| abstract |
Disclosed are a polybutadiene having a controlled microstructure, a narrow molecular weight distribution, minimal gel content, and a low APHA color, a modified polybutadiene, producing methods for both, and a rubber-reinforced styrene resin composition using the same. The polybutadiene of the present invention is characterized in that the ratio (Tcp/ML1+4) of a 5% toluene melting viscosity (Tcp) measured at 25° C. and the Mooney viscosity (ML1+4) at 100° C. is 2.0 or higher, the molecular weight distribution (Mw/Mn) is 2.80 or less, the gel content is 0.06 wt % or less, and the APHA color is 20 or less. |