Walter-absorbing agent

• US 20060204755A1
• Filed: 02/02/2004
• Published: 09/14/2006
• Est. Priority Date: 02/10/2003
• Status: Active Grant

• Current Assignee: Nippon Shokubai Company Limited
• Original Assignee: Nippon Shokubai Company Limited
• Inventors: Torii, Kazushi, Mitsukami, Yoshiro, Iwamura, Taku, Imura, Motohiro
• Granted Patent: US 7,638,570 B2
• Time in Patent Office: Days
• US Class Current: 428/402
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: C08J 3/245 Differential crosslinking of one polymer with one crosslinking type, e.g. surface crosslinking
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

There is disclosed a water-absorbing agent which combines both performances of the capillary suction force and the liquid permeability. This water-absorbing agent is a particulate water-absorbing agent comprising water-absorbent resin particles (α) and a liquid-permeability-enhancing agent (β), wherein the water-absorbent resin particles (α) are surface-crosslink-treated particles of a crosslinked polymer of a monomer including acrylic acid and/or its salt; with the water-absorbing agent being characterized in that the particulate water-absorbing agent has: a mass-average particle diameter (D50) in the range of 234 to 394 gm, a logarithmic standard deviation (σξY) of a particle diameter distribution in the range of 0.25 to 0.45, an absorption capacity without load (CRC) of not less than 15 g/g, and a water-extractable component content of not higher than 15 mass %; and further a liquid-permeability-enhancing agent (β) content in the range of 0.01 to 5 mass parts per 100 mass parts of the water-absorbent resin particles (α).

Claims

1. A water-absorbing agent, which is a particulate water-absorbing agent comprising water-absorbent resin particles (α

) and a liquid-permeability-enhancing agent (β

), wherein the water-absorbent resin particles (α

) are further-surface-crosslink-treated irregular-shaped pulverized particles of a crosslinked polymer of a monomer including acrylic acid and its salt;

wherein the particulate water-absorbing agent has;

a mass-average particle diameter in the range of 234 to 394 μ

m, a logarithmic standard deviation (σ

ξ

) of a particle diameter distribution in the range of 0.25 to 0.45, an absorption capacity of not less than 15 g/g without load, and a water-extractable component content of not higher than 15 mass %; and

further

a liquid-permeability-enhancing agent (β

) content in the range of 0.01 to 5 mass parts per 100 mass parts of the water-absorbent resin particles (α

).

2. A water-absorbing agent according to claim 1, wherein the water-absorbent resin particles (α

) included in the water-absorbing agent include particles having a porous structure.

3. A water-absorbing agent according to claim 1 or 2, which includes particles having particle diameters in the range of 100 to 500 μ

m in an amount of not smaller than 80 mass % relative to the water-absorbing agent.

4. A water-absorbing agent according to claim 1 or 2, wherein the water-absorbing agent has a mass ratio (particles having particle diameters of not smaller than 300 μ

m)/(particles having particle diameters of smaller than 300 μ

m) in the range of 80/20 to 20/80.

5. A water-absorbing agent according to claim 1 or 2, wherein the water-absorbing agent displays a capillary absorption capacity of not less than 15 g/g for a 0.90 mass % physiological saline solution.

6. A water-absorbing agent according to claim 1 or 2, wherein the water-absorbing agent displays a saline flow conductivity of not less than 50 (10⁻

7·

cm³·

s·

g<sup>−

1</sup>) for a 0.69 mass % physiological saline solution.

7. A water-absorbing agent according to claim 1 or 2, wherein the absorption capacity of the water-absorbing agent without load is less than 29 g/g.

8. A water-absorbing agent according to claim 1 or 2, wherein the liquid-permeability-enhancing agent (β

) includes water-insoluble hydrophilic inorganic fine particles and a water-soluble polyvalent metal salt.