Nippon Shokubai Co., Ltd.

Nobuya Tanaka

Kazushi Torii

Kohei Omori

Kenji Tada

Shigeru Sakamoto

Hironori Sato

Kazuki Kimura

Yoshiro Mitsukami

Yusuke Watanabe

Reiko Nakatsuru

Daisuke Takeda

Tomoya Arai

Yuki Tanaka

Kazushi Horie

Kimiaki Nishimura

It is an object to provide a water-absorbing resin that while maintaining water-absorbing resin physical properties such as water absorption performance, has a sufficiently reduced odor produced during swelling. The object is attained by causing the water-absorbing resin to be a water-absorbing resin which is a surface-crosslinked water-absorbing resin, the water-absorbing resin having a volatile component concentration of 3.5 ppm or less as measured when the water-absorbing resin is caused to stand still for 15 minutes under a condition that the water-absorbing resin has a swelling capacity of 1.0-fold.

Water-absorbing resin and manufacturing method for same

Provided is a water-absorbing agent having an excellent ability to absorb and retain liquid and an excellent liquid suction power. The water-absorbing agent contains a polyacrylic acid (salt)-based water-absorbing resin as a main component and satisfies all of the following physical properties (a) to (e): (a) a weight average particle diameter (D50) is 300 &#x3bc;m or more and less than 400 &#x3bc;m; (b) a proportion of particles with a particle diameter of 600 &#x3bc;m or more and less than 850 &#x3bc;m is less than 10 weight %; (c) an average gap radius is 100 &#x3bc;m or more and less than 180 &#x3bc;m; (d) a CRC is 28 g/g or more and less than 34 g/g; and (e) an AAP is 24 g/g or more.

Water-absorbing agent and method for producing same, and absorbent article produced using water-absorbing agent

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

The present invention provides (i) a water absorbing agent which is excellent in a water absorbing physical properties, in particular water absorbing speed and has a great bulk specific gravity and (ii) a method for producing the water absorbing agent. The method for producing the water absorbing agent includes a surfactant adding step of adding a surfactant whose HLB is 10 or less. The surfactant adding step is the step of adding a dispersion liquid, which contains the surfactant equivalent to 30 parts by weight to 150 parts by weight, relative to 1000000 parts by weight of a water absorbent resin solid content, and the surfactant adding step is carried out after a drying step. Further, in a case where a water-soluble polyvalent metal salt adding step is carried out after the drying step, the surfactant adding step is carried out after the water-soluble polyvalent metal salt adding step.

Water absorbing agent and method for producing the 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 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.

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Hyogo, Japan

Nobuya Tanaka