Absorbent members for body fluids having good wet integrity and relatively high concentrations of hydrogel-forming absorbent polymer having high porosity

• US 5,562,646 A
• Filed: 04/06/1995
• Issued: 10/08/1996
• Est. Priority Date: 03/29/1994
• Status: Expired due to Term

• Current Assignee: The Procter & Gamble Company
• Original Assignee: The Procter & Gamble Company
• Inventors: Goldman, Stephen A., Retzsch, Herbert L., Mansfield, Todd L.
• Primary Examiner(s): Milano, Michael J.
• Assistant Examiner(s): ZUTTARELLI, ANTHONY
• Application Number:
  US08/416,396
• Time in Patent Office: 551 Days
• Field of Search: 604/358, 604/367-368, 604/372, 604/374-375, 428/290, 428/339
• 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 13/4702 having a reinforcing member
• 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 2013/15406 Basis weight
• CPC Class Codes: A61F 2013/15967 by meltblown technique
• CPC Class Codes: A61F 2013/530218 followed by heat treatment
• CPC Class Codes: A61F 2013/530452 having chemically-stiffened fibres
• CPC Class Codes: A61F 2013/530496 being fixed to fibres
• CPC Class Codes: A61F 2013/530547 positioned in a separate layer or layers
• CPC Class Codes: A61F 2013/530569 characterized by the particle size
• CPC Class Codes: A61F 2013/5307 characterized by the quantity or ratio of superabsorbent material
• CPC Class Codes: A61F 2013/530744 by the absorbency under load
• CPC Class Codes: A61F 2013/8491 including test methods
• CPC Class Codes: A61L 15/42 Use of materials characterised by their function or physical properties liquid bandages A61L26/00
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: Y10T 428/269 including synthetic resin or polymer layer or component

Abstract

Absorbent members useful in the containment of body fluids such as urine, that have at least one region containing hydrogel-forming absorbent polymer in a concentration of from about 60 to 100% by weight and providing a gel-continuous fluid transportation zone when in a swollen state. This hydrogel-forming absorbent polymer has: (a) a porosity of at least about 0.15; (b) a Performance under Pressure (PUP) capacity value of at least about 23 g/g under a confining pressure of 0.7 psi (5 kPa); (c) a basis weight of at least about 10 gsm; and (d) optionally, but preferably, a Saline Flow Conductivity (SFC) value of at least about 30×10^-7 cm³ sec/g. In addition, the region where this hydrogel-forming absorbent polymer is present has, even when subjected to normal use conditions, sufficient wet integrity such that the gel-continuous zone substantially maintains its ability to acquire and transport body fluids through the gel-continuous zone.

Claims

1. An absorbent member for the containment of aqueous body fluids, which comprises at least one region comprising hydrogel-forming absorbent polymer in a concentration of from about 60 to 100% by weight, said hydrogel-forming polymer providing a gel continuous fluid transportation zone when in a swollen state and having:

(a) a porosity of at least about 0.15;

(b) a Performance under Pressure (PUP) capacity value of at least about 23 g/g under a confining pressure of 0.7 psi (5 kPa);

(c) a basis weight of at least about 10 gsm;

said region having, when subjected to normal use conditions, sufficient wet integrity such that said gel continuous zone substantially maintains its ability to acquire and transport said body fluids through said gel continuous zone.

2. The absorbent member of claim 1 wherein said hydrogel-forming polymer has anionic functional groups.

3. The absorbent member of claim 2 wherein said anionic functional groups of said hydrogel-forming polymer are carboxy groups.

4. The absorbent member of claim 3 wherein said hydrogel-forming polymer is surface crosslinked.

5. The absorbent member of claim 4 wherein said hydrogel-forming polymer is selected from the group consisting of hydrolyzed starch-acrylonitrile graft copolymers;

partially neutralized hydrolyzed starch-acrylonitrile graft copolymers;

starch-acrylic acid graft copolymers, partially neutralized starch-acrylic acid graft copolymers;

saponified vinyl acetate-acrylic ester copolymers;

hydrolyzed acrylonitrile copolymers;

hydrolyzed acrylamide copolymers;

slightly network crosslinked products of any of the foregoing copolymers;

partially neutralized polyacrylic acid;

slightly network crosslinked products of partially neutralized polyacrylic acid; and

mixtures thereof.

6. The absorbent member of claim 1 wherein said hydrogel-forming polymer is in the form of particles.

7. The absorbent member of claim 6 wherein said particles of said hydrogel-forming polymer have a particle size in the range of from about 20 to about 1500 microns.

8. The absorbent member of claim 7 wherein said hydrogel-forming polymer has a mass median particle size of from about 100 to about 800 microns.

9. The absorbent member of claim 1 where in said hydrogel-forming polymer has a porosity of from about 0.15 to about 0.40 and a PUP capacity value of from about 23 to about 35 g/g.

10. The absorbent member of claim 1 wherein said hydrogel-forming polymer has a porosity of at least about 0.18.

11. The absorbent member of claim 10 wherein said hydrogel-forming polymer has a porosity of from about 0.18 to about 0.25.

12. The absorbent member of claim 10 wherein said hydrogel-forming polymer has a porosity of at least about 0.20.

13. The absorbent member of claim 1 wherein said hydrogel-forming polymer has a Saline Flow Conductivity (SFC) value of at least about 30×

10^-7 cm³ sec/g.

14. The absorbent member of claim 13 wherein said hydrogel-forming polymer has an SFC value of from about 30 to about 1000×

10^-7 cm³ sec/g.

15. The absorbent member of claim 14 wherein said hydrogel-forming polymer has an SFC value of from about 50 to about 500×

10^-7 cm³ sec/g.

16. The absorbent member of claim 15 wherein said hydrogel-forming polymer has an SFC value of from about 100 to about 350×

10^-7 cm³ sec/g.

17. The absorbent member of claim 1 wherein said hydrogel-forming polymer has about 15% or less extractable polymer.

18. The absorbent member of claim 17 wherein said hydrogel-forming polymer has about 10% or less extractable polymer.

19. The absorbent member of claim 1 wherein said hydrogel-forming polymer has a gel volume of at least about 20 g/g.

20. The absorbent member of claim 19 wherein said hydrogel-forming polymer has a gel volume of from about 25 to about 80 g/g.

21. The absorbent member of claim 20 wherein said hydrogel-forming polymer has a gel volume of from about 30 to about 70 g/g.

22. The absorbent member of claim 19 wherein said hydrogel-forming polymer has a gel strength of at least about 10,000 dynes/cm².

23. The absorbent member of claim 1 wherein the basis weight of said hydrogel-forming polymer in said region is at least about 20 gsm.

24. The absorbent member of claim 23 wherein the basis weight of said hydrogel-forming polymer in said region is at least about 50 gsm.

25. The absorbent member of claim 24 wherein the basis weight of said hydrogel-forming polymer in said region is at least about 100 gsm.

26. The absorbent member of claim 1 wherein said region comprises from about 70 to 100% of said hydrogel-forming polymer.

27. The absorbent member of claim 26 wherein said region comprises from about 80 to 100% of said hydrogel-forming polymer.

28. An absorbent core for acquiring, distributing and storing body fluids, which comprises a fluid storage absorbent layer comprising fibrous matrix having at least one region containing particles of a surface crosslinked hydrogel-forming absorbent polymer having carboxy functional groups, said hydrogel-forming polymer being present in said region in a concentration of from about 60 to 100% by weight, said hydrogel-forming polymer providing a gel continuous fluid transportation zone when in a swollen state and having:

(a) a porosity of from about 0.15 to about 0.40;

(b) a Performance under Pressure (PUP) capacity value of at least about 23 g/g under a confining pressure of 0.7 psi (5 kPa);

(c) a basis weight of at least about 20 gsm;

(d) a Saline Flow Conductivity (SFC) value of from about 30 to about 1000×

10^-7 cm³ sec/g;

(e) about 15% or less extractable polymer;

(f) a gel volume of from about 25 to about 80 g/g;

said region having, when subjected to normal use conditions, sufficient wet integrity such that said gel continuous zone substantially maintains its ability to acquire and transport body fluids through said gel continuous zone.

29. The absorbent core of claim 28 which further comprises a fluid acquisition layer.

30. The absorbent core of claim 29 wherein said fluid layer comprises chemically stiflened cellulosic fibers.

31. The absorbent core of claim 28 wherein said storage layer comprises a layer of said hydrogel-forming polymer contained between a first fibrous layer and a second fibrous layer.

32. The absorbent core of claim 28 wherein said storage layer further comprises thermoplastic material.

33. The absorbent core of claim 32 wherein said storage layer is thermally bonded.

34. The absorbent core of claim 32 wherein said thermoplastic material is thermoplastic binder fibers.

35. The absorbent core of claim 28 wherein said region comprises from about 70 to 100% of said hydrogel-forming polymer.

36. The absorbent core of claim 35 wherein said region comprises from about 80 to 100% of said hydrogel-forming polymer.

37. The absorbent core of claim 28 wherein the basis weight of said hydrogel-forming absorbent polymer in said region is at least about 50 gsm.

38. The absorbent core of claim 28 wherein said hydrogel-forming polymer is selected from the group consisting of hydrolyzed starch-acrylonitrile graff copolymers;

partially neutralized hydrolyzed starch-acrylonitrile graff copolymers;

starch-acrylic acid graff copolymers, partially neutralized starch-acrylic acid graff copolymers;

saponified vinyl acetate-acrylic ester copolymers;

hydrolyzed acrylonitrile copolymers;

hydrolyzed acrylamide copolymers;

slightly network crosslinked products of any of the foregoing copolymers;

partially neutralized polyacrylic acid;

slightly network crosslinked products of partially neutralized polyacrylic acid; and

mixtures thereof.

39. The absorbent core of claim 28 wherein said hydrogel-forming polymer has:

(a) a porosity of from about 0.18 to about 0.25;

(b) a Performance under Pressure (PUP) capacity value of from about 23 to about 35 g/g under a confining pressure of 0.7 psi (5 kPa);

(c) a basis weight of at least about 50 gsm;

(d) a Saline Flow Conductivity (SFC) value of from about 50 to about 500×

10^-7 cm³ sec/g;

(e) about 10% or less extractable polymer.

40. The absorbent core of claim 28 wherein said hydrogel-forming polymer has a mass median particle size of from about 100 to about 800 microns.

41. The absorbent core of claim 28 wherein said hydrogel-forming polymer has a gel strength of at least about 20,000 dynes/cm².

42. An absorbent article comprising a fluid pervious topsheet, a backsheet and the absorbent core of claim 28 positioned between said topsheet and said backsheet.

43. The absorbent article of claim 42 which is a diaper.

44. The absorbent article of claim 42 which is a training pant.

45. The absorbent article of claim 42 which is a catamenial pad.