Patent ID: 9644058
Date: 2017-05-09
CPC Classifications: B07B,C08F,C08J

Claim:
1. A method for producing a polyacrylic acid (salt)-based water absorbent resin, which sequentially comprises: a polymerization step, in which a monomer aqueous solution containing 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, 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, rotation speed F: from 60 to 600 rpm; and two or more sieve nets each having an opening in the range of ±2% relative to an intended opening are used sequentially in the rocking-type sieve classification apparatus.