Patent ID: 7294680

Claim:
A method of producing a conjugated diene polymer which comprises polymerizing a conjugated diene compound with a catalyst consisting essentially of the following components (a) to (d) in an organic hydrocarbon solvent; and then reacting with component (j) and, optionally, component (i): Component (a): a compound containing a rare earth element of atomic number 57-71 in the Periodic Table or a compound obtained by reacting the compound with a Lewis base; Component (b): a compound containing at least one halogen atom; Component (c): an aluminoxane; Component (d): an organoaluminum compound represented by the following general formula (1): AlR 1 R 2 R 3 (1) wherein R 1 and R 2 are the same or different and are a hydrocarbon group having a carbon number of 1-10 or a hydrogen atom, and R 3 is a hydrocarbon group having a carbon number of 1-10 provided that R 3 is the same as or different from R 1 or R 2 ; Component (i): a carboxylic acid, an acid halide, an ester compound, a carboxylic ester compound or an acid anhydride represented by the following general formula (8), (9), (10), (11), (12) or (13): R 7 —(COOH) m (8) R 8 —(COX) m (9) R 9 —(COO—R 10 ) (10) R 11 —OCOO—R 12 (11) R 13 —(COOCO—R 14 ) m (12) wherein R 7 to R 15 are the same or different and are a hydrocarbon group having a carbon number of 1-50, X is a halogen atom and m is an integer of 1-5; and Component (j): a component selected from the group consisting of dioctyltin dilaurate, dioctyltin bisoctylmaleate, dioctyltin bisbenzylmaleate, dioctyltin bisethylmaleate and bisoctyltin maleate, wherein the component (j) is used as a modifying agent.