Multiple layer filter media

• US 8,147,583 B2
• Filed: 06/08/2007
• Issued: 04/03/2012
• Est. Priority Date: 06/08/2007
• Status: Active Grant

• Current Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Original Assignee: Gore Enterprise Holdings Incorporated
• Inventors: Gebert, Richard, Poon, Wai Sing, Stark, Steve
• Primary Examiner(s): Greene, Jason M
• Assistant Examiner(s): Hawkins, Karla
• Application Number:
  US11/760,433
• Publication Number:
  US 20080302074A1
• Time in Patent Office: 1,761 Days
• Field of Search: 554/86, 555/21, 555/24, 554/97, 555/00, 555/02, 555/22, 55/97, 553/02, 555/14, 428/198, 428/286, 428/315.5, 428/315.7, 428/315.9, 428/340
• US Class Current: 55/486
• CPC Class Codes: B01D 2239/0668 The layers being joined by heat or melt-bonding
• CPC Class Codes: B01D 2275/10 Multiple layers
• CPC Class Codes: B01D 39/1623 of synthetic origin
• CPC Class Codes: B01D 39/1692 Other shaped material, e.g. perforated or porous sheets
• CPC Class Codes: B01D 46/521 using folded, pleated material
• CPC Class Codes: B01D 46/543 using membranes

Abstract

The invention provides a multiple layer filter media for removal of particles from a fluid stream. The multiple layer filter media may include a depth filtration layer, a membrane filtration layer and a support layer. Additional layers may be present. The membrane filtration layer may comprise expanded polytetrafluoroethylene (ePTFE). The various layers of the multiple layer filter media may be bonded together through a plurality of point bonds. The point bonding process may include simultaneously bonding multiple layers of the multiple layer filter media together in a single operation. The point bonds may be created using ultrasonic bonding.

Claims

1. Filter media comprising:

a first material comprising a first thermoplastic;

a second filter material comprising a PTFE membrane having porosity; and

a third material comprising a second thermoplastic;

wherein in a first region of said filter media, at least portions of said first material are separately disposed in a first layer, at least portions of said second filter material are separately disposed in a second layer, and at least portions of said third material are separately disposed in a third layer;

wherein said second layer is disposed between said first and third layers in said first region of said filter media;

wherein in at least one second region of said filter media different from the first region, one of a portion of said first material or a portion of said third material fills at least a portion of the porosity of said second filter material to provide a bond for restricting relative movement between at least the first layer and the second layer or between at least the third layer and the second layer in the first region.

2. The filter media of claim 1, wherein said second layer has an air permeability of at least 4 Frazier.

3. The filter media of claim 2, wherein said second layer has a water entry pressure of greater than 0.5 PSI.

4. The filter media of claim 3, wherein said second filter material comprises ePTFE, wherein said second layer comprises a first ePTFE membrane.

5. The filter media of claim 4, wherein said first material is a filter material, wherein at least portions of said first material are disposed in a meltblown polymeric web, wherein said first material comprises a material selected from a group consisting of polypropylene, polyester, nylon, and polyethylene.

6. The filter media of claim 5, wherein said third material is a support material, wherein at least portions of said third material are disposed in fibers, wherein said fibers are selected from a group consisting of spunbond fibers, hydroentangled fibers, and wet laid fibers.

7. The filter media of claim 6, wherein said third material comprises a material selected from a group consisting of polyester, nylon, polypropylene, and polyethylene.

8. The filter media of claim 6, wherein said second layer comprises ePTFE membrane.

9. The filter media of claim 5, wherein said third material provides structural support for said filter media, wherein said third material comprises cellulose fibers and a thermoplastic binder, selected from a group consisting of phenolic, acrylic, and poly-vinyl acetate.

10. The filter media of claim 5, wherein at least portions of said third material are disposed in a permeable thermoplastic web, wherein said third material comprises a material selected from a group consisting of polypropylene, polyester, nylon, polyethylene and polyurethane.

11. The filter media of claim 4, wherein at least portions of said first material are disposed in a permeable thermoplastic web, wherein said first material comprises a material selected from a group consisting of polypropylene, polyester, nylon, polyethylene and polyurethane.

12. The filter media of claim 11, wherein said third material is a support material, wherein at least portions of said third material are disposed in fibers, wherein said fibers are selected from a group consisting of spunbond fibers, hydroentangled fibers, and wet laid fibers.

13. The filter media of claim 12, wherein said third material comprises a material selected from a group consisting of polyester, nylon, polypropylene, and polyethylene.

14. The filter media of claim 11, wherein said third material provides structural support for said filter media, wherein said third material comprises cellulose fibers and a thermoplastic binder, selected from a group consisting of phenolic, acrylic, and poly-vinyl acetate.

15. The filter media of claim 3, wherein said second layer has a water entry pressure of greater than 1.5 PSI.

16. The filter media of claim 2, wherein said second layer has an air permeability of at least 10 Frazier.

17. The filter media of claim 1, wherein first, second and third layers are free from being bonded to each other in said first region of said filter media.

18. The filter media of claim 17, wherein said first material has a first melting point, wherein said second filter material has a second melting point, wherein said third material has a third melting point, and wherein said first and third melting points are lower than said second melting point.

19. The filter media of claim 18, wherein a ratio of the area of said first region to the total area of area all of said second regions is at least 9 to 1.

20. The filter media of claim 19, wherein a ratio of the area of said first region to the total area of area all of said second regions is at least 32 to 1.

21. The filter media of claim 1, wherein said second region of said filter media has a minimum thickness that is less than 50 percent of a maximum thickness of said filter media in said first region.

22. The filter media of claim 1, wherein said bond in said second region of said filter media restricts any of the layers of the filter media from being removed from the other layers without damaging any of the layers of the said media.

23. The filter media of claim 1, wherein said filter media has a specific quality of at least about 0.8 1/krayls at 0.1 μ

m DOP particle at 2.5 cm/s air velocity.

24. The filter media of claim 1, wherein said filter media has a dust loading capacity greater than about 10 g/m2.

25. The filter media of claim 1, wherein said filter media is folded to form pleats.

26. The filter media of claim 25, wherein a maximum cross dimension of one of said at least one second regions is less than twice a minimum thickness of said filter media in said first region.

27. The filter media of claim 1, further comprising a fourth layer comprising a meltblown fibrous web, wherein said third layer is disposed between said second and fourth layers.

28. The filter media of claim 27, further comprising a fifth layer comprising a spun bond thermoplastic fibrous web, wherein said fourth layer is disposed between said third and fifth layers.

29. The filter media of claim 1, further comprising a plurality of said second regions.

30. The filter media of claim 29, wherein each of said plurality of said second regions defines a point bond.

31. The filter media of claim 30, wherein said point bonds are ultrasonic bonds.

32. The filter media of claim 29, wherein said second layer has an air permeability of at least 4 Frazier.

33. The filter media of claim 32, wherein said second layer has a water entry pressure of greater than 0.5 PSI.

34. The filter media of claim 33, wherein said second material comprises ePTFE, wherein said second layer comprises a first ePTFE membrane.

35. The filter media of claim 33, wherein said second layer has a water entry pressure of greater than 1.5 PSI.

36. The filter media of claim 32, wherein said second layer has an air permeability of at least 10 Frazier.

37. The filter media of claim 29, wherein a ratio of the area of said first region to the total area of area all of said second regions is at least 9 to 1.

38. The filter media of claim 37, wherein a ratio of the area of said first region to the total area of area all of said second regions is at least 32 to1.

39. The filter media of claim 1 made by the process comprising:

a. providing a first material comprising a first thermoplastic;

b. providing a second filter material comprising a PTFE membrane having porosity;

c. providing a third material comprising a second thermoplastic

d. applying energy to a region of said filter media to heat the first, second and third layers to a temperature that is above the melting points of said first and below the melting point of the second layer, and wherein one or both of the first material and the third material flows into the open pores of the second material and the first and third material are bonded to provide a bond for restricting relative movement between at least the first layer and the second layer or between at least the third layer and the second layer in the first region.

40. The filter media of claim 1, wherein in at least one second region of said filter media at least portions of said first material and said second filter material, and at least portions of said first material said third material, are directly bonded to define a continuous bond therebetween, wherein said continuous bond restricts relative movement of said first layer, said second layer and said third layer in said first region.

41. The filter media of claim 40, wherein in each of a plurality of second regions of said filter media at least portions of said first material and said second filter material, and at least portions of said first material and said third material, are directly bonded to define a continuous bond therebetween, wherein said continuous bond of each of said plurality of second regions restricts relative movement of said first layer, said second layer and said third layer in said first region.

42. The filter media of claim 41, wherein said plurality of second regions are arranged in a pattern with said first region located thereabout.

43. The filter media of claim 41, wherein in said first region said first layer, said second layer and said third layer are free from being bonded to each other.

44. The filter media of claim 41, wherein a ratio of the area of said first region to the total area of area all of said plurality of second regions is at least 9 to 1.

45. The filter media of claim 41, wherein each of said plurality of second regions of said filter media has a minimum thickness that is less than 50 percent of a maximum thickness of said filter media in said first region.

46. The filter media of claim 1, wherein at least a portion of said first material fills at least a portion of the porosity of said second filter material to provide a bonding for restricting relative movement between at least the first layer and the second layer in the first region, and wherein a portion of said third material fills at least a portion of the porosity of said second filter material to provide bond for restricting relative movement between at least the third layer and the second layer in the first region.