Carbon fiber and ceramic fiber paper composites and uses therefor

• US 5,989,736 A
• Filed: 05/30/1997
• Issued: 11/23/1999
• Est. Priority Date: 05/30/1997
• Status: Expired due to Term

• Current Assignee: Unifrax I LLC (ASP Unifrax Holdings, Inc.)
• Original Assignee: Unifrax Corporation (ASP Unifrax Holdings, Inc.)
• Inventors: Stahlman, Mark D., Lintz, Timothy S., Robinson, Christopher B.
• Primary Examiner(s): Jones, Deborah
• Assistant Examiner(s): Bahta, Abraham
• Application Number:
  US08/866,643
• Time in Patent Office: 907 Days
• Field of Search: 428/113, 428/212, 428/325, 428/688, 428/195, 280/728.1, 55/520, 501/95.1
• US Class Current: 428/688
• CPC Class Codes: B01D 2239/064 The fibres being mixed
• CPC Class Codes: B01D 2239/086 Binders between particles or fibres
• CPC Class Codes: B01D 2239/1233 Fibre diameter
• CPC Class Codes: B01D 2239/1258 Permeability
• CPC Class Codes: B01D 2239/1291 Other parameters
• CPC Class Codes: B01D 39/2065 the material being fibrous
• CPC Class Codes: B01D 39/2089 otherwise bonded, e.g. by resins
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder
• CPC Class Codes: C04B 14/38 Fibrous materials; Whiskers
• CPC Class Codes: C04B 14/386 Carbon carbon nanotubes C04B14/026
• CPC Class Codes: C04B 2111/00793 as filters or diaphragms
• CPC Class Codes: C04B 24/2641 Polyacrylates; Polymethacrylates
• CPC Class Codes: C04B 30/02 containing fibrous materials
• CPC Class Codes: D21H 13/40 vitreous, e.g. mineral wool, glass fibres
• CPC Class Codes: D21H 13/50 Carbon fibres
• CPC Class Codes: D21H 27/08 Filter paper self-supporting filtering material B01D39/14; making on paper-making machines D21F11/14
• CPC Class Codes: Y10T 428/24124 Fibers
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• CPC Class Codes: Y10T 428/252 Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.]

Abstract

A paper composite includes activated carbon fibers and inorganic fibers bound together by an organic latex binder. Such a ceramic paper is useful in a variety of applications and is particularly useful as a filter media in the filter unit of an inflator in an automotive airbag. The filter media is particularly suitable for use with non-azide generants within an airbag inflator.

Claims

1. A single-ply paper composite comprising activated carbon fibers, inorganic fibers and a binder for holding said carbon fibers and said inorganic fibers together, wherein said single-ply paper composite has a tensile strength of about 400 to about 1000 grams/inch and a permeability of at least 40 cubic feet/minute.

2. The paper composite of claim 1, comprising from about 5 to about 30 percent by weight activated carbon fibers, from about 50 to about 80 percent by weight inorganic fibers, and from about 2 to about 10 percent by weight latex binder.

3. The paper composite of claim 1, wherein said inorganic fibers are selected from the group consisting of aluminosilicates, mineral wool, fiberglass, zirconia, zirconia tow, conventional silica, alumina and mixtures thereof.

4. The paper composite of claim 1, wherein said carbon fibers are novoloid-based surface activated carbon fibers.

5. The paper composite of claim 1, wherein said organic latex binder is an acrylic latex.

6. The paper composite of claim 1, wherein said paper fibers have an effective surface area (BET method) of at least 2000 m² /g.

7. The paper composite of claim 1, wherein said carbon fibers chemically filter by-products of a combustion reaction of non-azide generant materials.

8. The paper composite of claim 1, wherein said inorganic fibers have a diameter ranging from about 2 to 7 μ

m and a fiber index level of at least 50%.

9. A filter media for use in an inflator unit of an airbag comprising:

a paper composite containing carbon fibers and inorganic fibers, wherein the filter media has a tensile strength of about 400 to about 1000 grams/inch and a permeability of at least 40 cubic feet/minute.

10. The filter media of claim 9, wherein said inorganic fibers are selected from the group consisting of aluminosilicates, mineral wool, fiberglass, zirconia, zirconia tow, conventional silica, alumina and mixtures thereof.

11. The filter media of claim 9, wherein said carbon fibers are novoloid-based surface activated carbon fibers.

12. The filter media of claim 9, wherein said carbon fibers have an effective surface area (BET method) of at least 2000 m² /g.

13. The filter media of claim 9, wherein said paper composite ranges from about 0.06 inches (0.152 cm) to about 0.14 inches (0.356 cm) in thickness.

14. The filter media of claim 9, wherein the inflator unit of the airbag employs non-azide generants and said carbon fibers chemically filter by-products of a combustion reaction of said non-azide generants.

15. The filter media of claim 9, wherein said inorganic fibers have a diameter of from about 2 μ

m to about 7 μ

m and a fiber index level of at least 50%.

16. A filter for use in an inflator unit of an automotive airbag comprising the filter media of claim 9, and further comprising a strengthening support wound around said filter media.

17. The filter of claim 16, wherein said strengthening support is selected from the group consisting of metal mesh, metal fleece, expanded metals and mixtures thereof.

18. A filter for use in an inflator unit of an automotive airbag comprising a paper composite including activated carbon fibers, an inorganic fibers.

19. The filter of claim 18, wherein said filter is positioned radially outwardly of an ignitor located within a pressure vessel containing a generant such that when said ignitor ignites said generant, a reaction occurs and an inflation gas expels from said pressure vessel and through said filter.

20. The filter of claim 19, wherein said generant is a non-azide generant.

21. The filter of claim 18 further comprising a strengthening support wound around said paper composite.

22. The filter of claim 21, wherein said strengthening support is selected from the group consisting of metal mesh, metal fleece, expanded metals and mixtures thereof.

23. The filter of claim 18, wherein said inorganic fibers are selected from the group consisting of aluminosilicates, mineral wool, fiberglass, zirconia, zirconia tow, conventional silica, alumina and mixtures thereof.

24. The filter of claim 18, wherein said carbon fibers are novoloid-based surface activated carbon fibers.

25. The filter of claim 18, wherein said paper composite ranges from about 0.06 inches (0.152 cm) to about 0.14 inches (0.356 cm) in thickness.

26. The filter of claim 20, wherein said carbon fibers chemically filter by-products of a combustion reaction of said non-azide generants.

27. The filter of claim 18, wherein said carbon fibers have an effective surface are (BET Method) of at least 2000 m² /g.

28. The filter of claim 18, wherein said inorganic fibers have a fiber index level of at least 50%.