JP6973048B2 - Rubber composition for tires and pneumatic tires - Google Patents

Description

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

In recent years, due to growing interest in environmental issues, there is a growing demand for fuel efficiency in automobiles, and rubber compositions used in automobile tires are also required to have excellent fuel efficiency. ..

As a method for improving fuel efficiency, for example, a method of reducing the amount of the reinforcing filler is known, but in this method, the wet grip performance and wear resistance are reduced due to the decrease in the calorific value and the reinforcing property of the rubber composition. Tends to get worse. As described above, these performances are generally contrary to the fuel efficiency, and it is difficult to obtain the respective performances in a well-balanced manner.

The present invention provides a rubber composition for a tire having improved fuel efficiency, wet grip performance and wear resistance in a well-balanced manner by solving the above problems, and a pneumatic tire produced by using the rubber composition. The purpose.

The present invention includes a rubber component having a styrene-butadiene rubber content of 75 to 100% by mass, an aromatic resin having a number average molecular weight of 3000 or less, a structural unit based on styrene, and a structural unit based on conjugated diene. The present invention relates to a rubber composition for a tire containing a liquid polymer having a number average molecular weight of 7,000 or less and silica having a content of 90 to 130 parts by mass with respect to 100 parts by mass of the rubber component, and satisfying the following formulas (A) and (B). ..
(A) α1 / (β1 + β2) ≦ 5.5
(B) β2 / β1 ≧ 1
α1: Silica content with respect to 100 parts by mass of rubber component [parts by mass]
β1: Content of aromatic resin with respect to 100 parts by mass of rubber component [parts by mass]
β2: Content of liquid polymer with respect to 100 parts by mass of rubber component [parts by mass]

The total content of the butadiene rubber and the isoprene-based rubber is preferably 1 to 25% by mass in the 100% by mass of the rubber component.

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

The rubber composition preferably contains carbon black having a specific surface area of cetyltrimethylammonium bromide of 150 m ^{2 / g or more.}

The rubber composition preferably contains carbon black and satisfies the following formula (C).
(C) α2 / α1 ≦ 0.1
α1: Silica content with respect to 100 parts by mass of rubber component [parts by mass]
α2: Content of carbon black with respect to 100 parts by mass of rubber component [parts by mass]

The nitrogen adsorption specific surface area of the silica ^{is preferably 220 m 2} / g or more.

The present invention also relates to a pneumatic tire produced using the rubber composition.

According to the present invention, a tire rubber containing a predetermined amount of styrene-butadiene rubber, a specific aromatic resin, a specific liquid polymer, and a predetermined amount of silica to satisfy the formulas (A) and (B). Since it is a composition, it can improve fuel efficiency, wet grip performance and wear resistance in a well-balanced manner.

The rubber composition for a tire of the present invention contains a predetermined amount of styrene-butadiene rubber (SBR), a specific aromatic resin, a specific liquid polymer, and a predetermined amount of silica, and the formula (A), ( B) is satisfied.

The above-mentioned rubber composition has the above-mentioned effect, and it is presumed that this is achieved by the following action and effect.
Both the aromatic resin and the liquid polymer have a structural unit similar to that of styrene, and have good compatibility with SBR. After blending these with a predetermined amount of silica, the amount of silica and the total amount of the aromatic resin and the liquid polymer are adjusted to a specific ratio, and further, the aromatic resin and the liquid polymer are further adjusted. By adjusting the amount of silica to a specific ratio, silica, the aromatic resin and the liquid polymer are well dispersed in the rubber composition. As a result, it is considered that fuel efficiency, wet grip performance and wear resistance are significantly (synergistically) improved in a well-balanced manner.

The rubber composition contains SBR as a rubber component.
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 any 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 terminal), 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 (coupled) and has a hydroxyl group. And end-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 suitable.

(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 may be the same or different and represent a hydrogen atom or an alkyl group. R ⁴ and R ⁵ may be combined 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 end (active end) of solution-polymerized styrene-butadiene rubber (S-SBR) using the compound represented by the above formula. Modified SBR (modified SBR or the like described in JP-A-2010-111753) is preferably used.

Alkoxy groups are suitable for R ¹ , R ² and R ³ (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group 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 such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, polyepoxidized liquid polybutadiene; 4,4'-diglycidyl-diphenyl Epoxy group-containing tertiary amines such as methylamine, 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N, N'-diglycidyl-4-glycidyloxyaniline, diglycidyl orthotoluidine, tetraglycidylmethoxylidineamine , Tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, tetraglycidyl-1,3-bisaminomethylcyclohexane and other diglycidylamino compounds;

Amino group-containing acid chlorides such as bis- (1-methylpropyl) carbamate chloride, 4-morpholincarbonyl chloride, 1-pyrrolidincarbonyl chloride, N, N-dimethylcarbamide chloride, N, N-diethylcarbamide 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- (methyldisilyl) 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) ) A (thio) benzophenone compound having an amino group and / or a substituted amino group 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 pyrrolidone 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-laurylolactum, N-vinyl-ω-laurylolactum, N -N-substituted lactams such as methyl-β-propiolactam, N-phenyl-β-propiolactam; etc.

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-propanol, 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 the SBR is preferably 10% by mass or more, more preferably 25% by mass or more, further preferably 35% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less. Within the above range, the effect of the present invention tends to be obtained better.
The amount of styrene can be measured by the method described in Examples described later.

The vinyl content of SBR is preferably 15% by mass or more, more preferably 24% by mass or more, and preferably 70% by mass or less, more preferably 60% by mass or less. Within the above range, the effect of the present invention tends to be obtained better.
The amount of vinyl (1,2-bonded butadiene unit amount) can be measured by the method described in Examples described later.

The weight average molecular weight (Mw) of SBR is preferably 100,000 or more, more preferably 150,000 or more, and preferably 1.5 million or less, more preferably 1.36 million or less. Within the above range, the effect of the present invention tends to be obtained better.
Mw is based on the measured value by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation). Can be obtained by standard polystyrene conversion.

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

The content of SBR in 100% by mass of the rubber component may be 75 to 100% by mass, but is preferably 90% by mass or less, and more preferably 80% by mass or less. Within the above range, the effect of the present invention tends to be obtained better.

Rubber components that can be used other than SBR include isoprene-based rubber, butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). And the like, butadiene rubber can be mentioned. These diene-based rubbers may be used alone or in combination of two or more. Of these, isoprene-based rubber and BR are preferable, and BR is more preferable.

Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR and the like. As the NR, for example, SIR20, RSS # 3, TSR20 and the like, which are common in the tire industry, can be used. The IR is not particularly limited, and for example, IR2200 or the like, which is common in the tire industry, can be used. Modified NR includes deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., and modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of the modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber and the like. 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 10% by mass or more, and preferably 25% by mass or less. .. Within the above range, the effect of the present invention tends to be obtained better.

The BR is not particularly limited, and BR having a high cis content, 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. In particular, the cis content of BR is preferably 90% by mass or more (preferably 95% by mass or more) because the wear resistance is improved. The cis content can be measured by infrared absorption spectrum analysis.

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

When BR is contained, the content of BR in 100% by mass of the rubber component is preferably 1% by mass or more, more preferably 10% by mass or more, and preferably 25% by mass or less. Within the above range, the effect of the present invention tends to be obtained better.

The total content of BR and isoprene-based rubber in 100% by mass of the rubber component is preferably 1% by mass or more, more preferably 10% by mass or more, and preferably 25% by mass or less. Within the above range, the effect of the present invention tends to be obtained better.

The rubber composition contains an aromatic resin having a number average molecular weight (Mn) of 3000 or less.
The aromatic resin is a polymer that is solid at 20 ° C. using a monomer having a benzene ring as a constituent monomer, and a polymer obtained by polymerizing the monomer as a main component (50% by mass or more) is used. Can be mentioned. Specifically, styrene-based monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, Examples thereof include styrene-based resins obtained by polymerizing o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.), and the styrene-based resin includes a single weight obtained by polymerizing a styrene-based monomer independently. In addition to a copolymer obtained by copolymerizing two or more kinds of styrene-based monomers, a copolymer of a styrene-based monomer and another monomer capable of copolymerizing with the styrene-based monomer can also be mentioned.

Examples of other monomers include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, terpene and chloroprene. Examples thereof include conjugated dienes such as butadiene isoprene, olefins such as 1-butene and 1-pentene; α, β-unsaturated carboxylic acids such as maleic anhydride or acid anhydrides thereof; These may be used alone or in combination of two or more.

As the aromatic resin, a phenol-based resin using phenol as a constituent monomer can also be used. Examples of the phenolic resin include phenolic resins and terpene phenolic resins. These may be used alone or in combination of two or more.

The aromatic resin is preferably a styrene resin, and is preferably an α-methylstyrene resin (α-methylstyrene homopolymer, α-methylstyrene, etc.) because the effects of the present invention tend to be obtained better. (Polymer with styrene, etc.) is more preferable, and the copolymer of α-methylstyrene and styrene is further preferable.

The softening point of the aromatic resin is preferably 30 ° C. or higher, more preferably 60 ° C. or higher, and preferably 120 ° C. or lower, more preferably 85 ° C. or lower. Within the above range, the effect of the present invention tends to be obtained better.
In the present invention, the softening point of the resin is the temperature at which the ball drops when the softening point defined in JIS K 62201: 2001 is measured by a ring-ball type softening point measuring device.

The number average molecular weight (Mn) of the aromatic resin may be 3000 or less, preferably 2000 or less, more preferably 1000 or less, and preferably 100 or more, more preferably 300 or more. Within the above range, the effect of the present invention tends to be obtained better.
Mn can be obtained by the same method as Mw.

The content of the aromatic resin with respect to 100 parts by mass of the rubber component may be appropriately adjusted within a range satisfying the formulas (A) and (B), but is preferably 1 part by mass or more, more preferably 5 parts by mass or more. Also, it is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and further preferably 10 parts by mass or less. Within the above range, the effect of the present invention tends to be obtained better.

The rubber composition may contain other resins in addition to the aromatic resins. The other resins are not particularly limited as long as they are widely used in the tire industry, and are rosin-based resins other than rosin ester resins, kumaron inden resins, terpene-based resins, pt-butylphenol acetylene resins, and acrylic-based resins. Examples thereof include resin, C5 resin, and C9 resin. These may be used alone or in combination of two or more.

Examples of commercially available aromatic resins and other resins include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Toso Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Ltd., and Arizona Chemical Co., Ltd. Products such as Nikko Chemical Co., Ltd., Nippon Catalyst Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., and Taoka Chemical Industry Co., Ltd. can be used.

The rubber composition contains a styrene-based structural unit and a conjugated diene-based structural unit, and contains a liquid polymer having a number average molecular weight of 7,000 or less.
The liquid polymer is a polymer liquid at 20 ° C. using styrene and conjugated diene as constituent monomers. Specific examples thereof include a copolymer obtained by copolymerizing styrene with a conjugated diene (butadiene, isoprene, farnesene, myrcene, etc.). As the conjugated diene, one kind may be used alone, or two or more kinds may be used in combination. Of these, butadiene is preferable. That is, the liquid polymer is preferably a liquid styrene-butadiene copolymer.

Further, the liquid polymer may be a copolymer of styrene and another monomer copolymerizable with the conjugated diene. As the other monomer, the same monomer as those exemplified for the above aromatic resin can be used.

The number average molecular weight (Mn) of the liquid polymer may be 7,000 or less, preferably 5500 or less, more preferably 4500 or less, and preferably 3500 or more. Within the above range, the effect of the present invention tends to be obtained better.

The content of the liquid polymer with respect to 100 parts by mass of the rubber component may be appropriately adjusted within a range satisfying the formulas (A) and (B), but is preferably 5 parts by mass or more, more preferably 15 parts by mass or more. Further, it is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 20 parts by mass or less. Within the above range, the effect of the present invention tends to be obtained better.

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 has 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 effect of the present invention tends to be obtained better.
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 adjusted in the range of 90 to 130 parts by mass and in the range satisfying the formula (A), but is preferably 100 parts by mass or more, and is preferably 125. It is less than the mass part. Within the above range, the effect of the present invention tends to be obtained better.

In the rubber composition, the content of silica, the content of aromatic resin, and the content of liquid polymer satisfy the following formulas (A) and (B).
(A) α1 / (β1 + β2) ≦ 5.5
(B) β2 / β1 ≧ 1
α1: Silica content with respect to 100 parts by mass of rubber component [parts by mass]
β1: Content of aromatic resin with respect to 100 parts by mass of rubber component [parts by mass]
β2: Content of liquid polymer with respect to 100 parts by mass of rubber component [parts by mass]

In the formula (A), α1 / (β1 + β2) may be 5.5 or less, preferably 4.8 or less, more preferably 4.4 or less, and preferably 1.5 or more. It is preferably 2.5 or more, and more preferably 3 or more. Within the above range, the effect of the present invention tends to be obtained better.

In the formula (B), β2 / β1 may be 1 or more, preferably 1.3 or more, more preferably 1.5 or more, and preferably 4 or less, more preferably 3 or less. .. Within the above range, the effect of the present invention tends to be obtained better.

The rubber composition preferably contains a silane coupling agent together with silica. Thereby, the effect of the present invention tends to be obtained better.
The silane coupling agent is not particularly limited, and for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, and the like. 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-based such as triethoxysilane and 3-aminopropyltrimethoxysilane, glycidoxy-based 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, a sulfide type and a mercapto type are preferable, and a mercapto type is more preferable, because the effect of the present invention can be obtained more satisfactorily.

As the mercapto-based silane coupling agent, in addition to the 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、−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Ｒ^１００１、Ｒ^１００２、水素原子又は−［Ｏ（Ｒ^１００９Ｏ）_ｊ］_０．５−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、ｘは０以上の整数、ｙは１以上の整数である。Ｒ^１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^２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^１とＲ^２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 , -ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , -NR ¹⁰⁰⁶ R ^{1007 and-} ( The monovalent groups (R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ^{1008 ) selected from the OSiR 1006} R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) may be the same or different, each having a hydrogen atom or 1 to 18 carbon atoms. It is a monovalent hydrocarbon group, 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 R. ¹⁰⁰¹ , R ^{1002 , hydrogen atom or-} [O (R 1009 O) _j ] _0.5- group (R ¹⁰⁰⁹ is an alkylene group having 1 to 18 carbon atoms, j is an integer of 1 to 4), R ^1004. divalent hydrocarbon group having 1 to 18 carbon ^{atoms, R 1005} represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, x, y and z is, x + y + 2z = 3,0 ≦ x ≦ 3,0 It is a number that satisfies the relationship of ≦ y ≦ 2 and 0 ≦ z ≦ 1.)

(In the equation, x is an integer of 0 or more, y is an integer of 1 or more. R ¹ 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 groups or carboxyl groups. R ² has branched or unbranched carbon atoms. It represents an alkylene group of 1 to 30, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, or a branched or unbranched alkynylene group having 2 to 30 carbon atoms. A ring structure is formed by ^{R 1} and R ^2. 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 it is a group selected from the group consisting of. 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 is particularly preferable.

^{Specific examples of R 1002} , R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ^{1008 in} the formula (S1) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group and a 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 trill 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-hexanoi 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, and 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 end 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 may form a unit corresponding to the formulas (I) and (II) representing the binding units A and B. ..

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

For formula (I), ^{R 2} in (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 unbranched 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 (x) of the binding unit A and the number of repetitions (y) of the binding unit B. The total number of repetitions (x + y) is preferably in the range of 3 to 300.

When the 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 effect of the present invention tends to be obtained better.

The rubber composition preferably contains carbon black. Thereby, the effect of the present invention tends to be obtained better.
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 cetyltrimethylammonium bromide (CTAB) is preferably 150 m ² / g or more, more preferably 160 m ² / g or more, and preferably 250 m ² / g or less, more preferably 200 m ² / g. It is as follows. Within the above range, the effect of the present invention tends to be obtained better.
The CTAB specific surface area of carbon black is a value measured in accordance with JIS K6217-3: 2001.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 160 m ² / g or more, more preferably 179 m ² / g or more, and preferably 250 m ² / g or less, more preferably 200 m ² / g. It is as follows. Within the above range, the effect of the present invention tends to be obtained better.
The carbon black N ₂ SA is a value measured in accordance with JIS K6217-2: 2001.

The iodine adsorption amount (IA) of carbon black is preferably 160 mg / g or more, more preferably 166 mg / g or more, and preferably 250 mg / g or less, more preferably 200 mg / g or less. Within the above range, the effect of the present invention tends to be obtained better.
The carbon black IA is a value measured in accordance with JIS K6217-1: 2008.

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 20 parts by mass or less. Within the above range, the effect of the present invention can be obtained more preferably.

When carbon black is contained, it is preferable that the content of silica and the content of carbon black in the rubber composition satisfy the following formula (C). Thereby, the effect of the present invention tends to be obtained better.
(C) α2 / α1 ≦ 0.4
α1: Silica content with respect to 100 parts by mass of rubber component [parts by mass]
α2: Content of carbon black with respect to 100 parts by mass of rubber component [parts by mass]

In the formula (C), α2 / α1 may be 0.4 or less, preferably 0.2 or less, more preferably 0.1 or less, and preferably 0.01 or more, more preferably. It is 0.04 or more. Within the above range, the effect of the present invention tends to be obtained better.

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, a paraffin-based process oil, an aroma-based process oil, a 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 oils are preferable, and aroma-based process oils are more preferable, because the effects of the present invention can be obtained satisfactorily.

When oil is contained, the content of the oil is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and preferably 40 parts by mass or less, more preferably more preferably, with respect to 100 parts by mass of the rubber component. It is 30 parts by mass or less. Within the above range, the effect of the present invention tends to be obtained better.

The rubber composition may contain wax.
The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant waxes and animal waxes; synthetic waxes such as polymers 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 3 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 effect of the present invention tends to be obtained better.

The rubber composition may contain an anti-aging agent.
Examples of the antiaging agent include naphthylamine-based antiaging agents such as phenyl-α-naphthylamine; diphenylamine-based antiaging 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 antioxidants; quinoline-based antioxidants such as polymers 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 antiaging agents and quinoline-based antiaging 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 5 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 effect of the present invention tends to be obtained better.

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, 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 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 effect of the present invention tends to be obtained better.

The rubber composition may contain zinc oxide.
As the zinc oxide, conventionally known products can be used, for example, products of Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech 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 effect of the present invention tends to be obtained better.

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 1.5 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 5 parts by mass or less. Within the above range, the effect of the present invention tends to be obtained better.

The rubber composition may contain a vulcanization accelerator.
Examples of the sulfide accelerator include thiazole-based glucotase accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyldisulfide, and N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide (TMTD). ), Tetrabenzylthiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N) and other thiuram-based vulgurization 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 sulphurization accelerator; guanidine-based sulphurization 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 because the effects of the present invention can be obtained more preferably.

When the vulcanization accelerator is contained, the content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 5 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 effect of the present invention tends to be obtained better.

In addition to the above components, the rubber composition contains additives commonly 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 component 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 finish 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 in which the vulcanizing agent and the vulcanization accelerator are kneaded 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 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 a side reinforcing layer of a run-flat tire.

The pneumatic tire of the present invention is manufactured 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 pneumatic tire can be used for passenger car tires, truck / bus tires, two-wheeled vehicle tires, high-performance tires, and the like, and is particularly suitable for passenger car tires.

The present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.
The various chemicals used in the examples will be described below.
SBR1: SLR6430 manufactured by Dow (styrene amount: 40% by mass, vinyl amount: 24% by mass, Mw: 1.36 million, oil spreading rubber containing 37.5 parts by mass of oil with respect to 100 parts by mass of rubber)
SBR2: Modified SBR synthesized in Production Example 1 below (styrene amount: 25% by mass, vinyl amount: 60% by mass, Mw: 150,000)
SBR3: Modified SBR synthesized in Production Example 2 below (styrene amount: 40% by mass, vinyl amount: 30% by mass, Mw: 950,000)
BR: BR710 manufactured by Ube Industries, Ltd.
Carbon black: Prototype (CTAB: 160m ² / g, N ₂ SA: 179m ² / g, IA: 166mg / g)
Silica 1: Ultrasil 9000GR manufactured by Evonik Degussa (N ₂ SA: ^{240m 2} / g)
Silica 2: Zeosil 195GR manufactured by Rhodia (N ₂ SA: 180m 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: Naften-based process oil Styrene-based resin: Sylvatraxx4401 manufactured by Arizona Chemical Co., Ltd. (α-methylstyrene-based resin (copolymer of α-methylstyrene and styrene), Mn: 700, softening point: 85 ° C.)
Liquid polymer: RICON100 manufactured by Clay Valley (Liquid SBR, Mn: 4500)
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 sulfurization accelerator manufactured by Tsurumi Chemical Co., Ltd .1: Noxeller NS (N-tert-butyl) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. -2-Benzothiazolyl sulfenamide)
Vulcanization accelerator 2: Noxeller D (1,3-diphenylguanidine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

(Manufacturing Example 1)
N, N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane was placed in a 100 ml volumetric flask under a nitrogen atmosphere, and anhydrous hexane was further added to prepare a terminal modifier.
N-Hexane, styrene, butadiene, and tetramethylethylenediamine were added to a pressure-resistant container sufficiently substituted with nitrogen, and the temperature was raised to 40 ° C. Next, after adding butyllithium, the temperature was raised to 50 ° C. and the mixture was stirred. Next, a silicon tetrachloride / hexane solution was added, and the mixture was stirred. Next, the above-mentioned terminal denaturing agent was added, and stirring was performed. After adding methanol in which 2,6-tert-butyl-p-cresol was dissolved in the reaction solution, the reaction solution was placed in a stainless steel container containing methanol to recover the aggregate. The obtained aggregate was dried under reduced pressure for 24 hours to obtain SBR2.

(Manufacturing Example 2)
Under a nitrogen atmosphere, 3-diethylaminopropyltrimethoxysilane was placed in a 100 ml volumetric flask, and anhydrous hexane was further added to prepare a terminal modifier.
N-Hexane, styrene, butadiene, and tetramethylethylenediamine were added to a pressure-resistant container sufficiently substituted with nitrogen, and the temperature was raised to 40 ° C. Next, after adding butyllithium, the temperature was raised to 50 ° C. and the mixture was stirred. Next, a silicon tetrachloride / hexane solution was added, and the mixture was stirred. Next, the above-mentioned terminal denaturing agent was added, and stirring was performed. After adding methanol in which 2,6-tert-butyl-p-cresol was dissolved in the reaction solution, the reaction solution was placed in a stainless steel container containing methanol to recover the aggregate. The obtained aggregate was dried under reduced pressure for 24 hours to obtain SBR3.

<Analysis of SBR>
The structure identification of SBR (measurement of styrene amount and vinyl amount) was performed using a device of 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 compounding contents shown in Tables 1 and 2, using a 1.7 L 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 and mixed. I got a paste. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded under the condition of 80 ° C. for 5 minutes 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 10 minutes under the condition of 170 ° 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 Tables 1 and 2.
In Tables 1 and 2, the amount of rubber is described in the column of SBR1 which is the oil-extended rubber, and the oil content in the oil-extended rubber is added to the column of oil.

(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. The index was expressed as an index when the standard formulation (Comparative Example 1 in Table 1 and Example 6 in Table 2) was set to 100 (fuel efficiency index). The larger the index, the better the fuel efficiency.

(Wet grip performance)
Each test tire was attached to all wheels of the vehicle (domestic FF2000cc), and the braking distance from the initial speed of 100 km / h was obtained on a wet asphalt road surface. It is displayed as an index when 6) is set to 100 (wet grip performance index). The larger the index, the shorter the braking distance and the better the wet grip performance.

(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 used as a reference. It is expressed as an index when the composition (Table 1 is Comparative Example 1 and Table 2 is Example 6) is set to 100 (wear resistance index). The larger the index, the longer the mileage when the tire groove depth is reduced by 1 mm, and the better the wear resistance.

From Tables 1 and 2, examples containing a predetermined amount of SBR, a specific aromatic resin, a specific liquid polymer, and a predetermined amount of silica and satisfying the formulas (A) and (B) are low. Fuel efficiency, wet grip performance and wear resistance have been significantly improved in a well-balanced manner.

Claims (6)

A rubber component having a styrene-butadiene rubber content of 75 to 100% by mass, and
Aromatic resins with a number average molecular weight of 3000 or less,
A liquid polymer containing a styrene-based structural unit and a conjugated diene-based structural unit and having a number average molecular weight of 7,000 or less.
And silica content of 90 to 130 parts by mass with respect to 100 parts by mass of the rubber component,
Contains carbon black ,
A rubber composition for a tire satisfying the following formulas (A), (B) and (C).
(A) α1 / (β1 + β2) ≦ 5.5
(B) β2 / β1 ≧ 1
(C) α2 / α1 ≦ 0.1
α1: Silica content with respect to 100 parts by mass of rubber component [parts by mass]
α2: Content of carbon black with respect to 100 parts by mass of rubber component [parts by mass]
β1: Content of aromatic resin with respect to 100 parts by mass of rubber component [parts by mass]
β2: Content of liquid polymer with respect to 100 parts by mass of rubber component [parts by mass] The rubber composition for a tire according to claim 1, wherein the total content of the butadiene rubber and the isoprene-based rubber is 1 to 25% by mass in 100% by mass of the rubber component. The rubber composition for a tire according to claim 1 or 2, which contains a mercapto-based silane coupling agent. The rubber composition for a tire according to any one of claims 1 to 3, which contains carbon black having a specific surface area of 150 m ^{2 / g or more.} The rubber composition for a tire according to any one of claims 1 to 4 , wherein the silica has a nitrogen adsorption specific surface area of 220 m ² / g or more. A pneumatic tire produced by using the rubber composition according to any one of claims 1 to 5.