METHOD FOR PRODUCING WATER-ABSORBENT RESIN PARTICLES AND WATER-ABSORBENT RESIN PARTICLES

摘要

Provided are: a method for producing water-absorbent resin particles which have excellent water absorption speed and high equilibrium swelling performance as well as a reasonable particle size and good handleability; and water-absorbent resin particles obtained therefrom. The present invention is a method for producing water-absorbent resin particles by subjecting a water-soluble ethylenically unsaturated monomer to a reverse phase suspension polymerization, comprising: (A) a step of subjecting the water-soluble ethylenically unsaturated monomer to a first reverse phase suspension polymerization in the absence of an internal crosslinking agent, in the presence of a surfactant with an HLB of 8-12, and in a petroleum hydrocarbon dispersion medium by using a water-soluble radical polymerization initiator; (B) a step of conducting an intermediate crosslinking reaction by further adding an intermediate crosslinking agent; (C) a step of producing a water-absorbent resin precursor by adding the water-soluble ethylenically unsaturated monomer while the surfactant is dissolved in the petroleum hydrocarbon dispersion medium, and by performing a second reverse phase suspension polymerization in the absence of the internal crosslinking agent by using the water-soluble radical polymerization initiator; and (D) a step of conducting a post-crosslinking reaction after adjusting the moisture content of the water-absorbent resin precursor to 30-100 mass% relative to the water-soluble ethylenically unsaturated monomer component which constitutes the water-absorbent resin precursor.