Perfluoroelastomer articles having good surface properties

Abstract

Cured perfluoroelastomer articles are disclosed which have improved surface characteristics. The articles are coated with a thin durable film comprising a fluorocarbon telomer which reduces surface stickiness, while maintaining the sealing properties of the article.

1 . A cured perfluoroelastomer article for use as a vacuum seal in a high temperature environment, said article having a surface coated with a film comprising a fluorocarbon telomer having a weight average molecular weight between 1000 and 10000.  
   
   
       2 . A cured perfluoroelastomer article of  claim 1  wherein said perfluoroelastomer comprises copolymerized units of tetrafluoroethylene, a perfluorinated vinyl ether and a cure site monomer.  
   
   
       3 . A cured perfluoroelastomer article of  claim 2  wherein said perfluoroelastomer comprises copolymerized units of 53.0-79.6 mole percent tetrafluoroethylene, 20.0-46.6 mole percent perfluoro(methyl vinyl ether) and 0.4-1.5 mole percent nitrile-containing cure site monomer.  
   
   
       4 . A cured perfluoroelastomer article of  claim 1  wherein said fluorocarbon telomer is polytetrafluoroethylene.  
   
   
       5 . A cured perfluoroelastomer article of  claim 1  wherein said fluorocarbon telomer has a weight average molecular weight between 2000 and 4000.  
   
   
       6 . A cured perfluoroelastomer article of  claim 1  wherein said film has a thickness between 0.1 and 20 microns.  
   
   
       7 . A cured perfluoroelastomer article of  claim 6  wherein said film has a thickness between 3 and 10 microns.  
   
   
       8 . A process for making a cured perfluoroelastomer article for use as a vacuum seal in a high temperature environment, said process comprising: 
 A. coating a cured perfluoroelastomer article with a dispersion comprising i) a fluorocarbon telomer having a weight average molecular weight between 1000 and 10000 to for a wet-coated perfluoroelastomer article;    B. drying said wet-coated perfluoroelastomer article to form a dry-coated perfluoroelastomer article at a temperature below 200° C.; and    C. heating said dry-coated perfluoroelastomer article to a temperature and for a sufficient period of time whereby said fluorocarbon telomer melts and forms a film on said perfluoroelastomer article.    
   
   
       9 . A process for making a cured perfluoroelastomer article of  claim 8  wherein said drying step B) is at a temperature between 20° and 25° C.  
   
   
       10 . A process for making a cured perfluoroelastomer article of  claim 8  wherein said heating step C) is at a temperature between 290° and 320° C. for more than 5 minutes.  
   
   
       11 . A process for making a cured perfluoroelastomer article of  claim 8  wherein said perfluoroelastomer comprises copolymerized units of tetrafluoroethylene, a perfluorinated vinyl ether and a cure site monomer.  
   
   
       12 . A process for making a cured perfluoroelastomer article of  claim 8  wherein said fluorocarbon telomer is polytetrafluoroethylene.  
   
   
       13 . A process for making a cured perfluoroelastomer article of  claim 8  wherein said film formed in step C) has a thickness between 0.1 and 20 microns.