FIELD: rubber industry.
SUBSTANCE: invention concerns synthetic polyisoprenes having elevated content of cis-1,4 units. Synthetic polyisoprenes having content of cis-1,4 units above 90% as measured by 13C NMR method and by a method of quantitative analysis using infra red emission is obtained by a process involving a catalytic system efficient in presence of isoprene, said system being a system based on at least one monomer of the conjugated diene type, one salt of one or several rare-earth metals with organic phosphorus acid, one alkylation agent of formula AlR3 or HalR2, and one halogen donor, namely alkylaluminum halide. Indicated salt of the catalytic system is in the form of suspension in at least one inert saturated hydrocarbon solvent of aliphatic or alicyclic type and molar ratio of alkylation agent to rare-earth metal salt ranges from 1 to 5. Polymerization of isoprene is effected at temperature below or equal to 5°C in inert hydrocarbon solvent or in bulk.
EFFECT: enabled sufficiently efficient polymerization of isoprene at temperatures, which are below or equal to 5°C to produce polyisoprenes with content of 1,4-cis units reliably above 99%.
15 cl, 4 tbl
