Breathable composite sheet structure and absorbent articles utilizing same

• US 7,307,031 B2
• Filed: 01/07/2004
• Issued: 12/11/2007
• Est. Priority Date: 05/29/1997
• Status: Expired

• Current Assignee: The Procter & Gamble Company
• Original Assignee: The Procter & Gamble Company
• Inventors: Carroll, Nora Liu, Lim, Hyun Sung, Ostapchenko, George Joseph, Vaidya, Shailaja R., McKenna, J. Michael, Curro, John Joseph, Lavon, Gary Dean, Sparks, Richard L.
• Primary Examiner(s): Torres-Velazquez, Norca
• Application Number:
  US10/752,849
• Publication Number:
  US 20040142621A1
• Time in Patent Office: 1,434 Days
• Field of Search: 442/394, 442/395, 442/398, 442/399, 442/62, 442/76, 442/86, 442/77
• US Class Current: 442/76
• CPC Class Codes: A61F 13/51462 being defined by a value or parameter
• CPC Class Codes: A61F 13/5148 having an impervious inner layer and a cloth-like outer layer
• CPC Class Codes: B32B 2262/0253 Polyolefin fibres
• CPC Class Codes: B32B 2307/724 Permeability to gases, adsorption
• CPC Class Codes: B32B 2307/7265 Non-permeable
• CPC Class Codes: B32B 2535/00 Medical equipment, e.g. bandage, prostheses or catheter
• CPC Class Codes: B32B 2555/00 Personal care
• CPC Class Codes: B32B 27/12 next to a fibrous or filamentary layer
• CPC Class Codes: D04H 1/4291 Olefin series
• CPC Class Codes: D04H 1/4374 using different kinds of webs, e.g. by layering webs
• CPC Class Codes: Y10T 442/2025 Coating produced by extrusion
• CPC Class Codes: Y10T 442/2139 Coating or impregnation specified as porous or permeable to a specific substance [e.g., water vapor, air, etc.]
• CPC Class Codes: Y10T 442/2148 Coating or impregnation is specified as microporous but is not a foam
• CPC Class Codes: Y10T 442/2221 Coating or impregnation is specified as water proof
• CPC Class Codes: Y10T 442/674 Nonwoven fabric with a preformed polymeric film or sheet
• CPC Class Codes: Y10T 442/675 Ester condensation polymer sheet or film [e.g., polyethylene terephthalate, etc.]
• CPC Class Codes: Y10T 442/678 Olefin polymer or copolymer sheet or film [e.g., polypropylene, polyethylene, ethylene-butylene copolymer, etc.]
• CPC Class Codes: Y10T 442/679 Natural or synthetic rubber sheet or film

Abstract

A breathable composite sheet material, a method for making such a sheet material, and an absorbent article utilizing the sheet material are provided. The composite sheet material is comprised of a thermoplastic film adhered directly to a fibrous substrate. The thermoplastic film comprises at least 50% by weight of a polymer material from the group of block copolyether esters, block copolyether amides and polyurethanes. The substrate comprises a fibrous web of at least 50% by weight of polyolefin polymer synthetic fibers. The composite sheet exhibits a peel strength of at least 0.1 N/cm, a dynamic fluid transmission of less than about 0.75 g/m² when subjected to an impact energy of about 2400 joules/m², and a moisture vapor transmission rate, according to the desiccant method, of at least 1500 g/m²/24 hr. The absorbent article comprises (a) a topsheet; (b) a backsheet; and (c) an absorbent core located between the topsheet and the backsheet; wherein the backsheet comprises the non-porous, substantially fluid impermeable, moisture vapor permeable composite sheet material described above. The composite sheet material is oriented such that the film layer of the composite sheet material faces toward the absorbent core. The absorbent article may comprise a disposable diaper.

Claims

1. A moisture vapor permeable, substantially liquid impermeable composite sheet material comprising a fibrous substrate and a moisture vapor permeable thermoplastic film layer;

said fibrous substrate comprised of synthetic fibers, said synthetic fibers being comprised of at least 50% by weight polyolefin polymer, said substrate having opposite first and second planar sides;

said moisture vapor permeable film layer comprised of at least about 50% by weight of polymer selected from the group of block copolyether esters, block copolyether amides, polyurethanes, and combinations thereof, said film layer being melt bonded directly to the first side of said substrate in the absence of an adhesive between the film layer and the substrate; and

said composite sheet exhibiting a peel strength of at least 0.1 N/cm, a dynamic fluid transmission of less than about 0.75 g/m² when subjected to an impact energy of about 2400 joules/m², and having a moisture vapor transmission rate, according to the desiccant method, of at least 1500 g/m²/24 hr.

2. The composite sheet of claim 1 wherein the film layer has an average thickness of less than about 50 microns.

3. The composite sheet of claim 1 wherein said composite sheet has a peel strength of at least about 0.15 N/cm.

4. The composite sheet of claim 3 wherein said composite sheet has a peel strength per unit thickness of the film layer of the sheet material of at least 0.003 N/cm-micron.

5. The composite sheet of claim 3 wherein the film layer of said composite sheet has a thickness of less than 30 microns, and the composite sheet has a moisture vapor transmission rate, according to the dessicant method, of at least 2500 g/m²/24 hr.

6. The composite sheet of claim 5 wherein said film layer of said composite sheet has a thickness between about 10 microns and about 25 microns, and the basis weight of said fibrous substrate is between about of 13.5 and about 40 g/m².

7. The composite sheet of claim 2 wherein the film layer has opposite first and second sides, said first side being melt bonded directly to the first side of said substrate, and wherein said first side of said film layer has a surface area per unit area that is greater than the surface area per unit area of said second side of said film layer.

8. The composite sheet of claim 1 wherein said sheet has a dynamic fluid transmission of less than about 0.5 g/m² when subjected to an impact energy of about 2400 joules/m².

9. The composite sheet of claim 8 wherein the composite sheet is substantially free of micropores, and substantially no liquid moisture passes through the sheet when tested according to the liquid moisture seepage test.

10. The composite sheet of claim 8 wherein said composite sheet prevents passage of microbes when tested according to the ISO 11607 standard for sterile packaging materials.

11. The composite sheet of claim 1 wherein said composite sheet has a machine direction tensile strength and a cross direction tensile strength of at least about 1 N/cm, and a machine direction elongation and a cross direction elongation of at least about 30%.

12. The composite sheet of claim 11 wherein said fibrous substrate consists essentially of fibers of polyolefin polymer.

13. The composite sheet of claim 1 wherein said film layer comprises a moisture vapor permeable film having multiple layers, each of such multiple layers being comprised of a different moisture vapor permeable thermoplastic polymer composition.

14. The composite sheet of claim 13 wherein one of said film layers comprises a substantially hydropbilic film layer and one of said film layers comprises a substantially hydrophobic film layer.

15. The composite sheet of claim 1, wherein said composite sheet further includes an additional layer of diverse construction and composition from said film layer and said fibrous substrate.

16. The composite sheet of claim 15, wherein said additional layer comprises a microporous film.

17. The composite sheet of claim 1 wherein said film layer is comprised at least 50% by weight of a Fraction A consisting essentially of polymer from the group of block copolyether esters, block copolyether amides, polyurethanes and combinations thereof, at least 5% by weight of a Fraction B consisting essentially of a polymer from the group of homopolymers of an alpha-olefin, copolymers or terpolymers containing an alpha-olefin and one or more other monomers, and block copolymers of a vinylarene and a conjugated diene, and at least 0.1% by weight of a Fraction C consisting essentially of a compatibilizer for Fractions A and B.

18. The composite sheet material of claim 17 wherein film Fraction C consists essentially of homopolymers, copolymers and terpolymers with backbones that are compatible with Fraction B, said backbones being grafted with a monomer having a functional group that is compatible with Fraction A.

19. The composite sheet material of claim 18 wherein film Fraction C is a polymer with a backbone identical to Fraction B, said backbone being grafled with monomer selected from the group of alpha- and beta-ethylenically unsaturated carbonic acids and anhydrides, and derivatives thereof.

20. The composite sheet material of claim 19 wherein the film layer comprises, by weight, 50% to 95% film Fraction A, 5% to 40% film Fraction B, and 0.1% to 15% film Fraction C.

21. The composite sheet material of claim 20 wherein film Fraction A is a block copolyether ester, film Fraction B is polypropylene, film Fraction C is a grafted polymer having a backbone of polypropylene that is grafted with maleic anhydride, and the substrate is a carded fibrous web comprised of at least 75% by weight polypropylene.