Thermoplastic material containing absorbent pad or other article

• US 4,886,697 A
• Filed: 04/29/1988
• Issued: 12/12/1989
• Est. Priority Date: 04/29/1988
• Status: Expired due to Term

• Current Assignee: Weyerhaeuser Company (Weyerhauser)
• Original Assignee: Weyerhaeuser Company (Weyerhauser)
• Inventors: Neogi, Amar N., Young, Robert H., Perdelwitz, Lee E. Jr., Hanke, David E., Iff, Ron H., Rahkonen, Raimo K., Allison, Kathleen S.
• Primary Examiner(s): Robinson, Ellis P.
• Assistant Examiner(s): Ryan, P. J.
• Application Number:
  US07/188,474
• Time in Patent Office: 592 Days
• Field of Search: 428/280, 428/137, 428/282, 428/138, 428/284, 428/218, 428/285, 428/136, 428/286, 428/288, 428/297, 428/298, 428/903, 428/192, 428/326, 428/340, 428/920, 428/913, 428/156 , 428/171, 428/172, 297/219, 297/229, 297/DIG. 5, 5/483, 5/484, 5/487, 604/385.1, 604/379, 604/367, 604/378, 604/381, 604/393
• US Class Current: 428/192
• CPC Class Codes: A47C 27/005 liquid-impermeable
• CPC Class Codes: A47C 27/008 protecting against wear or damage
• CPC Class Codes: A47D 15/00 Accessories for children's furniture, e.g. safety belts or baby-bottle holders
• CPC Class Codes: A61F 13/1565 by depositing continuous layers of fibrous material between webs, e.g. wrapping layers of fibrous material
• CPC Class Codes: A61F 13/539 characterised by the connection of the absorbent layers with each other or with the outer layers
• CPC Class Codes: A61F 2013/15048 for protection against contamination, or protection in using body disinfecting wipes
• CPC Class Codes: A61F 2013/15056 for the protection for furniture, e.g. car seats, chairs, beds
• CPC Class Codes: A61F 2013/53024 being bicomponent fibres
• CPC Class Codes: A61F 2013/53035 of cotton
• CPC Class Codes: A61F 2013/530481 having superabsorbent materials, i.e. highly absorbent polymer gel materials
• CPC Class Codes: A61F 2013/8408 with odour control
• CPC Class Codes: A61F 5/485 Absorbent protective pads mattress underlays A47C21/06; bed linen A47G9/02
• CPC Class Codes: B32B 2262/0253 Polyolefin fibres
• CPC Class Codes: B32B 2262/0276 Polyester fibres
• CPC Class Codes: B32B 2262/067 Wood fibres
• CPC Class Codes: B32B 2307/726 Permeability to liquids, absorption
• CPC Class Codes: B32B 2307/7265 Non-permeable
• CPC Class Codes: B32B 2555/00 Personal care
• CPC Class Codes: B32B 27/12 next to a fibrous or filamentary layer
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: B32B 7/14 : applied in spaced arrangements, e.g. in stripes
• CPC Class Codes: D04H 1/5412 : sheath-core
• CPC Class Codes: D04H 1/5418 : Mixed fibres, e.g. at least two chemically different fibres or fibre blends
• CPC Class Codes: Y10S 297/05 : Fireproof
• CPC Class Codes: Y10T 428/24777 : Edge feature
• CPC Class Codes: Y10T 428/253 : Cellulosic [e.g., wood, paper, cork, rayon, etc.]
• CPC Class Codes: Y10T 428/27 : Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.]

Abstract

Materials have at least one layer comprising a mixture of thermoplastic and other fibers. This latter layer may be thermobonded together and then densified along at least a section of the eventual peripheral edge margin of an article to be formed from the material. Thermoplastic material-containing cover sheets may also be secured to the core and densified in this manner. The entire eventual peripheral edge margin of the article is typically densified. The material is cut within the densified region or slightly outside the densified region to provide a soft peripheral edge. Absorbent materials may be thermobonded within the layer and surrounded by a densified edge to fix them within the article. The composite materials are used in manufacturing infant car seat liners and other articles. In addition, sections of the material may be densified and provided with weakened areas, such as perforations, to enable users to selectively separate the articles along the perforations.

Claims

1. An absorbent article comprised of a thermobonded mixture of fibrous material which includes thermoplastic fibers, the article having a field and a densified peripheral edge margin of fiberous material along at least a section of the article, the densified peripheral edge margin of fiberous material forming a substantial liquid barrier along the at least a section of the article.

2. An article according to claim 1 in which the densified edge margin extends to the edge of the article.

3. An article according to claim 1 in which the densified edge margin is bounded at least in part by an edge of the article which is of a lower density than the densified edge margin.

4. An article according to claim 3 in which the thermobonded mixture comprises a core, the article including at least one cover sheet mounted to the core and densified along at least a section of the article.

5. An article according to claim 2 in which the thermobonded mixture comprises a core, the article including at least one cover sheet mounted to the core and densified along the at least a section of the article.

6. An article according to claim 1 also having a pattern of densified areas in the field of the article.

7. An article according to claim 6 in which the thermobonded mixture comprises a core, the article having a backing sheet of a liquid impermeable material mounted to the core and a face sheet of a liquid permeable material, the face sheet being mounted to core.

8. An article according to claim 7 in which the backing sheet is secured at every point of contact to the core.

10. An article according to claim 8 in which the face sheet contains a thermoplastic material and is heat bonded to the core.

11. An article according to claim 10 in which the backing sheet is of a thermoplastic containing material and in which the face sheet, core and backing sheet are each densified and bonded together about the periphery of the article and at a pattern of bond areas within the field of the article.

13. An article according to claim 1 which is also bonded together at a spaced pattern of bond areas.

14. An article according to claim 7 formed in the shape of an infant seat liner having a lower leg supporting portion, a central seat supporting portion and upper body supporting portion.

15. An article according to claim 8 formed in the shape of an infant seat liner having a lower leg supporting portion, a central seat supporting portion and an upper body supporting portion.

16. An article according to claim 1 in which the thermobonded mixture comprises the core, the article having a backing sheet mounted to one side of the core and a face sheet mounted to another side of the core.

19. An article according to claim 16 having a basis weight of from 80 to 450 g/m².

21. An article according to claim 1 having a taber stiffness of from 10 to 100 g-cm.

29. An article according to claim 16 in which the core is comprised of thermoplastic fibers in a weight percentage of from 5 to 40 and in which the other weight fibers comprise wood pulp in a weight percentage of from 95 to 60.

30. An article according to claim 1 in which the core is comprised of thermoplastic fibers in a weight percentage of from 5 to 40 and in which the other fibers comprise wood pulp in a weight percentage of from 95 to 60.

32. An article according to claim 1 in which the core is comprised of thermoplastic fibers in a weight percentage of from 95 to 60 and in which the other fibers comprise wood pulp in a weight percentage of from 5 to 40.

41. An article according to claim 1 including a superabsorbent material.

42. An article according to claim 1 including a moisture absorbing material.

43. An article according to claim 1 including an oil absorbing particulate polymer material.

9. An article according to claim B in which the backing sheet is adhesively secured to the core.

12. An article according to claim 9 in which the face sheet contains a thermoplastic material and the backing sheet contains a thermoplastic material and in which the face sheet, core and backing sheet are each densified and bonded together about the periphery of the article and at a pattern of bond areas within the field of the article.

17. An absorbent article comprised of a thermobonded mixture of fibrous material which includes thermoplastic fibers, the article having a field and a densified peripheral edge margin of fiberous material along at least a section of the article;

the thermobonded mixture comprising a core, the article having a backing sheet mounted to one side of the core and a face sheet mounted to another side of the core; and

the article having a Z direction tensile strength at the densified edge margin of fiberous material of greater than 25 KN/m², but not greater than the breaking point of the materials, when dry.

18. An article according to claim 17 having a Z direction tensile strength at the densified edge margin of the article of greater than 50 KN/m², but not greater than the breaking point of the materials, when dry.

20. An absorbent article comprised of a thermobonded mixture of fibrous material which includes thermoplastic fibers, the article having a field and a densified peripheral edge margin of fiberous material along at least a section of the article;

the thermobonded mixture comprising a core, the article having a backing sheet mounted to one side of the core and a face sheet mounted to another side of the core; and

in which

the density of the article at the densified edge margin of fiberous material is from 0.3 to 1.0 g/cm³.

22. An article according to claim I having a taber stiffness of from 20 to 50 g-cm.

23. An absorbent article comprised of a thermobonded mixture of fibrous material which includes some thermoplastic fibers, the article having a field and a densified peripheral edge margin of fiberous material along at least a section of the article;

the thermobonded mixture comprising a core, the article having a backing sheet mounted to one side of the core and a face sheet mounted to another side of the core; and

the face sheet containing a thermoplastic material and being heat bonded to the core, and in which there is a pattern of bonded areas in the field of the article, the article having a Z direction tensile strength at the densified edge margin of fiberous material of greater than 25 KN/m², but not greater than the breaking point of the materials, when dry, a basis weight of from 200 to 350 g/m², a density at the densified edge margin from 0.3 to 1.0 g/cm³, and a taber stiffness of from 10 to 100 g-cm, the article comprising an infant seat liner having a lower leg supporting portion, a central seat supporting portion and an upper body supporting portion.

24. An article according to claim 23 in which the core contains a superabsorbent material.

25. An article according to claim 23 in which the Z tensile strength at the densified edge margin is greater than 50 KN/m², but not greater than the breaking point of the materials, when dry and the taber stiffness is from 20 to 50 g-cm.

26. An article according to claim 23 in which the bonded areas in the field of the article occupy from at least about two to about four percent of the surface area of the article.

27. An article according to claim 23 in which there are less than ten bonded areas per square inch in the field of the article.

28. An article according to claim 23 in which the core is comprised of thermoplastic fibers in a weight percentage of from 5 to 40 and in which the other fibers comprise wood pulp in a weight percentage of from 95 to 60.

31. An article according to claim S in which the core is comprised of thermoplastic fibers in a weight percentage of about 20 and in which the other fibers comprise wood pulp in a weight percentage of about 80.

33. An absorbent article having a core comprised of a thermobonded mixture of fibrous material which includes thermoplastic fibers, the article having a field and a densified peripheral edge margin of fiberous material along at least a section of the article;

and

a facing sheet and a backing sheet which each contain a thermoplastic material, the facing and backing sheets being heat bonded to the core, and the core, facing and backing sheets being densified and bonded about the periphery of the article and being densified and bonded at a pattern of field bond locations within the field of the article.

34. An article according to claim 33 in which the facing and backing sheets are each of a liquid permeable material.

35. An article according to claim 34 in which the field bond locations comprise point bonds that are spaced approximately two inches apart.

36. An article according to claim 35 comprising a towel having a basis weight of approximately 175 g/m², a density of approximately 0.5 g/cm³, a taber stiffness of approximately from 5 to 6 g-cm, and an absorbency of approximately from 10-15 ml/g.

37. An article according to claim 34 having a basis weight of greater than 500 g/m².

38. An article according to claim 34 in which the article comprises a mat with a core having a basis weight approximately no less than 700 g/m².

39. An article according to claim 38 in which the article comprises a mat having a taber stiffness of approximately 250 g-cm.

40. An article according to claim 38 in which the pattern of bond areas comprises a quilted pattern of intersecting parallel bond lines, the parallel lines being spaced approximately one inch apart.

44. An absorbent article comprised of a thermobonded mixture of fibrous material which includes thermoplastic fibers, the article having a field and a densified peripheral edge margin of fiberous material along at least a section of the article;

and including a deodorizing material.

45. An absorbent article comprised of a thermobonded mixture of fibrous material which includes thermoplastic fibers, the article having a field and a bonded densified periphery of fibrous material and at least one elongated bond area separating the article into at least two compartments, whereby the elongated bond area provides a fold line about which the article may be folded.

46. An article according to claim 45 which is also bonded together at densified bond areas within the field of the article.

47. An article according to claim 46 in which the thermobonded mixture comprises a core, the article having a backing sheet of a thermoplastic containing liquid impermeable material mounted to the core, and a face sheet of a thermoplastic containing liquid permeable material, the face sheet being bonded to the core and being heat bonded and densified at the periphery of the article.

48. An article according to claim 47 having a first set of at least two spaced-apart transverse bond lines each extending across the article in a first direction and a second set of at least one bond line extending across the article in a second direction normal to the first direction, the bond lines separating the article into plural compartments and defining fold lines for the article.

49. An article according to claim 48 in which the bond lines of the first set are generally equally spaced apart by a first distance and in which there are at least two bond lines of the second set spaced apart a second distance which is substantially smaller than the first distance, whereby the article may be folded about the bond lines of the first set and then about the at least two bond lines of the second set to provide a compact folded article.

50. A changing pad according to claim 49 in which the pad is of a generally rectangular shape and which the bond lines of the first set are parallel to one edge of the pad and the bond lines of the second set are normal to the one edge of the pad.

51. An absorbent article comprised of a thermobonded mixture of fibrous material which includes thermoplastic fibers, the article having a field and a bonded densified peripheral edge margin of fibrous material along at least a section of the article, the mixture of fibers comprising first thermoplastic fibers of a first length greater than about one half-inch in a weight percentage of the core of from about 1 to 15, second thermoplastic fibers of a second length shorter than the first length in a weight percentage of the core of from about 5 to 85, and wood pulp fibers in a weight percentage of the core of about 5 to 95.

52. An article according to claim 51 including a thermoplastic containing facing sheet which is both thermobonded to the core and densified at the periphery of the article.

53. An article according to claim 52 including a thermoplastic containing backing sheet bonded to the core.

54. An article according to claim 53 including a pattern of heat bond locations in the field of the article.

55. An absorbent article comprised of a mixture of fibrous material which includes thermoplastic fibers having at least one bonded densified region of fiberous material and a weakened region positioned in the densified region to define a tear line so as to permit selective severing of the portion of the article along the tear line and weakened region.

56. An article according to claim 55 in which the weakened region comprises perforations positioned in the densified region.

57. An article according to claim 56 in which the densified region is positioned along at least a portion of the periphery of the article so as to provide a soft edge along the periphery when severed.

58. An article according to claim 57 in which the thermobonded mixture comprises a core, the article having a backing sheet of a thermoplastic containing liquid impermeable material mounted to the core and a face sheet of a thermoplastic containing liquid permeable material, the face sheet being heat bonded to the core, the perforations extending through the face sheet, the core and the backing sheet.

59. An article according to claim 58 in which the face sheet and backing sheet are also densified in the area of the perforations.

60. An article according to claim 55 bonded at its periphery by a bonded densified region and having at least one bonded an densified area positioned at least partially in the field of the article, the weakened area being positioned in such latter densified region to define a tear line so as to permit selective severing of the portion of the article along the tear line and weakened area.

61. An article according to claim 60 in which the thermobonded mixture comprises a core, the article having a backing sheet of a thermoplastic containing liquid impermeable material mounted to the core and a face sheet of a thermoplastic containing liquid permeable material, the face sheet being heat bonded to the core, the weakened areas comprising performations extending through the face sheet, the core and the backing sheet.

62. An article according to claim 61 in which the face sheet and backing sheet are also densified in the area of the perforations.

63. A limited life absorbent article with a field or body bounded by a peripheral edge, the article comprising a backing sheet of a thermoplastic containing material, a liquid permeable face sheet of thermoplastic containing material, an absorbent core located between the backing sheet and the face sheet, the absorbent core comprising a thermobonded mixture of fibrous material which includes thermoplastic fibers, the core extending substantially to the peripheral edge of the article, the core, backing sheet and face sheet being compressed and bonded together at the peripheral edge of the article, and at least the core and face sheet being bonded together by a spaced pattern of bond areas in the field to the article.

64. An article according to claim 63 in which the core is comprised of thermoplastic fibers having a diameter of greater than approximately nine microns.

65. An article according to claim 64 in which the density of the thermobonded peripheral edge is from approximately 0.3 to 1.0 g/cm³ and the edge has a tensile strength in the Z direction of greater than 20 KN/m² , but not greater than the breaking point of the materials, when wet.

66. An article according to claim 64 in which the basis weight of the core is from approximately 150 to 300 g/m².

67. An article according to claim 66 in which the spaced pattern of bonds is less than approximately twenty bonds per square inch, and in which the bulk of the article is from approximately 10 to 30 cc/gm.

68. An article according to claim 63 in which the core is comprised of thermoplastic fibers having a diameter of greater than approximately nine microns, in which the density of the thermobonded peripheral edge is approximately from 0.3 to 1.0 g/cm³ and the edge has a Z direction dry tensile strength of greater than, but not greater than the breaking point of the materials, approximately 50 KN/m², in which the basis weight of the core is approximately from 150 to 300 g/m², in which the spaced pattern of bonds is less than approximately twenty bonds per square inch, in which the bulk of the article is approximately from 10 to 30 cc/gm, the article being formed from a generally planar web having a cross machine direction and a machine direction, the dry tensile strength of the article in a direction perpendicular to a plane containing the article and at locations other than the edge and bond areas is from approximately 1 to 10 KN/m², and the ratio of wet to dry tensile strengths of the article in the machine and cross machine directions is from approximately 0.5 to 1.0.

69. A limited life absorbent article having a field and an edge, the article comprising:

a uniformly mixed blend of wood pulp fibers and synthetic thermoplastic fibers;

said article having a pair of major opposed outer surfaces;

said major opposed outer surfaces of the article being compressed and heat sealed at spaced locations within the field of the article; and

the entire edge of said article being compressed and heat sealed.

70. The article of claim 69 further comprising a cover enclosing said article to form a pair of outer cover layers;

and

said core and at least one of said pair of cover layers being compressed and heat sealed together at said spaced locations and along said edge.

71. The article of claim 69 in which the blend also includes synthetic non-thermoplastic fibers.

72. A limited life absorbent article comprising:

a core comprising a uniformly mixed blend of wood pulp fibers and first and second synthetic thermoplastic fibers, the first and second synthetic thermoplastic fibers having different melting points;

said second thermoplastic fiber having a higher melting point than said first thermoplastic fiber;

the core being head fused together at a temperature at least at the melting point of the first of the thermoplastic fibers and below the melting point of the second of the thermoplastic fibers so as to preserve the integrity of the second of the thermoplastic fibers;

a cover comprising a first sheet and a second sheet enclosing said core to form a pair of outer cover layers;

said core and said first and second sheets being compressed and sealed together at spaced locations;

the article having a Z direction wet strength of at least 20 KN/m², but not greater than the breaking point of the materials.

73. An article according to claim 72 in which the blend also includes synthetic non-thermoplastic fibers.

74. An article according to claim 72 wherein said first synthetic thermoplastic fiber is a polyolefin.

75. An article according to claim 74 wherein said second synthetic thermoplastic fiber is a polyester.

76. An article according to claim 74 in which said synthetic thermoplastic fibers are bicomponent fibers.

77. An article according to claim 74 in which said thermoplastic fibers are shorter than said wood pulp fibers.

78. An article according to claim 74 in which said thermoplastic fibers are longer than said wood pulp fibers.

79. An article according to claim 74 in which the second of said thermoplastic fibers are longer than said wood pulp fibers.

80. An article according to claim 79 in which the second thermoplastic fibers are generally at least one half-inch in length and comprise from 1 to 15 percent by weight of the core, the first synthetic fibers comprising from 5 to 85 percent by weight of the core.