Unitary absorbent system

• US 6,734,335 B1
• Filed: 06/04/1999
• Issued: 05/11/2004
• Est. Priority Date: 12/06/1996
• Status: Expired due to Fees

• Current Assignee: Ahlstrom Glassfibre OY (Ahlstrom Oyj), National Institute for Strategic Technology Acquisition and Commercialization, Weyerhaeuser Company (Weyerhauser)
• Original Assignee: Weyerhaeuser Company (Weyerhauser)
• Inventors: Miller, Charles E., Grant, Terry M., Laine, Eino, Dopps, Melissa L., Jansson, Juhani, Mathews, Jeffrey D., Naieni, Shahrokh A., Rokman, Kay, Marsh, David G., Graef, Peter A., Howard, Fred B., Bunker, Daniel T.
• Primary Examiner(s): Lo, Weilun
• Assistant Examiner(s): KIDWELL, MICHELE M
• Application Number:
  US09/326,213
• Time in Patent Office: 1,803 Days
• Field of Search: 424/402, 428/298.4, 428/300.4, 604/327, 604/378, 604/365, 604/367, 604/383, 604/384, 442/381, 442/389, 442/358, 442/383, 442/384, 442/387, 442/388, 442/402
• US Class Current: 604/365
• CPC Class Codes: A61F 13/532 inhomogeneous in the plane of the pad
• 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 13/53743 characterised by the position of the layer relative to the other layers
• CPC Class Codes: A61F 2013/15422 Density
• CPC Class Codes: B32B 2307/7265 Non-permeable
• CPC Class Codes: B32B 2555/02 Diapers or napkins
• CPC Class Codes: B32B 5/26 another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: B32B 7/02 Physical, chemical or physicochemical properties
• CPC Class Codes: D21F 11/002 by using a foamed suspension
• CPC Class Codes: D21F 11/04 paper or board consisting on two or more layers
• CPC Class Codes: D21F 9/006 paper or board consisting of two or more layers
• CPC Class Codes: D21H 27/32 with materials applied between the sheets attaching together paper or cardboard sheets B31F5/00; adhesives C09J
• CPC Class Codes: D21H 27/38 at least one of the sheets having a fibrous composition differing from that of other sheets
• CPC Class Codes: Y10T 428/249943 Fiber is nonlinear [e.g., crimped, sinusoidal, etc.]
• CPC Class Codes: Y10T 428/249949 Two or more chemically different fibers

Abstract

A unitary absorbent composite having a plurality of strata is disclosed. In the composite, adjacent strata are separated by a transition zone integrally connecting the strata. Each stratum includes fibers and a binder, and the transition zone includes fibers from adjacent strata. Method for forming the unitary composite are also disclosed.

Claims

1. An absorbent composite comprising a first stratum, a second stratum, a third stratum, a first transition zone intermediate and coextensive with the first and second strata, and a second transition zone intermediate and coextensive with the second and third strata;

the first stratum comprising first fibers and a binder;

the second stratum comprising second fibers and a binder;

the third stratum comprising third fibers and a binder;

the first transition zone comprising fibers from the first and second strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length; and

the second transition zone comprising fibers from the second and third strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length.

2. The composite of claim 1 wherein the first, second, and third strata comprise fibers selected from the group consisting of resilient fibers, matrix fibers, and mixtures thereof.

3. The composite of claim 2 wherein the resilient fibers comprise fibers selected from the group consisting of chemically stiffened fibers, anfractuous fibers, chemithermomechanical pulp fibers, prehydrolyzed kraft pulp fibers, synthetic fibers, and mixtures thereof.

4. The composite of claim 3 wherein the synthetic fibers comprise fibers selected from the group consisting of polyolefin, polyester, polyamide, and thermobondable fibers.

5. The composite of claim 4 wherein the polyester fibers comprise polyethylene terephthalate fibers.

6. The composite of claim 3 wherein the chemically stiffened fibers comprise crosslinked cellulosic fibers.

7. The composite of claim 2 wherein the matrix fibers comprise cellulosic fibers.

8. The composite of claim 7 wherein the cellulosic fibers comprise fibers selected from the group consisting of wood pulp fibers, cotton linters, cotton fibers, hemp fibers, rayon fibers, cellulose acetate fibers, and mixtures thereof.

9. The composite of claim 1 wherein the binder is selected from the group consisting of thermoplastic fibers, soluble bonding mediums, and wet strength agents.

10. The composite of claim 9 wherein the binder comprises a fibrous binding material.

11. The composite of claim 10 wherein the fibrous binding material comprises bicomponent binding fibers.

12. The composite of claim 9 wherein the binder comprises a wet strength agent.

13. The composite of claim 1 further comprising absorbent material.

14. The composite of claim 13 wherein the absorbent material comprises a superabsorbent polymer.

15. An absorbent article comprising the composite of claim 13.

16. The composite of claim 1 wherein adjacent strata have at least one different property.

17. The composite of claim 1 having a liquid-impermeable bottom surface.

18. The composite of claim 17 wherein the first stratum comprises fibers selected from the group consisting of synthetic fibers, cellulosic fibers, eucalyptus fibers, microfibrillated fibers, and mixtures thereof.

19. The composite of claim 17 wherein the first stratum has a density in the range from about 0.3 to about 0.7 g/cm³.

20. An absorbent article comprising the composite of claim 17.

21. The composite of claim 1 wherein the first stratum comprises a densified stratum.

22. The composite of claim 21 wherein the densified stratum expands on liquid contact.

23. An absorbent article comprising the composite of claim 22.

24. The composite of claim 21 wherein the densified stratum comprises fibers selected from the group consisting of crosslinked cellulosic fibers, chemithermomechanical pulp fibers, and mixtures thereof.

25. The composite of claim 21 wherein the densified stratum has a density from about 0.1 to about 0.6 g/cm³.

26. An absorbent article comprising the composite of claim 21.

27. The composite of claim 1 wherein the third stratum comprises a liquid-impermeable bottom surface.

28. An absorbent article comprising the composite of claim 1.

29. The absorbent article of claim 28 further comprising a liquid pervious topsheet and a liquid impervious backsheet.

30. The composite of claim 1, wherein the second stratum further comprises absorbent material.

31. The composite of claim 1, wherein the second stratum comprises a densified stratum.

32. The composite of claim 1, wherein the third stratum comprises a densified stratum.

33. An absorbent composite comprising a plurality of strata, wherein adjacent strata are separated by a transition zone intermediate and coextensive with adjacent strata, wherein each stratum comprises fibers and a binder, wherein each transition zone comprises fibers from adjacent strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length, and wherein the composite comprises at least three strata.

34. The composite of claim 33 wherein the composite comprises at least four strata.

35. The composite of claim 33 wherein the composite comprises at least five strata.

36. The composite of claim 33 wherein adjacent strata have at least one different property.

37. The composite of claim 33 further comprising absorbent material.

38. An absorbent article comprising the composite of claim 33.

39. The absorbent article of claim 38 further comprising a liquid pervious topsheet and a liquid impervious backsheet.

40. An absorbent composite comprising a first stratum, a second stratum, a third stratum, a first transition zone intermediate and coextensive with the first and second strata, and a second transition zone intermediate and coextensive with the second and third strata;

the first stratum comprising synthetic fibers and a binder;

the second stratum comprising crosslinked cellulosic fibers and a binder;

the third stratum comprising synthetic fibers and a binder;

the first transition zone comprising fibers from the first and second strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length; and

the second transition zone comprising fibers from the second and third strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length.

41. The composite of claim 40 wherein the synthetic fibers comprise polyethylene terephthalate fibers.

42. The composite of claim 40 wherein the binder is selected from the group consisting of bicomponent binding fibers and a wet strength agent.

43. The composite of claim 40, wherein the second stratum further comprises absorbent material.

44. An absorbent composite comprising a first stratum, a second stratum, a third stratum, a first transition zone intermediate and coextensive with the first and second strata, and a second transition zone intermediate and coextensive with the second and third strata;

the first stratum comprising synthetic fibers and a binder;

the second stratum comprising crosslinked cellulosic fibers and a binder;

the third stratum comprising cellulosic fibers and a binder;

the first transition zone comprising fibers from the first and second strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length; and

the second transition zone comprising fibers from the second and third strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length.

45. The composite of claim 44 wherein the synthetic fibers comprise polyethylene terephthalate fibers.

46. The composite of claim 44 wherein the binder is selected from the group consisting of bicomponent binding fibers and a wet strength agent.

47. The composite of claim 44 wherein the cellulosic fibers comprise crosslinked cellulosic fibers.

48. The composite of claim 44, wherein the second stratum comprises absorbent material.

49. An absorbent composite comprising a first stratum, a second stratum, a third stratum, a first transition zone intermediate and coextensive with the first and second strata, and a second transition zone intermediate and coextensive with the second and third strata;

the first stratum comprising cellulosic fibers and a binder;

the second stratum comprising crosslinked cellulosic fibers and a binder;

the third stratum comprising cellulosic fibers and a binder;

the first transition zone comprising fibers from the first and second strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length; and

the second transition zone comprising fibers from the second and third strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length.

50. The composite of claim 49 wherein the binder is selected from the group consisting of bicomponent binding fibers and a wet strength agent.

51. The composite of claim 49 wherein the cellulosic fibers comprise polyethylene terephthalate fibers.

52. The composite of claim 49, wherein the second stratum comprises absorbent material.

53. An absorbent composite comprising a first stratum, a second stratum, a third stratum, a first transition zone intermediate and coextensive with the first and second strata, and a second transition zone intermediate and coextensive with the second and third strata;

the first stratum comprising synthetic fibers and a binder;

the second stratum comprising crosslinked cellulosic fibers, absorbent material, and a binder;

the third stratum comprising synthetic fibers and a binder;

the first transition zone comprising fibers from the first and second strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length; and

the second transition zone comprising fibers from the second and third strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length.

54. The composite of claim 53 wherein the synthetic fibers comprise polyethylene terephthalate fibers.

55. The composite of claim 53 wherein the binder is selected from the group consisting of bicomponent binding fibers and a wet strength agent.

57. The composite of claim 53 wherein the second stratum further comprises fluff pulp fibers.

58. The composite of claim 53 wherein the second stratum binder comprises a wet strength agent.

56. The composite of 53 claim wherein the absorbent material comprises a superabsorbent polymer.

59. An absorbent composite comprising a first stratum, a second stratum, a third stratum, a first transition zone intermediate and coextensive with the first and second strata, and a second transition zone intermediate and coextensive with the second and third strata;

the first stratum comprising synthetic fibers and a binder;

the second stratum comprising crosslinked cellulosic fibers, absorbent material, and a binder;

the third stratum comprising cellulosic fibers and a binder;

the first transition zone comprising fibers from the first and second strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length; and

the second transition zone comprising fibers from the second and third strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length.

60. The composite of claim 59 wherein the synthetic fibers comprise polyethylene terephthalate fibers.

61. The composite of claim 59 wherein the binder is selected from the group consisting of bicomponent binding fibers and a wet strength agent.

62. The composite of claim 59 wherein the cellulosic fibers comprise crosslinked cellulosic fibers.

63. The composite of claim 59 wherein the absorbent material comprises a superabsorbent polymer.

64. The composite of claim 59 wherein the second stratum further comprises fluff pulp fibers.

65. The composite of claim 59 wherein the second stratum binder comprises a wet strength agent.

66. An absorbent composite comprising a first stratum, a second stratum, a third stratum, a first transition zone intermediate and coextensive with the first and second strata, and a second transition zone intermediate and coextensive with the second and third strata;

the first stratum comprising cellulosic fibers and a binder;

the second stratum comprising crosslinked cellulosic fibers, absorbent material, and a binder;

the third stratum comprising cellulosic fibers and a binder;

the first transition zone comprising fibers from the first and second strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length; and

the second transition zone comprising fibers from the second and third strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length.

67. The composite of claim 66 wherein the binder is selected from the group consisting of bicomponent binding fibers and a wet strength agent.

68. The composite of claim 66 wherein the cellulosic fibers comprise crosslinked cellulosic fibers.

69. The composite of claim 66 wherein the absorbent material comprises a superabsorbent polymer.

70. The composite of claim 66 wherein the second stratum further comprises fluff pulp fibers.

71. The composite of claim 66 wherein the second stratum binder comprises a wet strength agent.