Patent ID: 8664344

Claim:
A process for preparing polybutadiene, the process comprising polymerizing butadiene in an aliphatic solvent, a cyclo-aliphatic solvent, or both, in the presence of a catalytic system prepared in situ, wherein the polymerizing is continuous and conducted at a temperature of from 70° C. to 130° C., the catalytic system comprises: (i) a carboxylate of neodymium soluble in the solvent, comprising a variable quantity of water, in which a H 2 O/Nd molar ratio is from 0.001/1 to 0.3/1; (ii) an alkyl compound of aluminum; and (iii) an alkyl compound of aluminum in which at least one bond of Al comprises an Al—Cl bond, a total Al/Nd molar ratio is from 4/1 to 12/1, a Cl/Nd molar ratio is from 2/1 to 6/1, and the polybutadiene has: a content of 1,4-cis units of higher than 92%; a Mooney viscosity of from 40 to 60; a M w /M n ratio of from 2 to 3; a branching index value (g m ) of from 0.5 to 0.80; and an absolute viscosity in styrene of from 100 to 450 cPs, in which the styrene is in solution at 5% at a temperature of 25° C.