Patent ID: 7056990

Claim:
A liquid phase polymerization process for preparing a mid-range vinylidene content PIB polymer composition comprising PIB molecules, wherein a first portion of said PIB molecules have alpha position double bonds and a second portion of said PIB molecules have beta position double bonds, wherein said first and second portions together include at least 90% of the PIB molecules of the composition, and wherein no more than about 10% of the PIB molecules of the composition have tetra-substituted internal double bonds, said process comprising: providing a liquid feedstock comprising isobutylene; providing a catalyst composition comprising a stable complex of BF 3 and a catalyst complexing agent, wherein the ratio of complexing agent to BF 3 in said complex is no more than about 1.3:1; introducing said feedstock and said catalyst composition into a residual reaction mixture in a loop reactor reaction zone; recirculating the residual reaction mixture in said zone at a recirculation rate sufficient to cause intimate intermixing of the residual reaction mixture, the feedstock and the catalyst composition to thereby present a recirculating, intimately intermixed reaction admixture in said reaction zone; maintaining the recirculating intimately intermixed reaction admixture in its intimately intermixed condition and removing heat of reaction from the reaction admixture at a rate calculated to provide a substantially constant reaction temperature in the reaction admixture while the same is recirculating in said reaction zone; withdrawing a product stream comprising said mid-range vinylidene content PIB polymer composition; and controlling the introduction of said feedstock into said reaction zone and the withdrawal of said product stream from the reaction zone such that the residence time of the isobutylene components undergoing polymerization in the reaction zone is no more than about 4 minutes.