Films of hydrophilic interpolymers of neutralized acrylic acid, hydroxyalkyl methacrylate or dialkylaminoalkyl (meth)acrylate and optionally a cross-linking agent

Claim 1

A water insoluble, flexible, highly water absorbent polymeric film having up to 25 mil thickness and containing 25 to 45 weight percent of water, said film being prepared by photopolymerizing a monomer mixture consisting of (a) 65 to 95 weight percent of acrylic acid, 60 to 100 percent of the carboxylic groups having been neutralized with an alkali metal hydroxide or ammonia base prior to polymerization, (b) 5 to 35 weight percent of a comonomer selected from the group consisting of 2-hydroxyethyl methacrylate and dialkylaminoalkyl acrylate or methacrylate wherein each alkyl of the dialkyl groups has 1 to 8 carbons and the other alkyl group has 2 to 6 carbons, and (c) 0 to 5 weight percent, based on the weight of the monomers, of a cross-linking agent which contains two or more ethylenic unsaturations in the presence of 0.01 to 5 weight percent, based on the total weight of the monomers, of a photoinitiator and a sufficient amount of water so that the resulting polymeric film contains 25 to 45 weight percent of water.