METHOD OF PREPARATION OF LOW MOLECULAR WEIGHT POLYMERS OF CONJUGATED DIENES Russian patent published in 1997 - IPC

FIELD: synthetic rubber, electrotechnical, paint and tyre industries. SUBSTANCE: polymerization of conjugated dienes is carried out in hydrocarbon solvent in the presence of catalyst which includes mixture of butyl ithium in amount of 0.035-0.025 mole per 1 mole of initial amount of monomer with compound of general formula: wherein R is C₁-C₄ hydrocarbon radical, n is 1 or 2, Me is sodium or potassium in amount of 0.1-1.0 mole per 1 mole of n-butyl lithium, and process is carried out at 30-40 C and monomer is first added in amount of 20-25% wt% of its total amount and the remaining monomer is then added portionwise and polymerized at 60-80 C, each subsequent portion being added at monomer conversion rate of 90 wt%, and process is carried out to final polymer content of 60-70 wt% in the solution. The hydrocarbon solvent includes toluene or mixture of hexane or gasoline with toluene at molar ratio thereof from 1:40 to 1:1, respectively. The claimed method makes it possible to obtain polymer having desired microstructure, low molecular weight and small amount of components of the catalyst system. EFFECT: more efficient preparation method. 1 tbl