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The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Patent No.:

US 9012356 B1

PDFFull Text
Date of Patent:
Apr. 21, 2015

Filed:

Nov. 16, 2012

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

Applicant:

Nippon Shokubai Co., Ltd., Osaka, JP;

Inventors:

Koji Tachi, Himeji, JP;

Hironori Sato, Himeji, JP;

Kazushi Torii, Himeji, JP;

Hiroyuki Ikeuchi, Himeji, JP;

Assignee:

Nippon Shokubai Co., Ltd., Osaka, JP;

Attorney:

Roylance, Abrams, Berdo & Goodman, L.L.P.

Primary Examiner:

Robert C Boyle

Int. Cl.
CPC ...
C08L 33/02 (2006.01); C08J 3/24 (2006.01); C08F 20/06 (2006.01); A61L 15/24 (2006.01); A61L 15/60 (2006.01); C08F 220/06 (2006.01); C08F 120/06 (2006.01);
U.S. Cl.
CPC ...
C08J 3/245 (2013.01); C08L 33/02 (2013.01); C08F 20/06 (2013.01); A61L 15/24 (2013.01); A61L 15/60 (2013.01); C08F 220/06 (2013.01); C08F 120/06 (2013.01); C08J 2333/02 (2013.01);
Abstract

The purpose of the present invention is to provide a method for producing a water absorbent resin having improved physical properties, particularly, improved saline flow conductivity (SFC) and less amount of fine powder. The present invention provides a method for producing a polyacrylic acid (salt)-based water absorbent resin, the method comprising: a polymerization step of supplying as a base material an aqueous solution containing an acrylic acid and/or an acrylic acid salt as a monomer component and polymerizing the monomer in the presence of a polymerization initiator, wherein in the polymerization step, there is used a polymerization apparatus which comprises a polymerization part covered with a case, said polymerization part comprising at least a supply line for supplying the aqueous solution, an external gas supply port, and a gas discharge port, and has a structure that a liquid contact part in contact with the aqueous solution and a gas supplied from the outside of the polymerization apparatus are brought into contact with the aqueous solution during a polymerization, and assuming that a controlled temperature of the liquid contact part is set as TS, a temperature of the gas part is set as TG, and TT is (TS+TG)/2, the polymerization is carried out under temperature conditions satisfying the following Equations 1 to 3:35° C.≦TS≦85° C.,  Equation 1:40° C.≦TG≦90° C.,  Equation 2:47° C.≦TT≦73° C.  Equation 3:

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