Particulate water absorbent and process for production thereof

Patent metadata

Field	Value
Publication number	US-9775927-B2
Application number	US-201414563877-A
Country	US
Kind code	B2
Filing date	Dec 8, 2014
Priority date	Sep 29, 2009
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A particulate water absorbing agent of the present invention is a water absorbing agent containing a water absorbing resin as a main component, the particulate water absorbing agent containing a polyvalent metal cation and satisfying: (1) the polyvalent metal cation is contained in an amount between 0.001 wt % and 5 wt % relative to the amount of the water absorbing agent; (2) an absorbency without pressure (CRC) is not less than 28 (g/g) and an absorbency against pressure (AAP 4.83 kPa) is not less than 10 (g/g); (3) the absorbency against pressure and the absorbency without pressure satisfy 77 ≦AAP (4.83 kPa)+1.8×CRC≦100; and (4) a moisture content of the water absorbing agent is between 5 wt % and 20 wt %. This provides a water absorbing agent which has blocking resistance after moisture absorption, is excellent in stability to shock and suppresses Re-Wet when used in a diaper.

First claim

The invention claimed is:

1. A particulate water absorbing agent comprising, as a main component, a surface-treated polyacrylic acid (salt) water absorbing resin; a water-soluble polyvalent metal salt; and a residual monomer content not more than 500 ppm; wherein said particulate water absorbing agent satisfies the following requirements (2), (4) and (5):
(2) an absorbency without pressure (CRC) of the particulate water absorbing agent is not less than 28 (g/g) and an absorbency against pressure (AAP 4.83 kPa) of the particulate water absorbing agent is not less than 10 (g/g);
(4) a moisture content of the particulate water absorbing agent is between 5 wt % and 20 wt %; and
(5) a vertical diffusion absorbency under pressure (VDAUP) of the particulate water absorbing agent is not less than 15 g.

2. The particulate water absorbing agent according to claim 1 , which has been surface-treated with a water-soluble aluminum salt.

3. The particulate water absorbing agent according to claim 1 , which is a powder in a form of irregular fragments.

4. The particulate water absorbing agent according to claim 1 , which further satisfies the following requirement (1):
(1) the water-soluble polyvalent metal salt is contained in an amount between 0.001 wt % and 5 wt % relative to the amount of the particulate water absorbing agent.

5. The particulate water absorbing agent according to claim 1 , which further satisfies the following requirement (3):
(3) the absorbency against pressure and the absorbency without pressure satisfy the inequality: 77≦Absorbency against pressure (AAP 4.83 kPa)+1.8×Absorbency without pressure (CRC)≦100.

6. An absorbing article comprising a particulate water absorbing agent recited in claim 1 .

Assignees

• Nippon Catalytic Chem Ind

Inventors

• Kobayashi Taishi
• Imura Motohiro
• Iwamura Taku
• Wada Katsuyuki
• Nogi Kozo
• Mitsukami Yoshiro
• Abe Masato
• Ueda Hiroko
• Honda Koji

Classifications

• C08J2333/02

  Homopolymers or copolymers of acids; Metal or ammonium salts thereof · CPC title

• C08J3/245

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

• C08F220/06

  Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof · CPC title

• B01J2220/44

  Materials comprising a mixture of organic materials (materials coated or impregnated on a carrier B01J20/32) · CPC title

• B01J20/267 Primary

  Cross-linked polymers · CPC title