| abstract |
A novel semi-batch emulsion polymerization process for the production of fluoroelastomers is disclosed wherein a hydrocarbon anionic surfactant is employed as the dispersing agent. The surfactant has the formula R-L-M wherein R is an alkyl group having between 6 and 17 carbon atoms, L is selected from the group consisting of ArSO 3 − , SO 3 − , SO 4 − , PO 3 − and COO − and M is a univalent cation. Preferred surfactants are sulfonates of the formula CH 3 —(CH 2 ) n —SO 3 M, CH 3 —(CH 2 ) n —C 6 H 4 —SO 3 M, or CH 3 —(CH 2 ) n —CH═CHCH 2 —SO 3 M, where n is an integer from 6 to 17, or mixtures thereof, and M is a cation having a valence of 1. Surfactant is not introduced to the reactor until shortly after the polymerization reaction has begun. |