Tetrafluoroethylene/hexafluoropropylene copolymers with higher drawability

Abstract

A tetrafluoroethylene/hexafluoropropylene copolymer with high drawability is provided. Also provided is a process employing the polymer and an article coated with the polymer.

1. A fluoropolymer comprising from 78 to 95 weight percent tetrafluoroethylene (TFE) and 5 to 22 weight percent hexafluoropropylene (HFP) and optionally up to 3 mol % of a further fluorinated monomer copolymerizable with TFE and HFP, said fluoropolymer having
 a ratio of its weight average molecular weight (M w ) to its number average molecular weight (M n ) of less than 2, and  
 a melt flow index (MFI) of greater than or equal to 15.  
 
     
     
       2. A fluoropolymer according to  claim 1  wherein the further fluorinated monomer is a perfluoroalkyl vinyl ether. 
     
     
       3. A fluoropolymer according to  claim 1  wherein the polymer is essentially free from thermally unstable end groups. 
     
     
       4. An article comprising a conductor coated with the polymer of  claim 1 . 
     
     
       5. A fluoropolymer according to  claim 1  having less than 220  200 parts per billion (ppb) of heavy metals. 
     
     
       6. A fluoropolymer according to  claim 1  consisting of a copolymer of TFE and HFP. 
     
     
       7. A fluoropolymer according to  claim 1  having a melting point in the range of from 240° C. to 275° C. 
     
     
       8. A fluoropolymer according to  claim 1  that contains less than 80 thermally unstable endgroups per million carbon atoms. 
     
     
       9. A fluoropolymer according to  claim 1  comprising a copolymer of from 82 to 90 weight percent TFE and from 10 to 18 weight percent of HFP. 
     
     
       10. A fluoropolymer according to  claim 1  having a ratio of its weight average molecular weight ( M   w )  to its number average molecular weight  ( M   n )  of  1 . 7 .    
     
     
       11. A fluoropolymer according to  claim 1  having a ratio of its weight average molecular weight ( M   w )  to its number average molecular weight  ( M   n )  of  1 . 6 .    
     
     
       12. A fluoropolymer according to  claim 1  polymerized without chain transfer agents.  
     
     
       13. A fluoropolymer according to  claim 1  that contains less than  30  thermally unstable endgroups per million carbon atoms.  
     
     
       14. A fluoropolymer according to  claim 1  obtained by an aqueous emulsion polymerization process.  
     
     
       15. A fluoropolymer according to  claim 1  having perfluorinated endgroups, with less than  80  endgroups per million carbon atoms that are not perfluorinated.  
     
     
       16. A fluoropolymer according to  claim 15  wherein the fluoropolymer has been post fluorinated.  
     
     
       17. A fluoropolymer according to  claim 15  wherein the further fluorinated monomer is a perfluoroalkyl vinyl ether.  
     
     
       18. An article comprising a conductor coated with the polymer of  claim 15 .  
     
     
       19. A fluoropolymer according to  claim 15  consisting of a copolymer of TFE and HFP.  
     
     
       20. A fluoropolymer according to  claim 15  polymerized without chain transfer agents.  
     
     
       21. A fluoropolymer according to  claim 15  obtained by an aqueous emulsion polymerization process.  
     
     
       22. A fluoropolymer according to  claim 1  resulting from the polymerization of an alkali metal salt- free polymerization recipe.    
     
     
       23. A fluoropolymer according to  claim 16 , wherein the post fluorinating occurs when the fluoropolymer is an agglomerate.  
     
     
       24. A fluoropolymer according to  claim 15  polymerized with an initiator comprising ammonium persulfate.