Nippon Shokubai Co., Ltd.

Kohei Omori

Kazushi Torii

Nobuya Tanaka

Shigeru Sakamoto

Kenji Tada

Hironori Sato

Yusuke Watanabe

Provided is a water-absorbing agent which is less likely to cause gel blocking and is suitable for a sanitary product and an absorbent article each being thin and containing a large amount of a water-absorbing agent, and which, while maintaining or hardly losing the other physical properties (a fluid retention capacity and a bulk specific gravity) of the water-absorbing agent, simultaneously achieves a high water absorbing speed (e.g., FSR), a high fluid retention capacity under load, high liquid permeability, and salt tolerance. The water-absorbing agent is a polyacrylic acid (salt)-based water-absorbing agent whose surface and its vicinity are crosslinked by an organic surface crosslinking agent, characterized by satisfying the following (A)-(D): (A) Free Swell Rate (FSR) of at least 0.28 g/g/s, or Absorption Time (Vortex) of 42 seconds or less; (B) Absorption Against Pressure (AAP) of at least 20 g/g; (C) Salt Tolerance Index represented by 'Salt Tolerance Index=(CRCdw)/(CRCs)' where CRCdw is a centrifuge retention capacity (unit; g/g) for deionized water (dw), and CRCs is a centrifuge retention capacity (unit; g/g) for a 0.9 weight % saline, satisfying 'Salt Tolerance Index&#x2264;0.49&#xd7;CRCs&#x2212;7.47'; and (D) Bulk Specific Gravity of 0.55 to 0.70 g/cm.

Polyacrylic acid (salt) water absorbent, and method for producing same

Provided is a water absorbent resin that is useful to sanitary materials such as a disposable diaper, a sanitary napkin, and a blood absorbent for medical use each having a higher liquid permeability and a higher water absorbing speed. Further provided is a water absorbent resin powder that is useful to sanitary materials such as a disposable diaper, a sanitary napkin, and a blood absorbent for medical use each having increased in absorbency of a liquid and in heat retaining property. A gel grinding device to be used to produce a water absorbent resin, includes: a screw; a feed opening; an extrusion opening; a porous plate; and a barrel, the barrel including a return preventing member provided on an inner surface thereof, and the return preventing member satisfying at least one of specific parameters.

Water absorbent resin powder

A particulate water absorbing agent having a polyacrylic acid (salt)-based water-absorbing resin as a main component, being surface-crosslinked and satisfying physical properties (1) to (3) below: (1) a proportion of particles with a particle diameter of not less than 150 &#x3bc;m and less than 850 &#x3bc;m is not less than 90% by weight; (2) an elastic modulus index (EMI) of particles with a particle diameter of not less than 500 &#x3bc;m and less than 600 &#x3bc;m is not less than 5500; and (3) a recovery rate defined as Rec.CRC/CRC is 1.05 to 1.20, the particulate water absorbing agent being particularly useful for absorbent articles.

Particulate water absorbing agent

Gel pulverization device, method for manufacturing polyacrylic acid (polyacrylate) superabsorbent polymer powder, and superabsorbent polymer powder

The present invention provides a particulate water-absorbing agent which has an excellent fluid retention capacity under pressure and an excellent liquid permeability. Each of the following values of the particulate water-absorbing agent of the present invention falls within a certain range: a ratio represented by 'centrifuge retention capacity/Ln (water-soluble component amount)'; a molecular weight distribution of the water-soluble component; a weight average molecular weight after a hydrolysis treatment; and a branching density after the hydrolysis treatment.

Particulate water-absorbing agent

Provided is a water absorbent resin that is useful to sanitary materials such as a disposable diaper, a sanitary napkin, and a blood absorbent for medical use each having a higher liquid permeability and a higher water absorbing speed. Further provided is a water absorbent resin powder that is useful to sanitary materials such as a disposable diaper, a sanitary napkin, and a blood absorbent for medical use each having a smaller amount of return of a liquid and a higher heat retaining property. A gel grinding device to be used to produce a water absorbent resin, includes: a screw; a feed opening; an extrusion opening; a porous plate; and a barrel, the screw including: a rotating shaft; and a flight, and the screw satisfying at least one of specific parameters.

Growing community of inventors

Hyogo, Japan

Kohei Omori