Patent ID: 7799874

Claim:
A polyurethane obtained by (i) homopolymerising ε-caprolactone to form a caprolactone polyol (ii) reacting the caprolactone polyol with at least one diisocyanate to form a diisocyanate terminated intermediate oligomer, and (iii) converting the diisocyanate terminated intermediate oligomer into the polyurethane by further reaction with a chain extender, wherein the homopolymerisation is catalyzed by a catalyst selected from the group of catalysts consisting of (a) bismuth ethylhexanoate and ethylhexanoic acid, (b) bismuth ethylhexanoate and bismuth neodecanoate, and (c) zinc neodecanoate and zinc oxide, the formation of the intermediate homopolymer and the chain extension are performed in the presence of residual active catalyst in the obtained ε-caprolactone polyol homopolymer, and the diisocyanate terminated intermediate oligomer has an average molecular weight of from 1000 to 5000.