To obtain a new polybutadiene excellent as an impact resistance imparter for a polystyrene, etc., properly containing a 1,2-structure in high cis-structure, specifying the bond form of each structure.
This polybutadiene has 4-30% 1,2 structure content, 65-95% cis-1,4-structure content and ≤5% trans-1,4-structure content and has a B value shown by the formula [P1,2 is 1,2-structure content; P1,4 is 1,4-structure content; P1,2-1,4 is (1,2-structure) (1,4 structure) diad chain content in total diad chain] in a range satisfying 1.0<B≤1.43. The objective polybutadiene is preferably obtained, for example, by polymerizing a conjugated diene compound using a catalyst comprising (A) a vanadium compound of the formula VRX3 [R is a (substituted) cyclopentadienyl; X is H, a halogen, etc.] and (B) an ionic compound of a non-coordinating anion and a cation and/or an aluminoxane.
SUZUKI MICHINORI
TSUKAHARA MEGUMI
