Process for producing high vinylidene polyisobutylene

Abstract

A liquid phase polymerization process for preparing low molecular weight, highly reactive polyisobutylene. The process includes the steps of providing a feedstock containing isobutylene and a catalyst composition made up of a complex of BF and a complexing agent. The feedstock and the catalyst composition are introduced into a residual reaction mixture in a reaction zone where the residual reaction mixture, the feedstock and the catalyst composition are intimately intermixed so as to present an intimately intermixed reaction admixture in said reaction zone. The intimately intermixed reaction admixture is maintained in its intimately intermixed condition and kept at a temperature of at least about 0° C. while the same is in the reaction zone, whereby the isobutylene therein is polymerized to form polyisobutylene having a high degree of terminal unsaturation. A product stream is withdrawn from the reaction zone. The introduction of feedstock into the reaction zone and the withdrawal of the product stream from the reaction zone are controlled such that the residence time of the isobutylene undergoing polymerization in the reaction zone is no greater than about 4 minutes whereby the product stream contains a low molecular weight, highly reactive polyisobutylene product. Preferably the reaction may be conducted on the tube side of a shell-and-tube exchanger in which a coolant is circulated on the shell side.