Breathable, extensible films made with two-component single resins

• US 20040127131A1
• Filed: 12/31/2002
• Published: 07/01/2004
• Est. Priority Date: 12/31/2002
• Status: Active Grant

• Current Assignee: Watchfire Corp. (Ontario) (International Business Machines Corporation)
• Original Assignee: Watchfire Corp. (Ontario) (International Business Machines Corporation)
• Inventors: Potnis, Prasad Shrikirshna
• Granted Patent: US 7,226,880 B2
• Time in Patent Office: Days
• US Class Current: 442/394
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: C08L 2205/02 containing two or more polymers of the same C08L -group
• CPC Class Codes: C08L 23/0815 Copolymers of ethene with aliphatic 1-olefins
• CPC Class Codes: C08L 2666/06 Homopolymers or copolymers of unsaturated hydrocarbons; Derivatives thereof
• 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

A film formed from a two-component single resin including two components, not blended or co-polymerized, but inter-polymerized. The two components may have different densities and/or different melt indexes, with the resulting resin having properties of a blend of the two components but with improved durability and improved cross-directional extension properties compared to a conventional blend. The two components may be linear low density polyethylene and a metallocene-catalyzed polymer, for example. The film may also include calcium carbonate to provide breathability. The film has a more uniform cross-directional gauge profile and can be extended more uniformly. The film has cross-direction extensibility at a low force, for example, between about 25% and about 50% at a force below 500 grams per 3 inches.

Claims

1. A film formed from a two-component single resin, comprising:

a first component having a density of at least 0.9; and

a second component having a density of 0.9 or lower;

wherein the two-component single resin includes the first component and the second component in a ratio of between about 2;

1 and about 1;

2, and the film has cross-direction extensibility of between about 25% and about 50% at a force below 500 grams per 3 inches.

2. The film of claim 1, wherein the film has cross-direction extensibility of between about 25% and about 50% at a force below about 400 grams per 3 inches.

3. The film of claim 1, wherein the film has cross-direction extensibility of between about 25% and about 50% at a force below about 350 grams per 3 inches.

4. The film of claim 1, wherein the first component comprises a linear low density polyolefin.

5. The film of claim 1, wherein the second component comprises a metallocene-catalyzed polymer.

6. The film of claim 1, further comprising between about 40% and about 60% by weight calcium carbonate.

7. The film of claim 1, wherein the resin has a density of between about 0.85 and about 0.91.

8. The film of claim 1, having a water-vapor transmission rate of between about 1,000 and about 20,000 grams/m²-24 hours.

9. The film of claim 1, wherein the first component has a melt index between about 2 and about 10.

10. The film of claim 1, wherein the second component has a melt index between about 1 and about 12.

11. The film of claim 1, wherein the resin has a melt index between about 2.5 and about 12.

12. The film of claim 1, wherein the film has a uniform cross-directional gauge profile.

13. The film of claim 1, wherein the film has uniform cross-direction extensibility.

14. The film of claim 1, wherein the first component has a melting point between about 100 and about 120 degrees Celsius.

15. The film of claim 1, wherein the second component has a melting point between about 50 and about 95 degrees Celsius.

16. The film of claim 1, wherein the resin has two melting peaks, one melting peak between about 50 and about 95 degrees Celsius and one melting peak between about 100 and about 120 degrees Celsius.

17. The film of claim 1, wherein the resin can be used as both a carrier and a letdown in a concentrate letdown film-formulation approach.

18. The film of claim 1, wherein the resin can be used in a fully compounded film-formulation approach.

19. A laminate comprising at least one nonwoven layer and at least one layer of the film of claim 1.

20. A breathable film formed from a two-component single resin, comprising:

a linear low density component;

a metallocene-catalyzed component; and

between about 40% and about 60% by weight calcium carbonate;

wherein the resin includes the linear low density component and the metallocene-catalyzed component in a ratio of about 2;

1, and the film has cross-direction extensibility of between about 25% and about 50% at a force below 500 grams per 3 inches.

21. The film of claim 20, wherein the film has cross-direction extensibility of between about 25% and about 50% at a force below about 400 grams per 3 inches.

22. The film of claim 20, wherein the film has cross-direction extensibility of between about 25% and about 50% at a force below about 350 grams per 3 inches.

23. The film of claim 20, wherein the resin has a density of between about 0.85 and about 0.91.

24. The film of claim 20, having a water-vapor transmission rate of between about 1,000 and about 20,000 grams/m²-24 hours.

25. The film of claim 20, wherein the linear low density component has a melt index between about 2 and about 10.

26. The film of claim 20, wherein the metallocene-catalyzed component has a melt index between about 1 and about 12.

27. The film of claim 20, wherein the two-component single resin has a melt index between about 2.5 and about 12.

28. The film of claim 20, wherein the film has a uniform cross-directional gauge profile.

29. The film of claim 20, wherein the film has uniform cross-direction extensibility.

30. The film of claim 20, wherein the linear low density component has a melting point between about 100 and about 120 degrees Celsius.

31. The film of claim 20, wherein the metallocene-catalyzed component has a melting point between about 50 and about 95 degrees Celsius.

32. The film of claim 20, wherein the resin has two melting peaks, one melting peak between about 50 and about 95 degrees Celsius and one melting peak between about 100 and about 120 degrees Celsius.

33. The film of claim 20, wherein the resin can be used as both a carrier and a letdown in a concentrate letdown film-formulation approach.

34. The film of claim 20, wherein the resin can be used in a fully compounded film-formulation approach.

35. A laminate comprising at least one nonwoven layer and at least one layer of the film of claim 20.

36. A breathable film formed from a two-component single resin, comprising:

between about 33% and about 66% linear low density polyethylene; and

between about 33% and about 66% metallocene-catalyzed polymer;

to which between about 40% and about 60% by weight calcium carbonate is added;

wherein the film has cross-direction extensibility of between about 25% and about 50% at a force below 500 grams per 3 inch.

37. The film of claim 36, wherein the film has cross-direction extensibility of between about 25% and about 50% at a force below about 400 grams per 3 inches.

38. The film of claim 36, wherein the film has cross-direction extensibility of between about 25% and about 50% at a force below about 350 grams per 3 inches.

39. The film of claim 36, wherein the resin has a density of between about 0.85 and about 0.91.

40. The film of claim 36, having a water-vapor transmission rate of between about 1,000 and about 20,000 grams/m²-24 hours.

41. The film of claim 36, wherein the linear low density polyethylene has a melt index between about 2 and about 10.

42. The film of claim 36, wherein the metallocene-catalyzed polymer has a melt index between about 1 and about 12.

43. The film of claim 36, wherein the two-component single resin has a melt index between about 2.5 and about 12.

44. The film of claim 36, wherein the film has a uniform cross-directional gauge profile.

45. The film of claim 36, wherein the film has uniform cross-direction extensibility.

46. The film of claim 36, wherein the linear low density polyethylene has a melting point between about 100 and about 120 degrees Celsius.

47. The film of claim 36, wherein the metallocene-catalyzed polymer has a melting point between about 50 and about 95 degrees Celsius.

48. The film of claim 36, wherein the two-component single resin has two melting peaks, one melting peak between about 50 and about 95 degrees Celsius and one melting peak between about 100 and about 120 degrees Celsius.

49. The film of claim 36, wherein the resin can be used as both a carrier and a letdown in a concentrate letdown film-formulation approach.

50. The film of claim 36, wherein the resin can be used in a fully compounded film-formulation approach.

51. A laminate comprising at least one nonwoven layer and at least one layer of the film of claim 36.