Process if making fine fiber material

• US 6,955,775 B2
• Filed: 09/30/2003
• Issued: 10/18/2005
• Est. Priority Date: 09/05/2000
• Status: Expired due to Term

• Current Assignee: Donaldson Company Incorporated
• Original Assignee: Donaldson Company Incorporated
• Inventors: Chung, Hoo Y., Gogins, Mark A., Weik, Thomas M., Crofoot, Douglas G., Hall, John R. B.
• Primary Examiner(s): Tentoni, Leo B.
• Application Number:
  US10/676,239
• Publication Number:
  US 20040060269A1
• Time in Patent Office: 749 Days
• Field of Search: 264/10, 264/13, 264/115, 264/211.17, 264/460, 264/465, 977/DIG.1
• US Class Current: 264/10
• CPC Class Codes: B01D 2239/025 comprising nanofibres apparatus incorporating such gas filtering material see B01D46/546
• CPC Class Codes: B01D 2239/0428 Rendering the filter material hydrophobic
• CPC Class Codes: B01D 2239/0492 on fibres
• CPC Class Codes: B01D 2239/0613 Woven
• CPC Class Codes: B01D 2239/0618 Non-woven
• CPC Class Codes: B01D 2239/0627 Spun-bonded
• CPC Class Codes: B01D 2239/064 The fibres being mixed
• CPC Class Codes: B01D 2239/065 More than one layer present in the filtering material apparatus incorporating such gas filtering material B01D2275/10
• CPC Class Codes: B01D 2239/0654 Support layers
• CPC Class Codes: B01D 2239/1233 Fibre diameter
• CPC Class Codes: B01D 2239/1258 Permeability
• CPC Class Codes: B01D 2275/10 Multiple layers
• CPC Class Codes: B01D 39/04 Organic material, e.g. cellulose, cotton
• CPC Class Codes: B01D 39/086 of inorganic material
• CPC Class Codes: B01D 39/1623 of synthetic origin
• CPC Class Codes: B01D 39/163 sintered or bonded
• CPC Class Codes: B01D 39/18 the material being cellulose or derivatives thereof cork or peat B01D39/1646 ; making filter paper D21F11/14
• CPC Class Codes: B01D 46/0001 Making filtering elements
• CPC Class Codes: B01D 46/02 Particle separators, e.g. dust precipitators, having hollow filters made of flexible material
• 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 46/2411 : Filter cartridges
• CPC Class Codes: B01D 46/521 : using folded, pleated material
• CPC Class Codes: B01D 46/523 : with means for maintaining spacing between the pleats or folds
• CPC Class Codes: B01D 46/546 : using nano- or microfibres
• CPC Class Codes: C08L 65/00 : Compositions of macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain C08L7/00 - C08L57/00, C08L61/00 take precedence; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 77/00 : Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain of polyhydrazides C08L79/06; of polyamideimides or polyamide acids C08L79/08; Compositions of derivatives of such polymers
• CPC Class Codes: D01D 5/0007 : Electro-spinning non-woven fabrics produced by electro-spinning D04H1/728
• CPC Class Codes: D01D 5/003 : the material being a polymer solution or dispersion D01D5/0053 takes precedence
• CPC Class Codes: D01D 5/0084 : Coating by electro-spinning, i.e. the electro-spun fibres are not removed from the collecting device but remain integral with it, e.g. coating of prostheses
• CPC Class Codes: D01F 1/10 : Other agents for modifying properties
• CPC Class Codes: D01F 6/80 : from copolyamides
• CPC Class Codes: D01F 6/90 : of polyamides
• CPC Class Codes: D01F 6/92 : of polyesters
• CPC Class Codes: D04H 3/02 : characterised by the method of forming fleeces or layers, e.g. reorientation of yarns or filaments
• CPC Class Codes: Y10S 428/903 : Microfiber, less than 100 micron diameter
• CPC Class Codes: Y10T 428/1362 : Textile, fabric, cloth, or pile containing [e.g., web, net, woven, knitted, mesh, nonwoven, matted, etc.]
• CPC Class Codes: Y10T 428/24686 : Pleats or otherwise parallel adjacent folds
• CPC Class Codes: Y10T 428/24942 : including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/26 : Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/29 : Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
• CPC Class Codes: Y10T 428/2915 : including textile, cloth or fabric
• CPC Class Codes: Y10T 428/2933 : Coated or with bond, impregnation or core
• CPC Class Codes: Y10T 428/2938 : Coating on discrete and individual rods, strands or filaments
• CPC Class Codes: Y10T 428/2967 : Synthetic resin or polymer
• CPC Class Codes: Y10T 428/2969 : Polyamide, polyimide or polyester
• CPC Class Codes: Y10T 428/298 : Physical dimension
• CPC Class Codes: Y10T 442/16 : Two or more nonwoven layers
• CPC Class Codes: Y10T 442/614 : Strand or fiber material specified as having microdimensions [i.e., microfiber]
• CPC Class Codes: Y10T 442/626 : Microfiber is synthetic polymer
• CPC Class Codes: Y10T 442/659 : Including an additional nonwoven fabric

Abstract

Improved polymer materials and fine fiber materials can be made from the improved polymeric materials in the form of microfiber and nanofiber structures. The microfiber and nanofiber structures can be used in a variety of useful applications including the formation of filter materials.

Claims

1. A method of making a fine fiber material comprising a fiber having a diameter of about 0.01 to 0.5 micron and a surface coating having a thickness of less than about 100 Å

, the method comprises forming a solution comprising a lower alcohol, water or mixtures thereof and about 3 to about 30 wt % of a polymer composition, other than a copolymer formed from a cyclic lactam and a C_6-10 diamine monomer or a C_6-10 diacid monomer, and about 2 to 25 wt % of an additive, based on the polymer composition, the additive comprising a resinous material having a molecular weight of about 500 to about 3000 and an aromatic character wherein the additive is miscible in the polymer, exposing the polymer solution to an electric field of a potential greater than about 10×

10³ volts causing the solution to form accelerated strands of solution which upon evaporation of the solvent forms a fine fiber, collecting the fine fiber on a substrate and exposing the fine fiber and substrate to a heat treatment, the heat treatment raising the temperature of the fine fiber to a temperature less than the melting point of the polymer.

2. The method of claim 1 wherein the solvent comprises a combined aqueous alcoholic solvent.

3. The method of claim 1 wherein the solvent comprises a mixture of a major proportion of water and about 10 to 90 wt % of an alcohol selected from the group consisting of methanol, ethanol, isopropanol, n-propanol, butanol and mixtures thereof.

4. The method of claim 1 wherein the polymer comprises an addition polymer.

5. The method of claim 1 wherein the polymer comprises a polyvinyl halide polymer.

6. The method of claim 1 wherein the polymer comprises a polyvinylidene halide.

7. The method of claim 1 wherein the polymer comprises a polyvinylalcohol.

8. The method of claim 1 wherein the polymer comprises a nylon homopolymer.

9. The method of claim 1 wherein the polymer comprises a blend of a nylon homopolymer and a nylon copolymer comprising repeating units derived from cyclic lactam, a C_6-10 diamine monomer and a C_6-10 diacid monomer.

10. A method of making fine fiber material comprising a fiber having a diameter about 0.01 to 2 microns, the fiber comprising a linear fiber forming polymer and catalyst, the method comprises forming a solution comprising lower alcohol, water or mixtures thereof and about 3 to 30 weight percent of polymer composition, exposing the polymer solution to an electric field of potential greater than a threshold potential volts causing solution to form accelerated strands of solution that dry to a fine fiber, collecting the fine fiber on a substrate and exposing the fine fiber to a heat treatment, the heat treatment raising the temperature of the fine fiber to a temperature less than the melting temperature of fiber forming polymer.

11. The method of claim 10 wherein the threshold potential is about 10×

10³ volts.

12. The method of claim 10 wherein the polymer is a crosslinkable polymer.

13. The method of claim 10 wherein an acidic catalyst is used.

14. The method of claim 10 wherein the polymer comprises mixed fiber forming and non-fiber forming polymers.

15. The method of claim 10 wherein the fine fiber is found between two substrates.

16. The method of claim 10 wherein the line fiber layer can be exposed to an alcoholic solvent at 70°

F. and wherein at least 50% of the fiber remains after 5 minutes.