Patent ID: 7691957

Claim:
A butadiene-based polymer having a 1,3-butadiene monomer unit, characterized in that a cis-1,4 bond content and a vinyl bond content in the 1,3-butadiene monomer unit as measured by a Fourier transform infrared spectroscopy (FT-IR) and calculated according to the following equations (IV) and (VI) are not less than 98.0% and not more than 0.3%, respectively, and a ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) is 1.6-3.5, (cis-1,4 bond content)= e /( e+f+g )×100(%) (IV) (vinyl bond content)= g /( e+f+g )×100(%) (VI) wherein e, f and g are derived from the following matrix (III): ( 1.7455 0 - 0.0151 - 0.0454 0.4292 - 0.0129 - 0.007 0 0.3746 ) ⁢ ( log 10 ⁡ ( a / d ) log 10 ⁡ ( a / b ) log 10 ⁡ ( a / c ) ) = ( e f g ) ( III ) wherein a represents a mountain peak value near 1130 cm −1 , b represents a valley peak value near 967 cm −1 , c represents a valley peak value near 911 cm −1 and d represents a valley peak value near 736 cm −1 in the FT-IR spectrum.