METHOD FOR PREPARING A POROUS FLUOROPOLYMER AND PREPARING AN ARTICLE OF SAME

• US 20150202827A1
• Filed: 10/18/2012
• Published: 07/23/2015
• Est. Priority Date: 10/18/2012
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Sadana, Anil K.
• Granted Patent: US 9,452,372 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B01D 29/0093 Making filtering elements not provided for elsewhere
• CPC Class Codes: B01D 29/0095 Flat filtering elements B01D25/12, B01D25/26 take precedence
• CPC Class Codes: B01D 39/1661 sintered or bonded
• CPC Class Codes: B01D 39/1692 Other shaped material, e.g. perforated or porous sheets
• CPC Class Codes: B01D 67/003 by selective elimination of components, e.g. by leaching
• CPC Class Codes: B01D 71/36 Polytetrafluoroethene
• CPC Class Codes: B29B 11/12 Compression moulding
• CPC Class Codes: B29B 13/02 by heating B29B13/06, B29B13/08 take precedence
• CPC Class Codes: B29B 7/88 Adding charges , i.e. additives
• CPC Class Codes: B29C 67/202 comprising elimination of a solid or a liquid ingredient
• CPC Class Codes: B29K 2027/12 containing fluorine
• CPC Class Codes: B29K 2105/0005 containing compounding ingredients releasing, lubricating or separating agents B29C33/56, fibers B29K2105/08, B29K2105/12; fillers B29K2105/16, recycled material B29K2105/26
• CPC Class Codes: B29K 2105/04 cellular or porous
• CPC Class Codes: B29K 2105/251 Particles, powder or granules expandable particles B29K2105/046
• CPC Class Codes: C08J 2201/044 Elimination of an inorganic solid phase
• CPC Class Codes: C08J 2201/0444 Salts
• CPC Class Codes: C08J 2327/12 containing fluorine atoms
• CPC Class Codes: C08J 2327/18 Homopolymers or copolymers of tetrafluoroethylene
• CPC Class Codes: C08J 9/26 by elimination of a solid phase from a macromolecular composition or article, e.g. leaching out
• CPC Class Codes: E21B 43/02 Subsoil filtering
• CPC Class Codes: E21B 43/12 : Methods or apparatus for controlling the flow of the obtained fluid to or in wells E21B43/25 takes precedence; valve arrangements E21B34/00
• CPC Class Codes: E21B 43/38 : in the well

Abstract

A method for preparing a porous fluoropolymer precursor includes combining a fluoropolymer and a removable additive to form a composition, the removable additive having a thermal decomposition temperature greater than a sintering temperature of the fluoropolymer, compressing the composition to form a preform, and sintering the preform to form the porous fluoropolymer precursor. A method for preparing a porous fluoropolymer includes disposing the porous fluoropolymer precursor in a removing agent, contacting the removable additive with the removing agent, and removing, by the removing agent, the removable additive from the porous fluoropolymer precursor to form the porous fluoropolymer, wherein the porous fluoropolymer comprises a plurality of pores formed by removing the removable additive

Claims

1. A method for preparing a porous fluoropolymer precursor, the method comprising:

combining a fluoropolymer and a removable additive to form a composition, the removable additive having a thermal decomposition temperature greater than a sintering temperature of the fluoropolymer;

compressing the composition to form a preform; and

sintering the preform to form the porous fluoropolymer precursor.

2. The method of claim 1, further comprising:

disposing the composition in a mold prior to compressing the composition; and

removing the preform from the mold before sintering the preform.

3. The method of claim 1, wherein combining the fluoropolymer and the removable additive distributes the removable additive in the fluoropolymer, and the porous fluoropolymer precursor has the removable additive distributed among the fluoropolymer.

4. The method of claim 1, wherein sintering the preform is performed at a temperature from 79°

C. (175°

F.) to 371°

C. (700°

F.).

5. The method of claim 1, wherein the fluoropolymer is partially fluorinated.

6. The method of claim 1, wherein the fluoropolymer is completely fluorinated.

7. The method of claim 1, wherein the fluoropolymer comprises polytetrafluoroethylene, polyethylenetetrafluoroethylene, fluorinated ethylene propylene copolymer, perfluoroalkoxy polymer, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, polyethylenechlorotrifluoroethylene, chlorotrifluoroethylenevinylidene fluoride, perfluoroelastomer, tetrafluoroethylene-propylene elastomeric copolymer, perfluoropolyether, perfluorosulfonic acid, or a combination comprising at least one of the foregoing fluoropolymers.

8. The method of claim 1, wherein the removable additive comprises an inorganic salt, glass, or a combination comprising at least one of the foregoing removable additives.

9. The method of claim 8, wherein the removable additive is the inorganic salt which comprises an alkali metal halide, alkaline earth metal halide, ammonium halide, alkali metal nitrates, alkali metal nitrates, alkali metal carbonate, alkali metal hydrogencarbonate, alkaline earth metal carbonate, ammonium carbonate, ammonium hydrogen carbonate, alkali metal phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, or a combination comprising at least one of the foregoing inorganic salts.

10. The method of claim 8, wherein the removable additive is the glass which comprises silicon dioxide, aluminum oxide, barium oxide, bismuth trioxide, boron oxide, calcium oxide, cesium oxide, lead oxide, strontium oxide, a rare earth oxide, lanthanum oxide, neodymium oxide, samarium oxide, cerium oxide, or a combination comprising at least one of the foregoing glasses.

11. The method of claim 1, wherein the removable additive is present in the porous fluoropolymer precursor in an amount from 1 wt. % to 80 wt. %, based on the weight of the porous fluoropolymer precursor.

12. The method of claim 8, wherein a size of the removable additive is from 50 μ

m to 500 μ

m.

13. The method of claim 1, wherein the melting temperature of the removable additive is greater than the sintering temperature.

14. A method for preparing a porous fluoropolymer, the method comprising:

disposing the porous fluoropolymer precursor of claim 1 in a removing agent;

contacting the removable additive with the removing agent; and

removing, by the removing agent, the removable additive from the porous fluoropolymer precursor to form the porous fluoropolymer,

wherein the porous fluoropolymer comprises a plurality of pores formed by removing the removable additive.

15. The method of claim 14, further comprising flowing the removing agent through the plurality of pores.

16. The method of claim 14, wherein removing the removable additive is performed at a temperature from 60°

C. to 90°

C.

17. The method of claim 14, wherein the removing agent comprises water, hydrogen fluoride, ammonium fluoride, alkali metal fluoride, antimony fluoride, ammonium bifluoride, alkali metal bifluoride, calcium bifluoride, alkylated ammonium tetrafluoroborate, potassium tetrafluoroborate, fluoroboric acid, tin bifluoride, tetrabutylammonium tetrafluoroborate, aluminum hexafluoride, or a combination comprising at least one of the foregoing removing agents.

18. The method of claim 14, wherein a size of the plurality of pores is from 50 μ

m to 500 μ

m.

19. The method of claim 14, wherein the porous fluoropolymer is an article which is configured such that a fluid having a surface energy less than 40 milliNewton per meter (mN/m) at 25°

C. has a higher flow rate through the pores of the porous fluoropolymer than a fluid having a surface energy greater than 40 mN/m at 25°

C.

20. The method of claim 19, wherein the article comprises a flow control device, filter, membrane, tubular, sand screen, motor cover, mesh, cover, sheet, or a combination comprising at least one of the foregoing.