Process for the preparation of printing plates from urethane polymers

摘要

A urethane polymer having free carboxyl groups on the backbone of the polymer and terminal methacrylate groups is prepared by (1) reacting a mixture of at least two aliphatic diols and an aliphatic dihydroxy mono- or dicarboxylic acid with an excess of an aliphatic, cycloaliphatic or aromatic diisocyanate in the presence of a catalyst to produce an isocyanate-terminated urethane polymer and (2) reacting the terminal isocyanate groups of the product of step (1) with an aliphatic monohydroxy methacrylate. The polymer can be used in photopolymerizable compositions for making tack-free flexographic printing plates.