WATER-ABSORBING POLYMER STRUCTURE HAVING IMPROVED PERMEABILITY AND ABSORPTION UNDER PRESSURE

• US 20140350191A1
• Filed: 08/13/2014
• Published: 11/27/2014
• Est. Priority Date: 04/21/2006
• Status: Active Grant

• Current Assignee: Evonik Superabsorber GmbH (Rag-Stiftung)
• Original Assignee: Evonik Degussa GmbH (Rag-Stiftung)
• Inventors: Walden, Mirko, Schmidt, Harald, Teni, Rainer, Reimann, Armin, Furno, Franck, Issberner, Jorg, Herbe, Peter, Nielinger, Ursula, Keup, Michael
• Granted Patent: US 9,534,095 B2
• Time in Patent Office: Days
• US Class Current: 525/329.8
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: C08F 220/06 Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• CPC Class Codes: C08F 220/40 Esters of unsaturated alcohols , e.g. allyl (meth)acrylate
• CPC Class Codes: C08F 222/102 of dialcohols, e.g. ethylene glycol di(meth)acrylate or 1,4-butanediol dimethacrylate
• CPC Class Codes: C08F 222/1063 of alcohol terminated polyethers
• CPC Class Codes: C08F 8/44 Preparation of metal salts or ammonium salts
• CPC Class Codes: C08J 2300/14 Water soluble or water swellable polymers, e.g. aqueous gels
• CPC Class Codes: C08J 2333/02 Homopolymers or copolymers of acids; Metal or ammonium salts thereof
• CPC Class Codes: C08J 3/24 Crosslinking, e.g. vulcanising, of macromolecules mechanical aspects B29C35/00; crosslinking agents C08K
• CPC Class Codes: C08J 3/245 Differential crosslinking of one polymer with one crosslinking type, e.g. surface crosslinking
• CPC Class Codes: C08L 101/14 the macromolecular compounds being water soluble or water swellable, e.g. aqueous gels
• CPC Class Codes: C08L 33/02 Homopolymers or copolymers of acids; Metal or ammonium salts thereof

Abstract

The present invention relates to a process for the preparation of water-absorbing polymer structures, comprising the following process steps:

• i) providing an untreated, water-absorbing polymer structure; and
• ii) bringing the untreated, water-absorbing polymer structure into contact with a salt comprising a divalent or higher-valent cation of a metal and at least one organic base as anion.

The invention relates also to the water-absorbing polymer structures obtainable by that process, to water-absorbing polymer structures, to a composite comprising a water-absorbing polymer structure and a substrate, to a process for the preparation of a composite, to the composite obtainable by that process, to chemical products, such as foams, molded articles and fibers comprising water-absorbing polymer structures or a composite, to the use of water-absorbing polymer structures or of a composite in chemical products and to the use of a salt in the treatment of the surface of water-absorbing polymer structures.

Claims

1-35. -35. (canceled)

36. A process for the preparation of a water-absorbing polymer structure, comprising the following process steps:

i) providing an untreated, water-absorbing polymer structure;

ii) bringing the untreated, water-absorbing polymer structure into contact with from about 0.1 to about 5 wt % based on the weight of the untreated, water-absorbing polymer structure, of a salt comprising at least about 50 wt % of the salt, of aluminum lactate.

37. The process according to claim 36, wherein the salt comprises from about 0.6 wt % to about 2 wt % based on the water-absorbing polymer structure, of aluminum lactate.

38. The process according to claim 36, wherein the salt comprises from about 0.6 wt % to about 1 wt % based on the water-absorbing polymer structure, of aluminum lactate.

39. The process according to claim 36, wherein the salt comprises at least about 75 wt % of the salt, of aluminum lactate.

40. The process according to claim 36, wherein the salt comprises at least about 100 wt % of the salt, of aluminum lactate.

41. The process according to claim 36, wherein the salt comprises from about 0.2 wt % to about 1 wt % based on the water-absorbing polymer structure of aluminum lactate and an amount of aluminum sulfate wherein the amount of aluminum lactate and aluminum sulfate is at least 0.6 wt % based on the water-absorbing polymer structure.

42. The process according to claim 36, wherein in process step ii) the untreated, water-absorbing polymer structure is brought into contact with the salt in the presence of at most about 15% by weight, based on the weight of the untreated, water-absorbing polymer structure, of a solvent.

43. The process according to claim 36, of which more than about 80% by weight, relative to the water-absorbing polymer structure, are based on acrylic acid, of which in a range of from about 50 to about 85 mol % are neutralized, the water-absorbing polymer structure having the following properties:

A1 a saline flow conductivity (SFC) determined in accordance with the test method described herein of from about 10×

10<sup>−

7</sup> cm³s/g to about 180×

10<sup>−

7</sup> cm³s/g;

B1 a retention (CRC) determined according to ERT 441.2-02 of at least about 25 g/g; and

C1 a particle size distribution with at least about 80% by weight of the particles of the water-absorbing polymer structure in a particle size range of from about 150 to about 850 μ

m, at least about 5% by weight of the particles of water-absorbing polymer structure having a particle size in a range of from about 150 to about 250 μ

m.

44. A water-absorbing polymer structure comprising,

an untreated, water absorbing polymer structure comprising

(A1) from about 20 to about 99.999% by weight, polymerized, ethylenically unsaturated, acid-group-carrying monomers or their salts or polymerized, ethylenically unsaturated monomers containing a protonated or quaternized nitrogen atom, or mixtures thereof;

and

(α

2) from 0.001 to about 0.5% by weight of the part (α

1), of a crosslinker;

wherein the untreated water-absorbing polymer structure forms an inner region and

an outer region surrounding the inner region, wherein the outer region comprises from about 0.1 to about 5 wt % based on the weight of the untreated, water-absorbing polymer structure, of a salt comprising at least about 50 wt % of the salt, of aluminum lactate

45. The water-absorbing polymer structure according to claim 44, wherein the salt comprises at least about 75 wt % of the salt, of aluminum lactate.

46. The water-absorbing polymer structure according to claim 44, wherein the salt comprises at least about 100 wt % of the salt, of aluminum lactate.

47. The water-absorbing polymer structure according to claim 44, wherein the salt comprises from about 0.6 wt % to about 2 wt % based on the water-absorbing polymer structure, of aluminum lactate.

48. The water-absorbing polymer structure according to claim 44, wherein the salt comprises from about 0.6 wt % to about 1 wt % based on the water-absorbing polymer structure, of aluminum lactate.

49. The water-absorbing polymer structure according to claim 44, wherein the salt comprises from about 0.2 wt % to about 1 wt % based on the water-absorbing polymer structure of aluminum lactate and an amount of aluminum sulfate wherein the amount of aluminum lactate and aluminum sulfate is at least 0.6 wt % based on the water-absorbing polymer structure.

50. The water-absorbing polymer structure according to claim 44, of which more than about 80% by weight, relative to the water-absorbing polymer structure, are based on acrylic acid, of which in a range of from about 50 to about 85 mol % are neutralized, the water-absorbing polymer structure having the following properties:

A1 a saline flow conductivity (SFC) determined in accordance with the test method described herein of from about 10×

10<sup>−

7</sup> cm³s/g to about 180×

10<sup>−

7</sup> cm³s/g;

B1 a retention (CRC) determined according to ERT 441.2-02 of at least about 25 g/g; and

C1 a particle size distribution with at least about 80% by weight of the particles of the water-absorbing polymer structure in a particle size range of from about 150 to about 850 μ

m, at least about 5% by weight of the particles of water-absorbing polymer structure having a particle size in a range of from about 150 to about 250 μ

m.

51. The water-absorbing polymer structure according to claim 44, wherein the outer region further comprises from about 0.01 wt % to about 1 wt % based on the water-absorbing polymer structure, of aluminum sulfate.

52. A composite comprising a water-absorbing polymer structure according to claim 44 and a substrate.