl-containing compound of molecular weight above 1,000 in the presence of water and an organopolysiloxane. Uses: the process of the invention may be used to make high modulus flexible foams for filling crash pad fascia panels, arm rests and cases for electrical equipment. Specifications 967,441 and 967,442 are referred to.