PROBLEM TO BE SOLVED: To provide a water-absorptive resin with high performance, comprising: a polymer that is obtained by polymerizing an aqueous monomer solution containing an unsaturated monomer containing an acid group as an essential component and polysaccharides, with high productivity.SOLUTION: The water-absorbing agent is a surface-crosslinked water-absorptive resin comprising: the polymer that is obtained by polymerizing the aqueous monomer solution containing the unsaturated monomer containing the acid group as the essential component and the polysaccharides and meets the following (i)-(iv): (i) a neutralization index of the acid group of 80-100 mol% (ii) a weight average particle size (D50) of 250-450 &mum (iii) a percent by weight of particles with less than a particle size of 150 &mum of 0-5 wt.% and (iv) a water content is 3-15 wt.%.COPYRIGHT: (C)2012,JPO&INPIT【課題】酸基含有不飽和単量体を必須成分とする単量体水溶液を重合させて得られる重合体と多糖類とを含む高性能な吸水性樹脂を高い生産性で提供する。【解決手段】酸基含有不飽和単量体を必須成分とする単量体水溶液を重合させて得られる重合体と多糖類とを含む、表面架橋された吸水性樹脂であって、以下の(i)~(iv)を満たすことを特徴とする吸水剤。(i)酸基の中和率が80~100モル%、(ii)重量平均粒子径(D50)が250~450μm、(iii)粒子径150μm未満の粒子の重量百分率が0~5重量%、(iv)含水率が3~15重量%【選択図】なし
