Poly (meth) acrylic acid (salt)-based particulate water-absorbing agent and production method therefor

A method for producing a poly(meth)acrylic acid (salt)-based particulate water-absorbing agent containing poly(meth)acrylic acid (salt)-based water-absorbing resin particles as a main component, the method comprising:

• (i) a step for preparing a (meth)acrylic acid (salt)-based aqueous monomer solution;
• (ii) a step for polymerizing the (meth)acrylic acid (salt)-based aqueous monomer solution;
• (iii) a step for gel-crushing a crosslinked hydrogel polymer during polymerization or after polymerization to obtain hydrogel particles;
• (iv) a step for drying the hydrogel particles to obtain a dried product;
• (v) a step for pulverizing and/or classifying the dried product to obtain water-absorbing resin powder;
• (vi) a step for surface crosslinking the water-absorbing resin powder to obtain water-absorbing resin particles;
• and
• (vii) a step for adding a liquid permeability enhancer to the water-absorbing resin powder or the water-absorbing resin particles, wherein
• the method further includes adding an adhesion controlling agent, which controls adhesion of the crosslinked hydrogel polymer and/or the hydrogel particles, in the step (iii) or before the step (iii), and where the adhesion controlling agent is added in an amount of 0.03 wt % to 2 wt % with respect to the raw material monomer of the crosslinked hydrogel polymer,
• a solid content of the hydrogel particles is adjusted to 10 wt % to 80 wt % and a weight average particle diameter (RB) of the hydrogel particles is adjusted to 50 μm to 460 μm, and
• a surface tension of the poly(meth)acrylic acid (salt)-based particulate water-absorbing agent is adjusted to 60 mN/m or more, and an absorption capacity without pressure (CRC) is adjusted to 28 g/g or more;
• the adhesion controlling agent is one or more compounds selected from a nonionic substance, an amphoteric substance, an anionic substance, and a cationic sub stance,
• the nonionic substance is (a) a polyol, (b) a hydroxy group-modified product of a polyol, (c) side-chain and/or terminal polyether-modified polysiloxane, or (d) an alkylene oxide adduct of higher aliphatic amine,
• the amphoteric substance is (e) alkylaminobetaine or (f) alkylamine oxide,
• the anionic substance is (g) a sulfuric acid ester salt of a higher alcohol alkylene oxide adduct or (h) alkyl diphenyl ether disulfonate, and
• the cationic substance is (i) an ammonium salt.