JP7618970B2 - Rubber composition for tires and tires - Google Patents

Description

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

Various methods for improving fuel economy and wear resistance have been studied (see, for example, Patent Documents 1 and 2). However, in recent years, there has been a demand for further improvement in these overall performance characteristics.

JP 2000-344955 A JP 2017-141405 A

The present invention aims to provide a rubber composition for tires and a tire that can solve the above problems and improve the overall performance of fuel economy and abrasion resistance.

The present invention relates to a rubber composition for tires that contains a rubber component including styrene-butadiene rubber, butadiene rubber, and isoprene-based rubber, silica, and a mercapto-based silane coupling agent, and the content of the styrene-butadiene rubber ≧ the content of the isoprene-based rubber ≧ the content of the butadiene rubber, and the content of the styrene-butadiene rubber ≧ the content of the silica.

It is preferable that the silica content is greater than or equal to the isoprene-based rubber content.

It is preferable that the cis content of the butadiene rubber is 60% by mass or less.

It is preferable that the rubber composition contains carbon black and that the cis content of the butadiene rubber is greater than or equal to the carbon black content.

It is preferable that the rubber composition contains a resin and the content of the resin is less than or equal to the content of the isoprene-based rubber.

It is preferable that the average particle size of the silica is 16 nm or less.

The rubber composition preferably contains a dibenzylamine compound.

The rubber composition preferably contains a dialkyldithiophosphate compound.

The present invention also relates to a tire having a tread using the rubber composition.

The present invention is a rubber composition for tires that contains a rubber component including styrene-butadiene rubber, butadiene rubber, and isoprene-based rubber, silica, and a mercapto-based silane coupling agent, and the styrene-butadiene rubber content is greater than or equal to the isoprene-based rubber content greater than or equal to the butadiene rubber content, and the styrene-butadiene rubber content is greater than or equal to the silica content, resulting in good overall performance in terms of fuel economy and abrasion resistance.

The rubber composition for tires of the present invention contains a rubber component including styrene-butadiene rubber, butadiene rubber, and isoprene-based rubber, silica, and a mercapto-based silane coupling agent, and the styrene-butadiene rubber content is greater than or equal to the isoprene-based rubber content greater than or equal to the butadiene rubber content, and the styrene-butadiene rubber content is greater than or equal to the silica content.

The reason why the above-mentioned effects are obtained with the above-mentioned rubber composition is presumed to be as follows.
In the above rubber composition, styrene-butadiene rubber, butadiene rubber, isoprene-based rubber, silica and mercapto-based silane coupling agent are blended, and the relationship of the content of styrene-butadiene rubber ≧ the content of isoprene-based rubber ≧ the content of butadiene rubber and the relationship of the content of styrene-butadiene rubber ≧ the content of silica are satisfied, so that the dispersion of silica is promoted and the reaction of mercapto-based silane coupling agent proceeds well.By these actions, silica is uniformly dispersed (distributed) in the rubber component, and the reinforcing effect of silica is improved, and the overall performance of fuel economy and wear resistance is significantly improved.

The rubber composition contains a rubber component.
Here, the rubber component is a component that contributes to crosslinking, and generally has a weight average molecular weight (Mw) of 10,000 or more.

The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more, and is preferably 2,000,000 or less, more preferably 1,500,000 or less, even more preferably 1,000,000 or less, and particularly preferably 800,000 or less. Within the above range, the effect tends to be better.

In this specification, the weight average molecular weight (Mw) can be calculated based on the measured value obtained by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation) and converted into standard polystyrene.

From the viewpoint of overall performance such as fuel economy and abrasion resistance, it is preferable that the total amount of styrene in the rubber component of the above rubber composition is less than the total amount of vinyl in the rubber component.

The ratio of the total vinyl content in the rubber component to the total styrene content in the rubber component is preferably 1.05 or more, more preferably 1.20 or more, even more preferably 1.50 or more, and particularly preferably 1.60 or more, and is preferably 3.50 or less, more preferably 2.50 or less, even more preferably 2.00 or less, and particularly preferably 1.70 or less. Within the above range, the effect tends to be better.

The total amount of styrene in the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 12% by mass or more, and particularly preferably 15% by mass or more, and is preferably 35% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. Within the above range, the effect tends to be better obtained.

Here, the total amount of styrene in the rubber component is the total content (unit: mass%) of the styrene moieties contained in the entire rubber component, and can be calculated by Σ (content of each rubber component x amount of styrene in each rubber component/100). For example, if 100% by mass of the rubber component contains 85% by mass of SBR with a styrene content of 40% by mass, 5% by mass of SBR with a styrene content of 25% by mass, and 10% by mass of BR with a styrene content of 0% by mass, the total amount of styrene in the rubber component is 35.25% by mass (=85 x 40/100 + 5 x 25/100 + 10 x 0/100).

The total vinyl content in the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, and particularly preferably 27% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less, and particularly preferably 30% by mass or less. Within the above range, the effect tends to be better obtained.

Here, the total vinyl content in the rubber component is the total content (unit: mass%) of vinyl parts contained in the total rubber component, and can be calculated by Σ (content of each rubber component x vinyl content in each rubber component/100). For example, if 100 mass% of the rubber component contains 85 mass% SBR with a vinyl content of 30 mass%, 5 mass% SBR with a vinyl content of 20 mass%, and 10 mass% BR with a vinyl content of 10 mass%, the total vinyl content in the rubber component is 27.5 mass% (=85 x 30/100 + 5 x 20/100 + 10 x 10/100).

The styrene content and vinyl content in each rubber component can be measured by a nuclear magnetic resonance (NMR) method.
In addition, the total styrene amount and the total vinyl amount in the rubber component are calculated according to the above-mentioned formula in the examples of this specification, but they may be analyzed from the tire using, for example, a pyrolysis gas chromatograph mass spectrometer (Py-GC/MS) or the like.

The rubber composition contains styrene-butadiene rubber (SBR) as a rubber component.
The SBR is not particularly limited, and examples of the SBR that can be used include emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. Commercially available products include those from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc.

The styrene content of SBR is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass or more, and is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less. If it is within the above range, the effect tends to be better.

The vinyl content of the SBR is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 35% by mass or more, and particularly preferably 40% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less. If it is within the above range, the effect tends to be better.

The above-mentioned styrene amount and vinyl amount of SBR mean the styrene amount and vinyl amount of the SBR when there is one type of SBR, and mean the average styrene amount and average vinyl amount when there are multiple types of SBR.
The average styrene amount of SBR can be calculated by {Σ(content of each SBR × styrene amount of each SBR)}/total content of all SBRs. For example, when 100% by mass of the rubber component contains 85% by mass of SBR with a styrene amount of 40% by mass and 5% by mass of SBR with a styrene amount of 25% by mass, the average styrene amount of the SBR is 39.2% by mass (=(85×40+5×25)/(85+5)).
Similarly, the average vinyl content of SBR can be calculated by {Σ(content of each SBR × vinyl content of each SBR)}/total content of all SBRs. For example, when 100% by mass of the rubber component contains 85% by mass of SBR with a vinyl content of 30% by mass and 5% by mass of SBR with a vinyl content of 20% by mass, the average vinyl content of SBR is 29.4% by mass (=(85×30+5×20)/(85+5)).

The amount of SBR in 100% by mass of the rubber component is preferably 45% by mass or more, more preferably 55% by mass or more, and even more preferably 65% by mass or more, and is preferably 85% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less. Within the above range, the effect tends to be better obtained.

The rubber composition contains butadiene rubber (BR) as a rubber component.
The BR is not particularly limited, and may be a BR having a high cis content, a BR having a low cis content, a BR containing syndiotactic polybutadiene crystals, etc. Commercially available products include those of Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, etc.

The cis amount (cis content) of the BR is preferably 10% by mass or more, more preferably 25% by mass or more, and even more preferably 35% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less. When it is within the above range, the effect tends to be better obtained.
The cis amount of BR can be measured by infrared absorption spectroscopy.

The above-mentioned cis amount of BR means the cis amount of the BR when there is one type of BR, and means the average cis amount when there are multiple types of BR.
The average cis amount of BR can be calculated by {Σ(content of each BR × cis amount of each BR)}/total content of all BRs. For example, in 100% by mass of the rubber component, when 20% by mass of BR with a cis amount of 90% and 10% by mass of BR with a cis amount of 40% are present, the average cis amount of BR is 73.3% by mass (=(20×90+10×40)/(20+10)).

The BR content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less. Within the above range, the effect tends to be better obtained.

The rubber composition contains an isoprene-based rubber as a rubber component.
Examples of isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of NR include SIR20, RSS#3, TSR20, and other rubbers that are common in the tire industry. Examples of IR include, but are not limited to, IR2200 and other rubbers that are common in the tire industry. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), and other rubbers. Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more. Among these, NR is preferred.

The content of isoprene-based rubber in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, and is preferably 45% by mass or less, more preferably 35% by mass or less, and even more preferably 25% by mass or less. Within the above range, the effect tends to be better obtained.

In the above rubber composition, the SBR content is greater than or equal to the isoprene-based rubber content and greater than or equal to the BR content.

In the above rubber composition, the ratio of SBR content to isoprene-based rubber content is preferably 1.5 or more, more preferably 2.5 or more, even more preferably 3.0 or more, and is preferably 5.5 or less, more preferably 4.5 or less, even more preferably 3.5 or less, and particularly preferably 3.3 or less. Within the above range, the effect tends to be better obtained.

In the above rubber composition, the ratio of isoprene rubber content/BR content is preferably 1.1 or more, more preferably 1.2 or more, even more preferably 1.3 or more, and is preferably 3.0 or less, more preferably 2.0 or less, even more preferably 1.5 or less, and particularly preferably 1.4 or less. Within the above range, the effect tends to be better.

In these relationships, the SBR content, isoprene rubber content, and BR content are the contents (unit: mass%) in 100% by mass of the rubber component.

From the viewpoint of overall performance such as fuel economy and abrasion resistance, it is preferable that the content of isoprene-based rubber in the above rubber composition is equal to or greater than the total amount of styrene in the rubber component.

In the above rubber composition, the content of isoprene-based rubber/total amount of styrene in the rubber component is preferably 1.1 or more, and is preferably 2.5 or less, more preferably 1.8 or less, even more preferably 1.5 or less, and particularly preferably 1.3 or less. Within the above range, the effect tends to be better obtained.

In these relationships, the total amount of styrene in the rubber component is the total amount of styrene contained in the entire rubber component (unit: mass%), and the amount of isoprene-based rubber is the amount in 100 mass of the rubber component (unit: mass%).

Other than SBR, BR, and isoprene-based rubber, other usable rubber components include diene-based rubbers such as acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). These may be used alone or in combination of two or more.

The rubber component may be modified to introduce a functional group that interacts with a filler such as silica.
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, a disulfide 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. These functional groups may have a substituent. Among them, an amino group (preferably an amino group in which a hydrogen atom of an amino group is substituted 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 alkoxysilyl group having 1 to 6 carbon atoms) are preferred.

Specific examples of compounds (modifiers) having the above functional groups include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc.

The rubber composition contains silica.
Examples of silica include dry silica (anhydrous silicic acid) and wet silica (hydrated silicic acid), but wet silica is preferred because it has many silanol groups. Commercially available products include those from Rhodia, EVONIK, Tosoh Silica, Solvay Japan, and Tokuyama. These may be used alone or in combination of two or more.

The average particle size of the silica is preferably 20 nm or less, more preferably 17 nm or less, even more preferably 16 nm or less, and particularly preferably 15 nm or less, and is preferably 6 nm or more, more preferably 9 nm or more, and even more preferably 12 nm or more. If it is within the above range, the effect tends to be better.

In this specification, the average particle size of silica is measured by observation with a transmission electron microscope (TEM). Specifically, the silica particles are photographed with a transmission electron microscope, and if the particle shape is spherical, the diameter of the sphere is taken as the particle size. If the particle shape is needle-like or rod-like, the short diameter is taken as the particle size. If the particle shape is irregular, the average particle diameter from the center is taken as the particle diameter, and the average value of the particle diameters of 100 fine particles is taken as the average particle size.

The silica content is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, and particularly preferably 50 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 100 parts by mass or less, more preferably 75 parts by mass or less, even more preferably 65 parts by mass or less, and particularly preferably 60 parts by mass or less. Within the above range, the effect tends to be better obtained.

In the above rubber composition, the SBR content is greater than or equal to the silica content.

In the above rubber composition, the ratio of SBR content to silica content is preferably 1.1 or more, more preferably 1.2 or more, even more preferably 1.3 or more, and is preferably 3.5 or less, more preferably 2.5 or less, even more preferably 1.8 or less, and particularly preferably 1.5 or less. Within the above range, the effect tends to be better.

In these relationships, the SBR content is the content (unit: mass %) in 100% by mass of the rubber component, and the silica content is the content (unit: mass parts) per 100 parts by mass of the rubber component.

From the viewpoint of overall performance such as fuel economy and abrasion resistance, it is preferable that the silica content in the above rubber composition is greater than or equal to the isoprene-based rubber content.

In the above rubber composition, the silica content/isoprene-based rubber content is preferably 1.5 or more, more preferably 1.8 or more, even more preferably 2.0 or more, and particularly preferably 2.5 or more, and is preferably 5.5 or less, more preferably 4.5 or less, even more preferably 3.5 or less, and particularly preferably 3.0 or less. Within the above range, the effect tends to be better.

In these relationships, the silica content is the content (unit: parts by mass) relative to 100 parts by mass of the rubber component, and the isoprene-based rubber content is the content (unit: mass%) in 100% by mass of the rubber component.

The rubber composition contains a mercapto-based silane coupling agent.
The mercapto-based silane coupling agent is a silane coupling agent having a mercapto group, and examples thereof include 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, etc. As the mercapto-based silane coupling agent, a compound having a structure in which a mercapto group is protected by a protecting group (for example, a compound represented by the following formula (S1)) can also be used.

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

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

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

(In the formula, v is an integer of 0 or more, and w is an integer of 1 or more. R ¹¹ represents hydrogen, halogen, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, or an alkyl group in which the terminal hydrogen atom is substituted with a hydroxyl group or a carboxyl group. R ¹² represents a branched or unbranched alkylene group having 1 to 30 carbon atoms, 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. R ¹¹ and R ¹² may form a ring structure.)

In formula (S1), R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ are each preferably independently a group selected from the group consisting of a linear, cyclic or branched alkyl group, alkenyl group, aryl group and aralkyl group having 1 to 18 carbon atoms. When R ¹⁰⁰² is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is preferably a group selected from the group consisting of a linear, cyclic or branched alkyl group, alkenyl group, aryl group and aralkyl group. R ¹⁰⁰⁹ is preferably a linear, cyclic or branched alkylene group, particularly preferably a linear one. Examples of R ¹⁰⁰⁴ include 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, an arylene group having 6 to 18 carbon atoms, and an aralkylene group having 7 to 18 carbon atoms. The alkylene group and the alkenylene group may be either linear or branched, and the cycloalkylene group, the cycloalkylalkylene group, the arylene group, and the aralkylene group may have a functional group such as a lower alkyl group on the ring. As this 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 formula (S1) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a cyclopentyl group, a cyclohexyl group, a vinyl group, a propenyl group, an allyl group, a hexenyl group, an octenyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a benzyl group, a phenethyl group and a naphthylmethyl group.
Examples of R ¹⁰⁰⁹ in formula (S1) include linear alkylene groups such as a methylene group, an ethylene group, an n-propylene group, an n-butylene group, and a hexylene group, and examples of branched alkylene groups such as an isopropylene group, an isobutylene group, and a 2-methylpropylene group.

Specific examples of silane coupling agents represented by formula (S1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 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 preferred.

In the silane coupling agent comprising the bond unit A represented by formula (I) and the bond unit B represented by formula (II), the content of the bond unit A is preferably 30 mol% or more, more preferably 50 mol% or more, and preferably 99 mol% or less, more preferably 90 mol% or less.The content of the bond unit B is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and preferably 70 mol% or less, more preferably 65 mol% or less, even more preferably 55 mol% or less.The total content of the bond 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 bond units A and B includes the case where the bond units A and B are located at the terminals of the silane coupling agent. When the bond units A and B are located at the terminals of the silane coupling agent, the form of the bond units A and B is not particularly limited, and it is sufficient that the bond units A and B form units corresponding to the formulas (I) and (II) shown in FIG.

With respect to R ¹¹ in formulae (I) and (II), examples of halogen include chlorine, bromine, and fluorine. Examples of branched or unbranched alkyl groups having 1 to 30 carbon atoms include methyl and ethyl groups. Examples of branched or unbranched alkenyl groups having 2 to 30 carbon atoms include vinyl and 1-propenyl groups. Examples of branched or unbranched alkynyl groups having 2 to 30 carbon atoms include ethynyl and propynyl groups.

With respect to R ¹² in formulas (I) and (II), examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms include an ethylene group, a propylene group, etc. Examples of the branched or unbranched alkenylene group having 2 to 30 carbon atoms include a vinylene group, a 1-propenylene group, etc. Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms include an ethynylene group, a propynylene group, etc.

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

The rubber composition may contain a silane coupling agent other than a mercapto-based one. Examples of silane coupling agents that can be used include 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, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilyl butyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide and other sulfide-based compounds, vinyl triethoxysilane, vinyl trimethoxysilane and other vinyl-based compounds, 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane and other amino-based compounds, γ-glycidoxypropyl triethoxysilane, γ-glycidoxypropyl trimethoxysilane and other glycidoxy-based compounds, 3-nitropropyl trimethoxysilane, 3-nitropropyl triethoxysilane and other nitro-based compounds, 3-chloropropyl trimethoxysilane, 3-chloropropyl triethoxysilane and other chloro-based compounds, and the like. These compounds may be used alone or in combination of two or more.

Commercially available silane coupling agents include those from Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry, Azumax, and Dow Corning Toray.

The content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, and even more preferably 8 parts by mass or more, relative to 100 parts by mass of silica, and is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, the effect tends to be better.

The rubber composition preferably contains carbon black.
The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Shin-Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., and the like. These may be used alone or in combination of two or more kinds.

The cetyltrimethylammonium bromide (CTAB) specific surface area of the carbon black is preferably 90 m ² /g or more, more preferably 100 m ² /g or more, even more preferably 110 m ² /g or more, and is preferably 160 m ² /g or less, more preferably 140 m ² /g or less, even more preferably 130 m ² /g or less. Within the above range, the effect tends to be better obtained.
The CTAB specific surface area of carbon black is a value measured in accordance with JIS K6217-3:2001.

The carbon black content is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. Within the above range, the effect tends to be better obtained.

From the viewpoint of overall performance such as fuel economy and abrasion resistance, it is preferable that the cis amount of BR in the above rubber composition is equal to or greater than the carbon black content.

In the above rubber composition, the BR cis content/carbon black content is preferably 3.5 or more, more preferably 5.5 or more, even more preferably 6.5 or more, and particularly preferably 7.5 or more, and is preferably 9.5 or less, more preferably 8.5 or less, and even more preferably 8.0 or less. Within the above range, the effect tends to be better.

In these relationships, the cis content of BR is the content (unit: mass%) of cis parts contained in BR. When there is one type of BR, it means the cis content of that BR, and when there are multiple types, it means the average cis content. The carbon black content is the content (unit: mass parts) per 100 parts by mass of the rubber component.

The rubber composition preferably contains a resin.
Examples of the resin include cyclopentadiene resins, aromatic resins, and terpene resins. These may be used alone or in combination of two or more. They may also be hydrogenated (hydrogenated resins). Among these, cyclopentadiene resins and aromatic resins are preferred, and cyclopentadiene resins are more preferred.

Cyclopentadiene-based resins are polymers that contain cyclopentadiene-based monomers as constituent monomers, and examples of such resins include homopolymers in which one type of cyclopentadiene-based monomer is polymerized alone, copolymers in which two or more types of cyclopentadiene-based monomers are copolymerized, and copolymers of a cyclopentadiene-based monomer and another monomer that can be copolymerized with it.

Examples of cyclopentadiene monomers include cyclopentadiene, dicyclopentadiene, tricyclopentadiene, and the like. These may be used alone or in combination of two or more. Among these, dicyclopentadiene is preferred.

Because there is a tendency for the effect to be more satisfactorily obtained, the cyclopentadiene-based resin is preferably a polymer containing dicyclopentadiene (DCPD) as a constituent monomer (DCPD-based resin), more preferably a copolymer of DCPD and an aromatic monomer, and even more preferably a copolymer of DCPD and a C9 fraction (vinyl toluene, indene, etc.) (DCPD-C9 resin).
In this specification, a polymer containing a cyclopentadiene-based monomer and an aromatic-based monomer as constituent monomers, such as DCPD-C9 resin, is treated as a cyclopentadiene-based resin, not an aromatic resin.

The amount of the cyclopentadiene resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. Within the above range, the effect tends to be better obtained.

Aromatic resins are polymers that contain aromatic monomers as constituent monomers, and examples of such resins include homopolymers in which one type of aromatic monomer is polymerized alone, copolymers in which two or more types of aromatic monomers are copolymerized, and copolymers of aromatic monomers and other monomers that can be copolymerized with them.

Examples of aromatic monomers include styrene-based monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene; phenol-based monomers such as phenol, alkylphenol, and alkoxyphenol; naphthol-based monomers such as naphthol, alkylnaphthol, and alkoxynaphthol; coumarone, indene, and the like. These may be used alone or in combination of two or more. Of these, coumarone and indene are preferred.

Aromatic resins that are preferably polymers containing coumarone and indene as constituent monomers (coumarone-indene resins) are preferred because they tend to produce better effects.

The content of the aromatic resin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, the effect tends to be better obtained.

Commercially available examples of the above-mentioned resins include those from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Nippon Oil & Energy Corporation, Arakawa Chemical Industries Co., Ltd., and Taoka Chemical Co., Ltd.

The resin content (the total content when multiple types of resins are used) is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and particularly preferably 25 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. Within the above range, the effect tends to be better obtained.

From the viewpoint of overall performance such as fuel economy and abrasion resistance, it is preferable that the resin content in the above rubber composition is less than or equal to the isoprene-based rubber content.

In the above rubber composition, the ratio of isoprene-based rubber content to resin content is preferably 1.0 or more, and is preferably 3.5 or less, more preferably 2.5 or less, and even more preferably 1.5 or less. Within the above range, the effect tends to be better.

In these relationships, the isoprene-based rubber content is the content (unit: mass%) in 100% by mass of the rubber component, and the resin content is the content (unit: mass parts) per 100 parts by mass of the rubber component.

In the rubber composition, the resin content/silica content is preferably 0.1 or more, more preferably 0.3 or more, and even more preferably 0.5 or more, and is preferably 1.5 or less, more preferably 1.0 or less, and even more preferably 0.8 or less. Within the above ranges, the effect tends to be better obtained.
In this relationship, the resin content and the silica content are amounts (unit: parts by mass) based on 100 parts by mass of the rubber component.

The rubber composition preferably contains a dibenzylamine compound.
The dibenzylamine compound is a compound having at least one group (dibenzylamine group) represented by the following formula:

Specific examples of dibenzylamine compounds include dibenzylamine, tetrabenzylthiuram disulfide (TBzTD), zinc dibenzyldithiocarbamate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, etc. Commercially available products include those from Sanshin Chemical Industry Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., LANXESS, etc. These may be used alone or in combination of two or more. Of these, compounds having two dibenzylamine groups are preferred, and tetrabenzylthiuram disulfide is more preferred.

The content of the dibenzylamine compound is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less, per 100 parts by mass of the rubber component. If it is within the above range, the effect tends to be better.

（式中、Ｒ^１～Ｒ^４はそれぞれ独立に炭素数１～１８の直鎖若しくは分岐鎖アルキル基、又は炭素数５～１２のシクロアルキル基を表す。） The rubber composition preferably contains a dialkyldithiophosphate compound.
As the dialkyldithiophosphate compound, for example, a salt of a dialkyldithiophosphate with a metal such as zinc or molybdenum can be used. As a commercially available product, a product from Rhein Chemie or the like can be used. These may be used alone or in combination of two or more. Among them, a compound represented by the following formula (1) (zinc dialkyldithiophosphate) is preferred.

(In the formula, R ¹ to R ⁴ each independently represent a linear or branched alkyl group having 1 to 18 carbon atoms, or a cycloalkyl group having 5 to 12 carbon atoms.)

In formula (1), examples of the linear or branched alkyl group represented by R ¹ to R ⁴ include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a 4-methylpentyl group, a 2-ethylhexyl group, an octyl group, an octadecyl group, etc., while examples of the cycloalkyl group include a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, etc. Among these, from the viewpoints of easy dispersion in the rubber composition and easy production, R ¹ to R ⁴ are preferably linear or branched alkyl groups having 2 to 8 carbon atoms, more preferably an n-butyl group, an n-propyl group, an iso-propyl group, or an n-octyl group, and even more preferably an n-butyl group.

The content of the dialkyldithiophosphate compound is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less, per 100 parts by mass of the rubber component. Within the above range, the effect tends to be better obtained.

The rubber composition may contain an antioxidant.
Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants 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, and N,N'-di-2-naphthyl-p-phenylenediamine. Examples of the antioxidant include p-phenylenediamine antioxidants such as quinolinone, quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline, monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol, and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Commercially available products include those of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis Co., Ltd. These may be used alone or in combination of two or more.

The content of the anti-aging agent is preferably 1 part by mass or more, more preferably 2.5 parts by mass or more, and even more preferably 3.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less. Within the above range, the effect tends to be better.

The rubber composition may contain a processing aid.
Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, mixtures of fatty acid metal salts and fatty acid amides, etc. Commercially available products include those from Rhein Chemie and Struktol. These may be used alone or in combination of two or more. Among these, fatty acid metal salts are preferred.

The fatty acids constituting the fatty acid metal salt include saturated or unsaturated fatty acids (preferably saturated or unsaturated fatty acids having 6 to 28 carbon atoms (more preferably 10 to 25 carbon atoms, and even more preferably 14 to 20 carbon atoms)), such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, behenic acid, and nervonic acid. These can be used alone or in combination of two or more. Of these, saturated fatty acids are preferred, and saturated fatty acids having 14 to 20 carbon atoms are more preferred.

Examples of metals constituting fatty acid metal salts include alkali metals such as potassium and sodium, alkaline earth metals such as magnesium, calcium and barium, zinc, nickel, molybdenum, etc. These may be used alone or in combination of two or more. Of these, zinc is preferred.

The content of the processing aid is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the rubber component, and is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less. Within the above range, the effect tends to be better obtained.

The rubber composition may contain oil.
Examples of the oil include process oil, vegetable oil, and mixtures thereof. Examples of the process oil include paraffin-based process oil, aromatic process oil, and naphthenic process oil. Examples of the vegetable oil include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Examples of commercially available products include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., JXTG Energy Corporation, Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Mill Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and the like. These may be used alone or in combination of two or more.

The oil content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of the rubber component. Within the above range, the effect tends to be better.

From the viewpoint of overall performance such as fuel economy and abrasion resistance, it is preferable that the oil content of the above rubber composition is less than or equal to the total styrene content in the rubber component.

In the above rubber composition, the total styrene content in the rubber component/oil content is preferably 1.2 or more, more preferably 1.4 or more, and even more preferably 1.6 or more, and is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less. Within the above range, the effect tends to be better.

In these relationships, the oil content is the content (unit: parts by mass) relative to 100 parts by mass of the rubber component, and the total styrene content in the rubber component is the total content of styrene parts contained in the entire rubber component (unit: mass%).

The rubber composition may contain a wax.
The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as vegetable wax and animal wax; and synthetic waxes such as polymers of ethylene, propylene, etc. Commercially available products include those from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. These may be used alone or in combination of two or more kinds.

The wax content is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, per 100 parts by mass of the rubber component. Within the above range, the effect tends to be better.

The rubber composition may contain stearic acid.
As the stearic acid, a conventionally known one can be used, and as a commercially available product, a product from NOF Corp., Kao Corp., Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used. These may be used alone or in combination of two or more kinds.

The content of stearic acid is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, per 100 parts by mass of the rubber component. Within the above range, the effect tends to be better obtained.

The rubber composition may contain zinc oxide.
As the zinc oxide, a conventionally known one can be used, and as a commercially available product, there can be used products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more kinds.

The amount of zinc oxide is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, per 100 parts by mass of the rubber component. Within the above range, the effect tends to be better.

The rubber composition may contain sulfur.
Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. Commercially available products include those from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more.

The sulfur content is preferably 0.8 parts by mass or more, more preferably 1.2 parts by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 6 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less. Within the above range, the effect tends to be better obtained.

The rubber composition may contain a vulcanization accelerator.
Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD) and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. Commercially available products include products from Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Co., Ltd. These may be used alone or in combination of two or more.

The content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 4.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less. Within the above range, the effect tends to be better.

In addition to the above components, the rubber composition may further contain additives commonly used in the tire industry, such as organic peroxides; fillers such as talc, alumina, clay, aluminum hydroxide, and mica; etc. The content of these additives is preferably 0.1 to 200 parts by mass per 100 parts by mass of the rubber component.

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

As for kneading conditions, in the base kneading process where additives other than the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C. In the finish kneading process where the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 120°C or lower, preferably 85 to 110°C. Furthermore, the composition kneaded with the vulcanizing agent and 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 rubber composition can be used (as a rubber composition for tires) in tire components such as treads (cap treads), sidewalls, base treads, under treads, shoulders, clinches, bead apexes, breaker cushion rubber, carcass cord covering rubber, insulation, chafers, inner liners, and the like, as well as side reinforcing layers of run-flat tires. In particular, it is suitable for treads.

The tire of the present invention is produced by a conventional method using the above rubber composition.
That is, the rubber composition is extruded in an unvulcanized state to match the shape of the tread, and molded together with other tire components in a tire building machine by a normal method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire.

The tire tread may be at least partially made of the rubber composition, or may be entirely made of the rubber composition.

The above tires (pneumatic tires, etc.) can be used for passenger car tires; truck and bus tires; motorcycle tires; high-performance tires; winter tires such as studless tires; run-flat tires with side reinforcing layers; tires with sound absorbing materials that have sound absorbing materials such as sponge in the tire cavity; tires with sealing materials that have a sealant inside or in the tire cavity that can seal in the event of a puncture; tires with electronic components that have electronic components such as sensors and wireless tags inside or in the tire cavity, etc., and are suitable for passenger car tires.

The size of the above tires is not particularly limited, and can be appropriately selected, for example, the tire width within the range of 100 to 400 mm, the aspect ratio within the range of 25 to 85%, and the rim diameter within the range of 10 to 25 inches. Specific examples include 105/50R16, 115/50R17, 125/55R20, 135/45R21, 145/45R21, 155/45R18, 165/45R22, 175/45R23, 185/60R20, 195/55R14, 205/40R16, 215/40R16, 225/40R17, 235/40R17, 245/40R16, 255/40R17, 265/40R17, 275/35R18, 285/30R19, and 295/45R20.

なお、タイヤ外径（Ｄｔ）とは、タイヤを適用リムに装着して内圧２５０ｋＰａ・無負荷とした状態のタイヤの外径である。タイヤ断面幅（Ｗｔ）とは、タイヤを適用リムに装着して内圧２５０ｋＰａ・無負荷とした状態のタイヤ側面の模様又は文字など全てを含むサイドウォール間の直線距離、つまり総幅からタイヤの側面の模様、文字などを除いた幅である。 It is preferable that the tire outer diameter Dt and the tire section width Wt of the tire satisfy the following relational expression.

The tire outer diameter (Dt) is the outer diameter of the tire when mounted on an applicable rim and the internal pressure is 250 kPa with no load. The tire cross-sectional width (Wt) is the linear distance between the sidewalls including all patterns and letters on the tire side when mounted on an applicable rim and the internal pressure is 250 kPa with no load, that is, the width excluding the patterns and letters on the tire side from the total width.

Specific examples of tires that can satisfy the above formula include 145/60R18, 145/60R19, 155/55R18, 155/55R19, 155/70R17, 155/70R19, 165/55R20, 165/55R21, 165/60R19, 165/65R19, 165/70R18, 175/55R19, 175/55R20, 175/55R22, 175/60R18, 185/55R19, 185/60R20, 195/50R20, 195/55R20, etc.

Tires that satisfy the above formula are preferably used as pneumatic tires for passenger cars. This is because pneumatic tires for passenger cars that satisfy the above formula tend to be more suitable for solving the problem in question.

The present invention will be specifically explained based on examples, but the present invention is not limited to these.

The various chemicals used in the examples and comparative examples are described below.

(Rubber component)
Isoprene rubber 1: TSR20 (NR)
Isoprene rubber 2: LIR-50 (liquid IR) manufactured by Kuraray Co., Ltd.
SBR1: Modified SBR synthesized in Production Example 1 below (styrene content: 10% by mass, vinyl content: 40% by mass, Mw: 200,000)
SBR2: Modified SBR synthesized in Production Example 2 below (styrene content: 40% by mass, vinyl content: 40% by mass, Mw: 750,000)
SBR3: Modified SBR synthesized in Production Example 3 below (styrene content: 25% by mass, vinyl content: 60% by mass, Mw: 300,000)
SBR4: Modified SBR synthesized in Production Example 4 below (styrene content: 40% by mass, vinyl content: 30% by mass, Mw: 950,000)
SBR5: Buna VSL 5228-2 manufactured by LANXESS (styrene content: 28% by mass, vinyl content: 52% by mass, oil content: 37.5 parts by mass per 100 parts by mass of rubber solids)
SBR6: Buna VSL 2438-2 HM manufactured by LANXESS (styrene content: 38% by mass, vinyl content: 24% by mass, oil content: 37.5 parts by mass per 100 parts by mass of rubber solids)
BR: N103 manufactured by Asahi Kasei Chemicals Corporation (cis content: 38% by mass, vinyl content: 12% by mass)

(Chemicals other than rubber components)
Carbon black: N220 (CTAB: 111 ^m2 /g)
Silica 1: Ultrasil 9100GR (average particle size: 15 nm) manufactured by Evonik Degussa
Silica 2: Ultrasil VN3 (average particle size: 17 nm) manufactured by Evonik Degussa
Silane coupling agent 1: NXT-Z45 manufactured by Momentive (a 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: Si266 (bis(3-triethoxysilylpropyl)disulfide) manufactured by Evonik Degussa
Oil: A/O mix resin manufactured by Sankyo Yuka Kogyo Co., Ltd. 1: Oppera PR-395 (hydrogenated DCPD-C9 resin) manufactured by Exxon Mobil
Resin 2: Nitto Chemical Co., Ltd. knit resin Kumarone V-120 (cumarone indene resin)
Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd.
Antioxidant 1: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Antioxidant 2: Antigen FR manufactured by Sumitomo Chemical Co., Ltd. (a quinoline-based antioxidant made by purifying the reaction product of amines and ketones, with no residual amines)
Processing aid: EF44 (zinc salt of saturated fatty acid) manufactured by Struktol
Stearic acid: NOF Corporation's "Tsubaki" stearic acid
Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (powdered sulfur containing 5% by mass of oil) manufactured by Hosoi Chemical Industry Co., Ltd.
Dialkyldithiophosphate compound: TP-50 manufactured by Rhein Chemie (a mixture of zinc dithiophosphate and polymer, R ¹ to R ⁴ in formula (1) are n-butyl groups, and the active ingredient is 50% by mass)
Vulcanization accelerator 1: Sancerer NS-G (N-tert-butyl-2-benzothiazole sulfenamide) manufactured by Sanshin Chemical Industry Co., Ltd.
Vulcanization accelerator 2: Sancerer D (diphenyl guanidine) manufactured by Sanshin Chemical Industry Co., Ltd.
Dibenzylamine compound: Sancerer TBzTD (tetrabenzyl thiuram disulfide) manufactured by Sanshin Chemical Industry Co., Ltd.

(Production Example 1)
Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into a nitrogen-substituted autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium was added to initiate polymerization. Polymerization was performed under adiabatic conditions, with the maximum temperature reaching 85°C. When the polymerization conversion reached 99%, butadiene was added and polymerization was continued for another 5 minutes, after which 3-dimethylaminopropyltriethoxysilane was added as a modifier and the reaction was continued for 15 minutes. After completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Next, the solvent was removed by steam stripping, and the mixture was dried with a heated roll adjusted to 110°C to obtain SBR1.

(Production Example 2)
Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into a nitrogen-substituted autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium was added to initiate polymerization. Polymerization was performed under adiabatic conditions, with the maximum temperature reaching 85°C. When the polymerization conversion reached 99%, butadiene was added and polymerization was continued for another 5 minutes, after which 3-dimethylaminopropyltrimethoxysilane was added as a modifier and the reaction was continued for 15 minutes. After completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Next, the solvent was removed by steam stripping, and the mixture was dried with a heated roll adjusted to 110°C to obtain SBR2.

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

(Production Example 4)
Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into a nitrogen-substituted autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium was added to initiate polymerization. Polymerization was performed under adiabatic conditions, with the maximum temperature reaching 85°C. When the polymerization conversion reached 99%, 1,3-butadiene was added, and polymerization was continued for another 5 minutes, after which N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane was added as a modifier to carry out the reaction. After completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Next, the solvent was removed by steam stripping, and the mixture was dried with a heated roll adjusted to 110°C to obtain SBR4.

Examples and Comparative Examples
According to the formulation shown in Table 1, materials other than the dibenzylamine compound, sulfur, and vulcanization accelerator were kneaded for 5 minutes under the condition of 150 ° C. using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded product. Next, the dibenzylamine compound, sulfur, and 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 was molded into a tread shape, and laminated together with other tire components to form an unvulcanized tire, which was press-vulcanized for 12 minutes under the condition of 150 ° C. to produce a test tire (size: 175 / 60R18). The following evaluations were performed using the obtained test tire, and the results are shown in Table 1.
In Table 1, the rubber content in the oil-extended rubber is shown in the rubber column, and the oil content in the oil-extended rubber is added to the oil column.

(low fuel consumption)
Using a rolling resistance tester, the rolling resistance of each test tire was measured when it was run at a speed (80 km/h), and the rolling resistance was expressed as an index with Comparative Example 1 being set at 100. A larger index indicates a smaller rolling resistance and better fuel economy.

(Wear resistance)
Each test tire was mounted on a vehicle, and the groove depth of the tread portion was measured after driving 50,000 km. The amount of wear of the tread portion was calculated from the measured values, and expressed as an index with Comparative Example 2 being set at 100. The larger the index, the smaller the amount of wear and the better the wear resistance.

As can be seen from Table 1, the examples were superior to the comparative examples in terms of the overall performance (total of each index) of the desired fuel economy and wear resistance.

Claims (8)

The rubber component includes a styrene-butadiene rubber, a butadiene rubber, and an isoprene-based rubber, silica, a mercapto-based silane coupling agent, and a resin,
The average particle size of the silica is 16 nm or less,
the content of the styrene-butadiene rubber is equal to or greater than the content of the isoprene-based rubber, and the content of the butadiene rubber is equal to or greater than the content of the isoprene-based rubber,
The content of the styrene-butadiene rubber is equal to or greater than the content of the silica,
A rubber composition for tires in which the content of the resin is equal to or less than the content of the isoprene-based rubber (excluding the rubber composition shown in (1) below).
(1) A rubber composition for tires comprising a rubber component having a styrene-butadiene rubber content of 60% by mass or more and a styrene-based resin, the styrene-butadiene rubber being composed of a plurality of styrene-butadiene rubbers, the difference in styrene content among the plurality of styrene-butadiene rubbers being 15% by mass or less and the difference in vinyl content among the plurality of styrene-butadiene rubbers being 15% by mass or less, and satisfying the following formula (A):
(A) α/β≦4
α: total amount of styrene in the rubber component [mass%]
β: content of styrene-based resin per 100 parts by mass of rubber component [parts by mass] The rubber component includes a styrene-butadiene rubber, a butadiene rubber, and an isoprene-based rubber, silica, a mercapto-based silane coupling agent, a resin, and an oil,
the content of the styrene-butadiene rubber is equal to or greater than the content of the isoprene-based rubber, and the content of the butadiene rubber is equal to or greater than the content of the isoprene-based rubber,
The content of the styrene-butadiene rubber is equal to or greater than the content of the silica,
The content of the resin is less than or equal to the content of the isoprene-based rubber,
The content of the oil is 15 parts by mass or more based on 100 parts by mass of the rubber component,
A rubber composition for tires, wherein a total styrene amount in the rubber component/a content of the oil is ≧1.6. The rubber composition for tires according to claim 1 or 2, wherein the content of the silica is equal to or greater than the content of the isoprene-based rubber. The rubber component includes a styrene-butadiene rubber, a butadiene rubber, and an isoprene-based rubber, silica, a mercapto-based silane coupling agent, and a resin,
the content of the styrene-butadiene rubber is equal to or greater than the content of the isoprene-based rubber, and the content of the butadiene rubber is equal to or greater than the content of the isoprene-based rubber,
The content of the styrene-butadiene rubber is equal to or greater than the content of the silica,
The content of the resin is less than or equal to the content of the isoprene-based rubber,
A rubber composition for tires , in which the cis content of the butadiene rubber is 60 mass % or less (excluding the rubber composition shown in (1) below) .
(1) A rubber composition for tires comprising a rubber component having a styrene-butadiene rubber content of 60% by mass or more and a styrene-based resin, the styrene-butadiene rubber being composed of a plurality of styrene-butadiene rubbers, the difference in styrene content among the plurality of styrene-butadiene rubbers being 15% by mass or less and the difference in vinyl content among the plurality of styrene-butadiene rubbers being 15% by mass or less, and satisfying the following formula (A):
(A) α/β≦4
α: total amount of styrene in the rubber component [mass%]
β: content of styrene-based resin per 100 parts by mass of rubber component [parts by mass] The rubber component includes a styrene-butadiene rubber, a butadiene rubber, and an isoprene-based rubber, silica, a mercapto-based silane coupling agent, a resin, and carbon black,
the content of the styrene-butadiene rubber is equal to or greater than the content of the isoprene-based rubber, and the content of the butadiene rubber is equal to or greater than the content of the isoprene-based rubber,
The content of the styrene-butadiene rubber is equal to or greater than the content of the silica,
The content of the resin is less than or equal to the content of the isoprene-based rubber,
A rubber composition for tires in which the cis amount of the butadiene rubber is equal to or greater than the carbon black content (excluding the rubber composition shown in (1) below) .
(1) A rubber composition for tires comprising a rubber component having a styrene-butadiene rubber content of 60% by mass or more and a styrene-based resin, the styrene-butadiene rubber being composed of a plurality of styrene-butadiene rubbers, the difference in styrene content among the plurality of styrene-butadiene rubbers being 15% by mass or less and the difference in vinyl content among the plurality of styrene-butadiene rubbers being 15% by mass or less, and satisfying the following formula (A):
(A) α/β≦4
α: total amount of styrene in the rubber component [mass%]
β: content of styrene-based resin per 100 parts by mass of rubber component [parts by mass] The rubber composition for tires according to any one of claims 1 to 5 , further comprising a dibenzylamine compound. The rubber composition for tires according to any one of claims 1 to 6, further comprising a dialkyldithiophosphate compound. A tire having a tread using the rubber composition according to any one of claims 1 to 7 .