JP6993918B2 - Method for manufacturing modified conjugated diene rubber - Google Patents

Description

The present invention relates to a modified conjugated diene rubber and a method for producing the same. More specifically, the present invention has excellent processability when a filler such as silica is blended, and has low heat generation property, wet grip property, wear resistance and steering stability. The present invention relates to a modified conjugated diene-based rubber capable of giving a rubber crosslinked product having excellent properties, and a method for producing the same. The present invention also relates to a rubber composition containing the modified conjugated diene-based rubber and a rubber crosslinked product thereof.

In recent years, due to environmental problems and resource problems, low heat generation is strongly required for automobile tires. A tire obtained from a rubber composition containing silica is superior in heat generation to a tire obtained from a rubber composition containing carbon black, which is usually used. Therefore, a tire having low fuel consumption can be manufactured by using this. can do. However, on the other hand, even if a commonly used rubber is blended with silica, it is easy to separate because of its inferior affinity with silica, and as a result, there is a possibility that fuel efficiency is inferior.

In such a rubber composition, in order to enhance the affinity between rubber and silica, a technique for introducing a functional group having a high affinity for silica by reacting a modifier with a polymerization active terminal of rubber or the like is known. Has been done. For example, Patent Document 1 examines a technique for giving a rubber itself an affinity for silica by reacting a modifier with the active terminal of the polymer when a rubber polymer is obtained by a solution polymerization method. ing.

Japanese Unexamined Patent Publication No. 2005-290355

On the other hand, in view of the increasing demand for automobile tires in recent years, the tires newly developed in the future have lower heat generation and wetness than the case of using conventional rubber such as the rubber described in Patent Document 1. It is required to be more excellent in grip, wear resistance and steering stability.

The present invention has been made in view of such an actual situation, and is excellent in processability when a filler such as silica is blended, and has low heat generation property, wet grip property, wear resistance and steering stability. It is an object of the present invention to provide a method for producing a conjugated diene-based rubber capable of giving an excellent rubber crosslinked product.

As a result of diligent research to achieve the above object, the present inventors react the active end of the conjugated diene polymer chain having an active end with a denaturing agent having a functional group capable of interacting with silica. Next, the modified conjugated diene rubber obtained by further reacting the alkylthiol compound with the conjugated diene polymer chain reacted with the modifier using a radical initiator is mixed with a filler such as silica. We have found that it is possible to provide a rubber crosslinked product having excellent workability, low heat generation property, wet grip property, abrasion resistance and steering stability, and have completed the present invention.

That is, according to the present invention, a first, a conjugated diene-based polymer chain having an active end is obtained by polymerizing a monomer containing at least a conjugated diene compound in an inert solvent using a polymerization initiator. By reacting the step and the active end of the conjugated diene polymer chain having the active end with a modifier having a functional group capable of interacting with silica, the conjugated diene polymer having a modifying group at the end is reacted. Production of a modified conjugated diene-based rubber comprising a second step of obtaining a chain and a third step of reacting an alkylthiol compound with the conjugated diene-based polymer chain having a modifying group at the terminal using a radical initiator. The method is provided.
In the method for producing a modified conjugated diene rubber of the present invention, it is preferable that the modifying agent is a silicon compound.

Further, according to the present invention, there is provided a modified conjugated diene-based rubber obtained by any of the above production methods.
Further, according to the present invention, there is provided a rubber composition containing 10 to 200 parts by weight of silica with respect to 100 parts by weight of the rubber component containing the modified conjugated diene rubber.
The rubber composition of the present invention preferably further contains a cross-linking agent.

Further, according to the present invention, there is provided a rubber crosslinked product obtained by cross-linking the rubber composition and a tire containing the rubber cross-linked product.

According to the present invention, a modified rubber crosslinked product having excellent processability when a filler such as silica is blended and having excellent low heat generation property, wet grip property, abrasion resistance and steering stability can be provided. A conjugated diene-based rubber, a rubber composition containing the modified conjugated diene-based rubber, and a rubber obtained by using the rubber composition and having excellent low heat generation property, wet grip property, abrasion resistance and steering stability. A crosslinked product can be provided.

<Manufacturing method of modified conjugated diene rubber>
The method for producing a modified conjugated diene rubber of the present invention is
The first step of polymerizing a monomer containing at least a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene-based polymer chain having an active terminal.
By reacting the active end of the conjugated diene polymer chain having an active end with a modifying agent having a functional group capable of interacting with silica, a conjugated diene polymer chain having a modifying group at the end is obtained. The second step and
The present invention comprises a third step of reacting an alkylthiol compound with a conjugated diene-based polymer chain having a modifying group at the terminal using a radical initiator.

<First step>
First, the first step in the manufacturing method of the present invention will be described. In the first step in the production method of the present invention, a monomer containing at least a conjugated diene compound is polymerized in an inert solvent using a polymerization initiator to obtain a conjugated diene-based polymer chain having an active terminal. This is the process of obtaining.

In the first step, the conjugated diene compound used for polymerization in order to obtain a conjugated diene-based polymer chain having an active terminal is not particularly limited, and is, for example, 1,3-butadiene, isoprene, 2,3-dimethyl-. 1,3-butadiene, 1,3-pentadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-cyclohexadiene, etc. Can be mentioned. Among these, 1,3-butadiene, isoprene and 1,3-pentadiene are preferable, and 1,3-butadiene and isoprene are particularly preferable. In addition, these conjugated diene compounds may be used individually by 1 type, and may be used in combination of 2 or more types.

Further, in the production method of the present invention, the conjugated diene-based polymer chain having an active terminal to be produced in the first step is obtained by copolymerizing an aromatic vinyl compound in addition to the conjugated diene compound. You may. The aromatic vinyl compound is not particularly limited, and is, for example, 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-butyl-2-methylstyrene, vinylnaphthalene, dimethylaminomethylstyrene, dimethylaminoethylstyrene and the like. Can be done. Among these, styrene, α-methylstyrene, and 4-methylstyrene are preferable, and styrene is particularly preferable. note that. These aromatic vinyl compounds may be used alone or in combination of two or more. The conjugated diene-based polymer chain having an active terminal produced in the first step preferably contains 45 to 100% by weight of the conjugated diene monomer unit, more preferably 50 to 100% by weight, and 55 to 100% by weight. Those containing 95% by weight are particularly preferable, those containing 0 to 55% by weight of the aromatic vinyl monomer unit are preferable, those containing 0 to 50% by weight are further preferable, and those containing 5 to 45% by weight. Is particularly preferable.

Further, in the production method of the present invention, the conjugated diene-based polymer chain having an active terminal is, if desired, in addition to the conjugated diene compound and the aromatic vinyl compound, other than these, as long as the object of the present invention is not impaired. It may be obtained by copolymerizing other monomers. 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 and acrylic. Unsaturated carboxylic acid esters such as ethyl acid, butyl acrylate; unconjugated diene such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadien, dicyclopentadiene, 5-ethylidene-2-norbornene; etc. Can be mentioned. The amount of these other monomers is preferably 10% by weight or less, more preferably 5% by weight or less, as a monomer unit in the conjugated diene-based polymer chain having an active terminal.

The inert solvent used in the first step of the production method of the present invention is usually used in solution polymerization and is not particularly limited as long as it does not inhibit the polymerization reaction. Specific examples of the inert solvent include chain aliphatic hydrocarbons such as butane, pentane, hexane, heptane, and 2-butene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and cyclohexene; benzene, toluene, xylene, and the like. Aromatic hydrocarbons; ether compounds such as tetrahydrofuran and diethyl ether; and the like. These inert solvents may be used alone or in combination of two or more. The amount of the inert solvent used is such that the monomer concentration is, for example, 1 to 50% by weight, preferably 10 to 40% by weight.

The polymerization initiator is not particularly limited as long as it can provide a conjugated diene-based polymer chain having an active terminal by polymerizing each of the above-mentioned monomers. As a specific example thereof, a polymerization initiator having an organic alkali metal compound, an organic alkaline earth metal compound, a lanthanum series metal compound or the like as a main catalyst is preferably used. Examples of the organic alkali metal compound include organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium and stelvenelithium; dilithiomethane, 1,4-dilithiobtan, 1,4. -Organic polyvalent lithium compounds such as dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, 1,3,5-tris (lithiomethyl) benzene; organic sodium compounds such as sodium naphthalene; organic such as potassium naphthalene Potassium compounds; and the like. Examples of the organic alkaline earth metal compound include di-n-butylmagnesium, di-n-hexylmagnesium, diethoxycalcium, calcium distearate, dit-butoxystrontium, diethoxybarium, and diisopropoxybarium. , Diethyl mercaptobarium, dit-butoxybarium, diphenoxybarium, diethylaminobarium, barium distearate, diketylbarium and the like. Examples of the polymerization initiator using a lanthanum-series metal compound as a main catalyst include a lanthanum-series metal such as lanthanum, cerium, placeodim, neodym, samarium, and gadrinium, and a lanthanum-series metal composed of a carboxylic acid and a phosphorus-containing organic acid. Examples thereof include a polymerization initiator composed of a salt of the above as a main catalyst and a co-catalyst such as an alkylaluminum compound, an organic aluminum hydride compound, and an organic aluminum halide compound. Among these polymerization initiators, an organic monolithium compound and an organic polyvalent lithium compound are preferable, an organic monolithium compound is more preferable, and n-butyl lithium is particularly preferable. The organic alkali metal compound is previously reacted with a secondary amine such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, hexamethyleneimine, and heptamethyleneimine to be used as an organic alkali metal amide compound. May be good. These polymerization initiators may be used alone or in combination of two or more.

The amount of the polymerization initiator used may be determined according to the molecular weight of the target polymer, but is usually 1 to 50 mmol, preferably 1.5 to 20 mmol, more preferably 2 per 1000 g of the monomer. It is in the range of ~ 15 mmol.

The polymerization temperature in the first step of the production method of the present invention is usually in the range of −80 to + 150 ° C., preferably 0 to 100 ° C., and more preferably 30 to 90 ° C. As the polymerization mode, any mode such as batch type or continuous type can be adopted, but when the conjugated diene compound and the aromatic vinyl compound are copolymerized, the conjugated diene monomer unit and the aromatic vinyl monomer are used. The batch formula is preferable because it is easy to control the randomness of the combination with the unit.

In the production method of the present invention, when the conjugated diene-based polymer chain having an active terminal is composed of two or more kinds of monomer units, the bonding mode thereof is, for example, block-like, tapered-like, random-like, or the like. Although various binding modes can be used, a random binding mode is preferable. By making it random, the obtained rubber crosslinked product is particularly excellent in low heat generation.

Further, in the production method of the present invention, in order to adjust the vinyl bond content in the conjugated diene monomer unit in the conjugated diene polymer chain having an active terminal, a polar compound is added to the inert organic solvent during the polymerization. It is preferable to add it. Examples of the polar compound include ether compounds such as dibutyl ether and tetrahydrofuran; tertiary amines such as tetramethylethylenediamine; alkali metal alkoxides; phosphine compounds; and the like. Among these, ether compounds and tertiary amines are preferable, tertiary amines are more preferable, and tetramethylethylenediamine is particularly preferable. These polar compounds may be used alone or in combination of two or more. The amount of the polar compound to be used may be determined according to the desired vinyl bond content, preferably 0.001 to 100 mol, more preferably 0.01 to 10 mol, based on 1 mol of the polymerization initiator. be. When the amount of the polar compound used is in this range, the vinyl bond content in the conjugated diene monomer unit can be easily adjusted, and problems due to deactivation of the polymerization initiator are unlikely to occur.

As described above, according to the first step in the production method of the present invention, a conjugated diene-based polymer chain having an active terminal can be obtained by polymerizing a monomer containing a conjugated diene compound. ..

The vinyl bond content (vinyl bond unit amount) in the conjugated diene monomer unit in the conjugated diene polymer chain having an active terminal obtained in the first step of the production method of the present invention is preferably 5 to 80% by weight. It is more preferably 10 to 70% by weight. When the vinyl bond amount is in the above range, the obtained rubber crosslinked product is particularly excellent in low heat generation. Further, since the vinyl bond portion in the conjugated diene monomer unit becomes a portion that reacts with the alkylthiol compound in the third step described later, by setting the vinyl bond amount within the above range, in the third step described later. , The modification reaction with the alkylthiol compound can be more preferably carried out, whereby the modification effect by the alkylthiol compound, that is, the processability when a filler such as silica is blended, and the obtained rubber crosslinked product are low. Heat generation, wet grip, wear resistance and steering stability can be improved more appropriately.

The peak top molecular weight detected by gel permeation chromatography (hereinafter, also referred to as GPC) of the conjugated diene-based polymer chain having an active terminal obtained in the first step of the production method of the present invention is a polystyrene-equivalent value. It is preferably 100,000 to 1,000,000, more preferably 150,000 to 900,000, and particularly preferably 150,000 to 800,000. When a plurality of peaks of the conjugated diene polymer chain are observed, the peak top molecular weight of the peak having the smallest molecular weight derived from the conjugated diene polymer chain detected by GPC is used as the peak top molecular weight of the conjugated diene system having an active end. The peak top molecular weight of the polymer chain. When the peak top molecular weight of the conjugated diene polymer chain having an active end is in the above range, the obtained rubber crosslinked product is particularly excellent in low heat generation and wear resistance.

The molecular weight distribution expressed 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 having an active terminal obtained in the first step of the production method of the present invention is It is preferably 1.0 to 1.5, more preferably 1.0 to 1.4, and particularly preferably 1.0 to 1.3. When the value of the molecular weight distribution (Mw / Mn) is in the above range, the obtained rubber crosslinked product is particularly excellent in low heat generation and wet grip.

<Second step>
In the second step of the production method of the present invention, a modifying agent having a functional group capable of interacting with silica is added to the active end of the conjugated diene-based polymer chain having the active end obtained in the first step described above. This is a step of obtaining a conjugated diene-based polymer chain having a modifying group at the terminal by reacting.

The modifier used in the second step of the present invention may be a compound having a functional group capable of interacting with silica, and is not particularly limited, but the obtained modified conjugated diene rubber may be used as a filler such as silica. It can be made more excellent in affinity for rubber, which makes it easier to process when a filler such as silica is blended, and has low heat generation, wet grip, and abrasion resistance when it is made into a rubber crosslinked product. Silicon compounds are preferable because they can further improve steering stability.

上記一般式（１）中、Ｒ^１～Ｒ^８は、炭素数１～６のアルキル基、または炭素数６～１２のアリール基であり、これらは互いに同一であっても相違していてもよい。Ｘ^１およびＸ^４は、炭素数１～６のアルキル基、炭素数６～１２のアリール基、炭素数１～５のアルコキシ基、および、エポキシ基を含有する炭素数４～１２の基からなる群より選ばれるいずれかの基であり、これらは互いに同一であっても相違していてもよい。Ｘ^２は、炭素数１～５のアルコキシ基、またはエポキシ基を含有する炭素数４～１２の基であり、Ｘ^２が複数あるときは、それらは互いに同一であっても相違していてもよい。Ｘ^３は、２～２０のアルキレングリコールの繰返し単位を含有する基であり、Ｘ^３が複数あるときは、それらは互いに同一であっても相違していてもよい。ｍは１～２００の整数、ｎは０～２００の整数、ｋは０～２００の整数であり、ｍ＋ｎ＋ｋは１以上である。 Examples of the silicon compound as such a modifier include a siloxane compound having a siloxane structure (—Si—O—Si—), and among the siloxane compounds, the siloxane compound has an organic group in addition to the siloxane structure. Organosiloxane is preferable, and polyorganosiloxane represented by the following general formula (1) is more preferable from the viewpoint that the affinity for a filler such as silica can be further enhanced.

In the above general formula (1), R ¹ to R ⁸ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same or different from each other. .. X ¹ and X ⁴ are composed of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and a group having 4 to 12 carbon atoms containing an epoxy group. Any group selected from the group, which may be the same or different from each other. X ² is an alkoxy group having 1 to 5 carbon atoms or a group having 4 to 12 carbon atoms containing an epoxy group, and when there are a plurality of X ^2s , they may be the same or different from each other. good. X ³ is a group containing repeating units of 2 to 20 alkylene glycols, and when there are a plurality of X ³ , they may be the same or different from each other. m is an integer of 1 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200, and m + n + k is 1 or more.

In the polyorganosiloxane represented by the general formula (1), examples of the alkyl group having 1 to 6 carbon atoms which can constitute R ¹ to R ⁸ , X ¹ and X ⁴ in the general formula (1) are, for example. , Methyl group, ethyl group, n-propyl group, isopropyl group, butyl group, pentyl group, hexyl group, cyclohexyl group and the like. 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 ease of production of the polyorganosiloxane itself.

Further, in the polyorganosiloxane represented by the general formula (1), examples of the alkoxy group having 1 to 5 carbon atoms that can constitute X ¹ , X ² and X ⁴ include a methoxy group, an ethoxy group, and a propoxy group. , Isopropoxy group and butoxy group and the like. Among these, a methoxy group and an ethoxy group are preferable from the viewpoint of easiness of producing the polyorganosiloxane itself.

Further, in the polyorganosiloxane represented by the above general formula (1), as a group having 4 to 12 carbon atoms containing an epoxy group capable of constituting X ¹ , X ² and X ⁴ , for example, the following general formula ( The group represented by 2) can be mentioned.
-Z ¹ -Z ² -E (2)
In the above general formula (2), Z ¹ is an alkylene group or an alkylarylene group having 1 to 10 carbon atoms, Z ² is a methylene group, a sulfur atom or an oxygen atom, and E is a carbon having an epoxy group. It is a hydrocarbon group having a number of 2 to 10.

As the group represented by the general formula (2), it is preferable that Z ² is an oxygen atom, Z ² is an oxygen atom and E is a glycidyl group, and Z ¹ is carbon. It is particularly preferable that the alkylene group has the number 1 to 3, where Z ² is an oxygen atom and E is a glycidyl group.

Further, in the polyorganosiloxane represented by the general formula ( ¹ ), as X1 and X4, among the above, a group having ⁴ to 12 carbon atoms containing an epoxy group or a group having 1 to 6 carbon atoms is used. Alkyl groups are preferred. Further, as X2, among the above, a group having ⁴ to 12 carbon atoms containing an epoxy group is preferable. Further, it is more preferable that X ¹ and X ⁴ are alkyl groups having 1 to 6 carbon atoms, and X ² is a group having 4 to 12 carbon atoms containing an epoxy group.

上記一般式（３）中、ｔは２～２０の整数であり、Ｘ^５は炭素数２～１０のアルキレン基またはアルキルアリーレン基であり、Ｒ^９は水素原子またはメチル基であり、Ｘ^６は炭素数１～１０のアルコキシ基またはアリールオキシ基である。これらの中でも、ｔが２～８の整数であり、Ｘ^５が炭素数３のアルキレン基であり、Ｒ^９が水素原子であり、かつ、Ｘ^６がメトキシ基であるものが好ましい。 Further, in the polyorganosiloxane represented by the general formula (1), the group represented by the following general formula (3) is preferable as the group containing the repeating unit of X3 ^, that is, 2 to 20 alkylene glycols. ..

In the above general formula (3), t is an integer of 2 to 20, X ⁵ is an alkylene group or an alkyl arylene group having 2 to 10 carbon atoms, R ⁹ is a hydrogen atom or a methyl group, and X ⁶ is. It is an alkoxy group or an aryloxy group having 1 to 10 carbon atoms. Among these, it is preferable that t is an integer of 2 to 8, X ⁵ is an alkylene group having 3 carbon atoms, R ⁹ is a hydrogen atom, and X ⁶ is a methoxy group.

In the polyorganosiloxane represented by the general formula (1), m is an integer of 1 to 200, preferably an integer of 20 to 150, and more preferably an integer of 30 to 120. When m is 1 to 200, the polyorganosiloxane itself represented by the general formula (1) can be more easily produced, its viscosity does not become too high, and it becomes easier to handle.

Further, in the polyorganosiloxane represented by the general formula (1), n is an integer of 0 to 200, preferably an integer of 0 to 150, and more preferably an integer of 0 to 120. k is an integer of 0 to 200, preferably an integer of 0 to 150, and more preferably an integer of 0 to 130. The total number of m, n and k is 1 or more, preferably 1 to 400, more preferably 20 to 300, and particularly preferably 30 to 250. When the total number of m, n and k is 1 or more, the reaction between the polyorganosiloxane represented by the above general formula (1) and the conjugated diene polymer chain having an active terminal is likely to proceed, and further, m When the total number of, n and k is 400 or less, the polyorganosiloxane itself represented by the general formula (1) can be easily produced, its viscosity does not become too high, and its handling becomes easy.

In addition to the above-mentioned siloxane compound, the modifier used in the second step of the production method of the present invention includes tetramethoxysilane, tetraethoxysilane, 3- (dimethylamino) propyltrimethoxysilane, and 3- (diethylamino) propyl. Trimethoxysilane, 3- (dimethylamino) propyltriethoxysilane, 3- (diethylamino) propyltriethoxysilane, N, N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane, N, N-bis (trimethylsilyl) -3-Aminopropyltriethoxysilane, N, N-bis (trimethylsilyl) -3-aminopropyldiethoxymethylsilane, N, N-bis (trimethylsilyl) aminoethyltrimethoxysilane, N, N-bis (trimethylsilyl) amino Ethyltriethoxysilane, bis (trimethoxysilyl) ethane, 3-glycidoxypropyltriethoxysilane, 1- [3- (triethoxysilanyl) -propyl] -4-methylpiperazine, 2,2-dimethoxy-1 -(3-Trimethoxysilylpropyl) -1-aza-2-alkoxysilane compound such as silacyclopentane; and the like can also be mentioned.

In the second step of the production method of the present invention, the method for reacting the active end of the conjugated diene-based polymer chain having the active end obtained in the above-mentioned first step with the modifying agent is not particularly limited, but is described above. Examples thereof include a method in which a modifier dissolved in a solvent is added to a solution of a conjugated diene-based polymer chain having an active terminal obtained in the first step and mixed. As the solvent used in this case, those exemplified as the solvent used for the polymerization of the above-mentioned conjugated diene-based polymer chain can be used. Further, in this case, there is a method in which the conjugated diene-based polymer chain having the active end obtained in the above-mentioned first step is left as it is in the polymerization solution used for the polymerization, and a modifying agent is added thereto. Simple and preferable. Further, in this case, the modifier is preferably dissolved in the above-mentioned inert solvent used for the polymerization and added into the polymerization system, and the solution concentration thereof is preferably in the range of 1 to 50% by weight. .. The reaction temperature in the second step is not particularly limited, but is usually 0 to 120 ° C., and the reaction time is not particularly limited, but is usually 1 minute to 1 hour.

The timing of adding the modifier to the solution containing the conjugated diene-based polymer chain having an active end is not particularly limited, but the polymerization reaction is not completed and contains the conjugated diene-based polymer chain having an active end. The state in which the solution also contains a monomer, more specifically, the solution containing a conjugated diene-based polymer chain having an active terminal is 100 ppm or more, more preferably 300 to 50,000 ppm of the monomer. It is desirable to add a modifier to this solution in the state of containing. By adding the denaturant in this way, it is possible to suppress side reactions between the conjugated diene polymer chain having an active terminal and impurities contained in the polymerization system, and to control the reaction satisfactorily. Become.

Before reacting the conjugated diene polymer chain having an active terminal with the modifier, a coupling agent is added into the polymerization system to the extent that the effect of the present invention is not impaired, and the conjugated diene polymer chain is added. A part of the active terminal of the above may be subjected to a coupling reaction.

The coupling agent used in this case is not particularly limited, and examples thereof include tin halide and silicon halide. By performing a coupling reaction using such a coupling agent, a branched structure (preferably a branched structure having three or more branches) can be introduced into the obtained modified conjugated diene rubber, and the modified conjugated diene rubber can be introduced. The shape stability of the rubber can be further improved.

上記一般式（４）中、Ｒ^１０は置換基を有していてもよい２価の炭化水素基を表し、Ｘ^７はハロゲン基を表す。上記一般式（４）中、Ｒ^１０は置換基を有していてもよい２価の炭化水素基を表し、Ｒ^１０となりうる２価の炭化水素基としては、特に限定されないが、メチレン基、１，２－エチレン基、１，３－プロピレン基、１，４－ブチレン基、１，５－ペンチレン基、１，６－ヘキシレン基、４－メチル－２，２－ペンチレン基、２，３－ジメチル－２，３－ブチレン基などが挙げられる。これらのなかでも、１，２－エチレン基および１，６－ヘキシレン基が好ましい。また、Ｘ^７となりうるハロゲン基としては、特に限定されないが、フルオロ基、クロロ基、ブロモ基、ヨード基が挙げられ、これらのなかでも、クロロ基が好ましい。 Examples of the tin halide include tin tetrachloride, triphenylmonochlorotin, and a compound represented by the following general formula (4). Among these, tin tetrachloride is preferable.

In the above general formula (4), R ¹⁰ represents a divalent hydrocarbon group which may have a substituent, and X ⁷ represents a halogen group. In the above general formula (4), R ¹⁰ represents a divalent hydrocarbon group which may have a substituent, and the divalent hydrocarbon group which can be R ¹⁰ is not particularly limited, but a methylene group, 1,2-ethylene group, 1,3-propylene group, 1,4-butylene group, 1,5-pentylene group, 1,6-hexylene group, 4-methyl-2,2-pentylene group, 2,3- Examples thereof include a dimethyl-2,3-butylene group. Of these, 1,2-ethylene groups and 1,6-hexylene groups are preferred. The halogen group that can be X ⁷ is not particularly limited, and examples thereof include a fluoro group, a chloro group, a bromo group, and an iodine group, and among these, a chloro group is preferable.

上記一般式（５）中、Ｒ^１１は置換基を有していてもよい２価の炭化水素基を表し、Ｘ^８はハロゲン基を表す。上記一般式（５）中、Ｒ^１１は置換基を有していてもよい２価の炭化水素基を表し、Ｒ^１１となりうる２価の炭化水素基としては、特に限定されないが、メチレン基、１，２－エチレン基、１，３－プロピレン基、１，４－ブチレン基、１，５－ペンチレン基、１，６－ヘキシレン基、４－メチル－２，２－ペンチレン基、２，３－ジメチル－２，３－ブチレン基などが挙げられる。これらのなかでも、１，２－エチレン基および１，６－ヘキシレン基が好ましい。また、Ｘ^８となりうるハロゲン基としては、特に限定されないが、フルオロ基、クロロ基、ブロモ基、ヨード基が挙げられ、これらのなかでも、クロロ基が好ましい。上記一般式（５）で表される化合物の具体例としては、ビス（トリクロロシリル）メタン、１，２－ビス（トリクロロシリル）エタン、１，３－ビス（トリクロロシリル）プロパン、１，４－ビス（トリクロロシリル）ブタン、１，５－ビス（トリクロロシリル）ペンタン、および１，６－ビス（トリクロロシリル）ヘキサンなどが挙げられる。 Examples of the halogenated silicon include silicon tetrachloride, hexachlorodisilane, triphenoxychlorosilane, methyltriphenoxysilane, diphenoxydichlorosilane, and a compound represented by the following general formula (5). Among these, silicon tetrachloride is preferable.

In the above general formula (5), R ¹¹ represents a divalent hydrocarbon group which may have a substituent, and X ⁸ represents a halogen group. In the above general formula (5), R ¹¹ represents a divalent hydrocarbon group which may have a substituent, and the divalent hydrocarbon group which can be R ¹¹ is not particularly limited, but a methylene group, 1,2-ethylene group, 1,3-propylene group, 1,4-butylene group, 1,5-pentylene group, 1,6-hexylene group, 4-methyl-2,2-pentylene group, 2,3- Examples thereof include a dimethyl-2,3-butylene group. Of these, 1,2-ethylene groups and 1,6-hexylene groups are preferred. The halogen group that can be ^X8 is not particularly limited, and examples thereof include a fluoro group, a chloro group, a bromo group, and an iodine group, and among these, a chloro group is preferable. Specific examples of the compound represented by the above general formula (5) include bis (trichlorosilyl) methane, 1,2-bis (trichlorosilyl) ethane, 1,3-bis (trichlorosilyl) propane, and 1,4-. Examples thereof include bis (trichlorosilyl) butane, 1,5-bis (trichlorosilyl) pentane, and 1,6-bis (trichlorosilyl) hexane.

In the production method of the present invention, the amount of the coupling agent used is not particularly limited, but is 0.001 to 0.2 mol as the amount of the conjugated diene polymer chain having the active end to be reacted with respect to 1 mol of the active end. It is preferably 0.005 to 0.1 mol, more preferably 0.01 to 0.07 mol, and particularly preferably 0.01 to 0.07 mol. By using the coupling agent in such an amount, the shape stability of the obtained modified conjugated diene rubber can be further enhanced.

The method for reacting a part of the chain end of the conjugated diene polymer having an active end with the coupling agent is not particularly limited, and examples thereof include a method of mixing these in a solvent in which each of them can be dissolved. As the solvent used in this case, those exemplified as the solvent used for the polymerization of the above-mentioned conjugated diene-based polymer chain can be used. Further, in this case, there is a method in which the conjugated diene-based polymer chain having the active end obtained in the above-mentioned first step is left as it is in the polymerization solution used for the polymerization, and a modifying agent is added thereto. Simple and preferable. Further, in this case, the coupling agent is preferably dissolved in an inert solvent and added to the polymerization system, and the solution concentration thereof is preferably in the range of 1 to 50% by weight. The reaction temperature is not particularly limited, but is usually 0 to 120 ° C., and the reaction time is also not particularly limited, but is usually 1 minute to 1 hour.

Further, at the time of adding the coupling agent to the solution containing the conjugated diene polymer chain having an active end, the polymerization reaction in the conjugated diene polymer chain having an active end is completed as in the case of the modifier. However, it is desirable to add the solution containing the conjugated diene-based polymer chain having an active terminal in a state where it also contains a monomer.

In the second step of the production method of the present invention, after reacting the active end of the conjugated diene-based polymer chain with a modifier and, if desired, a coupling agent, alcohol such as methanol and isopropanol or water or the like may be used. , It is preferable to add a polymerization inhibitor to inactivate the unreacted active terminal.

<Third step>
The third step in the production method of the present invention is a step of reacting an alkylthiol compound with a conjugated diene-based polymer chain having a modifying group at the terminal obtained in the above-mentioned second step using a radical initiator. .. In the third step of the production method of the present invention, the alkylthiol compound mainly reacts with the vinyl-bonded moiety in the conjugated diene monomer unit constituting the conjugated diene-based polymer chain having a modifying group at the terminal.

According to the production method of the present invention, the active end of the conjugated diene polymer chain having an active end is reacted with a denaturing agent having a functional group capable of interacting with silica (second step), and then a radical. The alkylthiol compound is reacted with the conjugated diene-based polymer chain obtained by reacting the modifier with the initiator (third step), whereby the modified conjugated diene-based rubber obtained by this reaction is subjected to the polymer chain. The terminal may be provided with a modified structure by a modifier having a functional group capable of interacting with silica, and may have a group derived from an alkylthiol compound. As a result, it is possible to suppress an increase in Mooney viscosity when a filler such as silica is blended, whereby the filler such as silica can be satisfactorily dispersed, and further, filling with silica or the like can be suppressed. It is possible to improve the processability when the agent is blended. Furthermore, since a filler such as silica can be satisfactorily dispersed, the reinforcing property of the filler such as silica can be sufficiently exhibited, and as a result, when a rubber crosslinked product is obtained, it can be obtained. The obtained rubber crosslinked product can be made excellent in low heat generation property, wet grip property, wear resistance and steering stability.

The alkylthiol compound is not particularly limited, but is ethanethiol, 1-propanethiol, 2-propanethiol, 1-butanethiol, 2-butanethiol, 2-methyl-1-propanethiol, 2-methyl-2-propane. Thiol, 2-methyl-1-butanethiol, 1-pentanethiol, 2,2-dimethyl-1-propanethiol, 1-hexanethiol, 1-heptanethiol, 2-ethylhexanethiol, 1-octanethiol, 1- Nonanthiol, 1-decanethiol, 1-undecanethiol, 1-dodecanethiol, tert-dodecyl mercaptan, 1-tridecanethiol, 1-tetradecanethiol, 1-pentadecanethiol, 1-hexadecanethiol, 1-heptadecanethiol, Alkyl monothiols such as 1-octadecanethiol, 1-nonadecanthiol, 1-eicosanthiol; and the like. Among these, alkyl monothiols are preferable, and alkyl monothiols having a primary thiol group (that is, an alkyl thiol compound in which one thiol group is bonded to a primary carbon atom) are more preferable, and primary thiols are preferable. Alkyl monothiols having a thiol group and having 4 to 18 carbon atoms are more preferable. In addition, these alkylthiol compounds may be used individually by 1 type, and may be used in combination of 2 or more types.

The amount of the alkylthiol compound used is not particularly limited, and the amount of the alkyl group introduced from the alkylthiol compound in the obtained modified conjugated diene rubber is preferably 0.5 to 30% by weight, more preferably 1 to 20%. The amount may be% by weight, more preferably 3 to 13% by weight. Specifically, the amount of the alkylthiol compound used is preferably in the range of 0.5 to 35 parts by weight with respect to 100 parts by weight of the conjugated diene polymer chain having a modifying group at the terminal obtained in the second step described above. It is more preferably in the range of 1.0 to 25 parts by weight, and further preferably in the range of 3 to 15 parts by weight. By setting the amount of the alkyl group introduced from the alkyl thiol compound in the above range, the modification effect of the alkyl thiol compound, that is, the processability when a filler such as silica is blended, and the low heat buildup of the obtained rubber crosslinked product. , Wet grip, wear resistance and steering stability can be improved more appropriately. The amount of the alkyl group introduced from the alkyl thiol compound can be determined by, for example, ¹³ C-NMR measurement of the modified conjugated diene rubber and the result of ¹³ C-NMR measurement according to the following formula.
Alkyl group introduction amount derived from alkyl thiol compound (% by weight) = (content of alkyl group derived from alkyl thiol compound based on weight / weight of modified conjugated diene rubber) × 100

Further, the radical initiator used when reacting the alkylthiol compound with the conjugated diene polymer chain having a modifying group at the terminal in the third step of the production method of the present invention is not particularly limited, but sodium persulfate. , Inorganic peroxide-based radical initiators such as potassium persulfate, ammonium persulfate, potassium perphosphate, hydrogen peroxide; hydroperoxides (eg, diisopropylbenzenehydroperoxide, cumenehydroperoxide, t-butylhydroperoxide). , P-mentan hydroperoxide, 1,1,3,3-tetramethylbutylhydroperoxide, etc.), Dialkyl peroxide (eg, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, etc.) , Peroxyester (eg isobutyryl peroxide, t-butylperoxyisobutyrate, etc.), diacyl peroxide (eg benzoyl peroxide, lauroyl peroxide, isobutyryl peroxide, octanoyl peroxide, 3, 5, 5 -Organic peroxide-based radical initiators such as trimethylhexanoyl peroxide, etc.), peroxydicarbonate, peroxyketal, ketone peroxide; 2,2'-azobisisobutyronitrile, azobis-2,4 -Azo compound-based radical initiators such as dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and methyl azobisisobutyrate; and the like. Among these, an azo compound-based radical initiator is preferable, and 2,2'-azobisisobutyronitrile is particularly preferable, from the viewpoint of reactivity.

The amount of the radical initiator used may be appropriately selected depending on the type of radical initiator used, but is preferably 0.1 to 200 parts by weight, more preferably 0.5 to 100 parts by weight, based on 100 parts by weight of the alkylthiol compound. It is 50 parts by weight, more preferably 1 to 20 parts by weight. By setting the amount of the radical initiator used in the above range, the reaction between the conjugated diene-based polymer chain having a modifying group at the terminal and the alkylthiol compound can proceed more appropriately.

As a method for reacting an alkylthiol compound with a conjugated diene polymer chain having a modifying group at the terminal obtained in the above-mentioned second step using a radical initiator in the third step of the production method of the present invention. The present invention is not particularly limited, and examples thereof include a method of adding an alkylthiol compound and a radical initiator to the solution of the conjugated diene polymer chain having a modifying group at the terminal obtained in the above-mentioned second step and mixing them. .. As the solvent used at this time, those exemplified as the solvent used for the polymerization of the above-mentioned conjugated diene-based polymer chain and the reaction with the modifier can be used. Further, in this case, the conjugated diene-based polymer chain having a modifying group at the terminal obtained in the above-mentioned second step is left as it is in the solution used for the reaction, and the alkylthiol compound and the radical initiator are started here. The method of adding the agent is simple and preferable. Further, in this case, the alkylthiol compound and the radical initiator may be dissolved in a solvent and added into the polymerization system, and the solution concentration thereof is preferably in the range of 1 to 50% by weight. The reaction temperature in the third step is not particularly limited, but is usually 0 to 100 ° C., and the reaction time is not particularly limited, but is usually 1 minute to 600 minutes.

After reacting the alkylthiol compound with the conjugated diene polymer chain having a modifying group at the terminal, if desired, an antiaging agent such as a phenol-based stabilizer, a phosphorus-based stabilizer, or a sulfur-based stabilizer, a crumbing agent, And an antiscale agent or the like is added to the polymerization solution, and then the polymerization solvent is separated from the polymerization solution by direct drying or steam stripping to recover the modified conjugated diene rubber obtained by the production method of the present invention. Before separating the polymerization solvent from the polymerization solution, the spreading oil may be mixed with the polymerization solution and the modified conjugated diene rubber may be recovered as the oil spreading rubber.

Examples of the spreading oil used when recovering the modified conjugated diene-based rubber as an oil-based rubber include paraffin-based, aromatic and naphthen-based petroleum-based softeners, plant-based softeners, and fatty acids. When a petroleum-based softener is used, the content of polycyclic aromatics extracted by the method of IP346 (inspection method of THE INSTITUTE PETROLEUM in the United Kingdom) is preferably less than 3%. When the wrought oil is used, the amount used is preferably 5 to 100 parts by weight, more preferably 10 to 60 parts by weight, still more preferably 20 to 50 parts by weight with respect to 100 parts by weight of the modified conjugated diene rubber. be.

The weight average molecular weight (Mw) of the modified conjugated diene rubber obtained by the production method of the present invention is a value measured by gel permeation chromatography in terms of polystyrene, preferably 100,000 to 3,000,000, more preferably. Is 150,000 to 2,000,000, particularly preferably 200,000 to 1,500,000. By setting the weight average molecular weight of the modified conjugated diene rubber within the above range, it becomes easier to mix silica into the modified conjugated diene rubber, the rubber composition becomes more processable, and the obtained rubber crosslinks are obtained. The low heat generation and wear resistance of the object can be further improved.

The molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the modified conjugated diene rubber obtained by the production method of the present invention is 1.1 to 3.0. It is preferably 1.2 to 2.5, more preferably 1.2 to 2.2, and particularly preferably 1.2 to 2.2. By setting the molecular weight distribution (Mw / Mn) of the modified conjugated diene rubber within the above range, it is possible to further improve the low heat generation property and the wet grip property of the obtained rubber crosslinked product.

The Mooney viscosity (ML1 + 4,100 ° C.) of the modified conjugated diene rubber obtained by the production method of the present invention is preferably 20 to 100, more preferably 30 to 90, and particularly preferably 35 to 80. When the modified conjugated diene rubber is an oil-extended rubber, it is preferable that the Mooney viscosity of the oil-extended rubber is in the above range.

In this way, the modified conjugated diene-based rubber obtained by the production method of the present invention is excellent in processability when a filler such as silica is blended, and a blending agent such as a filler and a cross-linking agent can be used. After being added, it can be suitably used for various uses. In particular, when silica is blended as a filler, a rubber composition suitably used for obtaining a rubber crosslinked product having excellent low heat generation property, wet grip property, wear resistance and steering stability can be provided.

<Rubber composition>
The rubber composition of the present invention is a composition containing 10 to 200 parts by weight of silica with respect to 100 parts by weight of a rubber component containing the modified conjugated diene rubber obtained by the above-mentioned production method of the present invention.

The rubber composition of the present invention may contain other rubbers other than the modified conjugated diene-based rubber obtained by the above-mentioned production method of the present invention. Other rubbers include, for example, modified natural rubbers (epoxidized natural rubber (ENR), hydrided natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), grafted natural rubber and the like. Quality Natural rubber may be used), polyisoprene rubber, emulsified polymerized styrene-butadiene copolymer rubber, solution-polymerized styrene-butadiene copolymer rubber, polybutadiene rubber (high cis-BR, low cis BR). Further, it may be a polybutadiene rubber containing a crystal fiber composed of a 1,2-polybutadiene polymer), a styrene-isoprene copolymer rubber, a butadiene-isoprene copolymer rubber, a styrene-isoprene-butadiene copolymer rubber, and an acrylonitrile-. Among butadiene copolymer rubber, acrylonitrile-styrene-butadiene copolymer rubber, butyl rubber (IIR), ethylene-propylene copolymer, chloroprene rubber, nitrile chloroprene rubber, nitrile isoprene rubber, etc., according to the above-mentioned production method of the present invention. It refers to other than the obtained modified conjugated diene rubber. Among these, natural rubber, polyisoprene rubber, polybutadiene rubber, and solution-polymerized styrene-butadiene copolymer rubber are preferable. These rubbers can be used alone or in combination of two or more, such as natural rubber and polybutadiene rubber, and natural rubber and styrene-butadiene copolymer rubber.

In the rubber composition of the present invention, the modified conjugated diene-based rubber obtained by the production method of the present invention preferably occupies 10 to 100% by weight, preferably 50 to 100% by weight of the rubber component in the rubber composition. Is particularly preferable. By including the modified conjugated diene-based rubber obtained by the production method of the present invention in the rubber component at such a ratio, it is possible to obtain a rubber crosslinked product having excellent low heat generation, wet grip and steering stability. can.

Examples of the silica used in the present invention include dry method white carbon, wet method white carbon, colloidal silica, precipitated silica, calcium silicate, aluminum silicate and the like. Among these, the wet method white carbon containing hydrous silicic acid as a main component is preferable. Further, a carbon-silica dual phase filler in which silica is supported on the surface of carbon black may be used. These silicas can be used alone or in combination of two or more. The nitrogen adsorption specific surface area of the silica used (measured by the BET method according to ASTM D3037-81) is preferably 20 to 400 m ² / g, more preferably 50 to 220 m ² / g, and particularly preferably 80 to 170 m ² / g. g. The pH of silica is preferably 5 to 10.

As the silica used in the present invention, the silica having a dibutyl phthalate (DBP) absorption value preferably in the range of about 100 to about 400, particularly preferably in the range of about 150 to about 300.

The silica used in the present invention preferably has an average limit particle size in the range of 0.01 to 0.05 μm as measured by an electron microscope, but the average limit particle size of silica is not limited to this range and is even smaller. Or even larger.

As the silica used in the present invention, for example, various commercially available silicas can be used. For example, Hi-Sil, 210, Hi-Sil233, Hi-Sil243LD manufactured by PPG Industries; ZEOSIL1115MP, ZEOSIL1165MP, ZEOSIL165GR, ZEOSIL PREMIUM 200MP manufactured by Solvay;

The blending amount of silica in the rubber composition of the present invention is preferably 10 to 200 parts by weight, more preferably 15 to 150 parts by weight, still more preferably 20 parts by weight with respect to 100 parts by weight of the rubber component in the rubber composition. ~ 130 parts by weight. By setting the blending amount of silica in the above range, the wet grip property, low heat generation property and steering stability of the obtained rubber crosslinked product can be further improved.

A silane coupling agent may be further added to the rubber composition of the present invention from the viewpoint of further improving the low heat generation property. The silane coupling agent is not particularly limited, and various silane coupling agents can be used, but in the present invention, a sulfide type, a mercapto type, and a protected mercapto type (for example, those having a carbonylthio group) can be used. , Thiocyanate-based, vinyl-based, amino-based, methacrylate-based, glycidoxy-based, nitro-based, epoxy-based or chloro-based silane coupling agents can be preferably used. Specific examples of the silane coupling agent include bis (3- (triethoxysilyl) propyl) disulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3- (triethoxysilyl) propyl) tetrasulfide, and γ. -Mercaptopropyltriethoxysilane, 3- [ethoxybis (3,6,9,12,15-pentaoxaoctacosan-1-yloxy) silyl] -1-propanethiol, 3-octanoylthio-1-propyl-triethoxysilane , 3-Trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, γ-trimethoxysilylpropylbenzothiazyltetrasulfide, 3-trimethoxysilylpropylbenzothiazoletetrasulfide, 3-thiocyanatepropyltriethoxysilane, vinyl Triethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, 3-trimethoxysilylpropylmethacrylate monosulfide, γ-glycidoxypropyltriethoxysilane, 3-nitropropyltrimethoxysilane, β -(3,4-Epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropyltrimethoxysilane and the like can be mentioned. Further, NXT-Z100, NXT-Z30, NXT-Z45, NXT-Z60, NXT-Z45, NXT manufactured by Momentive Performance Materials, Si69, Si75, VP Si363 manufactured by Evonik, and the like can also be used. These silane coupling agents can be used alone or in combination of two or more. Further, one or more of these may be oligomerized in advance and used in the oligomerized state. The blending amount of the silane coupling agent is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight, based on 100 parts by weight of silica.

Further, the rubber composition of the present invention may further contain carbon black such as furnace black, acetylene black, thermal black, channel black, and graphite. Of these, furnace black is preferable. These carbon blacks can be used alone or in combination of two or more. The blending amount of carbon black is usually 120 parts by weight or less with respect to 100 parts by weight of the rubber component in the rubber composition.

The method of adding silica to the rubber component containing the modified conjugated diene rubber obtained by the production method of the present invention is not particularly limited, and the method of adding and kneading the solid rubber component (dry kneading method). ) Or a method of adding to a solution containing a modified conjugated diene rubber to coagulate and dry it (wet kneading method) can be applied.

Further, it is preferable that the rubber composition of the present invention further contains a cross-linking agent. Examples of the cross-linking agent include sulfur-containing compounds such as sulfur and sulfur halide, organic peroxides, quinonedioximes, organic polyvalent amine compounds, and alkylphenol resins having a methylol group. Of these, sulfur is preferably used. The blending amount of the cross-linking agent is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight with respect to 100 parts by weight of the rubber component in the rubber composition. Is.

Further, in addition to the above components, the rubber composition of the present invention contains a cross-linking accelerator, a cross-linking activator, an antioxidant, a filler (excluding the above-mentioned silica and carbon black), an activator, and a process oil according to a conventional method. , Plasticizers, lubricants, tackifiers, compatibilizers, surfactants and other compounding agents can be blended in required amounts.

When sulfur or a sulfur-containing compound is used as the cross-linking agent, it is preferable to use a cross-linking accelerator and a cross-linking activator in combination. Examples of the cross-linking accelerator include a sulfenamide-based cross-linking accelerator; a guanidine-based cross-linking accelerator; a thiourea-based cross-linking accelerator; a thiazole-based cross-linking accelerator; a thiuram-based cross-linking accelerator; a dithiocarbamic acid-based cross-linking accelerator; a xanthate acid-based agent. Crosslinking accelerators; and the like. Among these, those containing a sulfenamide-based cross-linking accelerator are preferable. These cross-linking accelerators may be used alone or in combination of two or more. The amount of the cross-linking accelerator to be blended is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight with respect to 100 parts by weight of the rubber component in the rubber composition. It is a department.

Examples of the cross-linking activator include higher fatty acids such as stearic acid; zinc oxide; and the like. These cross-linking activators may be used alone or in combination of two or more. The blending amount of the cross-linking activator is preferably 0.05 to 20 parts by weight, particularly preferably 0.5 to 15 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition.

Further, the rubber composition of the present invention may contain a resin in addition to the rubber component. By blending the resin, it is possible to impart adhesiveness to the rubber composition and enhance the dispersibility of the filler in the rubber composition. As a result, improvement in wet grip and wear resistance of the obtained rubber crosslinked product can be expected. Further, it is possible to improve the processability of the rubber composition as an effect similar to that of the plasticizer. Examples of the resin include C5 type petroleum resin, C5 / C9 type petroleum resin, C9 type petroleum resin, dicyclopentadiene type resin, terpene type resin, terpene phenol resin, aromatic modified terpene resin, alkylphenol-acetylene resin, and rosin type. Examples thereof include a resin, a rosin ester resin, an inden resin, a C9 resin containing inden, an α-methylstyrene / inden copolymer resin, a kumaron-inden resin, a farnesene resin, and a polylymonen resin. These resins may be modified or hydrogenated. These resins may be used alone or in combination of two or more. The blending amount of the resin is preferably 25 parts by weight or less with respect to 100 parts by weight of the rubber component in the rubber composition.

In order to obtain the rubber composition of the present invention, each component may be kneaded according to a conventional method. For example, a component excluding heat-unstable components such as a cross-linking agent and a cross-linking accelerator and a modified conjugated diene-based rubber are used. After kneading, a heat-unstable component such as a cross-linking agent or a cross-linking accelerator can be mixed with the kneaded product to obtain a desired composition. The kneading temperature of the component excluding the heat-unstable component and the modified conjugated diene rubber is preferably 80 to 200 ° C., more preferably 120 to 180 ° C., and the kneading time is preferably 30 seconds to 30 minutes. Is. Further, the kneaded product and the heat-unstable component are usually mixed after cooling to 100 ° C. or lower, preferably 80 ° C. or lower.

<Rubber cross-linked product>
The rubber crosslinked product of the present invention is obtained by cross-linking the above-mentioned rubber composition of the present invention.
The rubber crosslinked product of the present invention is formed by using the rubber composition of the present invention, for example, by molding with a molding machine corresponding to a desired shape, for example, an extruder, an injection molding machine, a compressor, a roll, or the like, and heating. It can be manufactured by carrying out a cross-linking reaction and fixing the shape as a rubber cross-linked product. In this case, cross-linking may be performed after molding in advance, or cross-linking may be performed at the same time as molding. The molding temperature is usually 10 to 200 ° C, preferably 25 to 120 ° C. The crosslinking temperature is usually 100 to 200 ° C., preferably 130 to 190 ° C., and the crosslinking time is usually 1 minute to 24 hours, preferably 2 minutes to 12 hours, particularly preferably 3 minutes to 6 hours. ..

Further, depending on the shape and size of the rubber crosslinked product, even if the surface is crosslinked, it may not be sufficiently crosslinked to the inside, so that it may be further heated for secondary crosslinking.

As the heating method, a general method used for cross-linking rubber such as press heating, steam heating, oven heating, and hot air heating may be appropriately selected.

Since the rubber crosslinked product of the present invention thus obtained is obtained by using the modified conjugated diene-based rubber obtained by the above-mentioned production method of the present invention, it has low heat generation property, wet grip property and wear resistance. And it has excellent steering stability. In particular, the modified conjugated diene rubber obtained by the production method of the present invention has a modified structure with a modifier having a functional group capable of interacting with silica at the end of the polymer chain, and is derived from an alkylthiol compound. Since it has a group of silica, it is possible to suppress an increase in the viscosity of the rubber composition obtained by blending a filler such as silica, thereby satisfactorily dispersing the filler such as silica. As a result, the reinforcing property of the filler such as silica can be sufficiently exhibited. Therefore, the rubber crosslinked product of the present invention obtained by using the modified conjugated diene rubber of the present invention is excellent in low heat generation property, wet grip property, wear resistance and steering stability.

Therefore, the rubber crosslinked product of the present invention takes advantage of its excellent wet grip property, low heat generation property and steering stability, and for example, in a tire, each part of the tire such as a cap tread, a base tread, a carcass, a sidewall, and a bead portion. Materials; Materials for hoses, belts, mats, anti-vibration rubber, and other various industrial products; Resin impact resistance improvers; Resin film cushioning agents; Sole; Rubber shoes; Golf balls; Toys; Can be used. In particular, the rubber crosslinked product of the present invention is excellent in wet grip, low heat generation and steering stability, and therefore can be suitably used as a material for tires, particularly as a material for fuel-efficient tires, and is most suitable for tread applications. ..

Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples. In the following, "part" is based on weight unless otherwise specified. The tests and evaluations were as follows.

[Number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn)]
The number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn) were determined by gel permeation chromatography (GPC) as polystyrene-equivalent molecular weights. The specific measurement conditions for gel permeation chromatography were as follows.
Measuring instrument: High-performance liquid chromatograph (manufactured by Tosoh, trade name "HLC-8320")
Column: Polystyrene column manufactured by Tosoh Corporation, trade name "GMH-HR-H" was connected in series.
Detector: Differential refractometer Eluent: Tetrahydrofuran Column temperature: 40 ° C

[Styrene unit content and vinyl bond content]
The styrene unit content and the vinyl bond content were measured by ¹ H-NMR using an FT-NMR device (product name: ADVANCE III 500) manufactured by Bruker Biospin.

[Amount of alkyl group introduced from alkyl thiol compound]
The amount of alkyl thiol derived from the alkyl thiol compound of the modified conjugated diene rubber is measured by ¹³ C-NMR using an FT-NMR device (product name: ADVANCE III 500) manufactured by Bruker Biospin. The amount of the alkyl group derived from the compound was quantified and determined according to the following formula.
Alkyl group introduction amount derived from alkyl thiol compound (% by weight) = (content of alkyl group derived from alkyl thiol compound based on weight / weight of modified conjugated diene rubber) × 100

[Workability]
Mooney viscosity (polymer Mooney, ML1 + 4, 100 ° C.) of modified conjugated Diene rubber before blending a compounding agent such as a cross-linking agent, and after blending a compounding agent such as silica or a cross-linking agent with the modified conjugated Diene rubber. The Mooney viscosity (compound Mooney, ML1 + 4, 100 ° C.) of the crosslinkable rubber composition of the above was measured using a Mooney viscometer (manufactured by Shimadzu Corporation, product name "SMV-300") according to JIS K6300, and crosslinked. The value ΔML obtained by subtracting the Mooney viscosity (polymer Mooney viscosity) of the modified conjugated Diene rubber from the Mooney viscosity (compound Mooney viscosity) of the sex rubber composition was obtained, and this was used as an index of processability. It can be judged that the lower the value of ΔML, the better the workability.

[Silica dispersibility]
The silica dispersibility in the crosslinkable rubber composition is dynamically set at 60 ° C. and 1 Hz by a viscoelasticity measuring device (manufactured by Alpha Technologies, product name “RPA-2000”) using the crosslinkable rubber composition. The storage elastic modulus G'at 1% strain and 10% dynamic strain was measured, and the storage elastic modulus G'(1%) at 1% dynamic strain and the storage elastic modulus G'(10%) at 10% dynamic strain. It was obtained by calculating the difference between the above and (ΔG'= G'(1%) −G'(10%)). The obtained difference ΔG'is shown as an exponent with Comparative Example 2 as a reference sample of 100. The smaller this index is, the more the dispersibility of the filler such as silica is excellent, so that the processability is excellent.

[Low heat generation]
The crosslinkable rubber composition was press-crosslinked at 160 ° C. for 20 minutes to obtain a test piece having a length of 50 mm, a width of 12.7 mm and a thickness of 2 mm. Then, with respect to the obtained test piece, tan δ at 60 ° C. was measured under the condition of dynamic strain 0.5% and 10 Hz using ARES-G2 manufactured by TA Instruments. The value of this tan δ is shown as an exponent with Comparative Example 2 as a reference sample of 100. The smaller this index is, the better the fuel efficiency when the rubber crosslinked product is used for the tire.

[Wet grip]
The crosslinkable rubber composition was press-crosslinked at 160 ° C. for 20 minutes to obtain a test piece having a length of 50 mm, a width of 12.7 mm and a thickness of 2 mm. Then, with respect to the obtained test piece, tan δ at 0 ° C. was measured under the condition of dynamic strain of 0.5% and 10 Hz using ARES-G2 manufactured by TA Instruments. The value of this tan δ is shown as an exponent with Comparative Example 2 as a reference sample of 100. The larger the index, the better the wet grip property when the rubber crosslinked product is used for the tire.

[Abrasion resistance]
The crosslinkable rubber composition was press-crosslinked at 160 ° C. for 25 minutes to prepare a test piece having an outer diameter of 50 mm, an inner diameter of 15 mm, and a thickness of 10 mm. 2012 ”, manufactured by Ueshima Seisakusho), the road surface temperature was 30 ° C., the load was 10N, and the frictional force (contact force) generated between the sample and the wear wheel was 5N. The obtained wear rate (mm / 1000 km) is shown by an index of 100 with Comparative Example 2 as a reference sample. The smaller this index is, the better the wear resistance when the rubber crosslinked product is used for the tire.

[Maneuvering stability]
The crosslinkable rubber composition was press-crosslinked at 160 ° C. for 20 minutes to obtain a test piece having a length of 50 mm, a width of 12.7 mm and a thickness of 2 mm. Then, using the obtained test piece, a tensile test was performed according to JIS K6301 to measure the tensile stress at an elongation of 300%. The larger the tensile stress at 300% elongation, the better the steering stability when the rubber crosslinked product is used for the tire.

[Manufacturing Example 1]
In an autoclave with a stirrer, 800 g of cyclohexane, 1.28 mmol of tetramethylethylenediamine, 94.8 g of 1,3-butadiene, and 25.2 g of styrene were charged under a nitrogen atmosphere, 0.71 mmol of n-butyllithium was added, and the temperature was 60 ° C. Polymerization was started at. Subsequently, after confirming that the polymerization conversion was in the range of 95% to 100%, 0.04 mmol of tin tetrachloride was added and the reaction was carried out for 10 minutes. A part of the polymer before the addition of tin tetrachloride was sampled, and the weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) were measured. As a result, the weight average molecular weight (Mw) was 268. It was 000 and the molecular weight distribution (Mw / Mn) was 1.13.

Next, the polyorganosiloxane represented by the following formula (6) was prepared so that the amount of the epoxy group contained in the polyorganosiloxane was 0.31 times the molar amount of the n-butyllithium used. It was added in the form of a 20% concentration xylene solution and reacted for 30 minutes. Then, as a polymerization inhibitor, methanol corresponding to twice the molar amount of n-butyllithium used was added to obtain a solution containing a modified conjugated diene rubber (A-1) having a terminal modifying group. ..

A part of the obtained solution containing a modified conjugated diene rubber (A-1) having a terminal modifying group was sampled, and an antiaging agent (trade name "Irganox 1520L", manufactured by BASF) was added to the terminal modifying group. After adding 0.20 part to 100 parts of the modified conjugated diene rubber (A-1) having the above, the solvent is removed by steam stripping, and the residue is vacuum-dried at 60 ° C. for 24 hours to have a terminally modified group. A modified conjugated diene-based rubber (A-1) was obtained. The content of the styrene unit in the obtained modified conjugated diene rubber (A-1) having a terminal modifying group is 21.0% by weight, and the vinyl bond content in the butadiene monomer unit is 64.4% by weight. %, The weight average molecular weight (Mw) was 492,000, and the molecular weight distribution (Mw / Mn) was 1.50.

[Manufacturing Example 2]
In a solution containing a modified conjugated diene rubber (A-1) having a terminal modifying group obtained in the same manner as in Production Example 1, 1-butanethiol per 100 parts of the modified conjugated diene polymer having a terminal modifying group. The reaction was carried out by adding 4.6 parts and 0.56 parts of 2,2'-azobisisobutyronitrile and stirring at 70 ° C. for 5 hours. After completion of the reaction, a part of the solution was separated and poured into methanol to precipitate a rubbery polymer. The obtained rubber-like polymer was vacuum-dried at 60 ° C. for 24 hours, and then ¹³ C-NMR was measured according to the above method. As a result, a group derived from 1-butanethiol was introduced into the polymer. It was confirmed that That is, it was confirmed that the obtained solution was a solution containing a modified conjugated diene-based rubber (A-2) having a terminal modifying group and an alkyl group derived from 1-butanethiol (Production Examples 3 to 6 described later). It was also confirmed that a group derived from the alkylthiol compound used in the same manner was introduced in (). The amount of the alkyl group derived from 1-butanethiol introduced in the modified conjugated diene rubber (A-2) was 3.6% by weight.

Next, an antiaging agent (trade name "Irganox 1520L", manufactured by BASF) is modified in a solution containing a modified conjugated diene rubber (A-2) having a terminal modifying group and an alkyl group derived from 1-butanethiol. 0.20 part was added to 100 parts of the conjugated diene rubber (A-2). Then, the solvent was removed by steam stripping and vacuum dried at 60 ° C. for 24 hours to obtain a modified conjugated diene rubber (A-2) having a terminal modifying group and an alkyl group derived from 1-butanethiol. The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) are as shown in Table 1.

[Manufacturing Example 3]
Modified conjugate having a terminal modifying group and an alkyl group derived from 1-dodecanethiol in the same manner as in Production Example 2, except that 10.4 parts of 1-dodecanethiol was used instead of 4.6 parts of 1-butanethiol. A diene rubber (A-3) was obtained. The amount of the alkyl group derived from 1-dodecanethiol introduced in the modified conjugated diene rubber (A-3) was 7.7% by weight. The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) are as shown in Table 1.

[Manufacturing Example 4]
Modified conjugate having a terminal modifying group and an alkyl group derived from 1-octadecanethiol in the same manner as in Production Example 2, except that 14.7 parts of 1-octadecanethiol was used instead of 4.6 parts of 1-butanethiol. A diene rubber (A-4) was obtained. The amount of the alkyl group derived from 1-octadecanethiol introduced in the modified conjugated diene rubber (A-4) was 10.7% by weight. The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) are as shown in Table 1.

[Manufacturing Example 5]
A modified conjugate having a terminal modifying group and an alkyl group derived from 1-dodecanethiol, as in Production Example 2, except that 29.7 parts of 1-dodecanethiol was used instead of 4.6 parts of 1-butanethiol. A diene-based rubber (A-5) was obtained. The amount of the alkyl group derived from 1-dodecanethiol introduced in the modified conjugated diene rubber (A-5) was 19.0% by weight. The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) are as shown in Table 1.

[Manufacturing Example 6]
In an autoclave with a stirrer, 800 g of cyclohexane, 1.28 mmol of tetramethylethylenediamine, 94.8 g of 1,3-butadiene, and 25.2 g of styrene were charged under a nitrogen atmosphere, 0.71 mmol of n-butyllithium was added, and the temperature was 60 ° C. Polymerization was started at. Subsequently, after confirming that the polymerization conversion was in the range of 95% to 100%, 0.04 mmol of tin tetrachloride was added and the reaction was carried out for 10 minutes. Then, as a polymerization inhibitor, methanol corresponding to twice the mole of n-butyllithium used was added to obtain a solution containing a conjugated diene rubber (A-6) having no terminal modifying group. ..

A part of the obtained solution containing the conjugated diene rubber (A-6) was sampled, and an antiaging agent (manufactured by BASF, trade name "Irganox 1520L") was applied to the conjugated diene rubber (A-6). After adding 0.20 part to 100 parts, the solvent was removed by steam stripping and vacuum dried at 60 ° C. for 24 hours to obtain a conjugated diene rubber (A-6). The content of the styrene unit in the obtained conjugated diene rubber (A-6) was 22.0% by weight, the vinyl bond content in the butadiene monomer unit was 62.2% by weight, and the weight average molecular weight (weight average molecular weight). Mw) was 315,000 and the molecular weight distribution (Mw / Mn) was 1.54.

Next, the same procedure as in Production Example 3 was carried out except that the solution containing the conjugated diene rubber (A-6) was used instead of the solution containing the modified conjugated diene rubber (A-1) having a terminal modifying group. A modified conjugated diene rubber (A-7) having an alkyl group derived from 1-dodecanethiol was obtained. The amount of the alkyl group derived from 1-dodecanethiol introduced in the modified conjugated diene rubber (A-7) was 7.8% by weight. The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) are as shown in Table 1.

[Example 1]
Using a Banbury mixer having a capacity of 250 ml, 103.4 parts of a modified conjugated diene rubber (A-2) having a terminal modifying group and an alkyl group derived from 1-butanethiol obtained in Production Example 2 was kneaded. Next, 46.5 parts of silica (trade name "Zeosil 1165MP", manufactured by Solvay), 5.4 parts of silane coupling agent (trade name "Si69", manufactured by Evonik), and process oil (trade name "Aromax T"). -DAE ", manufactured by JXTG Energy Co., Ltd.) 15.5 parts were added, and the mixture was kneaded at 110 ° C. as a starting temperature for 1.5 minutes. In this kneaded product, silica (trade name "Zeosil 1165MP", manufactured by Solvay) 20.7 parts, zinc oxide (zinc oxide No. 1) 3.1 parts, stearic acid (trade name "bead stearic acid Tsubaki", Nikko) 2.1 parts, and N-phenyl-N'-(1,3-dimethylbutyl) -p-phenylenediamine as an antioxidant, trade name "Nocrack 6C", manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.) 2.1 parts were added and kneaded for 3 minutes to drain the kneaded product from the Banbury mixer. The temperature of the rubber composition at the end of kneading was 150 ° C. The kneaded product was cooled to room temperature and then kneaded again in a Banbury mixer for 3 minutes, after which the kneaded product was discharged from the Banbury mixer. Then, using an open roll at 50 ° C., the obtained kneaded product, 1.7 parts of nitrogen and a cross-linking accelerator (N-cyclohexyl-2-benzothiazolyl sulfenamide (trade name "Noxeller CZ-G"), After kneading 1.4 parts of Ouchi Shinko Chemical Industry Co., Ltd.) and 2.8 parts of diphenylguanidine (a mixture of 1.4 parts of diphenylguanidine (trade name "Noxeller D", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)) The sheet-shaped crosslinkable rubber composition was taken out. Using the obtained crosslinkable rubber composition, each measurement / evaluation of processability, silica dispersibility, low heat generation property, wet grip property, wear resistance, processability and steering stability was performed. The results are shown in Table 1.

[Example 2]
Instead of the modified conjugated diene rubber (A-2) having a terminal modifying group and an alkyl group derived from 1-butanethiol, the modification having the terminal modifying group and the alkyl group derived from 1-dodecanethiol obtained in Production Example 3 A crosslinkable rubber composition was obtained in the same manner as in Example 1 except that 103.4 parts of the conjugated diene rubber (A-3) was used, and the evaluation was carried out in the same manner. The results are shown in Table 1.

[Example 3]
Instead of the modified conjugated diene rubber (A-2) having a terminal modifying group and an alkyl group derived from 1-butanethiol, the modification having the terminal modifying group and the alkyl group derived from 1-octadecanethiol obtained in Production Example 4 A crosslinkable rubber composition was obtained in the same manner as in Example 1 except that 103.4 parts of the conjugated diene rubber (A-4) was used, and the evaluation was carried out in the same manner. The results are shown in Table 1.

[Example 4]
Instead of the modified conjugated diene rubber (A-2) having a terminal modifying group and an alkyl group derived from 1-butanethiol, the modification having the terminal modifying group and the alkyl group derived from 1-dodecanethiol obtained in Production Example 5 A crosslinkable rubber composition was obtained in the same manner as in Example 1 except that 103.4 parts of the conjugated diene rubber (A-5) was used, and the evaluation was carried out in the same manner. The results are shown in Table 1.

[Comparative Example 1]
Instead of the modified conjugated diene rubber (A-2) having a terminal modifying group and an alkyl group derived from 1-butanethiol, the modified conjugated diene rubber (A-1) having a terminal modifying group obtained in Production Example 1 A crosslinkable rubber composition was obtained and evaluated in the same manner as in Example 1 except that 103.4 parts were used. The results are shown in Table 1.

[Comparative Example 2]
Instead of the modified conjugated diene rubber (A-2) having an alkyl group derived from a terminal modified group and 1-butanethiol, the modified conjugated diene rubber having an alkyl group derived from 1-dodecanethiol obtained in Production Example 6 (A-7) A crosslinkable rubber composition was obtained in the same manner as in Example 1 except that 103.4 parts were used, and the evaluation was carried out in the same manner. The results are shown in Table 1.

実施例１～４、比較例２（変性共役ジエン系ゴム（Ａ－２）～（Ａ－５）、（Ａ－７））における、スチレン単位含有量およびビニル結合含有量は、アルキルチオール化合物を反応させる前のゴムにおける含有量である。

In Examples 1 to 4 and Comparative Example 2 (modified conjugated diene rubbers (A-2) to (A-5), (A-7)), the styrene unit content and the vinyl bond content are the alkylthiol compounds. It is the content in the rubber before the reaction.

From Table 1, the active end of the conjugated diene polymer chain having an active end is reacted with a denaturing agent having a functional group capable of interacting with silica, and then the denaturing agent is reacted with a radical initiator. According to the modified conjugated diene rubber obtained by reacting the crosslinked diene polymer chain with an alkylthiol compound, the increase in Mooney viscosity when a filler such as silica is blended is small, and the processability is excellent. Moreover, the rubber crosslinked product obtained by using the same was excellent in low heat generation property, wet grip property, abrasion resistance and steering stability (Examples 1 to 4).

On the other hand, when the modification reaction is carried out with a modifier having a functional group capable of interacting with silica but the reaction with the alkylthiol compound is not carried out, the rubber obtained by using the obtained modified conjugated diene rubber is used. The crosslinked product did not have sufficient effects of improving low heat generation, wet grip, wear resistance and steering stability (Comparative Example 1).
Further, when only the reaction with the alkylthiol compound is carried out without carrying out the modification reaction with the modifying agent having a functional group capable of interacting with silica, the obtained modified conjugated diene rubber is filled with silica or the like. The increase in Mooney viscosity is large when the agent is blended, and the processability is inferior. Moreover, the rubber crosslinked product obtained by using the agent has low heat generation property, wet grip property, abrasion resistance and steering stability. It was inferior (Comparative Example 1).

Claims (7)

The first step of polymerizing a monomer containing at least a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene-based polymer chain having an active terminal.
By reacting the active end of the conjugated diene polymer chain having an active end with a modifying agent having a functional group capable of interacting with silica, a conjugated diene polymer chain having a modifying group at the end is obtained. The second step and
A method for producing a modified conjugated diene-based rubber, comprising a third step of reacting an alkylthiol compound with a conjugated diene-based polymer chain having a modifying group at the terminal using a radical initiator. The method for producing a modified conjugated diene-based rubber according to claim 1, wherein the modifier is a silicon compound. A method for producing a rubber composition in which a modified conjugated diene-based rubber is obtained by the production method according to claim 1 or 2, and silica is added to the modified conjugated diene-based rubber. The method for producing a rubber composition according to claim 3, wherein the blending amount of silica in the rubber composition is 10 to 200 parts by weight with respect to 100 parts by weight of the rubber component in the rubber composition . The method for producing a rubber composition according to claim 3 or 4, wherein a cross-linking agent is further added . A method for producing a rubber crosslinked product in which a rubber composition is obtained by the production method according to claim 5 and the rubber composition is crosslinked. A method for producing a tire , wherein a rubber composition is obtained by the production method according to claim 5, and the rubber composition is crosslinked to produce a tire containing the rubber crosslinked product of the rubber composition.