Water absorbent resin production method and usage thereof

Details Water absorbent resin production method and usage thereof Water absorbent resin production method and usage thereof

2008-03-14

2011-10-25

Wu, David W (Department: 1762)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S089000, C526S210000, C526S217000, C524S555000, C524S556000, C523S111000

Reexamination Certificate

active

08044157

ABSTRACT:
A method for producing a water absorbent resin comprises the steps of: (i) polymerizing a monomer including an unsaturated monomer containing a carboxyl group, in the presence of an internal cross-linking agent (A) having two or more radical polymerizable unsaturated groups in its single molecule and in the presence of a non-polymeric internal cross-linking agent (B) having in its single molecule two or more functional groups each of which allows formation of an ester bond or an amide bond by reacting with a carboxyl group so as to obtain a cross-linked polymer hydrogel; (ii) crushing the cross-linked polymer hydrogel obtained in the step (i); and (iii) drying crushed cross-linked polymer hydrogel products obtained in the step (ii), wherein: an amount of the internal cross-linking agent (A) is 0.01 mol % or more and 0.2 mol % or less relative to an amount of the unsaturated monomer containing a carboxyl group, and a molar ratio (B)/(A) of the internal cross-linking agent (A) and the non-polymeric internal cross-linking agent (B) is 0.01 or more and 1.8 or less.

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