Process for producing polymers or copolymers of conjugated dienes

Claim 1

A process for producing in high yield polymers having a high content of trans-1,4-linkage of a conjugated diene, copolymers of a conjugated diene and another conjugated diene, or copolymer of conjugated diene and a vinyl aromatic hydrocarbon, which comprises polymerizing the corresponding monomers in the presence of a complex initiator consisting of components (a) and (b) described below, or (a) and (b) together with one or more components selected from components (c) and (d); wherein (a) comprises a barium, strontium or calcium compound specified by the following formulae: ##STR3## wherein R is a hydrocarbon radical selected from the group consisting of aliphatic alicyclic or aromatic hydrocarbons; Y is an oxygen atom or a sulfur atom; and M is barium, strontium or calcium; (b) comprises a reaction product of an organolithium compound and at least one compound of the group consisting of the organomagnesium and organoberyllium compound each reactant specified by the following formulae, respectively: R(Li).sub.n !R(Li).sub.n wherein R is selected from the group consisting of aliphatic, alicyclic or aromatic hydrocarbon radicals; and n is an integer of from 1 to 4; and R.sub.2 M' (1) and RM'X (2) wherein R is selected from the group consisting of aliphatic, alicyclic or aromatic hydrocarbon radicals; X is a halogen atom; and M' is a magnesium atom or a beryllium atom; (c) comprises an organolithium compound, an organomagnesium compound or an organoberyllium compound specified by the following formulae, respectively: R(Li).sub.n !R(Li).sub.n wherein R is selected from the group consisting of aliphatic, alicyclic or aromatic hydrocarbon radicals and n is an integer of from 1 to 4; and R.sub.2 M' (1) and RM'X (2) wherein R is selected from the group consisting of aliphatic, alicyclic or aromatic hydrocarbon radicals; X is a halogen atom; and M' is a magnesium atom or a beryllium atom; and (d) comprises an organoaluminum compound or an organozinc compound specified by the following formulae, respectively: R.sub.3-m AlX'.sub.m or R.sub.2-l ZnX'.sub.l ( 1) wherein R is selected from the group consisting of aliphatic, alicyclic or aromatic hydrocarbon radicals; X' is a hydrogen atom or a halogen atom; m is an integer of zero, one or 2; and l is an integer of zero or one.