Particulate water-absorbing agent and method for producing the same

Patent metadata

Field	Value
Publication number	US-2017136441-A1
Application number	US-201515300310-A
Country	US
Kind code	A1
Filing date	Mar 31, 2015
Priority date	Mar 31, 2014
Publication date	May 18, 2017
Grant date	—

Abstract

It is an object to provide a particulate water-absorbing agent having a high fluid retention capacity under pressure and reduced moisture absorption blocking properties, and a method for producing the same.
A particulate water-absorbing agent including a water-insoluble metal phosphate including an anion of a phosphoric acid compound and a divalent or trivalent metal cation, the water-insoluble metal phosphate having a crystallite size of less than 0.15 mm, wherein the particulate water-absorbing agent has a fluid retention capacity under pressure of 2.06 kpa of 20 g/g or more.

First claim

1 . A particulate water-absorbing agent comprising a water-insoluble metal phosphate including an anion of a phosphoric acid compound and a divalent or trivalent metal cation, the water-insoluble metal phosphate having a crystallite size of less than 0.15 mm,
wherein the particulate water-absorbing agent has a fluid retention capacity under pressure of 2.06 kPa of 20 g/g or more.

2 . The particulate water-absorbing agent according to claim 1 , wherein an average primary particle size of the water-insoluble metal phosphate is less than 2.0 mm.

3 . The particulate water-absorbing agent according to claim 1 , wherein the water-insoluble metal phosphate includes at least one salt formed from:
an anion of phosphoric acid selected from the group consisting of a phosphate ion, a pyrophosphate ion, a tripolyphosphate ion, a hexapolyphosphate ion, a pentapolyphosphate ion, a heptapolyphosphate ion, a trimetaphosphate ion, a tetrametaphosphate ion, a hexametaphosphate ion, a dihydrogen phosphate ion and a hydrogen phosphate ion; and a divalent or trivalent metal cation selected from the group consisting of a calcium ion, a magnesium ion, a strontium ion, a barium ion, a zinc ion, an iron ion, an aluminum ion, a titanium ion, a zirconium ion, a hafnium ion, a tin ion, a cerium ion, a scandium ion, a yttrium ion and a lanthanum ion.

4 . The particulate water-absorbing agent according to claim 1 , wherein an amount of the water-insoluble metal phosphate added is 0.01 to 2 parts by weight per 100 parts by weight of the water-absorbing resin.

5 . The particulate water-absorbing agent according to claim 1 , wherein a mass average particle size (D50) of the particulate water-absorbing agent is 600 mm or less.

6 . The particulate water-absorbing agent according to claim 1 , wherein a CRC of the particulate water-absorbing agent is 60 g/g or less.

7 . The particulate water-absorbing agent according to claim 1 , wherein an amount of deteriorated soluble contents of the particulate water-absorbing agent is 30% or less.

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

9 . A method for producing a particulate water-absorbing agent comprising a surface crosslinking step for surface crosslinking a water-absorbing resin,
the surface crosslinking step including, before, after or during the surface crosslinking step, a step for adding a water-insoluble metal phosphate comprising: an anion of a phosphoric acid compound; and a divalent or trivalent metal cation, the water-insoluble metal phosphate having a crystallite size of less than 0.15 mm, wherein the particulate water-absorbing agent has a fluid retention capacity under pressure of 2.06 kPa of 20 g/g or more.

10 . The method according to claim 9 , wherein an average primary particle size of the water-insoluble metal phosphate is less than 2.0 mm.

11 . The method according to claim 9 , wherein an amount of the water-insoluble metal phosphate to add is 0.01 to 2 parts by weight per 100 parts by weight of the water-absorbing resin.

12 . The method according to claim 9 , wherein a mass average particle size (D50) of the particulate water-absorbing agent is 600 mm or less.

13 . The method according to claim 9 , wherein a fluid retention capacity without pressure (CRC) of the particulate water-absorbing agent is 60 g/g or less.

14 . The method according to claim 9 , wherein an amount of deteriorated soluble contents of the particulate water-absorbing agent is 30% or less.

Assignees

• Nippon Catalytic Chem Ind

Inventors

• Kobayashi Taishi
• Tamaki Mariko
• Ikeuchi Hiroyuki

Classifications

• C08J2335/02

  Characterised by the use of homopolymers or copolymers of esters (C08J2335/06, C08J2335/08 take precedence) · CPC title

• B01J20/048 Primary

  containing phosphorus, e.g. phosphates, apatites, hydroxyapatites · CPC title

• B01J20/3085

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

• B01J20/28004

  Sorbent size or size distribution, e.g. particle size · CPC title

• B01J20/267

  Cross-linked polymers · CPC title