Low stress to seal ePTFE gasket material

• US 20070040338A1
• Filed: 08/22/2005
• Published: 02/22/2007
• Est. Priority Date: 08/22/2005
• Status: Active Grant

• Current Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Original Assignee: Gore Enterprise Holdings Incorporated
• Inventors: Dove, Kevin
• Granted Patent: US 7,361,398 B2
• Time in Patent Office: Days
• US Class Current: 277/626
• CPC Class Codes: B32B 2305/026 Porous
• CPC Class Codes: B32B 2307/516 mono-axially
• CPC Class Codes: B32B 2307/518 bi-axially
• CPC Class Codes: B32B 2307/52 multi-axially
• CPC Class Codes: B32B 2307/7242 Non-permeable
• CPC Class Codes: B32B 2581/00 Seals; Sealing equipment; Gaskets
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/28 comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
• CPC Class Codes: B32B 27/322 comprising halogenated polyolefins, e.g. PTFE
• CPC Class Codes: B32B 3/02 characterised by features of form at particular places, e.g. in edge regions non-uniform thickness B32B3/263
• CPC Class Codes: B32B 7/10 at least one layer having inter-reactive properties
• CPC Class Codes: F16J 15/104 characterised by structure
• CPC Class Codes: Y10T 428/215 Seal, gasket, or packing
• CPC Class Codes: Y10T 428/24612 Composite web or sheet
• CPC Class Codes: Y10T 428/249981 Plural void-containing components
• CPC Class Codes: Y10T 428/249986 Void-containing component contains also a solid fiber or solid particle
• CPC Class Codes: Y10T 428/249988 Of about the same composition as, and adjacent to, the void-containing component
• CPC Class Codes: Y10T 428/249991 Synthetic resin or natural rubbers
• CPC Class Codes: Y10T 428/249992 Linear or thermoplastic

Abstract

A low stress-to-seal gasket material is described. Gaskets made according to the present invention comprise at least two tapes of porous PTFE and a substantially air impermeable layer at the interface of the two tape layers. The tape layers each have a non-porous region extending the tape length and separating two porous regions. The non-porous regions of at least two tape layers are not aligned in the z-axis direction.

Claims

1. A multilayer form-in-place gasket comprising

an upper and lower gasket surface, and

at least two layers of tape, each layer of tape comprising

a length of porous polytetrafluoroethylene (PTFE) tape having a top tape surface and a bottom tape surface, wherein the PTFE is densified along the x-axis forming at least one substantially non-porous region disposed between porous regions extending the length of the PTFE tape and

a substantially air impermeable layer disposed on the top tape surface of the porous PTFE tape,

wherein the substantially non-porous regions of at least two layers of tape are not aligned in the z-axis direction.

2. The gasket of claim 1 wherein at least one porous PTFE tape comprises expanded PTFE (ePTFE).

3. The gasket of claim 2, wherein at least one porous ePTFE tape comprises monoaxially expanded PTFE.

4. The gasket of claim 2, wherein at least one porous ePTFE tape comprises biaxially expanded PTFE.

5. The gasket of claim 2, wherein at least one porous ePTFE tape comprises multiaxially expanded PTFE.

6. The gasket of claim 1, wherein at least one porous tape is monolithic ePTFE.

7. The gasket of claim 1, wherein at least one porous tape comprises multiple layers of ePTFE.

8. The gasket of claim 7, wherein the layers ePTFE are selected from monoaxially, biaxially or multiaxially expanded PTFE or combinations thereof.

9. The gasket of claim 1, wherein the porous tape is porous microcellular PTFE.

10. The gasket of claim 1, wherein the at least one substantially air impermeable layer and the at least one substantially non-porous regions of the at least two tapes form a substantially air impermeable barrier extending the length of the tape that is continuous from the upper gasket surface to the lower gasket surface.

11. The gasket of claim 1, wherein the densified region extends from the top tape surface to the bottom tape surface.

12. The gasket of claim 1, wherein the densified region defines a channel along the top surface of the ePTFE tape, having channel sides and the at least one substantially air impermeable layer is further disposed on the channel sides.

13. The gasket of claim 12, wherein the densified region defines a channel on each of the top and bottom tape surfaces of the porous PTFE tape, having channel sides and the at least one substantially air impermeable layer is further disposed on the channel sides.

14. The gasket of claim 1 wherein at least two tape layers are joined by at least one substantially air impermeable layer.

15. The gasket of claim 1 wherein the at least two tape layers are joined at top tape surfaces by at least one substantially air impermeable layer.

16. The gasket of claim 14 further comprising at least one additional tape layer.

17. The gasket of claim 1, wherein at least two tape layers are joined by the substantially air impermeable layer disposed on the top tape surface of a first tape layer and a porous PTFE bottom tape surface of a second tape layer.

18. The gasket of claim 1, wherein at least one of the upper gasket surface and the bottom gasket surface is substantially porous.

19. The gasket of claim 1, wherein the upper gasket surface comprises at least one substantially air impermeable layer.

20. The gasket of claim 1, wherein the upper gasket surface and lower gasket surface comprise an air impermeable layer.

21. The gasket of claim 1, wherein at least one of the at least two layers of tape comprises at least one substantially air impermeable layer disposed on the top and bottom surfaces of the porous PTFE.

22. The gasket of claim 1, wherein all of the tape layers comprise a substantially air impermeable layer disposed on the top and bottom tape surfaces of the porous PTFE.

23. The gasket of claim 22, wherein at least two tape layers are joined at the bottom tape surfaces.

24. The gasket of claim 23, further comprising at least one additional tape layers joined to the top surface of at least one tape layer.

25. The gasket of claim 1, wherein the substantially air impermeable layer comprises tetrafluoroethylene/hexafluoropropylene copolymer (FEP).

26. The gasket of claim 1, wherein the substantially air impermeable layer comprises tetrafluoroethylen/(perfluoroalkyl) vinyl ether copolymer (PFA).

27. The gasket of claim 1, wherein the substantially air impermeable layer comprises densified ePTFE.

28. The gasket of claim 1, wherein at least one layer of tape comprises at least two substantially non-porous regions.

29. The gasket of claim 1, wherein the substantially non-porous regions in adjacent layers of the at least two layers of tape are not aligned in the z-axis direction.

30. The gasket of claim 1, wherein porous PTFE further comprises at least one filler.

31. The gasket of claim 30, wherein at least one filler comprises at least one material selected from metals, semi-metals, metal oxides, glasses, activated carbons, carbon blacks and polymeric resins.

32. The gasket of claim 30, wherein the at least one filler comprises at least one material selected from silica, barium sulfate, graphite and glass beads.

33. A multilayer form-in-place gasket comprising

at least two tapes, each tape comprising

a length of porous expanded polytetrafluoroethylene (ePTFE) having a top and a bottom tape surface,

a substantially air impermeable layer disposed on the top tape surface to form at least one substantially air impermeable surface,

at least one compression from the top tape surface, the compression extending the length of the tape and defining a substantially non-porous region of ePTFE disposed between two porous regions of ePTFE, each region extending the tape length,

wherein the at least two tapes are aligned along tape lengths and at least one substantially air impermeable surface is an interface between the at least two tapes, and

wherein the non-porous regions of the at least two tapes are not substantially aligned in the z-axis direction.

34. The gasket of claim 33, wherein the at least two tapes are joined by the substantially air impermeable layer forming the interface.

35. The gasket of claim 33, wherein the bottom tape surface of at least one tape forms a porous upper gasket surface.

36. The gasket of claim 33, wherein the bottom tape surface of at least one tape forms a porous lower gasket surface.

37. The gasket of claim 33, wherein the gasket comprises a porous upper gasket surface and a porous lower gasket surface.

38. The gasket of claim 33 wherein at least one tape further comprises a substantially air impermeable layer on the bottom tape surface.

39. The gasket of claim 33, wherein all of the tapes further comprise a substantially air impermeable layer on the bottom tape surface.

40. The gasket of claim 33, further comprising at least one additional tape layer comprising a porous ePTFE tape having a substantially air impermeable layer on the top tape surface and at least one compression defining a densified region separating two porous regions.

41. The gasket of claim 33 further comprising at least two additional tape layers comprising a porous ePTFE tape having a substantially air impermeable layer on the tape top surface and at least one compression defining a densified region separating two porous regions.

42. The gasket of claim 41, wherein at least some of the compressions of the tape layers are not aligned in the z-axis direction.

43. The gasket of claim 33, wherein at least one porous ePTFE tape comprises monoaxially expanded PTFE.

44. The gasket of claim 33, wherein at least one porous ePTFE tape comprises biaxially expanded PTFE.

45. The gasket of claim 33, wherein at least one porous ePTFE tape comprises multiaxially expanded PTFE.

46. The gasket of claim 33, wherein the porous ePTFE tapes comprise one or more of monoaxially expanded PTFE tape, biaxially expanded PTFE tape and multiaxially expanded PTFE tape.

47. The gasket of claim 33, wherein the porous ePTFE tape comprise monolithic PTFE.

48. The gasket of claim 33, wherein the porous ePTFE tape comprises a multilayer ePTFE tape.

49. The gasket of claim 33, wherein porous ePTFE further comprises at least one filler.

50. The gasket of claim 49, wherein at least one filler comprises at least one material selected from metals, semi-metals, metal oxides, glasses, activated carbons, carbon blacks and polymeric resins.

51. The gasket of claim 49, wherein the at least one filler comprises at least one material selected from silica, barium sulfate, graphite and glass beads.

52. The gasket of claim 33, wherein the substantially air impermeable layer comprises FEP.

53. The gasket of claim 33, wherein the substantially air impermeable layer comprises PFA.

54. The gasket of claim 33, wherein the substantially air impermeable layer comprises densified ePTFE.