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

Abstract

To provide a production method for a modified conjugated diene-based polymer that has a high degree of branching and enables the lengths of a main chain and a side chain to be adjusted, and a modified conjugated diene-based polymer that expresses excellent processability and wear resistance.SOLUTION: A production method for a modified conjugated diene-based polymer has a polymerizing step of obtaining a conjugated diene-based polymer having an active end with an alkali metal compound or an alkaline earth metal compound used as a polymerization initiator, a branching step of introducing a branch structure by reacting a styrene derivative with the active end of the conjugated diene-based polymer, and a modifying step for reacting the active end of the conjugated diene-based polymer resulting from the branching step with a compound [M] having a group: -C(R1)=N-A1 and / or a group: -N=C(R1)-A1 (R1 is a hydrogen atom or hydrocarbyl group and A1 is a monovalent group having an alkoxysilyl group), the number of these groups being at least two in total.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a modified conjugated diene-based polymer, a modified conjugated diene-based polymer, a rubber composition, a method for producing a rubber composition, and a method for producing a tire. [Background technology]

[0002] From the viewpoint of environmental load, there has been an increasing demand for automobiles to have lower fuel consumption. In particular, there is a demand for improved fuel consumption in the materials used for the tread portion of automobile tires, which is in direct contact with the ground. In recent years, there has been a demand for the development of materials having low rolling resistance, i.e., low hysteresis loss. There is also a demand for lighter tires, which requires a reduction in the thickness of the tire tread portion and the use of a material with high abrasion resistance for the tire tread portion. On the other hand, from the viewpoint of safety, materials used in the tire tread portion are required to have excellent wet skid resistance and sufficient fracture properties for practical use.

[0003] Materials that meet the various requirements as described above include rubber materials that contain a rubber-like polymer and a reinforcing filler such as carbon black or silica. The use of rubber materials containing silica can improve the balance between low hysteresis loss (an index of fuel economy) and wet skid resistance. Also, by introducing a functional group having affinity or reactivity with silica to the molecular end of a rubber-like polymer with high mobility, the dispersibility of silica in the rubber material can be improved, and further, the mobility of the molecular end of the rubber-like polymer can be reduced by bonding with silica particles, thereby reducing hysteresis loss. On the other hand, one method for improving the abrasion resistance is to increase the molecular weight of the rubber-like polymer, but increasing the molecular weight tends to deteriorate the processability when the rubber-like polymer is kneaded with a reinforcing filler. In view of these circumstances, attempts have been made to introduce a branched structure into rubber-like polymers in order to increase the molecular weight without impairing processability.

[0004] For example, a resin composition has been proposed in the past that contains silica and a modified conjugated diene polymer obtained by reacting an alkoxysilane containing an amino group with an active terminal of a conjugated diene polymer. In addition, modified conjugated diene polymers have been proposed that have a branched structure obtained by subjecting an active terminal of a polymer to a coupling reaction with a polyfunctional silane compound (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2007 / 114203 Brochure [Patent Document 2] International Publication No. 2016 / 133154 Brochure Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the method of introducing a branched structure into a conjugated diene polymer by coupling reaction of a polymer active terminal with a polyfunctional silane compound, the degree of branching of the modified conjugated diene polymer obtained by the method is largely dependent on the number of groups capable of reacting with the polymer active terminal possessed by the polyfunctional silane compound, and does not exceed the number of reactive groups. From the viewpoint of synthesis feasibility, there is a limit to the number of reactive groups that can be imparted to one polyfunctional silane, and therefore there is a problem in that the degree of branching of the modified conjugated diene polymer obtained is also limited.

[0007] Therefore, the present invention aims to provide a method for producing a modified conjugated diene polymer that can produce a modified conjugated diene polymer having a higher degree of branching than when a branched structure is introduced into a conjugated diene polymer using only a modifier, and that allows the lengths of the main chain and side chains to be adjusted, thereby providing a high degree of freedom in polymer design, and thereby providing a modified conjugated diene polymer with excellent processability and abrasion resistance. [Means for solving the problem]

[0008] Means for Solving the Problems of the Prior Art As a result of intensive research and investigation, the present inventors have found that the above-mentioned problems of the prior art can be solved by reacting a conjugated diene-based polymer having an active terminal with a styrene derivative as a branching agent and then reacting the polymer with a specific modifying agent, thereby completing the present invention. That is, the present invention is as follows.

[0009] [1] a polymerization step of 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 to obtain a conjugated diene polymer having an active terminal; a branching step of reacting an active terminal of the conjugated diene polymer with a styrene derivative to introduce a branched structure; The active terminal of the conjugated diene polymer formed after the branching step and the group "-C(R 1 )=NA 1 " and / or the group "-N=C(R 1 )-A 1 " (However, R 1 is a hydrogen atom or a hydrocarbyl group, A 1 is a monovalent group having an alkoxysilyl group.) with a compound [M] having a total of two or more The present invention relates to a method for producing a modified conjugated diene polymer comprising the steps of: [2] The method for producing a modified conjugated diene-based polymer according to the above item [1], wherein the compound [M] is a compound represented by the following formula (A):

[0010] [ka]

[0011] (In formula (A), R 2 and R 3 are each independently a hydrocarbyl group having 1 to 20 carbon atoms; R 4 is an alkanediyl group having 1 to 20 carbon atoms, 2 is the group "*-C(R 1 )=N-" or the group "*-N=C(R 1 )-" (However, R 1 is a hydrogen atom or a hydrocarbyl group, and "*" is R 5 ) indicates that it is a bond that bonds to. R 5 is an m-valent hydrocarbyl group having 1 to 20 carbon atoms, or an m-valent group having 1 to 20 carbon atoms which has at least one atom selected from the group consisting of nitrogen atoms, oxygen atoms, and sulfur atoms and has no active hydrogen. n is an integer from 1 to 3, and m is an integer from 2 to 10. In formula (A), a plurality of R 2 , R 3 , R 4 , A 2 , n may be the same or different.)

[0012] [3] The styrene derivative is a compound represented by the following formula (1) and / or the following formula (2): A method for producing the modified conjugated diene polymer according to the above [1] or [2].

[0013] [ka]

[0014] [ka]

[0015] (In formulas (1) and (2), Q 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, which may partially have a branched structure. 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. Each may be independent and the same or different.

[0016] [4] In the formula (1), Q 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. [5] In the formula (1), Q 1 is a hydrogen atom, and Y 1 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom. [6] 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. [7] In the formula (1), Q 1 is a hydrogen atom, and Y 1 The method for producing a modified conjugated diene polymer according to the above item [3], wherein is an alkoxy group having 1 to 20 carbon atoms. [8] In the formula (1), Q 1 is a hydrogen atom, and X1 is a single bond, and Y 1 The method for producing a modified conjugated diene polymer according to the above item [3], wherein is an alkoxy group having 1 to 20 carbon atoms. [9] 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, and X 3 is a single bond, and Y 3 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom.

[10] a conjugated diene-based polymer having an active end with a branched structure; Base “-CR 1 =NA 1 " and / or the group "-N=CR 1 -A 1 " (However, R 1 is a hydrogen atom or a hydrocarbyl group, A 1 is a monovalent group having an alkoxysilyl group.) A compound [M] having a total of two or more is the reaction product of Modified conjugated diene polymer.

[11] The modified conjugated diene polymer according to the above

[10] , which is represented by the following formula (B):

[0017] [ka]

[0018] (In formula (B), R 2 is a hydrocarbyl group having 1 to 20 carbon atoms, R 6 is a hydrocarbyloxy group having 1 to 20 carbon atoms or a modified or unmodified branched conjugated diene polymer, R 4 is an alkanediyl group having 1 to 20 carbon atoms, and Z is a group represented by the following formula (C) or formula (D). R 5is an m-valent hydrocarbyl group having 1 to 20 carbon atoms, or an m-valent group having 1 to 20 carbon atoms which has at least one atom selected from the group consisting of nitrogen atoms, oxygen atoms, and sulfur atoms and has no active hydrogen. n is an integer from 1 to 3, and m is an integer from 2 to 10. In the formula, multiple R 2 , R 4 , R 6 , Z, and n may be the same or different.

[0019] [ka]

[0020] [ka]

[0021] (In formula (C) and formula (D), R 1 is a hydrogen atom or a hydrocarbyl group, and Poly is a modified or unmodified branched conjugated diene polymer. 5 )

[0022]

[12] A rubber component containing 10% by mass or more of the modified conjugated diene polymer according to

[10] or

[11] above; The rubber composition comprises 5.0 parts by mass or more and 150 parts by mass or less of a filler per 100 parts by mass of the rubber component.

[13] A step of obtaining a modified conjugated diene polymer by the production method according to any one of [1] to [9] above; obtaining a rubber component containing 10% by mass or more of the modified conjugated diene polymer; A filler is contained in an amount of 5.0 parts by mass or more and 150 parts by mass or less based on 100 parts by mass of the rubber component. to obtain a rubber composition; The method for producing a rubber composition comprising the steps of:

[14] Obtaining a rubber composition by the method for producing a rubber composition according to

[13] above; molding the rubber composition to obtain a tire; A tire manufacturing method comprising the steps of: Effect of the Invention

[0023] According to the present invention, it is possible to produce a modified conjugated diene-based polymer having a higher degree of branching than when only a modifier is used, and it is also possible to provide a production method that allows a high degree of freedom in polymer design by adjusting the lengths of the main chain and side chains, thereby making it possible to provide a modified conjugated diene-based polymer that exhibits excellent processability and abrasion resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention (hereinafter, referred to as "the present embodiment") will be described in detail. It should be noted that the following embodiment is merely an example for explaining the present invention, and the present invention is not limited to the following embodiment. The present invention can be practiced with appropriate modifications within the scope of the gist of the present invention.

[0025] [Method for producing modified conjugated diene polymer] The method for producing a modified conjugated diene polymer of the present embodiment includes the steps of: a polymerization step of 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 to obtain a conjugated diene polymer having an active terminal; a branching step of reacting an active terminal of the conjugated diene polymer with a styrene derivative as a branching agent to introduce a branched structure; The active terminal of the conjugated diene polymer formed after the branching step and the group "-C(R 1 )=NA 1 " and / or the group "-N=C(R 1 )-A 1 " (However, R 1 is a hydrogen atom or a hydrocarbyl group, A 1is a monovalent group having an alkoxysilyl group.) with a compound [M] having a total of two or more of has. The conjugated diene polymer constituting the modified conjugated diene polymer may be any one of a homopolymer of a single conjugated diene compound, a polymer or copolymer of different types of conjugated diene compounds, and a copolymer of a conjugated diene compound and an aromatic vinyl compound. According to the present embodiment, by introducing a branch point into the main chain, a modified conjugated diene-based polymer having a higher degree of branching can be produced as compared with a case in which a branched structure is introduced into a conjugated diene-based polymer using only a modifying agent, and a production method can be provided which allows a high degree of freedom in polymer design by adjusting the lengths of the main chain and side chains, thereby providing a modified conjugated diene-based polymer that exhibits excellent processability and abrasion resistance.

[0026] (polymerization process) In the polymerization step in the method for producing a modified conjugated diene polymer of the present embodiment, an alkali metal compound or an alkaline earth metal compound is used as a polymerization initiator to polymerize or copolymerize a conjugated diene compound, or a conjugated diene compound and an aromatic vinyl compound, to obtain a conjugated diene polymer having an active end. In the polymerization step, it is preferable to carry out polymerization by a propagation reaction through a living anionic polymerization reaction, whereby a conjugated diene polymer having an active terminal can be obtained.

[0027] <Polymerization initiator> As the polymerization initiator, an alkali metal compound or an alkaline earth metal compound is used. As the polymerization initiator, an organolithium compound is preferably used, and an organomonolithium compound is more preferably used. The organomonolithium compound is not limited to the following, but examples thereof include organomonolithium compounds of low molecular weight compounds and solubilized oligomeric organomonolithium compounds. In addition, the organomonolithium compound can be any of compounds having a carbon-lithium bond, a nitrogen-lithium bond, and a tin-lithium bond in terms of the bonding mode between the organic group and the lithium.

[0028] The amount of the polymerization initiator used is preferably determined depending on the targeted molecular weight of the conjugated diene polymer. The amount of a monomer such as a conjugated diene compound used relative to the amount of a polymerization initiator used relates to the degree of polymerization of a target conjugated diene polymer, i.e., tends to relate to the number average molecular weight and / or weight average molecular weight. Therefore, in order to increase the molecular weight of the conjugated diene polymer, the amount of the polymerization initiator should be adjusted to decrease, and in order to decrease the molecular weight, the amount of the polymerization initiator should be adjusted to increase.

[0029] From the viewpoint that the organomonolithium compound is used as one method for introducing nitrogen atoms into the conjugated diene polymer, it is preferably an alkyllithium compound having a substituted amino group or a dialkylaminolithium. When these are used as a polymerization initiator, a conjugated diene polymer having a nitrogen atom consisting of an amino group at the polymerization initiation terminal can be obtained.

[0030] The substituted amino group is an amino group that does not have an active hydrogen or has a structure in which the active hydrogen is protected. Examples of alkyllithium compounds having an amino group that does not have an active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium. Examples of alkyllithium compounds having an amino group with an active hydrogen protected structure include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0031] Examples of 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 hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithio-1,2,3,6-tetrahydropyridine.

[0032] These organomonolithium compounds having a substituted amino group can also be used as oligomeric organomonolithium compounds solubilized in normal hexane or cyclohexane by reacting them with a small amount of a polymerizable monomer, such as 1,3-butadiene, isoprene, or styrene.

[0033] The organomonolithium compound is preferably an alkyllithium compound from the viewpoints of industrial availability and ease of control of the polymerization reaction, in which case a conjugated diene-based polymer having an alkyl group at the polymerization initiation terminal can be obtained. Examples of the alkyl lithium compound include, but are not limited to, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, n-hexyl lithium, benzyl lithium, phenyl lithium, and stilbene lithium. As the alkyllithium compound, n-butyllithium and sec-butyllithium are preferred from the viewpoints of industrial availability and ease of control of the polymerization reaction.

[0034] These organomonolithium compounds may be used alone or in combination of two or more, and 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. Alkaline earth metal compounds include, but are not limited to, organomagnesium compounds, organocalcium compounds, and organostrontium compounds, as well as alkaline earth metal alkoxides, sulfonates, carbonates, and amides. Organomagnesium compounds include, for example, dibutylmagnesium and ethylbutylmagnesium. Other examples of organometallic compounds include organoaluminum compounds.

[0035] In the polymerization step, the polymerization reaction mode is not limited to the following, but examples thereof include a batchwise polymerization mode (also called a "batch type") and a continuous polymerization mode. In the continuous system, one or more connected reactors can be used. The continuous reactor is, for example, a tank type or a tube type equipped with an agitator. In the continuous system, preferably, the monomer, the inert solvent, and the polymerization initiator are continuously fed to the reactor, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is continuously discharged. The batch reactor may be, for example, a tank-type reactor equipped with a stirrer. In the batch reactor, preferably, a monomer, an inert solvent, and a polymerization initiator are fed, and if necessary, a monomer is added continuously or intermittently during polymerization to obtain a polymer solution in the reactor, and the polymer solution is discharged after the polymerization is completed. In the method for producing a modified conjugated diene polymer of this embodiment, in order to obtain a conjugated diene polymer having a high proportion of active ends in the polymerization step, a continuous system is preferred, which allows the polymer to be continuously discharged and subjected to the next reaction in a short time. In the continuous system, the number of reactors is not particularly limited, and one or two or more connected reactors can be used. The reactor is preferably one that can sufficiently contact the monomer and the polymerization initiator in a solution, and a tank type or a tube type with a stirrer is used. The number of reactors can be appropriately selected, but one reactor is preferred from the viewpoint of space saving of the production equipment, and two or more reactors are preferred from the viewpoint of improving productivity. When two or more reactors are used, it is more preferable to add the branching agent to the second or subsequent reactors.

[0036] The polymerization step for 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. Specific 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 consisting of mixtures thereof. By treating the impurities, that is, allenes and acetylenes, with an organometallic compound before subjecting the polymer to the polymerization reaction, a conjugated diene-based polymer having a high concentration of active ends tends to be obtained, which is preferable since a modified conjugated diene-based polymer having a high modification rate tends to be obtained.

[0037] In the polymerization step, a polar compound may be added. This allows the aromatic vinyl compound to be randomly copolymerized with the conjugated diene compound. The polar compound also tends to function as a vinylizing agent for controlling the microstructure of the conjugated diene portion. Furthermore, the polar compound also tends to be effective in promoting the polymerization reaction.

[0038] Examples of polar compounds 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-butylate, sodium tert-butylate, and sodium amylate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used alone or in combination of two or more.

[0039] The amount of the polar compound used is not particularly limited and can be selected depending on the purpose, but is preferably 0.01 moles or more and 100 moles or less per mole of the polymerization initiator. Such polar compounds (vinylating agents) can be used in an appropriate amount according to the desired vinyl bond amount as regulators for the microstructure of the conjugated diene portion of the conjugated diene polymer. Many polar compounds also have an effective randomizing effect in the copolymerization of a conjugated diene compound and an aromatic vinyl compound, and tend to be usable as agents for adjusting the distribution of the aromatic vinyl compound or the amount of styrene blocks. 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 is started with the whole amount of styrene and a part of 1,3-butadiene, and the remaining 1,3-butadiene is intermittently added during the copolymerization reaction.

[0040] The polymerization temperature in the polymerization step is preferably a temperature at which living anionic polymerization proceeds, and from the viewpoint of productivity, is more preferably 0° C. or higher and 120° C. or lower. By setting the temperature within this range, it is possible to ensure a sufficient amount of the modifying agent reacting with the active terminals after the polymerization is completed.

[0041] (Branching process) In the method for producing a modified conjugated diene polymer of the present embodiment, 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 functional group of the branching agent reacts with the active end of another polymer chain, thereby forming a branched structure in the polymer. It is also possible to form a further branched structure by polymerizing and reacting the conjugated diene polymer into which a branched structure has been introduced with a monomer and a branching agent, or, as described below, to react the conjugated diene polymer with a modifying agent having a functional group to form a modified conjugated diene polymer, or to carry out a coupling reaction to further extend the polymer chain. In this way, a branched conjugated diene polymer can be obtained by continuing the polymerization reaction of the aromatic vinyl compound while using, as a branching agent, a styrene derivative whose functional group reacts with the active terminal of the polymer.

[0042] <Branching agent> From the viewpoints of polymerization continuity and gelation prevention, the styrene derivative used as a branching agent in the branching step is preferably one in which the main skeleton is one in which only one active terminal remains at the branch site after the branching step, and further, it is preferable that the functional group constituting the styrene derivative has sufficient reactivity to react with the polymerization active terminal during the branching step. More specifically, the styrene derivative, which is the branching agent, is preferably a compound having a vinyl group on the benzene ring and a functional group that quantitatively reacts with the polymerization active terminal of living anionic polymerization. The functional group of the styrene derivative reacts with the polymerization active terminal in a one-to-one ratio, and the functional group is eliminated to form a single bond, while the vinyl group is polymerized 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 is eliminated by nucleophilic substitution reaction with the polymerization active terminal of living anionic polymerization, and examples of such groups include alkoxy groups, halogens, ester groups, formyl groups, ketone groups, amide groups, acid chloride groups, acid anhydride groups, and epoxy groups. By having the above-mentioned structure of the styrene derivative, which is a branching agent, the styrene derivative maintains its polymerization activity as styrene, and the styrene derivative is incorporated into the main chain, and another monomer is polymerized to the terminal where activity is maintained, and the polymer chain is further extended. In addition, the active terminal of another polymer chain reacts with the functional group of the incorporated styrene derivative to form a bond, resulting in a branched structure. By repeating this reaction, the number of branches in the polymer chain increases, the polymer structure becomes more complex, and the molecular weight becomes larger. From the viewpoint of polymerization continuity and controllability of polymer structure, it is also necessary that the functional group that is eliminated after reacting with the active end of another polymer chain has little inhibitory effect on polymerization. Here, "little inhibitory effect on polymerization" means little side reaction 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 of the styrene derivative must not excessively improve the polymerization activity, and must not deactivate the polymerization activity. When polymerizing a polymer by living anionic polymerization, it is important that the functional group does not have a hydrogen atom as a functional group that does not deactivate the active terminal, and is a hard base as defined based on Pearson's HASB rule, and more specifically, an alkoxy group or a halogen group can be mentioned. Among these, the structure of the styrene derivative as the branching agent used in the production method of this embodiment can be selected from the viewpoint of reactivity with the active terminal and that the eliminated functional group does not inhibit polymerization. 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 branching agent represented by the following formula (2) having a diphenylethylene skeleton as the main skeleton, from the viewpoints of suppressing chain transfer reactions, suppressing deactivation of active terminals, and preventing gelation.

[0043] [ka]

[0044] [ka]

[0045] (In formulas (1) and (2), Q 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, which may partially have a branched structure. 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. Each may be independent and the same or different.

[0046] The branching agent used in the branching step is a styrene derivative represented by the formula (1), Q 1 is 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.

[0047] In the present embodiment, the styrene derivative used as the branching agent in the branching step is, from the viewpoint of improving the degree of branching, 2is 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.

[0048] In the present embodiment, the branching agent used in the branching step is a styrene derivative represented by the formula (1), Q 1 is a hydrogen atom, and Y 1 is more preferably an alkoxy group having 1 to 20 carbon atoms or a halogen atom.

[0049] In the present embodiment, the branching agent used in the branching step is a styrene derivative represented by the formula (2), Y 2 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom, and Y 3 is more preferably an alkoxy group having 1 to 20 carbon atoms or a halogen atom.

[0050] In the present embodiment, the branching agent used in the branching step is a styrene derivative represented by the formula (1), Q 1 is a hydrogen atom, and Y 1 is more preferably an alkoxy group having 1 to 20 carbon atoms.

[0051] In the present embodiment, the branching agent used in the branching step is a styrene derivative represented by the formula (1) Q 1 is a hydrogen atom, and X 1 is a single bond, and Y 1 is even more preferably an alkoxy group having 1 to 20 carbon atoms.

[0052] In the present embodiment, the branching agent used in the branching step is a styrene derivative represented by the formula (2) X 2 is a single bond, and Y 2is an alkoxy group having 1 to 20 carbon atoms or a halogen atom, and X 3 is a single bond, and Y 3 is even more preferably an alkoxy group having 1 to 20 carbon atoms or a halogen atom.

[0053] 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, (2-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 methyl(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, phenyl)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 )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, diisoprop methoxymethyl(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, Examples of the silane include 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, and tripropoxy(4-vinylbenzyl)silane. 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 ... tripropoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)sil Trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane, trimethoxy(4-vinylbenzyl)silane, and triethoxy(4-vinylbenzyl)silane are more preferred, and trimethoxy(4-vinylphenyl)silane and triethoxy(4-vinylphenyl)silane are even more preferred.

[0054] The branching agent represented by the formula (2) is not limited to the following, but examples thereof include 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-triisopropoxysilylphenyl)ethylene, Examples of such ethylene include 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-trippropoxysilylbenzyl)ethylene, and 1,1-bis(4-tripentoxysilylbenzyl)ethylene. 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, and 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 above formulas (1) and (2), the number of branches is increased, and the effects of improving the wear resistance and processability can be obtained.

[0055] In the method for producing a modified conjugated diene polymer of the present embodiment, the timing of adding the branching agent is not particularly limited as long as it is during the polymerization step in which a conjugated diene polymer having an active end is present in the reaction system, and can be selected depending on the purpose, etc. From the viewpoint of improving the absolute molecular weight of the conjugated diene polymer and improving the coupling rate, the timing is preferably when the raw material conversion rate after addition of the polymerization initiator is 20% or more, more preferably 40% or more, even more preferably 50% or more, even more preferably 65% ​​or more, and even more preferably 75% or more. Furthermore, during or after the branching step, a monomer as a desired raw material may be further added, and the polymerization step may be continued after branching, or the above-described contents may be repeated. The monomer to be added is not particularly limited, but is preferably a conjugated diene compound and / or an aromatic vinyl compound, and in particular, when a monomer is added during the branching step, from the viewpoint of improving the modification rate by alleviating steric hindrance at the branching points of the conjugated diene polymer, the monomer is preferably 5% or more of the total amount of conjugated diene monomers used in the polymerization step, for example, the total amount of butadiene, more preferably 10% or more, even more preferably 15% or more, even more preferably 20% or more, and even more preferably 25% or more. In such a case, it is particularly preferable to add a monomer using a continuous polymerization process at the branching step, in an amount of 5% or more of the total amount of conjugated diene monomers used in the polymerization step, for example, the total amount of butadiene, from the viewpoint of improving the modification rate. The length of the main chain and side chains can be adjusted by changing the timing of adding the branching agent and the amount of monomer added, allowing for a high degree of freedom in polymer design.

[0056] The branched structure of the conjugated diene polymer having a branched structure introduced therein, which is obtained in the branching step in the method for producing a modified conjugated diene polymer of the present embodiment, preferably has 3 to 24 branches, more preferably has 4 to 20 branches, and further preferably has 5 to 18 branches. By restricting the number of branches to 24 or less, it tends to be easy to react with a functional group-containing modifier in the modification step described below to produce a modified conjugated diene polymer, or to further extend the polymer chain by a coupling reaction. In addition, by restricting the number of branches to 3 or more, the resulting polymer tends to have excellent processability and abrasion resistance.

[0057] The amount of branching agent added is not particularly limited, and can be selected depending on the purpose, etc., but from the viewpoints of improving the terminal termination reaction rate of the conjugated diene polymer, improving the coupling rate, and continuity of polymerization after branching, the amount of branching agent relative to the amount of active polymerization initiator is preferably ½ or less and 1 / 100 or more, more preferably ¼ or less and 1 / 50 or more, even more preferably ¼ 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.

[0058] Further, during and / or after the branching step, further monomers may be added and the polymerization step may be continued after branching, or further branching agent may be added after the addition of monomers, and the addition of monomers may be repeated. By adding monomers, the steric hindrance around the branch points is alleviated, which improves the continuity of the polymerization and the coupling and modification rates, thereby forming branches at desired positions while increasing the molecular weight of the polymer. The monomer to be added may be an aromatic vinyl compound such as styrene or a conjugated diene compound such as butadiene, or a mixture of these, and may be the same as or different from the type and ratio of the monomer to be polymerized initially, but from the viewpoint of continuity of polymerization, a conjugated diene compound is preferred. From the viewpoint of improving the heat resistance of the polymer, it is preferable to add an aromatic vinyl compound.

[0059] The conjugated diene polymer having a branched structure introduced therein, which is obtained in the branching step in the production method of the present embodiment, has a Mooney viscosity measured at 110° C. of preferably 10 or more and 150 or less, more preferably 15 or more and 140 or less, even more preferably 20 or more and 130 or less, and still more preferably 30 or more and 100 or less. When the Mooney viscosity is within the above range, the modified conjugated diene polymer finally obtained by the production method of the present embodiment tends to have excellent processability and abrasion resistance.

[0060] The weight average molecular weight of the conjugated diene polymer having a branched structure introduced therein, which is obtained in the branching step in the production method of the present embodiment, 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 even more preferably 200,000 or more and 900,000 or less. When the weight average molecular weight is within the above range, the modified conjugated diene polymer finally obtained by the production method of the present embodiment tends to be excellent in processability, abrasion resistance, and a balance of these properties. When producing a modified conjugated diene polymer in the modification step described below, in order to reach a weight-average molecular weight in the range of 100,000 or more and 1,000,000 or less, it is necessary to control the amount of branching agent added to be in the range of one-third or less and one-fiftieth or more of the amount of polymerization initiator in terms of molar ratio, thereby preventing the polymerization initiator from being completely consumed before the modification step while forming branches, and to make the number of functional groups of the modifier two or more. In order to reach a weight-average molecular weight in the range of 200,000 or more and 900,000 or less, it is necessary to control the amount of branching agent added to be in the range of one-third or less and one-fiftieth or more of the amount of polymerization initiator in terms of molar ratio, and to make the number of functional groups of the modifier three or more.

[0061] The modified conjugated diene polymer obtained by the production method of the present embodiment may be a polymer of a conjugated diene monomer and a branching agent, or a copolymer of a conjugated diene monomer, a branching agent, and a monomer other than these. For example, when the conjugated diene monomer is butadiene or isoprene and is polymerized with a branching agent containing an aromatic vinyl moiety, the polymer chain is a so-called polybutadiene or polyisoprene, and the branched portion contains a structure derived from aromatic vinyl. By having such a structure, it is possible to improve the linearity per polymer chain and improve the crosslinking density after vulcanization, and the effect of improving the abrasion resistance of the polymer is achieved. Therefore, it is suitable for applications such as tires, resin modification, interior and exterior parts of automobiles, anti-vibration rubber, and footwear. When the conjugated diene polymer is used for tire tread applications, a copolymer of a conjugated diene monomer, an aromatic vinyl monomer, and a branching agent is suitable, and in the copolymer for this application, the bound conjugated diene content 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. Furthermore, the amount of bound aromatic vinyl in the modified 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 bound conjugated diene amount and bound aromatic vinyl amount are within the above ranges, the balance between low hysteresis loss and wet skid resistance, abrasion resistance, and fracture properties tend to be excellent when made into a vulcanizate. The amount of bound aromatic vinyl can be measured by ultraviolet absorption of the phenyl group, and the amount of bound conjugated diene can also be calculated from the amount. Specifically, the amount can be measured according to the method described in the examples below.

[0062] In the modified 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. If the amount of vinyl bonds is within the above range, the balance between low hysteresis loss and wet skid resistance, abrasion resistance, and breaking strength tend to be excellent when made into a vulcanizate. Here, when the modified conjugated diene polymer is a copolymer of butadiene and styrene, the vinyl bond amount (1,2-bond amount) in the butadiene bond unit can be determined by the Hampton method (RR Hampton, Analytical Chemistry, 21, 923 (1949)). Specifically, it can be measured by the method described in the examples below.

[0063] Regarding the microstructure of the modified conjugated diene polymer, when the bond amounts in the modified conjugated diene polymer obtained by the production method of this embodiment are within the above-mentioned numerical ranges, and further, when the glass transition temperature of the modified conjugated diene polymer is within the range of -80°C or higher and -15°C or lower, a vulcanizate having an even better balance between low hysteresis loss and wet skid resistance tends to be obtained. The glass transition temperature is measured in accordance with ISO 22768:2006 by recording a DSC curve while increasing the temperature within a specified temperature range, and the peak top (inflection point) of the DSC differential curve is taken as the glass transition temperature.

[0064] When the modified 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 having 30 or more aromatic vinyl units linked together is small or that there is no such block. More specifically, when the modified conjugated diene polymer obtained by the production method of the present embodiment is a butadiene-styrene copolymer, the block having 30 or more aromatic vinyl units linked together is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, based on the total amount of the modified conjugated diene polymer, in a known method in which the polymer is decomposed by the Kolthoff method (the method described in I.M.Kolthoff, et al., J.Polym.Sci.1,429(1946)) and the amount of polystyrene insoluble in methanol is analyzed.

[0065] When the modified conjugated diene polymer obtained by the production method of the present embodiment is a conjugated diene-aromatic vinyl copolymer, it is preferable that the proportion of aromatic vinyl units present alone is high from the viewpoint of improving fuel saving performance. Specifically, when the modified conjugated diene polymer obtained by the production method of the present embodiment is a butadiene-styrene copolymer, when the modified conjugated diene polymer is decomposed by an ozonolysis method known as the Tanaka et al. method (Polymer, 22, 1721 (1981)) and the styrene chain distribution is analyzed by GPC, it is preferable that the amount of isolated styrene is 40 mass% or more relative to the total bound styrene amount, and the amount of chain styrene structures having 8 or more styrene chains is 5.0 mass% or less. In this case, the resulting vulcanized rubber tends to have excellent performance, particularly low hysteresis loss.

[0066] (Denaturation process) In the method for producing a modified conjugated diene polymer of the present embodiment, a modification step is carried out in which a predetermined compound [M] is reacted with the active terminal of the conjugated diene polymer into which a branched structure has been introduced, which is obtained through the above-mentioned polymerization step and branching step. The compound [M] is a compound having the group "-CR 1 =NA 1 " and / or the group "-N=C(R 1 )-A 1 ". Hereinafter, these groups are also referred to as "specific imino groups". However, R 1 is a hydrogen atom or a hydrocarbyl group, A 1 is a monovalent group having an alkoxysilyl group. By this modification step, a modified conjugated diene polymer having a large number of branches in the polymer chain and modified with a group that interacts with silica can be obtained.

[0067] In certain imino groups, R 1 Examples of the hydrocarbyl group include an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. A 1As long as it has an alkoxysilyl group, the remaining structure is not particularly limited, but it is preferable that it is a group further having a methylene group or a polymethylene group, and it is more preferable that it has a methylene group or a polymethylene group and an alkoxysilyl group, and that the methylene group or the polymethylene group is bonded to a nitrogen atom or a carbon atom that constitutes a carbon-nitrogen double bond. The number of specific imino groups contained in the compound [M] may be 2 or more, and is preferably 2 to 6. 1 , A 1 may be the same or different.

[0068] As the compound [M], a compound represented by the following formula (A) is particularly preferable.

[0069] [ka]

[0070] (In formula (A), R 2 and R 3 are each independently a hydrocarbyl group having 1 to 20 carbon atoms; R 4 is an alkanediyl group having 1 to 20 carbon atoms, 2 is the group "*-C(R 1 )=N-" or the group "*-N=C(R 1 )-" (However, R 1 is a hydrogen atom or a hydrocarbyl group, and "*" is R 5 ) indicates that it is a bond that bonds to. R 5 is an m-valent hydrocarbyl group having 1 to 20 carbon atoms, or an m-valent group having 1 to 20 carbon atoms which has at least one atom selected from the group consisting of nitrogen atoms, oxygen atoms, and sulfur atoms and has no active hydrogen. n is an integer from 1 to 3, and m is an integer from 2 to 10. In formula (A), a plurality of R 2 , R 3 , R 4 , A 2 , n may be the same or different.)

[0071] In the above formula (A), R 2 , R 3 Examples of the hydrocarbyl group having 1 to 20 carbon atoms include an alkyl group having 1 to 20 carbon atoms, an allyl group, a cycloalkyl group having 3 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. R 4 R is an alkanediyl group having 1 to 20 carbon atoms, and examples thereof include a cycloalkylene group having 3 to 20 carbon atoms and an arylene group having 6 to 20 carbon atoms. 4 is preferably linear.

[0072] A 2 R has 1 With regard to n, the above explanation of the “specific imino group” applies. n is preferably 2 or 3, and more preferably 3, from the viewpoint of a high effect of improving silica dispersibility. R 5 Examples of the m-valent hydrocarbyl group include groups in which m hydrogen atoms have been removed from a chain hydrocarbon having 1 to 20 carbon atoms, an alicyclic hydrocarbon having 3 to 20 carbon atoms, or an aromatic hydrocarbon having 6 to 20 carbon atoms. From the viewpoint of a high effect of improving the abrasion resistance of the resulting vulcanized rubber, a group in which m hydrogen atoms have been removed from a ring portion of an aromatic hydrocarbon (aromatic ring group) is preferred. Examples of the aromatic hydrocarbon include a ring structure represented by the following formula (A-2) and a polycyclic structure (e.g., a biphenyl group) in which two or more of the ring structures are linked together.

[0073] [ka]

[0074] (In formula (A-2), r is an integer of 0 to 5.)

[0075] In the formula (A), R 5When is an m-valent group having 1 to 20 carbon atoms having at least one atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom and having no active hydrogen, preferred specific examples include an m-valent heterocyclic group, an m-valent group having a tertiary amine structure, and the like. The heterocyclic group is preferably a conjugated system, and examples thereof include a monocyclic or fused ring such as pyridine, pyrimidine, pyrazine, quinoline, naphthalidine, furan, or thiophene, or a group in which m hydrogen atoms have been removed from a ring portion of a structure in which a plurality of such monocyclic or fused rings are linked together. m is an integer from 2 to 10. m is preferably from 2 to 6 from the viewpoint of processability of the rubber composition. In this specification, the term "active hydrogen" refers to a hydrogen atom bonded to an atom other than a carbon atom, and preferably refers to one having a bond energy lower than that of the carbon-hydrogen bond of polymethylene.

[0076] The compound [M] used in the modification step is not limited to the following, but examples thereof include compounds represented by each of the following formulae (M-1) to (M-23). The compound [M] may be used alone or in combination of two or more kinds. In addition, R in formula (M-11) 7 represents a hydrogen atom or an alkyl group. Compounds [M] of formulae (M-1) to (M-23) shown below are also used in the examples and comparative examples described later.

[0077] <Compound [M] used in the modification step: Formula (M-1) to Formula (M-23)>

[0078] [ka]

[0079] [ka]

[0080] [ka]

[0081] [ka]

[0082] In the formulas (M-1) to (M-23), Et is an ethyl group, and Me is a methyl group.

[0083] The compound [M] can be synthesized by appropriately combining standard methods in organic chemistry. For example, a method for obtaining the compound represented by the above formula (A) includes the following steps: (i) combining an alkoxysilyl group and R 4 and a monofunctional amine compound having R 5 (ii) a method of dehydrating and condensing a polyfunctional aldehyde compound having the formula (e.g., terephthalaldehyde, isophthalaldehyde, phthaldialdehyde, 2,4-pyridinedicarboxaldehyde, etc.) represented by the formula R 5 and a polyfunctional amine compound (e.g., tris(2-aminoethyl)amine, N,N'-bis(2-aminoethyl)methylamine, etc.) having an alkoxysilyl group and R 4 and a method of dehydrating and condensing a monofunctional hydroxyl group-containing compound having the formula (e.g., 4-(triethoxysilyl)butanal, etc.). These synthesis reactions are preferably carried out in a suitable organic solvent, and, if necessary, in the presence of a suitable catalyst. However, the method for synthesizing the compound [M] is not limited to the above method.

[0084] The reaction between the conjugated diene polymer having an active end obtained in the branching step and the compound [M] can be carried out, for example, as a solution reaction. The proportion of the compound [M] used (the total amount when two or more kinds are used) is preferably 0.01 mol or more, more preferably 0.05 mol or more, per mol of the metal atom involved in the polymerization of the polymerization initiator, from the viewpoint of sufficiently proceeding the modification reaction. Also, the upper limit is preferably less than 2.0 mol, more preferably less than 1.5 mol, per mol of the metal atom involved in the polymerization of the polymerization initiator, in order to avoid excessive addition.

[0085] The temperature of the modification reaction is usually the same as that of the polymerization reaction, and is preferably -20°C to 150°C, and more preferably 0 to 120°C. If the reaction temperature is low, the viscosity of the polymer after modification tends to increase, and if the reaction temperature is high, the polymerization active terminals are easily deactivated. The reaction time is preferably 1 minute to 5 hours, and more preferably 2 minutes to 1 hour.

[0086] When reacting the conjugated diene polymer having an active end obtained in the branching step with the compound [M], other modifiers or coupling agents may be used together with the compound [M]. The other modifier or coupling agent is not particularly limited as long as it is a compound capable of reacting with the active terminal of the conjugated diene polymer obtained by the above-mentioned polymerization step and branching step, and a compound known as a modifier or coupling agent for a conjugated diene polymer can be used. When other modifiers or coupling agents are used, the proportion of them used is preferably 10 mol % or less, and more preferably 5 mol % or less.

[0087] The branched structure of the modified conjugated diene polymer obtained by the production method of this embodiment through the above-mentioned polymerization step, branching step, and modification step is preferably 8 to 36 branches, more preferably 10 to 24 branches, and even more preferably 12 to 22 branches. The total number of branching points in the modified conjugated diene polymer obtained by the production method of this embodiment is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and even more preferably 5 or more. When the branched structure and the total number of branching points are within the above ranges, the processability, fuel economy, and abrasion resistance tend to be excellent. When the branched structure of the modified conjugated diene polymer has 8 to 36 branches, in order to construct one having a total of 2 to 15 branching points, it is necessary that the molar ratio of the branching agent is 1 / 2 or less and 1 / 100 or more of the polymerization initiator, and that the functional number of the modifier is 3 or more. In order to construct a branched structure having 8 to 36 branches and a total number of branching points of 3 to 12, it is preferable to use a branching agent having a molar ratio of 1 / 3 or less and 1 / 50 or more of the polymerization initiator and a modifying agent having 4 or more functional groups. In order to construct a branched structure having 10 to 24 branches and a total number of branching points of 4 to 10, it is preferable to use a branching agent having a molar ratio of 1 / 6 or less and 1 / 25 or more of the polymerization initiator and a modifying agent having 5 or more functional groups. In order to construct a branched structure having 12 to 20 branches and a total number of branching points of 5 to 9, it is preferable to use a branching agent having a molar ratio of 1 / 8 or less and 1 / 12 or more of that of the polymerization initiator and a modifying agent having 6 or more functional groups.

[0088] (Modified conjugated diene polymer) The modified conjugated diene polymer of the present embodiment comprises a conjugated diene polymer having an active terminal with a branched structure and a group "-CR 1 =NA 1 " and / or the group "-N=CR 1 -A 1 " (However, R 1 is a hydrogen atom or a hydrocarbyl group, A 1 is a monovalent group having an alkoxysilyl group.) It is a reaction product with a compound [M] having a total of two or more.

[0089] The modified conjugated diene polymer of the present embodiment is preferably represented by the following formula (B).

[0090] [ka]

[0091] (In formula (B), R 2 is a hydrocarbyl group having 1 to 20 carbon atoms, R 6 is a hydrocarbyloxy group having 1 to 20 carbon atoms or a modified or unmodified branched conjugated diene polymer, R 4 is an alkanediyl group having 1 to 20 carbon atoms, and Z is a group represented by the following formula (C) or formula (D). R 5 is an m-valent hydrocarbyl group having 1 to 20 carbon atoms, or an m-valent group having 1 to 20 carbon atoms which has at least one atom selected from the group consisting of nitrogen atoms, oxygen atoms, and sulfur atoms and has no active hydrogen. n is an integer from 1 to 3, and m is an integer from 2 to 10. In the formula, multiple R 2 , R 4 , R 6 , Z, and n may be the same or different.

[0092] [ka]

[0093] [ka]

[0094] (In formula (C) and formula (D), R 1 is a hydrogen atom or a hydrocarbyl group, and Poly is a modified or unmodified branched conjugated diene-based polymer. "*" is R 5 )

[0095] In the above formula (B), formula (C) and formula (D), R 1 , R 2 , R 4 and R 5 The explanation for formula (A) above applies to this. R 6 The hydrocarbyloxy group is preferably an ethoxy group or a methoxy group. R 6 The conjugated diene polymer chain in formula (C) and formula (D) has a structure corresponding to the conjugated diene polymer having an active end obtained in the polymerization step. These conjugated diene polymer chains may have a functional group at the end that interacts with silica.

[0096] (Condensation modification process) In the method for producing a modified conjugated diene polymer of the present embodiment, a condensation modification step of carrying out a condensation reaction in the presence of a condensation promoter may be carried out after or before the above-mentioned modification step.

[0097] (Hydrogenation process) In the method for producing a modified conjugated diene polymer of the present embodiment, a hydrogenation step of hydrogenating the conjugated diene portion may be carried out. The method for hydrogenating the conjugated diene portion of the conjugated diene polymer is not particularly limited, and any known method can be used. A suitable hydrogenation method is to blow gaseous hydrogen into a polymer solution in the presence of a catalyst. The catalyst is not particularly limited, but examples thereof include heterogeneous catalysts such as catalysts in which a precious metal is supported on a porous inorganic material; catalysts in which a salt of nickel, cobalt, or the like is solubilized and reacted with an organoaluminum, and homogeneous catalysts such as catalysts using metallocenes such as titanocene. Among these, titanocene catalysts are preferred from the viewpoint of being able to select mild hydrogenation conditions. Hydrogenation of aromatic groups can also be carried out by using a supported catalyst of a precious metal.

[0098] Examples of the hydrogenation catalyst include, but are not limited to, (1) supported heterogeneous hydrogenation catalysts in which metals such as Ni, Pt, Pd, Ru, etc. are supported on carbon, silica, alumina, diatomaceous earth, etc., (2) so-called Ziegler-type hydrogenation catalysts that use transition metal salts such as organic acid salts or acetylacetone salts of Ni, Co, Fe, Cr, etc. and reducing agents such as organoaluminum, and (3) so-called organometallic complexes such as organometallic compounds of Ti, Ru, Rh, Zr, etc. Furthermore, examples of the hydrogenation catalyst include, but are not limited to, known hydrogenation catalysts described in JP-B-42-8704, JP-B-43-6636, JP-B-63-4841, JP-B-1-37970, JP-B-1-53851, JP-B-2-9041, and JP-A-8-109219. Preferred hydrogenation catalysts include a reaction mixture of a titanocene compound and a reducing organometallic compound.

[0099] (Deactivator and neutralizer addition process) In the method for producing a modified conjugated diene polymer of the present embodiment, after the above-mentioned modification step, a deactivator, a neutralizer, and the like may be added to the polymer solution, if necessary. The quenching agent is not limited to the following, but examples thereof include water; alcohols such as methanol, ethanol, isopropanol, and the like; and the like. Examples of neutralizing agents include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture having 9 to 11 carbon atoms, with the majority having 10 carbon atoms); aqueous solutions of inorganic acids, and carbon dioxide gas.

[0100] (rubber stabilizer addition process) In the method for producing the modified conjugated diene polymer of the present embodiment, it is preferable to add a rubber stabilizer from the viewpoint of preventing gel formation after polymerization and improving stability during processing. The rubber stabilizer is not limited to the following ones, 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-butylphenol) propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol are preferred.

[0101] (rubber softener addition process) In the method for producing the modified conjugated diene polymer of the present embodiment, from the viewpoint of further improving the productivity of the modified conjugated diene polymer and the processability when a filler or the like is blended to form a resin composition, a rubber softener can be added as necessary. The rubber softener is not particularly limited, but examples thereof include extender oil, liquid rubber, and resin. The method of adding a rubber softener to a modified conjugated diene polymer is not limited to the following, but a preferred method is to add a rubber softener to a modified conjugated diene polymer solution, mix, and remove the solvent from the resulting polymer solution containing the rubber softener.

[0102] Examples of preferred extender oils include aromatic oils, naphthenic oils, and paraffinic oils. Among these, aromatic substitute oils having a polycyclic aromatic (PCA) content of 3% by mass or less according to the IP346 method are preferred from the viewpoints of environmental safety, oil bleeding prevention, and wet grip properties. Examples of aromatic substitute oils include TDAE (Treated Distillate Aromatic Extracts), MES (Mild Extraction Solvate), and RAE (Residual Aromatic Extracts) as shown in Kautschuk Gummi Kunststoffe 52(12)799(1999). Preferred liquid rubbers include, but are not limited to, liquid polybutadiene, liquid styrene-butadiene rubber, and the like. The effects of adding liquid rubber include the ability to improve the processability of a resin composition containing the modified conjugated diene polymer and a filler, etc., and the ability to shift the glass transition temperature of the resin composition to a lower temperature, which tends to improve the abrasion resistance, low hysteresis loss, and low-temperature properties of the vulcanized product. Resins as rubber softeners include, but are not limited to, aromatic petroleum resins, coumarone-indene resins, terpene resins, rosin derivatives (including paulownia oil resins), tall oil, tall oil derivatives, 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, monoolefin oligomers, diolefin oligomers, aromatic hydrocarbon resins, aromatic petroleum resins, hydrogenated aromatic hydrocarbon resins, cyclic aliphatic hydrocarbon resins, hydrogenated hydrocarbon resins, hydrocarbon resins, hydrogenated paulownia oil resins, hydrogenated oil resins, esters of hydrogenated oil resins with monofunctional or polyfunctional alcohols, etc. 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. The effects of adding a resin as a rubber softener include the following: when a resin composition is prepared by blending the modified conjugated diene polymer with a filler or the like, the processability can be improved; when a vulcanizate is prepared, the breaking strength tends to be improved; and, by shifting the glass transition temperature of the resin composition to the higher temperature side, the wet skid resistance tends to be improved.

[0103] The amount of the rubber softener, such as an extender oil, liquid rubber, or resin, added 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, and even more preferably 10 parts by mass or more and 37.5 parts by mass or less, relative to 100 parts by mass of the modified conjugated diene-based polymer obtained by the production method of the present embodiment. When the rubber softener is added within the above range, the processability of a resin composition containing the modified conjugated diene polymer obtained by the production method of the present embodiment and a filler or the like is improved, and the breaking strength and abrasion resistance of a vulcanizate tend to be improved.

[0104] (Desolvation process) In the method for producing the modified conjugated diene polymer of the present embodiment, a known method can be used as a method for obtaining the obtained modified conjugated diene polymer from the polymer solution. The method is not particularly limited, but examples thereof include a method of separating the solvent by steam stripping or the like, filtering the polymer, and further dehydrating and drying it to obtain the polymer, a method of concentrating in a flashing tank and further devolatilizing with a vent extruder or the like, and a method of directly devolatilizing with a drum dryer or the like.

[0105] [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 modified conjugated diene-based polymer produced by the production method of the present embodiment described above, and 5.0 parts by mass or more and 150 parts by mass or less of a filler per 100 parts by mass of the rubber component. The method for producing the rubber composition of the present embodiment includes the steps of obtaining a modified conjugated diene polymer by the above-described production method, obtaining a rubber component containing 10% by mass or more of the modified conjugated diene polymer, and incorporating 5.0 parts by mass or more and 150 parts by mass or less of a filler per 100 parts by mass of the rubber component. Furthermore, it is preferable for the rubber component to contain 10% by mass of the modified conjugated diene polymer obtained by the production method of this embodiment from the viewpoints of improving fuel economy performance, processability, and abrasion resistance.

[0106] The filler preferably includes a silica-based inorganic filler. By dispersing a silica-based inorganic filler as a filler, the rubber composition tends to have excellent processability when vulcanized, and the vulcanized product tends to have an excellent balance between abrasion resistance, breaking strength, and low hysteresis loss and wet skid resistance. The rubber composition preferably contains a silica-based inorganic filler even when it is used for vulcanized rubber applications such as automobile parts such as tires and anti-vibration rubbers, and shoes.

[0107] The rubber composition of the present embodiment is obtained by mixing a rubber component containing 10% by mass or more of the modified conjugated diene-based polymer obtained by the above-mentioned production method with the filler. The rubber component may contain a rubber-like polymer (hereinafter simply referred to as "rubber-like polymer") other than the above-mentioned modified conjugated diene-based 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 others include non-diene polymers and natural rubber.

[0108] Examples of rubber-like polymers include, but are not limited to, styrene-based elastomers such as butadiene rubber or hydrogenated products thereof, isoprene rubber or hydrogenated products thereof, styrene-butadiene rubber or hydrogenated products thereof, styrene-butadiene block copolymer or hydrogenated products thereof, and styrene-isoprene block copolymer or hydrogenated products thereof, and acrylonitrile-butadiene rubber or hydrogenated products thereof.

[0109] Examples of non-diene polymers include, but are not limited to, olefin 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-acrylate-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber.

[0110] Examples of natural rubber include, but are not limited to, smoked sheets such as RSS3 to 5, SMR, and epoxidized natural rubber.

[0111] The various rubber-like polymers described above may be modified rubbers to which a polar functional group such as a hydroxyl group, an amino group, etc. When the rubber composition of the present embodiment is used as a tire material, the rubber-like polymers that are preferably used are butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber.

[0112] From the viewpoint of the balance between various performances and processing characteristics of the resin composition, the weight average molecular weight of the rubber-like polymer is preferably from 2000 to 2,000,000, and more preferably from 5000 to 1,500,000. Also, a low molecular weight rubber-like polymer, so-called liquid rubber, can be used. These rubber-like polymers may be used alone or in combination of two or more.

[0113] When a rubber composition using the modified conjugated diene polymer obtained by the manufacturing method of this embodiment is used as a rubber composition containing the above-mentioned rubbery polymer, the content ratio (mass ratio) of the above-mentioned modified conjugated diene polymer to the rubbery polymer (the above-mentioned modified conjugated diene polymer / 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. Therefore, the rubber component contains the above-mentioned modified conjugated diene polymer in an amount of preferably 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, based on the total amount (100% by mass) of the rubber component.

[0114] When the content ratio of (modified conjugated diene polymer / rubber-like polymer) is within the above range, the vulcanizate tends to have excellent abrasion resistance and fracture strength, and also tends to have a good balance between low hysteresis loss and wet skid resistance.

[0115] The filler contained in the rubber composition of the present embodiment is not limited to the following, but examples thereof include, in addition to the silica-based inorganic filler, carbon black, metal oxides, and metal hydroxides. Among these, silica-based inorganic fillers are preferred. The fillers 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 or less, 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, per 100 parts by mass of the rubber component containing the modified conjugated diene-based polymer described above. In the rubber composition, the content of the filler is 5.0 parts by mass or more per 100 parts by mass of the rubber component from the viewpoint of expressing the effect of adding the filler, and is 150 parts by mass or less per 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.

[0116] The silica-based inorganic filler is not particularly limited and may be any known one, but solid particles containing SiO2 or Si3Al as a structural unit are preferred, and solid particles containing SiO2 or Si3Al as a main component of the structural 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.

[0117] Examples of silica-based inorganic fillers include, but are not limited to, inorganic fibrous substances such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, glass fiber, etc. Other examples include silica-based inorganic fillers whose surfaces have been hydrophobized, and mixtures of silica-based inorganic fillers and inorganic fillers other than silica-based fillers. Among these, silica and glass fiber are preferred from the viewpoints of strength, abrasion resistance, and the like, 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 effect of improving fracture strength and wet skid resistance.

[0118] From the viewpoint of obtaining practically satisfactory abrasion resistance and breaking strength in a rubber composition, the nitrogen adsorption specific surface area of ​​the silica-based inorganic filler determined by the BET adsorption method is 100 m 2 / g or more 300m 2 / g or less, and 2 / g or more 250m 2 It is more preferable that the molecular weight is not more than 1 / g. If necessary, a relatively small specific surface area (e.g., a specific surface area of ​​200 m 2 / g) and silica-based inorganic fillers with a relatively large specific surface area (e.g., 200 m 2 / g or more) in combination with a silica-based inorganic filler. In particular, those with a relatively large specific surface area (e.g., 200 m 2 In the case where a silica-based inorganic filler (having a silica content of 100% or more per 1000 g / g or more) is used, the rubber composition containing the modified conjugated diene polymer described above improves the dispersibility of silica, and is particularly effective in improving abrasion resistance, and tends to achieve a high level of balance between good fracture strength and low hysteresis loss.

[0119] 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 more, more preferably 20 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of the rubber component containing the modified conjugated diene polymer obtained by the production method of this embodiment. The content of the silica-based inorganic filler in the rubber composition is preferably 5.0 parts by mass or more per 100 parts by mass of the rubber component from the viewpoint of exhibiting the effect of adding the silica-based inorganic filler, and is preferably 150 parts by mass or less per 100 parts by mass of the rubber component from the viewpoint of sufficiently dispersing the silica-based inorganic filler and making the processability and mechanical strength of the rubber composition practically sufficient.

[0120] The carbon black is not limited to the following, but examples thereof include carbon blacks of various classes such as SRF, FEF, HAF, ISAF, and SAF. Among these, carbon blacks 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 preferred.

[0121] In the rubber composition, the content of carbon black is preferably 0.5 parts 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 even more preferably 5.0 parts by mass or more and 50 parts by mass or less, per 100 parts by mass of the rubber component containing the modified 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 parts by mass or more per 100 parts by mass of the rubber component from the viewpoint of expressing performance required for applications such as tires, such as dry grip performance and electrical conductivity, and is preferably 100 parts by mass or less per 100 parts by mass from the viewpoint of dispersibility.

[0122] Metal oxide refers to solid particles whose main component is a structural unit represented by the chemical formula MxOy (M represents a metal atom, and x and y each independently represent an integer of 1 to 6).

[0123] Examples of metal oxides include, but are not limited to, alumina, titanium oxide, magnesium oxide, and zinc oxide.

[0124] Examples of metal hydroxides include, but are not limited to, aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0125] In the method for producing the rubber composition of the present embodiment, a silane modifier may be added. The silane modifier has a function of strengthening the interaction between the rubber component and the inorganic filler, and has a group that has affinity or binding properties for each of the rubber component and the silica-based inorganic filler, and is preferably a compound that has a sulfur bond portion and an alkoxysilyl group or a silanol group portion in one molecule. Examples of such compounds include, but are not limited to, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide.

[0126] In the rubber composition, the content of the silane modifier is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, and even more preferably 1.0 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the inorganic filler. When the content of the silane modifier is within the above range, the above-mentioned effect of the addition of the silane modifier tends to be more remarkable.

[0127] The rubber composition of the present embodiment may contain a rubber softener from the viewpoint of improving its processability. The amount of rubber softener added is expressed as the total amount including the amount of rubber softener already contained in the modified conjugated diene polymer or other rubber-like polymers, and the amount of rubber softener added when forming a rubber composition, per 100 parts by mass of the rubber component containing the modified conjugated diene polymer obtained by the manufacturing method of the present embodiment described above. As the rubber softener, mineral oil or liquid or low molecular weight synthetic softener is preferable. Mineral oil-based rubber softeners known as process oils or extender oils, which are used to soften rubber, increase its volume, and improve its processability, are mixtures of aromatic rings, naphthenic rings, and paraffin chains; those in which the carbon number of paraffin chains accounts for 50% or more of the total carbon are called paraffinic; those in which the carbon number of naphthenic rings accounts for 30% to 45% of the total carbon are called naphthenic; and those in which the aromatic carbon number accounts for more than 30% of the total carbon are called aromatic. When the modified conjugated diene polymer of the present embodiment is a copolymer of a conjugated diene compound and a vinyl aromatic compound, it is preferable to use a rubber softener having an appropriate aromatic content, since it tends to have good compatibility with the copolymer. In the rubber composition, the content of the rubber softener is preferably 0 to 100 parts by mass, more preferably 10 to 90 parts by mass, and even more preferably 30 to 90 parts by mass, per 100 parts by mass of the rubber component. By making the content of the rubber softener 100 parts by mass or less per 100 parts by mass of the rubber component, bleeding out is suppressed and stickiness of the surface of the rubber composition tends to be suppressed.

[0128] The method for mixing the modified conjugated diene polymer obtained by the production method of the present embodiment with various additives such as other rubber-like polymers, silica-based inorganic fillers, carbon black and other fillers, silane modifiers, and rubber softeners is not limited to the following, but examples thereof include a melt-kneading method using a general mixer such as an open roll, a Banbury mixer, a kneader, a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, and a method in which the components are dissolved and mixed and then the solvent is removed by heating. Among these, the melt kneading method using a roll, a Banbury mixer, a kneader, or an extruder is preferred from the viewpoints of productivity and good kneading properties. In addition, either a method of kneading the rubber component, other fillers, silane modifier, and additives at once or a method of mixing them in several batches can be applied.

[0129] The rubber composition of the present embodiment may be a vulcanized composition that has been subjected to a vulcanization treatment with a vulcanizing agent. Examples of the vulcanizing agent include, but are not limited to, radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds. Examples of the sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, and polymeric polysulfur compounds. In the rubber composition of the present embodiment, the content of the vulcanizing agent is preferably 0.01 parts by mass to 20 parts by mass, more preferably 0.1 parts by mass to 15 parts by mass, 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 to 200°C, more preferably 140°C to 180°C.

[0130] In vulcanization, a vulcanization accelerator may be used as necessary. As the vulcanization accelerator, a conventionally known material may be used, and examples thereof include, but are not limited to, sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators. As the vulcanization aid, examples thereof include, but are not limited to, zinc oxide and stearic acid. The content of the vulcanization accelerator is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the rubber component.

[0131] In the rubber composition of the present embodiment, various additives such as softeners and fillers other than those described above, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants may be used within the scope that does not impair the object of the present embodiment. As the other softening agents, known softening agents can be used. The other fillers are not particularly limited, but include, for example, calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. As the heat resistance stabilizer, antistatic agent, weather resistance stabilizer, antiaging agent, colorant, and lubricant, known materials can be used.

[0132] [Tire and tire manufacturing method] 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 modified conjugated diene polymer by the production method of the present embodiment, a step of obtaining a rubber composition containing the modified conjugated diene polymer, and a step of molding the rubber composition. The rubber composition containing the modified conjugated diene polymer obtained by the production method of the present embodiment described above is suitably used as a rubber composition for tires.

[0133] The rubber composition for tires is not limited to the following, but can be used in various tire parts such as treads, carcasses, sidewalls, beads, etc. of various tires such as fuel-efficient tires, all-season tires, high-performance tires, studless tires, etc. In particular, the rubber composition for tires has an excellent balance between abrasion resistance, breaking strength, low hysteresis loss, and wet skid resistance when vulcanized, and is therefore suitably used for the treads of fuel-efficient tires and high-performance tires. EXAMPLES

[0134] Hereinafter, the present embodiment will be described in more detail with reference to specific examples and comparative examples, but the present embodiment is not limited in any way to the following examples and comparative examples. Various physical properties in the examples and comparative examples were measured by the methods shown below. Hereinafter, a conjugated diene polymer that is coupled with a nitrogen atom-containing modifier made of a specific compound will be referred to as a "modified conjugated diene polymer" or a "coupled conjugated diene polymer". Moreover, an unmodified conjugated diene polymer will be referred to as an "unmodified conjugated diene polymer" or a "conjugated diene polymer".

[0135] (Physical property 1) Polymer Mooney viscosity An unmodified conjugated diene polymer or a conjugated diene polymer coupled with a nitrogen atom-containing modifier (hereinafter also referred to as a "modified conjugated diene polymer") was used as a sample, and the Mooney viscosity was measured using a Mooney viscometer (manufactured by Ueshima Seisakusho Co., Ltd., product name "VR1132") using an L-type rotor in accordance with ISO 289. The measurement temperature was 110° C. when an unmodified conjugated diene polymer was used as the sample, and 100° C. when a modified conjugated diene polymer was used as the sample. First, the sample was preheated at the test temperature for 1 minute, and then the rotor was rotated at 2 rpm. The torque was measured after 4 minutes to determine the Mooney viscosity (ML (1+4) ) was decided.

[0136] (Physical property 2) Mooney relaxation rate The modified conjugated diene polymer was used as a sample, and the Mooney viscosity was measured using a Mooney viscometer (manufactured by Ueshima Seisakusho Co., Ltd. under the trade name "VR1132") with an L-shaped rotor in accordance with ISO 289. The rotation of the rotor was then immediately stopped, and the torque was recorded in Mooney units every 0.1 seconds for 1.6 to 5 seconds after the rotor was stopped. The slope of the straight line obtained by plotting the torque versus time (seconds) on a double logarithmic scale was determined, and the absolute value of this was taken as the Mooney relaxation rate (MSR).

[0137] (Physical property 3) Branching degree (Bn) The branching degree (Bn) of the modified conjugated diene polymer was measured by a GPC-light scattering method equipped with a viscosity detector as follows. A modified conjugated diene polymer was used as a sample, and measurements were performed using a gel permeation chromatography (GPC) measuring device (manufactured by Malvern under the trade name "GPCmax VE-2001") having three columns packed with polystyrene gel connected together, and three detectors connected in that order: a light scattering detector, an RI detector, and a viscosity detector (manufactured by Malvern under the trade name "TDA305"). 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. Linear polymer has an intrinsic viscosity [η] = -3.883M 0.771 The shrinkage factor (g') was calculated as the ratio of the intrinsic viscosity corresponding to each molecular weight, where M represents the absolute molecular weight. The obtained shrinkage factor (g') was then used to calculate the branching degree (Bn), defined as g' = 6Bn / [(Bn+1)(Bn+2)]. The eluent used was tetrahydrofuran (hereinafter also referred to as "THF") containing 5 mmol / L triethylamine. The columns used were "TSKgel G4000HXL", "TSKgel G5000HXL", and "TSKgel G6000HXL" manufactured by Tosoh Corporation. 20 mg of the measurement sample was dissolved in 10 mL of THF to prepare a measurement solution, and 100 μL of the measurement solution was injected into a GPC measurement device and measured under conditions of an oven temperature of 40° C. and a THF flow rate of 1 mL / min.

[0138] (Physical property 4) Molecular weight <Measurement condition 1>: Using an unmodified conjugated diene polymer or a modified conjugated diene polymer as a sample, a chromatogram was measured using a GPC measuring device (manufactured by Tosoh Corporation under the trade name "HLC-8320GPC") in which three columns packed with polystyrene gel were connected together, and an RI detector (manufactured by Tosoh Corporation under the trade name "HLC8020"), and the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were determined based on a calibration curve obtained using standard polystyrene. The eluent used was tetrahydrofuran (THF) containing 5 mmol / L triethylamine. Three columns, Tosoh Corporation's "TSKgel SuperMultiporeHZ-H" (trade name), were connected, and a Tosoh Corporation's "TSKguardcolumn SuperMP(HZ)-H" (trade name) was connected in front of them as a guard column. 10 mg of the measurement sample was dissolved in 10 mL of THF to prepare a measurement solution, and 10 μL of the measurement solution was injected into a GPC measurement device and measured under 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, samples whose molecular weight distribution (Mw / Mn) was less than 1.6 were measured again under the following measurement condition 2. Samples whose molecular weight distribution was 1.6 or more after measurement under measurement condition 1 were measured again under measurement condition 1. <Measurement condition 2>: Using an unmodified conjugated diene polymer or a modified conjugated diene polymer as a sample, a chromatogram was measured using a GPC measuring device having three columns connected together, each column using a polystyrene gel as a packing material, and the weight average molecular weight (Mw) and number average molecular weight (Mn) were determined based on a calibration curve using standard polystyrene. The eluent used was THF containing 5 mmol / L triethylamine. The columns used were the following: guard column: Tosoh Corporation's product name "TSKguardcolumn SuperH-H"; columns: Tosoh Corporation's product names "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000". An RI detector (manufactured by Tosoh Corporation under the trade name "HLC8020") was used under the conditions of an oven temperature of 40° C. and a THF flow rate of 0.6 mL / min. 10 mg of a sample to be measured was dissolved in 20 mL of THF to prepare a measurement solution, and 20 μL of the measurement solution was injected into a GPC measurement device for measurement. For samples that were measured under measurement condition 1 and had a molecular weight distribution value of less than 1.6, measurement was performed under measurement condition 2.

[0139] (Physical property 5) Modification rate The modification rate of the modified conjugated diene polymer was measured by a column adsorption GPC method as follows. The modified conjugated diene polymer was used as a sample, and the measurement was carried out by utilizing the adsorption property of the modified basic polymer component in a GPC column packed with silica gel. The amount of a sample solution containing a sample and low molecular weight internal standard polystyrene was adsorbed onto the silica-based column by measuring the difference between the chromatogram measured using a polystyrene-based column and the chromatogram measured using a silica-based column, and the modification rate was calculated. Specifically, it is as follows: Furthermore, samples that were measured under the above (Physical Property 4) Measurement Condition 1 and had a molecular weight distribution value of 1.6 or more were measured under the following Measurement Condition 3. Samples that were measured under the above (Physical Property 4) Measurement Condition 1 and had a molecular weight distribution value of less than 1.6 were measured under the following Measurement Condition 4.

[0140] <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 polystyrene columns: A Tosoh Corporation product name "HLC-8320GPC" was used, and 10 μL of the sample solution was injected into the device using THF containing 5 mmol / L triethylamine as the eluent. A chromatogram was obtained using an RI detector under the following conditions: column oven temperature 40°C, THF flow rate 0.35 mL / min. The columns used were three Tosoh Corporation products (TSKgel SuperMultiporeHZ-H) connected together, with a Tosoh Corporation product (TSKguardcolumn SuperMP(HZ)-H) connected in front of them as a guard column. <Measurement condition 4>: GPC measurement conditions using polystyrene columns: THF containing 5 mmol / L triethylamine was used as the eluent, and 20 μL of the sample solution was injected into the device for measurement. The columns used were a guard column manufactured by Tosoh Corporation under the trade name "TSKguardcolumn SuperH-H" and columns manufactured by Tosoh Corporation under the trade names "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000". Measurement was performed using an RI detector (manufactured by Tosoh Corporation, HLC8020) under conditions of a column oven temperature of 40°C and a THF flow rate of 0.6 mL / min, to obtain a chromatogram.

[0141] GPC measurement conditions using a silica column: A Tosoh Corporation product name "HLC-8320GPC" was used, THF was used as the eluent, 50 μL of the sample solution was injected into the device, 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 Zorbax PSM-1000S, PSM-300S, and PSM-60S, and a guard column "DIOL 4.6 × 12.5 mm 5 micron" was connected to the front of the columns.

[0142] How to calculate the denaturation rate: The total peak area of ​​the chromatogram using the polystyrene column was set as 100, the peak area of ​​the sample was set as P1, the peak area of ​​the standard polystyrene was set as P2, the total peak area of ​​the chromatogram using the silica column was set as 100, the peak area of ​​the sample was set as P3, and the peak area of ​​the standard polystyrene was set as P4, and the modification rate (%) was calculated using the following formula. Denaturation rate (%) = [1-(P2 x P3) / (P1 x P4)] x 100 (where P1+P2=P3+P4=100)

[0143] (Physical property 6) Bound styrene content A modified conjugated diene polymer not containing a rubber softener was used as a sample, and 100 mg of the sample was dissolved in chloroform up to 100 mL to prepare a measurement sample. The amount of bound styrene (mass%) relative to 100 mass% of the sample modified conjugated diene polymer was measured based on the amount of absorption of ultraviolet light (around 254 nm) by the phenyl group of styrene (measuring device: Shimadzu Corporation spectrophotometer "UV-2450").

[0144] (Physical property 7) Microstructure of butadiene part (1,2-vinyl bond amount) A modified conjugated diene polymer not containing a rubber softener was used as a sample, and 50 mg of the sample was dissolved in 10 mL of carbon disulfide to prepare a measurement sample. Using a solution cell, infrared spectra are recorded from 600 to 1000 cm -1The absorbance at a predetermined wave number was measured in the range of 100 nm to 150 nm, and the microstructure of the butadiene portion, i.e., the amount of 1,2-vinyl bonds (mol%) was calculated according to the formula of Hampton's method (method described in R.R. Hampton, Analytical Chemistry 21, 923 (1949)) (measuring device: Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation).

[0145] (Physical Property 8) Molecular weight measured by GPC-light scattering method (absolute molecular weight Mw-i) The modified conjugated diene polymer was used as a sample, and a chromatogram was measured using a GPC-light scattering measurement device in which three columns packed with polystyrene gel 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 the "absolute molecular weight"). The eluent used was a mixed solution of tetrahydrofuran and triethylamine (THF in TEA: prepared by mixing 5 mL of triethylamine in 1 L of tetrahydrofuran). The columns used were a guard column (manufactured by Tosoh Corporation under the trade name "TSKguardcolumn HHR-H") and columns (manufactured by Tosoh Corporation under the trade names "TSKgel G6000HHR", "TSKgel G5000HHR", and "TSKgel G4000HHR"). A GPC-light scattering measuring device (trade name "Viscotek TDAmax" manufactured by Malvern Instruments) was used under conditions of an oven temperature of 40° C. and a THF flow rate of 1.0 mL / min. 10 mg of the measurement sample 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.

[0146] (Rating 9) Change over time (Mooney viscosity increase after one month) The modified conjugated diene polymer was stored at room temperature and pressure for one month, and the Mooney viscosity after storage was measured, and the difference from the Mooney viscosity measured immediately after polymerization was calculated. In the table, this is indicated as "δML Mooney viscosity." The smaller the value, the less change there is over time and the better the quality stability.

[0147] [Modified conjugated diene polymer] (Example 1) Modified conjugated diene polymer (sample 1) Two tank-type pressure vessels having an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom and an outlet at the top, and an agitator as a tank-type reactor and a jacket for temperature control were connected together as polymerization reactors. 1,3-butadiene, which had been previously dehydrated, was mixed at 18.6 g / min, styrene at 10.0 g / min, and n-hexane at 175.2 g / min. In a static mixer installed in the middle of the pipe supplying this mixed solution to the inlet of the reactor, n-butyllithium for inactivating remaining impurities was added at 0.103 mmol / min, mixed, and then continuously supplied to the bottom of the reactor. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance was supplied 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 to the bottom of the first reactor, which was 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 fed to the bottom of the second reactor to continue the reaction at 70°C, and further fed to a static mixer from the top of the second reactor. When the polymerization was sufficiently stabilized, trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was added as a branching agent from the bottom of the second reactor at a rate of 0.0190 mmol / min while copolymerizing 1,3-butadiene and styrene, and a polymerization reaction and a branching reaction were carried out to obtain a conjugated diene-based polymer having a main chain branched structure. When the polymerization reaction and branching reaction became stable, a small amount of the conjugated diene polymer solution before the addition of the modifier was withdrawn, and an antioxidant (BHT) was added in an amount of 0.2 g per 100 g of polymer, after which 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, compound M-1 (the compound shown as (M-1) in the above <Compound [M] used in the modification step>. In the table, it is abbreviated as "M-1") was continuously added as a modifier 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 to carry out a coupling reaction. At this time, it took 4.8 minutes for the modifier to be added to the polymer solution flowing out from the outlet of the reactor, the temperature was 68°C, and the difference between the temperature in the polymerization step and the temperature before the modifier was added was 2°C. After the coupling reaction, a small amount of the conjugated diene polymer solution was taken out, and an antioxidant (BHT) was added in an amount of 0.2 g per 100 g of polymer. The solvent was then removed, and the amount of bound styrene (physical property 6) and the microstructure of the butadiene portion (amount of 1,2-vinyl bonds: physical property 7) were measured. The measurement results are shown in Table 1. 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 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 as a rubber softener so that the amount was 25.0 g per 100 g of polymer, and mixed with a static mixer. The solvent was removed by steam stripping to obtain a modified conjugated diene polymer (sample 1). The physical properties of Sample 1 are shown in Table 1. The structure of the modified conjugated diene polymer was identified by comparing the molecular weight measured by GPC and the branching degree measured by GPC with a viscometer 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 modifier. The structure of each sample was similarly identified.

[0148] (Example 2) Modified conjugated diene polymer (sample 2) A modified conjugated diene polymer (sample 2) was obtained in the same manner as in Example 1, except that the modifying agent was changed from compound M-1 to compound M-2 (a compound shown as (M-2) in the above <Compounds [M] used in the modification step>. In the table, it is abbreviated as "M-2") and the amount of the modifying agent was changed to 0.0720 mmol / min. The physical properties of sample 2 are shown in Table 1.

[0149] (Example 3) Modified conjugated diene polymer (sample 3) A modified conjugated diene polymer (sample 3) was obtained in the same manner as in Example 1, except that the modifying agent was changed from compound M-1 to compound M-3 (the compound shown as (M-3) in the above <Compounds [M] used in the modification step>. In the table, it is abbreviated as "M-3") and the amount of the modifying agent was changed to 0.0360 mmol / min. The physical properties of sample 3 are shown in Table 1.

[0150] (Example 4) Modified conjugated diene polymer (sample 4) A modified conjugated diene polymer (sample 4) was obtained in the same manner as in Example 1, except that the modifying agent was changed from compound M-1 to compound M-4 (the compound shown as (M-4) in the above <Compounds [M] used in the modification step>. In the table, it is abbreviated as "M-4") and the amount of the modifying agent was changed to 0.0720 mmol / min. The physical properties of sample 4 are shown in Table 1.

[0151] (Example 5) Modified conjugated diene polymer (sample 5) A modified conjugated diene polymer (sample 5) was obtained in the same manner as in Example 1, except that the modifying agent was changed from compound M-1 to compound M-5 (a compound shown as (M-5) in the above <Compounds [M] used in the modification step>. In the table, it is abbreviated as "M-5") and the amount of the modifying agent was changed to 0.0360 mmol / min. The physical properties of sample 5 are shown in Table 1.

[0152] (Example 6) Modified conjugated diene polymer (sample 6) A modified conjugated diene polymer (sample 6) was obtained in the same manner as in Example 1, except that the modifying agent was changed from compound M-1 to compound M-13 (a compound shown as (M-13) in the above <Compounds [M] used in the modification step>. In the table, it is abbreviated as "M-13") and the amount of the modifying agent was changed to 0.0250 mmol / min. The physical properties of sample 6 are shown in Table 1.

[0153] (Example 7) Modified conjugated diene polymer (sample 7) A modified conjugated diene polymer (sample 7) was obtained in the same manner as in Example 1, except that the amount of compound M-1 (abbreviated as "M-1" in the table) added as the modifying agent was changed to 0.0420 mmol / min. The physical properties of sample 7 are shown in Table 1.

[0154] (Example 8) Modified conjugated diene polymer (sample 8) A modified conjugated diene polymer (sample 8) was obtained in the same manner as in Example 1, except that 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 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 physical properties of sample 8 are shown in Table 1.

[0155] (Example 9) Modified conjugated diene polymer (sample 9) A modified conjugated diene polymer (sample 9) was obtained in the same manner as in Example 1, except that 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 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 physical properties of sample 9 are shown in Table 2.

[0156] (Example 10) Modified conjugated diene polymer (sample 10) A modified conjugated diene polymer (sample 10) was obtained in the same manner as in Example 1, except that the addition rate of the polar substance 2,2-bis(2-oxolanyl)propane was changed from 0.081 mmol / min to 0.200 mmol / min. The physical properties of sample 10 are shown in Table 2.

[0157] (Example 11) Modified conjugated diene polymer (sample 11) A modified conjugated diene polymer (sample 11) was obtained in the same manner as in Example 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 amount of the branching agent was changed to 0.0350 mmol / min. The physical properties of sample 11 are shown in Table 2.

[0158] (Example 12) Modified conjugated diene polymer (sample 12) A modified conjugated diene polymer (sample 12) was obtained in the same manner as in Example 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 amount of the branching agent was changed to 0.0350 mmol / min, and the modifying agent was changed from compound M-1 to compound M-3 (the compound shown as (M-3) in the above <Compounds [M] used in the modification step>. Abbreviated as "M-3" in the table). The physical properties of sample 12 are shown in Table 2.

[0159] (Example 13) Modified conjugated diene polymer (sample 13) A modified conjugated diene polymer (sample 13) was obtained in the same manner as in Example 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 amount of addition was changed to 0.0350 mmol / min, and the modifying agent was changed from compound M-1 to compound M-13 (the compound shown as (M-13) in the above <Compounds [M] used in the modification step>. Abbreviated as "M-13" in the table), the amount of addition was changed to 0.0160 mmol / min. The physical properties of sample 13 are shown in Table 2.

[0160] (Example 14) Modified conjugated diene polymer (sample 14) A modified conjugated diene polymer (sample 14) was obtained in the same manner as in Example 1, except that 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 the amount added was changed to 0.0120 mmol / min. The physical properties of sample 14 are shown in Table 2.

[0161] (Example 15) Modified conjugated diene polymer (sample 15) A modified conjugated diene polymer (sample 15) was obtained in the same manner as in Example 1, except that 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), the amount of addition was changed to 0.0120 mmol / min, the modifying agent was changed from compound M-1 (abbreviated as "M-1" in the table) to compound M-3 (the compound shown as (M-3) in the above <Compounds [M] used in the modification step>. Abbreviated as "M-3" in the table), the amount of addition was changed to 0.0360 mmol / min. The physical properties of sample 15 are shown in Table 2.

[0162] (Example 16) Modified conjugated diene polymer (sample 16) A modified conjugated diene polymer (sample 16) was obtained in the same manner as in Example 1, except that 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 the amount added was changed to 0.0120 mmol / min, and the modifying agent was changed from compound M-1 (abbreviated as "M-1" in the table) to compound M-13 (the compound shown as (M-13) in <Compounds [M] used in the modification step> above. Abbreviated as "M-13" in the table), and the amount added was changed to 0.0160 mmol / min. The physical properties of sample 16 are shown in Table 2.

[0163] (Example 17) Modified conjugated diene polymer (sample 17) A modified conjugated diene polymer (sample 17) was obtained in the same manner as in Example 1, except that 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 the amount of the branching agent added was changed to 0.0210 mmol / min. The physical properties of sample 17 are shown in Table 3.

[0164] (Example 18) Modified conjugated diene polymer (sample 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), and the amount added was changed to 0.0210 mmol / min. The modifying agent was changed from compound M-1 (abbreviated as "M-1" in the table) to compound M-3 (the compound shown as (M-3) in the above <Compounds [M] used in the modification step>. Abbreviated as "M-3" in the table). The amount added was changed to 0.0360 mmol / min. A modified conjugated diene polymer (sample 18) was obtained. The physical properties of sample 18 are shown in Table 3.

[0165] (Example 19) Modified conjugated diene polymer (sample 19) A modified conjugated diene polymer (sample 19) was obtained in the same manner as in Example 1, except that the branching agent was changed from trimethoxy(4-vinylphenyl)silane to 1,1-bis(4-trimethoxysilylphenyl)ethylene (abbreviated as "BS-4" in the table), the modifying agent was changed from compound M-1 (abbreviated as "M-1" in the table) to compound M-13 (the compound shown as (M-13) in the above <Compounds [M] used in the modification step>. Abbreviated as "M-13" in the table), and the amount of addition was changed to 0.0160 mmol / min. The physical properties of sample 19 are shown in Table 3.

[0166] (Example 20) Modified conjugated diene polymer (sample 20) A modified conjugated diene polymer (sample 20) was obtained in the same manner as in Example 1, except that the branching agent was changed from trimethoxy(4-vinylphenyl)silane to trichloro(4-vinylphenyl)silane (abbreviated as "BS-5" in the table) and the amount of the branching agent was changed to 0.0190 mmol / min. The physical properties of sample 20 are shown in Table 3.

[0167] (Example 21) Modified conjugated diene polymer (sample 21) A modified conjugated diene polymer (sample 21) was obtained in the same manner as in Example 1, except that the branching agent was changed from trimethoxy(4-vinylphenyl)silane to trichloro(4-vinylphenyl)silane (abbreviated as "BS-5" in the table), the amount of addition was changed to 0.0190 mmol / min, and the modifying agent was changed from compound M-1 (abbreviated as "M-1" in the table) to compound M-3 (the compound shown as (M-3) in the above <Compounds [M] used in the modification step>. Abbreviated as "M-3" in the table), the amount of addition was changed to 0.0360 mmol / min. The physical properties of sample 21 are shown in Table 3.

[0168] (Example 22) Modified conjugated diene polymer (sample 22) A modified conjugated diene polymer (sample 22) was obtained in the same manner as in Example 1, except that the branching agent was changed from trimethoxy(4-vinylphenyl)silane to trichloro(4-vinylphenyl)silane (abbreviated as "BS-5" in the table), the amount of addition was changed to 0.0190 mmol / min, and the modifying agent was changed from compound M-1 (abbreviated as "M-1" in the table) to compound M-13 (the compound shown as (M-13) in the above <Compounds [M] used in the modification step>. Abbreviated as "M-13" in the table), the amount of addition was changed to 0.0160 mmol / min. The physical properties of sample 22 are shown in Table 3.

[0169] (Example A-1) Coupling conjugated diene polymer (sample A-1) Two tank-type pressure vessels having an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom and an outlet at the top, and an agitator as a tank-type reactor and a jacket for temperature control were connected together as polymerization reactors. 1,3-butadiene, which had been previously dehydrated, was mixed at 14.0 g / min, styrene at 10.0 g / min, and n-hexane at 175.2 g / min. In a static mixer installed in the middle of the pipe supplying this mixed solution to the inlet of the reactor, n-butyllithium for inactivating remaining impurities was added at 0.103 mmol / min, mixed, and then continuously supplied to the bottom of the reactor. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance was supplied 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 to the bottom of the first reactor, which was 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 fed to the bottom of the second reactor to continue the reaction at 70°C, and further fed to a static mixer from the top of the second reactor. When the polymerization was sufficiently stabilized, the branching agent trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was added from the bottom of the second reactor at a rate of 0.0190 mmol / min while 1,3-butadiene was added at 4.6 g / min in parallel, to perform the polymerization reaction and branching reaction to obtain a conjugated diene polymer having a main chain branched structure. When the polymerization reaction and branching reaction became stable, a small amount of the conjugated diene polymer solution before the addition of the coupling agent was withdrawn, and an antioxidant (BHT) was added in an amount of 0.2 g per 100 g of polymer, after which the solvent was removed and the Mooney viscosity at 110°C and various molecular weights were measured. The physical properties are shown in Table 4. Next, compound M-1 (the compound shown as (M-1) in the above <Compounds [M] used in the modification step>. In the table, it is abbreviated as "M-1") was used as a coupling agent in the polymer solution discharged from the outlet of the reactor, and the compound M-1 was continuously added at an addition amount of 0.0360 mmol / min, and the mixture was 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 from the outlet of the reactor was 4.8 minutes, the temperature was 68°C, and the difference between the temperature in the polymerization process and the temperature until the coupling agent was added was 2°C. After the coupling reaction, a small amount of the conjugated diene polymer solution was taken out, and an antioxidant (BHT) was added in an amount of 0.2 g per 100 g of polymer. The solvent was then removed, and the amount of bound styrene (physical property 6) and the microstructure of the butadiene portion (amount of 1,2-vinyl bonds: physical property 7) were measured. The measurement results are shown in Table 4. 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 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 as a rubber softener in an amount of 25.0 g per 100 g of polymer, and mixed with a static mixer. The solvent was removed by steam stripping to obtain a coupled conjugated diene polymer (modified conjugated diene polymer) (sample A-1) having a four-branched structure derived from the branching agent (hereinafter also referred to as "branching agent structure (1)"), which is a compound represented by the above formula (1), in a portion of the main chain and a four-branched star polymer structure derived from the coupling agent. The physical properties of sample A-1 are shown in Table 4. The structure of the coupling conjugated diene polymer was identified by comparing the molecular weight measured by GPC and the branching degree measured by GPC with a viscometer 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 each sample was similarly identified.

[0170] (Example A-2) Coupling conjugated diene polymer (Sample A-2) Two tank-type pressure vessels having an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom and an outlet at the top, and an agitator as a tank-type reactor and a jacket for temperature control were connected together as polymerization reactors. 1,3-butadiene, which had been previously dehydrated, was mixed at 14.0 g / min, styrene at 8.0 g / min, and n-hexane at 175.2 g / min. In a static mixer installed in the middle of the pipe supplying this mixed solution to the inlet of the reactor, n-butyllithium for inactivating remaining impurities was added at 0.103 mmol / min, mixed, and then continuously supplied to the bottom of the reactor. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance was supplied 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 to the bottom of the first reactor, which was 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 fed to the bottom of the second reactor to continue the reaction at 70°C, and further fed to a static mixer from the top of the second reactor. When the polymerization was sufficiently stable, 1,3-butadiene and styrene were copolymerized while trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table), a branching agent, was added from the bottom of the second reactor 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-based polymer having a main chain branched structure. When the polymerization reaction and branching reaction became stable, a small amount of the conjugated diene polymer solution before the addition of the coupling agent was withdrawn, and an antioxidant (BHT) was added in an amount of 0.2 g per 100 g of polymer, after which the solvent was removed and the Mooney viscosity at 110°C and various molecular weights were measured. The physical properties are shown in Table 4. Next, compound M-1 (the compound shown as (M-1) in the above <Compounds [M] used in the modification step>. In the table, it is abbreviated as "M-1") was used as a coupling agent in the polymer solution discharged from the outlet of the reactor, and the compound M-1 was continuously added at an addition amount of 0.0360 mmol / min, and the mixture was 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 from the outlet of the reactor was 4.8 minutes, the temperature was 68°C, and the difference between the temperature in the polymerization process and the temperature before the coupling agent was added was 2°C. A small amount of the conjugated diene polymer solution after the coupling reaction was withdrawn, and an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of polymer, and 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 4. 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 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 as a rubber softener in an amount of 25.0 g per 100 g of polymer, and mixed with a static mixer. The solvent was removed by steam stripping to obtain a coupled conjugated diene polymer (modified conjugated diene polymer) (sample A-2) having a four-branched structure derived from the branching agent (hereinafter also referred to as "branching agent structure (1)"), which is a compound represented by the above formula (1), in a portion of the main chain and a four-branched star polymer structure derived from the coupling agent. The physical properties of sample A-2 are shown in Table 4. The structure of the coupling conjugated diene polymer was identified by comparing the molecular weight measured by GPC and the branching degree measured by GPC with a viscometer 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 each sample was similarly identified.

[0171] (Comparative Example 1) Modified conjugated diene polymer (sample 23) Two tank-type pressure vessels having an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom and an outlet at the top, and an agitator as a tank-type reactor and a jacket for temperature control were connected together as polymerization reactors. 1,3-butadiene, which had been previously dehydrated, was mixed at 18.6 g / min, styrene at 10.0 g / min, and n-hexane at 175.2 g / min. In a static mixer installed in the middle of the pipe supplying this mixed solution to the inlet of the reactor, n-butyllithium for inactivating remaining impurities was added at 0.103 mmol / min, mixed, and then continuously supplied to the bottom of the reactor. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance was supplied 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 to the bottom of the first reactor, which was 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 fed to the bottom of the second reactor to continue the reaction at 70°C, and then fed to the static mixer from the top of the second reactor. When the polymerization was sufficiently stabilized, a small amount of the polymer solution before the addition of the modifier was withdrawn, and an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of polymer, after which the solvent was removed and the Mooney viscosity at 110°C and various molecular weights were measured. The physical properties are shown in Table 5. Next, compound M-1 (a compound shown as (M-1) in the above <Compound [M] used in the modification step>. In the table, it is abbreviated as "M-1") was continuously added as a modifier 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 to carry out 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 before the modifier was added was 2 ° C. A small amount of the conjugated diene polymer solution after the coupling reaction was extracted, and an antioxidant (BHT) was added so that it was 0.2 g per 100 g of polymer, and 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 5. 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 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 as a rubber softener so that the amount was 25.0 g per 100 g of polymer, and mixed with a static mixer. The solvent was removed by steam stripping to obtain a modified conjugated diene polymer (sample 23). The physical properties of sample 23 are shown in Table 5.

[0172] (Comparative Example 2) Modified conjugated diene polymer (sample 24) A modified conjugated diene polymer (sample 24) was obtained in the same manner as in Comparative Example 1, except that the modifying agent was changed from compound M-1 (abbreviated as "M-1" in the table) to compound M-2 (a compound shown as (M-2) in the above <Compounds [M] used in the modification step>. Abbreviated as "M-2" in the table) and the amount of the modifying agent was changed to 0.0720 mmol / min. The physical properties of sample 24 are shown in Table 5.

[0173] (Comparative Example 3) Modified conjugated diene polymer (sample 25) A modified conjugated diene polymer (sample 25) was obtained in the same manner as in Comparative Example 1, except that the modifying agent was changed from compound M-1 (abbreviated as "M-1" in the table) to compound M-3 (a compound shown as (M-3) in the above <Compounds [M] used in the modification step>. Abbreviated as "M-3" in the table) and the amount of the modifying agent was changed to 0.0360 mmol / min. The physical properties of sample 25 are shown in Table 5.

[0174] (Comparative Example 4) Modified conjugated diene polymer (sample 26) A modified conjugated diene polymer (sample 26) was obtained in the same manner as in Comparative Example 1, except that the modifying agent was changed from compound M-1 (abbreviated as "M-1" in the table) to compound M-4 (a compound shown as (M-4) in the above <Compounds [M] used in the modification step>. Abbreviated as "M-4" in the table) and the amount of the compound added was changed to 0.0720 mmol / min. The physical properties of sample 26 are shown in Table 5.

[0175] (Comparative Example 5) Modified conjugated diene polymer (sample 27) A modified conjugated diene polymer (sample 27) was obtained in the same manner as in Comparative Example 1, except that the modifying agent was changed from compound M-1 (abbreviated as "M-1" in the table) to compound M-5 (a compound shown as (M-5) in the above <Compounds [M] used in the modification step>. Abbreviated as "M-5" in the table) and the amount of the modifying agent was changed to 0.0360 mmol / min. The physical properties of sample 27 are shown in Table 5.

[0176] (Comparative Example 6) Modified conjugated diene polymer (sample 28) A modified conjugated diene polymer (sample 28) was obtained in the same manner as in Comparative Example 1, except that the modifying agent was changed from compound M-1 (abbreviated as "M-1" in the table) to compound M-13 (a compound shown as (M-13) in the above <Compounds [M] used in the modification step>. Abbreviated as "M-13" in the table) and the amount of the modifying agent was changed to 0.0250 mmol / min. The physical properties of sample 28 are shown in Table 5.

[0177] (Example 23) Modified conjugated diene polymer (sample 29) An autoclave with an internal volume of 5 L (L / D: 3.4), equipped with a stirrer and a jacket and capable of controlling temperature was used as a reactor. 1995 g of normal hexane and n-butyllithium for neutralizing impurities present in the reactor that may hinder the polymerization reaction were placed in the reactor, and the mixture was stirred at 70°C for 5 minutes. The mixture was then cooled to room temperature, the solution was removed, and the reactor was emptied. Next, 1,670 g of normal hexane from which impurities had been removed, 83 g of styrene, 236 g of 1,3-butadiene, and 2.73 mmol of 2,2-bis(2-oxolanyl)propane as a polar substance were placed in a reactor, and when the temperature inside the reactor was 56°C, 2.92 mmol of n-butyllithium (referred to as "NBL" in the table) was added as a polymerization initiator to initiate polymerization. Immediately after the polymerization started, the temperature in the reactor rose and reached a peak temperature of 79°C. When a drop in temperature was confirmed, 1.50 mmol of trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was added as a branching agent, and the mixture was stirred for 5 minutes. 0.73 mmol of tetraethoxysilane compound M-1 (a compound shown as (M-1) in the above <Compound [M] used in the modification step>. Abbreviated as "M-1" in the table) was added as a coupling agent, and the mixture was stirred for another 5 minutes. The stirring speed at this time was 200 rpm. The coupling agent was added 7 minutes after the peak temperature was reached. The reaction was terminated by adding 2.92 mmol of ethanol as a polymerization terminator, to obtain a polymer solution containing a modified conjugated diene polymer. To the resulting polymerization solution, 0.64 g of 2,6-di-tert-butyl-4-hydroxytoluene was added as an antioxidant, and the solvent was then removed by steam stripping. After vacuum drying, modified conjugated diene polymer 29 was obtained. The physical properties are shown in Table 6 below.

[0178] (Comparative Example 7) Modified conjugated diene polymer (sample 30) A 5 L internal volume autoclave equipped with a stirrer and a jacket and capable of controlling temperature was used as a reactor. 1670 g of normal hexane, 83 g of styrene, 236 g of 1,3-butadiene, and 1.91 mmol of 2,2-bis(2-oxolanyl)propane as a polar substance, from which impurities had been removed in advance, were placed in the reactor, and when the temperature inside the reactor was 58°C, 2.55 mmol of a polymerization initiator, n-butyllithium, was added to initiate polymerization. Immediately after the start of polymerization, the temperature in the reactor rose, and when the temperature reached a peak and a drop was confirmed, tetraethoxysilane compound M-1 (a compound shown as (M-1) in the above <Compound [M] used in the modification step>. In the table, it is abbreviated as "M-1") was added as a coupling agent and stirred for another 10 minutes. 2.55 mmol of ethanol was added as a polymerization terminator to terminate the reaction, and a polymer solution containing a modified conjugated diene polymer was obtained. 0.64 g of 2,6-di-tert-butyl-4-hydroxytoluene was added as a stabilizer to the obtained polymerization solution, and the solvent was removed by steam stripping, and the mixture was dried in vacuum to obtain a modified conjugated diene polymer 30. The physical properties are shown in Table 6 below.

[0179] (Comparative Example B-1) Coupling Conjugated Diene Polymer (Sample B-1) Two tank-type pressure vessels having an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom and an outlet at the top, and an agitator as a tank-type reactor and a jacket for temperature control were connected together as polymerization reactors. 1,3-butadiene, which had been previously dehydrated, was mixed at 18.6 g / min, styrene at 10.0 g / min, and n-hexane at 175.2 g / min. In a static mixer installed in the middle of the pipe supplying this mixed solution to the inlet of the reactor, n-butyllithium for inactivating remaining impurities was added at 0.103 mmol / min, mixed, and then continuously supplied to the bottom of the reactor. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance was supplied 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 to the bottom of the first reactor, which was 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 fed to the bottom of the second reactor where the reaction was continued at 70° C., and further fed to a static mixer from the top of the second reactor. When the polymerization reaction became stable, a small amount of the conjugated diene polymer solution before the addition of the coupling agent was withdrawn, and an antioxidant (BHT) was added in an amount of 0.2 g per 100 g of polymer, after which the solvent was removed and the Mooney viscosity at 110°C and various molecular weights were measured. The physical properties are shown in Table 4. Next, trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was added to the polymer solution discharged 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. The mixture was 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 from the outlet of the reactor was 4.8 minutes, the temperature was 68° C., and the difference between the temperature in the polymerization process and the temperature before the coupling agent was added was 2° C. A small amount of the conjugated diene polymer solution after the coupling reaction was withdrawn, and an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of polymer, and 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 4. 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 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 as a rubber softener in an amount of 25.0 g per 100 g of the polymer, and mixed in a static mixer. The solvent was removed by steam stripping to obtain a coupling conjugated diene polymer (modified conjugated diene polymer) (sample B-1). The physical properties of sample B-1 are shown in Table 4. In Table 4 (Comparative Example B-1), "BS-1" is listed in the branching agent column, but in the addition method of this example, it did not act as a branching agent. In (Comparative Example B-1), since "BS-1" was added after the monomer was consumed, it is assumed that after the active end was bonded to the methoxy group of "BS-1", there was almost no monomer to polymerize with the vinyl group of "BS-1". In other words, even if "BS-1" was added, the "branching process" did not occur because there was no monomer. From the shrinkage factor of (Sample B-1), it can be confirmed that branches are formed only within the range of the number of functional groups of the coupling agent, and it is considered that an increase in the number of branches due to the combination of the main chain branching structure due to "BS-1" and the coupling structure in one polymer has not occurred. The structure of the coupled conjugated diene polymer was identified by comparing the molecular weight measured by GPC and the branching degree measured by GPC equipped with a viscometer for the polymer before the addition of "BS-1", the polymer after the addition of "BS-1", and the polymer in each step after the addition of the coupling agent.

[0180] (Comparative Example B-2) Coupling conjugated diene polymer (Sample B-2) The coupling agent used was the coupling agent shown in (Z-1) below (abbreviated as "Z-1" in the table), and the amount added was 0.0360 mmol / min. The other conditions were the same as in Comparative Example 1, and a coupling conjugated diene polymer (modified conjugated diene polymer) (sample B-2) was obtained that had no main chain branching derived from the branching agent and had a 10-branch star polymer structure derived from the coupling agent. The physical properties of sample B-2 are shown in Table 4.

[0181] [ka]

[0182] [Table 1]

[0183] [Table 2]

[0184] [Table 3]

[0185] [Table 4]

[0186] [Table 5]

[0187] [Table 6]

[0188] (Examples 24 to 46, Examples a-1 to 2, and Comparative Examples 8 to 14, Comparative Examples b-1 to 2) Rubber composition Samples 1 to 30, A-1 to 2, and B-1 to 2 shown in Tables 1 to 6 were used as raw rubbers to obtain rubber compositions containing each raw rubber according to the formulation shown below.

[0189] (Rubber component) Modified conjugated diene polymers (samples 1-30, A-1-2, B-1-2) : 80 parts by weight (excluding rubber softener) High cis polybutadiene (product name "UBEPOL BR150" manufactured by Ube Industries) :20 parts by mass

[0190] (Combination conditions) The amount of each compounding ingredient added is shown in parts by mass per 100 parts by mass of the rubber component not including the rubber softener. Silica 1 (product name "Ultrasil 7000GR" manufactured by Evonik Degussa) Nitrogen adsorption specific surface area 170m2 / g): 50.0 parts by mass Silica 2 (Rhodia product name "Zeosil Premium 200MP") Nitrogen adsorption specific surface area 220m2 / 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" manufactured by Evonik Degussa, bis(triethoxysilylpropyl) disulfide): 6.0 parts by mass SRAE oil (product name "Process NC140" manufactured by JX Nippon Oil & Energy Corporation) :42.0 parts by mass (This includes the amount previously added as a rubber softener in Samples 1 to 30, Samples A-1 to 2, and Samples B-1 to 2.) ·Zinc white: 2.5 parts by mass Stearic acid: 1.0 parts by weight Anti-aging agent (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 (diphenyl guanidine): 2.0 parts by mass ·Total: 239.4 parts by mass

[0191] (Mixing method) The above materials were kneaded by the following method to obtain rubber compositions. Using an internal mixer (capacity 0.3 L) equipped with a temperature control device, the raw rubber (samples 1 to 30, samples A-1 to 2, samples B-1 to 2), fillers (silica 1, silica 2, carbon black), silane modifier, SRAE oil, zinc oxide, and stearic acid were kneaded in the first stage of kneading under conditions of a filling rate of 65% and a rotor rotation speed of 30 to 50 rpm. At this time, the temperature of the internal mixer was controlled, and each rubber composition (compound) was obtained at a discharge temperature of 155 to 160°C. Next, in the second stage of kneading, the mixture obtained above was cooled to room temperature, and then the antioxidant was added and kneaded again to improve the dispersion of the silica. In this case, the discharge temperature of the mixture was adjusted to 155 to 160°C by controlling the temperature of the mixer. After cooling, in the third stage of kneading, sulfur and vulcanization accelerators 1 and 2 were added and kneaded using an open roll set at 70°C. Thereafter, the product was molded and vulcanized in a vulcanization press at 160°C for 20 minutes. The rubber compositions before and after vulcanization were evaluated. Specifically, the evaluation was performed by the following methods. The evaluation results are shown in Tables 7 to 12.

[0192] [Evaluation of characteristics] (Evaluation 1) Compound Mooney Viscosity The compound obtained above after the second stage mixing and before the third stage mixing was used as a sample, and the viscosity was measured using a Mooney viscometer in accordance with ISO 289 after preheating at 130°C for 1 minute and rotating the rotor at 2 revolutions per minute for 4 minutes. The result of Comparative Example 8 was set to 100 and indexed. The smaller the index, the better the processability.

[0193] (Evaluation 2) Tensile strength and tensile elongation The tensile strength and tensile elongation were measured according to the tensile test method of JIS K6251, and indexed based on the result of Comparative Example 8 being 100. A larger index indicates better tensile strength and tensile elongation (breaking strength).

[0194] (Rating 3) Abrasion resistance Using an Acron abrasion tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), the amount of wear was measured at a load of 44.4 N and 1000 revolutions in accordance with JIS K6264-2, and indexed with the result of Comparative Example 8 being set at 100. A higher index indicates better abrasion resistance.

[0195] (Evaluation 4) Viscoelastic parameters Viscoelastic parameters were measured in torsion mode using a viscoelasticity tester "ARES" manufactured by Rheometrics Scientific Co., Ltd. Each measured value was indexed with the result for the rubber composition of Comparative Example 8 set at 100. Tan δ measured at 0°C, a frequency of 10 Hz, and a strain of 1% was used as an index of wet skid resistance. A higher index value indicates better wet skid resistance. In addition, tan δ measured at 50°C, a frequency of 10 Hz, and a strain of 3% was used as an index of fuel economy. The smaller the index, the better the fuel economy. 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 steering stability. A higher index value indicates better steering stability.

[0196] [Table 7]

[0197] [Table 8]

[0198] [Table 9]

[0199] [Table 10]

[0200] [Table 11]

[0201] [Table 12]

[0202] As shown in Tables 7 to 12, it was confirmed that, compared with Comparative Examples 8 to 14 and Comparative Examples b-1 to 2, Examples 24 to 46 and Examples a-1 and a-2 had low compound Mooney viscosity when vulcanized, exhibited good processability, and were excellent in abrasion resistance, handling stability and fracture strength when vulcanized, and also had an excellent balance between low hysteresis loss and wet skid resistance. [Industrial Applicability]

[0203] The modified conjugated diene polymer obtained by the production method of the present invention is used in tire treads, automobile In the fields of interior and exterior parts, vibration-proof rubber, belts, footwear, foams, various industrial products, etc. This has industrial applicability.

Claims

1. An alkali metal compound or an alkaline earth metal compound is used as a polymerization initiator to produce a conjugated diene. or by polymerizing or copolymerizing a conjugated diene compound and an aromatic vinyl compound, a polymerization step for obtaining a conjugated diene-based polymer having an active terminal; A branched structure is introduced by reacting a styrene derivative with the active terminal of the conjugated diene polymer. A branching step; The active terminal of the conjugated diene polymer formed after the branching step and the group "-C(R 1 ) = N-A 1 " and / or the group "-N=C(R 1 ) -A 1 ” (However, R 1 is a hydrogen atom or A is an aryl group; 1 is a monovalent group having an alkoxysilyl group. a modification step of reacting a compound [M] having the formula The present invention relates to a method for producing a modified conjugated diene polymer comprising the steps of:

2. The compound [M] is a compound represented by the following formula (A): A method for producing the modified conjugated diene polymer according to claim 1. 【Chemistry 1】 (In formula (A), R 2 and R 3 are each independently a hydrocarbyl group having 1 to 20 carbon atoms. R 4 is an alkanediyl group having 1 to 20 carbon atoms; A 2 is the group "*-C(R 1 ) = N -" or the group "*-N=C(R 1 ) -" (However, R 1 is a hydrogen atom or a hydrocarbyl group. and "*" is R 5 ) indicates that the bond is bonded to the atom. R 5 represents an m-valent hydrocarbyl group having 1 to 20 carbon atoms, or a nitrogen atom, an oxygen atom, and a sulfur atom A carbon having at least one atom selected from the group consisting of atoms and having no active hydrogen. It is a group having a valence of m, which is a prime number from 1 to 20. n is an integer from 1 to 3, and m is an integer from 2 to 10. In formula (A), a plurality of R 2 , R 3 , R 4 , A 2 , n may be the same or different.

3. The styrene derivative is a compound represented by the following formula (1) and / or the following formula (2): 、 A method for producing the modified conjugated diene polymer according to claim 1 or 2. 【Chemistry 2】 【Chemistry 3】 (In formulas (1) and (2), Q 1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a group having 6 aryl group having a branched structure in a portion thereof. It is okay to do so. X 1 , X 2 , X 3 is a single bond or a group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen. It is an organic group containing any of the following: Y 1 , Y 2 , Y 3 represents an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and and halogen atoms. may be the same or different.)

4. In the formula (1), Q 1 is a hydrogen atom, and Y 1 represents an alkyl group having 1 to 20 carbon atoms, 1 to 20 alkoxy groups, and halogen atoms. A method for producing the modified conjugated diene polymer according to claim 3.

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

6. In the formula (2), Y 2 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom; Y 3 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom, A method for producing a diene polymer.

7. In the formula (1), Q 1 is a hydrogen atom, and Y 1 is an alkoxy group having 1 to 20 carbon atoms; A method for producing the modified conjugated diene polymer according to claim 3.

8. In the formula (1), Q 1 is a hydrogen atom, and X 1 is a single bond, and Y 1 is a compound with 1 to 20 carbon atoms The method for producing a modified conjugated diene polymer according to claim 3, wherein the group is an alkoxy group.

9. 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 halo group X is a 3 is a single bond, and Y 3 is an alkoxy group having 1 to 20 carbon atoms or a halogen atom. The method for producing a modified conjugated diene polymer according to claim 3, wherein the aryl group is a fluorine atom.

10. A modified conjugated diene polymer is obtained by the production method according to any one of claims 1 to 9. and obtaining a rubber component containing 10% by mass or more of the modified conjugated diene polymer; A filler is contained in an amount of 5.0 parts by mass or more and 150 parts by mass or less based on 100 parts by mass of the rubber component. to obtain a rubber composition; The method for producing a rubber composition comprising the steps of:

11. Obtaining a rubber composition by the method for producing a rubber composition according to claim 10; molding the rubber composition to obtain a tire; A tire manufacturing method comprising the steps of:

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