JP5992770B2 - 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, tires with reduced rolling resistance and reduced heat generation have been developed in response to demands for lower fuel consumption in automobiles, especially for treads with high occupation ratios in tires. Low heat generation is required. As a method of improving low heat build-up, a method of replacing part of the reinforcing filler carbon black with silica has been proposed, and as a further improvement method, reducing the weight of the filler or using a filler having a low reinforcing property is also possible. Although being studied, wear resistance, wet grip performance, and rubber strength tend to decrease.

Highly reactive mercapto-based silanes are considered to be able to improve fuel economy, wear resistance, wet grip performance, and rubber strength in a well-balanced manner if the bond between the silica and the silica in the silica rubber composition becomes stronger. Promotion of chemical bonding between rubber and silica, such as a method using a coupling agent (see Patent Document 1) and a method using a modified diene rubber containing a functional group that interacts with silica (see Patent Document 2) A way to do this is also being considered.

The reaction of chemically bonding rubber and silica via a mercapto-based silane coupling agent is advantageous in improving performance, but this reaction occurs before vulcanization and tends to deteriorate processability. When a modified rubber such as a modified styrene butadiene rubber is used, the processability is further deteriorated. For this reason, polysulfide silane coupling agents that are less likely to react during kneading are mainly used as silane coupling agents. Therefore, it is hoped to provide a silica rubber composition which is excellent in processability even when a mercapto silane coupling agent is used, and has improved fuel economy, rubber strength, abrasion resistance, wet grip performance and processability in a well-balanced manner. It is rare.

JP 2009-126907 A JP 2001-114939 A

The present invention provides a rubber composition for a tire that solves the above-mentioned problems and improves the fuel economy, rubber strength, wear resistance, wet grip performance and processability in a well-balanced manner, and a pneumatic tire using the same. With the goal.

（式中、Ｒ^１は、同一又は異なって、置換基を有してもよい炭素数３〜１５の１価の炭化水素基を表す。ｎは、２〜６の整数を表す。）

（式中、Ｒ^２は、同一又は異なって、置換基を有してもよい炭素数３〜１５の２価の炭化水素基を表す。ｍは、２〜６の整数を表す。） The present invention relates to a tire rubber composition comprising a rubber component, silica, a silane coupling agent having a mercapto group, and a polysulfide compound represented by the following formulas (I) and / or (II).

(In the formula, R ^1, same or different, .n representing a monovalent hydrocarbon group which may having 3 to 15 carbon atoms have a substituent, represents an integer from 2 to 6.)

(Wherein, R ² are the same or different, .m representing a divalent hydrocarbon group which may having 3 to 15 carbon atoms have a substituent, represents an integer from 2 to 6.)

The tire rubber composition is preferably obtained by kneading the polysulfide compound in a step prior to the vulcanizing chemical kneading step.
The rubber composition for a tire is 5 to 150 parts by mass of silica with respect to 100 parts by mass of the rubber component, and 0.5 to 20 parts by mass of a silane coupling agent having the mercapto group with respect to 100 parts by mass of the silica. The compound represented by the formula (I) is preferably contained in an amount of 10 to 250 parts by mass with respect to 100 parts by mass of the 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 component preferably contains a modified styrene butadiene rubber.
As the rubber composition for a tire, the rubber component, the silica, the silane coupling agent having a mercapto group and the polysulfide compound are kneaded, and the kneaded product and the vulcanized chemical obtained in the step 1 are mixed. What is obtained by the manufacturing method including the process 2 of kneading | mixing is preferable.
The present invention also relates to a pneumatic tire produced using the rubber composition.

According to the present invention, since it is a rubber composition for a tire containing a predetermined amount of a rubber component, silica, a silane coupling agent having a mercapto group, and a specific polysulfide compound, low fuel consumption, rubber strength, wear resistance, wet Grip performance and workability can be improved in a well-balanced manner.

The rubber composition for tires of the present invention comprises a rubber component, silica, a silane coupling agent having a mercapto group, and a polysulfide compound represented by the formula (I) and / or (II).

By blending a specific polysulfide compound with a mercapto-based silane coupling agent, which can be expected to have an effect of improving performance such as fuel efficiency, in a compounding containing a rubber component and silica, At the same time as the processability is improved, the effects of improving fuel economy, rubber strength, wear resistance, and wet grip performance are also exhibited, and these performance balances can be improved synergistically.

Furthermore, a normal rubber composition was obtained by a base kneading step of kneading chemicals other than vulcanizing chemicals (vulcanizing agent and vulcanizing accelerator) such as sulfur and sulfenamide vulcanization accelerators, and the step. The kneaded product is manufactured by performing a final kneading step in which kneaded chemicals are added and kneaded in this order, where the polysulfide compound is kneaded in a base kneading step performed before the final kneading step. Since the processability is dramatically improved and the performance such as fuel efficiency is greatly improved, the performance balance can be improved more remarkably.

Examples of rubber components include natural rubber (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), styrene butadiene rubber (SBR), diene rubbers such as butadiene rubber (BR), and silica. Examples thereof include modified diene rubbers containing at least one functional group. These may be used alone or in combination of two or more. Here, examples of the modified diene rubber include diene rubber modified with a modifier having a functional group containing at least one atom of nitrogen, oxygen, and silicon at least one terminal, May have such a functional group. Examples of the functional group that interacts with silica include amino group, amide group, alkoxysilyl group, isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, carboxyl group, hydroxyl group, and nitrile group. And pyridyl group.

From the viewpoint that the effects of the present invention can be obtained satisfactorily, it is preferable to use SBR as the rubber component, and it is more preferable to use SBR and BR in combination. In this case, a tire having a good performance balance can be obtained.

SBR and BR are not particularly limited, and those common in the tire industry can be used. For example, as SBR, emulsion polymerization SBR (S-SBR), solution polymerization SBR (E-SBR) or the like can be used, and as BR, high cis BR, high trans BR or the like can be used. Further, as SBR, modified SBR can be suitably used from the viewpoint that processability can be improved and the performance balance can be improved.

As the modified SBR, those obtained by treating SBR generally used in the tire industry with a modifying agent can be used. Examples of the modifier include 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylethyldimethoxysilane, 3-aminopropyltrimethoxysilane, and 3- (2-aminoethylamino) propyl. Examples include trimethoxysilane, tin tetrachloride, butyltin trichloride, N-methylpyrrolidone and the like. These may be used alone or in combination of two or more. Among these, N-methylpyrrolidone-modified SBR can be preferably used from the viewpoint that the effects of the present invention can be obtained satisfactorily.

As a modification method using the above modifier, conventionally known methods such as methods described in JP-B-6-53768 and JP-B-6-57767 can be used.

（式中、Ｒは、炭素数が１〜１０の炭化水素基を表す。） In addition, as the modified SBR, those in which the main chain is modified with a compound represented by the following formula (main chain modifying agent) and at least one terminal is modified with the above modifying agent as necessary can be suitably used. .

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

In the above formula, the carbon number of R is preferably from 1 to 8, more preferably from 1 to 6, and even more preferably from 1 to 3, from the viewpoint that the effect of improving fuel economy and wet grip performance is high.

Examples of the hydrocarbon group represented by R include a monovalent aliphatic hydrocarbon group such as an alkyl group, and a monovalent aromatic hydrocarbon group such as an aryl group. R is preferably an alkyl group, more preferably a methyl group or a tert-butyl group, from the viewpoint that the effect of improving fuel economy and wet grip performance is high.

（式中のＲは、前記と同様である。） Among the main chain modifiers, compounds represented by the following formula are preferable.

(R in the formula is the same as described above.)

Specific examples of the main chain modifier 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 SBR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 25% by mass or more, and further preferably 60% by mass or more. If it is less than 10% by mass, sufficient fuel economy may not be obtained. The SBR content may be 100% by mass, but is preferably 90% by mass or less, and more preferably 80% by mass or less from the viewpoint that good workability and wear resistance can be obtained.

The content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more. If it is less than 5% by mass, sufficient fuel economy, wear resistance and crack resistance may not be obtained. Further, the BR content is preferably 60% by mass or less, more preferably 40% by mass or less. If it exceeds 60% by mass, sufficient mechanical strength and wet grip performance may not be obtained.

Examples of the silica include dry method silica (anhydrous silica), wet method silica (hydrous silica), and the like. Of these, wet-process silica is preferred because it has many silanol groups. Silica may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 30 m ² / g or more, more preferably 100 m ² / g or more, and preferably 300 m ² / g or less, more preferably 200 m ² / g. It is as follows. If it is in the said range, reinforcement property, abrasion resistance, low fuel consumption, and wet grip performance will be obtained with good balance.
The _N 2 SA of silica is a value measured by the BET method in accordance with ASTM D3037-81.

The content of silica is preferably 5 parts by mass or more, more preferably 20 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 5 parts by mass, sufficient reinforcing properties and low fuel consumption may not be obtained. Further, the content of silica 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, the Mooney viscosity tends to be high, and the workability tends to deteriorate.

（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 (-SH), a compound represented by the following formula (1) and / or a bond unit A represented by the following formula (2) and a bond represented by the following formula (3): A compound containing unit B can be preferably 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, wet grip performance and 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, methoxy group, ethoxy group, n-propoxy group, 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) of 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, such as _{-O- (C 2 H 4 -O)} 7 -C 13 H 27 and the like. 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, And dodecynyl group. 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, octadecylene group and the like. 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 the branched or unbranched alkynylene group having 2 to 30 carbon atoms of R ²⁰² include ethynylene group, propynylene group, butynylene group, pentynylene group, hexynylene group, heptynylene group, octynylene group, noninylene 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 content of the silane coupling agent having a mercapto group is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and further preferably 2 parts by mass or more with respect to 100 parts by mass of silica. If it is less than 0.5 parts by mass, there is a possibility that an improvement effect such as low fuel consumption cannot be obtained sufficiently. Moreover, this content becomes like this. Preferably it is 20 mass parts or less, More preferably, it is 12 mass parts or less, More preferably, it is 9 mass parts or less. If it exceeds 20 parts by mass, the rubber strength and wear resistance tend to decrease.

（式中、Ｒ^１は、同一又は異なって、置換基を有してもよい炭素数３〜１５の１価の炭化水素基を表す。ｎは、２〜６の整数を表す。）

（式中、Ｒ^２は、同一又は異なって、置換基を有してもよい炭素数３〜１５の２価の炭化水素基を表す。ｍは、２〜６の整数を表す。） In the present invention, a polysulfide compound represented by the following formula (I) and / or (II) is used.

(In the formula, R ^1, same or different, .n representing a monovalent hydrocarbon group which may having 3 to 15 carbon atoms have a substituent, represents an integer from 2 to 6.)

(Wherein, R ² are the same or different, .m representing a divalent hydrocarbon group which may having 3 to 15 carbon atoms have a substituent, represents an integer from 2 to 6.)

In the above formula (I), R ¹ is a monovalent hydrocarbon group having 3 to 15 carbon atoms which may have a substituent, and the carbon number is preferably 5 to 12, more preferably 6 -10. The monovalent hydrocarbon group for R ¹ may be linear, branched or cyclic, and any of saturated and unsaturated hydrocarbon groups (aliphatic, alicyclic, aromatic hydrocarbon groups, etc.) But you can. Of these, an aromatic hydrocarbon group which may have a substituent is preferable.

Examples of R ¹ include an alkyl group having 3 to 15 carbon atoms, a substituted alkyl group, a cycloalkyl group, a substituted cycloalkyl group, an aralkyl group, and a substituted aralkyl group. Among these, an aralkyl group and a substituted aralkyl group are exemplified. preferable. Here, examples of the alkyl group include a butyl group and an octyl group; examples of the cycloalkyl group include a cyclohexyl group; examples of the aralkyl group include a benzyl group and a phenethyl group; and examples of the substituent include an oxo group (═O). And polar groups such as hydroxy group, carboxyl group, carbonyl group, amino group, acetyl group, amide group and imide group.

In the above formula (I), n is an integer of 2 to 6, preferably 2 to 3, and more preferably 2.

In the formula (II), R ² is a divalent hydrocarbon group having 3 to 15 carbon atoms which may have a substituent, and the carbon number is preferably 3 to 10, more preferably 4 ~ 8. The divalent hydrocarbon group for R ² may be linear, branched, or cyclic, and any of saturated and unsaturated hydrocarbon groups (aliphatic, alicyclic, aromatic hydrocarbon groups, etc.) But you can. Especially, the aliphatic hydrocarbon group which may have a substituent is preferable, and a linear aliphatic hydrocarbon group is more preferable.

Examples of R ² include an alkylene group having 3 to 15 carbon atoms and a substituted alkylene group. Here, examples of the alkylene group include a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, and a nonylene group, and examples of the substituent include those similar to the substituent for R ¹ .

In the above formula (I), m is an integer of 2 to 6, preferably 2 to 3, and more preferably 2.

Specific examples of the polysulfide compound represented by the above formulas (I) and (II) include N, N′-di (γ-butyrolactam) disulfide, N, N′-di (5-methyl-γ-butyrolactam) disulfide, N, N′-di (5-ethyl-γ-butyrolactam) disulfide, N, N′-di (5-isopropyl-γ-butyrolactam) disulfide, N, N′-di (5-methoxy-γ-butyrolactam) disulfide N, N′-di (5-ethoxy-γ-butyrolactam) disulfide, N, N′-di (5-chloro-γ-butyrolactam) disulfide, N, N′-di (5-nitro-γ-butyrolactam) Disulfide, N, N'-di (5-amino-γ-butyrolactam) disulfide, N, N'-di (δ-valerolactam) disulfide, N, N'-di (δ- Caprolactam) disulfide, N, N'-di (ε-caprolactam) disulfide, N, N'-di (3-methyl-δ-caprolactam) disulfide, N, N'-di (3-ethyl-ε-caprolactam) disulfide N, N′-di (3-isopropyl-ε-caprolactam) disulfide, N, N′-di (δ-methoxy-ε-caprolactam) disulfide, N, N′-di (3-ethoxy-ε-caprolactam) Disulfide, N, N′-di (3-chloro-ε-caprolactam) disulfide, N, N′-di (δ-nitro-ε-caprolactam) disulfide, N, N′-di (3-amino-ε-caprolactam ) Disulfide, N, N′-di (ω-heptalactam) disulfide, N, N′-di (ω-octalactam) disulfide, dithiodica Rorakutamu, morpholine disulfide, N-benzyl-N - [(dibenzylamino) disulfanyl] phenylmethanamine (N, N'- dithiobis (dibenzyl amine)), and the like. These polysulfide compounds may be used alone or in combination of two or more.

The content of the polysulfide compound is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more with respect to 100 parts by mass of the silica. If it is less than 0.5 parts by mass, good workability cannot be ensured, and the performance balance may not be sufficiently improved. Moreover, this content becomes like this. Preferably it is 20 mass parts or less, More preferably, it is 13 mass parts or less, More preferably, it is 10 mass parts or less. If it exceeds 20 parts by mass, the rubber strength tends to be lowered, and the cost is undesirable.

Further, the content of the polysulfide compound is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, with respect to 100 parts by mass of the silane coupling agent having a mercapto group. Moreover, this content becomes like this. Preferably it is 250 mass parts or less, More preferably, it is 150 mass parts or less. When it is less than the lower limit, when it exceeds the upper limit, there is a tendency similar to the above.

The rubber composition of the present invention usually contains a vulcanized chemical that is added and kneaded in the final kneading step. Examples of vulcanizing chemicals include vulcanizing agents and vulcanization accelerators.

Examples of the vulcanizing agent include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur.

When the rubber composition of the present invention contains sulfur, the content thereof is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 0.5 mass part, there is little bridge | crosslinking and there exists a possibility that various rubber physical properties may deteriorate. Moreover, this content becomes like this. Preferably it is 4.5 mass parts or less, More preferably, it is 2.3 mass parts or less. If it exceeds 4.5 parts by mass, the rubber strength tends to decrease.

Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, and xanthate vulcanization accelerators. Among them, sulfenamide-based and guanidine-based vulcanization accelerators are preferable from the viewpoint of excellent vulcanization characteristics.

Examples of the sulfenamide vulcanization accelerator include CBS (N-cyclohexyl-2-benzothiazylsulfenamide), TBBS (Nt-butyl-2-benzothiazylsulfenamide), N, N-dicyclohexyl. -2-benzothiazylsulfenamide and the like, and examples of the guanidine vulcanization accelerator include diphenylguanidine (DPG). Of these, TBBS is preferable, and it is more preferable to use TBBS and DPG in combination.

When the rubber composition of the present invention contains a vulcanization accelerator, the content thereof is preferably 0.7 parts by mass or more, more preferably 1.2 parts by mass or more with respect to 100 parts by mass of the rubber component. . If it is less than 0.7 parts by mass, the vulcanization start time tends to be delayed. Moreover, this content becomes like this. Preferably it is 5.0 mass parts or less, More preferably, it is 4.0 mass parts or less. If it exceeds 5.0 parts by mass, the vulcanization speed is high, and there is a possibility that scorch occurs during processing.

The rubber composition of the present invention includes various materials commonly used in the tire industry such as carbon black, oil, stearic acid, zinc oxide, anti-aging agent, plasticizer, lubricant, and wax in addition to the above components. You may mix | blend suitably.

As a method for producing the rubber composition of the present invention, known methods can be used. For example, the above components are kneaded using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanized (crosslinked). It can be manufactured by a method or the like.

Among them, it is preferable to prepare the polysulfide compound by kneading in the step before the vulcanizing chemical kneading step. For example, the rubber component, silica, a silane coupling agent having a mercapto group, and the polysulfide compound are kneaded. It can be suitably produced by a production method comprising Step 1 and Step 2 of kneading the kneaded product and vulcanized chemical obtained in Step 1. In this case, the workability is dramatically improved, and the performance such as fuel efficiency is remarkably improved.

(Process 1 (base kneading process 1))
In step 1, the rubber component, silica, a silane coupling agent having a mercapto group, and a polysulfide compound are kneaded. The kneading method is not particularly limited, and a kneader used in a general rubber industry such as a Banbury mixer or an open roll can be used. The base kneading step may be performed once, but the number of kneading is not particularly limited, such as dividing the additive or increasing the kneading.

The kneading temperature in step 1 is preferably 50 ° C. or higher, more preferably 80 ° C. or higher, and preferably 200 ° C. or lower, more preferably 190 ° C. or lower. The kneading time is not particularly limited, but is usually 30 seconds to 30 minutes, preferably 1 to 30 minutes. If it is less than the lower limit, the reaction between the silane coupling agent and silica does not proceed sufficiently, silica cannot be dispersed well, and the effect of improving rubber properties tends to be small. On the other hand, when the upper limit is exceeded, the Mooney viscosity increases and the processability tends to deteriorate.

The rubber component kneaded in step 1 is preferably 60% by mass or more, more preferably 80% by mass or more, and still more preferably 100% when the total amount is 100% by mass from the viewpoint that the effects of the present invention can be obtained satisfactorily. % By mass.

(Process 2 (finishing process))
After performing Step 1, the kneaded product obtained in Step 1 is cooled, and further vulcanized chemicals such as a vulcanizing agent and a vulcanization accelerator are added and kneaded to obtain an unvulcanized rubber composition.

The kneading temperature in step 2 is usually 100 ° C. or lower, and preferably room temperature (20 ° C.) to 80 ° C. If the temperature exceeds 100 ° C., rubber scorch may occur. The kneading time in step 2 is not particularly limited, but is usually 30 seconds or longer, preferably 1 to 30 minutes.

(Process 3 (vulcanization process))
By vulcanizing the unvulcanized rubber composition obtained in step 2 by a known method, the rubber composition of the present invention is obtained. The vulcanization temperature in step 3 is preferably 120 ° C. or higher, more preferably 140 ° C. or higher, and preferably 200 ° C. or lower, more preferably 180 ° C. or lower, from the viewpoint that the effects of the present invention can be obtained satisfactorily. It is.

The timing of kneading the appropriately added compounding materials (carbon black, zinc oxide, plasticizer, lubricant, wax, oil, stearic acid, zinc oxide, anti-aging agent, etc.) is not particularly limited. It is preferable.

The rubber composition of the present invention can be used for each member of a tire, and in particular, can be suitably used for a tread and a sidewall.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition. That is, a rubber composition containing various additives as necessary is extruded in accordance with the shape of each member of the tire at an unvulcanized stage and molded by a normal method on a tire molding machine. After forming an unvulcanized tire by heating, it can be produced by heating and pressing in a vulcanizer.

The pneumatic tire of the present invention can be suitably used as a tire for passenger cars.

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

Hereinafter, various chemicals used at the time of synthesis and polymerization will be described together. In addition, the chemical | medical agent refine | purified according to the usual method as needed.
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-dimethylamino) propyltrimethoxysilane 2,6-tert- Butyl-p-cresol: NOCRACK 200 manufactured by Ouchi Shinsei Chemical Co., Ltd.

<Analysis of main chain terminal modified S-SBR>
Analysis of the modified S-SBR obtained as follows was performed by the following method.
(Measurement of weight average molecular weight Mw)
The weight average molecular weight Mw of the modified S-SBR is a gel permeation chromatograph (GPC) (GPC-8000 series manufactured by Tosoh Corp., detector: differential refractometer, column: TSKGEL SUPERMALTIPORE HZ-M manufactured by Tosoh Corp. ) Based on standard polystyrene conversion.

(Structural identification of modified S-SBR)
The structural identification of the modified S-SBR was performed using a JNM-ECA series device manufactured by JEOL Ltd. From the measurement results, the contents of 1,3-butadiene, p-methoxystyrene and styrene in the copolymer were calculated.

<Production Example Synthesis of Main Chain Terminal Modified S-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. After adding 1 g of 2,6-tert-butyl-p-cresol to the reaction solution, main chain terminal modified S-SBR was obtained by reprecipitation purification. The obtained main chain terminal modified S-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.

シランカップリング剤Ｃ：Ｍｏｍｅｎｔｉｖｅ社製のＮＸＴ−Ｚ４５（結合単位Ａと結合単位Ｂとの共重合体、上記式（２）〜（３）において、結合単位Ａ：５５モル％、結合単位Ｂ：４５モル％）
ポリスルフィド化合物１：ジチオジカプロラクタム（Ｒｈｅｉｎ−Ｃｈｅｍｉｅ社製のＲｈｅｎｏｃｕｒｅ Ｓ、８０％マスターバッチ品、下記式で示される化合物）
ポリスルフィド化合物２：Ｎ−ｂｅｎｚｙｌ−Ｎ−［（ｄｉｂｅｎｚｙｌａｍｉｎｏ）ｄｉｓｕｌｆａｎｙｌ］ｐｈｅｎｙｌｍｅｔｈａｎａｍｉｎｅ（Ａｌｄｒｉｃｈ社製、下記式で示される化合物）
オイル：（株）ジャパンエナジー製のプロセスＸ−１４０
ステアリン酸：日油（株）製のステアリン酸「椿」
酸化亜鉛：三井金属工業（株）製の亜鉛華１号
老化防止剤：大内新興化学工業（株）製のノクラック６Ｃ（Ｎ−（１，３−ジメチルブチ
ル）−Ｎ’−フェニル−ｐ−フェニレンジアミン）
硫黄：鶴見化学工業（株）の粉末硫黄
加硫促進剤ＮＳ：大内新興化学工業（株）製のノクセラーＮＳ（Ｎ−ｔｅｒｔ−ブチル−２−ベンゾチアゾリルスルフェンアミド）
加硫促進剤ＤＰＧ：大内新興化学工業（株）製のノクセラーＤ（Ｎ，Ｎ’−ジフェニルグアニジン） Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
BR: BR150B (non-modified) manufactured by Ube Industries, Ltd.
Terminal modified S-SBR: Nipol NS116R manufactured by Nippon Zeon Co., Ltd. (S-SBR modified at one end with N-methylpyrrolidone)
Main chain terminal modified S-SBR: Main chain terminal modified S-SBR prepared in the above production example
Silica: Ultrasil VN3 (N ₂ SA: 175 m ² / g) manufactured by EVONIK-DEGUSSA
Silane coupling agent A: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by EVONIK-DEGUSSA
Silane coupling agent B: Si363 manufactured by EVONIK-DEGUSSA

Silane coupling agent C: NXT-Z45 manufactured by Momentive (copolymer of bonding unit A and bonding unit B, in the above formulas (2) to (3), bonding unit A: 55 mol%, bonding unit B: 45 mol%)
Polysulfide compound 1: dithiodicaprolactam (Rhenocure S manufactured by Rhein-Chemie, 80% master batch, compound represented by the following formula)
Polysulfide compound 2: N-benzyl-N-[(dibenzylamino) disulfanyl] phenylmethanamine (a compound represented by the following formula, manufactured by Aldrich)
Oil: Process X-140 manufactured by Japan Energy Co., Ltd.
Stearic acid: Stearic acid “椿” manufactured by NOF Corporation
Zinc oxide: zinc oxide No. 1 anti-aging agent manufactured by Mitsui Kinzoku Kogyo Co., Ltd .: NOCRACK 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-p) manufactured by Ouchi Shinsei Chemical Co., Ltd. Phenylenediamine)
Sulfur: powder sulfur vulcanization accelerator NS of Tsurumi Chemical Co., Ltd. NS: Noxeller 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>
Using a 1.7 L Banbury mixer, the materials described in the items of base kneading in Tables 1 and 2 were kneaded for 3 minutes at 150 ° C. to obtain a kneaded product (base kneading step). Next, the materials described in the items of finish kneading in Tables 1 and 2 are added to the kneaded material obtained, and kneaded for 3 minutes under the condition of 80 ° C. using an open roll, and an unvulcanized rubber composition A product was obtained (finish kneading step).
The obtained unvulcanized rubber composition was press vulcanized at 170 ° C. for 15 minutes to obtain a vulcanized rubber composition.

Further, the obtained unvulcanized rubber composition was molded into a tread shape and bonded together with other tire members on a tire molding machine to form an unvulcanized tire, and then press vulcanized at 170 ° C. for 10 minutes. A test tire (size: 195 / 65R15) was produced.

The following evaluation was performed about the obtained unvulcanized rubber composition, the vulcanized rubber composition, and the test tire. The results are shown in Tables 1-2.

(Measurement of Mooney viscosity)
About the obtained unvulcanized rubber composition, the Mooney viscosity based on JISK6300 was measured at 130 degreeC. The Mooney viscosity (ML _{1 + 4} ) of Comparative Example 1 or 7 was set to 100, and indexed by the following formula (Mooney viscosity index). The larger the index, the lower the Mooney viscosity and the better the processability.
(Mooney viscosity index) = (ML _{1 + 4} of Comparative Example 1 or 7) / (ML _{1 + 4 of} each formulation) × 100

(Rolling resistance)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the loss tangent of each compound (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 ( tan δ) was measured, and the loss tangent tan δ of Comparative Example 1 or 7 was taken as 100, and the result was expressed as an index (rolling resistance index) by the following formula. The larger the index, the better the rolling resistance characteristics.
(Rolling resistance index) = (tan δ of Comparative Example 1 or 7) / (tan δ of each formulation) × 100

(Tensile test)
Using a tensile testing machine (Toyo Seiki Co., Ltd.), a tensile test was performed with a dumbbell-shaped test piece (vulcanized rubber composition) in accordance with JIS K 6251, tensile stress at shear (TSb), elongation at break The energy multiplied by (Eb) and divided by 2 was defined as the breaking energy. The fracture energy of Comparative Example 1 or 7 was taken as 100, and the index was expressed by the following formula (tensile test index). The greater the index, the better the strength.
(Tensile test index) = (Fracture energy of each formulation) / (Fracture energy of Comparative Example 1 or 7) × 100

(Abrasion test)
About the obtained vulcanized rubber composition, the amount of lamborn wear was measured under the conditions of a temperature of 20 ° C., a slip rate of 20% and a test time of 2 minutes using a lamborn wear tester. Was calculated. The volume loss amount of Comparative Example 1 or 7 was set to 100, and the index was displayed by the following formula (Lambourn wear index). The higher the index, the better the wear resistance.
(Lambourn wear index) = (volume loss amount of Comparative Example 1 or 7) / (volume loss amount of each formulation) × 100

(Wet grip performance)
On a test course with wet and wet surfaces, test tires are mounted on a 2000 cc domestic FR vehicle, run at a speed of 70 km / h, run from braking the tire to stopping The distance (braking distance) was measured. The braking distance of Comparative Example 1 or 7 was set to 100, and an index was displayed by the following formula (wet grip performance index). It shows that it is excellent in wet grip performance, so that an index | exponent is large.
(Wet grip performance index) = (Brake distance of Comparative Example 1 or 7) / (Brake distance of each formulation) × 100

In Table 1, in Comparative Examples 1 and 3 in which Si69 was used as the silane coupling agent and the polysulfide compound was not blended, and the mercapto silane coupling agent was substituted, the processability was lowered. On the other hand, in the examples in which the mercapto-based silane coupling agent and the polysulfide compound are blended, the improvement effect of the workability is exhibited and the fuel efficiency, tensile strength, wear resistance, and wet grip performance are synergistically improved. It became clear that it could be improved. Table 2 also showed the same effect.

Claims (5)

Step 1 for kneading a rubber component, silica, a silane coupling agent having a mercapto group, and a polysulfide compound represented by the following formula (I) and / or (II) , and the kneaded product and vulcanization obtained in Step 1 A tire rubber composition obtained by a production method comprising a step 2 of kneading a chemical .

(In the formula, R ^1, same or different, .n representing a monovalent hydrocarbon group which may having 3 to 15 carbon atoms have a substituent, represents an integer from 2 to 6.)

(Wherein, R ² are the same or different, .m representing a divalent hydrocarbon group which may having 3 to 15 carbon atoms have a substituent, represents an integer from 2 to 6.) 5 to 150 parts by mass of silica with respect to 100 parts by mass of the rubber component, 0.5 to 20 parts by mass of silane coupling agent having the mercapto group with respect to 100 parts by mass of silica, and a silane cup having the mercapto group The rubber composition for a tire according to claim 1, comprising 10 to 250 parts by mass of the compound represented by the formula (I) with respect to 100 parts by mass of the ring agent. 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). a compound is claimed in claim 1 or 2 tire rubber composition according comprising.

(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 tire rubber composition according to any one of claims 1 to 3 , wherein the rubber component includes a modified styrene butadiene rubber. The pneumatic tire produced using the rubber composition in any one of Claims 1-4 .