Patent ID: 8912298

Claim:
A method for producing a particulate water absorbing agent containing, as a main component, a water absorbent resin whose surface is cross-linked, the method comprising the steps of: (1) mixing, with an aqueous solution of a monomer for a water absorbent resin, an aqueous solution containing a polymerization initiator; (2) polymerizing the monomer so as to obtain a hydrogel; (3) drying the hydrogel so as to obtain a dried polymer; (4) cross-linking a surface of the water absorbent resin; (5) adding, to the hydrogel or the dried polymer, a liquid containing a modifier, and (6) producing the liquid containing the modifier by a method comprising the steps of: (a) providing at least one kind of liquids in at least one tank; (b) removing the at least one kinds of liquid from the at least one tank and mixing the at least one kind of liquid with a liquid separately prepared by a mixing device provided in a tube connecting the at least one tank to a storage tank to produce a mixture solution thus obtained; (c) continuously taking out a part of the resulting mixture solution from the storage tank while continuously feeding the resulting mixture solution to the storage tank, the modifier being a surface cross-linking agent which is used in the step (4), in the step (a), the at least one kind of liquid provided in the at least one tank being a stock solution of the surface cross-linking agent, and in the step(b), the liquid separately prepared being water and the step of said mixing being performed with use of the water to dilute the stock solution of the surface cross-linking agent removed from the at least one tank wherein the water absorbing agent is continuously produced at not less than 1000 kg/hr per one line or per one plant.