| abstract |
PROBLEM TO BE SOLVED: To provide a polymerization catalyst for producing a polymer having a high content of a cis 1,4-structure in a microstructure and a narrow molecular weight distribution. A catalyst composition for polymerizing a conjugated diene, comprising: (A) a general formula (I): (C 5 R 1 R 2 R 3 R 4 R 5) a MX b ยท L c ( wherein, M represents a rare earth metal; C 5 R 1 R 2 R 3 R 4 R 5 represents a substituted cyclopentadienyl group; R 1 to R 5 each represent the same or different hydrocarbon groups (provided that R 1 = R 2 = R 3 = R 4 = R 5 = unless methyl group); X represents a hydrogen atom, a halogen atom, an alkoxide group, a thiolate group, an amide group, or a hydrocarbon group of a carbon number of 1 to 20; L is a Lewis basic compound A represents an integer of 1, 2, or 3; b represents an integer of 0, 1, or 2; c represents an integer of 0, 1, or 2), and (B A) a catalyst composition comprising an ionic compound comprising a non-coordinating anion and a cation and / or an aluminoxane. |