Method for preparing a porous fluoropolymer and preparing an article of same

Abstract

A method of controlling a flow of fluid comprises providing a porous article, the porous article comprising a fluoropolymer and a plurality of pores formed by removing a removable additive, a portion of the pores being connected and establishing fluid flow paths through the article; flowing a fluid through the plurality of pores of the porous article; the fluid comprising a first component having a surface energy less than 40 milliNewton per meter at 25° C. and a second component having a surface energy greater than 40 mN/m at 25° C.; wherein the fluoropolymer is selected such that the first component of the fluid has a better wettability with the fluoropolymer than the second component of the fluid.

What is claimed is: 
     
         1 . A method of controlling a flow of fluid, the method comprising:
 providing a porous article, the porous article comprising a fluoropolymer and a plurality of pores formed by removing a removable additive, a portion of the pores being connected and establishing fluid flow paths through the article;   flowing a fluid through the plurality of pores of the porous article; the fluid comprising a first component having a surface energy less than 40 milliNewton per meter at 25° C. and a second component having a surface energy greater than 40 mN/m at 25° C.;   wherein the fluoropolymer is selected such that the first component of the fluid has a better wettability with the fluoropolymer than the second component of the fluid.   
     
     
         2 . The method of  claim 1 , wherein the fluoropolymer impedes the flow of the second component of the fluid more than the first component of the fluid. 
     
     
         3 . The method of  claim 1 , wherein flowing the fluid through the pores of the porous article is conducted in a downhole environment. 
     
     
         4 . The method of  claim 1 , wherein the fluoropolymer is partially fluorinated. 
     
     
         5 . The method of  claim 1 , wherein the fluoropolymer is completely fluorinated. 
     
     
         6 . The method of  claim 1 , wherein the fluoropolymer comprises polytetrafluoroethylene, polyethylenetetrafluoroethylene, fluorinated ethylene propylene copolymer, perfluoroalkoxy polymer, polyvinylidene fluoride, polyvinylfluoride, polychlorotrifluoroethylene, polyethylenechlorotrifluoroethylene, chlorotrifluoroethylenevinylidene fluoride, perfluoroelastomer, tetrafluoroethylene-propylene elastomeric copolymer, perfluoropolyether, perfluorosulfonic acid, or a combination comprising at least one of the foregoing fluoropolymers. 
     
     
         7 . The method of  claim 1 , wherein a size of the plurality of pores is from 50 μm to 500 μm. 
     
     
         8 . The method of  claim 1 , 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. 
     
     
         9 . The method of  claim 1 , further comprising forming the porous article. 
     
     
         10 . The method of  claim 8 , wherein forming the porous article comprises:
 combining the 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 powder composition to form a compressed composition;   sintering the compressed composition to form a preform;   disposing the preform in a removing agent;   contacting the removable additive with the removing agent; and   removing, by the removing agent, the removable additive, from the preform to form the porous article.   
     
     
         11 . The method of  claim 10 , further comprising:
 disposing the powder composition in a mold prior to compressing the powder composition; and   removing the compressed composition from the mold before sintering the compressed composition.   
     
     
         12 . The method of  claim 10 , wherein combining the fluoropolymer and the removable additive distributes the removable additive in the fluoropolymer, and the compressed composition has the removable additive distributed among the fluoropolymer. 
     
     
         13 . The method of  claim 10 , wherein sintering the compressed composition is performed at a temperature from 79° C. (175° F.) to 371° C. (700° F.). 
     
     
         14 . The method of  claim 10 , wherein the removable additive is the glass pellets, strand, filament, or fiber 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. 
     
     
         15 . The method of  claim 14 , wherein the glass pellets, strand, filament, or fiber comprises a dissolvable glass. 
     
     
         16 . The method of  claim 10 , 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. 
     
     
         17 . The method of  claim 10 , wherein a size of the removable additive is from 50 μm to 500 μm. 
     
     
         18 . The method of  claim 10 , wherein the melting temperature of the removable additive is greater than the sintering temperature. 
     
     
         19 . The method of  claim 10 , further comprising flowing the removing agent through the plurality of pores. 
     
     
         20 . The method of  claim 10 , wherein removing the removable additive is performed at a temperature from 60° C. to 90° C. 
     
     
         21 . The method of  claim 10 , 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.