METHOD FOR PRODUCING WATER ABSORBENT-RESIN

A method for producing a water-absorbent resin by a reversed-phase suspension polymerization method, includes step 1 of dispersing a first aqueous solution containing a partially neutralized product (A) of a water-soluble ethylenically unsaturated monomer having acid groups in the molecule in a petroleum-type hydrocarbon dispersion medium in the presence of a dispersing agent, and then polymerizing the resulting dispersion to obtain a slurry containing primary particles of a polymer, and step 2 of adding a second aqueous solution containing a partially neutralized product (B) of a water-soluble ethylenically unsaturated monomer having acid groups in the molecule to the slurry obtained in step 1, and then polymerizing the mixture to obtain a slurry in which the primary particles are agglomerated. In the method, a molar neutralization degree X of the partially neutralized product (A) is set larger than a molar neutralization degree Y of the partially neutralized product (B), and also a difference between the molar neutralization degree X and the molar neutralization degree Y is set to 5% or more. The dispersing agent usable herein is at least one member among those of a surfactant and a polymer-type dispersing agent. The water-absorbent resin produced by this method suppresses odor originating from a dispersion medium and odor generated with the lapse of time after absorption of a body fluid or the like.