JP2014162809A - Rubber composition and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition excellent in low rolling resistance and wet performance and also excellent in scorching property when the rubber composition is formed into a tire.SOLUTION: The rubber composition comprises a rubber component containing 10 mass% or more of conjugated diene rubber (A), a mercapto-based silane coupling agent (B), and silica (C), in which the conjugated diene rubber (A) contains 5 mass% or more of a specific structure (a), the content of the mercapto-based silane coupling agent (B) is 0.5-20 mass% based on the content of the silica (C), and the content of the silica (C) is 5-150 pts.mass to 100 pts.mass of the rubber component.

Description

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

In recent years, it has been required to reduce rolling resistance of tires from the viewpoint of low fuel consumption during vehicle travel. Moreover, the improvement of wet performance is calculated | required from the surface of safety. On the other hand, a method is known in which silica is blended with the rubber component constituting the tread portion of the tire so as to achieve both low rolling resistance and wet performance.
However, since silica has low affinity with rubber components and high cohesiveness between silicas, silica is not dispersed even if silica is simply added to the rubber component, reducing rolling resistance and wet performance. There was a problem that the effect of improving could not be obtained sufficiently.

  Under such circumstances, Patent Document 1 discloses a rubber composition containing a conjugated diene rubber having an isoprene block. According to Patent Document 1, it is described that by using the above composition, the affinity between silica and rubber is improved, and the low heat build-up (low rolling resistance) and wet grip properties of the tire can be improved. ing.

  In addition, the rubber composition for tires is required to have less cross-linking (rubber burn) in the storage stage and the stage before the vulcanization process. That is, excellent scorch (workability) is required.

International Publication No. 2011/105362

  On the other hand, due to environmental problems and resource problems, further fuel efficiency of vehicles is required, and accordingly, further improvement of tire rolling resistance is required. Further, with the improvement of the required safety level, further improvement in wet performance is also required.

Under such circumstances, the rubber composition described in Patent Document 1 was examined, and it was revealed that the low rolling resistance and the wet performance did not satisfy the levels required recently, although the scorch property was excellent.
Therefore, in view of the above circumstances, an object of the present invention is to provide a rubber composition which is excellent in low rolling resistance and wet performance when made into a tire and excellent in scorch properties.

As a result of intensive studies on the above problems, the present inventors have used a rubber component containing a specific amount of a specific conjugated diene rubber and a mercapto silane coupling agent in combination, so that the tire has low rolling resistance. And it discovered that the rubber composition excellent in wet performance and scorch property was obtained, and it came to this invention.
That is, the present inventors have found that the above problem can be solved by the following configuration.

(1) A rubber component containing 10% by mass or more of the conjugated diene rubber (A), a mercapto silane coupling agent (B), and silica (C),
Three or more conjugated diene copolymer chains (a1) obtained by reacting the conjugated diene rubber (A) with a conjugated diene copolymer chain (a1) and a modifier (a2) Containing 5 mass% or more of the structure (a) formed by bonding via the modifier (a2),
The conjugated diene copolymer chain (a1) is a conjugated diene copolymer chain having an isoprene block containing 70% by mass or more of isoprene units at one end and an active end at the other end. ,
The modifier (a2) is an modifier having an epoxy group and / or a hydrocarbyloxysilyl group, and the total number of the epoxy group and the hydrocarbyloxy group contained in the hydrocarbyloxysilyl is 3 or more. ,
The content of the mercapto-based silane coupling agent (B) is 0.5 to 20% by mass with respect to the content of the silica (C),
The rubber composition whose content of the said silica (C) is 5-150 mass with respect to 100 mass parts of said rubber components.
(2) The mercapto-based silane coupling agent (B) is a compound represented by the following formula (7) and / or a repeating unit represented by the following formula (9) and a formula (10) described later. The rubber composition according to (1) above, which is a copolymer having a repeating unit represented by:
(3) The rubber composition according to (1) or (2), wherein the modifier (a2) is polyorganosiloxane.
(4) A pneumatic tire using the rubber composition according to any one of (1) to (3) in a tire tread.

  As shown below, according to the present invention, a rubber composition excellent in low rolling resistance and wet performance when made into a tire and excellent in scorch and a pneumatic tire using the rubber composition for a tire tread is provided. can do.

It is a partial section schematic diagram of the tire showing an example of the embodiment of the pneumatic tire of the present invention.

  Below, the rubber composition of this invention and the pneumatic tire using the rubber composition of this invention are demonstrated.

[Rubber composition]
The rubber composition of the present invention contains a rubber component containing 10% by mass or more of a conjugated diene rubber (A), a mercapto silane coupling agent (B), and silica (C), and the conjugated diene rubber described above. (A) is obtained by reaction of the conjugated diene copolymer chain (a1) with the modifier (a2), and three or more conjugated diene copolymer chains (a1) are the modifier (a2). 5% by mass or more of the structure (a) formed through bonding is included.
Here, the conjugated diene copolymer chain (a1) has an isoprene block containing 70% by mass or more of isoprene units at one end and an active end at the other end. Is a chain.
The modifier (a2) has an epoxy group and / or a hydrocarbyloxysilyl group, and the total number of the epoxy group and the hydrocarbyloxy group contained in the hydrocarbyloxysilyl is 3 or more. It is.
Further, the content of the mercapto-based silane coupling agent (B) is 0.5 to 20% by mass with respect to the content of the silica (C), and the content of the silica (C) is the rubber. It is 5-150 mass with respect to 100 mass parts of components.

  Since the rubber composition of the present invention uses a conjugated diene rubber (A) containing a predetermined amount of the structure (a) described later and a mercapto silane coupling agent (B), low rolling resistance, wet It is considered that the rubber composition exhibits excellent characteristics in both performance and scorch properties.

The reason is not clear, but it is presumed that it is as follows.
As will be described later, the structure (a) has a structure in which a conjugated diene polymer chain (a1) having an isoprene block is bonded via a modifier (a2). Since the rubber composition of the present invention uses the conjugated diene rubber (A) containing a predetermined amount of the structure (a) and the mercapto silane coupling agent (B), the mercapto silane coupling agent (B ) Mercapto groups and hydrolyzable groups interact with both the isoprene block of the structure (a) and silica to improve the dispersibility of the silica, resulting in excellent low rolling resistance and wet performance. It is thought that it shows. In particular, the strong affinity of the mercapto group for the isoprene block is considered to ensure the excellent characteristics as described above. This means that even when the conjugated diene rubber (A) containing a predetermined amount of the structure (a) is used, a non-mercapto silane coupling agent is used as the silane coupling agent (Comparative Example 3 described later). Even when the mercapto-based silane coupling agent (B) is used and the conjugated diene rubber not containing the structure (a) is used (Comparative Example 1 described later), low rolling resistance and wet performance are obtained. It is also inferred from the fact that it becomes insufficient.
In addition, it is considered that the mercapto group is stabilized by the strong affinity between the mercapto group and the isoprene block as described above, and excellent scorch properties are ensured. This is also inferred from the fact that the conjugated diene rubber not containing the structure (a) is used (Comparative Example 1 described later) and the fact that the scorch property becomes insufficient.

  Hereinafter, each component contained in the rubber composition of the present invention will be described in detail.

[Rubber component]
The rubber component contained in the rubber composition of the present invention contains 10% by mass or more of a conjugated diene rubber (A) described later. The rubber component may contain a diene rubber other than the conjugated diene rubber (A).

  The conjugated diene rubber (A) is obtained by reacting a conjugated diene copolymer chain (a1) described later with a modifying agent (a2) described later and three or more conjugated diene copolymer chains (a1). Contains 5% by mass or more of a structure (a) described later formed by bonding via a modifier (a2).

<Conjugated Diene Polymer Chain (a1)>
The conjugated diene polymer chain (a1) used for forming the structure (a) contained in the conjugated diene rubber (A) is a polymer chain comprising a conjugated diene monomer unit. There is no particular limitation as long as it has an isoprene block at one end and an active end (polymerization active end or living growth end) at the other end.

  The conjugated diene polymer chain (a1) is obtained by subjecting an isoprene or an isoprene mixture containing a predetermined amount of isoprene in an inert solvent to living polymerization using a polymerization initiator, thereby producing an active end (polymerization active end or Forming an isoprene block having a living growth terminal), and then coupling a conjugated diene monomer or a monomer mixture comprising a conjugated diene monomer to an isoprene block having an active terminal, followed by living polymerization. Can be obtained. The monomer mixture containing the conjugated diene monomer preferably further contains an aromatic vinyl monomer.

  The isoprene block is a homopolymer of isoprene or a copolymer of isoprene and another monomer (monomer), and is a polyisoprene having a content of isoprene units of 70% by mass or more. The content of isoprene units in the isoprene block is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass.

  As described above, the conjugated diene polymer chain (a1) has the isoprene block at one end. An isoprene block may be further included in the chain of the conjugated diene polymer chain (a1). It has an isoprene block at both ends, and an isoprene block at one end of them may have an active end, but it is preferable from the viewpoint of productivity to have an isoprene block only at the end that is not the active end. .

  The weight average molecular weight of the isoprene block is not particularly limited, but is preferably 500 to 25,000, more preferably 1,000 to 15,000, and particularly preferably 1,500 to 10,000 from the viewpoint of strength. is there.

  The molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the isoprene block is not particularly limited, but from the viewpoint of productivity, preferably 1.0 to 1. 5, More preferably, it is 1.0-1.4, Most preferably, it is 1.0-1.3.

  The other monomer that can be copolymerized with isoprene used for obtaining the isoprene block is not particularly limited as long as it is copolymerizable with isoprene. For example, 1,3-butadiene, styrene, α-methylstyrene Etc. can be used. Among these, styrene is preferable. In the isoprene block, the content of other monomer units is less than 30% by mass, preferably less than 20% by mass, more preferably less than 10% by mass, and monomers other than isoprene units. It is particularly preferred not to contain.

  As the inert solvent used for the polymerization of isoprene (or isoprene mixture), any solvent that is usually used in solution polymerization and does not inhibit the polymerization reaction can be used without particular limitation. Specific examples thereof include, for example, chain aliphatic hydrocarbons such as butane, pentane, hexane, heptane and 2-butene; alicyclic hydrocarbons such as cyclopentane, cyclohexane and cyclohexene; aromatics such as benzene, toluene and xylene. Group hydrocarbons; and the like. The amount of the inert solvent used is not particularly limited, but is usually an amount such that the concentration of all monomers (isoprene and other monomers) is 1 to 50% by mass, preferably 10 to 40% by mass. It is the quantity which becomes.

  The polymerization initiator for synthesizing the isoprene block is not particularly limited as long as it is capable of living polymerizing isoprene (or an isoprene mixture) to give a polymer chain having an active end. A polymerization initiator mainly comprising an alkali metal compound, an organic alkaline earth metal compound, a lanthanum series metal compound, or the like is preferably used. Specific examples of the organic alkali metal compound include, for example, organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenelithium; dilithiomethane, 1,4-dilithiobutane Organic polyvalent lithium compounds such as 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, and 1,3,5-tris (lithiomethyl) benzene; organic sodium compounds such as sodium naphthalene; Organic potassium compounds such as potassium naphthalene; and the like. Examples of organic alkaline earth metal compounds include di-n-butylmagnesium, di-n-hexylmagnesium, diethoxycalcium, calcium distearate, di-t-butoxystrontium, diethoxybarium, diisopropoxybarium, and diethyl. Examples include mercaptobarium, di-t-butoxybarium, diphenoxybarium, diethylaminobarium, barium distearate, and diketylbarium. As a polymerization initiator having a lanthanum series metal compound as a main catalyst, a lanthanum series metal salt comprising a lanthanum series metal such as lanthanum, cerium, praseodymium, neodymium, samarium and gadolinium, a carboxylic acid, and a phosphorus-containing organic acid As a main catalyst, and a polymerization initiator comprising this and a co-catalyst such as an alkylaluminum compound, an organoaluminum hydride compound, and an organoaluminum halide compound. Among these polymerization initiators, it is preferable to use an organic monolithium compound and an organic polyvalent lithium compound, more preferably an organic monolithium compound, and particularly preferably n-butyllithium. In addition, the organic alkali metal compound is a secondary compound such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, hexamethyleneimine, and heptamethyleneimine (preferably pyrrolidine, hexamethyleneimine, and heptamethyleneimine). You may make it react with an amine and use it as an organic alkali metal amide compound. These polymerization initiators can be used alone or in combination of two or more.

  The amount of the polymerization initiator used may be determined according to the target molecular weight, but is preferably 4 to 250 mmol, more preferably 30 to 200 mmol, and particularly preferably 40 to 100 mmol per 100 g of isoprene (or isoprene mixture). It is a range.

  When polymerizing isoprene (or isoprene mixture), the polymerization temperature is usually in the range of -80 to 150 ° C, preferably 0 to 100 ° C, more preferably 20 to 90 ° C.

  In order to adjust the content of vinyl bonds derived from isoprene units in the isoprene block (hereinafter also simply referred to as vinyl bond content), it is preferable to add a polar compound to an inert organic solvent during polymerization. Examples of the polar compound include ether compounds such as dibutyl ether, tetrahydrofuran and 2,2-di (tetrahydrofuryl) propane; tertiary amines such as tetramethylethylenediamine; alkali metal alkoxides; phosphine compounds; Among these, ether compounds and tertiary amines are preferable, and among them, those capable of forming a chelate structure with the metal of the polymerization initiator are more preferable, and 2,2-di (tetrahydrofuryl) propane and tetramethylethylenediamine are particularly preferable. preferable. The amount of the polar compound used may be determined according to the target vinyl bond content, and is preferably adjusted in the range of 0.1 to 30 mol, more preferably 0.5 to 10 mol, relative to 1 mol of the polymerization initiator. do it. When the amount of the polar compound used is within this range, the vinyl bond content can be easily adjusted, and problems due to the deactivation of the polymerization initiator hardly occur.

  The vinyl bond content in the isoprene block is preferably from 21 to 85% by mass, more preferably from 50 to 80% by mass, and even more preferably from 70 to 80% by mass because the low rolling resistance and wet performance are more excellent. The vinyl bond content derived from isoprene units is the total ratio (mass of 1,2-vinyl bond units derived from isoprene units and 3,4-vinyl bond units derived from isoprene units in the isoprene block. %).

  The part other than the isoprene block in the conjugated diene polymer chain (a1) may be a homopolymer chain of a conjugated diene monomer or a copolymer chain of a conjugated diene monomer and an aromatic vinyl monomer. preferable. The mass ratio of the conjugated diene monomer unit to the aromatic vinyl monomer unit in the portion other than the isoprene block (conjugated diene monomer unit: aromatic vinyl monomer unit) is 100: 0 to 50:50. Preferably, 90:10 to 70:30 is more preferable.

  Although it does not specifically limit as a conjugated diene monomer used in order to obtain parts other than an isoprene block in a conjugated diene type polymer chain (a1), For example, 1, 3- butadiene, isoprene (2-methyl-1,3) -Butadiene), 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and the like. Among these, 1,3-butadiene or isoprene is preferably used, and 1,3-butadiene is more preferably used. These conjugated diene monomers can be used alone or in combination of two or more.

  In addition, the aromatic vinyl monomer used to obtain a portion other than the isoprene block in the conjugated diene polymer chain (a1) is not particularly limited, and examples thereof include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t- Examples thereof include butyl-2-methylstyrene, vinylnaphthalene, dimethylaminomethylstyrene, and dimethylaminoethylstyrene. Among these, styrene, α-methylstyrene, and 4-methylstyrene are preferable, and styrene is more preferable. These aromatic vinyl monomers can be used alone or in combination of two or more.

  As a monomer to be used for obtaining a portion other than the isoprene block in the conjugated diene polymer chain (a1), a conjugated diene monomer and an aromatic vinyl are optionally selected as long as the essential characteristics of the present invention are not impaired. Other monomers other than the monomer can be used. Other monomers include, for example, α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids or acid anhydrides such as acrylic acid, methacrylic acid, and maleic anhydride; methyl methacrylate Unsaturated carboxylic acid esters such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene Non-conjugated dienes can be mentioned. The amount of these monomers used is preferably 10% by mass or less, preferably 5% by mass or less, based on the total amount of monomers used for obtaining a portion other than the isoprene block in the conjugated diene polymer chain (a1). Is more preferable.

  The inert solvent used for polymerization of a portion other than the isoprene block in the conjugated diene polymer chain (a1) is the same as the inert solvent used for the synthesis of the above-described isoprene block.

  As the polymerization initiator used for the synthesis of a portion other than the isoprene block in the conjugated diene polymer chain (a1), the above-described isoprene block having an active end is used as it is. The amount of the polymerization initiator used may be determined according to the target molecular weight, but is usually 0.1 to 5 mmol, preferably 0.2 to 2 mmol, more preferably 0 per 100 g of the monomer (mixture). The range is from 3 to 1.5 mmol.

  In polymerizing a portion other than the isoprene block in the conjugated diene polymer chain (a1), the polymerization temperature is usually -80 to 150 ° C, preferably 0 to 100 ° C, more preferably 20 to 90 ° C. is there. As the polymerization mode, any mode such as batch mode or continuous mode can be adopted. When the portion other than the isoprene block in the conjugated diene polymer chain (a1) is a copolymer chain of a conjugated diene monomer and an aromatic vinyl monomer, or two or more conjugated diene monomers In the case where the copolymer chain is made of, a batch system is preferable because the randomness of the bond can be easily controlled.

  When the portion other than the isoprene block in the conjugated diene polymer chain (a1) is a copolymer chain of a conjugated diene monomer and an aromatic vinyl monomer, or two or more conjugated diene monomers The coupling mode of each monomer in the case of forming a copolymer chain comprising, for example, various coupling modes such as a block shape, a taper shape, or a random shape. Among these, a random shape is preferable. When the coupling mode of the conjugated diene monomer and the aromatic vinyl monomer is random, in the polymerization system, the aromatic vinyl monomer with respect to the total amount of the conjugated diene monomer and the aromatic pinyl monomer. It is preferable that the conjugated diene monomer or the conjugated diene monomer and the aromatic pinyl monomer are continuously or intermittently supplied into the polymerization system for polymerization so that the ratio of the body does not become too high. .

  In order to adjust the vinyl bond content in the portion other than the isoprene block of the conjugated diene polymer chain (a1), as in the case of adjusting the vinyl bond content in the isoprene unit in the isoprene block, an inert organic compound is used during the polymerization. It is preferable to add a polar compound to the solvent. However, when synthesizing the isoprene block, when adding a sufficient amount of a polar compound to the inert organic solvent to adjust the vinyl bond content in the portion other than the isoprene block of the conjugated diene polymer chain, It is not necessary to newly add a polar compound. The specific example about the polar compound used in order to adjust vinyl bond content in parts other than an isoprene block is the same as the polar compound used for the synthesis | combination of the above-mentioned isoprene block. The amount of the polar compound used may be determined according to the target vinyl bond content, and is preferably adjusted in the range of 0.01 to 100 mol, more preferably 0.1 to 30 mol with respect to 1 mol of the polymerization initiator. do it. When the amount of the polar compound used is within this range, the vinyl bond content in the portion other than the isoprene block can be easily adjusted, and problems due to the deactivation of the polymerization initiator hardly occur.

The vinyl bond content in the portion other than the isoprene block of the conjugated diene polymer chain (a1) is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, from the viewpoint of balance between viscoelastic properties and strength. It is.
In addition, vinyl bond content in parts other than an isoprene block is a ratio (mass%) of a vinyl bond unit in parts other than the isoprene block of a conjugated diene polymer chain (a1).

  The weight average molecular weight of the conjugated diene polymer chain (a1) is not particularly limited, but is preferably 1,000 to 2,000,000, more preferably 10,000 to 1,500,000, and 100,000 to 1 1,000,000 is particularly preferred. When the weight average molecular weight of the conjugated diene polymer chain (a1) is within the above range, the balance between tire strength and low rolling resistance is good.

  The molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the conjugated diene polymer chain (a1) is preferably 1.0 to 3.0, more preferably. Is 1.0 to 2.5, particularly preferably 1.0 to 2.2. When the molecular weight distribution value (Mw / Mn) is within the above range, the conjugated diene rubber (A) can be easily produced.

  As described above, the conjugated diene polymer chain (a1) forms an isoprene block having an active end by first living polymerizing isoprene (or an isoprene mixture) using an initiator in an inert solvent. Then, using this isoprene block as a new polymerization initiator, it can be obtained by living polymerizing a monomer such as a conjugated diene monomer. At this time, an isoprene block may be added to a monomer solution such as a conjugated diene monomer, or a monomer such as a conjugated diene monomer may be added to a solution of an isoprene block. It is preferable to add an isoprene block in a solution of a monomer such as a diene monomer. Further, when the polymerization conversion rate of a monomer such as a conjugated diene monomer is usually 95% or more, a conjugated diene polymer chain (a1) is newly added by adding isoprene (or an isoprene mixture). An isoprene block can also be formed on the active terminal side of. The amount of isoprene (or isoprene mixture) used is preferably 10 to 100 mol, more preferably 15 to 70 mol, and particularly preferably 20 to 35 mol with respect to 1 mol of the polymerization initiator used in the initial polymerization reaction.

  The conjugated diene polymer chain (a1) does not need to contain an aromatic vinyl monomer unit, but preferably contains it. The preferred range of the weight ratio of the conjugated diene monomer unit to the aromatic vinyl monomer unit (conjugated diene monomer unit aromatic vinyl monomer unit) in the conjugated diene polymer chain (a1) is as described above. The same as the portion other than the isoprene block. Moreover, the preferable range of the vinyl bond content in the conjugated diene monomer unit in the conjugated diene polymer chain (a1) is also the same as the portion other than the above-described isoprene block.

<Modifier (a2)>
The conjugated diene rubber (A) used in the present invention has an active terminal of the conjugated diene polymer chain (a1) obtained as described above, an epoxy group and / or a hydrocarbyloxysilyl group, and The epoxy group and the hydrocarbyloxy group (—OR: where R is a hydrocarbon group or aryl group) contained in the hydrocarbyloxysilyl group react with the modifier (a2) having a total number of 3 or more. Is.

  In the present specification, the “modifier” is a compound having a functional group that reacts with the active end of the conjugated diene polymer chain (a1) in one molecule. However, the functional group to be contained is limited to those having an affinity for silica. In the present invention, the functional group is an epoxy group or a hydrocarbyloxy group contained in a hydrocarbyloxysilyl group.

  The modifier (a2) used to form the structure (a) contained in the conjugated diene rubber of the present invention has an epoxy group and / or a hydrocarbyloxysilyl group, and the epoxy group and the hydrocarbyloxysilyl group If it is a modifier | denaturant whose total number with the hydrocarbyl oxy group contained in group is 3 or more, it will not specifically limit. That is, as the modifier (a2), there are those having 3 or more epoxy groups in the molecule, and hydrocarbyloxy groups having hydrocarbyloxysilyl groups in the molecules and bonded to silicon atoms in the hydrocarbyloxysilyl groups. Those having 3 or more in the molecule can be used, and in addition, both the epoxy group and the hydrocarbyloxysilyl group are included in the molecule, and in one molecule, in the epoxy group and the hydrocarbyloxysilyl group Those having a total number of 3 or more of hydrocarbyloxy groups bonded to silicon atoms can also be used. In the case where the molecule has a hydrocarbyloxysilyl group and the hydrocarbyloxysilyl group has two or more hydrocarbyloxy groups bonded to a silicon atom, the silicon atom having one hydrocarbyloxy group Includes two or more, those having two or more hydrocarbyloxy groups on the same silicon atom, and combinations thereof. When an organic group other than the hydrocarbyloxy group is bonded to the silicon atom of the hydrocarbyloxysilyl group, the organic group is not particularly limited.

  In addition, when the conjugated diene polymer chain (a1) reacts with the modifier (a2) having an epoxy group, at least a part of the epoxy group in the modifier (a2) is ring-opened so that the epoxy group becomes It is considered that a bond is formed between the carbon atom of the ring-opened portion and the active end of the conjugated diene polymer chain (a1). Further, when the conjugated diene polymer chain (a1) reacts with the modifier (a2) having a hydrocarbyloxysilyl group, at least a part of the hydrocarbyloxysilyl group in the hydrocarbyloxysilyl group of the modifier (a2) is removed. By separating, it is considered that a bond between the silicon atom contained in the modifier (a2) and the active end of the conjugated diene polymer chain (a1) is formed.

  By using the modifier (a2) in which the total number of epoxy groups and hydrocarbyloxy groups contained in the hydrocarbyloxysilyl group is 3 or more, the conjugated diene polymer chain (a1) of 3 or more is converted into the modifier. A conjugated diene rubber (A) having a structure (a) bonded through (a2) can be obtained.

  Examples of the hydrocarbyloxysilyl group contained in the modifier (a2) include alkoxysilyl groups such as methoxysilyl group, ethoxysilyl group, propoxysilyl group, butoxysilyl group, and aryloxysilyl groups such as phenoxysilyl group. Can be mentioned. Among these, an alkoxysilyl group is preferable and an ethoxysilyl group is more preferable.

  Examples of the hydrocarbyloxy group contained in the hydrocarbyloxysilyl group contained in the modifier (a2) include alkoxy groups such as methoxy group, ethoxy group, propoxy group and butoxy group, and aryloxy groups such as phenoxy group. Can be mentioned. Among these, an alkoxy group is preferable and an ethoxy group is more preferable.

  The modifier (a2) is preferably a polyorganosiloxane for the reason that the low rolling resistance and the wet performance are more excellent.

  Preferred embodiments of the modifier (a2) include a polyorganosiloxane represented by the following formula (1), a polyorganosiloxane represented by the following formula (2), and a polyorganosiloxane represented by the following formula (3). Examples thereof include siloxane and hydrocarbyloxysilane represented by the following formula (4). Among these, a polyorganosiloxane represented by the following formula (1), a polyorganosiloxane represented by the following formula (2), and a polyorganosiloxane represented by the following formula (3) are preferable. The polyorganosiloxane represented by (1) is more preferable.

In said formula (1), R < ₁ > -R < ₈ > is a C1-C6 alkyl group or a C6-C12 aryl group, and these may mutually be same or different. In the above formula (1), X ₁ and X ₄ are each an alkoxy group having 1 to 5 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, or a group having 4 to 12 carbon atoms containing an epoxy group, or carbon It is a C1-C6 alkyl group or a C6-C12 aryl group, and X < ₁ > and X < ₄ > may be the same or different. In the above formula (1), X ₂ is an alkoxy group having 1 to 5 carbon atoms, a group having 4 to 12 carbon atoms containing an aryl group or an epoxy group, having 6 to 14 carbon atoms. In the above formula (1), X ₃ is a group containing 2 to 20 alkylene glycol repeating units. In said formula (1), m is an integer of 3-200, n is an integer of 0-200, k is an integer of 0-200.

In said formula (2), R < ₉ > -R < ₁₆ > is a C1-C6 alkyl group or a C6-C12 aryl group, and these may mutually be same or different. In the above formula (2), X ₅ ~X ₈ is an alkoxy group having 1 to 5 carbon atoms, a group having 4 to 12 carbon atoms containing an aryl group or an epoxy group, having 6 to 14 carbon atoms, these May be the same or different.

In said formula (3), R < ₁₇ > -R < ₁₉ > is a C1-C6 alkyl group or a C6-C12 aryl group, and these may mutually be same or different. In the above formula (3), X ₉ ~X ₁₁ is an alkoxy group having 1 to 5 carbon atoms, a group having 4 to 12 carbon atoms containing an aryl group or an epoxy group, having 6 to 14 carbon atoms, these May be the same or different. In said formula (3), s is an integer of 1-18.

In the formula (4), R ₂₀ is an alkylene group having 1 to 12 carbon atoms. In the formula (4), R ₂₁ ~R ₂₉ is an alkyl group or an aryl group having 6 to 12 carbon atoms, 1 to 6 carbon atoms, which may be different from be the same as each other. In said formula (4), r is an integer of 1-10.

In the polyorganosiloxane represented by the above formula (1), examples of the alkyl group having 1 to 6 carbon atoms represented by R _{1 to} R ₈ , X ₁ and X ₄ include a methyl group, an ethyl group, and n- Examples include propyl group, isopropyl group, butyl group, pentyl group, hexyl group, and cyclohexyl group. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a methylphenyl group. Among these, a methyl group and an ethyl group are preferable from the viewpoint of production of the polyorganosiloxane itself.

In the polyorganosiloxane represented by the above formula (1), examples of the alkoxy group having 1 to 5 carbon atoms represented by X ₁ , X ₂ and X ₄ include a methoxy group, an ethoxy group, a propoxy group, A propoxy group, a butoxy group, etc. are mentioned. Of these, a methoxy group and an ethoxy group are preferable from the viewpoint of reactivity with the active terminal of the conjugated diene polymer chain (a1).

In the polyorganosiloxane represented by the above formula (1), examples of the aryloxy group having 6 to 14 carbon atoms represented by X ₁ , X ₂ and X ₄ include a phenoxy group and a tolyloxy group. It is done.

In the polyorganosiloxane represented by the above formula (1), the group having 4 to 12 carbon atoms containing an epoxy group represented by X ₁ , X ₂ , and X ₄ is represented by the following formula (5). Group.

The formula (5) in, Z ₁ is an alkylene group or an alkyl arylene group having 1 to 10 carbon atoms, Z ₂ is methylene group, a sulfur atom or an oxygen atom, 2 carbon atoms E is an epoxy group -10 hydrocarbyl groups (hydrocarbon groups). In the above formula (5), * represents a bonding position.

In the group represented by the formula (5) is preferably a Z ₂ is an oxygen atom, Z ₂ is an oxygen atom, and is more preferable E is a glycidyl group, Z ₁ is 3 carbon atoms Are particularly preferred, wherein Z ₂ is an oxygen atom and E is a glycidyl group.

In the polyorganosiloxane represented by the above formula (1), X ₁ and X ₄ are preferably a group having 4 to 12 carbon atoms or an alkyl group having 1 to 6 carbon atoms containing an epoxy group. X ₂ is preferably an epoxy group-containing group having 4 to 12 carbon atoms, X ₁ and X ₄ are alkyl groups having 1 to 6 carbon atoms, and X ₂ is an epoxy group. It is more preferable that it is a C4-C12 group containing group.

In the polyorganosiloxane represented by the above formula (1), the group containing a repeating unit of X ₃ , that is, an alkylene glycol of 2 to 20, is preferably a group represented by the following formula (6).

  In said formula (6), t is an integer of 2-20, P is a C2-C10 alkylene group or alkylarylene group, R is a hydrogen atom or a methyl group, Q is C1-C1. 10 alkoxy groups or aryloxy groups. In the above formula (6), * represents a bonding position. Among these, it is preferable that t is an integer of 2 to 8, P is an alkylene group having 3 carbon atoms, R is a hydrogen atom, and Q is a methoxy group.

  In the polyorganosiloxane represented by the above formula (1), m is preferably an integer of 20 to 150, more preferably 30 to 120, for the reason that low rolling resistance and mechanical strength are more excellent.

  In the polyorganosiloxane represented by the above formula (1), n is preferably an integer of 0 to 150, more preferably an integer of 0 to 120. In the polyorganosiloxane represented by the above formula (1), k is preferably an integer of 0 to 150, more preferably an integer of 0 to 120.

  In the polyorganosiloxane represented by the above formula (1), the total number of m, n, and k is preferably 400 or less, more preferably 300 or less, and particularly preferably 250 or less. . When the total number of m, n, and k is 400 or less, the production of the polyorganosiloxane itself is facilitated, the viscosity is not excessively increased, and the handling is facilitated.

In the polyorganosiloxane represented by the above formula (2), specific examples and preferred embodiments of R _{9 to} R ₁₆ are the same as R _{1 to} R ₈ in the above formula (1). In the polyorganosiloxane represented by the above formula (2), specific examples and preferred embodiments of X _{5 to} X ₈ are the same as X ₂ in the above formula (1).

In the polyorganosiloxane represented by the above formula (3), specific examples and preferred embodiments of R _{17 to} R ₁₉ are the same as R _{1 to} R ₈ in the above formula (1). In the polyorganosiloxane represented by the above formula (3), specific examples and preferred embodiments of X _{9 to} X ₁₁ are the same as X ₂ in the above formula (1).

In the hydrocarbyloxysilane represented by the above formula (4), examples of the alkylene group having 1 to 12 carbon atoms represented by R ₂₀ include a methylene group, an ethylene group, and a propylene group. Among these, a propylene group is preferable.
In the hydrocarbyloxysilane represented by the above formula (4), specific examples and preferred embodiments of R _{21 to} R ₂₉ are the same as R _{1 to} R ₈ in the above formula (1).

  Specific examples of the hydrocarbyloxysilane represented by the above formula (4) include N, N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane and N, N-bis (trimethylsilyl) -3-aminopropyltriethoxy. Examples thereof include silane, N, N-bis (trimethylsilyl) aminoethyltrimethoxysilane, and N, N-bis (trimethylsilyl) aminoethyltriethoxysilane. Among these, it is preferable to use N, N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane and N, N-bis (trimethylsilyl) -3-aminopropyltriethoxysilane.

  Other examples of the modifier (a2) include tetraalkoxysilane compounds such as tetramethoxysilane; hexaalkoxysilane compounds such as bis (trimethoxysilyl) methane; alkylalkoxysilane compounds such as methyltriethoxysilane; vinyltrimethoxy Alkenylalkoxysilane compounds such as Silane; arylalkoxysilane compounds such as phenyltrimethoxysilane; halogenoalkoxysilane compounds such as triethoxychlorosilane; 3-glycidoxyethyltrimethoxysilane, 3-glycidoxybutylpropyltri Epoxy group-containing alkoxysilane compounds such as methoxysilane and bis (3-glycidoxypropyl) dimethoxysilane; sulfur-containing compounds such as bis (3- (triethoxysilyl) propyl) disulfide Coxisilane compounds; amino group-containing alkoxysilane compounds such as bis (3-trimethoxysilylpropyl) methylamine; isocyanate group-containing alkoxysilane compounds such as tris (3-trimethoxysilylpropyl) isocyanurate; tetraglycidyl-1,3- And epoxy group-containing compounds such as bisaminomethylcyclohexane.

  A modifier | denaturant (a2) may be used individually by 1 type, and can also be used in combination of 2 or more type.

  Although the usage-amount of modifier | denaturant (a2) is not specifically limited, The modifier in the modifier | denaturant (a2) which reacts with the active terminal of a conjugated diene type polymer chain (a1) with respect to the mole number of the polymerization initiator used for polymerization reaction. The ratio of the total number of moles of the epoxy group and the hydrocarbyloxy group contained in the hydrocarbyloxysilyl group is usually from 0.1 to 5, and the reason why the low rolling resistance and mechanical strength are more excellent is 0. It is preferable that it is 5-3.

  The conjugated diene polymer chain (a1) is a polymerization terminator other than the polymerization terminator and the modifier (a2), as long as the effect of the present invention is not inhibited before the above-described modifier (a2) is reacted. A coupling agent or the like may be added to the polymerization system to inactivate a part of the active end of the conjugated diene polymer chain (a1).

  Examples of the polymerization terminal modifier and coupling agent used at this time include N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, and N-methyl-ε-caprolactam. N-substituted cyclic amides; N-substituted cyclic ureas such as 1,3-dimethylethyleneurea and 1,3-diethyl-2-imidazolidinone; 4,4′-bis (dimethylamino) benzophenone, and N-substituted aminoketones such as 4,4′-bis (diethylamino) benzophenone; aromatic isocyanates such as diphenylmethane diisocyanate and 2,4-tolylene diisocyanate; N, N-dimethylaminopropyl methacrylamide and the like N, N-disubstituted aminoalkylmethacrylamides; 4-N, N-di N-substituted aminoaldehydes such as tilaminobenzaldehyde; N-substituted carbodiimides such as dicyclohexylcarbodiimide; Schiff bases such as N-ethylethylideneimine and N-methylbenzylideneimine; pyridyl group-containing vinyl compounds such as 4-vinylpyridine Tin tetrachloride, silicon tetrachloride, hexachlorodisilane, bis (trichlorosilyl) methane, 1,2-bis (trichlorosilyl) ethane, 1,3-bis (trichlorosilyl) propane, 1,4-bis (trichlorosilyl) And metal halide compounds such as butane, 1,5-bis (trichlorosilyl) pentane, and 1,6-bis (trichlorosilyl) hexane. Among these, it is preferable to use a metal halide compound as a coupling agent because the coupling efficiency is more excellent. A silicon halide compound having 5 or more silicon-halogen atom bonds in one molecule is used as a coupling agent. More preferably, 1,6-bis (trichlorosilyl) hexane is particularly preferably used.

  The amount of the coupling agent used is not particularly limited as long as the effect of the present invention is not impaired. For example, in the case of a halogenated silicon compound having 5 or more silicon-halogen atom bonds in one molecule, the amount used is as follows. The ratio of the number of moles of silicon-halogen atom bonds of the silicon halide compound to the number of moles of the polymerization initiator used in the polymerization reaction is 0.001 to 0.001 because the low rolling resistance and mechanical strength are more excellent. It is preferable that it is 0.25, and it is more preferable that it is 0.01-0.2.

  The said coupling agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  When adding the modifier (a1) and the coupling agent to the solution containing the conjugated diene polymer chain (a2), they are dissolved in an inert solvent from the viewpoint of controlling the reaction well. It is preferable to add to the polymerization system. The solution concentration is preferably in the range of 1 to 50% by mass.

<Conjugated diene rubber (A)>
The conjugated diene rubber (A) contained in the rubber composition of the present invention is a conjugated diene rubber obtained by reacting the conjugated diene polymer chain (a1) with the modifier (a2). Specifically, it contains 5% by mass or more of a structure in which three or more conjugated diene polymer chains (a1) are bonded via a modifier (a2).

  The reaction between the conjugated diene polymer chain (a1) and the modifier (a2) can be performed, for example, by adding the modifier (a2) to a solution containing the conjugated diene polymer chain (a1). it can. The timing for adding the modifier (a2) and the coupling agent is not particularly limited, but the polymerization reaction in the conjugated diene polymer chain (a1) is not completed and the conjugated diene polymer chain (a1) is contained. The solution containing the monomer such as isoprene, more specifically, the solution containing the conjugated diene polymer chain (a1) is preferably 100 ppm or more, more preferably 300 to 50,000 ppm. It is desirable to add a modifier (a2), a coupling agent, and the like to this solution in a state where the monomer is contained. By adding a modifier (a2), a coupling agent, etc., the side reaction between the conjugated diene polymer chain (a1) and impurities contained in the polymerization system is suppressed, and the reaction is controlled well. Is possible.

  In obtaining conjugated diene rubber (A), when two or more modifiers (a2) and coupling agents are used in combination, the order of adding them to the polymerization system is not particularly limited. Even when the modifying agent (a2) and a silicon halide compound as a coupling agent having 5 or more silicon-halogen atom bonds in one molecule are used in combination, the order of addition is not particularly limited. It is preferable to add the agent prior to the addition of the modifier (a2). By adding in this order, it becomes easy to obtain a highly branched conjugated diene rubber obtained via a coupling agent, and a tire obtained using the highly branched conjugated diene rubber has a steering stability. Better.

  As conditions for reacting the modifier (a2) and the coupling agent, the temperature is usually in the range of 0 to 100 ° C., preferably 30 to 90 ° C., and each reaction time is usually 1 to 1 ° C. The range is 120 minutes, preferably 2 to 60 minutes.

  After the modifier (a2) is reacted with the conjugated diene polymer chain (a1), it is preferable to deactivate the active terminal by adding alcohol such as methanol or water.

  After deactivating the active end of the conjugated diene polymer chain (a1), if desired, an anti-aging agent such as a phenol-based stabilizer, a phosphorus-based stabilizer, a sulfur-based stabilizer, a crumbizing agent, and a scale-inhibiting agent Are added to the polymerization solution, and then the polymerization solvent is separated from the polymerization solution by direct drying and steam stripping to recover the conjugated diene rubber (A). Before separating the polymerization solvent from the polymerization solution, an extending oil may be mixed into the polymerization solution, and the conjugated diene rubber (A) may be recovered as an oil-extended rubber.

  Examples of the extending oil used when the conjugated diene rubber (A) is recovered as an oil-extended rubber include paraffinic, aromatic and naphthenic petroleum softeners, plant softeners, and fatty acids. . When using a petroleum softener, the polycyclic aromatic content is preferably less than 3%. This content is measured by the method of IP346 (the testing method of THE INSTITUTE PETROLEUM, UK). When using the extender oil, the amount used is usually 5 to 100 parts by mass, preferably 10 to 60 parts by mass, more preferably 20 to 50 parts by mass with respect to 100 parts by mass of the conjugated diene rubber (A). It is.

The conjugated diene rubber (A) contains 5% by mass or more of the structure (a) in which three or more conjugated diene polymer chains (a1) are bonded via the modifier (a2), and more preferably. Is contained in an amount of 5 to 40% by mass, particularly preferably 10 to 30% by mass.
The ratio of the structure (a) in which three or more conjugated diene polymer chains (a1) are bonded via the modifier (a2) to the total amount of the conjugated diene rubber (A) finally obtained is expressed as “ It is expressed as “coupling ratio of 3 or more branches (mass%)” (hereinafter also simply referred to as coupling ratio). This can be measured by gel permeation chromatography (polystyrene conversion). From the chart obtained by gel permeation chromatography measurement, the area of the peak portion (s2) having a peak top molecular weight of 2.8 times or more of the peak top molecular weight indicated by the peak with the smallest molecular weight relative to the total elution area (s1). The ratio (s2 / s1) is a coupling rate of three or more branches. When a coupling agent other than the modifying agent (a2) is added before the modification, a sample is taken before the modifying agent (a2) is added, and the coupling agent is measured by measuring GPC. The proportion of the conjugated diene polymer chain bonded only to the monomer can be corrected.

  The weight average molecular weight of the conjugated diene rubber (A) is not particularly limited, but is usually 1,000 to 3,000,000, preferably 100,000 to a value measured by gel permeation chromatography in terms of polystyrene. It is in the range of 2,000,000, more preferably 300,000 to 1,500,000. When the weight average molecular weight is 3,000,000 or less, the silica (C) can be easily blended with the conjugated diene rubber (A), and the scorch property of the rubber composition becomes more excellent. Further, when the weight average molecular weight is 1,000 or more, the low rolling resistance of the obtained tire becomes more excellent.

  The molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the conjugated diene rubber (A) is not particularly limited, but preferably 1.1 to 3.0. More preferably, it is 1.2-2.5, Most preferably, it is 1.3-2.2. When the molecular weight distribution value (Mw / Mn) is 3.0 or less, the resulting tire has more excellent low rolling resistance.

The Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the conjugated diene rubber (A) is not particularly limited, but is usually in the range of 20 to 100, preferably 30 to 90, and more preferably 40 to 85. When the conjugated diene rubber (A) is an oil-extended rubber, the Mooney viscosity of the oil-extended rubber is preferably in the above range.

<Diene rubber>
As described above, the rubber component contained in the rubber composition of the present invention may contain a diene rubber other than the conjugated diene rubber (A).
The diene rubber is not particularly limited, and specific examples thereof include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), aromatic vinyl-conjugated diene copolymer rubber, acrylonitrile-butadiene copolymer. Polymerized rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), chloroprene rubber (CR) and the like can be mentioned. The diene rubber may be a single diene rubber or a combination of two or more diene rubbers.

[Mercapto silane coupling agent (B)]
The rubber composition of the present invention contains a mercapto silane coupling agent (B). The mercapto silane coupling agent (B) has a mercapto group and a hydrolyzable group.

  Examples of the hydrolyzable group include an alkoxy group, a phenoxy group, a carboxyl group, and an alkenyloxy group. Among these, an alkoxy group is preferable because the dispersibility of silica is more excellent and a tire excellent in low rolling resistance and wet performance can be obtained. When the hydrolyzable group is an alkoxy group, the alkoxy group preferably has 1 to 16 carbon atoms, more preferably 1 to 4 carbon atoms. As a C1-C4 alkoxy group, a methoxy group, an ethoxy group, a propoxy group etc. are mentioned, for example.

The mercapto-based silane coupling agent (B) is a mercapto having a polyether chain because the rubber composition of the present invention is more excellent in scorch and a tire having excellent rolling resistance and wet performance can be obtained. A silane coupling agent and / or a mercapto silane coupling agent having a polysiloxane structure (—Si—O—) is preferred.
Here, the polyether chain is a side chain having two or more ether bonds, and specific examples thereof include, for example, a side chain having two or more structural units —R ^a —O—R ^b — in total. Can be mentioned. Here, in the structural unit, R ^a and R ^b are each independently a linear or branched alkylene group, a linear or branched alkenylene group, a linear or branched alkynylene group, Alternatively, it represents a substituted or unsubstituted arylene group.

  As a suitable aspect of the mercapto type | system | group silane coupling agent which has the said polyether chain, the compound represented by following formula (7) is mentioned, for example.

In the above formula (7), R ⁷¹ represents an alkoxy group having 1 to 8 carbon atoms, and among them, the reason why a tire excellent in silica dispersion and excellent in rolling resistance can be obtained. The alkoxy group is preferable. Examples of the alkoxy group having 1 to 3 carbon atoms include a methoxy group and an ethoxy group. A plurality of R ⁷¹ in the case where l is 2 may be the same or different.
In the above formula (7), R ⁷² represents a straight-chain polyether group having 4 to 30 carbon atoms. The polyether group is a group having two or more ether bonds, and specific examples thereof include a group having two or more structural units —R ^a —O—R ^b — in total. Definitions and preferred embodiments of R ^a and R ^b are the same as R ^a and R ^b as described above. A plurality of R ⁷² when m is 2 may be the same or different.
As a suitable aspect of a C4-C30 linear polyether group, group represented by following formula (8) is mentioned.

In the above formula (8), R ⁸¹ represents a linear alkyl group, a linear alkenyl group, or a linear alkynyl group, and among them, a linear alkyl group is preferable. As the linear alkyl group, a linear alkyl group having 1 to 20 carbon atoms is preferable, and a linear alkyl group having 8 to 15 carbon atoms is more preferable. Specific examples of the linear alkyl group having 8 to 15 carbon atoms include octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group and the like, and tridecyl group is particularly preferable.
In the above formula (8), R ⁸² represents a linear alkylene group, a linear alkenylene group, or a linear alkynylene group, and among these, a linear alkylene group is preferable. As said linear alkylene group, a C1-C2 linear alkylene group is preferable and an ethylene group is more preferable.
In said formula (8), p represents the integer of 1-10 and it is preferable that it is 3-7.
In the above formula (8), * indicates a bonding position.

In said formula (7), ^R73 represents a hydrogen atom or a C1-C8 alkyl group.
In the above formula (7), R ⁷⁴ represents an alkylene group having 1 to 30 carbon atoms, among them preferably an alkylene group having 1 to 12 carbon atoms, more preferably an alkylene group having 1 to 5 carbon atoms. Specific examples of the alkylene group having 1 to 5 carbon atoms include a methylene group, an ethylene group, and a propylene group.
In said formula (7), l represents the integer of 1-2 and it is preferable that it is 1. In said formula (7), m represents the integer of 1-2 and it is preferable that it is 2. n represents an integer of 0 to 1, and is preferably 0. l, m, and n satisfy the relationship of l + m + n = 3.

  On the other hand, as a suitable aspect of the mercapto silane coupling agent having the polysiloxane structure, for example, a copolymer having a repeating unit represented by the following formula (9) and a repeating unit represented by the following formula (10): Things.

In the above formulas (9) and (10), R ⁹¹ and R ¹⁰¹ each independently represent an alkylene group having 1 to 5 carbon atoms, and specific examples thereof include a methylene group, an ethylene group, a propylene group, and the like. It is done. Of these, a propylene group is preferred. A plurality of R ⁹¹ and R ¹⁰¹ may be the same or different.
In the above formulas (9) and (10), R ⁹² and R ¹⁰² are each independently a linear or branched alkylene group having 1 to 30 carbon atoms, or a linear or branched carbon group having 2 to 30 carbon atoms. The alkenylene group or the linear or branched alkynylene group having 2 to 30 carbon atoms is preferable, and those having 3 to 20 carbon atoms are preferable. When R ⁹² is a terminal, R ⁹² is a hydrogen atom, a linear or branched alkyl group having 1 to 30 carbon atoms, a linear or branched alkenyl group having 2 to 30 carbon atoms, or a straight chain. It represents a chain or branched alkynyl group having 2 to 30 carbon atoms, and among them, those having 3 to 20 carbon atoms are preferable. If R ¹⁰² is terminated, the definition of R ^102, specific examples and preferred embodiments are the same as above R ^92. A plurality of R ⁹² and R ¹⁰² may be the same or different.
In the above formulas (9) and (10), R ⁹³ and R ¹⁰³ are each independently a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 30 carbon atoms, linear or branched. A alkenyl group having 2 to 30 carbon atoms, a linear or branched alkynyl group having 2 to 30 carbon atoms, a linear or branched alkyl group having 1 to 30 carbon atoms, and a hydroxyl group or a carboxyl group at the terminal Or a linear or branched alkenyl group having 2 to 30 carbon atoms and having a hydroxyl group or a carboxyl group at the terminal. R ¹⁰³ is preferably a group having a hydroxyl group at the terminal. R ⁹² and R ⁹³ may form a ring with R ⁹² and R ¹⁰³ . R ¹⁰² and R ¹⁰³ may form a ring with R ¹⁰² and R ¹⁰³ . A plurality of R ⁹³ and R ¹⁰³ may be the same or different.
R ⁹⁴ represents an alkyl group having 1 to 13 carbon atoms, and among them, an alkyl group having 3 to 10 carbon atoms is preferable. Specific examples of the alkyl group having 3 to 10 carbon atoms include a hexyl group, a heptyl group, and an octyl group. A plurality of R ⁹⁴ may be the same or different.

  The mercapto-based silane coupling agent (B) is more excellent in silica dispersibility of the rubber composition of the present invention, and the above polysiloxane structure is obtained because a tire excellent in low rolling resistance and wet performance can be obtained. The mercapto silane coupling agent having the polyether chain is more preferable than the mercapto silane coupling agent.

  In the rubber composition of the present invention, the content of the mercapto-based silane coupling agent (B) is 0.5 to 20% by mass with respect to the content of silica (C) described later, and has low rolling resistance and From the reason that a tire superior in wet performance is obtained, the content is preferably 2 to 18% by mass, and more preferably 4 to 15% by mass.

[Silica (C)]
The silica (C) contained in the rubber composition of the present invention is not particularly limited, and any conventionally known silica compounded in the rubber composition for uses such as tires can be used.
Examples of the silica (C) include wet silica, dry silica, fumed silica, diatomaceous earth, and the like. As the silica (C), one type of silica may be used alone, or two or more types of silica may be used in combination.

The silica (C) preferably has a cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of 100 to 300 m ² / g, and 150 to 220 m ² , because of its superior wet performance and wear resistance when used as a tire. / G is more preferable.
Here, the CTAB adsorption specific surface area is a surrogate property of the surface area that silica can be used for adsorption with the silane coupling agent, and the amount of CTAB adsorption on the silica surface is JIS K6217-3: 2001 “Part 3: Specific surface area of It is a value measured according to “How to obtain—CTAB adsorption method”.

  In the rubber composition of the present invention, the content of the silica (C) is 5 to 150 parts by mass with respect to 100 parts by mass of the rubber component, and a tire excellent in low rolling resistance is obtained. In order to improve wear resistance and wet performance, the amount is preferably 30 to 140 parts by mass, and more preferably 50 to 135 parts by mass.

[Optional ingredients]
If necessary, the rubber composition of the present invention may further contain an additive within a range that does not impair its effects and purposes.
Examples of the additive include silane coupling agents other than the mercapto-based silane coupling agent (B) contained in the rubber composition of the present invention, fillers other than silica (C) (for example, carbon black), oxidation, and the like. Various additives commonly used in rubber compositions such as zinc, stearic acid, antioxidants, processing aids, aroma oils, liquid polymers, terpene resins, thermosetting resins, vulcanizing agents, vulcanization accelerators Agents.

[Method for producing rubber composition]
The method for producing the rubber composition of the present invention is not particularly limited, and specific examples thereof include, for example, kneading the above-described components using a known method and apparatus (for example, a Banbury mixer, a kneader, a roll, etc.). The method of doing is mentioned.
The rubber composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[Pneumatic tire]
The pneumatic tire of the present invention is a pneumatic tire using the above-described rubber composition of the present invention for a tire tread.
FIG. 1 shows a schematic partial sectional view of a tire representing an example of an embodiment of the pneumatic tire of the present invention, but the pneumatic tire of the present invention is not limited to the embodiment shown in FIG.

In FIG. 1, reference numeral 1 represents a bead portion, reference numeral 2 represents a sidewall portion, and reference numeral 3 represents a tire tread portion.
Further, a carcass layer 4 in which fiber cords are embedded is mounted between the pair of left and right bead portions 1, and the end of the carcass layer 4 extends from the inside of the tire to the outside around the bead core 5 and the bead filler 6. Wrapped and rolled up.
In the tire tread 3, a belt layer 7 is disposed over the circumference of the tire on the outside of the carcass layer 4.
Moreover, in the bead part 1, the rim cushion 8 is arrange | positioned in the part which touches a rim | limb.

  The pneumatic tire of the present invention is not particularly limited except that the rubber composition of the present invention is used for a tread of a pneumatic tire, and can be produced, for example, according to a conventionally known method. Moreover, as gas with which a tire is filled, inert gas, such as nitrogen, argon, helium other than the air which adjusted normal or oxygen partial pressure, can be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

<Production of Conjugated Diene Rubber 1>
To a 100 ml ampule bottle purged with nitrogen, 28 g of cyclohexane and 8.6 mmol of tetramethylethylenediamine were added, and 6.1 mmol of n-butyllithium was further added. Then, 8.0 g of isoprene was slowly added and reacted in an ampoule bottle at 60 ° C. for 120 minutes to obtain an isoprene block (referred to as initiator 1). For this initiator 1, the weight average molecular weight, molecular weight distribution, and vinyl bond content were measured. The measurement results are shown in Table 1.

  Next, in a nitrogen atmosphere, 4000 g of cyclohexane, 357.7 g of 1,3-butadiene and 132.3 g of styrene were charged in an autoclave equipped with a stirrer, and then the whole amount of initiator 1 was added, and polymerization was started at 40 ° C. Ten minutes after the start of polymerization, 195.3 g of 1,3-butadiene and 14.7 g of styrene were continuously added over 60 minutes. The maximum temperature during the polymerization reaction was 60 ° C. After completion of the continuous addition, the polymerization reaction was continued for another 20 minutes, and after confirming that the polymerization conversion was in the range of 95% to 100%, 1,6-bis (trichlorosilyl) hexane 0.08 mmol was then obtained. Was added in the form of a 20% strength by weight cyclohexane solution and allowed to react for 10 minutes. Furthermore, 0.027 mmol of polyorganosiloxane A represented by the following formula (11) was added in the form of a 20% by mass concentration of xylene solution and reacted for 30 minutes. Thereafter, as a polymerization terminator, an amount of methanol corresponding to twice the mole of n-butyllithium used was added to obtain a solution containing the conjugated diene rubber 1. To this solution, 0.15 parts by mass of Irganox 1520L (manufactured by Ciba Specialty Chemicals) as an anti-aging agent was added to 100 parts by mass of the conjugated diene rubber 1, and then the solvent was removed by steam stripping. Then, the solid conjugated diene rubber 1 was obtained by vacuum drying at 60 ° C. for 24 hours.

In the formula _{(11), X 1, X} 4, R 1 ~R 3 and R ₅ to R ₈ is a methyl group. In the above formula (11), m is 80 and n is 120. In the above formula (11), X ₂ is a group represented by the following formula (12) (here, * represents a bonding position).

  For the conjugated diene rubber 1, the weight average molecular weight, molecular weight distribution, coupling rate, styrene unit content, vinyl bond content in portions other than the isoprene block, and Mooney viscosity were measured. The measurement results are shown in Table 2. The measurement method is as follows.

(Weight average molecular weight, molecular weight distribution and coupling rate)
About weight average molecular weight, molecular weight distribution, and coupling rate (ratio (mass%) of structure (a) to conjugated diene rubber (A)), a chart based on molecular weight in terms of polystyrene was obtained by gel permeation chromatography. And based on the chart. The specific measurement conditions for gel permeation chromatography are as follows.

・ Measurement device: HLC-8020 (manufactured by Tosoh Corporation)
Column: GMH-HR-H (manufactured by Tosoh Corporation) connected in series Detector: Differential refractometer RI-8020 (manufactured by Tosoh Company)
-Elution night: Tetrahydrofuran-Column temperature: 40 ° C

  Here, the coupling rate is the ratio of the area (s2) of the peak portion having a peak top molecular weight of 2.8 times or more of the peak top molecular weight indicated by the smallest peak of molecular weight to the total elution area (s1) (s2 / s1).

(Styrene unit content and vinyl bond content)
The styrene unit content and the vinyl bond content were measured by ¹ H-NMR.

(Mooney viscosity)
The Mooney viscosity (ML _{1 + 4} (100 ° C.)) was measured according to JIS K6300-1: 2001.

<Production of Conjugated Diene Rubber 2>
To a 100 ml ampoule bottle purged with nitrogen, 28 g of cyclohexane and 7.5 mmol of tetramethylethylenediamine were added, and 5.4 mmol of n-butyllithium was further added. Next, 7.0 g of isoprene was slowly added and reacted in an ampoule bottle at 70 ° C. for 120 minutes to obtain an isoprene block (referred to as initiator 2). For this initiator 2, the weight average molecular weight, molecular weight distribution, and vinyl bond content were measured. The measurement results are shown in Table 1.

  Next, in a nitrogen atmosphere, 4000 g of cyclohexane, 357.7 g of 1,3-butadiene and 132.3 g of styrene were charged in an autoclave equipped with a stirrer, and then the whole amount of initiator 2 was added, and polymerization was started at 40 ° C. Ten minutes after the start of polymerization, 195.3 g of 1,3-butadiene and 14.7 g of styrene were continuously added over 60 minutes. The maximum temperature during the polymerization reaction was 60 ° C. After completion of the continuous addition, the polymerization reaction was continued for another 20 minutes. After confirming that the polymerization conversion was in the range of 95% to 100%, the polyorganosiloxane A0 represented by the above formula (11) was then used. 0.023 mmol was added in the form of a 20% strength by weight xylene solution and allowed to react for 30 minutes. Thereafter, as a polymerization terminator, an amount of methanol corresponding to twice the mole of n-butyllithium used was added to obtain a solution containing the conjugated diene rubber 2. To this solution, 0.15 parts by mass of Irganox 1520L (manufactured by Ciba Specialty Chemicals) as an antioxidant is added to 100 parts by mass of the conjugated diene rubber 2, and then the solvent is removed by steam stripping. The solid conjugated diene rubber 2 was obtained by vacuum drying at 60 ° C. for 24 hours.

  For the conjugated diene rubber 2, the weight average molecular weight, molecular weight distribution, coupling rate, styrene unit content, vinyl bond content, and Mooney viscosity were measured. The measurement results are shown in Table 2. In addition, it is as a measuring method and the above-mentioned.

<Production of Conjugated Diene Rubber 3>
To a 100 ml ampoule bottle purged with nitrogen, 50 g of cyclohexane and 0.9 mmol of tetramethylethylenediamine were added, and 5.4 mmol of n-butyllithium was further added. Next, 9.0 g of isoprene was slowly added and reacted in an ampoule bottle at 70 ° C. for 120 minutes to obtain an isoprene block (referred to as initiator 3). For this initiator 3, the weight average molecular weight, molecular weight distribution, and vinyl bond content were measured. The measurement results are shown in Table 1.

  Next, in a nitrogen atmosphere, 4000 g of cyclohexane, 357.7 g of 1,3-butadiene and 132.3 g of styrene were charged in an autoclave equipped with a stirrer, and then the whole amount of initiator 3 was added, and polymerization was started at 40 ° C. After 10 minutes from the start of polymerization, 195.3 g of 1,3-butadiene and 14.7 g of styrene were continuously added over 60 minutes. The maximum temperature during the polymerization reaction was 60 ° C. After completion of the continuous addition, the polymerization reaction was continued for another 20 minutes. After confirming that the polymerization conversion was in the range of 95% to 100%, the polyorganosiloxane A0 represented by the above formula (11) was then used. 0.023 mmol was added in the form of a 20% strength by weight xylene solution and allowed to react for 30 minutes. Thereafter, as a polymerization terminator, an amount of methanol corresponding to twice the mole of n-butyllithium used was added to obtain a solution containing the conjugated diene rubber 3. Irganox 1520L (manufactured by Ciba Specialty Chemicals) was added to this solution as an anti-aging agent in an amount of 0.15 parts by mass with respect to 100 parts by mass of the conjugated diene rubber 3, and the solvent was removed by steam stripping. Then, it was vacuum dried at 60 ° C. for 24 hours to obtain a solid conjugated diene rubber 3.

  The conjugated diene rubber 3 was measured for weight average molecular weight, molecular weight distribution, coupling rate, styrene unit content, vinyl bond content and Mooney viscosity. The measurement results are shown in Table 2. In addition, it is as a measuring method and the above-mentioned.

<Manufacture of Conjugated Diene Rubber 4>
To a 100 ml ampoule bottle purged with nitrogen, 50 g of cyclohexane and 7.0 mmol of tetramethylethylenediamine were added, and 5.1 mmol of n-butyllithium was further added. Next, 10.2 g of isoprene was slowly added and reacted for 120 minutes in an ampoule bottle at 60 ° C. to obtain an isoprene block (referred to as initiator 4). For this initiator 4, the weight average molecular weight, molecular weight distribution, and vinyl bond content were measured. The measurement results are shown in Table 1.

  Next, in a nitrogen atmosphere, 4000 g of cyclohexane, 357.7 g of 1,3-butadiene and 132.3 g of styrene were charged in an autoclave equipped with a stirrer, and then the whole amount of initiator 4 was further added, and polymerization was started at 40 ° C. After 10 minutes from the start of polymerization, 195.3 g of 1,3-butadiene and 14.7 g of styrene were continuously added over 60 minutes. The maximum temperature during the polymerization reaction was 60 ° C. After completion of the continuous addition, the polymerization reaction was continued for another 20 minutes, and after confirming that the polymerization conversion was in the range of 95% to 100%, N, N-bis (trimethylsilyl) -3-aminopropyl was then obtained. 0.55 mmol of triethoxysilane was added in the form of a 20% by mass concentration xylene solution and reacted for 10 minutes. Thereafter, as a polymerization terminator, an amount of methanol corresponding to twice the mole of n-butyllithium used was added to obtain a solution containing the conjugated diene rubber 4. Irganox 1520L (manufactured by Ciba Specialty Chemicals) as an anti-aging agent was added to this solution in an amount of 0.15 parts by mass with respect to 100 parts by mass of the conjugated diene rubber 4, and the solvent was removed by steam stripping. Then, it was vacuum dried at 60 ° C. for 24 hours to obtain a solid conjugated diene rubber 4.

  The conjugated diene rubber 4 was measured for weight average molecular weight, molecular weight distribution, coupling rate, styrene unit content, vinyl bond content and Mooney viscosity. The measurement results are shown in Table 2. In addition, it is as a measuring method and the above-mentioned.

<Examples 1 to 10, Comparative Examples 1 to 5>
The components shown in Table 3 below were blended in the proportions (parts by mass) shown in Table 3 below.
Specifically, first, the components excluding sulfur and the vulcanization accelerator among the components shown in Table 3 below were raised to around 150 ° C. using a 1.7 liter closed Banbury mixer, and then 5 After mixing for a minute, it was discharged and cooled to room temperature to obtain a masterbatch. Furthermore, using the Banbury mixer, sulfur and a vulcanization accelerator were mixed with the obtained master batch to obtain a rubber composition.

<Mooney viscosity> (Scorch index)
For the prepared rubber composition (unvulcanized), Mooney was used in accordance with JIS K6300-1: 2001, using an L-shaped rotor, with a preheating time of 1 minute, a rotor rotation time of 4 minutes, and a test temperature of 100 ° C. The viscosity was measured. The results are shown in Table 3. The results were expressed as an index with the Mooney viscosity of Comparative Example 1 as 100. A smaller value indicates better scorch (workability).

<Tan δ (0 ° C.)> (Wet performance index)
The prepared rubber composition (unvulcanized) was press vulcanized at 160 ° C. for 20 minutes in a mold (15 cm × 15 cm × 0.2 cm) to prepare a vulcanized rubber sheet.
About the produced vulcanized rubber sheet, in accordance with JIS K6394: 2007, using a viscoelastic spectrometer (manufactured by Iwamoto Seisakusho Co., Ltd.) under the conditions of 10% ± 2% elongation deformation strain rate, frequency 20 Hz, temperature 0 ° C. , Tan δ (0 ° C.) was measured.
The results are shown in Table 3. The results were expressed as an index with tan δ (0 ° C.) of Comparative Example 1 as 100. The larger the index, the larger the tan δ (0 ° C.), and the better the wet performance when made into a tire.

<Tan δ (60 ° C.)> (Index of low rolling resistance)
The prepared rubber composition (unvulcanized) was press vulcanized at 160 ° C. for 20 minutes in a mold (15 cm × 15 cm × 0.2 cm) to prepare a vulcanized rubber sheet.
About the produced vulcanized rubber sheet, in accordance with JIS K6394: 2007, using a viscoelastic spectrometer (manufactured by Iwamoto Seisakusho Co., Ltd.) under the conditions of an elongation deformation strain rate of 10% ± 2%, a frequency of 20 Hz and a temperature of 60 ° C. , Tan δ (60 ° C.) was measured.
The results are shown in Table 3. The results were expressed as an index with tan δ (60 ° C.) of Comparative Example 1 as 100. The smaller the index, the smaller the tan δ (60 ° C.), and the lower the rolling resistance when the tire is made.

Details of each component shown in Table 3 are as follows.
Conjugated diene rubber 1: Conjugated diene rubber 1 produced as described above
Conjugated diene rubber 2: Conjugated diene rubber 2 produced as described above
Conjugated diene rubber 3: Conjugated diene rubber 3 produced as described above
Conjugated diene rubber 4: Conjugated diene rubber 4 produced as described above
Comparative conjugated diene rubber 1: NS616 (manufactured by ZEON Corporation) (terminal modified SSBR for silica)
-Butadiene rubber: Nipol 1220 (manufactured by Nippon Zeon)
Silica 1: Zeosil 1165MP (CTAB adsorption specific surface area = 160 m ² / g, manufactured by Rhodia)
Carbon black: Show black N339 (CTAB adsorption specific surface area = 90 m ² / g, manufactured by Cabot Japan)
Comparative silane coupling agent 1: Si69 (Evonik Degussa) (bis (3-triethoxysilylpropyl) tetrasulfide)
Silane coupling agent 1: VP Si363 (manufactured by Evonik Degussa) (compound represented by the above formula (7). Here, R ⁷¹ : —OC ₂ H ₅ , R ⁷² : —O (C ₂ H ₄ O) ₅ —C ₁₃ H ₂₇ , R ⁷⁴ : — (CH ₂ ) ₃ —, l = 1, m = 2, n = 0.)
Silane coupling agent 2: NXT-Z45 (manufactured by Momentive) (a copolymer having a repeating unit represented by the above formula (9) and a repeating unit represented by the above formula (10). (The ratio of the repeating unit represented by (9) is 55 mol%, and the ratio of the repeating unit represented by the above formula (10) is 45 mol%.)
Silane coupling agent 3: KBM-803 (manufactured by Shin-Etsu Chemical) (γ-mercaptopropyltrimethoxysilane)
・ Zinc oxide: 3 types of zinc oxide (manufactured by Shodo Chemical Industry Co., Ltd.)
・ Stearic acid: Stearic acid YR (manufactured by NOF Corporation)
Anti-aging agent: Santoflex 6PPD (manufactured by Solutia Europe)
・ Wax: Paraffin wax (Ouchi Shinsei Chemical Co., Ltd.)
・ Process oil: Extract No. 4 S (made by Showa Shell Sekiyu KK)
・ Sulfur: Oil-treated sulfur (manufactured by Tsurumi Chemical Co., Ltd.)
・ Vulcanization accelerator 1: Noxeller CZ-G (Ouchi Shinsei Chemical Co., Ltd.)
・ Vulcanization accelerator 2: Perkacit DPG (manufactured by Flexsys)

As can be seen from Table 3, the mercapto-based silane coupling agent (B) is contained, but the conjugated diene rubber (A) containing the structure (a) is not contained (the conjugated diene not containing the structure (a)). Compared with Comparative Example 1 (containing a rubber), Examples 1 to 10 of the present application in which the conjugated diene rubber (A) containing the structure (a) and the mercapto silane coupling agent (B) were used in combination, Excellent characteristics were exhibited in all of the points of low rolling resistance, wet performance and scorch.
Among these, as the mercapto silane coupling agent (B), a mercapto silane coupling agent having a polyether chain and / or a mercapto silane coupling agent having a polysiloxane structure (—Si—O—) is used. Examples 1 to 8 showed a tendency to exhibit better characteristics in any of the low rolling resistance, the wet performance, and the scorch property. Among them, Examples 1 to 4 using a mercapto-based silane coupling agent having a polyether chain as the mercapto-based silane coupling agent (B) are more excellent in both wet performance and scorch properties. The tendency which shows was seen.
From the comparison of Examples 1 to 4, the comparison of Examples 5 to 8, and the comparison of Examples 9 and 10, Examples 1 to 3 and Examples 5 to 7 using polyorganosiloxane as the modifier (a2). And, Example 9 showed better wet performance and low rolling resistance. Among them, Examples 1, 5 and 9 using a coupling agent showed further excellent wet performance and low rolling resistance.
From the comparison of Examples 1 to 4, the comparison of Examples 5 to 8, and the comparison of Examples 9 and 10, Examples 1, 5 and 9 in which the vinyl bond content in the isoprene block is 70% by mass or more are as follows: Excellent wet performance and low rolling resistance.

On the other hand, Comparative Example 3 containing the conjugated diene rubber (A) containing the structure (a) but not containing the mercapto silane coupling agent (B) (containing a non-mercapto silane coupling agent) Although the scorch property was excellent, it was inferior to the examples of the present application in terms of low rolling resistance and wet performance.
Further, the conjugated diene rubber (A) containing the structure (a) and the mercapto silane coupling agent (B) are used in combination, and the content of the mercapto silane coupling agent (B) is silica (C). Although the comparative example 4 exceeding 20 mass% with respect to content is excellent in low rolling resistance, it was inferior to the Example of this application in the point of scorch property and wet performance.
Further, the conjugated diene rubber (A) containing the structure (a) and the mercapto silane coupling agent (B) are used in combination, and the content of the mercapto silane coupling agent (B) is silica (C). Although the comparative example 5 which is less than 0.5 mass% with respect to content is excellent in scorch property, it was inferior to the present Example in the point of low rolling resistance and wet performance.

As can be seen from the comparison between Comparative Example 1 and Comparative Example 2, when a non-mercapto silane coupling agent is used as the silane coupling agent, a conjugated diene rubber (A) containing the structure (a) as the conjugated diene rubber (A) ) Showed little improvement in low rolling resistance and wet performance.
On the other hand, as can be seen from the comparison between Comparative Example 1 and Examples of the present application, when the mercapto silane coupling agent (B) is used as the silane coupling agent, the conjugate containing the structure (a) as the conjugated diene rubber. By using the diene rubber (A), all the characteristics of rolling resistance, wet performance and scorch property were improved.

1 Bead part 2 Side wall part 3 Tire tread part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Rim cushion

Claims (4)

A rubber component containing 10% by mass or more of the conjugated diene rubber (A), a mercapto silane coupling agent (B), and silica (C);
Three or more conjugated diene copolymer chains (a1) obtained by reacting the conjugated diene rubber (A) with a conjugated diene copolymer chain (a1) and a modifier (a2) Containing 5 mass% or more of the structure (a) formed by bonding via the modifier (a2),
The conjugated diene copolymer chain (a1) is a conjugated diene copolymer chain having an isoprene block containing 70% by mass or more of isoprene units at one end and an active terminal at the other end. ,
The modifier (a2) is a modifier having an epoxy group and / or a hydrocarbyloxysilyl group, and the total number of the epoxy group and the hydrocarbyloxy group contained in the hydrocarbyloxysilyl is 3 or more. ,
The content of the mercapto silane coupling agent (B) is 0.5 to 20% by mass with respect to the content of the silica (C),
The rubber composition whose content of the said silica (C) is 5-150 mass with respect to 100 mass parts of said rubber components. The mercapto-based silane coupling agent (B) is a compound represented by the following formula (7) and / or a repeating unit represented by the following formula (9) and a repeating unit represented by the following formula (10). The rubber composition according to claim 1, which is a copolymer having
(In formula (7), R ⁷¹ represents an alkoxy group having 1 to 8 carbon atoms. R ⁷² represents a linear polyether group having 4 to 30 carbon atoms. R ⁷³ represents a hydrogen atom or a carbon atom. .R ⁷⁴ representing the number 1-8 alkyl group represents an integer of .l 1-2 representing an alkylene group having 1 to 30 carbon atoms, m represents an integer of 1-2, n is 0-1 Represents an integer, and l, m, and n satisfy a relational expression of l + m + n = 3, and a plurality of R ⁷¹ in the case where l is 2 may be the same or different from each other. The plurality of R ⁷² may be the same or different.)
(In formulas (9) and (10), R ⁹¹ and R ¹⁰¹ each independently represents an alkylene group having 1 to 5 carbon atoms.
R ⁹² and R ¹⁰² are each independently a linear or branched alkylene group having 1 to 30 carbon atoms, a linear or branched alkenylene group having 2 to 30 carbon atoms, or a linear or branched group. Represents a alkynylene group having 2 to 30 carbon atoms. When R ⁹² is a terminal, R ⁹² is a hydrogen atom, a linear or branched alkyl group having 1 to 30 carbon atoms, a linear or branched alkenyl group having 2 to 30 carbon atoms, or a straight chain. A chain or branched alkynyl group having 2 to 30 carbon atoms is represented. When ^R102 is a terminal, ^R102 is a hydrogen atom, a linear or branched alkyl group having 1 to 30 carbon atoms, a linear or branched alkenyl group having 2 to 30 carbon atoms, or a straight chain. A chain or branched alkynyl group having 2 to 30 carbon atoms is represented.
R ⁹³ and R ¹⁰³ each independently represents a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 30 carbon atoms, a linear or branched alkenyl group having 2 to 30 carbon atoms, A linear or branched alkynyl group having 2 to 30 carbon atoms, a linear or branched alkyl group having 1 to 30 carbon atoms and having a hydroxyl group or a carboxyl group at the terminal, or linear or branched A alkenyl group having 2 to 30 carbon atoms and having a hydroxyl group or a carboxyl group at its terminal.
R ⁹² and R ⁹³ may form a ring with R ⁹² and R ⁹³ .
R ¹⁰² and R ¹⁰³ may form a ring with R ¹⁰² and R ¹⁰³ .
R ⁹⁴ represents an alkyl group having 1 to 13 carbon atoms.
A plurality of R ⁹¹ , R ⁹² , R ⁹³ , R ⁹⁴ , R ¹⁰¹ , R ¹⁰² and R ¹⁰³ may be the same or different. )   The rubber composition according to claim 1 or 2, wherein the modifier (a2) is a polyorganosiloxane.   A pneumatic tire using the rubber composition according to claim 1 for a tire tread.