Particulate water-absorbing agent and production method for the same

Patent metadata

Field	Value
Publication number	US-9669386-B2
Application number	US-201113876728-A
Country	US
Kind code	B2
Filing date	Sep 30, 2011
Priority date	Sep 30, 2010
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

A particulate water-absorbing agent containing a surface-crosslinked polyacrylic acid (salt)-type water-absorbing resin as a main component and at least one spacer selected from a polycation and water-insoluble fine particles. The particulate water-absorbing agent has a free swell capacity (FSC) of 55 to 65 g/g, an absorption against pressure (AAP—4.83 kPa) of 20 to 30 g/g, and a vertical diffusion absorption amount under pressure (VDAUP—4.83 kPa) of 30 to 80 g. Also disclosed is a method for producing a particulate water-absorbing agent, an absorbent core containing the particulate water-absorbing agent, and an absorbing article containing the absorbent core.

First claim

The invention claimed is:

1. A particulate water-absorbing agent comprising a surface-crosslinked polyacrylic acid (salt)-type water-absorbing resin as a main component, and comprising at least one spacer selected from a polycation and water-insoluble fine particles,
the particulate water-absorbing agent having a free swell capacity (FSC) of 55 to 65 [g/g], an absorption against pressure (AAP—4.83 kPa) of 20 to 30 [g/g], and a vertical diffusion absorption amount under pressure (VDAUP—4.83 kPa) of 30 to 80 g.

2. The particulate water-absorbing agent according to claim 1 , wherein the polycation is a polyamine polymer having a molecular weight of 1,000 or greater.

3. The particulate water-absorbing agent according to claim 2 , wherein the content of the polyamine polymer is greater than or equal to 0.001 parts by weight and less than 0.3 parts by weight, relative to 100 parts by weight of the water-absorbing resin.

4. The particulate water-absorbing agent according to claim 1 , wherein the polycation is a water-soluble polyvalent metal cation.

5. The particulate water-absorbing agent according to claim 4 , wherein the content of the water-soluble polyvalent metal cation is 0.001 parts to 3 parts by weight relative to 100 parts by weight of the water-absorbing resin.

6. The particulate water-absorbing agent according to claim 1 , wherein the water-insoluble fine particles are inorganic fine particles.

7. The particulate water-absorbing agent according to claim 1 , wherein the content of the water-insoluble fine particles is 0.001 parts to 0.4 parts by weight relative to 100 parts by weight of the water-absorbing resin.

8. The particulate water-absorbing agent according to claim 1 , further comprising a polyhydric alcohol.

9. The particulate water-absorbing agent according to claim 8 , wherein the polyhydric alcohol is propanediol.

10. The particulate water-absorbing agent according to claim 8 , wherein the content of the polyhydric alcohol is 0.01 parts to 3 parts by weight relative to 100 parts by weight of the water-absorbing resin.

11. The particulate water-absorbing agent according to claim 1 , further comprising an α-hydroxycarboxylic acid.

12. The particulate water-absorbing agent according to claim 11 , wherein the content of the α-hydroxycarboxylic acid is 0.01 parts to 3 parts by weight relative to 100 parts by weight of the water-absorbing resin.

13. The particulate water-absorbing agent according to claim 1 , wherein the polyacrylic acid (salt)-type water-absorbing resin is surface-crosslinked with a surface crosslinking agent other than a polycation.

14. The particulate water-absorbing agent according to claim 1 , further comprising a plant component.

15. The particulate water-absorbing agent according to claim 14 , wherein the content of the plant component is greater than 0 parts and less than or equal to 10 parts by weight relative to 100 parts by weight of the water-absorbing resin.

16. A method for producing a particulate water-absorbing agent comprising a polyacrylic acid (salt)-type water-absorbing resin as a main component, the method comprising a polymerization step for polymerizing a water-soluble unsaturated monomer comprising acrylic acid (salt) as a main component, a drying step, and a surface-crosslinking step, the method comprising the following steps (A), (B) and (D):
Step (A): a step for obtaining water-absorbing resin particles having an centrifuge retention capacity (CRC) of 40 to 56 [g/g] before the surface-crosslinking step;
Step (B): a step for surface-crosslinking the water-absorbing resin particles obtained in the step (A), and thereby obtaining a water-absorbing resin powder having an centrifuge retention capacity (CRC) of 32 to 40 [g/g] and an absorption against pressure (AAP—4.83 kPa) of 20 to 30 [g/g]; and
Step (D): a step for mixing 100 parts by weight of the water-absorbing resin powder obtained in the step (B) with 0.001 parts to 3 parts by weight of a polyvalent metal cation as an aqueous solution.

17. A method for producing a particulate water-absorbing agent comprising a polyacrylic acid (salt)-type water-absorbing resin as a main component, the method comprising a polymerization step for polymerizing a water-soluble unsaturated monomer comprising acrylic acid (salt) as a main component, a drying step, and a surface-crosslinking step,
the method comprising the following steps (A), (B) and (E):
Step (A): a step for obtaining water-absorbing resin particles having an centrifuge retention capacity (CRC) of 40 to 56 [g/g] before the surface-crosslinking step;
Step (B): a step for surface-crosslinking the water-absorbing resin particles obtained in the step (A), and thereby obtaining a water-absorbing resin powder having an centrifuge retention capacity (CRC) of 32 to 40 [g/g] and an absorption against pressure (AAP—4.83 kPa) of 20 to 30 [g/g]; and
Step (E): a step for mixing 100 parts by weight of the water-absorbing resin powder obtained in the step (B) with a polyamine polymer in an amount of greater than or equal to 0.001 parts and less than 0.3 parts by weight as an aqueous solution or a powder.

18. A method for producing a particulate water-absorbing agent comprising a polyacrylic acid (salt)-type water-absorbing resin as a main component, the method comprising a polymerization step for polymerizing a water-soluble unsaturated monomer comprising acrylic acid (salt) as a main component, a drying step, and a surface-crosslinking step,
the method comprising the following steps (A), (B) and (F):
Step (A): a step for obtaining water-absorbing resin particles having an centrifuge retention capacity (CRC) of 40 to 56 [g/g] before the surface-crosslinking step;
Step (B): a step for surface-crosslinking the water-absorbing resin particles obtained in the step (A), and thereby obtaining a water-absorbing resin powder having an centrifuge retention capacity (CRC) of 32 to 40 [g/g] and an absorption against pressure (AAP—4.83 kPa) of 20 to 30 [g/g]; and
Step (F): a step for mixing 100 parts by weight of the water-absorbing resin powder obtained in the step (B) with 0.001 parts to 0.4 parts by weight of water-insoluble fine particles as a powder.

19. The method according to claim 16 , wherein, in the step (B), the decrement of the absorption capacity defined by the following formula is 7 [g/g] or greater:
Decrement of absorption capacity [g/g]={Centrifuge retention capacity (CRC) before surface crosslinking}−{Centrifuge retention capacity (CRC) after surface crosslinking}  [Mathematical Formula 1]

20. The method according to claim 19 , wherein the decrement of the absorption capacity is 16 [g/g] or less.

21. The method according to claim 16 , wherein, in the step (B) or in the steps after the step (B), the polycation selected from a polyvalent metal cation or a polyamine polymer is incorporated as an aqueous solution comprising a polyhydric alcohol or an α-hydroxycarboxylic acid.

22. An absorbent core comprising the particulate water-absorbing agent according to claim 1 .

23. The absorbent core according to claim 22 , wherein the absorbent core is molded to comprise the particulate water-absorbing agent and optionally a fibrous base material, and the content of the particulate water-absorbing agent is 40% to 90% by weight.

24. An absorbing article comprising the absorbent core according to claim 22 .

25. The absorbent core of claim 22 , wherein the particulate water absorbing ag

Assignees

• Wada Katsuyuki
• Nakashima Yasuhisa
• Nippon Catalytic Chem Ind

Inventors

• Wada Katsuyuki
• Nakashima Yasuhisa

Classifications

• B01J20/267

  Cross-linked polymers · CPC title

• A61L15/60

  Liquid-swellable gel-forming materials, e.g. super-absorbents · CPC title

• C08J3/203

  Solid polymers with solid and/or liquid additives · CPC title

• C08J3/245

  Differential crosslinking of one polymer with one crosslinking type, e.g. surface crosslinking · CPC title

• B01J20/3085

  Chemical treatments not covered by groups B01J20/3007 - B01J20/3078 · CPC title