Elastomeric copolymides containing fluorine and process for preparing same

Claim 1

Elastomeric vulcanizable copolymers of (A) a mixture of two or more comonomers derived from tetracarboxylic acids and (B) a mixture of α, α, ω, ω-tetrahydropolyoxaperfluoroalkane-α, ω-diamine comonomers, the molar ratio of (A) to (B) being comprised between 0.98 and 1.02, in which the polydispersity index of (B) defined by the Mw/Mn ratio, wherein Mw is the weight average molecular weight and Mn is the number average molecular weight of the mixture, is comprised between 1 and 1.3, the macromolecular perfluoropolyether and copolyimide chain of said elastomeric copolymers being made of repeating units: ##STR3## wherein C 2 F 4 represents a group obtained by opening of the double bond of a tetrafluoroethylene molecule; --C 2 F 4 O-- and --CF 2 O-- are oxyperfluoroalkylene units randomly distributed along the chain, the m/n ratio of which is comprised between 0.2 and 5; n and m are whole numbers from 4 to 100, the sum n+m is a whole number from 20 to 200, radicals R are organic tetravalent groups representing at least two different structures randomly distributed along the chain and selected from the group consisting of aliphatic hydrocarbon radicals containing from 2 to 18 carbon atoms; halogen substituted aliphatic radicals containing from 2 to 18 carbon atoms; alkyl-substituted aliphatic radicals containing from 2 to 18 carbon atoms; alicyclic mono- or non-aromatic polycyclic radicals containing from 4 to 12 arbon atoms; mono- or polycyclic radicals substituted by halogen, alkyl, phenyl, alkylene or vinylene groups; aromatic, alkyl-aromatic and condensed-rings aromatic radicals; aromatic radicals consisting of two or more benzene rings linked together directly or through O, S, NH, CO, SO, SO 2 , an alkylene, alkylidene or vinylene bridge; such radicals in which the benzene rings are halogen-substituted and such radicals in which the benzene rings are phenyl-substituted; and heterocyclic radicals the ring of which is made up of 5 or 6 atoms, provided that at least one of said radicals R is selected from the group consisting of aliphatic radicals, cycloaliphatic radicals, aliphatic- substituted aromatic radicals and cycloaliphatic-substituted aromatic radicals.