Abstract: An improved process for preparing integral skin polyurethane, wherein a reaction mixture comprising polyol, polyisocyanate the NCO groups of which are not directly bonded to an aromatic group, no more than 0.5 part by weight of water to 100 parts by weight of polyol, and a catalyst is reacted in a mould, said improvement consisting in using as catalyst a synergistic combination of at least one organic initiator, comprising at least one functional group of primary or secondary amines, with at least one organic compound of bismuth.

Abstract: A hydrophile polyurethane foam prepared from a hydrophile polyol, a polyisocyanate in which NCO groups are not directly bonded to an aromatic ring, a surface active agent, a swelling agent and a catalyst comprising:(A) at least one compound selected from the group consisting of:(1) diazabicyclo-alkenes of formula: ##STR1## (2) substituted guanidines and salts of formula: ##STR2## (3) substituted biguanidines of formula: ##STR3## (4) substituted biguanidines of formula: ##STR4## wherein the substituents can have different meanings, and (B) at least an alkali metal or alkaline earth metal salt of organic acids having a dissociation constant Ka<10.sup.-1.

Abstract: A process for preparing polyurethane with integral skin, wherein a composition comprising following ingredients: polyol, polyisocyanate, at most one part by weight of water to 100 parts by weight of polyol and catalyst, is reacted in a mould so that a polyurethane is formed, characterized in that one uses a polyisocyanate the NCO groups of which are not directly bonded to an aromatic group and, as catalyst, at least one of the following four synergistic combinations:(1) at least an amine containing the structure: ##STR1## in association with at least an alkali metal or alkaline-earth metal salt, alcoholate and/or phenolate of an acid the dissociation constant of which Ka.ltoreq.10.sup.-1, preferably Ka.ltoreq.10.sup.

Abstract: A process for preparing polyurethane foam which consists in introducing in the reaction, between a polyisocyanate and a polyol, a catalyst containing the chemical structure >N--C=N-- and also a compound selected from the group comprising metal salts of carboxylic acids having the structure ##STR1## M and metal alcoholates and/or phenolates having the structure M'OR', wherein M' represents an alkaline metal, M represents an alkaline or alkaline-earth metal, R represents hydrogen or an organic radical and R' represents an organic radical.