Slurry technique for producing fluoropolymer composites

Abstract

A fluoropolymer composite comprising at least one fluoropolymer and particulate filler material is formed using a slurry process, in which the particulate filler material is first dispersed in a polar organic liquid, which is then combined with a suitable particulate fluoropolymer. The combination is dried to form a composite powder material. The composite powder material, with optional addition of another fluoropolymer, is processed to form a fluoropolymer composite body. The process can be carried out with either melt-processible or non-melt-processible fluoropolymers.

1 . A process for forming a composite powder material comprising:
 (a) creating a particle dispersion of particulate filler material in a polar organic liquid;   (b) mixing the particle dispersion with fluoropolymer particles to form a precursor slurry; and   (c) drying the precursor slurry by removing the polar organic liquid to form the composite powder material, wherein the particulate filler material is associated with a surface of the fluoropolymer particles.   
     
     
         2 . The process of  claim 1 , wherein the particulate filler material comprises submicron particles. 
     
     
         3 . The process of  claim 1 , wherein the polar organic liquid is one of methanol, ethanol, isopropanol, n-butanol, tert-butanol, N,N-dimethylacetamide, a ketone, an ester, or a mixture thereof. 
     
     
         4 . The process of  claim 1 , wherein the fluoropolymer particles comprise a melt processible fluoropolymer. 
     
     
         5 . The process of  claim 4 , wherein the melt processible fluoropolymer comprises at least one of PFA, FEP, PTFE micropowder, or a mixture thereof. 
     
     
         6 . The process of  claim 1 , wherein the fluoropolymer particles comprise a non-melt processible fluoropolymer. 
     
     
         7 . The process of  claim 6 , wherein the non-melt processible fluoropolymer comprises at least one of PTFE, modified PTFE, or a mixture thereof. 
     
     
         8 . (canceled) 
     
     
         9 . The process of  claim 1 , wherein the mechanical energy is provided by a source of ultrasonic energy. 
     
     
         10 . The process of  claim 9 , wherein the mechanical energy is provided by a high shear mixing operation 
     
     
         11 . (canceled) 
     
     
         12 . A composite powder material made by the process of  claim 1 . 
     
     
         13 . A process for manufacturing a fluoropolymer composite body comprising:
 (a) creating a composite powder material by a process comprising:   
       (i) creating a particle dispersion of particulate filler material in a polar organic liquid, (ii) mixing the particle dispersion with fluoropolymer particles to form a precursor slurry, and (iii) drying the precursor slurry by removing the polar organic liquid to form the composite powder material, wherein the particulate filler material is associated with a surface of the fluoropolymer particles; and
 (b) forming the composite powder material into the fluoropolymer composite body. 
 
     
     
         14 . The process of  claim 13 , wherein the particulate filler material comprises submicron particles. 
     
     
         15 . The process of  claim 13 , wherein the forming comprises compression molding and sintering the composite powder material to form the fluoropolymer composite body. 
     
     
         16 . (canceled) 
     
     
         17 . A fluoropolymer composite body made by the process of  claim 13 . 
     
     
         18 . A process for manufacturing a fluoropolymer composite body comprising:
 (a) creating a composite powder material by a process comprising:   
       (i) creating a particle dispersion of particulate filler material in a polar organic liquid, (ii) mixing the particle dispersion with particles of a first fluoropolymer to form a precursor slurry, and (iii) drying the precursor slurry by removing the polar organic liquid to form the composite powder material, wherein the particulate filler material is associated with the surface of the particles of the first fluoropolymer;
 (b) combining particles of a second fluoropolymer with the composite powder material; and 
 (c) melt processing the combined composite powder material and second fluoropolymer particles to form the fluoropolymer composite body. 
 
     
     
         19 . The process of  claim 18 , wherein the particulate filler material comprises submicron particles. 
     
     
         20 . The process of  claim 18 , wherein the first fluoropolymer comprises a melt processible fluoropolymer. 
     
     
         21 . The process of  claim 18 , wherein the first fluoropolymer comprises a non-melt processible fluoropolymer. 
     
     
         22 . The process of  claim 21 , wherein the second fluoropolymer comprises a melt-processible fluoropolymer. 
     
     
         23 . (canceled) 
     
     
         24 . A fluoropolymer composite body made by the process of  claim 18 .