WO2019117266A1 - Rubber composition and tire - Google Patents

Abstract

Provided is a rubber composition which enables a tire to achieve a good balance among low loss tangent, wear resistance and dry handling properties. This rubber composition is characterized by containing (A) a rubber component, (B) a styrene-alkylene block copolymer, (C) a silica, and (D) a silane coupling agent. This rubber composition is also characterized in that: the styrene-alkylene block copolymer (B) has a total content of styrene units of 30% by mass or more; and the silane coupling agent (D) has a mercapto group.

Description

Rubber composition and tire

The present invention relates to a rubber composition and a tire.

In recent years, the demand for reducing fuel consumption of automobiles has been increasing in connection with the movement of global carbon dioxide emission regulation accompanying the growing interest in environmental issues. In order to meet such demands, reduction in 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 general to apply a rubber composition having a low loss tangent (tan δ) (hereinafter referred to as “excellent low loss property”) to a tire It has been done.

From the standpoint of improving vehicle safety, it is also important to ensure braking performance on wet road surfaces (hereinafter referred to as "wet performance"), which improves tire fuel efficiency and wet performance. It is also required. On the other hand, conventionally, a tire having both wet performance and low loss characteristics has been mainstream by using a rubber composition containing styrene-butadiene copolymer rubber (SBR) and silica. In recent years, by using a rubber composition mainly composed of natural rubber (NR) as a rubber component and containing a thermoplastic resin and a softening agent in a larger amount than in the past, the tire has further improved wet performance and low loss property. Improved tires have been proposed (Patent Documents 1 and 2 below).

International Publication No. 2015/079703 International Publication No. 2017/077712

However, according to the investigation by the present inventor, when a rubber composition mainly using natural rubber as a rubber component and containing a thermoplastic resin and a softening agent in a larger amount than conventional is used for tread rubber of a tire, the elasticity of tread rubber is obtained. The rate decreased, and it was found that there is room for improvement in the handling stability of the tire on a dry road surface (hereinafter referred to as "dry handling property"). In addition, the above rubber composition is also required to further improve the wear resistance.

Therefore, it is an object of the present invention to provide a rubber composition capable of solving the above-mentioned problems of the prior art and achieving a high balance between the low loss property of a tire, the wear resistance and the dry handling property. Do.
Another object of the present invention is to provide a tire in which the low loss property, the wear resistance and the dry handling property are highly balanced.

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

The rubber composition of the present invention comprises 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 according to the present invention is characterized in that the above rubber composition is used for tread rubber.

ADVANTAGE OF THE INVENTION According to this invention, the rubber composition which can make the low loss property of a tire, abrasion resistance, and dry handling property be highly balanced can be provided.
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.

Below, the rubber composition and tire of the present invention are illustrated in detail based on the embodiment.

<Rubber composition>
The rubber composition of the present invention comprises a rubber component (A), a styrene-alkylene block copolymer (B), a silica (C) and a silane coupling agent (D), and the above-mentioned styrene-alkylene block co-polymer 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. Further, the rubber composition of the present invention can optionally contain a filler other than silica (C), a resin (E) and other components.

In general, silane coupling agents having a mercapto group tend to deteriorate processability while having high activity. However, as a result of intensive investigations, the present inventors combined use of a styrene / alkylene block copolymer (B) containing a predetermined amount or more of styrene units with a silane coupling agent (D) having a mercapto group. It has been found that the above-mentioned deterioration can be suppressed and at the same time, low loss, dry handling and wear resistance of the tire can be made at a high level. Although the effect is not desired to be bound by theory, the styrene block in the styrene-alkylene block copolymer (B) acts like a filler in the vulcanized rubber composition. On the other hand, it is presumed that an alkylene block is 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 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), chloroprene rubber (CR) And diene rubbers 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 a natural rubber (A1), the low loss property of the tire can be further improved.
20 mass% or more is preferable, and, as for the content rate of the natural rubber (A1) in the said rubber component (A), 30 mass% or more is more preferable. If 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. Moreover, 60 mass% or less is preferable, and, as for the content rate of the natural rubber (A1) in a rubber component (A), 50 mass% or less is more preferable.

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

The content of the high Tg rubber in the rubber component (A) is preferably 20 to 50% by mass, and 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 it is applied to the tire. 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-based 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 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, branched polymers tend to be smaller in molecular size when compared to linear polymers having the same absolute molecular weight, and the shrinkage factors (g ′) are assumed to be identical. It is a measure of the ratio of the size occupied by the molecule to the linear polymer, which is an absolute molecular weight of That is, the shrinkage factor (g ') tends to decrease as the degree of branching of the polymer increases. In the present embodiment, the intrinsic viscosity is used as an index of the molecular size, and the linear polymer is used according to the relational expression of intrinsic viscosity []] = − 3.883 ^{M 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') at an absolute molecular weight of 100 × 10 ⁴ to 200 × 10 ⁴ is calculated Let it be a contraction factor (g ') of the modified conjugated diene polymer. Here, “branched” is formed by direct or indirect bonding of another polymer to one polymer. Also, the “degree of branching” is the number of polymers directly or indirectly bonded to each other for one branch. For example, the degree of branching is 5 when five conjugated diene polymer chains described later are linked to each other indirectly via a coupling residue described later. The coupling residue is a constituent unit of a modified conjugated diene polymer which is bonded to a conjugated diene polymer chain, and for example, a conjugated diene polymer to be described later is reacted with a coupling agent. Is a structural unit derived from a coupling agent. The conjugated diene polymer chain is a constituent unit of a modified conjugated diene polymer, and is derived from, for example, a conjugated diene polymer which is produced by reacting a conjugated diene polymer described later with a coupling agent. It is a structural unit.
The contraction 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, still more preferably 0. It is less than .57. The lower limit of the contraction factor (g ′) is not particularly limited, and may be below the detection limit, but is preferably 0.30 or more, more preferably 0.33 or more, and still more preferably 0. It is not less than .35 and more preferably not less than 0.45. The processability of the rubber composition is improved by using the modified conjugated diene-based polymer (A2) in which the shrinkage factor (g ′) is in this range.
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, when a modified conjugated diene polymer having a branching degree of 6 is used, the shrinkage factor (g ′) tends to be 0.59 or more and 0.63 or less, and the branching degree is 8 When a certain modified conjugated diene polymer is used, the shrinkage factor (g ′) tends to be 0.45 or more and 0.59 or less.

The modified conjugated diene-based polymer (A2) preferably has a branch and a degree of branching of 5 or more. Further, the modified conjugated diene polymer (A2) has one or more coupling residues and a conjugated diene polymer chain bonded to the coupling residues, and the above-mentioned branching is 1 It is more preferable to include a branch in which five or more of the conjugated diene-based polymer chains are connected to the coupling residue of Structure of a modified conjugated diene-based polymer such that the degree of branching is 5 or more, and the branch includes a branch in which 5 or more conjugated diene-based polymer chains are bonded to one coupling residue The contraction factor (g ′) can be more reliably made less than 0.64 by specifying The number of conjugated diene-based polymer chains bound to one coupling residue can be confirmed from the value of shrinkage 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. More preferably, it is 80 × 10 ⁴ or more. The weight average molecular weight is preferably 250 × 10 ⁴ or less, more preferably 180 × 10 ⁴ or less, and still more preferably 150 × 10 ⁴ or less. If the weight average molecular weight is 20 × 10 ⁴ or more, the low loss property and the wet performance of the tire can be more compatible. When the weight average molecular weight is 300 × 10 ⁴ or less, the processability of the rubber composition is improved.

The modified conjugated diene polymer (A2) is a modified conjugated diene polymer having a molecular weight of 200 × 10 ⁴ or more and 500 × 10 ⁴ or less based on the total amount (100% by mass) of the modified conjugated diene polymer (Hereinafter, it is also called "a specific high molecular weight component.") 0.25 mass% or more and 30 mass% or less. If the content of the specific high molecular weight component is 0.25% by mass or more and 30% by mass or less, the low loss property and the wet performance of the tire can be more compatible.
The modified conjugated diene polymer (A2) preferably contains 1.0% by mass or more, more preferably 1.4% by mass or more, and still more preferably 1.75% by mass or more of a specific high molecular weight component. Even more preferably, it contains 2.0% by mass or more, particularly preferably 2.15% by mass or more, and most preferably 2.5% by mass or more. In addition, the modified conjugated diene polymer (A2) preferably contains 28% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less of the specific high molecular weight component, and still more preferably 18 mass% or less is included.
In addition, in this specification, "molecular weight" is standard polystyrene conversion molecular weight obtained by GPC (gel permeation chromatography). In order to obtain the modified conjugated diene-based polymer (A2) in which the content of the 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 use amount of the organic monolithium compound described later as a polymerization initiator may be adjusted. In addition, in the polymerization step, in any of the continuous and batch polymerization methods, it is preferable to use a method having a residence time distribution, that is, to extend 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. If the molecular weight distribution of the modified conjugated diene-based polymer (A2) is in this range, the processability of the rubber composition will be good.

The modified conjugated diene polymer (A2) has the following general formula (I):

[In the general formula (I), D represents a conjugated diene-based polymer chain, R ¹ , R ² and R ³ each independently represent a single bond or an alkylene group having 1 to 20 carbon atoms, R ⁴ and R ⁷ each independently represent an alkyl group having 1 to 20 carbon atoms, R ⁵ , R ⁸ , and R ⁹ each 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 Represents an integer of to 3, x ≦ m, p represents 1 or 2, y represents an integer of 1 to 3, y ≦ (p + 1), z represents an integer of 1 or 2; And each of a plurality of D, R ¹ to R ¹¹ , m, p, x, y and z are independent of each other, and the same I may represent an integer of 0 to 6, j represents an integer of 0 to 6, k represents an integer of 0 to 6, and (i + j + k) represents 3 to 10). ((X × i) + (y × j) + (z × k)) is an integer of 5 to 30, and A is a hydrocarbon group having 1 to 20 carbon atoms, or Represents 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 preferable. In this case, the dry handling property of the tire can be further improved by applying the tire to the tire.
The hydrocarbon group represented by A includes saturated, unsaturated, aliphatic and aromatic hydrocarbon groups. Examples of the organic group having no active hydrogen include active hydrogens such as hydroxyl group (-OH), secondary amino group (> NH), primary amino group (-NH ₂ ) and sulfhydryl group (-SH). And an organic group having no functional group.

Here, in the general formula (I), A is preferably one represented by any one of the following general formulas (II) to (V). In this case, by applying to a tire, it is possible to balance the low loss property of the tire, the wear resistance, and the dry handling property to a higher degree.

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 when there exist a plurality of B ^{1 s} are each independently ing.
In the general formula (III), B ² represents a single bond or a hydrocarbon group having a carbon number of 1 to 20, B ³ represents an alkyl group having 1 to 20 carbon atoms, a is an integer of 1 to 10 And B ² and B ³ when there are a plurality of B ² and B ³ are each independent.
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 when there are a plurality of B ^{4 s} , each is independently ing.
In the general formula (V), B ⁵ represents a single bond or a hydrocarbon group having a carbon number of 1 ~ 20, a is an integer of 1 to 10, B ⁵ when there are a plurality, each independently ing.
As for B ¹ , B ² , B ⁴ and B ⁵ in the above 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 and the like. Be

In addition, 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 is 0, and in the general formula (II) or (III), a is , Represents an integer of 2 to 10.
Even more preferably, in the general formula (I), A is represented by the general formula (II), k is 0, and in the general formula (II), a is an integer of 2 to 10 Show.

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

The modified conjugated diene polymer (A2) is a conjugated diene polymer represented by 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 R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ and R 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 , An alkyl group or a trialkylsilyl group, m is an integer of 1 to 3, p is 1 or 2, and R ¹² to R ²² , m and p are each independently independent of each other, And i, j and k each independently represent an integer of 0 to 6, provided that (i + j + k) is an integer of 3 to 10, and A is a hydrocarbon group having 1 to 20 carbon atoms Or at least one selected from the group consisting of oxygen atom, nitrogen atom, silicon atom, sulfur atom and phosphorus atom Also has a kind of atoms, it is preferably formed by reacting a coupling agent represented by an organic group having no active hydrogen. In this case, the dry handling property of the tire can be further improved by applying to a tire.
The modified conjugated diene-based polymer obtained by reacting the coupling agent represented by the general formula (VI) with the conjugated diene-based polymer is represented by, for example, the general formula (I).

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

As the coupling agent represented by the above general formula (VI), for example, bis (3-trimethoxysilylpropyl)-[3- (2,2-dimethoxy-1-aza-2-silacyclopentane) propyl] Amine, tris (3-trimethoxysilylpropyl) amine, tris (3-triethoxysilylpropyl) amine, tris (3-trimethoxysilylpropyl)-[3- (2,2-dimethoxy-1-aza-2-) Silacyclopentane) propyl] -1,3-propanediamine, tetrakis [3- (2,2-dimethoxy-1-aza-2-silacyclopentane) propyl] -1,3-propanediamine, tetrakis (3-triamine) Methoxysilylpropyl) -1,3-propanediamine, tetrakis (3-trimethoxysilylpropyl) -1,3-bisamino Ethylcyclohexane, Tris (3-trimethoxysilylpropyl) -methyl-1,3-propanediamine, bis [3- (2,2-dimethoxy-1-aza-2-silacyclopentane) propyl]-(3-tris Methoxysilylpropyl) -methyl-1,3-propanediamine and the like can be mentioned, and among these tetrakis [3- (2,2-dimethoxy-1-aza-2-silacyclopentane) propyl] -1,3- Propanediamine, tetrakis (3-trimethoxysilylpropyl) -1,3-propanediamine, tetrakis (3-trimethoxysilylpropyl) -1,3-bisaminomethylcyclohexane are particularly preferred.

The addition 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 to the number of moles of the coupling agent can be reacted at a desired stoichiometric ratio. Can tend to achieve the desired degree of branching. The specific number of moles of the polymerization initiator is preferably 5.0 or more moles, more preferably 6.0 or more moles, with respect to the number of moles of the coupling agent. In this case, in the general formula (VI), the number of functional groups of the coupling agent ((m-1) × i + p × j + k) is preferably an integer of 5 to 10, more preferably 6 to 10 preferable.

The conjugated diene 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.
The conjugated diene compound is preferably a conjugated diene compound having 4 to 12 carbon atoms, and more preferably a conjugated diene compound having 4 to 8 carbon atoms. As such conjugated diene compounds, for example, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3 Hexadiene and 1,3-heptadiene. Among these, 1,3-butadiene and isoprene are preferable from the viewpoint of industrial availability. These conjugated diene compounds may be used alone or in combination of two or more.
Moreover, as said 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 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 industrial availability and easiness of control of polymerization reaction. In this case, a conjugated diene polymer having an alkyl group at the polymerization initiation end is obtained. Examples of the alkyllithium compound include n-butyllithium, sec-butyllithium, tert-butyllithium and n-hexyllithium. In addition, as an organic monolithium compound other than the alkyllithium compound, benzyllithium, phenyllithium, and stilbene lithium can be mentioned. As the alkyllithium compound, n-butyllithium and sec-butyllithium are preferable from the viewpoint of industrial availability and easiness of control of the polymerization reaction. These organic monolithium compounds may be used alone or in combination of two or more.

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

In the above conjugated diene polymer or modified conjugated diene polymer (A2), the amount of vinyl bond in the conjugated diene bond unit is not particularly limited, but it is preferably 10 mol% or more and 75 mol% or less, and 20 mol % Or more and 65 mol% or less is more preferable. When the rubber composition is applied to the tire as the amount of vinyl bond is in the above range, it is possible to further balance low loss, wear resistance, and dry handling with a high degree.
When the modified conjugated diene polymer (A2) is a copolymer of butadiene and styrene, the method of Hampton [R. R. Hampton, Analytical Chemistry, 21, 923 (1949)] can be used to determine the amount of vinyl bonds (1, 2-bonds) in butadiene bonding units.

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, or more. Preferably, it is set to 1.8 or more and 2.2 or less. Moreover, it is preferable that the modified conjugated diene polymer (A2) to be obtained is a polymer whose molecular weight curve by GPC has a peak 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 and 80 × 10 ⁴ or less is preferable. Moreover, it is preferable that the following formula is established.
_{(Mp 1 / Mp 2) <} 1.8 × 10-12 × (Mp 2 -120 × 10 4) 2 +2
Mp ₂ is more preferably 20 × 10 ⁴ or more and 80 × 10 ⁴ or less, and Mp ₁ is more preferably 30 × 10 ⁴ or more and 150 × 10 ⁴ or less.

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

(Styrene · Alkylene Block Copolymer (B))
The rubber composition of the present invention comprises a styrene-alkylene block copolymer (B) having a total content of styrene units of 30% by mass or more. The styrene-alkylene block copolymer (B) is a copolymer having a block derived from a styrenic monomer and an alkylene block, and in the present invention, it is distinguished from the rubber component (A) described above. Here, the total content of styrene units in the styrene-alkylene block copolymer (B) is the total content of blocks derived from styrenic monomers relative to the total mass of the styrene-alkylene block copolymer (B). is there. A styrene alkylene block copolymer (B) may be used individually by 1 type, and may be used in combination of 2 or more type.
When the total content of styrene units in the styrene-alkylene block copolymer (B) is less than 30% by mass, the modulus of elasticity of the tire does not sufficiently improve when the rubber composition is applied to the tire, and at least The dry handling properties of the tire can not 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 styrene units in the styrene-alkylene block copolymer (B) is 50% by mass or more, the dry handling properties 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 an integral 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 less. When the glass transition temperature (Tg) of the styrene / alkylene block copolymer (B) is −30 ° C. or less, 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 styrenic monomer (polymerized styrenic monomer). Examples of such styrenic monomers include styrene, α-methylstyrene, p-methylstyrene, vinyl toluene and the like. Among these, styrene is preferable as the styrene-based monomer.

The alkylene block of the said styrene-alkylene block copolymer (B) has an alkylene (divalent saturated hydrocarbon group) unit. As such an alkylene unit, for example, an alkylene group having 1 to 20 carbon atoms can be mentioned. The alkylene unit may be a linear structure, a branched structure, or a combination thereof. As the alkylene unit having a linear structure, for example,-(CH ₂ -CH ₂ ) -unit (ethylene unit),-(CH ₂ -CH ₂ -CH ₂ -CH ₂ ) -unit (linear butylene unit), etc. It can be mentioned. Examples of the alkylene unit having a branched structure include, for example,-[CH ₂ -CH (C ₂ H ₅ )]-unit (butylene unit),-[CH ₂ -CH (CH ₃ )]-unit (propylene unit), etc. Be Among these, it is preferable to have an — [CH ₂ —CH (C ₂ H ₅ )] — unit as the alkylene unit.

The content of the alkylene unit in the above-mentioned styrene / alkylene block copolymer (B) may be suitably adjusted, but for example, it is 40 to 70% by mass with respect to the total mass of the styrene / alkylene block copolymer (B) Is preferred. 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),-(CH 2) ₂ -CH ₂₎ - and a unit (ethylene units), the content of the butylene units, preferably has a total weight less than 50 wt% with respect to the oxybutylene units and the ethylene units, 65 wt% It is more preferable that it is more than. The total amount is preferably 90% by mass or less, more preferably 85% by mass or less, and still more preferably 80% by mass or less. When the content is 50% by mass or more, the low loss property and the wear resistance can be further improved while further improving the dry handling property of the tire.

Examples of the styrene / alkylene block copolymer (B) include styrene / ethylene butylene / styrene block copolymer (SEBS), styrene / ethylene propylene / styrene block copolymer (SEPS), styrene / ethylene / ethylene / styrene copolymer A polymer (SEEPS) etc. are mentioned, 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 handling properties of the tire can be further improved.
In addition, the ethylene butylene block of the said styrene ethylene butylene styrene block copolymer is a block which has the ethylene unit and the butylene unit which were mentioned above.

Moreover, the said styrene alkylene block copolymer (B) may contain the other structural units other than the said styrene block and an alkylene block. As such other structural units, for example, structural units having unsaturated bonds such as — [CH ₂ —CH (CH (CH ₂ )] — units and the like can be mentioned.

The synthesis method of the styrene / alkylene block copolymer (B) is not particularly limited, and known methods can be used. For example, a precursor copolymer is obtained by copolymerizing a styrene-based monomer such as styrene and a conjugated diene compound such as 1,3-butadiene or an olefin such as butene, and hydrogenating this precursor copolymer Thus, a styrene-alkylene block copolymer (B) can be obtained. More specifically, styrene / ethylene butylene / styrene block copolymer (SEBS) is obtained by hydrogenation of styrene / butadiene / styrene block copolymer (SBS), and styrene / ethylene propylene / styrene block copolymer (SEPS) is obtained by hydrogenation of styrene isoprene styrene block copolymer (SBS).
Moreover, you may use a commercial item as said styrene alkylene block copolymer (B). Examples of such commercial products include JSR DYNARON (registered trademark) 8903P, 9901P, etc. manufactured by 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). If 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 handling property 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 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, still more preferably 220 m ² / g or more, and 300 m ² / g or less. it is more preferable, and more preferably not more than 270m ² / g.
In the present invention, the BET specific surface area is measured in accordance with 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, cetyltrimethylammonium bromide (CTAB) adsorption specific surface area is measured by the method described in the examples.

Examples of the silica include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), 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.

40 mass parts or more are preferable with respect to 100 mass parts of said rubber components (A), as for the compounding quantity of the said silica, 45 mass parts or more are more preferable, and 120 mass parts or less are preferable, and 70 mass parts or less are more preferable . When the compounding amount of silica is 40 parts by mass or more with respect to 100 parts by mass of the rubber component (A), tan δ at around 60 ° C. of the rubber composition decreases, and the rolling resistance of the tire to which the rubber composition is applied Furthermore, if it 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 deformation volume of the tread rubber becomes large, and the tire Wet performance can be improved.

(Filler 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"). Such fillers include, for example, carbon black, aluminum oxide, clay, alumina, talc, mica, kaolin, glass balloon, glass beads, calcium carbonate, magnesium carbonate, magnesium hydroxide, calcium carbonate, magnesium oxide, magnesium oxide, titanium oxide, titanium Acid potassium, barium sulfate and the like. These fillers may be used alone or in combination of two or more.

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

The compounding amount of the above-mentioned filler is not particularly limited and may be appropriately adjusted, and is, for example, 2 to 20 parts by mass with respect to 100 parts by mass of the rubber component (A). The compounding amount of the filler is preferably 2 to 10 parts by mass with respect to 100 parts by mass of the rubber component (A) from the viewpoint of low loss and abrasion resistance.

(Silane coupling agent (D))
Further, the rubber composition of the present invention contains a silane coupling agent (D) having a mercapto group together with the silica (C) in order to improve the blending effect of the silica (C). As a silane coupling agent, for example, bis (3-triethoxysilylpropyl) tetrasulfide (for example, trade name “Si69” manufactured by Evonik Co., Ltd., etc.), bis (3-triethoxysilylpropyl) trisulfide, bis (3 -Triethoxysilylpropyl) disulfide (for example, trade name "Si75" manufactured by Evonik Co., Ltd.), bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2- Trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N, N -The Tylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl Tetrasulfide, 3-triethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis (3-diethoxymethylsilylpropyl) tetrasulfide, 3 -Mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, dimethoxymethylsilylpropiyl Benzothiazolyl tetrasulfide, 3-octanoylthiopropyltriethoxysilane, 3-octanoylthio-propyltriethoxysilane (eg, trade name “NXT” manufactured by Momentive Performance Materials, Inc.), 3- [ethoxybis ( 3,6,9,12,15-pentaoxaoctacosan-1-yloxy) silyl] -1-propanethiol (eg, trade name "Si 363" manufactured by Evonik Degussa, etc.) and the like. Therefore, 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 above-mentioned silane coupling agent (D) is 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.

The amount of the silane coupling agent (D) is preferably 1 part by mass or more, more preferably 4 parts by mass or more, based on 100 parts by mass of the silica (C), from the viewpoint of improving the dispersibility of the silica. Moreover, 20 mass parts or less are preferable, and 12 mass parts or less are 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 include at least one resin (E) selected from the group consisting of a system resin. When the rubber composition contains a resin (E), the wet performance of the tire can be improved.

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

The C ₅ resin refers to C ₅ type synthetic petroleum resins and C ₅ fraction, it means a resin obtained by polymerization using a Friedel-Crafts catalyst such as AlCl ₃ or BF _3. Specifically, copolymers containing isoprene, cyclopentadiene, 1,3-pentadiene and 1-pentene as main components, copolymers of 2-pentene and dicyclopentadiene, and 1,3-pentadiene as main components. Polymers and the like.

The C ₅ -C ₉ resin refers to a C ₅ -C ₉ synthetic petroleum resin and is obtained by polymerizing a C ₅ -C ₁₁ fraction using a Friedel-Crafts-type catalyst such as AlCl ₃ or BF ₃ Mean a resin that For example, copolymers having styrene, vinyl toluene, α-methylstyrene, indene or the like as a main component can be mentioned. Among these, a C ₅ -C ₉ based resin containing few components of C ₉ or more is preferable because of its excellent compatibility with the rubber component. Specifically, a resin in which the proportion of the C ₉ or more component in the C ₅ -C ₉ resin is less than 50% by mass is preferable, and the resin in which the proportion is 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 . For example, copolymers having as main components indene, methyl indene, α-methyl styrene, vinyl toluene and the like can be mentioned.

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

The terpene-aromatic 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-phenol resin and the like can be mentioned. Among the terpene-phenol resins, resins in which the phenol component in the terpene-phenol resin is less than 50% by mass are preferable, and resins having 40% by mass or less are more preferable.
The terpene as a raw material is not particularly limited and may be appropriately selected according to the 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 according to the purpose. For example, natural resin rosins such as gum rosin, tall oil resin, wood rosin and the like contained in raw pine jani and tall oil; modified rosin; And modified rosin derivatives. Specifically, the modified rosin derivative is, for example, polymerized rosin, partially hydrogenated rosin thereof, glycerin ester rosin, partially hydrogenated rosin or fully hydrogenated rosin thereof, pentaerythritol ester rosin, partially hydrogenated rosin or partially hydrogenated rosin Etc.

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 products of dicyclopentadiene resin include Quinton 1920 (manufactured by Nippon Zeon Co., Ltd.), Quinton 1105 (manufactured by Nippon Zeon Co., Ltd.), and Marcarets M-890A (manufactured by Maruzen Petrochemical Co., Ltd.).

There is no restriction | limiting in particular as said alkyl phenol-type resin, According to the objective, it can select suitably, For example, alkyl phenol acetylene resin, such as p-tert- butylphenol- acetylene resin, the alkyl phenol formaldehyde resin of low polymerization degree, etc. It can be mentioned.

In the resin (E), unsaturated bonds in the molecule may be partially or completely hydrogenated. When the unsaturated bonds in the molecule of the resin (E) are partially or completely hydrogenated, the wet performance of the tire can be effectively improved. In addition, as the resin (E), a partially or completely hydrogenated C ₅ resin, a partially or completely hydrogenated C ₅ -C ₉ resin, a partially or completely hydrogen Preferred is a C ₉ -based resin added. In this case, the wet performance of the tire can be effectively improved.

As the partially or completely hydrogenated resin, commercially available products can be suitably used. Specifically, Idemarco Co., Ltd. trade name "I-Merb P100", "I-Merb P125", " Aimab P140, Aimab S100, Aimab S110, trade name "Arcone P-90" manufactured by Arakawa Chemical Industries, Ltd., Arkone P-100, Arkone P-115, Arkone P-125 , "Alcon-P140", "Arcon M-90", "Arcon M-100", "Alcon M-115", "Alcon M-135", trade name "T-REZ OP501" manufactured by Tonen General Petroleum Co., Ltd. , "T-REZ PR801", "T-REZ HA125", "T-REZ HB125" and the like.

The hydrogenation may be carried out, for example, by using a resin having unsaturated bond in the molecule, a hydrogenation catalyst comprising nickel of organic carboxylic acid, cobalt of organic carboxylic acid, organic metal compound of groups 1 to 3; carbon, silica, diatomaceous earth, etc. The hydrogenation can be carried out under a hydrogen pressure of 1 to 100 atm using a catalyst selected from nickel, platinum, palladium, ruthenium, rhodium metal catalyst, cobalt, nickel, rhodium, ruthenium complex and the like supported thereon.

(Other ingredients)
The rubber composition of the present invention preferably contains a vulcanizing agent in addition to the components described above. Sulfur etc. are mentioned as this vulcanizing agent. The amount of the vulcanizing agent is preferably in the range of 0.1 to 10 parts by mass as sulfur, and more preferably in the range of 1 to 4 parts by mass with respect to 100 parts by mass of the rubber component (A). If the compounding amount of the vulcanizing agent is 0.1 parts by mass or more as sulfur content, the fracture strength, abrasion resistance and the like of the vulcanized rubber can be secured, and if it is 10 parts by mass or less, sufficient rubber elasticity can be obtained. 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 sulfur content.

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

The guanidines are not particularly limited and can be appropriately selected according to the purpose. For example, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, dicatechol Di-o-tolyl guanidine salt of borate, 1,3-di-o-cumenyl guanidine, 1,3-di-o-biphenyl guanidine, 1,3-di-o-cumenyl 2-propionyl guanidine and the like Be Among these, 1,3-diphenylguanidine, 1,3-di-o-tolyl guanidine and 1-o-tolylbiguanide are preferable in view of high reactivity, and 1,3-diphenyl guanidine is more preferable.

The sulfenamides are not particularly limited and may be appropriately selected depending on the purpose. For example, N-cyclohexyl-2-benzothiazolesulfenamide, N, N-dicyclohexyl-2-benzothiazolylsulfene Amide, N-tert-butyl-2-benzothiazolylsulfenamide, N-oxydiethylene-2-benzothiazolylsulfenamide, N-methyl-2-benzothiazolylsulfenamide, N-ethyl-2- Benzothiazolylsulfenamide, N-propyl-2-benzothiazolylsulfenamide, N-butyl-2-benzothiazolylsulfenamide, N-pentyl-2-benzothiazolylsulfenamide, N-hexyl- 2-benzothiazolylsulfenamide, N-octyl-2-benzothia Lylsulfenamide, N-2-ethylhexyl-2-benzothiazolylsulfenamide, N-decyl-2-benzothiazolylsulfenamide, N-dodecyl-2-benzothiazolylsulfenamide, N-stearyl- 2-benzothiazolylsulfenamide, N, N-dimethyl-2-benzothiazolylsulfenamide, N, N-diethyl-2-benzothiazolylsulfenamide, N, N-dipropyl-2-benzothiazole Rusulfenamide, N, N-dibutyl-2-benzothiazolylsulfenamide, N, N-dipentyl-2-benzothiazolylsulfenamide, N, N-dihexyl-2-benzothiazolylsulfenamide, N , N-dioctyl-2-benzothiazolylsulfenamide, N, N-di-2-ethyl Sill benzothiazolyl sulfenamide, N, N- didodecyl-2-benzothiazolyl sulfenamide, N, etc. N- distearyl-2-benzothiazolyl sulfenamide and the like. Among these, N-cyclohexyl-2-benzothiazolylsulfenamide and N-tert-butyl-2-benzothiazolylsulfenamide are preferable in terms of high reactivity.

The thiazoles are not particularly limited and may be appropriately selected depending on the purpose. For example, 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, zinc salt of 2-mercaptobenzothiazole, 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-methoxyben Thiazole, such as 6-amino-2-mercaptobenzothiazole and the like. 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 .

Diethyl thiourea is a compound represented by _{C 2 H 5 NHCSNHC 2 H 5} .

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

In addition to guanidines, sulfenamides, thiazoles, thiourea and diethylthiourea, in addition to their functions as vulcanization accelerators, when they are mixed with silica and a silane coupling agent, a cup of the silane coupling agent relative to silica is used. It is preferable at the point which can exhibit the function as an activator which improves a ring function. From the same point of view, the rubber composition of the present invention more preferably contains at least one selected from guanidines, thiazoles and thioureas.

In the rubber composition of the present invention, other additives commonly used in the rubber industry, such as softeners, stearic acid, anti-aging agents, zinc oxide (zinc white), etc. do not impair the object of the present invention You may select suitably and mix within the range. A commercial item can be used suitably 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 comprises a rubber component (A), a styrene-alkylene block copolymer (B), silica (C), a silane coupling agent (D), a vulcanization accelerator, and a vulcanizing agent. Kneading step A in which at least part or all of rubber component (A), styrene / alkylene block copolymer (B), silica (C), silane coupling agent (D) and vulcanization accelerator are kneaded After the kneading step A, it is preferable to prepare by a method including the kneading step B in which the kneaded material obtained by the kneading in the kneading step A and the vulcanizing agent are kneaded. Thereby, the activity reduction 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 further excellent in 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, fillers other than silica (C), resin (E) are kneaded. A kneaded material (preliminary composition) is obtained by this kneading. The kneaded material (preliminary composition) prepared in the kneading step A does not contain a vulcanizing agent.

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 enhancing the activity of the coupling function of the silane coupling agent (D) more suitably. Is more preferable, and the temperature is preferably 140 to 170.degree.

In addition, 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 to mix | blend and knead | fill the filler of this, resin (E), add a vulcanization accelerator to this, and knead | mix further.

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. The rubber composition can be prepared by this kneading. In the kneading step B, a vulcanization accelerator may be further added.

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

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

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 suitably enhancing the activity of the coupling function of the silane coupling agent. Preferably, the temperature is 140 to 170 ° C.

In addition, when moving from the kneading step A to the kneading step B, or when moving from the optional kneading step C to the kneading step B, simply by opening the inner lid (so-called "lam") of the kneader The operation of releasing the vulcanization pressure and adding a chemical may be performed, but the kneaded material (preliminary composition) is taken out, and the temperature of the kneaded material (preliminary composition) is completed at the kneading stage A or the kneading stage C. It is more preferable to shift to the kneading step B after lowering the temperature immediately after the addition by 10 ° C. or more (for example, the operation of once discharging the rubber composition from the kneader).

The kneading apparatus used for the kneading is not particularly limited and may be appropriately selected according to the purpose. For example, a single-screw kneading extruder; a multi-screw kneading extruder (continuous kneader); Banbury mixer, intermix Kneaders having a meshing or non-meshing type rotary rotor such as a kneader; rolls (batch-type kneading apparatus) and the like. Various conditions such as the rotational speed of the rotor, the ram pressure, the kneading temperature, the type of the kneading apparatus, and the like in the kneading can be appropriately selected.

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

<Tire>
The tire according to the present invention is characterized in that the above rubber composition is used for tread rubber. In the tire according to the present invention, since the above rubber composition is used for the tread rubber, the dry handling property is excellent while achieving both the low loss property and the wear resistance. Moreover, although the tire of this invention can be utilized 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 molding and curing after molding using an unvulcanized rubber composition according to the type of tire to be applied, or by using a semi-vulcanized rubber which has undergone a pre-vulcanization process and the like. After molding, it may be obtained by further vulcanization. The tire according to the present invention is preferably a pneumatic tire, and as a gas to be filled in the pneumatic tire, in addition to normal air having a controlled partial pressure of oxygen, an inert gas such as nitrogen, argon, or helium can be used. It can be used.

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples. However, these examples are intended to illustrate the present invention and do not limit the present invention at all.

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

<Preparation of Modified Conjugated Diene-Based Polymer 2>
Add a cyclohexane solution of 1,3-butadiene and a cyclohexane solution of styrene to 70.2 g of 1,3-butadiene and 39.5 g of styrene in an 800 mL pressure-resistant glass container which has been dried and replaced with nitrogen. 0.6 mmol of ditetrahydrofurylpropane was added, and 0.8 mmol of n-butyllithium was added, followed by polymerization at 50 ° C. for 1.5 hours. 0.72 mmol of N- (1,3-dimethylbutylidene) -3-triethoxysilyl-1-propanamine as a modifier is added to the polymerization reaction system in which the polymerization conversion ratio at this time is almost 100%. The denaturation reaction was carried out at 50 ° C. for 30 minutes. Then, 2 mL of a 5% by mass solution of 2,6-di-t-butyl-p-cresol (BHT) in isopropanol is added to stop the reaction, and the reaction is dried according to a conventional method to obtain a modified conjugated diene system as component (A). Polymer 2 was obtained.

<Preparation of Modified Conjugated Diene-Based 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 inlet is at the bottom, the outlet is at the top, and the tank reactor with stirrer is A tank-type pressure vessel having a stirrer and a jacket for temperature control was used as a polymerization reactor. 17.2 g / min of 1,3-butadiene, 10.5 g / min of styrene, and 145.3 g / min of n-hexane were mixed under the condition of water previously removed. At the bottom of the reactor, after adding and mixing n-butyllithium for residual impurity inactivation treatment at 0.117 mmol / min with a static mixer provided in the middle of the piping that supplies this mixed solution to the inlet of the reactor. It supplied continuously. Furthermore, the polymerization is carried out with a stirrer vigorously mixing 2,2-bis (2-oxolanyl) propane as a polar substance 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 fed to the bottom of the reactor to continue the polymerization reaction continuously. The temperature was controlled so that the temperature of the polymerization solution at the top of the reactor was 75 ° C. When polymerization is sufficiently stabilized, a small amount of the polymer solution before addition of the coupling agent is withdrawn from the top outlet of the reactor, and after adding the antioxidant (BHT) to 0.2 g per 100 g of the polymer, the solvent is added It removed and measured various molecular weights.
Next, 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 to which the coupling agent was added was continuously added by passing through a static mixer at a rate of n-hexane solution (water containing 5.2 ppm), and the coupling reaction was carried out. At this time, the time until the coupling agent is added to the polymerization solution flowing out from the outlet of the reactor is 4.8 minutes and the temperature is 68 ° C., and the temperature in the polymerization step and the addition of the coupling agent are The difference from the temperature was 7 ° C. Antioxidant (BHT) is continuously added at 0.055 g / min (n-hexane solution) to a concentration of 0.2 g per 100 g of the polymer to the polymer solution subjected to the coupling reaction to complete the coupling reaction. did. At the same time as the antioxidant, 10.0 g of oil (JX Nippon Oil & Energy JOMO Process NC 140) was continuously added to 100 g of the polymer, 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).
The styrene-butadiene copolymer (conjugated diene polymer) obtained from the polymer solution before addition of the coupling agent was analyzed and found to have a weight average molecular weight (Mw) of 85.2 × 10 ⁴ g / mol, and the molecular weight It was found that the ratio of 200 × 10 ⁴ or more and 500 × 10 ⁴ or less was 4.6%.
In the above modified styrene-butadiene copolymer, the “degree of branching” corresponding to the number of branches assumed from the number of functional groups of the coupling agent and the addition amount is 8 (can also be confirmed from the value of shrinkage factor) The “number of SiOR residues” corresponding to a value obtained by subtracting the number of SiORs reduced by the reaction from the total number of SiORs contained in one ring agent molecule is 4.

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

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

(2) Microstructure of butadiene moiety (1,2-vinyl bond content)
50 mg of a sample was dissolved in 10 mL of carbon disulfide to obtain a measurement sample. Using the solution cell, the infrared spectrum is measured in the range of 600 to 1000 cm ^-1 , and the method of Hampton according to the absorbance at a predetermined wave number (the method described in R. R. Hampton, Analytical Chemistry 21, 923 (1949)) The microstructure of the butadiene portion, that is, the amount of 1,2-vinyl bond (mol%) was determined according to the calculation formula of (Fourier Transform Infrared Spectrophotometer “FT-IR230” manufactured by JASCO Corporation).

(3) Glass transition temperature (Tg)
According to ISO 22768: 2006, using a differential scanning calorimeter “DSC3200S” manufactured by Mac Science, under the flow of helium 50 mL / min, record the DSC curve while raising the temperature from −100 ° C. to 20 ° C./min. The peak point (Inflection point) of the DSC differential curve was taken as the glass transition temperature.

<Synthesis of Silica 1>
180 liter jacketed stainless reactor equipped with a stirrer, water 89 liters and an aqueous sodium silicate solution (SiO ₂ 160 g / l, SiO ₂ / Na ₂ O molar ratio 3.3) was placed 1.70 liters, 75 Heated to ° C. The Na ₂ O concentration in the resulting solution was 0.015 mol / liter.
While maintaining the temperature of this solution at 75 ° C., the same sodium silicate aqueous solution as above was added dropwise at a flow rate of 520 ml / min and sulfuric acid (18 mol / l) at a flow rate of 23 ml / min. While adjusting the flow rate, the neutralization reaction was carried out while maintaining the Na ₂ O concentration in the reaction solution in the range of 0.005 to 0.035 mol / liter. During the reaction, the reaction solution became cloudy, and the viscosity increased at 45 minutes to form a gel-like solution. Furthermore, the addition was continued and the reaction was stopped in 100 minutes. The concentration of silica 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 siliceous slurry. The obtained silica slurry was filtered by a filter press and washed with water to obtain a wet cake. The wet cake was then dried as a slurry using an emulsifying apparatus 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 method.

(4) Measurement of BET Specific Surface Area Measurement was performed 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 performed according to the method described in ASTM D3765-92. At this time, a standard solution of cetyltrimethylammonium bromide (hereinafter abbreviated as CE-TRAB) was prepared separately without using IRB # 3 (83.0 m ² / g), which is a standard product of carbon black, and silica was thereby obtained. The OT (sodium di-2-ethylhexylsulfosuccinate) solution is standardized, and the adsorption cross section per molecule of CE-TRAB on the silica surface is 0.35 nm ^{2 and} the adsorption amount of CE-TRAB is based on the specific surface area (m ² / g ) 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>
Subsequently, according to the compounding prescription shown in Table 2, the rubber composition was manufactured about Comparative Example 10 and Example 2 using the normal Banbury mixer. For Comparative Examples 1-9 and Example 1, a rubber composition is produced. The green strength, the viscosity, and the loss tangent (tan δ) and the storage elastic modulus (E ′) of the vulcanized rubber were measured for the obtained rubber composition by the following method. For Comparative Examples 1 to 9 and Example 1, the green strength, viscosity, and 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 A tensile test was conducted on the unvulcanized rubber composition 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, and the stress was measured until the time of breakage. Assuming that the tensile strength of Comparative Example 1 is 100, the green strength is indicated as an index. The larger the index value, the better the processability.

(7) Viscosity of Unvulcanized Rubber Composition Mooney viscosity was measured at 130 ° C. using an L-shaped rotor in accordance with JIS K 6300-1: 2001. The viscosity of the unvulcanized rubber composition of Comparative Example 1 was indexed as 100. The larger the index value, the better the processability.

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

<Production and evaluation of tires>
Using the rubber composition obtained as described above for tread rubber, a radial tire for passenger car of size: 195 / 65R15 is produced according to a conventional method. Dry handling property, abrasion resistance, and rolling resistance are evaluated by the following method using the obtained rubber composition or the obtained test tire. 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 load is 4.82 kN, the rolling resistance is measured, and the reciprocal of the rolling resistance of the comparative example 1 is indexed as 100. Do. The larger the index value, the lower the rolling resistance and the better the low loss property.

(10) Dry Handling Property The dry handling property of each test tire 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 of 100. The larger the index value, the better the dry handling properties of the tire.

(11) Wear resistance After vulcanizing the obtained rubber composition at 145 ° C. for 33 minutes, the amount of wear is measured at 23 ° C. according to JIS K 6264-2: 2005, using a Lambourn abrasion tester, The inverse number of the amount of wear of Comparative Example 1 is set to 100, and is displayed as an index. The larger the index value, the smaller the amount of wear and the better the wear resistance.

(12) Comprehensive Evaluation The evaluation was performed comprehensively by calculating the sum of the dry handling index, the wear resistance index, and the rolling resistance index calculated as described above. The larger the index of the comprehensive evaluation, the better the balance between low loss, wear resistance, and dry handling.

* 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 Company name, "Si 363"
* 4 Silane coupling agent 2: manufactured by Evonik Degussa, trade name "Si 2.5", not having mercapto group * 5 SEBS 1: styrene, ethylene butylene, styrene block copolymer, manufactured by JSR, trade name "DYNARON" (Registered trademark) 8903P ", total content of styrene units = 35% by mass, content of butylene units to total mass of butylene units and ethylene units = 70% by mass
* 6 SBS1: JSR Corporation, trade name "TR2250", total content of styrene unit = 52% by mass
* 7 Wax: Micro crystal wax, manufactured by Nippon Seiwa Co., Ltd., trade name "Ozo Ace 0701"
* 8 Anti-aging agent 6PPD: N-phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine, manufactured by Ouchi Emerging Chemical Industry Co., Ltd., trade name "NOCLAK 6C"
* 9 Anti-aging agent TMQ: 2,2,4-trimethyl-1,2-dihydroquinoline polymer, manufactured by SEIKO CHEMICAL CO., LTD., Trade name "Nonflex RD-S"
* 10 Vulcanization accelerator DPG: 1,3-diphenyl guanidine, manufactured by Ouchi Shinko Chemical Co., Ltd., trade name "Noxceler D"
* 11 Vulcanization accelerator MBTS: di-2-benzothiazolyl disulfide, manufactured by Ouchi Emerging Chemical Industry Co., Ltd., trade name "Noxceler 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 resin manufactured by ExxonMobil Chemical Company, trade name "ECR 213"

From Table 2, it can be seen that the tire of the example according to the present invention is highly balanced between low loss, abrasion resistance and dry handling.

ADVANTAGE OF THE INVENTION According to this invention, the rubber composition which can make the low loss property of a tire, abrasion resistance, and dry handling property be highly balanced can be provided.
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)

1. 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 rubber composition characterized in that the silane coupling agent (D) has a mercapto group.
2. The alkylene block of the styrene-alkylene block copolymer (B) comprises-[CH ₂ -CH (C ₂ H ₅ )]-units (butylene units) and-(CH ₂ -CH ₂ )-units (ethylene units) The rubber composition according to claim 1, wherein the content of the butylene unit is 50% by mass or more based on the total mass of the butylene unit and the ethylene unit.
3. 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.
4. 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.
5. Furthermore, C ₅ resins, C ₅ -C ₉ resins, C ₉ resins, terpene resins, terpene - selected aromatic compound resin, rosin resin, from the group consisting of dicyclopentadiene resin and alkylphenol resin The rubber composition according to any one of claims 1 to 4, which comprises at least one resin (E).
6. 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.
7. 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.
8. 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
9. A tire comprising the rubber composition according to any one of claims 1 to 8 as a tread rubber.