Nippon Shokubai Co., Ltd.

Koji Tachi

Kazushi Torii

Hiroyuki Ikeuchi

Shigeru Sakamoto

Sayaka Machida

Reiko Nakatsuru

Hironori Sato

Yoko Shirai

Taku Iwamura

Yasuhisa Nakashima

Yukihiro Kasano

Hiroki Kawada

Makiko Masuda

Provided is a water-absorbing agent that causes no or little fluctuation of feed rate when fed with use of a feeder. A water-absorbing agent containing a water-absorbing resin as a main component, the water-absorbing agent satisfying the following (a) and (b): (a) K-index is 70 or more; and (b) Moisture absorption blocking ratio, after 30 minutes of standing at a temperature of 25&#xb0; C. and a relative humidity of 80% RH, is 70 weight % or less, the K-index being defined by the following equation: K-index=100&#x2212;(&#x2212;438+3.6&#xd7;angle of repose+3.5&#xd7;angle of difference+7.9&#xd7;compressibility rate+290&#xd7;bulk density (EDANA method)).

Absorption agent and absorbent article

An object of the present invention is to provide a method for producing water absorbent resin powder in which permeability potential (SFC) is improved while a water absorbing rate (FSR) is being kept. The method is a method for producing water absorbent polyacrylic acid (salt) resin powder including the steps of: (i) polymerizing an acrylic acid (salt) monomer aqueous solution; (ii) during or after the step of (i), performing gel grinding of a hydrogel crosslinked polymer obtained by the polymerization, wherein the hydrogel crosslinked polymer has resin solid content of 10 wt % to 80 wt %, and the gel grinding is carried out with gel grinding energy (GGE) of 18 [J/g] to 60 [J/g]; (iii) drying a particulate hydrogel crosslinked polymer obtained by the gel grinding, wherein the drying is performed at 150&#xb0; C. to 250&#xb0; C.; and (iv) carrying out a surface treatment to the particulate hydrogel crosslinked polymer thus dried.

Method for producing water absorbent polyacrylic acid (salt) resin powder, and water absorbent polyacrylic acid (salt) resin powder

An object of the present invention is to provide a water absorbent resin which attains high liquid permeability and water absorbing speed, and which does not have problems of coloring and odor. The water absorbent resin includes: (A) a water absorbent resin particle having a carboxyl group; (B) a covalent surface crosslinking agent in which the number of carbons is not more than 10; (C) 0.001 mass % to 0.2 mass % of a water-soluble or water-dispersible polymer whose Log P is not less than 1.0; and (D) 0.001 mass % to 1 mass % of a water-soluble polyvalent cation. The water absorbent resin has not less than 20 g/g of a fixed height absorption (FHA) at a height of 20 cm.

Water absorbent resin material, and method for producing same

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&#xb0; C.&#x2266;TS&#x2266;85&#xb0; C.,&#x2003;&#x2003;Equation 1:40&#xb0; C.&#x2266;TG&#x2266;90&#xb0; C.,&#x2003;&#x2003;Equation 2:47&#xb0; C.&#x2266;TT&#x2266;73&#xb0; C.&#x2003;&#x2003;Equation 3:

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

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Himeji, Japan

Koji Tachi