JP6631059B2 - Pneumatic tire - Google Patents

Description

The present invention relates to a pneumatic tire manufactured using a predetermined rubber composition.

In recent years, due to increasing interest in environmental issues, there has been an increasing demand for low fuel consumption for automobiles, and rubber compositions used for automobile tires are also required to have excellent fuel economy. . As a rubber composition for an automobile tire, a rubber composition containing a conjugated diene-based polymer such as polybutadiene or a butadiene-styrene copolymer and a filler such as carbon black or silica is used.

As a method for improving fuel economy, for example, Patent Document 1 proposes a method using a diene rubber (modified rubber) modified with an organosilicon compound containing an amino group and an alkoxy group. Although the fuel efficiency is improved by such a conventional technology, from the viewpoint of economy and safety, wear resistance, fracture characteristics (rubber fracture strength), grip performance (particularly wet grip performance) and workability are improved. Ensuring sufficient security is also an important issue. In contrast to the above problems, in the prior art, there is a problem that wear resistance, wet grip performance and workability, which are contrary to fuel efficiency, are not sufficient, and also cause rubber chipping, rubber breaking strength, There is room for improvement in wear resistance, wet grip performance and workability.

JP-A-2000-344955

An object of the present invention is to solve the above-mentioned problems and to provide a pneumatic tire with improved rubber breaking strength, abrasion resistance and wet grip performance with improved productivity while maintaining or improving good fuel economy. I do.

The present inventors have improved rubber breaking strength and abrasion resistance while maintaining or improving good wet grip performance and low fuel consumption by using a specific copolymer having a high hydrogenation rate as a rubber component. I found what I can do. However, when the above copolymer is blended, a new problem arises that the processability of the rubber composition is significantly reduced. As a result of earnestly examining this newly created problem, by blending silica and a specific compound with the above copolymer, good rubber breaking strength and abrasion resistance obtained by blending the above copolymer are obtained. The processability can be greatly improved while suppressing a large decrease in the performance, and the wet grip performance can also be improved. As a result, by combining the specified three components together, good fuel economy can be maintained or improved. In addition, they have found that the rubber breaking strength, abrasion resistance, wet grip performance, and workability can be improved, and the present invention has been completed.

The present invention is a pneumatic tire manufactured using a rubber composition, wherein the rubber composition is obtained by copolymerizing an aromatic vinyl compound and a conjugated diene compound, and has a hydrogenation rate of a conjugated diene portion. It contains a hydrogenated copolymer of 75 mol% or more, silica and a compound represented by the formula (I), and the content of the hydrogenated copolymer in 100% by mass of a rubber component is 75% by mass or more. And the content of the silica is 5 to 150 parts by mass with respect to 100 parts by mass of the rubber component, and the content of the compound represented by the formula (I) is 0.5 to 20 parts by mass with respect to 100 parts by mass of the silica. Related to a pneumatic tire.

In the formula (I), R ³⁰¹ represents a hydrogen atom, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched carbon atom having 6 to 30 carbon atoms. Represents 30 aryl groups or hydroxyl groups. R ³⁰² and R ³⁰³ are the same or different and each are a hydrogen atom, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched carbon number. 2 to 30 alkynyl groups, branched or unbranched aryl groups having 6 to 30 carbon atoms, or groups represented by the following formula (II): the alkyl group, the alkenyl group, the alkynyl group, and the aryl group May be substituted with a hydroxyl group or a carboxyl group. R ³⁰¹ and R ³⁰² , R ³⁰¹ and R ³⁰³ , or R ³⁰² and R ³⁰³ may form a ring structure. d ₁ is an integer of 0-8.

In the formula (II), R ³⁰⁴ represents a branched or unbranched alkylene group having 1 to 30 carbon atoms. R ³⁰⁵ is a hydrogen atom, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched aryl group having 6 to 30 carbon atoms, or Represents a hydroxyl group. d ₂ is an integer of 0.

The hydrogenated copolymer preferably has a weight average molecular weight of 200,000 to 2,000,000.

The hydrogenated copolymer preferably has a hydrogenation rate of 90 mol% or more.

The hydrogenated copolymer is preferably a hydrogenated styrene-butadiene copolymer.

Preferably, the hydrogenated styrene-butadiene copolymer is a hydrogenated modified styrene-butadiene copolymer.

The hydrogenated styrene-butadiene copolymer preferably has a styrene content of 5 to 40% by mass.

The content of the hydrogenated styrene-butadiene copolymer in 100% by mass of the rubber component is preferably 90 to 100% by mass.

It is preferable that the rubber composition further contains carbon black, and the content of carbon black is 1 part by mass or more based on 100 parts by mass of the rubber component.

According to the present invention, a specific hydrogenated copolymer having a hydrogenation rate of 75 mol% or more is contained in an amount of 75 mass% or more in 100 mass% of a rubber component, and further contains silica and the above-mentioned formula (I). Pneumatic tire produced by using a rubber composition containing a specific amount of a compound having the above-mentioned properties, while maintaining or improving good fuel economy and having good rubber breaking strength, abrasion resistance and wet grip performance. Further, since the processability of the rubber composition is good, the pneumatic tire can be manufactured with high productivity.

The pneumatic tire of the present invention provides a conjugated diene of a copolymer obtained by copolymerizing an aromatic vinyl compound and a conjugated diene compound (hereinafter also referred to as a copolymer of an aromatic vinyl compound and a conjugated diene compound). Parts of the hydrogenated copolymer having a hydrogenation rate of 75 mol% or more is contained in the rubber component in an amount of 75 mass% or more per 100 mass% of the rubber component. It is produced using a rubber composition further containing silica and 0.5 to 20 parts by mass of the compound represented by the above formula (I) based on 100 parts by mass of silica.

The rubber composition of the present invention is obtained by adding a hydrogenated copolymer having a conjugated diene portion of a copolymer of an aromatic vinyl compound and a conjugated diene compound to a hydrogenation rate of at least 75 mol% to a rubber component of 100 mass%. % By mass. Further, the rubber composition of the present invention is represented by the formula (I) in an amount of 5 to 150 parts by mass with respect to 100 parts by mass of the rubber component and 0.5 to 20 parts by mass with respect to 100 parts by mass of the silica. And a compound. By using such a rubber composition, it is possible to improve or improve rubber fracture strength, abrasion resistance, wet grip performance and processability (particularly, rubber fracture strength) while maintaining or improving good fuel economy. This effect can be obtained only when a specific hydrogenated copolymer having a hydrogenation rate of 75 mol% or more, silica, and a compound represented by the above formula (I) are combined in specific amounts and blended, and this is the first synergistic effect. Effect.

The rubber composition of the present invention is characterized in that it contains, as a rubber component, a hydrogenated copolymer in which a conjugated diene portion of a copolymer of an aromatic vinyl compound and a conjugated diene compound is hydrogenated. Since ordinary rubber has a large number of double bonds serving as reaction points for cross-linking, the cross-linking density is considered to be high, and the cross-linking density is considered to be a starting point of destruction due to stress concentration. In the present invention, the number of reaction sites for crosslinking is reduced by reducing the number of double bonds by hydrogenation. This is expected to reduce cross-linkage density and alleviate stress concentration, thereby improving wear resistance and the like.

Examples of the aromatic vinyl compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, and 2,4,6-trimethylstyrene. These may be used alone or in combination of two or more. Among them, practical viewpoints such as availability of monomers and the reason that the effects of the present invention can be more preferably obtained. To styrene are particularly preferred.

Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene. These may be used alone or in combination of two or more. Among them, practical viewpoints such as availability of monomers and the reason that the effects of the present invention can be more preferably obtained. To 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred.

As the copolymer of the aromatic vinyl compound and the conjugated diene compound, a copolymer of styrene and 1,3-butadiene (styrene-butadiene copolymer) is preferable. Therefore, the hydrogenated copolymer is preferably a hydrogenated styrene butadiene copolymer. Further, the hydrogenated styrene-butadiene copolymer is preferably a hydrogenated modified styrene-butadiene copolymer modified by a method described below.

The styrene-butadiene copolymer is not particularly limited in the order of copolymerization as long as it copolymerizes styrene and 1,3-butadiene, and may be a random copolymer or a block copolymer, but a random copolymer is preferred. . The same applies to a copolymer of an aromatic vinyl compound and a conjugated diene compound other than the styrene-butadiene copolymer.

The hydrogenation rate of the hydrogenated copolymer (the ratio of the hydrogenated copolymer to the conjugated diene portion of the copolymer of the aromatic vinyl compound and the conjugated diene compound) is at least 75 mol%, preferably at least 80 mol%, It is more preferably at least 90 mol%, further preferably at least 93 mol%. If the hydrogenation rate is less than 75 mol%, it is difficult to improve the rubber breaking strength and the wear resistance. Further, the hydrogenation rate of the hydrogenated copolymer is preferably at most 99 mol%, more preferably at most 98 mol%. If the hydrogenation rate exceeds 99 mol%, the rubber composition may be hardened.
In addition, the hydrogenation rate can be calculated from the spectrum reduction rate of the unsaturated bond part of the spectrum obtained by measuring H ¹ -NMR.

The weight average molecular weight (Mw) of the hydrogenated copolymer is preferably 200,000 or more, more preferably 400,000 or more. If Mw is less than 200,000, good rubber breaking strength and abrasion resistance may not be obtained. Further, the Mw of the hydrogenated copolymer is preferably 2,000,000 or less, more preferably 1,000,000 or less, and further preferably 700,000 or less. When Mw exceeds 2,000,000, workability tends to decrease.

In addition, in this specification, weight average molecular weight (Mw) and number average molecular weight (Mn) are gel permeation chromatograph (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: It can be determined in terms of standard polystyrene based on the measured value by TSKEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation.

The glass transition temperature (Tg) of the hydrogenated copolymer is preferably −45 ° C. or higher, more preferably −35 ° C. or higher, further preferably −30 ° C. or higher, still more preferably −25 ° C. or higher, and −24.5. C. or higher is particularly preferable, and -24 C or higher is most preferable. When Tg is less than -45 ° C, sufficient wet grip performance may not be obtained. The Tg of the hydrogenated copolymer is preferably lower than -10C, more preferably lower than -12.5C, further preferably lower than -15C, and particularly preferably lower than -20C. If the Tg is -10 ° C or higher, sufficient low-temperature characteristics may not be obtained.
The glass transition temperature (Tg) of the hydrogenated copolymer is measured by the method described in Examples described later.

When the hydrogenated copolymer is a hydrogenated styrene-butadiene copolymer, the styrene content of the hydrogenated styrene-butadiene copolymer is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 15% by mass. %, Particularly preferably at least 20% by mass, most preferably at least 25% by mass. If the styrene content is less than 5% by mass, sufficient grip performance may not be obtained. The styrene content of the hydrogenated styrene-butadiene copolymer is preferably 40% by mass or less, more preferably 35% by mass or less. If the styrene content exceeds 40% by mass, sufficient rubber breaking strength and abrasion resistance cannot be obtained, and fuel economy may be deteriorated. When the styrene content is within the above range, the effects of the present invention can be more suitably obtained.
The styrene content is measured by a method described in Examples described later.

The hydrogenated copolymer can be synthesized, for example, by subjecting a polymer obtained by polymerizing an aromatic vinyl compound and a conjugated diene compound to a hydrogenation treatment, and specifically, by the following method.

<Method for producing copolymer>
(Polymerization method)
The polymerization method of the copolymer of the aromatic vinyl compound and the conjugated diene compound is not particularly limited, and any of a solution polymerization method, a gas phase polymerization method, and a bulk polymerization method can be used, but the solution polymerization method is particularly preferable. Further, the polymerization system may be any of a batch system and a continuous system.

When the solution polymerization method is used, the monomer concentration in the solvent (the total of styrene and 1,3-butadiene in the case of a styrene-butadiene copolymer) is preferably 5% by mass or more, more preferably 10% by mass or more. . When the monomer concentration in the solution is less than 5% by mass, the amount of the obtained copolymer is small, and the cost tends to be high. Further, the monomer concentration in the solvent is preferably 50% by mass or less, more preferably 30% by mass or less. When the monomer concentration in the solvent exceeds 50% by mass, the solution viscosity becomes too high, stirring becomes difficult, and the polymerization tends to be difficult.

(Polymerization initiator in anionic polymerization)
When performing anionic polymerization, the polymerization initiator is not particularly limited, but an organic lithium compound is preferably used. As the organic lithium compound, those having an alkyl group having 2 to 20 carbon atoms are preferable. For example, ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, tert-butyl lithium Reaction products of octyl lithium, n-decyl lithium, phenyl lithium, 2-naphthyl lithium, 2-butyl-phenyl lithium, 4-phenyl-butyl lithium, cyclohexyl lithium, cyclopentyl lithium, diisopropenyl benzene and butyl lithium, etc. Among these, n-butyllithium or sec-butyllithium is preferred from the viewpoint of availability, safety and the like.

The polymerization reaction may be carried out in the presence of a compound (R) obtained by mixing at least one of the above-mentioned organolithium compounds and a compound (B1) having a functional group that interacts with silica. By performing the polymerization in the presence of the compound (R), a functional group having an interaction with silica can be introduced to the polymerization initiation terminal of the copolymer. As a result, a copolymer having a modified starting end is obtained. Note that in this specification, “interaction” means that a covalent bond is formed between molecules or an intermolecular force weaker than a covalent bond (for example, an ion-dipole interaction, a dipole-dipole interaction, It means to form an electromagnetic force acting between molecules such as hydrogen bond and van der Waals force. The “functional group that interacts with silica” refers to a group having at least one atom that interacts with silica, such as a nitrogen atom, a sulfur atom, a phosphorus atom, and an oxygen atom.

The compound (R) is preferably a reaction product of an organolithium compound and a nitrogen-containing compound such as a secondary amine compound. Specific examples of the nitrogen-containing compound include, for example, dimethylamine, diethylamine, dipropylamine, dibutylamine, dodecamethyleneimine, N, N′-dimethyl-N′-trimethylsilyl-1,6-diaminohexane, piperidine, pyrrolidine, Hexamethyleneimine, heptamethyleneimine, dicyclohexylamine, N-methylbenzylamine, di- (2-ethylhexyl) amine, diallylamine, morpholine, N- (trimethylsilyl) piperazine, N- (tert-butyldimethylsilyl) piperazine, 1, 3-ditrimethylsilyl-1,3,5-triazinan and the like. When the polymerization is performed in the presence of the compound (R), the compound (R) is prepared by previously mixing the organolithium compound and the compound (B1), and the prepared compound (R) is added to the polymerization system. To perform polymerization. Alternatively, the polymerization may be carried out by adding the organolithium compound and the compound (B1) to the polymerization system and mixing the two in the polymerization system to prepare the compound (R).

(Method of anionic polymerization)
The method for producing a copolymer by anionic polymerization using the polymerization initiator is not particularly limited, and a conventionally known method can be used.
Specifically, an organic solvent inert to the reaction, for example, aliphatic, alicyclic, in a hydrocarbon solvent such as an aromatic hydrocarbon compound, for example, butyllithium as a polymerization initiator, if necessary, randomizer By subjecting styrene, 1,3-butadiene, and the like to anionic polymerization in the presence of styrene, an intended copolymer such as a styrene-butadiene copolymer can be obtained.

(Hydrocarbon solvents in anionic polymerization)
The hydrocarbon solvent preferably has 3 to 8 carbon atoms, for example, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2. -Butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene and the like. These may be used alone or as a mixture of two or more.

(Randomizer in anionic polymerization)
The randomizer is used to control the microstructure of the conjugated diene moiety in the copolymer, for example, increase the 1,2-bond in butadiene, increase the 3,4-bond in isoprene, or the composition of the monomer unit in the copolymer. A compound having an effect of controlling distribution, for example, randomizing styrene units and butadiene units in a styrene-butadiene copolymer. The randomizer is not particularly limited, and any known compounds generally used as conventional randomizers can be used. For example, dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, bistetrahydrofurylpropane, triethylamine, pyridine, N-methylmorpholine, N, N, N ', N'-tetramethylethylenediamine (TMEDA), Examples thereof include ethers such as 2-dipiperidinoethane and tertiary amines. Further, potassium salts such as potassium-t-amylate and potassium-t-butoxide, and sodium salts such as sodium-t-amylate can also be used. One of these randomizers may be used alone, or two or more thereof may be used in combination. The amount of the randomizer used is preferably at least 0.01 mole equivalent, more preferably at least 0.05 mole equivalent, per mole of the organic lithium compound. If the used amount of the randomizer is less than 0.01 molar equivalent, the effect of addition is small and randomization tends to be difficult. Further, the use amount of the randomizer is preferably at most 1,000 molar equivalents, more preferably at most 500 molar equivalents, per mol of the organic lithium compound. When the use amount of the randomizer exceeds 1000 molar equivalents, the reaction rate of the monomer greatly changes, and on the contrary, randomization tends to be difficult.

By adjusting the type and amount of the randomizer, the Tg of the copolymer can be adjusted. For example, the Tg of the copolymer can be reduced by reducing the amount of tetrahydrofuran.

(Reaction temperature)
The reaction temperature at the time of anionic polymerization is not particularly limited as long as the reaction proceeds suitably, but is usually preferably from -10 ° C to 100 ° C, more preferably from 25 ° C to 70 ° C.

(Denaturation step)
By reacting the active terminal of the copolymer obtained in the above polymerization step with the compound (B2) having a functional group that interacts with silica, the active terminal of the copolymer interacts with silica at the polymerization end terminal of the copolymer. Functional groups can be introduced. As a result, a copolymer having a modified polymerization end is obtained. In the present invention, the term "terminal" means a portion other than the structure derived from the monomer having a carbon-carbon double bond, which is present at the end of the molecular chain.

（式（１）中、Ａ^１は、窒素原子、リン原子及び硫黄原子からなる群より選択される少なくとも一種の原子を有し、活性水素を有さず、かつＲ^５に対して窒素原子、リン原子又は硫黄原子で結合する１価の官能基である。Ｒ^３及びＲ^４はヒドロカルビル基であり、Ｒ^５はヒドロカルビレン基であり、ｎは０〜２の整数である。但し、Ｒ^３及びＲ^４が複数存在する場合、複数のＲ^３及びＲ^４は、それぞれ同じでも異なっていてもよい。）
（ＩＩ）分子中に、環状エーテル基、（チオ）カルボニル基及びイソ（チオ）シアナート基からなる群より選択される少なくとも１種の官能基（ｘ１）と、窒素原子、リン原子、酸素原子及び硫黄原子からなる群より選択される少なくとも一種の原子（但し、窒素原子、リン原子及び硫黄原子は、少なくともいずれかが３置換のヒドロカルビルシリル基で保護されていてもよい。）を有し、かつ活性水素を有していない、前記官能基（ｘ１）とは異なる基（ｘ２）と、を各々１つ以上有する化合物（Ｂ２−２）；
（ＩＩＩ）分子中に、イソ（チオ）シアナート基を２つ以上有する化合物（Ｂ２−３）；
等が挙げられる。化合物（Ｂ２）としては、これらを一種単独で又は二種以上を組み合わせて使用することができる。なお、本明細書において、（チオ）カルボニル基は、カルボニル基及びチオカルボニル基を示し、イソ（チオ）シアナート基は、イソシアナート基及びイソチオシアナート基を示す。 The copolymer used in the above modification reaction (hereinafter also referred to as a terminal modification reaction) may have an unmodified or a modified polymerization initiation terminal as long as it has an active terminal. The compound (B2) is not particularly limited as long as it has a functional group that interacts with silica and can react with a polymerization active terminal. Preferred specific examples of the compound (B2) include, for example, (I) a compound (B2-1) represented by the following formula (1);

(In the formula (1), A ¹ has at least one atom selected from the group consisting of a nitrogen atom, a phosphorus atom and a sulfur atom, has no active hydrogen, and has a nitrogen atom for R ⁵ ; R ³ and R ⁴ are hydrocarbyl groups, R ⁵ is a hydrocarbylene group, and n is an integer of 0 to 2, provided that R is a monovalent functional group linked by a phosphorus atom or a sulfur atom. ^{If 3} and R ⁴ there are a plurality, the plurality of R ³ and R ⁴ may be the same or different.)
(II) In a molecule, at least one functional group (x1) selected from the group consisting of a cyclic ether group, a (thio) carbonyl group and an iso (thio) cyanate group, a nitrogen atom, a phosphorus atom, an oxygen atom, Has at least one atom selected from the group consisting of sulfur atoms (provided that at least one of a nitrogen atom, a phosphorus atom and a sulfur atom may be protected by a trisubstituted hydrocarbylsilyl group), and A compound (B2-2) having at least one group (x2) having no active hydrogen and different from the functional group (x1);
(III) a compound (B2-3) having two or more iso (thio) cyanate groups in the molecule;
And the like. As the compound (B2), these can be used alone or in combination of two or more. In this specification, a (thio) carbonyl group indicates a carbonyl group and a thiocarbonyl group, and an iso (thio) cyanate group indicates an isocyanate group and an isothiocyanate group.

In the above formula (1), the hydrocarbyl group of R ³ and R ⁴ includes a linear or branched alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or a cycloalkyl group having 6 to 20 carbon atoms. It is preferably an aryl group.
R ⁵ is preferably a linear or branched alkanediyl group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, or an arylene group having 6 to 20 carbon atoms.
n is preferably 0 or 1 from the viewpoint of increasing the reactivity with the copolymer.
A ¹ has at least one atom selected from the group consisting of a nitrogen atom, a phosphorus atom and a sulfur atom (hereinafter, also referred to as a specific atom), and bonds to R ⁵ at these specific atoms. The specific atom is not bonded to active hydrogen and may be protected by, for example, a trisubstituted hydrocarbylsilyl group. Here, the term "active hydrogen" refers to a hydrogen atom bonded to an atom other than a carbon atom, and preferably refers to a hydrogen atom having a lower binding energy than a carbon-hydrogen bond of polymethylene.

A ¹ is particularly preferably a group that can be turned into an onium ion by an onium salt generator. When the compound (B2) has such a group (A ¹ ), excellent shape retention can be imparted to the modified copolymer.
Specific examples of A ¹ include, for example, a nitrogen-containing group in which two hydrogen atoms of a primary amino group are substituted with two protecting groups, and a hydrogen atom of a secondary amino group is substituted with one protecting group. A nitrogen-containing group, a phosphorus-containing group in which two hydrogen atoms of a tertiary amino group, an imino group, a pyridyl group, and a primary phosphino group are substituted with two protecting groups, and one hydrogen atom of a secondary phosphino group is 1 Examples include a phosphorus-containing group substituted by one protective group, a tertiary phosphino group, and a sulfur-containing group in which one hydrogen atom of a thiol group is substituted by one protective group. Among these, a group having a nitrogen atom is preferable from the viewpoint of good affinity with silica. The "protecting group" is a functional group to be converted to A ¹ in inert functional group to the polymerization active terminal, e.g., 3 hydrocarbylsilyl groups and substituted and the like.

Specific examples of the compound (B2-1) include a nitrogen-containing group in which two hydrogen atoms of a primary amine are substituted with two protecting groups, and one hydrogen atom of a secondary amine is substituted with one protecting group. Examples of the compound having a nitrogen-containing group or a tertiary amino group and an alkoxysilyl group include N, N-bis (trimethylsilyl) aminopropyltrimethoxysilane and N, N-bis (trimethylsilyl) aminopropylmethyl Diethoxysilane, N, N ′, N′-tris (trimethylsilyl) -N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3- (4-trimethylsilyl-1-piperazino) propylmethyldimethoxysilane, And the like.

Compounds having an imino group or a pyridyl group and an alkoxysilyl group include N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine, N- (1-methylpropylidene) ) -3- (Triethoxysilyl) -1-propanamine, N- (4-N, N-dimethylaminobenzylidene) -3- (triethoxysilyl) -1-propanamine, N- (cyclohexylidene)- 3- (triethoxysilyl) -1-propanamine and trimethoxysilyl compounds, methyldiethoxysilyl compounds, ethyldimethoxysilyl compounds, N- (3-trimethoxysilylpropyl) -4 corresponding to these triethoxysilyl compounds , 5-Dihydroimidazole, N- (3-triethoxysilylpropyl) -4,5-dihydroimid Sol, N- (3-trimethoxysilylpropyl) -4,5-imidazole, N- (3-triethoxysilylpropyl) -4,5-imidazole, 3-hexamethyleneiminopropyltrimethoxysilane, 3-hexamethylene Examples include iminopropylmethyldimethoxysilane, and compounds in which the alkyl group and alkanediyl group in the above compounds are replaced with an alkyl group having 1 to 6 carbon atoms and an alkanediyl group having 1 to 6 carbon atoms, respectively.

A phosphorus-containing group in which two hydrogen atoms of a primary phosphino group are substituted by two protective groups, a phosphorus-containing group in which one hydrogen atom of a secondary phosphino group is substituted by one protective group, a tertiary phosphino group Or a compound having a sulfur-containing group in which one hydrogen atom of a thiol group is substituted with one protective group and an alkoxysilyl group include P, P-bis (trimethylsilyl) phosphinopropylmethyldimethoxysilane, P , P-bis (trimethylsilyl) phosphinopropyltrimethoxysilane, 3-dimethylphosphinopropyltrimethoxysilane, 3-dimethylphosphinopropylmethyldimethoxysilane, 3-diphenylphosphinopropyltrimethoxysilane, 3-diphenylphosphinopropyl Triethoxysilane, 3- Phenylphosphinopropylmeryldimethoxysilane, S-trimethylsilylmercaptopropylmethyldimethoxysilane, S-trimethylsilylmercaptopropyltrimethoxysilane, S-trimethylsilylmercaptopropyltriethoxysilane, S-trimethylsilylmercaptopropylmethyldiethoxysilane, and in the above compounds Examples thereof include compounds in which an alkyl group and an alkanediyl group are replaced with an alkyl group having 1 to 6 carbon atoms and an alkanediyl group having 1 to 6 carbon atoms, respectively. Other examples of the compound having an iso (thio) cyanate group include 3-isocyanatopropyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane.

In the compound (B2-2), the group (x2) is preferably a group containing a nitrogen atom that is not bonded to active hydrogen, and specific examples thereof include compounds having a cyclic ether group such as Epoxyamine compounds such as glycidyl-1,3-bisaminomethylcyclohexane;
Examples of the compound having a (thio) carbonyl group include 4-aminoacetophenone such as 4-N, N-dimethylaminobenzophenone; and bis (dihydrocarbylaminoalkyl) such as 1,7-bis (methylethylamino) -4-heptanone. Ketones; dihydrocarbylaminoalkyl (meth) acrylates such as 2-dimethylaminoethyl acrylate; hydrocarbyl imidazolidinones such as 1,3-dimethyl-2-imidazolidinone; N-hydrocarbyl pyrrolidones such as 1-phenyl-2-pyrrolidone N-hydrocarbylcaptolactam such as N-methyl-ε-caprolactam; N-dihydrocarbylformamide such as N, N-diethylformamide; N, N-dihydrocarbylacetamide such as N, N-dimethylacetamide; N-dimethyl Acrylamide such as (meth) acrylamide; and the like;
Examples of the compound having an iso (thio) cyanate group include 3-isocyanatopropyltrimethoxysilane.

Examples of the compound (B2-3) include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, and p-phenylene diisocyanate. Isocyanate, tris (isocyanatophenyl) thiophosphate, xylene diisocyanate, benzene-1,2,4-triisocyanate, naphthalene-1,2,5,7-tetraisocyanate, 1,4-phenylenediisothiate Ossinate may be mentioned.

（一般式（１−１）中、Ｒ^６は水素原子またはヒドロカルビル基であり、複数存在するＲ^６は同じであっても異なっていてもよい。Ａ^４、Ｒ^３、Ｒ^５及びｎは上記式（１）のＡ^１、Ｒ^３、Ｒ^５及びｎと同義である。） As the compound (B2), it is particularly preferable to use the compound (B2-1) in that it has a strong affinity for silica. When the silane compound (B2-1) is used, for the purpose of adjusting the Mooney viscosity of the modified copolymer, together with the silane compound (B2-1), silicon tetrachloride and an epoxy-containing compound (for example, tetraglycidyl-1, 3-bisaminomethylcyclohexane) and the like. The compounds (B2) exemplified above all have the same action in that a modified copolymer having a modified polymerization end can be obtained. Therefore, even those not described in the examples described below can be used in the present invention. In addition, the structure represented by the following formula (1-1) is introduced into the polymer terminal by the reaction between the compound represented by the formula (1) and the modified copolymer.

(In the general formula (1-1), R ⁶ is a hydrogen atom or a hydrocarbyl group, and a plurality of R ⁶ may be the same or different. A ⁴ , R ³ , R ⁵ and n are the same as above. (It is synonymous with A ¹ , R ³ , R ⁵ and n in the formula (1).)

The above terminal modification reaction can be performed, for example, as a solution reaction. This solution reaction may be performed using a solution containing an unreacted monomer after the completion of the polymerization reaction in the polymerization step, and the copolymer contained in the solution is isolated and dissolved in a suitable solvent such as cyclohexane. You may go on. Further, the terminal modification reaction may be performed using either a batch system or a continuous system. At this time, the method of adding the compound (B2) is not particularly limited, and examples thereof include a method of adding the compound (B2) at a time, a method of adding the compound at a time, and a method of continuously adding the compound (B2).

The amount of the compound (B2) used for the terminal modification reaction may be appropriately set according to the type of the compound used for the reaction, but is preferably 0.1 to 0.1% of the metal atom involved in the polymerization reaction of the polymerization initiator. It is at least 1 molar equivalent, more preferably at least 0.3 molar equivalent. When the amount is 0.1 molar equivalent or more, the modification reaction can sufficiently proceed, and the dispersibility of silica can be suitably improved.
The temperature of the terminal modification reaction is usually the same as the temperature of the above-mentioned polymerization reaction, preferably -20 to 150 ° C, more preferably 0 to 120 ° C, and particularly preferably 20 to 100 ° C. preferable. If the temperature of the modification reaction is low, the viscosity of the modified copolymer tends to increase. On the other hand, when the temperature of the denaturation reaction is high, the polymerization active terminal is easily deactivated. The reaction time of the denaturation reaction is preferably from 1 minute to 5 hours, more preferably from 2 minutes to 1 hour.

(Reaction stopped)
The anionic polymerization can be terminated by adding a reaction terminator commonly used in this field. As such a reaction terminator, for example, a polar solvent having an active proton such as alcohol or acetic acid such as methanol, ethanol and isopropanol and a mixture thereof, or a mixture of such a polar solvent and a non-polar solvent such as hexane and cyclohexane. Mixtures are mentioned. The addition amount of the reaction terminator is usually about the same molar amount or about twice the molar amount with respect to the anionic polymerization initiator.

<Coupling>
In the method for producing a copolymer, a coupling agent may be added to a hydrocarbon solution of the copolymer from the start of polymerization of the monomer to the recovery of the polymer described below. Examples of the coupling agent include a compound represented by the following formula (2-1).
^{_{R 1 a ML 4-a (}} 2-1)
(In the formula (2-1), R ¹ represents an alkyl group, an alkenyl group, a cycloalkenyl group or an aryl group, M represents a silicon atom or a tin atom, L represents a halogen atom or a hydrocarbyloxy group, and a represents Represents an integer of 0 to 2)

As the coupling agent represented by the above formula (2-1), silicon tetrachloride, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, tin tetrachloride, methyltrichlorotin, dimethyldichlorotin, trimethylchlorotin, tetramethoxy Examples include silane, methyltrimethoxysilane, dimethoxydimethylsilane, methyltriethoxysilane, ethyltrimethoxysilane, dimethoxydiethylsilane, diethoxydimethylsilane, tetraethoxysilane, ethyltriethoxysilane, and diethoxydiethylsilane.

The amount of the coupling agent to be added is preferably 0.03 mol or more, more preferably 0.05 mol or more, per 1 mol of the alkali metal derived from the alkali metal catalyst in order to enhance the processability of the polymer. In order to enhance fuel economy, the amount is preferably 0.4 mol or less, more preferably 0.3 mol or less.

<Hydrogenation method>
In the method for producing a hydrogenated copolymer, the copolymer described above is hydrogenated to obtain a hydrogenated copolymer having a hydrogenation rate of 75 mol% or more. By hydrogenating the copolymer, there is an advantage that heat resistance is improved. On the other hand, if the hydrogenation rate is low, the effect of improving the rubber breaking strength and wear resistance cannot be sufficiently obtained.

The method of hydrogenation and the reaction conditions are not particularly limited, and hydrogenation may be performed by a known method and known conditions. Usually, the reaction is carried out at 20 to 150 ° C. and under a hydrogen pressure of 0.1 to 10 MPa in the presence of a hydrogenation catalyst. The hydrogenation rate can be arbitrarily selected by changing the amount of the hydrogenation catalyst, the hydrogen pressure during the hydrogenation reaction, the reaction time, and the like. As the hydrogenation catalyst, usually, a compound containing any one of metals of Groups 4 to 11 of the periodic table can be used. For example, compounds containing Ti, V, Co, Ni, Zr, Ru, Rh, Pd, Hf, Re, and Pt atoms can be used as the hydrogenation catalyst. More specific hydrogenation catalysts include metallocene compounds such as Ti, Zr, Hf, Co, Ni, Pd, Pt, Ru, Rh, and Re; metals such as Pd, Ni, Pt, Rh, and Ru as carbon; A supported heterogeneous catalyst supported on a carrier such as silica, alumina, or diatomaceous earth; a homogeneous Ziegler-type catalyst obtained by combining an organic salt or acetylacetone salt of a metal element such as Ni or Co with a reducing agent such as organic aluminum; Organometallic compounds or complexes such as Ru and Rh; fullerenes and carbon nanotubes in which hydrogen is stored.

Among these, metallocene compounds containing any of Ti, Zr, Hf, Co, and Ni are preferable in that they can be uniformly hydrogenated in an inert organic solvent. Further, a metallocene compound containing any of Ti, Zr, and Hf is preferable. In particular, a hydrogenation catalyst obtained by reacting a titanocene compound with an alkyl lithium is preferable because it is an inexpensive and industrially particularly useful catalyst. As specific examples, for example, JP-A-1-275605, JP-A-5-271326, JP-A-5-271325, JP-A-5-222115, JP-A-11-292924, 2000-37632, JP-A-59-133203, JP-A-63-5401, JP-A-62-218403, JP-A-7-90017, JP-B-43-19960, The hydrogenation catalyst described in JP-B-47-40473 can be exemplified. In addition, these hydrogenation catalysts can be used individually by 1 type or in combination of 2 or more types.

The content of the hydrogenated copolymer in 100% by mass of the rubber component is 75% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 100% by mass. is there. When the content of the hydrogenated copolymer is less than 75% by mass, the effect of improving the rubber breaking strength and the wear resistance (particularly, the rubber breaking strength) tends to be hardly obtained.

In particular, when the hydrogenated copolymer is a hydrogenated styrene butadiene copolymer, the content of the hydrogenated styrene butadiene copolymer in 100% by mass of the rubber component is preferably 90% by mass or more, and more preferably. Is 95% by mass or more, and more preferably 100% by mass.

Other rubber components that can be used in addition to the hydrogenated copolymer include conventional styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), butadiene isoprene copolymer rubber, butyl rubber, and the like. Further, natural rubber (NR), ethylene propylene copolymer, ethylene octene copolymer and the like can also be mentioned. These rubber components may be used in combination of two or more.

When NR is contained as the rubber component, the NR is not particularly limited, and for example, SIR20, RSS # 3, TSR20, and the like generally used in the tire industry can be used.

The rubber composition according to the present invention further includes a filler. In the present specification, the filler is one that is added to the rubber composition for the purpose of reinforcing the rubber, for example, silica, calcium carbonate, mica such as sericite, aluminum hydroxide, magnesium oxide, magnesium hydroxide, White fillers such as clay, talc, alumina, titanium oxide and mica; and carbon black. These fillers may be used in combination of two or more. The rubber composition of the present invention contains silica as a filler, and preferably further contains carbon black. Thereby, the effect of the present invention can be more suitably obtained.

The silica is not particularly limited, and examples thereof include dry silica (anhydrous silica) and wet silica (hydrous silica). Of these, wet silica is preferable because of a large amount of silanol groups.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 30 m ² / g or more, more preferably 45 m ² / g or more, further preferably 60 m ² / g or more, particularly preferably 100 m ² / g or more, and most preferably. Is 150 m ² / g or more. If it is less than 30 m ² / g, the abrasion resistance and the rubber breaking strength may be deteriorated. The _N 2 SA of the silica is preferably 500 meters ² / g or less, more preferably 350 meters ² / g or less, more preferably 300 meters ² / g or less, particularly preferably 270 meters ² / g or less, and most preferably 220 m ² / g or less. If it exceeds 500 m ² / g, it is difficult to disperse the silica, and the fuel economy may be deteriorated.
In addition, the nitrogen adsorption specific surface area of silica is a value measured by a BET method according to ASTM D3037-81.

The content of silica is preferably at least 5 parts by mass, more preferably at least 10 parts by mass, still more preferably at least 30 parts by mass, particularly preferably at least 45 parts by mass with respect to 100 parts by mass of the rubber component. If the amount is less than 5 parts by mass, the effect of blending silica is not sufficiently obtained, and fuel economy and abrasion resistance tend to deteriorate. The content of the silica is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and further preferably 100 parts by mass or less. If the amount exceeds 150 parts by mass, the silica is difficult to disperse, so that processability, fuel economy and abrasion resistance tend to deteriorate.

When the rubber composition in the present invention contains a filler, the content of silica in 100% by mass of the filler is preferably 80% by mass or more, more preferably 90% by mass or more. If it is less than 80% by mass, the effect of the present invention may not be sufficiently obtained. In addition, when the content of silica in the filler of 100% by mass is less than 80% by mass, when carbon black is used as the remaining filler, wet grip performance tends to be deteriorated. When the filler is used, the abrasion resistance may be deteriorated.

In the rubber composition of the present invention, it is preferable to use a silane coupling agent together with silica. In the present invention, since the above hydrogenated copolymer having a high hydrogenation rate is used, a sufficient crosslink density may not be obtained, but silica and a silane coupling agent are blended together with the hydrogenated copolymer. Thereby, a good crosslinked network can be formed, and the effects of the present invention can be more suitably obtained.

As the silane coupling agent, conventionally known silane coupling agents can be used. For example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxy) (Silylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) ) Disulfide, bis (3-trimethoxysilylpropyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazolyltetrasulfide, 3-trie Sulfides such as xylsilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, and 3-trimethoxysilylpropyl methacrylate monosulfide; 3-mercaptopropyltrimethoxysilane; 3-mercaptopropyltriethoxysilane; Mercapto-based such as mercaptoethyltrimethoxysilane and 2-mercaptoethyltriethoxysilane; vinyl-based such as vinyltriethoxysilane and vinyltrimethoxysilane; 3-aminopropyltriethoxysilane; 3-aminopropyltrimethoxysilane; Amino series such as (2-aminoethyl) aminopropyltriethoxysilane and 3- (2-aminoethyl) aminopropyltrimethoxysilane, and γ-glycidoxypropyltrie Glycidoxy, such as toxoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, 3-nitropropyltrimethoxysilane, 3-nitropropyltrimethoxysilane Nitro series such as ethoxysilane, and chloro series such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane and the like can be mentioned. The above silane coupling agents may be used alone or in combination of two or more. Of these, sulfide-based silane coupling agents are preferred from the viewpoint of the coupling effect, processability, and cost of the silane coupling agent, and bis (3-triethoxysilylpropyl) tetrasulfide and bis (3-triethoxysilylpropyl) Disulfide is more preferred.

The content of the silane coupling agent is preferably at least 3 parts by mass, more preferably at least 5 parts by mass, based on 100 parts by mass of silica. If the amount is less than 3 parts by mass, the coupling effect is insufficient, high silica dispersion cannot be obtained, and the effect of the present invention tends to be insufficient. Therefore, fuel economy and rubber breaking strength may be reduced. The content of the silane coupling agent is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of silica. If the amount exceeds 15 parts by mass, an extra silane coupling agent may remain, which may cause deterioration in processability and breakage characteristics of the obtained rubber composition.

When the rubber composition in the present invention contains carbon black, examples of the carbon black include furnace blacks (furnace carbon blacks) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF and ECF. ); Acetylene black (acetylene carbon black); thermal black (thermal carbon black) such as FT and MT; channel black (channel carbon black) such as EPC, MPC and CC; and graphite. These can be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is usually from 5 to 200 m ² / g. The lower limit is preferably 50 m ² / g, and more preferably 80 m ² / g. The upper limit is preferably 150 m ² / g, and more preferably 120 m ² / g. Further, the absorption amount of dibutyl phthalate (DBP) of carbon black is usually 5 to 300 ml / 100 g, the lower limit is preferably 80 ml / 100 g, and the upper limit is preferably 180 ml / 100 g. If the amount of N ₂ SA or DBP absorption of the carbon black is less than the lower limit of the above range, the reinforcing effect tends to be small and the wear resistance tends to decrease. If the amount exceeds the upper limit of the above range, the dispersibility is poor and the hysteresis loss increases. Fuel economy tends to decrease.
The nitrogen adsorption specific surface area is measured according to ASTM D4820-93, and the DBP absorption is measured according to ASTM D2414-93.

When the rubber composition of the present invention contains carbon black, the content of carbon black is preferably at least 1 part by mass, more preferably at least 3 parts by mass, based on 100 parts by mass of the rubber component. If the amount is less than 1 part by mass, sufficient reinforcement may not be obtained. The content of carbon black is preferably 60 parts by mass or less, more preferably 30 parts by mass or less, and still more preferably 15 parts by mass or less. If it exceeds 60 parts by mass, fuel economy tends to deteriorate.

The rubber composition according to the present invention contains a compound (processing aid) represented by the following formula (I).

In the formula (I), R ³⁰¹ represents a hydrogen atom, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched carbon atom having 6 to 30 carbon atoms. Represents 30 aryl groups or hydroxyl groups. R ³⁰² and R ³⁰³ are the same or different and each are a hydrogen atom, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched carbon number. 2 to 30 alkynyl groups, branched or unbranched aryl groups having 6 to 30 carbon atoms, or groups represented by the following formula (II): the alkyl group, the alkenyl group, the alkynyl group, and the aryl group May be substituted with a hydroxyl group or a carboxyl group. R ³⁰¹ and R ³⁰² , R ³⁰¹ and R ³⁰³ , or R ³⁰² and R ³⁰³ may form a ring structure. d ₁ is an integer of 0-8.

In the formula (II), R ³⁰⁴ represents a branched or unbranched alkylene group having 1 to 30 carbon atoms. R ³⁰⁵ is a hydrogen atom, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched aryl group having 6 to 30 carbon atoms, or Represents a hydroxyl group. d ₂ is an integer of 0.

As a branched or unbranched alkyl group having 1 to 30 carbon atoms (preferably 3 to 25 carbon atoms, more preferably 10 to 20 carbon atoms, and still more preferably 15 to 20 carbon atoms) for R ³⁰¹ , for example, a methyl group , Ethyl group, n-propyl group, isopropyl group, n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group , Nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, octadecyl and the like.

^Examples of the branched or unbranched alkenyl group having 2 to 30 carbon atoms (preferably having 3 to 25 carbon atoms, more preferably having 10 to 20 carbon atoms, and still more preferably having 15 to 20 carbon atoms) include a vinyl group. , 1-propenyl group, 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, pentadecenyl group, octadecenyl group and the like.

Examples of the branched or unbranched aryl group having 6 to 30 (preferably 6 to 10) carbon atoms for R ³⁰¹ include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a biphenyl group and the like.

As R ³⁰¹ , a hydrogen atom, a branched or unbranched alkyl group having 1 to 30 carbon atoms, and a hydroxyl group (—OH) are preferable, and the above alkyl group is more preferable.

R ³⁰² and R ^{303 each have} a branched or unbranched carbon number of 1 to 30 (preferably 1 to 25 carbon atoms, more preferably 1 to 20 carbon atoms, still more preferably 1 to 10 carbon atoms, and particularly preferably 1 to 10 carbon atoms. the alkyl group of 5), for example, a branched or unbranched same group as the alkyl group having 1 to 30 carbon atoms of the R ^301.

R ³⁰² and R ^{303 each have} 2 to 30 branched or unbranched carbon atoms (preferably 2 to 25 carbon atoms, more preferably 2 to 20 carbon atoms, still more preferably 2 to 10 carbon atoms, and particularly preferably 2 to 2 carbon atoms. the alkenyl group of 5), for example, a branched or unbranched same groups as the alkenyl group having 2 to 30 carbon atoms of the R ^301.

R ³⁰² and R ^{303 each have} 2 to 30 branched or unbranched carbon atoms (preferably 2 to 25 carbon atoms, more preferably 2 to 20 carbon atoms, still more preferably 2 to 10 carbon atoms, and particularly preferably 2 to 2 carbon atoms. Examples of the alkynyl group 5) include an ethynyl group, a propynyl group, a butynyl group, a pentynyl group, a hexynyl group, a heptynyl group, an octynyl group, a noninyl group, a decynyl group, an undecynyl group, and a dodecynyl group.

The aryl group of the branched or unbranched carbon atoms 6 to 30 (preferably 6 to 10 carbon atoms) in R ³⁰² and ^{R 303,} for example, branched or unbranched aryl group having 6 to 30 carbon atoms of the ^{R 301} And the same groups as described above.

R ³⁰² and R ^{303 each} represent a hydrogen atom, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkyl group substituted with a hydroxyl group or a carboxyl group, having 1 to 30 carbon atoms, a hydroxyl group or a carboxyl group. A branched or unbranched aryl group having 6 to 30 carbon atoms substituted with a group, a group represented by the above formula (II) is preferable, and the above alkyl group substituted with the above alkyl group, hydroxyl group or carboxyl group is more preferable. And a combination of the above alkyl group and the above alkyl group substituted with a hydroxyl group or a carboxyl group. In the case of this combination, better fuel economy can be obtained.

d ₁ is an integer of 0-8. The reason that the effect can be obtained favorably according to the present invention, it is preferable that d ₁ is an integer of 0 to 3, more preferably 0.

Examples of the branched or unbranched alkylene group having 1 to 30 (preferably 1 to 15 carbon atoms, more preferably 1 to 3 carbon atoms) of R ³⁰⁴ include 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 alkyl group having 1 to 30 (preferably 3 to 25, more preferably 10 to 20) carbon atoms of R ³⁰⁵ include the branched or unbranched carbon number of R ³⁰¹ described above. The same groups as the alkyl groups 1 to 30 can be exemplified.

Examples of the branched or unbranched alkenyl group having 2 to 30 (preferably 3 to 25, more preferably 10 to 20) carbon atoms of R ³⁰⁵ include, for example, the branched or unbranched carbon number of R ³⁰¹ described above. The same groups as the 2 to 30 alkenyl groups can be exemplified.

The branched or aryl group unbranched carbon atoms 6 to 30 (preferably 6 to 10 carbon atoms) of R ^305, e.g., similar to branched or unbranched aryl group having 6 to 30 carbon atoms in the ^{R 301} Groups can be mentioned.

As R ³⁰⁵ , a branched or unbranched alkyl group having 1 to 30 carbon atoms is preferable.

d ₂ is an integer of 0. The reason that the effects of the present invention can be obtained satisfactorily, it is preferable that d ₂ is an integer of 0 to 3, more preferably 0.

Examples of the compound represented by the formula (I) include N, N-dimethylformamide, octadecanamide, N- (4-hydroxyphenyl) octadecanamide, ε-caprolactam, sarcosine, N-lauroylsarcosine, N-octadecylsarcosine. , N, N'-ethylenebisoctadecanamide, N- (1-oxooctadecyl) sarcosine and the like. These may be used alone or in combination of two or more.

The content of the compound represented by the formula (I) is preferably 0.5 parts by mass or more, more preferably 0.7 parts by mass or more, and still more preferably 1 part by mass or more based on 100 parts by mass of silica. . If the amount is less than 0.5 parts by mass, the improvement effect of the compound represented by the formula (I) may not be sufficiently obtained. Further, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 10 parts by mass or less. If the amount exceeds 20 parts by mass, fuel economy may be deteriorated.

In the rubber composition of the present invention, it is preferable to further compound an amino acid derivative in addition to the compound represented by the formula (I). Thereby, the dispersibility of silica can be further improved, and the effect of improving each performance can be further enhanced.

When an amino acid derivative is further compounded in addition to the compound represented by the formula (I), HT254 manufactured by Schill + Seilacher, which is commercially available as a mixture of the compound represented by the formula (I) and the amino acid derivative, may be used. Can be used.

The total content of the compound represented by the formula (I) and the amino acid derivative is preferably at least 0.5 part by mass, more preferably at least 0.7 part by mass, and still more preferably 1 part by mass, per 100 parts by mass of silica. Parts by weight, particularly preferably at least 2 parts by weight, most preferably at least 3 parts by weight. If the amount is less than 0.5 parts by mass, the compound represented by the formula (I) and the amino acid derivative may not be sufficiently improved. Further, the total content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 10 parts by mass or less. If the amount exceeds 20 parts by mass, fuel economy may be deteriorated.

In addition to the above components, the rubber composition of the present invention may further contain a vulcanizing agent such as sulfur; a thiazole vulcanization accelerator, a thiuram vulcanization accelerator, a sulfenamide vulcanization accelerator, and a guanidine vulcanization accelerator. Vulcanization accelerators such as agents; vulcanization activators such as stearic acid and zinc oxide; organic peroxides; processing aids such as extender oils (oils) and lubricants; Can be used.

As extender oils (oils), aromatic mineral oils (viscosity constants (VGC values) 0.900 to 1.049) and naphthenic mineral oils (VGC values of 0. 850 to 0.899) and paraffinic mineral oil (VGC value 0.790 to 0.849). The polycyclic aromatic content of the extender oil is preferably less than 3% by weight, more preferably less than 1% by weight. The polycyclic aromatic content is measured according to the British Petroleum Institute 346/92 method. Further, the aromatic compound content (CA) of the extension oil is preferably 20% by mass or more. These extender oils may be used in combination of two or more.

Examples of the vulcanization accelerator include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, dibenzothiazyldisulfide, and N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram monosulfide, tetramethylthiuram disulfide Thiuram-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N- Sulfenamide-based vulcanization accelerators such as oxyethylene-2-benzothiazolesulfenamide, N, N'-diisopropyl-2-benzothiazolesulfenamide; diphenylguanidine, dioltotolylguanidine, orthotolylbiguanidine and the like Guani It can be mentioned emission-based vulcanization accelerator. Among them, a sulfenamide-based vulcanization accelerator is preferable, and N-cyclohexyl-2-benzothiazolesulfenamide is more preferable because the effects of the present invention can be more suitably obtained. It is also preferable to use a guanidine vulcanization accelerator in combination. The amount of the vulcanization accelerator used is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4 parts by mass, per 100 parts by mass of the rubber component.

The vulcanizing agent is not particularly limited, but sulfur can be suitably used. The sulfur content is preferably 0.5 to 5 parts by mass, more preferably 1 to 3 parts by mass, based on 100 parts by mass of the rubber component. Thereby, the effect of the present invention can be more suitably obtained.

The rubber composition in the present invention is produced by a general method. That is, it can be produced by a method of kneading the above components with a Banbury mixer, a kneader, an open roll, or the like, followed by vulcanization.

The rubber composition of the present invention can be used for each member (tread, sidewall, carcass, belt, bead, etc.) of a tire, and is particularly preferably used as a tread of a tire. In the case of a tread having a two-layer structure, the tread includes a surface layer (cap tread) and an inner surface layer (base tread).

The tread having a multilayer structure is manufactured by a method in which a sheet-shaped tread is bonded to a predetermined shape, or a method in which two or more extruders are charged and formed into two or more layers at a head outlet of the extruder. Can be.

The pneumatic tire of the present invention is manufactured by a usual method using the above rubber composition. That is, a rubber composition containing the rubber component containing the hydrogenated copolymer, silica, the compound represented by the above formula (I) and, if necessary, the above various compounding agents is added to an unvulcanized stage such as a tread. An unvulcanized tire is formed by extruding according to the shape of each tire member and forming it together with other tire members on a tire molding machine by a usual method. By heating and pressurizing the unvulcanized tire in a vulcanizer, the pneumatic tire of the present invention is obtained.

The pneumatic tire of the present invention is suitably used as a tire for passenger cars, a tire for trucks and buses, a tire for motorcycles, a tire for competition, and the like, and is particularly preferably 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.

Hereinafter, various chemicals used in the synthesis and polymerization will be described together. The chemicals were purified as necessary according to a standard method.
n-hexane: Styrene manufactured by Kanto Chemical Co., Ltd .: Butadiene manufactured by Kanto Chemical Co., Ltd .: 1,3-butadiene TMEDA manufactured by Tokyo Chemical Industry Co., Ltd .: N, N, N ′, N manufactured by Kanto Chemical Co., Ltd. '-Tetramethylethylenediamine n-butyllithium solution: 1.6 M n-butyllithium hexane solution manufactured by Kanto Chemical Co., Ltd.Ethanol: 2,6-di-tert-butyl-p-cresol manufactured by Kanto Chemical Co., Ltd .: large Nocrack 200 manufactured by Uchi Shinko Chemical Industry Co., Ltd.
Amine modifier: N, N-bis (trimethylsilyl) aminopropylmethyldiethoxysilane

The method for evaluating the obtained copolymer will be described below.

(Measurement of hydrogenation rate of conjugated diene part of copolymer)
A solution having a concentration of 15% by mass was prepared using carbon tetrachloride as a solvent, and the solution was calculated from the spectrum reduction rate of the unsaturated bond portion in H ¹ -NMR at 100 MHz.

(Measurement of styrene content)
H ¹ -NMR was measured at 25 ° C. using a JEOL JNM-A400 NMR apparatus, and a phenyl proton based on styrene units of 6.5 to 7.2 ppm and 4.9 to 5.4 ppm of butadiene obtained from the spectrum were measured. The styrene content was determined from the ratio of vinyl protons based on units.

(Measurement of weight average molecular weight (Mw) and number average molecular weight (Mn))
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the copolymer were determined by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: Tosoh Corporation) ) Was measured in terms of standard polystyrene based on the value measured by TSKGEL SUPERMULTIPORE HZ-M). When the copolymer has a modifying group, Mw and Mn were measured before performing the modifying treatment. This is because when a copolymer having a modifying group is measured, the modifying group interacts with the silica gel of the column, and accurate Mw and Mn cannot be obtained.

(Measurement of glass transition temperature (Tg))
The glass transition temperature (Tg) is measured according to JIS K 7121 using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan Inc. while heating at a heating rate of 10 ° C./min. Was determined as a glass transition onset temperature.

<Production example of copolymer>
Synthesis Example 1 (Synthesis of copolymer (1): hydrogenation rate: 0 mol%, SBR)
2000 ml of n-hexane, 60 g of styrene, 140 g of 1,3-butadiene, 0.93 g of TMEDA and 0.45 mmol of n-butyllithium were added to a heat-resistant reaction vessel sufficiently purged with nitrogen, and the mixture was stirred at 50 ° C. for 5 hours to carry out a polymerization reaction. went. Thereafter, ethanol was added to stop the reaction, and 1 g of 2,6-tert-butyl-p-cresol was added to the reaction solution, followed by reprecipitation purification to obtain a copolymer (1). The obtained copolymer (1) had a weight average molecular weight (Mw) of 490,000 and a styrene content of 30% by mass.

Synthesis Example 2 (Synthesis of copolymer (2): hydrogenation ratio 60 mol%, hydrogenated SBR)
Copolymer (2) was obtained according to the same recipe as copolymer (1) except that the obtained polymer was hydrogenated. That is, after the polymerization conversion reaction in the copolymer (1), ethanol was not added to stop the polymerization reaction, and then the mixture was stirred for 20 minutes while supplying hydrogen gas at a pressure of 0.4 MPa-Gauge to obtain unreacted polymer. It was reacted with terminal lithium to obtain lithium hydride. The hydrogen gas supply pressure was set to 0.7 MPa-Gauge, the reaction temperature was set to 90 ° C., and hydrogenation was performed using a catalyst mainly composed of titanocene dichloride. When the amount of hydrogen absorbed reaches the target amount of hydrogenation, the reaction temperature is set to normal temperature, the hydrogen pressure is returned to normal pressure, the reaction solution is taken out of the reaction vessel, the reaction solution is stirred into water, and the solvent is steamed. The hydrogenated copolymer was obtained by removing by stripping. The hydrogenation ratio of the obtained copolymer (2) was 60 mol%, and the weight average molecular weight (Mw) was 450,000.

Synthesis Example 3 (Synthesis of copolymer (3): hydrogenation ratio 80 mol%, hydrogenated SBR)
Copolymer (3) was obtained according to the same recipe as copolymer (2) except that the integrated amount of hydrogen suction was adjusted so as to obtain the target hydrogenation rate. The hydrogenation ratio of the obtained copolymer (3) was 80 mol%, and the weight average molecular weight (Mw) was 480,000.

Synthesis Example 4 (Synthesis of copolymer (4): hydrogenation rate 95 mol%, hydrogenated SBR)
Copolymer (4) was obtained according to the same recipe as copolymer (2) except that the integrated amount of hydrogen suction was adjusted so as to obtain the target hydrogenation rate. The hydrogenation ratio of the obtained copolymer (4) was 95 mol%, and the weight average molecular weight (Mw) was 450,000.

Synthesis Example 5 (Synthesis of copolymer (5): hydrogenation rate: 95 mol%, hydrogenated modified SBR)
2000 ml of n-hexane, 60 g of styrene, 140 g of 1,3-butadiene, 0.93 g of TMEDA and 0.45 mmol of n-butyllithium were added to a heat-resistant reaction vessel sufficiently purged with nitrogen, and the mixture was stirred at 50 ° C. for 5 hours to carry out a polymerization reaction. went. Thereafter, 0.15 mol of an amine-based modifier was added, and the mixture was stirred at 0 ° C for 1 hour. In the subsequent steps, a copolymer (5) was obtained according to the same recipe as the copolymer (2) except that the integrated amount of hydrogen suction was adjusted. The hydrogenation ratio of the obtained copolymer (5) was 95 mol%, and the weight average molecular weight (Mw) before modification was 440,000.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described.
Copolymers (1) to (5): Natural rubber synthesized by the above method: TSR20
Carbon black: Diablack N339 manufactured by Mitsubishi Chemical Corporation (N ₂ SA: 96 m ² / g, DBP absorption: 124 ml / 100 g)
Oil: X-140 manufactured by Japan Energy Co., Ltd.
Silica: ULTRASIL VN3 manufactured by EVONIK (N ₂ SA: 180 m ² / g)
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Amide compound A: N, N-dimethylformamide amide compound manufactured by Tokyo Chemical Industry Co., Ltd. B: N, N'-ethylenebisoctadecanamide amide compound C: manufactured by Tokyo Chemical Industry Co., Ltd .: manufactured by Tokyo Chemical Industry Co., Ltd. N-octadecyl sarcosine amide compound D: N-lauroyl sarcosine amide compound E: manufactured by Tokyo Chemical Industry Co., Ltd .: HT254 (manufactured by Schill + Seilacher) (fatty acid amide-based processing aid [fatty acid amide (represented by the above formula (I) Mixture of compound N- (1-oxooctadecyl) sarcosine) and amino acid derivative, fatty acid amide content: 25 to 50% by mass])
Anti-aging agent: Antigen 3C manufactured by Sumitomo Chemical Co., Ltd.
Stearic acid: beaded stearic acid zinc oxide manufactured by NOF CORPORATION: Zinc flower No. 1 wax manufactured by Mitsui Mining & Smelting Co., Ltd .: Sannoc N manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Sulfur: powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd. (1): Succinol CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Sumitomo Chemical Co., Ltd.
Vulcanization accelerator (2): Succinol D (1,3-diphenylguanidine) manufactured by Sumitomo Chemical Co., Ltd.

(Examples and Comparative Examples)
According to the composition shown in Tables 2 to 4, materials other than sulfur and the vulcanization accelerator were kneaded for 5 minutes at 150 ° C. using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd. A paste was obtained. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded with an open roll at 80 ° C. for 5 minutes to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press-vulcanized at 170 ° C. for 20 minutes using a mold having a thickness of 0.5 mm to obtain a vulcanized rubber composition.
In addition, the obtained unvulcanized rubber composition was molded into a tread shape, bonded together with other tire members on a tire molding machine to form an unvulcanized tire, and vulcanized at 170 ° C. for 12 minutes. Tires (size: 195 / 65R15) were manufactured.

<Evaluation items and test methods>
The obtained unvulcanized rubber composition, vulcanized rubber composition, and test tire were evaluated as follows. The results are shown in Tables 2 to 4.

(Rubber breaking strength)
The above vulcanized rubber composition was subjected to a tensile test according to JIS K6251, and the elongation at break was measured. The measurement results are shown by an index with Comparative Example 1 being 100. A higher index indicates a higher rubber breaking strength.
(Rubber breaking strength index) = (Rubber breaking strength of each compound) / (Rubber breaking strength of Comparative Example 1) × 100

(Wear resistance)
The volume loss amount of each vulcanized rubber composition was measured using a LAT tester (Laboratory Ablation and Skid Tester) under the conditions of a load of 50 N, a speed of 20 km / h, and a slip angle of 5 °. The volume loss amount of Comparative Example 1 was set to 100 and indicated as an index. The larger the value, the better the wear resistance.

(Low fuel consumption)
Using a spectrometer manufactured by Kamishima Seisakusho, tan δ of the vulcanized rubber composition was measured at a dynamic strain amplitude of 1%, a frequency of 10 Hz and a temperature of 50 ° C. The value of the reciprocal of tan δ was indicated as an index by setting Comparative Example 1 to 100. The larger the value, the smaller the rolling resistance and the better the fuel economy. In addition, when the index was 85 or more, it was determined to be good.

(Wet grip performance)
Each test tire was mounted on all wheels of a vehicle (domestic FF 2000 cc), and a braking distance from an initial speed of 100 km / h on a wet asphalt road surface was determined. The result is represented by an index, and the larger the number, the better the wet skid performance (wet grip performance). The index was obtained by the following equation.
Wet skid performance = (braking distance of comparative example 1) / (braking distance of each combination) × 100

(Workability)
The obtained unvulcanized rubber composition was subjected to a test in accordance with the description of the Mooney scorch test of the physical test method for unvulcanized rubber in JIS K 6300, and the Mooney viscosity at 130.0 ± 0.5 ° C. (ML _{1 + 4} ) was determined. It was measured. Then, the _{ML 1 + 4} of Comparative Example 1 as 100, the following calculation formula, was displayed by indices of _{ML 1 + 4} of each formulation. The larger the index, the lower the Mooney viscosity, the better the processability, and the higher the productivity.
(Workability index) = (ML _{1 + 4} of Comparative Example 1) / (ML _{1 + 4 of} each formulation) × 100

According to Tables 2 to 4, the hydrogenated styrene-butadiene copolymer having a hydrogenation rate of 75 mol% or more is contained in an amount of 75% by mass or more in 100% by mass of the rubber component. In Examples 1 to 12 using the rubber composition containing 0.5 to 20 parts by mass of the compound represented by the formula (I) with respect to 100 to 150 parts by mass of silica and 100 parts by mass of silica, good fuel economy is maintained. It was also found that the rubber breaking strength, abrasion resistance, wet grip performance and workability can be improved while improving.

Claims (8)

A pneumatic tire manufactured using a rubber composition,
The rubber composition comprises a hydrogenated copolymer obtained by copolymerizing an aromatic vinyl compound and a conjugated diene compound and having a hydrogenation rate of a conjugated diene portion of 75 mol% or more, silica, and a compound represented by the formula (I) ) And a compound represented by the formula:
The content of the hydrogenated copolymer in 100% by mass of the rubber component is 75% by mass or more,
The content of the silica with respect to 100 parts by mass of the rubber component is 5 to 150 parts by mass,
A pneumatic tire having a content of the compound represented by the formula (I) of 0.5 to 20 parts by mass based on 100 parts by mass of the silica.

(In the formula (I), R ³⁰¹ represents a hydrogen atom, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched carbon number of 6 R ³⁰² and R ³⁰³ are the same or different and are a hydrogen atom, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched carbon group having 2 to 30 carbon atoms. An alkyl group, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, a branched or unbranched aryl group having 6 to 30 carbon atoms, or a group represented by the following formula (II): A hydrogen atom of the alkenyl group, the alkynyl group, or the aryl group may be substituted with a hydroxyl group or a carboxyl group, R ³⁰¹ and R ³⁰² , R ³⁰¹ and R ³⁰³ , or R ³⁰² and ^{R 303} and a good .d ₁ to form a ring structure represents an integer of 0-8.)

(In the formula (II), R ³⁰⁴ represents a branched or unbranched alkylene group having 1 to 30 carbon atoms. R ³⁰⁵ represents a hydrogen atom, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkyl group, unbranched alkenyl group having 2 to 30 carbon atoms, branched or unbranched aryl group having 6 to 30 carbon atoms, or .d ₂ representing a hydroxy group represents an integer of 0.) The pneumatic tire according to claim 1, wherein the hydrogenated copolymer has a weight average molecular weight of 200,000 to 2,000,000. The pneumatic tire according to claim 1 or 2, wherein the hydrogenated copolymer has a hydrogenation rate of 90 mol% or more. The pneumatic tire according to any one of claims 1 to 3, wherein the hydrogenated copolymer is a hydrogenated styrene butadiene copolymer. The pneumatic tire according to claim 4, wherein the hydrogenated styrene butadiene copolymer is a hydrogenated modified styrene butadiene copolymer. The pneumatic tire according to claim 4 or 5, wherein the hydrogenated styrene-butadiene copolymer has a styrene content of 5 to 40% by mass. The pneumatic tire according to any one of claims 4 to 6, wherein the content of the hydrogenated styrene-butadiene copolymer in 100% by mass of the rubber component is 90 to 100% by mass. The rubber composition further includes carbon black,
The pneumatic tire according to any one of claims 1 to 7, wherein the content of carbon black is 1 part by mass or more based on 100 parts by mass of the rubber component.