Patent ID: 7030195
Filing Date: 2006-04-18
Classification: C08C,C08F

Abstract:
1. A process for the preparation of polybutadiene with a low branching degree having the following characteristics: branching index value (gM) lower than 1; damping coefficient value (tans), defined as the trigonometric tangent of the ratio between the viscous modulus (G″) and the elastic modulus (G′) [tan δ=G″/G′] measured at 0.01 Hz, 100° C. and 1% of strain, ranging from 0.80 to 1.40; Mooney viscosity lower than 49; M percentage of 1,4-cis units higher than 93%; the above process being effected by the polymerization of 1,3-butadiene in the presence of neodymium catalysts, the above process comprising: (a) a first polymerization step of butadiene in the presence of organic solvents and in the presence of a catalytic system comprising (a1) a derivative of neodymium selected from neodymium carboxylates with a molar ratio H (b) treatment of the polymeric solution obtained at the end of step (a) with a peroxide until polybutadiene with a low branching degree is obtained; (c) recovery of the polybutadiene with a low branching degree obtained at the end of step (b).