Claims
- 1. A process comprising forming beads of melt-fabricable fluoropolymer resin by solvent-aided pelletization of aqueous dispersion of particles of said resin, wherein said solvent-aided pelletization is carried out using fluorinated solvent containing oxygen only as ether oxygen.
- 2. The process of claim 1, wherein said solvent is selected from the group consisting of(a) perfluorinated cyclic amine having the general formula wherein R1 is a linear or branched saturated perfluorocarbon group having 1-4 carbon atoms, R2 and R3 are linear or branched saturated perfluorocarbon groups having, independently, 1-5 carbon atoms, and the total number of carbon atoms in the molecule of formula (I) is 3-10,(b) hydrofluoroether having the formula R—O—Rf, wherein R is alkyl having 1-3 carbon atoms, and Rf is linear or branched fluoroalkyl containing no halogen other than fluorine and having 2-7 carbon atoms, and at most one terminal hydrogen atom, and (c) hydrofluoroether having the formula R4—O—R5, wherein R4 is a fluoroalkyl having 1-6 carbon atoms and at least one hydrogen atom and R5 is linear or branched fluoroalkyl containing no halogen other than fluorine, having 1-7 carbon atoms.
- 3. The process of claim 2, wherein said solvent is a hydrofluoroether.
- 4. The process of claim 3, wherein said hydrofluoroether is CH3—O—C4F9.
- 5. The process of claim 3, wherein Rf is perfluoroalkyl.
- 6. The process of claim 1, wherein said melt-fabricable fluoropolymer resin is copolymer comprising tetrafluoroethylene and at least one perfluoro(alkyl vinyl ether), said alkyl having 1-5 carbon atoms.
- 7. The process of claim 1, wherein said particles are particles produced by dispersion polymerization.
- 8. The process of claim 7, wherein said particles have a raw dispersion particle size of 50 to 350 nm.
- 9. The process of claim 7, wherein said particles have a raw dispersion particle size of 100 to 300 nm.
- 10. The process of claim 7, wherein said particles have a raw dispersion particle size of 150 to 250 nm.
- 11. The process of claim 1 wherein said beads have a D50 of 100 to 3000 μm.
- 12. The process of claim 1 wherein said beads have a D50 of 200 to 1000 μm.
- 13. The process of claim 1, wherein said beads are hardened by heat treatment below the melting point of said fluoropolymer.
- 14. The process of claim 1, wherein said beads are treated by exposure to elemental fluorine.
- 15. The process of claim 2, wherein R5 contains an ether oxygen.
- 16. The process of claim 2, wherein said solvent is solvent (a).
- 17. The process of claim 2, wherein said solvent is solvent (b).
- 18. The process of claim 1, wherein the weight ratio of said solvent to fluoropolymer resin is 0.4-1.4.
Parent Case Info
This application claims benefit of Prov. No. 60/120,512 filed Feb. 18, 1999.
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Provisional Applications (1)
|
Number |
Date |
Country |
|
60/120512 |
Feb 1999 |
US |