Polyisocyanate compositions and their use in the preparation of polyurethane foams.

摘要

A method for the preparation of polyurethane foams which comprises intimately mixing: (a) a prepolymer prepared by reacting a polyoxyalkylene diol or triol with an excess of a polyisocyanate comprising diphenylmethane disocyanate, the polyoxyalkylene diol or triol containing propylene oxide and ethylene oxide residues, the latter being distributed in a random manner throughout the polyoxyalkylene chain or part thereof and constituting at least 50% by weight of the total alkylene oxide residues; (b) a polyoxyalkylene polyol containing oxypropylene and optionally oxyethylene residues; (c) water; and (d) a catalyst for foam formation; optionally in the presence of other conventional polyurethane foam ingredients. The method is useful for preparing cold cure foams.