Patent ID: 8772413

Claim:
A method for producing a polyacrylic acid (salt)-type water absorbent resin comprising steps of: preparing an aqueous monomer solution of an acrylic acid (salt), continuously polymerizing the aqueous monomer solution into a hydrous gel-like crosslinked polymer, finely shredding the hydrous gel-like crosslinked polymer during or after polymerization, drying the obtained particulate hydrous gel-like crosslinked polymer to obtain a dried water absorbent resin powder, adding a surface-crosslinking agent to the dried water absorbent resin powder with a continuous mixing apparatus, wherein the pressure inside of the continuous mixing apparatus is a reduced pressure greater than 0 kPa and is 10 kPa or lower than atmospheric pressure, and carrying out reaction of the mixture, wherein a stifling shaft of the continuous mixing apparatus for the surface-crosslinking agent is heated in the step of mixing the surface-crosslinking agent.