Microporous stretch thinned film/nonwoven laminates and limited use or disposable product applications

• US 7,932,196 B2
• Filed: 08/22/2003
• Issued: 04/26/2011
• Est. Priority Date: 08/22/2003
• Status: Active Grant

• Current Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Original Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Inventors: Shea, Courtney Eileen, Palmer, Randall James, McCormack, Ann Louise
• Primary Examiner(s): Tarazano; D. Lawrence
• Assistant Examiner(s): Matzek; Matthew D
• Application Number:
  US10/646,979
• Publication Number:
  US 20050042962A1
• Time in Patent Office: 2,804 Days
• Field of Search: 442/327, 442/394, 442/398
• US Class Current: 442/398
• CPC Class Codes: B32B 2038/0028 Stretching, elongating
• CPC Class Codes: B32B 2307/558 Impact strength, toughness
• CPC Class Codes: B32B 2323/046 LDPE, i.e. low density polyethylene
• CPC Class Codes: B32B 2555/02 Diapers or napkins
• CPC Class Codes: B32B 27/12 next to a fibrous or filamentary layer
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 37/12 characterised by using adhesives
• CPC Class Codes: B32B 37/153 at least one layer is extruded and immediately laminated while in semi-molten state
• CPC Class Codes: B32B 5/022 Non-woven fabric
• CPC Class Codes: Y10T 442/60 Nonwoven fabric [i.e., nonwoven strand or fiber material]
• CPC Class Codes: Y10T 442/674 Nonwoven fabric with a preformed polymeric film or sheet
• CPC Class Codes: Y10T 442/678 Olefin polymer or copolymer sheet or film [e.g., polypropylene, polyethylene, ethylene-butylene copolymer, etc.]

Abstract

Breathable laminates of a film and nonwoven with increased toughness and the ability to undergo strain without splitting for applications as components of personal care products and other uses. The film is formed using a carrier/letdown resin approach where the filled carrier resin is an ethylene polymer or copolymer having a density at least 0.003 g/cc higher than the letdown resin which is also an ethylene copolymer but has a density in the range of less than about 0.915 g/cc and a melt index less than about 6. The resin phases may be dry blended, formed into a film, stretched and bonded to a nonwoven support layer.

Claims

1. A breathable laminate having a moisture vapor transmission rate of at least about 300 g/m²/24 hours comprising a nonwoven support layer bonded to an oriented film comprising a letdown resin phase wherein said letdown resin comprises a first ethylene copolymer having a density between 0.900 and 0.915 g/cc and a melt index of no greater than 6 g/10 minutes and a carrier resin phase comprising a filler and a different ethylene polymer or copolymer having a density at least about 0.003 g/cc greater than the density of said letdown resin, wherein substantially all of said filler in said oriented film is contained only within discrete regions of said carrier resin phase and thereby separated from contact with said letdown phase, and wherein each of the discrete regions of the carrier resin phase is completely intermixed with and surrounded by the letdown resin phase.

2. The breathable laminate of claim 1 wherein the density of the film letdown resin is less than about 0.913 g/cc.

3. The breathable laminate of claim 2 wherein the density of the film letdown resin is in the range of from about 0.900 g/cc to about 0.912 g/cc.

4. The breathable laminate of claim 3 wherein the carrier resin ethylene polymer or copolymer has a density at least about 0.007 g/cc higher than that of said letdown resin.

5. The breathable laminate of claim 1 wherein the carrier resin ethylene polymer or copolymer has a melt index of at least about 10 g/10 min.

6. The breathable laminate of claim 1 wherein the carrier resin ethylene polymer or copolymer has a melt index of at least about 20 g/10 min.

7. The breathable laminate of claim 1 having a film basis weight in the range of from about 13 gsm to about 25 gsm.

8. The breathable laminate of claim 4 having a film basis weight in the range of from about 13 gsm to about 25 gsm.

9. The breathable laminate of claim 1 wherein the film has a calcium carbonate filler concentration based on the total film composition in the range of from about 30% to about 70% by weight.

10. The breathable laminate of claim 8 wherein the film has a calcium carbonate filler concentration based on the total film composition in the range of from about 30% to about 70% by weight.

11. The breathable laminate of claim 1 wherein both film ethylene copolymers are selected from the group consisting of linear low density polyethylene.

12. The breathable laminate of claim 10 wherein both film ethylene copolymers are selected from the group consisting of linear low density polyethylene.

13. The breathable laminate of claim 1 wherein said nonwoven comprises a spunbond nonwoven.

14. The breathable laminate of claim 12 wherein said nonwoven comprises a spunbond nonwoven.

15. The breathable laminate of claim 1 wherein said nonwoven comprises a bonded carded web.

16. The breathable laminate of claim 12 wherein said nonwoven comprises a bonded carded web.

17. The breathable laminate of claim 1 wherein said nonwoven comprises more than one layer.

18. The breathable laminate of claim 14 wherein said nonwoven comprises more than one layer.

19. The breathable laminate of claim 1 wherein said film comprises more than one layer.

20. The breathable laminate of claim 14 wherein said film comprises more than one layer.

21. The breathable laminate of claim 1 wherein said film has a break strain in the cross machine direction of greater than 300%.

22. The breathable laminate of claim 14 wherein said film has a break strain in the cross machine direction of greater than 300%.

23. The breathable laminate of claim 1 having a moisture vapor transmission rate of about 5000 g/m²/24 hours to about 10,000 g/m²/24 hours.

24. The breathable laminate of claim 1 wherein said film higher density ethylene copolymer has a density greater than 0.915 g/cc.

25. The breathable laminate of claim 14 wherein said letdown resin phase and said carrier resin phase comprise a layer constituting at least about 90% of the total film thickness.

26. A personal care product comprising the breathable film laminate of claim 1.

27. A disposable diaper comprising the breathable film laminate of claim 1 as a backing component.