CATALYTIC GEL COMPOSITION FOR PREPARATION OF POLYURETHANE RIGID FOAMS AND PERFECT PROCESS FOR PREPARATION OF POLYURETHANE RIGID FOAMS

摘要

Rigid polyurethane foam is prepared by reacting a polyol containing at least three active hydrogen atoms with a polyfunctional isocyanate or isothiocyanate in the presence of a gel catalyst and a blowing agent. As gel catalyst there is used a catalyst composition comprising an antimony carboxylate, a potassium carboxylate and a zinc carboxylate wherein the hydrocarbyl as hereinbefore defined portion of each carboxylate contains from 1 to 20 carbon atoms and wherein each of the antimony and potassium carboxylates constitutes from 10 to 40% by weight of the total carboxylate content and the zinc carboxylate constitutes the remaining 20 to 80% by weight of the total carboxylate content, either alone or in combination with another gel catalyst, particularly one chosen from tertiary amines, inorganic tin compounds an organotin compounds. The use of the specified gel catalyst composition enables the isocyanate- or isothiocyanate- polyol reaction to be controlled over a wide range.