JP2020186321A - Rubber composition for tires, and pneumatic tire - Google Patents

Abstract

To provide a rubber composition for tires capable of improving wet grip performance, and a pneumatic tire produced using the rubber composition.SOLUTION: The present invention relates to the rubber composition for tires which contains: a rubber component in which the total content of a styrene-butadiene rubber and a butadiene rubber is 90 mass% or more; 50 pts.mass or more of silica based on 100 pts.mass of the rubber component; and a liquid isoprene rubber. The rubber composition for tires satisfies the following formulae (A) and (B): (A) α≥30 and (B) α/β≥3, where α is the total vinyl content [mass%] in the styrene-butadiene rubber and the butadiene rubber; and β is the content [pts.mass] of the liquid isoprene rubber based on 100 pts.mass of the rubber component.SELECTED DRAWING: None

Description

The present invention relates to a rubber composition for a tire and a pneumatic tire.

As a technique for improving wet grip performance, for example, Patent Document 1 discloses a method of blending epoxidized natural rubber, silica, plant-derived oil, silane coupling agent, anionic surfactant and the like. However, in recent years, further improvement in wet grip performance has been required.

Japanese Unexamined Patent Publication No. 2005-263956

An object of the present invention is to provide a rubber composition for a tire capable of solving the above problems and improving wet grip performance, and a pneumatic tire produced by using the rubber composition.

The present invention contains a rubber component having a total content of styrene-butadiene rubber and butadiene rubber of 90% by mass or more, silica having a content of 50 parts by mass or more with respect to 100 parts by mass of the rubber component, and liquid isoprene rubber. The present invention relates to a rubber composition for a tire satisfying the following formulas (A) and (B).
(A) α ≧ 30
(B) α / β ≧ 3
α: Total amount of vinyl in styrene-butadiene rubber and butadiene rubber [mass%]
β: Content of liquid isoprene rubber with respect to 100 parts by mass of rubber component [parts by mass]

The rubber composition preferably contains a mercapto-based silane coupling agent.

The total amount of styrene-butadiene rubber and the total amount of styrene in the butadiene rubber is preferably 10% by mass or less.

The nitrogen adsorption specific surface area of the silica is preferably 200 m ² / g or more.

The present invention also relates to pneumatic tires made using the rubber composition.

According to the present invention, the total content of styrene-butadiene rubber and butadiene rubber is within a predetermined range, and a predetermined amount of silica and liquid isoprene rubber are contained, and the formulas (A) and (B) are further expressed. Since it is a rubber composition for tires that satisfies the requirements, wet grip performance can be improved.

The rubber composition for a tire of the present invention has a total content of styrene-butadiene rubber (SBR) and butadiene rubber (BR) within a predetermined range, and further contains a predetermined amount of silica and liquid isoprene rubber. , Equations (A) and (B) are satisfied.

The above-mentioned rubber composition has the above-mentioned effect, and it is presumed that this is achieved by the following effects.
In the above rubber composition, the total content of SBR and BR and the content of silica are adjusted within a predetermined range, and further, the total vinyl amount in SBR and BR, the total vinyl amount, and the content of liquid isoprene rubber. By adjusting the amount ratio within a predetermined range, silica and liquid isoprene rubber are well dispersed in the rubber composition. This is considered to significantly improve the wet grip performance.

Further, according to the rubber composition, the overall performance of wet grip performance, fuel efficiency, steering stability and wear resistance tends to be improved.

In the above rubber composition, the rubber component is a component that contributes to cross-linking, and generally has a weight average molecular weight (Mw) of 10,000 or more (preferably 100,000 or more) and is solid at normal temperature and pressure.
Mw is standard based on the values measured by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Toso Co., Ltd., detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Toso Co., Ltd.). It can be obtained by polystyrene conversion.

The rubber composition contains SBR and / or BR as a rubber component. It is preferable to use SBR and BR together because the overall performance tends to be good.

The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR) and the like can be used. The SBR may be either a non-modified SBR or a modified SBR.

The modified SBR may be an SBR having a functional group that interacts with a filler such as silica. For example, at least one end of the SBR is modified with a compound having the above functional group (modifying agent). SBR (terminally modified SBR having the above functional group at the end), main chain modified SBR having the above functional group on the main chain, and main chain terminal modified SBR having the above functional group on the main chain and the terminal (for example, on the main chain) Main chain terminal modified SBR having the above functional group and having at least one end modified with the above modifying agent) or a polyfunctional compound having two or more epoxy groups in the molecule, which is modified (coupling) with a hydroxyl group. And terminally modified SBR into which an epoxy group has been introduced.

Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group and a disulfide. Examples thereof include a group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group and an epoxy group. .. In addition, these functional groups may have a substituent. Among them, an amino group (preferably an amino group in which the hydrogen atom of the amino group is replaced with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxy group having 1 to 6 carbon atoms). An alkoxysilyl group having 1 to 6 carbon atoms is preferable.

（式中、Ｒ^１、Ｒ^２及びＲ^３は、同一又は異なって、アルキル基、アルコキシ基、シリルオキシ基、アセタール基、カルボキシル基（−ＣＯＯＨ）、メルカプト基（−ＳＨ）又はこれらの誘導体を表す。Ｒ^４及びＲ^５は、同一又は異なって、水素原子又はアルキル基を表す。Ｒ^４及びＲ^５は結合して窒素原子と共に環構造を形成してもよい。ｎは整数を表す。） As the modified SBR, an SBR modified with a compound (modifying agent) represented by the following formula is particularly preferable.

(In the formula, R ¹ , R ² and R ³ represent the same or different alkyl group, alkoxy group, silyloxy group, acetal group, carboxyl group (-COOH), mercapto group (-SH) or derivatives thereof. R ⁴ and R ⁵ represent the same or different hydrogen atoms or alkyl groups. R ⁴ and R ⁵ may combine to form a ring structure with a nitrogen atom. N represents an integer.)

The modified SBR modified by the compound (modifying agent) represented by the above formula includes, among others, the polymerization terminal (active terminal) of solution-polymerized styrene-butadiene rubber (S-SBR) using the compound represented by the above formula. Modified SBR (modified SBR described in JP-A-2010-111753, etc.) is preferably used.

Alkoxy groups are preferable as R ¹ , R ² and R ³ (preferably alkoxy groups having 1 to 8 carbon atoms, and more preferably alkoxy groups having 1 to 4 carbon atoms). Alkyl groups (preferably alkyl groups having 1 to 3 carbon atoms) are suitable as R ⁴ and R ⁵ . n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. Further, when R ⁴ and R ⁵ are bonded to form a ring structure together with a nitrogen atom, a 4- to 8-membered ring is preferable. The alkoxy group also includes a cycloalkoxy group (cyclohexyloxy group, etc.) and an aryloxy group (phenoxy group, benzyloxy group, etc.).

Specific examples of the above modifier include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, and 2-diethylaminoethyltri. Examples thereof include methoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane and the like. Of these, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyltriethoxysilane, and 3-diethylaminopropyltrimethoxysilane are preferable. These may be used alone or in combination of two or more.

As the modified SBR, a modified SBR modified with the following compound (modifying agent) can also be preferably used. Examples of the modifier include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethanetriglycidyl ether, and trimethylolpropane triglycidyl ether; and two or more diglycidylated bisphenol A and the like. Polyepoxy compounds of aromatic compounds having a phenol group of; 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, polyepoxidized liquid polybutadiene and other polyepoxy compounds; 4,4'-diglycidyl-diphenyl Epoxy group-containing tertiary amines such as methylamine, 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N, N'-diglycidyl-4-glycidyloxyaniline, diglycidyl orthotoluidine, tetraglycidyl metaxylene diamine , Tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, tetraglycidyl-1,3-bisaminomethylcyclohexane and other diglycidylamino compounds;

Amino group-containing acid chlorides such as bis- (1-methylpropyl) carbamic acid chloride, 4-morpholincarbonyl chloride, 1-pyrrolidincarbonyl chloride, N, N-dimethylcarbamic acid chloride, N, N-diethylcarbamic acid chloride; 1 , 3-Bis- (Glysidyloxypropyl) -Tetramethyldisiloxane, (3-Glysidyloxypropyl) -Pentamethyldisiloxane and other epoxy group-containing silane compounds;

(Trimethylsilyl) [3- (trimethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (triethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (tripropoxysilyl) propyl] sulfide, (trimethylsilyl) [3 -(Tributoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldimethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldiethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldimethoxysilyl) propyl] Sulfide group-containing silane compounds such as propoxysilyl) propyl] sulfide and (trimethylsilyl) [3- (methyldibutoxysilyl) propyl] sulfide;

N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N, N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane, N, N-bis (trimethylsilyl) -3-aminopropyltriethoxy Alkoxysilanes such as silane, N, N-bis (trimethylsilyl) aminoethyltrimethoxysilane, N, N-bis (trimethylsilyl) aminoethyltriethoxysilane; 4-N, N-dimethylaminobenzophenone, 4-N, N- Di-t-butylaminobenzophenone, 4-N, N-diphenylaminobenzophenone, 4,4'-bis (dimethylamino) benzophenone, 4,4'-bis (diethylamino) benzophenone, 4,4'-bis (diphenylamino) ) (Thio) benzophenone compounds having amino groups and / or substituted amino groups such as benzophenone, N, N, N', N'-bis- (tetraethylamino) benzophenone; 4-N, N-dimethylaminobenzaldehyde, 4- Benzaldehyde compounds having an amino group and / or a substituted amino group such as N, N-diphenylaminobenzaldehyde, 4-N, N-divinylaminobenzaldehyde; N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N- N-substituted pyrrolidones such as phenyl-2-pyrrolidone, N-t-butyl-2-pyrrolidone, N-methyl-5-methyl-2-pyrrolidone N-methyl-2-piperidone, N-vinyl-2-piperidone, N N-substituted piperidones such as -phenyl-2-piperidone; N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-lauryllactam, N-vinyl-ω-lauryllactam, N N-substituted lactams such as -methyl-β-propiolactam, N-phenyl-β-propiolactam;

N, N-bis- (2,3-epoxypropoxy) -aniline, 4,4-methylene-bis- (N, N-glycidylaniline), tris- (2,3-epoxypropyl) -1,3,5 -Triazine-2,4,6-triones, N, N-diethylacetamide, N-methylmaleimide, N, N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3 -Diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N, N-dimethylaminoacetophen, 4-N, N-diethylaminoacetophenone, 1,3-bis (diphenyl) Amino) -2-propanone, 1,7-bis (methylethylamino) -4-heptanone and the like can be mentioned. Of these, modified SBR modified with alkoxysilane is preferable.
The modification with the above compound (denaturing agent) can be carried out by a known method.

The amount of styrene in SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 60% by mass or less, more preferably 40% by mass or less, still more preferably 35% by mass or less. Within the above range, the above-mentioned overall performance tends to be good.
The amount of styrene can be measured by the method described in Examples described later.

The vinyl content of SBR is preferably 10% by mass or more, more preferably 25% by mass or more, further preferably 35% by mass or more, and preferably 65% by mass or less, more preferably 55% by mass or less. Within the above range, the above-mentioned overall performance tends to be good.
The amount of vinyl (1,2-bonded butadiene unit amount) can be measured by the method described in Examples described later.

As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., Zeon Corporation, etc. can be used.

When SBR is contained, the content of SBR in 100% by mass of the rubber component is preferably 40% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and preferably 90% by mass. % Or less, more preferably 80% by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The BR is not particularly limited, and a BR having a high cis content, a BR having a low cis content, a BR containing syndiotactic polybutadiene crystals, and the like can be used. The BR may be either a non-modified BR or a modified BR, and examples of the modified BR include a modified BR into which the above-mentioned functional group has been introduced. These may be used alone or in combination of two or more. The cis content of BR is preferably 30% by mass or more.
The cis content can be measured by infrared absorption spectrum analysis.

As the BR, for example, products such as Ube Industries, Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., and Zeon Corporation can be used.

The vinyl content of BR is preferably 1% by mass or more, more preferably 2% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less. Within the above range, the above-mentioned overall performance tends to be good.
The amount of vinyl (1,2-bonded butadiene unit amount) can be measured by the method described in Examples described later.

When BR is contained, the content of BR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and preferably 60% by mass or less, more preferably 40% by mass. % Or less, more preferably 30% by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The total content of SBR and BR in 100% by mass of the rubber component may be 90% by mass or more, preferably 95% by mass or more, and may be 100% by mass. Within the above range, the above-mentioned overall performance tends to be good.
When a rubber component other than SBR and BR is blended, the upper limit of the total content is preferably 99% by mass or less, more preferably 95% by mass or less.

Rubber components that can be used in addition to SBR and BR include diene rubbers such as isoprene rubber, acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). Rubber is mentioned. These diene rubbers may be used alone or in combination of two or more. Of these, isoprene-based rubber is preferable because the above-mentioned overall performance tends to be good.

As the isoprene-based rubber, isoprene rubber (IR), natural rubber (NR), epoxidized natural rubber (ENR) and the like can be used. Further, modified NR such as deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR) can also be used. These may be used alone or in combination of two or more.

When the isoprene-based rubber is contained, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 1% by mass or more, more preferably 3% by mass or more, and preferably 10% by mass or less. It is preferably 5% by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The rubber composition contains silica.
Examples of silica include dry silica (silicic anhydride) and wet silica (hydrous silicic acid), but wet silica is preferable because it contains a large amount of silanol groups. These may be used alone or in combination of two or more.

Nitrogen adsorption specific surface area _(N 2 SA) of silica is preferably 150 meters ² / g or more, more preferably 200 meters ² / g or more, further preferably 220 m ² / g or more, and preferably not more than 300 meters ² / g , More preferably 260 m ² / g or less. Within the above range, the above-mentioned overall performance tends to be good.
The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

As the silica, for example, products such as Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation can be used.

The content of silica with respect to 100 parts by mass of the rubber component may be 50 parts by mass or more, preferably 65 parts by mass or more, more preferably 75 parts by mass or more, and preferably 150 parts by mass or less, more preferably. Is 130 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The rubber composition preferably contains a silane coupling agent together with silica.
The silane coupling agent is not particularly limited, and for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, Bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis ( 3-Triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) ) Disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 3- Sulfide type such as triethoxysilylpropyl methacrylate monosulfide, mercapto type such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, vinyl type such as vinyltriethoxysilane and vinyltrimethoxysilane, 3-aminopropyl Amino type such as triethoxysilane and 3-aminopropyltrimethoxysilane, glycidoxy type such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, 3-nitropropyltrimethoxysilane, 3- Examples thereof include nitro type such as nitropropyltriethoxysilane, chloro type such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These may be used alone or in combination of two or more. Among them, the mercapto system is more preferable because the above-mentioned overall performance tends to be good.

As the mercapto-based silane coupling agent, in addition to a compound having a mercapto group, a compound having a structure in which the mercapto group is protected by a protecting group (for example, a compound represented by the following formula (S1)) can also be used. ..

（式中、Ｒ^１００１は−Ｃｌ、−Ｂｒ、−ＯＲ^１００６、−Ｏ（Ｏ＝）ＣＲ^１００６、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＮＲ^１００６Ｒ^１００７及び−（ＯＳｉＲ^１００６Ｒ^１００７）_ｈ（ＯＳｉＲ^１００６Ｒ^１００７Ｒ^１００８）から選択される一価の基（Ｒ^１００６、Ｒ^１００７及びＲ^１００８は同一でも異なっていても良く、各々水素原子又は炭素数１〜１８の一価の炭化水素基であり、ｈは平均値が１〜４である。）であり、Ｒ^１００２はＲ^１００１、水素原子又は炭素数１〜１８の一価の炭化水素基、Ｒ^１００３は−［Ｏ（Ｒ^１００９Ｏ）_ｊ］−基（Ｒ^１００９は炭素数１〜１８のアルキレン基、ｊは１〜４の整数である。）、Ｒ^１００４は炭素数１〜１８の二価の炭化水素基、Ｒ^１００５は炭素数１〜１８の一価の炭化水素基を示し、ｘ、ｙ及びｚは、ｘ＋ｙ＋２ｚ＝３、０≦ｘ≦３、０≦ｙ≦２、０≦ｚ≦１の関係を満たす数である。）

（式中、ｖは０以上の整数、ｗは１以上の整数である。Ｒ^１１は水素、ハロゲン、分岐若しくは非分岐の炭素数１〜３０のアルキル基、分岐若しくは非分岐の炭素数２〜３０のアルケニル基、分岐若しくは非分岐の炭素数２〜３０のアルキニル基、又は該アルキル基の末端の水素が水酸基若しくはカルボキシル基で置換されたものを示す。Ｒ^１２は分岐若しくは非分岐の炭素数１〜３０のアルキレン基、分岐若しくは非分岐の炭素数２〜３０のアルケニレン基、又は分岐若しくは非分岐の炭素数２〜３０のアルキニレン基を示す。Ｒ^１１とＲ^１２とで環構造を形成してもよい。） As a particularly suitable mercapto-based silane coupling agent, a silane coupling agent represented by the following formula (S1) and a binding unit A represented by the following formula (I) and a binding unit B represented by the following formula (II) are used. Included silane coupling agents include.

(In the formula, R ¹⁰⁰¹ is -Cl, -Br, -OR ¹⁰⁰⁶ , -O (O =) CR ¹⁰⁰⁶ , -ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , -NR ¹⁰⁰⁶ R ¹⁰⁰⁷ and-(OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸⁾ a monovalent group selected from ^{(R 1006, R 1007} and ^{R 1008} may be the same or different, be each a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms , H has an average value of 1 to 4), R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰³ is − [O (R ¹⁰⁰⁹ O) _j. ] ^-Group (R ¹⁰⁰⁹ is an alkylene group having 1 to 18 carbon atoms, j is an integer of 1 to 4), R ¹⁰⁰⁴ is a divalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰⁵ is 1 carbon atom. It represents a monovalent hydrocarbon group of ~ 18, and x, y and z are numbers that satisfy the relationship of x + y + 2z = 3, 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, 0 ≦ z ≦ 1).

(In the formula, v is an integer of 0 or more, w is an integer of 1 or more. R ¹¹ is a hydrogen, halogen, branched or unbranched alkyl group having 1 to 30 carbon atoms, branched or unbranched carbon number 2 to 2. 30 alkenyl groups, branched or unbranched alkynyl groups having 2 to 30 carbon atoms, or hydrogens at the ends of the alkyl groups substituted with hydroxyl or carboxyl groups. R ¹² has branched or unbranched carbon atoms. It represents an alkylene group of 1 to 30, a branched or non-branched alkenylene group having 2 to 30 carbon atoms, or a branched or non-branched alkynylene group having 2 to 30 carbon atoms. A ring structure is formed by R ¹¹ and R ^12. May be.)

In formula (S1), R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ are independently derived from a linear, cyclic or branched alkyl group having 1 to 18 carbon atoms, an alkenyl group, an aryl group and an aralkyl group, respectively. It is preferable that the group is selected from the group. When R ¹⁰⁰² is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is selected from the group consisting of a linear, cyclic or branched alkyl group, an alkenyl group, an aryl group and an aralkyl group. It is preferably a group. R ¹⁰⁰⁹ is preferably a linear, cyclic or branched alkylene group, and particularly preferably linear. ^R1004 is, for example, an alkylene group having 1 to 18 carbon atoms, an alkenylene group having 2 to 18 carbon atoms, a cycloalkylene group having 5 to 18 carbon atoms, a cycloalkylalkylene group having 6 to 18 carbon atoms, and an arylene having 6 to 18 carbon atoms. Examples thereof include a group and an aralkylene group having 7 to 18 carbon atoms. The alkylene group and the alkenylene group may be linear or branched, and the cycloalkylene group, the cycloalkylalkylene group, the arylene group and the aralkylene group have a functional group such as a lower alkyl group on the ring. You may be doing it. As the R ¹⁰⁰⁴ , an alkylene group having 1 to 6 carbon atoms is preferable, and a linear alkylene group such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group and a hexamethylene group are particularly preferable.

Specific examples of R ¹⁰⁰² , R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ^{1008 in} the formula (S1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group and sec-butyl. Group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, vinyl group, propenyl group, allyl group, hexenyl group, octenyl group, cyclopentenyl group, cyclo Examples thereof include a hexenyl group, a phenyl group, a tolyl group, a xsilyl group, a naphthyl group, a benzyl group, a phenethyl group and a naphthylmethyl group.
Examples of R ¹⁰⁰⁹ in the formula (S1) include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, a hexylene group and the like as the linear alkylene group, and examples of the branched alkylene group include a branched alkylene group. Examples thereof include an isopropylene group, an isobutylene group and a 2-methylpropylene group.

Specific examples of the silane coupling agent represented by the formula (S1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, and 3-. Lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoy Luciopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthio Examples thereof include ethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, 2-lauroylthioethyltrimethoxysilane and the like. These may be used alone or in combination of two or more. Of these, 3-octanoylthiopropyltriethoxysilane is particularly preferable.

In the silane coupling agent containing the binding unit A represented by the formula (I) and the binding unit B represented by the formula (II), the content of the binding unit A is preferably 30 mol% or more, more preferably 50 mol. % Or more, preferably 99 mol% or less, more preferably 90 mol% or less. The content of the binding unit B is preferably 1 mol% or more, more preferably 5 mol% or more, still more preferably 10 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or less. More preferably, it is 55 mol% or less. The total content of the binding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%.
The content of the binding units A and B is an amount including the case where the binding units A and B are located at the ends of the silane coupling agent. The form in which the binding units A and B are located at the ends of the silane coupling agent is not particularly limited, and a unit corresponding to the formulas (I) and (II) representing the binding units A and B may be formed. ..

Regarding R ¹¹ in the formulas (I) and (II), examples of the halogen include chlorine, bromine and fluorine. Examples of the branched or non-branched alkyl group having 1 to 30 carbon atoms include a methyl group and an ethyl group. Examples of the branched or non-branched alkenyl group having 2 to 30 carbon atoms include a vinyl group and a 1-propenyl group. Examples of the branched or non-branched alkynyl group having 2 to 30 carbon atoms include an ethynyl group and a propynyl group.

For ^{R 12} in the formula (I), (II), Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms, an ethylene group, a propylene group, and the like. Examples of the branched or non-branched alkenylene group having 2 to 30 carbon atoms include a vinylene group and a 1-propenylene group. Examples of the branched or non-branched alkynylene group having 2 to 30 carbon atoms include an ethynylene group and a propynylene group.

In a silane coupling agent containing the binding unit A represented by the formula (I) and the binding unit B represented by the formula (II), the number of repetitions (v) of the binding unit A and the number of repetitions (w) of the binding unit B The total number of repetitions (v + w) is preferably in the range of 3 to 300.

When a silane coupling agent is contained, the content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and preferably 20 parts by mass with respect to 100 parts by mass of silica. Hereinafter, it is more preferably 15 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The rubber composition contains liquid isoprene rubber (liquid IR).
The liquid IR is a polyisoprene polymer having isoprene as a constituent unit, which is liquid at normal temperature and pressure, and is not included in the rubber component. The Mw of the liquid IR is usually less than 100,000 (preferably 80,000 or less).

The liquid IR may be either a non-modified liquid IR or a modified liquid IR. Examples of the modified liquid IR include the modified liquid IR into which the above-mentioned functional groups have been introduced. These may be used alone or in combination of two or more.

As the liquid IR, for example, a product such as Kuraray Co., Ltd. can be used.

The content of the liquid IR is preferably 1 part by mass or more, more preferably 5 parts by mass or more, further preferably 8 parts by mass or more, and preferably 30 parts by mass or less with respect to 100 parts by mass of the rubber component. It is more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

In the rubber composition, the total vinyl content and the liquid IR content in SBR and BR satisfy the following formulas (A) and (B).
(A) α ≧ 30
(B) α / β ≧ 3
α: Total amount of vinyl in styrene-butadiene rubber and butadiene rubber [mass%]
β: Content of liquid isoprene rubber with respect to 100 parts by mass of rubber component [parts by mass]

α (total vinyl amount in SBR and BR) may be adjusted within a range satisfying the formulas (A) and (B), but from the viewpoint of wet grip performance, it is preferably 32% by mass or more, more preferably 35% by mass. % Or more, preferably 60% by mass or less, and more preferably 45% by mass or less.
Here, the total vinyl content in SBR and BR (the ratio of the vinyl portion to the total content of SBR and BR) is ((Σ (content of each SBR × vinyl content of each SBR / 100) + Σ (each BR). Content x vinyl content of each BR / 100)) / Σ (content of each SBR + content of each BR)) x 100. For example, the rubber component is SBR (A) (vinyl amount 40% by mass) 85% by mass, SBR (B) (vinyl amount 25% by mass) 5% by mass, BR (vinyl amount 25% by mass) 5% by mass, NR 5% by mass. When composed of%, the total amount of vinyl in SBR and BR is 38.4% by mass (= (((85 × 40/100 + 5 × 25/100 + 5 × 25/100) / (85 + 5 + 5)) × 100). ..

In the formula (B), α / β is preferably 3.3 or more, more preferably 3.5 or more, and preferably 10 or less, more preferably 8 or less, from the viewpoint of wet grip performance.

The total amount of styrene in SBR and BR is preferably 1% by mass or more, more preferably 5% by mass or more, and preferably 25% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass. It is as follows. Within the above range, the above-mentioned overall performance tends to be good.
Here, the total amount of styrene in SBR and BR (the ratio of the styrene portion to the total content of SBR and BR) is (Σ (content of each SBR × amount of styrene of each SBR / 100) / Σ (each SBR). Content + content of each BR))) × 100. For example, when the rubber component is composed of SBR (A) (40% by mass of styrene) 85% by mass, SBR (B) (25% by mass of styrene) 5% by mass, 5% by mass of BR, and 5% by mass of NR, SBR And the total amount of styrene in BR is 37.1% by mass (= (((85 × 40/100 + 5 × 25/100) / (85 + 5 + 5)) × 100).

The rubber composition may contain a resin other than liquid IR.
The resin other than the liquid IR is not particularly limited as long as it is widely used in the tire industry. For example, C5 resin, styrene resin, terpene resin, rosin resin, Kumaron inden resin, pt. -Butylphenol acetylene resin, acrylic resin and the like can be mentioned. These may be used alone or in combination of two or more. Of these, C5-based resins and terpene-based resins are preferable.

The weight average molecular weight (Mw) of the resin is preferably 200 or more, more preferably 400 or more, and preferably 5000 or less, more preferably 3000 or less. Within the above range, the above-mentioned overall performance tends to be good.

The C5-based resin is a polymer containing a C5 fraction as a constituent monomer, and examples thereof include a polymer obtained by polymerizing the C5 fraction as a main component (50% by mass or more). Specifically, C5 distillates (olefin hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3 -A homopolymer obtained by independently polymerizing a diolefin hydrocarbon such as pentadiene), a copolymer obtained by copolymerizing two or more C5 distillates, a C5 distillate and other copolymers capable of copolymerizing the same. Copolymers with monomers can also be mentioned.

Examples of other monomers include C9 fractions such as vinyltoluene, indene, and methyl indene. These may be used alone or in combination of two or more.

The C5 resin is preferably a copolymer of a C5 fraction and another monomer, and is a copolymer of a C5 fraction and a C9 fraction (because the above-mentioned overall performance tends to be good). C5 / C9 resin) is more preferable.

When the C5 resin is contained, the content of the C5 resin with respect to 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 25 parts by mass or more, and more preferably. Is 50 parts by mass or less, more preferably 35 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

As the terpene-based resin, a polyterpene resin obtained by polymerizing a terpene compound, an aromatic-modified terpene resin obtained by polymerizing a terpene compound and an aromatic compound, and the like can be used. Moreover, these hydrogenated additives can also be used.

The polyterpene resin is a resin obtained by polymerizing a terpene compound. The terpene compound _is a hydrocarbon and oxygenated derivative _{(C 5} H ₈₎ represented by a composition of _n, monoterpenes _(C 10 _{H 16),} sesquiterpene _(C 15 _{H 24),} diterpenes _{(C 20} H It is a compound having a terpene as a basic skeleton classified into ₃₂ ) and the like. Examples thereof include terpinene, 1,8-cineol, 1,4-cineol, α-terpineol, β-terpineol, and γ-terpineol.

Examples of the polyterpene resin include pinene resin, limonene resin, dipentene resin, and pinene / limonene resin made from the above-mentioned terpene compound. Of these, pinene resin is preferable because it is easy to carry out a polymerization reaction and is inexpensive because it is made from natural pine resin. The pinene resin usually contains both α-pinene and β-pinene having an isomer relationship, but depending on the difference in the contained components, β-pinene resin containing β-pinene as a main component and α- It is classified as α-pinene resin containing pinene as the main component.

Examples of the aromatic-modified terpene resin include a terpene phenol resin made from the above terpene compound and a phenol compound, a terpene styrene resin made from the above terpene compound and a styrene compound, and the like. Further, a terpene phenol styrene resin made from the above terpene compound, phenol compound and styrene compound can also be used. Examples of the phenolic compound include phenol, bisphenol A, cresol, xylenol and the like. Examples of the styrene compound include styrene and α-methylstyrene.

The aromatic-modified terpene resin is preferable as the terpene-based resin because the above-mentioned overall performance tends to be good.

When the terpene resin is contained, the content of the terpene resin is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. Further, it is preferably 60 parts by mass or less, more preferably 50 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

Commercially available products of resins other than liquid IR include, for example, Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Toso Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Ltd., Arizona Chemical Co., Ltd., Nikko Chemical Co., Ltd. Products such as Nippon Catalyst Co., Ltd., JXTG Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Co., Ltd., ExxonMobil Co., Ltd., and CrayValley Co., Ltd. can be used.

The total content of the liquid IR and other resins is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 25 parts by mass or more, and particularly preferably 35 parts by mass with respect to 100 parts by mass of the rubber component. It is more than parts, preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and particularly preferably 60 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.
When no resin other than liquid IR is contained, the total content is synonymous with the content of liquid IR.

The rubber composition preferably contains carbon black.
The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. These may be used alone or in combination of two or more.

The specific surface area of carbon black with cetyltrimethylammonium bromide (CTAB) is preferably 100 m ² / g or more, more preferably 130 m ² / g or more, and preferably 200 m ² / g or less, more preferably 160 m ² / g. It is as follows. Within the above range, the above-mentioned overall performance tends to be good.
The CTAB specific surface area of carbon black is a value measured in accordance with JIS K6217-3: 2001.

As carbon black, for example, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nikka Carbon Co., Ltd., Columbia Carbon Co., Ltd., etc. Can be used.

When carbon black is contained, the content of carbon black is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and preferably 30 parts by mass or less, based on 100 parts by mass of the rubber component. It is preferably 15 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The rubber composition may contain oil.
Examples of the oil include process oils, vegetable oils and fats, or mixtures thereof. As the process oil, for example, paraffin-based process oil, aroma-based process oil, naphthenic process oil, or the like can be used. Vegetable oils and fats include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, rosin, pine oil, pineapple, tall oil, corn oil, rice oil, beni flower oil, sesame oil, Examples thereof include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These may be used alone or in combination of two or more. Of these, process oil is preferable.

Examples of oils include Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H & R Co., Ltd. And other products can be used.

The content of the oil is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, and particularly preferably 5 parts by mass or less with respect to 100 parts by mass of the rubber component. The lower limit is not particularly limited and may be 0 parts by mass. Within the above range, the above-mentioned overall performance tends to be good.

The rubber composition may contain wax.
The wax is not particularly limited, and examples thereof include petroleum wax such as paraffin wax and microcrystalline wax; natural wax such as plant wax and animal wax; and synthetic wax such as a polymer such as ethylene and propylene. These may be used alone or in combination of two or more. Of these, petroleum wax is preferable, and paraffin wax is more preferable.

As the wax, for example, products such as Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Kagaku Co., Ltd. can be used.

When the wax is contained, the content of the wax is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 20 parts by mass or less, more preferably 20 parts by mass or more, based on 100 parts by mass of the rubber component. It is 10 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The rubber composition may contain an anti-aging agent.
Examples of the anti-aging agent include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis (α, α'-dimethylbenzyl) diphenylamine; N. -Isopropyl-N'-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylenediamine, etc. P-Phenylenediamine-based anti-aging agent; quinoline-based anti-aging agent such as a polymer of 2,2,4-trimethyl-1,2-dihydroquinolin; 2,6-di-t-butyl-4-methylphenol, Monophenolic antioxidants such as styrenated phenol; tetrakis- [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] bis, tris, polyphenolic aging such as methane Examples include preventive agents. These may be used alone or in combination of two or more. Of these, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferable.

As the anti-aging agent, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis Co., Ltd. and the like can be used.

When the anti-aging agent is contained, the content of the anti-aging agent is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and preferably 10 parts by mass or less with respect to 100 parts by mass of the rubber component. , More preferably 8 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The rubber composition may contain stearic acid.
As the stearic acid, conventionally known ones can be used, and for example, products such as NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., and Chiba Fatty Acid Co., Ltd. can be used.

When stearic acid is contained, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less with respect to 100 parts by mass of the rubber component. , More preferably 5 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The rubber composition may contain zinc oxide.
Conventionally known zinc oxide can be used. For example, products of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., HakusuiTech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. Can be used.

When zinc oxide is contained, the content of zinc oxide is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. It is preferably 5 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The rubber composition may contain sulfur.
Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur, which are generally used in the rubber industry. These may be used alone or in combination of two or more.

As the sulfur, for example, products such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Corporation, Flexis Co., Ltd., Nippon Inui Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd. can be used.

When sulfur is contained, the sulfur content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. It is preferably 5 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The rubber composition may contain a vulcanization accelerator.
Examples of the sulfide accelerator include thiazole-based sulfide-based sulfide accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; tetramethylthiuram disulfide (TMTD). ), Tetrabenzyl thiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N) and other thiuram-based sulfide accelerators; N-cyclohexyl-2-benzothiazolesulfenamide, N-t-butyl- 2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N, N'-diisopropyl-2-benzothiazolesulfenamide, etc. Sulfenamide-based sulfide accelerator; guanidine-based sulfide accelerators such as diphenylguanidine, dioltotrilguanidine, orthotrilbiguanidine can be mentioned. These may be used alone or in combination of two or more. Of these, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferable.

As the vulcanization accelerator, for example, products manufactured by Kawaguchi Chemical Industry Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Sanshin Chemical Industry Co., Ltd., etc. can be used.

When the vulcanization accelerator is contained, the content of the vulcanization accelerator is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, and preferably 10 parts by mass with respect to 100 parts by mass of the rubber component. Parts or less, more preferably 8 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

In addition to the above components, the rubber composition contains additives generally used in the tire industry, such as organic peroxides; fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. ; Etc. may be further blended. The content of these additives is preferably 0.1 to 200 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition can be produced, for example, by kneading each of the components using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanizing.

As the kneading conditions, in the base kneading step of kneading additives other than the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 100 to 180 ° C., preferably 120 to 170 ° C. In the final kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 120 ° C. or lower, preferably 85 to 110 ° C. Further, the composition obtained by kneading the vulcanizing agent and the vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190 ° C, preferably 150 to 185 ° C. The vulcanization time is usually 5 to 15 minutes.

The above rubber composition is preferably used for treads (cap treads), but for members other than treads, such as sidewalls, base treads, under treads, clinch apex, bead apex, breaker cushion rubber, and carcass cord coating. It may be used for rubber, insulation, chafer, inner liner, etc., and as a side reinforcing layer for run-flat tires.

The pneumatic tire of the present invention is produced by a usual method using the above rubber composition.
That is, the rubber composition is extruded according to the shape of each tire member of the tread at the unvulcanized stage, and is molded together with other tire members by a normal method on a tire molding machine. Form a vulcanized tire. A tire is obtained by heating and pressurizing this unvulcanized tire in a vulcanizer.

The above-mentioned pneumatic tires include passenger car tires; truck / bus tires; two-wheeled vehicle tires; high-performance tires; winter tires such as studless tires; run-flat tires having side reinforcing layers; and sound absorbing members such as sponges in the tire cavity. Tire with sound absorbing member; Tire with sealing member that has a sealant that can be sealed inside the tire or inside the tire cavity; Tire with electronic parts that has electronic parts such as sensors and wireless tags inside the tire or inside the tire cavity. It can be used for such purposes, and is suitable for passenger car tires.

The present invention will be specifically described based on Examples, but the present invention is not limited thereto.
The various chemicals used in the examples will be described below.
SBR1: Buna VSL5025-2 HM manufactured by LANXESS (styrene amount: 25% by mass, vinyl amount: 50% by mass)
SBR2: Modified SBR synthesized in Production Example 1 below (styrene amount: 10% by mass, vinyl amount: 40% by mass, Mw: 200,000)
SBR3: Modified SBR synthesized in Production Example 2 below (styrene amount: 35% by mass, vinyl amount: 50% by mass, Mw: 600,000)
BR1: BR1280 manufactured by LG Chem (vinyl amount: 2% by mass, cis content: 96 mol%)
BR2: N103 manufactured by Asahi Kasei Chemicals Co., Ltd. (vinyl amount: 12% by mass, cis content: 38% by mass)
Isoprene rubber: TSR20 (natural rubber)
Carbon black 1: N134 (CTAB: 135m ² / g)
Carbon black 2: N220 (CTAB: 111m ² / g)
Silica 1: Ultrasil 9000GR (N ₂ SA: 240m ² / g) manufactured by Evonik Degussa
Silica 2: Ultrasil VN3 manufactured by Evonik Degussa (N ₂ SA: 167m ² / g)
Silane coupling agent 1: NXT-Z45 manufactured by Momentive (copolymer of bond unit A and bond unit B (bond unit A: 55 mol%, bond unit B: 45 mol%))
Silane coupling agent 2: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive.
Silane coupling agent 3: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Evonik Degussa
Oil: A / O mixed liquid manufactured by Sankyo Yuka Kogyo Co., Ltd .: LIR50 manufactured by Kuraray Co., Ltd. (Mw: 54000, liquid at normal temperature and pressure)
Resin 1: YS resin TO125 manufactured by Yasuhara Chemical Co., Ltd. (aromatically modified terpene resin, Mw: 800)
Resin 2: Ricon 340 (C5 / C9 resin, Mw: 240) manufactured by CrayValley.
Wax: Ozo Ace 0355 manufactured by Nippon Seiro Co., Ltd.
Anti-aging agent 1: Nocrack 6C (N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Anti-aging agent 2: Nocrack RD (Poly (2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Stearic acid: Stearic acid "Camellia" manufactured by NOF CORPORATION
Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Metal Mining Co., Ltd. Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. 1: Noxeller CZ (N-cyclohexyl-2) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. − Benzothiazolylsulfenamide)
Vulcanization accelerator 2: Noxeller D (1,3-diphenylguanidine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

(Manufacturing Example 1)
Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into a nitrogen-substituted autoclave reactor. After adjusting the temperature of the contents of the reactor to 20 ° C., n-butyllithium was added to initiate polymerization. Polymerization was carried out under adiabatic conditions, and the maximum temperature reached 85 ° C. When the polymerization conversion rate reached 99%, 1,3-butadiene was added, and after further polymerization for 5 minutes, 3-diethylaminopropyltrimethoxysilane was added as a denaturant to carry out the reaction. After completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Then, the solvent was removed by steam stripping and dried by a heat roll adjusted to 110 ° C. to obtain SBR1.

(Manufacturing Example 2)
Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into a nitrogen-substituted autoclave reactor. After adjusting the temperature of the contents of the reactor to 20 ° C., n-butyllithium was added to initiate polymerization. Polymerization was carried out under adiabatic conditions, and the maximum temperature reached 85 ° C. When the polymerization conversion rate reached 99%, 1,3-butadiene was added, and after further polymerization for 5 minutes, N- (3-dimethylaminopropyl) acrylamide was added as a denaturant to carry out the reaction. After completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Then, the solvent was removed by steam stripping and dried by a heat roll adjusted to 110 ° C. to obtain SBR3.

(SBR analysis)
The structure identification of SBR (measurement of the amount of styrene and the amount of vinyl) was performed using an apparatus of the JNM-ECA series manufactured by JEOL Ltd. The measurement was carried out by dissolving 0.1 g of the polymer in 15 ml of toluene, slowly pouring it into 30 ml of methanol to reprecipitate, and drying under reduced pressure.

(Examples and comparative examples)
According to the formulation shown in Table 1, using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., materials other than sulfur and vulcanization accelerator are kneaded under the condition of 150 ° C. for 5 minutes to prepare the kneaded product. Obtained. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded for 5 minutes under the condition of 80 ° C. using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is formed into a tread shape and bonded together with other tire members to form an unvulcanized tire, which is press-vulcanized for 12 minutes under the condition of 150 ° C. to obtain a test tire (test tire). Size: 195 / 65R15) was manufactured. The following evaluations were performed using the obtained test tires, and the results are shown in Table 1.
In Table 1, the rubber content in the oil-extended rubber is described in the rubber column, and the oil content in the oil-extended rubber is added to the oil column.

(Wet grip performance)
Each test tire was attached to all wheels of the vehicle (domestic FF2000cc), the braking distance from the initial speed of 100km / h was obtained on a wet asphalt road surface, and the index was displayed when Comparative Example 1 was set to 100 (wet). Grip performance index). The larger the index, the shorter the braking distance and the better the wet grip performance.

(Fuel efficiency)
Using a rolling resistance tester, the rolling resistance when each test tire was run at a rim (15 x 6JJ), internal pressure (230 kPa), load (3.43 kN), and speed (80 km / h) was measured. It is displayed as an index when Comparative Example 1 is set to 100 (fuel efficiency index). The larger the index, the smaller the rolling resistance and the better the fuel efficiency.

(Maneuvering stability)
A test piece cut out from the tread of each test tire was subjected to E * under the conditions of a temperature of 70 ° C., an initial strain of 10%, and a dynamic strain of 2% using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.). It was measured and displayed as an index when Comparative Example 1 was set to 100 (steering stability index). The larger the index, the larger the E *, indicating that the steering stability is excellent.

(Abrasion resistance)
Each test tire is attached to all wheels of the vehicle (domestic FF2000cc), the groove depth of the tire tread after a mileage of 8000 km is measured, and the mileage when the tire groove depth is reduced by 1 mm is calculated and compared. It is expressed as an index when Example 1 is set to 100 (wear resistance index). The larger the index, the longer the mileage and the better the wear resistance.

From Table 1, the target wet grip performance was improved in the examples as compared with the comparative examples. In addition, the overall performance of wet grip performance, fuel efficiency, steering stability and wear resistance (total of each index) was also better than that of the comparative example.

Claims (5)

A rubber component having a total content of styrene-butadiene rubber and butadiene rubber of 90% by mass or more,
Silica having a content of 50 parts by mass or more with respect to 100 parts by mass of the rubber component, and
Contains liquid isoprene rubber,
A rubber composition for a tire that satisfies the following formulas (A) and (B).
(A) α ≧ 30
(B) α / β ≧ 3
α: Total amount of vinyl in styrene-butadiene rubber and butadiene rubber [mass%]
β: Content of liquid isoprene rubber with respect to 100 parts by mass of rubber component [parts by mass] The rubber composition for a tire according to claim 1, which contains a mercapto-based silane coupling agent. The rubber composition for a tire according to claim 1 or 2, wherein the styrene-butadiene rubber and the total amount of styrene in the butadiene rubber are 10% by mass or less. The rubber composition for a tire according to any one of claims 1 to 3, wherein the silica has a nitrogen adsorption specific surface area of 200 m ² / g or more. A pneumatic tire produced by using the rubber composition according to any one of claims 1 to 4.