Patent ID: 6197839
Filing Date: 2001-03-06
Classification: C08G,C08J

Abstract:
A process for the preparation of a polyurethane elastomer comprising the steps of:a) reacting a first polyhydroxyl compound having a functionality of from 2 to 3 and a molecular weight of from 800 to 6000 and, optionally, a chain extender or crosslinker having a molecular weight of up to 800 with an organic diisocyanate selected from the group consisting of toluene diisocyanate, diphenylmethane diisocyanate, 3,3'-dimethylbiphenyl diisocyanate, 1,2-diphenylmethane diisocyanate, aliphatic diisocyanates having from 4 to 12 carbon atoms, cycloaliphatic diisocyanates having from 6 to 18 carbon atoms and mixtures thereof, to form a polyaddition product, wherein the equivalence ratio of hydroxyl groups in the polyhydroxyl compounds and optional chain extenders or crosslinkers to the isocyanate groups in the organic diisocyanate is 1:>1-6;b) reacting the polyaddition product with 1,4-phenylene diisocyanate to form a polyisocyanate prepolymer, wherein the equivalence ratio of the hydroxyl groups in the polyhydroxyl compounds and optional chain extenders or crosslinkers to isocyanate groups in the 1,4-phenylene diisocyanate is 1:0.02-6; andc) reacting the polyisocyanate prepolymer with a second polyhydroxyl compound having a functionality of from 2 to 3 and a molecular weight of from 800 to 6000 and optionally, chain extenders or crosslinkers having a molecular weight of up to 800 to form the polyurethane elastomer.