Patent ID: 8859685

Claim:
A method for producing a polyacrylic acid (salt)-type water absorbent resin, comprising a step of preparing an aqueous monomer solution of an acrylic acid (salt), a step of continuously polymerizing the aqueous monomer solution, a step of finely shredding a hydrous gel-like crosslinked polymer during or after polymerization, a step of drying the obtained particulate hydrous gel-like crosslinked polymer, and a surface treatment step of adding and reacting a surface treatment agent to and with the dried water absorbent resin powder, wherein crosslinking reaction is carried out at a stirring power index of 3 to 15 W·hr/kg in a transverse type continuous stirring apparatus having stirring means including a feeding inlet and a discharging outlet of a water absorbent resin and one or more rotary shafts having with a plurality of stirring discs, and heating means after the addition of the surface-crosslinking agent in the surface treatment step: wherein (stirring power index)=((power consumption of apparatus at the time surface treatment)−(power consumption at the time of idling))×average retention time)/(treatment amount per unit time×average retention time).