Chlorinated EPDM with superior stability

Claim 1

A process for preparing a chlorinated ethylene-alpha olefin-nonconjugated diolefin terpolymer characterized by a superior stability on storage or exposure to elevated temperatures and containing from about 0.5 to about 14 weight percent chlorine substituted in the allylic position wherein the base ethylene-alpha olefin-nonconjugated diolefin terpolymer comprises: (i) about 40 to 80 mol percent ethylene, (ii) about 20 to 60 mol percent of a C 3 to C 8 alpha olefin, and (iii) about 0.5 to 10 mol percent of a C 7 to C 16 nonconjugated diolefin wherein one olefinic bond is monosubstituted and terminal and the other olefinic bond is trisubstituted, which comprises the steps of: (A) forming a solution of said base ethylene-alpha olefin-nonconjugated diolefin terpolymer in an inert organic solvent wherein there is dispersed from about 0 to 10 percent by volume per volume of inert organic solvent of water, (B) adding to said terpolymer solution molecular chlorine in a quantity sufficient to achieve the desired level of chlorination, (C) subjecting the resulting solution to a temperature of from about 0° C. to 50° C. in the absence or near absence of light, whereby said ethylene-alpha olefin-nonconjugated diolefin terpolymer becomes chlorinated, adding (D) an alkaline solution to the solution of the chlorinated ethylene-alpha olefin-nonconjugated diolefin terpolymer sufficient to neutralize said solution, and (E) recovering from the solution the chlorinated ethylene-alpha olefin-nonconjugated diolefin terpolymer.