Process for emulsion polymerization

Claim 1

A polymerization process which comprises emulsion polymerizing at least one hardly soluble in water fluoro(vinyl ether) monomer of the formula: ##STR2## wherein X is independently a hydrogen atom, a fluorine atom or a chlorine atom, R is CF 3 or CH 2 Y (in which Y is an iodine atom, a bromine atom or a chlorine atom), m is a number of 0 to 10, n is a number of 0 to 10 and p is a number of 0 to 3 provided that the sum of m and n (m+n) is from 1 to 10, wherein the polymerization is carried out in the presence of: a polymerization initiating source, an emulsifier compound of the formula: R.sub.f -[OCFX'CF.sub.2 (CF.sub.2).sub.q ].sub.r -CFXCOOM (II) wherein R f is a C 1 -C 12 perfluoroalkyl group, X' is a fluorine atom or a trifluoromethyl group, q is 0 or 1, r is a number of 0 to 30 and M is a hydrogen atom, an ammonium group or an alkali metal, a chain transfer agent in which said chain transfer agent is an iodine compound selected from the group consisting of CF 2 I 2 , I(CF 2 ) 4 I and CF 2 ═CFCF 2 CF 2 I, and a monovalent cation in which said monovalent cation is an ammonium ion emanated from an inorganic salt, the amount of the inorganic salt is so selected that a total amount of the cations (including a cation emanated from the emulsifier when it is used) is at least 2.5×10 -1 gram ion/liter, and the molar ration of the ammonium ion to the total molar amount of all the monovalent cations in the polymerization system is from 0.4 to 1.