Process for homogeneously polymerized high unsaturation C4-C10 isoolefin conjugated diene copolymers

In a solution polymerization process for preparing a substantially gel-free, high number average molecular weight, high unsaturation copolymer of a C.sub.4 -C.sub.10 isoolefin, at least one C.sub.5 -C.sub.14 acyclic conjugated diolefin and at least one C.sub.5 -C.sub.9 cyclic conjugated multiolefin wherein said copolymer contains about 5 to about 40 mole percent unsaturation and wherein the polymerization is performed by using as a catalyst a catalytic amount of either an aluminum halide dissolved in a polar solvent or a hydrocarbyl aluminum dihalide and wherein the polymerization is carried out at a temperature below -100.degree. C., the improvement which comprises using a cosolvent in the amount of about 20 to about 40 volume percent based on the monomers plus cosolvent wherein the cosolvent comprises a blend of about 15 to about 90 volume percent of at least one C.sub.5 -C.sub.8 cycloparaffin and about 85 to about 10 volume percent of at least one C.sub.4 -C.sub.8 acyclic paraffin based on the total volume of cosolvent.

In a solution polymerization process for preparing a substantially gel-free, high number average molecular weight, high unsaturation copolymer of a C.sub.4 -C.sub.10 isoolefin and cyclopentadiene wherein said copolymer contains about 5 to 40 mole percent unsaturation and wherein the polymerization is carried out in a homogeneous phase using as a catalyst a catalytic amount of either an aluminum halide dissolved in a polar solvent or a hydrocarbyl aluminum dihalide and wherein the polymerization temperature is below -100.degree. C., the improvement which comprises using about 20 to about 40 volume % of cosolvent based on the cosolvent plus monomers wherein the cosolvent comprises about 15 to about 90 volume % of at least one C.sub.5 -C.sub.8 cycloparaffin and about 85 to about 10 volume % of at least one C.sub.4 -C.sub.8 acyclic paraffin based on the total volume of cosolvent.