WO2012144541A1 - Rubber composition for tires and pneumatic tire - Google Patents

Abstract

Provided are: a rubber composition for tires, which is capable of improving fuel consumption saving, wet grip performance, dry grip performance, wear resistance and processability; and a pneumatic tire which uses the rubber composition for tires. The present invention relates to a rubber composition for tires, which contains a diene polymer and silica. The diene polymer is a modified diene polymer that is obtained by reacting the substance (A) and the substance (B) described below. When a particle of silica having three or more particles adjacent thereto is considered as a branch particle (X), the silica has an average length (L₁) between branch particles X-X including the branch particles Xs of 30-400 nm. (A) an active conjugated diene polymer having an alkali metal end, said active conjugated diene polymer being obtained by polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer in the presence of the substance (C) described below (B) a modifying agent having a functional group (C) a chemical species which is obtained by reacting a compound represented by formula (1) with an organic alkali metal compound

Description

Rubber composition for tire and pneumatic tire

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

In recent years, interest in environmental issues has increased, and there has been a strong demand for lower fuel consumption for automobiles, and a reduction in rolling resistance (lower fuel consumption) is also required for rubber compositions used in automobile tires. ing.

However, in general, a rubber composition that has reduced rolling resistance by reducing stress and hysteresis loss when the tire is low stretched (low strain) during low-speed driving or the like is used when the tire is highly stretched during sudden braking ( Stress and hysteresis loss were reduced even during high strain), and dry grip performance tended to decrease. Therefore, it has been difficult to achieve both reduction in rolling resistance and improvement in dry grip performance.

As a method for satisfying the reduction in fuel consumption in the rubber composition, a method for reducing the content of the reinforcing filler is known. However, since the hardness of the rubber composition is lowered, the tire is softened, and there is a problem that steering stability, wet grip performance, and wear resistance are lowered.

As another method of satisfying the reduction in fuel consumption in a rubber composition, a method of replacing carbon black with silica is known. However, it is known that a rubber composition blended with silica tends to have a low dry grip performance, and when traveling, the rubber stiffness decreases and the dry grip performance tends to further decrease. Silica has a hydrophilic silanol group on its surface, so it has a lower affinity with rubber (especially natural rubber, butadiene rubber, styrene butadiene rubber, etc. often used for tires) and wear resistance than carbon black. There was a tendency to be inferior in terms of property and mechanical strength (tensile strength and elongation at break).

Patent Document 1 discloses a rubber composition containing specific silica (linear silica) and capable of improving wet grip performance and dry grip performance while maintaining low fuel consumption. However, there is room for improvement in terms of improving fuel economy, wet grip performance, dry grip performance, wear resistance, and workability.

JP 2007-154158 A

The present invention provides a rubber composition for a tire that solves the above-described problems and can improve fuel economy, wet grip performance, dry grip performance, wear resistance, and processability, and a pneumatic tire using the same. Objective.

The present invention includes a diene polymer and silica,
The diene polymer is a modified diene polymer obtained by reacting the following (A) and (B):
When the silica has three or more particles adjacent to one particle as the branched particle X, the average length L ₁ between the branched particles XX including the branched particle X is 30 to 400 nm. The present invention relates to a tire rubber composition.
(A): an active conjugated diene polymer having an alkali metal end obtained by polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer in the presence of (C) below (B): functional group Modifier (C) having: a chemical species obtained by reacting a compound represented by the following formula (1) with an organic alkali metal compound

(In Formula (1), R ¹ and R ² are the same or different and are a hydrogen atom, a branched or unbranched alkyl group, a branched or unbranched aryl group, a branched or unbranched alkoxy group, branched or unbranched. A silyloxy group, a branched or unbranched acetal group, a carboxyl group, a mercapto group, or a derivative thereof, A represents a branched or unbranched alkylene group, a branched or unbranched arylene group, or a derivative thereof.

The present invention also relates to a tire rubber composition obtained by kneading a modified diene polymer obtained by reacting the above (A) and (B) with silica sol.

It is preferable that the compound represented by the above formula (1) is a compound represented by the following formula (2).

The modifying agent is preferably a compound represented by the following formula (3).

(In Formula (3), R ³ and R ⁴ are the same or different and each represents a hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group is selected from the group consisting of ethers and tertiary amines. R ⁵ and R ⁶ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, the hydrocarbon group being an ether, and 3 It may have at least one group selected from the group consisting of a tertiary amine, R ⁷ represents a hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group is an ether, a tertiary amine, an epoxy And at least one group selected from the group consisting of carbonyl, and halogen, n represents an integer of 1 to 6.)

It is preferable that the modifiers introduced at both ends of the active conjugated diene polymer are the same.

The content of the diene polymer in 100% by mass of the rubber component is preferably 5% by mass or more.

The conjugated diene monomer is preferably 1,3-butadiene and / or isoprene, and the aromatic vinyl monomer is preferably styrene.

The modified diene polymer is preferably a modified styrene butadiene rubber obtained by polymerizing 1,3-butadiene and styrene.

The silica preferably has an average aspect ratio L ₁ / D of 3 to 100 between the branched particles XX including the branched particles X when the average primary particle diameter is D.

The tire rubber composition preferably contains 5 to 150 parts by mass of the silica with respect to 100 parts by mass of the rubber component.

The tire rubber composition is preferably used as a tread rubber composition.

The present invention also relates to a pneumatic tire using the rubber composition.

According to the present invention, since it is a tire rubber composition containing a specific modified diene polymer and a specific silica, low fuel consumption, wet grip performance, dry grip performance, wear resistance, workability Can be improved. Further, according to the present invention, since it is a tire rubber composition obtained by kneading a specific modified diene polymer and silica sol, low fuel consumption, wet grip performance, dry grip performance, abrasion resistance And processability can be improved. Therefore, the pneumatic tire excellent in the above-mentioned performance can be provided by using these rubber compositions for each member of the tire such as a tread.

3 is a schematic diagram of a branched particle X. FIG. Outline of average primary particle diameter of silica, average length of XX between branched particles including branched particle X (L ₁ ), and average length of XX between branched particles not including branched particle X (L ₂ ) It is a schematic diagram.

The rubber composition for tires of the present invention includes a diene polymer and silica, and the diene polymer is obtained by reacting the following (A) and (B) with a modified diene polymer (hereinafter referred to as “diene polymer”). , Also referred to as a modified diene polymer), and when the above-mentioned silica has three or more particles adjacent to one particle as the branched particle X, the inter-branched particle XX including the branched particle X The average length L ₁ is 30 to 400 nm (structure silica (linear silica)).
(A): an active conjugated diene polymer having an alkali metal end obtained by polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer in the presence of (C) below (B): functional group Modifier (C) having: a chemical species obtained by reacting a compound represented by the following formula (1) with an organic alkali metal compound

(In Formula (1), R ¹ and R ² are the same or different and are a hydrogen atom, a branched or unbranched alkyl group, a branched or unbranched aryl group, a branched or unbranched alkoxy group, branched or unbranched. A silyloxy group, a branched or unbranched acetal group, a carboxyl group, a mercapto group, or a derivative thereof, A represents a branched or unbranched alkylene group, a branched or unbranched arylene group, or a derivative thereof.

In order to perform the polymerization reaction using the chemical species (C) obtained by reacting the compound represented by the above formula (1) and the organic alkali metal compound as a polymerization initiator, the polymer chain obtained by the polymerization reaction (above (A) (Active conjugated diene polymer)) has both ends as living polymer ends. Therefore, both ends of the active conjugated diene polymer (A) can be modified with the modifier (B), and the modified diene polymer obtained by modifying both ends of (A) with the above (B) Compared with the case where only one end is modified, excellent fuel economy, wet grip performance, dry grip performance, and wear resistance can be obtained, and these performances can be improved in a well-balanced manner.

On the other hand, as a method for introducing functional groups (modifying groups) at both ends, a method in which polymerization is performed using a polymerization initiator having a functional group, and a modifier is further reacted at the polymerization ends can be considered. In this case, the functional group of the polymerization initiator is present at one end, and the functional group due to the modifier is present at the other end. However, since the functional group of the polymerization initiator generally has a weak interaction with silica, the balance between low fuel consumption, wet grip performance, dry grip performance, and wear resistance is poor. Moreover, since the functional group which a polymerization initiator has is easy to detach | leave, it becomes a cause of an increase in energy loss and is inferior to low fuel consumption. Furthermore, when the polarity of the functional group possessed by the polymerization initiator is high, it can coordinate to the end of the living polymer to affect the reaction between the polymerization end and the modifier, and any functional group can be introduced to the end of the polymerization. Can not.

On the other hand, since (A) is obtained by using (C) as a polymerization initiator, the polymer chain extends in two directions by the polymerization reaction, and there are two living polymer terminals. A functional group can be introduced. Therefore, by blending the modified diene polymer obtained by reacting the above (A) and (B), rubber excellent in fuel economy, wet grip performance, dry grip performance, and wear resistance balance performance A composition is obtained.

Also, by blending the above structure silica, the occluder rubber (rubber which is encapsulated in the silica aggregate and cannot be distorted) produced by the aggregation of the silica particles is reduced, and the local stress concentration, that is, the local Distortion is reduced. Thereby, the hysteresis loss at the time of the low expansion | extension of a tire (at the time of low distortion) can be reduced, and rolling resistance can be reduced. Furthermore, the structure silica is oriented in the tread circumferential direction of the tire when the tire is highly stretched (during high strain) such as during sudden braking or sharp turning. As a result, the rubber in the vicinity of the structure silica is abruptly distorted and the hysteresis loss is increased, thereby improving the dry grip performance.

And the improvement effect of each can be synergistically enhanced by the combined use of the modified diene polymer and the structure silica. In general, when a modified rubber is used, the processability may be lowered. However, in the present invention, the processability can be improved by using the modified diene polymer in combination with the structure silica. These effects can synergistically improve fuel efficiency, wet grip performance, dry grip performance, wear resistance, and workability.

The rubber composition containing the structure silica of the present invention can be produced, for example, by kneading the modified diene polymer and silica sol.

In the present invention, the diene polymer is a modified diene polymer obtained by reacting (A) and (B).

(A) is an active conjugated diene polymer having an alkali metal end obtained by polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer in the presence of (C). The active conjugated diene polymer has two alkali metal terminals.

(C) is a chemical species obtained by reacting a compound represented by the following formula (1) with an organic alkali metal compound.

(R ¹ and R ² are the same or different and each represents a hydrogen atom, a branched or unbranched alkyl group, a branched or unbranched aryl group, a branched or unbranched alkoxy group, a branched or unbranched silyloxy group, branched or Represents an unbranched acetal group, carboxyl group (—COOH), mercapto group (—SH) or a derivative thereof, and A represents a branched or unbranched alkylene group, a branched or unbranched arylene group or a derivative thereof. .)

Examples of the branched or unbranched alkyl group for R ¹ and R ² include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, iso-butyl group, sec-butyl group, tert- 1 to 30 carbon atoms such as butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group, etc. (preferably 1 to 8 carbon atoms, more preferably 1 to 3 carbon atoms) 4, more preferably an alkyl group having 1 to 2 carbon atoms. The alkyl group includes a group in which a hydrogen atom of the alkyl group is substituted with an aryl group (such as a phenyl group).

Examples of the branched or unbranched aryl group for R ¹ and R ² include those having 6 to 18 carbon atoms (preferably 6 to 8 carbon atoms) such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a biphenyl group. An aryl group is mentioned. The aryl group includes a group in which a hydrogen atom of the aryl group is substituted with an alkyl group (such as a methyl group).

Examples of the branched or unbranched alkoxy group for R ¹ and R ² include 1 to 8 carbon atoms such as a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, and a t-butoxy group. And an alkoxy group (preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms). The alkoxy group includes a cycloalkoxy group (such as a cycloalkoxy group having 5 to 8 carbon atoms such as a cyclohexyloxy group), an aryloxy group (an aryloxy group having 6 to 8 carbon atoms such as a phenoxy group and a benzyloxy group), etc. ) Is also included.

Examples of the branched or unbranched silyloxy group of R ¹ and R ² include, for example, a silyloxy group substituted with an aliphatic group or aromatic group having 1 to 20 carbon atoms (trimethylsilyloxy group, triethylsilyloxy group, triisopropylsilyl group). Oxy group, diethylisopropylsilyloxy group, t-butyldimethylsilyloxy group, t-butyldiphenylsilyloxy group, tribenzylsilyloxy group, triphenylsilyloxy group, tri-p-xylylsilyloxy group, etc.) Can be mentioned.

Examples of the branched or unbranched acetal group of R ¹ and R ² include groups represented by —C (RR ′) — OR ″ and —O—C (RR ′) — OR ″. . Examples of the former include a methoxymethyl group, an ethoxymethyl group, a propoxymethyl group, a butoxymethyl group, an isopropoxymethyl group, a t-butoxymethyl group, and a neopentyloxymethyl group. The latter includes a methoxymethoxy group, an ethoxy group, and the like. A methoxy group, propoxymethoxy group, i-propoxymethoxy group, n-butoxymethoxy group, t-butoxymethoxy group, n-pentyloxymethoxy group, n-hexyloxymethoxy group, cyclopentyloxymethoxy group, cyclohexyloxymethoxy group, etc. Can be mentioned.

R ¹ and R ² are preferably a hydrogen atom, a branched or unbranched alkyl group, or a branched or unbranched aryl group. This can improve the balance of fuel efficiency, wet grip performance, dry grip performance, and wear resistance. Moreover, it is preferable that R ¹ and R ² are the same group because the polymer can be grown uniformly in two directions.

Examples of the branched or unbranched alkylene group of A include, for example, a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, an undecylene group, and a dodecylene group. And an alkylene group having 1 to 30 carbon atoms (preferably 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms) such as a group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group and octadecylene group. .

Examples of the derivative of the alkylene group of A include an alkylene group substituted with an aryl group or an arylene group.

As said arylene group of A, a phenylene group, a tolylene group, a xylylene group, a naphthylene group etc. are mentioned, for example.

Examples of the derivative of the arylene group of A include an arylene group substituted with an alkylene group.

As A, a branched or unbranched arylene group is preferable, and a phenylene group (a compound represented by the following formula (2)) is more preferable. This can improve the balance of fuel efficiency, wet grip performance, dry grip performance, and wear resistance.

^{R 1} and ^{R 2} in the formula (2) are the same as ^{R 1} and ^{R 2} in the formula (1).

Specific examples of the compound represented by the above formula (1) or (2) include 1,2-divinylbenzene, 1,3-divinylbenzene, 1,4-divinylbenzene, 1,2-diisopropenylbenzene, 1,3-diisopropenylbenzene, 1,4-diisopropenylbenzene, 1,2-diisobutenylbenzene, 1,3-diisobutenylbenzene, 1,4-diisobutenylbenzene, 1,3-phenylenebis (1 -Vinylbenzene), 1,4-phenylenebis (1-vinylbenzene), 1,1'-methylenebis (2-vinylbenzene), 1,1'-methylenebis (3-vinylbenzene), 1,1'-methylenebis (4-vinylbenzene) and the like. These may be used alone or in combination of two or more. Of these, 1,3-divinylbenzene, 1,3-diisopropenylbenzene, and 1,3-phenylenebis (1-vinylbenzene) are preferable.

Examples of the organic alkali metal compound used in the present invention include hydrocarbon compounds containing an alkali metal such as lithium, sodium, potassium, rubidium, and cesium. Of these, lithium or sodium compounds having 2 to 20 carbon atoms are preferred. Specific examples thereof include, for example, ethyl lithium, n-propyl lithium, iso-propyl lithium, n-butyl lithium, sec-butyl lithium, t-octyl lithium, n-decyl lithium, phenyl lithium, 2-naphthyl lithium, 2 -Butyl-phenyllithium, 4-phenyl-butyllithium, cyclohexyllithium, 4-cyclopentyllithium, 1,4-dilithio-butene-2 and the like. Among these, n-butyllithium or sec-butyllithium is preferable in that the reaction proceeds rapidly to give a polymer having a narrow molecular weight distribution.

The method for preparing (C) is not particularly limited as long as it is a method in which the compound represented by the above formula (1) is brought into contact with the organic alkali metal compound. Specifically, the compound represented by the formula (1) and the organic alkali metal compound are separately dissolved in an organic solvent inert to the reaction, for example, a hydrocarbon solvent, and represented by the formula (1). (C) can be prepared by dropping the organic alkali metal compound solution into the compound solution with stirring. The reaction temperature for preparing (C) is preferably 40 to 60 ° C.

The hydrocarbon solvent does not deactivate the organic alkali metal compound (alkali metal catalyst), and the suitable hydrocarbon solvent is selected from aliphatic hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons. In particular, propane having 2 to 12 carbon atoms, n-butane, iso-butane, n-pentane, iso-pentane, n-hexane, cyclohexane, propene, 1-butene, iso-butene, trans-2-butene, Examples thereof include cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, and ethylbenzene. Moreover, these solvents can be used in mixture of 2 or more types.

Examples of the conjugated diene monomer used in the present invention include 1,3-butadiene, isoprene, 1,3-pentadiene (piperine), 2,3-dimethyl-1,3-butadiene, 1,3-hexadiene and the like. Of these, 1,3-butadiene and isoprene are preferred from the viewpoint of the physical properties of the resulting polymer and the availability for industrial implementation.

Examples of the aromatic vinyl monomer used in the present invention include styrene, α-methylstyrene, vinyl toluene, vinyl naphthalene, divinyl benzene, trivinyl benzene, divinyl naphthalene and the like. Of these, styrene is preferred from the viewpoint of the physical properties of the polymer obtained and the availability for industrial implementation.

As the monomer, only a conjugated diene monomer may be used, or a conjugated diene monomer and an aromatic vinyl monomer may be used in combination. When the conjugated diene monomer and the aromatic vinyl monomer are used in combination, the ratio by mass of the conjugated diene monomer / aromatic vinyl monomer is preferably 50/50 to 90/10, more preferably 55/45 to 85/15. It is. If the ratio is less than 50/50, the polymer rubber becomes insoluble in the hydrocarbon solvent, and uniform polymerization may not be possible. On the other hand, if the ratio exceeds 90/10, the strength of the polymer rubber may be reduced. May decrease.

The modified diene polymer is preferably obtained by copolymerizing a conjugated diene monomer and an aromatic vinyl monomer, and is obtained by copolymerizing 1,3-butadiene and styrene (modified styrene butadiene rubber). Is particularly preferred. When such a modified copolymer is used, fuel economy, wet grip performance, dry grip performance, and wear resistance can be improved. Moreover, low-fuel-consumption property, wet grip performance, dry grip performance, abrasion resistance, and workability can be suitably improved by using together with the structure silica.

There is no restriction | limiting in particular as a preparation method of (A) except using (C) as a polymerization initiator, A conventionally well-known method can be used. Specifically, a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer are optionally used in a reaction inert organic solvent such as a hydrocarbon solvent, using (C) as a polymerization initiator. By polymerizing in the presence of a mizer, an active conjugated diene-based polymer having two target alkali metal ends can be obtained.

As a hydrocarbon solvent, the thing similar to the case of the preparation of said (C) can be used conveniently.

The randomizer is a microstructure control of a conjugated diene moiety in a polymer, for example, an increase in 1,2-bonds in butadiene, a 3,4-bond in isoprene, or a control of the composition distribution of monomer units in the polymer. It is a compound having an action such as randomization of butadiene units and styrene units in a butadiene-styrene copolymer.

Various compounds can be used as a randomizer. Of these, ether compounds or tertiary amines are preferred from the viewpoint of industrial availability. Examples of ether compounds include cyclic ethers such as tetrahydrofuran, tetrahydropyran, and 1,4-dioxane; aliphatic monoethers such as diethyl ether and dibutyl ether; ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol diethyl ether, Examples thereof include aliphatic ethers such as diethylene glycol dibutyl ether; aromatic ethers such as diphenyl ether and anisole. Examples of tertiary amine compounds include triethylamine, tripropylamine, tributylamine, N, N, N ′, N′-tetramethylethylenediamine, N, N-diethylaniline, pyridine, quinoline, etc. Can give.

(B) is a modifier having a functional group. (B) is preferably a compound having a functional group containing at least one atom selected from the group consisting of nitrogen, oxygen and silicon.
Examples of functional groups include amino groups, amide groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups (especially epoxy groups), carbonyl groups, carboxyl groups, hydroxyl groups, nitrile groups, pyridyls. Group, diglycidylamino group and the like. These functional groups may have a substituent. Of these, amino groups, alkoxysilyl groups, ether groups (particularly epoxy groups), carbonyl groups, hydroxyl groups, carboxyl groups, and diglycidylamino groups are preferred because of their high reactivity with silica.

(B) is preferably a compound represented by the following formula (3). Moreover, it is preferable that (B) to be used is one type (the modifiers introduced at both ends of (A) are the same). By using only one type of (B), the same functional group can be introduced at both ends of (A), and the reactivity with silica is stabilized by forming uniform polymer ends.

The compound represented by the following formula (3) is a polyfunctional compound having two or more epoxy groups. A hydroxyl group can be introduced into the polymer chain by reacting the active terminal of the active conjugated diene polymer (A) with an epoxy group. Furthermore, since the polyfunctional compound has two or more epoxy groups in the molecule, one polyfunctional compound reacts with the active terminal of a plurality of active conjugated diene polymers (A), so that two or more The polymer chains can be coupled. Therefore, a modified diene polymer having three or more sites (terminals and the like) modified with the polyfunctional compound can also be obtained. By increasing the number of modified sites (terminals, etc.) of the modified diene polymer, the balance between fuel efficiency, wet grip performance, dry grip performance, and wear resistance can be improved.

(In Formula (3), R ³ and R ⁴ are the same or different and each represents a hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group is selected from the group consisting of ethers and tertiary amines. R ⁵ and R ⁶ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, the hydrocarbon group being an ether, and 3 It may have at least one group selected from the group consisting of a tertiary amine, R ⁷ represents a hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group is an ether, a tertiary amine, an epoxy And at least one group selected from the group consisting of carbonyl, and halogen, n represents an integer of 1 to 6.)

R ³ and R ⁴ are preferably an alkylene group having 1 to 10 carbon atoms (preferably having 1 to 3 carbon atoms). R ⁵ and R ⁶ are preferably a hydrogen atom. R ⁷ is a hydrocarbon group having 3 to 20 carbon atoms (preferably 6 to 10 carbon atoms, more preferably 8 carbon atoms), and is a cycloalkyl group, cycloalkylene group, cycloalkane represented by the following formula or the like. A triyl group is preferable, and a cycloalkylene group is more preferable.

N is preferably 2 to 3. Examples of the compound represented by the above formula (3) include tetraglycidylmetaxylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, tetraglycidyl-1,3-bisaminomethyl. Cyclohexane or the like is preferably used.

In the present invention, the diene polymer (modified diene polymer) is obtained by reacting (A) and (B) in an organic solvent inert to the reaction, such as a hydrocarbon solvent.

As a hydrocarbon solvent, the thing similar to the case of the preparation of said (C) can be used conveniently.

The amount of the modifier (B) having a functional group is preferably 0.1 to 10 mol, more preferably 0.5 to 2 mol, relative to 1 mol of the organic alkali metal compound. When the amount is less than 0.1 mol, the effect of improving the fuel efficiency is small. Conversely, when the amount exceeds 10 mol, (B) remains in the polymerization solvent. This is economically undesirable because it requires a separation step.

Since the reaction between (A) and (B) occurs rapidly, the reaction temperature and reaction time can be selected in a wide range. In general, the temperature is from room temperature (25) to 80 ° C. for several seconds to several hours. The reaction may be performed by bringing (A) and (B) into contact. For example, a method of polymerizing a diene polymer using (C) and adding a predetermined amount of (B) to the polymer solution. However, it can be exemplified as a preferred embodiment, but is not limited to this method.

From the viewpoint of kneadability, _a coupling agent represented by the general formula R _a MX _b may be added before or after the reaction of (A) and (B) (wherein R is an alkyl group, an alkenyl group, A cycloalkenyl group or an aromatic hydrocarbon group, M is a silicon or tin atom, X is a halogen atom, a is an integer of 0 to 2, and b is an integer of 2 to 4. The amount of the coupling agent is preferably 0.03 to 0.4 mol, more preferably 0.05 to 0.3 mol, per mol of the organic alkali metal compound (alkali metal catalyst) used. When the amount used is less than 0.03, the effect of improving the workability is small. Conversely, when the amount exceeds 0.4 mol, the alkali metal terminal reacting with the modifier having a functional group is reduced, and the fuel efficiency is improved. The effect is reduced.

After completion of the reaction, the modified diene polymer can be coagulated by a coagulation method used in the production of rubber by ordinary solution polymerization such as addition of a coagulant or steam coagulation, and can be separated from the reaction solvent. The solidification temperature is not limited at all.

A diene polymer (modified diene polymer) is obtained by drying the coagulated product separated from the reaction solvent. For drying the coagulated product, a band drier, an extrusion drier, etc. used in normal synthetic rubber production can be used, and the drying temperature is not limited at all.

The Mooney viscosity (ML _{1 + 4} ) (100 ° C.) of the diene polymer is preferably 10 to 200, more preferably 20 to 150. The upper limit is more preferably 100 or less, and particularly preferably 75 or less. When the Mooney viscosity is less than 10, mechanical properties such as the tensile strength of the vulcanizate may be reduced. On the other hand, when the viscosity exceeds 200, the miscibility is poor when used in combination with other rubbers. Processing operability may deteriorate, and the mechanical properties of the resulting vulcanizate of the rubber composition may deteriorate. The Mooney viscosity can be measured by the method described in the examples.

The vinyl content of the conjugated diene part of the diene polymer is not particularly limited, but is preferably 10 to 70 mol%, more preferably 15 to 60 mol%. The lower limit is more preferably 35 mol% or more, particularly preferably 40 mol% or more, and most preferably 50 mol% or more. If it is less than 10 mol%, the glass transition temperature of the polymer will be low, and when used as a polymer for tires, the grip performance may be inferior. On the other hand, if it exceeds 70 mol%, the glass transition temperature of the polymer will be low. The temperature rises and the resilience may be inferior.
The vinyl content (1,2-bond butadiene unit amount) can be measured by infrared absorption spectrum analysis.

The content of the diene polymer in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 40% by mass or more, and particularly preferably 60% by mass or more. If it is less than 5% by mass, sufficient fuel economy, wet grip performance, dry grip performance, wear resistance, and processability may not be obtained. The content of the diene polymer may be 100% by mass, but is preferably 90% by mass or less.

In the rubber composition of the present invention, other rubber components may be used in combination with the diene polymer. Examples of other rubber components include natural rubber (NR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), Examples include acrylonitrile butadiene rubber (NBR). A rubber component may be used independently and may use 2 or more types together. Of these, NR and BR are preferable because of the improvement in rubber strength, high wear resistance, and high crack growth resistance.
Further, when NR or BR is used together with the diene polymer, the effect of improving wet grip performance, wear resistance, and workability is great by the combined use with the structure silica.

The NR is not particularly limited, and for example, those commonly used in the tire industry such as SIR20, RSS # 3, TSR20 and the like can be used.

When NR is blended in the rubber composition of the present invention, the content of NR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more. If it is less than 5% by mass, fuel economy and wear resistance may be reduced. The NR content is preferably 40% by mass or less, more preferably 30% by mass or less. If it exceeds 40% by mass, the dry grip performance may be lowered.

The BR is not particularly limited. For example, BR1220 and BR1250H manufactured by Nippon Zeon Co., Ltd., BR130B and BR150B manufactured by Ube Industries, Ltd., BR with high cis content, VCR412 and VCR617 manufactured by Ube Industries, Ltd. BR containing a syndiotactic polybutadiene crystal such as can be used. Among these, BR having a cis content of 95% by mass or more is preferable because it has a low glass transition temperature (Tg) and is advantageous for low temperature characteristics.

When BR is blended in the rubber composition of the present invention, the content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more. If it is less than 5% by mass, fuel economy and wear resistance may be reduced. The BR content is preferably 40% by mass or less, more preferably 30% by mass or less. If it exceeds 40 mass%, wet grip performance, dry grip performance, and workability may be deteriorated.

The structure silica (linear silica) used in the present invention has three or more particles adjacent to one particle (hereinafter referred to as a branched particle X), and the branched particle X and a particle adjacent thereto. As a result, a branched structure is formed. The branched particle X is a particle X of the particles in FIG. 1 which is a schematic explanatory diagram of the branched particle, and is adjacent to three or more other particles. In addition, as structure silica, what has a branched structure (for example, FIG. 2) and what does not have are mentioned, However, Since the structured silica which does not have a branched structure will aggregate immediately, it does not exist substantially.

The average length (L ₁ in FIG. 2) between the branched particles XX including the branched particles X of the structure silica is 30 nm or more, preferably 40 nm or more. If it is less than 30 nm, there is a tendency that the dry grip performance cannot be sufficiently improved. L ₁ is 400 nm or less, preferably 200 nm or less, more preferably 100 nm or less. When it exceeds 400 nm, hysteresis loss increases and fuel efficiency tends to deteriorate.

The average primary particle size of the structure silica (D, see FIG. 2 which is a schematic explanatory diagram of structure silica containing branched particles) is preferably 5 nm or more, more preferably 7 nm or more. If it is less than 5 nm, the hysteresis loss increases and the fuel efficiency tends to deteriorate. Further, D is preferably 1000 nm or less, more preferably 100 nm or less, and still more preferably 18 nm or less. If it exceeds 1000 nm, the dry grip performance tends not to be sufficiently improved.

The average aspect ratio (L ₁ / D) of the XX between the branched particles including the branched particle X of the structure silica is preferably 3 or more, more preferably 4 or more. If it is less than 3, there is a tendency that the dry grip performance cannot be sufficiently improved. L ₁ / D is preferably 100 or less, more preferably 30 or less. When L ₁ / D exceeds 100, hysteresis loss increases and fuel efficiency tends to deteriorate.

In the present invention, silica D, L ₁ and L ₁ / D can be measured by observation with a transmission electron microscope of silica dispersed in a vulcanized rubber composition. For example, in FIG. 2, when the particle is a true sphere, L ₁ / D is 5.

The content of the structure silica is preferably 5 parts by mass or more, more preferably 45 parts by mass or more, and still more preferably 65 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 5 mass parts, there exists a tendency for the effect which mix | blended structure silica is not fully acquired. The content of the structure silica is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and still more preferably 100 parts by mass or less. When it exceeds 150 parts by mass, the rigidity of the rubber composition increases, and the workability and wet grip performance tend to deteriorate.

In the rubber composition of the present invention, it is preferable to use a silane coupling agent together with the structure silica. Examples of the silane coupling agent include sulfide, mercapto, vinyl, amino, glycidoxy, nitro, and chloro silane coupling agents. Among these, a sulfide system is preferable because the effects of the present invention can be obtained satisfactorily.

As the sulfide-based silane coupling agent, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3- Triethoxysilylpropyl) disulfide and bis (2-triethoxysilylethyl) disulfide are preferred, and bis (3-triethoxysilylpropyl) disulfide is more preferred.

The content of the silane coupling agent is preferably 1 part by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the structure silica. If it is less than 1 part by mass, the dry grip performance and workability tend not to be improved sufficiently. The content of the silane coupling agent is preferably 20 parts by mass or less, more preferably 12 parts by mass or less. When it exceeds 20 parts by mass, there is a tendency that an effect commensurate with the increase in cost cannot be obtained.

In addition to the components described above, the rubber composition of the present invention includes compounding agents conventionally used in the tire industry, such as reinforcing fillers such as carbon black, various softening agents, various anti-aging agents, waxes, and stearic acid. Vulcanizing agents such as zinc oxide and sulfur, various vulcanization accelerators, and the like can be blended.

The rubber composition of the present invention preferably contains carbon black. As a result, good reinforcement can be obtained, and wear resistance and durability can be further improved.
The carbon black is not particularly limited, and for example, GPF, HAF, ISAF, SAF and the like can be used.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 30 m ² / g or more, more preferably 70 m ² / g or more, and still more preferably 100 m ² / g or more. When N ₂ SA is less than 30 m ² / g, there is a tendency that sufficient reinforcing properties cannot be obtained. Also, _N 2 SA is preferably 250 meters ² / g or less of carbon black, more preferably not more than ^{150m 2 / g, 125m 2 /} g or less is more preferable. When N ₂ SA is more than 250 meters ² / g, the viscosity of the unvulcanized becomes very high, processability tends to be deteriorated. In addition, fuel efficiency tends to deteriorate.
The nitrogen adsorption specific surface area of carbon black is measured according to JIS K6217-2: 2001.

Carbon black has a dibutyl phthalate (DBP) oil absorption of preferably 70 ml / 100 g or more, more preferably 90 ml / 100 g or more. The DBP oil absorption of carbon black is preferably 160 ml / 100 g or less, more preferably 117 ml / 100 g or less. By making it within this range, fuel economy, wet grip performance, dry grip performance, and wear resistance can be improved in a well-balanced manner.
The DBP oil absorption of carbon black is measured according to JIS K6217-4: 2001.

When carbon black is blended in the rubber composition of the present invention, the content of carbon black is preferably 5 parts by mass or more, more preferably 8 parts by mass or more with respect to 100 parts by mass of the rubber component. When the amount is less than 5 parts by mass, the effect of blending carbon black may not be sufficiently obtained. Further, the content of carbon black is preferably 20 parts by mass or less, more preferably 15 parts by mass or less. If it exceeds 20 parts by mass, the fuel efficiency tends to deteriorate.

Examples of vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Agents. Of these, sulfenamide vulcanization accelerators are preferred because the effects of the present invention can be obtained satisfactorily.

Examples of the sulfenamide vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N, N And '-dicyclohexyl-2-benzothiazolylsulfenamide (DZ). Among these, CBS is preferable because the effects of the present invention can be obtained satisfactorily, and it is more preferable to use CBS and N, N′-diphenylguanidine in combination.

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

In particular, it is preferable to knead the silica sol together with a rubber component containing the modified diene polymer in a rubber kneading apparatus from the viewpoint that the rubber composition of the present invention in which structure silica is formed can be easily produced. In particular,
(I) A rubber component containing the modified diene polymer, silica sol, and carbon black, silane coupling agent, zinc oxide, stearic acid, softener, anti-aging agent, wax, etc. A base kneading step of kneading at 0 ° C. (preferably 90-110 ° C.) for 3-10 minutes
(II) a final kneading step in which the kneaded product obtained by the base kneading step, the vulcanizing agent, and the vulcanization accelerator are kneaded at 30 to 70 ° C. (preferably 40 to 60 ° C.) for 3 to 10 minutes;
(III) A vulcanization step of vulcanizing the unvulcanized rubber composition obtained by the finish kneading step at 150 to 190 ° C. (preferably 160 to 180 ° C.) for 5 to 30 minutes is more preferable.

The preferable compounding amount (silica conversion) of silica sol is the same as that of the above-mentioned structure silica.

In the kneading step of forming a structure silica (such as the base kneading step), when kneading the respective components in toluene is a good solvent for rubber, for L ₁ of structure silica tends to likely too long, toluene It is preferable to knead without using.

In this specification, silica sol refers to a colloidal solution in which silica is dispersed in a solvent. The silica sol is not particularly limited, but a colloidal solution in which elongated silica is dispersed in a solvent is preferable because a structure silica can be suitably formed. A colloidal solution in which elongated silica is dispersed in an organic solvent (organo Silica sol) is more preferable. Here, the elongated silica means a silica (secondary particle) having a chain shape in which a plurality of primary particles such as a spherical shape and a granular shape are connected. It may be linear or branched.

The solvent for dispersing silica is not particularly limited, but alcohols such as methanol and isopropanol are preferable, and isopropanol is more preferable.

The average particle diameter of primary particles constituting silica (secondary particles) contained in the silica sol is preferably 1 to 100 nm, more preferably 5 to 80 nm.
The average particle size of the primary particles was determined by visually measuring the particle size (average diameter) of 50 primary particles in a photograph taken with a transmission electron microscope JEM2100FX manufactured by JEOL. .

In addition, when the silica (secondary particles) has an elongated shape, the average diameter of the primary particles is an average value of thicknesses (diameters) measured at arbitrary 50 locations of the silica (secondary particles) in the electron micrograph. When silica (secondary particles) has a constriction and a bead shape, it can be obtained as an average value of the diameters of 50 bead beads in an electron micrograph. When each rosary has a major axis and a minor axis, that is, when each rosary is elongated, the minor axis is measured.

The average particle diameter of silica (secondary particles) contained in the silica sol is preferably 20 to 300 nm, more preferably 30 to 150 nm. The average particle diameter of silica (secondary particles) can be measured by a dynamic light scattering method, and specifically, can be measured by the following method.
The average particle diameter of silica (secondary particles) was measured with a laser particle analysis system ELS-8000 (cumulant analysis) manufactured by Otsuka Electronics Co., Ltd. The measurement conditions are a temperature of 25 ° C., an angle between incident light and a detector of 90 °, and the number of integrations of 100 times. The measurement concentration was usually about 5 × 10 ⁻³ mass%.

The silica (secondary particles) can be obtained by, for example, the method described in claim 2 of the pamphlet of International Publication No. 00/15552 and the disclosure of the specification related thereto, Patent No. 2803134, Patent No. 2926915 It can manufacture according to the method etc. as described in the disclosure part of claim | item 2 and the specification regarding it.

Specific examples of the silica (secondary particles) that can be used in the present invention include “Snowtex-OUP” (average secondary particle size: 40 to 100 nm) manufactured by Nissan Chemical Industries, Ltd. “Tex-UP” (average secondary particle size: 40 to 100 nm), “Snowtex PS-M” (average secondary particle size: 80 to 150 nm), “Snowtex PS-MO” (average secondary particle size) : 80-150 nm), “Snowtex PS-S” (average secondary particle size: 80-120 nm), “Snowtex PS-SO” (average secondary particle size: 80-120 nm), “IPA-ST” -UP "(average secondary particle size: 40 to 100 nm)," Quatron PL-7 "(average secondary particle size: 130 nm) manufactured by Fuso Chemical Co., Ltd., and the like. Among these, IPA-ST-UP is preferable because it can form a structure silica suitably.

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

The pneumatic tire of the present invention is produced by a usual method using the rubber composition. That is, if necessary, a rubber composition containing various additives is extruded in accordance with the shape of each member of the tire (especially, the tread (cap tread)) at an unvulcanized stage, and is applied to the tire molding machine. Then, after forming by an ordinary method and pasting together with other tire members to form an unvulcanized tire, the tire can be manufactured by heating and pressing in a vulcanizer.

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

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

Hereinafter, various chemicals used in the production examples will be described together. In addition, the chemical | medical agent refine | purified according to the usual method as needed.
Cyclohexane: manufactured by Tokyo Chemical Industry Co., Ltd. (purity 99.5% or more)
Styrene: Tokyo Kasei Co., Ltd. (purity 99% or more)
1,3-Butadiene: N, N, N ′, N′-tetramethylethylenediamine manufactured by Tokyo Chemical Industry Co., Ltd .: n-butyllithium manufactured by Wako Pure Chemical Industries, Ltd .: 1,3-divinyl manufactured by Wako Pure Chemical Industries, Ltd. Benzene in hexane solution (1.6M): Tokyo Chemical Industry Co., Ltd. Isopropanol: Wako Pure Chemical Industries, Ltd. 2,6-tert-butyl-p-cresol: Wako Pure Chemical Industries, Ltd. Tetraglycidyl-1,3 -Bisaminomethylcyclohexane: Wako Pure Chemical Industries, Ltd. (compound represented by the following formula (modifier))

Methanol: manufactured by Kanto Chemical Co., Inc.

Production Example 1
(Preparation of polymerization initiator)
Add 10 ml of 1,3-divinylbenzene in hexane (1.6 M) to a 100 ml pressure-resistant container thoroughly purged with nitrogen, and drop 20 ml of n-butyllithium hexane solution (1.6 M) at 0 ° C. A polymerization initiator solution was obtained by stirring for a period of time.

Production Example 2
(Preparation of diene polymer (modified diene polymer))
To a 1000 ml pressure vessel fully purged with nitrogen, add 600 ml of cyclohexane, 0.12 mol of styrene, 0.8 mol of 1,3-butadiene, 0.7 mmol of N, N, N ′, N′-tetramethylethylenediamine, and further manufacture 1.5 ml of the polymerization initiator solution obtained in Example 1 was added and stirred at 40 ° C. Three hours later, 1.0 mmol of tetraglycidyl-1,3-bisaminomethylcyclohexane as a modifier was added and stirred. After 1 hour, 3 ml of isopropanol was added to terminate the polymerization. After adding 1 g of 2,6-tert-butyl-p-cresol to the reaction solution, reprecipitation treatment with methanol, and heat drying to modify a diene polymer (more than two modified sites (terminals, etc.)) Diene polymer) was obtained.

The following evaluation was performed about the obtained diene polymer.

(Mooney viscosity)
Heated by preheating for 1 minute using a Mooney viscosity tester in accordance with JIS K 6300-1 “Unvulcanized rubber-Physical properties-Part 1: Determination of viscosity and scorch time using Mooney viscometer” Under the temperature condition of 100 ° C., the small rotor was rotated, and the Mooney viscosity (ML _{1 +} 4/100 ° C.) of the diene polymer after 4 minutes was measured. The numbers after the decimal point are rounded off. As a result, the Mooney viscosity of the diene polymer was 60.

(Vinyl content)
The vinyl content of the diene polymer was measured by infrared absorption spectrum analysis. As a result, the vinyl content of the diene polymer was 57 mol%.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
Diene polymer: Diene polymer SBR prepared in Production Example 2 above: S15 coupled with E15 (a compound having an epoxy group (tetraglycidyl-1,3-bisaminomethylcyclohexane) manufactured by Asahi Kasei Chemicals Corporation) -SBR, styrene unit amount: 23% by mass, vinyl unit amount: 64% by mass, terminal group: OH (one-end modified SBR))
BR: Nipol BR1220 (cis content: 97% by mass) manufactured by Nippon Zeon Co., Ltd.
NR: RSS # 3
Carbon black: Seast N220 manufactured by Mitsubishi Chemical Corporation (N220, N ₂ SA: 114 m ² / g, DBP oil absorption: 114 ml / 100 g)
Silica (1): Ultrasil VN3 manufactured by Evonik Degussa (N ₂ SA: 175 m ² / g)
Silica (2): Organosilica sol IPA-ST-UP manufactured by Nissan Chemical Industries, Ltd. (elongated isopropanol-dispersed silica sol (average particle diameter of silica (secondary particles) measured by dynamic light scattering method): 40 to 100 nm), silica content: 15% by mass) (the amounts shown in Table 2 indicate the amount of silica in the organosilica sol)
Silane coupling agent: Si75 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa
Zinc oxide: Zinc Hua 1 manufactured by Mitsui Mining & Smelting Co., Ltd.
Aroma oil: Process X-140 manufactured by JX Nippon Oil & Energy
Anti-aging agent: Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Sulfur: Powder sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd. (1): Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator (2): Noxeller D (N, N'-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Examples and Comparative Examples According to the formulation shown in Table 2, materials other than sulfur and a vulcanization accelerator were kneaded for 5 minutes at 100 ° C. using a Banbury mixer to obtain a kneaded product. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 5 minutes at 50 ° C. using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is molded into a tread shape, bonded to another tire member, molded into a tire, and vulcanized at 170 ° C. for 20 minutes to test tires (tire size: 195 / 65R15). ) Was manufactured.

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

(Average primary particle diameter, average length and average aspect ratio of silica)
A sample was cut out from the tread of the test tire, and the silica dispersed in the sample was observed with a transmission electron microscope. The average primary particle diameter (D) of silica and the distance between the branched particles XX including the branched particles X were measured. The average length (L ₁ in FIG. 2), the average length of the XX between the branched particles not including the branched particle X (L ₂ in FIG. ₂ ), the average aspect ratio of the XX between the branched particles including the branched particle X (L ₁ / D), the average aspect ratio (L ₂ / D) of XX between the branched particles not including the branched particle X was calculated. The numerical value was an average value obtained by measuring 30 locations.

(Rolling resistance)
Using a rolling resistance tester, the rolling resistance when the test tire was run at a rim (15 × 6JJ), internal pressure (230 kPa), load (3.43 kN), and speed (80 km / h) was measured. The index was expressed by the calculation formula. The larger the index, the lower the rolling resistance and the better the fuel efficiency.
(Rolling resistance index) = (Rolling resistance of Comparative Example 5) / (Rolling resistance of each formulation) × 100

(Dry grip performance)
The test tire was mounted on a test vehicle, and the vehicle was driven on a dry asphalt road test course. At this time, the vehicle was run at 40 km / h, the maximum friction coefficient (μ) from when the brake was applied to when it was stopped was measured, the dry grip index of Comparative Example 5 was set to 100, and the index was displayed by the following formula. The larger the dry grip index, the better the dry grip performance.
(Dry grip index) = (Maximum friction coefficient of each formulation) / (Maximum friction coefficient of Comparative Example 5) × 100

(Wet grip performance)
The test tire was mounted on a test vehicle, and the vehicle was driven on a wet asphalt road test course. At this time, the vehicle was run at 40 km / h, the maximum friction coefficient (μ) from when the brake was applied to when it was stopped was measured, the wet grip index of Comparative Example 5 was set to 100, and the index was displayed by the following formula. The larger the wet grip index, the better the wet grip performance.
(Wet grip index) = (Maximum friction coefficient of each formulation) / (Maximum friction coefficient of Comparative Example 5) × 100

(Abrasion resistance)
The test tire was mounted on a passenger car equipped with 1800 cc-class ABS, the amount of decrease in groove depth after traveling 30000 km in an urban area was measured, and the travel distance when the groove depth decreased by 1 mm was calculated. Furthermore, the abrasion resistance index of Comparative Example 5 was set to 100, and the amount of decrease in the groove depth of each formulation was displayed as an index according to the following formula. In addition, it shows that it is excellent in abrasion resistance, so that an abrasion resistance index | exponent is large.
(Abrasion resistance index) = (travel distance when the groove depth is reduced by 1 mm in each formulation) / (travel distance when the groove of the tire of Comparative Example 5 is reduced by 1 mm) × 100

(Mooney viscosity)
About the obtained unvulcanized rubber composition, it measured at 130 degreeC according to the measuring method of the Mooney viscosity based on JISK6300. The Mooney viscosity (ML _{1 + 4} ) of Comparative Example 5 was set to 100, and indexed by the following formula (Mooney viscosity index). The larger the index, the lower the Mooney viscosity and the better the processability.
(Mooney viscosity index) = (ML _{1 + 4} of Comparative Example 5) / (ML _{1 + 4 of} each formulation) _× 100

From Tables 1 and 2, the examples in which the modified specific diene polymer and the specific silica (structure silica in which L ₁ is in a specific range) are used in combination are low in comparison with the corresponding comparative examples. The fuel efficiency, wet grip performance, dry grip performance, wear resistance, and workability are all greatly improved.
Moreover, from the results of Example 1 and Comparative Examples 1, 2, and 5, it was found that the combined use can synergistically improve fuel efficiency, wet grip performance, dry grip performance, wear resistance, and workability.

X Branched particle

Claims (12)

1. Including a diene polymer and silica;
   The diene polymer is a modified diene polymer obtained by reacting the following (A) and (B):
   When the silica has three or more particles adjacent to one particle as the branched particle X, the average length L ₁ between the branched particles XX including the branched particle X is 30 to 400 nm. A rubber composition for a tire.
   (A): an active conjugated diene polymer having an alkali metal end obtained by polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer in the presence of (C) below (B): functional group Modifier (C) having: a chemical species obtained by reacting a compound represented by the following formula (1) with an organic alkali metal compound
   

   

   (In Formula (1), R ¹ and R ² are the same or different and are a hydrogen atom, a branched or unbranched alkyl group, a branched or unbranched aryl group, a branched or unbranched alkoxy group, branched or unbranched. A silyloxy group, a branched or unbranched acetal group, a carboxyl group, a mercapto group, or a derivative thereof, A represents a branched or unbranched alkylene group, a branched or unbranched arylene group, or a derivative thereof.
2. A tire rubber composition obtained by kneading a modified diene polymer obtained by reacting the following (A) and (B) with silica sol.
   (A): an active conjugated diene polymer having an alkali metal end obtained by polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer in the presence of (C) below (B): functional group Modifier (C) having: a chemical species obtained by reacting a compound represented by the following formula (1) with an organic alkali metal compound
   

   

   (In Formula (1), R ¹ and R ² are the same or different and are a hydrogen atom, a branched or unbranched alkyl group, a branched or unbranched aryl group, a branched or unbranched alkoxy group, branched or unbranched. A silyloxy group, a branched or unbranched acetal group, a carboxyl group, a mercapto group, or a derivative thereof, A represents a branched or unbranched alkylene group, a branched or unbranched arylene group, or a derivative thereof.
3. The tire rubber composition according to claim 1 or 2, wherein the compound represented by the formula (1) is a compound represented by the following formula (2).
   

   
4. The tire rubber composition according to any one of claims 1 to 3, wherein the modifier is a compound represented by the following formula (3).
   

   

   (In Formula (3), R ³ and R ⁴ are the same or different and each represents a hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group is selected from the group consisting of ethers and tertiary amines. R ⁵ and R ⁶ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, the hydrocarbon group being an ether, and 3 It may have at least one group selected from the group consisting of a tertiary amine, R ⁷ represents a hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group is an ether, a tertiary amine, an epoxy And at least one group selected from the group consisting of carbonyl, and halogen, n represents an integer of 1 to 6.)
5. The tire rubber composition according to any one of claims 1 to 4, wherein the modifiers introduced at both ends of the active conjugated diene polymer are the same.
6. The tire rubber composition according to any one of claims 1 to 5, wherein the content of the diene polymer in 100% by mass of the rubber component is 5% by mass or more.
7. 7. The tire rubber composition according to claim 1, wherein the conjugated diene monomer is 1,3-butadiene and / or isoprene, and the aromatic vinyl monomer is styrene.
8. The tire rubber composition according to any one of claims 1 to 7, wherein the modified diene polymer is a modified styrene butadiene rubber obtained by polymerizing 1,3-butadiene and styrene.
9. The silica, an average primary particle diameter is D, the branch of the branch intergranular X-X of the particles comprising an X average aspect ratio L ₁ / D is according to claim 1 or 3-8 is of 3 to 100 The rubber composition for tires in any one.
10. The tire rubber composition according to any one of claims 1 and 3 to 9, comprising 5 to 150 parts by mass of the silica with respect to 100 parts by mass of the rubber component.
11. The tire rubber composition according to any one of claims 1 to 10, which is used as a rubber composition for a tread.
12. A pneumatic tire using the rubber composition according to any one of claims 1 to 11.

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