Process for preparing polyurethane foam and foam so obtained

Claim 1

A process for preparing a polyurethane foam comprising reacting in one stage an aliphatic or alicyclic polyisocyanate with a polyol in the presence of water and a catalyst combination comprising: (a) a compound having the general formula >N-- C= N selected from the group consisting of diazabicycloalkene according to formula: ##STR11## wherein m is an integer of 3 to 7 and n is an integer of 2 to 4, the salts thereof formed with acetic acid, phenol or fumaric acid and the guanidine derivatives having the general formula: ##STR12## wherein R 1 is a C 1 to C 20 alkyl radical or a group ##STR13## in which R 4 and R 5 are identical or different and represent hydrogen or a C 1 to C 3 alkyl radical, R 2 and R 3 are identical or different and represent hydrogen or a C 1 -C 3 alkyl radical; and X represents hydrogen, a C 1 to C 20 alkyl radical, a cycloalkyl radical, or phenyl radical, said C 1 -C 20 alkyl, cycloalkyl or phenyl radical being unsubstituted or substituted by one or more halogen atoms, by one or more linear or branched C 1 to C 8 alkyl groups, C 2 to C 8 alkenyl groups, or C 2 to C 8 alkynyl groups, by a phenyl group or by a carboxyl group, and the salts of said guanidine derivatives formed with carbonic acid, phenol or benzoic acid, and (b) a compound selected from the group consisting of alkaline or alkaline earth metal salts of carboxylic acids having the structural formula R--(CO 2 H) x wherein x is 1 or 2 and the metal alcoholates and phenolates having the structure M' OR', wherein R represents: hydrogen, a linear or branched C 1 to C 20 alkyl, C 2 to C 20 alkenyl or C 2 to C 20 alkynyl radical, these radicals being unsubstituted or substituted by one or more halogens, a C 3 to C 6 cycloalkyl radical which is unsubstituted or substituted by one or more C 1 to C 6 alkyl, C 2 to C 6 alkenyl or C 2 to C 6 alkynyl groups, which are linear or branched, a phenyl radical, unsubstituted or substituted by one or more halogens, or by one or more C 1 to C 8 alkyl, C 2 to C 8 alkenyl or C 2 to C 8 alkynyl groups, which are linear or branched, or by a phenyl group; R' represents a C 1 to C 20 alkyl, C 2 to C 20 alkenyl or C 2 to C 20 alkynyl radical, linear or branched, which is unsubstituted or substituted by a phenyl group or by one or more halogens, a C 3 to C 6 cycloalkyl radical which is unsubstituted or substituted by one or more linear or branched C 1 to C 6 alkyl, C 2 to C 6 alkenyl, C 2 to C 6 alkynyl groups, or a phenyl radical, which is unsubstituted or substituted by one or more linear or branched C 1 to C 20 alkyl, C 2 to C 20 alkenyl, or C 2 to C 20 alkynyl groups, or by one or more phenyl groups or by one or more halogen of hydroxyl radicals, and M' is an alkaline metal.