Patent ID: 9074030
Filing Date: 2015-07-07
Classification: A61L,C08F,C08J,Y10T

Abstract:
1. A method for producing a polyacrylic acid-type water absorbent resin, comprising (A) a step of obtaining an aqueous solution of acrylic acid-type monomers containing gas bubbles dispersed therein; (B) a step of polymerizing the aqueous monomer solution and thereby obtaining a foamed polymer; and (C) a step of heating and drying the foamed polymer, in which the gas bubbles that are dispersed are formed by an inert gas, Wherein the gas bubbles are incorporated such that the volumetric expansion factor defined by the following formula (1): [Formula 1] exceeds 1.1 times, and the aqueous monomer solution having a monomer concentration defined by the following formula (2): [Formula 2] of 40% by weight or greater is boiling polymerized at a temperature of 100° C. or higher.