Deactivation of syndiotactic—1, 2—polybutadiene

Abstract

Syndiotactic 1,2-polybutadiene is a thermoplastic resin which has double bonds attached in an alternating fashion to its polymeric backbone. Films, fibers and molded articles can be made utilizing syndiotactic 1,2-polybutadiene. It can also be blended into rubbers and cocured therewith. It is generally preferred to synthesize syndiotactic 1,2-polybutadiene in an aqueous medium by suspension or emulsion polymerization utilizing a cobalt-based catalyst system. This invention is based upon the unexpected finding that certain substituted benzoic acids can be employed to deactivate such cobalt based catalyst systems. This invention more specifically discloses a process for synthesizing and deactivating syndiotactic 1,2-polybutadiene which comprises (1) polymerizing 1,3-butadiene monomer in the aqueous medium in the presence of a catalyst system which is comprised of (a) transition metal compound, (b) an organoaluminum compound and (c) at least one member selected from the group consisting of carbon disulfide, phenyl isothiocyanate and xanthic acid to produce an aqueous medium which contains the syndiotactic 1,2-polybutadiene; and (2) subsequently adding a substituted benzoic acid to the aqueous medium which contains the syndiotactic 1,2-polybutadiene to deactivate the catalyst system.