Patent ID: 6251960
Filing Date: 2001-06-26
Classification: A61L,C07C,C08J,Y02P

Abstract:
A process for producing a water-absorbent resin comprising the steps of:polymerizing an unsaturated monomer after dispersing a solid blowing agent having an average particle diameter within a range of from 1 .mu.m to 100 .mu.m in an aqueous monomer solution containing said unsaturated monomer and a cross-linking agent; andforming a covalent, bond by treating a vicinity of a surface of said water-adsorbent resin with a surface cross-linking agent after said polymerizing step;wherein at least one condition selected from the group consisting of conditions (a), (b) and (c) is satisfied:(a) said blowing agent is an acrylic acid salt of an azo compound containing an amino group represented by formula (1) ##STR3##(b) said blowing agent is an acrylic acid salt of an azo compound containing an amino group represented by formula (2) ##STR4##(c) the step of polymerizing said unsaturated monomer i, carried out under the presence of a dispersion stabilizer.