JP2018158979A - Tread rubber composition and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tread rubber composition that can improve wet grip performance and low fuel consumption performance in a balanced manner, and a pneumatic tire using the tread rubber composition.SOLUTION: A tread rubber composition contains a rubber component 100 pts.mass, containing (a) styrene-butadiene rubber (SBR) 1 of 40-55 mass% with styrene content (st) of 15-30 mass% and with a weight average molecular weight (Mw) of 100,000-300,000, (b) SBR2 of 20-40 mass% with st of 35-55 mass% and Mw of 600,000-850,000, and (c) SB3 with st of 5 mass% or less and Mw of 300,000-550,000, as well as (d) silica of 45-70 pts.mass, (e) carbon black of 1-30 pts.mass, (f) aromatic resin of 2-10 pts.mass, (g) softener of 5-20 pts.mass, and (h) silane coupling agent represented by a formula (S1) of 3-15 pts.mass relative to the (d) silica 100 pts.mass.SELECTED DRAWING: None

Description

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

In recent years, with the demand for safety for automobiles, tire rubber materials are required to be improved in wet grip performance and the like, and are also desired to be compatible with low fuel consumption performance which is contradictory performance.

For example, Patent Document 1 proposes a technique for improving wet grip performance by using a rubber composition containing an oil-extended butadiene rubber synthesized using a rare earth element-based catalyst, a predetermined styrene butadiene rubber, an inorganic filler, or the like. However, further improvement is desired for compatibility between wet grip performance and low fuel consumption performance.

Japanese Patent Laid-Open No. 2015-232114

An object of the present invention is to solve the above problems and provide a rubber composition for a tread that can improve the wet grip performance and the low fuel consumption performance in a well-balanced manner, and a pneumatic tire using the same.

［式中、Ｒ^１００１は−Ｃｌ、−Ｂｒ、−ＯＲ^１００６、−Ｏ（Ｏ＝）ＣＲ^１００６、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＮＲ^１００６Ｒ^１００７及び−（ＯＳｉＲ^１００６Ｒ^１００７）_ｈ（ＯＳｉＲ^１００６Ｒ^１００７Ｒ^１００８）から選択される一価の基（Ｒ^１００６、Ｒ^１００７及びＲ^１００８は同一でも異なっていても良く、各々水素原子又は炭素数１〜１８の一価の炭化水素基であり、ｈは平均値が１〜４である。）であり、Ｒ^１００２はＲ^１００１、水素原子又は炭素数１〜１８の一価の炭化水素基、Ｒ^１００３はＲ^１００１、Ｒ^１００２、水素原子又は−［Ｏ（Ｒ^１００９Ｏ）_ｊ］_０．５−基（Ｒ^１００９は炭素数１〜１８のアルキレン基、ｊは１〜４の整数である。）、Ｒ^１００４は炭素数１〜１８の二価の炭化水素基、Ｒ^１００５は炭素数１〜１８の一価の炭化水素基を示し、ｘ、ｙ及びｚは、ｘ＋ｙ＋２ｚ＝３、０≦ｘ≦３、０≦ｙ≦２、０≦ｚ≦１の関係を満たす数である。］ The present invention relates to a styrene butadiene rubber (1) having a styrene content of 15 to 30% by mass and a weight average molecular weight of 100,000 to 300,000, a styrene butadiene rubber (2) having a styrene content of 35 to 55% by mass and a weight average molecular weight of 60 to 850,000. In addition, a rubber component containing a styrene butadiene rubber (3) having a styrene content of 5% by mass or less and a weight average molecular weight of 30 to 550,000 or a butadiene rubber having a weight average molecular weight of 30 to 550,000, silica, and the following formula (S1) Silane coupling agent, carbon black, and a softener component containing an aromatic resin,
In 100% by mass of the rubber component, the content of the styrene butadiene rubber (1) is 40 to 55% by mass, the content of the styrene butadiene rubber (2) is 20 to 40% by mass, the styrene butadiene rubber (3) and The total content of the butadiene rubber is 10 to 20% by mass,
The silica content is 45 to 70 parts by mass, the carbon black content is 1 to 30 parts by mass, and the aromatic resin content is 2 to 10 parts by mass with respect to 100 parts by mass of the rubber component. The softener component content is 5 to 20 parts by mass,
It is related with the rubber composition for treads whose content of the said silane coupling agent is 3-15 mass parts with respect to 100 mass parts of said silicas.

[Wherein R ¹⁰⁰¹ represents —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 OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) may be the same or different and each have a hydrogen atom or a carbon number of 1 to 18 R is a monovalent hydrocarbon group, h has an average value of 1 to 4, and R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰³ is R ^{1001, R 1002,} a hydrogen atom or _{^{- [O (R 1009 O)}} j] 0.5 - group ^{(R 1009} represents an alkylene group having 1 to 18 carbon atoms, j is 1 to 4 Is an ^{integer.), R 1004} represents a divalent hydrocarbon ^{group, R 1005} is a monovalent hydrocarbon group having 1 to 18 carbon atoms having 1 to 18 carbon atoms, x, y and z, x + y + 2z = 3 , 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1. ]

The present invention relates to a pneumatic tire having a tread produced from the rubber composition.

The present invention is a rubber composition for treads containing a predetermined amount of a predetermined rubber component, silica, a predetermined silane coupling agent, carbon black, and a predetermined softener component, so that the wet grip performance, The fuel efficiency can be improved in a well-balanced manner.

The rubber composition for a tread of the present invention contains a predetermined amount of a predetermined rubber component, silica, a predetermined silane coupling agent, carbon black, and a predetermined softener component. Thereby, wet grip performance and low fuel consumption performance can be improved in a well-balanced manner.

In particular, by using a predetermined amount of a predetermined amount of a predetermined styrene butadiene rubber (1), a styrene butadiene rubber (2), a styrene butadiene rubber (3) or a butadiene rubber, a silane coupling agent, and an aromatic resin. Performance balance of wet grip performance and low fuel consumption performance is improved synergistically.

In the rubber composition for a tread of the present invention, it is presumed that the performance balance of wet grip performance and low fuel consumption performance is remarkably (synergistically) improved by the following effects.
By blending high-styrene and high-molecular-weight styrene-butadiene rubber (2) and an aromatic resin that is compatible with it, energy loss occurs when deformation occurs and the entanglement between polymers is loosened, resulting in wet grip performance. In addition to the improvement, the combined use of the styrene butadiene rubber (1) with a low styrene content and the styrene butadiene rubber (3) or butadiene rubber with a low styrene content and a high molecular weight makes the silica distribution state uniform among the three types of polymers. In addition, as a result of suppressing the movement of the three types of polymers bonded to the silica by the silane coupling agent represented by the formula (S1), it is considered that the fuel economy performance is improved along with the wet grip performance. Accordingly, in the present invention, the predetermined styrene butadiene rubber (1), the styrene butadiene rubber (2), the styrene butadiene rubber (3) or the butadiene rubber, the silane coupling agent, and the aromatic resin are used in combination. Therefore, it is considered that these performance balances are remarkably (synergistically) improved.
In the present invention, since styrene butadiene rubber (3) and butadiene rubber function in the same manner, for example, even when styrene butadiene rubber (3) is blended, the same effect as when butadiene rubber is blended is obtained.

The rubber composition of the present invention comprises, as rubber components, a styrene butadiene rubber (1) (SBR (1)) having a styrene content of 15 to 30% by mass and a weight average molecular weight of 100,000 to 300,000, a styrene content of 35 to 55% by mass and a weight. Styrene butadiene rubber (2) (SBR (2)) having an average molecular weight of 60 to 850,000, and styrene butadiene rubber (3) (SBR (3)) having a styrene amount of 5% by mass or less and a weight average molecular weight of 30 to 550,000, or Contains butadiene rubber (BR) having a weight average molecular weight of 300 to 550,000.

SBR that can be used as SBR (1), SBR (2), SBR (3) is not particularly limited. For example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR), etc. are used. it can.

The amount of styrene in SBR (1) is 15% by mass or more, preferably 20% by mass or more, more preferably 22% by mass or more. When it is 15% by mass or more, good wet grip performance can be obtained. Moreover, the said styrene amount is 30 mass% or less, Preferably it is 28 mass% or less. When it is 30% by mass or less, heat generation is reduced, and good fuel efficiency is obtained.
In the present specification, the amount of styrene is calculated by H ¹ -NMR measurement.

The weight average molecular weight (Mw) of SBR (1) is 100,000 or more, preferably 120,000 or more. When it is 100,000 or more, good wet grip performance can be obtained. The Mw is 300,000 or less, preferably 200,000 or less, more preferably 180,000 or less. When it is 300,000 or less, good fuel efficiency can be obtained.
In this specification, Mw is gel permeation chromatography (GPC) (GPC-8000 series, manufactured by Tosoh Corp., detector: differential refractometer, column: TSKGEL SUPERMALTPORE HZ-M manufactured by Tosoh Corp.) Can be determined by standard polystyrene conversion based on the measured value of

The amount of vinyl in SBR (1) is preferably 30% by mass or more, more preferably 40% by mass or more, and still more preferably 50% by mass or more. The vinyl content is preferably 80% by mass or less, more preferably 70% by mass or less. If it is within the above numerical range, the effect of the present invention tends to be obtained better.
In the present specification, the vinyl content (1,2-bond butadiene unit content) can be measured by infrared absorption spectrum analysis.

The amount of styrene in SBR (2) is 35% by mass or more, preferably 38% by mass or more. When it is 35% by mass or more, good wet grip performance can be obtained. Moreover, the said styrene amount is 55 mass% or less, Preferably it is 50 mass% or less, More preferably, it is 45 mass% or less. When it is 55% by mass or less, heat generation is reduced, and good fuel efficiency is obtained.

The weight average molecular weight (Mw) of SBR (2) is 600,000 or more, preferably 650,000 or more. If it is 600,000 or more, good wet grip performance can be obtained. The Mw is 850,000 or less, preferably 800,000 or less, more preferably 750,000 or less. When it is 850,000 or less, good fuel efficiency can be obtained.

The amount of vinyl in SBR (2) is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 30% by mass or more. The vinyl content is preferably 70% by mass or less, more preferably 60% by mass or less, and still more preferably 50% by mass or less. If it is within the above numerical range, the effect of the present invention tends to be obtained better.

The amount of styrene in SBR (3) is 5% by mass or less, preferably 3% by mass or less. The lower limit of the amount of styrene is not particularly limited, but is preferably 0.5% by mass, more preferably 1% by mass. Within the above numerical range, the effect of the present invention can be obtained satisfactorily.

The weight average molecular weight (Mw) of SBR (3) is 300,000 or more, preferably 350,000 or more. When it is 300,000 or more, good wet grip performance can be obtained. The Mw is 550,000 or less, preferably 500,000 or less, more preferably 450,000 or less. When it is 550,000 or less, good fuel efficiency can be obtained.

The vinyl content of SBR (3) is preferably 1% by mass or more, more preferably 5% by mass or more. The vinyl content is preferably 40% by mass or less, more preferably 30% by mass or less, and still more preferably 20% by mass or less. If it is within the above numerical range, the effect of the present invention tends to be obtained better.

Each of SBR (1), SBR (2), and SBR (3) may be a non-modified SBR or a modified SBR, but may be a modified SBR because the effects of the present invention can be obtained more favorably. preferable.

The modified SBR may be any SBR having a functional group that interacts with a filler such as silica or carbon black. For example, at least one terminal of the SBR is modified with a compound having a functional group (modifier). Terminal-modified SBR (terminal-modified SBR having the functional group at the terminal), main-chain modified SBR having the functional group at the main chain, and main-chain terminal-modified SBR having the functional group at the main chain and the terminal (for example, Modified (coupling) with a polyfunctional compound having the above functional group in the main chain and at least one terminal modified with the above modifier, or a polyfunctional compound having two or more epoxy groups in the molecule And terminal-modified SBR into which a hydroxyl group or an epoxy group is introduced.

Examples of the functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfides. Group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group, etc. . These functional groups may have a substituent. Among these, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably, because the effects of the present invention can be obtained more suitably. C1-C6 alkoxy group) and alkoxysilyl groups (preferably C1-C6 alkoxysilyl groups) are preferred.

The rubber composition of the present invention may contain SBR other than SBR (1), SBR (2), and SBR (3).
Examples of SBR such as SBR (1), SBR (2), SBR (3) are manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd., etc. SBR can be used.

The content of SBR (1) in 100% by mass of the rubber component is 40% by mass or more. When it is 40% by mass or more, good wet grip performance can be obtained. Moreover, the said content is 55 mass% or less, Preferably it is 50 mass% or less, More preferably, it is 45 mass% or less. When the content is 55% by mass or less, good fuel efficiency can be obtained.

The content of SBR (2) in 100% by mass of the rubber component is 20% by mass or more, preferably 25% by mass or more. When it is 20% by mass or more, good wet grip performance can be obtained. Moreover, the said content is 40 mass% or less, Preferably it is 35 mass% or less. When the content is 40% by mass or less, good fuel efficiency can be obtained.

The content of SBR (3) in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 15% by mass or more. There exists a tendency for a more favorable fuel-efficient performance to be acquired as it is 10 mass% or more. The content is preferably 20% by mass or less. When the content is 20% by mass or less, better wet grip performance tends to be obtained.

The BR that can be used as the BR is not particularly limited, and for example, BR having a high cis content, BR containing a syndiotactic polybutadiene crystal, and the like can be used.

The weight average molecular weight (Mw) of the BR is 300,000 or more, preferably 350,000 or more. When it is 300,000 or more, good wet grip performance can be obtained. The Mw is 550,000 or less, preferably 500,000 or less, more preferably 450,000 or less. When it is 550,000 or less, good fuel efficiency can be obtained.

The vinyl content of the BR is preferably 1% by mass or more, more preferably 5% by mass or more. The vinyl content is preferably 70% by mass or less, more preferably 60% by mass or less. If it is within the above numerical range, the effect of the present invention tends to be obtained better.

The BR may be non-modified BR or modified BR, but is preferably a modified BR because the effects of the present invention can be obtained better.
Examples of the modified BR include a modified BR in which the same functional group as that of the above-described modified SBR is introduced.

The rubber composition of the present invention may contain BR other than the above BR.
As BR, such as the above BR, products such as Ube Industries, JSR, Asahi Kasei, and Nippon Zeon can be used.

The BR content in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 15% by mass or more. There exists a tendency for a more favorable fuel-efficient performance to be acquired as it is 10 mass% or more. The content is preferably 20% by mass or less. When the content is 20% by mass or less, better wet grip performance tends to be obtained.

The total content of SBR (3) and BR in 100% by mass of the rubber component is 10% by mass or more, preferably 15% by mass or more. When the content is 10% by mass or more, good fuel efficiency can be obtained. Moreover, the said total content is 20 mass% or less. When it is 20% by mass or less, good wet grip performance can be obtained.

In addition to SBR and BR, rubber components that can be used in the present invention include isoprene rubber, acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), styrene-isoprene-butadiene copolymer rubber (SIBR), and the like. A diene rubber is mentioned. These diene rubbers may be used alone or in combination of two or more. Of these, isoprene-based rubber is preferable because it can further improve the fuel efficiency.

Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. As the NR, for example, those commonly used in the tire industry such as SIR20, RSS # 3, TSR20 and the like can be used. As IR, it is not specifically limited, For example, IR2200 etc. can use what is common in tire industry. As modified NR, deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of the 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.

The content of isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more. The content is preferably 30% by mass or less, more preferably 20% by mass or less. If it is within the above numerical range, the effect of the present invention tends to be obtained better.

The rubber composition of the present invention contains carbon black.
Although it does not specifically limit as carbon black, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762 etc. are mentioned. These may be used alone or in combination of two or more.

Nitrogen adsorption specific surface area _(N 2 SA) of carbon black is preferably at least ^{5 m} 2 / g, more preferably not less than ^{50m 2 / g, 100m 2 /} g or more is particularly preferable. When it is 5 m ² / g or more, the reinforcing property is improved and sufficient wear resistance tends to be obtained. Further, the _N 2 SA is preferably 200 meters ² / g or less, more preferably 150 meters ² / g, more preferably not more than 130m ² / g. When it is 200 m ² / g or less, good dispersion of carbon black is likely to be obtained, and good wear resistance and low fuel consumption performance tend to be obtained.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by JISK6217-2: 2001.

Carbon black has a dibutyl phthalate oil absorption (DBP) of preferably 5 ml / 100 g or more, more preferably 50 ml / 100 g or more, and still more preferably 100 ml / 100 g or more. When it is 5 ml / 100 g or more, the reinforcing property is improved and sufficient wear resistance tends to be obtained. The DBP is preferably 300 ml / 100 g or less, more preferably 200 ml / 100 g or less, still more preferably 130 ml / 100 g or less. There exists a tendency for favorable abrasion resistance to be acquired as it is 300 ml / 100g or less.
In addition, DBP of carbon black is calculated | required by the measuring method of JISK6217-4: 2001.

Examples of carbon black include products such as Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Shin-Nikka Carbon Co., Ltd., Columbia Carbon Co., etc. Can be used.

The content of carbon black is 1 part by mass or more, preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. When the amount is 1 part by mass or more, sufficient reinforcing properties can be obtained, and good wear resistance can be obtained. Moreover, the said content is 30 mass parts or less, Preferably it is 15 mass parts or less. A favorable rolling resistance is obtained as it is 30 mass parts or less.

The rubber composition of the present invention contains silica. Examples of the silica include dry process silica (anhydrous silicic acid), wet process silica (hydrous silicic acid) and the like, but wet process silica is preferred because of the large number of silanol groups.

Examples of silica that can be used include products such as Degussa, Rhodia, Tosoh Silica, Solvay Japan, and Tokuyama.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 70 m ² / g or more, and more preferably 150 m ² / g or more. By setting it to 70 m ² / g or more, wear resistance and the like tend to be further improved. _N 2 SA of the silica is preferably 500 meters ² / g or less, more preferably 200m ² / g. There exists a tendency for workability to improve more by setting it as 500 m < ² > / g or less.
The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

The content of silica is 45 parts by mass or more with respect to 100 parts by mass of the rubber component. When it is 45 parts by mass or more, low fuel consumption performance and the like are improved. The content is 70 parts by mass or less, preferably 60 parts by mass or less. If it is 70 parts by mass or less, the balance between processability and fuel efficiency is improved.

［式中、Ｒ^１００１は−Ｃｌ、−Ｂｒ、−ＯＲ^１００６、−Ｏ（Ｏ＝）ＣＲ^１００６、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＮＲ^１００６Ｒ^１００７及び−（ＯＳｉＲ^１００６Ｒ^１００７）_ｈ（ＯＳｉＲ^１００６Ｒ^１００７Ｒ^１００８）から選択される一価の基（Ｒ^１００６、Ｒ^１００７及びＲ^１００８は同一でも異なっていても良く、各々水素原子又は炭素数１〜１８の一価の炭化水素基であり、ｈは平均値が１〜４である。）であり、Ｒ^１００２はＲ^１００１、水素原子又は炭素数１〜１８の一価の炭化水素基、Ｒ^１００３はＲ^１００１、Ｒ^１００２、水素原子又は−［Ｏ（Ｒ^１００９Ｏ）_ｊ］_０．５−基（Ｒ^１００９は炭素数１〜１８のアルキレン基、ｊは１〜４の整数である。）、Ｒ^１００４は炭素数１〜１８の二価の炭化水素基、Ｒ^１００５は炭素数１〜１８の一価の炭化水素基を示し、ｘ、ｙ及びｚは、ｘ＋ｙ＋２ｚ＝３、０≦ｘ≦３、０≦ｙ≦２、０≦ｚ≦１の関係を満たす数である。］ The rubber composition of the present invention contains a silane coupling agent represented by the following formula (S1) together with silica.

[Wherein R ¹⁰⁰¹ represents —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 OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) may be the same or different and each have a hydrogen atom or a carbon number of 1 to 18 R is a monovalent hydrocarbon group, h has an average value of 1 to 4, and R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰³ is R ^{1001, R 1002,} a hydrogen atom or _{^{- [O (R 1009 O)}} j] 0.5 - group ^{(R 1009} represents an alkylene group having 1 to 18 carbon atoms, j is 1 to 4 Is an ^{integer.), R 1004} represents a divalent hydrocarbon ^{group, R 1005} is a monovalent hydrocarbon group having 1 to 18 carbon atoms having 1 to 18 carbon atoms, x, y and z, x + y + 2z = 3 , 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1. ]

In the above formula (S1), R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ are each independently composed of a linear, cyclic or branched alkyl group, alkenyl group, aryl group and aralkyl group having 1 to 18 carbon atoms. A group selected from the group is preferred. In addition, when R ¹⁰⁰² is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is a group selected from the group consisting of a linear, cyclic or branched alkyl group, alkenyl group, aryl group and aralkyl group. Preferably there is. R ¹⁰⁰⁹ is preferably a linear, cyclic or branched alkylene group, particularly preferably a linear one. R ¹⁰⁰⁴ is, for example, an alkylene group having 1 to 18 carbon atoms, an alkenylene group having 2 to 18 carbon atoms, a cycloalkylene group having 5 to 18 carbon atoms, a cycloalkylalkylene group having 6 to 18 carbon atoms, or an arylene having 6 to 18 carbon atoms. And aralkylene groups having 7 to 18 carbon atoms. The alkylene group and alkenylene group may be linear or branched, and the cycloalkylene group, cycloalkylalkylene group, arylene group, and aralkylene group have a functional group such as a lower alkyl group on the ring. You may have. As 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 above formula (S1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, 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, Examples include cyclohexenyl group, phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenethyl group, naphthylmethyl group and the like.
As examples of R ¹⁰⁰⁹ in the above formula (S1), examples of the linear alkylene group include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, a hexylene group, and the like. , Isopropylene group, isobutylene group, 2-methylpropylene group and the like.

Specific examples of the silane coupling agent represented by the above formula (S1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3 -Lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexa Noylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2 Octanoylthiopropyl ethyltrimethoxysilane, 2- deca Neu thio ethyltrimethoxysilane, and 2-lauroyl thio ethyl trimethoxysilane. Of these, 3-octanoylthiopropyltriethoxysilane is particularly preferable in terms of both workability and low fuel consumption. The silane coupling agent may be used alone or in combination of two or more.

In addition, in the range which does not inhibit the effect of this invention, you may further add silane coupling agents other than the silane coupling agent represented by said Formula (S1).

As the silane coupling agent, for example, products such as Degussa (NXT, etc.), Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Amax Co., Ltd., Toray Dow Corning Co., Ltd. can be used .

Content of a silane coupling agent is 3 mass parts or more with respect to 100 mass parts of silica, and 5 mass parts or more are preferable. The effect by having mix | blended the silane coupling agent as it is 3 mass parts or more is acquired. Moreover, the said content is 15 mass parts or less, and 10 mass parts or less are preferable. When it is 15 parts by mass or less, an effect commensurate with the blending amount is obtained, and good workability during kneading is obtained.

The rubber composition of the present invention contains a softener component containing an aromatic resin. In the present invention, the softener component means a component soluble in acetone. Specifically, in addition to aromatic resins, oils such as process oils and vegetable oils, liquid diene polymers, polyterpene resins, etc. Is mentioned.

An aromatic resin is a polymer containing an aromatic compound as a constituent component. The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring. For example, phenol compounds such as phenol, alkylphenol, alkoxyphenol, unsaturated hydrocarbon group-containing phenol; naphthol, alkylnaphthol, alkoxynaphthol, unsaturated Examples thereof include naphthol compounds such as hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; coumarone and indene.

Examples of aromatic resins include α-methylstyrene resins, coumarone indene resins, aromatic modified terpene resins, terpene aromatic resins, and the like. Of these, α-methylstyrene-based resins and aromatic-modified terpene resins are preferable, and α-methylstyrene-based resins are more preferable from the viewpoint that the effects of the present invention can be obtained better.
Examples of the α-methylstyrene-based resin include α-methylstyrene homopolymers and copolymers of α-methylstyrene and styrene. Coumarone indene resin is a resin containing coumarone and indene as monomer components constituting the resin skeleton (main chain). In addition to coumarone and indene, monomer components contained in the skeleton include styrene, methylindene, and vinyltoluene. Etc. Examples of the aromatic modified terpene resin include a resin obtained by modifying a terpene resin with an aromatic compound (preferably a styrene derivative, more preferably styrene), and a resin obtained by hydrogenating the resin. Examples of the terpene aromatic resin include a resin obtained by copolymerizing a terpene compound and an aromatic compound (preferably a styrene derivative, a phenol compound, more preferably styrene), and a resin obtained by hydrogenating the resin.

Examples of the α-methylstyrene-based resin include SYLVARES SA85 (SYLVATRAX 4401), SA100, SA120, SA140 (manufactured by Arizona Chemical Co.), FTR0100, 2120, 2140, 7100 (manufactured by Mitsui Chemicals, Inc.). Examples of the coumarone indene resin include G-90, V-120 (manufactured by Nikko Chemical Co., Ltd.), NOVARES C10, C30, C70, C80, C90, C100, C120, C140, C160 (Rutgers Chemicals). It is done. Examples of the aromatic modified terpene resin include YS resin TO85, TO105, TO115, TO125, Clearon M125, M115, M105, K100, K4100 (manufactured by Yasuhara Chemical Co., Ltd.) and the like. As terpene aromatic resins, YS polystar U130, U115, T160, T145, T130, T115, T100, T80, T30, S145, G150, G125, N125, K125, TH130, UH115 (manufactured by Yashara Chemical Co., Ltd.), Tamanoru 803L, 901 (made by Arakawa Chemical Co., Ltd.), SYVARES TP95, TP96, TP300, TP2040, TP2019, TP2040HM, TP7042, TP105, TP115 (made by Arizona Chemical Co., Ltd.) and the like.

The softening point of the aromatic resin is preferably 30 ° C. or higher, more preferably 60 ° C. or higher. The softening point is preferably 160 ° C. or lower, more preferably 130 ° C. or lower. If it is within the above numerical range, the effect of the present invention tends to be obtained better.
In the present invention, the softening point is a temperature at which the sphere descends when the softening point specified in JIS K 6220-1: 2001 is measured with a ring and ball softening point measuring device.

The content of the aromatic resin is 2 parts by mass or more, preferably 4 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, the said content is 10 mass parts or less, Preferably it is 7 mass parts or less. If it is within the above numerical range, the effect of the present invention tends to be obtained better.

Examples of the oil include process oil, vegetable oil and fat, or a mixture thereof. As the process oil, for example, a paraffin process oil, an aroma process oil, a naphthenic process oil, or the like can be used. As vegetable oils and fats, castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut hot water, rosin, pine oil, pineapple, tall oil, corn oil, rice bran oil, beet flower oil, sesame oil, Examples 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. Among these, process oil is preferable because the effects of the present invention can be obtained satisfactorily.

The liquid diene polymer is not particularly limited as long as it is a diene polymer having a weight average molecular weight of 50000 or less. For example, a styrene butadiene copolymer (rubber), a butadiene polymer (rubber), an isoprene polymer (rubber) ), Acrylonitrile butadiene copolymer (rubber), and the like. Especially, a liquid styrene butadiene copolymer (liquid SBR) and a liquid butadiene polymer (liquid BR) are preferable.

The weight average molecular weight (Mw) of the liquid diene polymer is preferably 1000 or more, more preferably 1500 or more. If Mw is less than 1000, the wear resistance tends to be reduced. Further, Mw is preferably 50000 or less, more preferably 20000 or less, and still more preferably 15000 or less. When Mw exceeds 50000, the performance on snow and ice, in particular, the initial performance on snow and ice tends to decrease. In addition, the difference in molecular weight from the rubber component becomes small, and the effect as a softening agent tends to be hardly exhibited.

Examples of the polyterpene resin include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, β-pinene / limonene resin, and hydrogenated terpene resins obtained by hydrogenating the terpene resin.

Content of a softening agent component is 5 mass parts or more with respect to 100 mass parts of rubber components, Preferably it is 10 mass parts or more. Moreover, the said content is 20 mass parts or less, Preferably it is 18 mass parts or less. If it is within the above numerical range, the effect of the present invention tends to be obtained better.

Examples of the softener component include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yashara Chemical Co., Ltd., Tosoh Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Arizona Chemical Co., Ltd. Nippon Shokubai Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., Idemitsu Kosan Co., Ltd., Sankyo Oil Chemical Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H & R Co., Ltd. Products such as Toyokuni Oil Co., Ltd., Showa Shell Sekiyu Co., Ltd., Fuji Kosan Co., Ltd. can be used.

The rubber composition of the present invention preferably contains zinc oxide.
Conventionally known zinc oxide can be used, for example, Mitsui Kinzoku Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd. Can be used.

The content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more with respect to 100 parts by mass of the rubber component. Further, the content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. If it is within the above numerical range, the effect of the present invention tends to be obtained better.

The rubber composition of the present invention preferably contains stearic acid.
A conventionally well-known thing can be used as a stearic acid, For example, products, such as NOF Corporation, NOF company, Kao Corporation, Wako Pure Chemical Industries, Ltd., and Chiba fatty acid company, can be used.

The content of stearic acid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more with respect to 100 parts by mass of the rubber component. Further, the content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. Within the above numerical range, the effects of the present invention tend to be obtained satisfactorily.

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

As the anti-aging agent, for example, products such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Co., Ltd., and Flexis Co. can be used.

The content of the antioxidant is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more with respect to 100 parts by mass of the rubber component. Further, the content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. Within the above numerical range, the effects of the present invention tend to be obtained satisfactorily.

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

As the sulfur, for example, products such as Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis Co., Nihon Kiboshi Kogyo Co., Ltd., Hosoi Chemical Co., Ltd. can be used.

The sulfur content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and still more preferably 3 parts by mass or less. Within the above numerical range, the effects of the present invention tend to be obtained satisfactorily.

The rubber composition of the present invention preferably contains a vulcanization accelerator.
Examples of the vulcanization accelerator include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide (TMTD ), Tetrabenzylthiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N) and other thiuram vulcanization accelerators; N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl- 2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N, N′-diisopropyl-2-benzothiazole sulfenamide, etc. Sulfena De-based vulcanization accelerator; diphenylguanidine, it may be mentioned di-ortho-tolyl guanidine, guanidine-based vulcanization accelerators such as ortho tri ruby guanidine. These may be used alone or in combination of two or more. Of these, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferred because the effects of the present invention can be obtained more suitably.

The content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. Further, the content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less. Within the above numerical range, the effects of the present invention tend to be obtained satisfactorily.

In addition to the above components, the rubber composition may contain additives commonly used in the tire industry, such as organic peroxides: calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica Examples thereof include fillers such as plasticizers, processing aids such as lubricants, and the like.

The rubber composition for a tread of the present invention can be produced by, for example, a method of kneading the above components using a rubber kneading apparatus such as an open roll or a Banbury mixer, and then vulcanizing.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition for tread. That is, a rubber composition containing the above components is extruded into a tread shape at an unvulcanized stage and molded together with other tire members on a tire molding machine by a normal method. Form a sulfur tire. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

The pneumatic tire of the present invention can be suitably used for passenger car tires, large passenger car tires, large SUV tires, heavy duty tires such as trucks and buses, and light truck tires.

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

Hereinafter, various chemicals used in Examples and Comparative Examples will be described.
NR: RSS # 3
SBR1: modified SBR (prepared in Production Example 1 below, styrene content 25% by mass, vinyl content 60% by mass, Mw 150,000, SBR (1))
SBR2: Modified SBR (prepared in Production Example 2 below, styrene content 15% by mass, vinyl content 65% by mass, Mw 200,000, SBR (1))
SBR3: Modified SBR (prepared in Production Example 3 below, styrene content 40% by mass, vinyl content 40% by mass, Mw 700,000, SBR (2))
SBR4: Modified SBR (prepared in Production Example 4 below, styrene content 35% by mass, vinyl content 50% by mass, Mw 700,000, SBR (2))
BR: Modified BR (prepared in Production Example 5 below, vinyl content 10% by mass, Mw 400,000)
Carbon black: N ₂ SA 111 m ² / g, DBP absorption 115 ml / 100 g
Silica: N ₂ SA 175 m ² / g
Silane coupling agent 1: NXT (3-octanoylthio-1-propyltriethoxysilane) manufactured by Momentive
Silane coupling agent 2: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Oil: naphthenic process oil resin 1: SYLVATRAX 4401 manufactured by Arizona Chemical Co. (α-methylstyrene resin (copolymer of α-methylstyrene and styrene), softening point 85 ° C., Tg 43 ° C.)
Resin 2: TO125 (aromatic modified terpene resin (terpene resin modified with styrene), softening point 125 ° C., Tg 80 ° C.) manufactured by Yasuhara Chemical Co., Ltd.
Zinc oxide: Zinc Hana No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Stearic acid “Kashiwa” manufactured by NOF Corporation
Anti-aging agent: N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. NS: Nt-butyl-2-benzo Thiazolylsulfenamide vulcanization accelerator DPG: N, N'-diphenylguanidine

(Production Example 1)
A nitrogen-substituted autoclave reactor was charged with cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene. After adjusting the temperature of the reactor contents to 20 ° C., n-butyllithium was added to initiate polymerization. Polymerization was performed under adiabatic conditions, and the maximum temperature reached 85 ° C. When the polymerization conversion rate reached 99%, butadiene was added and further polymerized for 5 minutes, and then 3-dimethylaminopropyltrimethoxysilane was added as a modifier and reacted for 15 minutes. After completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Subsequently, the solvent was removed by steam stripping, and drying was performed with a hot roll adjusted to 110 ° C. to obtain modified SBR (SBR1).

(Production Example 2)
A nitrogen-substituted autoclave reactor was charged with cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene. After adjusting the temperature of the reactor contents to 20 ° C., n-butyllithium was added to initiate polymerization. Polymerization was performed under adiabatic conditions, and the maximum temperature reached 85 ° C. When the polymerization conversion rate reached 99%, butadiene was added and further polymerized for 5 minutes, and then 3-dimethylaminopropyltrimethoxysilane was added as a modifier and reacted for 15 minutes. After completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Subsequently, the solvent was removed by steam stripping, and drying was performed with a hot roll adjusted to 110 ° C. to obtain modified SBR (SBR2).

(Production Example 3)
A nitrogen-substituted autoclave reactor was charged with cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene. After adjusting the temperature of the reactor contents to 20 ° C., n-butyllithium was added to initiate polymerization. Polymerization was performed under adiabatic conditions, and the maximum temperature reached 85 ° C. When the polymerization conversion rate reached 99%, butadiene was added and further polymerized for 5 minutes, and then 3-dimethylaminopropyltrimethoxysilane was added as a modifier and reacted for 15 minutes. After completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Subsequently, the solvent was removed by steam stripping, and drying was performed with a hot roll adjusted to 110 ° C. to obtain modified SBR (SBR3).

(Production Example 4)
Hexane, 1,3-butadiene, styrene, tetrahydrofuran, and ethylene glycol diethyl ether were charged into an autoclave reactor purged with nitrogen. Next, bis (diethylamino) methylvinylsilane and n-butyllithium were added as a cyclohexane solution and an n-hexane solution, respectively, to initiate polymerization.
The stirring speed was 130 rpm, the temperature in the reactor was 65 ° C., and 1,3-butadiene and styrene were copolymerized for 3 hours while continuously supplying the monomer into the reactor. Next, the obtained polymer solution was stirred at a stirring speed of 130 rpm, N- (3-dimethylaminopropyl) acrylamide was added, and the reaction was performed for 15 minutes. After completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Subsequently, the solvent was removed by steam stripping, and drying was performed with a hot roll adjusted to 110 ° C. to obtain modified SBR (SBR4).

(Production Example 5)
Under a nitrogen atmosphere, 3-dimethylaminopropyltrimethoxysilane was placed in a volumetric flask, and anhydrous hexane was added to prepare a terminal modifier.
N-Hexane, butadiene, and TMEDA were added to a pressure vessel sufficiently substituted with nitrogen, and the temperature was raised to 60 ° C. Next, after adding butyl lithium, the mixture was heated to 50 ° C. and stirred for 3 hours. Next, the terminal modifier was added and stirred for 30 minutes. After adding methanol and 2,6-tert-butyl-p-cresol to the reaction solution, the reaction solution was put into a stainless steel container containing methanol to collect aggregates. The obtained aggregate was dried under reduced pressure for 24 hours to obtain a modified BR.

(Examples and Comparative Examples)
According to the blending contents shown in Table 1, materials other than sulfur and a vulcanization accelerator were kneaded for 5 minutes at 150 ° C. using a Banbury mixer manufactured by Kobe Steel Co., Ltd. to obtain a kneaded product. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and 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, press vulcanized at 170 ° C. for 10 minutes, and a test tire ( Size: 195 / 65R15). The following evaluations were performed using the test tires obtained, and the results are shown in Table 1.

(Low fuel consumption performance)
Using a rolling resistance tester, the rolling resistance when a test tire is run at a rim (15 × 6JJ), internal pressure (230 kPa), load (3.43 kN), speed (80 km / h) is measured and compared. Example 1 is shown as an index when the index is 100 (low fuel consumption performance index). A larger index indicates better fuel efficiency.

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

From Table 1, an embodiment containing a predetermined amount of a predetermined rubber component, silica, a predetermined silane coupling agent, carbon black, and a predetermined softener component balances fuel efficiency and wet grip performance. It became clear that it could improve well.

Claims (2)

Styrene butadiene rubber (1) having a styrene content of 15 to 30% by mass and a weight average molecular weight of 100,000 to 300,000, a styrene butadiene rubber (2) having a styrene content of 35 to 55% by mass and a weight average molecular weight of 60 to 850,000, and a styrene content A rubber component containing a styrene butadiene rubber (3) having a weight average molecular weight of 300 to 550,000 or a butadiene rubber having a weight average molecular weight of 300 to 550,000, a silica, and a silane coupling represented by the following formula (S1) An agent, carbon black, and a softener component including an aromatic resin,
In 100% by mass of the rubber component, the content of the styrene butadiene rubber (1) is 40 to 55% by mass, the content of the styrene butadiene rubber (2) is 20 to 40% by mass, the styrene butadiene rubber (3) and The total content of the butadiene rubber is 10 to 20% by mass,
The silica content is 45 to 70 parts by mass, the carbon black content is 1 to 30 parts by mass, and the aromatic resin content is 2 to 10 parts by mass with respect to 100 parts by mass of the rubber component. The softener component content is 5 to 20 parts by mass,
The rubber composition for treads whose content of the said silane coupling agent is 3-15 mass parts with respect to 100 mass parts of said silicas.

[Wherein R ¹⁰⁰¹ represents —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 OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) may be the same or different and each have a hydrogen atom or a carbon number of 1 to 18 R is a monovalent hydrocarbon group, h has an average value of 1 to 4, and R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰³ is R ^{1001, R 1002,} a hydrogen atom or _{^{- [O (R 1009 O)}} j] 0.5 - group ^{(R 1009} represents an alkylene group having 1 to 18 carbon atoms, j is 1 to 4 Is an ^{integer.), R 1004} represents a divalent hydrocarbon ^{group, R 1005} is a monovalent hydrocarbon group having 1 to 18 carbon atoms having 1 to 18 carbon atoms, x, y and z, x + y + 2z = 3 , 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1. ] A pneumatic tire having a tread produced from the rubber composition according to claim 1.