Composite filter media

• US 7,501,003 B2
• Filed: 03/02/2004
• Issued: 03/10/2009
• Est. Priority Date: 03/02/2004
• Status: Active Grant

• Current Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Original Assignee: Gore Enterprise Holdings Incorporated
• Inventors: Poon, Wai Sing, Muller, Jason William
• Primary Examiner(s): Smith; Duane S
• Assistant Examiner(s): PHAM, MINH CHAU THI
• Application Number:
  US10/791,659
• Publication Number:
  US 20050193696A1
• Time in Patent Office: 1,834 Days
• Field of Search: 554/86, 554/97, 555/00, 555/02, 555/22, 554/98, 555/24, 555/28, 553/82, 554/85, 553/854, 555/21, 55D/IG.42, 55D/IG.39, 96/66
• US Class Current: 55/486
• CPC Class Codes: B01D 2275/10 Multiple layers
• CPC Class Codes: B01D 46/0032 using electrostatic forces to remove particles, e.g. electret filters
• CPC Class Codes: B01D 46/10 Particle separators, e.g. dust precipitators, using filter plates, sheets or pads having plane surfaces
• CPC Class Codes: B01D 46/521 using folded, pleated material
• CPC Class Codes: B01D 46/543 using membranes
• CPC Class Codes: Y10S 55/39 Electrets separator

Abstract

The invention provides a renewable composite filter media for removal of particles from a fluid stream. The filter media includes a membrane filtration layer comprising a porous polymeric membrane having an upstream side and a downstream side relative to the direction of fluid flow, a first depth filtration media layer having an upstream side and a downstream side relative to the direction of fluid flow, the first depth filtration media layer being disposed on upstream side of the membrane filtration layer; and at least one additional depth filtration media layer removably attached to the upstream side of the first depth filtration media layer. In this aspect, the first depth filtration media layer may be removably attached to the membrane filtration layer.

Claims

1. A composite filter media for removal of particles from a fluid stream comprising:

a) a membrane filtration layer comprising porous hydrophobic ePTFE, the membrane filtration layer having an upstream side and a downstream side relative to the direction of fluid flow and an air permeability at least about 5 Frazier; and

b) at least one meltblown filtration media layer comprising fibers, said fibers being less than 5 μ

m and having an electrostatic charge, the at least one meltblown filtration media layer disposed directly on the upstream side of the membrane filtration layer; and

c) support layer disposed on the downstream side of the membrane filter layer, wherein the composite filter media has a dust capacity of at least 10 mg.

2. The composite filter media of claim 1, in which the support layer is laminated to the membrane filtration layer.

3. The composite filter media of claim 1, in which the membrane filtration layer further comprises filler material selected from the group consisting of carbon, carbon black, activated carbon, TiO₂, platinum, colloidal silica, and fumed silica.

4. A renewable composite filter media for removal of particles from a fluid stream comprising:

a) a membrane filtration layer comprising a porous hydrophobic ePTFE, the membrane filtration layer having an upstream side and a downstream side relative to the direction of fluid flow and an air permeability of at least about 5 Frazier;

b) a first meltblown filtration media layer having an upstream side and a downstream side relative to the direction of fluid flow, the first meltblown filtration media layer having an electrostatic charge, the meltblown filtration media layer being disposed directly on the upstream side of the membrane filtration layer; and

c) further comprising a support layer disposed on the downstream side of the membrane filtration layer

d) at least one additional meltblown media layer having an electrostatic charge and removably attached to the upstream side of the first depth filtration media layer;

wherein the renewable composite filter media has a dust holding capacity of at least 40 mg.

5. The renewable composite filter media of claim 4, in which the first meltblown filtration media layer is removably attached to the membrane filtration layer.

6. The renewable composite filter of claim 4, in which the support layer is laminated to the membrane filtration layer.

7. The renewable composite filter media of claim 4, in which the membrane filtration layer further comprises filler material selected from the group consisting of carbon, carbon black, activated carbon, TiO₂, platinum, colloidal silica, and fumed silica.

8. The renewable composite filter media of claim 4, further comprising at least two additional meltblown filtration media layers removably attached to the upstream side of the first meltblown filtration media layer.

9. The renewable composite filter media of claim 4, in which the membrane filtration layer has a permeability of at least about 7 Frazier.

10. The renewable composite filter media of claim 4, in which the membrane filtration layer has a permeability of at least about 15 Frazier.

11. The renewable composite filter media of claim 4, in which the membrane filtration layer has a permeability of at least about 80 Frazier.

12. The renewable composite filter media of claim 4, in which each of the meltblown filtration media layers has a permeability of at least about 30 Frazier.

13. The renewable composite filter media of claim 4, in which each of the meltblown filtration media layers has a permeability of at least about 100 Frazier.

14. The renewable composite filter media of claim 4, in which each of the meltblown filtration media layers has a permeability of at least about 200 Frazier.

15. The renewable composite filter media of claim 4, in which the membrane filtration layer having an air permeability of about 10 Frazier to about 40 Frazier and a particle filtration efficiency of at least about 50% for 0.3 micron sized particles, and wherein the at least one additional meltblown media layer has an air permeability of about 30 to about 200 Frazier and having a particle filtration efficiency of at least 50% for 0.3 micron sized particles.

16. The renewable composite filter media of claim 15, in which the membrane filtration layer has a particle filtration efficiency of at least 75% for 0.3 micron sized particles and wherein the at least one additional meltblown media layer has an air permeability of about 60 to about 150 Frazier and a particle filtration efficiency of at least 85% for 0.3 micron sized particles.

17. The renewable composite filter media of claim 4 in which the membrane filtration layer and the meltblown filtration media layers are pleated such that the apices of the membrane filtration layer and meltblown filtration media layers are aligned.

18. The renewable filter media of claim 4 in which the filter media is shaped as a pleated panel.

19. The renewable composite filter media of claim 4 in which two edges of the filter media are joined to form a cylindrical filter media.

20. The renewable composite filter media of claim 4 in which the filter media is formed as a pleated cylinder.

21. A renewable composite filter media for removal of particles from a fluid stream comprising;

a) a membrane filtration layer comprising a porous hydrophobic ePTFE, the membrane filtration layer having an upstream side and a downstream side relative to the direction of fluid flow;

b) a support layer having an upstream side and a downstream side relative to the direction of fluid flow, the support layer disposed on the upstream side of the membrane filtration layer;

c) a first meltblown filtration media layer having an upstream side and a downstream side relative to the direction of fluid flow, the first meltblown filtration media layer having an electrostatic charge and disposed on the upstream side of the support layer; and

c) at least one additional meltblown filtration media layer removably attached to the upstream side of the first meltblown filtration media layer.

22. The renewable composite filter media of claim 21, in which the first meltblown filtration media layer is removably attached to the support layer.

23. The renewable composite filter media of claim 21, in which the membrane filtration layer having an air permeability of about 10 Frazier to about 40 Frazier and a particle filtration efficiency of at least about 50% for 0.3 micron sized particles, and wherein the at least one additional meltblown media layer has an air permeability of about 30 to about 200 Frazier and a particle filtration efficiency of at least 50% for 0.3 micron sized particles.

24. The renewable composite filter media of claim 23, in which the membrane filtration layer has a particle filtration efficiency of at least 75% for 0.3 micron sized particles and wherein the at least one additional meltblown media layer has an air permeability of about 60 to about 150 Frazier and a particle filtration efficiency of at least 85% for 0.3 micron sized particles.

25. The renewable composite filter media of claim 21, in which the membrane filtration layer and the meltblown filtration media layers are pleated such that the apices of the membrane filtration layer and meltblown filtration media layers are aligned.

26. The renewable filter media of claim 21, in which the filter media is formed as a pleated panel.

27. The renewable composite filter media of claim 21, in which two edges of the filter media are joined to form a cylindrical filter media.

28. The renewable composite filter media of claim 21, in which the filter media is formed as a pleated cylinder.