Water-Absorbing Polymer Structure Surface-Treated with Polycations

• US 20080280128A1
• Filed: 04/21/2006
• Published: 11/13/2008
• Est. Priority Date: 04/22/2005
• Status: Abandoned Application

• Current Assignee: Evonik Degussa GmbH
• Original Assignee: Evonik Degussa GmbH
• Inventors: Walden, Mirko, Furno, Franck, Schmidt, Harald, Issberner, Jorg
• Application Number:
  US11/912,241
• Publication Number:
  US 20080280128A1
• Time in Patent Office: Days
• US Class Current: 428/327
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: Y10T 428/254 Polymeric or resinous material
• CPC Class Codes: Y10T 428/2998 including synthetic resin or polymer

Abstract

The present invention relates to water-absorbing polymer structures, whose surface has been brought into contact with a compound comprising a polycation and at least one anion. The invention further relates to a process for treating the surface of water-absorbing polymer structures, the surface-treated water-absorbing polymer structures obtainable by this process, a composite comprising a surface-treated, water-absorbing polymer structure as well as a substrate, a process for production of a composite, the composite obtainable by this process, chemical products such as foams, formed bodies, and fibers comprising surface-treated water-absorbing polymer structures or a composite, the use of surface-treated, water-absorbing polymer structures or of a composite in chemical products as well as the use of compounds comprising a polycation with a given structure for the treatment of the surface of water-absorbing polymer structures.

Claims

1. A water-absorbing polymer structure, whose surface has been brought into contact with a compound comprising a polycation and at least one anion and which has an absorption under a pressure of 50 g/cm² of at least about 16 g/g.

3. The water-absorbing polymer structure according to claim 1, comprising an inner region and an outer region surrounding the inner region, wherein the outer region has a higher degree of crosslinking than the inner region.

4. The water-absorbing structure according to claim 1 wherein the polycation has the structure I

5. A polymer structure according to claim 4 wherein R¹ and R¹ represent a methyl group.

6. The polymer structure according to claim 4 wherein n has a value of at least about 1,000.

7. The polymer structure according to claim 4 wherein n has a value of at least about 2,000.

8. The polymer structure according to claim 4 wherein n has a value of at least about 3,000.

9. The polymer structure according to claim 4 wherein the anion is a chloride ion.

10. The polymer structure according to claim 4 wherein the polymer structure has at least one of the following properties:

(β

1) no caking after three hours;

(β

2) with a CRC value of less than about 26 g/g, an SFC value of at least about 80×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

3) with a CRC value within the range from about 26 to less than 27 g/g, an SFC value of at least about 70×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

4) with a CRC value within the range from about 27 to less than 28 g/g, an SFC value of at least about 60×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

5) with a CRC value within the range from about 28 to less than 29 g/g, an SFC value of at least about 45×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

6) with a CRC value within the range from about 29 to less than 30 g/g, an SFC value of at least about 30×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

7) with a CRC value within the range from about 30 to less than 31 g/g, an SFC value of at least about 20×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

8) with a CRC value of at least about 31 g/g, an SFC value of at least about 10×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

9) a Wicking Index after one minute of at least about 7.5 cm;

(β

10) a degree of neutralization of at most about 75 mol %.

17. A composite comprising a water-absorbing polymer structure according to claim 1 and a substrate.

25. The polymer structure according to claim 5 wherein n has a value of at least about 1,000.

26. The polymer structure according to claim 5 wherein n has a value of at least about 2,000.

27. The polymer structure according to claim 5 wherein n has a value of at least about 3,000.

28. The polymer structure according to claim 5 wherein the anion is a chloride ion.

29. The polymer structure according to claim 5 wherein the polymer structure has at least one of the following properties:

(β

1) no caking after three hours;

(β

2) with a CRC value of less than about 26 g/g, an SFC value of at least about 80×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

3) with a CRC value within the range from about 26 to less than 27 g/g, an SFC value of at least about 70×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

4) with a CRC value within the range from about 27 to less than 28 g/g, an SFC value of at least about 60×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

5) with a CRC value within the range from about 28 to less than 29 g/g, an SFC value of at least about 45×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

6) with a CRC value within the range from about 29 to less than 30 g/g, an SFC value of at least about 30×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

7) with a CRC value within the range from about 30 to less than 31 g/g, an SFC value of at least about 20×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

8) with a CRC value of at least about 31 g/g, an SFC value of at least about 10×

10<sup>−

7</sup> cm³ s g<sup>−

1</sup>;

(β

9) a Wicking Index after one minute of at least about 7.5 cm;

(β

10) a degree of neutralization of at most about 75 mol %.

2. A water-absorbing polymer structure, whose surface has been brought into contact with a compound comprising a polycation and at least one anion, wherein the compound comprising a polycation and at least one anion has a weight average molecular weight of more than about 3,000 g/mol.

23. The water-absorbing polymer structure according to claim 2 comprising an inner region and an outer region surrounding the inner region, wherein the outer region has a higher degree of crosslinking than the inner region.

24. The water-absorbing structure according to claim 2 wherein the polycation has the structure I

11. A process for treatment of the surface of water-absorbing polymer structures, comprising the following steps:

i) providing an untreated water-absorbing polymer structure,

ii) bringing into contact the untreated water-absorbing polymer structure with a compound comprising at least one anion and a polycation, and

iii) post-crosslinking the water-absorbing polymer structure,

wherein the process step iii) can be carried out before, during or after process step ii).

12. The process according to claim 11, wherein the polycation has the structure I

13. The process according to claim 11 wherein the water-absorbing polymer structure is brought into contact with the compound in an amount within a range from about 0.001 to about 10 wt. %, based on the weight of the water-absorbing polymer structure.

14. The process according to claim 11 wherein the compound is brought into contact with the water-absorbing polymer structure in the form of an about 10 to about 80 wt. % aqueous solution.

15. The process according to claim 11 wherein the water-absorbing polymer structure has a degree of neutralization of not more than about 70 mol %.

30. The process according to claim 12 wherein the water-absorbing polymer structure is brought into contact with the compound in an amount within a range from about 0.001 to about 10 wt. %, based on the weight of the water-absorbing polymer structure.

31. The process according to claim 12 wherein the compound is brought into contact with the water-absorbing polymer structure in the form of a 10 to 80 wt. % aqueous solution.

16. (canceled)

18-22. -22. (canceled)