JP7102925B2 - 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, not only automobiles are required to have low fuel consumption, but also rubber compositions used for automobile tires are required to be provided with good wear resistance and the like. There is.

Tires are required to have grip performance such as dry grip performance and wet grip performance in order to ensure safety. In order to meet this demand, styrene-butadiene rubber is widely used as a rubber component, but when styrene-butadiene rubber is used, the wear resistance tends to decrease. As described above, the grip performance and the wear resistance are in a contradictory relationship, and it is difficult to comprehensively improve them.

The present invention provides a rubber composition for a tire capable of solving the above problems and comprehensively improving wear resistance, wet grip performance and dry grip performance, and a pneumatic tire produced by using the rubber composition. With the goal.

The present invention contains a styrene-butadiene rubber and a rubber component containing butadiene rubber and silica having a content of 60 parts by mass or more with respect to 100 parts by mass of the rubber component, and the styrene-butadiene rubber is composed of a plurality of styrene-butadiene rubbers. The plurality of styrene-butadiene rubbers relate to a rubber composition for a tire in which the difference in the amount of styrene is 10% by mass or more and the difference in the amount of vinyl in each is 20% by mass or more.

It is preferable that the content of locis butadiene rubber having a cis content of 50% by mass or less is 10% by mass or more in 100% by mass of the rubber component.

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

The rubber composition preferably contains a styrene resin and satisfies the following formula (A).
(A) α / β ≦ 4
α: Total amount of styrene in rubber component [mass%]
β: Content of styrene resin 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 pneumatic tires made using the rubber composition.

According to the present invention, a plurality of styrene-butadiene rubbers containing a styrene-butadiene rubber and a butadiene rubber and a predetermined amount of silica, and having a difference in the amount of styrene and a difference in the amount of vinyl within a specific range as the styrene-butadiene rubber. Since it is the rubber composition for tires used, wear resistance, wet grip performance and dry grip performance can be comprehensively improved.

The rubber composition for a tire of the present invention contains styrene-butadiene rubber (SBR) and butadiene rubber (BR) and a predetermined amount of silica, and the difference in the amount of styrene and the difference in the amount of vinyl are within a specific range as SBR. A plurality of SBRs are used.

The above-mentioned rubber composition has the above-mentioned effect, and it is presumed that this is achieved by the following effects.
When SBR is the main component of the rubber component, the grip performance tends to be improved, but the wear resistance tends to decrease. On the other hand, in the above rubber composition, BR is used as a rubber component other than SBR, the amount of silica is adjusted to a specific range, and further, the difference in the amount of styrene and the difference in the amount of vinyl are specific as the SBR. By using a plurality of SBRs within the range, silica is well dispersed in the rubber composition. As a result, wear resistance, wet grip performance and dry grip performance are considered to be comprehensively improved.

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 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) and an amide group are 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, 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 or the like described in JP-A-2010-111753) is preferably used.

As ^R1 , ^R2 and R3 ^, an alkoxy group is preferable (preferably an alkoxy group having 1 to 8 carbon atoms, and more preferably an alkoxy group having 1 to 4 carbon atoms). As R ⁴ and R ⁵ , an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is preferable. 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 modifiers include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, and 2-diethylaminoethyltri. Examples thereof include methoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. 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) carbamate chloride, 4-morpholincarbonyl chloride, 1-pyrrolidincarbonyl chloride, N, N-dimethylcarbamide, and N, N-diethylcarbamide chloride; 1 , 3-Bis- (glycidyloxypropyl) -tetramethyldisiloxane, (3-glycidyloxypropyl) -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 an amino group and / or a substituted amino group such as benzophenone, N, N, N', N'-bis- (tetraethylamino) benzophenone; 4-N, N-dimethylaminobenzaldehyde, 4- A benzaldehyde compound 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, Nt-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-laurillolactam, N-vinyl-ω-laurylolactum, 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.

In the rubber composition, the SBR is composed of a plurality of SBRs.
In the plurality of SBRs, the difference in the amount of each styrene may be 10% by mass or more, preferably 12% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less. .. Similarly, in the plurality of SBRs, the difference in the amount of vinyl may be 20% by mass or more, preferably 28% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass. It is as follows. Within the above range, the effect of the present invention tends to be obtained better.

At least one of the plurality of SBRs has a styrene content of preferably 20% by mass or more, more preferably 25% 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.

At least one of the plurality of SBRs has a vinyl content of 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.

At least one of the plurality of SBRs has a weight average molecular weight (Mw) of preferably 150,000 or more, more preferably 450,000 or more, and preferably 1.2 million or less, more preferably 900,000 or less. Within the above range, the effect of the present invention tends to be obtained better.
Mw and Mn are measured values 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 based on.

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 (total content of a plurality of SBRs) is preferably 60% by mass or more, more preferably 75% by mass or more, and preferably 90% by mass or less, more preferably. Is 85% by mass or less. Within the above range, the effect of the present invention tends to be obtained better.

The rubber composition contains BR as a rubber component.
The BR is not particularly limited, and BR having a high cis content, BR having a low 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. Among them, losis butadiene rubber (rosis BR) having a cis content of 50% by mass or less is preferable. The cis content of locis BR is preferably 40% by mass or less, and preferably 5% by mass or more.
The cis content can be measured by infrared absorption spectrum analysis.

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

When Rosis BR is contained, the content of Rosis BR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 15% by mass or more, and preferably 40% by mass or less, more preferably. It is 35% by mass or less. Within the above range, the effect of the present invention tends to be obtained better.

The content of BR in 100% by mass of the rubber component (total content of Rosis BR and other BR) is preferably 10% by mass or more, preferably 15% by mass or more, and preferably 40% by mass or less. More preferably, it is 35% 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 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.

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.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 110 m ² / g or more, more preferably 150 m ² / g or more, still more preferably 200 m ² / g or more, and particularly preferably 220 m ² / g or more. Further, it is preferably 300 m ² / g or less, and 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., and Tokuyama Corporation can be used.

The content of silica with respect to 100 parts by mass of the rubber component may be 60 parts by mass or more, preferably 70 parts by mass or more, more preferably 85 parts by mass or more, and preferably 120 parts by mass or less, more preferably. Is 105 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 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, 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- Sulfates such as triethoxysilylpropylmethacrylate monosulfide, mercaptos such as 3-mercaptopropyltrimethoxysilane and 2-mercaptoethyltriethoxysilane, vinyls 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 and 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 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、－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 , -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 of hydrogen atom or carbon number 1-18. 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 −. [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 having 1 to 18 carbon atoms. The group, R ¹⁰⁰⁵ , represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, and x, y and z have a relationship of x + y + 2z = 3, 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, 0 ≦ z ≦ 1. It is a number that satisfies.)

(In the formula, v is an integer of 0 or more, w is an integer of 1 or more. R ¹¹ is hydrogen, halogen, an alkyl group having 1 to 30 carbon atoms branched or unbranched, and 2 to 2 carbon atoms branched or unbranched. 30 alkenyl groups, branched or non-branched 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 ¹² has branched or non-branched 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 alkaneylene 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 an aralkylene group having 7 to 18 carbon atoms. The alkylene group and the alkaneylene 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, or 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 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.

Regarding ^R12 in the formulas (I) and (II), examples of the branched or non-branched alkylene group having 1 to 30 carbon atoms include an ethylene group and a propylene group. 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 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 a styrene resin. Thereby, the effect of the present invention tends to be obtained better.
The styrene-based resin is a polymer containing a styrene-based monomer as a constituent monomer, and examples thereof include a polymer obtained by polymerizing a styrene-based monomer as a main component (50% by mass or more). Specifically, styrene-based monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, A homopolymer obtained by independently polymerizing o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.), a copolymer obtained by copolymerizing two or more types of styrene-based monomers, and a styrene-based monomer. And a copolymer with another monomer that can copolymerize with this.

Other monomers include acrylonitrile 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. Conjugate 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; and the like can be exemplified. These may be used alone or in combination of two or more.

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

The softening point of the styrene 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 6220-1: 2001 is measured by a ring-ball type softening point measuring device.

The number average molecular weight (Mn) of the styrene resin is preferably 500 or more, more preferably 700 or more, and preferably 3000 or less, more preferably 2000 or less. Within the above range, the effect of the present invention tends to be obtained better.

When the styrene-based resin is contained, the content of the styrene-based resin is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and further preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. Further, it is preferably 70 parts by mass or less, more preferably 50 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 styrene resin. The other resins are not particularly limited as long as they are widely used in the tire industry, and are rosin-based resins, kumaron inden resins, terpene-based resins, pt-butylphenol acetylene resins, acrylic resins, C5 resins, and the like. Examples include C9 resin. These may be used alone or in combination of two or more.

Commercially available products of styrene resin and other resins 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. Products such as Petrochemical Co., Ltd., Nippon Catalyst Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., and Taoka Chemical Industry Co., Ltd. can be used.

In the rubber composition, it is preferable that the total amount of styrene in the rubber component and the content of the styrene-based resin satisfy the following formula (A). Thereby, the effect of the present invention tends to be obtained better.
(A) α / β ≦ 7
α: Total amount of styrene in rubber component [mass%]
β: Content of styrene resin with respect to 100 parts by mass of rubber component [parts by mass]

In the formula (A), α / β may be 7 or less, preferably 4 or less, more preferably 2 or less, and preferably 0.1 or more, more preferably 0.5 or more. .. Within the above range, the effect of the present invention tends to be obtained better.

The total amount of styrene in the rubber component (total content of the styrene portion contained in the total amount of the rubber component) may be adjusted within a range satisfying the formula (A), but is preferably 10% by mass or more, more preferably 20% by mass. % Or more, more preferably 23% by mass, and preferably 40% by mass or less, more preferably 30% by mass or less. Within the above range, the effect of the present invention tends to be obtained better.
Here, the total amount of styrene in the rubber component is Σ (content of each styrene-containing rubber × amount of styrene of each styrene-containing rubber / 100). For example, when the rubber component is composed of 90% by mass of SBR (A) (40% by mass of styrene amount), 5% by mass of SBR (B) (25% by mass of styrene amount), and 5% by mass of BR, the total amount of styrene in the rubber component. Is 37.25% by mass (= 90 × 40/100 + 5 × 25/100).

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 nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 90 m ² / g or more, more preferably 111 m ² / g or more, and preferably 180 m ² / g or less, more preferably 150 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.

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 20 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 effect of the present invention can be obtained more preferably.

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-based 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 10 parts by mass or more, and preferably 50 parts by mass or less, more preferably 50 parts by mass or more, based on 100 parts by mass of the rubber component. It is 40 parts by mass or less, more preferably 35 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 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-based 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 wax is contained, the content of 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 effect of the present invention tends to be obtained better.

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 anti-aging agents such as styrenated phenol; tetrakis- [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] bis, tris, polyphenolic aging such as methane Preventive agents and the like can be mentioned. 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 3.5 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.

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.
Conventionally known zinc oxide 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 of 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. and the like 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 vulcanization accelerator include thiazole-based vulcanization 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 vulcanization accelerators; N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl- 2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N, N'-diisopropyl-2-benzothiazolesulfenamide, etc. Sulfenamide-based vulcanization accelerator; guanidine-based vulcanization 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 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 effect of the present invention tends to be obtained better.

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 pneumatic tire can be used for passenger car tires, truck / bus tires, motorcycle 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: Modified SBR synthesized in Production Example 1 below (styrene amount: 25% by mass, vinyl amount: 60% by mass, Mw: 150,000)
SBR2: Modified SBR synthesized in Production Example 2 below (styrene amount: 40% by mass, vinyl amount: 30% by mass, Mw: 900,000)
SBR3: Buna VSL 5228-2 manufactured by LANXESS (styrene amount: 28% by mass, vinyl amount: 52% by mass, oil content 37.5 parts by mass with respect to 100 parts by mass of rubber solid content)
SBR4: SLR6430 manufactured by Dow (styrene amount: 40% by mass, vinyl amount: 24% by mass, oil content 37.5 parts by mass with respect to 100 parts by mass of rubber solid content)
BR: N103 manufactured by Asahi Kasei Chemicals Co., Ltd. (cis content: 38% by mass)
Carbon Black 1: N134 (N ₂ SA: 146m ² / g) manufactured by Asahi Carbon Co., Ltd.
Carbon Black 2: N220 manufactured by Mitsubishi Chemical Corporation (N ₂ SA: 111m ² / g)
Silica 1: Ultrasil 9000GR manufactured by Evonik Degussa (N ₂ SA: 240m ² / g)
Silica 2: Ultrasil VN3 manufactured by Evonik Degussa (N ₂ SA: 167m ² / g)
Silica 3: ZEOSIL 1115MP manufactured by Rhodia (N ₂ SA: 115m 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.
Oil: VIVATEC500 (TDAE oil) manufactured by H & R
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.)
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 NS (N-tert-butyl) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd. -2-Benzothiazolyl vulcan amide)
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 reaches 99%, 1,3-butadiene is added, and after further polymerization for 5 minutes, N, N-bis (trimethylsilyl) -3-aminopropyltriethoxysilane is added as a denaturant. The reaction was carried out. 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 SBR2.

(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, and the kneaded product is kneaded. 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.

(Abrasion resistance)
Each test tire is mounted on all wheels of a 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 3 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. In this embodiment, the target is 60 or more.

(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 3 was set to 100 (wet). Grip performance index). The larger the index, the shorter the braking distance and the better the wet grip performance. In this embodiment, the target is 120 or more.

(Dry grip performance)
Each test tire was attached to all wheels of the vehicle (domestic FF2000cc), and the actual vehicle ran 10 laps on the test course on the dry asphalt road surface. The test site was the Okayama test course of Sumitomo Rubber Industries, Ltd., and the temperature was 20 to 25 ° C. Then, the test driver evaluated the stability of the control at the time of steering at that time, and displayed it as an index when Comparative Example 3 was set to 100 (dry grip performance index). The larger the index, the better the grip performance on the dry road surface. In this embodiment, the target is 80 or more.

Claims (6)

Styrene-butadiene rubber and rubber components containing butadiene rubber,
Silica having a content of 60 parts by mass or more with respect to 100 parts by mass of the rubber component , and
Contains styrene resin ,
The styrene-butadiene rubber is composed of a plurality of styrene-butadiene rubbers.
The plurality of styrene-butadiene rubbers have a difference in the amount of styrene of 10% by mass or more and a difference in the amount of vinyl of 20% by mass or more .
A rubber composition for a tire satisfying the following formula (A) .
(A) α / β ≦ 4
α: Total amount of styrene in rubber component [mass%]
β: Content of styrene resin 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 content of locis butadiene rubber having a cis content of 50% by mass or less in 100% by mass of the rubber component is 10% by mass or more. 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, wherein the plurality of styrene-butadiene rubbers have a difference in the amount of vinyl of 28 to 40% by mass . 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.