Mixed-bed ion-exchange hydrogel-forming polymer compositions and absorbent members comprising relatively high concentrations of these compositions

• US 6,258,996 B1
• Filed: 08/19/1999
• Issued: 07/10/2001
• Est. Priority Date: 02/19/1997
• Status: Expired due to Fees

• Current Assignee: The Procter & Gamble Company
• Original Assignee: The Procter & Gamble Company
• Inventors: Goldman, Stephen Allen
• Primary Examiner(s): Weiss, John G.
• Assistant Examiner(s): SHANOSKI, PAUL A
• Application Number:
  US09/367,758
• Time in Patent Office: 691 Days
• Field of Search: 604/358, 604/367, 604/368
• US Class Current: 604/368
• CPC Class Codes: A61F 13/15658 Forming continuous, e.g. composite, fibrous webs, e.g. involving the application of pulverulent material on parts thereof
• CPC Class Codes: A61F 13/534 having an inhomogeneous composition through the thickness of the pad A61F13/538, A61F13/539 take precedence; homogeneous cores with tissue wrapping A61F13/53
• CPC Class Codes: A61F 13/537 characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer A61F13/538 takes precedence
• CPC Class Codes: A61F 2013/15967 by meltblown technique
• CPC Class Codes: A61F 2013/530496 being fixed to fibres
• CPC Class Codes: A61F 2013/530708 characterized by the absorbency properties
• CPC Class Codes: A61F 2013/530744 by the absorbency under load
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: C08L 101/14 the macromolecular compounds being water soluble or water swellable, e.g. aqueous gels

Abstract

Disclosed are compositions comprising at least one cationic ion-exchange hydrogel-forming polymer and at least one anionic ion-exchange hydrogel-forming polymer, wherein the composition exhibits improved absorbency characteristics relative to comparable mixtures of the hydrogel-forming polymers in their neutralized state. Also disclosed are mixed-bed ion-exhange compositions having improved Performance Under Pressure values relative to prior mixed-bed compositions, which alleviate detrimental gel blocking incurred with these prior systems. Also disclosed are absorbent members useful in the containment of body fluids such as urine, that have at least one region comprising a mixed-bed ion-exchange hydrogel-forming absorbent polymer composition in a concentration of from about 60 to 100% by weight.

Claims

1. A mixed-bed ion-exchange composition comprising one or more cationic ion-exchange hydrogel-forming polymers and one or more anionic ion-exchange hydrogel-forming polymers, wherein the mixed-bed ion-exchange composition exhibits increased absorbence of an urine electrolyte solution under PUP-absorption conditions relative to a comparable mixture of the constituent cationic and anionic hydrogel-forming polymers in their neutralized forms.

2. The mixed-bed ion-exchange composition of claim 1 having a PUP capacity of at least about 20% more than the PUP capacity of the comparable mixture of the constituent cationic and anionic hydrogel-forming polymers in their neutralized forms.

3. The mixed-bed ion-exchange composition of claim 2 having a PUP capacity of at least about 50% more than the PUP capacity of the comparable mixture of the constituent cationic and anionic hydrogel-forming polymers in their neutralized forms.

4. The mixed-bed ion-exchange composition of claim 3 having a PUP capacity of at least about 100% more than the PUP capacity of the comparable mixture of the constituent cationic and anionic hydrogel-forming polymers in their neutralized forms.

5. The mixed-bed ion-exchange composition of claim 2 wherein PUP capacity measurements are made after a period of 225 minutes.

6. The mixed-bed ion-exchange composition of claim 2 wherein the PUP capacity measurements are made after a period of 60 minutes.

7. The mixed-bed ion-exchange composition of claim 2 wherein the PUP capacity measurements are made after a period of 5 minutes.

8. The mixed-bed ion-exchange composition of claim 2 wherein PUP capacity measurements are made under a confining pressure of 0.3 psi.

9. The mixed-bed ion-exchange composition of claim 2 wherein PUP capacity measurements are made under a confining pressure of 0.7 psi.

10. The mixed-bed ion-exchange composition of claim 2 wherein PUP capacity measurements are made under a confining pressure of 1.4 psi.

11. An absorbent member for the containment of aqueous body fluids, which comprises at least one region comprising the mixed-bed ion-exchange composition of claim 1 in a concentration of from about 60 to 100% by weight.

12. The absorbent member of claim 11 wherein the region comprises from about 70 to 100% of the composition.

13. The absorbent member of claim 12 wherein the region comprises from about 80 to 100% of the composition.

14. An absorbent member for the containment of aqueous body fluids having at least one region comprising a mixed-bed ion-exchange composition comprising one or more cationic ion-exchange hydrogel-forming polymers and one or more anionic ion-exchange hydrogel-forming polymers in a concentration of from about 60% to 100% by weight, wherein the composition exhibits increased absorbence of an urine electrolyte solution under PUP-absorption conditions relative to a comparable mixture of the constituent cationic and anionic hydrogel-forming polymers in their neutralized forms.

15. The absorbent member of claim 14 wherein the mixed-bed ion-exchange composition has a PUP capacity of at least about 20% more than the PUP capacity of the comparable mixture of the constituent cationic and anionic hydrogel-forming polymers in their neutralized forms.

16. A mixed-bed ion-exchange composition comprising one or more cationic ion-exchange hydrogel-forming polymers and one or more anionic ion-exchange hydrogel-forming polymers, wherein the composition has a PUP capacity at 225 minutes of at least about 25 g/g under a confining pressure of 0.7 psi.

17. The mixed-bed ion-exchange composition of claim 16 having a PUP capacity of at least about 40 g/g.

18. The mixed-bed ion-exchange composition of claim 17 having a PUP capacity of at least about 50 g/g.

19. An absorbent member for the containment of aqueous body fluids, which comprises at least one region comprising the mixed-bed ion-exchange composition of claim 16 in a concentration of from about 60 to 100% by weight.

20. An absorbent article comprising a fluid pervious topsheet, a backsheet and an absorbent core positioned between said topsheet and said backsheet, wherein the absorbent core comprises the absorbent member of claim 19.

21. The absorbent article of claim 20 which is a diaper.

22. The mixed-bed ion-exchange composition of claim 16 wherein the anionic ion-exchange hydrogel-forming polymer is selected from the group consisting of polyacrylic acid, polymaleic anhydride copolymers, and derivatives and mixtures thereof.

23. An absorbent member for the containment of aqueous body fluids, which comprises at least one region comprising the mixed-bed ion-exchange composition of claim 22.

24. The mixed-bed ion-exchange composition of claim 16 wherein the cationic ion-exchange hydrogel-forming polymer is selected from the group consisting of polyethylenimine, polyvinylamine, polydimethyldiallylammonium hydroxide, polydimethylaminoethylacrylate, polydimethylaminoethylmethacrylate, polyallylamine, and derivatives and mixtures thereof.

25. An absorbent member for the containment of aqueous body fluids, which comprises at least one region comprising the mixed-bed ion-exchange composition of claim 24.

26. The mixed-bed ion-exchange composition of claim 16, wherein the composition has an SFC value of at least about 30×

10<sup>−

7</sup> cm³sec/g.

27. The mixed-bed ion-exchange composition of claim 26 wherein the composition has an SFC value of at least about 100×

10<sup>−

7</sup> cm³sec/g.

28. An absorbent member for the containment of aqueous body fluids, which comprises at least one region comprising the mixed-bed ion-exchange composition of claim 26.

29. The mixed-bed ion-exchange composition of claim 16 wherein the composition has a PHL value of at least 0.15.

30. The mixed-bed ion-exchange composition of claim 29 wherein the composition has a PHL value of at least 0.20.

31. An absorbent member for the containment of aqueous body fluids, which comprises at least one region comprising the mixed-bed ionexchange composition of claim 29.

32. The mixed-bed ion-exchange composition of claim 16 wherein the cationic ion-exchange hydrogel-forming polymer(s) has an anionic-exchange capacity of at least about 6 meq/g.

33. The mixed-bed ion-exchange composition of claim 32 wherein the cationic ion-exchange hydrogel-forming polymer(s) has an anionic-exchange capacity of at least about 10 meq/g.

34. An absorbent member for the containment of aqueous body fluids, which comprises at least one region comprising the mixed-bed ion-exchange composition of claim 32.

35. The mixed-bed ion-exchange composition of claim 33 wherein the cationic ion-exchange hydrogel-forming polymer(s) has an anionic-exchange capacity of at least about 15 meq/g.

36. The mixed-bed ion-exchange composition of claim 16 wherein the anionic ion-exchange hydrogel-forming polymer(s) has an cationic-exchange capacity of at least about 4 meq/g.

37. The mixed-bed ion-exchange composition of claim 36 wherein the anionic ion-exchange hydrogel-forming polymer(s) has an cationic-exchange capacity of at least about 8 meq/g.

38. An absorbent member for the containment of aqueous body fluids, which comprises at least one region comprising the mixed-bed ion-exchange composition of claim 36.

39. The mixed-bed ion-exchange composition of claim 37 wherein the anionic ion-exchange hydrogel-forming polymer(s) has an cationic-exchange capacity of at least about 10 meq/g.

40. The mixed-bed ion-exchange composition of claim 16 wherein the composition has an ion-exchange capacity of at least about 4 meq/g.

41. The mixed-bed ion-exchange composition of claim 40 wherein the composition has an ion-exchange capacity of at least about 6 meq/g.

42. An absorbent member for the containment of aqueous body fluids, which comprises at least one region comprising the mixed-bed ion-exchange composition of claim 40.

43. The mixed-bed ion-exchange composition of claim 41 wherein the composition has an ion-exchange capacity of at least about 7 meq/g.

44. A mixed-bed ion-exchange composition comprising one or more cationic ion-exchange hydrogel-forming polymers and one or more anionic ion-exchange hydrogel-forming polymers, wherein the composition has a PUP capacity at 60 minutes of at least about 25 g/g under a confining pressure of 0.7 psi.

45. The mixed-bed ion-exchange composition of claim 44 having a PUP capacity of at least about 40 g/g.

46. The mixed-bed ion-exchange composition of claim 45 having a PUP capacity of at least about 50 g/g.

47. The absorbent member of claim 44 wherein the region comprises from about 60 to 100% of the mixed-bed ion-exchange composition.

48. A mixed-bed ion-exchange composition comprising one or more cationic ion-exchange hydrogel-forming polymers and one or more anionic ion-exchange hydrogel-forming polymers, wherein the composition has a PUP capacity at 225 minutes of at least about 20 g/g under a confining pressure of 1.4 psi.

49. The mixed-bed ion-exchange composition of claim 48 having PUP capacity of at least about 30 g/g.

50. The mixed-bed ion-exchange composition of claim 49 having PUP capacity of at least about 40 g/g.

51. The absorbent member of claim 48 wherein the region comprises from about 60 to 100% of the mixed-bed ion-exchange composition.