JPWO2019117266A1 - Rubber composition and tires - Google Patents

Abstract

Provided is a rubber composition capable of highly balancing the low loss property of a tire, the wear resistance, and the dry handling property. The rubber composition contains a rubber component (A), a styrene / alkylene block copolymer (B), silica (C), and a silane coupling agent (D), and the styrene / alkylene block copolymer ( B) is characterized in that the total content of styrene units is 30% by mass or more, and the silane coupling agent (D) has a mercapto group.

Description

The present invention relates to rubber compositions and tires.

In recent years, there has been an increasing demand for fuel efficiency of automobiles in connection with the movement of global carbon dioxide emission regulations accompanying the growing interest in environmental issues. In order to meet such demands, reduction of rolling resistance is also required for tire performance. On the other hand, conventionally, as a method for reducing the rolling resistance of a tire, it is common to apply a rubber composition having a low loss tangent (tan δ) (hereinafter referred to as “excellent in low loss property”) to the tire. It is done in.

From the viewpoint of improving vehicle safety, it is also important to ensure braking performance on wet road surfaces (hereinafter referred to as "wet performance"), improving the fuel efficiency of tires and improving wet performance. It is also required. On the other hand, conventionally, tires that have both wet performance and low loss by using a rubber composition containing styrene-butadiene copolymer rubber (SBR) and silica have been the mainstream. In recent years, by using a rubber composition that mainly uses natural rubber (NR) as a rubber component and contains a larger amount of thermoplastic resin and softener than before for tires, wet performance and low loss property are further improved. Improved tires have been proposed (Patent Documents 1 and 2 below).

International Publication No. 2015/07973 International Publication No. 2017/077712

However, as examined by the present inventor, when a rubber composition containing mainly natural rubber as a rubber component and a larger amount of a thermoplastic resin and a softening agent than before is used for the tread rubber of a tire, the elastic modulus of the tread rubber is used. It was found that the rate decreased and there was room for improvement in the steering stability of the tires on dry road surfaces (hereinafter referred to as "dry handling"). Further, the above-mentioned rubber composition has been required to further improve the wear resistance.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a rubber composition capable of highly balancing low loss property, wear resistance and dry handling property of a tire. To do.
Another object of the present invention is to provide a tire in which low loss property, wear resistance and dry handling property are highly balanced.

The gist structure of the present invention for solving the above problems is as follows.

The rubber composition of the present invention contains a rubber component (A), a styrene / alkylene block copolymer (B), silica (C), and a silane coupling agent (D).
The styrene / alkylene block copolymer (B) has a total content of styrene units of 30% by mass or more.
The silane coupling agent (D) is characterized by having a mercapto group.

The tire of the present invention is characterized in that the above rubber composition is used for a tread rubber.

According to the present invention, it is possible to provide a rubber composition capable of highly balancing the low loss property of a tire, the wear resistance, and the dry handling property.
Further, according to the present invention, it is possible to provide a tire in which low loss property, wear resistance and dry handling property are highly balanced.

Hereinafter, the rubber composition and the tire of the present invention will be illustrated and described in detail based on the embodiments thereof.

<Rubber composition>
The rubber composition of the present invention contains a rubber component (A), a styrene / alkylene block copolymer (B), silica (C), and a silane coupling agent (D), and the styrene / alkylene block together. The polymer (B) has a total content of styrene units of 30% by mass or more, and the silane coupling agent (D) has a mercapto group. In addition, the rubber composition of the present invention may contain a filler other than silica (C), a resin (E), and other components, if necessary.

In general, a silane coupling agent having a mercapto group has high activity but tends to deteriorate processability. However, as a result of diligent studies, the present inventors have obtained a styrene / alkylene block copolymer (B) containing a predetermined amount or more of styrene units in combination with the silane coupling agent (D) having a mercapto group. It has been found that the deterioration can be suppressed and the low loss property, dry handling property and wear resistance of the tire can be made parallel at a high level. Although it is not desired to be bound by the theory, the styrene block in the styrene-alkylene block copolymer (B) acts like a filler in the vulcanized product of the rubber composition. On the other hand, it is presumed that one of the reasons is that the alkylene blocks are present between the polystyrene blocks and the friction between the polystyrene blocks is reduced.
Therefore, according to the rubber composition of the present invention, by applying it to the tread rubber of a tire, it is possible to highly balance the low loss property of the tire, the wear resistance, and the dry handling property.

(Rubber component (A))
The rubber component (A) is not particularly limited, and various rubbers can be used. Examples of the rubber component (A) include natural rubber (NR), styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), and chloroprene rubber (CR). , Diene rubber such as isoprene rubber (IR). The rubber component (A) may be unmodified or modified. The rubber component (A) may be used alone or in combination of two or more.

The rubber composition of the present invention preferably contains a natural rubber (A1) as the rubber component (A). When the rubber composition contains natural rubber (A1), the low loss property of the tire can be further improved.
The content of the natural rubber (A1) in the rubber component (A) is preferably 20% by mass or more, more preferably 30% by mass or more. When the content of the natural rubber (A1) in the rubber component (A) is 20% by mass or more, the low loss property of the tire can be further improved. The content of the natural rubber (A1) in the rubber component (A) is preferably 60% by mass or less, more preferably 50% by mass or less.

The rubber composition of the present invention preferably contains as the rubber component (A) a rubber having a glass transition temperature (Tg) of more than −50 ° C. (hereinafter, may be abbreviated as “high Tg rubber”). .. It is more preferable that the high Tg rubber has a glass transition temperature (Tg) of −45 ° C. or higher and −15 ° C. or lower. By including high Tg rubber, the low loss property of the tire can be further improved.
Further, in the present application, rubber having a glass transition temperature (Tg) of −50 ° C. or lower may be abbreviated as “low Tg rubber”. The low Tg rubber preferably has a glass transition temperature (Tg) of −150 ° C. or higher and −50 ° C. or lower. When the low Tg rubber is SBR, its glass transition temperature (Tg) is more preferably −80 ° C. or higher and −52 ° C. or lower.
In the present specification, the glass transition temperature is set as the peak point (Inflection point) of the DSC differential curve by recording the DSC curve while raising the temperature in a predetermined temperature range in accordance with ISO 22768: 2006.

The content of the high Tg rubber in the rubber component (A) is preferably 20 to 50% by mass, more preferably 25 to 40% by mass. When the content of the high Tg rubber in the rubber component (A) is 20% by mass or more, the wet performance of the tire can be improved when applied to the tire. Further, when the content of the high Tg rubber in the rubber component (A) is 50% by mass or less, the processability of the rubber composition is improved.

As the high Tg rubber, the following modified conjugated diene polymer (A2) is preferable.
The modified conjugated diene polymer (A2) has a weight average molecular weight of 20 × 10 ⁴ or more and 300 × 10 ⁴ or less, and has a molecular weight of 200 × with respect to the total amount of the modified conjugated diene polymer (A2). 10 ⁴ or more 500 × 10 ⁴ or less is modified conjugated diene polymer, comprising 0.25% by mass or more and 30% or less, shrinkage factor (g ') is less than 0.64. When the rubber composition contains the modified conjugated diene polymer (A2), the low loss property of the tire can be further improved.

In general, a polymer having a branch tends to have a smaller molecular size when compared with a linear polymer having the same absolute molecular weight, and the contraction factor (g') is assumed to be the same. It is an index of the ratio of the size occupied by the molecule to the linear polymer, which is the absolute molecular weight of. That is, the shrinkage factor (g') tends to decrease as the degree of branching of the polymer increases. In this embodiment, the intrinsic viscosity is used as an index of the size of the molecule, and the linear polymer is used according to the relational expression of the intrinsic viscosity [η] = -3.883M ^0.771 . The shrinkage factor (g') at each absolute molecular weight of the modified conjugated diene polymer is calculated, and the average value of the shrinkage factor (g') when the absolute molecular weight is 100 × 10 ⁴ to 200 × 10 ⁴ is used as the average value. It is used as a contraction factor (g') of the modified conjugated diene polymer. Here, the "branch" is formed by directly or indirectly binding another polymer to one polymer. Further, the "branch degree" is the number of polymers directly or indirectly bonded to each other with respect to one branch. For example, when the five conjugated diene polymer chains described below are indirectly bound to each other via a coupling residue described later, the degree of branching is 5. The coupling residue is a structural unit of the modified conjugated diene polymer bonded to the conjugated diene polymer chain. For example, the conjugated diene polymer described later is reacted with a coupling agent. It is a structural unit derived from a coupling agent produced by. The conjugated diene polymer chain is a constituent unit of the modified conjugated diene polymer, and is derived from the conjugated diene polymer, for example, which is produced by reacting the conjugated diene polymer described later with a coupling agent. It is a structural unit.
The contractile factor (g') is less than 0.64, preferably 0.63 or less, more preferably 0.60 or less, still more preferably 0.59 or less, and even more preferably 0. It is .57 or less. The lower limit of the contraction factor (g') is not particularly limited and may be not more than the detection limit value, but is preferably 0.30 or more, more preferably 0.33 or more, and further preferably 0. It is .35 or more, and even more preferably 0.45 or more. By using the modified conjugated diene polymer (A2) in which the shrinkage factor (g') is in this range, the processability of the rubber composition is improved.
Since the contraction factor (g') tends to depend on the degree of branching, for example, the contraction factor (g') can be controlled using the degree of branching as an index. Specifically, in the case of a modified conjugated diene polymer having a branching degree of 6, the contractile factor (g') tends to be 0.59 or more and 0.63 or less, and the branching degree is 8. In the case of a certain modified conjugated diene-based polymer, its contractile factor (g') tends to be 0.45 or more and 0.59 or less.

The modified conjugated diene polymer (A2) preferably has a branch and has a degree of branching of 5 or more. Further, the modified conjugated diene-based polymer (A2) has one or more coupling residues and a conjugated diene-based polymer chain that binds to the coupling residues, and further, the branching is 1. It is more preferable to include a branch in which 5 or more of the conjugated diene-based polymer chains are bonded to the coupling residue of the above. The structure of the modified conjugated diene polymer so that the degree of branching is 5 or more and the branching contains a branch in which 5 or more conjugated diene polymer chains are bonded to 1 coupling residue. By specifying, the contractile factor (g') can be more reliably reduced to less than 0.64. The number of conjugated diene-based polymer chains bound to one coupling residue can be confirmed from the value of the contractile factor (g').

The weight average molecular weight (Mw) of the modified conjugated diene polymer (A2) is 20 × 10 ⁴ or more and 300 × 10 ⁴ or less, preferably 50 × 10 ⁴ or more, and more preferably 64 × 10 ⁴ or more. , and still more preferably 80 × 10 ⁴ or more. Further, the weight average molecular weight is preferably not 250 × 10 ⁴ or less, more preferably 180 × 10 ⁴ or less, further preferably 0.99 × 10 ⁴ or less. When the weight-average molecular weight of 20 × 10 ⁴ or more, it is possible to achieve both low loss factor and wet performance of the tire more highly. Further, if the weight average molecular weight of 300 × 10 ⁴ or less, to improve the processability of the rubber composition.

The modified conjugated diene polymer (A2) has a molecular weight of 200 × 10 ⁴ or more and 500 × 10 ⁴ or less with respect to the total amount (100% by mass) of the modified conjugated diene polymer. (Hereinafter, also referred to as “specific high molecular weight component”) is contained in an amount of 0.25% by mass or more and 30% by mass or less. When the content of the specific high molecular weight component is 0.25% by mass or more and 30% by mass or less, low loss property of the tire and wet performance can be more highly compatible.
The modified conjugated diene polymer (A2) contains a specific high molecular weight component, preferably 1.0% by mass or more, more preferably 1.4% by mass or more, and further preferably 1.75% by mass or more. , More preferably 2.0% by mass or more, particularly preferably 2.15% by mass or more, and most preferably 2.5% by mass or more. Further, the modified conjugated diene polymer (A2) contains a specific high molecular weight component, preferably 28% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less, and even more preferably. Contains 18% by mass or less.
In the present specification, the "molecular weight" is a standard polystyrene-equivalent molecular weight obtained by GPC (gel permeation chromatography). In order to obtain a modified conjugated diene polymer (A2) in which the content of a specific high molecular weight component is in such a range, it is preferable to control the reaction conditions in the polymerization step and the reaction step. For example, in the polymerization step, the amount of the organic monolithium compound described later as a polymerization initiator may be adjusted. Further, in the polymerization step, it is preferable to use a method having a residence time distribution in both the continuous type and the batch type polymerization modes, that is, to widen the time distribution of the growth reaction.

In the modified conjugated diene polymer (A2), the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 1.6 or more and 3.0 or less. preferable. When the molecular weight distribution of the modified conjugated diene polymer (A2) is within this range, the processability of the rubber composition is good.

［上記一般式（Ｉ）中、Ｄは、共役ジエン系重合体鎖を示し、Ｒ¹、Ｒ²及びＲ³は、それぞれ独立して単結合又は炭素数１〜２０のアルキレン基を示し、Ｒ⁴及びＲ⁷は、それぞれ独立して炭素数１〜２０のアルキル基を示し、Ｒ⁵、Ｒ⁸、及びＲ⁹は、それぞれ独立して水素原子又は炭素数１〜２０のアルキル基を示し、Ｒ⁶及びＲ¹⁰は、それぞれ独立して炭素数１〜２０のアルキレン基を示し、Ｒ¹¹は、水素原子又は炭素数１〜２０のアルキル基を示し、ｍ及びｘは、それぞれ独立して１〜３の整数を示し、ｘ≦ｍであり、ｐは、１又は２を示し、ｙは、１〜３の整数を示し、ｙ≦（ｐ＋１）であり、ｚは、１又は２の整数を示し、それぞれ複数存在する場合のＤ、Ｒ¹〜Ｒ¹¹、ｍ、ｐ、ｘ、ｙ、及びｚは、それぞれ独立しており、同じであっても異なっていてもよく、ｉは、０〜６の整数を示し、ｊは、０〜６の整数を示し、ｋは、０〜６の整数を示し、（ｉ＋ｊ＋ｋ）は、３〜１０の整数であり、（（ｘ×ｉ）＋（ｙ×ｊ）＋（ｚ×ｋ））は、５〜３０の整数であり、Ａは、炭素数１〜２０の、炭化水素基、又は、酸素原子、窒素原子、ケイ素原子、硫黄原子及びリン原子からなる群より選ばれる少なくとも１種の原子を有し、かつ、活性水素を有しない有機基を示す］で表されるものであることが好ましい。この場合、タイヤに適用することで、タイヤのドライハンドリング性をより向上させることができる。
なお、Ａが示す炭化水素基は、飽和、不飽和、脂肪族、及び芳香族の炭化水素基を包含する。上記活性水素を有しない有機基としては、例えば、水酸基（−ＯＨ）、第２級アミノ基（＞ＮＨ）、第１級アミノ基（−ＮＨ₂）、スルフヒドリル基（−ＳＨ）等の活性水素を有する官能基、を有しない有機基が挙げられる。The modified conjugated diene polymer (A2) has the following general formula (I):

[In the above general formula (I), D represents a conjugated diene-based polymer chain, and R ¹ , R ² and R ³ each independently represent a single bond or an alkylene group having 1 to 20 carbon atoms, and R ⁴ and R ⁷ each independently represent an alkyl group having 1 to 20 carbon atoms, and R ⁵ , R ⁸ and R ⁹ independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. R ⁶ and R ¹⁰ each independently represent an alkylene group having 1 to 20 carbon atoms, R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and m and x each independently represent 1 Indicates an integer of ~ 3, x ≦ m, p indicates 1 or 2, y indicates an integer of 1 to 3, y ≦ (p + 1), and z indicates an integer of 1 or 2. As shown, D, R ^{1 to} R ¹¹ , m, p, x, y, and z when there are a plurality of them are independent of each other and may be the same or different, and i is 0 to 0. An integer of 6 is indicated, j is an integer of 0 to 6, k is an integer of 0 to 6, (i + j + k) is an integer of 3 to 10, and ((xxi) + (y). × j) + (z × k)) is an integer of 5 to 30, and A is a hydrocarbon group having 1 to 20 carbon atoms, or an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom, and a phosphorus atom. It has at least one atom selected from the group consisting of, and shows an organic group having no active hydrogen]. In this case, by applying it to a tire, the dry handleability of the tire can be further improved.
The hydrocarbon group indicated by A includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. Examples of the organic group having no active hydrogen include active hydrogen such as a hydroxyl group (-OH), a secondary amino group (> NH), a primary amino group (-NH ₂ ), and a sulfhydryl group (-SH). Examples include functional groups having and organic groups not having.

上記一般式（ＩＩ）中、Ｂ¹は、単結合又は炭素数１〜２０の炭化水素基を示し、ａは、１〜１０の整数を示し、複数存在する場合のＢ¹は、各々独立している。
上記一般式（ＩＩＩ）中、Ｂ²は、単結合又は炭素数１〜２０の炭化水素基を示し、Ｂ³は、炭素数１〜２０のアルキル基を示し、ａは、１〜１０の整数を示し、それぞれ複数存在する場合のＢ²及びＢ³は、各々独立している。
上記一般式（ＩＶ）中、Ｂ⁴は、単結合又は炭素数１〜２０の炭化水素基を示し、ａは、１〜１０の整数を示し、複数存在する場合のＢ⁴は、各々独立している。
上記一般式（Ｖ）中、Ｂ⁵は、単結合又は炭素数１〜２０の炭化水素基を示し、ａは、１〜１０の整数を示し、複数存在する場合のＢ⁵は、各々独立している。
なお、上記一般式（ＩＩ）〜（Ｖ）中のＢ¹、Ｂ²、Ｂ⁴、Ｂ⁵に関して、炭素数１〜２０の炭化水素基としては、炭素数１〜２０のアルキレン基等が挙げられる。Here, in the above general formula (I), A is preferably represented by any of the following general formulas (II) to (V). In this case, by applying it to a tire, the low loss property of the tire, the wear resistance, and the dry handling property can be more highly balanced.

In the above general formula (II), B ¹ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, a represents an integer of 1 to 10, and B ¹ in the case of a plurality of carbon atoms is independent of each other. ing.
In the above general formula (III), B ² represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, B ³ represents an alkyl group having 1 to 20 carbon atoms, and a is an integer of 1 to 10 carbon atoms. B ² and B ³ are independent when there are a plurality of them.
In the above general formula (IV), B ⁴ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, a represents an integer of 1 to 10, and B ⁴ in the case of a plurality of carbon atoms is independent of each other. ing.
In the above general formula (V), B ⁵ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, a represents an integer of 1 to 10, and B ⁵ in the case of a plurality of carbon atoms is independent of each other. ing.
Regarding B ¹ , B ² , B ⁴ , and B ^{5 in the} general formulas (II) to (V), examples of the hydrocarbon group having 1 to 20 carbon atoms include an alkylene group having 1 to 20 carbon atoms. Be done.

Further, preferably, in the general formula (I), A is represented by the general formula (II) or (III), and k represents 0.
More preferably, in the general formula (I), A is represented by the general formula (II) or (III), k represents 0, and in the general formula (II) or (III), a is Indicates an integer of 2 to 10.
Even more preferably, in the general formula (I), A is represented by the general formula (II), k represents 0, and in the general formula (II), a is an integer of 2 to 10. Shown.

The method for producing the modified conjugated diene polymer (A2) is not particularly limited, but an organic monolithium compound is used as a polymerization initiator, and at least the conjugated diene compound is polymerized to obtain a conjugated diene polymer. It is preferable to have a polymerization step and a reaction step of reacting a reactive compound having a pentafunctionality or higher (hereinafter, also referred to as “coupling agent”) with the active terminal of the conjugated diene polymer. As the coupling agent, it is preferable to react a reactive compound having five or more functionalities having a nitrogen atom and a silicon atom.

［上記一般式（ＶＩ）中、Ｒ¹²、Ｒ¹³及びＲ¹⁴は、それぞれ独立して単結合又は炭素数１〜２０のアルキレン基を示し、Ｒ¹⁵、Ｒ¹⁶、Ｒ¹⁷、Ｒ¹⁸及びＲ²⁰は、それぞれ独立して炭素数１〜２０のアルキル基を示し、Ｒ¹⁹及びＲ²²は、それぞれ独立して炭素数１〜２０のアルキレン基を示し、Ｒ²¹は、炭素数１〜２０の、アルキル基又はトリアルキルシリル基を示し、ｍは、１〜３の整数を示し、ｐは、１又は２を示し、Ｒ¹²〜Ｒ²²、ｍ及びｐは、複数存在する場合、それぞれ独立しており、ｉ、ｊ及びｋは、それぞれ独立して０〜６の整数を示し、但し、（ｉ＋ｊ＋ｋ）は、３〜１０の整数であり、Ａは、炭素数１〜２０の、炭化水素基、又は、酸素原子、窒素原子、ケイ素原子、硫黄原子及びリン原子からなる群から選択される少なくとも一種の原子を有し、活性水素を有しない有機基を示す］で表されるカップリング剤と反応させてなることが好ましい。この場合、タイヤに適用することで、タイヤのドライハンドリング性を更に向上させることができる。
なお、上記一般式（ＶＩ）で表されるカップリング剤と、共役ジエン系重合体とを反応させてなる変性共役ジエン系重合体は、例えば、上記一般式（Ｉ）で表される。The modified conjugated diene polymer (A2) is a conjugated diene polymer having the following general formula (VI):

[In the above general formula (VI), R ¹² , R ¹³ and R ¹⁴ each independently represent a single bond or an alkylene group having 1 to 20 carbon atoms, and are R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ and R, respectively. ²⁰ each independently represents an alkyl group having 1 to 20 carbon atoms, R ¹⁹ and R ²² each independently represent an alkylene group having 1 to 20 carbon atoms, and R ²¹ has 1 to 20 carbon atoms. , Alkyl group or trialkylsilyl group, m indicates an integer of 1 to 3, p indicates 1 or 2, R ^{12 to} R ²² , m and p are independent when there are a plurality of them. Independently, i, j and k each represent an integer of 0 to 6, where (i + j + k) is an integer of 3 to 10 and A is a hydrocarbon group having 1 to 20 carbon atoms. , Or an organic group having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom and a phosphorus atom, and having no active hydrogen]. It is preferable to react. In this case, by applying it to a tire, the dry handleability of the tire can be further improved.
The modified conjugated diene polymer obtained by reacting the coupling agent represented by the general formula (VI) with the conjugated diene polymer is represented by, for example, the general formula (I).

In the general formula (VI), A is preferably represented by any of the general formulas (II) to (V). When A is represented by any of the general formulas (II) to (V), a modified conjugated diene-based polymer (A2) having more excellent performance can be obtained.

Examples of the coupling agent represented by the above general formula (VI) include bis (3-trimethoxysilylpropyl)-[3- (2,2-dimethoxy-1-aza-2-silacyclopentane) propyl]. Amin, Tris (3-trimethoxysilylpropyl) amine, Tris (3-triethoxysilylpropyl) amine, Tris (3-trimethoxysilylpropyl)-[3- (2,2-dimethoxy-1-aza-2- Silacyclopentane) propyl] -1,3-propanediamine, tetrax [3- (2,2-dimethoxy-1-aza-2-silacyclopentane) propyl] -1,3-propanediamine, tetrax (3-tri Methoxysilylpropyl) -1,3-propanediamine, tetrakis (3-trimethoxysilylpropyl) -1,3-bisaminomethylcyclohexane, tris (3-trimethoxysilylpropyl) -methyl-1,3-propanediamine, Bis [3- (2,2-dimethoxy-1-aza-2-silacyclopentane) propyl]-(3-trismethoxysilylpropyl) -methyl-1,3-propanediamine and the like can be mentioned. Tetrax [3- (2,2-dimethoxy-1-aza-2-silacyclopentane) propyl] -1,3-propanediamine, tetrakis (3-trimethoxysilylpropyl) -1,3-propanediamine, tetrakis ( 3-Trimethoxysilylpropyl) -1,3-bisaminomethylcyclohexane is particularly preferable.

The amount of the compound represented by the general formula (VI) as the coupling agent is adjusted so that the number of moles of the conjugated diene polymer and the number of moles of the coupling agent react at a desired stoichiometric ratio. This tends to achieve the desired degree of branching. The specific number of moles of the polymerization initiator is preferably 5.0 times or more, more preferably 6.0 times or more, based on the number of moles of the coupling agent. In this case, in the general formula (VI), the number of functional groups ((m-1) × i + p × j + k) of the coupling agent is preferably an integer of 5 to 10, and more preferably an integer of 6 to 10. preferable.

The conjugated diene-based polymer is obtained by polymerizing at least a conjugated diene compound, and is obtained by copolymerizing both a conjugated diene compound and a vinyl-substituted aromatic compound, if necessary.
As the conjugated diene compound, a conjugated diene compound having 4 to 12 carbon atoms is preferable, and a conjugated diene compound having 4 to 8 carbon atoms is more preferable. Examples of such conjugated diene compounds include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, and 1,3. -Hexadiene and 1,3-heptadiene can be mentioned. Among these, 1,3-butadiene and isoprene are preferable from the viewpoint of easy industrial availability. These conjugated diene compounds may be used alone or in combination of two or more.
Further, as the vinyl-substituted aromatic compound, a monovinyl aromatic compound is preferable. Examples of the monovinyl aromatic compound include styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferable from the viewpoint of easy industrial availability. These vinyl-substituted aromatic compounds may be used alone or in combination of two or more.

The organic monolithium compound is preferably an alkyllithium compound from the viewpoint of easy industrial availability and easy control of the polymerization reaction. In this case, a conjugated diene-based polymer having an alkyl group at the polymerization initiation terminal can be obtained. Examples of the alkyllithium compound include n-butyllithium, sec-butyllithium, tert-butyllithium, and n-hexyllithium. Examples of the organic monolithium compound other than the alkyllithium compound include benzyllithium, phenyllithium, and stilbenelithium. As the alkyllithium compound, n-butyllithium and sec-butyllithium are preferable from the viewpoint of easy industrial availability and easy control of the polymerization reaction. These organic monolithium compounds may be used alone or in combination of two or more.

The amount of the bound conjugated diene in the conjugated diene polymer or the modified conjugated diene polymer (A2) is not particularly limited, but is preferably 40% by mass or more and 100% by mass or less, and 55% by mass or more and 80% by mass or more. The following is more preferable.
The amount of the bound aromatic vinyl in the conjugated diene polymer or the modified conjugated diene polymer (A2) is not particularly limited, but is preferably 0% by mass or more and 60% by mass or less, preferably 20% by mass or more. It is more preferably 45% by mass or less.
When the amount of the bonded conjugated diene and the amount of the bonded aromatic vinyl are in the above ranges, when the rubber composition is applied to a tire, low loss property, wear resistance, and dry handling property are more highly balanced. It becomes possible.
The amount of bound aromatic vinyl can be measured by the ultraviolet absorption of the phenyl group, and the amount of bound conjugated diene can also be obtained from this.

In the conjugated diene polymer or the modified conjugated diene polymer (A2), the amount of vinyl bond in the conjugated diene bonding unit is not particularly limited, but is preferably 10 mol% or more and 75 mol% or less, preferably 20 mol. More preferably, it is% or more and 65 mol% or less. When the vinyl bond amount is in the above range, when the rubber composition is applied to a tire, low loss property, wear resistance, and dry handling property can be more highly balanced.
When the modified conjugated diene polymer (A2) is a copolymer of butadiene and styrene, the Hampton method [R. R. From Hampton, Analytical Chemistry, 21,923 (1949)], the amount of vinyl bond (1,2-bond amount) in the butadiene bond unit can be determined.

In order to obtain the modified conjugated diene polymer (A2) having the specific polymer component, the molecular weight distribution (Mw / Mn) of the conjugated diene polymer is preferably 1.5 or more and 2.5 or less. It is preferably 1.8 or more and 2.2 or less. Further, in the obtained modified conjugated diene polymer (A2), it is preferable that a peak having a single peak in the molecular weight curve by GPC is detected. The peak molecular weight (Mp ₁ ) of the modified conjugated diene polymer (A2) by GPC is preferably 30 × 10 ⁴ or more and 150 × 10 ⁴ or less, and the peak molecular weight (Mp ₂ ) of the conjugated diene polymer is 20. × 10 ⁴ or more 80 × 10 ⁴ or less. Further, it is preferable that the following equation holds.
_{(Mp 1 / Mp 2) <} 1.8 × 10-12 × (Mp 2 -120 × 10 4) 2 +2
More preferably, Mp ₂ is 20 × 10 ⁴ or more and 80 × 10 ⁴ or less, and Mp ₁ is 30 × 10 ⁴ or more and 150 × 10 ⁴ or less.

The modification rate of the modified conjugated diene polymer (A2) is preferably 30% by mass or more, more preferably 50% by mass or more, and further preferably 70% by mass or more. When the modification rate is 30% by mass or more, when the rubber composition is applied to a tire, the rolling resistance can be further reduced while improving the wear resistance of the tire. The modification rate can be measured by applying the property of adsorbing the modified basic polymer component to a GPC column using a modified conjugated diene polymer as a sample and a silica gel as a filler. .. Specifically, adsorption to the silica-based column from the difference between the chromatogram of the sample and the sample solution containing the low molecular weight internal standard polystyrene measured on the polystyrene-based column and the chromatogram of the sample solution measured on the silica-based column. The amount can be measured and the modification rate can be determined.

(Styrene-alkylene block copolymer (B))
The rubber composition of the present invention contains a styrene-alkylene block copolymer (B) having a total styrene unit content of 30% by mass or more. The styrene-alkylene block copolymer (B) is a copolymer having a block derived from a styrene-based monomer and an alkylene block, and is distinguished from the above-mentioned rubber component (A) in the present invention. Here, the total content of the styrene unit of the styrene-alkylene block copolymer (B) is the total content of the blocks derived from the styrene-based monomer with respect to the total mass of the styrene-alkylene block copolymer (B). is there. The styrene / alkylene block copolymer (B) may be used alone or in combination of two or more.
If the total content of the styrene unit in the styrene-alkylene block copolymer (B) is less than 30% by mass, the elastic modulus of the tire will not be sufficiently improved when the rubber composition is applied to the tire, and at least The dry handleability of the tire cannot be sufficiently improved.

In the rubber composition of the present invention, the styrene-alkylene block copolymer (B) preferably has a total content of styrene units of 50% by mass or more. When the total content of the styrene units in the styrene-alkylene block copolymer (B) is 50% by mass or more, the dry handleability of the tire can be further improved.
The styrene / alkylene block copolymer (B) is not particularly limited, but the total content of styrene units is preferably 60% by mass or less.
In the present invention, the (total) content of the styrene unit of the styrene-alkylene block copolymer (B) and the (total) content of the alkylene unit described later are determined by the integration ratio of ¹ H-NMR.

In the rubber composition of the present invention, the styrene-alkylene block copolymer (B) preferably has a glass transition temperature (Tg) of −30 ° C. or lower. When the glass transition temperature (Tg) of the styrene / alkylene block copolymer (B) is −30 ° C. or lower, the low loss property of the tire can be further improved.

The styrene block of the styrene-alkylene block copolymer (B) has a unit derived from a styrene-based monomer (polymerized with a styrene-based monomer). Examples of such a styrene-based monomer include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene and the like. Among these, styrene is preferable as the styrene-based monomer.

The alkylene block of the styrene-alkylene block copolymer (B) has an alkylene (divalent saturated hydrocarbon group) unit. Examples of such an alkylene unit include an alkylene group having 1 to 20 carbon atoms. The alkylene unit may have a linear structure, a branched structure, or a combination thereof. Examples of the alkylene unit having a linear structure include − (CH ₂ −CH ₂ ) − unit (ethylene unit), − (CH ₂ −CH ₂ −CH ₂ −CH ₂ ) − unit (linear butylene unit), and the like. Can be mentioned. Examples of the alkylene unit of the branched structure include − [CH ₂ −CH (C ₂ H ₅ )] − unit (butylene unit) and − [CH ₂ −CH (CH ₃ )] − unit (propylene unit). Be done. Of these, the alkylene unit preferably has- [CH _2- CH (C ₂ H ₅ )]-units.

The content of the alkylene unit in the styrene / alkylene block copolymer (B) may be appropriately adjusted, and is, for example, 40 to 70% by mass with respect to the total mass of the styrene / alkylene block copolymer (B). Is preferable. Further, in the rubber composition of the present invention, the alkylene block of the styrene-alkylene block copolymer (B) is − [CH _2- CH (C ₂ H ₅ )] − unit (butylene unit) and − (CH. _{It has 2-} CH ₂ ) -units (ethylene units), and the content of the butylene units is preferably 50% by mass or more, preferably 65% by mass, based on the total mass of the butylene units and the ethylene units. The above is more preferable. The total amount is preferably 90% by mass or less, more preferably 85% by mass or less, and further preferably 80% by mass or less. When the content is 50% by mass or more, the dry handling property of the tire can be further improved, and the low loss property and the wear resistance can be further improved.

Examples of the styrene / alkylene block copolymer (B) include styrene / ethylenebutylene / styrene block copolymer (SEBS), styrene / ethylenepropylene / styrene block copolymer (SEPS), and styrene / ethyleneethylenepropylene / styrene. Examples thereof include a polymer (SEEPS), and among these, a styrene / ethylene butylene / styrene block copolymer is preferable. When the styrene / alkylene block copolymer (B) is a styrene / ethylene butylene / styrene block copolymer, the dry handleability of the tire can be further improved.
The ethylene butylene block of the styrene / ethylene butylene / styrene block copolymer is a block having the above-mentioned ethylene unit and butylene unit.

Further, the styrene / alkylene block copolymer (B) may contain other structural units other than the styrene block and the alkylene block. Examples of such other structural units include structural units having unsaturated bonds such as − [CH ₂ −CH (CH = CH ₂ )] − units.

The method for synthesizing the styrene-alkylene block copolymer (B) is not particularly limited, and a known method can be used. For example, a styrene-based monomer such as styrene is copolymerized with a conjugated diene compound such as 1,3-butadiene or an olefin such as butene to obtain a precursor copolymer, and the precursor copolymer is hydrogenated. The styrene-alkylene block copolymer (B) can be obtained. More specifically, the styrene / ethylenebutylene / styrene block copolymer (SEBS) is obtained by hydrogenating the styrene / butadiene / styrene block copolymer (SBS), and is a styrene / ethylenepropylene / styrene block copolymer. (SEPS) is obtained by hydrogenating a styrene / isoprene / styrene block copolymer (SBS).
Further, as the styrene / alkylene block copolymer (B), a commercially available product may be used. Examples of such commercially available products include JSR DYNARON (registered trademark) 8903P and 9901P of JSR Corporation.

The blending amount of the styrene-alkylene block copolymer (B) in the rubber composition of the present invention is not particularly limited and may be appropriately adjusted. For example, the blending amount of the styrene-alkylene block copolymer (B) is preferably in the range of 5 to 30 parts by mass with respect to 100 parts by mass of the rubber component (A). When the blending amount of the styrene / alkylene block copolymer (B) is 5 parts by mass or more with respect to 100 parts by mass of the rubber component (A), the elastic modulus of the tire to which the rubber composition is applied is further improved. The dry handleability of the tire can be further improved, and if it is 30 parts by mass or less, the low loss property of the tire can be further improved. From the same viewpoint, the blending amount of the styrene-alkylene block copolymer (B) is more preferably 10 parts by mass or more and more preferably 20 parts by mass or less with respect to 100 parts by mass of the rubber component (A). ..

(Silica (C))
The rubber composition of the present invention contains silica (C). When the rubber composition contains silica (C), the low loss property of the rubber composition can be improved.

The silica (C) preferably has a BET specific surface area of 40 to 350 m ² / g. In this case, the low loss property of the tire can be further improved. From the same viewpoint, the BET specific surface area of the silica (C) is more preferably 80 m ² / g or more, further preferably 220 m ² / g or more, and 300 m ² / g or less. Is more preferable, and 270 m ² / g or less is further preferable.
In the present invention, the BET specific surface area is measured according to JIS K6430.

The silica (C) preferably has a cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of 150 to 260 m ² / g. In this case, the low loss property of the tire can be further improved. From the same viewpoint, the CTAB adsorption specific surface area of the silica (C) is more preferably 176 to 206 m ² / g.
In the present invention, the specific surface area of cetyltrimethylammonium bromide (CTAB) adsorption is measured by the method described in Examples.

Examples of silica include wet silica (hydrous silicic acid), dry silica (silicic anhydride), calcium silicate, aluminum silicate, and the like, and among these, wet silica is preferable. These silicas may be used alone or in combination of two or more.

The blending amount of the silica is preferably 40 parts by mass or more, more preferably 45 parts by mass or more, preferably 120 parts by mass or less, and more preferably 70 parts by mass or less with respect to 100 parts by mass of the rubber component (A). .. When the blending amount of silica is 40 parts by mass or more with respect to 100 parts by mass of the rubber component (A), tan δ of the rubber composition at around 60 ° C. decreases, and the rolling resistance of the tire to which the rubber composition is applied is reduced. If it can be further reduced and is 120 parts by mass or less, the flexibility of the rubber composition is high, and by applying the rubber composition to the tread rubber of the tire, the deformed volume of the tread rubber becomes large and the tire becomes Wet performance can be improved.

(Fillers other than silica (C))
The rubber composition of the present invention may contain a filler other than silica (C) (hereinafter, simply referred to as "filler"). Examples of such fillers include carbon black, aluminum oxide, clay, alumina, talc, mica, kaolin, glass balloon, glass beads, calcium carbonate, magnesium carbonate, magnesium hydroxide, calcium carbonate, magnesium oxide, titanium oxide and titanium. Examples thereof include potassium acid acid and barium sulfate. These fillers may be used alone or in combination of two or more.

The carbon black is not particularly limited, and examples thereof include high, medium, or low structure carbon blacks such as SAF, ISAF, ISAF-HS, IISAF, N339, HAF, FEF, GPF, and SRF grades.

The blending amount of the filler is not particularly limited and may be appropriately adjusted. For example, it is 2 to 20 parts by mass with respect to 100 parts by mass of the rubber component (A). From the viewpoint of low loss and wear resistance, the blending amount of the filler is preferably 2 to 10 parts by mass with respect to 100 parts by mass of the rubber component (A).

(Silane Coupling Agent (D))
In addition, the rubber composition of the present invention contains a silane coupling agent (D) having a mercapto group together with silica (C) in order to improve the blending effect of the silica (C). Examples of the silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide (for example, trade name "Si69" manufactured by Ebonic), bis (3-triethoxysilylpropyl) trisulfide, and bis (3). -Triethoxysilylpropyl) disulfide (for example, trade name "Si75" manufactured by Ebonic), bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-) Trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N, N -Dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazoli Lutetrasulfide, 3-triethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis (3-diethoxymethylsilylpropyl) tetrasulfide, 3-Mercaptopropyl dimethoxymethylsilane, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, dimethoxymethylsilylpropylbenzothiazolyltetrasulfide, 3-octanoylthiopropyltriethoxysilane, 3-octanoylthio-propyltri Ethoxysilane (for example, trade name "NXT" manufactured by Momentive Performance Materials), 3- [ethoxybis (3,6,9,12,15-pentaoxaoctacosan-1-yloxy) silyl] -1 -Propylthiol (for example, trade name "Si363" manufactured by Ebonic Degussa Co., Ltd.) and the like can be mentioned, and among these, those having a mercapto group can be appropriately selected and used. These silane coupling agents (D) may be used alone or in combination of two or more.
Among these, the silane coupling agent (D) includes 3-mercaptopropyltrimethoxysilane and 3- [ethoxybis (3,6,9,12,15-pentaoxaoctacosan-1-yloxy) silyl]-. It is preferably at least one selected from 1-propanethiol. In this case, the low loss property of the tire can be further improved.

Further, the blending amount of the silane coupling agent (D) is preferably 1 part by mass or more, more preferably 4 parts by mass or more with respect to 100 parts by mass of the silica (C) from the viewpoint of improving the dispersibility of silica. Further, 20 parts by mass or less is preferable, and 12 parts by mass or less is more preferable.

(Resin (E))
The rubber composition of the present invention, further, C ₅ resins, C ₅ -C ₉ resins, C ₉ resins, terpene resins, terpene - aromatics-based resin, rosin resin, dicyclopentadiene resin and alkylphenols It is preferable to contain at least one kind of resin (E) selected from the group consisting of based resins. When the rubber composition contains the resin (E), the wet performance of the tire can be improved.

The blending amount of the resin (E) is preferably in the range of 5 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the rubber component (A). When the blending amount of the resin (E) is in this range, the wet performance of the tire can be effectively improved. From the same viewpoint, the blending amount of the resin (E) is more preferably 10 parts by mass or more and more preferably 20 parts by mass or less with respect to 100 parts by mass of the rubber component (A).

The C ₅ series resin refers to a C ₅ series synthetic petroleum resin, and means a resin obtained by polymerizing a C ₅ fraction using a Friedel-Crafts type catalyst such as AlCl ₃ or BF ₃ . Specifically, a copolymer containing isoprene, cyclopentadiene, 1,3-pentadiene, 1-pentene and the like as main components, a copolymer of 2-pentene and dicyclopentadiene, and 1,3-pentadiene as main components. Such as a polymer to be used.

Said C ₅ -C ₉ resins refers to C ₅ -C ₉ based synthetic petroleum resins, a C ₅ -C ₁₁ fraction, and polymerized using a Friedel-Crafts catalyst such as AlCl ₃ or BF ₃ to give Means the resin to be polymerized. For example, a copolymer containing styrene, vinyltoluene, α-methylstyrene, indene or the like as a main component can be mentioned. Of these, fewer C ₅ -C ₉ resins of C ₉ or more components is preferable because of excellent compatibility with the rubber component. Specifically, a resin in which the ratio of components of C ₉ or more in the C _5- C ₉ series resin is less than 50% by mass is preferable, and a resin of 40% by mass or less is more preferable.

The C _9- based resin refers to a C _9- based synthetic petroleum resin, and means a resin obtained by polymerizing a C ₉ fraction using a Friedel-Crafts type catalyst such as AlCl ₃ or BF ₃ . Examples thereof include copolymers containing indene, methylindene, α-methylstyrene, vinyltoluene and the like as main components.

The terpene resin can be obtained by blending turpentine oil obtained at the same time as obtaining rosin from a pine tree or a polymerization component separated from the turpentine oil, and polymerizing the resin using a Friedel-Crafts type catalyst. For example, β-pinene resin, α-pinene resin and the like can be mentioned.

The terpene-aromatic compound resin can be obtained by reacting terpenes with various phenols using a Friedel-Crafts type catalyst, or by further condensing with formaldehyde. For example, terpene-phenolic resin and the like can be mentioned. Among the above-mentioned terpene-phenolic resins, a resin having a phenol component of less than 50% by mass, more preferably 40% by mass or less in the terpene-phenolic resin.
The raw material terpenes are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include monoterpene hydrocarbons such as α-pinene and limonene. Among these, those containing α-pinene are preferable, and α-pinene is more preferable.

The rosin-based resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, natural resin rosins such as gum rosin, tall oil resin and wood rosin contained in raw pine tar and tall oil; modified rosin; Examples include modified rosin derivatives. Specifically, the modified rosin derivative is a polymerized rosin, a partially hydrogenated rosin thereof; a glycerin ester rosin, a partially hydrogenated rosin or a fully hydrogenated rosin; a pentaerythritol ester rosin, a partially hydrogenated rosin or a completely hydrogenated rosin thereof. And so on.

The dicyclopentadiene resin can be obtained by polymerizing dicyclopentadiene using a Friedel-Crafts type catalyst such as AlCl ₃ or BF ₃ . Specific examples of commercially available dicyclopentadiene resins include Quinton 1920 (manufactured by Zeon Corporation), Quinton 1105 (manufactured by Zeon Corporation), and Marcalets M-890A (manufactured by Maruzen Petrochemical Co., Ltd.).

The alkylphenol-based resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include alkylphenol-acetylene resins such as p-tert-butylphenol-acetylene resin and alkylphenol-formaldehyde resins having a low degree of polymerization. Can be mentioned.

The resin (E) may be partially or completely hydrogenated with unsaturated bonds in the molecule. When the intramolecular unsaturated bond of the resin (E) is partially or completely hydrogenated, the wet performance of the tire can be effectively improved. The resin (E) includes a partially or completely hydrogenated C ₅ resin, a partially or fully hydrogenated C ₅ −C ₉ resin, and a partially or completely hydrogenated resin. The added C ₉ resin is preferable. In this case, the wet performance of the tire can be effectively improved.

As the partially or completely hydrogenated resin, a commercially available product can be preferably used. Specifically, the trade names "Imarb P100", "Imarb P125", and "Imarb P125" manufactured by Idemitsu Kosan Co., Ltd. "Imarb P140", "Imarb S100", "Imarb S110", trade names "Alcon P-90", "Alcon P-100", "Alcon P-115", "Alcon P-125" manufactured by Arakawa Chemical Industry Co., Ltd. , "Alcon-P140", "Alcon M-90", "Alcon M-100", "Alcon M-115", "Alcon M-135", trade name "T-REZ OP501" manufactured by Tonen General Oil Co., Ltd. , "T-REZ PR801", "T-REZ HA125", "T-REZ HB125" and the like.

Further, in the above hydrogenation, for example, a resin having an unsaturated bond in the molecule is hydrogenated with nickel organic carboxylate, cobalt organic carboxylate, and organic metal compounds of groups 1 to 3; carbon, silica, rhodium, etc. Nickel, platinum, palladium, ruthenium, rhodium metal catalyst carried on the catalyst; it can be carried out by hydrogenating under pressurized hydrogen at 1 to 100 atm using one selected from cobalt, nickel, rhodium, ruthenium complex and the like as a catalyst.

(Other ingredients)
The rubber composition of the present invention preferably contains a vulcanizing agent in addition to the above-mentioned components. Examples of the vulcanizing agent include sulfur and the like. The blending amount of the vulcanizing agent is preferably in the range of 0.1 to 10 parts by mass and more preferably in the range of 1 to 4 parts by mass as the sulfur content with respect to 100 parts by mass of the rubber component (A). If the blending amount of the vulcanizing agent is 0.1 parts by mass or more as the sulfur content, the breaking strength and abrasion resistance of the vulcanized rubber can be secured, and if it is 10 parts by mass or less, the rubber elasticity is sufficient. Can be secured. In particular, the wet performance of the tire can be improved by setting the blending amount of the vulcanizing agent to 4 parts by mass or less as the sulfur content.

The rubber composition of the present invention preferably contains a vulcanization accelerator in addition to the above-mentioned components. The vulcanization accelerator is, for example, at least one selected from guanidines, sulfenamides, thiazoles, thiourea and diethyl thiourea. Each of these may be used alone or in combination of two or more.

The guanidines are not particularly limited and may be appropriately selected depending on the intended purpose. For example, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, dicatechol. Borate di-o-tolylguanidine salt, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, etc. Be done. Among these, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine and 1-o-tolylbiguanide are preferable, and 1,3-diphenylguanidine is more preferable in terms of high reactivity.

The sulfene amides are not particularly limited and may be appropriately selected depending on the intended purpose. For example, N-cyclohexyl-2-benzothiazolesulfenamide, N, N-dicyclohexyl-2-benzothiazolyl sulfene. Amide, N-tert-butyl-2-benzothiazolyl sulphenamide, N-oxydiethylene-2-benzothiazolyl sulphenamide, N-methyl-2-benzothiazolyl sulphenamide, N-ethyl-2- Benthiazolyl sulfene amide, N-propyl-2-benzothiazolyl sulfenamide, N-butyl-2-benzothiazolyl sulfenamide, N-pentyl-2-benzothiazolyl sulfenamide, N-hexyl- 2-benzothiazolyl sulfeneamide, N-octyl-2-benzothiazolyl sulfeneamide, N-2-ethylhexyl-2-benzothiazolyl sulfeneamide, N-decyl-2-benzothiazolyl sulfeneamide, N-dodecyl-2-benzothiazolyl sulphenamide, N-stearyl-2-benzothiazolyl sulphenamide, N, N-dimethyl-2-benzothiazolyl sulphenamide, N, N-diethyl-2-benzo Thiazolyl sulfene amide, N, N-dipropyl-2-benzothiazolyl sulfenamide, N, N-dibutyl-2-benzothiazolyl sulfenamide, N, N-dipentyl-2-benzothiazolyl sulfenamide , N, N-dihexyl-2-benzothiazolyl sulfenamide, N, N-dioctyl-2-benzothiazolyl sulfenamide, N, N-di-2-ethylhexylbenzothiazolyl sulfenamide, N, N -Didodecyl-2-benzothiazolyl sulphenamide, N, N-distearyl-2-benzothiazolyl sulphenamide and the like can be mentioned. Among these, N-cyclohexyl-2-benzothiazolyl sulphenamide and N-tert-butyl-2-benzothiazolyl sulphenamide are preferable in terms of high reactivity.

The thiazoles are not particularly limited and may be appropriately selected depending on the intended purpose. For example, 2-mercaptobenzothiazole, di-2-benzothiazolyldisulfide, 2-mercaptobenzothiazole zinc salt, 2- Cyclohexylamine salt of mercaptobenzothiazole, 2- (N, N-diethylthiocarbamoylthio) benzothiazole, 2- ( ^4' -morpholinodithio) benzothiazole, 4-methyl-2-mercaptobenzothiazole, di- (4-) Methyl-2-benzothiazolyl) disulfide, 5-chloro-2-mercaptobenzothiazole, 2-mercaptobenzothiazole sodium, 2-mercapto-6-nitrobenzothiazole, 2-mercapto-naphtho [1,2-d] thiazole, 2 -Mercapto-5-methoxybenzothiazole, 6-amino-2-mercaptobenzothiazole and the like can be mentioned. Among these, 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide are preferable in terms of high reactivity.

Thiourea is a compound represented by NH ₂ CSNH ₂ .

Diethylthiourea is a compound represented by C ₂ H ₅ NHCSNHC ₂ H ₅ .

The blending amount of the vulcanization accelerator is not particularly limited and can be appropriately adjusted according to the intended purpose. For example, it is 0.1 to 20 parts by mass with respect to 100 parts by mass of the rubber component. When it is 0.1 part by mass or more, the effect of vulcanization can be easily obtained, and when it is 20 parts by mass or less, excessive progress of vulcanization can be suppressed.

In addition to its function as a vulcanization accelerator, guanidines, sulfenamides, thiazoles, thiourea and diethylthiourea are cups of silane coupling agent for silica when kneaded with silica and silane coupling agent. It is preferable in that it can exert a function as an activator that enhances the ring function. From the same viewpoint, it is more preferable that the rubber composition of the present invention contains at least one selected from guanidines, thiazoles and thiourea.

In addition, the rubber composition of the present invention contains other compounding agents commonly used in the rubber industry, such as softeners, stearic acid, antioxidants, zinc oxide (zinc oxide), etc., which do not impair the object of the present invention. It may be appropriately selected and blended within the range. Commercially available products can be preferably used as these compounding agents.

(Preparation of rubber composition)
The method for preparing the rubber composition of the present invention is not particularly limited, and components such as a rubber component, a styrene / alkylene block copolymer, and a filler may be kneaded using a known kneading method. However, the rubber composition of the present invention contains a rubber component (A), a styrene / alkylene block copolymer (B), silica (C), a silane coupling agent (D), a vulcanization accelerator, and a vulcanization agent. With at least a kneading step A in which a rubber component (A), a styrene / alkylene block copolymer (B), a silica (C), a silane coupling agent (D), and a part or all of a vulcanization accelerator are kneaded. It is preferable to prepare by a method including the kneading step B in which the kneaded product obtained by the kneading in the kneading step A and the vulcanizing agent are kneaded after the kneading step A. Thereby, the reduction of the activity of the coupling function of the silane coupling agent can be suitably suppressed, the activity of the coupling function can be further enhanced, and a rubber composition having further excellent low loss property can be obtained.

In the kneading step A, as described above, the rubber component (A), the styrene / alkylene block copolymer (B), the silica (C), the silane coupling agent (D), a part or all of the vulcanization accelerator, and , Optionally, a filler other than silica (C) and a resin (E) are kneaded. By this kneading, a kneaded product (preliminary composition) is obtained. The kneaded product (preliminary composition) prepared in the kneading step A does not contain a vulcanizing agent.

In the kneading in the kneading step A, the maximum temperature of the mixture is preferably 120 to 190 ° C., preferably 130 to 175 ° C., from the viewpoint of more preferably enhancing the activity of the coupling function of the silane coupling agent (D). Is more preferable, and the temperature is further preferably 140 to 170 ° C.

Further, in the kneading step A, first, the rubber component (A), the styrene / alkylene block copolymer (B), the silica (C), the silane coupling agent (D), and optionally other than the silica (C) It is preferable that the filler and the resin (E) of the above are mixed and kneaded, and then a vulcanization accelerator is added thereto and further kneaded.

The kneading step B is a step of kneading the obtained kneaded product (preliminary composition) and the vulcanizing agent after the kneading step A or the kneading step C described later. By this kneading, a rubber composition can be prepared. In the kneading step B, a vulcanization accelerator may be further added.

In the kneading in the kneading step B, the maximum temperature of the mixture is preferably 60 to 140 ° C., more preferably 80 to 120 ° C., and even more preferably 100 to 120 ° C.

The above method may further include a step (kneading step C) of further kneading the kneaded product (preliminary composition) prepared in the kneading step A between the kneading step A and the kneading step B, if necessary. Good. The kneading step C may be performed a plurality of times. However, in the kneading step C, no vulcanizing agent is added.

In the kneading in the kneading step C, the maximum temperature of the mixture is preferably 120 to 190 ° C, more preferably 130 to 175 ° C, from the viewpoint of more preferably enhancing the activity of the coupling function of the silane coupling agent. It is preferably 140 to 170 ° C., particularly preferably 140 to 170 ° C.

When shifting from the kneading step A to the kneading step B, or when shifting from the optional kneading step C to the kneading step B, simply opening the inner lid (so-called "ram") of the kneader is added. The operation of releasing the vulcanization pressure and adding chemicals may be performed, but the kneaded product (preliminary composition) is taken out and the temperature of the kneaded product (preliminary composition) is adjusted to the end of kneading in the kneading step A or the kneading step C. It is more preferable to move to the kneading step B after lowering the temperature immediately after the vulcanization by 10 ° C. or more (for example, once the rubber composition is discharged from the kneader).

The kneading device used for kneading is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a single-screw kneading extruder; a multi-screw kneading extruder (continuous kneading device); a batchy mixer, an intermix , A kneader having a meshing type or non-meshing type rotary rotor such as a kneader; a roll (batch type kneading device) and the like can be mentioned. In kneading, various conditions such as rotor rotation speed, ram pressure, kneading temperature, and type of kneading device can be appropriately selected.

The rubber composition of the present invention can be used for various rubber products such as tires. In particular, the rubber composition of the present invention is suitable as a tread rubber for tires.

<Tire>
The tire of the present invention is characterized in that the above rubber composition is used for a tread rubber. Since the rubber composition of the present invention is used for the tread rubber, the tire of the present invention is excellent in dry handling while achieving both low loss resistance and wear resistance. Further, although the tire of the present invention can be used as a tire for various vehicles, it is preferable as a tire for passenger cars.

The tire of the present invention may be obtained by vulcanizing after molding using an unvulcanized rubber composition, or using a semi-vulcanized rubber that has undergone a preliminary vulcanization step or the like, depending on the type of tire to be applied. After molding, it may be obtained by further vulcanization. The tire of the present invention is preferably a pneumatic tire, and as the gas to be filled in the pneumatic tire, an inert gas such as nitrogen, argon, or helium is used in addition to normal or adjusted oxygen partial pressure. Can be used.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for the purpose of exemplifying the present invention and do not limit the present invention in any way.

<Preparation of Modified Conjugated Diene Polymer 1>
To a dry, nitrogen-substituted 800 mL pressure-resistant glass container, add 1,3-butadiene cyclohexane solution and styrene cyclohexane solution to 67.5 g of 1,3-butadiene and 7.5 g of styrene, and add 2,2. -Ditetrahydrofurylpropane 0.6 mmol is added, 0.8 mmol n-butyllithium is added, and then polymerization is carried out at 50 ° C. for 1.5 hours. At this time, 0.72 mmol of N, N-bis (trimethylsilyl) -3- [diethoxy (methyl) silyl] propylamine was added as a denaturant to the polymerization reaction system in which the polymerization conversion rate was almost 100%, and 50 The denaturation reaction was carried out at ° C. for 30 minutes. Then, 2 mL of a 5 mass% solution of 2,6-di-t-butyl-p-cresol (BHT) in isopropanol was added to stop the reaction, dried according to a conventional method, and modified conjugated diene system as the component (A). Obtain polymer 1.

<Preparation of modified conjugated diene polymer 2>
To a dry, nitrogen-substituted 800 mL pressure-resistant glass container, add 1,3-butadiene cyclohexane solution and styrene cyclohexane solution to 70.2 g of 1,3-butadiene and 39.5 g of styrene, and add 2,2. -Ditetrahydrofurylpropane 0.6 mmol was added, 0.8 mmol of n-butyllithium was added, and then polymerization was carried out at 50 ° C. for 1.5 hours. 0.72 mmol of N- (1,3-dimethylbutylidene) -3-triethoxysilyl-1-propaneamine was added as a denaturant to the polymerization reaction system in which the polymerization conversion rate was almost 100% at this time. , The denaturation reaction was carried out at 50 ° C. for 30 minutes. Then, 2 mL of a 5 mass% solution of 2,6-di-t-butyl-p-cresol (BHT) in isopropanol was added to stop the reaction, dried according to a conventional method, and modified conjugated diene system as the component (A). Polymer 2 was obtained.

<Preparation of Modified Conjugated Diene Polymer 3>
The internal volume is 10 L, the ratio (L / D) of the internal height (L) to the diameter (D) is 4.0, the reactor has an inlet at the bottom and an outlet at the top, and a tank reactor with a stirrer. A tank-type pressure vessel having a stirrer and a jacket for temperature control was used as a polymerization reactor. The water was removed in advance, and 1,3-butadiene was mixed at 17.2 g / min, styrene at 10.5 g / min, and n-hexane at 145.3 g / min. In a static mixer provided in the middle of the pipe for supplying this mixed solution to the inlet of the reactor, n-butyllithium for the residual impurity inactivation treatment was added at 0.117 mmol / min, mixed, and then added to the bottom of the reactor. Supplied continuously. Further, polymerization in which 2,2-bis (2-oxolanyl) propane as a polar substance is vigorously mixed with a stirrer at a rate of 0.019 g / min and n-butyllithium as a polymerization initiator at a rate of 0.242 mmol / min. It was supplied to the bottom of the reactor and the polymerization reaction was continued continuously. The temperature was controlled so that the temperature of the polymerization solution at the outlet of the top of the reactor was 75 ° C. When the polymerization is sufficiently stable, a small amount of the polymer solution before the addition of the coupling agent is withdrawn from the outlet at the top of the reactor, and after adding the antioxidant (BHT) to 0.2 g per 100 g of the polymer, the solvent is added. It was removed and various molecular weights were measured.
Next, 0.0302 mmol / min (0.0302 mmol / min) of tetrakis (3-trimethoxysilylpropyl) -1,3-propanediamine diluted to 2.74 mmol / L as a coupling agent was added to the polymer solution flowing out from the outlet of the reactor. The polymer solution was continuously added at a rate of (n-hexane solution containing 5.2 ppm of water), and the polymer solution to which the coupling agent was added was mixed by passing through a static mixer and the coupling reaction was carried out. At this time, the time until the coupling agent was added to the polymerization solution flowing out from the outlet of the reactor was 4.8 minutes and the temperature was 68 ° C., and the temperature in the polymerization step and the time until the coupling agent was added. The difference from the temperature was 7 ° C. Antioxidant (BHT) is continuously added to the polymer solution that has undergone the coupling reaction at 0.055 g / min (n-hexane solution) so as to be 0.2 g per 100 g of the polymer, and the coupling reaction is completed. did. At the same time as the antioxidant, oil (JOMO Process NC140 manufactured by JX Nikko Nisseki Energy Co., Ltd.) was continuously added to 100 g of the polymer so as to be 10.0 g, and mixed with a static mixer. The solvent was removed by steam stripping to obtain a modified styrene-butadiene copolymer (modified conjugated diene polymer 3) as the component (A).
When the styrene-butadiene copolymer (conjugated diene-based polymer) obtained from the polymer solution before the addition of the coupling agent was analyzed, the weight average molecular weight (Mw) was 85.2 × 10 ⁴ g / mol, and the molecular weight was 85.2 × 10 ⁴ g / mol. It was found that the ratio of 200 × 10 ⁴ or more and 500 × 10 ⁴ or less was 4.6%.
The modified styrene-butadiene copolymer has a "branching degree" of 8 (which can also be confirmed from the value of the shrinkage factor), which corresponds to the number of branches estimated from the number of functional groups and the amount of the coupling agent added. The “number of SiOR residues” corresponding to the value obtained by subtracting the number of SiORs subtracted by the reaction from the total number of SiORs contained in one molecule of the ring agent is 4.

Using the obtained modified conjugated diene polymer as a sample, the amount of bound styrene, the microstructure of the butadiene moiety, and the glass transition temperature (Tg) were analyzed by the following methods. The results are shown in Table 1.

(1) Amount of bound styrene A 100 mg sample was scalpel-up to 100 mL with chloroform and dissolved to prepare a measurement sample. The amount of bound styrene (mass%) with respect to 100% by mass of the sample was measured by the amount of ultraviolet absorption wavelength (around 254 nm) absorbed by the phenyl group of styrene (spectrophotometer "UV-2450" manufactured by Shimadzu Corporation). ..

(2) Microstructure of butadiene part (1,2-vinyl bond amount)
50 mg of the sample was dissolved in 10 mL of carbon disulfide to prepare a measurement sample. Using a solution cell, the infrared spectrum was measured in the range of 600 to 1000 cm ^-1 , and the absorbance at a predetermined wave number was used by Hampton's method (method described in RR Hampton, Analytical Chemistry 21,923 (1949)). The microstructure of the butadiene moiety, that is, the amount of 1,2-vinyl bond (mol%) was determined according to the above formula (Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation).

(3) Glass transition temperature (Tg)
In accordance with ISO 22768: 2006, a DSC curve was recorded while raising the temperature from -100 ° C to 20 ° C / min under the flow of 50 mL / min of helium using the differential scanning calorimeter "DSC3200S" manufactured by MacScience. , The peak top (Inflection point) of the DSC differential curve was defined as the glass transition temperature.

<Synthesis of silica 1>
In a 180 liter jacketed stainless steel reaction vessel equipped with a stirrer, 89 liters of water and 1.70 liters of sodium silicate aqueous solution (SiO ₂ 160 g / liter, SiO ₂ / Na ₂ O molar ratio 3.3) were placed and 75 Heated to ° C. The Na ₂ O concentration in the produced solution was 0.015 mol / liter.
While maintaining the temperature of this solution at 75 ° C., the same sodium silicate aqueous solution as described above was simultaneously added dropwise at a flow rate of 520 ml / min and sulfuric acid (18 mol / liter) at a flow rate of 23 ml / min. The neutralization reaction was carried out while adjusting the flow rate and maintaining the Na ₂ O concentration in the reaction solution in the range of 0.005 to 0.035 mol / liter. The reaction solution began to become cloudy from the middle of the reaction, and the viscosity increased at 45 minutes to become a gel-like solution. Further, the addition was continued and the reaction was stopped after 100 minutes. The silica concentration in the resulting solution was 60 g / liter. Subsequently, the same sulfuric acid as above was added until the pH of the solution reached 3, to obtain a silicic acid slurry. The obtained silicic acid slurry was filtered with a filter press and washed with water to obtain a wet cake. Next, the wet cake was made into a slurry using an emulsifying device and dried with a spray dryer to obtain silica 1.
The BET specific surface area and the CTAB adsorption specific surface area of the obtained silica 1 were measured by the following methods.

(4) Measurement of BET specific surface area Measurement was carried out in accordance with JIS K6430. As a result, the BET specific surface area of silica 1 was 245 m ² / g.

(5) Measurement of CTAB adsorption specific surface area Measurement was carried out according to the method described in ASTM D3765-92. At this time, IRB # 3 (83.0 m ² / g), which is a standard product of carbon black, is not used, and a separate standard solution of cetyltrimethylammonium bromide (hereinafter abbreviated as CE-TRAB) is prepared, thereby silica. The OT (sodium di-2-ethylhexyl sulfosuccinate) solution was standardized, and the adsorption cross-sectional area per molecule of CE-TRAB on the silica surface was set to 0.35 nm ² , and the specific surface area (m ² / g) was calculated from the adsorption amount of CE-TRAB. ) Was calculated.
As a result, the CTAB adsorption specific surface area of silica 1 was 180 m ² / g.

<Preparation and evaluation of rubber composition>
Then, according to the formulation shown in Table 2, for Comparative Example 10 and Example 2, a rubber composition was produced using a normal Bunbury mixer. For Comparative Examples 1 to 9 and Example 1, a rubber composition is produced. The green strength, viscosity, loss tangent (tan δ) and storage elastic modulus (E') of the vulcanized rubber were measured with respect to the obtained rubber composition by the following methods. For Comparative Examples 1 to 9 and Example 1, the green strength, viscosity, loss tangent (tan δ) and storage elastic modulus (E') of the vulcanized rubber are measured. The results are shown in Table 2.

(6) Green strength The unvulcanized rubber composition was subjected to a tensile test in accordance with JIS K 6251: 2010. Specifically, a sheet of a rubber composition having a thickness of 4.00 ± 0.40 mm is punched into a ring shape (JIS-5 type) to prepare a sample, and a speed of 100 ± 5 mm / min at a temperature of 40 ° C. The tensile strength of the unvulcanized rubber composition was measured by measuring the stress up to the time of breaking. The green strength was expressed in exponential notation with the tensile strength of Comparative Example 1 as 100. The larger the index value, the better the workability.

(7) Viscosity of Unvulcanized Rubber Composition The Mooney viscosity was measured at 130 ° C. using an L-type rotor in accordance with JIS K 630-1: 2001. The viscosity of the unvulcanized rubber composition of Comparative Example 1 was expressed as 100 as an exponential notation. The larger the index value, the better the workability.

(8) Storage elastic modulus (E') and loss tangent (tan δ) of vulcanized rubber
The vulcanized rubber obtained by vulcanizing the rubber composition at 145 ° C. for 33 minutes was subjected to conditions of initial strain of 2%, dynamic strain of 1%, and frequency of 52 Hz using a spectrometer manufactured by Ueshima Seisakusho Co., Ltd. The storage elastic modulus (E') at 30 ° C. and tan δ (loss tangent) at 0 ° C., 30 ° C. and 50 ° C. were measured.

<Manufacturing and evaluation of tires>
The rubber composition obtained as described above is used as a tread rubber to prepare a radial tire for a passenger car having a size of 195 / 65R15 according to a conventional method. Using the obtained rubber composition or the obtained test tire, the dry handling property, wear resistance, and rolling resistance are evaluated by the following methods. The results are shown in Table 2.

(9) Rolling resistance The test tire is rotated at a speed of 80 km / hr by a rotating drum, the rolling resistance is measured with a load of 4.82 kN, and the reciprocal of the rolling resistance of the tire of Comparative Example 1 is displayed as an index as 100. To do. The larger the index value, the lower the rolling resistance and the better the low loss property.

(10) Dry handling property For each test tire, the dry handling property is evaluated based on the feeling by the test driver in an actual vehicle test on a dry road surface, and the dry handling property of Comparative Example 1 is displayed as an index as 100. The larger the index value, the better the dry handleability of the tire.

(11) Abrasion resistance The obtained rubber composition was vulcanized at 145 ° C. for 33 minutes, and then the amount of wear was measured at 23 ° C. using a Lambourn wear tester in accordance with JIS K 6264-2: 2005. Each index is displayed with the reciprocal of the amount of wear in Comparative Example 1 as 100. The larger the index value, the smaller the amount of wear and the better the wear resistance.

(12) Comprehensive evaluation The total of the dry handleability index, the wear resistance index, and the rolling resistance index calculated as described above was calculated and comprehensively evaluated. The larger the index of the comprehensive evaluation, the better the balance between low loss property, wear resistance, and dry handling property.

* 1 Natural rubber: RSS # 3
* 2 Carbon black: SAF grade * 3 Silane coupling agent 1: 3- [ethoxybis (3,6,9,12,15-pentaoxaoctacosan-1-yloxy) silyl] -1-propanethiol, Evonik Degussa Made by the company, product name "Si363"
* 4 Silane coupling agent 2: Evonik Degussa, trade name "Si2.5", no mercapto group * 5 SEBS1: Styrene / ethylenebutylene / styrene block copolymer, JSR, trade name "DYNARON" (Registered Trademark) 8903P ”, total content of styrene units = 35% by mass, content of butylene units relative to total mass of butylene units and ethylene units = 70% by mass.
* 6 SBS1: JSR, trade name "TR2250", total content of styrene unit = 52% by mass
* 7 Wax: Microcrystalline wax, manufactured by Nippon Seiro Co., Ltd., trade name "Ozoace 0701"
* 8 Anti-aging agent 6PPD: N-Phenyl-N'-(1,3-dimethylbutyl) -p-phenylenediamine, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., trade name "Nocrack 6C"
* 9 Anti-aging agent TMQ: 2,2,4-trimethyl-1,2-dihydroquinoline polymer, manufactured by Seiko Kagaku Co., Ltd., trade name "Nonflex RD-S"
* 10 Vulcanization accelerator DPG: 1,3-diphenylguanidine, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., trade name "Noxeller D"
* 11 Vulcanization accelerator MBTS: Di-2-benzothiazolyl disulfide, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., trade name "Noxeller DM"
* 12 Vulcanization accelerator CBS: N-cyclohexyl-2-benzothiazolesulfenamide, manufactured by Sanshin Chemical Industry Co., Ltd., trade name "Sunseller CM-G"
* 13 resin: C ₅ -C ₉ resins, ExxonMobil Chemical Co., Ltd. under the trade name "ECR213"

From Table 2, it can be seen that the tires of the examples according to the present invention have a high balance between low loss property, wear resistance, and dry handling property.

According to the present invention, it is possible to provide a rubber composition capable of highly balancing the low loss property of a tire, the wear resistance, and the dry handling property.
Further, according to the present invention, it is possible to provide a tire in which low loss property, wear resistance and dry handling property are highly balanced.

Claims (9)

It contains a rubber component (A), a styrene / alkylene block copolymer (B), silica (C), and a silane coupling agent (D).
The styrene / alkylene block copolymer (B) has a total content of styrene units of 30% by mass or more.
The silane coupling agent (D) is a rubber composition having a mercapto group. The alkylene block of the styrene-alkylene block copolymer (B) has- [CH _2- CH (C ₂ H ₅ )]-units (butylene unit) and-(CH _2- CH ₂ ) -units (ethylene unit). The rubber composition according to claim 1, wherein the content of the butylene unit is 50% by mass or more with respect to the total mass of the butylene unit and the ethylene unit. The rubber composition according to claim 1 or 2, wherein the silica (C) has a BET specific surface area of 40 to 350 m ² / g. The rubber composition according to any one of claims 1 to 3, wherein the silica (C) has a cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of 150 to 260 m ² / g. Further, it is selected from the group consisting of C ₅ resin, C _{5 −} C ₉ resin, C ₉ resin, terpene resin, terpene-aromatic compound resin, rosin resin, dicyclopentadiene resin and alkylphenol resin. The rubber composition according to any one of claims 1 to 4, which comprises at least one kind of resin (E). The rubber composition according to any one of claims 1 to 5, wherein the styrene-alkylene block copolymer (B) has a total content of styrene units of 50% by mass or more. The rubber composition according to any one of claims 1 to 6, wherein the styrene / alkylene block copolymer (B) is a styrene / ethylene butylene / styrene block copolymer. The silane coupling agent (D) is 3-mercaptopropyltrimethoxysilane and 3- [ethoxybis (3,6,9,12,15-pentaoxaoctacosan-1-yloxy) silyl] -1-propanethiol. The rubber composition according to any one of claims 1 to 7, which is at least one selected from. A tire according to any one of claims 1 to 8, wherein the rubber composition is used for the tread rubber.