JP5840971B2 - Rubber composition for tire and pneumatic tire - Google Patents

Description

The present invention relates to a rubber composition for tires and a pneumatic tire using the same.

In recent years, in response to the demand for lower fuel consumption in automobiles, tires with reduced rolling resistance and reduced heat generation have been developed. Exothermic property is required. Known methods for improving fuel economy include replacing carbon black, which has been used as a reinforcing filler, with silica, reducing the amount of filler, and using a filler with low reinforcing properties. However, these methods have a problem that the fracture performance and wear resistance are greatly reduced.

On the other hand, by using a modified polymer for silica having a functional group that interacts with a silane coupling agent or silica, it is possible to improve the dispersibility of silica, or chemically bond rubber and silica to achieve rolling resistance performance. Improvements in performance such as wear resistance are made. As for silica, it has been proposed to achieve both low fuel consumption and wear resistance by using silica having a high specific surface area or blending two types of silica having different specific surface areas (see Patent Document 1).

By using these methods, it is possible to improve the fuel economy, wear resistance, fracture performance, etc. to some extent, but there is a great demand for improvement, and further improvement of these performance balances is desired. .

JP 2008-50570 A

An object of the present invention is to solve the above-mentioned problems and to provide a rubber composition for tires that can improve fuel economy, wear resistance, and fracture performance in a well-balanced manner, and a pneumatic tire using the same.

The present invention relates to a rubber composition for a tire containing a rubber component and silica having an average primary particle diameter X (nm) and a nitrogen adsorption specific surface area Y (m ² / g) satisfying the following three formulas.
Y ≧ 370-9.0X
5.0 ≦ X ≦ 40.0
30 ≦ Y ≦ 500

The silica is preferably wet silica produced from water glass.
X is preferably 10.0 ≦ X ≦ 28.0.
The rubber composition preferably contains 10 parts by mass or more of silica with respect to 100 parts by mass of the rubber component.

The rubber component preferably contains a modified diene rubber having a functional group that interacts with silica.
The rubber composition preferably contains a silane coupling agent having a mercapto group.

（式（１）中、Ｒ^１０１〜Ｒ^１０３は、分岐若しくは非分岐の炭素数１〜１２のアルキル基、分岐若しくは非分岐の炭素数１〜１２のアルコキシ基、又は−Ｏ−（Ｒ^１１１−Ｏ）_ｚ−Ｒ^１１２（ｚ個のＲ^１１１は、分岐若しくは非分岐の炭素数１〜３０の２価の炭化水素基を表す。ｚ個のＲ^１１１はそれぞれ同一でも異なっていてもよい。Ｒ^１１２は、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、炭素数６〜３０のアリール基、又は炭素数７〜３０のアラルキル基を表す。ｚは１〜３０の整数を表す。）で表される基を表す。Ｒ^１０１〜Ｒ^１０３はそれぞれ同一でも異なっていてもよい。Ｒ^１０４は、分岐若しくは非分岐の炭素数１〜６のアルキレン基を表す。）

（式（２）及び（３）中、Ｒ^２０１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表す。Ｒ^２０２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表す。Ｒ^２０１とＲ^２０２とで環構造を形成してもよい。） The silane coupling agent having a mercapto group comprises a compound represented by the following formula (1) and / or a binding unit A represented by the following formula (2) and a binding unit B represented by the following formula (3). It is preferable that it is a compound containing.

(In the formula (1), R ^{101 to} R ¹⁰³ are each a branched or unbranched C 1-12 alkyl group, a branched or unbranched C 1-12 alkoxy group, or —O— (R ¹¹¹ — O) _z- R ¹¹² (z R ¹¹¹ represents a branched or unbranched divalent hydrocarbon group having 1 to 30 carbon atoms. The z R ^{111 s} may be the same as or different from each other. ¹¹² represents a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms. Z represents an integer of 1 to 30.) R ^{101 to} R ¹⁰³ may be the same as or different from each other, and R ¹⁰⁴ has 1 to 6 carbon atoms which are branched or unbranched. Represents an alkylene group of

(In the formulas (2) and (3), R ²⁰¹ is hydrogen, halogen, branched or unbranched alkyl group having 1 to 30 carbon atoms, branched or unbranched alkenyl group having 2 to 30 carbon atoms, branched or unbranched. Or an alkyl group substituted with a hydroxyl group or a carboxyl group, and R ²⁰² represents a branched or unbranched C 1-30 alkylene group, branched or It represents an unbranched C2-C30 alkenylene group or a branched or unbranched C2-C30 alkynylene group, and R ²⁰¹ and R ²⁰² may form a ring structure.)

The rubber composition is preferably a cap tread rubber composition.
The present invention also relates to a pneumatic tire produced using the rubber composition described above.

According to the present invention, since it is a rubber composition for tires containing specific silica, by applying the rubber composition to a tire member (particularly, cap tread), low fuel consumption, wear resistance, and fracture performance are achieved. It is possible to provide a pneumatic tire with an excellent performance balance.

The relationship figure of the average primary particle diameter X (nm) and nitrogen adsorption specific surface area Y (m < ² > / g) of the silica currently used by the Example and the comparative example.

The rubber composition for tires of the present invention contains a rubber component and specific silica having an average primary particle diameter X (nm) and a nitrogen adsorption specific surface area Y (m ² / g) satisfying the above three formulas. By blending the specific silica having the above three formulas with the rubber component, the performance balance of low fuel consumption, wear resistance and fracture performance can be improved remarkably and efficiently. This is presumed that when the specific silica is used, the silica is sufficiently dispersed in the rubber and the performance balance is greatly improved by the silica and the rubber being bonded more firmly.

The rubber component is not particularly limited, and natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), Examples thereof include diene rubbers such as chloroprene rubber (CR) and acrylonitrile butadiene rubber (NBR). A rubber component may be used independently and may use 2 or more types together. Among these, BR and SBR are preferable because the performance balance is excellent.

The BR is not particularly limited, and for example, BR having a high cis content, BR containing a syndiotactic polybutadiene crystal, and modified BR thereof can be used. Among these, BR having a cis content of 95% by mass or more is preferable because the effect of improving wear resistance is high.

The content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 15% by mass or more. If it is less than 5% by mass, sufficient wear resistance and fracture performance may not be obtained. The BR content is preferably 60% by mass or less, more preferably 50% by mass or less. If it exceeds 60% by mass, the fuel economy, wear resistance, and breaking performance may not be improved in a well-balanced manner.

SBR is not particularly limited, and for example, emulsion-polymerized styrene butadiene rubber (E-SBR), solution-polymerized styrene butadiene rubber (S-SBR), modified SBR thereof, and the like can be used. Of these, S-SBR is preferable.

The content of SBR in 100% by mass of the rubber component is preferably 30% by mass or more, more preferably 50% by mass or more. If it is less than 30% by mass, grip performance may not be secured, and the performance balance tends to be lowered. The SBR content is preferably 90% by mass or less, more preferably 80% by mass or less. If it exceeds 90% by mass, the desired performance balance may not be obtained.

Moreover, since the effect of this invention is acquired more efficiently, it is preferable to use the modified diene rubber which has a functional group in which a diene rubber interacts with a silica as a rubber component.

As the modified diene rubber, for example, at least one end of the diene rubber is modified with a compound (modifier) having a functional group containing at least one atom selected from the group consisting of nitrogen, oxygen and silicon. Terminal modified diene rubber, main chain modified diene rubber having the above functional group in the main chain, main chain terminal modified diene rubber having the above functional group in the main chain and terminal (for example, the above functional group in the main chain) And main chain terminal modified diene rubber having at least one terminal modified with the above modifier.

Examples of the functional groups include amino groups, amide groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, carboxyl groups, hydroxyl groups, nitrile groups, pyridyl groups, alkoxy groups, and the like. Is mentioned. These functional groups may have a substituent. Among these, an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), an amino group (preferably a hydrogen atom contained in the amino group has 1 to 6 carbon atoms) because it has a high effect of improving fuel economy and breaking performance. An amino group substituted with an alkyl group) or an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms).

Examples of the diene rubber into which the functional group is introduced (polymer constituting the skeleton of the modified diene rubber) include the above-mentioned diene rubbers, among which BR and SBR are preferable, and SBR is more preferable. By blending the specific silica with the modified BR or the modified SBR, the fuel efficiency, wear resistance, and breaking performance can be improved more efficiently, and the performance balance can be improved synergistically.

（式中、Ｒ^１、Ｒ^２及びＲ^３は、同一若しくは異なって、アルキル基、アルコキシ基（好ましくは炭素数１〜８、より好ましくは炭素数１〜６、更に好ましくは炭素数１〜４のアルコキシ基）、シリルオキシ基、アセタール基、カルボキシル基（−ＣＯＯＨ）、メルカプト基（−ＳＨ）又はこれらの誘導体を表す。Ｒ^４及びＲ^５は、同一若しくは異なって、水素原子、アルキル基（好ましくは炭素数１〜４のアルキル基）又は環状エーテル基（好ましくはエーテル結合を１つ有する炭素数３〜５の環状エーテル基（例えば、オキセタン基））を表す。ｎは整数（好ましくは１〜５、より好ましくは２〜４、更に好ましくは３）を表す。） As the modifying agent, a compound represented by the following formula (4) (a compound described in JP 2010-111753 A) is preferable. Thereby, it is easy to control the molecular weight of the polymer, the low molecular weight component that increases tan δ can be reduced, the bond between the silica and the polymer chain is moderately strengthened, and the fuel economy and breaking performance can be further improved.

(In formula, R < ¹ >, R < ² > and R < ³ > are the same or different, and are an alkyl group and an alkoxy group (preferably C1-C8, More preferably C1-C6, More preferably C1-C4 An alkoxy group), a silyloxy group, an acetal group, a carboxyl group (—COOH), a mercapto group (—SH) or a derivative thereof, and R ⁴ and R ⁵ are the same or different and represent a hydrogen atom, an alkyl group (preferably Represents an alkyl group having 1 to 4 carbon atoms) or a cyclic ether group (preferably a cyclic ether group having 3 to 5 carbon atoms having one ether bond (for example, oxetane group)), and n is an integer (preferably 1 to 1). 5, more preferably 2-4, still more preferably 3).)

As R ¹ , R ² and R ³ , an alkoxy group is desirable, and as R ⁴ and R ⁵ , an alkyl group is desirable. Thereby, the outstanding low fuel consumption and destruction performance can be obtained.

Specific examples of the compound represented by the above formula (4) include 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 2-dimethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 3 -Dimethylaminopropyltrimethoxysilane etc. are mentioned. These may be used alone or in combination of two or more.

Examples of the method for modifying the diene rubber with the compound (modifier) represented by the above formula (4) are described in JP-B-6-53768, JP-B-6-57767, JP-T2003-514078, and the like. A conventionally known method such as a known method can be used. For example, a diene rubber and a modifier may be brought into contact with each other, and examples thereof include a method of adding a modifier to the prepared diene rubber solution and reacting it.

（式中、Ｒ^２１は、炭素数が１〜１０の炭化水素基を表す。） The main chain-modified diene rubber can be prepared using a conventionally known polymerization method. For example, as part of the monomer used for polymerization, a monomer having the above functional group (for example, a compound represented by the following formula (5) such as p-methoxystyrene, 3- or 4- (2-pyrrolidinoethyl) Obtained by polymerization using a nitrogen-containing compound such as styrene). The main chain terminal-modified diene rubber is obtained, for example, by bringing a main chain modified diene rubber and a modifier into contact with each other.

(In the formula, R ²¹ represents a hydrocarbon group having 1 to 10 carbon atoms.)

In the above formula (5), R ²¹ represents a hydrocarbon group having 1 to 10 carbon atoms. If the carbon number exceeds 10, the cost tends to be high. In addition, there is a tendency that fuel efficiency and destruction performance cannot be sufficiently improved. The number of carbon atoms is preferably 1 to 8, more preferably 1 to 6, and still more preferably 1 to 3, from the viewpoint that the resulting polymer is highly effective in improving fuel economy and breaking performance.

Examples of the hydrocarbon group represented by R ²¹ include a monovalent aliphatic hydrocarbon group such as an alkyl group, and a monovalent aromatic hydrocarbon group such as an aryl group. R ²¹ is preferably an alkyl group, and more preferably a methyl group, from the viewpoint that the resulting polymer is highly effective in improving fuel economy and breaking performance.

（上記式（５−１）中のＲ^２１は、上記式（５）中のＲ^２１と同様である。） In addition, the compound represented by the following formula (5-1) is preferable among the compounds represented by the formula (5) from the viewpoint that the resulting copolymer has a high fuel economy and an improvement effect on breaking performance. .

^{(R 21} in the formula (5-1) is the same as ^{R 21} in the formula (5).)

Examples of the compound represented by the formula (5) include p-methoxystyrene, p-ethoxystyrene, p- (n-propoxy) styrene, p- (tert-butoxy) styrene, m-methoxystyrene, and the like. . These may be used alone or in combination of two or more.

The content of the compound represented by the above formula (5) in 100% by mass of the modified diene rubber (alkoxystyrene component content) is preferably 0.05% by mass or more, more preferably 0.5% by mass or more, More preferably, it is 1 mass% or more. If it is less than 0.05% by mass, it may be difficult to obtain an effect of improving fuel economy and breaking performance. The content is preferably 30% by mass or less, more preferably 15% by mass or less, still more preferably 5% by mass or less, and particularly preferably 2% by mass or less. When it exceeds 30 mass%, there exists a tendency for the effect corresponding to the increase in cost not to be acquired.
The alkoxystyrene component content can be measured using NMR (for example, JNM-ECA series apparatus manufactured by JEOL Ltd.).

Examples of the nitrogen-containing compound include 3- or 4- (2-azetidinoethyl) styrene, 3- or 4- (2-pyrrolidinoethyl) styrene, 3- or 4- (2-piperidinoethyl) styrene, 3- or 4- (2-hexamethyleneiminoethyl) styrene and the like can be mentioned. These may be used alone or in combination of two or more. Among these, 3- or 4- (2-pyrrolidinoethyl) styrene is preferable from the viewpoint that silica can be more favorably dispersed.

The content of the nitrogen-containing compound in 100% by mass of the modified diene rubber is preferably 0.05% by mass or more, more preferably 0.1% by mass or more. If it is less than 0.05% by mass, there is a tendency that it is difficult to obtain an effect of improving fuel economy and breaking performance. The content is preferably 10% by mass or less, more preferably 5% by mass or less. When it exceeds 10 mass%, there exists a tendency for the effect corresponding to the increase in cost not to be acquired.
In addition, content of a nitrogen-containing compound can be measured using NMR (For example, the apparatus of the JNM-ECA series by JEOL Co., Ltd.).

Among the above-mentioned modified diene rubbers, at least one terminal is modified with the compound represented by the above formula (4) because of its high effect of improving fuel economy and breaking performance (particularly fuel economy). SBR or BR is preferable, and is obtained by copolymerizing 1,3-butadiene, a compound represented by the above formula (5) and, if necessary, styrene, and at least one terminal is represented by the above formula (4). SBR or BR modified with a compound is more preferred.

The content of the modified diene rubber in 100% by mass of the rubber component is 5% by mass or more, preferably 15% by mass or more, and more preferably 50% by mass or more. If it is less than 5% by mass, sufficient fuel economy and destructive performance cannot be obtained. The upper limit of the content of the modified diene rubber is not particularly limited, and may be 100% by mass, but is preferably 90% by mass or less, more preferably 80% by mass or less from the viewpoint of the performance balance.

In the present invention, specific silica having an average primary particle diameter X (nm) and a nitrogen adsorption specific surface area Y (m ² / g) satisfying the following three formulas is used as the silica component.
Y ≧ 370-9.0X
5.0 ≦ X ≦ 40.0
30 ≦ Y ≦ 500

When Y <370-9.0X, low fuel consumption, wear resistance, and destructive performance, particularly wear resistance and destructive performance are low, and the performance balance tends to be inferior.

X is preferably 10.0 ≦ X ≦ 28.0, more preferably 10.0 ≦ X ≦ 25.0, still more preferably 12.0 ≦ X ≦ 24.0, and particularly preferably 14.0 ≦ X. ≦ 23.0. Y is preferably 50 ≦ Y ≦ 400, more preferably 80 ≦ Y ≦ 300, still more preferably 150 ≦ Y ≦ 280, and particularly preferably 180 ≦ Y ≦ 260. When X> 40.0 or Y <30, the reinforcing property is insufficient, the fuel efficiency, the wear resistance, and the breaking performance are low, and the performance balance tends to be inferior. When X <5.0 or Y> 500, the processability decreases, the dispersibility of silica decreases, and these performances tend to decrease.

The average primary particle diameter X can be determined from, for example, the observation of silica alone with an electron microscope, the measurement of the particle diameter of any 50 particles, and the average value. Nitrogen adsorption specific surface area _{Y (N} 2 SA) can be measured by the BET method in conformity with ASTM-D-4820-93.

Specific silica includes, for example, silica obtained by a dry method (anhydrous silicic acid), silica obtained by a wet method (hydrous silicic acid), etc., and is wet from the point that it has many silanol groups and is excellent in processability and fuel efficiency. Silica obtained by the method is preferred.

Moreover, as a specific silica obtained by a wet method, what is manufactured from water glass is preferable, For example, the fine particle silica manufactured by adjusting pH of a water glass aqueous solution to 9-11 can be used conveniently.

The water glass is usually represented by a composition represented by the following formula.
Na ₂ O · nSiO ₂ · mH ₂ O
The coefficient n is a value represented by a molecular ratio of SiO ₂ / Na ₂ O, and is a range defined in JIS K 1408-1966 generally called a molar ratio. Although this coefficient n is not specifically limited, Preferably it is 2.1-3.3, More preferably, it is 3.1-3.3. When the coefficient n is 3.1 to 3.3, the silica component (SiO ₂ equivalent amount) in the water glass increases, so that it can be efficiently combined with rubber.

In general, the water glass having the coefficient n of 3.1 to 3.3 is commercially available as Water Glass No. 3. The water glass which can be used for this invention is not limited to this, For example, No. 1-3 water glass prescribed | regulated to JISK1408, and other various grade products can be used.

By preparing an aqueous solution of water glass and adjusting the pH of the aqueous solution to a range of 9 to 11, a fine particle silica dispersion in which fine particle silica having an average primary particle diameter of 40.0 nm or less is dispersed can be prepared. The specific silica in the present invention can be produced by washing and drying by a known method. When the pH is less than 9, gelation tends to occur, and when the pH exceeds 11, the fine particle silica tends to dissolve. More preferably, the pH is adjusted to a range of 9.5 to 10.5. The method for adjusting the pH to the range of 9 to 11 is not particularly limited, and can be performed by a conventionally known method such as addition of an acid or alkali, use of an ion exchange resin, or the like.

Examples of the acid that can be used for adjusting the pH include inorganic acids such as sulfuric acid, nitric acid, and hydrochloric acid, and organic acids such as acetic acid. Examples of the alkali include aqueous ammonia, sodium hydroxide, and potassium hydroxide.

Examples of the pH adjustment method using an ion exchange resin include a method of bringing an aqueous solution of water glass into contact with a cation exchange resin. For example, an H-type strong acid cation exchange resin, a weak acid cation exchange resin, or the like can be used. What is necessary is just to ion-exchange by a well-known method using a cation exchange resin.

When adjusting the pH, the temperature of the aqueous solution of water glass is preferably adjusted to 10 to 90 ° C. If the temperature is less than 10 ° C., the production rate of fine-particle silica is slow, and if the temperature exceeds 90 ° C., water in the aqueous solution evaporates, and the concentration of water glass in the aqueous solution tends to become unstable. What is necessary is just to adjust the temperature of the said aqueous solution suitably, and 15-40 degreeC and 60-80 degreeC are mentioned as a preferable range, for example.

The reaction time is preferably in the range of 30 minutes to 72 hours. If it is less than 30 minutes, the formation of fine-particle silica is not sufficient, and even if it exceeds 72 hours, the reaction has already ended and there is a tendency that there is no further change. When making it react at room temperature, it is suitable to carry out for 6 to 24 hours on stirring conditions. Further, in order to be as close to a true sphere as possible, aging at a high temperature and a long time is good, and a temperature of 60 to 80 ° C. for 24 hours or more is preferable.

The concentration of the silica component (SiO ₂ ) contained in the aqueous water glass solution is preferably in the range of 1 to 30% by mass. When the concentration is less than 1% by mass, a large amount of water glass aqueous solution is required for compounding with the rubber, and when it exceeds 30% by mass, silica aggregation tends to occur. The concentration of the silica component is more preferably in the range of 1.5 to 20% by mass, still more preferably 2 to 8% by mass. However, when water glass that has been subjected to desalting treatment is used, the upper limit is not particularly limited because silica aggregation is unlikely to occur.

The specific silica in the present invention satisfies the above three formulas, but by adjusting the pH of the water glass aqueous solution, the concentration of the silica component, the reaction temperature, the reaction time, etc., the average primary particle diameter and N ₂ SA are appropriately adjusted. Can be adjusted and manufactured.

The rubber composition of the present invention may contain only the specific silica alone as a silica component, but may contain other silica within a range not inhibiting the effect. Examples of other silica include commercially available products known in the tire industry.

In the rubber composition of the present invention, the total content of silica is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, and still more preferably 50 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 10 parts by mass, the effects of improving fuel economy, wear resistance, and fracture performance tend to be insufficient. The total content is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and still more preferably 100 parts by mass or less. When it exceeds 150 parts by mass, it becomes difficult to disperse silica into rubber, and the fuel economy, wear resistance, and fracture performance tend to be lowered.

When blending the specific silica satisfying the formula 3 and other silicas, the content of the specific silica in 100% by mass of the total silica to be blended is preferably 10% by mass or more, more preferably 15% by mass or more. . If it is less than 10%, there is a possibility that the performance balance of fuel efficiency, wear resistance, and fracture performance cannot be improved.

The rubber composition of the present invention preferably uses a silane coupling agent in combination with silica. As the silane coupling agent, any silane coupling agent conventionally used in combination with silica can be used in the rubber industry. For example, sulfide systems such as bis (3-triethoxysilylpropyl) tetrasulfide, 3 -Mercapto type such as mercaptopropyltrimethoxysilane, vinyl type such as vinyltriethoxysilane, amino type such as 3-aminopropyltriethoxysilane, glycidoxy type of γ-glycidoxypropyltriethoxysilane, 3-nitropropyltri Examples thereof include nitro compounds such as methoxysilane and chloro compounds such as 3-chloropropyltrimethoxysilane. These may be used alone or in combination of two or more. Among them, a mercapto-based silane coupling agent is preferable because of its high performance improvement rate. In particular, by using the modified diene rubber, specific silica, and a mercapto-based silane coupling agent, the performance is remarkable and synergistic. Balance can be improved.

（式（１）中、Ｒ^１０１〜Ｒ^１０３は、分岐若しくは非分岐の炭素数１〜１２のアルキル基、分岐若しくは非分岐の炭素数１〜１２のアルコキシ基、又は−Ｏ−（Ｒ^１１１−Ｏ）_ｚ−Ｒ^１１２（ｚ個のＲ^１１１は、分岐若しくは非分岐の炭素数１〜３０の２価の炭化水素基を表す。ｚ個のＲ^１１１はそれぞれ同一でも異なっていてもよい。Ｒ^１１２は、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、炭素数６〜３０のアリール基、又は炭素数７〜３０のアラルキル基を表す。ｚは１〜３０の整数を表す。）で表される基を表す。Ｒ^１０１〜Ｒ^１０３はそれぞれ同一でも異なっていてもよい。Ｒ^１０４は、分岐若しくは非分岐の炭素数１〜６のアルキレン基を表す。）

（式（２）及び（３）中、Ｒ^２０１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表す。Ｒ^２０２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表す。Ｒ^２０１とＲ^２０２とで環構造を形成してもよい。） As a silane coupling agent having a mercapto group, a compound represented by the following formula (1), a compound containing a binding unit A represented by the following formula (2) and a binding unit B represented by the following formula (3): It can be suitably used.

(In the formula (1), R ^{101 to} R ¹⁰³ are each a branched or unbranched C 1-12 alkyl group, a branched or unbranched C 1-12 alkoxy group, or —O— (R ¹¹¹ — O) _z- R ¹¹² (z R ¹¹¹ represents a branched or unbranched divalent hydrocarbon group having 1 to 30 carbon atoms. The z R ^{111 s} may be the same as or different from each other. ¹¹² represents a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms. Z represents an integer of 1 to 30.) R ^{101 to} R ¹⁰³ may be the same as or different from each other, and R ¹⁰⁴ has 1 to 6 carbon atoms which are branched or unbranched. Represents an alkylene group of

(In the formulas (2) and (3), R ²⁰¹ is hydrogen, halogen, branched or unbranched alkyl group having 1 to 30 carbon atoms, branched or unbranched alkenyl group having 2 to 30 carbon atoms, branched or unbranched. Or an alkyl group substituted with a hydroxyl group or a carboxyl group, and R ²⁰² represents a branched or unbranched C 1-30 alkylene group, branched or It represents an unbranched C2-C30 alkenylene group or a branched or unbranched C2-C30 alkynylene group, and R ²⁰¹ and R ²⁰² may form a ring structure.)

Hereinafter, the compound represented by Formula (1) is demonstrated.

By using the compound represented by Formula (1), silica is dispersed well, and the effects of the present invention are obtained well. In particular, the fuel efficiency can be greatly improved.

R ^{101 to} R ¹⁰³ are each a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or —O— (R ¹¹¹ —O) _z —R ¹¹² . Represents the group represented. From the viewpoint that the effect of the present invention can be obtained satisfactorily, at least one of R ^{101 to} R ¹⁰³ is preferably a group represented by —O— (R ¹¹¹ —O) _z —R ¹¹² , and two of them are — More preferably, it is a group represented by O— (R ¹¹¹ —O) _z —R ¹¹² , and one is a branched or unbranched C 1-12 alkoxy group.

Examples of the branched or unbranched alkyl group having 1 to 12 carbon atoms (preferably 1 to 5 carbon atoms) represented by R ^{101 to} R ¹⁰³ include, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and n-butyl. Group, iso-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group and the like.

Examples of the branched or unbranched alkoxy group having 1 to 12 carbon atoms (preferably 1 to 5 carbon atoms) of R ^{101 to} R ¹⁰³ include, for example, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, n- Examples include butoxy, iso-butoxy, sec-butoxy, tert-butoxy, pentyloxy, hexyloxy, heptyloxy, 2-ethylhexyloxy, octyloxy, nonyloxy and the like.

In —O— (R ¹¹¹ —O) _z —R ¹¹² of R ^{101 to} R ¹⁰³ , R ¹¹¹ represents a branched or unbranched carbon number of 1 to 30 (preferably having 1 to 15 carbon atoms, more preferably 1 carbon number). To 3) a divalent hydrocarbon group.
Examples of the hydrocarbon group include a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, and a branched or unbranched alkynylene group having 2 to 30 carbon atoms. And an arylene group having 6 to 30 carbon atoms. Of these, a branched or unbranched alkylene group having 1 to 30 carbon atoms is preferable.

Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms (preferably 1 to 15 carbon atoms, more preferably 1 to 3 carbon atoms) of R ¹¹¹ include, for example, a methylene group, an ethylene group, a propylene group, and a butylene group. Pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, octadecylene group and the like.

Examples of the branched or unbranched carbon atoms 2-30 alkenylene group (preferably 2 to 15 carbon atoms, more preferably 2 to 3 carbon atoms) of R ^111, for example, vinylene group, propenylene group, 2-propenylene Group, 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group, 1-hexenylene group, 2-hexenylene group, 1-octenylene group and the like.

Examples of the branched or unbranched carbon atoms 2-30 alkynylene group (preferably 2 to 15 carbon atoms, more preferably 2 to 3 carbon atoms) of R ^111, for example, ethynylene group, propynylene group, butynylene group, pentynylene group Hexynylene group, heptynylene group, octynylene group, noninylene group, decynylene group, undecynylene group, dodecynylene group and the like.

Examples of the arylene group having 6 to 30 carbon atoms (preferably 6 to 15 carbon atoms) of R ¹¹¹ include a phenylene group, a tolylene group, a xylylene group, and a naphthylene group.

z represents an integer of 1 to 30 (preferably 2 to 20, more preferably 3 to 7, further preferably 5 to 6).

R ¹¹² represents a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms. Represent. Of these, a branched or unbranched alkyl group having 1 to 30 carbon atoms is preferable.

Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms (preferably 3 to 25 carbon atoms, more preferably 10 to 15 carbon atoms) of R ¹¹² include, for example, a methyl group, an ethyl group, an n-propyl group, Isopropyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, 2-ethylhexyl, octyl, nonyl, decyl, undecyl , Dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, octadecyl group and the like.

Examples of the branched or unbranched alkenyl group having 2 to 30 carbon atoms (preferably 3 to 25 carbon atoms, more preferably 10 to 15 carbon atoms) for R ¹¹² include, for example, a vinyl group, a 1-propenyl group, and 2-propenyl. Group, 1-butenyl group, 2-butenyl group, 1-pentenyl group, 2-pentenyl group, 1-hexenyl group, 2-hexenyl group, 1-octenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group Group, pentadecenyl group, octadecenyl group and the like.

Examples of the aryl group having 6 to 30 carbon atoms (preferably 10 to 20 carbon atoms) represented by R ¹¹² include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a biphenyl group.

Examples of the aralkyl group having 7 to 30 carbon atoms (preferably 10 to 20 carbon atoms) of R ¹¹² include a benzyl group and a phenethyl group.

Specific examples of the group represented by —O— (R ¹¹¹ —O) _z —R ¹¹² include, for example, —O— (C ₂ H ₄ —O) ₅ —C ₁₁ H ₂₃ , —O— (C _{2 H 4 -O) 5 -C 12 H} 25, -O- (C 2 H 4 -O) 5 -C 13 H 27, -O- (C 2 H 4 -O) 5 -C 14 H 29, -O _{- (C 2 H 4 -O)} 5 -C 15 H 31, -O- (C 2 H 4 -O) 3 -C 13 H 27, -O- (C 2 H 4 -O) 4 -C 13 H _{27, -O- (C 2 H 4} -O) 6 -C 13 H 27, and the like _{-O- (C 2 H 4 -O)} 7 -C 13 H 27. Among _{these, -O- (C 2 H 4 -O} ) 5 -C 11 H 23, -O- (C 2 H 4 -O) 5 -C 13 H 27, -O- (C 2 H 4 -O) 5 _{-C 15 H 31, -O- (C} 2 H 4 -O) 6 -C 13 H 27 are preferable.

Examples of the branched or unbranched alkylene group having 1 to 6 carbon atoms (preferably 1 to 5 carbon atoms) of R ¹⁰⁴ include the same groups as the branched or unbranched alkylene group having 1 to 30 carbon atoms of R ^111. Can give.

Examples of the compound represented by the formula (1) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the following formula: The compound represented by the following formula (Si363 manufactured by EVONIK-DEGUSSA) and the like can be used, and a compound represented by the following formula can be preferably used. These may be used alone or in combination of two or more.

Next, the compound containing the bond unit A represented by the formula (2) and the bond unit B represented by the formula (3) will be described.

The compound containing the bond unit A represented by the formula (2) and the bond unit B represented by the formula (3) is more viscous during processing than a polysulfide silane such as bis- (3-triethoxysilylpropyl) tetrasulfide. The rise is suppressed. This is presumably because the increase in Mooney viscosity is small because the sulfide portion of the bond unit A is a C—S—C bond and is thermally stable compared to tetrasulfide and disulfide.

Moreover, the shortening of the scorch time is suppressed as compared with mercaptosilane such as 3-mercaptopropyltrimethoxysilane. This is because the bonding unit B has a structure of mercaptosilane, but the —C ₇ H ₁₅ part of the bonding unit A covers the —SH group of the bonding unit B, so that it does not easily react with the polymer and scorch is less likely to occur. This is probably because of this.

In the silane coupling agent having the above structure, the content of the bond unit A is preferably 30 from the viewpoint that the effect of suppressing the increase in viscosity during processing and the effect of suppressing the shortening of the scorch time can be enhanced. It is at least mol%, more preferably at least 50 mol%, preferably at most 99 mol%, more preferably at most 90 mol%. Further, the content of the bond unit B is preferably 1 mol% or more, more preferably 5 mol% or more, further preferably 10 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or less, More preferably, it is 55 mol% or less. Further, the total content of the binding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%.
The content of the bond units A and B is an amount including the case where the bond units A and B are located at the terminal of the silane coupling agent. The form in which the bonding units A and B are located at the end of the silane coupling agent is not particularly limited, as long as the units corresponding to the formulas (2) and (3) indicating the bonding units A and B are formed. .

Examples of the halogen for R ²⁰¹ include chlorine, bromine, and fluorine.

^Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms of R ²⁰¹ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, iso-butyl group, sec-butyl group, tert- Examples thereof include a butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, and a decyl group. The number of carbon atoms of the alkyl group is preferably 1-12.

^Examples of the branched or unbranched C 2-30 alkenyl group of R ²⁰¹ include a vinyl group, 1-propenyl group, 2-propenyl group, 1-butenyl group, 2-butenyl group, 1-pentenyl group, and 2-pentenyl. Group, 1-hexenyl group, 2-hexenyl group, 1-octenyl group and the like. The alkenyl group preferably has 2 to 12 carbon atoms.

^Examples of the branched or unbranched alkynyl group having 2 to 30 carbon atoms of R ²⁰¹ include ethynyl group, propynyl group, butynyl group, pentynyl group, hexynyl group, heptynyl group, octynyl group, nonynyl group, decynyl group, undecynyl group, A dodecynyl group etc. are mentioned. The alkynyl group preferably has 2 to 12 carbon atoms.

Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms of R ²⁰² include an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, an undecylene group, Examples include dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, and octadecylene group. The alkylene group preferably has 1 to 12 carbon atoms.

^Examples of the branched or unbranched C2-C30 alkenylene group of R202 include vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group and 2-pentenylene. Group, 1-hexenylene group, 2-hexenylene group, 1-octenylene group and the like. The alkenylene group preferably has 2 to 12 carbon atoms.

Examples of branched or unbranched alkynylene group having 2 to 30 carbon atoms R ^202, ethynylene group, propynylene group, butynylene group, pentynylene group, hexynylene group, heptynylene group, octynylene group, nonynylene group, decynylene group, undecynylene group, And dodecynylene group. The alkynylene group preferably has 2 to 12 carbon atoms.

In the compound containing the bond unit A represented by the formula (2) and the bond unit B represented by the formula (3), the repetition of the total of the repeating number (x) of the bonding unit A and the repeating number (y) of the bonding unit B The number (x + y) is preferably in the range of 3 to 300. Within this range, since the mercaptosilane of the bond unit B is covered by —C ₇ H ₁₅ of the bond unit A, it is possible to suppress the scorch time from being shortened and to have good reactivity with silica and rubber components. Can be secured.

For example, NXT-Z30, NXT-Z45, NXT-Z60, etc. manufactured by Momentive are used as the compound containing the binding unit A represented by the formula (2) and the coupling unit B represented by the formula (3). Can do. These may be used alone or in combination of two or more.

The rubber composition of the present invention may be used by blending other silane coupling agents together with the silane coupling agent having a mercapto group.

The content of the silane coupling agent is preferably 0.5 parts by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of silica. If the amount is less than 0.5 parts by mass, the viscosity of the unvulcanized rubber composition tends to be high, the processability tends to deteriorate, and the fuel economy, fracture performance, and wear resistance tend to decrease. Further, the content of the silane coupling agent is preferably 20 parts by mass or less, more preferably 10 parts by mass or less. When the amount exceeds 20 parts by mass, the effect corresponding to the amount added cannot be obtained, and only the cost is increased.

In addition to the above components, the rubber composition of the present invention includes compounding agents generally used in the production of rubber compositions, for example, reinforcing fillers such as carbon black and clay, softeners such as oil, zinc oxide, Stearic acid, various anti-aging agents, vulcanizing agents such as wax and sulfur, vulcanization accelerators and the like can be appropriately blended.

The rubber composition of the present invention can be used for each member of a tire, and among these, it is preferably used for a tread portion, and particularly preferably used for a cap tread.

As a method for producing the rubber composition for tires of the present invention, known methods can be used. For example, the above components are kneaded using a rubber kneader such as an open roll or a Banbury mixer, and then vulcanized. Etc. can be manufactured.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition.
That is, the rubber composition containing the above components is extruded in accordance with the shape of each tire member such as a tread at an unvulcanized stage, and is molded together with the other tire members by a normal method on a tire molding machine. Thus, an unvulcanized tire is formed, and the unvulcanized tire can be heated and pressurized in a vulcanizer to produce the tire.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.
Various chemicals used in the synthesis of the following silicas A to B will be described.
NaOH: NaOH manufactured by Wako Pure Chemical Industries, Ltd.
Water glass: Water glass No. 3 manufactured by Fuji Chemical Co., Ltd. (Na ₂ O.nSiO ₂ .mH ₂ O, n = 3.2, silica component (SiO ₂ equivalent) content: 28% by mass)

(Silica A)
A water glass aqueous solution having a silica component content (concentration) of 2% by mass was prepared using water glass, adjusted to pH 10 with sulfuric acid, and stirred at 80 ° C. for 60 minutes to prepare a silica dispersion. This silica dispersion was filtered, washed repeatedly with water, and then spray-dried to obtain silica A. The obtained silica A had an average primary particle diameter of 16.5 nm and a nitrogen adsorption specific surface area of 245 m ² / g.

(Silica B)
A water glass aqueous solution having a silica component content (concentration) of 2% by mass was prepared using water glass, adjusted to pH 10 with sulfuric acid, and stirred at 80 ° C. for 90 minutes to prepare a silica dispersion. This silica dispersion was filtered, washed repeatedly with water, and then spray-dried to obtain silica B. The obtained silica B had an average primary particle diameter of 22.0 nm and a nitrogen adsorption specific surface area of 195 m ² / g.

Various chemicals used in the synthesis of the following main chain terminal-modified SBR will be described.
n-hexane: Kanto Chemical Co., Ltd. Styrene: Kanto Chemical Co., Ltd. 1,3-Butadiene: Tokyo Chemical Industry Co., Ltd. p-methoxystyrene: Kanto Chemical Co., Ltd. Tetramethylethylenediamine: Kanto Chemical Co., Ltd. ) N-butyllithium: 1.6M n-butyllithium hexane solution modifier manufactured by Kanto Chemical Co., Ltd .: 3- (N, N-dimethylaminopropyl) trimethoxysilane 2,6-tert- Butyl-p-cresol: NOCRACK 200 manufactured by Ouchi Shinsei Chemical Co., Ltd.

(Synthesis of main chain terminal modified SBR)
Add 1500 ml of n-hexane, 100 mmol of styrene, 800 mmol of 1,3-butadiene, 5 mmol of p-methoxystyrene, 0.2 mmol of tetramethylethylenediamine, and 0.12 mmol of n-butyllithium to a heat-resistant container sufficiently purged with nitrogen at 0 ° C. Stir for 48 hours. Thereafter, 0.15 mmol of a modifier was added and stirred at 0 ° C. for 1 hour. Thereafter, alcohol was added to stop the reaction, 1 g of 2,6-tert-butyl-p-cresol was added to the reaction solution, and then modified SBR was obtained by reprecipitation purification. The obtained modified SBR had a weight average molecular weight of 500,000, a p-methoxystyrene component content of 1.2% by mass, and a styrene component content of 19% by mass.

Various chemicals used in the following examples and comparative examples will be described.
BR: Ubepol BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass)
SBR: Nipol NS116 (S-SBR, vinyl content: 60% by mass, styrene content: 20% by mass) manufactured by Nippon Zeon Co., Ltd.
Modified SBR: Main chain terminal modified SBR prepared above
Silica A: Silica A synthesized above
Silica B: Silica B synthesized above
Silica a: Ultrasil VN3 (average primary particle size: 15 nm, N ₂ SA: 175 m ² / g) manufactured by EVONIK-DEGUSSA
Silica b: 115GR manufactured by Rhodia (average primary particle size: 22 nm, N ₂ SA: 115 m ² / g)
Silane coupling agent Si69: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by EVONIK-DEGUSSA
Silane coupling agent Si363: Si363 manufactured by Evonik Degussa (silane coupling agent represented by the following formula (R ^{101 in the} above formula (1) = — O— (C ₂ H ₄ —O) ₅ —C ₁₃ H) ^{_{27, R 102 = -O-C}} 2 H 5, R 103 = -O- (C 2 H 4 -O) 5 -C 13 H 27, R 104 = -C 3 H 6 -))
Silane coupling agent NXT-Z45: NXT-Z45 manufactured by Momentive (copolymer of bonding unit A and bonding unit B (bonding unit A: 55 mol%, bonding unit B: 45 mol%))
Oil: Process X-140 manufactured by Japan Energy Co., Ltd.
Zinc oxide: Zinc Hua No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Anti-aging agent manufactured by NOF Corporation: NOCRACK 6C (N- (1,3-3-) manufactured by Ouchi Shinsei Chemical Co., Ltd. Dimethylbutyl) -N′-phenyl-p-phenylenediamine)
Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. NS: Noxera-NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator DPG: Noxeller D (N, N'-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Co., Ltd.

[Examples and Comparative Examples]
According to the formulation shown in Tables 1 to 4, materials other than sulfur and a vulcanization accelerator were kneaded for 4 minutes using a 1.7 L Banbury mixer to obtain a kneaded product. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 3 minutes at 80 ° C. using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press vulcanized at 170 ° C. for 15 minutes to obtain a vulcanized rubber composition.
The following evaluation was performed about the obtained vulcanized rubber composition. The results are shown in Tables 1-4.

(Rolling resistance)
Loss tangent of each compound (each vulcanized rubber composition) under the conditions of a temperature of 50 ° C., an initial strain of 10%, a dynamic strain of 2%, and a frequency of 10 Hz using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.) (Tan δ) was measured. In each table, the loss tangent tan δ of the reference comparative example (Comparative Examples 1, 2, 3, or 4) was set to 100, and indexed by the following formula. The greater the rolling resistance index, the better the rolling resistance characteristics.
(Rolling resistance index) = (tan δ of reference comparative example) / (tan δ of each formulation) × 100

(Destructive performance)
Using the obtained vulcanized rubber sheet, a No. 3 dumbbell-shaped rubber test piece was prepared, and subjected to a tensile test according to JIS K 6251 “Vulcanized rubber and thermoplastic rubber-Determination of tensile properties”. (TB) and elongation at break (EB) were measured, and the product (TB × EB) was calculated. In each table, the rubber strength (TB × EB) of the reference comparative example (Comparative Examples 1, 2, 3 or 4) was set to 100, and an index was displayed by the following calculation formula. The larger the fracture performance index, the better the fracture performance.
(Destructive performance index) = (TB of each formulation × EB) / (TB of the reference comparative example × EB) × 100

(Abrasion resistance)
For the obtained vulcanized rubber composition, the amount of Lambourn wear was measured using a Lambourn abrasion tester under the conditions of a temperature of 20 ° C., a slip rate of 20% and a test time of 2 minutes, and the volume loss was calculated from the amount of abrasion. did. In each table, the volume loss amount of the reference comparative example (Comparative Examples 1, 2, 3, or 4) was set to 100, and the index was expressed by the following calculation formula. The larger the Lambourn wear index, the better the wear resistance.
(Lambourn wear index) = (volume loss amount of reference comparative example) / (volume loss amount of each formulation) × 100

From the results of Table 1, in the blended system containing silica A as in Examples 1 to 3, compared to Comparative Example 1 using the conventional silica a, the fracture performance is maintained while maintaining good rolling resistance. The wear resistance was greatly improved, and the balance of these performances was greatly improved. Also in the blending system using the modified polymer for silica in Table 2, the same improvement effect as in Table 1 was confirmed, and the improvement rate was larger than that of the blending system in Table 1 using the unmodified polymer. Improved performance balance.

The compounding system using the mercapto-based silane coupling agent shown in Table 3 is confirmed to have the same improvement effect as in Table 1, and the improvement rate is larger than that of the compounding system not using the mercapto system, and the performance balance is improved efficiently. It was. In particular, the performance balance was remarkably and synergistically improved by blending the three components of the modified polymer, silica A, and mercapto silane coupling agent.

From the results shown in Table 4, it was confirmed that, even in the blended system containing silica B, the fracture performance and wear resistance were greatly improved while maintaining good rolling resistance as in the case of silica A.

Claims (8)

A rubber composition for a tire containing a rubber component and silica having an average primary particle diameter X (nm) and a nitrogen adsorption specific surface area Y (m ² / g) satisfying the following three formulas.
Y ≧ 370-9.0X
10.0 ≦ X ≦ 28.0
30 ≦ Y ≦ 500 The tire rubber composition according to claim 1, wherein the silica is hydrous silicic acid . The rubber composition for a tire according to claim 1 or 2 , comprising 10 parts by mass or more of silica with respect to 100 parts by mass of the rubber component. The tire rubber composition according to any one of claims 1 to 3 , wherein the rubber component contains a modified diene rubber having a functional group that interacts with silica. The rubber composition for tires according to any one of claims 1 to 4 , comprising a silane coupling agent having a mercapto group. The silane coupling agent having the mercapto group comprises a compound represented by the following formula (1) and / or a binding unit A represented by the following formula (2) and a binding unit B represented by the following formula (3). The rubber composition for a tire according to claim 5 , which is a compound containing the tire.

(In the formula (1), R ^{101 to} R ¹⁰³ are each a branched or unbranched C 1-12 alkyl group, a branched or unbranched C 1-12 alkoxy group, or —O— (R ¹¹¹ — O) _z- R ¹¹² (z R ¹¹¹ represents a branched or unbranched divalent hydrocarbon group having 1 to 30 carbon atoms. The z R ^{111 s} may be the same as or different from each other. ¹¹² represents a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms. Z represents an integer of 1 to 30.) R ^{101 to} R ¹⁰³ may be the same as or different from each other, and R ¹⁰⁴ has 1 to 6 carbon atoms which are branched or unbranched. Represents an alkylene group of

(In the formulas (2) and (3), R ²⁰¹ is hydrogen, halogen, branched or unbranched alkyl group having 1 to 30 carbon atoms, branched or unbranched alkenyl group having 2 to 30 carbon atoms, branched or unbranched. Or an alkyl group substituted with a hydroxyl group or a carboxyl group, and R ²⁰² represents a branched or unbranched C 1-30 alkylene group, branched or It represents an unbranched C2-C30 alkenylene group or a branched or unbranched C2-C30 alkynylene group, and R ²⁰¹ and R ²⁰² may form a ring structure.) The rubber composition for tires according to any one of claims 1 to 6 , which is a rubber composition for cap treads. A pneumatic tire produced using the rubber composition according to any one of claims 1-7.

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