PREPARATION OF HIGHLY PERMEABLE, SUPERABSORBENT POLYMER STRUCTURES

• US 20090105389A1
• Filed: 04/20/2007
• Published: 04/23/2009
• 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, Reimann, Armin, Teni, Rainer
• Granted Patent: US 9,133,342 B2
• Time in Patent Office: Days
• US Class Current: 524/437
• CPC Class Codes: C08L 101/14 the macromolecular compounds being water soluble or water swellable, e.g. aqueous gels

Abstract

The present invention relates to a superabsorber composition comprising

• • an at least surface-crosslinked, water-absorbing polymer structure having a structure surface,
  • a large number of fine particles at least partly immobilized on the structure surface.

The invention furthermore relates to a process for the preparation of a superabsorber composition, the superabsorber composition obtainable by this process, a composite comprising the superabsorber composition according to the invention, a process for the production of a composite, the composite obtainable by this process, the use of the superabsorber composition according to the invention in chemical products and chemical products comprising the superabsorber composition according to the invention or the composite according to the invention.

Claims

1. A superabsorber composition comprising:

a) a surface-crosslinked, water-absorbing polymer structure having a structure surface, and

b) a large number of fine particles at least partly immobilized on the structure surface.

2. The superabsorber composition according to claim 1 wherein the fine particles are immobilized via a binder.

3. The superabsorber composition according to claim 1 wherein at least two of the large number of fine particles are combined with one another to form a fine particle agglomerate.

4. The superabsorber composition according to claim 2 wherein the binder comprises an organic compound as a main binder component.

5. The superabsorber composition according to claim 4 wherein the organic compound is a solid at about 20°

C.

6. The superabsorber composition according to claim 4 wherein the organic compound is a polymer.

7. The superabsorber composition according to claim 4 wherein the organic compound is a linear polymer.

8. The superabsorber composition according to claim 4 wherein the organic compound is a linear polyether.

9. The superabsorber composition according to claim 4 wherein the organic compound has a weight-average molecular weight M_w in a range of from about 100 to about 1,000,000 g/mol.

10. The superabsorber composition according to claim 4 wherein the organic compound is a polyalkylene glycol.

11. The superabsorber composition according to claim 4 wherein the organic compound is a polyethylene glycol or polypropylene glycol.

12. The superabsorber composition according to claim 4 wherein at least about 50 wt. % of the fine particles have an average particle diameter in a range of from about 10 to about 1,000 μ

m.

13. The superabsorber composition according to claim 4 wherein the fine particles are inorganic.

14. The superabsorber composition according to claim 4 wherein the fine particles contain an at least divalent metal cation.

15. The superabsorber composition according to claim 4 wherein the fine particles contain aluminum.

16. The superabsorber composition according to claim 4 wherein the fine particles are in the form of a salt.

17. The superabsorber composition according to claim 4 wherein the fine particles comprise at least two different types of fine particles.

31. A product comprising a superabsorber composition according to claim 1.

32. A use of a superabsorber composition according to claim 1.

18. A process for the preparation of a superabsorber composition comprising as process steps:

i) providing a surface-crosslinked, water-absorbing polymer structure having a structure surface;

ii) providing a fine particle component comprising a large number of fine particles,

iii) mixing of the fine particle component comprising a large number of fine particles with the water-absorbing polymer structure; and

iv) immobilizing of at least some of the fine particles on the structure surface.

19. The process according to claim 18, wherein the fine particle component additionally comprises a binder.

20. The process according to claim 19, wherein the fine particle component is premixed with the binder before the mixing with the water-absorbing polymer structure.

21. The process according to claim 18 wherein the immobilizing is carried out by heating.

22. The process according to claim 18 wherein the immobilizing is carried out by heating to not more than about 10% above the softening temperature of a constituent of the fine particle component.

23. A composition obtainable by a process according to claim 18.

24. The composition according to claim 23, wherein the composition is characterized by at least one of the following properties:

(β

1) an AAP value, determined in accordance with ERT 442.2-02 under a pressure of 0.3 psi, of at least about 15 g/g;

(β

2) an AAP value, determined in accordance with ERT 442.2-02 under a pressure of 0.7 psi, of at least about 12 g/g;

(β

3) an SFC value, determined in accordance with the test method described herein, of at least about 110×

10<sup>−

7</sup> cm³s/g at a CRC value, determined in accordance with ERT 441.2-02, of greater than 20 g/g to less than or equal to 22 g/g;

(β

4) an SFC value, determined in accordance with the test method described herein, of at least about 90×

10<sup>−

7</sup> cm³s/g at a CRC value, determined in accordance with ERT 441.2-02, of greater than 22 g/g to ≦

24 g/g;

(β

5) an SFC value, determined in accordance with the test method described herein, of at least about 70×

10<sup>−

7</sup> cm³s/g at a CRC value, determined in accordance with ERT 441.2-02, of greater than 24 g/g to less than or equal to 26 g/g;

(β

6) an SFC value, determined in accordance with the test method described herein, of at least about 50×

10<sup>−

7</sup> cm³s/g at a CRC value, determined in accordance with ERT 441.2-02, of greater than 26 g/g to less than or equal to 28 g/g;

(β

7) an SFC value, determined in accordance with the test method described herein, of at least about 30×

10<sup>−

7</sup> cm³s/g at a CRC value, determined in accordance with ERT 441.2-02, of greater than 28 g/g to less than or equal to 30 g/g;

or

(β

8) an SFC value, determined in accordance with the test method described herein, of at least about 10×

10<sup>−

7</sup> cm³s/g at a CRC value, determined in accordance with ERT 441.2-02, of greater than 30 g/g.

25. A composite comprising a superabsorber composition according to claim 23 and a substrate.

26. A process for the production of a composite comprising a superabsorber composition according to claim 23 and a substrate, wherein the polymer structures and the substrate are brought into contact with one another.

27. The process according to claim 26, comprising the following process steps:

I) providing the substrate;

II) providing an at least surface-crosslinked, water-absorbing polymer structure having a structure surface;

III) providing a fine particle component comprising a large number of fine particles;

IV) bringing the substrate into contact with the surface-crosslinked, water-absorbing polymer structure;

V) bringing the surface-crosslinked, water-absorbing polymer structure into contact with the fine particle component; and

VI) immobilizing some of the fine particles on the structure surface.

28. The process according to claim 27, wherein process step V) is carried out after process step IV).

29. The process according to claim 27, wherein process step V) is carried out before process step IV).

30. A composite obtainable by a process according to claim 26.