Process for preparing a diene elastomer, such as a polybutadiene

Abstract

The present invention relates to a process for preparing a diene elastomer. The invention especially applies to the production of a polybutadiene with a high level of cis-1,4 linkages that has at the same time a Mooney viscosity ML (1+4) greater than or equal to 40, a polydispersity index less than 2.1 and a reduced cold flow and of a polyisoprene. The process according to the invention comprises a reaction of a catalyst system with at least one conjugated diene monomer, this catalyst system being based on at least: one conjugated diene; one organic phosphoric acid salt of one or more rare-earth metals, said salt being in suspension and in at least one saturated and aliphatic or alicyclic, and inert hydrocarbon-based solvent; one alkylating agent composed of an alkyl aluminum for formula AlR3 or HAlR2 and a halogen donor belonging to the family of alkylaluminium halides, with the exclusion of alkylaluminium sesquihalides. This process comprises a separate bringing together of the monomer(s) to be polymerized with at least one alkylaluminium compound of formula AlR3 or HAlR2 which is identical or not to the alkylating agent of said catalyst system, said amount being chosen as a function of the characteristics of the polymerization medium and/or the polymerization conditions and/or said elastomer to be obtained.

Dependencies are inferred from the claim text.