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Polyacrylic acid (salt)-type water absorbent resin and method for producing of same

  • US 8,859,685 B2
  • Filed: 08/27/2010
  • Issued: 10/14/2014
  • Est. Priority Date: 08/27/2009
  • Status: Active Grant
First Claim
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1. A method for producing a polyacrylic acid (salt)-type water absorbent resin, comprising a step of preparing an aqueous monomer solution of an acrylic acid (salt), a step of continuously polymerizing the aqueous monomer solution, a step of finely shredding a hydrous gel-like crosslinked polymer during or after polymerization, a step of drying the obtained particulate hydrous gel-like crosslinked polymer, and a surface treatment step of adding and reacting a surface treatment agent to and with the dried water absorbent resin powder,wherein crosslinking reaction is carried out at a stirring power index of 3 to 15 W·

  • hr/kg in a transverse type continuous stirring apparatus having stirring means including a feeding inlet and a discharging outlet of a water absorbent resin and one or more rotary shafts having with a plurality of stirring discs, and heating means after the addition of the surface-crosslinking agent in the surface treatment step;

    wherein
    (stirring power index)=((power consumption of apparatus at the time surface treatment)−

    (power consumption at the time of idling))×

    average retention time)/(treatment amount per unit time×

    average retention time).

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