Provided is a rubber composition that realizes excellent low heat generating properties while maintaining good steering stability when applied to a tire. The rubber composition of the present disclosure contains a rubber component containing a copolymer having a conjugated diene unit and an aromatic vinyl unit, and a filler, where the copolymer is a modified copolymer having a content of the aromatic vinyl unit of less than 10 mass % and modified with a modifier containing a compound represented by the formula (1).

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The present disclosure provides a tire having excellent enduring performance. The present disclosure relates to a tire including a tread containing a rubber composition, the rubber composition satisfying the following relationships 1) to 3) when measured within 180 days after vulcanization: 1) Hso/Hsa×100≥95 wherein Hso: hardness at room temperature, Hsa: hardness at room temperature after heat treatment at 80° C. for 168 hours; 2) As/Ts×100≤70 wherein Ts: sulfur content before acetone extraction, As: sulfur content after acetone extraction; and 3) Swell≤330 wherein Swell: toluene swelling index.

A method for producing a modified conjugated diene-based polymer includes polymerizing a monomer including a conjugated diene compound in the presence of an alkali metal compound or an alkali earth metal compound to obtain a polymer having an active terminal; (a modification) reacting the polymer having an active terminal with a compound [M] having a plurality of hydrocarbyloxysilyl groups to obtain a modified polymer; and a mixing the modified polymer with at least one compound [C] selected from a compound [N] having one hydrocarbyloxysilyl group and an alcohol having 6 to 20 carbon atoms.

Provided is a pneumatic tire having excellent abrasion resistance and excellent handling stability on an extremely cold road while having a reduced weight. The present disclosure relates to a pneumatic tire, including a tread having a hardness at −20° C. of 90 or less, a hardness at 30° C. of 60 or more, and a maximum thickness of 8.5 mm or less, and a carcass including one carcass ply.

The conjugated diene-based polymer has a Mooney viscosity measured at 100° C. of 40 or more and 170 or less, has Mooney stress relaxation measured at 100° C. of 0.35 or less, and has a branch number (Bn) measured by viscosity detector-equipped GPC-light scattering measurement of 8 or more.

A modifying agent, a modified conjugated diene polymer prepared using the same, a method for preparing a modified conjugated diene polymer, and a rubber composition including a modified conjugated diene polymer are disclosed herein. In some embodiments, a modifying agent comprises a compound represented by formula 1. The modifying agent is capable of improving processability of a rubber composition including the polymer prepared using the modifying agent. Fuel consumption properties of a car using tires including the rubber composition may be improved.

A modifying agent, a modified conjugated diene polymer prepared using the same, a method for preparing a modified conjugated diene polymer, and a rubber composition including a modified conjugated diene polymer are disclosed herein. In some embodiments, a modifying agent comprises a compound represented by formula 1. The modifying agent is capable of improving processability of a rubber composition including the polymer prepared using the modifying agent. Fuel consumption properties of a car using tires including the rubber composition may be improved.

The present invention provides a compounding agent which, when used in a rubber composition containing a reinforcing filler, exhibits excellent dispersibility, workability, toughness, low heat build-up, and wear resistance; and a rubber composition containing the compounding agent. A modified butadiene polymer of the present invention has a functional group containing a nitrogen atom and silicon atom at a terminal, a weight average molecular weight of the modified butadiene polymer being from 1000 to 15000, and a molecular weight distribution of the modified butadiene polymer being 2.0 or less.

The present invention provides a compounding agent which, when used in a rubber composition containing a reinforcing filler, exhibits excellent dispersibility, workability, toughness, low heat build-up, and wear resistance; and a rubber composition containing the compounding agent. A modified butadiene polymer of the present invention has a functional group containing a nitrogen atom and silicon atom at a terminal, a weight average molecular weight of the modified butadiene polymer being from 1000 to 15000, and a molecular weight distribution of the modified butadiene polymer being 2.0 or less.

The present invention relates to a rubber composition having excellent tensile properties and viscoelasticity properties and including a modified conjugated diene-based polymer. The rubber composition may include a modified conjugated diene-based polymer which is selected considering target tensile properties and viscoelasticity properties, by predicting in advance the correlation of the modification ratio of the modified conjugated diene-based polymer and the dynamic viscoelasticity loss coefficient at 60° C. of the rubber composition through Mathematical Formula 1 and Mathematical Formula 2. Therefore, excellent compounding properties may be shown.