# US 9,517,289 B2 · Water-absorbing agent and method for producing the same

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- Number: US 9,517,289 B2
- Document ID: US9517289B2
- Status: Granted
- Kind: B2
- Application number: 12/680,740
- Filed: 2008-11-26
- Published: 2010-09-23
- Granted: 2016-12-13
- Earliest claimed: 2007-12-12
- Assignees: Nippon Shokubai Co., Ltd.
- Applicants: Shigeru Sakamoto; Hiroyuki Ikeuchi; Sayaka Machida
- Inventors: Shigeru Sakamoto; Hiroyuki Ikeuchi; Sayaka Machida
- Web page: https://patentgrep.com/patent/US9517289B2

## CPC

- A61L 15/60: Liquid-swellable gel-forming materials, e.g. super-absorbents
- C08G 65/3322: {acyclic}
- C08J 3/12: Powdering or granulating
- C08L 71/02: Polyalkylene oxides
- C08L 101/14: the macromolecular compounds being water soluble or water swellable, e.g. aqueous gels
- C08J 2300/14: Water soluble or water swellable polymers, e.g. aqueous gels
- C08L 33/02: Homopolymers or copolymers of acids; Metal or ammonium salts thereof
- C08L 2205/05: containing polymer components which can react with one another
- A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K)
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)

## Abstract

The present invention provides a water-absorbing agent that includes water-absorbent resin particles as essential components and is suitable for a sanitary material. A water-absorbing agent of the present invention includes water-absorbent resin particles obtained by polymerizing an unsaturated monomer having an acid group. The water-absorbing agent has centrifuge retention capacity (CRC) of 5 to 20 g/g and includes: a compound with a structure unit derived from polyalkyleneglycol other than the unsaturated monomer; and a multivalent metal salt, and accordingly the water-absorbing agent has high saline flow conductivity (SFC) in a range of the above centrifuge retention capacity (CRC).

## Claims

### Claim 1

A water-absorbing agent, comprising water-absorbent resin particles obtained by polymerizing an acid group-containing unsaturated monomer,
the water-absorbing agent having Centrifuge Retention Capacity (CRC) ranging from 5 to 20 g/g, and including (i) a compound that includes a constitutional unit derived from polyalkyleneglycol and that is other than an unsaturated monomer, said compound having a weight-average molecular weight ranging from 1000 to 6000 and (ii) polyvalent metal salt, and
the compound including no radical polymerizable group, and being free without forming a chemical bond with the water-absorbent resin particles or being separable from the water-absorbent resin particles and without forming an internal crosslinked structure in the water-absorbent resin particles,
the compound included in the water-absorbing agent falling within a range of 0.05 to 5 mass % with respect to the water-absorbing agent.

### Claim 2 (depends on 1)

The water-absorbing agent as set forth in claim 1, wherein the water-absorbent resin particles are surface-crosslinked.

### Claim 3 (depends on 1)

The water-absorbing agent as set forth in claim 1, wherein Saline Flow Conductivity (SFC) is 400 cm3·s·10−7/g or more.

### Claim 4 (depends on 1)

The water-absorbing agent as set forth in claim 1, wherein the water-absorbent resin particles are obtained by polymerization in a presence of an internal crosslinking agent containing an unsaturated monomer including a constitutional unit derived from polyalkyleneglycol.

### Claim 5 (depends on 1)

The water-absorbing agent as set forth in claim 1, wherein:
the compound including no radical polymerizable group, and being free without forming a chemical bond with the water-absorbent resin particles or being separable from the water-absorbent resin particles and without forming an internal crosslinked structure in the water-absorbent resin particles means that:
the compound includes no radical polymerizable group, and at least 50% of the compound exist without forming a covalent bond with the water-absorbent resin particles.