Polyurethane resins

摘要

A polyurethane resin obtained from a diol component and a diisocyanate component by an ordinary process, wherein the diisocyanate component comprises: at least one kind of unmodified diisocyanate, and at least one kind of carbodiimide-modified aromatic diisocyanate having, at one or both of the ortho positions of the two isocyanate groups, an aliphatic, alicyclic or aromatic substituent of one or more carbon atoms, or at least one kind of carbodiimide-modified aliphatic diisocyanate wherein at least one of the two carbons each bonded with an isocyanate group is di- or tri-substituted, and the molar ratio of the unmodified diisocyanate and the carbodiimide-modified diisocyanate is 35-0.1:1. The polyurethane resin containing carbodiimide bonds in the molecular chain alleviates the problems of the prior art and exhibits hydrolysis resistance stably over a long period of time without losing the carbodiimide bonds out of the molecule.