Filtration materials using fiber blends that contain strategically shaped fibers and/or charge control agents

• US 9,909,767 B2
• Filed: 12/24/2014
• Issued: 03/06/2018
• Est. Priority Date: 10/25/2010
• Status: Active Grant

• Current Assignee: Swm Luxembourg SARL (Mativ Holdings, Inc.)
• Original Assignee: DelStar Electrostatic, Inc. (Mativ Holdings, Inc.)
• Inventors: Chapman, Rick L.
• Primary Examiner(s): Smith, Duane
• Assistant Examiner(s): Turner, Sonji
• Application Number:
  US14/582,267
• Publication Number:
  US 20150110957A1
• Time in Patent Office: 1,168 Days
• CPC Class Codes: B01D 2239/0435 Electret apparatus incorporating such gas filtering material B01D46/0032
• CPC Class Codes: B01D 2239/0492 on fibres
• CPC Class Codes: B01D 2239/0627 Spun-bonded
• CPC Class Codes: B01D 2239/10 Filtering material manufacturing
• CPC Class Codes: B01D 2239/1233 Fibre diameter
• CPC Class Codes: B01D 39/1623 of synthetic origin
• CPC Class Codes: B01D 46/0032 using electrostatic forces to remove particles, e.g. electret filters
• CPC Class Codes: B03C 3/28 Plant or installations without electricity supply, e.g. using electrets
• CPC Class Codes: D01D 5/06 Wet spinning methods D01D5/0046 takes precedence
• CPC Class Codes: D01D 5/253 with a non-circular cross section; Spinnerette packs therefor D01D5/38 takes precedence
• CPC Class Codes: D01F 1/00 General methods for the manufacture of artificial filaments or the like
• CPC Class Codes: D01F 1/09 for making electroconductive or anti-static filaments
• CPC Class Codes: D01F 1/10 Other agents for modifying properties
• CPC Class Codes: D01F 6/06 from polypropylene
• CPC Class Codes: D01F 6/38 comprising unsaturated nitriles as the major constituent
• CPC Class Codes: D04H 3/018 characterised by the shape
• CPC Class Codes: D06M 13/00 Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds D06M10/00, D06M14/00 take precedence; treatment with complexes of organic amines with inorganic substances D06M11/59; Such treatment combined with mechanical treatment
• CPC Class Codes: F24F 8/10 by separation, e.g. by filtering
• CPC Class Codes: F24F 8/192 by electrical means, e.g. by applying electrostatic fields or high voltages

Abstract

A filtration material comprising a blend of polypropylene and acrylic fibers of round, flat, dog bone, oval or kidney bean shape in any size from 0.08 to 3.3 Dtex. A preferred blend contains about 50 weight percent polypropylene fibers and about 50 weight percent acrylic fibers. The fibers can be blended ranging from 90:10 to 10:90 polypropylene to acrylic. The shape contains 25 weight percent round, flat, oval, dog bone and kidney bean shapes. The fiber blend contains 25 weight percent of at least one size between 0.08 and 3.3 Dtex. Electret fibers incorporated within these blends have 0.02 to 33 weight percent of a charge control agent. These fibers can be used in producing electret material by corona or triboelectric charging methods.

Claims

1. A method of making fibers used in a non-woven electret gas filter media, the method comprising:

(a) wet spinning a plurality of acrylic fibers;

(b) dry spinning or wet spinning a plurality of polypropylene fibers;

(c) adding a charge control agent during step (b) in a range of about 0.1 percent to about 50 percent by weight prior to extruding the polypropylene fibers;

(d) charging the polypropylene fibers to form charged polypropylene fibers; and

(e) blending the wet spun acrylic fibers with the charged polypropylene fibers to form the non-woven electret gas filter media.

2. The method in accordance with claim 1, further comprising adding, during the step of wet spinning, an organic wax, wherein about 2.0% wax by weight remains on the outer surfaces of at least some of the acrylic fibers.

3. The method in accordance with claim 1, wherein about 0.3 percent to about 10 percent by weight of the charge control agent remains on the outer surfaces of at least some of the polypropylene fibers.

4. The method in accordance with claim 1, wherein at least some of the charged polypropylene fibers are dog bone shaped.

5. The method in accordance with claim 1, wherein at least some of the acrylic fibers are dog bone shaped.

6. The method in accordance with claim 1, wherein the charge control agent is polyvinylidene fluoride.

7. A method of making fibers used in a non-woven electret gas filter media, the method comprising:

(a) wet spinning a plurality of acrylic fibers; and

(b) blending the wet spun acrylic fibers with charged polypropylene fibers having about 0.3 percent to about 10 percent by weight of a charge control agent on an outer surface of at least some of the polypropylene fibers to form the non-woven electret gas filter media.

8. The method in accordance with claim 7, further comprising adding, during the step of wet spinning, an organic wax, wherein about 2.0% wax by weight remains on an outer surface of at least some of the acrylic fibers.

9. The method in accordance with claim 7, wherein the charge control agent is polyvinylidene fluoride.

10. The method in accordance with claim 7, wherein at least some of the polypropylene fibers are dog bone shaped.

11. The method in accordance with claim 7, wherein at least some of the acrylic fibers are dog bone shaped.

12. A method of making fibers used in a non-woven electret gas filter media, the method comprising:

(a) wet spinning a plurality of acrylic fibers with an organic wax, wherein about 2.0% wax by weight remains on an outer surface of at least some of the acrylic fibers;

(b) dry spinning or wet spinning a plurality of polypropylene fibers;

(c) adding a charge control agent during step (b), wherein, about 2.0% of the charge control agent by weight remains on an outer surface of at least some of the polypropylene fibers;

(d) charging the polypropylene fibers to form charged polypropylene fibers; and

(e) blending the wet spun acrylic fibers with the charged polypropylene fibers to form the non-woven electret gas filter media.