Flexible nonwoven mat

• US 5,380,580 A
• Filed: 01/03/1994
• Issued: 01/10/1995
• Est. Priority Date: 01/07/1993
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Rogers, John J., Erickson, John L., Sanocki, Stephen M.
• Primary Examiner(s): Bell, James J.
• Application Number:
  US08/176,329
• Time in Patent Office: 372 Days
• Field of Search: 501/95, 428/224, 428/219, 428/288, 428/284, 428/297, 428/298, 428/299, 428/300, 428/902, 428/920, 428/921, 428/367, 428/408, 156/148, 28/104, 28/107, 55/523, 60/299, 429/247
• US Class Current: 428/219
• CPC Class Codes: B32B 2262/101 Glass fibres
• CPC Class Codes: B32B 2262/105 Ceramic fibres
• CPC Class Codes: B32B 2307/102 Insulating
• CPC Class Codes: B32B 2307/302 Conductive
• CPC Class Codes: B32B 5/06 characterised by a fibrous or filamentary layer mechanically connected, e.g. by needling to another layer, e.g. of fibres, of paper
• CPC Class Codes: B32B 5/26 another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: C04B 2235/3409 Boron oxide, borates, boric acids, or oxide forming salts thereof, e.g. borax
• CPC Class Codes: C04B 2235/526 characterised by the length of the fibers
• CPC Class Codes: C04B 2235/5264 characterised by the diameter of the fibers
• CPC Class Codes: C04B 35/62245 rich in aluminium oxide
• CPC Class Codes: D04H 1/4209 Inorganic fibres
• CPC Class Codes: D04H 1/4218 Glass fibres
• CPC Class Codes: D04H 1/4234 Metal fibres
• CPC Class Codes: D04H 1/4242 Carbon fibres
• CPC Class Codes: D04H 1/4374 using different kinds of webs, e.g. by layering webs
• CPC Class Codes: D04H 1/43828 sheath-core
• CPC Class Codes: D04H 1/43835 Mixed fibres, e.g. at least two chemically different fibres or fibre blends
• CPC Class Codes: D04H 1/43838 Ultrafine fibres, e.g. microfibres
• CPC Class Codes: D04H 1/46 by needling or like operations to cause entanglement of fibres D04H1/45 takes precedence; needling machines D04H18/00
• CPC Class Codes: F01N 3/2853 using mats or gaskets between catalyst body and housing
• CPC Class Codes: Y10S 428/902 : High modulus filament or fiber
• CPC Class Codes: Y10S 428/92 : Fire or heat protection feature
• CPC Class Codes: Y10T 428/2918 : including free carbon or carbide or therewith [not as steel]
• CPC Class Codes: Y10T 428/30 : Self-sustaining carbon mass or layer with impregnant or other layer
• CPC Class Codes: Y10T 442/618 : Blend of chemically different inorganic microfibers
• CPC Class Codes: Y10T 442/687 : Containing inorganic strand or fiber material
• CPC Class Codes: Y10T 442/689 : Hydroentangled nonwoven fabric

Abstract

The present invention relates to a flexible nonwoven mat comprising physically entangled shot-free ceramic oxide fibers. The flexible nonwoven mat is useful, for example, as filter material, mounting mat, thermal insulation, and sound insulation.

Claims

1. A flexible nonwoven mat comprising shot-free ceramic oxide fibers, wherein at least a portion of said shot-free ceramic oxide fibers are physically entangled, wherein said shot-free ceramic oxide fibers have a diameter greater than 5 micrometers and a length greater than about 1.5 cm, wherein said shot-free ceramic oxide fibers are selected from the group consisting of (a) aluminosilicate-based fibers comprising aluminum oxide in the range from 60 to about 85 percent by weight and silicon oxide in the range from about 40 to about 15 percent by weight silicon oxide, based on the total weight of said aluminosilicate-based fibers, said aluminosilicate-based fibers being at least 20 percent by weight crystalline;

(b) crystalline quartz fibers, and (c) mixtures of (a) and (b), and wherein the combined weight of said aluminosilicate-based fibers and said crystalline quartz fibers is at least 50 percent by weight of the total weight of said nonwoven mat.

2. The flexible nonwoven mat according to claim 1, wherein the combined weight of said aluminosilicate-based fibers and said crystalline quartz fibers is at least 60 percent by weight of the total weight of said nonwoven mat.

3. The flexible nonwoven mat according to claim 1, wherein the combined weight of said aluminosilicate-based fibers and said crystalline quartz fibers is at least about 75 percent by weight of the total weight of said nonwoven mat.

4. The flexible nonwoven mat according to claim 3, wherein said mat can be bent back upon itself without breaking more than 10 percent of said aluminosilicate-based fibers and said crystalline quartz fibers present.

5. The flexible nonwoven mat according to claim 3 having an average of at least 5 needle punches/cm².

6. The flexible nonwoven mat according to claim 3, wherein at least a portion of said shot-free ceramic oxide fibers are hydroentangled.

7. The flexible nonwoven mat according to claim 3, wherein said shot-free ceramic oxide fibers are aluminosilicate-based fibers.

8. The flexible nonwoven mat according to claim 7, wherein said aluminosilicate-based fibers are crystalline fibers which comprise about 67 to about 77 percent by weight aluminum oxide and about 33 to about 23 percent by weight silicon oxide.

9. The flexible nonwoven mat according to claim 7, wherein said shot-free ceramic oxide fibers are crystalline fibers.

10. The flexible nonwoven mat according to claim 7, wherein said aluminosilicate-based fibers are aluminoborosilicate fibers.

11. The flexible nonwoven mat according to claim 10, wherein said aluminoborosilicate fibers comprise about 55 to about 75 percent by weight aluminum oxide, less than 45 to greater than zero percent by weight silicon oxide, and less than 25 to greater than zero percent boron oxide by weight, based on the total weight of said aluminoborosilicate fibers.

12. The flexible nonwoven mat according to claim 11, wherein said aluminosilicate-based fibers are at least 50 percent by weight crystalline.

13. The flexible nonwoven mat according to claim 11, wherein said aluminoborosilicate-based fibers are at least 75 percent by weight crystalline.

14. The flexible nonwoven mat according to claim 11, wherein said aluminosilicate-based fibers are crystalline.

15. The flexible nonwoven mat according to claim 7, which is essentially free of shot.

16. The flexible nonwoven mat according to claim 7, said mat being essentially free of ceramic fiber having a diameter less than 5 micrometers.

17. The flexible nonwoven mat according to claim 7, said mat being essentially free of ceramic fiber having a diameter less than 3 micrometers.

18. The flexible nonwoven mat according to claim 7, wherein at least a portion of said aluminosilicate-based fibers are needle-punched, and wherein said flexible, nonwoven mat has a weight per unit area value in the range from about 50 to about 5000 g/m².

19. The flexible nonwoven mat according to claim 7, said mat comprising a plurality of layers of said shot-free ceramic oxide fibers.

20. The flexible nonwoven mat according to claim 7, further comprising high strength fibers selected from the group consisting of silicon carbide fibers, silicon nitride fibers, carbon fibers, glass fibers, stainless steel fibers, brass fibers, and mixtures thereof.

21. The flexible nonwoven mat according to claim 7, further comprising fugitive fibers.

22. The flexible nonwoven mat according to claim 7, needle-punched, nonwoven mat comprising fibers selected from the group consisting of silicon carbide fibers, carbon fibers, silicon nitride fibers, glass fibers, stainless steel fibers, brass fibers, fugitive fibers, and mixtures thereof.

23. The flexible nonwoven mat according to claim 7, which is at least one of filtration media, thermal insulation, acoustic insulation, mounting mat, gasket material, or catalyst support.

24. The flexible nonwoven mat according to claim 3 having an average of at least 5 needle punches/cm² and which can be bent back upon itself without breaking more than 1 percent of said aluminosilicate-based fibers and said quartz fibers present.

27. The flexible nonwoven mat according to claim 1 wherein said at least a portion of said shot-free ceramic oxide fibers are hydroentangled.

25. A method for making a flexible nonwoven mat, the method comprising the steps of:

(a) providing a flexible nonwoven mat comprising shot-free ceramic oxide fibers, wherein said shot-free ceramic oxide fibers have a diameter greater than 5 micrometers and a length greater than about 1.5 cm, wherein said shot-free ceramic oxide fibers are selected from the group consisting of (a) aluminosilicate-based fibers comprising aluminum oxide in the range from 60 to about 85 percent by weight and silicon oxide in the range from about 40 to about 15 percent by weight silicon oxide, based on the total weight of said aluminosilicate-based fibers, said aluminosilicate-based fibers being at least 20 percent by weight crystalline;

(b) crystalline quartz fibers, and (c) mixtures of (a) and (b), and wherein the combined weight of said aluminosilicate-based fibers and said crystalline quartz fibers is at least 50 percent by weight of the total weight of the nonwoven mat; and

(b) physically entangling at least a portion of said shot-free ceramic oxide fibers.

26. The method according to claim 25, wherein the combined weight of said aluminosilicate-based fibers and said crystalline quartz fibers is at least about 75 percent by weight of the total weight of said nonwoven mat.