Patent ID: 6908975

Claim:
A method for preparing a high 1,4-cis polybutadiene having a 1,4-cis content of at least 95%, the method comprising: initiating polymerization of a 1,3-butadiene in the presence of a non-polar solvent using a polymerization catalyst prepared by mixing irrespective of the addition order (1) a neodymium compound with or without a conjugated diene compound, (2) a halogenated organoaluminum compound or a halogenated organic compound, and (3) an organoaluminum compound; and adding an organoborane compound represented by following formula 1 or 2 as a cold flow controller of 1,4-cis polybutadiene after a predetermined time of the polymerization: wherein R 1 , R 2 and R 3 are the same or different and include an alkyl group having 1 to 5 carbon atoms, respectively, wherein R is an alkoxy or alkyl group having 1 to 5 carbon atoms.