Patent ID: 8431644

Claim:
A rubber composition comprising: silica and a rubber component that contains a modified butadiene rubber having a vinyl content of 35% by weight or less and having, in a main chain thereof, a constitutional unit derived from a nitrogen-containing compound represented by the formula: wherein R 1 and R 2 are each hydrogen, the formula: or the formula: provided that at least one of R 1 and R 2 is not hydrogen, R 3 represents hydrogen or a C 1-4 hydrocarbon group, X represents a saturated ring-forming part consisting of (CR 8 R 9 ) l , (CR 10 R 11 ) m —NR 12 —(CR 13 R 14 ) n , (CR 10 R 11 ) m —O—(CR 13 R 14 ) n , or (CR 10 R 11 ) m —S—(CR 13 R 14 ) n , X may be substituted with the formula: or the formula: Z represents a saturated ring-forming part consisting of (CR 8 R 9 ) l , (CR 10 R 11 ) m —NR 12 —(CR 13 R 14 ) n , (CR 10 R 11 ) m —O—(CR 13 R 14 ) n , or (CR 10 R 11 ) m —S—(CR 13 R 14 ) n , R 4 to R 7 each represent hydrogen, a C 1-30 aliphatic hydrocarbon group, a C 3-30 alicyclic hydrocarbon group, a C 5-30 aromatic hydrocarbon group, or a heterocyclic group containing 3 to 30 annular atoms, and are the same as or different from each other, R 0 , and R 8 to R 14 each represent hydrogen, a C 1-30 aliphatic hydrocarbon group, a C 3-30 alicyclic hydrocarbon group, or a C 5-30 aromatic hydrocarbon group, and are the same as or different from each other, and l represents an integer of 3 to 10, and m and n each represent an integer of 1 to 9, wherein the modified butadiene rubber consists essentially of constitutional units derived from butadiene and the constitutional units derived from the nitrogen-containing compounds, wherein an amount of the modified butadiene rubber is 5 to 45% by weight per 100% by weight of the rubber component, and wherein an amount of the silica is 10 to 150 parts by weight per 100 parts by weight of the rubber component.