Process for the preparation of cellular or non-cellular polyurethane resins

Claim 1

A process for the preparation of cellular or non-cellular polyurethane resins by the reaction of (a) organic polyisocyanates with (b) compounds containing at least 2 active hydrogen atoms and having a molecular weight of from 32 to 400, optionally (c) compounds containing at least 2 active hydrogen atoms and having a molecular weight of from 400 to 10,000, and optionally (d) blowing agents, catalysts and other known additives, characterized in that the compounds used as component (b) are low molecular weight polyhydroxyl compounds prepared by condensing formaldehyde hydrate in the presence of soluble or insoluble compounds of metals of the 2nd to 4th Main Group or 2nd to 8th sub-Group of the Periodic System of Elements as catalyst, and optionally in the presence of compounds capable of enediol formation as cocatalyst and/or of low molecular weight and/or higher molecular weight polyhydroxyl compounds, controlling the pH during the condensation reaction by the addition of from 5 to 200 milliequivalents, based on 1 mol of formaldehyde, of a tertiary amine which contains an electrophilic hetero atom in the β-position to the tertiary nitrogen atom.