Water-absorbing polymer structure having improved permeability and absorption under pressure

Patent metadata

Field	Value
Publication number	US-9534095-B2
Application number	US-201414458761-A
Country	US
Kind code	B2
Filing date	Aug 13, 2014
Priority date	Apr 21, 2006
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

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.

First claim

The invention claimed is:

1. A process for the preparation of a water-absorbing polymer structure, 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 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, and

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 7 cm 3 s/g to about 180×10 7 cm 3 s/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 μm, 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 μm.

2. The process according to claim 1 , wherein the salt comprises from about 0.6 wt % to about 2 wt % based on the water-absorbing polymer structure, of aluminum lactate.

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

4. The process according to claim 1 , wherein the salt comprises at least about 75 wt % of the salt, of aluminum lactate.

5. The process according to claim 1 , wherein the salt comprises at least about 100 wt % of the salt, of aluminum lactate.

6. The process according to claim 1 , 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.

7. The process according to claim 1 , 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.

8. A water-absorbing polymer structure comprising,
an untreated, water absorbing polymer structure comprising
(α1) 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
(α2) from 0.001 to about 0.5% by weight of the part (α1), 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, and
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 7 cm 3 s/g to about 180×10 7 cm 3 s/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 μm, 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 μm.

9. The water-absorbing polymer structure according to claim 8 , wherein the salt comprises at least about 75 wt % of the salt, of aluminum lactate.

10. The water-absorbing polymer structure according to claim 8 , wherein the salt comprises at least about 100 wt % of the salt, of aluminum lactate.

11. The water-absorbing polymer structure according to claim 8 , wherein the salt comprises from about 0.6 wt % to about 2 wt % based on the water-absorbing polymer structure, of aluminum lactate.

12. The water-absorbing polymer structure according to claim 8 , wherein the salt comprises from about 0.6 wt % to about 1 wt % based on the water-absorbing polymer structure, of aluminum lactate.

13. The water-absorbing polymer structure according to claim 8 , 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.

14. The water-absorbing polymer structure according to claim 8 , 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.

15. A composite comprising a water-absorbing polymer structure according to claim 8 and a substrate.

Assignees

• Evonik Degussa Gmbh

Inventors

• Walden Mirko
• Schmidt Harald
• Teni Rainer
• Reimann Armin
• Furno Franck
• Issberner Jorg
• Herbe Peter
• Nielinger Ursula
• Keup Michael

Classifications

• C08L101/14

  the macromolecular compounds being water soluble or water swellable, e.g. aqueous gels · CPC title

• C08J2333/02

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

• C08F220/06

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

• C08J2300/14

  Water soluble or water swellable polymers, e.g. aqueous gels · CPC title

• A61L15/60 Primary

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