Patent ID: 8633281

Claim:
A method for producing a conjugated diene polymer composition, comprising steps 1, 2 and 3: step 1: polymerizing a monomer containing a conjugated diene in a hydrocarbon solvent in the presence of an alkali metal catalyst to obtain a conjugated diene polymer having at its end an alkali metal derived from the catalyst, step 2: adding a silicon compound of the formula (IV): wherein R 6 , R 7 , and R 8 represent independently a hydrocarbon group having 1 to 4 carbon atoms or a hydrocarbon oxy group having 1 to 4 carbon atoms, at least one of R 6 , R 7 , and R 8 is a hydrocarbon oxy group having 1 to 4 carbon atoms, n represents an integer of 0 to 10, and A 2 represents a group of formula (II): wherein R 3 and R 4 represent independently a hydrocarbon group having 1 to 6 carbon atoms optionally having a nitrogen atom, oxygen atom or silicon atom, and R 3 and R 4 may be connected to form a cyclic structure, to the hydrocarbon solution of the conjugated diene polymer, to modify the conjugated diene polymer with the silicon compound, and step 3: mixing the conjugated diene polymer obtained in step 2 and silica, wherein in step 2, the feed amount of the silicon compound of the formula (IV) is 0.1 to 10 mol per mol of the alkali metal of the alkali metal catalyst used in the step 1, and the feed rate of the silicon compound of the formula (IV) is not less than 6 mmol/sec/m 3 per unit volume of the hydrocarbon solution and per unit time.