To obtain a coupling type butadiene-based polymer having a high 1,4-cis content and a narrow molecular weight distribution and to provide a method for efficiently producing the polymer.
This coupling type polymer comprises (I) 0-90 pts.wt. of a butadiene-based polymer having ≥50% cis-bond unit in a butadiene unit and 1,000-10,000,000 number-average molecular weight (Mn) and (II) 100-10 pts.wt. of a polymer composed of at least two molecules of the polymers (I) bonded through a coupling agent. A method for producing the coupling type butadiene- based polymer comprises polymerizing a conjugated diene monomer in the presence of a catalyst obtained by bringing a cyclopentadienyl skeleton- containing transition metal compound of the group IV of the periodic table into contact with a cocatalyst under conditions satisfying the following two equations -100<T<80 and 0.017<t<6000 exp(-0.0921 T) ((t) is a contact time (minute); and T is a contact temperature (°C)).
ASAI MICHIHIKO
SUZUKI YASUZO
MIYAZAWA SATORU
TSUCHIHARA KENJI
MURATA MASAHIDE
OZAKI HIROYUKI
KAWABE MASANAO
FUKUI YOSHIFUMI
JIN JIJU
HAGIWARA HIDEAKI
KASE TOSHIO
JAPAN CHEMICAL INNOVATION INST
Uchida Yukio