JP2008001743A - Tread rubber composition and tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a tread rubber composition, which improves driving stability and braking properties on a wet road surface while significantly reducing tire rolling resistance. <P>SOLUTION: The tread rubber composition is obtained by mixing 100 parts by mass of a rubber component (A) containing at least a modified conjugated diene-based polymer having one or more functional group containing nitrogen in the molecule with 10-200 parts by mass of silica (B), 1-30 parts by mass a sulfur-containing silane compound (C) of specific structure and a compound (D) of specific structure having a reactive group to the rubber component and an adsorption group to silica. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rubber composition for a tread and a tire using the rubber composition, and in particular, a tire tread capable of improving steering stability and braking performance on a wet road surface while greatly reducing rolling resistance. The present invention relates to a rubber composition.

  Generally, among many fillers used in rubber compositions, silica is known to be able to lower the rolling resistance of the tire and improve the braking performance on the wet road surface of the tire as compared with carbon black. . However, in recent years, in connection with the movement of global carbon dioxide emission regulations due to the increasing interest in environmental issues, in addition to the increasing demand for automobile fuel efficiency, the safety of driving automobiles has increased. In order to further improve the tire, the rubber composition in which the silica in the filler occupies 70% or more is used for the tread of the tire, so that the rolling resistance of the tire is greatly reduced, while the driving stability and the braking performance on the wet road surface are improved. There is a need for technology that can greatly improve.

  In the above silica compounded rubber composition, as a method for reducing the rolling resistance of the tire, a method of reducing the compounding amount of the filler is known, but if the compounding amount of the filler is decreased, the elastic modulus of the rubber composition is reduced. Therefore, when such a rubber composition is used for a tread of a tire, there is a problem that steering stability of the tire is deteriorated.

  In addition, it is known that the rolling resistance of the tire can be reduced by lowering the glass transition temperature of the rubber component of the rubber composition used for the tread. In this case, however, the braking performance on the wet road surface of the tire is deteriorated at the same time. There is a problem of end.

  Furthermore, in recent years, a modified polymer has been developed in which the end of the polymer is easily reacted with a silane coupling agent. However, when the modified polymer is used as a rubber component of a rubber composition, the elastic modulus of the rubber composition decreases. There is a problem that the steering stability of the tire deteriorates.

  On the other hand, JP-A-2003-176378 (Patent Document 1) uses a compound having at least one reactive group a for a rubber component and two or more adsorbing groups b for an inorganic filler in the same molecule. Thus, a rubber composition in which the dispersibility of an inorganic filler such as silica in a conjugated diene rubber is improved to improve the storage elastic modulus is disclosed.

JP 2003-176378 A

  However, in the above prior art, there is a problem that, when trying to reduce the rolling resistance of the tire, the steering stability and the braking performance on a wet road surface are lowered at the same time.

  Accordingly, an object of the present invention is to solve the problems of the prior art described above, and to improve the steering stability and the braking performance on wet road surfaces while greatly reducing the rolling resistance of the tire, the rubber composition for a tread. Is to provide.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have found that a rubber composition containing silica further has a sulfur-containing silane compound having a specific structure, and a compound having a reactive group for a rubber component and an adsorption group for silica. In addition, by using a modified conjugated diene polymer having one or more functional groups containing nitrogen in the molecule as a rubber component, the steering stability and wetness of a tire in which the silica-containing rubber composition is applied to a tread It has been found that rolling resistance can be greatly reduced while improving braking performance on the road surface, and the present invention has been completed.

That is, the rubber composition for a tread of the present invention is
For 100 parts by mass of rubber component (A) containing at least a modified conjugated diene polymer having one or more functional groups containing nitrogen in the molecule,
10 to 200 parts by mass of silica (B),
The following average composition formula (I):
_{^{(R 1 O) 3-p}} (R 2) p Si-R 3 -S m -R 4 -S m -R 3 -Si (R 2) p (OR 1) 3-p ··· (I)
[Wherein R ¹ and R ² are each a monovalent hydrocarbon group having 1 to 4 carbon atoms, R ³ is a divalent hydrocarbon group having 1 to 15 carbon atoms, p is an integer of 0 to 2, m is The average value is 1 or more and less than 4, R ⁴ is represented by the following general formulas (II), (III) and (IV):
S-R ⁵ -S (II)
R ⁶ -S _x -R ⁷ (III)
^{_{R 8 -S y -R 9 -S z}} -R 10 ··· (IV)
(In the formula, R ^{5 to} R ¹⁰ are linear or branched divalent hydrocarbon groups having 1 to 20 carbon atoms, divalent aromatic groups, divalent aromatic groups, or hetero elements other than sulfur and oxygen. Each of R ^{5 to} R ¹⁰ may be the same or different, and each of x, y, and z is an average value of 1 or more and less than 4). 1-30 parts by mass of a sulfur-containing silane compound (C) represented by
The following general formula (V):
HOOC—CH═CH—COO—R ¹¹ —CO—CH═CH—COOH (V)
[Wherein R ¹¹ is a group represented by the formula —R ¹² O—, where R ¹² is an alkylene group having 2 to 36 carbon atoms, an alkenylene group or a divalent aromatic hydrocarbon group}, A group represented by — (R ¹³ O) _s —, wherein R ¹³ is an alkylene group having 2 to 4 carbon atoms; s is a number of 1 to 60 indicating the average number of moles added of the oxyalkylene group} , A group represented by the formula —CH ₂ CH (OH) CH ₂ O— or a group represented by the formula — (R ¹⁴ O—COR ¹⁵ —COO—) _t R ¹⁴ O—, wherein R ¹⁴ has 2 carbon atoms -18 alkylene group, alkenylene group, divalent aromatic hydrocarbon group or group represented by-(R ¹⁶ O) _u R ^16- (wherein R ¹⁶ is an alkylene group having 2 to 4 carbon atoms; u in a number of 1 to 30 showing an average addition mol number of the oxyalkylene group); R ¹⁵ is an alkylene group having 2 to 18 carbon atoms, an alkenylene group or A divalent aromatic hydrocarbon group; t is characterized by being obtained by blending a compound represented by a is is a number of 1 to 30 as an average value} (D).

  In a preferred example of the rubber composition for a tread of the present invention, the compounding amount of the compound (D) represented by the general formula (V) is 0.5 to 20 parts by mass with respect to 100 parts by mass of the rubber component (A). It is.

  In another preferred embodiment of the rubber composition for a tread of the present invention, 10% by mass or more of the rubber component (A) is a modified conjugated diene polymer having one or more functional groups containing nitrogen in the molecule. is there.

  In another preferred embodiment of the rubber composition for a tread of the present invention, the modified conjugated diene polymer having one or more functional groups containing nitrogen in the molecule is a conjugated diene polymer having an active terminal. It is obtained by reacting the active terminal with a compound containing nitrogen in the molecule.

  In another preferred embodiment of the rubber composition for a tread of the present invention, the conjugated diene polymer is a copolymer of 1,3-butadiene and a vinyl aromatic compound or a homopolymer of 1,3-butadiene. is there. Here, the vinyl aromatic compound is preferably styrene. The modified conjugated diene polymer preferably has a weight average molecular weight (Mw) of 50,000 or more and less than 700,000, and a glass transition point (Tg) of 0 ° C. or less.

  In another preferred embodiment of the rubber composition for a tread of the present invention, the conjugated diene polymer is polymerized using an organic alkali metal compound. Here, the organic alkali metal compound is preferably a lithium compound.

  The tire of the present invention is characterized by using the rubber composition for a tread.

  According to the present invention, a modified conjugated diene polymer having at least one functional group containing nitrogen as a rubber component is used as a rubber component, and a sulfur-containing silane compound (C) having a specific structure and a reactive group for the rubber component and silica. A rubber composition for a tread with silica, which is compounded with a compound (D) having an adsorbing group for the rubber, and which can significantly reduce rolling resistance while improving the steering stability of a tire and the braking performance on a wet road surface. Can be provided.

  The present invention is described in detail below. The rubber composition for a tread according to the present invention comprises 10 parts by mass of silica (B) 10 with respect to 100 parts by mass of the rubber component (A) containing at least a modified conjugated diene polymer having one or more functional groups containing nitrogen in the molecule. ~ 200 parts by mass, 1 to 30 parts by mass of the sulfur-containing silane compound (C) represented by the above average composition formula (I), and the compound (D) represented by the above general formula (V) It is characterized by becoming.

  In the tread rubber composition of the present invention, the sulfur-containing silane compound (C) of the above formula (I) improves the dispersibility of the silica (B) in the rubber component (A), and the formula (I) The sulfur-containing silane compound (C) improves the reactivity between the silica (B) and the rubber component (A). In addition, since the compound (D) of the above formula (V) has one or more reactive groups for the rubber component (A), the compound (D) is excellent in compatibility with the rubber component (A) and has an adsorption group for the silica (B). Since it has two or more, it has excellent affinity with silica (B). Therefore, the rubber of the silica (B) is blended with the compound (D) of the formula (V) together with the silica (B) and the sulfur-containing silane compound (C) of the above formula (I) in the rubber component (A). The dispersibility and reinforcement in the component (A) are further improved, and the rubber composition can be made highly elastic. For this reason, rolling resistance can be reduced by using the rubber composition for treads of this invention, improving the steering stability on a dry road surface.

  In addition, since the hysteresis loss of the rubber composition is reduced, the braking performance on a wet road surface is usually reduced, but the modified conjugated diene polymer having one or more functional groups containing nitrogen in the molecule is Since the hysteresis loss in the low temperature region is increased while reducing the hysteresis loss in the high temperature region, the braking performance on the wet road surface can be improved while reducing the rolling resistance. Therefore, a modified conjugated having one or more functional groups containing nitrogen in the molecule and a sulfur-containing silane compound (C) of formula (I), a compound (D) of formula (V), and a silica-containing rubber composition A rubber composition for a tread that can significantly reduce rolling resistance while improving steering stability on a dry road surface and braking performance on a wet road surface by using in combination with a diene polymer. Is obtained.

  The rubber component (A) of the rubber composition for a tread of the present invention is a modified conjugated diene polymer having at least one functional group containing nitrogen in the molecule, and is 10% by mass or more of the rubber component. Is preferably a modified conjugated diene polymer having one or more functional groups containing nitrogen in the molecule. When the content of the modified conjugated diene polymer in the rubber component is less than 10% by mass, the effect of increasing the hysteresis loss in the low temperature region while reducing the hysteresis loss in the high temperature region of the rubber composition is small. Here, the rubber component is a polymer other than the modified conjugated diene polymer, such as natural rubber (NR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR). , Butyl rubber (IIR), ethylene-propylene copolymer, and the like.

  In the rubber composition of the present invention, the modified conjugated diene polymer used as a rubber component is not particularly limited as long as it has one or more functional groups containing nitrogen in the molecule. The modified conjugated diene polymer having one or more functional groups containing nitrogen is, for example, (1) after producing a conjugated diene polymer having an active end by polymerizing monomers, then the conjugated diene polymer. The compound is obtained by reacting a compound containing nitrogen as a modifier with the active terminal of (2) or polymerizing a monomer using a polymerization initiator having a nitrogen-containing functional group. In the modified conjugated diene polymer having one or more functional groups containing nitrogen, the conjugated diene polymer includes a copolymer of a conjugated diene compound and a vinyl aromatic compound, and a conjugated diene compound homopolymer. A copolymer of 1,3-butadiene and a vinyl aromatic compound, and a homopolymer of 1,3-butadiene are more preferable. Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, and the like. Among these, 1,3-butadiene is particularly preferable. On the other hand, examples of the vinyl aromatic compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene and 2,4,6-trimethylstyrene. Of these, styrene is preferred. These monomers may be used individually by 1 type, and may be used in combination of 2 or more type.

  When producing a conjugated diene polymer having an active end by anionic polymerization, an organic alkali metal compound is preferably used as a polymerization initiator, and a lithium compound is more preferably used. Examples of the lithium compound include hydrocarbyl lithium and lithium amide compounds. When hydrocarbyl lithium is used as the polymerization initiator, a polymer having a hydrocarbyl group at the polymerization initiation terminal and the other terminal being the active terminal is obtained. On the other hand, when a lithium amide compound is used as a polymerization initiator, a polymer having a nitrogen-containing functional group at the polymerization start terminal and an active terminal at the other terminal is obtained, and the polymer is modified with a nitrogen-containing modifier. Even if not, it can be used as the modified conjugated diene polymer in the present invention. In addition, the usage-amount of a polymerization initiator has the preferable range of 0.2-20 mmol per 100g of monomers.

  Examples of the hydrocarbyl lithium include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-octyl lithium, n-decyl lithium, phenyl lithium, 2-naphthyl lithium, and 2-butyl-phenyl. Examples include lithium, 4-phenyl-butyllithium, cyclohexyllithium, cyclopentyllithium, reaction products of diisopropenylbenzene and butyllithium, and among these, ethyllithium, n-propyllithium, isopropyllithium, n-butyl Alkyl lithium such as lithium, sec-butyl lithium, tert-octyl lithium and n-decyl lithium is preferable, and n-butyl lithium is particularly preferable.

  On the other hand, the lithium amide compounds include lithium hexamethylene imide, lithium pyrrolidide, lithium piperidide, lithium heptamethylene imide, lithium dodecamethylene imide, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium Dihexylamide, lithium diheptylamide, lithium dioctylamide, lythym-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiperazide, lithium ethylpropylamide, lithium ethylbutyramide, lithium methylbutyramide, lithium ethylbenzylamide, Examples include lithium methylphenethyl amide, among these, lithium hexamethylene imide, lithium pyrrolidide, lithium Cyclic lithium amide compounds such as piperidide, lithium heptamethylene imide and lithium dodecamethylene imide are preferred, and lithium hexamethylene imide and lithium pyrrolidide are particularly preferred.

（式中、Ｒ¹⁷は、それぞれ独立して炭素数１〜１２のアルキル基、シクロアルキル基又はアラルキル基である）で表される置換アミノ基又は下記式(VII)：

（式中、Ｒ¹⁸は、３〜１６のメチレン基を有するアルキレン基、置換アルキレン基、オキシアルキレン基又はＮ-アルキルアミノ-アルキレン基を示す）で表される環状アミノ基である］で表されるリチウムアミド化合物を用いることで、式(VI)で表される置換アミノ基及び式(VII)で表される環状アミノ基からなる群から選択される少なくとも一種の窒素を含む官能基が重合開始末端に導入された変性共役ジエン系重合体が得られる。 As the lithium amide compound, the formula: Li-AM [wherein AM is the following formula (VI):

(Wherein R ¹⁷ is each independently a C 1-12 alkyl group, cycloalkyl group or aralkyl group) or a substituted amino group represented by the following formula (VII):

Wherein R ¹⁸ is a cyclic amino group represented by an alkylene group having 3 to 16 methylene groups, a substituted alkylene group, an oxyalkylene group or an N-alkylamino-alkylene group. By using the lithium amide compound, at least one functional group containing nitrogen selected from the group consisting of a substituted amino group represented by the formula (VI) and a cyclic amino group represented by the formula (VII) starts polymerization. A modified conjugated diene polymer introduced at the terminal is obtained.

In the formula (VI), R ¹⁷ is an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group or an aralkyl group, and specifically includes a methyl group, an ethyl group, a butyl group, an octyl group, a cyclohexyl group, a 3- Preferable examples include phenyl-1-propyl group and isobutyl group. R ¹⁷ may be the same or different.

In the formula (VII), R ¹⁸ is an alkylene group having 3 to 16 methylene groups, a substituted alkylene group, an oxyalkylene group or an N-alkylamino-alkylene group. Here, the substituted alkylene group includes a mono- to octa-substituted alkylene group, and examples of the substituent include a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, a bicycloalkyl group, and an aryl group. Groups and aralkyl groups. R ¹⁸ is specifically preferably a trimethylene group, a tetramethylene group, a hexamethylene group, an oxydiethylene group, an N-alkylazadiethylene group, a dodecamethylene group, a hexadecamethylene group, or the like.

  The lithium amide compound may be preliminarily prepared from a secondary amine and a lithium compound and used for the polymerization reaction, but may be generated in a polymerization system. Here, examples of the secondary amine include dimethylamine, diethylamine, dibutylamine, dioctylamine, dicyclohexylamine, diisobutylamine and the like, as well as azacycloheptane (ie, hexamethyleneimine), 2- (2-ethylhexyl) pyrrolidine, 3 -(2-propyl) pyrrolidine, 3,5-bis (2-ethylhexyl) piperidine, 4-phenylpiperidine, 7-decyl-1-azacyclotridecane, 3,3-dimethyl-1-azacyclotetradecane, 4- Dodecyl-1-azacyclooctane, 4- (2-phenylbutyl) -1-azacyclooctane, 3-ethyl-5-cyclohexyl-1-azacycloheptane, 4-hexyl-1-azacycloheptane, 9-isoamyl -1-Azacycloheptadecane, 2-methyl-1-azacycloheptadec-9-ene, 3-isobutyl-1-azacyclododecane 2-Methyl-7-tert-butyl-1-azacyclododecane, 5-nonyl-1-azacyclododecane, 8- (4′-methylphenyl) -5-pentyl-3-azabicyclo [5.4.0] ] Undecane, 1-butyl-6-azabicyclo [3.2.1] octane, 8-ethyl-3-azabicyclo [3.2.1] octane, 1-propyl-3-azabicyclo [3.2.2] nonane And cyclic amines such as 3- (t-butyl) -7-azabicyclo [4.3.0] nonane and 1,5,5-trimethyl-3-azabicyclo [4.4.0] decane. On the other hand, as the lithium compound, the above hydrocarbyl lithium can be used.

  The method for producing a conjugated diene polymer by anionic polymerization using the above organic alkali metal compound or the like is not particularly limited, for example, in a hydrocarbon solvent inert to the polymerization reaction, the conjugated diene compound alone, Alternatively, a conjugated diene polymer can be produced by polymerizing a mixture of a conjugated diene compound and a vinyl aromatic compound. Here, hydrocarbon solvents inert to the polymerization reaction include propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2-butene, cis -2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene and the like. These may be used alone or in combination of two or more.

  The anionic polymerization may be performed in the presence of a randomizer. The randomizer can control the microstructure of the conjugated diene compound. For example, the randomizer can control the 1,2-bond content of a butadiene unit of a polymer using butadiene as a monomer, or can be styrene as a monomer. And butadiene units of a copolymer using butadiene are randomized. Examples of the randomizer include dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, bistetrahydrofurylpropane, triethylamine, pyridine, N-methylmorpholine, N, N, N ′, N′-tetramethylethylenediamine, 1 , 2-dipiperidinoethane, potassium-t-amylate, potassium-t-butoxide, sodium-t-amylate and the like. The amount of these randomizers used is preferably in the range of 0.01 to 100 molar equivalents per mole of polymerization initiator.

  The anionic polymerization may be performed by any of solution polymerization, gas phase polymerization, and bulk polymerization. In the case of solution polymerization, the concentration of the monomer in the solution is preferably in the range of 5 to 50% by mass, A range of 10 to 30% by mass is more preferable. In addition, when using together a conjugated diene compound and a vinyl aromatic compound as a monomer, the content rate of the vinyl aromatic compound in a monomer mixture has the preferable range of 3-50 mass%, 4-45 mass% The range of is more preferable. Further, the polymerization mode is not particularly limited, and may be batch type or continuous type.

  The polymerization temperature of the anionic polymerization is preferably in the range of 0 to 150 ° C, more preferably in the range of 20 to 130 ° C. The polymerization can be carried out under a generated pressure, but it is usually preferred to carry out the polymerization under a pressure sufficient to keep the monomer used in a substantially liquid phase. Here, when the polymerization reaction is carried out under a pressure higher than the generated pressure, it is preferable to pressurize the reaction system with an inert gas. Moreover, it is preferable to use what removed reaction-inhibiting substances, such as water, oxygen, a carbon dioxide, and a protic compound, as raw materials, such as a monomer used for superposition | polymerization, a polymerization initiator, and a solvent.

［式中、Ａは、(チオ)インシアネート、イミン、アミド、イソシアヌル酸トリエステル、環状三級アミン、非環状三級アミン、ニトリル及びピリジンの中から選ばれる少なくとも一種の窒素含有官能基を有する一価の基で；Ｒ¹⁹は単結合又は二価の不活性炭化水素基で；Ｒ²⁰及びＲ²¹は、それぞれ独立に炭素数１〜２０の一価の脂肪族炭化水素基又は炭素数６〜１８の一価の芳香族炭化水素基で；ｎは０〜２の整数であり；ＯＲ²¹が複数ある場合、複数のＯＲ²¹はたがいに同一でも異なっていてもよく；また分子中には活性プロトン及びオニウム塩は含まれない］で表される窒素含有ヒドロカルビルオキシシラン化合物及びその部分縮合物も好ましい。 In modifying the polymer having an active terminal with a modifier, the modifier used is a nitrogen-containing compound having a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrile group or pyridyl group. preferable. As a nitrogen-containing compound suitable as the modifier, nitrogen-containing compounds such as N, N′-diethylaminobenzophenone, dimethylimidazolidinone, N-methylpyrrolidone, 4-dimethylaminobenzylideneaniline can be used. In addition, a hydrocarbyloxysilane compound having a functional group containing nitrogen can also be used as a modifier, and specifically, the following formula (VIII):

[Wherein A has at least one nitrogen-containing functional group selected from (thio) inocyanate, imine, amide, isocyanuric acid triester, cyclic tertiary amine, acyclic tertiary amine, nitrile and pyridine. R ¹⁹ is a single bond or a divalent inert hydrocarbon group; R ²⁰ and R ²¹ are each independently a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or 6 carbon atoms; in ~ 18 monovalent aromatic hydrocarbon group; n is an integer from 0 to 2; if OR ²¹ there are a plurality or different and a plurality of OR ²¹ is identical to each other; in addition in the molecule An active proton and onium salt are not included], and a nitrogen-containing hydrocarbyloxysilane compound and a partial condensate thereof are also preferable.

  In the formula (VIII), among the functional groups in A, imine includes ketimine, aldimine, amidine, and acyclic tertiary amine is N, N-disubstituted aromatic such as N, N-disubstituted aniline. Amines are included, and cyclic tertiary amines can include (thio) ethers as part of the ring.

The divalent inert hydrocarbon group in R ¹⁹ is preferably an alkylene group having 1 to 20 carbon atoms. The alkylene group may be linear, branched or cyclic, but is particularly preferably linear. Examples of the linear alkylene group include a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, an octamethylene group, a decamethylene group, and a dodecamethylene group.

Examples of R ²⁰ and R ²¹ include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, and an aralkyl group having 7 to 18 carbon atoms. Here, the alkyl group and alkenyl group may be linear, branched, or cyclic, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl, tert-butyl, pentyl, hexyl, octyl, decyl, dodecyl, cyclopentyl, cyclohexyl, vinyl, propenyl, allyl, hexenyl, octenyl, cyclopentenyl Group, cyclohexenyl group and the like. The aryl group may have a substituent such as a lower alkyl group on the aromatic ring, and examples thereof include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. Furthermore, the aralkyl group may have a substituent such as a lower alkyl group on the aromatic ring, and examples thereof include a benzyl group, a phenethyl group, and a naphthylmethyl group.

  In the formula (VIII), n is an integer of 0 to 2, but 0 is preferable, and it is necessary that this molecule does not have active protons and onium salts.

  Examples of the hydrocarbyloxysilane compound represented by the formula (VIII) include N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine as an imine group-containing hydrocarbyloxysilane compound. , N- (1-methylethylidene) -3- (triethoxysilyl) -1-propanamine, N-ethylidene-3- (triethoxysilyl) -1-propanamine, N- (1-methylpropylidene)- 3- (Triethoxysilyl) -1-propanamine, N- (4-N, N-dimethylaminobenzylidene) -3- (triethoxysilyl) -1-propanamine, N- (cyclohexylidene) -3- (Triethoxysilyl) -1-propanamine and trimethoxysilyl compounds, methyldiethoxysilyl compounds, ethyldiethoxysilyl compounds, methyldimethoxysilanes corresponding to these triethoxysilyl compounds And N- (1-methylpropylidene) -3- (triethoxysilyl) -1-propanamine and N- (1,3-dimethyl). Butylidene) -3- (triethoxysilyl) -1-propanamine is particularly preferred.

  Further, the imine (amidine) group-containing compounds include 1- [3- (triethoxysilyl) propyl] -4,5-dihydroimidazole, 1- [3- (trimethoxysilyl) propyl] -4,5-dihydro. Imidazole, N- (3-triethoxysilylpropyl) -4,5-dihydroimidazole, N- (3-isopropoxysilylpropyl) -4,5-dihydroimidazole, N- (3-methyldiethoxysilylpropyl)- 4,5-dihydroimidazole and the like can be mentioned, and among these, N- (3-triethoxysilylpropyl) -4,5-dihydroimidazole is preferable.

  Examples of the isocyanate group-containing compound include 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropylmethyldiethoxysilane, and 3-isocyanatopropyltriisopropoxysilane. Of these, 3-isocyanatopropyltriethoxysilane is preferred.

  In addition, cyclic tertiary amine group-containing hydrocarbyloxysilane compounds include 3- (1-hexamethyleneimino) propyl (triethoxy) silane, 3- (1-hexamethyleneimino) propyl (trimethoxy) silane, and (1-hexamethylene). Imino) methyl (trimethoxy) silane, (1-hexamethyleneimino) methyl (triethoxy) silane, 2- (1-hexamethyleneimino) ethyl (triethoxy) silane, 2- (1-hexamethyleneimino) ethyl (trimethoxy) silane , 3- (1-pyrrolidinyl) propyl (triethoxy) silane, 3- (1-pyrrolidinyl) propyl (trimethoxy) silane, 3- (1-heptamethyleneimino) propyl (triethoxy) silane, 3- (1-dodecamethyleneimino ) Propyl (triethoxy) silane, 3- (1-hexamethyleneimino) propyl (diethoxy) methylsilane, 3- (1-he Xamethyleneimino) propyl (diethoxy) ethylsilane, 3- [10- (triethoxysilyl) decyl] -4-oxazoline and the like, among which 3- (1-hexamethyleneimino) propyl (triethoxy) silane and (1-Hexamethyleneimino) methyl (trimethoxy) silane is preferred.

  Furthermore, as the hydrocarbyloxysilane compound containing an acyclic tertiary amine group, 3-dimethylaminopropyl (triethoxy) silane, 3-dimethylaminopropyl (trimethoxy) silane, 3-diethylaminopropyl (triethoxy) silane, 3-diethylaminopropyl ( Trimethoxy) silane, 2-dimethylaminoethyl (triethoxy) silane, 2-dimethylaminoethyl (trimethoxy) silane, 3-dimethylaminopropyl (diethoxy) methylsilane, 3-dibutylaminopropyl (triethoxy) silane, and the like. Of these, 3-diethylaminopropyl (triethoxy) silane and 3-dimethylaminopropyl (triethoxy) silane are preferable.

  Still other nitrogen-containing hydrocarbyloxysilane compounds include 2- (trimethoxysilylethyl) pyridine, 2- (triethoxysilylethyl) pyridine, 2-cyanoethyltriethoxysilane, and the like.

  The amount of the modifier used is usually in the range of 0.1 to 3.0 mol, preferably in the range of 0.3 to 1.5 mol, with respect to 1 mol of the organic alkali metal compound as the polymerization initiator. Further, the modification reaction with the modifying agent is preferably performed by a solution reaction, and the solution may contain a monomer used at the time of polymerization. The reaction mode of the modification reaction is not particularly limited, and may be a batch type or a continuous type. Furthermore, the reaction temperature of the modification reaction is not particularly limited as long as the reaction proceeds, and the reaction temperature of the polymerization reaction may be employed as it is.

  The modified conjugated diene polymer preferably has a polystyrene-equivalent weight average molecular weight (Mw) of 50,000 or more and less than 700,000 as measured by gel permeation chromatography (GPC). If the weight average molecular weight of the modified conjugated diene polymer is less than 50,000, the fracture resistance and wear resistance are poor, and if it is 700,000 or more, the workability is remarkably deteriorated.

  The modified conjugated diene polymer preferably has a glass transition point (Tg) measured by a differential scanning calorimeter (DSC) of 0 ° C. or lower. When the glass transition point of the modified conjugated diene polymer exceeds 0 ° C., the rubber properties at low temperatures are remarkably deteriorated.

The rubber composition for a tread of the present invention contains 10 to 200 parts by mass of silica (B) with respect to 100 parts by mass of the rubber component (A). When the compounding amount of silica (B) is less than 10 parts by mass, the effect of reducing the rolling resistance of the tire and the effect of improving braking performance and driving stability on wet road surfaces are low. When the amount exceeds 200 parts by mass, the rubber composition As a result, the unvulcanized viscosity increases and workability deteriorates. The silica used in the rubber composition for a tread of the present invention is not particularly limited, and examples thereof include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, and the like. Among these, wet silica is most preferable because it has the most remarkable effects of improving the fracture resistance, braking performance / driving stability (wet grip properties) on wet road surfaces, and low rolling resistance. The silica preferably has a BET surface area of 40 to 350 m ² / g. Silica having a BET surface area within this range has an advantage that both rubber reinforcement and dispersibility in a rubber component can be achieved. From this viewpoint, silica having a BET surface area in the range of 80 to 300 m ² / g is more preferable.

  The rubber composition for a tread of the present invention contains 1 to 30 parts by mass of the sulfur-containing silane compound (C) represented by the average composition formula (I) with respect to 100 parts by mass of the rubber component (A). When the blending amount of the sulfur-containing silane compound of the formula (I) is less than 1 part by mass, the effect of improving the dispersibility of the silica (B) in the rubber component (A) and the unvulcanized viscosity of the rubber composition are reduced. Small effect. Moreover, when the compounding amount of the sulfur-containing silane compound of the formula (I) exceeds 30 parts by mass, the cost of the rubber composition increases. Here, the blending amount of the sulfur-containing silane compound (C) of the above formula (I) is more preferably in the range of 2 to 20 parts by mass with respect to 100 parts by mass of the rubber component (A) from the viewpoints of effect and cost.

  The sulfur-containing silane compound used in the rubber composition for a tread of the present invention is a compound represented by an average composition formula (I) having an organooxysilyl group at both ends of a molecule and a sulfide or polysulfide at the center of the molecule. is there.

In the average composition formula (I), R ¹ and R ² are each a monovalent hydrocarbon group having 1 to 4 carbon atoms, and examples of the monovalent hydrocarbon group include a methyl group, an ethyl group, n- Examples include propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, vinyl group, allyl group, isopropenyl group and the like. R ¹ and R ² may be the same or different. R ³ is a divalent hydrocarbon group having 1 to 15 carbon atoms, and examples of the divalent hydrocarbon group include a methylene group, an ethylene group, a propylene group, an n-butylene group, an i-butylene group, Examples include a hexylene group, a decylene group, a phenylene group, and a methylphenylethylene group. p represents an integer of 0 to 2, and m is 1 or more and less than 4 as an average value. m may be an average value within this range, and may be a mixture of a plurality of sulfur-containing silane compounds having different m values. From the viewpoint of the above effect, m is preferably 1 or more and less than 2, and most preferably 1, as an average value.

R ⁴ in the average composition formula (I) is a divalent functional group represented by any one of the general formulas (II), (III), and (IV). From the viewpoint of the above effects, R ⁴ is preferably the general formula (IV). Here, R ^{5 to} R ¹⁰ are linear or branched divalent hydrocarbon groups having 1 to 20 carbon atoms, divalent aromatic groups, or divalent organic groups containing hetero elements other than sulfur and oxygen. As R ^{5 to} R ¹⁰ , specifically, methylene group, ethylene group, propylene group, n-butylene group, i-butylene group, hexylene group, decylene group, phenylene group, methylphenylethylene group and the like And a group introduced with a hetero element other than sulfur and oxygen, such as nitrogen and phosphorus. R ^{5 to} R ¹⁰ in R ⁴ [any one of the functional groups represented by (II) to (IV)] in the average composition formula (I) may be the same or different. From the viewpoints of the above effects and production costs, R ^{5 to} R ¹⁰ in R ⁴ [any one of the functional groups represented by (II) to (IV)] of the average composition formula (I) are hexylene groups. It is preferable.

R ⁴ must contain a sulfur atom, and x, y, and z are 1 or more and less than 4 on average. From the viewpoint of the above effect, x, y, and z are each preferably an average value of 2 or more and less than 4, and most preferably 2 or more and 3 or less.

  The purity of the sulfur-containing silane compound of the present invention is preferably 60% or more, more preferably 70% or more, and particularly preferably 80% or more from the viewpoint of effects. In addition, the sulfur-containing silane compound of the present invention may produce a multimer such as a dimer or trimer of the above average composition formula (I) at the time of production, and 3 or more silicon atoms in one molecule. The sulfur-containing silane compound containing an atom may adversely affect the effect of the present invention. In the present invention, when the sulfur-containing silane compound according to the present invention is blended, the content of the sulfur-containing silane compound having 3 or more silicon atoms in one molecule is 30% by mass or less based on the rubber composition. It is preferably 10% by mass or less, and most preferably not substantially contained.

  The rubber composition for a tread of the present invention further contains a compound (D) represented by the above formula (V). By blending the compound (D) of the formula (V) with the rubber composition for tread, the elastic modulus of the rubber composition can be improved without reducing the hysteresis loss of the rubber composition. Here, the compounding amount of the compound (D) of the formula (V) is preferably in the range of 0.5 to 20 parts by mass, more preferably in the range of 0.5 to 10 parts by mass with respect to 100 parts by mass of the rubber component (A). The range of 1 to 5 parts by mass is even more preferable. When the compounding amount of the compound (D) of the formula (V) is less than 0.5 parts by mass, the effect of improving the elastic modulus of the rubber composition is small, and the steering stability on the dry road surface of the tire cannot be sufficiently improved. When the amount exceeds 20 parts by mass, the elastic modulus is remarkably increased and the cost is increased.

In formula (V), R ¹¹ is represented by a group represented by the formula —R ¹² O—, a group represented by the formula — (R ¹³ O) _s —, or a formula —CH ₂ CH (OH) CH ₂ O—. Or a group represented by the formula — (R ¹⁴ O—COR ¹⁵ —COO—) _t R ¹⁴ O—. Here, R ¹² is an alkylene group having 2 to 36 carbon atoms, an alkenylene group or a divalent aromatic hydrocarbon group, preferably an alkylene group having 2 to 18 carbon atoms or a phenylene group, more preferably a carbon number. 4 to 12 alkylene groups. R ¹³ is an alkylene group having 2 to 4 carbon atoms, preferably an ethylene group or a propylene group, and s is a number from 1 to 60 indicating the average number of moles added of the oxyalkylene group, preferably 2 to 40. More preferably, the number is 4 to 30. R ¹⁴ is an alkylene group having 2 to 18 carbon atoms, an alkenylene group, a divalent aromatic hydrocarbon group or a group represented by — (R ¹⁶ O) _u R ¹⁶ — (wherein R ¹⁶ is the number of carbon atoms) 2 to 4 alkylene groups; u is a number of 1 to 30 indicating the average number of added moles of the oxyalkylene group, preferably 1 to 20, and more preferably 2 to 15). R ¹⁵ is an alkylene group having 2 to 18 carbon atoms, an alkenylene group or a divalent aromatic hydrocarbon group, preferably an alkylene group having 2 to 12 carbon atoms or a phenylene group, more preferably 2 to 8 carbon atoms. An alkylene group. t is an average value of 1 to 30, preferably 1 to 20, and more preferably 1 to 15.

  Specific examples of the compound (D) represented by the formula (V) include dimaleates of alkylene diols such as glycerine dimaleate, 1,4-butanediol dimaleate, 1,6-hexanediol dimaleate; Dimer fumarate of alkylene diol such as 1,6-hexanediol difumarate; Dimaleate of polyoxyalkylene glycol such as PEG 200 dimaleate, PEG 600 dimaleate (where PEG 200 and PEG 600 are polyethylene glycol having an average molecular weight of 200 or 600, respectively); Polybutylene maleate having a carboxyl group at both ends, poly (PEG200) maleate having a carboxyl group at both ends, etc. Polyoxyalkylene glycol difumarate such as butylene adipate maleate and PEG 600 difumarate; polybutylene fumarate having a carboxyl group at both ends, poly (PEG200) fumarate having a carboxyl group at both ends, etc. / Fumarate polyester etc. are mentioned.

  The compound (D) of the above formula (V) preferably has a molecular weight of 250 or more, more preferably in the range of 250 to 5000, and particularly preferably in the range of 250 to 3000. Within this range, the flash point is high, which is desirable not only from the viewpoint of safety, but also from the viewpoint of the working environment because it produces less smoke. In addition, the compound (D) of the said formula (V) may be used individually by 1 type, and may be used in combination of 2 or more type.

  In addition to the rubber component (A), silica (B), sulfur-containing silane compound (C) of formula (I), and compound (D) of formula (V), the rubber composition for tread of the present invention includes rubber. A compounding agent usually used in the industry, for example, a softening agent, an anti-aging agent, a vulcanizing agent, a vulcanization accelerator and the like can be appropriately blended according to the purpose. As these compounding agents, commercially available products can be suitably used. The rubber composition for a tread of the present invention includes a rubber component (A) containing a modified conjugated diene polymer, silica (B), a sulfur-containing silane compound (C) of the formula (I), and a compound of the formula (V). It can manufacture by mix | blending various compounding agents selected suitably as needed with a compound (D), kneading | mixing, heating, extrusion, etc.

  The tire of the present invention is characterized by using the above-described rubber composition for a tread in the tread, and has rolling resistance significantly reduced while having sufficient steering stability and braking performance on a wet road surface. The tire of the present invention has a conventionally known structure and is not particularly limited, and can be produced by a normal method. Moreover, as gas with which the tire of the present invention is filled, an inert gas such as nitrogen, argon, helium, etc. can be used in addition to normal or air having an adjusted oxygen partial pressure.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

  First, a modified conjugated diene polymer having one or more functional groups containing nitrogen in the molecule and a sulfur-containing silane compound were synthesized by the following method.

<Synthesis Example of Modified Conjugated Diene Polymer>
Add 800 g of cyclohexane, 0.24 mmol of ditetrahydrofurylpropane, and 0.48 mmol of n-butyllithium (n-BuLi) together with 300 g of cyclohexane, 40 g of 1,3-butadiene, and 10 g of styrene in an 800 mL pressure-resistant glass container that is dried and purged with nitrogen Thereafter, a polymerization reaction was carried out at 50 ° C. for 1.5 hours. The polymerization conversion rate at this time was almost 100%. Next, 0.48 mmol of N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine as a modifier is quickly added to the polymerization reaction system, and the modification reaction is further performed at 50 ° C. for 30 minutes. Went. Thereafter, 0.5 mL of an isopropanol solution (BHT concentration: 5% by mass) of 2,6-di-t-butyl-p-cresol (BHT) was added to the polymerization reaction system to stop the polymerization reaction, and further according to a conventional method. It dried and the modified conjugated diene type polymer was obtained. Weight obtained by gel permeation chromatography [GPC: Tosoh HLC-8020, column: Tosoh GMH-XL (two in series), detector: differential refractometer (RI)] based on monodisperse polystyrene When the polystyrene-reduced number average molecular weight (Mn) and weight average molecular weight (Mw) of the polymer were determined, the polymer had a number average molecular weight of 210 × 10 ³ before the modification reaction, and the weight average molecular weight after the modification reaction was 320 × 10 ³ . Further, the obtained modified polymer had a vinyl bond content determined by the infrared method (Morero method) of 58%, and a bonded styrene content determined by an integral ratio of ¹ H-NMR spectrum was 20%. . Furthermore, using a differential thermal analyzer (DSC) 7 type apparatus manufactured by PerkinElmer, Inc., the polymer was cooled to −100 ° C. and then heated at a rate of temperature increase of 10 ° C./min. Was measured to find that the glass transition point was -38 ° C.

<Production example of sulfur-containing silane compound>
A 0.5 liter separable flask equipped with a nitrogen gas inlet tube, thermometer, Dimroth condenser and dropping funnel was charged with 80 g of ethanol, 5.46 g (0.07 mol) of anhydrous sodium sulfide, and 2.24 g (0.07 mol) of sulfur at 80 ° C. The temperature was raised to. While stirring this solution, 33.7 g (0.14 mol) of propyltriethoxysilane chloride [(CH ₃ CH ₂ O) ₃ Si— (CH ₂ ) ₃ —Cl] and 1,6-dichlorohexane [ClCH ₂ — (CH ₂ ) _4- CH ₂ Cl] 10.8 g (0.07 mol) was slowly added dropwise. After completion of dropping, stirring was continued at 80 ° C. for 10 hours. After completion of the stirring, the mixture was cooled and the produced salt was filtered off, and the solvent ethanol was distilled under reduced pressure. The obtained solution was subjected to infrared absorption spectrum analysis (IR analysis), ¹ H nuclear magnetic resonance spectrum analysis ( ¹ H-NMR analysis), and supercritical chromatography analysis. As a result, an average composition formula: (CH ₃ CH ₂ O) ₃ Si— (CH ₂ ) ₃ —S—S— (CH ₂ ) ₆ —S—S— (CH ₂ ) ₃ —Si (OCH ₂ CH ₃ ) ₃ was confirmed. That is, in the average composition formula (I), R ¹ is an ethyl group, R ³ is a trimethylene group, R ⁴ is S— (CH ₂ ) ₆ —S [general formula (II), and R ⁵ is (CH _{2 6} )], p = 0 and m = 1. The purity of this product in gel permeation chromatographic analysis (GPC analysis) was 82.5%.

  Next, a rubber composition having a formulation shown in Table 1 was prepared, and the rubber composition was used as a tread and vulcanized under normal vulcanization conditions to produce a tire of size 205 / 55R16, which is shown below. The rolling resistance, handling stability on dry road surfaces, and braking performance on wet road surfaces were evaluated by the method. The results are shown in Table 1.

(1) Rolling resistance Rolling resistance is determined by the coasting method when rotating at a speed of 80 km / h under the action of a load of 460 kg using a rotating drum with an outer diameter of 1707.6 mm and a width of 350 mm with a smooth steel surface. Measured and evaluated. The measured value was indicated as an index with the value of Comparative Example 1 being 100. The larger the index value, the smaller the rolling resistance and the better.

(2) Steering stability on dry roads Cars run on a dry road test course, and overall evaluation of driving performance, braking performance, steering wheel response, and controllability during steering is performed, giving a score of 1 to 10 points. In addition, each item was averaged to give a handling stability score. The larger the index value, the better the steering stability.

(3) Braking performance on wet road surface The test tire (internal pressure: 196 kPa) is mounted on four wheels of a passenger car, and the braking distance on the wet road surface is measured at an initial speed of 70 km on the test course. The reciprocal of the braking distance was expressed as an index with 100 as the inverse. The larger the index value, the shorter the braking distance and the better the wet road surface braking performance.

* 1 Made by JSR, SL563.
* 2 Modified conjugated diene polymer synthesized by the above method.
* 3 “Seast 7HM” manufactured by Tokai Carbon Co., Ltd.
* 4 Made by Nippon Silica Kogyo Co., Ltd., “Nip seal AQ”, BET surface area = 210 m ² / g.
_{* 5 (CH 3 CH 2 O} ) 3 Si- (CH 2) 3 -S 2.2 - (CH 2) 3 -Si (OCH 2 CH 3) 3, Degussa, "Si75".
* 6 Sulfur-containing silane compound synthesized by the above method.
* 7 In the formula (V), R ¹¹ is a group represented by — (R ¹⁴ O—COR ¹⁵ —COO—) _t R ¹⁴ O—; R ¹⁴ is — (R ¹⁶ O) _u R ¹⁶ — (R ¹⁶ is an ethylene group, u = 3.5); R ¹⁵ is —CH═CH—; t = 4.
* 8 N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine.
* 9 N-cyclohexyl-2-benzothiazylsulfenamide.
* 10 1,3-Diphenylguanidine.

  As is clear from Table 1, tires of examples using a rubber composition containing a nitrogen-containing modified conjugated diene polymer, a sulfur-containing silane compound of formula (I) and a compound of formula (V) in the tread are compared. Compared with the tire of Example 1, the steering stability was improved, the rolling resistance was remarkably low, and the braking performance on wet road surfaces was improved.

  On the other hand, the tires of Comparative Examples 1 to 4 in which the rubber composition not containing the sulfur-containing silane compound of the formula (I) and the compound of the formula (V) is used for the tread have a larger rolling resistance than the tires of the examples. Steering stability on dry road surfaces and braking performance on wet road surfaces were poor. In addition, the tires of Comparative Examples 5, 6 and 8 using a rubber composition not containing the nitrogen-containing modified conjugated diene polymer and the compound of formula (V) in the tread have a larger rolling resistance than the tires of the examples. The steering stability on the dry road surface and the braking performance on the wet road surface were poor.

Further, tires of Comparative Examples 7 and 9 using a rubber composition containing a sulfur-containing silane compound of formula (I) and a nitrogen-containing modified conjugated diene polymer but not containing a compound of formula (V) in the tread, Compared to the tires of the examples, the rolling resistance is large, the steering stability on the dry road surface is poor, and the sulfur-containing silane compound of the formula (I) and the compound of the formula (V) are contained, but the nitrogen-containing modified conjugated diene polymer The tire of Comparative Example 10 using a rubber composition containing no rubber as a tread had poor handling stability on a dry road surface and braking performance on a wet road surface compared to the tire of the Example.

Claims (11)

For 100 parts by mass of rubber component (A) containing at least a modified conjugated diene polymer having one or more functional groups containing nitrogen in the molecule,
10 to 200 parts by mass of silica (B),
The following average composition formula (I):
_{^{(R 1 O) 3-p}} (R 2) p Si-R 3 -S m -R 4 -S m -R 3 -Si (R 2) p (OR 1) 3-p ··· (I)
[Wherein R ¹ and R ² are each a monovalent hydrocarbon group having 1 to 4 carbon atoms, R ³ is a divalent hydrocarbon group having 1 to 15 carbon atoms, p is an integer of 0 to 2, m is The average value is 1 or more and less than 4, R ⁴ is represented by the following general formulas (II), (III) and (IV):
S-R ⁵ -S (II)
R ⁶ -S _x -R ⁷ (III)
^{_{R 8 -S y -R 9 -S z}} -R 10 ··· (IV)
(In the formula, R ^{5 to} R ¹⁰ are linear or branched divalent hydrocarbon groups having 1 to 20 carbon atoms, divalent aromatic groups, divalent aromatic groups, or hetero elements other than sulfur and oxygen. Each of R ^{5 to} R ¹⁰ may be the same or different, and each of x, y, and z is an average value of 1 or more and less than 4). 1-30 parts by mass of a sulfur-containing silane compound (C) represented by
The following general formula (V):
HOOC—CH═CH—COO—R ¹¹ —CO—CH═CH—COOH (V)
[Wherein R ¹¹ is a group represented by the formula —R ¹² O—, where R ¹² is an alkylene group having 2 to 36 carbon atoms, an alkenylene group or a divalent aromatic hydrocarbon group}, A group represented by — (R ¹³ O) _s —, wherein R ¹³ is an alkylene group having 2 to 4 carbon atoms; s is a number of 1 to 60 indicating the average number of moles added of the oxyalkylene group} , A group represented by the formula —CH ₂ CH (OH) CH ₂ O— or a group represented by the formula — (R ¹⁴ O—COR ¹⁵ —COO—) _t R ¹⁴ O—, wherein R ¹⁴ has 2 carbon atoms -18 alkylene group, alkenylene group, divalent aromatic hydrocarbon group or group represented by-(R ¹⁶ O) _u R ^16- (wherein R ¹⁶ is an alkylene group having 2 to 4 carbon atoms; u in a number of 1 to 30 showing an average addition mol number of the oxyalkylene group); R ¹⁵ is an alkylene group having 2 to 18 carbon atoms, an alkenylene group or A divalent aromatic hydrocarbon group; t is a compound represented by a is is a number of 1 to 30 as an average value} (D) and a tread rubber composition obtained by blending.   The tread according to claim 1, wherein the compounding amount of the compound (D) represented by the general formula (V) is 0.5 to 20 parts by mass with respect to 100 parts by mass of the rubber component (A). Rubber composition.   The rubber composition for a tread according to claim 1, wherein 10% by mass or more of the rubber component (A) is a modified conjugated diene polymer having one or more functional groups containing nitrogen in the molecule. object.   A modified conjugated diene polymer having one or more functional groups containing nitrogen in the molecule is reacted with a compound containing nitrogen in the molecule at the active end of the conjugated diene polymer having an active end. The rubber composition according to claim 1, which is obtained.   The rubber composition for a tread according to claim 1, wherein the conjugated diene polymer is a copolymer of 1,3-butadiene and a vinyl aromatic compound or a homopolymer of 1,3-butadiene. object.   The rubber composition for a tread according to claim 5, wherein the vinyl aromatic compound is styrene.   The rubber composition for a tread according to claim 1, wherein the modified conjugated diene polymer has a weight average molecular weight (Mw) of 50,000 or more and less than 700,000.   The rubber composition for a tread according to claim 1, wherein the modified conjugated diene polymer has a glass transition point (Tg) of 0 ° C or lower.   The rubber composition for a tread according to claim 1, wherein the conjugated diene polymer is polymerized using an organic alkali metal compound.   The rubber composition for a tread according to claim 9, wherein the organic alkali metal compound is a lithium compound. A tire using the tread rubber composition according to any one of claims 1 to 10.