Process for producing fluoroelastomers

Abstract

An emulsion polymerization process for the production of fluoroelastomers is disclosed wherein at least one fluorosurfactant is employed as dispersant, said fluorosurfactant being a fluoroalkylphosphoric acid ester of the formula X—Rf—(CH 2 ) n —O—P(O)(OM) 2 , wherein n=1 or 2, X=H or F, M=a univalent cation, and Rf is a C 4 -C 6 fluoroalkyl or fluoroalkoxy group. Optionally, a second dispersing agent may be employed in the polymerization, said second agent being a perfluoropolyether having at least one endgroup selected from the group consisting of carboxylic acid, a salt thereof, sulfonic acid and a salt thereof, phosphoric acid and a salt thereof.

1 . A dispersing agent having the formula CF 3 CF 2 CF 2 OCF(CF 3 )(CH 2 ) n OPO(OM) 2  wherein n is 1 or 2 and M is a univalent cation. 
     
     
         2 . A dispersing agent of  claim 1  having a formula selected from the group consisting of CF 3 CF 2 CF 2 OCF(CF 3 )CH 2 OPO(OH) 2  and CF 3 CF 2 CF 2 OCF(CF 3 )CH 2 OPO(OH)(ONH 4 ).