| abstract |
The present invention relates to a method for producing butadiene-styrene block copolymers by copolymerisation of styrene and butadiene in a hydrocarbon solvent medium in the presence of an organolithium initiator and a modifier, with subsequent treatment of "living" polymer chains using a coupling agent. The method includes stages wherein, at stage (i), polymerisation of styrene is carried out in the presence of n-butyllithium and a modifier selected from tetrahydrofuran and/or di-C 1 -C 6 -alkyl ethers of ethylene glycol, so as to produce a polystyrene block of "living" polystyryllithium; and at stage (ii), butadiene is added to the reaction mixture obtained at stage (i) and synthesis of a polybutadiene block is carried out, optionally in the presence of a modifier selected from di-C 1 -C 6 -alkyl ethers of diethylene glycol, wherein said modifier is introduced after the beginning of the butadiene polymerisation, so as to produce a "living" block copolymer of polystyrene-polybutadienyllithium. Furthermore, stage (iii) of the claimed method includes treatment of the obtained block copolymer of polystyrene-polybutadienyllithium using a coupling agent, where diphenyldichlorosilane and/or silicon tetrachloride are used as said coupling agent. The technical result of the invention is the production of butadiene-styrene block copolymers with an increased content of 1,2-vinyl units and with a narrow molecular-weight distribution, with a simultaneous reduction in both the consumption of polymerisation modifiers and the time taken to carry out the process. |