Abstract: A rubber composition for a tire tread according to an embodiment includes, per 100 parts by mass of a diene rubber including 30 to 85 parts by mass of a styrene butadiene rubber and 15 to 70 parts by mass of a butadiene rubber and having an average glass transition temperature of -57° C. or less: 90 to 150 parts by mass of silica; 5 to 30 parts by mass of an oil; and 10 parts by mass or more and less than 40 parts by mass of a thermoplastic resin having a softening point of 40° C. or more. In the rubber composition, the total content of the oil and the thermoplastic resin is less than 45 parts by mass, and the oil content is less than 20 parts by mass per 100 parts by mass of silica.

Abstract: A rubber composition for a tire tread is disclosed, which provides a tire excellent in wet grip performance at low temperatures and wet grip performance at high temperatures. The rubber composition for a tire tread includes, per 100 parts by mass of diene-based rubbers including (a) 30 to 50 parts by mass of a styrene butadiene rubber having a glass transition point of ?35° C. or more, (b) 20 to 40 parts by mass of a styrene butadiene rubber having a glass transition point of ?45° C. or more and less than ?35° C., and (c) 10 to 30 parts by mass of a styrene butadiene rubber having a glass transition point of ?65° C. or more and less than ?45° C.: 80 to 140 parts by mass of silica; and 15 to 50 parts by mass of a thermoplastic resin having a softening point of 40° C. or more.

Abstract: Provided a rubber composition for a tire that can improve processability while maintaining reinforcing property that is a property of a hydrogenated copolymer, and a pneumatic tire using the same. A rubber composition for a tire comprising 100 parts by mass of a hydrogenated copolymer obtained by hydrogenating an aromatic vinyl-conjugated diene copolymer, the hydrogenated copolymer having a weight average molecular weight measured by gel permeation chromatography of 300,000 or more and having a hydrogenation ratio of a conjugated diene moiety of 80 mol % or more, and 3 to 30 parts by mass of crosslinked rubber particles.

Abstract: A rubber composition for a tire having further improved processability while maintaining abrasion resistance that is a property of a hydrogenated copolymer, and a pneumatic tire using the same, are disclosed. A rubber composition for a tire comprising a solid rubber component containing a hydrogenated copolymer obtained by hydrogenating an aromatic vinyl-conjugated diene copolymer, the hydrogenated copolymer having a weight average molecular weight measured by gel permeation chromatography of 300,000 or more and having a hydrogenation ratio of a conjugated diene moiety of 80 mol % or more, and a liquid rubber.

Abstract: A novel silicon compound capable of initiating radical polymerization is provided. The silicon compound is represented by the following general formula (1) A-Z1—S—Z2—Si(OR1)n(R2)3-n??(1) wherein A is a group capable of initiating radical polymerization, Z1 and Z2 are each independently a bivalent group that has at least a carbon atom, R1 and R2 are each independently an alkyl group having from 1 to 3 carbon atoms, and n is an integer of 1 to 3. A radical polymerization initiator comprising the silicon compound, and a polymer obtained by radical polymerization of a monomer with the radical polymerization initiator are also provided. Also provided is a complex having a polymer graft chain formed on a solid substance surface with the use of the silicon compound.

Abstract: A novel silicon compound capable of initiating radical polymerization is provided. The silicon compound is represented by the following general formula (1) A-Z1—S—Z2—Si(OR1)n(R2)3-n??(1) wherein A is a group capable of initiating radical polymerization, Z1 and Z2 are each independently a bivalent group that has at least a carbon atom, R1 and R2 are each independently an alkyl group having from 1 to 3 carbon atoms, and n is an integer of 1 to 3. A radical polymerization initiator comprising the silicon compound, and a polymer obtained by radical polymerization of a monomer with the radical polymerization initiator are also provided. Also provided is a complex having a polymer graft chain formed on a solid substance surface with the use of the silicon compound.

Abstract: An alkoxysilyl group-containing azo compound represented by the following formula (I), a method for easily obtaining the alkoxysilyl group-containing azo compound, and a rubber composition having improved heat build-up characteristic and the like obtained using the azo compound are provided. The alkoxysilyl group-containing azo compound is preferably obtained by reacting a compound represented by the following formula (2) and a compound represented by the following formula (3); wherein R1 and R2 represent an alkyl group having from 1 to 3 carbon atoms, R3 and R8 represent an alkylene group having from 1 to 3 carbon atoms, R4, R5, R6 and R7 represent hydrogen or an alkyl group having from 1 to 3 carbon atoms, n is an integer of from 1 to 3, and m is an integer of from 1 to 5.

Abstract: An alkoxysilyl group-containing azo compound represented by the following formula (1), a method for easily obtaining the alkoxysilyl group-containing azo compound, and a rubber composition having improved heat build-up characteristic and the like obtained using the azo compound are provided. The alkoxysilyl group-containing azo compound is preferably obtained by reacting a compound represented by the following formula (2) and a compound represented by the following formula (3): HS—(CH2)m—Si(OR1)n(R2)3-n??(3) wherein R1 and R2 represent an alkyl group having from 1 to 3 carbon atoms, R3 and R8 represent an alkylene group having from 1 to 3 carbon atoms, R4, R5, R6 and R7 represent hydrogen or an alkyl group having from 1 to 3 carbon atoms, n is an integer of from 1 to 3, and m is an integer of from 1 to 5.