ELECTROSPINNING OF PTFE WITH HIGH VISCOSITY MATERIALS

• US 20100193999A1
• Filed: 01/19/2010
• Published: 08/05/2010
• Est. Priority Date: 01/16/2009
• Status: Active Grant

• Current Assignee: Zeus Co. LLC
• Original Assignee: Zeus Industrial Products, Inc.
• Inventors: Ballard, Robert, Anneaux, Bruce L., Garner, David P.
• Granted Patent: US 8,178,030 B2
• Time in Patent Office: Days
• US Class Current: 264/438
• CPC Class Codes: B05D 1/007 using an electrostatic field B05D1/02 - B05D1/16 take precedence
• CPC Class Codes: B29B 11/06 by moulding the material
• CPC Class Codes: B29B 13/023 Half-products, e.g. films, plates
• CPC Class Codes: B29C 55/04 uniaxial, e.g. oblique
• CPC Class Codes: B29K 2027/18 PTFE, i.e. polytetrafluorethene , e.g. ePTFE, i.e. expanded polytetrafluorethene
• CPC Class Codes: B29K 2105/0094 having particular viscosity
• CPC Class Codes: B29K 2995/0063 Density
• CPC Class Codes: B29K 2995/0077 Yield strength; Tensile strength
• CPC Class Codes: B29L 2031/755 Membranes, diaphragms
• CPC Class Codes: B32B 1/08 Tubular products
• CPC Class Codes: B32B 15/085 comprising polyolefins
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 5/022 Non-woven fabric
• CPC Class Codes: B32B 9/005 comprising one layer of ceramic material, e.g. porcelain, ceramic tile layered products with at least two ceramic layers composed mainly of ceramic B32B18/00
• CPC Class Codes: C08F 114/26 Tetrafluoroethene
• CPC Class Codes: C08J 2327/18 Homopolymers or copolymers of tetrafluoroethylene
• CPC Class Codes: C08J 2471/02 Polyalkylene oxides
• CPC Class Codes: C08J 3/005 Processes for mixing polymers
• CPC Class Codes: C08J 3/05 from solid polymers
• CPC Class Codes: C08J 9/232 by sintering expandable particles
• CPC Class Codes: D01D 10/02 : Heat treatment heating for finishing D02J13/00
• 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 5/0038 : the fibre formed by solvent evaporation, i.e. dry electro-spinning
• CPC Class Codes: D01F 6/12 : from polymers of fluorinated hydrocarbons
• CPC Class Codes: D01F 6/48 : of polymers of halogenated hydrocarbons
• CPC Class Codes: D04H 1/413 : containing granules other than absorbent substances
• CPC Class Codes: D04H 1/42 : characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
• CPC Class Codes: D04H 1/4318 : Fluorine series
• CPC Class Codes: D04H 1/4326 : Condensation or reaction polymers
• CPC Class Codes: D04H 1/54 : by welding together the fibres, e.g. by partially melting or dissolving in combination with needling D04H1/485
• CPC Class Codes: D04H 1/728 : by electro-spinning electro-spinning methods and apparatus D01D5/0007
• CPC Class Codes: D04H 1/74 : the fibres being orientated, e.g. in parallel (anisotropic fleeces)
• 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: D06N 7/00 : Flexible sheet materials not otherwise provided for, e.g. textile threads, filaments, yarns or tow, glued on macromolecular material paper-based or board-based structures for surface covering D21H27/20
• CPC Class Codes: D10B 2321/042 : polymers of fluorinated hydrocarbons, e.g. polytetrafluoroethene [PTFE]
• CPC Class Codes: Y10T 428/1314 : Contains fabric, fiber particle, or filament made of glass, ceramic, or sintered, fused, fired, or calcined metal oxide, or metal carbide or other inorganic compound [e.g., fiber glass, mineral fiber, sand, etc.]
• CPC Class Codes: Y10T 428/1355 : Elemental metal containing [e.g., substrate, foil, film, coating, etc.]
• 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 442/60 : Nonwoven fabric [i.e., nonwoven strand or fiber material]
• CPC Class Codes: Y10T 442/656 : Preformed metallic film or foil or sheet [film or foil or sheet had structural integrity prior to association with the nonwoven fabric]
• CPC Class Codes: Y10T 442/674 : Nonwoven fabric with a preformed polymeric film or sheet
• CPC Class Codes: Y10T 442/681 : Spun-bonded nonwoven fabric

Abstract

An improved process for forming a PTFE mat is described. The process includes providing a dispersion with PTFE, a fiberizing polymer and a solvent wherein said dispersion has a viscosity of at least 50,000 cP. An apparatus is provided which comprises a charge source and a target a distance from the charge source. A voltage source is provided which creates a first charge at the charge source and an opposing charge at the target. The dispersion is electrostatically charged by contact with the charge source. The electrostatically charged dispersion is collected on the target to form a mat precursor which is heated to remove the solvent and the fiberizing polymer thereby forming the PTFE mat.

Claims

1. A process for forming a PTFE mat comprising:

providing a dispersion comprising;

PTFE;

a fiberizing polymer; and

a solvent wherein said dispersion has a viscosity of at least 50,000 cP;

providing an apparatus comprising a charge source and a target a distance from said charge source;

providing a voltage source to create a first charge at said charge source and an opposing charge at said target wherein said dispersion is electrostatically charged by contact with said charge source;

collecting said electrostatically charged dispersion on said target to form a mat precursor; and

heating said mat precursor to remove said solvent and said fiberizing polymer thereby forming said PTFE mat.

2. The process for forming a PTFE mat of claim 1 wherein said dispersion comprises 50-80 wt % PTFE solids.

3. The process for forming a PTFE mat of claim 2 wherein said dispersion comprises 59-61 wt % PTFE solids.

4. The process for forming a PTFE mat of claim 1 further comprising sintering.

5. The process for forming a PTFE mat of claim 4 wherein said sintering is at a temperature of at least 500°

F. to no more than 900°

F.

6. The process for forming a PTFE mat of claim 1 wherein said dispersion has a viscosity of at least 100,000 cP to no more than 300,000 cP.

7. The process for forming a PTFE mat of claim 1 comprising providing a voltage of 2,000 to 80,000 volts across said orifice and said target.

8. The process for forming a PTFE mat of claim 1 wherein said dispersion comprises at least 1 wt % to no more than 10 wt % of said fiberizing polymer.

9. The process for forming a PTFE mat of claim 1 wherein said dispersion comprises a weight ratio of fiberizing polymer to PTFE of at least 3.0 to no more than 5.5.

10. The process for forming a PTFE mat of claim 1 wherein said fiberizing polymer has a solubility in said solvent of greater than 0.5 wt %.

11. The process for forming a PTFE mat of claim 1 wherein said solvent is water.

12. The process for forming a PTFE mat of claim 1 wherein said fiberizing polymer has an ash content of less than 5 wt % upon sintering at 400°

C.

13. The process for forming a PTFE mat of claim 1 wherein said fiberizing polymer is selected from the group consisting of dextran, alginates, chitosan, guar gum compounds, starch, polyvinylpyridine compounds, cellulosic compounds, cellulose ether, hydrolyzed polyacrylamides, polyacrylates, polycarboxylates, polyvinyl alcohol, polyethylene oxide, polyethylene glycol, polyethylene imine, polyvinylpyrrolidone, polyacrylic acid, poly(methacrylic acid), poly(itaconic acid), poly(2-hydroxyethyl acrylate), poly(2-(dimethylamino)ethyl methacrylate-co-acrylamide), poly(N-isopropylacrylamide), poly(2-acrylamido-2-methyl-1-propanesulfonic acid), poly(methoxyethylene), poly(vinyl alcohol), poly(vinyl alcohol) 12% acetyl, poly(2,4-dimethyl-6-triazinylethylene), poly(3-morpholinylethylene), poly(N-1,2,4-triazolyethylene), poly(vinyl sulfoxide), poly(vinyl amine), poly(N-vinyl pyrrolidone-co-vinyl acetate), poly(g-glutamic acid), poly(N-propanoyliminoethylene), poly(4-amino-sulfo-aniline), poly[N-(p-sulphophenyl)amino-3-hydroxymethyl-1,4-phenyleneimino-1,4-phenylene)], isopropyl cellulose, hydroxyethyl, hydroxylpropyl cellulose, cellulose acetate, cellulose nitrate, alginic ammonium salts, i-carrageenan, N-[(3′

-hydroxy-2′

,3′

-dicarboxy)ethyl]chitosan, konjac glocomannan, pullulan, xanthan gum, poly(allyammonium chloride), poly(allyammonium phosphate), poly(diallydimethylammonium chloride), poly(benzyltrimethylammonium chloride), poly(dimethyldodecyl(2-acrylamidoethyly) ammonium bromide), poly(4-N-butylpyridiniumethylene iodine), poly(2-N-methylpridiniummethylene iodine), poly(N methylpryidinium-2,5-diylethenylene), polyethylene glycol polymers and copolymers, cellulose ethyl ether, cellulose ethyl hydroxyethyl ether, cellulose methyl hydroxyethyl ether, poly(1-glycerol methacrylate), poly(2-ethyl-2-oxazoline), poly(2-hydroxyethyl methacrylate/methacrylic acid) 90;

10, poly(2-hydroxypropyl methacrylate), poly(2-methacryloxyethyltrimethylammonium bromide), poly(2-vinyl-1-methylpyridinium bromide), poly(2-vinylpyridine N-oxide), poly(2-vinylpyridine), poly(3-chloro-2-hydroxypropyl-2-methacryloxyethyldimethylammonium chloride), poly(4-vinylpyridine N-oxide), poly(4-vinylpyridine), poly(acrylamide/2-methacryloxyethyltrimethylammonium bromide) 80;

20, poly(acrylamide/acrylic acid), poly(allylamine hydrochloride), poly(butadiene/maleic acid), poly(diallyldimethylammonium chloride), poly(ethyl acrylate/acrylic acid), poly(ethylene glycol) bis(2-aminoethyl), poly(ethylene glycol) monomethyl ether, poly(ethylene glycol)-bisphenol A diglycidyl ether adduct, poly(ethylene oxide-b-propylene oxide), poly(ethylene/acrylic acid) 92;

8, poly(1-lysine hydrobromide), poly(1-lysine hydrobromide), poly(maleic acid), poly(n-butyl acrylate/2-methacryloxyethyltrimethylammonium bromide), poly(N-iso-propylacrylamide), poly(N-vinylpyrrolidone/2-dimethylaminoethyl methacrylate), dimethyl sulfatequaternary, poly(N-vinylpyrrolidone/vinyl acetate), poly(oxyethylene) sorbitan monolaurate (Tween 20®

), poly(styrenesulfonic acid), poly(vinyl alcohol), N-methyl-4(4′

-formylstyryl)pyridinium, methosulfate acetal, poly(vinyl methyl ether), poly(vinylamine) hydrochloride, poly(vinylphosphonic acid), poly(vinylsulfonic acid) sodium salt and polyaniline

14. The process for forming a PTFE mat of claim 13 wherein said fiberizing polymer is polyethylene oxide.

15. The process for forming a PTFE mat of claim 14 wherein said polyethylene oxide has a molecular weight of at least 50,000 to no more than 4,000,000.

16. The process for forming a PTFE mat of claim 1 wherein said target is an expanded structure.

17. The process for forming a PTFE mat of claim 1 further comprising expanding or contracting said target.

18. The process for forming a PTFE mat of claim 1 further comprising expanding or contracting said target prior to said collecting.

19. A process for forming a PTFE mat comprising:

providing a dispersion comprising;

PTFE with a particle size of at least 0.1 microns to no more than 0.8 microns;

1 wt % to no more than 10 wt % of polyethylene oxide with a molecular weight of at least 50,000 to no more than 4,000,000; and

a solvent wherein said dispersion has a viscosity of at least 50,000 cP;

providing an apparatus comprising an orifice and a target a distance from said orifice;

providing a voltage source to create a first charge at said orifice and an opposing charge at said target;

forcing said dispersion through said orifice wherein said dispersion is electrostatically charged by contact with said orifice;

collecting said electrostatically charged dispersion on said target to form a mat precursor; and

heating said mat precursor to remove said solvent and said fiberizing polymer thereby forming said PTFE mat.