Patent ID: 8883944
Filing Date: 2014-11-11
Classification: C08F

Abstract:
1. A method for producing a water-absorbent resin by performing only a one-stage reversed-phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a petroleum hydrocarbon dispersion medium, comprising the following steps of: (A) forming a primary dispersion in the absence of surfactants by adding an aqueous solution of a water-soluble ethylenically unsaturated monomer containing a hydrophilic polymeric dispersion agent to a petroleum hydrocarbon dispersion medium in which a hydrophobic polymeric dispersion agent is heat-dispersed or heat-dissolved, under stirring; (B) further forming a secondary dispersion by adding a surfactant to a dispersion liquid obtained after the primary dispersion; and (C) performing the reversed-phase suspension polymerization process by using a radical polymerization initiator; wherein the hydrophilic polymeric dispersion agent is at least one kind selected from the group consisting of polyvinyl alcohol and polyvinyl pyrrolidone.