JP2013166865A - Rubber composition for tire tread - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for tire treads, which is configured to improve low rolling resistance, wet performance and wear resistance to levels higher than those of conventional ones.SOLUTION: A rubber composition for tire treads is obtained by blending 3-40 pts.wt. of an aromatic modified terpene resin that has a softening point of 100-150°C and 60-150 pts.wt. of a filler that contain ≥50 wt.% of silica, per 100 pts.wt. of a diene rubber that contains 35-95 wt.% of a modified conjugated diene polymer rubber and 5-40 wt.% of a terminally modified butadiene rubber. The modified conjugated diene polymer rubber has a terminally modified group that contains a functional group interactive with silica. This modified conjugated diene polymer rubber has an aromatic vinyl unit content of 38-48 wt.%, a vinyl unit content of 20-35 wt.%, and a weight average molecular weight of 600,000-1,000,000. The terminally modified butadiene rubber has a vinyl unit content of ≤20 wt.%.

Description

  The present invention relates to a rubber composition for a tire tread, and more particularly, to a rubber composition for a tire tread in which low rolling resistance, wet performance, and wear resistance are improved to a conventional level or more.

  As performance requirements for pneumatic tires for high-performance vehicles, in addition to excellent driving stability and braking performance when driving on wet roads, and excellent durability, fuel efficiency is also improved due to increased interest in global environmental issues It is demanded. For this reason, by adding silica to the rubber composition constituting the tread portion, the dynamic viscoelastic properties such as loss tangent (tan δ) of the tread rubber are improved, heat generation is suppressed, rolling resistance is reduced, and fuel efficiency performance is improved. Increasing the wet performance as well as increasing. However, silica has poor affinity with diene rubber and tends to be poorly dispersed, and especially when the particle size of silica is small, the dispersibility deteriorates, so the effect of improving low heat build-up and wet performance can be sufficiently obtained. There wasn't. In addition, the reinforcing property is small and the wear resistance tends to be lower than that of carbon black. If the dispersibility is poor, the wear resistance is further lowered.

  For this reason, Patent Document 1 improves the dispersibility of silica with a rubber composition in which silica is blended with a terminal-modified solution-polymerized styrene butadiene rubber whose terminal is modified with polyorganosiloxane or the like, and the exothermic property (tan δ at 60 ° C.) is improved. It has been proposed to reduce the wet grip property (tan δ at 0 ° C.) and improve the wear resistance. Patent Document 2 discloses a rubber composition in which 80 to 180 parts by weight of a filler containing 50 parts by weight or more of silica and 5 to 60 parts by weight of a resin having a softening point of 100 to 150 ° C. are blended with 100 parts by weight of a styrene butadiene copolymer rubber. Proposing things.

  However, the level of demand that consumers expect to improve low rolling resistance, wet performance and wear resistance is higher than the performance achieved by these rubber compositions, further reducing low rolling resistance, wet performance and wear resistance. There was a need to improve.

JP 2009-91498 A JP 2007-321046 A

  An object of the present invention is to provide a rubber composition for a tire tread in which low rolling resistance, wet performance, and wear resistance are improved to a level higher than conventional levels.

  The rubber composition for a tire tread of the present invention that achieves the above object is based on 100 parts by weight of a diene rubber containing 35 to 95% by weight of a modified conjugated diene polymer rubber and 5 to 40% by weight of a terminal modified butadiene rubber. 3-40 parts by weight of the aromatic modified terpene resin and 60-150 parts by weight of the filler are blended, the filler contains 50% by weight or more of silica, and the modified conjugated diene polymer rubber is a hydrocarbon solvent. Among them, an active conjugated diene polymer chain obtained by copolymerizing a conjugated diene monomer and an aromatic vinyl monomer using an organic active metal compound as an initiator can react with the active end of the polymer chain. The modified conjugated diene polymer rubber has a terminal modified group obtained by reacting at least one compound having a functional group, the terminal modified group includes a functional group having an interaction with silica. The aromatic vinyl unit content is 38 to 48% by weight, the vinyl unit content is 20 to 35% by weight, the weight average molecular weight is 600,000 to 1 million, and the vinyl unit content of the terminal-modified butadiene rubber is 20% by weight. %, And the softening point of the aromatic modified terpene resin is 100 to 150 ° C.

  The rubber composition for a tire tread of the present invention has at least one functional group having a reactive group at the active end of an active conjugated diene polymer chain obtained by copolymerizing a conjugated diene monomer and an aromatic vinyl monomer. It has a terminal-modified group obtained by reacting various types of compounds, the terminal-modified group includes a functional group having an interaction with silica, the aromatic vinyl unit content is 38 to 48% by weight, and the vinyl unit content is 20 35 to 95% by weight, 35 to 95% by weight of a modified conjugated diene polymer rubber having a weight average molecular weight of 600,000 to 1,000,000, and 5 to 40% by weight of a terminal modified butadiene rubber having a vinyl unit content of 20% by weight or less. 3 to 40 parts by weight of an aromatic modified terpene resin having a softening point of 100 to 150 ° C. and 60 to 150 parts by weight of a filler containing 50% by weight or more of silica are blended with 100 parts by weight of a diene rubber containing 100% by weight. And by, while reducing the rolling resistance by reducing the exothermic by improving the dispersibility of the high affinity between the diene rubber and silica silica, it can improve the wet performance. In particular, when the aromatic vinyl unit content is 38 to 48% by weight, the modified conjugated diene polymer rubber forms a fine phase separation form and can react with the active end of the active conjugated diene polymer chain. The terminal modified group produced by the reaction with at least one kind of compound having a group contains a functional group that interacts with silica, and the concentration of the terminal modified group is optimized by making the weight average molecular weight 600,000 to 1,000,000. As a result, the terminal-modified group acts efficiently on the silica, further improving the dispersibility of the silica, greatly reducing the low rolling resistance of the pneumatic tire, and further improving the wet performance. Further, when 5 to 40% by weight of the terminal-modified butadiene rubber is contained in the diene rubber, the wear resistance can be improved while maintaining excellent low rolling resistance and wet performance. Furthermore, since the softening point of the aromatic modified terpene resin is set to 100 to 150 ° C., the wet performance can be further improved while maintaining excellent low rolling resistance.

  As the functional group of the modified butadiene rubber, a polyorganosiloxane group is preferable, and it has excellent reactivity with a silanol group on the silica surface, and the dispersibility of silica can be further improved.

  The aromatic-modified terpene resin is preferably a terpene resin modified with styrene, and can achieve both excellent low rolling resistance and wet performance.

  The compound having a functional group capable of reacting with the active end of the active conjugated diene polymer chain described above may include at least one polyorganosiloxane compound selected from the following general formulas (I) to (III).

（上記式（Ｉ）において、Ｒ¹〜Ｒ⁸は、炭素数１〜６のアルキル基または炭素数６〜１２のアリール基であり、これらは互いに同一であっても相違してもよい。Ｘ¹およびＸ⁴は、活性共役ジエン系重合体鎖の活性末端と反応する官能基を有する基、または炭素数１〜６のアルキル基もしくは炭素数６〜１２のアリール基であり、Ｘ¹およびＸ⁴は互いに同一であっても相違してもよい。Ｘ²は、活性共役ジエン系重合体鎖の活性末端と反応する官能基を有する基である。Ｘ³は、２〜２０のアルキレングリコールの繰返し単位を含有する基であり、Ｘ³の一部は２〜２０のアルキレングリコールの繰返し単位を含有する基から導かれる基であってもよい。ｍは３〜２００の整数、ｎは０〜２００の整数、ｋは０〜２００の整数である。）

(In the above formula (I), R ^{1 to} R ⁸ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same or different from each other. X ¹ and X ⁴ are the active conjugated diene polymer chain groups having a functional group capable of reacting with the active terminal of an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon atoms,, X ¹ and X ⁴ may be the same as or different from each other, X ² is a group having a functional group that reacts with the active end of the active conjugated diene polymer chain, and X ³ is an alkylene glycol of 2 to 20 It is a group containing a repeating unit, and a part of X ³ may be a group derived from a group containing a repeating unit of 2 to 20 alkylene glycol, m is an integer of 3 to 200, and n is 0 to 0. 200 is an integer, and k is an integer of 0 to 200.)

（上記式（ＩＩ）において、Ｒ⁹〜Ｒ¹⁶は、炭素数１〜６のアルキル基または炭素数６〜１２のアリール基であり、これらは互いに同一であっても相違してもよい。Ｘ⁵〜Ｘ⁸は、活性共役ジエン系重合体鎖の活性末端と反応する官能基を有する基である。）

(In the above formula (II), R ^{9 to} R ¹⁶ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same as or different from each other. ^{5 to} X ⁸ are groups having a functional group that reacts with the active terminal of the active conjugated diene polymer chain.

（上記式（ＩＩＩ）において、Ｒ¹⁷〜Ｒ¹⁹は、炭素数１〜６のアルキル基または炭素数６〜１２のアリール基であり、これらは互いに同一であっても相違してもよい。Ｘ⁹〜Ｘ¹¹は、活性共役ジエン系重合体鎖の活性末端と反応する官能基を有する基である。ｓは１〜１８の整数である。）

(In the above formula (III), R ^{17 to} R ¹⁹ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same as or different from each other. ^{9 to} X ¹¹ are groups having a functional group that reacts with the active end of the active conjugated diene polymer chain, and s is an integer of 1 to 18.)

  A pneumatic tire using this rubber composition in the tread portion can improve low rolling resistance, wet performance, and wear resistance to a level higher than the conventional level.

  In the rubber composition for a tire tread of the present invention, the rubber component is a diene rubber, and the diene rubber necessarily includes a modified conjugated diene polymer rubber and a terminal modified butadiene rubber.

  The modified conjugated diene polymer rubber is a conjugated diene polymer rubber produced by solution polymerization that has functional groups at both ends of a molecular chain. Incorporating the modified conjugated diene polymer rubber increases the affinity with silica and improves dispersibility, further improving the action and effect of silica, thus improving low rolling resistance and wet performance, Increase wear resistance.

  In the present invention, the skeleton of the modified conjugated diene polymer is composed of a copolymer obtained by copolymerizing a conjugated diene monomer and an aromatic vinyl monomer. Examples of the conjugated diene monomer include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, and 2-chloro-1,3-butadiene. 1,3-pentadiene and the like. Examples of the aromatic vinyl monomer include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, and 4-tert. -Butylstyrene, divinylbenzene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl) dimethylaminoethyl ether, N, N-dimethylaminoethylstyrene, vinylpyridine and the like.

  It is preferable that the terminal of the conjugated diene polymer serving as a skeleton is constituted by an isoprene unit block. Since the terminal is composed of isoprene unit blocks, when the terminal is modified and silica is blended, the affinity between the modified conjugated diene polymer and silica is improved, and low heat build-up, wet performance, wear resistance Good. Therefore, when the conjugated diene monomer unit constituting the polymer contains a conjugated diene other than the isoprene unit, before adding the compound having a functional group capable of reacting with the active end of the active conjugated diene polymer chain, Alternatively, it is preferable to introduce isoprene unit blocks at the ends of the polymer by adding isoprene to the solution containing the polymer having an active end while adding these compounds separately.

  In the present invention, the conjugated diene polymer is prepared by copolymerizing the conjugated diene monomer and the aromatic vinyl monomer described above in a hydrocarbon solvent using an organic active metal compound as an initiator. As a hydrocarbon solvent, what is necessary is just a solvent used normally, for example, cyclohexane, n-hexane, benzene, toluene etc. are illustrated.

  As the organic active metal catalyst to be used, an organic alkali metal compound is preferably used. For example, an organic monolithium compound such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, stilbenelithium; Organic polyvalent lithium compounds such as 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene; organic sodium compounds such as sodium naphthalene; organic potassium compounds such as potassium naphthalene Is mentioned. In addition, 3,3- (N, N-dimethylamino) -1-propyllithium, 3- (N, N-diethylamino) -1-propyllithium, 3- (N, N-dipropylamino) -1- Propyllithium, 3-morpholino-1-propyllithium, 3-imidazole-1-propyllithium and organolithium compounds in which these are chain-extended with 1 to 10 units of butadiene, isoprene or styrene can also be used.

  Also, in the polymerization reaction, diethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, 2,2-bis (2-oxolanyl) propane, etc. for the purpose of randomly copolymerizing aromatic vinyl monomers with conjugated diene monomers. It is also possible to add aprotic polar compounds such as amines such as ethers, triethylamine and tetramethylethylenediamine.

  In the present invention, at least one compound having a reactive functional group is bonded to the active terminal of an active conjugated diene polymer chain obtained by copolymerizing a conjugated diene monomer and an aromatic vinyl monomer. To generate a terminally modified group. Here, the compound having a functional group capable of reacting with the active terminal of the active conjugated diene polymer chain may be bonded to at least one active conjugated diene polymer chain, and one or more active conjugates may be bonded to one compound. Diene polymer chains can be bonded. That is, the modified conjugated diene polymer rubber used in the present invention is a modified rubber having modified groups at both ends of the conjugated diene polymer, and optionally other conjugated diene polymers having one or more modified groups. Bonded modified rubbers and mixtures of these modified rubbers can be included. In addition, the reaction between the active terminal of the active conjugated diene polymer chain and the compound having a functional group capable of reacting with this active terminal can be reacted in one stage or multiple stages. The same or different compounds can be reacted sequentially.

  In the present invention, examples of the compound having a functional group capable of reacting with the active terminal of the active conjugated diene polymer chain include tin compounds, silicon compounds, silane compounds, amide compounds and / or imide compounds, isocyanates and / or isothiocyanates. Examples of compounds having compounds, ketone compounds, ester compounds, vinyl compounds, oxirane compounds, thiirane compounds, oxetane compounds, polysulfide compounds, polysiloxane compounds, polyorganosiloxane compounds, polyether compounds, polyene compounds, halogen compounds, fullerenes, etc. be able to. Of these, polyorganosiloxane compounds are preferred. These compounds can be bonded to a polymer by combining one type of compound or a plurality of compounds.

  Specifically, two compounds such as polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether and glycerin triglycidyl ether, diglycidylated bisphenol A and the like can be reacted with the active terminal of the active conjugated diene polymer chain. Polyepoxy compounds such as polyglycidyl ethers of aromatic compounds having the above phenol groups, 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, polyepoxidized liquid polybutadiene, 4,4′-diglycidyl- Epoxy group-containing tertiary amine such as diphenylmethylamine, 4,4′-diglycidyl-dibenzylmethylamine, diglycidylaniline, diglycidylorthotoluidine, tetraglycidylmetaxylenediamine, tetraglycidylaminodiphenylmethane, Toragurishijiru -p- phenylenediamine, diglycidyl aminomethyl cyclohexane, diglycidyl amino compounds such as tetraglycidyl-1,3-bis-aminomethyl cyclohexane, and the like.

  Examples of the silicon compound include tetrachlorosilicon, tetrabromosilicon, methyltrichlorosilicon, butyltrichlorosilicon, dichlorosilicon, bistrichlorosilylsilicon, and the like.

  Examples of the tin compound include tetrachlorotin, tetrabromotin, methyltrichlorotin, butyltrichlorotin, dichlorotin, bistrichlorosilyltin, and bistrichlorosilyltin.

  Examples of the silane compound include a silane compound containing at least one selected from an alkoxy group, a phenoxy group, and a halogen. Examples of such silane compounds include dimethoxydimethylsilane, diphenoxydimethylsilane, diethoxydiethylsilane, triphenoxymethylsilane, triphenoxyvinylsilane, trimethoxyvinylsilane, triethoxyvinylsilane, tri (2-methylbutoxy) ethylsilane, tri (2-methylbutoxy) vinylsilane, triphenoxyphenylsilane, tetraphenoxysilane, tetraethoxysilane, tetramethoxysilane, tetrakis (2-ethylhexyloxy) silane, phenoxydivinylchlorosilane, methoxybiethylchlorosilane, diphenoxymethylchlorosilane, diphenoxy Phenyliodosilane, diethoxymethylchlorosilane, dimethoxymethylchlorosilane, trimethoxychlorosilane, Ethoxychlorosilane, triphenoxychlorosilane, tris (2-ethylhexyloxy) chlorosilane, phenoxymethyldichlorosilane, methoxyethyldichlorosilane, ethoxymethyldichlorosilane, phenoxyphenyldiiodosilane, diphenoxydichlorosilane, dimethoxydichlorosilane, bis (2- Methylbutoxy) dibromosilane, bis (2-methylbutoxy) dichlorosilane, diethoxydichlorosilane, methoxytrichlorosilane, ethoxytrichlorosilane, phenoxytrichlorosilane, (2-ethylhexyloxy) trichlorosilane, (2-methylbutoxy) trichlorosilane Etc. are exemplified.

  Moreover, the silane compound can have a glycidyl group, an epoxy group, a methacryloxy group, etc. as functional groups other than the above. Examples of such silane compounds include γ-glycidoxyethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxybutyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ -Glycidoxypropyltripropoxysilane, γ-glycidoxypropyltributoxysilane, γ-glycidoxypropyltriphenoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylethyldimethoxysilane, γ -Glycidoxypropylethyldiethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldipropoxysilane, γ-glycidoxypropylmethyldibutoxysilane, γ-glycidoxypropylmethyl Diphenoki Sisilane, γ-glycidoxypropyldimethylmethoxysilane, γ-glycidoxypropyldiethylethoxysilane, γ-glycidoxypropyldimethylethoxysilane, γ-glycidoxypropyldimethylphenoxysilane, γ-glycidoxypropyldiethylmethoxy Silane, γ-glycidoxypropylmethyldiisopropeneoxysilane, bis (γ-glycidoxypropyl) dimethoxysilane, bis (γ-glycidoxypropyl) diethoxysilane, bis (γ-glycidoxypropyl) di Propoxysilane, bis (γ-glycidoxypropyl) dibutoxysilane, bis (γ-glycidoxypropyl) diphenoxysilane, bis (γ-glycidoxypropyl) methylmethoxysilane, bis (γ-glycidoxypropyl) ) Methylethoxysilane, bi (Γ-glycidoxypropyl) methylpropoxysilane, bis (γ-glycidoxypropyl) methylbutoxysilane, bis (γ-glycidoxypropyl) methylphenoxysilane, tris (γ-glycidoxypropyl) methoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxymethyltrimethoxysilane, γ-methacryloxyethyltriethoxysilane, bis (γ-methacryloxypropyl) dimethoxysilane, tris (γ -Methacryloxypropyl) methoxysilane, β- (3,4-epoxycyclohexyl) ethyl-trimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-triethoxysilane, β- (3,4-epoxycyclohexyl) Ethyl-to Ripropoxysilane, β- (3,4-epoxycyclohexyl) ethyl-tributoxysilane, β- (3,4-epoxycyclohexyl) ethyl-triphenoxysilane, β- (3,4-epoxycyclohexyl) propyl-trimethoxy Silane, β- (3,4-epoxycyclohexyl) ethyl-methyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-ethyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-ethyldiethoxysilane , Β- (3,4-epoxycyclohexyl) ethyl-methyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldipropoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldibutoxy Silane, β- (3,4-epoxycyclohexyl) Ethyl-methyldiphenoxysilane, β-3,4-epoxycyclohexyl) ethyl-dimethylmethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-diethylethoxysilane, β- (3,4-epoxycyclohexyl) ethyl- Dimethylethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylpropoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylbutoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylphenoxy Examples include silane, β- (3,4-epoxycyclohexyl) ethyl-diethylmethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldiisopropeneoxysilane, and the like.

  Examples of the isocyanate compound or isothiocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, tolidine diisocyanate, triphenylmethane triisocyanate, p-phenylene diisocyanate, tris (isocyanatophenyl) thiophosphate, xylylene diisocyanate, benzene-1,2,4-triisocyanate, naphthalene-1,2,5,7-tetraisocyanate, naphthalene-1 , 3,7-triisocyanate, phenyl isocyanate, hexamethylene diisocyanate, methylcyclohexane diisocyanate, phenyl-1,4-diisothiocyanate, 2,4-tolylene diisocyanate And aromatic polyisocyanate compounds such as diphenylmethane diisocyanate and naphthalene diisocyanate.

  Furthermore, 4-dimethylaminobenzophenone, 4-diethylaminobenzophenone, 4-di-t-butylaminobenzophenone, 4-diphenylaminobenzophenone, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) Benzophenone, 4,4′-bis (di-t-butylamino) benzophenone, 4,4′-bis (diphenylamino) benzophenone, 4,4′-bis (divinylamino) benzophenone, 4-dimethylaminoacetophenone, 4- N-substituted aminoketones such as diethylaminoacetophenone, 1,3-bis (diphenylamino) -2-propanone, 1,7-bis- (methylethylamino) -4-heptanone, and corresponding N-substituted aminothioketones ; 4-diethylaminobenz aldehyde N-substituted aminoaldehydes such as 4-divinylaminobenzaldehyde and the corresponding N-substituted aminothioaldehydes; N-methyl-β-propiolactam, Nt-butyl-β-propiolactam, N-phenyl -Β-propiolactam, N-methoxyphenyl-β-propiolactam, N-naphthyl-β-propiolactam, N-methyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, N-phenyl- Pyrrolidone, N-methoxyphenyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-benzyl-2-pyrrolidone, N-naphthyl-2-pyrrolidone, N-methyl-5-methyl-2-pyrrolidone, N-methyl −3,3′-dimethyl-2-pyrrolidone, Nt-butyl-3,3′-dimethyl-2-pyrrolidone, N-phenyl-3, '-Dimethyl-2-pyrrolidone, N-methyl-2-piperidone, Nt-butyl-2-piperidone, N-phenyl-piperidone, N-methoxyphenyl-2-piperidone, N-vinyl-2-piperidone, N -Benzyl-2-piperidone, N-naphthyl-2-piperidone, N-methyl-3,3'-dimethyl-2-piperidone, N-phenyl-3,3'-dimethyl-2-piperidone, N-methyl-ε -Caprolactam, N-phenyl-ε-caprolactam, N-methoxyphenyl-ε-caprolactam, N-vinyl-ε-caprolactam, N-benzyl-ε-caprolactam, N-naphthyl-ε-caprolactam, N-methyl-ω- Laurylactam, N-phenyl-ω-laurylactam, Nt-butyl-laurylactam, N-vinyl-ω-ra N-substituted lactams such as rilolactam and N-benzyl-ω-laurylactam and their corresponding thiolactams; 3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1 , 3-dipropyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 1-methyl-3-propyl-2-imidazolidinone, 1-methyl-3-til-2-imidazolidone N-substituted ethyleneureas such as ridinone, 1-methyl-3--2-ethoxyethyl) -2-imidazolidinone, 1,3-dimethyl-3,4,5,6-tetrahydropyrimidinone and the corresponding N-substituted thioethylene ureas, etc .; 4,4′-bis (dimethylamino) -benzophenone, 4,4′-bis (diethylamino) -benzophenone, 4,4′-bi (Dibutylamino) -benzophenone, 4,4′-diaminobenzophenone, 4-dimethylaminobenzophenone, etc. and their corresponding thiobenzophenone, etc., at least one amino group, alkylamino group or dialkyl on one or both benzene rings Examples include benzophenone and thiobenzophenone having an amino group;

  As a silicon compound containing a halogen and / or an alkoxy group, a compound represented by the following general formula (IV) is preferable, and a plurality of active conjugated diene polymer chains can be easily bonded to one molecule of the compound.

（式（ＩＶ）において、Ｘ¹及びＸ²はハロゲン原子又は炭素数１〜２０のアルコキシ基である。ｐ及びｑは、それぞれ独立に０〜３の整数であり、式（ＩＶ）で表わされる化合物におけるハロゲン原子及び炭素数１〜２０のアルコキシ基の数の合計は５以上である。Ｒ¹及びＲ²は、それぞれ炭素数１〜２０の１価の炭化水素基である。ｎは、０〜２０の整数であり、Ａ¹及びＡ²は、それぞれ独立に、単結合又は炭素数１〜２０の２価の炭化水素である。Ａ³は、式−（ＳｉＸ³ _rＲ³ _2-r）_m−、又は−ＮＲ⁴−、又は−Ｎ（−Ａ⁴−ＳｉＸ⁴ _SＲ⁵ _3-S）−で表わされる２価の基である。なお、Ｘ³，Ｘ⁴は、ハロゲン原子または炭素数１〜２０のアルコキシ基である。Ｒ³，Ｒ⁵は、炭素数１〜２０の１価の炭化水素基である。Ｒ⁴は、水素原子または炭素数１〜２０の１価の炭化水素基である。Ａ⁴は、単結合または炭素数１〜２０の２価の炭化水素基である。ｒは０〜２の整数であり、ｍは０〜２０の整数である。ｓは、０〜３の整数である。）

In (Formula (IV), X ¹ and X ² is an alkoxy group having a halogen atom or a C 1 to 20 .p and q are each independently an integer of 0 to 3, of formula (IV) The total number of halogen atoms and alkoxy groups having 1 to 20 carbon atoms in the compound is at least 5. R ¹ and R ² are each a monovalent hydrocarbon group having 1 to 20 carbon atoms, where n is 0. And A ¹ and A ² are each independently a single bond or a divalent hydrocarbon having 1 to 20 carbon atoms, A ³ is represented by the formula — (SiX ³ _r R ³ _2-r ) _m -, or -NR ⁴ -, or _{^{-N (-A 4 -SiX 4 S R}} 5 3-S) -. a bivalent group represented by Incidentally, X ^3, X ⁴ is a halogen atom or is .R ^3, R ⁵ is an alkoxy group having 1 to 20 carbon atoms, a monovalent hydrocarbon group having 1 to 20 carbon atoms .R ⁴ is hydrogen Is a child or a monovalent hydrocarbon group having 1 to 20 carbon atoms .A ⁴ is, .r is a divalent hydrocarbon group of a single bond or a C 1-20 is an integer of 0 to 2, m Is an integer from 0 to 20. s is an integer from 0 to 3.)

  Examples of the compound represented by the general formula (IV) include hexachlorodisilane, bis (trichlorosilyl) methane, 1,2-bis (trichlorosilyl) ethane, 1,3-bis (trichlorosilyl) propane, and 1,4. -Halogenated silicon compounds such as bis (trichlorosilyl) butane, 1,5-bis (trichlorosilyl) pentane, 1,6-bis (trichlorosilyl) hexane; hexamethoxydisilane, hexaethoxydisilane, bis (trimethoxysilyl) Methane, bis (triethoxysilyl) methane, bis (trimethoxysilyl) ethane, bis (triethoxysilyl) ethane, bis (trimethoxysilyl) propane, bis (triethoxysilyl) propane, bis (trimethoxysilyl) butane, Bis (triethoxysilyl) butane, bis (to Methoxysilyl) heptane, bis (triethoxysilyl) heptane, bis (trimethoxysilyl) hexane, bis (triethoxysilyl) hexane, bis (trimethoxysilyl) benzene, bis (triethoxysilyl) benzene, bis (trimethoxysilyl) ) Cyclohexane, bis (triethoxysilyl) cyclohexane, bis (triethoxysilyl) benzene, bis (trimethoxysilyl) octane, bis (triethoxysilyl) octane, bis (trimethoxysilyl) nonane, bis (triethoxysilyl) nonane Bis (trimethoxysilyl) ethylene, bis (triethoxysilyl) ethylene, bis (trimethoxysilylethyl) benzene, bis (triethoxysilylethyl) benzene, bis (3-trimethoxysilylpropyl) ethane , Alkoxysilane compounds such as bis (3-triethoxysilylpropyl) ethane; bis (3-trimethoxysilylpropyl) methylamine, bis (3-triethoxysilylpropyl) methylamine, bis (3-trimethoxysilylpropyl) Ethylamine, bis (3-triethoxysilylpropyl) ethylamine, bis (3-trimethoxysilylpropyl) propylamine, bis (3-triethoxysilylpropyl) propylamine, bis (3-trimethoxysilylpropyl) butylamine, bis ( 3-triethoxysilylpropyl) butylamine, bis (3-trimethoxysilylpropyl) phenylamine, bis (3-triethoxysilylpropyl) phenylamine, bis (3-trimethoxysilylpropyl) benzylamine, bis (3- Triethoxysilylpropyl) benzylamine, bis (trimethoxysilylmethyl) methylamine, bis (triethoxysilylmethyl) methylamine, bis (2-trimethoxysilylethyl) methylamine, bis (2-triethoxysilylethyl) methyl Alkoxysilane compounds containing amino groups such as amine, bis (triethoxysilylmethyl) propylamine, bis (2-triethoxysilylethyl) propylamine; tris (trimethoxysilylmethyl) amine, tris (2-triethoxysilylethyl) And alkoxysilane compounds containing an amino group such as amine, tris (3-trimethoxysilylpropyl) amine, tris (3-triethoxysilylpropyl) amine, and the like.

  As the polyorganosiloxane compound, compounds represented by the following general formulas (I) to (III) are preferable. That is, the compound having a functional group capable of reacting with the active terminal of the active conjugated diene polymer chain may contain at least one selected from these polyorganosiloxane compounds, and a plurality of types may be combined. Moreover, you may combine these polyorganosiloxane compounds and the other compound which has a functional group which can react with an active terminal, for example, the compound represented by Formula (IV) mentioned above.

（上記式（Ｉ）において、Ｒ¹〜Ｒ⁸は、炭素数１〜６のアルキル基または炭素数６〜１２のアリール基であり、これらは互いに同一であっても相違してもよい。Ｘ¹およびＸ⁴は、活性共役ジエン系重合体鎖の活性末端と反応する官能基を有する基、または炭素数１〜６のアルキル基もしくは炭素数６〜１２のアリール基であり、Ｘ¹およびＸ⁴は互いに同一であっても相違してもよい。Ｘ²は、活性共役ジエン系重合体鎖の活性末端と反応する官能基を有する基である。Ｘ³は、２〜２０のアルキレングリコールの繰返し単位を含有する基であり、Ｘ³の一部は２〜２０のアルキレングリコールの繰返し単位を含有する基から導かれる基であってもよい。ｍは３〜２００の整数、ｎは０〜２００の整数、ｋは０〜２００の整数である。） Formula (I)

(In the above formula (I), R ^{1 to} R ⁸ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same or different from each other. X ¹ and X ⁴ are the active conjugated diene polymer chain groups having a functional group capable of reacting with the active terminal of an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon atoms,, X ¹ and X ⁴ may be the same as or different from each other, X ² is a group having a functional group that reacts with the active end of the active conjugated diene polymer chain, and X ³ is an alkylene glycol of 2 to 20 It is a group containing a repeating unit, and a part of X ³ may be a group derived from a group containing a repeating unit of 2 to 20 alkylene glycol, m is an integer of 3 to 200, and n is 0 to 0. 200 is an integer, and k is an integer of 0 to 200.)

（上記式（ＩＩ）において、Ｒ⁹〜Ｒ¹⁶は、炭素数１〜６のアルキル基または炭素数６〜１２のアリール基であり、これらは互いに同一であっても相違してもよい。Ｘ⁵〜Ｘ⁸は、活性共役ジエン系重合体鎖の活性末端と反応する官能基を有する基である。） Formula (II)

(In the above formula (II), R ^{9 to} R ¹⁶ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same as or different from each other. ^{5 to} X ⁸ are groups having a functional group that reacts with the active terminal of the active conjugated diene polymer chain.

（上記式（ＩＩＩ）において、Ｒ¹⁷〜Ｒ¹⁹は、炭素数１〜６のアルキル基または炭素数６〜１２のアリール基であり、これらは互いに同一であっても相違してもよい。Ｘ⁹〜Ｘ¹¹は、活性共役ジエン系重合体鎖の活性末端と反応する官能基を有する基である。ｓは１〜１８の整数である。） General formula (III):

(In the above formula (III), R ^{17 to} R ¹⁹ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same as or different from each other. ^{9 to} X ¹¹ are groups having a functional group that reacts with the active end of the active conjugated diene polymer chain, and s is an integer of 1 to 18.)

In the polyorganosiloxane represented by the above general formula (I), examples of the alkyl group having 1 to 6 carbon atoms constituting R ^{1 to} R ⁸ , X ¹ and X ⁴ include, for example, methyl group, ethyl group, n- Examples include propyl group, isopropyl group, butyl group, pentyl group, hexyl group, cyclohexyl group and the like. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a methylphenyl group. Among these alkyl groups and aryl groups, a methyl group is particularly preferable.

In the polyorganosiloxane of the general formula (I), the group having a functional group that reacts with the active terminal of the polymer chain constituting X ¹ , X ² and X ⁴ includes an alkoxyl group having 1 to 5 carbon atoms, 2- A hydrocarbon group containing a pyrrolidonyl group and a group having 4 to 12 carbon atoms containing an epoxy group are preferred.

The alkoxyl group having 1 to 5 carbon atoms constituting the X ^1, X ² and X ^4, for example, a methoxy group, an ethoxy group, a propoxy group, isopropoxy group, butoxy group. Of these, a methoxy group is preferable. When at least one of X ¹ , X ² and X ⁴ is an alkoxyl group having 1 to 5 carbon atoms, when a polyorganosiloxane having an alkoxyl group at the active end of the active conjugated diene polymer chain is reacted, a silicon atom and an alkoxyl The bond with the oxygen atom of the group is cleaved, and the active conjugated diene polymer chain is directly bonded to the silicon atom to form a single bond.

Preferred examples of the hydrocarbon group containing a 2-pyrrolidonyl group constituting X ¹ , X ² and X ⁴ include groups represented by the following general formula (V).

（式（Ｖ）中、ｊは２〜１０の整数である。特にｊは２であることが好ましい。）
このようにＸ¹，Ｘ²及びＸ⁴の少なくとも一つが２−ピロリドニル基を含有する炭化水素基を含むポリオルガノシロキサンを、活性共役ジエン系重合体鎖の活性末端に反応させると、２−ピロリドニル基を構成するカルボニル基の炭素−酸素結合が開裂して、その炭素原子に重合体鎖が結合した構造を形成する。

(In the formula (V), j is an integer of 2 to 10. In particular, j is preferably 2.)
When polyorganosiloxane containing a hydrocarbon group in which at least one of X ¹ , X ² and X ⁴ contains a 2-pyrrolidonyl group is reacted with the active end of the active conjugated diene polymer chain, 2-pyrrolidonyl is obtained. The carbon-oxygen bond of the carbonyl group constituting the group is cleaved to form a structure in which the polymer chain is bonded to the carbon atom.

Preferred examples of the group having 4 to 12 carbon atoms having an epoxy group constituting X ¹ , X ² and X ⁴ include groups represented by the following general formula (VI).
Formula (VI): ZYE
In the above formula (VI), Z is an alkylene group having 1 to 10 carbon atoms or an alkylarylene group, Y is a methylene group, sulfur atom or oxygen atom, and E is a carbon atom having 2 to 10 carbon atoms having an epoxy group. It is a hydrogen group. Among these, Y is preferably an oxygen atom, more preferably Y is an oxygen atom and E is a glycidyl group, Z is an alkylene group having 3 carbon atoms, Y is an oxygen atom, and E is a glycidyl group. Those are particularly preferred.

In the polyorganosiloxane represented by the general formula (I), when at least one of X ¹ , X ² and X ⁴ is a group having 4 to 12 carbon atoms containing an epoxy group, the activity of the active conjugated diene polymer chain When polyorganosiloxane is reacted at the terminal, the carbon-oxygen bond constituting the epoxy ring is cleaved to form a structure in which a polymer chain is bonded to the carbon atom.

In the polyorganosiloxane represented by the general formula (I), X ¹ and X ⁴ are preferably an epoxy group-containing group having 4 to 12 carbon atoms or an alkyl group having 1 to 6 carbon atoms, X ² is preferably a group having 4 to 12 carbon atoms containing an epoxy group.

In the polyorganosiloxane represented by the general formula (I), X ³ is a group containing 2 to 20 alkylene glycol repeating units. As a group containing the repeating unit of 2-20 alkylene glycol, group represented by the following general formula (VII) is preferable.

式（ＶＩＩ）中、ｔは２〜２０の整数であり、Ｒ¹は炭素数２〜１０のアルキレン基またはアルキルアリーレン基であり、Ｒ³は水素原子またはメチル基であり、Ｒ²は炭素数１〜１０のアルコキシル基またはアリーロキシ基である。これらの中でも、ｔが２〜８の整数であり、Ｒ¹が炭素数３のアルキレン基であり、Ｒ³が水素原子であり、かつＲ²がメトキシ基であるものが好ましい。

In the formula (VII), t is an integer of 2 to 20, R ¹ is an alkylene group or an alkylarylene group having 2 to 10 carbon atoms, R ³ is a hydrogen atom or a methyl group, and R ² is a carbon number. 1-10 alkoxyl groups or aryloxy groups. Among these, it is preferable that t is an integer of 2 to 8, R ¹ is an alkylene group having 3 carbon atoms, R ³ is a hydrogen atom, and R ² is a methoxy group.

In the polyorganosiloxane represented by the general formula (II), R ^{9 to} R ¹⁶ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same or different from each other. You may do it. X ^{5 to} X ⁸ are groups having a functional group that reacts with the active end of the polymer chain.

In the polyorganosiloxane represented by the general formula (III), R ^{17 to} R ¹⁹ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same or different from each other. You may do it. X ^{9 to} X ¹¹ are groups having a functional group that reacts with the active end of the polymer chain. s is an integer of 1-18.

  In the polyorganosiloxane represented by the general formula (II) and the general formula (III), it reacts with an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an active end of a polymer chain. The group having a functional group is the same as that described for the polyorganosiloxane of the general formula (I).

  Furthermore, the terminal modified group produced | generated by the said reaction has a functional group which has an interaction with a silica. The functional group having an interaction with silica may be a functional group included in the structure of the compound described above. Moreover, the functional group which could be produced by reaction with the said compound and active terminal may be sufficient. The functional group having an interaction with silica is not particularly limited. For example, alkoxysilyl group, hydroxyl group (including organosiloxane structure), aldehyde group, carboxyl group, amino group, imino group, epoxy group Amide, thiol group, ether group and the like. Of these, a hydroxyl group (including an organosiloxane structure) is preferred. Thus, when a terminal modification group contains the functional group which has an interaction with a silica, affinity with a silica can be made higher and a dispersibility can be improved significantly.

  In the present invention, the concentration of the terminal modified group in the modified conjugated diene polymer rubber is determined by the relationship with the weight average molecular weight (Mw) of the modified conjugated diene polymer rubber. The weight average molecular weight of the modified conjugated diene polymer rubber is 600,000 to 1,000,000, preferably 65 to 850,000. When the weight average molecular weight of the modified conjugated diene polymer rubber is less than 600,000, the modified group concentration at the end of the modified conjugated diene polymer rubber is increased, and the dispersibility of silica in the rubber composition is improved. Since the molecular weight of the polymer itself is low, the effect of improving the strength and rigidity cannot be sufficiently obtained, the wear resistance is insufficient, and the improvement range of the viscoelastic property may be reduced. In addition, the wear resistance of the rubber composition may be reduced. On the other hand, if the weight average molecular weight of the modified conjugated diene polymer rubber exceeds 1,000,000, the modified group concentration at the end of the modified conjugated diene polymer rubber will be low, so that the affinity with silica will be insufficient and the dispersibility will deteriorate. The effect of reducing rolling resistance is insufficient or the wet performance is insufficient. At the same time, the rigidity and strength of the rubber composition are lowered. The weight average molecular weight (Mw) of the modified conjugated diene polymer rubber is measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

  The modified conjugated diene polymer rubber used in the present invention has an aromatic vinyl unit content of 38 to 48% by weight, preferably 40 to 45% by weight. By making the aromatic vinyl unit content of the modified conjugated diene polymer rubber in such a range, the wet performance and wear resistance when the rubber composition is made into a pneumatic tire by increasing the rigidity and strength of the rubber composition. It can be compatible. When other diene rubbers other than the modified conjugated diene polymer rubber are blended, the modified conjugated diene polymer rubber forms a fine phase separation form with respect to the other diene rubber. For this reason, the modified conjugated diene polymer rubber is localized near the silica particles, and the affinity of the terminal modified group is increased due to the effective action of the terminal modified group on the silica, thereby dispersing the silica. Property can be improved. When the aromatic vinyl unit content of the modified conjugated diene polymer rubber is less than 38% by weight, the effect of forming a fine phase separation form with respect to other diene rubbers cannot be sufficiently obtained. For this reason, the effect of improving wet performance and increasing the rigidity and strength of the rubber composition cannot be sufficiently obtained. Further, the effect of increasing the rigidity and strength of the rubber composition cannot be sufficiently obtained. On the other hand, when the aromatic vinyl unit content of the modified conjugated diene polymer rubber exceeds 48% by weight, the glass transition temperature (Tg) of the conjugated diene polymer rubber rises, the balance of viscoelastic properties becomes worse, and heat is generated. It becomes difficult to obtain the effect of reducing the property. The aromatic vinyl unit content of the modified conjugated diene polymer rubber is measured by infrared spectroscopic analysis (Hampton method).

  In the present invention, the vinyl unit content of the modified conjugated diene polymer rubber is 20 to 35% by weight, preferably 26 to 34% by weight. By making the vinyl unit content of the modified conjugated diene polymer rubber 20 to 35% by weight, the Tg of the modified conjugated diene polymer rubber can be optimized. Moreover, the fine phase-separation form of the modified conjugated diene polymer rubber formed with respect to other diene rubber can be stabilized. When the vinyl unit content of the modified conjugated diene polymer rubber is less than 20% by weight, the Tg of the modified conjugated diene polymer rubber becomes low, and the loss of dynamic viscoelastic properties at 0 ° C., which is an index of wet performance. The tangent (tan δ) decreases. Moreover, the fine phase separation form of the modified conjugated diene polymer rubber cannot be stabilized. On the other hand, if the vinyl unit content of the modified conjugated diene polymer rubber exceeds 35% by weight, the vulcanization rate may decrease, and the strength and rigidity may decrease. Further, the effect of reducing the loss tangent (tan δ) of the dynamic viscoelastic property at 60 ° C., which is an index of heat generation, cannot be sufficiently obtained, and the rolling resistance cannot be sufficiently reduced when the tire is formed. The vinyl unit content of the modified conjugated diene polymer rubber is measured by infrared spectroscopic analysis (Hampton method).

  The Tg of the modified conjugated diene polymer rubber is preferably −22 to −32 ° C. By setting the Tg of the modified conjugated diene polymer rubber to −22 to −32 ° C., the wet performance can be secured and the rolling resistance can be reduced. If the Tg of the modified conjugated diene polymer rubber is higher than −22 ° C., the balance of viscoelastic properties is deteriorated, and it becomes difficult to obtain the effect of reducing the heat generation. Further, when the Tg of the modified conjugated diene polymer rubber is lower than -32 ° C, the Tg of the modified conjugated diene polymer rubber becomes low, and the loss tangent of the dynamic viscoelastic property at 0 ° C, which is an index of grip on a wet road. (Tan δ) decreases. The Tg of the modified conjugated diene polymer rubber is measured by a differential scanning calorimetry (DSC) under a temperature increase rate condition of 20 ° C./min, and is set as the temperature at the midpoint of the transition region. When the modified conjugated diene polymer rubber is an oil-extended product, the glass transition temperature of the modified conjugated diene polymer rubber in a state not containing an oil-extended component (oil) is used.

  The modified conjugated diene polymer rubber can improve the molding processability of the rubber composition by oil spreading. The amount of oil extended is not particularly limited, but is preferably 25 parts by weight or less with respect to 100 parts by weight of the modified conjugated diene polymer rubber. When the oil extended amount of the modified conjugated diene polymer rubber exceeds 25 parts by weight, the degree of freedom in composition design is reduced when an oil, a softener, a tackifier or the like is added to the rubber composition.

  In the present invention, the content of the modified conjugated diene polymer rubber is 35 to 95% by weight, preferably 40 to 90% by weight, in 100% by weight of the diene rubber. When the content of the modified conjugated diene polymer rubber is less than 35% by weight in the diene rubber, the affinity with silica is deteriorated and the dispersibility of silica cannot be improved. On the other hand, when the content of the modified conjugated diene polymer rubber exceeds 95% by weight, the Tg of the rubber composition increases, so that the wear resistance decreases.

  The rubber composition for a tire tread of the present invention can improve wear resistance while maintaining low rolling resistance and wet performance at a high level by containing a terminal-modified butadiene rubber. The amount of the terminal-modified butadiene rubber is 5 to 40% by weight, preferably 10 to 35% by weight, based on 100% by weight of the diene rubber. If the amount of the terminal-modified butadiene rubber is less than 5% by weight, rolling resistance and wear resistance cannot be improved. On the other hand, when the blending amount of the terminal-modified butadiene rubber exceeds 40% by weight, the Tg of the rubber composition becomes low, so that the wet grip property cannot be improved. As the terminal-modified butadiene rubber, those usually used for tire rubber compositions may be used.

  In the present invention, the terminal-modified butadiene rubber is a butadiene rubber in which both or one of its molecular ends is modified with a functional group having reactivity with a silanol group on the silica surface. The functional group that reacts with the silanol group is preferably a polyorganosiloxane group, a hydroxyl group-containing polyorganosiloxane structure, an alkoxysilyl group, a hydroxyl group, an aldehyde group, a carboxyl group, an amino group, an imino group, an epoxy group, an amide group, Examples thereof include at least one selected from a thiol group and an ether group. Of these, a polyorganosiloxane group is more preferable. Moreover, it can have the polyorganosiloxane group which the modified conjugated diene polymer rubber described above has.

  In the rubber composition of the present invention, the terminal-modified butadiene rubber has a vinyl unit content of 20% by weight or less, preferably 10 to 15% by weight. When the vinyl unit content of the terminal-modified butadiene rubber exceeds 20% by weight, the Tg of the rubber composition becomes high, so that the rolling resistance and the wear resistance cannot be sufficiently improved. The vinyl unit content of the terminal-modified butadiene rubber is measured by infrared spectroscopic analysis (Hampton method). The increase or decrease in the vinyl unit content in the terminal-modified butadiene rubber can be appropriately adjusted by a usual method such as a catalyst.

  The method for preparing the terminal-modified butadiene rubber used in the rubber composition of the present invention is not particularly limited, and a normal production method can be applied. A suitable modified BR production method includes, for example, a method of preparing a butadiene monomer by polymerizing an organic active metal compound as an initiator in a hydrocarbon solvent. As a hydrocarbon solvent, what is necessary is just a solvent used normally, for example, cyclohexane, n-hexane, benzene, toluene etc. are illustrated. As the organic active metal catalyst to be used, an organic alkali metal compound is preferably used. For example, an organic monolithium compound such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, stilbenelithium; Organic polyvalent lithium compounds such as 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene; organic sodium compounds such as sodium naphthalene; organic potassium compounds such as potassium naphthalene Is mentioned. In addition, 3,3- (N, N-dimethylamino) -1-propyllithium, 3- (N, N-diethylamino) -1-propyllithium, 3- (N, N-dipropylamino) -1- Propyllithium, 3-morpholino-1-propyllithium, 3-imidazole-1-propyllithium and organolithium compounds in which these are chain-extended with 1 to 10 units of butadiene, isoprene or styrene can also be used. In the polymerization reaction, ethers such as diethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, 2,2-bis (2-oxolanyl) propane, and amines such as triethylamine and tetramethylethylenediamine are used for the purpose of adjusting the vinyl content. It is also possible to add the aprotic polar compound.

  In the present invention, the diene rubber other than the above-described modified conjugated diene polymer rubber and terminal-modified butadiene rubber can be blended as the rubber component. Other diene rubbers include, for example, natural rubber, isoprene rubber, non-terminally modified butadiene rubber, non-terminally modified solution polymerized styrene butadiene rubber (S-SBR), emulsion polymerized styrene butadiene rubber (E-SBR), Examples include butyl rubber and halogenated butyl rubber. Natural rubber, isoprene rubber, and emulsion-polymerized styrene butadiene rubber are preferable. Such diene rubbers can be used alone or as a plurality of blends. The content of the other diene rubber is 25% by weight or less, preferably 20% by weight or less, in 100% by weight of the diene rubber.

  The rubber composition for a tire tread of the present invention can further improve wet performance, particularly steering stability on a wet road surface, while maintaining low rolling resistance by blending an aromatic modified terpene resin. As the aromatic modified terpene resin, one having a softening point of 100 to 150 ° C., preferably 110 to 140 ° C. may be used. When the softening point of the aromatic modified terpene resin is less than 100 ° C., the effect of improving the wet performance cannot be sufficiently obtained. Moreover, when the softening point of aromatic modified terpene resin exceeds 150 degreeC, the dispersibility with respect to diene rubber will deteriorate, the grip performance on wet road surface will fall, and rubber strength will fall. In addition, the softening point of aromatic modified terpene resin shall be measured based on JISK6220-1 (ring ball method).

  The compounding amount of the aromatic modified terpene resin is preferably 3 to 40 parts by weight, more preferably 8 to 35 parts by weight with respect to 100 parts by weight of the diene rubber. If the blending amount of the aromatic modified terpene resin is less than 3 parts by weight, the effect of improving the wet grip performance cannot be sufficiently obtained. When the blending amount of the aromatic modified terpene resin exceeds 40 parts by weight, the low rolling resistance is deteriorated. Moreover, the adhesiveness of the rubber composition is increased, and the molding processability and handleability are deteriorated, for example, the rubber composition is in close contact with the molding roll.

  The aromatic modified terpene resin is obtained by polymerizing a terpene and an aromatic compound. Examples of terpenes include α-pinene, β-pinene, dipentene, and limonene. Examples of the aromatic compound include styrene, α-methylstyrene, vinyl toluene, indene and the like. Of these, a styrene-modified terpene resin is preferable as the aromatic-modified terpene resin. Such an aromatic modified terpene resin has good compatibility with the diene rubber, so that the tan δ at 0 ° C. of the rubber composition is increased and the wet grip performance is improved.

  The hydroxyl value of the aromatic modified terpene resin is preferably 30 KOHmg / g or less, more preferably 0 to 25 KOHmg / g. By setting the hydroxyl value of the aromatic modified terpene resin to 30 KOH mg / g or less, tan δ at 0 ° C. is increased and wet grip performance is improved. The hydroxyl value of the aromatic modified terpene resin is measured according to JIS K1557-1.

  In the present invention, 60 to 150 parts by weight of a filler containing 50% by weight or more of silica is added to 100 parts by weight of the diene rubber. By making the compounding quantity of a filler into such a range, the low rolling resistance and wet performance of a rubber composition can be balanced at a higher level. When the blending amount of the filler is less than 60 parts by weight, wet grip performance and wear resistance are lowered. When the blending amount of the filler exceeds 150 parts by weight, the heat generation becomes large and the low rolling resistance deteriorates.

  The content of silica in 100% by weight of the filler is 50% by weight or more. By setting the content of silica in the filler in such a range, the low rolling resistance and wet performance of the rubber composition can be balanced at a higher level. In particular, when the ratio of silica is less than 50% by weight, low rolling resistance and wet performance are lowered. In the present invention, the modified conjugated diene polymer rubber and the terminal-modified butadiene rubber are blended to increase the affinity with silica and improve the dispersibility, thereby further improving the effect of blending silica.

  As the silica, silica usually used in a rubber composition for a tire tread, for example, wet method silica, dry method silica, or surface-treated silica can be used.

  In the rubber composition of the present invention, it is preferable to blend a silane coupling agent with silica, so that the dispersibility of silica can be improved and the reinforcement with the diene rubber can be further enhanced. The silane coupling agent is preferably added in an amount of 3 to 20% by weight, more preferably 5 to 15% by weight, based on the amount of silica. When the compounding amount of the silane coupling agent is less than 3% by weight of the silica weight, the effect of improving the dispersibility of the silica cannot be sufficiently obtained. On the other hand, when the silane coupling agent exceeds 20% by weight, the silane coupling agents are polymerized with each other, and a desired effect cannot be obtained.

  Although it does not restrict | limit especially as a silane coupling agent, A sulfur containing silane coupling agent is preferable, for example, bis- (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide. , 3-trimethoxysilylpropylbenzothiazole tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, and the like.

  The rubber composition for a tire tread of the present invention can contain other fillers other than silica. Examples of fillers other than silica include carbon black, clay, mica, talc, calcium carbonate, aluminum hydroxide, aluminum oxide, and titanium oxide. Of these, carbon black is preferred. By adding carbon black, the rubber strength can be increased. The content of carbon black is preferably 50% by weight or less, more preferably 0 to 30% by weight in 100% by weight of the filler. When the content of carbon black exceeds 50% by weight, rolling resistance is deteriorated.

  The tire tread rubber composition generally includes a vulcanization or crosslinking agent, a vulcanization accelerator, an anti-aging agent, a plasticizer, a processing aid, a liquid polymer, a thermosetting resin, and the like. Various compounding agents used can be blended. Such a compounding agent can be kneaded by a general method to form a rubber composition, which can be used for vulcanization or crosslinking. The compounding amounts of these compounding agents can be the conventional general compounding amounts as long as they do not contradict the purpose of the present invention. The rubber composition for a tire tread can be produced by mixing each of the above components using a known rubber kneading machine such as a Banbury mixer, a kneader, or a roll.

  The rubber composition for a tire tread of the present invention can be suitably used for a pneumatic tire. A pneumatic tire using this rubber composition in the tread portion can improve low rolling resistance, wet performance, and wear resistance to a level higher than the conventional level.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited to these Examples.

  25 common rubber composition for tire treads (Examples 1 to 6, Comparative Examples 1 to 19) having the composition shown in Tables 1 to 3 and components other than sulfur and vulcanization accelerators are shown in Table 4 At the same time, it was prepared by adding sulfur and a vulcanization accelerator to a master batch which was kneaded and discharged at 160 ° C. for 5 minutes with a 1.8 L closed mixer and kneaded with an open roll. In Tables 1 to 3, the blending amount of SBR containing oil-extended oil is described, and the net blending amount of each rubber component is described in parentheses. The description of the silica ratio in the filler means the content (% by weight) of silica in 100% by weight of the filler composed of silica and carbon black. Moreover, the quantity of the common compounding component shown in Table 4 means that it mix | blended with the weight part with respect to 100 weight part (net quantity) of the diene rubber described in Tables 1-3.

  Twenty-five types of rubber compositions for tire treads thus obtained were press vulcanized at 160 ° C. for 20 minutes in a mold having a predetermined shape to prepare a vulcanized rubber sample. tan δ) and abrasion resistance were measured.

Rolling resistance: tan δ (60 ° C)
The rolling resistance of the obtained vulcanized rubber sample was evaluated by loss tangent tan δ (60 ° C.), which is known to be an index of rolling resistance. Tan δ (60 ° C.) was measured using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho under the conditions of an initial strain of 10%, an amplitude of ± 2%, a frequency of 20 Hz, and a temperature of 60 ° C. The obtained results are shown in Tables 1 to 3 as an index with Comparative Example 1 as 100. As this index is smaller, particularly when the index is 98 or less, tan δ (60 ° C.) is small and heat generation is low, which means that when a pneumatic tire is made, rolling resistance is small and fuel efficiency is excellent.

Abrasion resistance Lambone wear of the obtained vulcanized rubber sample was measured according to JIS K6264-2 using a lambone wear tester manufactured by Iwamoto Seisakusho under the conditions of a temperature of 20 ° C., a load of 15 N, and a slip ratio of 50%. It was measured. The obtained results are shown in Tables 1 to 3 as an index with Comparative Example 1 as 100. The larger the index, the more excellent the abrasion resistance, especially when the index is 102 or more.

  Next, four pneumatic tires having a tire size of 245 / 50R18 were manufactured by using the above-described 25 kinds of tire tread rubber compositions in the tread portion. The wet performance of the obtained 25 types of pneumatic tires was evaluated by the following method.

Wet performance The obtained pneumatic tire is assembled to a wheel with a rim size of 18 x 8 JJ, mounted on a domestic 2.5 liter class test vehicle, and a test course of 2.6 km per lap consisting of a wet road surface under the condition of air pressure 230 kPa. The vehicle was run, and the handling stability at that time was scored by a sensitive evaluation by three expert panelists. The obtained results are shown in Tables 1 to 3 as an index with Comparative Example 1 as 100. It means that the wet steering stability on a wet road surface is excellent when the index is larger, particularly when the index is 102 or more.

  In addition, the kind of raw material used in Tables 1-3 is shown below.

Modified S-SBR1: modified conjugated diene polymer rubber, aromatic vinyl unit content 42% by weight, vinyl unit content 32% by weight, weight average molecular weight (Mw) 750,000, Tg −25 ° C. An oil-extended product containing 25 parts by weight of an oil component per 100 parts by weight of a rubber component, and a terminal-modified solution-polymerized styrene butadiene rubber prepared by the following production method.

[Production Method of Modified S-SBR1]
Into an autoclave reactor with a nitrogen content of 10 L, cyclohexane 4533 g, styrene 338.9 g (3.254 mol), butadiene 468.0 g (8.652 mol), isoprene 20.0 g (0.294 mol) and N, N, N ', N'-tetramethylethylenediamine 0.189 mL (1.271 mmol) was charged and stirring was started. After the temperature of the contents in the reaction vessel was adjusted to 50 ° C., 5.061 mL (7.945 mmol) of n-butyllithium was added. After the polymerization conversion rate reached almost 100%, 12.0 g of isoprene was further added and reacted for 5 minutes, and then 0.281 g (0.318 mmol) of a 40 wt% toluene solution of 1,6-bis (trichlorosilyl) hexane. ) Was added and allowed to react for 30 minutes. Furthermore, 18.3 g (0.318 mmol) of a 40 wt% xylene solution of polyorganosiloxane A shown below was added and reacted for 30 minutes. 0.5 mL of methanol was added and stirred for 30 minutes. A small amount of an anti-aging agent (Irganox 1520, manufactured by BASF) is added to the obtained polymer solution, and 25 parts of Fukkoreramic 30 (manufactured by Shin Nippon Oil Co., Ltd.) is added as an extension oil, followed by steam stripping. The solid rubber was recovered. The obtained solid rubber was dehydrated with a roll and dried in a dryer to obtain modified S-SBR1.

Polyorganosiloxane A; a polyorganosiloxane having the structure of the general formula (I), wherein m = 80, n = 0, k = 120, X ¹ , X ⁴ , R ^{1 to} R ³ , R ^{5 to} R Polyorganosiloxane, wherein ⁸ is a methyl group (—CH ₃ ) and X ² is a hydrocarbon group represented by the following formula (VIII)

Modified S-SBR2: modified conjugated diene polymer rubber, aromatic vinyl unit content 42% by weight, vinyl unit content 32% by weight, weight average molecular weight (Mw) 750,000, Tg −25 ° C. An oil-extended product containing 25 parts by weight of an oil component per 100 parts by weight of a rubber component, and a terminal-modified solution-polymerized styrene butadiene rubber prepared by the following production method.

[Method for producing modified S-SBR2]
Into an autoclave reactor with a nitrogen content of 10 L, cyclohexane 4550 g, styrene 341.1 g (3.275 mol), butadiene 459.9 g (8.502 mol), isoprene 20.0 g (0.294 mol) and N, N, N ', N'-tetramethylethylenediamine (0.190 mL, 1.277 mmol) was charged and stirring was started. After the temperature of the contents in the reaction vessel was adjusted to 50 ° C., 5.062 mL (7.946 mmol) of n-butyllithium was added. After the polymerization conversion reached almost 100%, 12.0 g of isoprene was further added and reacted for 5 minutes, and then 0.283 g (0.320 mmol) of a 40 wt% toluene solution of 1,6-bis (trichlorosilyl) hexane. ) Was added and allowed to react for 30 minutes. Furthermore, 19.0 g (0.330 mmol) of a 40 wt% xylene solution of polyorganosiloxane B shown below was added and reacted for 30 minutes. 0.5 mL of methanol was added and stirred for 30 minutes. A small amount of an anti-aging agent (Irganox 1520, manufactured by BASF) is added to the obtained polymer solution, and 25 parts of FUKKOR ERAMIC 30 (manufactured by Shin Nippon Oil Co., Ltd.) is added as an extension oil, followed by steam stripping. The solid rubber was recovered. The obtained solid rubber was dehydrated with a roll and dried in a dryer to obtain modified S-SBR2.

Polyorganosiloxane B; a polyorganosiloxane having the structure of the general formula (II), wherein R ^{9 to} R ¹⁶ are each a methyl group (—CH ₃ ), and X ^{5 to} X ⁸ are each a formula (VIII). Polyorganosiloxane which is a hydrocarbon group represented

Modified S-SBR3: modified conjugated diene polymer rubber, aromatic vinyl unit content 41 wt%, vinyl unit content 32 wt%, weight average molecular weight (Mw) 750,000, Tg −25 ° C. An oil-extended product containing 25 parts by weight of an oil component per 100 parts by weight of a rubber component, and a terminal-modified solution-polymerized styrene butadiene rubber prepared by the following production method.

[Production Method of Modified S-SBR3]
Into an autoclave reactor having a nitrogen content of 10 L, cyclohexane 4542 g, styrene 339.2 g (3.257 mol), butadiene 462.8 g (8.556 mol), isoprene 20.0 g (0.294 mol) and N, N, N ', N'-tetramethylethylenediamine (0.188 mL, 1.264 mmol) was charged and stirring was started. After the temperature of the contents in the reaction vessel was 50 ° C., 5.059 mL (7.942 mmol) of n-butyllithium was added. After the polymerization conversion reached almost 100%, 12.0 g of isoprene was further added and reacted for 5 minutes, and then 0.283 g (0.320 mmol) of a 40 wt% toluene solution of 1,6-bis (trichlorosilyl) hexane. ) Was added and allowed to react for 30 minutes. Further, 19.2 g (0.333 mmol) of a 40 wt% xylene solution of polyorganosiloxane C shown below was added and reacted for 30 minutes. 0.5 mL of methanol was added and stirred for 30 minutes. A small amount of an anti-aging agent (Irganox 1520, manufactured by BASF) is added to the obtained polymer solution, and 25 parts of FUKKOR ERAMIC 30 (manufactured by Shin Nippon Oil Co., Ltd.) is added as an extension oil, followed by steam stripping. The solid rubber was recovered. The obtained solid rubber was dehydrated with a roll and dried in a dryer to obtain modified S-SBR3.

Polyorganosiloxane C; a polyorganosiloxane having the structure of the general formula (III), wherein s = 2, R ^{17 to} R ¹⁹ are each a methyl group (—CH ₃ ), and X ^{9 to} X ¹¹ are each the above formula. Polyorganosiloxane which is a hydrocarbon group represented by (VIII)

Modified S-SBR4: terminal-modified solution polymerized styrene butadiene rubber, aromatic vinyl unit content 30% by weight, vinyl unit content 61% by weight, weight average molecular weight (Mw) 590,000, Tg -25 ° C, Nippon Zeon NSOL 530, an oil exhibition containing 20 parts by weight of oil for 100 parts by weight of rubber component

Modified S-SBR5: terminal-modified solution polymerized styrene butadiene rubber, aromatic vinyl unit content 37% by weight, vinyl unit content 43% by weight, weight average molecular weight (Mw) 1.2 million, Tg -27 ° C, Asahi Kasei Chemicals Toughden E581, an oil exhibition containing 37.5 parts by weight of oil for 100 parts by weight of rubber component

Modified S-SBR6: terminal-modified solution polymerized styrene butadiene rubber, aromatic vinyl unit content 20% by weight, vinyl unit content 67% by weight, weight average molecular weight (Mw) 510,000, Tg −25 ° C. Nipol NS616 manufactured by Nippon Zeon Co., Ltd.

Modified S-SBR7: terminal-modified solution-polymerized styrene butadiene rubber, aromatic vinyl unit content 16% by weight, vinyl unit content 34% by weight, weight average molecular weight (Mw) 610,000, Tg −60 ° C. Nipol NS612, non-oil exhibition by Nippon Zeon

Modified S-SBR8: Modified conjugated diene polymer rubber, aromatic vinyl unit content 34% by weight, vinyl unit content 34% by weight, weight average molecular weight (Mw) 760,000, Tg −33 ° C., An oil-extended product containing 25 parts by weight of an oil component per 100 parts by weight of a rubber component, and a terminal-modified solution-polymerized styrene butadiene rubber prepared by the following production method.

[Production Method of Modified S-SBR8]
A nitrogen-substituted autoclave reactor having an internal volume of 10 L was charged with 4541 g of cyclohexane, 277.6 g (2.665 mol) of styrene, 523.1 g (9.671 mol) of butadiene, 20.0 g (0.294 mol) of isoprene and N, N, N ', N'-tetramethylethylenediamine (0.175 mL, 1.178 mmol) was charged and stirring was started. After the temperature of the contents in the reaction vessel was 50 ° C., 4.984 mL (7.824 mmol) of n-butyllithium was added. After the polymerization conversion reached almost 100%, 12.0 g of isoprene was further added and reacted for 5 minutes, and then 0.273 g (0.327 mmol) of a 40 wt% toluene solution of 1,6-bis (trichlorosilyl) hexane. ) Was added and allowed to react for 30 minutes. Furthermore, 18.1 g (0.314 mmol) of the 40 wt% xylene solution of polyorganosiloxane A described above was added and reacted for 30 minutes. 0.5 mL of methanol was added and stirred for 30 minutes. A small amount of an anti-aging agent (Irganox 1520, manufactured by BASF) is added to the obtained polymer solution, and 25 parts of FUKKOR ERAMIC 30 (manufactured by Shin Nippon Oil Co., Ltd.) is added as an extension oil, followed by steam stripping. The solid rubber was recovered. The obtained solid rubber was dehydrated with a roll and dried in a drier to obtain modified S-SBR8.

Modified S-SBR9: Modified conjugated diene polymer rubber, aromatic vinyl unit content 49% by weight, vinyl unit content 28% by weight, weight average molecular weight (Mw) 710,000, Tg −17 ° C., An oil-extended product containing 25 parts by weight of an oil component per 100 parts by weight of a rubber component, and a terminal-modified solution-polymerized styrene butadiene rubber prepared by the following production method.

[Production Method of Modified S-SBR9]
An autoclave reactor with a nitrogen content of 10 L was charged with 4536 g of cyclohexane, 401.0 g (3.850 mol) of styrene, 392.0 g (7.247 mol) of butadiene, 20.0 g (0.294 mol) of isoprene and N, N, N ′, N′-tetramethylethylenediamine (0.201 mL, 1.352 mmol) was charged, and stirring was started. After the temperature of the contents in the reaction vessel was adjusted to 50 ° C., 5.141 mL (8.071 mmol) of n-butyllithium was added. After the polymerization conversion reached almost 100%, 12.0 g of isoprene was further added and reacted for 5 minutes, and then 0.279 g (0.320 mmol) of a 40 wt% toluene solution of 1,6-bis (trichlorosilyl) hexane. ) Was added and allowed to react for 30 minutes. Further, 18.6 g (0.323 mmol) of a 40 wt% xylene solution of polyorganosiloxane A described above was added and reacted for 30 minutes. 0.5 mL of methanol was added and stirred for 30 minutes. A small amount of an anti-aging agent (Irganox 1520, manufactured by BASF) is added to the obtained polymer solution, and 25 parts of FUKKOR ERAMIC 30 (manufactured by Shin Nippon Oil Co., Ltd.) is added as an extension oil, followed by steam stripping. The solid rubber was recovered. The obtained solid rubber was dehydrated with a roll and dried in a drier to obtain modified S-SBR9.

Modified S-SBR10: Modified conjugated diene polymer rubber, aromatic vinyl unit content 41% by weight, vinyl unit content 17% by weight, weight average molecular weight (Mw) 740,000, Tg -37 ° C, An oil-extended product containing 25 parts by weight of an oil component per 100 parts by weight of a rubber component, and a terminal-modified solution-polymerized styrene butadiene rubber prepared by the following production method.

[Method for producing modified S-SBR10]
Into an autoclave reactor having a nitrogen content of 10 L, cyclohexane 4542 g, styrene 339.2 g (3.257 mol), butadiene 462.8 g (8.556 mol), isoprene 20.0 g (0.294 mol) and N, N, 0.0376 mL (0.253 mmol) of N ′, N′-tetramethylethylenediamine was charged and stirring was started. After the temperature of the contents in the reaction vessel was 50 ° C., 5.059 mL (7.942 mmol) of n-butyllithium was added. After the polymerization conversion reached almost 100%, 12.0 g of isoprene was further added and reacted for 5 minutes, and then 0.280 g (0.331 mmol) of a 40 wt% toluene solution of 1,6-bis (trichlorosilyl) hexane. ) Was added and allowed to react for 30 minutes. Further, 18.8 g (0.326 mmol) of a 40 wt% xylene solution of polyorganosiloxane A described above was added and reacted for 30 minutes. 0.5 mL of methanol was added and stirred for 30 minutes. A small amount of an anti-aging agent (Irganox 1520, manufactured by BASF) is added to the obtained polymer solution, and 25 parts of FUKKOR ERAMIC 30 (manufactured by Shin Nippon Oil Co., Ltd.) is added as an extension oil, followed by steam stripping. The solid rubber was recovered. The obtained solid rubber was dehydrated with a roll and dried in a drier to obtain modified S-SBR10.

Modified S-SBR11: Modified conjugated diene polymer rubber, aromatic vinyl unit content 39% by weight, vinyl unit content 40% by weight, weight average molecular weight (Mw) 750,000, Tg −21 ° C. An oil-extended product containing 25 parts by weight of an oil component per 100 parts by weight of a rubber component, and a terminal-modified solution-polymerized styrene butadiene rubber prepared by the following production method.

[Production Method of Modified S-SBR11]
Into an autoclave reactor with a nitrogen content of 10 L, cyclohexane 4543 g, styrene 319.8 g (3.071 mol), butadiene 480.1 g (8.876 mol), isoprene 20.0 g (0.294 mol) and N, N, N ', N'-tetramethylethylenediamine (0.217 mL, 1.462 mmol) was charged and stirring was started. After the temperature of the contents in the reaction vessel was adjusted to 50 ° C., 5.141 mL (8.0714 mmol) of n-butyllithium was added. After the polymerization conversion reached almost 100%, 12.0 g of isoprene was further added and reacted for 5 minutes, and then 0.279 g (0.320 mmol) of a 40 wt% toluene solution of 1,6-bis (trichlorosilyl) hexane. ) Was added and allowed to react for 30 minutes. Further, 18.6 g (0.323 mmol) of a 40 wt% xylene solution of polyorganosiloxane A described above was added and reacted for 30 minutes. 0.5 mL of methanol was added and stirred for 30 minutes. A small amount of an anti-aging agent (Irganox 1520, manufactured by BASF) is added to the obtained polymer solution, and 25 parts of FUKKOR ERAMIC 30 (manufactured by Shin Nippon Oil Co., Ltd.) is added as an extension oil, followed by steam stripping. The solid rubber was recovered. The obtained solid rubber was dehydrated with a roll and dried in a drier to obtain modified S-SBR11.

S-SBR: unmodified solution polymerized styrene butadiene rubber, aromatic vinyl unit content 41% by weight, vinyl unit content 25% by weight, weight average molecular weight (Mw) 1,010,000, Tg -30 ° C, Dow Chemical's SLR6430, an oil-extended product containing 37.5 parts by weight of oil with respect to 100 parts by weight of the rubber component. E-SBR: emulsion-polymerized styrene butadiene rubber, aromatic vinyl unit content 35% by weight, vinyl unit content Is 13 wt%, weight average molecular weight (Mw) is 760,000, Tg is −28 ° C., Nipol 1739 manufactured by Nippon Zeon Co., Ltd. Unmodified butadiene rubber having a unit content of 1% by weight, Nipol BR1220 manufactured by Nippon Zeon Co., Ltd.

-Modified BR1: butadiene rubber modified with a polyorganosiloxane group at the end, and prepared by the following production method so that the vinyl unit content was 12% by weight.

[Production Method of Modified BR1]
Into an autoclave reactor with an internal volume of 10 L purged with nitrogen, 3147 g of cyclohexane and 498.4 g (9.215 mol) of butadiene were charged, and stirring was started. After the temperature of the contents in the reaction vessel was 50 ° C., 3.054 mL (4.856 mmol) of n-butyllithium was added. After the polymerization conversion reached 100%, 0.294 g (0.330 mmol) of a 40.3% by weight toluene solution of the polyorganosiloxane A was added and stirred for 1 hour. Furthermore, 0.5 mL of methanol was added and stirred for 30 minutes. A small amount of an antioxidant (Irganox 1520) was added to the resulting polymer solution, and the solvent was removed by concentration under reduced pressure. The polymer was coagulated and washed in methanol, and then dried to obtain a solid polymer (modified BR1).

Modified BR2: butadiene rubber modified with a polyorganosiloxane group at the end, prepared by the following production method so that the vinyl unit content was 25% by weight.

[Method for producing modified BR2]
A modified BR2 was produced by the same production method as the modified BR1 except that 0.094 mL (0.623 mmol) of N, N, N ′, N′-tetramethylethylenediamine was added simultaneously with the addition of the monomer.
Silica: silica, Zeosil 1165MP manufactured by Rhodia
・ CB: Carbon black, Toast Carbon Co., Ltd. Seest KH
Terpene resin 1: aromatic modified terpene resin having a softening point of 125 ° C., YS resin TO-125 manufactured by Yashara Chemical Co., Ltd.
-Terpene resin 2: Aromatic modified terpene resin having a softening point of 85 ° C, YS resin TO-85 manufactured by Yashara Chemical Co., Ltd.
Coupling agent: Si69 manufactured by Evonik Degussa
・ Oil: Showa Shell Sekiyu Extract 4 S

Moreover, the kind of raw material used in the common composition of Table 4 is shown below.
・ Stearic acid: NOF beads stearic acid YR
Anti-aging agent: Santoflex 6PPD manufactured by Flexis
・ Wax: Sunnock manufactured by Ouchi Shinsei Chemical Co., Ltd. ・ Zinc flower: Zinc oxide 3 types manufactured by Shodo Chemical Industry Co., Ltd. ・ Sulfur: Fine powder sulfur containing Jinhua seal oil manufactured by Tsurumi Chemical Industry Co., Ltd. , Nouchira CZ-G manufactured by Ouchi Shinsei Chemical Co., Ltd.
・ Vulcanization accelerator 2: Vulcanization accelerator DPG, Noxeller D manufactured by Ouchi Shinsei Chemical Co., Ltd.

  As is clear from Table 1, it was confirmed that the rubber compositions for tire treads of Examples 1 to 6 were improved in low rolling resistance (tan δ at 60 ° C.), wet performance and wear resistance. In the rubber composition of Comparative Example 2, since BR1 is not terminal-modified, improvement in wear resistance is not sufficient.

  As is apparent from Table 2, the rubber composition of Comparative Example 3 has a modified S-SBR4 having an aromatic vinyl unit content of less than 38% by weight, a vinyl unit content of more than 35% by weight, and a weight average molecular weight of 600,000. Therefore, rolling resistance and wear resistance cannot be improved sufficiently. In the rubber composition of Comparative Example 4, the modified S-SBR5 has an aromatic vinyl unit content of less than 38% by weight, a vinyl unit content of more than 35% by weight, and a weight average molecular weight of more than 1 million. Wet performance cannot be improved sufficiently. The rubber composition of Comparative Example 5 has a modified S-SBR6 having an aromatic vinyl unit content of less than 38% by weight, a vinyl unit content of more than 35% by weight, and a weight average molecular weight of less than 600,000. Rolling resistance and wear resistance deteriorate. Since the rubber composition of Comparative Example 6 was blended with unmodified S-SBR instead of the modified conjugated diene polymer rubber, rolling resistance and wet performance deteriorate. In the rubber composition of Comparative Example 7, since the aromatic vinyl unit content of the modified S-SBR7 is less than 38% by weight and the vinyl unit content is less than 20% by weight, the wet performance is deteriorated.

  In the rubber composition of Comparative Example 8, since the aromatic vinyl unit content of the modified S-SBR8 is less than 38% by weight, the wet performance is deteriorated and the wear resistance cannot be sufficiently improved. In the rubber composition of Comparative Example 9, since the aromatic vinyl unit content of the modified S-SBR9 exceeds 48% by weight, the rolling resistance cannot be sufficiently improved. In the rubber composition of Comparative Example 10, since the vinyl unit content of the modified S-SBR10 is less than 20% by weight, the wet performance is deteriorated. In the rubber composition of Comparative Example 11, since the vinyl unit content of the modified S-SBR11 exceeds 35% by weight, the rolling resistance cannot be sufficiently improved.

  As is apparent from Table 3, the rubber composition of Comparative Example 12 has a modified BR1 content of less than 5% by weight, so that rolling resistance and wear resistance are deteriorated. In the rubber composition of Comparative Example 13, since the blending amount of the modified BR1 exceeds 40% by weight, the wet performance is deteriorated. In the rubber composition of Comparative Example 14, since the blending amount of the modified S-SBR1 is less than 35% by weight, the rolling resistance is deteriorated and the wear resistance cannot be sufficiently improved.

  In the rubber composition of Comparative Example 15, since the total amount of the filler is less than 60 parts by weight, the wet performance and the wear resistance are deteriorated. In the rubber composition of Comparative Example 16, since the silica ratio in 100% by weight of the total filler is less than 50% by weight, rolling resistance and wet performance are deteriorated. In the rubber composition of Comparative Example 17, since the blending amount of the terpene resin 1 is less than 3 parts by weight, the wet performance is deteriorated. The rubber composition of Comparative Example 18 cannot sufficiently improve the wet performance because the softening point of the terpene resin 2 is less than 100 ° C. In the rubber composition of Comparative Example 19, since the vinyl unit content of the modified BR2 exceeds 20% by weight, the rolling resistance and wear resistance cannot be sufficiently improved.

Claims (5)

  3 to 40 parts by weight of an aromatic modified terpene resin and 60 parts by weight of a filler based on 100 parts by weight of a diene rubber containing 35 to 95% by weight of a modified conjugated diene polymer rubber and 5 to 40% by weight of a terminal-modified butadiene rubber. And 150 parts by weight of the filler, the filler contains 50% by weight or more of silica, and the modified conjugated diene polymer rubber is conjugated diene monomer using an organic active metal compound as an initiator in a hydrocarbon solvent. Terminal modification by reacting an active conjugated diene polymer chain obtained by copolymerization of a monomer and an aromatic vinyl monomer with at least one compound having a functional group capable of reacting with the active terminal of the polymer chain And the terminal modified group contains a functional group having an interaction with silica, and the modified vinyl conjugated diene polymer rubber has an aromatic vinyl unit content of 38 to 48% by weight and contains a vinyl unit. Is 20 to 35% by weight, the weight average molecular weight is 600,000 to 1,000,000, the vinyl unit content of the terminal-modified butadiene rubber is 20% by weight or less, and the softening point of the aromatic modified terpene resin is 100 to 100%. A rubber composition for a tire tread, characterized by being 150 ° C.   The tire tread rubber composition according to claim 1, wherein the terminal-modified butadiene rubber has a polyorganosiloxane group.   The rubber composition for a tire tread according to claim 1 or 2, wherein the aromatic modified terpene resin is a terpene resin modified with styrene. The compound having a functional group capable of reacting with the active terminal of the active conjugated diene polymer chain contains at least one polyorganosiloxane compound selected from the following general formulas (I) to (III): The rubber composition for a tire tread according to claim 1, 2 or 3.

(In the above formula (I), R ^{1 to} R ⁸ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same or different from each other. X ¹ and X ⁴ are the active conjugated diene polymer chain groups having a functional group capable of reacting with the active terminal of an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon atoms,, X ¹ and X ⁴ may be the same as or different from each other, X ² is a group having a functional group that reacts with the active end of the active conjugated diene polymer chain, and X ³ is an alkylene glycol of 2 to 20 It is a group containing a repeating unit, and a part of X ³ may be a group derived from a group containing a repeating unit of 2 to 20 alkylene glycol, m is an integer of 3 to 200, and n is 0 to 0. 200 is an integer, and k is an integer of 0 to 200.)

(In the above formula (II), R ^{9 to} R ¹⁶ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same as or different from each other. ^{5 to} X ⁸ are groups having a functional group that reacts with the active terminal of the active conjugated diene polymer chain.

(In the above formula (III), R ^{17 to} R ¹⁹ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same as or different from each other. ^{9 to} X ¹¹ are groups having a functional group that reacts with the active end of the active conjugated diene polymer chain, and s is an integer of 1 to 18.)   The pneumatic tire using the rubber composition for tire treads in any one of Claims 1-4.