Provided is an all-season tire tread rubber composition in which braking performance and wear performance are secured at the same time. A rubber composition for tire tread according to the present disclosure comprises: 100 parts by weight of raw rubber comprising solution polymerized styrene-butadiene rubber which has a styrene content of 20 to 30 wt % and a vinyl content within butadiene of 20 to 30 wt %, and is manufactured by a continuous method; 90 to 110 parts by weight of silica; and 20 to 40 parts by weight of modified liquid butadiene rubber.

A modified conjugated diene-based polymer and a rubber composition including the same are disclosed herein. In some embodiments, the modified conjugated diene-based polymer includes a functional group derived from a modification monomer represented by Formula 1 and a functional group derived from a modifier, and the polymer has a unimodal molecular weight distribution, and a polydispersity index of 1.0 to less than 1.7. The polymer has excellent processability, tensile properties and viscoelasticity properties.

A modified conjugated diene-based polymer and a rubber composition including the same are disclosed herein. In some embodiments, the modified conjugated diene-based polymer includes a functional group derived from a modification monomer represented by Formula 1 and a functional group derived from a modifier, and the polymer has a unimodal molecular weight distribution, and a polydispersity index of 1.0 to less than 1.7. The polymer has excellent processability, tensile properties and viscoelasticity properties.

The present invention relates to a modified conjugated diene-based polymer and a rubber composition including the same, and provides a modified conjugated diene-based polymer satisfying the following: a) a molecular weight distribution curve by gel permeation chromatography (GPC) has a unimodal shape; b) molecular weight distribution (PDI: MWD) is 1.00 or more and less than 1.70; c) cold flow is 1.00 or less; and d) the Si content is 100 ppm or more based on a total weight of the modified conjugated diene-based polymer.

The present disclosure relates to a modified conjugated diene-based polymer and a rubber composition including the same, and provides a modified conjugated diene-based polymer including: a derived unit from a modification initiator; a repeating unit derived from a conjugated diene-based monomer; and a derived unit from a modifier, and satisfying the conditions of i) a weight average molecular weight: 1,000,000 g/mol or more, ii) a glass transition temperature: −40° C. or less, iii) the N content: 70 ppm or more based on a total weight of the polymer, iv) the Si content: 70 ppm or more based on a total weight of the polymer, and v) a coupling number: greater than 2.5 and less than 5.0.

The present disclosure relates to a modified conjugated diene-based polymer and a rubber composition including the same, and provides a modified conjugated diene-based polymer including a first polymer chain and a second polymer chain, including a repeating unit derived from a conjugated diene-based monomer and a derived unit from a nitrogen-containing modification initiator, in each, wherein the first polymer chain includes a derived unit from an aminoalkoxysilane-based modifier in at least one terminal, the second polymer chain includes a derived unit from an aminoepoxy-based modifier in at least one terminal, and the aminoalkoxysilane-based modifier includes 6 or more alkoxy groups in a molecule.

A process for preparing a functionalized polybutadiene is provided. The process comprises the following steps: a) homopolymerising butadiene with a catalytic system based on at least one preforming conjugated diene, a salt of one or more rare earth metals of an organic phosphoric acid, an aluminium-containing alkylating agent, an alkylaluminium halide; b) adding a polyfunctional compound to the pseudo-living elastomer formed in step (a); and c) adding a functionalizing agent to the mixture formed in step (b). The total molar amount of aluminium in the polymerization medium is such that the (aluminium/rare earth salt) molar ratio has a value between 1 and 5 and the polymerization is carried out at a temperature between 40° C. and 90° C. A functionalized polybutadiene that can be obtained by the process, and a rubber composition containing the functionalized polybutadiene is also provided.

A process for preparing a functionalized polybutadiene is provided. The process comprises the following steps: a) homopolymerising butadiene with a catalytic system based on at least one preforming conjugated diene, a salt of one or more rare earth metals of an organic phosphoric acid, an aluminium-containing alkylating agent, an alkylaluminium halide; b) adding a polyfunctional compound to the pseudo-living elastomer formed in step (a); and c) adding a functionalizing agent to the mixture formed in step (b). The total molar amount of aluminium in the polymerization medium is such that the (aluminium/rare earth salt) molar ratio has a value between 1 and 5 and the polymerization is carried out at a temperature between 40° C. and 90° C. A functionalized polybutadiene that can be obtained by the process, and a rubber composition containing the functionalized polybutadiene is also provided.

To provide a narrow and large-diameter tire capable of improving noise performance at high speeds without compromising handling performance at low temperatures.

The tire has a tread portion formed of an elastomer composition. A relationship between a tire outer diameter (Dt) and a tire cross-sectional width (Wt) satisfy a following expression (1). The tread portion includes at least one circumferential groove extending in a tire circumferential direction. A rubber thickness at a groove bottom of the circumferential groove is 0.05 to 0.25 times a maximum thickness of the tread portion. The elastomer composition has a phase difference δ of 5.0×10.sup.−2π [rad] or less between a maximum value of strain and a maximum value of stress when repeatedly deformed at a temperature of 30 degrees Celsius and a frequency of 10 Hz in a dynamic viscoelasticity test;

1963.4≤(Dt.sup.2×π/4)/Wt≤2827.4  (1).

To provide a narrow and large-diameter tire capable of improving noise performance at high speeds without compromising handling performance at low temperatures.

The tire has a tread portion formed of an elastomer composition. A relationship between a tire outer diameter (Dt) and a tire cross-sectional width (Wt) satisfy a following expression (1). The tread portion includes at least one circumferential groove extending in a tire circumferential direction. A rubber thickness at a groove bottom of the circumferential groove is 0.05 to 0.25 times a maximum thickness of the tread portion. The elastomer composition has a phase difference δ of 5.0×10.sup.−2π [rad] or less between a maximum value of strain and a maximum value of stress when repeatedly deformed at a temperature of 30 degrees Celsius and a frequency of 10 Hz in a dynamic viscoelasticity test;

1963.4≤(Dt.sup.2×π/4)/Wt≤2827.4  (1).