PROBLEM TO BE SOLVED: To provide a water-absorbing resin that has a proper particle diameter, has an excellent water-absorbing performance and a water-absorbing rate suitable for hygienic material, has less solubility in water, and is suitable for use in the hygienic material.SOLUTION: This invention relates to a method of producing a water-absorbing resin from a water-soluble ethylenically unsaturated monomer by reverse-phase suspension polymerization reaction of two or more steps, wherein, in the reverse-phase suspension polymerization reaction in at least one step, used is a radical polymerization initiator which is different from the reverse-phase suspension polymerization reaction in another step.COPYRIGHT: (C)2015,JPO&INPIT【課題】本発明の目的は、適度な粒子径を有し、優れた吸水性能と衛生材料に好適な吸水速度を有する、水可溶分が少ない、衛生材料用途に適した吸水性樹脂を提供することにある。【解決手段】2段以上の逆相懸濁重合反応により、水溶性エチレン性不飽和単量体から吸水性樹脂を製造する方法において、少なくとも1段の逆相懸濁重合反応では、他段の逆相懸濁重合反応とは互いに異なるラジカル重合開始剤を使用する。【選択図】なし
