Process for preparing low bulk viscosity polymers

Claim 1

A two phase polymerization process for preparing an LM polymer which comprises reacting at polymerization conditions a C 4 -C 6 conjugated diolefin with an isoolefin having the general formula: ##EQU2## wherein R 1 is H, a C 1 -C 12 acyclic hydrocarbyl radical or a C 1 -C 12 alicyclic hydrocarbyl radical and R 2 is a hydrocarbyl radical selected from the group consisting of phenyl, C 1 -C 12 acyclic radicals, C 1 -C 12 alicyclic radicals and mixtures thereof, in the presence of a catalyst selected from the group consisting of (1) aluminum bromide and (2) ethyl aluminum dichloride promoted with a compound selected from the group consisting of hydrogen chloride, C 3 -C 7 organic halides, and mixtures thereof, said catalyst being dissolved in a C 5 -C 9 alkane; said polymerization being carried out in a vehicle wherein said vehicle is (1) propane or (2) propane plus a C 5 -C 9 alkane, the reaction being carried out continuously with the steady-state concentration of monomers to be polymerized plus C 5 -C 9 alkane is about 4 to about 23 weight percent based on monomers plus propane, plus C 5 -C 9 alkane, the polymerization being carried out at a temperature of about -30 to about -80°C. and the polymerization being carried out at a conversion rate of about 60 to about 90%.