Method for producing a disproportionated conjugated diene polymer, disproportionated conjugated diene polymer, method for producing a rubber composition, and method for producing a tire

Abstract

To provide a method for producing a branched conjugated diene-based polymer excellent in low fuel consumption performance, abrasion resistance, wet-skid resistance, and fracture strength.SOLUTION: A method for producing a branched conjugated diene-based polymer includes: a polymerizing step of obtaining a conjugated diene-based polymer having an active end by polymerizing or copolymerizing a conjugated diene compound, or the conjugated diene compound and an aromatic vinyl compound with an alkali metal compound or an alkaline earth metal compound used as a polymerization initiator; and a branching step of introducing a branch structure by reacting a styrene derivative as a branching agent with the active end of the conjugated diene-based polymer.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing a branched conjugated diene polymer, a branched conjugated diene polymer, a method for producing a rubber composition, and a method for producing a tire.

Background Art

[0002] Conventionally, from the viewpoint of environmental impact, the demand for lower fuel consumption in automobiles has been increasing. In particular, for automobile tires, improvement in low fuel consumption performance is required for the materials used in the tread portion that directly contacts the ground. In recent years, there has been a demand for the development of materials having low rolling resistance, that is, low hysteresis loss properties. At the same time, there is a trend towards lighter tires, and for this purpose, it is necessary to reduce the thickness of the tire tread portion. At the same time, a material with high wear resistance is required for the tire tread portion. On the other hand, the materials used in the tire tread portion are required to have excellent wet skid resistance and sufficient fracture properties in practical use from the viewpoint of safety.

[0003] Examples of materials that can meet the various requirements as described above include rubber materials containing a rubber-like polymer and a reinforcing filler such as carbon black or silica. When using a rubber material containing silica, it is possible to improve the balance between low hysteresis loss properties (an index of low fuel consumption) and wet skid resistance. Further, by introducing a functional group having an affinity or reactivity with silica at the molecular terminal portion of a highly mobile rubber-like polymer, the dispersibility of silica in the rubber material can be improved, and furthermore, the mobility of the molecular terminal portion of the rubber-like polymer can be reduced by bonding with silica particles, thereby reducing hysteresis loss. On the other hand, as a method for improving wear resistance, there is a method of increasing the molecular weight of the rubber-like polymer. However, when the molecular weight is increased, the processability tends to deteriorate when kneading the rubber-like polymer and the reinforcing filler. In view of such circumstances, in order to increase the molecular weight without impairing the processability, attempts have been made to introduce a branched structure into the rubbery polymer.

[0004] For example, conventionally, a resin composition of a modified conjugated diene polymer obtained by reacting alkoxysilanes containing an amino group with the active terminal of a conjugated diene polymer and silica has been proposed. In addition, a modified conjugated diene polymer having a branched structure introduced by subjecting the polymer active terminal and a polyfunctional silane compound to a coupling reaction has been proposed (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the method of introducing a branched structure into a conjugated diene polymer by subjecting the polymer active terminal and a polyfunctional silane compound to a coupling reaction, the degree of branching of the resulting modified conjugated diene polymer greatly depends on the number of reactive groups of the polyfunctional silane compound with the polymer active terminal, and does not exceed the number of reactive groups. From the viewpoint of synthetic feasibility, since there is a limit to the number of reactive groups that can be imparted to one polyfunctional silane, there is a problem that there is also a limit to the degree of branching of the resulting modified conjugated diene polymer.

[0007] Therefore, in the present invention, by introducing a branching point into the main chain, it is possible to produce a conjugated diene polymer with a higher degree of branching than when a branching structure is introduced into a conjugated diene polymer using only a modifier or a coupling agent, and it is also possible to adjust the length of the main chain and side chains. An object of the present invention is to provide a method for producing a branched conjugated diene polymer with a high degree of freedom in polymer design, and thereby provide a method for producing a branched conjugated diene polymer excellent in low fuel consumption, wear resistance, wet skid resistance, and breaking strength.

Means for Solving the Problems

[0008] As a result of intensive research and study to solve the above-described problems of the prior art, the present inventors have found a method for producing a branched conjugated diene polymer capable of introducing a branching point into the main chain by reacting a specific styrene derivative as a branching agent with a conjugated diene polymer having an active end, and have completed the present invention. That is, the present invention is as follows.

[0009] 〔1〕 A polymerization step of obtaining a conjugated diene polymer having an active end by polymerizing or copolymerizing a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound using an alkali metal compound or an alkaline earth metal compound as a polymerization initiator, A branching step of introducing a branched structure by reacting a styrene derivative as a branching agent with the active end of the conjugated diene polymer, A method for producing a branched conjugated diene polymer having the above steps. 〔2〕 The method for producing a branched conjugated diene polymer according to the above 〔1〕, further comprising a step of adding a conjugated diene compound and / or an aromatic vinyl compound to the reaction system during and / or after the branching step. 〔3〕 The method for producing a branched conjugated diene polymer according to the above 〔1〕 or 〔2〕, further comprising a reaction step of reacting a coupling agent or a polymerization terminator with the active end of the conjugated diene polymer obtained in the branching step. 〔4〕 The production method of the branched conjugated diene-based polymer according to [3], wherein the coupling agent has a nitrogen atom-containing group. [5] The production method of the branched conjugated diene-based polymer according to [3], wherein the polymerization terminator has a nitrogen atom-containing group. [6] The production method of the branched conjugated diene-based polymer according to [3] or [5], wherein the polymerization terminator is an alkoxy compound having a nitrogen atom-containing group. [7] The production method of the branched conjugated diene-based polymer according to [4], wherein the coupling agent is represented by the following formula (a).

[0010] [Chemical formula]

[0011] (In formula (a), R 1 ~R 4 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R 5 ~R 6 each independently represents an alkylene group having 1 to 20 carbon atoms.) m and n are integers from 1 to 3. In formula (a), a plurality of R 1 ~R 6 , m, and n may be the same or different. (In formula (b), X is represented by any one of the following general formulas (b) to (e).)

[0012] [Chemical formula]

[0013] (In formula (b), R 7 represents a hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group may have a partially branched structure or a cyclic structure. R 8 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and in the case of the hydrocarbon group, it may have a partially branched structure or a cyclic structure.)

[0014]

Chem.

[0015] (In formula (c), R 9 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and in the case of the hydrocarbon group, it may have a partially branched structure or a cyclic structure.)

[0016]

Chem.

[0017] (In formula (d), R 10 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and in the case of the hydrocarbon group, it may have a partially branched structure or a cyclic structure.)

[0018]

Chem.

[0019] (In formula (e), R 11 ~R 14 each independently represents an alkylene group having 1 to 20 carbon atoms. R 15 ~R 18 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, l and o each independently represent an integer of 1 to 3, and when there are a plurality of R 15 ~R 18 are each independent.)

[0020] 〔8〕 The method for producing a branched conjugated diene-based polymer according to any one of the above-mentioned 〔1〕 to 〔7〕, wherein the styrene derivative is a compound represented by the following formula (1) and / or the following formula (2).

[0021]

Chem.

[0022]

Chemical formula

[0023] (In formulas (1) and (2), R 1 represents any one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms, and may have a branched structure in a part thereof.) X 1 、X 2 、X 3 is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen.) Y 1 、Y 2 、Y 3 represents any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be the same or different from each other independently.)

[0024] 〔9〕 In the above formula (1), R 1 is a hydrogen atom, and Y 1 is any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. The method for producing a branched conjugated diene-based polymer according to the above 〔8〕.) 〔10〕 In the above formula (2), Y 2 is any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. The method for producing a branched conjugated diene-based polymer according to the above 〔8〕.) 〔11〕 In the above formula (1), R 1 is a hydrogen atom, and Y 1 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom. The method for producing a branched conjugated diene-based polymer according to the above 〔8〕.) 〔12〕 In the above formula (2), Y 2is an alkoxy group having 1 to 20 carbon atoms or a halogen atom, and Y 3 is a method for producing a branched conjugated diene polymer according to the above [8], which is an alkoxy group having 1 to 20 carbon atoms or a halogen atom.

[13] In the above formula (1), R 1 is a hydrogen atom, and Y 1 is a method for producing a branched conjugated diene polymer according to the above [8], which is an alkoxy group having 1 to 20 carbon atoms.

[14] In the above formula (1), R 1 is a hydrogen atom, X 1 is a single bond, and Y 1 is a method for producing a branched conjugated diene polymer according to the above [8], which is an alkoxy group having 1 to 20 carbon atoms.

[15] In the above formula (2), X 2 is a single bond, Y 2 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom, X 3 is a single bond, and Y 3 is a method for producing a branched conjugated diene polymer according to the above [8], which is an alkoxy group having 1 to 20 carbon atoms or a halogen atom.

[16] A conjugated diene polymer having an active terminal with a branched structure, and a compound represented by the following formula (a), and A branched conjugated diene polymer which is a reaction product thereof.

[0025] [Chemical formula]

[0026] (In formula (a), R 1 ~R 4 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R 5 ~R 6 each independently represents an alkylene group having 1 to 20 carbon atoms. m and n are integers from 1 to 3. In formula (A), a plurality of R 1 ~R6 m and n may be the same or different. In formula (a), X is represented by any one of the following general formulas (b) to (e).

[0027]

Chemical formula

[0028] (In formula (b), R 7 represents a hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group may have a partially branched structure or a cyclic structure. R 8 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. In the case of a hydrocarbon group, it may have a partially branched structure or a cyclic structure.)

[0029]

Chemical formula

[0030] (In formula (c), R 9 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. In the case of a hydrocarbon group, it may have a partially branched structure or a cyclic structure.)

[0031]

Chemical formula

[0032] (In formula (d), R 10 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. In the case of a hydrocarbon group, it may have a partially branched structure or a cyclic structure.)

[0033]

Chemical formula

[0034] (In formula (e), R 11 to R 14 each independently represent an alkylene group having 1 to 20 carbon atoms. R15 ~R 18 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, l and o each independently represent an integer of 1 to 3, and when there are a plurality of R 15 ~R 18 are each independent.)

[0035] 〔17〕 OR of the compound represented by the formula (a) 1 and / or OR 3 has a branched structure, and the branched conjugated diene polymer according to the above

[16] . 〔18〕 A rubber component containing 10% by mass or more of the branched conjugated diene polymer according to the above

[16] or

[17] , A rubber composition containing 5.0 parts by mass or more and 150 parts by mass or less of a filler with respect to 100 parts by mass of the rubber component. 〔19〕 A step of obtaining a branched conjugated diene polymer by the production method according to any one of the above [1] to

[15] , A step of obtaining a rubber component containing 10% by mass or more of the branched conjugated diene polymer, A step of obtaining a rubber composition by containing 5.0 parts by mass or more and 150 parts by mass or less of a filler with respect to 100 parts by mass of the rubber component, A method for producing a rubber composition having 〔20〕 A step of obtaining a rubber composition by the production method of the rubber composition according to the above

[19] , A step of molding the rubber composition to obtain a tire, A method for producing a tire having

Advantages of the Invention

[0036] According to the present invention, by introducing a branching point into the main chain, a conjugated diene polymer with a higher degree of branching can be produced than when only a coupling agent or a modifier is used, and the degree of freedom in polymer design is high enough to adjust the length of the main chain and side chains, thereby providing a method for producing a conjugated diene polymer excellent in low fuel consumption, wear resistance, wet skid resistance, and breaking strength.

Embodiment for Carrying Out the Invention

[0037] Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as "the present embodiments") will be described in detail. It should be noted that the following present embodiments are examples for explaining the present invention, and the present invention is not limited to the following embodiments. The present invention can be appropriately modified and implemented within the scope of its gist.

[0038] 〔Method for Producing Branched Conjugated Diene Polymer〕 The method for producing a branched conjugated diene polymer according to the present embodiment is a polymerization step of obtaining a conjugated diene polymer having an active terminal by polymerizing or copolymerizing a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound using an alkali metal compound or an alkaline earth metal compound as a polymerization initiator, and a branching step of introducing a branched structure by reacting a styrene derivative as a branching agent with the active terminal of the conjugated diene polymer. The conjugated diene polymer constituting the branched conjugated diene polymer may be any of a homopolymer of a single conjugated diene compound, a polymer of different types of conjugated diene compounds, i.e., a copolymer, and a copolymer of a conjugated diene compound and an aromatic vinyl compound. According to the method for producing a branched conjugated diene polymer of the present embodiment, by introducing a branching point into the main chain, a conjugated diene polymer with a higher degree of branching can be produced than when a branched structure is introduced into a conjugated diene polymer using only a coupling agent, and the length of the main chain and side chains can be adjusted.

[0039] (Polymerization Step) In the polymerization step of the method for producing a branched conjugated diene polymer of the present embodiment, an alkali metal compound or an alkaline earth metal compound is used as a polymerization initiator, and a conjugated diene compound, or a conjugated diene compound and an aromatic vinyl compound are polymerized or copolymerized to obtain a conjugated diene polymer having a living end. In the polymerization step, it is preferable to carry out polymerization by a growth reaction by a living anionic polymerization reaction, whereby a conjugated diene polymer having a living end can be obtained.

[0040] <Polymerization initiator> As the polymerization initiator, an alkali metal compound or an alkaline earth metal compound is used. It is preferable to use an organolithium-based compound as the polymerization initiator, and it is more preferable to use an organomono lithium compound. Examples of the organomono lithium compound include, but are not limited to, an organomono lithium compound of a low molecular weight compound and an organomono lithium compound of a solubilized oligomer. In addition, as for the bonding mode of the organic group and lithium of the organomono lithium compound, for example, any of a compound having a carbon-lithium bond, a compound having a nitrogen-lithium bond, and a compound having a tin-lithium bond can be used.

[0041] The amount of the polymerization initiator used is preferably determined by the molecular weight of the target conjugated diene polymer. The amount of the monomer such as the conjugated diene compound used relative to the amount of the polymerization initiator used is related to the degree of polymerization of the target conjugated diene polymer. That is, it tends to be related to the number average molecular weight and / or the weight average molecular weight. Therefore, in order to increase the molecular weight of the conjugated diene polymer, it is advisable to adjust it in the direction of reducing the polymerization initiator, and in order to decrease the molecular weight, it is advisable to adjust it in the direction of increasing the amount of the polymerization initiator.

[0042] From the perspective of being used as a method for introducing a nitrogen atom into a conjugated diene polymer, the organic monolithium compound is preferably an alkyllithium compound having a substituted amino group or a dialkylaminolithium. In this case, a conjugated diene polymer having a nitrogen atom consisting of an amino group at the polymerization initiation terminal can be obtained.

[0043] The substituted amino group is an amino group having no active hydrogen or having a structure in which active hydrogen is protected. Examples of the alkyllithium compound having an amino group having no active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium. Examples of the alkyllithium compound having an amino group having a structure in which active hydrogen is protected include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0044] Examples of the dialkylaminolithium include, but are not limited to, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium di-n-hexylamide, lithium diheptylamide, lithium diisopropylamide, lithium dioctylamide, lithium-di-2-ethylhexylamide, lithium didecylamide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, lithium methylphenethylamide, lithium hexamethylene imide, lithium pyrrolidide, lithium piperidide, lithium heptamethylene imide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithio-1,2,3,6-tetrahydropyridine.

[0045] These organolithium compounds having these substituted amino groups can also be used as oligomeric organolithium compounds solubilized in normal hexane or cyclohexane by reacting a small amount of polymerizable monomers such as 1,3-butadiene, isoprene, styrene and the like.

[0046] From the viewpoints of ease of industrial availability and ease of control of the polymerization reaction, the organolithium compound is preferably an alkyllithium compound. In this case, a conjugated diene polymer having an alkyl group at the polymerization initiation end can be obtained. Examples of the alkyllithium compound include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenyllithium. From the viewpoints of ease of industrial availability and ease of control of the polymerization reaction, n-butyllithium and sec-butyllithium are preferred as the alkyllithium compound.

[0047] These organolithium compounds may be used alone or in combination of two or more. They may also be used in combination with other organometallic compounds. Examples of the other organometallic compounds include alkaline earth metal compounds, other alkali metal compounds, and other organometallic compounds. Examples of the alkaline earth metal compounds include, but are not limited to, organomagnesium compounds, organocalcium compounds, and organostrontium compounds. Also included are compounds of alkoxides, sulfonates, carbonates, and amides of alkaline earth metals. Examples of the organomagnesium compounds include dibutylmagnesium and ethylbutylmagnesium. Examples of the other organometallic compounds include organoaluminum compounds.

[0048] In the polymerization process, the polymerization reaction mode is not limited to the following, but for example, a batch process (also referred to as a "batch type") and a continuous polymerization reaction mode can be mentioned. In the continuous process, one or two or more connected reactors can be used. As the continuous reactor, for example, a tank type with a stirrer or a tubular type is used. In the continuous process, preferably, the monomer, the inert solvent, and the polymerization initiator are continuously fed into the reactor, a polymer solution containing the polymer is obtained in the reactor, and the polymer solution is continuously discharged. As the batch reactor, for example, a tank type with a stirrer is used. In the batch process, preferably, the monomer, the inert solvent, and the polymerization initiator are fed, and if necessary, the monomer is continuously or intermittently added during the polymerization, a polymer solution containing the polymer is obtained in the reactor, and the polymer solution is discharged after the polymerization is completed. In the method for producing the branched conjugated diene polymer of the present embodiment, in the polymerization step, in order to obtain a conjugated diene polymer having active ends at a high ratio in the polymerization step, a continuous type that can continuously discharge the polymer and subject it to the next reaction in a short time is preferable. In the continuous process, the number of reactors is not particularly limited, and one or two or more connected reactors can be used. The reactor is preferably one in which the monomer and the polymerization initiator can be sufficiently contacted in the solution, and a tank type with a stirrer, a tubular type, etc. are used. The number of reactors can be appropriately selected, but from the viewpoint of saving space in the production equipment, one is preferable, and from the viewpoint of improving productivity, two or more are preferable. When using two or more reactors, it is more preferable to add the branching agent described later to the second and subsequent reactors.

[0049] The polymerization step of the conjugated diene polymer is preferably carried out in an inert solvent. Examples of the inert solvent include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Examples of the hydrocarbon solvent include, but are not limited to, aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; and hydrocarbons composed of mixtures thereof. Before subjecting to the polymerization reaction, treating allenes and acetylenes, which are impurities, with an organometallic compound tends to result in a conjugated diene polymer having a high concentration of active terminals, and tends to result in a modified conjugated diene polymer having a high modification rate, which is preferable.

[0050] In the polymerization step, a polar compound may be added. Thereby, an aromatic vinyl compound can be randomly copolymerized with a conjugated diene compound. Further, the polar compound tends to be also used as a vinylating agent for controlling the microstructure of the conjugated diene part. Furthermore, it tends to be effective for accelerating the polymerization reaction and the like.

[0051] Examples of the polar compound include, but are not limited to, ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butyrate, sodium tert-butyrate, and sodium amylate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used alone or in combination of two or more.

[0052] The amount of the polar compound used is not particularly limited and can be selected according to the purpose or the like, but it is preferably 0.01 mol or more and 100 mol or less per 1 mol of the polymerization initiator. Such a polar compound (vinylating agent) can be used in an appropriate amount according to the desired vinyl bond amount as an agent for adjusting the microstructure of the conjugated diene moiety of the conjugated diene polymer. Many polar compounds tend to have an effective randomizing effect in the copolymerization of a conjugated diene compound and an aromatic vinyl compound, and can be used as an agent for adjusting the distribution of the aromatic vinyl compound and also as an agent for adjusting the styrene block amount. As a method for randomizing a conjugated diene compound and an aromatic vinyl compound, for example, as described in JP-A-59-140211, a copolymerization reaction may be started with the total amount of styrene and a part of 1,3-butadiene, and the remaining 1,3-butadiene may be intermittently added during the copolymerization reaction.

[0053] The polymerization temperature in the polymerization step is preferably a temperature at which living anionic polymerization proceeds, and more preferably 0°C or higher and 120°C or lower from the viewpoint of productivity. By being in such a range, there is a tendency that the reaction amounts of the branching agent and the coupling agent with respect to the active terminal after the polymerization is completed can be sufficiently ensured. Even more preferably, it is 50°C or higher and 100°C or lower.

[0054] (Branching step) In the method for producing a branched conjugated diene polymer of the present embodiment, a branching step is carried out in which a styrene derivative is reacted as a branching agent with the active terminal of the conjugated diene polymer obtained in the polymerization step. While the branching agent maintains its polymerization activity and polymerizes with the monomer, the active end of another polymer chain reacts with the functional group of the branching agent, thereby forming a branched structure in the polymer. It is also possible to form a further branched structure by further polymerizing and reacting with the monomer and the branching agent in the branched conjugated diene polymer having the branched structure, or to react with a modifier having a functional group to obtain a modified conjugated diene polymer, or to further extend the polymer chain by a coupling reaction. Thus, while continuing the polymerization reaction as an aromatic vinyl compound, by using a styrene derivative in which the functional group reacts with the active end of the polymer as a branching agent, the target branched conjugated diene polymer can be obtained.

[0055] <Branching agent> The styrene derivative, which is a branching agent used in the branching step, needs to have a main skeleton in which only one active end remains at the branching site after the branching reaction from the viewpoints of polymerization continuity and prevention of gelation. Further, the styrene derivative portion formed after the branching reaction needs to have reactivity to sufficiently react with other polymerization active ends. More specifically, the styrene derivative is preferably a compound having a vinyl group and a functional group that quantitatively reacts with the polymerization active end of living anionic polymerization on the benzene ring. The functional group of the styrene derivative and the polymerization active end react one-to-one, and while the functional group detaches to form a single bond, the vinyl group undergoes a polymerization reaction with other monomers in the reactor, thereby forming a branched structure in the polymer. The functional group other than the vinyl group of the styrene derivative is a group that detaches by a nucleophilic substitution reaction with the polymerization active end of living anionic polymerization, and examples thereof include an alkoxy group, a halogen, an ester group, a formyl group, a ketone group, an amide group, an acid chloride group, an acid anhydride group, and an epoxy group. By having such a structure, while the styrene derivative maintains its polymerization activity as styrene, the styrene derivative is incorporated into the main chain, and another monomer polymerizes at the terminal where the activity is maintained, causing the polymer chain to further elongate. Also, the functional group of the incorporated styrene derivative reacts with the active terminal of another polymer chain to form a bond, resulting in a branched structure. As this reaction repeatedly occurs, the branching of the polymer chain increases, the polymer structure becomes more complex, and the molecular weight becomes larger. From the viewpoints of polymerization continuity and controllability of the polymer structure, it is also necessary that the functional group that detaches after the styrene derivative part reacts with the active terminal of another polymer chain has little inhibitory effect on polymerization. Here, "little inhibitory effect on polymerization" means that there are few side reactions of anionic polymerization such as chain transfer reaction, deactivation during polymerization, and decrease in activity due to an increase in the degree of association of the polymer. The functional group possessed by the styrene derivative needs to not overly improve the polymerization activity and further needs to not deactivate the polymerization activity. When polymerizing a polymer by living anionic polymerization, it is important that it does not have a hydrogen atom as a functional group that does not deactivate the active terminal and is a hard base in the definition based on Pearson's HASB rule. More specifically, an alkoxy group or a halogen group can be mentioned. From among these, from the viewpoints of reactivity with the active terminal and that the detached functional group does not inhibit polymerization, the structure of the styrene derivative as a branching agent used in the production method of this embodiment can be selected. More specifically, it is preferable to use a branching agent represented by the following formula (1) having a styrene skeleton as the main skeleton or a formula (2) having a diphenylethylene skeleton as the main skeleton from the viewpoints of suppressing the chain transfer reaction, suppressing the deactivation of the active terminal, and preventing gelation.

[0056]

Chemical formula

[0057]

Chemical formula

[0058] (In formulas (1) and (2), R 1 represents any one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms, and may have a branched structure in a part thereof.) X 1 、X 2 、X 3 is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen.) Y 1 、Y 2 、Y 3 represents any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be the same or different independently of each other.)

[0059] The styrene derivative, which is a branching agent used in the branching step, from the viewpoint of improving the degree of branching of the polymerization, in the formula (1), R 1 is preferably a hydrogen atom, and Y 1 is preferably any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom.)

[0060] Also, in the present embodiment, the styrene derivative, which is a branching agent used in the branching step, from the viewpoint of improving the degree of branching, in the formula (2), Y 2 is preferably any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom.)

[0061] Also, in the present embodiment, the styrene derivative, which is a branching agent used in the branching step, from the viewpoints of the continuity of polymerization and improving the degree of branching, in the formula (1), R 1 is preferably a hydrogen atom, and Y 1 is more preferably an alkoxy group having 1 to 20 carbon atoms or a halogen atom.)

[0062] In addition, in the present embodiment, the styrene derivative, which is a branching agent used in the branching step, from the viewpoints of polymerization continuity and improvement of the degree of branching, in the formula (2), Y 2 is an alkoxy group or a halogen atom, and Y 3 is more preferably an alkoxy group having 1 to 20 carbon atoms or a halogen atom.

[0063] In addition, in the present embodiment, the styrene derivative, which is a branching agent used in the branching step, from the viewpoints of polymerization continuity, improvement of the degree of branching, and improvement of the modification rate, in the formula (1), R 1 is a hydrogen atom, and Y 1 is more preferably an alkoxy group having 1 to 20 carbon atoms.

[0064] In addition, in the present embodiment, the styrene derivative, which is a branching agent used in the branching step, from the viewpoints of polymerization continuity, improvement of the degree of branching, and further improvement of the modification rate, in the formula (1), R 1 is a hydrogen atom, X 1 is a single bond, and Y 1 is more preferably an alkoxy group having 1 to 20 carbon atoms.

[0065] In addition, in the present embodiment, the styrene derivative, which is a branching agent used in the branching step, from the viewpoints of polymerization continuity, improvement of the degree of branching, and further improvement of the modification rate, in the formula (2), X 2 is a single bond, and Y 2 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom, X 3 is a single bond, and Y 3 is more preferably an alkoxy group having 1 to 20 carbon atoms or a halogen atom.

[0066] Examples of the branching agent represented by the formula (1) include, but are not limited to, trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane, trimethoxy(3-vinylphenyl)silane, triethoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)silane, tributoxy(3-vinylphenyl)silane, triisopropoxy(3-vinylphenyl)silane, trimethoxy(2-vinylphenyl)silane, triethoxy(2-vinylphenyl)silane, tripropoxy(2-vinylphenyl)silane, tributoxy(2-vinylphenyl)silane, triisopropoxy(2-vinylphenyl)silane, dimethoxymethyl(4-vinylphenyl)silane, diethoxymethyl(4-vinylphenyl)silane, dipropoxymethyl(4-vinylphenyl)silane, dibutoxymethyl(4-vinylphenyl)silane, diisopropoxymethyl(4-vinylphenyl)silane, dimethoxymethyl(3-vinylphenyl)silane, diethoxymethyl(3-vinylphenyl)silane, dipropoxymethyl(3-vinylphenyl)silane, dibutoxymethyl(3-vinylphenyl)silane, diisopropoxymethyl(3-vinylphenyl)silane, dimethoxymethyl(2-vinylphenyl)silane, diethoxymethyl(2-vinylphenyl)silane, dipropoxymethyl(2-vinylphenyl)silane, dibutoxymethyl(2-vinylphenyl)silane, diisopropoxymethyl(2-vinylphenyl)silane, dimethylmethoxy(4-vinylphenyl)silane, dimethylethoxy(4-vinylphenyl)silane, dimethylpropoxy(4-vinylphenyl)silane, dimethylbutoxy(4-vinylphenyl)silane, dimethylisopropoxy(4-vinylphenyl)silane, dimethylmethoxy(3-vinylphenyl)silane, dimethylethoxy(3-vinylphenyl)silane, dimethylpropoxy(3-vinylphenyl)silane, dimethylbutoxy(3-vinylphenyl)silane, dimethylisopropoxy(3-vinylphenyl)silane, dimethylmethoxy(2-vinylphenyl)silane,Dimethylethoxy(2-vinylphenyl)silane, dimethylpropoxy(2-vinylphenyl)silane, dimethylbutoxy(2-vinylphenyl)silane, dimethylisopropoxy(2-vinylphenyl)silane, trimethoxy(4-isopropenylphenyl)silane, triethoxy(4-isopropenylphenyl)silane, tripropoxy(4-isopropenylphenyl)silane, tributoxy(4-isopropenylphenyl)silane, triisopropoxy(4-isopropenylphenyl)silane, trimethoxy(3-isopropenylphenyl)silane, triethoxy(3-isopropenylphenyl)silane, tripropoxy(3-isopropenylphenyl)silane, tributoxy(3-isopropenylphenyl)silane, triisopropoxy(3-isopropenylphenyl)silane, trimethoxy(2-isopropenylphenyl)silane, triethoxy(2-isopropenylphenyl)silane, tripropoxy(2-isopropenylphenyl)silane, tributoxy(2-isopropenylphenyl)silane, triisopropoxy(2-isopropenylphenyl)silane, dimethoxymethyl(4-isopropenylphenyl)silane, diethoxymethyl(4-isopropenylphenyl)silane, dipropoxymethyl(4-isopropenylphenyl)silane, dibutoxymethyl(4-isopropenylphenyl)silane, diisopropoxymethyl(4-isopropenylphenyl)silane, dimethoxymethyl(3-isopropenylphenyl)silane, diethoxymethyl(3-isopropenylphenyl)silane, dipropoxymethyl(3-isopropenylphenyl)silane, dibutoxymethyl(3-isopropenylphenyl)silane, diisopropoxymethyl(3-isopropenylphenyl)silane, dimethoxymethyl(2-isopropenylphenyl)silane, diethoxymethyl(2-isopropenylphenyl)silane, dipropoxymethyl(2-isopropenylphenyl)silane, dibutoxymethyl(2-isopropenylphenyl)silane, diisopropoxymethyl(2-isopropenylphenyl)silane, dimethylmethoxy(4-isopropenylphenyl)silane, dimethylethoxy(4-isopropenylphenyl)silane, dimethylpropoxy(4-isopropenylphenyl)silane,Dimethylbutoxy(4-isopropenylphenyl)silane, dimethylisopropoxy(4-isopropenylphenyl)silane, dimethylmethoxy(3-isopropenylphenyl)silane, dimethylethoxy(3-isopropenylphenyl)silane, dimethylpropoxy(3-isopropenylphenyl)silane, dimethylbutoxy(3-isopropenylphenyl)silane, dimethylisopropoxy(3-isopropenylphenyl)silane, dimethylmethoxy(2-isopropenylphenyl)silane, dimethylethoxy(2-isopropenylphenyl)silane, dimethylpropoxy(2-isopropenylphenyl)silane, dimethylbutoxy(2-isopropenylphenyl)silane, dimethylisopropoxy(2-isopropenylphenyl)silane, trichloro(4-vinylphenyl)silane, trichloro(3-vinylphenyl)silane, trichloro(2-vinylphenyl)silane, tribromo(4-vinylphenyl)silane, tribromo(3-vinylphenyl)silane, tribromo(2-vinylphenyl)silane, dichloromethyl(4-vinylphenyl)silane, dichloromethyl(3-vinylphenyl)silane, dichloromethyl(2-vinylphenyl)silane, dibromomethyl(4-vinylphenyl)silane, dibromomethyl(3-vinylphenyl)silane, dibromomethyl(2-vinylphenyl)silane, dimethylchloro(4-vinylphenyl)silane, dimethylchloro(3-vinylphenyl)silane, dimethylchloro(2-vinylphenyl)silane, dimethylbromo(4-vinylphenyl)silane, dimethylbromo(3-vinylphenyl)silane, dimethylbromo(2-vinylphenyl)silane, Trimethoxy(4-vinylbenzyl)silane, triethoxy(4-vinylbenzyl)silane, tripropoxy(4-vinylbenzyl)silane, etc. can be mentioned. Among these, trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane, trimethoxy(3-vinylphenyl)silane, triethoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)silane, tributoxy(3-vinylphenyl)silane, triisopropoxy(3-vinylphenyl)silane, trichloro(4-vinylphenyl)silane are preferred, trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane, trimethoxy(4-vinylbenzyl)silane, triethoxy(4-vinylbenzyl)silane are more preferred, and trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane are even more preferred.

[0067] The branching agent represented by the formula (2) is not limited to the following, for example, 1,1-Bis(4-trimethoxysilylphenyl)ethylene, 1,1-bis(4-triethoxysilylphenyl)ethylene, 1,1-bis(4-tripropoxysilylphenyl)ethylene, 1,1-bis(4-tripentoxysilylphenyl)ethylene, 1,1-bis(4-triisopropoxysilylphenyl)ethylene, 1,1-bis(3-trimethoxysilylphenyl)ethylene, 1,1-bis(3-triethoxysilylphenyl)ethylene, 1,1-bis(3-tripropoxysilylphenyl)ethylene, 1,1-bis(3-tripentoxysilylphenyl)ethylene, 1,1-bis(3-triisopropoxysilylphenyl)ethylene, 1,1-bis(2-trimethoxysilylphenyl)ethylene, 1,1-bis(2-triethoxysilylphenyl)ethylene, 1,1-bis(3-tripropoxysilylphenyl)ethylene, 1,1-bis(2-tripentoxysilylphenyl)ethylene, 1,1-bis(2-triisopropoxysilylphenyl)ethylene, 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(diethylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(dipropylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(dimethylethoxysilyl)phenyl)ethylene, 1,1-bis(4-(diethylethoxysilyl)phenyl)ethylene, 1,1-bis(4-(dipropylethoxysilyl)phenyl)ethylene, 1,1-bis(4-trimethoxysilylbenzyl)ethylene, 1,1-bis(4-triethoxysilylbenzyl)ethylene, 1,1-bis(4-tripropoxysilylbenzyl)ethylene, 1,1-bis(4-tripentoxysilylbenzyl)ethylene, are exemplified. Among these, 1,1-bis(4-trimethoxysilylphenyl)ethylene, 1,1-bis(4-triethoxysilylphenyl)ethylene, 1,1-bis(4-tripropoxysilylphenyl)ethylene, 1,1-bis(4-tripentoxysilylphenyl)ethylene, 1,1-bis(4-triisopropoxysilylphenyl)ethylene are preferred, and 1,1-bis(4-trimethoxysilylphenyl)ethylene is more preferred. By using the branching agents represented by the formulas (1) and (2), the number of branches is improved, and the effects of improving the abrasion resistance and processability can be obtained.

[0068] The timing of adding the branching agent is not particularly limited and can be selected according to the purpose and the like. However, from the viewpoints of improving the absolute molecular weight of the branched conjugated diene polymer and the coupling rate, after adding the polymerization initiator, the timing when the raw material conversion rate is 20% or more is preferable, more preferably 40% or more, still more preferably 50% or more, even more preferably 65% or more, and even more preferably 75% or more. Also, during and / or after the branching step, a monomer which is a desired raw material may be additionally added, and the polymerization step may be continued after the branching step, and the above-described content may be repeated. Note that after the branching step is meant to be after adding the branching agent. The monomer to be added is not particularly limited, but is preferably a conjugated diene compound and / or an aromatic vinyl compound. In particular, when adding a monomer during the branching step, from the viewpoint of improving the modification rate due to the relaxation of steric hindrance at the branching point of the conjugated diene polymer, it is preferably 5% or more, more preferably 10% or more, still more preferably 15% or more, even more preferably 20% or more, and even more preferably 25% or more of the total amount of the conjugated diene monomer used in the polymerization step, for example, the total amount of butadiene. In such a case, in particular, from the viewpoint of improving the modification rate, it is preferable to add a monomer in an amount of 5% or more of the total amount of the conjugated diene monomer used in the polymerization step, for example, the total amount of butadiene, during the branching step using a continuous polymerization process. Since the length of the main chain and side chain can be adjusted by the timing of adding the branching agent and the amount of the monomer to be added, the degree of freedom in polymer design is high.

[0069] In the method for producing a branched conjugated diene-based polymer according to this embodiment, the branched structure of the branched conjugated diene-based polymer obtained in the branching step is preferably 3 to 24 branches, more preferably 4 to 20 branches, and even more preferably 5 to 18 branches. By making it 24 branches or less, it tends to be easy to react with a modifier having a functional group to form a modified conjugated diene-based polymer, or to further extend the polymer chain by a coupling reaction. By making it 3 branches or more, the resulting polymer tends to be excellent in processability and abrasion resistance.

[0070] The addition amount of the branching agent is not particularly limited, and the addition amount can be selected according to the purpose and the like. From the viewpoints of improving the terminal termination reaction rate of the conjugated diene-based polymer, improving the coupling rate, and the continuity of polymerization after branching, with respect to the amount of the active polymerization initiator, the molar ratio of the branching agent is preferably 1 / 2 or less and 1 / 100 or more, more preferably 1 / 3 or less and 1 / 50 or more, even more preferably 1 / 4 or less and 1 / 30 or more, even more preferably 1 / 6 or less and 1 / 25 or more, and even more preferably 1 / 8 or less and 1 / 12 or more.

[0071] Also, as described above, during and / or after the branching step, monomers may be additionally added to continue the polymerization step after branching. After the additional addition of the monomers, a branching agent may be further added, and the addition of the monomers may be repeated. By adding monomers, the steric hindrance around the branch point is relaxed, resulting in the effects of improving the continuity of polymerization, the coupling rate, and the modification rate. Thereby, while increasing the molecular weight of the polymer, a branched structure can be formed at a desired position. The monomers to be added may be aromatic vinyls such as styrene, conjugated diene compounds such as butadiene, or mixtures thereof, and may be the same as or different from the types and ratios of the monomers polymerized first. However, from the viewpoint of the continuity of polymerization, conjugated diene compounds are preferred. From the viewpoint of improving the heat resistance of the polymer, it is preferable to add an aromatic vinyl compound.

[0072] In the production method of this embodiment, the branched conjugated diene polymer obtained in the branching step preferably has a Mooney viscosity measured at 110°C of 10 or more and 150 or less, more preferably 15 or more and 140 or less, still more preferably 20 or more and 130 or less. Even more preferably, it is 30 or more and 100 or less. When the Mooney viscosity is within the above range, the branched conjugated diene polymer obtained by the production method of this embodiment tends to be excellent in processability and abrasion resistance.

[0073] In the production method of this embodiment, the weight average molecular weight of the branched conjugated diene polymer obtained in the branching step is preferably 10,000 or more and 1,500,000 or less, more preferably 100,000 or more and 1,000,000 or less, and still more preferably 200,000 or more and 900,000 or less. When the weight average molecular weight is within the above range, the branched conjugated diene polymer obtained by the production method of this embodiment tends to be excellent in processability, abrasion resistance, and the balance of these properties. When producing a branched conjugated diene polymer, in order for the weight average molecular weight to reach a range of 100,000 or more and 1,000,000 or less, it is necessary to control the addition amount of the branching agent in a molar ratio of 1 / 3 or less and 1 / 5 or more with respect to the polymerization initiator, while preventing all of the polymerization initiator from being consumed before the coupling step while forming branches, and making the functional group number of the coupling agent 2-functional or more. In order for the weight average molecular weight to reach a range of 200,000 or more and 900,000 or less, it is necessary to control the addition amount of the branching agent in a molar ratio of 1 / 3 or less and 1 / 50 or more with respect to the polymerization initiator, while making the functional group number of the coupling agent 3-functional or more. When producing a modified branched conjugated diene polymer, in order for the weight average molecular weight to reach a range of 100,000 or more and 1,000,000 or less, in order to prevent all of the polymerization initiator from being consumed before the coupling step while forming branches, it is necessary to control the addition amount of the branching agent in a range of 1 / 3 or less and 1 / 50 or more in terms of molar ratio with respect to the polymerization initiator, and to make the functional group number of the coupling agent 2 or more. In order for the weight average molecular weight to reach a range of 200,000 or more and 900,000 or less, it is necessary to control the addition amount of the branching agent in a range of 1 / 3 or less and 1 / 50 or more in terms of molar ratio with respect to the polymerization initiator, and to make the functional group number of the coupling agent 3 or more.

[0074] The branched conjugated diene polymer obtained by the production method of this embodiment may be a polymer of a conjugated diene monomer and a branching agent, or may be a copolymer of a conjugated diene monomer, a branching agent, and other monomers. For example, when a conjugated diene monomer is butadiene or isoprene and this is polymerized with a branching agent containing an aromatic vinyl moiety, the polymer chain is a so-called polybutadiene or polyisoprene, and becomes a polymer containing a structure derived from aromatic vinyl in the branched portion. By having such a structure, it is possible to improve the linearity per polymer chain and the crosslink density after vulcanization, thereby achieving the effect of improving the wear resistance of the polymer. Therefore, it is suitable for applications such as tires, resin modification, automotive interior and exterior parts, vibration-proof rubber, and footwear. When using the conjugated diene polymer for tire tread applications, a copolymer of a conjugated diene monomer, an aromatic vinyl monomer, and a branching agent is preferred. In the copolymer for this application, the amount of bound conjugated diene is preferably 40% by mass or more and 100% by mass or less, and more preferably 55% by mass or more and 80% by mass or less. In addition, the amount of bound aromatic vinyl in the branched conjugated diene polymer obtained by the production method of this embodiment is not particularly limited, but is preferably 0% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 45% by mass or less. When the amount of conjugated diene units and the amount of conjugated aromatic vinyl units are within the above ranges, the balance between low hysteresis loss property and wet skid resistance, abrasion resistance, and fracture characteristics of the vulcanizate tend to be excellent. Here, the amount of conjugated aromatic vinyl units can be measured by ultraviolet absorption of phenyl groups, and from this, the amount of conjugated diene units can also be determined. Specifically, it can be measured according to the method described in the examples below.

[0075] In the branched conjugated diene polymer obtained by the production method of this embodiment, the amount of vinyl bonds in the conjugated diene bond units is not particularly limited, but is preferably 10 mol% or more and 75 mol% or less, and more preferably 20 mol% or more and 65 mol% or less. When the amount of vinyl bonds is within the above range, the balance between low hysteresis loss property and wet skid resistance, abrasion resistance, and fracture strength of the vulcanizate tend to be excellent. Here, when the branched conjugated diene polymer is a copolymer of butadiene and styrene, the amount of vinyl bonds (1,2-bond amount) in the butadiene bond units can be determined by the method of Hampton (R.R. Hampton, Analytical Chemistry, 21, 923 (1949)). Specifically, it can be measured by the method described in the examples below.

[0076] Regarding the microstructure of the branched conjugated diene polymer, each bond amount in the branched conjugated diene polymer obtained by the production method of this embodiment is within the above-mentioned numerical range, and further, when the glass transition temperature of the branched conjugated diene polymer is in the range of -80°C or higher and -15°C or lower, a vulcanizate with an even more excellent balance between low hysteresis loss property and wet skid resistance can tend to be obtained. Regarding the glass transition temperature, in accordance with ISO 22768:2006, the DSC curve is recorded while increasing the temperature in a predetermined temperature range, and the peak top (Inflection point) of the DSC differential curve is taken as the glass transition temperature.

[0077] When the branched conjugated diene polymer obtained by the production method of the present embodiment is a conjugated diene-aromatic vinyl copolymer, it is preferable that the number of blocks in which 30 or more aromatic vinyl units are linked is small or non-existent. More specifically, when the branched conjugated diene polymer obtained by the production method of the present embodiment is a butadiene-styrene copolymer, in a known method of decomposing the polymer by the method of Kolthoff (the method described in I.M. KOLTHOFF, et al., J. Polym. Sci. 1, 429 (1946)) and analyzing the amount of polystyrene insoluble in methanol, the block in which 30 or more aromatic vinyl units are linked is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, based on the total amount of the branched conjugated diene polymer.

[0078] When the branched conjugated diene polymer obtained by the production method of the present embodiment is a conjugated diene-aromatic vinyl copolymer, from the viewpoint of improving fuel efficiency performance, it is preferable that the proportion of aromatic vinyl units existing alone is larger. Specifically, when the branched conjugated diene polymer obtained by the production method of the present embodiment is a butadiene-styrene copolymer, when the branched conjugated diene polymer is decomposed by the method of ozonolysis known as the method of Tanaka et al. (Polymer, 22, 1721 (1981)) and the styrene chain distribution is analyzed by GPC, it is preferable that the amount of isolated styrene is 40% by mass or more and the amount of chain styrene structures with 8 or more styrene chains is 5.0% by mass or less with respect to the total amount of bound styrene. In this case, the resulting vulcanized rubber tends to have excellent performance with particularly low hysteresis loss.

[0079] (Reaction step) In the method for producing a branched conjugated diene polymer according to the present embodiment, a coupling step or a polymerization termination step is preferably carried out on the active terminal of the conjugated diene polymer obtained through the above-described polymerization step and branching step. In the coupling step, a coupling agent, for example, a polyfunctional reactive compound having three or more functional groups, is used for coupling. In the polymerization termination step, a polymerization terminator, for example, a reactive compound having two or less functional groups, is used for reaction. Hereinafter, the step of reacting a coupling agent (coupling step) or the step of causing polymerization termination (polymerization termination step) are collectively referred to as a reaction step. In the reaction step, a coupling agent or a polymerization terminator is reacted with one end of the active terminal of the conjugated diene polymer.

[0080] <Coupling Step> In the method for producing a conjugated diene polymer according to the present embodiment, it is preferable to have a coupling step of coupling the conjugated diene polymer obtained through the above-described polymerization and branching steps with a coupling agent. By the coupling step, the molecular chain can be efficiently lengthened, and by using a coupling agent having three or more functional groups, branches can also be introduced into the polymer. Although the function of forming branches is common to the step of using a branching agent, performing it in the coupling step is preferable from the viewpoint that branches can be formed while introducing a desired element such as nitrogen, sulfur, or silicon using a known coupling agent. Examples of the coupling step include a coupling step of performing coupling on the active terminal of the conjugated diene polymer using a polyfunctional reactive compound having three or more functional groups, or a coupling step of performing coupling using a coupling agent having a nitrogen atom-containing group (hereinafter, may sometimes be collectively referred to as a "coupling agent"). A coupling step of performing coupling using a coupling agent represented by the following formula (a) is more preferable.

[0081] In the coupling step, for example, a polyfunctional reactive compound having three or more functional groups, a coupling agent having a nitrogen atom-containing group, or a coupling agent represented by the following formula (a) is used to perform a coupling reaction on one end of the active terminal of the conjugated diene polymer, and a branched conjugated diene polymer can be obtained.

[0082] [Reactive compound with three or more functional groups] In the method for producing a branched conjugated diene polymer of the present embodiment, the reactive compound having three or more functional groups used in the coupling step is preferably a reactive compound having three or more functional groups and having a silicon atom.

[0083] Examples of the reactive compound having three or more functional groups and having a silicon atom include, but are not limited to, halogenated silane compounds, epoxidized silane compounds, vinylated silane compounds, alkoxysilane compounds, and the like.

[0084] Examples of the halogenated silane compound as the coupling agent include, but are not limited to, methyltrichlorosilane, tetrachlorosilane, tris(trimethylsiloxy)chlorosilane, tris(dimethylamino)chlorosilane, hexachlorodisilane, bis(trichlorosilyl)methane, 1,2-bis(trichlorosilyl)ethane, 1,2-bis(methyldichlorosilyl)ethane, 1,4-bis(trichlorosilyl)butane, 1,4-bis(methyldichlorosilyl)butane, and the like.

[0085] Examples of the epoxidized silane compound as the coupling agent include, but are not limited to, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, epoxy-modified silicone, and the like.

[0086] Examples of the alkoxysilane compound as the coupling agent include, but are not limited to, tetramethoxysilane, tetraethoxysilane, triphenoxymethylsilane, 1,2-bis(triethoxysilyl)ethane, methoxy-substituted polyorganosiloxane, and the like.

[0087] [Coupling agent having a nitrogen atom-containing group] Examples of the coupling agent having a nitrogen atom-containing group include, but are not limited to, for example, isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, carbonyl compounds having a nitrogen atom-containing group, vinyl compounds having a nitrogen atom-containing group, epoxy compounds having a nitrogen atom-containing group, alkoxysilane compounds having a nitrogen atom-containing group, and protected amine compounds having a nitrogen atom-containing group and capable of forming a primary or secondary amine.

[0088] In the coupling agent having a nitrogen atom-containing group, examples of the nitrogen atom-containing functional group preferably include a functional group derived from an amine compound having no active hydrogen. Examples of the amine compound include tertiary amine compounds and protected amine compounds in which the above active hydrogen is substituted with a protecting group. Other compounds capable of forming a nitrogen atom-containing functional group include imine compounds represented by the general formula -N=C and alkoxysilane compounds bonded to the nitrogen atom-containing group.

[0089] Examples of the isocyanate compound as the coupling agent having a nitrogen atom-containing group include, but are not limited to, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, polymeric type diphenylmethane diisocyanate (C-MDI), phenyl isocyanate, isophorone diisocyanate, hexamethylene diisocyanate, butyl isocyanate, 1,3,5-benzene triisocyanate, and the like.

[0090] Examples of the isocyanuric acid derivative which is a coupling agent having a nitrogen atom-containing group include, but are not limited to, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate, 1,3,5-tris(3-triethoxysilylpropyl)isocyanurate, 1,3,5-tri(oxiran-2-yl)-1,3,5-triazinane-2,4,6-trione, 1,3,5-tris(isocyanatomethyl)-1,3,5-triazinane-2,4,6-trione, 1,3,5-trivinyl-1,3,5-triazinane-2,4,6-trione and the like.

[0091] Examples of the carbonyl compound which is a coupling agent having a nitrogen atom-containing group include, but are not limited to, 1,3-dimethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 1-methyl-3-(2-methoxyethyl)-2-imidazolidinone, N-methyl-2-pyrrolidone, N-methyl-2-piperidone, N-methyl-2-quinolone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, methyl-2-pyridyl ketone, methyl-4-pyridyl ketone, propyl-2-pyridyl ketone, di-4-pyridyl ketone, 2-benzoylpyridine, N,N,N',N'-tetramethylurea, N,N-dimethyl-N',N'-diphenylurea, methyl N,N-diethylcarbamate, N,N-diethylacetamide, N,N-dimethyl-N',N'-dimethylaminoacetamide, N,N-dimethylpicolinamide, N,N-dimethylisonicotinamide and the like.

[0092] Examples of the vinyl compound which is a coupling agent having a nitrogen atom-containing group include, but are not limited to, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N-methylmaleimide, N-methylphthalimide, N,N-bistrimethylsilylacrylamide, morpholinoacrylamide, 3-(2-dimethylaminoethyl)styrene, (dimethylamino)dimethyl-4-vinylphenylsilane, 4,4'-vinylidenebis(N,N-dimethylaniline), 4,4'-vinylidenebis(N,N-diethylaniline), 1,1-bis(4-morpholinophenyl)ethylene, 1-phenyl-1-(4-N,N-dimethylaminophenyl)ethylene, and the like.

[0093] Examples of the epoxy compound which is a coupling agent having a nitrogen atom-containing group include, but are not limited to, a hydrocarbon compound containing an epoxy group bonded to an amino group, and further a hydrocarbon compound containing an epoxy group bonded to an ether group. Examples of such an epoxy compound include, but are not limited to, an epoxy compound represented by the general formula (i).

[0094] [Chemical formula]

[0095] In the above formula (i), R is a divalent or higher hydrocarbon group, or a divalent or higher organic group having at least one polar group selected from the group consisting of polar groups having oxygen such as ether, epoxy, and ketone, polar groups having sulfur such as thioether and thioketone, and polar groups having nitrogen such as a tertiary amino group and an imino group.

[0096] The hydrocarbon group having a valency of 2 or more is a hydrocarbon group which may be saturated or unsaturated, linear, branched or cyclic, and includes an alkylene group, an alkenylene group, a phenylene group, etc. Preferably, it is a hydrocarbon group having 1 to 20 carbon atoms. For example, methylene, ethylene, butylene, cyclohexylene, 1,3-bis(methylene)-cyclohexane, 1,3-bis(ethylene)-cyclohexane, o-, m-, p-phenylene, m-, p-xylene, bis(phenylene)-methane, etc. may be mentioned.

[0097] In the above formula (i), R 1 , R 4 is a hydrocarbon group having 1 to 10 carbon atoms, and R 1 , R 4 may be the same as or different from each other. In the above formula (i), R 2 , R 5 is hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, and R 2 , R 5 may be the same as or different from each other. In the above formula (i), R 3 is a hydrocarbon group having 1 to 10 carbon atoms or has the structure of the following formula (ii). R 1 , R 2 , R 3 may form a cyclic structure bonded to each other. Also, when R 3 is a hydrocarbon group, it may form a cyclic structure bonded to R. In the case of the above cyclic structure, the form in which N bonded to R 3 and R are directly bonded may also be possible. In the above formula (i), n is an integer of 1 or more, and m is 0 or an integer of 1 or more.

[0098]

Chemical formula

[0099] In the above formula (ii), R 1 , R 2 are R 1 , R 2Defined in the same manner, R 1 , R 2 may be the same as or different from each other.

[0100] As the epoxy compound which is a coupling agent having a nitrogen atom-containing group, those having an epoxy group-containing hydrocarbon group are preferable, and those having a glycidyl group-containing hydrocarbon group are more preferable.

[0101] The epoxy group-containing hydrocarbon group bonded to an amino group or an ether group is not particularly limited, and examples thereof include a glycidylamino group, a diglycidylamino group, or a glycidyloxy group. A more preferable molecular structure is an epoxy group-containing compound having a glycidylamino group or a diglycidylamino group, and a glycidyloxy group, respectively, and examples thereof include a compound represented by the following general formula (iii).

[0102]

Chemical formula

[0103] In the above formula (iii), R is defined in the same manner as R in the above formula (i), and R 6 is a hydrocarbon group having 1 to 10 carbon atoms or a structure of the following formula (iv). R 6 When R is a hydrocarbon group, R may be bonded to each other to form a cyclic structure, and in that case, the N bonded to R 6 and R may be directly bonded. In formula (iii), n is an integer of 1 or more, and m is 0 or an integer of 1 or more.

[0104]

Chemical formula

[0105] As the epoxy compound which is a coupling agent having a nitrogen atom-containing group, particularly preferably a compound having one or more diglycidylamino groups and one or more glycidyloxy groups in the molecule.

[0106] Examples of the epoxy compound used as a coupling agent having a nitrogen atom-containing group include, but are not limited to, the following. For example, N,N-diglycidyl-4-glycidoxy aniline, 1-N,N-diglycidylaminomethyl-4-glycidoxy-cyclohexane, 4-(4-glycidoxyphenyl)-(N,N-diglycidyl) aniline, 4-(4-glycidoxyphenoxy)-(N,N-diglycidyl) aniline, 4-(4-glycidoxybenzyl)-(N,N-diglycidyl) aniline, 4-(N,N'-diglycidyl-2-piperazinyl)-glycidoxy benzene, 1,3-bis(N,N-diglycidylaminomethyl) cyclohexane, N,N,N',N'-tetraglycidyl-m-xylene diamine, 4,4-methylene-bis(N,N-diglycidyl aniline), 1,4-bis(N,N-diglycidylamino) cyclohexane, N,N,N',N'-tetraglycidyl-p-phenylene diamine, 4,4'-bis(diglycidylamino) benzophenone, 4-(4-glycidyl piperazinyl)-(N,N-diglycidyl) aniline, 2-[2-(N,N-diglycidylamino) ethyl]-1-glycidyl pyrrolidine, N,N-diglycidyl aniline, 4,4'-diglycidyl-dibenzyl methylamine, N,N-diglycidyl aniline, N,N-diglycidyl orthotoluidine, N,N-diglycidylaminomethyl cyclohexane, and the like. Among these, particularly preferred are N,N-diglycidyl-4-glycidoxy aniline and 1,3-bis(N,N-diglycidylaminomethyl) cyclohexane.

[0107] Examples of the alkoxysilane compound which is a coupling agent having a nitrogen atom-containing group include, but are not limited to, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropylmethyldimethoxysilane, 3-diethylaminopropyltriethoxysilane, 3-morpholinopropyltrimethoxysilane, 3-piperidinopropyltriethoxysilane, 3-hexamethyleneiminopropylmethyldiethoxysilane, 3-(4-methyl-1-piperazino)propyltriethoxysilane, 1-[3-(triethoxysilyl)-propyl]-3-methylhexahydropyrimidine, 3-(4-trimethylsilyl-1-piperazino)propyltriethoxysilane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane, 3-(3-trimethylsilyl-1-hexahydropyrimidinyl)propyltrimethoxysilane, 3-dimethylamino-2-(dimethylaminomethyl)propyltrimethoxysilane, bis(3-dimethoxymethylsilylpropyl)-N-methylamine, bis(3-trimethoxysilylpropyl)-N-methylamine, bis(3-triethoxysilylpropyl)methylamine, tris(trimethoxysilyl)amine, tris(3-trimethoxysilylpropyl)amine, N,N,N’,N’-tetra(3-trimethoxysilylpropyl)ethylenediamine, 3-isocyanatopropyltrimethoxysilane, 3-cyanopropyltrimethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-dimethoxy-8-(N,Examples thereof include (N - diethylamino)methyl - 1,6 - dioxo - 2 - silacyclooctane, etc.

[0108] As a coupling agent having a nitrogen atom - containing group and a protected amine compound capable of forming a primary or secondary amine, examples of the compound having an unsaturated bond and a protected amine in the molecule include, but are not limited to, 4,4’ - vinylidenebis[N,N - bis(trimethylsilyl)aniline], 4,4’ - vinylidenebis[N,N - bis(triethylsilyl)aniline], 4,4’ - vinylidenebis[N,N - bis(t - butyldimethylsilyl)aniline], 4,4’ - vinylidenebis[N - methyl - N - (trimethylsilyl)aniline], 4,4’ - vinylidenebis[N - ethyl - N - (trimethylsilyl)aniline], 4,4’ - vinylidenebis[N - methyl - N - (triethylsilyl)aniline], 4,4’ - vinylidenebis[N - ethyl - N - (triethylsilyl)aniline], 4,4’ - vinylidenebis[N - methyl - N - (t - butyldimethylsilyl)aniline], 4,4’ - vinylidenebis[N - ethyl - N - (t - butyldimethylsilyl)aniline], 1 - [4 - N,N - bis(trimethylsilyl)aminophenyl] - 1 - [4 - N - methyl - N - (trimethylsilyl)aminophenyl]ethylene, 1 - [4 - N,N - bis(trimethylsilyl)aminophenyl] - 1 - [4 - N,N - dimethylaminophenyl]ethylene, etc.

[0109] A coupling agent having a nitrogen atom-containing group, which is a protected amine compound capable of forming a primary or secondary amine. Examples of compounds having an alkoxysilane and a protected amine in the molecule include, but are not limited to, N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane, N,N-bis(triethylsilyl)aminopropylmethyldiethoxysilane, 3-(4-trimethylsilyl-1-piperazino)propyltriethoxysilane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane, 3-(3-trimethylsilyl-1-hexahydropyrimidinyl)propyltrimethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(triethoxysilyl)-1-propanamine, N-ethylidene-3-(triethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)-3-(triethoxysilyl)-1-propanamine, etc. Examples include N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(1,3-(Dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, 3-(benzylideneamino)propyltrimethoxysilane, 3-(benzylideneamino)propyltriethoxysilane, 3-(benzylideneamino)propyltripropylsilane, etc. may be mentioned.,

[0110] Although the alkoxysilane compound, which is a coupling agent having a nitrogen atom-containing group and is particularly preferable, is not limited to the following, for example, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-tripropoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bis(aminomethyl)cyclohexane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bis(aminomethyl)cyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexamethylenediamine, pentakis(3-trimethoxysilylpropyl)-diethylenetriamine, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]silane, 3-tris[2-(2,2-Dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-trimethoxysilylpropane, 1-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 1-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexyl-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]ether, (3-trimethoxysilylpropyl)phosphate, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)phosphate, and tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate are mentioned.,

[0111] [Coupling agent represented by formula (a)] In the method for producing a branched conjugated diene polymer of the present embodiment, it is preferable to carry out a reaction step of reacting a compound [A] represented by the following formula (a) with the active terminal of the conjugated diene polymer having a branched structure obtained through the above-described polymerization step and branching step. Compound [A] is a compound having a total of 2 or more alkoxysilyl groups containing a nitrogen atom, and the structure represented by X in formula (a) is the structure represented by the above formulas (b) to (e). By performing the reaction step using the coupling agent represented by the formula (a), a branched conjugated diene polymer having a large number of branched polymer chains and modified with a group that interacts with silica can be obtained.

[0112] [Chemical formula]

[0113] In formula (a), R 1 ~R 4 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R 5 ~R 6 each independently represents an alkylene group having 1 to 20 carbon atoms. m and n are integers from 1 to 3. In formula (a), a plurality of R 1 ~R 6 , m, and n may be the same or different. In formula (a), X is represented by any one of the following general formulas (b) to (e).

[0114]

Chemical formula

[0115] In formula (b), R 7 represents a hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group may have a partially branched structure or a cyclic structure. R 8 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. In the case of a hydrocarbon group, it may have a partially branched structure or a cyclic structure.

[0116]

Chemical formula

[0117] In formula (c), R 9 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. In the case of a hydrocarbon group, it may have a partially branched structure or a cyclic structure.

[0118]

Chemical formula

[0119] In formula (d), R 10 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. In the case of a hydrocarbon group, it may have a partially branched structure or a cyclic structure.

[0120]

Chem.

[0121] In formula (e), R 11 ~R 14 each independently represents an alkylene group having 1 to 20 carbon atoms. R 15 ~R 18 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and l and o each independently represent an integer of 1 to 3. When there are a plurality of R 15 ~R 18 are each independent.

[0122] The compound [A] used in the modification step, i.e., the reaction step, is not limited to the following, and examples include compounds represented by each of the following formulas (A-1) to (A-16). Note that the compound [A] may be used alone or in combination of two or more.

[0123] <Compound [A] used in the modification step: Formulas (A-1) to (A-16)>

[0124]

Chem.

[0125]

Chem.

[0126]

Chem.

[0127] In the above formulas (A-1) to (A-16), Et is an ethyl group and Me is a methyl group.

[0128] The reaction between the conjugated diene polymer having an active end obtained in the disproportionation step and the compound [A] represented by the formula (a) can be carried out, for example, as a solution reaction. The usage ratio of the compound [A] (the total amount when two or more are used) is preferably 0.01 mol or more, more preferably 0.05 mol or more, per 1 mol of the metal atom involved in the polymerization of the polymerization initiator, from the viewpoint of allowing the coupling reaction to proceed sufficiently. Also, regarding the upper limit value, in order to avoid excessive addition, it is preferably less than 2.0 mol, more preferably less than 1.5 mol, per 1 mol of the metal atom involved in the polymerization of the polymerization initiator.

[0129] The temperature of the coupling reaction using the compound [A] represented by the formula (a) is usually the same as that of the polymerization reaction, preferably -20°C to 150°C, more preferably 0 to 120°C. When the reaction temperature is low, the viscosity of the polymer after the coupling reaction tends to increase, and when the reaction temperature is high, the polymerization active ends are likely to be deactivated. The reaction time is preferably 1 minute to 5 hours, more preferably 2 minutes to 1 hour.

[0130] In the reaction between the conjugated diene polymer having an active end obtained in the disproportionation step and the compound [A] represented by the formula (a), other modifiers or coupling agents may be used together with the compound [A]. The other modifiers or coupling agents are not particularly limited as long as they are compounds capable of reacting with the active ends of the conjugated diene polymer obtained by the above polymerization step and disproportionation step, and known compounds as modifiers or coupling agents for conjugated diene polymers can be used. When using other modifiers or coupling agents, the usage ratio is preferably 10 mol% or less, more preferably 5 mol% or less.

[0131] <The branched conjugated diene polymer obtained through the polymerization step, disproportionation step, and reaction step> In the method for producing a branched conjugated diene polymer according to this embodiment, the branched conjugated diene polymer obtained through the above-described reaction steps, particularly the step of reacting a coupling agent, preferably contains a structure derived from a compound having a nitrogen atom-containing group represented by the following general formula (i) or any of general formulas (A) to (C).

[0132]

Chemical formula

[0133] In the above formula (i), R is a divalent or higher hydrocarbon group, or a divalent or higher organic group having at least one polar group selected from polar groups having oxygen such as ether, epoxy, and ketone, polar groups having sulfur such as thioether and thioketone, and polar groups having nitrogen such as tertiary amino group and imino group.

[0134] The divalent or higher hydrocarbon group is a saturated or unsaturated, linear, branched, or cyclic hydrocarbon group, and includes an alkylene group, an alkenylene group, a phenylene group, etc. Preferably, it is a hydrocarbon group having 1 to 20 carbon atoms. For example, methylene, ethylene, butylene, cyclohexylene, 1,3-bis(methylene)-cyclohexane, 1,3-bis(ethylene)-cyclohexane, o-, m-, p-phenylene, m-, p-xylene, bis(phenylene)-methane, etc. can be mentioned.

[0135] In the above formula (i), R 1 , R 4 are hydrocarbon groups having 1 to 10 carbon atoms, and R 1 , R 4 may be the same as or different from each other. In the above formula (i), R 2 , R 5 are hydrogen or hydrocarbon groups having 1 to 10 carbon atoms, and R 2 , R 5 may be the same as or different from each other. In the above formula (i), R 3 is a hydrocarbon group having 1 to 10 carbon atoms or has the structure of the following formula (ii). R1 , R 2 , R 3 may be a cyclic structure bonded to each other. Also, when R 3 is a hydrocarbon group, it may be a cyclic structure bonded to R. In the case of the above cyclic structure, N bonded to R 3 and R may be directly bonded. In the above formula (i), n is an integer of 1 or more, and m is 0 or an integer of 1 or more.

[0136]

Chemical formula

[0137] In the above formula (ii), R 1 , R 2 are defined in the same way as R 1 , R 2 in the above formula (i), and R 1 , R 2 may be the same as or different from each other.

[0138]

Chemical formula

[0139] (In formula (A), R 1 to R 4 each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, R 5 represents an alkylene group having 1 to 10 carbon atoms, and R 6 represents an alkylene group having 1 to 20 carbon atoms. m represents an integer of 1 or 2, n represents an integer of 2 or 3, and (m + n) represents an integer of 4 or more. When there are a plurality of R 1 to R 4 are each independent.)

[0140]

Chemical formula

[0141] (In formula (B), R 1 ~R 6 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R 7 ~R 9 each independently represents an alkylene group having 1 to 20 carbon atoms.) m, n, and l each independently represent an integer from 1 to 3, and (m + n + l) represents an integer of 4 or more. When there are a plurality of R 1 ~R 6 they are each independent.)

[0142] [Chemical formula]

[0143] (In formula (C), R 12 ~R 14 each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms, R 15 ~R 18 , and R 20 each independently represents an alkyl group having 1 to 20 carbon atoms, R 19 and R 22 each independently represents an alkylene group having 1 to 20 carbon atoms, and R 21 represents an alkyl group having 1 to 20 carbon atoms or a trialkylsilyl group.) m represents an integer from 1 to 3, and p represents 1 or 2.) When there are a plurality of each of R 12 ~R 22 , m, and p are each independent and may be the same or different.) i represents an integer from 0 to 6, j represents an integer from 0 to 6, k represents an integer from 0 to 6, and (i + j + k) is an integer from 4 to 10.) A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom, and a phosphorus atom and having no active hydrogen.)

[0144] Examples of the coupling agent having a nitrogen atom-containing group represented by the formula (A) include, but are not limited to, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacycloheptane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy,2-methyl-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-ethoxy,2-ethyl-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy,2-methyl-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, and 2-ethoxy,2-ethyl-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane.

[0145] Among these, from the viewpoints of the reactivity and interaction between the functional group of the coupling agent having a nitrogen atom-containing group and an inorganic filler such as silica, and the processability, those in which m is 2 and n is 3 are preferred. Specifically, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane and 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane are preferred.

[0146] When reacting the coupling agent having a nitrogen atom-containing group represented by the formula (A) with the polymerization active terminal, the reaction temperature, reaction time, etc. are not particularly limited, but it is preferably reacted at 0°C or higher and 120°C or lower for 30 seconds or longer.

[0147] The total molar number of the alkoxy groups bonded to the silyl group in the compound of the coupling agent having a nitrogen atom-containing group represented by the formula (A) is preferably in the range of 0.6 times or more and 3.0 times or less, more preferably in the range of 0.8 times or more and 2.5 times or less, and even more preferably in the range of 0.8 or more and 2.0 times or less, based on the added molar number of the alkali metal compound and / or alkaline earth metal compound of the polymerization initiator. From the viewpoint of obtaining a sufficiently modified branched conjugated diene polymer with a molecular weight and a branched structure, it is preferably 0.6 times or more. In addition to the preference for polymerizing the ends of the polymer to obtain a branched conjugated diene polymer component for improving processability, it is preferably 3.0 times or less from the viewpoint of the cost of the coupling agent.

[0148] The molar number of the polymerization initiator is preferably 3.0 times or more, more preferably 4.0 times or more, based on the molar number of the coupling agent having a nitrogen atom-containing group represented by the formula (A).

[0149] Examples of the coupling agent having a nitrogen atom-containing group represented by the formula (B) include, but are not limited to, tris(3-trimethoxysilylpropyl)amine, tris(3-methyldimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-methyldiethoxysilylpropyl)amine, tris(trimethoxysilylmethyl)amine, tris(2-trimethoxysilylethyl)amine, and tris(4-trimethoxysilylbutyl)amine.

[0150] Among these, from the viewpoints of the reactivity and interaction between the functional group of the coupling agent and an inorganic filler such as silica, and the processability, in the formula (B), it is preferable that n, m, and l are all 3. Preferred specific examples include tris(3-trimethoxysilylpropyl)amine and tris(3-triethoxysilylpropyl)amine.

[0151] When reacting the coupling agent having a nitrogen atom-containing group represented by the formula (B) with the active terminal of the conjugated diene polymer obtained in the branching step, the reaction temperature, reaction time, etc. are not particularly limited, but it is preferable to react at 0°C or higher and 120°C or lower for 30 seconds or more.

[0152] The total number of moles of the alkoxy group bonded to the silyl group in the compound of the coupling agent represented by the formula (B) is preferably in the range of 0.6 times or more and 3.0 times or less, more preferably in the range of 0.8 times or more and 2.5 times or less, and even more preferably in the range of 0.8 times or more and 2.0 times or less, of the number of moles of lithium constituting the polymerization initiator described above. From the viewpoint of obtaining a sufficient modification rate, molecular weight, and branched structure in the branched conjugated diene polymer obtained by the production method of the present embodiment, it is preferably 0.6 times or more. In addition to the preference for coupling the polymer terminals to obtain a branched conjugated diene polymer component for improving processability, from the viewpoint of the coupling agent cost, it is preferably 3.0 times or less.

[0153] The number of moles of the polymerization initiator is preferably 4.0 times or more, more preferably 5.0 times or more, the number of moles of the coupling agent having a nitrogen atom-containing group represented by the formula (B).

[0154] In the formula (C), A is preferably represented by any one of the following general formulas (II) to (V).

[0155]

Chemical formula

[0156] (In the formula (II), B 1 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. When there are a plurality of B1, they are each independent.)

[0157]

Chemical formula

[0158] (In formula (III), B 2 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, B 3 represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer from 1 to 10. When there are a plurality of each, B 2 and B 3 are each independent.)

[0159]

Chemical formula

[0160] (In formula (IV), B 4 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer from 1 to 10. When there are a plurality of B 4 are each independent.)

[0161]

Chemical formula

[0162] (In formula (V), B 5 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer from 1 to 10. When there are a plurality of B 5 are each independent.)

[0163] In the formula (C), the coupling agent having a nitrogen atom-containing group when A is represented by the formula (II) is not limited to the following, but for example, tris(3-trimethoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)amine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tris(3-ethoxysilylpropyl)amine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]amine, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)amine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis[3-(2,2-Dimethoxy-1-aza-2-silacyclopentyl)-(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentyl)propyl]-1,3-propanediamine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentyl)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentyl)propyl]-1,3-propanediamine, tetrakis(3-triethoxysilylpropyl)-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentyl)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-bis[3-(2,2-diethoxy-1-aza-2-silacyclopentyl)propyl]-1,3-propanediamine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentyl)propyl]-(3-triethoxysilylpropyl)-1,3-propanediamine, tetrakis[3-(2,2-diethoxy-1-aza-2-silacyclopentyl)propyl]-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentyl)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentyl)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentyl)propyl]-1,3-propanediamine, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentyl)propyl]-(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentyl)propyl]-1,3-propanediamine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentyl)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentyl)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-[3-(2,2-Dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bis(aminomethyl)cyclohexane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bis(aminomethyl)cyclohexane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-bis(aminomethyl)cyclohexane, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bis(aminomethyl)cyclohexane, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bis(aminomethyl)cyclohexane, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bis(aminomethyl)cyclohexane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bis(aminomethyl)cyclohexane, tetrakis(3-triethoxysilylpropyl)-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bis(aminomethyl)cyclohexane, bis(3-triethoxysilylpropyl)-bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bis(aminomethyl)cyclohexane, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-1,3-propanediamine, tetrakis[3-(2,2-Diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexamethylenediamine, and pentakis(3-trimethoxysilylpropyl)-diethylenetriamine may be mentioned.,

[0164] In the formula (C), the coupling agent having a nitrogen atom-containing group when A is represented by the formula (III) is not limited to the following, and examples thereof include tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, bis(2-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3-propanediamine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, tris(3-triethoxysilylpropyl)-methyl-1,3-propanediamine, bis(2-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3-propanediamine, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-methyl-1,3-propanediamine, N1,N1'-(propane-1,3-diyl)bis(N1-methyl-N3,N3-bis(3-(trimethoxysilyl)propyl)-1,3-propanediamine), and N1-(3-(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N1-methyl-N3-(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N3-(3-(trimethoxysilyl)propyl)-1,3-propanediamine.

[0165] In the formula (C), the coupling agent having a nitrogen atom-containing group when A is represented by the formula (IV) is not limited to the following, but for example, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]silane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, (3-trimethoxysilyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-bis(3-trimethoxysilylpropyl)silane, and bis(3-trimethoxysilylpropyl)-bis[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]silane may be mentioned.

[0166] In the formula (C), examples of the coupling agent having a nitrogen atom-containing group when A is represented by the formula (V) include, but are not limited to, 3-tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-(2,2-dimethoxy-1-aza-2-silacyclopentane)propane, and 3-tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-trimethoxysilylpropane.

[0167] In the formula (C), A is preferably represented by the formula (II) or the formula (III), and k represents 0.

[0168] Such coupling agents having a nitrogen atom-containing group tend to be easily available, and also tend to have more excellent abrasion resistance and low hysteresis loss performance when the branched conjugated diene polymer obtained by the production method of the present embodiment is used as a vulcanizate. Examples of such coupling agents having a nitrogen atom-containing group include, but are not limited to, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, and bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-tris-methoxysilylpropyl)-methyl-1,3-propanediamine.

[0169] In the formula (C), A is more preferably represented by the formula (II) or the formula (III), k represents 0, and in the formula (II) or the formula (III), a represents an integer of 2 to 10. Thereby, the abrasion resistance and low hysteresis loss performance when vulcanized tend to be more excellent. Examples of the coupling agent having such a nitrogen atom-containing group include, but are not limited to, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, and N 1 -(3-(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N 1 -methyl-N 3 -(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N 3 -(3-(trimethoxysilyl)propyl)-1,3-propanediamine.

[0170] The addition amount of the compound represented by the formula (C) as the coupling agent having a nitrogen atom-containing group can be adjusted so that the molar ratio of the conjugated diene polymer to the coupling agent reacts at a desired stoichiometric ratio, and thereby a desired star-branched structure tends to be achieved.

[0171] The molar number of the polymerization initiator is preferably 5.0 times mol or more, more preferably 6.0 times mol or more, relative to the molar number of the coupling agent having a nitrogen atom-containing group represented by the formula (C).

[0172] In this case, in the formula (C), the functional group number ((m - 1)×i + p×j + k) of the coupling agent is preferably an integer of 5 to 10, more preferably an integer of 6 to 10.

[0173] The modified conjugated diene polymer obtained by the production method of the present embodiment has the proportion of the polymer having a nitrogen atom-containing group in the polymer represented by the modification rate. The modification rate is preferably 60% by mass or more, more preferably 65% by mass or more, still more preferably 70% by mass or more, even more preferably 75% by mass or more, still more preferably 80% by mass or more, and particularly preferably 82% by mass or more. By setting the modification rate to 60% by mass or more, the processability during vulcanization is excellent, and the wear resistance and low hysteresis loss performance of the vulcanized product tend to be excellent.

[0174] <When the compound represented by the above formula (a) is used as the coupling agent, the branched conjugated diene polymer obtained through the above reaction steps> As a preferred form, the branched conjugated diene polymer of the present embodiment is a reaction product of a conjugated diene polymer having an active terminal with a branched structure and a compound represented by the following formula (a).

[0175]

Chemical formula

[0176] In formula (a), R 1 ~R 4 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R 5 ~R 6 each independently represents an alkylene group having 1 to 20 carbon atoms. m and n are integers from 1 to 3. In formula (a), a plurality of R 1 ~R 6 , m, and n may be the same or different. In formula (a), X is represented by any one of the following general formulas (b) to (e).

[0177]

Chemical formula

[0178] In formula (b), R 7 represents a hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group may have a partially branched structure or a cyclic structure. R 8 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. In the case of the hydrocarbon group, it may have a partially branched structure or a cyclic structure.

[0179]

Chemical formula

[0180] In formula (c), R 9 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. In the case of the hydrocarbon group, it may have a partially branched structure or a cyclic structure.

[0181]

Chemical formula

[0182] In formula (d), R 10 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. In the case of the hydrocarbon group, it may have a partially branched structure or a cyclic structure.

[0183]

Chemical formula

[0184] In formula (e), R 11 ~R 14 each independently represents an alkylene group having 1 to 20 carbon atoms. R 15 ~R 18 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. l and o each independently represent an integer of 1 to 3. When there are a plurality of R 15 ~R 18 are each independent.

[0185] The modified conjugated diene polymer of this embodiment has an OR of the compound represented by the above formula (a) 1 and OR 3 It is preferable that at least one of them has a branched structure.

[0186] From the viewpoints of fuel efficiency performance, processability, and wear resistance balance, the branched conjugated diene polymer of this embodiment is preferably a conjugated diene polymer having an active terminal having a branched structure obtained through a branching step and a compound represented by the above formula (a). The reaction product of and is a preferable form. Generally, a modified conjugated diene polymer having a branched structure has branch points derived from a coupling agent or a modifier. As the number of branches increases, the reactivity with silica decreases when a rubber composition is formed. In addition, a polymer with a low degree of branching tends to have an increase in the viscosity of the formulation and a deterioration in processability as the content of the coupling agent or modifier and the molecular weight increase. Therefore, it is difficult to improve the balance among fuel efficiency performance, processability, and wear resistance. On the other hand, a preferable form of the branched conjugated diene polymer of this embodiment is that at least one of the ORs of the compound represented by the above formula (a) 1 and OR 3 is a conjugated diene polymer having a branched structure, which is a preferable form. Therefore, due to the relaxation of steric hindrance around the modifier, the number of branches and the molecular weight can be improved without impairing the reactivity between the branched conjugated diene polymer and silica. Therefore, it is preferable that the modified conjugated diene polymer in which at least one of the ORs of the compound represented by the above formula (a) 1 and OR 3 has a branched structure is an asymmetric structure. That is, centering around the coupling agent, it is preferable that a skeleton having a main chain branched structure is formed on one side and a skeleton without a main chain branch introduced is formed on the opposite side. Furthermore, it is more preferable that the branch point of the conjugated diene polymer obtained through the branching step and the branch point formed by the modifier are separated by a molecular chain with a molecular weight of 10,000 or more.

[0187] <Polymerization terminator step> In the method for producing a branched conjugated diene polymer of the present embodiment, a reaction step of reacting the coupling agent or polymerization terminator described above with the active terminal of the conjugated diene polymer obtained through the polymerization step and the branching step described above can be carried out. As the polymerization termination step, for example, a polymerization termination step carried out using a bifunctional reactive compound on the active terminal of the conjugated diene polymer, or a polymerization termination step carried out using a polymerization terminator having a nitrogen atom-containing group (hereinafter, may be collectively referred to as "polymerization terminator") is preferable.

[0188] In the polymerization termination step, for example, the polymerization termination reaction is carried out on the active terminal of the polymer obtained in the above-described branching step using a bifunctional reactive compound or a polymerization terminator having a nitrogen atom-containing group to obtain the target branched conjugated diene polymer.

[0189] [Bifunctional reactive compound] In the method for producing a branched conjugated diene polymer of the present embodiment, the bifunctional reactive compound used in the polymerization termination step may have any structure, but is preferably a bifunctional reactive compound having a silicon atom.

[0190] [Polymerization terminator having a nitrogen atom-containing group] In the method for producing a branched conjugated diene polymer of the present embodiment, the polymerization terminator having a nitrogen atom-containing group used in the polymerization termination step may have any structure, but preferably has a functional group that reacts with the conjugated diene polymer.

[0191] As the polymerization terminator having a nitrogen atom-containing group, from the viewpoint of improving fuel efficiency performance, an alkoxy compound having a nitrogen atom-containing group is preferable. Examples of the polymerization terminator having a nitrogen atom-containing group include 3-(N,N-dimethylaminopropyl)dimethoxymethylsilane, 3-(N,N-diethylaminopropyl)dimethoxymethylsilane, 3-(N,N-dipropylaminopropyl)dimethoxymethylsilane, 3-(N,N-dimethylaminopropyl)diethoxymethylsilane, 3-(N,N-diethylaminopropyl)diethoxymethylsilane, 3-(N,N-dipropylaminopropyl)diethoxymethylsilane, 3-(N,N-dimethylaminopropyl)dimethoxyethylsilane, 3-(N,N-diethylaminopropyl)dimethoxyethylsilane, 3-(N,N-dipropylaminopropyl)dimethoxyethylsilane, 3-(N,N-dimethylaminopropyl)diethoxyethylsilane, 3-(N,N-diethylaminopropyl)diethoxyethylsilane, 3-(N,N-dipropylaminopropyl)diethoxyethylsilane and the like.

[0192] By the production method of the present embodiment, the branched structure of the branched conjugated diene polymer obtained through the above-described polymerization step, branching step, and reaction step is more preferably 6 branches or more and 36 branches or less, preferably 8 branches or more and 36 branches or less, more preferably 8 branches or more and 24 branches or less, 10 branches or more and 24 branches or less, 10 branches or more and 22 branches or less, and still more preferably 12 branches or more and 20 branches or less. In the branched conjugated diene polymer obtained by the production method of the present embodiment, the total number of branch points is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and still more preferably 5 or more. When the branched structure and the total number of branch points are within the above-described ranges, the polymer tends to be excellent in processability, fuel efficiency, and abrasion resistance. In order to construct a branched conjugated diene polymer having a branched structure of 8 branches or more and 36 branches or less and, in the case of a modified polymer, having a total number of branch points of 2 or more and 15 or less, the molar ratio of the branching agent needs to be 1 / 2 or less and 1 / 100 or more of the polymerization initiator, and the functional group number of the coupling agent needs to be 3-functional or more. In the case of a polymer that does not require modification, the number of branch points may be 1 or more. In order to construct a structure in which the branching structure has 8 or more branches and 36 or fewer branches, and the total number of branch points is 3 or more and 12 or fewer, it is preferable to use a branching agent with a molar ratio of 1 / 3 or less and 1 / 50 or more of the polymerization initiator, and a coupling agent with 4 or more functional groups. In order to construct a structure in which the branching structure has 10 or more branches and 24 or fewer branches, and the total number of branch points is 4 or more and 10 or fewer, it is preferable to use a branching agent with a molar ratio of 1 / 6 or less and 1 / 25 or more of the polymerization initiator, and a coupling agent with 5 or more functional groups. In order to construct a structure in which the branching structure has 12 or more branches and 20 or fewer branches, and the total number of branch points is 5 or more and 9 or fewer, it is preferable to use a branching agent with a molar ratio of 1 / 8 or less and 1 / 12 or more of the polymerization initiator, and a coupling agent with 6 or more functional groups.

[0193] (Condensation reaction step) In the method for producing a branched conjugated diene polymer of the present embodiment, after the coupling step described above, or before the coupling step, a condensation reaction step of performing a condensation reaction in the presence of a condensation accelerator may be performed.

[0194] (Hydrogenation step) In the method for producing a branched conjugated diene polymer of the present embodiment, a hydrogenation step of hydrogenating the conjugated diene portion may be performed. The method for hydrogenating the conjugated diene portion of the conjugated diene polymer is not particularly limited, and a known method can be used. As a suitable hydrogenation method, a method of hydrogenating by blowing gaseous hydrogen into a polymer solution in the presence of a catalyst can be mentioned. The catalyst is not particularly limited, and examples thereof include heterogeneous catalysts such as catalysts in which a noble metal is supported on a porous inorganic substance; homogeneous catalysts such as catalysts obtained by solubilizing salts of nickel, cobalt, etc. and reacting them with organoaluminum, etc., and catalysts using metallocenes such as titanocene. Among these, from the viewpoint of being able to select mild hydrogenation conditions, a titanocene catalyst is preferable. Also, the hydrogenation of aromatic groups can be carried out by using a supported noble metal catalyst.

[0195] Examples of the hydrogenation catalyst include, but are not limited to, (1) supported heterogeneous hydrogenation catalysts in which metals such as Ni, Pt, Pd, and Ru are supported on carbon, silica, alumina, diatomaceous earth, etc., (2) so-called Ziegler-type hydrogenation catalysts using transition metal salts such as organic acid salts or acetylacetone salts of Ni, Co, Fe, Cr, etc. and reducing agents such as organic aluminum, and (3) so-called organometallic complexes such as organometallic compounds of Ti, Ru, Rh, Zr, etc. Further, examples of the hydrogenation catalyst include, but are not particularly limited to, known hydrogenation catalysts described in Japanese Patent Publication No. Sho 42-8704, Japanese Patent Publication No. Sho 43-6636, Japanese Patent Publication No. Sho 63-4841, Japanese Patent Publication No. Hei 1-37970, Japanese Patent Publication No. Hei 1-53851, Japanese Patent Publication No. Hei 2-9041, and Japanese Patent Application Laid-Open No. Hei 8-109219. A preferred hydrogenation catalyst includes a reaction mixture of a titanocene compound and a reducing organometallic compound.

[0196] (Step of adding deactivator and neutralizer) In the method for producing a branched conjugated diene polymer of the present embodiment, after the coupling step described above, a deactivator, a neutralizer, etc. may be added to the polymer solution as necessary. Examples of the deactivator include, but are not limited to, water; alcohols such as methanol, ethanol, and isopropanol. Examples of the neutralizer include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a mixture of carboxylic acids having 9 to 11 carbon atoms and centered around 10 carbon atoms and having many branches); aqueous solutions of inorganic acids, and carbon dioxide gas.

[0197] (Step of adding rubber stabilizer) In the method for producing a branched conjugated diene polymer of the present embodiment, it is preferable to add a rubber stabilizer from the viewpoints of preventing gel formation after polymerization and improving stability during processing. The stabilizers for rubber are not limited to the following, and known ones can be used. For example, antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (hereinafter also referred to as "BHT"), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenyl) propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol are preferred.

[0198] (Step of adding softener for rubber) In the method for producing a branched conjugated diene polymer of the present embodiment, from the viewpoint of further improving the productivity of the branched conjugated diene polymer and the processability when a resin composition is prepared by blending a filler or the like, a softener for rubber can be added as necessary. The softener for rubber is not particularly limited, and examples thereof include extender oil, liquid rubber, resin, and the like. The method for adding a softener for rubber to a branched conjugated diene polymer is not limited to the following, but a method in which a softener for rubber is added to a branched conjugated diene polymer solution, mixed to obtain a polymer solution containing a softener for rubber, and then the solvent is removed is preferred.

[0199] Preferred extender oils include, for example, aromatic oil, naphthenic oil, paraffin oil, and the like. Among these, from the viewpoints of environmental safety, oil bleed prevention, and wet grip properties, an aromatic alternative oil having a polycyclic aromatic (PCA) component of 3% by mass or less according to the IP346 method is preferred. Examples of the aromatic alternative oil include TDAE (Treated Distillate Aromatic Extracts), MES (Mild Extraction Solvate), and RAE (Residual Aromatic Extracts) shown in Kautschuk Gummi Kunststoffe 52(12)799(1999). Preferred liquid rubbers include, but are not limited to, for example, liquid polybutadiene, liquid styrene-butadiene rubber, and the like. As effects when adding liquid rubber, in addition to being able to improve the processability when making a resin composition by blending a branched conjugated diene polymer and a filler or the like, the glass transition temperature of the resin composition can be shifted to the low temperature side, so that the abrasion resistance, low hysteresis loss property, and low temperature characteristics of the vulcanizate tend to be improved. Resins as softeners for rubber are not limited to the following, but for example, aromatic petroleum resins, coumarone-indene resins, terpene resins, rosin derivatives (including tung oil resins), tall oil, derivatives of tall oil, rosin ester resins, natural and synthetic terpene resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, mixed aliphatic-aromatic hydrocarbon resins, coumarin-indene resins, phenolic resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, oligomers of monoolefins, oligomers of diolefins, aromatic hydrocarbon resins, aromatic petroleum resins, hydrogenated aromatic hydrocarbon resins, cycloaliphatic hydrocarbon resins, hydrogenated hydrocarbon resins, hydrocarbon resins, hydrogenated tung oil resins, hydrogenated oil resins, esters of hydrogenated oil resins and monofunctional or polyfunctional alcohols, etc. may be mentioned. These resins may be used alone or in combination of two or more. When hydrogenating, all unsaturated groups may be hydrogenated or some may be left. As effects when adding a resin as a softener for rubber, in addition to being able to improve the processability when making a resin composition by blending a branched conjugated diene polymer and a filler or the like, the breaking strength of the vulcanizate tends to be improved, and also the glass transition temperature of the resin composition can be shifted to the high temperature side, so that the wet skid resistance tends to be improved.

[0200] The addition amount of stretching oil, liquid rubber, resin or the like as a softener for rubber is not particularly limited, but is preferably 1 part by mass or more and 60 parts by mass or less, more preferably 5 parts by mass or more and 50 parts by mass or less, still more preferably 10 parts by mass or more and 37.5 parts by mass or less with respect to 100 parts by mass of the branched conjugated diene polymer obtained by the production method of the present embodiment. When a softening agent for rubber is added within the above range, the processability of a resin composition obtained by blending the branched conjugated diene polymer obtained by the production method of the present embodiment with a filler or the like becomes good, and the breaking strength and abrasion resistance when vulcanized tend to be good.

[0201] (Desolventization step) In the method for producing a branched conjugated diene polymer of the present embodiment, as a method for obtaining the obtained branched conjugated diene polymer from the polymer solution, a known method can be used. Although the method is not particularly limited, for example, a method in which after separating the solvent by steam stripping or the like, the polymer is filtered off, and then it is dehydrated and dried to obtain the polymer, a method in which it is concentrated in a flashing tank and then devolatilized by a vent extruder or the like, and a method in which it is directly devolatilized by a drum dryer or the like can be mentioned.

[0202] [[Rubber composition, and method for producing rubber composition]] The rubber composition of the present embodiment contains a rubber component containing 10% by mass or more of the branched conjugated diene polymer produced by the production method of the present embodiment described above, and a filler of 5.0 to 150 parts by mass with respect to 100 parts by mass of the rubber component. The method for producing the rubber composition of the present embodiment includes a step of obtaining a branched conjugated diene polymer by the production method described above, a step of obtaining a rubber component containing 10% by mass or more of the branched conjugated diene polymer, and a step of containing a filler in an amount of 5.0 to 150 parts by mass with respect to 100 parts by mass of the rubber component. Further, by containing 10% by mass of the branched conjugated diene polymer obtained by the production method of the present embodiment in the rubber component, it is preferable from the viewpoints of fuel efficiency improvement, processability, and abrasion resistance improvement.

[0203] The filler preferably includes a silica-based inorganic filler. The rubber composition tends to be more excellent in processability when vulcanized by dispersing a silica-based inorganic filler as a filler, and is more excellent in the balance of abrasion resistance, breaking strength, and low hysteresis loss property and wet skid resistance when vulcanized. When the rubber composition is used for vulcanized rubber applications such as tires and anti-vibration rubbers for automobiles, or shoes, it is also preferable to contain a silica-based inorganic filler.

[0204] The rubber composition of the present embodiment is obtained by mixing a rubber component containing 10% by mass or more of the branched conjugated diene polymer obtained by the above-described production method with the filler. The rubber component may contain a rubber-like polymer other than the above-described branched conjugated diene polymer (hereinafter simply referred to as "rubber-like polymer"). Examples of such rubber-like polymers include, but are not limited to, conjugated diene polymers or hydrogenated products thereof, random copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, block copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, and other non-diene polymers and natural rubber.

[0205] Examples of rubber-like polymers include, but are not limited to, butadiene rubber or hydrogenated products thereof, isoprene rubber or hydrogenated products thereof, styrene-butadiene rubber or hydrogenated products thereof, styrene-butadiene block copolymers or hydrogenated products thereof, styrene-isoprene block copolymers or hydrogenated products thereof, and other styrene-based elastomers, acrylonitrile-butadiene rubber or hydrogenated products thereof.

[0206] Examples of non-diene polymers include, but are not limited to, olefin-based elastomers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, and ethylene-octene rubber, butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylic acid ester-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber.

[0207] Examples of natural rubbers include, but are not limited to, RSS3 to 5, SMR, and epoxidized natural rubber, such as smoked sheets.

[0208] Each of the above-described rubbery polymers may be a modified rubber having a polar functional group such as a hydroxyl group or an amino group. When used for tires, butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber are preferably used.

[0209] From the viewpoint of the balance between various performances and processing characteristics of the resin composition, the weight average molecular weight of the rubbery polymer is preferably 2,000 or more and 2,000,000 or less, and more preferably 5,000 or more and 1,500,000 or less. In addition, a low molecular weight rubbery polymer, so-called liquid rubber, can also be used. These rubbery polymers may be used alone or in combination of two or more.

[0210] When the rubber composition using the branched conjugated diene polymer obtained by the production method of the present embodiment is a rubber composition containing the above-described rubbery polymer, the content ratio (mass ratio) of the above-described branched conjugated diene polymer to the rubbery polymer is preferably 10 / 90 or more and 100 / 0 or less, more preferably 20 / 80 or more and 90 / 10 or less, and even more preferably 50 / 50 or more and 80 / 20 or less, as (the above-described branched conjugated diene polymer / rubbery polymer). Therefore, the rubber component preferably contains 10% by mass or more and 100% by mass or less, more preferably 20% by mass or more and 90% by mass or less, and even more preferably 50% by mass or more and 80% by mass or less of the above-described branched conjugated diene polymer with respect to the total amount (100% by mass) of the rubber component.

[0211] When the content ratio of (branched conjugated diene polymer / rubbery polymer) is within the above range, the vulcanizate tends to be excellent in abrasion resistance and breaking strength, and also has a good balance between low hysteresis loss property and wet skid resistance.

[0212] Examples of the filler contained in the rubber composition include, but are not limited to, for example, in addition to the silica-based inorganic filler, carbon black, metal oxides, and metal hydroxides. Among these, the silica-based inorganic filler is preferred. The filler may be used alone or in combination of two or more. The content of the filler in the rubber composition is 5.0 parts by mass or more and 150 parts by mass with respect to 100 parts by mass of the rubber component containing the above-mentioned branched conjugated diene polymer, preferably 20 parts by mass or more and 100 parts by mass or less, and more preferably 30 parts by mass or more and 90 parts by mass or less. In the rubber composition, the content of the filler is 5.0 parts by mass or more with respect to 100 parts by mass of the rubber component from the viewpoint of expressing the addition effect of the filler, and 150 parts by mass or less with respect to 100 parts by mass of the rubber component from the viewpoint of sufficiently dispersing the filler and making the processability and mechanical strength of the rubber composition practically sufficient.

[0213] The silica-based inorganic filler is not particularly limited, and known ones can be used. However, solid particles containing SiO 2 or Si 3 Al as a constituent unit are preferred, and solid particles containing SiO 2 or Si 3 Al as the main component of the constituent unit are more preferred. Here, the main component refers to a component contained in the silica-based inorganic filler in an amount of 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more.

[0214] Examples of the silica-based inorganic filler include, but are not limited to, for example, silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, inorganic fibrous substances such as glass fiber, etc. Further, a hydrophobized silica-based inorganic filler and a mixture of a silica-based inorganic filler and an inorganic filler other than silica-based are also included. Among these, from the viewpoints of strength and abrasion resistance, etc., silica and glass fiber are preferred, and silica is more preferred. Examples of silica include dry silica, wet silica, and synthetic silicate silica. Among these silicas, wet silica is preferred from the viewpoint of excellent balance between the improvement effect of fracture strength and wet skid resistance.

[0215] From the viewpoint of obtaining practically good abrasion resistance and fracture strength in the rubber composition, the nitrogen adsorption specific surface area determined by the BET adsorption method of the silica-based inorganic filler is 100 m 2 / g or more and 300 m 2 / g or less, preferably 170 m 2 / g or more and 250 m 2 / g or less. Optionally, a silica-based inorganic filler with a relatively small specific surface area (for example, with a specific surface area of less than 200 m 2 / g) and a silica-based inorganic filler with a relatively large specific surface area (for example, 200 m 2 / g or more) can be combined and used. In particular, when using a silica-based inorganic filler with a relatively large specific surface area (for example, 200 m 2 / g or more), the rubber composition containing the above-mentioned branched conjugated diene polymer can improve the dispersibility of silica, and is particularly effective in improving abrasion resistance, and tends to be able to highly balance good fracture strength and low hysteresis loss property.

[0216] The content of the silica-based inorganic filler in the rubber composition is preferably 5.0 parts by mass or more and 150 parts by mass or less, more preferably 20 parts by mass or more and 100 parts by mass or less, based on 100 parts by mass of the rubber component containing the branched conjugated diene polymer obtained by the production method of the present embodiment. In the rubber composition, from the viewpoint of the additive effect of the silica-based inorganic filler being manifested, the content of the silica-based inorganic filler is preferably 5.0 parts by mass or more based on 100 parts by mass of the rubber component, and from the viewpoint of sufficiently dispersing the silica-based inorganic filler and making the processability and mechanical strength of the rubber composition practically sufficient, it is preferably 150 parts by mass or less based on 100 parts by mass of the rubber component.

[0217] Examples of carbon black include, but are not limited to, carbon black of each class such as SRF, FEF, HAF, ISAF, and SAF. Among these, carbon black having a nitrogen adsorption specific surface area of 50 m 2 / g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100 g or less is preferable.

[0218] In the rubber composition, the content of carbon black is preferably 0.5 part by mass or more and 100 parts by mass or less, more preferably 3.0 parts by mass or more and 100 parts by mass or less, and still more preferably 5.0 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the rubber component containing the branched conjugated diene polymer obtained by the production method of the present embodiment. In the rubber composition, the content of carbon black is preferably 0.5 part by mass or more with respect to 100 parts by mass of the rubber component from the viewpoint of exhibiting performances required for applications such as tires, such as dry grip performance and conductivity, and is preferably 100 parts by mass or less with respect to 100 parts by mass of the rubber component from the viewpoint of dispersibility.

[0219] The metal oxide refers to solid particles having a chemical formula MxOy (M represents a metal atom, and x and y each independently represent an integer of 1 to 6) as a main component of a structural unit.

[0220] Examples of the metal oxide include, but are not limited to, alumina, titanium oxide, magnesium oxide, and zinc oxide.

[0221] Examples of the metal hydroxide include, but are not limited to, aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0222] In the method for producing the rubber composition of the present embodiment, a silane coupling agent may be contained. The silane coupling agent has a function of strengthening the interaction between the rubber component and the inorganic filler, and has an affinity or bonding group for each of the rubber component and the silica-based inorganic filler. A compound having a sulfur-bonded portion and an alkoxysilyl group or a silanol group portion in one molecule is preferred. Such compounds are not particularly limited, and examples thereof include bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide.

[0223] In the rubber composition, the content of the silane coupling agent is preferably 0.1 part by mass or more and 30 parts by mass or less, more preferably 0.5 part by mass or more and 20 parts by mass or less, and still more preferably 1.0 part by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the above-described inorganic filler. When the content of the silane coupling agent is within the above range, the above-described addition effect by the silane coupling agent tends to be more remarkable.

[0224] The rubber composition may contain a softening agent for rubber from the viewpoint of improving its processability. The addition amount of the softening agent for rubber is represented by the total amount of the softening agent for rubber contained in the branched conjugated diene-based polymer and other rubber-like polymers obtained in advance and the softening agent for rubber added when forming the rubber composition, with respect to 100 parts by mass of the rubber component containing the branched conjugated diene-based polymer obtained by the production method of the present embodiment described above. As the softening agent for rubber, mineral oil or a liquid or low molecular weight synthetic softening agent is suitable. The process oil or extender oil, which is a softening agent for mineral oil-based rubbers and is used to soften rubber, increase its compatibility, and improve its processability, is a mixture of aromatic rings, naphthene rings, and paraffin chains. Those in which the paraffin chains account for 50% or more of the total carbon are called paraffin-based, those in which the naphthene ring carbon accounts for 30% or more and 45% or less of the total carbon are called naphthene-based, and those in which the aromatic carbon accounts for more than 30% of the total carbon are called aromatic-based. When the conjugated diene polymer of the present embodiment is a copolymer of a conjugated diene compound and a vinyl aromatic compound, as the rubber softening agent to be used, those having an appropriate aromatic content are preferable because they tend to have good compatibility with the copolymer. In the rubber composition, the content of the rubber softening agent is preferably 0 parts by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more and 90 parts by mass or less, and even more preferably 30 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of the rubber component. When the content of the rubber softening agent is 100 parts by mass or less with respect to 100 parts by mass of the rubber component, bleeding out is suppressed, and stickiness on the surface of the rubber composition tends to be suppressed.

[0225] The method of mixing the branched conjugated diene polymer obtained by the production method of the present embodiment with other rubber-like polymers, silica-based inorganic fillers, carbon black and other fillers, silane coupling agents, additives such as rubber softening agents, etc. is not limited to the following, but for example, melt kneading methods using general mixers such as open rolls, Banbury mixers, kneaders, single-screw extruders, twin-screw extruders, multi-screw extruders, etc., and methods of heating and removing the solvent after dissolving and mixing each component can be mentioned. Among these, the melt kneading methods using rolls, Banbury mixers, kneaders, and extruders are preferable from the viewpoints of productivity and good kneading property. Also, either a method of kneading the rubber component, other fillers, silane coupling agents, and additives at once or a method of mixing them in multiple times is applicable.

[0226] The rubber composition may be a vulcanized composition vulcanized with a vulcanizing agent. The vulcanizing agent is not limited to the following, and examples include radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds. Sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, high molecular polysulfur compounds, and the like. In the rubber composition, the content of the vulcanizing agent is preferably 0.01 part by mass or more and 20 parts by mass or less, more preferably 0.1 part by mass or more and 15 parts by mass or less, based on 100 parts by mass of the rubber component. As the vulcanization method, a conventionally known method can be applied, and the vulcanization temperature is preferably 120°C or more and 200°C or less, more preferably 140°C or more and 180°C or less.

[0227] When vulcanizing, a vulcanization accelerator may be used as necessary. As the vulcanization accelerator, conventionally known materials can be used and are not limited to the following. Examples include sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators. Further, as the vulcanization aid, examples include, but are not limited to, zinc white and stearic acid. The content of the vulcanization accelerator is preferably 0.01 part by mass or more and 20 parts by mass or less, more preferably 0.1 part by mass or more and 15 parts by mass or less, based on 100 parts by mass of the rubber component.

[0228] In the rubber composition, various additives such as other softening agents and fillers, heat-resistant stabilizers, antistatic agents, weather-resistant stabilizers, antioxidants, colorants, and lubricants other than those described above may be used within a range that does not impair the object of the present embodiment. As the other softening agent, a known softening agent can be used. Specific examples of the other fillers are not particularly limited, and include, for example, calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. As the above heat-resistant stabilizer, antistatic agent, weather-resistant stabilizer, antioxidant, colorant, and lubricant, known materials can be used respectively.

[0229] Tire and Method for Producing Tire The tire of the present embodiment contains the rubber composition of the present embodiment described above. The method for producing a tire of the present embodiment includes a step of obtaining a branched conjugated diene polymer by the production method of the present embodiment, a step of obtaining a rubber composition containing the branched conjugated diene polymer, and a step of molding the rubber composition. A rubber composition containing a branched conjugated diene polymer obtained by the production method of the present embodiment described above is suitably used as a rubber composition for tires.

[0230] Examples of the rubber composition for tires include, but are not limited to, various tires such as fuel-efficient tires, all-season tires, high-performance tires, and studless tires: it can be used for each part of the tire such as the tread, carcass, sidewall, and bead part. In particular, since the rubber composition for tires is excellent in the balance between wear resistance, breaking strength, and low hysteresis loss property and wet skid resistance when vulcanized, it is suitably used for the treads of fuel-efficient tires and high-performance tires.

Examples

[0231] Hereinafter, specific examples and comparative examples will be given to explain the present embodiment in more detail, but the present embodiment is not limited to the following examples and comparative examples. First Example Hereinafter, various physical properties in the examples and comparative examples of [First Example] were measured by the methods shown below. Hereinafter, a conjugated diene polymer coupled with a nitrogen atom-containing modifier will be referred to as a "coupled conjugated diene polymer". In addition, an unmodified conjugated diene polymer will be referred to as an "unmodified conjugated diene polymer". Furthermore, a conjugated diene polymer having a branched structure will be referred to as a "branched conjugated diene polymer".

[0232] (Physical Property 1) Polymer Mooney Viscosity Using an unmodified conjugated diene polymer or a conjugated diene polymer coupled with a nitrogen atom-containing modifier (hereinafter also referred to as "coupled conjugated diene polymer") as a sample, a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho) was used to measure the Mooney viscosity in accordance with ISO 289 using an L-shaped rotor. The measurement temperature was set to 110 °C when using an unmodified conjugated diene polymer as a sample, and 100 °C when using a coupled conjugated diene polymer as a sample. First, after preheating the sample at the test temperature for 1 minute, the rotor was rotated at 2 rpm, and the torque after 4 minutes was measured to obtain the Mooney viscosity (ML (1+4) ).

[0233] (Physical property 2) Mooney relaxation rate Using a coupled conjugated diene polymer as a sample, after measuring the Mooney viscosity using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho) in accordance with ISO 289 using an L-shaped rotor, the rotation of the rotor was immediately stopped, and the torque every 0.1 second from 1.6 seconds to 5 seconds after the stop was recorded in Mooney units. The slope of the straight line when the torque and time (seconds) were plotted on a double logarithmic scale was obtained, and the absolute value thereof was defined as the Mooney relaxation rate (MSR).

[0234] (Physical property 3) Branching degree (Bn) The branching degree (Bn) of the coupled conjugated diene polymer was measured as follows by GPC-light scattering method measurement with a viscosity detector. Using a coupled conjugated diene polymer as a sample, a gel permeation chromatography (GPC) measuring device (trade name "GPCmax VE-2001" manufactured by Malvern) with three columns filled with a polystyrene-based gel was used, and measurements were performed using three detectors connected in the order of a light scattering detector, an RI detector, and a viscosity detector (trade name "TDA305" manufactured by Malvern). Based on standard polystyrene, the absolute molecular weight was determined from the results of the light scattering detector and the RI detector, and the intrinsic viscosity was determined from the results of the RI detector and the viscosity detector. For a linear polymer, the intrinsic viscosity [η] = -3.883M 0.771It was used as conforming to each, and the shrinkage factor (g') as the ratio of the intrinsic viscosity corresponding to each molecular weight was calculated. In the formula, M represents the absolute molecular weight. Thereafter, using the obtained shrinkage factor (g'), the branching degree (Bn) defined by g' = 6Bn / [(Bn + 1)(Bn + 2)] was calculated. As the eluent, tetrahydrofuran containing 5 mmol / L of triethylamine (hereinafter also referred to as "THF") was used. As the column, the products named "TSKgel G4000HXL", "TSKgel G5000HXL", and "TSKgel G6000HXL" manufactured by Tosoh Corporation were connected and used. 20 mg of the sample for measurement was dissolved in 10 mL of THF to prepare a measurement solution, 100 μL of the measurement solution was injected into a GPC measuring device, and measurement was carried out under the conditions of an oven temperature of 40°C and a THF flow rate of 1 mL / min.

[0235] (Physical property 4) Molecular weight <Measurement condition 1>: Using an unmodified conjugated diene polymer or a coupling conjugated diene polymer as a sample, a GPC measuring device (product name "HLC-8320GPC" manufactured by Tosoh Corporation) with three columns filled with a polystyrene gel as a filler connected was used, and a chromatogram was measured using an RI detector (product name "HLC8020" manufactured by Tosoh Corporation). Based on the calibration curve obtained using standard polystyrene, the weight average molecular weight (Mw), the number average molecular weight (Mn), and the molecular weight distribution (Mw / Mn) were determined. As the eluent, THF (tetrahydrofuran) containing 5 mmol / L of triethylamine was used. As the column, three products named "TSKgel SuperMultiporeHZ-H" manufactured by Tosoh Corporation were connected, and a product named "TSKguardcolumn SuperMP(HZ)-H" manufactured by Tosoh Corporation was connected as a guard column in front of them and used. 10 mg of the sample for measurement was dissolved in 10 mL of THF to prepare a measurement solution, 10 μL of the measurement solution was injected into a GPC measuring device, and measurement was carried out under the conditions of an oven temperature of 40°C and a THF flow rate of 0.35 mL / min. Among the various samples measured under the above measurement condition 1, the samples with a value of molecular weight distribution (Mw / Mn) less than 1.6 were re-measured under the following measurement condition 2. For the samples measured under measurement condition 1 and having a value of molecular weight distribution of 1.6 or more, the measured values measured under measurement condition 1 were adopted. <Measurement condition 2>: Using an unmodified conjugated diene polymer or a coupling conjugated diene polymer as a sample, a GPC measuring device with three columns connected in series filled with a polystyrene-based gel as a filler was used to measure a chromatogram, and the weight average molecular weight (Mw) and the number average molecular weight (Mn) were determined based on a calibration curve using standard polystyrene. The eluent used was THF containing 5 mmol / L of triethylamine. As the columns, a guard column: trade name "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation, and columns: trade names "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000" manufactured by Tosoh Corporation were used. Under the conditions of an oven temperature of 40°C and a THF flow rate of 0.6 mL / min, an RI detector (trade name "HLC8020" manufactured by Tosoh Corporation) was used. 10 mg of the sample for measurement was dissolved in 20 mL of THF to prepare a measurement solution, and 20 μL of the measurement solution was injected into the GPC measuring device for measurement. For the samples measured under measurement condition 1 and having a value of molecular weight distribution less than 1.6, they were measured under measurement condition 2.

[0236] (Physical property 5) Modification rate The modification rate of the coupling conjugated diene polymer was measured by the column adsorption GPC method as follows. Using the coupling conjugated diene polymer as a sample, by applying the property that the modified basic polymer component adsorbs to a GPC column filled with a silica-based gel as a filler, the measurement was performed. The adsorption amount to the silica-based column was measured from the difference between the chromatogram measured with a polystyrene-based column and the chromatogram measured with a silica-based column for a sample solution containing the sample and a low molecular weight internal standard polystyrene, and the modification rate was determined. Specifically, it is as shown below. Also, for the samples measured under Measurement Condition 1 of the above (Physical Property 4) and having a molecular weight distribution value of 1.6 or more, measurements were made under the following Measurement Condition 3. For the samples measured under Measurement Condition 1 of the above (Physical Property 4) and having a molecular weight distribution value of less than 1.6, measurements were made under the following Measurement Condition 4.

[0237] <Preparation of Sample Solution>: 10 mg of the sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF to prepare a sample solution. <Measurement Condition 3>: GPC measurement conditions using a polystyrene column: Using the product named "HLC-8320GPC" manufactured by Tosoh Corporation, THF containing 5 mmol / L of triethylamine was used as the eluent, 10 μL of the sample solution was injected into the apparatus, and a chromatogram was obtained using an RI detector under the conditions of a column oven temperature of 40°C and a THF flow rate of 0.35 mL / min. For the column, three columns named "TSKgel SuperMultipore HZ-H" manufactured by Tosoh Corporation were connected, and a guard column named "TSKguardcolumn SuperMP(HZ)-H" manufactured by Tosoh Corporation was connected in front of them for use.

[0238] <Measurement Condition 4>: THF containing 5 mmol / L of triethylamine was used as the eluent, and 20 μL of the sample solution was injected into the apparatus for measurement. For the column, a guard column: the product named "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation, columns: the products named "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000" manufactured by Tosoh Corporation were used. Measurements were made using an RI detector (HLC8020 manufactured by Tosoh Corporation) under the conditions of a column oven temperature of 40°C and a THF flow rate of 0.6 mL / min to obtain a chromatogram.

[0239] GPC measurement conditions using a silica column: Using the product named "HLC-8320GPC" manufactured by Tosoh Corporation, with THF as the eluent, 50 μL of the sample solution was injected into the apparatus, and a chromatogram was obtained using an RI detector under the conditions of a column oven temperature of 40 °C and a THF flow rate of 0.5 ml / min. The columns used were the products named "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S" connected in series, and a guard column named "DIOL 4.6×12.5mm 5micron" was connected and used in front of them.

[0240] Calculation method of modification rate: Taking the total peak area of the chromatogram using a polystyrene column as 100, the peak area of the sample as P1, the peak area of the standard polystyrene as P2, taking the total peak area of the chromatogram using a silica column as 100, the peak area of the sample as P3, and the peak area of the standard polystyrene as P4, the modification rate (%) was determined from the following formula. Modification rate (%) = [1 - (P2 × P3) / (P1 × P4)] × 100 (However, P1 + P2 = P3 + P4 = 100)

[0241] (Physical property 6) Bound styrene content Using a coupling conjugated diene polymer without a rubber softening agent as the sample, 100 mg of the sample was made up to 100 mL with chloroform and dissolved to obtain a measurement sample. Based on the absorption amount of the ultraviolet absorption wavelength (near 254 nm) by the phenyl group of styrene, the bound styrene content (mass %) with respect to 100 mass % of the coupling conjugated diene polymer as the sample was measured (measurement apparatus: spectrophotometer "UV-2450" manufactured by Shimadzu Corporation).

[0242] (Physical property 7) Microstructure of the butadiene part (1,2-vinyl bond content) Using a coupling conjugated diene polymer without a rubber softening agent as the sample, 50 mg of the sample was dissolved in 10 mL of carbon disulfide to obtain a measurement sample. Using a solution cell, an infrared spectrum was measured in the range of 600 - 1000 cm -1It was measured within the range, and the microstructure of the butadiene moiety, i.e., the amount of 1,2-vinyl bonds (mol%), was determined according to the calculation formula of the Hampton method (the method described in R.R. Hampton, Analytical Chemistry 21, 923 (1949)) based on the absorbance at a predetermined wave number (measurement apparatus: Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation).

[0243] (Physical Property 8) Molecular weight (absolute molecular weight) by GPC-light scattering method measurement Using a GPC-light scattering measurement apparatus in which three columns filled with a polystyrene-based gel were connected in series with a coupling conjugated diene-based polymer as a sample, a chromatogram was measured, and the weight average molecular weight (Mw-i) was determined based on the solution viscosity and the light scattering method (also referred to as "absolute molecular weight"). As the eluent, a mixed solution of tetrahydrofuran and triethylamine (THF in TEA: prepared by mixing 5 mL of triethylamine with 1 L of tetrahydrofuran) was used. As the columns, a guard column: trade name "TSKguardcolumn HHR-H" manufactured by Tosoh Corporation, and columns: trade names "TSKgel G6000HHR", "TSKgel G5000HHR", "TSKgel G4000HHR" manufactured by Tosoh Corporation were connected and used. Under the conditions of an oven temperature of 40°C and a THF flow rate of 1.0 mL / min, a GPC-light scattering measurement apparatus (trade name "Viscotek TDAmax" manufactured by Malvern) was used. 10 mg of the sample for measurement was dissolved in 20 mL of THF to prepare a measurement solution, and 200 μL of the measurement solution was injected into the GPC measurement apparatus for measurement.

[0244] [Branched conjugated diene-based polymer] (Example 1-1) Coupling conjugated diene-based polymer (Sample 1-1) Two tank-type pressure vessels each having an internal volume of 10 L, a ratio of internal height (L) to diameter (D) of 4.0, an inlet at the bottom, an outlet at the top, and equipped with a stirrer and a jacket for temperature control were connected in series as polymerization reactors. The pre - dehydrated 1,3 - butadiene was mixed at a rate of 18.6 g / min, styrene at a rate of 10.0 g / min, and n - hexane at a rate of 175.2 g / min. In a static mixer installed in the middle of the pipe supplying this mixed solution to the inlet of the reaction unit, n - butyllithium for treating residual impurities was added at a rate of 0.103 mmol / min and mixed, and then continuously supplied to the bottom of the reaction unit. Further, 2,2 - bis(2 - oxolanyl)propane as a polar substance was supplied to the bottom of the first reactor, which was vigorously mixed with a stirrer at a rate of 0.081 mmol / min, and n - butyllithium as a polymerization initiator was supplied at a rate of 0.143 mmol / min, and the temperature inside the reactor was maintained at 67°C. The polymer solution was continuously withdrawn from the top of the first reactor and continuously supplied to the bottom of the second reactor, and the reaction was continued at 70°C. Further, it was supplied from the top of the second reactor to a static mixer. When the polymerization was sufficiently stable, while copolymerizing 1,3 - butadiene and styrene, trimethoxy(4 - vinylphenyl)silane (abbreviated as "BS - 1" in the table) as a branching agent was added at a rate of 0.0190 mmol / min from the bottom of the second reaction unit, and a polymerization reaction and a branching reaction were carried out to obtain a conjugated diene - based polymer having a main - chain branched structure. Furthermore, when the polymerization reaction and the branching reaction were stable, a small amount of the conjugated diene - based polymer solution before adding the coupling agent was withdrawn, antioxidant (BHT) was added so that it was 0.2 g per 100 g of the polymer, and then the solvent was removed, and the Mooney viscosity at 110°C and various molecular weights were measured. The physical properties are shown in Table 1. Next, tetraethoxysilane (abbreviated as "A" in the table), as a coupling agent, was continuously added to the polymer solution flowing out of the reactor outlet at a rate of 0.0480 mmol / min, and mixed using a static mixer to carry out a coupling reaction. At this time, the time until the coupling agent was added to the polymer solution flowing out of the reactor outlet was 4.8 minutes, the temperature was 68 °C, and the difference between the temperature in the polymerization step and the temperature until the coupling agent was added was 2 °C. A small amount of the conjugated diene-based polymer solution after the coupling reaction was withdrawn, and after adding antioxidant (BHT) at 0.2 g per 100 g of the polymer, the solvent was removed, and the bound styrene content (physical property 6) and the microstructure of the butadiene moiety (1,2-vinyl bond content: physical property 7) were measured. The measurement results are shown in Table 1. Next, antioxidant (BHT) was continuously added to the polymer solution that had undergone the coupling reaction at 0.055 g / min (n-hexane solution) so that it was 0.2 g per 100 g of the polymer, and the coupling reaction was terminated. Simultaneously with the antioxidant, SRAE oil (JOMO Process NC140 manufactured by JX Nippon Oil & Energy Corporation) was continuously added at 25.0 g per 100 g of the polymer as a rubber softening agent, and mixed with a static mixer. The solvent was removed by steam stripping to obtain a coupled conjugated diene-based polymer (Sample 1-1) having a 4-branched structure derived from a branching agent (hereinafter also referred to as "branching agent structure (1)") represented by the following formula (1) in a part of the main chain and a 3-branched star polymer structure derived from the coupling agent. The physical properties of Sample 1-1 are shown in Table 1. In addition, for the polymer before the addition of the branching agent, the polymer after the addition of the branching agent, and the polymer in each step after the addition of the coupling agent, the structure of the coupled conjugated diene-based polymer was identified by comparing the molecular weight by GPC measurement and the branching degree by GPC measurement with a viscometer. Hereinafter, the structures of each sample were identified in the same manner.

[0245]

Chemical formula

[0246] (In formula (1), R1 represents any one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms, and may have a branched structure in a part thereof. X 1 is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen. Y 1 represents any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be independent of each other and may be the same or different.

[0247] (Example 1-2) Coupling conjugated diene polymer (Sample 1-2) A coupling conjugated diene polymer (Sample 1-2) having a 4-branched structure derived from the branching agent structure (1) in a part of the main chain and a 4-branched star polymer structure derived from the coupling agent was obtained in the same manner as in Example 1-1, except that the coupling agent was changed from tetraethoxysilane to 1,2-bis(triethoxysilyl)ethane (abbreviated as "B" in the table) and its addition amount was changed to 0.0360 mmol / min. The physical properties of Sample 1-2 are shown in Table 1.

[0248] (Example 1-3) Coupling conjugated diene polymer (Sample 1-3) A coupling conjugated diene polymer (Sample 1-3) having a 4-branched structure derived from the branching agent structure (1) in a part of the main chain and a 4-branched star polymer structure derived from the coupling agent was obtained in the same manner as in Example 1-1, except that the coupling agent was changed from tetraethoxysilane to 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (abbreviated as "C" in the table) and its addition amount was changed to 0.0360 mmol / min. The physical properties of Sample 1-3 are shown in Table 1.

[0249] (Example 1-4) Coupling conjugated diene polymer (Sample 1-4) The coupling agent was changed from tetraethoxysilane to 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (abbreviated as "D" in the table), and its addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-4) having a 4-branched structure derived from the branching agent structure (1) in some of the main chains and a 4-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-4 are shown in Table 1.

[0250] (Example 1-5) Coupling conjugated diene polymer (Sample 1-5) The coupling agent was changed from tetraethoxysilane to tris(3-trimethoxysilylpropyl)amine (abbreviated as "E" in the table), and its addition amount was changed to 0.0250 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-5) having a 4-branched structure derived from the branching agent structure (1) in some of the main chains and a 6-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-5 are shown in Table 1.

[0251] (Example 1-6) Coupling conjugated diene polymer (Sample 1-6) The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), and its addition amount was changed to 0.0190 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-6) having a 4-branched structure derived from the branching agent structure (1) in some of the main chains and an 8-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-6 are shown in Table 1.

[0252] (Example 1-7) Coupling conjugated diene polymer (Sample 1-7) The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), and its addition amount was changed to 0.0160 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-7) having a 4-branched structure derived from the branching agent structure (1) in a part of the main chain and an 8-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-7 are shown in Table 1.

[0253] (Example 1-8) Coupling conjugated diene polymer (Sample 1-8) The addition rate of 1,3-butadiene was changed from 18.6 g / min to 24.3 g / min, the addition rate of styrene was changed from 10.0 g / min to 4.3 g / min, and further, the addition rate of 2,2-bis(2-oxolanyl)propane as a polar substance was changed from 0.081 mmol / min to 0.044 mmol / min. The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), and its addition amount was changed to 0.0160 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-8) having a 4-branched structure derived from the branching agent structure (1) in a part of the main chain and an 8-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-8 are shown in Table 1.

[0254] (Example 1-9) Coupling conjugated diene polymer (Sample 1-9) The addition rate of 1,3-butadiene was changed from 18.6 g / min to 17.1 g / min, the addition rate of styrene was changed from 10.0 g / min to 11.5 g / min, and further, the addition rate of 2,2-bis(2-oxolanyl)propane as a polar substance was changed from 0.081 mmol / min to 0.089 mmol / min. The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), and its addition amount was changed to 0.0160 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-9) having a 4-branched structure derived from the branching agent structure (1) in a part of the main chain and an 8-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-9 are shown in Table 2.

[0255] (Example 1-10) Coupling conjugated diene polymer (Sample 1-10) The addition rate of 2,2-bis(2-oxolanyl)propane as a polar substance was changed from 0.081 mmol / min to 0.200 mmol / min. The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), and its addition amount was changed to 0.0160 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-10) having a 4-branched structure derived from the branching agent structure (1) in a part of the main chain and an 8-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-10 are shown in Table 2.

[0256] (Example 1-11) Coupling conjugated diene polymer (Sample 1-11) The branching agent was changed from trimethoxy(4-vinylphenyl)silane to dimethylmethoxy(4-vinylphenyl)silane (abbreviated as "BS-2" in the table), its addition amount was changed to 0.0350 mmol / min, the coupling agent was changed from tetraethoxysilane to 1,2-bis(triethoxysilyl)ethane (abbreviated as "B" in the table), and its addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-11) having a two-branched structure derived from the branching agent structure (1) in a part of the main chain and a four-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-11 are shown in Table 2.

[0257] (Example 1-12) Coupling conjugated diene polymer (Sample 1-12) The branching agent was changed from trimethoxy(4-vinylphenyl)silane to dimethylmethoxy(4-vinylphenyl)silane (abbreviated as "BS-2" in the table), its addition amount was changed to 0.0350 mmol / min, the coupling agent was changed from tetraethoxysilane to 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (abbreviated as "D" in the table), and its addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-12) having a two-branched structure derived from the branching agent structure (1) in a part of the main chain and a four-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-12 are shown in Table 2.

[0258] (Example 1-13) Coupling conjugated diene polymer (Sample 1-13) The disproportionating agent was changed from trimethoxy(4-vinylphenyl)silane to dimethylmethoxy(4-vinylphenyl)silane (abbreviated as "BS-2" in the table), its addition amount was changed to 0.0350 mmol / min, the coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), and its addition amount was changed to 0.0160 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-13) having a two-branched structure derived from the disproportionating agent structure (1) in a part of the main chain and an eight-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-13 are shown in Table 2.

[0259] (Example 1-14) Coupling conjugated diene polymer (Sample 1-14) The disproportionating agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene (abbreviated as "BS-3" in the table), its addition amount was changed to 0.0120 mmol / min, the coupling agent was changed from tetraethoxysilane to 1,2-bis(triethoxysilyl)ethane (abbreviated as "B" in the table), and its addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-14) having a three-branched structure derived from the disproportionating agent which is a compound represented by the following formula (2) (hereinafter also referred to as "disproportionating agent structure (2)") in a part of the main chain and a four-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-14 are shown in Table 2.

[0260] [Chemical formula]

[0261] (In formula (2), X 2 , X 3 is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen. Y 2 , Y 3represents any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be independent of each other, the same or different.)

[0262] (Example 1-15) Coupling conjugated diene polymer (Sample 1-15) The branching agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene (abbreviated as "BS-3" in the table), and its addition amount was changed to 0.0120 mmol / min. The coupling agent was changed from tetraethoxysilane to 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (abbreviated as "D" in the table), and its addition amount was changed to 0.0360 mmol / min. Except for this, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-15) having a three-branched structure derived from the branching agent structure (2) in some main chains and a four-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-15 are shown in Table 2.

[0263] (Example 1-16) Coupling conjugated diene polymer (Sample 1-16) The branching agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene (abbreviated as "BS-3" in the table), and its addition amount was changed to 0.0120 mmol / min. The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), and its addition amount was changed to 0.0160 mmol / min. Except for this, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-16) having a three-branched structure derived from the branching agent structure (2) in some main chains and an eight-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-16 are shown in Table 2.

[0264] (Example 1-17) Coupling conjugated diene polymer (Sample 1-17) The branching agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-trimethoxysilylphenyl)ethylene (abbreviated as "BS-4" in the table), its addition amount was changed to 0.0210 mmol / min, the coupling agent was changed from tetraethoxysilane to 1,2-bis(triethoxysilyl)ethane (abbreviated as "B" in the table), and its addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-17) having a 7-branched structure derived from the branching agent structure (2) in a part of the main chain and a 4-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-17 are shown in Table 3.

[0265] (Example 1-18) Coupling conjugated diene polymer (Sample 1-18) The branching agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-trimethoxysilylphenyl)ethylene (abbreviated as "BS-4" in the table), its addition amount was changed to 0.0210 mmol / min, the coupling agent was changed from tetraethoxysilane to 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (abbreviated as "D" in the table), and its addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-18) having a 7-branched structure derived from the branching agent structure (2) in a part of the main chain and a 4-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-18 are shown in Table 3.

[0266] (Example 1-19) Coupling conjugated diene polymer (Sample 1-19) The branching agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-trimethoxysilylphenyl)ethylene (abbreviated as "BS-4" in the table), and its addition amount was changed to 0.0210 mmol / min. The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table).), and its addition amount was changed to 0.0160 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-19) having a 7-branched structure derived from the branching agent structure (2) in a part of the main chain and an 8-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-19 are shown in Table 3.

[0267] (Example 1-20) Coupling conjugated diene polymer (Sample 1-20) The branching agent was changed from trimethoxy(4-vinylphenyl)silane to trichloro(4-vinylphenyl)silane (abbreviated as "BS-5" in the table), and its addition amount was changed to 0.0190 mmol / min. The coupling agent was changed from tetraethoxysilane to 1,2-bis(triethoxysilyl)ethane (abbreviated as "B" in the table).), and its addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-20) having a 4-branched structure derived from the branching agent structure (1) in a part of the main chain and an 8-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-20 are shown in Table 3.

[0268] (Example 1-21) Coupling conjugated diene polymer (Sample 1-21) The branching agent was changed from trimethoxy(4-vinylphenyl)silane to trichloro(4-vinylphenyl)silane (abbreviated as "BS-5" in the table), its addition amount was changed to 0.0190 mmol / min, the coupling agent was changed from tetraethoxysilane to 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (abbreviated as "D" in the table), and its addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-21) having a 4-branched structure derived from the branching agent structure (1) in a part of the main chain and an 8-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-21 are shown in Table 3.

[0269] (Example 1-22) Coupling conjugated diene polymer (Sample 1-22) The branching agent was changed from trimethoxy(4-vinylphenyl)silane to trichloro(4-vinylphenyl)silane (abbreviated as "BS-5" in the table), its addition amount was changed to 0.0190 mmol / min, the coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), and its addition amount was changed to 0.0160 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-22) having a 4-branched structure derived from the branching agent structure (1) in a part of the main chain and an 8-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-22 are shown in Table 3.

[0270] (Example 1-23) Coupling conjugated diene polymer (Sample 1-23) The addition amount of the branching agent trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was changed from 0.0190 mmol / min to 0.0100 mmol / min, and the coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table). Except that its addition amount was changed to 0.0190 mmol / min, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-23) having a four-branched structure derived from the branching agent structure (1) in a part of the main chain and an eight-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-23 are shown in Table 3.

[0271] (Example 1-24) Coupling conjugated diene polymer (Sample 1-24) The addition amount of the branching agent trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was changed from 0.0190 mmol / min to 0.0250 mmol / min, and the coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table). Except that its addition amount was changed to 0.0190 mmol / min, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-24) having a four-branched structure derived from the branching agent structure (1) in a part of the main chain and an eight-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-24 are shown in Table 4.

[0272] (Example 1-25) Coupling conjugated diene polymer (Sample 1-25) The addition amount of the branching agent trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was changed from 0.0190 mmol / min to 0.0350 mmol / min, and the coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table). Except that its addition amount was changed to 0.0190 mmol / min, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-25) having a four-branched structure derived from the branching agent structure (1) in a part of the main chain and an eight-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-25 are shown in Table 4.

[0273] (Example 1-26) Coupling conjugated diene polymer (Sample 1-26) The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table). Except that its addition amount was changed to 0.0190 mmol / min, the SRAE oil added as a rubber softening agent was changed to liquid rubber (liquid polybutadiene LBR-302 manufactured by Kuraray Co., Ltd.), in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-26) having a four-branched structure derived from the branching agent structure (1) in a part of the main chain and an eight-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-26 are shown in Table 4.

[0274] (Example 1-27) Coupling conjugated diene polymer (Sample 1-27) The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table). Except that its addition amount was changed to 0.0190 mmol / min, the SRAE oil added as a rubber softening agent was changed to resin (terpene resin YS resin PX1250 manufactured by Yasuhara Chemical Co., Ltd.), in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-27) having a four-branched structure derived from the branching agent structure (1) in a part of the main chain and an eight-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-27 are shown in Table 4.

[0275] (Example 1-28) Coupling conjugated diene polymer (Sample 1-28) The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), its addition amount was changed to 0.0190 mmol / min, and the SRAE oil added as a rubber softener was changed to naphthene oil (Nynas naphthene oil Nytex810). A coupling conjugated diene polymer (Sample 1-28) having a 4-branched structure derived from the branching agent structure (1) in a part of the main chain and an 8-branched star polymer structure derived from the coupling agent was obtained in the same manner as in Example 1-1. The physical properties of Sample 1-28 are shown in Table 4.

[0276] (Example 1-29) Coupling conjugated diene polymer (Sample 1-29) The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), its addition amount was changed to 0.0190 mmol / min, and a coupling conjugated diene polymer (Sample 1-29) having a 4-branched structure derived from the branching agent structure (1) in a part of the main chain and an 8-branched star polymer structure derived from the coupling agent was obtained in the same manner as in Example 1-1 except that no rubber softener was added. The physical properties of Sample 1-29 are shown in Table 4.

[0277] (Example 1-30) Coupling conjugated diene polymer (Sample 1-30) The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), its addition amount was changed to 0.0190 mmol / min, and the addition amount of the SRAE oil added as a rubber softener was changed from 25.0 g to 37.5 g per 100 g of the polymer. A coupling conjugated diene polymer (Sample 1-30) having a 4-branched structure derived from the branching agent structure (1) in a part of the main chain and an 8-branched star polymer structure derived from the coupling agent was obtained in the same manner as in Example 1-1. The physical properties of Sample 1-30 are shown in Table 4.

[0278] ( Reference Example Conjugated diene polymer (Sample 1-31) from 1 to 31 When the polymerization was sufficiently stable, from the bottom of the second reactive group, trimethoxy (4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was added at a rate of 0.0190 mmol / min, and except that no coupling agent was added, in the same manner as in Example 1-1 A conjugated diene polymer (Sample 1-31) having a four-branched structure derived from the branching agent structure (1) in a part of the main chain and not showing a star coupling structure derived from the coupling agent was obtained. The physical properties of Sample 1 -31 are shown in Table 5.

[0279] (Example 1-32) Coupling conjugated diene polymer (Sample 1-32) When the polymerization was sufficiently stable, from the bottom of the second reactive group, trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was added at a rate of 0.0190 mmol / min, and as the coupling agent, except that the addition amount of tetraethoxysilane (abbreviated as "A" in the table) was changed from 0.0480 mmol / min to 0.0120 mmol / min, in the same manner as in Example 1-1, a coupling conjugated diene polymer having a four-branched structure derived from the branching agent structure (1) in a part of the main chain and having a partially three-branched star polymer structure derived from the coupling agent (Sample 1-32) was obtained. The physical properties of Sample 1-32 are shown in Table 5.

[0280] (Example 1-33) Coupling conjugated diene polymer (Sample 1-33) ​When the coincidence became sufficiently stable, from the bottom of the second reactive group, trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was added as a branching agent at a rate of 0.0190 mmol / min, and as a coupling agent, tetraethoxysilane was changed to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), and its addition amount was changed to 0.0038 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-33) having a four-branched structure derived from the branching agent structure (1) in a part of the main chain and a partially eight-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-33 are shown in Table 5.

[0281] (Example 1-34) Coupling conjugated diene polymer (Sample 1-34) When the polymerization became sufficiently stable, from the bottom of the second reactive group, dimethylmethoxy(4-vinylphenyl)silane (abbreviated as "BS-2" in the table) was added as a branching agent at a rate of 0.0350 mmol / min, and the addition amount of tetraethoxysilane as the coupling agent was changed from 0.0480 mmol / min to 0.0120 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-34) having a two-branched structure derived from the branching agent structure (1) in a part of the main chain and a partially three-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-34 are shown in Table 5.

[0282] (Example 1-35) Coupling conjugated diene polymer (Sample 1-35) When the polymerization became sufficiently stable, from the bottom of the second reactive group, 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene (abbreviated as "BS-3" in the table) was added as a branching agent at a rate of 0.0120 mmol / min, and the addition amount of tetraethoxysilane as the coupling agent was changed from 0.0480 mmol / min to 0.0120 mmol / min. Otherwise, in the same manner as in Example 1-1, a coupling conjugated diene polymer (Sample 1-35) having a three-branched structure derived from the branching agent structure (2) in a part of the main chain and a partially three-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1-35 are shown in Table 5.

[0283] (Examples 1 - 36) Coupling conjugated diene polymer (Samples 1 - 36) A coupling conjugated diene polymer (Samples 1 - 36) having a 4 - branched structure derived from the branching agent structure (1) in a part of the main chain and a 2 - branched star polymer structure derived from the coupling agent was obtained in the same manner as in Example 1 - 1, except that the coupling agent was changed from tetraethoxysilane to 3 - (benzylideneamino)propyltriethoxysilane (abbreviated as "G" in the table) and its addition amount was changed to 0.0620 mmol / min. The physical properties of Samples 1 - 36 are shown in Table 5.

[0284] (Examples 1 - 37) Coupling conjugated diene polymer (Samples 1 - 37) A coupling conjugated diene polymer (Samples 1 - 37) having a 4 - branched structure derived from the branching agent structure (1) in a part of the main chain and a 4 - branched star polymer structure derived from the coupling agent was obtained in the same manner as in Example 1 - 1, except that the 1,3 - butadiene added to the first reactor was changed from 18.6 g / min to 13.95 g / min and 4.65 g / min of 1,3 - butadiene was added simultaneously with the branching agent from the bottom of the second reaction group. The physical properties of Samples 1 - 37 are shown in Table 5.

[0285] (Comparative Example 1 - 1) Coupling conjugated diene polymer (Samples 1 - 38) Two tank - type pressure vessels each having a stirrer and a jacket for temperature control were connected as polymerization reactors. Each tank - type pressure vessel had an internal volume of 10 L, the ratio of the internal height (L) to the diameter (D) was 4.0, had an inlet at the bottom and an outlet at the top, and was a tank - type reactor with a stirrer. 1,3 - butadiene that had been pre - dehydrated was mixed with styrene at a rate of 18.6 g / min and n - hexane at a rate of 175.2 g / min. In a static mixer installed in the middle of the pipe supplying this mixed solution to the inlet of the reaction unit, n - butyllithium for treating residual impurities was added at a rate of 0.103 mmol / min and mixed, and then continuously supplied to the bottom of the reaction unit. Further, 2,2 - bis(2 - oxolanyl)propane as a polar substance was supplied to the bottom of the first reactor at a rate of 0.081 mmol / min, and n - butyllithium as a polymerization initiator was supplied at a rate of 0.143 mmol / min, and they were vigorously mixed with a stirrer, and the internal temperature of the reactor was maintained at 67 °C. The polymer solution was continuously withdrawn from the top of the first reactor and continuously supplied to the bottom of the second reactor, and the reaction was continued at 70 °C. Further, it was supplied from the top of the second reactor to a static mixer. When the polymerization was sufficiently stable, a small amount of the polymer solution before adding the coupling agent was withdrawn, antioxidant (BHT) was added so that it was 0.2 g per 100 g of the polymer, and then the solvent was removed, and the Mooney viscosity at 110 °C and various molecular weights were measured. The physical properties are shown in Table 6. Next, tetraethoxysilane (abbreviated as "A" in the table) as a coupling agent was continuously added to the polymer solution flowing out from the outlet of the reactor at a rate of 0.0480 mmol / min, and mixed using a static mixer for a coupling reaction. At this time, the time until the coupling agent was added to the polymer solution flowing out from the outlet of the reactor was 4.8 minutes, the temperature was 68 °C, and the difference between the temperature in the polymerization step and the temperature until the coupling agent was added was 2 °C. A small amount of the conjugated diene - based polymer solution after the coupling reaction was withdrawn, antioxidant (BHT) was added so that it was 0.2 g per 100 g of the polymer, and then the solvent was removed, and the bound styrene amount (physical property 6) and the microstructure of the butadiene part (1,2 - vinyl bond amount: physical property 7) were measured. The measurement results are shown in Table 6. Next, an antioxidant (BHT) was continuously added to the polymer solution after the coupling reaction at a rate of 0.055 g / min (n - hexane solution) so that the amount was 0.2 g per 100 g of the polymer, and the coupling reaction was terminated. Simultaneously with the antioxidant, as a softening agent for rubber, SRAE oil (JOMO Process NC140, manufactured by JX Nippon Mining & Energy Corporation) was continuously added so that the amount was 25.0 g per 100 g of the polymer, and the mixture was mixed with a static mixer. The solvent was removed by steam stripping to obtain a coupling conjugated diene - based polymer (Sample 1 - 38) having no main - chain branches derived from the branching agent and having a three - branched star - shaped polymer structure derived from the coupling agent. The physical properties of Sample 1 - 38 are shown in Table 6.

[0286] (Comparative Example 1 - 2) Coupling conjugated diene - based polymer (Sample 1 - 39) The coupling agent was changed from tetraethoxysilane to 2,2 - dimethoxy - 1-(3 - trimethoxysilylpropyl)-1 - azasilacyclopentane (abbreviated as "D" in the table), and its addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as Comparative Example 1 - 1, a coupling conjugated diene - based polymer (Sample 1 - 39) having no main - chain branches derived from the branching agent and having a four - branched star - shaped polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1 - 39 are shown in Table 6.

[0287] (Comparative Example 1 - 3) Coupling conjugated diene - based polymer (Sample 1 - 40) The coupling agent was changed from tetraethoxysilane to tetrakis(3 - trimethoxysilylpropyl)-1,3 - propanediamine (abbreviated as "F" in the table), and its addition amount was changed to 0.0190 mmol / min. Otherwise, in the same manner as Comparative Example 1 - 1, a coupling conjugated diene - based polymer (Sample 1 - 40) having no main - chain branches derived from the branching agent and having an eight - branched star - shaped polymer structure derived from the coupling agent was obtained. The physical properties of Sample 1 - 40 are shown in Table 6.

[0288] [Table 1]

[0289]

Table 2

[0290]

Table 3

[0291]

Table 4

[0292]

Table 5

[0293]

Table 6

[0294] (Examples 1-38~ 1-67, Reference Example 1-68, Example 1-69~ 1-74, and Comparative Examples 1-4~1-6) Using Samples 1-1~1-40 shown in Tables 1~6 as raw rubbers, rubber compositions containing each raw rubber were obtained according to the following formulations.

[0295] (Rubber Components) · Branched conjugated diene polymer and coupled conjugated diene polymer (Samples 1-1~1-40) : 80 parts by mass (parts by mass excluding rubber softener) · High cis polybutadiene (trade name "UBEPOL BR150" manufactured by Ube Industries, Ltd.) : 20 parts by mass

[0296] (Formulation Conditions) The addition amounts of each compounding agent were shown as parts by mass based on 100 parts by mass of the rubber components excluding the rubber softener. · Silica 1 (trade name "Ultrasil 7000GR" manufactured by Evonik Degussa) Nitrogen adsorption specific surface area 170 m² / g): 50.0 parts by mass · Silica 2 (Product name of Rhodia: "Zeosil Premium 200MP") Nitrogen adsorption specific surface area 220 m² / g): 25.0 parts by mass · Carbon black (Product name of Tokai Carbon Co., Ltd.: "Seast KH (N339)") : 5.0 parts by mass · Silane coupling agent (Product name of Evonik Degussa: "Si75", bis(triethoxysilylpropyl) disulfide): 6.0 parts by mass · SRAE oil (Product name of JX Nippon Oil & Energy Corporation: "Process NC140") : 42.0 parts by mass (Including the amount previously added as a rubber softening agent contained in Samples 1-1 to 1-40) · Zinc oxide: 2.5 parts by mass · Stearic acid: 1.0 part by mass · Antioxidant (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 2.0 parts by mass · Sulfur: 2.2 parts by mass · Vulcanization accelerator 1 (N-cyclohexyl-2-benzothiazylsulfinamide) : 1.7 parts by mass · Vulcanization accelerator 2 (diphenylguanidine): 2.0 parts by mass · Total: 239.4 parts by mass

[0297] (Kneading method) The above materials were kneaded by the following method to obtain a rubber composition. Using a sealed kneader (internal volume 0.3 L) equipped with a temperature control device, as the first-stage kneading, under the conditions of a filling rate of 65% and a rotor rotation speed of 30 to 50 rpm, the raw rubber (Samples 1-1 to 1-40), fillers (Silica 1, Silica 2, Carbon black), silane coupling agent, SRAE oil, zinc oxide, and stearic acid were kneaded. At this time, the temperature of the sealed mixer was controlled, and the discharge temperature was 155 to 160 °C to obtain each rubber composition (compound). Next, as the kneading in the second stage, after cooling the formulation obtained above to room temperature, an antioxidant was added and kneaded again to improve the dispersion of silica. Also in this case, the discharge temperature of the formulation was adjusted to 155 - 160°C by controlling the temperature of the mixer. After cooling, as the kneading in the third stage, sulfur, vulcanization accelerators 1 and 2 were added and kneaded on an open roll set at 70°C. Thereafter, it was molded and vulcanized in a vulcanization press at 160°C for 20 minutes. The rubber composition before vulcanization and the rubber composition after vulcanization were evaluated. Specifically, they were evaluated by the following methods. The results are shown in Tables 7 - 12.

[0298] [Evaluation of Properties] (Evaluation 1) Mooney viscosity of the formulation Using the formulation obtained after the kneading in the second stage above and before the kneading in the third stage as a sample, a Mooney viscometer was used. In accordance with ISO 289, after preheating at 130°C for 1 minute, the viscosity was measured after rotating the rotor at 2 revolutions per minute for 4 minutes. The results of Comparative Examples 1 - 4 were indexed with 100 as the reference. The smaller the index, the better the processability.

[0299] (Evaluation 2) Tensile strength and elongation at break In accordance with the tensile test method of JIS K6251, the tensile strength and elongation at break were measured, and the results of Comparative Examples 1 - 4 were indexed with 100 as the reference. The larger the index, the better the tensile strength and elongation at break (breaking strength).

[0300] (Evaluation 3) Abrasion resistance Using an Akron abrasion tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), in accordance with JIS K6264 - 2, the abrasion loss at a load of 44.4 N and 1000 revolutions was measured, and the results of Comparative Examples 1 - 4 were indexed with 100 as the reference. The larger the index, the better the abrasion resistance.

[0301] (Evaluation 4) Viscoelastic parameters Using the viscoelastic tester "ARES" manufactured by Rheometrics Scientific, viscoelastic parameters were measured in torsion mode. Each measured value was indexed with the results for the rubber compositions of Comparative Examples 1-4 set to 100. Tanδ measured at 0 °C, a frequency of 10 Hz, and a strain of 1% was used as an index of wet skid resistance. A larger index indicates better wet skid resistance. Also, tanδ measured at 50 °C, a frequency of 10 Hz, and a strain of 3% was used as an index of fuel efficiency. A smaller index indicates better fuel efficiency. Furthermore, the elastic modulus (G’) measured at 50 °C, a frequency of 10 Hz, and a strain of 3% was used as an index of handling stability. A larger index indicates better handling stability.

[0302]

Table 7

[0303]

Table 8

[0304]

Table 9

[0305]

Table 10

[0306]

Table 11

[0307]

Table 12

[0308] As shown in Tables 7 to 12, Examples 1-38~ 1-67, Reference Example 1-68, Example 1-69~1-74 showed good processability with a lower Mooney viscosity of the compound when making a vulcanizate compared with Comparative Examples 1-4 to 1-6, was excellent in abrasion resistance, handling stability and breaking strength when made into a vulcanizate, and was also confirmed to be excellent in the balance between low hysteresis loss property and wet skid resistance property.

[0309] 〔Second Example〕 Hereinafter, various physical properties of Examples and Comparative Examples of 〔Second Example〕 were measured by the methods shown below. In the following, a conjugated diene polymer coupled with a nitrogen atom-containing modifier composed of a predetermined compound is described as a "coupled conjugated diene polymer". Also, an unmodified conjugated diene polymer is described as an "unmodified conjugated diene polymer". Furthermore, a conjugated diene polymer having a branched structure is described as a "branched conjugated diene polymer".

[0310] (Physical Property 1) Polymer Mooney viscosity Using an unmodified conjugated diene polymer or a conjugated diene polymer coupled with a nitrogen atom-containing modifier (hereinafter also referred to as a "coupled conjugated diene polymer") as a sample, a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) was used, and in accordance with ISO 289, the Mooney viscosity was measured using an L-shaped rotor. The measurement temperature was 110 °C when using an unmodified conjugated diene polymer as a sample, and 100 °C when using a coupled conjugated diene polymer as a sample. First, after preheating the sample at the test temperature for 1 minute, the rotor was rotated at 2 rpm, and the torque after 4 minutes was measured to obtain the Mooney viscosity (ML (1+4) ).

[0311] (Physical Property 2) Mooney relaxation rate Using a coupling conjugated diene polymer as a sample, the Mooney viscosity was measured in accordance with ISO 289 using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho) with an L-shaped rotor. After the measurement, the rotation of the rotor was immediately stopped, and the torque every 0.1 second from 1.6 seconds to 5 seconds after the stop was recorded in Mooney units. The slope of the straight line when the torque and time (seconds) were plotted on a log-log scale was determined, and the absolute value thereof was defined as the Mooney relaxation rate (MSR).

[0312] (Physical property 3) Branching degree (Bn) The branching degree (Bn) of the coupling conjugated diene polymer was measured as follows by GPC-light scattering method measurement with a viscosity detector. Using a coupling conjugated diene polymer as a sample, a gel permeation chromatography (GPC) measuring device (trade name "GPCmax VE-2001" manufactured by Malvern) with three columns filled with polystyrene-based gels connected in series was used. Measurement was carried out using three detectors connected in the order of a light scattering detector, an RI detector, and a viscosity detector (trade name "TDA305" manufactured by Malvern). Based on standard polystyrene, the absolute molecular weight was determined from the results of the light scattering detector and the RI detector, and the intrinsic viscosity was determined from the results of the RI detector and the viscosity detector. The linear polymer was used as one that follows [η]=-3.883M 0.771 and the shrinkage factor (g') as the ratio of the intrinsic viscosity corresponding to each molecular weight was calculated. In the formula, M represents the absolute molecular weight. Thereafter, using the obtained shrinkage factor (g'), the branching degree (Bn) defined by g'=6Bn / [(Bn + 1)(Bn + 2)] was calculated. The eluent used was tetrahydrofuran containing 5 mmol / L of triethylamine (hereinafter also referred to as "THF"). The columns used were "TSKgel G4000HXL", "TSKgel G5000HXL", and "TSKgel G6000HXL" manufactured by Tosoh Corporation connected together. 20 mg of the sample for measurement was dissolved in 10 mL of THF to prepare a measurement solution, and 100 μL of the measurement solution was injected into the GPC measuring device, and the measurement was carried out under the conditions of an oven temperature of 40°C and a THF flow rate of 1 mL / min.

[0313] (Physical Property 4) Molecular Weight <Measurement Condition 1>: Using an unmodified conjugated diene polymer or a coupling conjugated diene polymer as a sample, a GPC measuring device (trade name "HLC-8320GPC" manufactured by Tosoh Corporation) with three columns filled with polystyrene gel as a filler was used, and a chromatogram was measured using an RI detector (trade name "HLC8020" manufactured by Tosoh Corporation). Based on the calibration curve obtained using standard polystyrene, the weight average molecular weight (Mw), the number average molecular weight (Mn), and the molecular weight distribution (Mw / Mn) were determined. The eluent used was THF (tetrahydrofuran) containing 5 mmol / L of triethylamine. Three columns with the trade name "TSKgel SuperMultipore HZ-H" manufactured by Tosoh Corporation were connected, and a guard column with the trade name "TSKguardcolumn SuperMP(HZ)-H" manufactured by Tosoh Corporation was connected in front of them for use. 10 mg of the sample for measurement was dissolved in 10 mL of THF to prepare a measurement solution, and 10 μL of the measurement solution was injected into the GPC measuring device and measured under the conditions of an oven temperature of 40°C and a THF flow rate of 0.35 mL / min. Among the various samples measured under the above Measurement Condition 1, the samples with a molecular weight distribution (Mw / Mn) value of less than 1.6 were re-measured under the following Measurement Condition 2. The samples measured under Measurement Condition 1 and having a molecular weight distribution value of 1.6 or more were measured under Measurement Condition 1. <Measurement Condition 2>: Using an unmodified conjugated diene polymer or a coupling conjugated diene polymer as a sample, a chromatogram was measured using a GPC measuring device with three columns filled with polystyrene gel as a filler, and the weight average molecular weight (Mw) and the number average molecular weight (Mn) were determined based on the calibration curve obtained using standard polystyrene. The eluent used was THF containing 5 mmol / L of triethylamine. For the column, a guard column: the product name "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation, and columns: the product names "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000" manufactured by Tosoh Corporation were used. Under the conditions of an oven temperature of 40 °C and a THF flow rate of 0.6 mL / min, an RI detector (product name "HLC8020" manufactured by Tosoh Corporation) was used. 10 mg of the sample for measurement was dissolved in 20 mL of THF to prepare a measurement solution, and 20 μL of the measurement solution was injected into a GPC measuring device for measurement. For the samples measured under Measurement Condition 1 and having a molecular weight distribution value of less than 1.6, measurement was performed under Measurement Condition 2.

[0314] (Physical Property 5) Modification Rate The modification rate of the coupling conjugated diene polymer was measured by the column adsorption GPC method as follows. Using the coupling conjugated diene polymer as a sample, measurement was performed by applying the property that the modified basic polymer component is adsorbed onto a GPC column filled with a silica-based gel as a filler. The adsorption amount onto the silica-based column was measured from the difference between the chromatogram measured with a polystyrene-based column and the chromatogram measured with a silica-based column for a sample solution containing the sample and a low molecular weight internal standard polystyrene, and the modification rate was determined. Specifically, it is as shown below. Also, for the samples measured under Measurement Condition 1 of the above (Physical Property 4) and having a molecular weight distribution value of 1.6 or more, measurement was performed under the following Measurement Condition 3. For the samples measured under Measurement Condition 1 of the above (Physical Property 4) and having a molecular weight distribution value of less than 1.6, measurement was performed under the following Measurement Condition 4.

[0315] <Preparation of Sample Solution>: 10 mg of the sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF to prepare a sample solution.

[0316] <Measurement Condition 3>: GPC measurement conditions using a polystyrene column: Using the product name "HLC-8320GPC" manufactured by Tosoh Corporation, with THF containing 5 mmol / L of triethylamine as the eluent, 10 μL of the sample solution was injected into the apparatus, and a chromatogram was obtained using an RI detector under the conditions of a column oven temperature of 40 °C and a THF flow rate of 0.35 mL / min. Three columns with the product name "TSKgel SuperMultipore HZ-H" manufactured by Tosoh Corporation were connected, and a guard column with the product name "TSKguardcolumn SuperMP(HZ)-H" manufactured by Tosoh Corporation was connected in front of them for use.

[0317] <Measurement condition 4>: Using THF containing 5 mmol / L of triethylamine as the eluent, 20 μL of the sample solution was injected into the apparatus for measurement. The columns used were a guard column: the product name "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation, and columns: the product name "TSKgel SuperH5000", "TSKgel SuperH6000", "TSKgel SuperH7000" manufactured by Tosoh Corporation. Measurement was carried out using an RI detector (HLC8020 manufactured by Tosoh Corporation) under the conditions of a column oven temperature of 40 °C and a THF flow rate of 0.6 mL / min to obtain a chromatogram.

[0318] GPC measurement conditions using a silica column: Using the product name "HLC-8320GPC" manufactured by Tosoh Corporation, with THF as the eluent, 50 μL of the sample solution was injected into the apparatus, and a chromatogram was obtained using an RI detector under the conditions of a column oven temperature of 40 °C and a THF flow rate of 0.5 mL / min. The columns used were the product names "Zorbax PSA-1000S", "PSA-300S", "PSA-60S" connected together, and a guard column with the product name "DIOL 4.6×12.5mm 5micron" was connected in front of them for use.

[0319] Calculation method of the modification rate: Using the entire peak area of the chromatogram obtained with a polystyrene column as 100, the peak area of the sample is designated as P1, the peak area of the standard polystyrene as P2. Using the entire peak area of the chromatogram obtained with a silica column as 100, the peak area of the sample is designated as P3, and the peak area of the standard polystyrene as P4. The modification rate (%) was determined from the following formula. Modification rate (%) = [1 - (P2 × P3) / (P1 × P4)] × 100 (However, P1 + P2 = P3 + P4 = 100)

[0320] (Physical property 6) Styrene content A coupling conjugated diene polymer without a rubber softening agent was used as a sample. 100 mg of the sample was made up to 100 mL with chloroform and dissolved to obtain a measurement sample. Based on the absorption amount of the ultraviolet absorption wavelength (near 254 nm) by the phenyl group of styrene, the styrene content (mass %) with respect to 100 mass % of the coupling conjugated diene polymer as the sample was measured (measurement device: spectrophotometer "UV-2450" manufactured by Shimadzu Corporation).

[0321] (Physical property 7) Microstructure of the butadiene portion (1,2-vinyl bond content) A coupling conjugated diene polymer without a rubber softening agent was used as a sample. 50 mg of the sample was dissolved in 10 mL of carbon disulfide to obtain a measurement sample. Using a solution cell, an infrared spectrum was measured in the range of 600 to 1000 cm -1 and the micro-structure of the butadiene portion, that is, the 1,2-vinyl bond content (mol %) was determined according to the calculation formula of the Hampton method (the method described in R.R. Hampton, Analytical Chemistry 21, 923 (1949)) from the absorbance at a predetermined wave number (measurement device: Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation).

[0322] (Physical property 8) Molecular weight (absolute molecular weight Mw-i) by GPC-light scattering method measurement Using a coupling conjugated diene polymer as a sample, a chromatogram was measured using a GPC-light scattering measurement device in which three columns filled with a polystyrene-based gel as a filler were connected, and the weight average molecular weight (Mw-i) was determined based on the solution viscosity and the light scattering method (also referred to as "absolute molecular weight"). As the eluent, a mixed solution of tetrahydrofuran and triethylamine (THF in TEA: prepared by mixing 5 mL of triethylamine with 1 L of tetrahydrofuran) was used. As the columns, a guard column: trade name "TSKguardcolumn HHR-H" manufactured by Tosoh Corporation, and columns: trade names "TSKgel G6000HHR", "TSKgel G5000HHR", and "TSKgel G4000HHR" manufactured by Tosoh Corporation were connected and used. Under the conditions of an oven temperature of 40 °C and a THF flow rate of 1.0 mL / min, a GPC-light scattering measurement device (trade name "Viscotek TDAmax" manufactured by Malvern) was used. 10 mg of the sample for measurement was dissolved in 20 mL of THF to prepare a measurement solution, and 200 μL of the measurement solution was injected into the GPC measurement device for measurement.

[0323] (Evaluation 9) Change over time (increase in Mooney viscosity after 1 month) The coupling conjugated diene polymer was stored at room temperature and normal pressure for 1 month, the Mooney viscosity after storage was measured, and the difference from the Mooney viscosity measured immediately after polymerization was calculated. In the table, it is indicated as "δML Mooney viscosity". The smaller the value, the less the change over time, indicating excellent quality stability.

[0324] [Branched conjugated diene polymer] (Example 2-1) Branched conjugated diene polymer (Sample 2-1) Two tank-type pressure vessels having a stirrer and a jacket for temperature control were connected as polymerization reactors, each having an internal volume of 10 L, a ratio of internal height (L) to diameter (D) of 4.0, an inlet at the bottom, and an outlet at the top, and being a tank-type reactor with a stirrer. 1,3 - butadiene that had been dehydrated in advance was mixed with styrene at 10.0 g / min and n - hexane at 175.2 g / min at a rate of 18.6 g / min. In a static mixer installed in the middle of the pipe supplying this mixed solution to the inlet of the reaction group, n - butyllithium for treating residual impurities in an inert manner was added and mixed at 0.103 mmol / min, and then continuously supplied to the bottom of the reaction group. Further, 2,2 - bis(2 - oxolanyl)propane as a polar substance was supplied to the bottom of the first reactor at a rate of 0.081 mmol / min, and n - butyllithium as a polymerization initiator was supplied to the bottom of the first reactor at a rate of 0.143 mmol / min and vigorously mixed with a stirrer, and the temperature inside the reactor was maintained at 67 °C. The polymer solution was continuously withdrawn from the top of the first reactor and continuously supplied to the bottom of the second reactor, and the reaction was continued at 70 °C. Further, it was supplied from the top of the second reactor to a static mixer. When the polymerization was sufficiently stable, while copolymerizing 1,3 - butadiene and styrene, trimethoxy(4 - vinylphenyl)silane (abbreviated as "BS - 1" in the table) as a branching agent was added from the bottom of the second reaction group at a rate of 0.0190 mmol / min, and a polymerization reaction and a branching reaction were carried out to obtain a conjugated diene - based polymer having a main - chain branched structure. Furthermore, when the polymerization reaction and the branching reaction were stable, a small amount of the conjugated diene - based polymer solution before adding the modifier was withdrawn, antioxidant (BHT) was added so as to be 0.2 g per 100 g of the polymer, and then the solvent was removed, and the Mooney viscosity at 110 °C and various molecular weights were measured. The physical properties are shown in Table 13. Next, compound A - 1 (the compound shown in (A - 1) among the compounds [A] used in the above <modification step>. Abbreviated as "A - 1" in the table) as a coupling agent was continuously added to the polymer solution flowing out from the outlet of the reactor at a rate of 0.0360 mmol / min, and mixed using a static mixer for a coupling reaction. At this time, the time until the modifier was added to the polymer solution flowing out from the outlet of the reactor was 4.8 minutes, the temperature was 68 °C, and the difference between the temperature in the polymerization step and the temperature until the modifier was added was 2 °C. A small amount of the conjugated diene polymer solution after the coupling reaction was taken out, and an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of the polymer. Then the solvent was removed, and the bound styrene amount (physical property 6) and the microstructure of the butadiene moiety (1,2-vinyl bond amount: physical property 7) were measured. The measurement results are shown in Table 13. Next, an antioxidant (BHT) was continuously added to the polymer solution after the coupling reaction at 0.055 g / min (n-hexane solution) so that the amount was 0.2 g per 100 g of the polymer, and the coupling reaction was terminated. Simultaneously with the antioxidant, as a rubber softening agent, SRAE oil (JOMO Process NC140 manufactured by JX Nippon Oil & Energy Corporation) was continuously added so that the amount was 25.0 g per 100 g of the polymer, and the mixture was mixed with a static mixer. The solvent was removed by steam stripping to obtain a branched conjugated diene polymer (Sample 2-1). The physical properties of Sample 2-1 are shown in Table 13. Regarding the polymer before the addition of the branching agent, the polymer after the addition of the branching agent, and the polymers in each step after the addition of the coupling agent, the structure of the branched conjugated diene polymer was identified by comparing the molecular weight by GPC measurement and the branching degree by GPC measurement with a viscometer. Hereinafter, the structures of each sample were identified in the same manner.

[0325] (Example 2-2) Branched conjugated diene polymer (Sample 2-2) A branched conjugated diene polymer (Sample 2-2) was obtained in the same manner as in Example 2-1, except that the coupling agent was changed from Compound A-1 to Compound A-2 (the compound shown in (A-2) among the compounds [A] used in the above <modification step>. In the table, it is abbreviated as "A-2"). The physical properties of Sample 2-2 are shown in Table 13.

[0326] (Example 2-3) Branched conjugated diene polymer (Sample 2-3) A branched conjugated diene polymer (Sample 2-3) was obtained in the same manner as in Example 2-1, except that the coupling agent was changed from Compound A-1 to Compound A-4 (the compound shown in (A-4) among the compounds [A] used in the above <modification step>. In the table, it is abbreviated as "A-4"), and the addition amount was changed to 0.0720 mmol / min. The physical properties of Sample 2-3 are shown in Table 13.

[0327] (Example 2-4) Branched conjugated diene polymer (Sample 2-4) A branched conjugated diene polymer (Sample 2-4) was obtained in the same manner as in Example 2-1, except that the coupling agent was changed from Compound A-1 to Compounds A-6 (the compound shown as (A-6) in the above [Compound [A] used in the modification step], abbreviated as "A-6" in the table). The physical properties of Sample 2-4 are shown in Table 13.

[0328] (Example 2-5) Branched conjugated diene polymer (Sample 2-5) A branched conjugated diene polymer (Sample 2-5) was obtained in the same manner as in Example 2-1, except that the coupling agent was changed from Compound A-1 to Compounds A-8 (the compound shown as (A-8) in the above [Compound [A] used in the modification step], abbreviated as "A-8" in the table), and the addition amount was changed to 0.0720 mmol / min. The physical properties of Sample 2-5 are shown in Table 13.

[0329] (Example 2-6) Branched conjugated diene polymer (Sample 2-6) A branched conjugated diene polymer (Sample 2-6) was obtained in the same manner as in Example 2-1, except that the coupling agent was changed from Compound A-1 to Compounds A-9 (the compound shown as (A-9) in the above [Compound [A] used in the modification step], abbreviated as "A-9" in the table). The physical properties of Sample 2-6 are shown in Table 13.

[0330] (Example 2-7) Branched conjugated diene polymer (Sample 2-7) A branched conjugated diene polymer (Sample 2-7) was obtained in the same manner as in Example 2-1, except that the coupling agent was changed from Compound A-1 to Compounds A-10 (the compound shown as (A-10) in the above [Compound [A] used in the modification step], abbreviated as "A-10" in the table). The physical properties of Sample 2-7 are shown in Table 13.

[0331] (Example 2-8) Branched conjugated diene polymer (Sample 2-8) The coupling agent was changed from Compound A-1 to Compound A-12 (the compound shown as (A-12) in the above [Compound [A] used in the modification step], abbreviated as "A-12" in the table), and the addition amount was changed to 0.0720 mmol / min. Otherwise, in the same manner as in Example 2-1, a branched conjugated diene polymer (Sample 2-8) was obtained. The physical properties of Sample 2-8 are shown in Table 13.

[0332] (Example 2-9) Branched conjugated diene polymer (Sample 2-9) The coupling agent was changed from Compound A-1 to Compound A-13 (the compound shown as (A-13) in the above [Compound [A] used in the modification step], abbreviated as "A-13" in the table), and the addition amount was changed to 0.0160 mmol / min. Otherwise, in the same manner as in Example 2-1, a branched conjugated diene polymer (Sample 2-9) was obtained. The physical properties of Sample 2-9 are shown in Table 13.

[0333] (Example 2-10) Branched conjugated diene polymer (Sample 2-10) The coupling agent was changed from Compound A-1 to Compound A-14 (the compound shown as (A-14) in the above [Compound [A] used in the modification step], abbreviated as "A-14" in the table), and the addition amount was changed to 0.0160 mmol / min. Otherwise, in the same manner as in Example 2-1, a branched conjugated diene polymer (Sample 2-10) was obtained. The physical properties of Sample 2-10 are shown in Table 13.

[0334] (Example 2-11) Branched conjugated diene polymer (Sample 2-11) The coupling agent was changed from Compound A-1 to Compound A-15 (the compound shown as (A-15) in the above [Compound [A] used in the modification step], abbreviated as "A-15" in the table), and the addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as in Example 2-1, a branched conjugated diene polymer (Sample 2-11) was obtained. The physical properties of Sample 2-11 are shown in Table 13.

[0335] (Example 2-12) Branched conjugated diene polymer (Sample 2-12) A branched conjugated diene polymer (Sample 2-12) was obtained in the same manner as in Example 2-1, except that the branching agent was changed from trimethoxy(4-vinylphenyl)silane to dimethylmethoxy(4-vinylphenyl)silane (abbreviated as "BS-2" in the table), and the addition amount thereof was changed to 0.0350 mmol / min. The physical properties of Sample 2-12 are shown in Table 14.

[0336] (Example 2-13) Branched conjugated diene polymer (Sample 2-13) A branched conjugated diene polymer (Sample 2-13) was obtained in the same manner as in Example 2-1, except that the branching agent was changed from trimethoxy(4-vinylphenyl)silane to dimethylmethoxy(4-vinylphenyl)silane (abbreviated as "BS-2" in the table), the addition amount thereof was changed to 0.0350 mmol / min, and the coupling agent was changed from Compound A-1 to Compound A-2 (the compound shown in (A-2) among the compounds [A] used in the above <modification step>. Abbreviated as "A-2" in the table). The physical properties of Sample 2-13 are shown in Table 14.

[0337] (Example 2-14) Branched conjugated diene polymer (Sample 2-14) A branched conjugated diene polymer (Sample 2-14) was obtained in the same manner as in Example 2-1, except that the branching agent was changed from trimethoxy(4-vinylphenyl)silane to dimethylmethoxy(4-vinylphenyl)silane (abbreviated as "BS-2" in the table), the addition amount thereof was changed to 0.0350 mmol / min, the coupling agent was changed from Compound A-1 to Compound A-14 (the compound shown in (A-14) among the compounds [A] used in the above <modification step>. Abbreviated as "A-14" in the table), and the addition amount thereof was changed to 0.0160 mmol / min. The physical properties of Sample 2-14 are shown in Table 14.

[0338] (Example 2-15) Branched conjugated diene polymer (Sample 2-15) The disproportionating agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene (abbreviated as "BS-3" in the table), and its addition amount was changed to 0.0120 mmol / min. Otherwise, in the same manner as in Example 2-1, a disproportionated conjugated diene polymer (Sample 2-15) was obtained. The physical properties of Sample 2-15 are shown in Table 14.

[0339] (Example 2-16) Disproportionated conjugated diene polymer (Sample 2-16) The disproportionating agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene (abbreviated as "BS-3" in the table), and its addition amount was changed to 0.0120 mmol / min. The coupling agent was changed from Compound A-1 (abbreviated as "A-1" in the table) to Compound A-2 (the compound shown in (A-2) among the compounds [A] used in the above <modification step>. Abbreviated as "A-2" in the table), and its addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as in Example 2-1, a disproportionated conjugated diene polymer (Sample 2-16) was obtained. The physical properties of Sample 2-16 are shown in Table 14.

[0340] (Example 2-17) Disproportionated conjugated diene polymer (Sample 2-17) The disproportionating agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene (abbreviated as "BS-3" in the table), and its addition amount was changed to 0.0120 mmol / min. The coupling agent was changed from Compound A-1 (abbreviated as "A-1" in the table) to Compound A-14 (the compound shown in (A-14) among the compounds [A] used in the above <modification step>. Abbreviated as "A-14" in the table), and its addition amount was changed to 0.0160 mmol / min. Otherwise, in the same manner as in Example 2-1, a disproportionated conjugated diene polymer (Sample 2-17) was obtained. The physical properties of Sample 2-17 are shown in Table 14.

[0341] (Example 2-18) Disproportionated conjugated diene polymer (Sample 2-18) The disproportionating agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-trimethoxysilylphenyl)ethylene (abbreviated as "BS-4" in the table), and its addition amount was changed to 0.0210 mmol / min. Otherwise, in the same manner as in Example 2-1, a disproportionated conjugated diene polymer (Sample 2-18) was obtained. The physical properties of Sample 2-18 are shown in Table 14.

[0342] (Example 2-19) Disproportionated conjugated diene polymer (Sample 2-19) The disproportionating agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-trimethoxysilylphenyl)ethylene (abbreviated as "BS-4" in the table), and its addition amount was changed to 0.0210 mmol / min. The coupling agent was changed from Compound A-1 (abbreviated as "A-1" in the table) to Compound A-2 (the compound shown in (A-2) among the compounds [A] used in the above <modification step>. Abbreviated as "A-2" in the table), and its addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as in Example 2-1, a disproportionated conjugated diene polymer (Sample 2-19) was obtained. The physical properties of Sample 2-19 are shown in Table 14.

[0343] (Example 2-20) Disproportionated conjugated diene polymer (Sample 2-20) The disproportionating agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-trimethoxysilylphenyl)ethylene (abbreviated as "BS-4" in the table), and the coupling agent was changed from Compound A-1 (abbreviated as "A-1" in the table) to Compound A-14 (the compound shown in (A-14) among the compounds [A] used in the above <modification step>. Abbreviated as "A-14" in the table), and its addition amount was changed to 0.0160 mmol / min. Otherwise, in the same manner as in Example 2-1, a disproportionated conjugated diene polymer (Sample 2-20) was obtained. The physical properties of Sample 2-20 are shown in Table 14.

[0344] (Example 2-21) Disproportionated conjugated diene polymer (Sample 2-21) The disproportionating agent was changed from trimethoxy(4-vinylphenyl)silane to trichloro(4-vinylphenyl)silane (abbreviated as "BS-5" in the table), and its addition amount was changed to 0.0190 mmol / min. Otherwise, in the same manner as in Example 2-1, a disproportionated conjugated diene polymer (Sample 2-21) was obtained. The physical properties of Sample 2-21 are shown in Table 14.

[0345] (Example 2-22) Disproportionated conjugated diene polymer (Sample 2-22) The disproportionating agent was changed from trimethoxy(4-vinylphenyl)silane to trichloro(4-vinylphenyl)silane (abbreviated as "BS-5" in the table), and its addition amount was changed to 0.0190 mmol / min. The coupling agent was changed from Compound A-1 (abbreviated as "A-1" in the table) to Compound A-2 (the compound shown in (A-2) among the [Compound A] used in the above <modification step>. Abbreviated as "A-2" in the table), and its addition amount was changed to 0.0360 mmol / min. Otherwise, in the same manner as in Example 2-1, a disproportionated conjugated diene polymer (Sample 2-22) was obtained. The physical properties of Sample 2-22 are shown in Table 14.

[0346] (Example 2-23) Disproportionated conjugated diene polymer (Sample 2-23) The disproportionating agent was changed from trimethoxy(4-vinylphenyl)silane to trichloro(4-vinylphenyl)silane (abbreviated as "BS-5" in the table), and its addition amount was changed to 0.0190 mmol / min. The coupling agent was changed from Compound A-1 (abbreviated as "A-1" in the table) to Compound A-14 (the compound shown in (A-14) among the [Compound A] used in the above <modification step>. Abbreviated as "A-14" in the table), and its addition amount was changed to 0.0160 mmol / min. Otherwise, in the same manner as in Example 2-1, a disproportionated conjugated diene polymer (Sample 2-23) was obtained. The physical properties of Sample 2-23 are shown in Table 14.

[0347] (Example A-1) Disproportionated conjugated diene polymer (Sample A-1) Two tank-type pressure vessels each having a stirrer and a jacket for temperature control, which are tank-type reactors with an internal volume of 10 L, a ratio of internal height (L) to diameter (D) of 4.0, an inlet at the bottom, and an outlet at the top, are connected as polymerization reactors. 1,3-Butadiene from which moisture had been removed in advance was mixed with styrene at 10.0 g / min and n-hexane at 175.2 g / min at a rate of 14.0 g / min. In a static mixer provided in the middle of the pipe for supplying this mixed solution to the inlet of the reaction group, n-butyllithium for treating residual impurities with an inert gas was added and mixed at 0.103 mmol / min, and then continuously supplied to the bottom of the reaction group. Further, 2,2-bis(2-oxolanyl)propane as a polar substance was supplied to the bottom of the first reactor at a rate of 0.081 mmol / min, and n-butyllithium as a polymerization initiator was supplied to the bottom of the first reactor at a rate of 0.143 mmol / min and vigorously mixed with a stirrer, and the internal temperature of the reactor was maintained at 67 °C. The polymer solution was continuously withdrawn from the top of the first reactor and continuously supplied to the bottom of the second reactor, and the reaction was continued at 70 °C. Further, it was supplied from the top of the second reactor to a static mixer. When the polymerization was sufficiently stabilized, while copolymerizing 1,3-butadiene and styrene, trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table), which is a branching agent, was added at a rate of 0.0190 mmol / min from the bottom of the second reaction group, and in parallel, 1,3-butadiene was added at 4.6 g / min to carry out a polymerization reaction and a branching reaction to obtain a conjugated diene-based polymer having a main-chain branched structure. Furthermore, when the polymerization reaction and the branching reaction were stabilized, a small amount of the conjugated diene-based polymer solution before adding the coupling agent was withdrawn, an antioxidant (BHT) was added so as to be 0.2 g per 100 g of the polymer, and then the solvent was removed, and the Mooney viscosity and various molecular weights at 110 °C were measured. The physical properties are shown in Table 15. Next, to the polymer solution flowing out from the outlet of the reactor, the coupling agent was changed from Compound A-1 to Compound A-9 (the compound shown in (A-9) in the above [Compound [A] used in the modification step]. Abbreviated as "A-9" in the table), and the addition amount was continuously added at 0.0360 mmol / min, and mixed using a static mixer for coupling reaction. At this time, the time until the coupling agent was added to the polymer solution flowing out from the outlet of the reactor was 4.8 minutes, the temperature was 68°C, and the difference between the temperature in the polymerization step and the temperature until the coupling agent was added was 2°C. A small amount of the conjugated diene-based polymer solution after the coupling reaction was withdrawn, an antioxidant (BHT) was added so as to be 0.2 g per 100 g of the polymer, and then the solvent was removed. The bound styrene content (physical property 6) and the microstructure of the butadiene moiety (1,2-vinyl bond content: physical property 7) were measured. The measurement results are shown in Table 15. Next, an antioxidant (BHT) was continuously added to the polymer solution subjected to the coupling reaction at 0.055 g / min (n-hexane solution) so as to be 0.2 g per 100 g of the polymer, and the coupling reaction was terminated. Simultaneously with the antioxidant, an SRAE oil (JOMO Process NC140 manufactured by JX Nippon Oil & Energy Corporation) was continuously added to 100 g of the polymer as a rubber softening agent so as to be 25.0 g, and the mixture was mixed with a static mixer. The solvent was removed by steam stripping to obtain a branched conjugated diene-based polymer (Sample A-1) having a 4-branched structure derived from a branching agent and a 4-branched star polymer structure derived from a coupling agent in a part of the main chain. The physical properties of Sample A-1 are shown in Table 15. In addition, regarding the polymer before the addition of the branching agent, the polymer after the addition of the branching agent, and the polymer in each step after the addition of the coupling agent, the structure of the polymer was identified by comparing the molecular weight by GPC measurement and the branching degree by GPC measurement with a viscometer.

[0348] (Example A-2) Branched conjugated diene-based polymer (Sample A-2) Two tank-type pressure vessels each having a stirrer and a jacket for temperature control, which were tank-type reactors with an internal volume of 10 L, a ratio of internal height (L) to diameter (D) of 4.0, an inlet at the bottom, and an outlet at the top, were connected as polymerization reactors. 1,3-butadiene that had been pre-dehydrated was mixed with styrene at a rate of 8.0 g / min and n-hexane at a rate of 175.2 g / min at a rate of 14.0 g / min. In a static mixer provided in the middle of the pipe for supplying this mixed solution to the inlet of the reaction group, n-butyllithium for inactivating residual impurities was added and mixed at a rate of 0.103 mmol / min, and then continuously supplied to the bottom of the reaction group. Further, 2,2-bis(2-oxolanyl)propane as a polar substance was supplied to the bottom of the first reactor at a rate of 0.081 mmol / min, and n-butyllithium as a polymerization initiator was supplied at a rate of 0.143 mmol / min, and vigorously mixed with a stirrer, and the internal temperature of the reactor was maintained at 67 °C. The polymer solution was continuously withdrawn from the top of the first reactor, continuously supplied to the bottom of the second reactor, and the reaction was continued at 70 °C. Further, it was supplied from the top of the second reactor to a static mixer. When the polymerization was sufficiently stable, while copolymerizing 1,3-butadiene and styrene, trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table), which is a branching agent, was added from the bottom of the second reaction group at a rate of 0.0190 mmol / min, and in parallel, 1,3-butadiene was added at 4.6 g / min and styrene was added at 2.0 g / min to carry out a polymerization reaction and a branching reaction to obtain a conjugated diene polymer having a main chain branched structure. Furthermore, when the polymerization reaction and the branching reaction were stable, a small amount of the conjugated diene polymer solution before the addition of the coupling agent was withdrawn, antioxidant (BHT) was added so as to be 0.2 g per 100 g of the polymer, and then the solvent was removed, and the Mooney viscosity at 110 °C and various molecular weights were measured. The physical properties are shown in Table 15. Next, the polymer solution flowing out from the outlet of the reactor was changed from compound A-1 to compound A-9 (the compound shown in (A-9) in the above-mentioned compound [A] used in the modification step; abbreviated as "A-9" in the table) as a coupling agent, and the addition amount was continuously added at 0.0360 mmol / min, and mixed using a static mixer for coupling reaction. At this time, the time until the coupling agent was added to the polymer solution flowing out from the outlet of the reactor was 4.8 minutes, the temperature was 68 °C, and the difference between the temperature in the polymerization step and the temperature until the coupling agent was added was 2 °C. A small amount of the conjugated diene polymer solution after the coupling reaction was taken out, and an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of the polymer. Then the solvent was removed, and the bound styrene amount (physical property 6) and the microstructure of the butadiene portion (1,2-vinyl bond amount: physical property 7) were measured. The measurement results are shown in Table 15. Next, an antioxidant (BHT) was continuously added to the polymer solution after the coupling reaction at a rate of 0.055 g / min (n-hexane solution) so that the amount was 0.2 g per 100 g of the polymer, and the coupling reaction was terminated. Simultaneously with the antioxidant, an SRAE oil (JOMO Process NC140 manufactured by JX Nippon Oil & Energy Corporation) was continuously added so that the amount was 25.0 g per 100 g of the polymer as a rubber softening agent, and the mixture was mixed with a static mixer. The solvent was removed by steam stripping to obtain a branched conjugated diene polymer (Sample A-2) having a 4-branched structure derived from the branching agent and a 4-branched star polymer structure derived from the coupling agent. The physical properties of Sample A-2 are shown in Table 15. Regarding the polymer before the addition of the branching agent, the polymer after the addition of the branching agent, and the polymer in each step after the addition of the coupling agent, the structure of the polymer was identified by comparing the molecular weight by GPC measurement and the branching degree by GPC measurement with a viscometer.

[0349] (Comparative Example 2-1) Coupled conjugated diene polymer (Sample 2-24) Two tank-type pressure vessels each having a stirrer and a jacket for temperature control were connected as polymerization reactors. Each tank-type pressure vessel had an internal volume of 10 L, a ratio of internal height (L) to diameter (D) of 4.0, an inlet at the bottom, and an outlet at the top, and was a tank-type reactor with a stirrer. 1,3 - butadiene that had been pre - dehydrated was mixed with styrene at a rate of 18.6 g / min and n - hexane at a rate of 175.2 g / min. In a static mixer installed in the middle of the pipe for supplying this mixed solution to the inlet of the reaction unit, n - butyllithium for inactivating residual impurities was added and mixed at a rate of 0.103 mmol / min, and then continuously supplied to the bottom of the reaction unit. Further, 2,2 - bis(2 - oxolanyl)propane as a polar substance was supplied to the bottom of the first reactor at a rate of 0.081 mmol / min, and n - butyllithium as a polymerization initiator was supplied to the bottom of the first reactor at a rate of 0.143 mmol / min, and vigorously mixed with a stirrer, and the temperature inside the reactor was maintained at 67 °C. The polymer solution was continuously withdrawn from the top of the first reactor and continuously supplied to the bottom of the second reactor, and the reaction was continued at 70 °C. Further, it was supplied from the top of the second reactor to a static mixer. When the polymerization was sufficiently stable, a small amount of the polymer solution before the addition of the modifier was withdrawn, antioxidant (BHT) was added so that it was 0.2 g per 100 g of the polymer, and then the solvent was removed, and the Mooney viscosity at 110 °C and various molecular weights were measured. The physical properties are shown in Table 16. Next, as a coupling agent, compound A - 1 (the compound shown in (A - 1) among the compounds [A] used in the above <modification step>. In the table, it is abbreviated as "A - 1") was continuously added to the polymer solution flowing out from the outlet of the reactor at a rate of 0.0360 mmol / min, and mixed using a static mixer for a coupling reaction. At this time, the time until the modifier was added to the polymer solution flowing out from the outlet of the reactor was 4.8 minutes, the temperature was 68 °C, and the difference between the temperature in the polymerization step and the temperature until the modifier was added was 2 °C. A small amount of the conjugated diene - based polymer solution after the coupling reaction was withdrawn, antioxidant (BHT) was added so that it was 0.2 g per 100 g of the polymer, and then the solvent was removed, and the bound styrene amount (physical property 6) and the microstructure of the butadiene part (1,2 - vinyl bond amount: physical property 7) were measured. The measurement results are shown in Table 16. Next, an antioxidant (BHT) was continuously added to the polymer solution subjected to the coupling reaction at a rate of 0.055 g / min (n - hexane solution) so that the amount was 0.2 g per 100 g of the polymer, and the coupling reaction was terminated. Simultaneously with the antioxidant, as a softening agent for rubber, SRAE oil (JOMO Process NC140 manufactured by JX Nippon Oil & Energy Corporation) was continuously added so that the amount was 25.0 g per 100 g of the polymer, and the mixture was mixed with a static mixer. The solvent was removed by steam stripping to obtain a coupling conjugated diene - based polymer (Sample 2 - 24). The physical properties of Sample 2 - 24 are shown in Table 16.

[0350] (Comparative Example 2 - 2) Coupling conjugated diene - based polymer (Sample 2 - 25) A coupling conjugated diene - based polymer (Sample 2 - 25) was obtained in the same manner as in Comparative Example 1, except that the coupling agent was changed from Compound A - 1 (abbreviated as "A - 1" in the table) to Compound A - 2 (the compound shown as (A - 2) in the above <Compound [A] used in the modification step>, abbreviated as "A - 2" in the table). The physical properties of Sample 2 - 25 are shown in Table 16.

[0351] (Comparative Example 2 - 3) Coupling conjugated diene - based polymer (Sample 2 - 26) A coupling conjugated diene - based polymer (Sample 2 - 26) was obtained in the same manner as in Comparative Example 2 - 1, except that the coupling agent was changed from Compound A - 1 (abbreviated as "A - 1" in the table) to Compound A - 3 (the compound shown as (A - 3) in the above <Compound [A] used in the modification step>, abbreviated as "A - 3" in the table), and the addition amount was changed to 0.0720 mmol / min. The physical properties of Sample 2 - 26 are shown in Table 16.

[0352] (Comparative Example 2 - 4) Coupling conjugated diene - based polymer (Sample 2 - 27) A coupling conjugated diene - based polymer (Sample 2 - 27) was obtained in the same manner as in Comparative Example 2 - 1, except that the coupling agent was changed from Compound A - 1 to Compound A - 6 (the compound shown as (A - 6) in the above <Compound [A] used in the modification step>, abbreviated as "A - 6" in the table). The physical properties of Sample 2 - 27 are shown in Table 16.

[0353] (Comparative Example 2-5) Coupling conjugated diene polymer (Sample 2-28) A coupling conjugated diene polymer (Sample 2-28) was obtained in the same manner as in Comparative Example 2-1, except that the coupling agent was changed from Compound A-1 to Compound A-8 (the compound shown as (A-8) in the above <Compound [A] used in the modification step>, abbreviated as "A-8" in the table), and the addition amount was changed to 0.0720 mmol / min. The physical properties of Sample 2-28 are shown in Table 16.

[0354] (Comparative Example 2-6) Coupling conjugated diene polymer (Sample 2-29) A coupling conjugated diene polymer (Sample 2-29) was obtained in the same manner as in Comparative Example 2-1, except that the coupling agent was changed from Compound A-1 to Compound A-9 (the compound shown as (A-9) in the above <Compound [A] used in the modification step>, abbreviated as "A-9" in the table). The physical properties of Sample 2-29 are shown in Table 16.

[0355] (Comparative Example 2-7) Coupling conjugated diene polymer (Sample 2-30) A coupling conjugated diene polymer (Sample 2-30) was obtained in the same manner as in Comparative Example 2-1, except that the coupling agent was changed from Compound A-1 to Compound A-10 (the compound shown as (A-10) in the above <Compound [A] used in the modification step>, abbreviated as "A-10" in the table). The physical properties of Sample 2-30 are shown in Table 16.

[0356] (Comparative Example 2-8) Coupling conjugated diene polymer (Sample 2-31) A coupling conjugated diene polymer (Sample 2-31) was obtained in the same manner as in Comparative Example 2-1, except that the coupling agent was changed from Compound A-1 to Compound A-12 (the compound shown as (A-12) in the above <Compound [A] used in the modification step>, abbreviated as "A-12" in the table), and the addition amount was changed to 0.0720 mmol / min. The physical properties of Sample 2-31 are shown in Table 16.

[0357] (Comparative Example 2-9) Coupled conjugated diene polymer (Sample 2-32) A coupled conjugated diene polymer (Sample 2-32) was obtained in the same manner as in Comparative Example 2-1, except that the coupling agent was changed from Compound A-1 to Compound A-13 (the compound shown as (A-13) in the above [Compound [A] used in the modification step], abbreviated as "A-13" in the table), and the addition amount thereof was changed to 0.0160 mmol / min. The physical properties of Sample 2-32 are shown in Table 16.

[0358] (Comparative Example 2-10) Coupled conjugated diene polymer (Sample 2-33) A coupled conjugated diene polymer (Sample 2-33) was obtained in the same manner as in Comparative Example 2-1, except that the coupling agent was changed from Compound A-1 to Compound A-14 (the compound shown as (A-14) in the above [Compound [A] used in the modification step], abbreviated as "A-14" in the table), and the addition amount thereof was changed to 0.0160 mmol / min. The physical properties of Sample 33 are shown in Table 16.

[0359] (Comparative Example 2-11) Coupled conjugated diene polymer (Sample 2-34) A coupled conjugated diene polymer (Sample 2-34) was obtained in the same manner as in Comparative Example 2-1, except that the coupling agent was changed from Compound A-1 to Compound A-15 (the compound shown as (A-15) in the above [Compound [A] used in the modification step], abbreviated as "A-15" in the table), and the addition amount thereof was changed to 0.0360 mmol / min. The physical properties of Sample 2-34 are shown in Table 16.

[0360] (Comparative Example B-1) Coupled conjugated diene polymer (Sample B-1) Two tank-type pressure vessels each having a stirrer and a jacket for temperature control, which are tank-type reactors with an internal volume of 10 L, a ratio of internal height (L) to diameter (D) of 4.0, an inlet at the bottom, and an outlet at the top, were connected as polymerization reactors. 1,3 - butadiene from which moisture had been removed in advance was mixed with styrene at a rate of 18.6 g / min and n - hexane at a rate of 175.2 g / min. In a static mixer provided in the middle of the pipe for supplying this mixed solution to the inlet of the reaction group, n - butyllithium for treating residual impurities to be inert was added and mixed at a rate of 0.103 mmol / min, and then continuously supplied to the bottom of the reaction group. Further, 2,2 - bis(2 - oxolanyl)propane as a polar substance was supplied to the bottom of the first reactor at a rate of 0.081 mmol / min, and n - butyllithium as a polymerization initiator was supplied at a rate of 0.143 mmol / min, and vigorously mixed with a stirrer, and the temperature inside the reactor was maintained at 67 °C. The polymer solution was continuously withdrawn from the top of the first reactor and continuously supplied to the bottom of the second reactor, and the reaction was continued at 70 °C. Further, it was supplied from the top of the second reactor to a static mixer. When the polymerization reaction became stable, a small amount of the conjugated diene - based polymer solution before the addition of the coupling agent was withdrawn, antioxidant (BHT) was added so as to be 0.2 g per 100 g of the polymer, and then the solvent was removed, and the Mooney viscosity at 110 °C and various molecular weights were measured. The physical properties are shown in Table 15. Next, trimethoxy(4 - vinylphenyl)silane (abbreviated as "BS - 1" in the table) was added to the polymer solution flowing out from the outlet of the reactor at a rate of 0.0190 mmol / min, and at the same time, tetraethoxysilane (abbreviated as "A" in the table) was continuously added at a rate of 0.0480 mmol / min, and mixed using a static mixer for coupling reaction. In Table 15, "BS - 1" of Comparative Example B - 1 was described in the column of "branching agent". However, since the "BS - 1" and "A" were added simultaneously, a main - chain branched structure could not be formed and it did not function as a branching agent. At this time, the time until the coupling agent was added to the polymer solution flowing out from the outlet of the reactor was 4.8 minutes, the temperature was 68 °C, and the difference between the temperature in the polymerization step and the temperature until the coupling agent was added was 2 °C. A small amount of the conjugated diene polymer solution after the coupling reaction was taken out, and an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of the polymer. Then the solvent was removed, and the bound styrene content (physical property 6) and the microstructure of the butadiene moiety (1,2-vinyl bond content: physical property 7) were measured. The measurement results are shown in Table 15. Next, an antioxidant (BHT) was continuously added to the polymer solution after the coupling reaction at 0.055 g / min (n-hexane solution) so that the amount was 0.2 g per 100 g of the polymer, and the coupling reaction was terminated. Simultaneously with the antioxidant, as a rubber softening agent, SRAE oil (JOMO Process NC140 manufactured by JX Nippon Mining & Energy Corporation) was continuously added so that the amount was 25.0 g per 100 g of the polymer, and the mixture was mixed with a static mixer. The solvent was removed by steam stripping to obtain a coupled conjugated diene polymer (Sample B-1). The physical properties of Sample B-1 are shown in Table 15. Regarding the polymer before the addition of the branching agent, the polymer after the addition of the branching agent, and the polymer in each step after the addition of the coupling agent, the structure of the polymer was identified by comparing the molecular weight by GPC measurement and the branching degree by GPC measurement with a viscometer.

[0361] (Comparative Example B-2) Coupled conjugated diene polymer (Sample B-2) As the coupling agent, the coupling agent represented by the following (Z-1) (abbreviated as "Z-1" in the table) was used, and the addition amount was 0.0360 mmol / min. Under the same conditions as in Comparative Example 2-1, a coupled conjugated diene polymer (Sample B-2) having no main chain branches derived from the branching agent and having a 10-branched star polymer structure derived from the coupling agent was obtained. The physical properties of Sample B-2 are shown in Table 15.

[0362]

Chemical formula

[0363]

Table 13

[0364]

Table 14

[0365]

Table 15

[0366]

Table 16

[0367] (Examples 2-24 to 2-46, Examples a-1 to 2, and Comparative Examples 2-12 to 2-22, Comparative Examples b-1 to 2) 〔Rubber Composition〕 Using Samples 2-1 to 2-34, Samples A-1 to 2, and Samples B-1 to 2 shown in Tables 13 to 16 as raw rubbers, rubber compositions containing each raw rubber were obtained according to the following formulations.

[0368] (Rubber Component) · Branched conjugated diene polymer, coupled conjugated diene polymer (Samples 2-1 to 2-34, Samples A-1 to 2, Samples B-1 to 2) : 80 parts by mass (parts by mass excluding rubber softener) · High cis polybutadiene (trade name "UBEPOL BR150" manufactured by Ube Industries, Ltd.) : 20 parts by mass

[0369] (Formulation Conditions) The addition amount of each compounding agent is shown as the number of parts by mass based on 100 parts by mass of the rubber component excluding the rubber softener. · Silica 1 (trade name "Ultrasil 7000GR" manufactured by Evonik Degussa GmbH Nitrogen adsorption specific surface area 170 m2 / g): 50.0 parts by mass · Silica 2 (trade name "Zeosil Premium 200MP" manufactured by Rhodia Nitrogen adsorption specific surface area 220 m2 / g): 25.0 parts by mass · Carbon black (product name "Seast KH (N339)" manufactured by Tokai Carbon Co., Ltd.) : 5.0 parts by mass · Silane modifier (product name "Si75", bis(triethoxysilylpropyl)disulfide manufactured by Evonik Degussa GmbH): 6.0 parts by mass · SRAE oil (product name "Process NC140" manufactured by JX Nippon Oil & Energy Corporation) : 42.0 parts by mass (Including the amount previously added as a rubber softener contained in Samples 2-1 to 2-34, Samples A-1 to 2, and Samples B-1 to 2) · Zinc oxide: 2.5 parts by mass · Stearic acid: 1.0 part by mass · Antioxidant (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 2.0 parts by mass · Sulfur: 2.2 parts by mass · Vulcanization accelerator 1 (N-cyclohexyl-2-benzothiazylsulfinamide) : 1.7 parts by mass · Vulcanization accelerator 2 (diphenylguanidine): 2.0 parts by mass · Total: 239.4 parts by mass

[0370] (Kneading method) The above materials were kneaded by the following method to obtain a rubber composition. Using a closed kneader (internal volume 0.3 L) equipped with a temperature control device, as the first-stage kneading, under the conditions of a filling rate of 65% and a rotor rotation speed of 30 to 50 rpm, raw rubber (Samples 2-1 to 2-34, Samples A-1 to 2, Samples B-1 to 2), filler (silica 1, silica 2, carbon black), silane modifier, SRAE oil, zinc oxide, and stearic acid were kneaded. At this time, the temperature of the closed mixer was controlled, and the discharge temperature was 155 to 160 °C to obtain each rubber composition (compound). Next, as the second-stage kneading, after cooling the compound obtained above to room temperature, an antioxidant was added and kneaded again to improve the dispersion of silica. Also in this case, by controlling the temperature of the mixer, the discharge temperature of the compound was adjusted to 155 to 160 °C. After cooling, as the kneading in the third stage, sulfur, vulcanization accelerators 1 and 2 were added and kneaded on an open roll set at 70 °C. After that, it was molded and vulcanized in a vulcanization press at 160 °C for 20 minutes. The rubber composition before vulcanization and the rubber composition after vulcanization were evaluated. Specifically, they were evaluated by the following methods. The results are shown in Tables 17 to 20.

[0371] 〔Evaluation of properties〕 (Evaluation 1) Mooney viscosity of the compound Using the compound obtained after the kneading in the second stage and before the kneading in the third stage as a sample, a Mooney viscometer was used. After preheating at 130 °C for 1 minute in accordance with ISO 289, the viscosity after rotating the rotor at 2 revolutions per minute for 4 minutes was measured. The results of Comparative Example 2-12 were indexed with 100. The smaller the index, the better the processability.

[0372] (Evaluation 2) Tensile strength and elongation at break In accordance with the tensile test method of JIS K6251, the tensile strength and elongation at break were measured, and the results of Comparative Example 2-12 were indexed with 100. The larger the index, the better the tensile strength and elongation at break (breaking strength).

[0373] (Evaluation 3) Abrasion resistance Using an Akron abrasion tester (manufactured by Yasuda Seiki Seisakusho), in accordance with JIS K6264-2, the abrasion amount under a load of 44.4 N and 1000 revolutions was measured, and the results of Comparative Example 2-12 were indexed with 100. The larger the index, the better the abrasion resistance.

[0374] (Evaluation 4) Viscoelastic parameters Using a viscoelastic tester "ARES" manufactured by Rheometric Scientific, viscoelastic parameters were measured in torsion mode. Each measured value was indexed with 100 based on the results for the rubber composition of Comparative Example 2-12. The tanδ measured at 0 °C, a frequency of 10 Hz, and a strain of 1% was used as an index of wet skid resistance. The larger the index, the better the wet skid resistance. Also, the tanδ measured at 50 °C, a frequency of 10 Hz, and a strain of 3% was used as an index of fuel efficiency. The smaller the index, the better the fuel efficiency. Furthermore, the elastic modulus (G’) measured at 50 °C, a frequency of 10 Hz, and a strain of 3% was used as an index of handling stability. The larger the index, the better the handling stability.

[0375]

Table 17

[0376]

Table 18

[0377]

Table 19

[0378]

Table 20

[0379] As shown in Tables 17 to 20, Examples 2-24 to 2-46 and Examples a-1 to 2 showed good processability with a low Mooney viscosity of the compound when making a vulcanizate, and were excellent in abrasion resistance, handling stability, and breaking strength when made into a vulcanizate. It was also confirmed that they were excellent in the balance between low hysteresis loss property and wet skid resistance as compared with Comparative Examples 2-12 to 2-22 and Comparative Examples b-1 to 2.

Industrial Applicability

[0380] The modified conjugated diene polymer obtained by the production method of the present invention has industrial applicability in fields such as tire treads, automotive interior and exterior parts, vibration-proof rubber, belts, footwear, foams, and various industrial product applications.

Claims

1. A polymerization step of obtaining a conjugated diene polymer having an active end by polymerizing or copolymerizing a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound using an alkali metal compound or an alkaline earth metal compound as a polymerization initiator; A branching step of introducing a branched structure by reacting a styrene derivative as a branching agent with the active end of the conjugated diene polymer; A reaction step of reacting a coupling agent with the active end of the conjugated diene polymer obtained in the branching step, and The coupling agent is represented by the following formula (a), A method for producing a branched conjugated diene polymer. 【Chemical 1】 (In formula (a), R 1 ~R 4 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R 5 ~R 6 each independently represents an alkylene group having 1 to 20 carbon atoms.) m and n are integers from 1 to 3. In formula (a), a plurality of Rs 1 ~R 6 , m, and n may be the same or different. In formula (a), X is represented by any one of the following general formulas (b) to (e).) 【Chemical Formula 2】 (In formula (b), R 7 represents a hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group may have a partially branched structure or a cyclic structure. R 8 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and in the case of the hydrocarbon group, it may have a partially branched structure or a cyclic structure.) 【Chemical 3】 (In formula (c), R 9 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and in the case of the hydrocarbon group, it may have a partially branched structure or a cyclic structure.) 【Chemical Formula 4】 (In formula (d), R 10 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and in the case of the hydrocarbon group, it may have a partially branched structure or a cyclic structure.) [Chemical Formula 5] (In formula (e), R 11 ~R 14 each independently represents an alkylene group having 1 to 20 carbon atoms. R 15 ~R 18 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, l and o each independently represent an integer of 1 to 3, and when there are a plurality of R 15 ~R 18 are each independent.)

2. The method further includes a step of adding a conjugated diene compound and / or an aromatic vinyl compound to the reaction system during and / or after the branching step. The method for producing a branched conjugated diene polymer according to Claim 1.

3. The styrene derivative is a compound represented by the following formula (1) and / or the following formula (2), The method for producing a branched conjugated diene polymer according to Claim 1 or 2. [Chemical Formula 6] 【Chemical Formula 7】 (In formulas (1) and (2), R 1 represents any one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms, and may have a branched structure in a part thereof.) X 1 , X 2 , X 3 is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen. Y 1 、 Y 2 、 Y 3 represents any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be independent of each other, the same or different. )

4. In the formula (1), R 1 is a hydrogen atom, and Y 1 is any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. The method for producing a branched conjugated diene-based polymer according to claim 3.

5. In the formula (2), Y 2 is any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom, and is a method for producing a branched conjugated diene polymer according to claim 3.

6. In the formula (1), R 1 is a hydrogen atom, and Y 1 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom. The method for producing a branched conjugated diene polymer according to claim 3.

7. In the formula (2), Y 2 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom, and Y 3 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom. The method for producing a branched conjugated diene polymer according to claim 3.

8. A polymerization step of obtaining a conjugated diene polymer having an active end by polymerizing or copolymerizing a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound using an alkali metal compound or an alkaline earth metal compound as a polymerization initiator; A branching step of introducing a branched structure by reacting a styrene derivative as a branching agent with the active end of the conjugated diene polymer; A method for producing a branched conjugated diene polymer, comprising: The styrene derivative is a compound represented by the following formula (1) and / or the following formula (2), A method for producing a branched conjugated diene polymer. 【Chemical Formula 6-1】 【Chemical Formula 7-1】 (In formula (1), R 1 is a hydrogen atom.) In formulas (1) and (2), X 1 , X 2 , X 3 is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen. In formula (1), Y 1 is an alkoxy group having 1 to 20 carbon atoms. In formula (2), Y 2 , Y 3 represents any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be independent of each other and may be the same or different.

9. A polymerization step of obtaining a conjugated diene polymer having an active end by polymerizing or copolymerizing a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound using an alkali metal compound or an alkaline earth metal compound as a polymerization initiator; A branching step of introducing a branched structure by reacting a styrene derivative as a branching agent with the active end of the conjugated diene polymer; A method for producing a branched conjugated diene polymer, comprising: The styrene derivative is a compound represented by the following formula (1) and / or the following formula (2), A method for producing a branched conjugated diene polymer. 【Chemical Formula 6-2】 【Chemical Formula 7-2】 (In formula (1), R 1 is a hydrogen atom.) In formula (1), X 1 is a single bond. In formula (2), X 2 , X 3 is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen. In formula (1), Y 1 is an alkoxy group having 1 to 20 carbon atoms. In formula (2), Y 2 , Y 3 represents any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be independent of each other and may be the same or different.

10. In the formula (2), X 2 is a single bond, Y 2 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom, X 3 is a single bond, Y 3 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom, The method for producing a branched conjugated diene polymer according to claim 3.

11. A conjugated diene polymer having a living end with a branched structure, a compound represented by the following formula (a), and a branched conjugated diene polymer which is a reaction product thereof. [Chemical Formula 8] (In formula (a), R 1 to R 4 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R 5 to R 6 each independently represents an alkylene group having 1 to 20 carbon atoms.) m and n are integers from 1 to 3. In formula (A), a plurality of R 1 ~R 6 , m, and n may be the same or different. In formula (a), X is represented by any one of the following general formulas (b) to (e). 【Chemical Formula 9】 (In formula (b), R 7 represents a hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group may have a partially branched structure or a cyclic structure. R 8 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and in the case of the hydrocarbon group, it may have a partially branched structure or a cyclic structure.) 【Chemical Formula 10】 (In formula (c), R 9 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and in the case of the hydrocarbon group, it may have a partially branched structure or a cyclic structure.) 【Chemical 11】 (In formula (d), R 10 represents a hydrocarbon group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and in the case of the hydrocarbon group, it may have a partially branched structure or a cyclic structure.) 【Chemical Formula 12】 (In formula (e), R 11 ~R 14 each independently represents an alkylene group having 1 to 20 carbon atoms. R 15 ~R 18 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, l and o each independently represent an integer of 1 to 3, and when there are a plurality of R 15 ~R 18 are each independent.)

12. OR of the compound represented by the formula (a) 1 and / or OR 3 has a branched structure, and the branched conjugated diene polymer according to claim 11.

13. A rubber component containing 10% by mass or more of the branched conjugated diene polymer according to Claim 11 or 12, and a rubber composition containing 5.0 to 150 parts by mass of a filler with respect to 100 parts by mass of the rubber component.

14. A step of obtaining a branched conjugated diene polymer by the production method according to any one of Claims 1 to 10, a step of obtaining a rubber component containing 10% by mass or more of the branched conjugated diene polymer, and a step of obtaining a rubber composition by containing 5.0 to 150 parts by mass of a filler with respect to 100 parts by mass of the rubber component. A method for producing a rubber composition, comprising:

15. A step of obtaining a rubber composition by the method for producing a rubber composition according to Claim 14, and a step of molding the rubber composition to obtain a tire. A method for producing a tire, comprising:

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