Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2011-05-03
2011-05-03
Choi, Ling-Siu (Department: 1762)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S219600, C526S223000, C525S340000, C525S360000
Reexamination Certificate
active
07935774
ABSTRACT:
An object of the present invention is to provide a method for producing a particulate water-absorbent polymer particle having remarkably improved long-term color stability, without an adverse effect (such as a delay in polymerization) on synthesis of the particulate water-absorbent polymer. The method includes the steps of polymerizing a monomer aqueous solution (B) containing (i) at least one type of monomer (A) that is capable of forming a particulate water-absorbent polymer by polymerization, (ii) at least one type of crosslinking agent, (iii) at least one type of polymerization initiator and (iv) an organophosphorus compound in an amount of not less than 1 but not more than 100 ppm by mass with respect to the monomer (A) so as to form a hydrogel polymer, and drying the hydrogel polymer. The method enables to provide an excellent particulate water-absorbent polymer that realizes (i) long-term color stability and improvement in urine tolerance and (ii) absorbing property, which are in such a trade-off relationship. In this way, the above object is attained.
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Ikeuchi Hiroyuki
Nagasawa Makoto
Choi Ling-Siu
Nippon Shokubai Co. , Ltd.
Nixon & Vanderhye PC
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