Vater-absorbent resin composition and its production process

• US 20060073969A1
• Filed: 02/06/2004
• Published: 04/06/2006
• Est. Priority Date: 02/10/2003
• Status: Active Grant

• Current Assignee: Nippon Shokubai Company Limited
• Original Assignee: Nippon Shokubai Company Limited
• Inventors: Sakamoto, Shigeru, Torii, Kazushi, Inoue, Hiroki, Mitsukami, Yoshiro, Nakamura, Masatoshi, Nogi, Kozo, Iwamura, Taku, Kadonaga, Kenji, Kitayama, Toshimasa, Miyake, Koji, Imura, Motohiro
• Granted Patent: US 8,247,491 B2
• Time in Patent Office: Days
• US Class Current: 502/400
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents

Abstract

There are disclosed a water-absorbent resin composition and its production process, wherein the water-absorbent resin composition causes little gel-blocking and is excellent in the liquid permeability and liquid diffusibility and is high also in the absorption performances and further is strong also against the physical damage; and there are further disclosed a water-absorbent resin composition and its production process, wherein the water-absorbent resin composition has the following further advantages, in addition to the above, of involving little segregation of the metal compound and further having a dust prevention effect. One of water-absorbent resin compositions according to the present invention is a water-absorbent resin composition comprising water-absorbent resin particles obtained by polymerizing a monomer including acrylic acid and/or its salt, with the composition having a mass-average particle diameter of 100 to 600 μm and comprising water-soluble polyvalent metal salt particles and the water-absorbent resin particles that have been surface-crosslinked.

Claims

1. A water-absorbent resin composition, which is a water-absorbent resin composition comprising water-absorbent resin particles obtained by polymerizing a monomer including acrylic acid and/or its salt,

with the composition having a mass-average particle diameter of 100 to 600 μ

m and comprising water-soluble polyvalent metal salt particles and the water-absorbent resin particles that have been surface-crosslinked.

2. A water-absorbent resin composition according to claim 1, wherein at least a part of the water-absorbent resin particles are agglomerates.

3. A water-absorbent resin composition according to claim 1 or 2, wherein the water-soluble polyvalent metal salt particles are particles of an aluminum salt having water of crystallization.

4. A water-absorbent resin composition according to claim 1 or 2, wherein the water-absorbent resin particles are those which have been surface-crosslinked with a polyhydric alcohol.

5. A water-absorbent resin composition, which is a water-absorbent resin composition comprising water-absorbent resin particles and water-soluble polyvalent metal salt particles, wherein the water-absorbent resin particles are obtained by polymerizing a monomer including acrylic acid and/or its salt,

with the composition having a saline flow conductivity of at least 50 (×

10<sup>−

7</sup>·

cm³·

s·

g<sup>−

1</sup>) and a retention ratio of the saline flow conductivity of not less than 40%.

6. A water-absorbent resin composition according to claim 5, wherein the retention ratio of the saline flow conductivity after a paint shaker test is not less than 70%.

7. A process for production of a water-absorbent resin composition, which is characterized by comprising the steps of:

adding a binder to water-absorbent resin particles obtained by polymerizing a monomer including acrylic acid and/or its salt; and

then

mixing the binder and the water-absorbent resin particles with water-soluble polyvalent metal salt particles.

8. A process for production of a water-absorbent resin composition according to claim 7, wherein the water-absorbent resin particles are surface-crosslinked ones.

9. A process for production of a water-absorbent resin composition according to claim 7, wherein the binder contains a surface-crosslinking agent.

10. A process for production of a water-absorbent resin composition according to claims 7, 8 or 9, wherein the binder includes water and/or a polyhydric alcohol.

11. A process for production of a water-absorbent resin composition according to claims 7, 8 or 9, wherein, when the binder is added to the water-absorbent resin particles, the temperature of the water-absorbent resin particles is in the range of 40 to 100°

C.

12. A water-absorbent resin composition, which comprises water-absorbent resin particles and a metal compound, wherein the water-absorbent resin particles are obtained by polymerizing a monomer including acrylic acid and/or its salt, and wherein:

the metal compound is one or more members selected from the group consisting of alkaline metal salts and polyvalent metal salts (except polyvalent metal salts of organic acids having not fewer than 7 carbon atoms per molecule); and

at least a part of the metal compound is fused to surfaces of the water-absorbent resin particles.

13. A water-absorbent resin composition according to claim 12, wherein the water-absorbent resin particles are materials having been surface-crosslinked with a compound having at least two functional groups which make a dehydration reaction or transesterification reaction with a carboxyl group.

14. A water-absorbent resin composition according to claim 12 or 13, wherein at least a part of the metal compound is fused in the form of coating at least a part of surfaces of the water-absorbent resin particles in a layered state.

15. A water-absorbent resin composition according to claim 12 or 13, wherein the metal compound has a melting point of not higher than 250°

C.

16. A water-absorbent resin composition according to claim 12 or 13, wherein the metal compound is a water-soluble polyvalent metal salt.

17. A water-absorbent resin composition according to claim 16, wherein the metal compound is a water-soluble polyvalent metal salt having water of hydration and containing aluminum.

18. A water-absorbent resin composition according to claim 12 or 13, which displays an absorption capacity of not less than 20 g/g under load.

19. A water-absorbent resin composition according to claim 12 or 13, which displays a saline flow conductivity of not less than 30 (×

10<sup>−

7</sup>·

cm³·

s·

g⁻

) for a 0.69 mass % physiological saline solution.

20. A process for production of a water-absorbent resin composition, wherein the water-absorbent resin composition includes water-absorbent resin particles and a metal compound, wherein the water-absorbent resin particles are obtained by polymerizing a monomer including acrylic acid and/or its salt, and wherein:

the metal compound is one or more members selected from the group consisting of alkaline metal salts and polyvalent metal salts (except polyvalent metal salts of organic acids having not fewer than 7 carbon atoms per molecule);

with the process comprising the steps of;

heating the water-absorbent resin particles and/or the metal compound to a temperature of not lower than the melting point of the metal compound; and

thereby fusing at least a part of the metal compound to surfaces of the water-absorbent resin particles.

21. A process for production of a water-absorbent resin composition according to claim 20, wherein the fusion is carried out under stirring of the water-absorbent resin particles and/or the metal compound.

22. A process for production of a water-absorbent resin composition according to claim 20 or 21, wherein the fusion is carried out after a surface-crosslinking treatment of the water-absorbent resin particles.

23. A process for production of a water-absorbent resin composition according to claim 20 or 21, wherein the metal compound has a melting point of not higher than 250°

C.

24. A process for production of a water-absorbent resin composition according to claim 20 or 21, wherein the metal compound is a water-soluble polyvalent metal salt having water of hydration and containing aluminum.