Technique for reducing the molecular weight and broadening the molecular weight distribution of high cis-1,4-polybutadiene

摘要

High cis-1,4-polybutadiene can be synthesized by polymerizing 1,3- butadiene monomer with a three component nickel catalyst system containing (a) an organonickel compound, (b) an organoaluminum compound, and (c) a fluorine containing compound. However, the molecular weight of the high cis-1,4-polybutadiene prepared is typically too high to be utilized as a non-oil extended rubber. This invention is based upon the discovery that halogenated phenols act to reduce the molecular weight and to increase the molecular weight distribution of high cis-1,4- polybutadiene prepared with such nickel based catalyst systems. The use of halogenated phenols as modifiers in such polymerizations does not change the microstructure of the high cis-1,4-polybutadiene produced. Accordingly, the present invention specifically discloses a process for producing high cis-1,4-polybutadiene having a reduced molecular weight and broad molecular weight distribution which comprises polymerizing 1,3- butadiene in the presence of (a) an organonickel compound, (b) an organoaluminum compound, (c) a fluorine containing compound, and (d) a halogenated phenol.