Nippon Shokubai Co., Ltd.

Ryuichi Otani

Makoto Matsumoto

Shinichi Fujino

Seiji Kato

Makoto Eto

Yasuhiro Kawaguchi

Noboru Nabara

Narimasa Okugawa

Kentaro Ichikawa

Provided is a method for producing a polyacrylic acid (salt)-based water absorbent resin in which the physical properties (especially liquid permeability) are improved and maintained even in large scale production. The method for producing a polyacrylic acid (salt)-based water absorbent resin, which sequentially includes a polymerization step, in which a monomer aqueous solution having acrylic acid (salt) as a main component is polymerized, a drying step, in which a water-containing gel-like crosslinked polymer obtained in the polymerization step is dried, and a classification step, in which a polymer obtained in the drying step is classified, wherein a rocking-type sieve classification apparatus is used in the classification step, and the rocking-type sieve classification apparatus has a sieve net having a trajectory and a rotation speed in the following ranges; radial gradient R: from 5 to 40 mm, tangential gradient T: from 0.1 to 25 mm, eccentric gradient E: from 40 to 80 mm, and rotation speed F: from 60 to 600 rpm.

Process for producing polyacrylic acid (salt)-based water absorbent resin

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Hyogo, Japan

Ryuichi Otani