US Patent 7186785 Process for manufacturing vinyl-rich polybutadiene rubber

This invention relates to A process for manufacturing a vinyl-rich polybutadiene rubber, comprising polymerizing butadiene in a solvent using a catalyst system comprising an iron-based catalyst as catalyst and a phosphite as ligand, said catalyst system comprising: (A) an organoiron compound; (B) an organoaluminum compound; and (C) a phosphite selected from a group consisting of dialkyl phosphite, trialkyl phosphite, diaryl phosphite, triaryl phosphite and mixtures thereof; wherein, the mole ratio of component B to component A is 5:100; and that of component C to component A is 0.5:10; and 80 wt % of macromolecules of the rubber have a vinyl group.