Blended-fibre filter material

• US 4,798,850 A
• Filed: 04/27/1987
• Issued: 01/17/1989
• Est. Priority Date: 05/19/1986
• Status: Expired due to Term

• Current Assignee: BTG International Limited (Boston Scientific Corporation)
• Original Assignee: National Research Development Corporation
• Inventors: Brown, Richard C.
• Primary Examiner(s): Welsh, Maurice J.
• Assistant Examiner(s): Acquah, Samuel A.
• Application Number:
  US07/043,205
• Time in Patent Office: 631 Days
• Field of Search: 521/134, 521/138, 521/139, 521/142, 210/348, 210/500.1, 210/500.23, 210/500.35, 210/500.36, 210/500.43, 264/41, 264/45.3, 264/46.1, 428/394, 428/398
• US Class Current: 521/134
• CPC Class Codes: B01D 2239/064 The fibres being mixed
• CPC Class Codes: B01D 2239/1225 Fibre length
• CPC Class Codes: B01D 2239/1233 Fibre diameter
• CPC Class Codes: D04H 1/425 Cellulose series
• CPC Class Codes: D04H 1/4291 Olefin series
• CPC Class Codes: D04H 1/43 Acrylonitrile series
• CPC Class Codes: D04H 1/435 Polyesters
• CPC Class Codes: D04H 1/43835 Mixed fibres, e.g. at least two chemically different fibres or fibre blends
• 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: D04H 1/74 the fibres being orientated, e.g. in parallel (anisotropic fleeces)
• CPC Class Codes: Y10T 428/2967 Synthetic resin or polymer
• CPC Class Codes: Y10T 428/2975 Tubular or cellular

Abstract

A filter material is a felt of 60 weight % 2.8 decitex polypropylene fibres and 40 weight % of 3.5 decitex modacrylic fibres.

Claims

1. A filter material which comprises a blend of (i) clean polyolefine fibers and (ii) clean fibers of an addition polymer comprising one or more halogen-substituted hydrocarbons.

2. A filter material according to claim 1, wherein said halogen substituted hydrocarbon is a halogen-substituted polyolefine.

3. A filter material according to claim 2, wherein said halogen-substituted polyolefine is selected from halogen-substituted polyethylene and halogen-substituted polypropylene.

4. A filter material according to claim 2, wherein the fibers (ii) contain one or more units selected from chloroethylene units and tetrafluoroethylene units.

5. A filter material according to claim 4, wherein the fibers (ii) are selected from polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinylidene chloride copolymer, chlorinated polyvinyl chloride and polytetrafluoroethylene.

6. A filter material according to claim 5, wherein the fibers (ii) are halogen-substituted modacrylic.

7. A filter material according to claim 1, wherein the ratio of fiber (i) to fiber (ii) is from 30:

70 to 80;

20 by surface area.

8. A filter material according to claim 7, wherein the ratio of fiber (i) to fiber (ii) is from 40:

60 to 70;

30 by surface area.

9. A filter material according to claim 1, wherein the fibers are finer than 100 micrometers.

10. A filter material according to claim 9, wherein the fiber diameters are from 10 to 25 micrometers.

11. A filter material according to claim 1, wherein the fiber (i) cross-sectional area does not differ from the fiber (ii) cross-sectional area by more than a factor of 3.

12. A filter material according to claim 1, wherein the fiber staple length is from 30 to 200 mm.

13. A filter material according to claim 12, wherein the fiber staple length is from 40 to 100 mm.

14. A filter material according to claim 1, wherein the fibers (i) or (ii) or both are crimped.

15. A filter material according to claim 1, in the form of a felt.

16. A filter material according to claim 15, wherein the felt is made by carding the fibers into a fleece and needling them.