METHOD FOR PRODUCING WATER ABSORBENT POLYACRYLIC ACID (SALT) RESIN POWDER, AND WATER ABSORBENT POLYACRYLIC ACID (SALT) RESIN POWDER

摘要

An object of the present invention is to provide a method for producing water absorbent resin powder in which permeability potential (SFC) is improved while a water absorbing rate (FSR) is being kept. The method is a method for producing water absorbent polyacrylic acid (salt) resin powder including the steps of: (i) polymerizing an acrylic acid (salt) monomer aqueous solution; (ii) during or after the step of (i), performing gel grinding of a hydrogel crosslinked polymer obtained by the polymerization, wherein the hydrogel crosslinked polymer has resin solid content of 10 wt% to 80 wt%, and the gel grinding is carried as to obtain a particulate hydrogel crosslinked polymer having a weight average particle diameter (D50) of 350 pm to 2000 pm and logarithmic standard deviation (ö) of particle size distribution of 0.2 to 1.0; (iii) drying a particulate hydrogel crosslinked polymer obtained by the gel grinding, wherein the drying is performed at 150°C to 250°C; and (iv) carrying out a surface treatment to the particulate hydrogel crosslinked polymer thus dried.