JP2023144766A - Method for producing branched conjugated diene polymer, branched conjugated diene polymer, rubber composition, method for producing rubber composition, and method for producing tire - Google Patents

Abstract

To provide a method for producing a branched conjugated diene polymer that can constitute a rubber composition with excellent performance such as low fuel consumption, wear resistance, wet skid resistance, and fracture strength.SOLUTION: A method for producing a branched conjugated diene polymer comprises a polymerization step of obtaining a conjugated diene polymer having an active end, and a branching step of introducing a branched structure by reacting the active end of the conjugated diene polymer with a nitrogen atom-containing branching agent which is a compound represented by Formula (1), where R1 to R2 represent alkyl groups or the like, X1 is an organic group, and Y1 represents an alkyl group or the like.SELECTED DRAWING: None

Description

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

BACKGROUND ART There has been an increasing demand for lower fuel consumption for automobiles from the viewpoint of environmental impact. In particular, for automobile tires, there is a demand for improved fuel efficiency for the materials used in the tread portions that are in direct contact with the ground.
In recent years, there has been a demand for the development of materials with low rolling resistance, that is, low hysteresis loss.
Furthermore, there is a need to reduce the weight of tires, and there is a need to reduce the thickness of the tire tread and to use a material with high wear resistance for the tire tread.
On the other hand, from the viewpoint of safety, materials used for tire treads are required to have excellent wet skid resistance and to have practically sufficient breaking characteristics.

Rubber materials containing a rubber-like polymer and a reinforcing filler such as carbon black or silica are examples of materials that meet the various demands described above.
By using a rubber material containing silica, it is possible to improve the balance between low hysteresis loss (an indicator of fuel efficiency) and wet skid resistance. In addition, by introducing a functional group that has affinity or reactivity with silica into the molecular end of a highly mobile rubber-like polymer, the dispersibility of silica in the rubber material is improved, and furthermore, the dispersibility of silica is improved. By bonding with particles, the mobility of the molecular ends of the rubbery polymer can be reduced, and hysteresis loss can be reduced.
On the other hand, a method for improving wear resistance includes increasing the molecular weight of the rubbery polymer. However, when the molecular weight of the rubbery polymer is increased, the processability when kneading the rubbery polymer and reinforcing filler tends to deteriorate.
In view of these circumstances, attempts have been made to introduce branched structures into rubber-like polymers in order to increase the molecular weight without impairing processability.

For example, a resin composition of silica and a modified conjugated diene polymer obtained by reacting an alkoxysilane containing an amino group with the active end of a conjugated diene polymer has been proposed.
Furthermore, modified conjugated diene polymers have been proposed in which a branched structure obtained by coupling a polymer active end with a polyfunctional silane compound is introduced (see, for example, Patent Documents 1 and 2).
Furthermore, a technique has also been proposed in which a styrene derivative is used as a branching agent to introduce a branched structure into the main chain (see, for example, Patent Document 3).

International Publication No. 2007/114203 pamphlet International Publication No. 2016/133154 pamphlet International Publication No. 2020/070961 pamphlet

However, in the method of introducing a branched structure into a conjugated diene polymer, which involves coupling reaction between a polymer active end and a polyfunctional silane compound, as disclosed in Patent Documents 1 and 2, the modified conjugated diene obtained thereby The degree of branching of the system polymer largely depends on the number of groups that the polyfunctional silane compound has that can react with the active end of the polymer, and does not exceed the number of groups that can react with the active end of the polymer. From the viewpoint of synthesis possibilities, there is a limit to the number of reactive groups that can be added to a single polyfunctional silane, so there is a problem that there is also a limit to the degree of branching of the resulting modified conjugated diene polymer. are doing.
In addition, in the technology disclosed in Patent Document 3 that utilizes a styrene derivative as a branching agent to introduce a branched structure into the main chain, the introduction of nitrogen atoms depends on the progress of the modification reaction, so the resulting modified conjugated diene There is also a limit to the improvement in the modification rate of the polymer, and there are problems in that the introduction position of nitrogen atoms cannot be freely adjusted.

Therefore, in the present invention, it is possible to produce a conjugated diene polymer with a higher degree of branching and nitrogen content than when a branched structure is introduced into a conjugated diene polymer using only a coupling agent. It is an object of the present invention to provide a method for producing a branched conjugated diene polymer with a high degree of freedom in polymer design, which can introduce nitrogen atoms into the main chain and improve the modification rate compared to when a styrene derivative is used as an agent. The object of the present invention is to provide a method for producing a branched conjugated diene polymer having excellent fuel efficiency, abrasion resistance, wet skid resistance, and fracture strength.

As a result of intensive research and study in order to solve the above-mentioned problems of the prior art, the present inventors reacted a nitrogen atom-containing branching agent to a conjugated diene polymer to add branch points and nitrogen atoms to the main chain. It has been discovered that by simultaneously introducing the two, a branched conjugated diene polymer capable of solving the above-mentioned conventional problems can be obtained, and the present invention has been completed.
That is, the present invention is as follows.

[1]
By polymerizing or copolymerizing a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound using an alkali metal compound or an alkaline earth metal compound as a polymerization initiator, a conjugated diene polymer having an active end can be produced. a polymerization step to obtain;
A branching step of introducing a branched structure by reacting a nitrogen atom-containing branching agent, which is a compound represented by the following formula (1), with the active end of the conjugated diene polymer;
have,
A method for producing a branched conjugated diene polymer.

(In formula (1), R ¹ to R ² each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms.
X ¹ is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen.
Y ¹ represents one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be independent and the same, or may be different. )

[2]
The method for producing a branched conjugated diene polymer according to [1] above, further comprising a step of adding a conjugated diene compound and/or an aromatic vinyl compound to the reaction system during and/or after the branching step. .
[3]
The branching according to [1] or [2] above, further comprising a reaction step of reacting a coupling agent or a polymerization terminator with the active end of the branched conjugated diene polymer obtained in the branching step. A method for producing a conjugated diene polymer.
[4]
The method for producing a branched conjugated diene polymer according to [3] above, wherein the coupling agent has a nitrogen atom-containing group.
[5]
The method for producing a branched conjugated diene polymer according to [3] above, wherein the polymerization terminator has a nitrogen atom-containing group.
[6]
The method for producing a branched conjugated diene polymer according to any one of [3] to [5] above, wherein the polymerization terminator is an alkoxy compound having a nitrogen atom-containing group.
[7]
A branched conjugated diene polymer obtained by the method for producing a branched conjugated diene polymer according to any one of [1] to [6] above, wherein the polymer main chain contains the formula (1). A branched conjugated diene polymer having a main chain branched structure derived from a nitrogen atom-containing branching agent, which is the represented compound.

(In formula (1), R ¹ to R ² each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms.
X ¹ is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen.
Y ¹ represents one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be independent and the same, or may be different. )

[8]
A rubber component containing 10% by mass or more of the branched conjugated diene polymer described in [7] above, and 5.0 parts by mass or more and 150 parts by mass or less of a filler, based on 100 parts by mass of the rubber component. rubber composition.
[9]
Obtaining a branched conjugated diene polymer by the production method described in any one of [1] to [6] above;
obtaining a rubber component containing 10% by mass or more of the branched conjugated diene polymer;
A step of containing a filler in an amount of 5.0 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the rubber component to obtain a rubber composition;
A method for producing a rubber composition, comprising:
[10]
A method for producing a tire, comprising the steps of obtaining a rubber composition by the method for producing a rubber composition according to [9] above, and molding the rubber composition to obtain a tire.

According to the present invention, a branched conjugated diene polymer having a high degree of branching, a high nitrogen content, and a high modification rate can be produced. Further, it is possible to provide a method for producing a branched conjugated diene polymer that can constitute a rubber composition with excellent performance such as fuel efficiency, abrasion resistance, wet skid resistance, and fracture strength.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "this embodiment") will be described in detail.
Note that the following embodiment is an illustration for explaining the present invention, and the present invention is not limited to the following embodiment. The present invention can be implemented with appropriate modifications within the scope of its gist.

[Method for producing branched conjugated diene polymer]
The method for producing the branched conjugated diene polymer of this embodiment is as follows:
By polymerizing or copolymerizing a conjugated diene compound, or a conjugated diene compound and an aromatic vinyl compound using an alkali metal compound or an alkaline earth metal compound as a polymerization initiator, a conjugated diene polymer having an active end can be obtained. a polymerization step to obtain
A branching step of introducing a branched structure by reacting a nitrogen atom-containing branching agent, which is a compound represented by the following formula (1), with the active end of the conjugated diene polymer;
has.

(In formula (1), R ¹ to R ² each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms.
X ¹ is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen.
Y ¹ represents one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be independent and the same, or may be different. )

The branched conjugated diene polymer obtained by the production method of the present embodiment is a homopolymer of a single conjugated diene compound, a polymer or copolymer of different types of conjugated diene compounds, a conjugated diene compound and an aromatic vinyl It may be any copolymer with a compound.
According to the method for producing a branched conjugated diene polymer of the present embodiment, by simultaneously introducing a branch point and a nitrogen atom into the main chain, a branched structure is created in the conjugated diene polymer using only a coupling agent. It is possible to produce a branched conjugated diene polymer with a higher degree of branching and nitrogen content than when it is introduced, and the length of the main chain and side chain can be easily adjusted, increasing the degree of freedom in polymer design. Furthermore, according to the present invention, it is possible to produce a branched conjugated diene polymer that provides a rubber composition with excellent fuel efficiency, abrasion resistance, wet skid resistance, and fracture strength.

(Polymerization process)
In the polymerization step in the method for producing a branched conjugated diene polymer of this embodiment, an alkali metal compound or an alkaline earth metal compound is used as a polymerization initiator, and a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound are used. By polymerizing or copolymerizing, a conjugated diene polymer having an active terminal is obtained.
In the polymerization step, it is preferable to perform polymerization by a growth reaction based on a living anion polymerization reaction, whereby a conjugated diene polymer having an active terminal can be obtained.

<Polymerization initiator>
As the polymerization initiator, an alkali metal compound or an alkaline earth metal compound is used.
Examples of the alkali metal compound include organic lithium compounds, and it is preferable to use organic monolithium compounds.
Examples of alkaline earth metal compounds include organic magnesium compounds, organic calcium compounds, and organic strontium compounds. Also included are alkaline earth metal alkoxide, sulfonate, carbonate, and amide compounds.
Examples of the organic monolithium compound include, but are not limited to, low molecular weight compounds and solubilized oligomeric organic monolithium compounds.
Regarding the organic monolithium compound, in terms of the bonding mode between the organic group and the lithium, for example, any of compounds having a carbon-lithium bond, a compound having a nitrogen-lithium bond, and a compound having a tin-lithium bond may be used. I can do it.

The amount of the polymerization initiator to be used is preferably determined depending on the molecular weight of the conjugated diene polymer to be produced in the polymerization step.
The amount of monomer such as a conjugated diene compound used relative to the amount of polymerization initiator used is related to the degree of polymerization of the targeted conjugated diene polymer. That is, it tends to be related to 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 polymerization initiator may be decreased, and in order to decrease the molecular weight, the amount of polymerization initiator may be increased.

The organic monolithium compound is preferably an alkyllithium compound having a substituted amino group or dialkylaminolithium from the viewpoint of being used as a method for introducing a nitrogen atom into a conjugated diene polymer.
In this case, a conjugated diene polymer having a nitrogen atom consisting of an amino group at the polymerization initiation terminal is obtained.

A 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 without active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexyllithium. Methyleneiminobutyllithium is mentioned.
Examples of the alkyllithium compound having an amino group with a protected active hydrogen structure include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

Examples of the dialkylamino lithium include, but are not limited to, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium di-n-hexylamide, lithium diheptylamide, lithium diisopropylamide, lithium dioctylamide, and lithium. -di-2-ethylhexylamide, lithium didecylamide, lithium ethylpropylamide, lithium ethylbutyramide, lithium ethylbenzylamide, lithium methylphenethylamide, lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium hepta Methyleneimide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithio-1,2,3, 6-tetrahydropyridine is mentioned.

These organic monolithium compounds having substituted amino groups are made by reacting a small amount of a polymerizable monomer, such as 1,3-butadiene, isoprene, or styrene, to make them solubilized in n-hexane or cyclohexane. It can also be used as an oligomeric organomonolithium compound.

The organic monolithium compound is preferably an alkyllithium compound from the viewpoint of ease of industrial availability and ease of control of the polymerization reaction. In this case, a conjugated diene polymer having an alkyl group at the polymerization initiation terminal is obtained.
Examples of the alkyllithium compound include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium.
As the alkyllithium compound, n-butyllithium and sec-butyllithium are preferred from the viewpoint of industrial availability and ease of controlling the polymerization reaction.

These organic monolithium compounds may be used alone or in combination of two or more. Further, as a polymerization initiator, it may be used in combination with other organometallic compounds.
Other organometallic compounds include, for example, alkaline earth metal compounds, other alkali metal compounds, and other organometallic compounds.
Examples of the alkaline earth metal compound include, as described above, an organic magnesium compound, an organic calcium compound, and an organic strontium compound. Also included are alkaline earth metal alkoxide, sulfonate, carbonate, and amide compounds.
Examples of organomagnesium compounds include dibutylmagnesium and ethylbutylmagnesium.
Examples of other organometallic compounds include organoaluminum compounds.

In the polymerization process, the polymerization reaction mode is not limited to the following, but includes, for example, a batch type (also referred to as a "batch type") and a continuous type polymerization reaction mode.
In continuous mode, one or more connected reactors can be used. As the continuous reactor, for example, a tank type or a tube type with a stirrer is used. In the continuous system, preferably, a monomer, an inert solvent, and a polymerization initiator are continuously fed into a reactor, a polymer solution containing a polymer is obtained in the reactor, and the polymerization is continuously carried out. The coalescent solution is drained.
As the batch reactor, for example, a tank type reactor equipped with a stirrer is used. In the batch system, preferably the monomer, inert solvent, and polymerization initiator are fed, and if necessary, the monomer is added continuously or intermittently during the polymerization to form the polymer in the reactor. A polymer solution containing the polymer is obtained, and the polymer solution is discharged after the polymerization is completed.
In the method for producing a branched conjugated diene polymer of the present embodiment, in order to obtain a conjugated diene polymer having a high proportion of active terminals in the polymerization step, the polymer is continuously discharged in a short period of time. A continuous type is preferable because it can be used for the next reaction. In the continuous system, the number of reactors is not particularly limited, and one or more reactors connected together can be used. The reactor is preferably one that allows sufficient contact between the monomer and the polymerization initiator in a solution, and preferably a tank type, tube type, or the like with a stirrer is used. Although the number of reactors can be selected as appropriate, one reactor is preferable from the perspective of saving space in production equipment, and two or more reactors are preferable from the perspective of improving productivity. When using two or more reactors, it is more preferable to add the branching agent to the second reactor or later.

In the polymerization step of the conjugated diene polymer, it is preferable to polymerize the monomers in an inert solvent.
Examples of the inert solvent include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Examples of hydrocarbon solvents include, but are not limited to, aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; benzene, Examples include aromatic hydrocarbons such as toluene and xylene, and hydrocarbons consisting of mixtures thereof.
By treating impurities such as arenes and acetylenes with an organometallic compound before subjecting the inert solvent to the polymerization reaction, a conjugated diene polymer with a high concentration of active terminals tends to be obtained. This is preferable because a conjugated diene polymer with a modified modification rate tends to be obtained.

In the polymerization step, a polar compound (polar substance) may be added. Thereby, the aromatic vinyl compound can be randomly copolymerized with the conjugated diene compound. Polar compounds also tend to be able to be used as vinylating agents to control the microstructure of the conjugated diene moieties. Furthermore, they tend to be effective in promoting polymerization reactions.
Examples of polar compounds include, but are not limited to, tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, 2,2-bis(2-oxolanyl)propane. Tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, quinuclidine; Potassium-tert-amylate, potassium-tert-butyrate, sodium-tert-butyrate, sodium amine Alkali metal alkoxide compounds such as lat; phosphine compounds such as triphenylphosphine, etc. can be used.
These polar compounds may be used alone or in combination of two or more.

The amount of the polar compound to be used is not particularly limited and can be selected depending on the purpose, etc., but it is preferably 0.01 mol or more and 100 mol or less with respect to 1 mol of the polymerization initiator.
Such a polar compound also has a function as a vinylating agent, and can be used in an appropriate amount depending on the desired amount of vinyl bonds as an agent for adjusting the microstructure of the conjugated diene moiety of the conjugated diene polymer.
Many polar compounds simultaneously have an effective randomizing effect in the copolymerization of conjugated diene compounds and aromatic vinyl compounds, and can adjust the distribution of aromatic vinyl monomer units and the amount of aromatic vinyl monomer blocks. It tends to be able to be used as a regulator of
As a method of randomizing the conjugated diene compound and the aromatic vinyl compound, for example, as described in JP-A-59-140211, the total amount of styrene and a part of 1,3-butadiene are combined. A method may be used in which the polymerization reaction is started and the remaining 1,3-butadiene is added intermittently during the copolymerization reaction.

The polymerization temperature in the polymerization step is preferably a temperature at which living anion polymerization proceeds, and from the viewpoint of productivity, it is more preferably 0° C. or higher and 120° C. or lower.
By falling within this range, it tends to be possible to ensure a sufficient amount of the branching agent or coupling agent to be described later to react with the active end of the conjugated diene polymer after the polymerization step is completed. More preferably, the temperature is 50°C or more and 100°C or less.

The conjugated diene polymer obtained by the polymerization step is a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound.

<Conjugated diene compound>
The conjugated diene compound is not particularly limited as long as it is a polymerizable monomer, and examples include, but are not limited to, 1,3-butadiene, isoprene, 2,3-dimethyl-1, Examples include 3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-heptadiene, and 1,3-hexadiene. Among these, 1,3-butadiene and isoprene are preferred from the viewpoint of industrial availability. These may be used alone or in combination of two or more.

<Aromatic vinyl compound>
The aromatic vinyl compound may be any monomer copolymerizable with a conjugated diene compound, and is not particularly limited, but examples include styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinyl Examples include xylene, vinylnaphthalene, diphenylethylene, and the like. Among these, styrene is preferred from the viewpoint of industrial availability. These may be used alone or in combination of two or more.

(branching process)
In the method for producing a branched conjugated diene polymer of the present embodiment, a compound represented by the following formula (1) is added as a branching agent to the active end of the conjugated diene polymer obtained in the polymerization step. A branching step is carried out in which a certain nitrogen atom-containing branching agent is reacted.
While the branching agent maintains its polymerization activity and polymerizes with the monomer, the active end of another polymer chain reacts with the functional group of the branching agent, thereby forming a branched structure in the polymer.
By polymerizing and reacting the conjugated diene polymer into which a branched structure has been introduced with a monomer and a branching agent, it is also possible to form a further branched structure, and as described later, it is possible to form a further branched structure. It is also possible to make a modified conjugated diene polymer by reacting with a modifier, or to further extend the polymer chain by coupling.
In this embodiment, by producing a branched conjugated diene polymer using a branching agent, the branched conjugated diene polymer has a moiety derived from a compound represented by the following formula (1). Become what you have.
In this specification, "a moiety derived from the compound represented by formula (1)" is a skeleton in which a nitrogen atom is connected to a diphenylethylene skeleton and has a plurality of alkoxysilyl groups.

<Branching agent>
The nitrogen atom-containing branching agent used in the branching process has a main skeleton with only one active terminal remaining at the branching site after the branching reaction, from the viewpoint of continuity of polymerization and prevention of gelation. It is preferable that there be one, and it is further preferable that it has reactivity to sufficiently react with the polymerization active terminal during the branching reaction.
In other words, as the branching agent reacts, the nitrogen atom-containing branching agent is incorporated into the main chain while maintaining polymerization activity, and another monomer is polymerized at the end where the activity is maintained, further increasing the polymer chain. extend. In addition, the active ends of other polymer chains react with the incorporated functional groups of the nitrogen atom-containing branching agent to form bonds, thereby forming a branched structure. As this reaction occurs repeatedly, the branching of the polymer chain increases, the polymer structure becomes more complex, and the molecular weight becomes larger.
From the viewpoint of continuity of polymerization and controllability of polymer structure, it is also necessary that the functional group, which is eliminated after reacting with the active end of another polymer chain, has little effect of inhibiting polymerization. Here, "polymerization inhibiting effect is small" means that side reactions of anionic polymerization such as chain transfer reaction, deactivation during polymerization, and decrease in activity due to increase in the degree of association of the polymer are small.
The functional group possessed by the nitrogen atom-containing branching agent needs to be one that does not excessively improve the polymerization activity, and further needs to be one that does not deactivate the polymerization activity. When polymerizing a polymer by living anionic polymerization, it is important that it does not have a hydrogen atom as a functional group that does not deactivate the active end, and that it is a hard base according to the definition based on Pearson's HASB rule. A specific example of such a functional group is an alkoxy group. Among these, the structure of the nitrogen atom-containing branching agent used in the production method of this embodiment was selected from the viewpoint of reactivity with the active end and that the detached functional group does not inhibit polymerization. You can choose.
More specifically, it is preferable to use the following formula (1) as a nitrogen atom-containing branching agent from the viewpoint of suppressing chain transfer reaction, suppressing deactivation of active terminals, and preventing gelation.

(In formula (1), R ¹ to R ² each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms.
X ¹ is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen.
Y ¹ represents one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be independent and the same, or may be different. )

Examples of the nitrogen atom-containing branching agent represented by the above formula (1) include, but are not limited to, compounds represented by each of the following formulas (M-1) to (M-6). It will be done.
In addition, the nitrogen atom-containing branching agents may be used alone or in combination of two or more.

<Example of nitrogen atom-containing branching agent used in the branching process>
Specific examples of nitrogen atom-containing branching agents are shown in the following formulas (M-1) to (M-6).
In addition, in the formula, Me represents a methyl group, and Et represents an ethyl group.

The timing of adding the nitrogen atom-containing branching agent is not particularly limited and can be selected depending on the purpose, etc., but from the viewpoint of increasing the absolute molecular weight of the conjugated diene polymer and improving the coupling rate, After adding the agent, the timing is preferable when the raw material conversion rate 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%. It is even more preferable that the condition is above.
Further, during and/or after the branching step, a monomer as a desired raw material may be further added, and the polymerization step may be continued after the branching step, or the above description may be repeated.
In addition, here, after the branching step shall be after adding the nitrogen atom-containing branching agent.
The monomer to be added is not particularly limited, but is preferably a conjugated diene compound and/or an aromatic vinyl compound. In particular, when adding a monomer during the branching step, it is preferable to add a monomer at the branching point of the conjugated diene polymer. From the viewpoint of improving the modification rate by alleviating steric hindrance, the total amount of conjugated diene monomers used in the polymerization step, for example, the total amount of butadiene, is preferably 5% or more, more preferably 10% or more, and 15% or more. % or more, even more preferably 20% or more, even more preferably 25% or more. In such a case, it is particularly recommended to use a continuous polymerization process and add monomers during the branching process in an amount of 5% or more of the total amount of conjugated diene monomers used in the polymerization process, for example, the total amount of butadiene, in order to improve the modification rate. Preferable from this point of view.
The length of the main chain and side chain can be adjusted by adjusting the timing of adding the branching agent and the amount of monomer added, so there is a high degree of freedom in polymer design.

The branched structure of the branched conjugated diene polymer obtained in the branching step in the method for producing a branched conjugated diene polymer of the present embodiment is preferably 2 branches or more and 8 branches or less, more preferably 3 branches. The number of branches is greater than or equal to 6, and more preferably the number of branches is greater than or equal to 4 and less than or equal to 5.
By having 8 branches or less, it tends to be easier to react with a modifier having a functional group to form a modified conjugated diene polymer, or to further extend the polymer chain through a coupling reaction. By doing so, the branched conjugated diene polymer obtained tends to have excellent processability and wear resistance.

The amount of branching agent added in the branching step is not particularly limited, and can be selected depending on the purpose, etc., but it can improve the terminal termination reaction rate of the conjugated diene polymer, improve the coupling rate, From the viewpoint of continuity of polymerization after branching, the molar ratio of the branching agent to the amount of active polymerization initiator is 1/2 or less, preferably 1/100 or more, and 1/3 or less. It is more preferably 1/50 or more, more preferably 1/4 or less and 1/30 or more, even more preferably 1/6 or less and 1/25 or more, and even more preferably 1/8 or less. Even more preferably 1/12 or more.

Further, as described above, a monomer may be further added during and/or after the branching step, and the polymerization step may be continued after branching, or a branching agent may be further added after the additional monomer is added. , the addition of monomers may be repeated.
By adding a monomer, steric hindrance around the branch point is alleviated, thereby improving the continuity of polymerization and increasing the coupling rate and modification rate. Thereby, branches can be formed at desired positions while increasing the molecular weight of the polymer.
The monomer to be added may be an aromatic vinyl such as styrene, a conjugated diene compound such as butadiene, or a mixture thereof, and may be the same or different from the type and ratio of the monomers initially polymerized, but depending on the continuity of the polymerization. From this point of view, conjugated diene compounds are preferred. Further, from the viewpoint of improving the heat resistance of the polymer, it is preferable to add an aromatic vinyl compound.

The branched conjugated diene polymer containing a nitrogen atom into which a branched structure is introduced, which is obtained in the branching step in the production method of the present embodiment, has a Mooney viscosity of 10 to 150 when measured at 110°C. is preferable, more preferably 15 or more and 140 or less, still more preferably 20 or more and 130 or less, even more preferably 30 or more and 100 or less.
When the Mooney viscosity is within the above range, the branched conjugated diene polymer obtained by the production method of this embodiment tends to have excellent processability and wear resistance.

The weight average molecular weight of the branched conjugated diene polymer containing a nitrogen atom into which a branched structure is introduced, 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, and preferably 100,000 or more. It is more preferably 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 branched conjugated diene polymer obtained by the production method of the present embodiment tends to have excellent processability, abrasion resistance, and a balance of these properties.
When producing a branched conjugated diene polymer to which a modifying agent has been added, in order to ensure that the weight average molecular weight after modification reaches a range of 100,000 to 1,000,000, the amount of nitrogen atom-containing branching agent added must be adjusted. By controlling the molar ratio to the polymerization initiator in a range of 1/3 or less and 1/50 or more, it is possible to form branches while preventing the polymerization initiator from being completely consumed before the coupling step. It is necessary to increase the number of functional groups of the coupling agent to two or more functional groups while also preventing the addition of a nitrogen atom-containing branching agent. It is necessary to control the number of functional groups in the coupling agent to be 3 or more functional groups while controlling the molar ratio to be 1/3 or less and 1/50 or more relative to the coupling agent.

The branched conjugated diene polymer obtained by the production method of this embodiment may be a polymer of a conjugated diene compound and a nitrogen atom-containing branching agent, or a polymer of an aromatic vinyl compound, a conjugated diene compound, and a nitrogen atom. It may be a polymer with a branching agent contained therein, or a copolymer of these and other monomers.
For example, when the conjugated diene compound is butadiene or isoprene, and this is polymerized with a nitrogen atom-containing branching agent containing an aromatic vinyl moiety, the polymer chain is so-called polybutadiene or polyisoprene, and the branched moiety is derived from aromatic vinyl. It becomes a polymer containing structure. By having such a structure, it is possible to improve the linearity of each polymer chain and the crosslinking density after vulcanization, which has the effect of improving the wear resistance of the polymer. Therefore, it is suitable for applications such as tires, resin modification, interior and exterior parts of automobiles, anti-vibration rubber, and footwear.
When using a branched conjugated diene polymer for tire tread applications, a copolymer of a conjugated diene compound, an aromatic vinyl compound, and a nitrogen atom-containing branching agent is suitable; The amount of diene monomer is preferably 40% by mass or more and 100% by mass or less, more preferably 55% by mass or more and 80% by mass or less.
Further, the amount of bonded aromatic vinyl monomer in the branched conjugated diene polymer obtained by the production method of the present embodiment is not particularly limited, but is preferably 0% by mass or more and 60% by mass or less, and 20% by mass or less. More preferably, it is at least 45% by mass.
When the amount of bonded conjugated diene monomer and the amount of bonded aromatic vinyl monomer are within the above ranges, the balance between low hysteresis loss property and wet skid resistance, abrasion resistance, and fracture characteristics when made into a vulcanized product are improved. It tends to be better.
Here, the amount of bound aromatic vinyl monomer can be measured by ultraviolet absorption of the phenyl group, and from this, the amount of bound conjugated diene monomer can also be determined. Specifically, it can be measured according to the method described in Examples described later.

In the branched conjugated diene polymer obtained by the production method of the present 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 20 mol%. % or more and 65 mol% or less.
When the amount of vinyl bonds is within the above range, the vulcanized product tends to have a better balance between low hysteresis loss and wet skid resistance, abrasion resistance, and fracture strength.
Here, when the conjugated diene polymer is a copolymer of butadiene and styrene, the butadiene bonding units are separated by Hampton's method (R.R. Hampton, Analytical Chemistry, 21, 923 (1949)). The vinyl bond amount (1,2-bond amount) can be determined. Specifically, it can be measured by the method described in Examples below.

Regarding the microstructure of the conjugated diene polymer, the amount of vinyl bonds, the amount of bonded aromatic vinyl monomer, and the amount of bonded conjugated diene monomer in the branched conjugated diene polymer obtained by the production method of this embodiment are as follows. When the numerical value is within the above-mentioned range and the glass transition temperature of the conjugated diene polymer is in the range of -80°C or higher and -15°C or lower, the balance between low hysteresis loss property and wet skid resistance is even more excellent. vulcanizates tend to be obtained.
Regarding the glass transition temperature, according to ISO 22768:2006, a DSC curve is recorded while increasing the temperature in a predetermined temperature range, and the peak top (inflection point) of the DSC differential curve is taken as the glass transition temperature.

When the branched conjugated diene polymer obtained by the production method of the present embodiment is a conjugated diene-aromatic vinyl copolymer, the branched conjugated diene polymer has 30 aromatic vinyl monomer units. It is preferable that the number of blocks that are chained is small or non-existent. More specifically, when the branched conjugated diene polymer obtained by the production method of this embodiment is a butadiene-styrene copolymer, the method of Kolthoff (IM. KOLTHOFF, et al., J. Polym. Sci. 1, 429 (1946)) and analyzes the amount of polystyrene insoluble in methanol. , based on the total amount of the branched conjugated diene polymer, preferably 5.0% by mass or less, more preferably 3.0% by mass or less.

In the branched conjugated diene polymer obtained by the production method of the present embodiment, from the viewpoint of improving fuel efficiency, it is preferable that the proportion of aromatic vinyl monomer units present alone is large.
Specifically, when the branched conjugated diene polymer obtained by the production method of this embodiment is a butadiene-styrene copolymer, the method known as Tanaka et al. (Polymer, 22, 1721 (1981)) is used. When the conjugated diene polymer was decomposed using an ozonolysis method and the styrene chain distribution was analyzed by GPC, it was found that the amount of isolated styrene was 40% by mass or more based on the total amount of bound styrene, and the styrene chains were The content of chain styrene structures of 8 or more is preferably 5.0% by mass or less.
In this case, the resulting vulcanized rubber tends to exhibit excellent performance with particularly low hysteresis loss.

(Reaction process)
In the method for producing a branched conjugated diene polymer of the present embodiment, a coupling agent, for example 3 A step of performing coupling using a reactive compound with a functional level or higher, or a step of reacting a polymerization terminator, such as a reactive compound with a functional level or lower, with the active end of a branched conjugated diene polymer. is preferred.
Hereinafter, the process of reacting a coupling agent (coupling process) or the process of reacting polymerization termination (polymerization termination process) will be collectively referred to as a reaction process.
In the reaction step, one active end of the branched conjugated diene polymer is reacted with a coupling agent or a polymerization terminator.

<Step of reacting the coupling agent>
In the method for producing a branched conjugated diene polymer according to the present embodiment, as a reaction step, the branched conjugated diene polymer obtained through the above-mentioned polymerization step and branching step is coupled with a coupling agent. It is preferable to have a ring process.
By efficiently lengthening the molecular chain through the coupling step, branches can also be introduced into the polymer by employing a trifunctional or more functional coupling agent. The function of introducing branching is common to the process of using branching agents, but by performing it in the coupling process, desired elements such as nitrogen, sulfur, silicon, etc. can be introduced using known coupling agents. This is preferable from the viewpoint of being able to form branches.
The coupling step is, for example, a coupling step performed on the active end of the branched conjugated diene polymer using a trifunctional or higher functional reactive compound, or a coupling agent having a nitrogen atom-containing group ( The coupling step is preferably carried out using a coupling agent (hereinafter sometimes also referred to as a "coupling agent").

In the coupling step, for example, branching is performed by coupling reaction to one end of the active end of the conjugated diene polymer with a trifunctional or more reactive compound or a coupling agent having a nitrogen atom-containing group. A conjugated diene polymer can be obtained.

[Trifunctional or higher functional reactive compound]
In the method for producing a branched conjugated diene polymer of the present embodiment, the trifunctional or higher functional reactive compound used in the coupling step is preferably a trifunctional or higher functional reactive compound having a silicon atom.

Examples of the trifunctional or higher functional reactive compound having a silicon atom include, but are not limited to, halogenated silane compounds, epoxidized silane compounds, vinylated silane compounds, alkoxysilane compounds, alkoxysilane compounds containing nitrogen-containing groups, etc. can be mentioned.

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

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

Examples of the vinylated silane compound as a coupling agent include, but are not limited to, vinyltrimethoxysilane, vinyltriethoxysilane, and the like.

Examples of the alkoxysilane compound as a coupling agent include, but are not limited to, tetramethoxysilane, tetraethoxysilane, triphenoxymethylsilane, 1,2-bis(triethoxysilyl)ethane, methoxy-substituted polyorganosiloxane, etc. can be mentioned.

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

In the coupling agent having a nitrogen atom-containing group, the nitrogen atom-containing group is preferably a functional group derived from an amine compound having no active hydrogen, and the amine compound is, for example, a tertiary Examples include amine compounds and protected amine compounds in which the above-mentioned active hydrogen is substituted with a protecting group. Other compounds that can form a nitrogen atom-containing group include imine compounds represented by the general formula -N=C and alkoxysilane compounds bonded to the nitrogen atom-containing group.

Isocyanate compounds that are coupling agents having a nitrogen atom-containing group include, but are not limited to, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, and polymeric type. diphenylmethane diisocyanate (C-MDI), phenyl isocyanate, isophorone diisocyanate, hexamethylene diisocyanate, butyl isocyanate, 1,3,5-benzene triisocyanate, and the like.

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

Examples of the carbonyl compound which is a coupling agent having a nitrogen atom-containing group include, but are not limited to, 1,3-dimethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 1-Methyl-3-(2-methoxyethyl)-2-imidazolidinone, N-methyl-2-pyrrolidone, N-methyl-2-piperidone, N-methyl-2-quinolone, 4,4'-bis( diethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, methyl-2-pyridylketone, methyl-4-pyridylketone, propyl-2-pyridylketone, di-4-pyridylketone, 2-benzoylpyridine, N , N,N',N'-tetramethylurea, N,N-dimethyl-N',N'-diphenylurea, N,N-methyl diethylcarbamate, N,N-diethylacetamide, N,N-dimethyl- Examples include N',N'-dimethylaminoacetamide, N,N-dimethylpicolinic acid amide, and N,N-dimethylisonicotinic acid amide.

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

Examples of the epoxy compound which is a coupling agent having a nitrogen atom-containing group include, but are not limited to, epoxy group-containing hydrocarbon compounds bonded to an amino group, and epoxy group-containing hydrocarbon compounds bonded to an ether group. Compounds may also be mentioned. Examples of such epoxy compounds include, but are not limited to, the epoxy compounds represented by general formula (i).

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

The divalent or higher-valent hydrocarbon group is a saturated or unsaturated hydrocarbon group that may be linear, branched, or cyclic, and includes an alkylene group, an alkenylene group, a phenylene group, and the like. Preferably, it is a hydrocarbon group having 1 to 20 carbon atoms. For example, methylene, ethylene, butylene, cyclohexylene, 1,3-bis(methylene)-cyclohexane, 1,3-bis(ethylene)-cyclohexane, o-, m-, p-phenylene, m-, p-xylene, Examples include bis(phenylene)-methane.

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

In the formula (ii), R ¹ and R ² are defined in the same manner as R ¹ and R ² in the formula (i), and R ¹ and R ² may be the same or different.

As the epoxy compound which is a coupling agent having a nitrogen atom-containing group, one having an epoxy group-containing hydrocarbon group is preferable, and one having a glycidyl group-containing hydrocarbon group is more preferable.

Examples of the epoxy group-containing hydrocarbon group bonded to an amino group or an ether group include, but are not limited to, a glycidylamino group, a diglycidylamino group, or a glycidoxy group. A more preferred molecular structure is an epoxy group-containing compound having a glycidylamino group or a diglycidylamino group, and a glycidoxy group, such as a compound represented by the following general formula (iii).

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

The epoxy compound which is a coupling agent having a nitrogen atom-containing group is particularly preferably a compound having one or more diglycidylamino groups and one or more glycidoxy groups in the molecule.

Examples of the epoxy compound which is a coupling agent having a nitrogen atom-containing group include, but are not limited to, N,N-diglycidyl-4-glycidoxyaniline, 1-N,N-diglycidylaminomethyl-4- Glycidoxy-cyclohexane, 4-(4-glycidoxyphenyl)-(N,N-diglycidyl)aniline, 4-(4-glycidoxyphenoxy)-(N,N-diglycidyl)aniline, 4-(4-glycidyl)aniline sidoxybenzyl)-(N,N-diglycidyl)aniline, 4-(N,N'-diglycidyl-2-piperazinyl)-glycidoxybenzene, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane , N,N,N',N'-tetraglycidyl-m-xylene diamine, 4,4-methylene-bis(N,N-diglycidylaniline), 1,4-bis(N,N-diglycidylamino) Cyclohexane, N,N,N',N'-tetraglycidyl-p-phenylenediamine, 4,4'-bis(diglycidylamino)benzophenone, 4-(4-glycidylpiperazinyl)-(N,N-diglycidyl ) Aniline, 2-[2-(N,N-diglycidylamino)ethyl]-1-glycidylpyrrolidine, N,N-diglycidylaniline, 4,4'-diglycidyl-dibenzylmethylamine, N,N-di Examples include glycidylaniline, N,N-diglycidyl orthotoluidine, N,N-diglycidylaminomethylcyclohexane, and the like. Among these, particularly preferred are N,N-diglycidyl-4-glycidoxyaniline and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

Examples of alkoxysilane compounds that are coupling agents having a nitrogen atom-containing group include, but are not limited to, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropylmethyldimethoxysilane, and 3-diethylaminopropyltriethoxysilane. , 3-morpholinopropyltrimethoxysilane, 3-piperidinopropyltriethoxysilane, 3-hexamethyleneiminopropylmethyldiethoxysilane, 3-(4-methyl-1-piperazino)propyltriethoxysilane, 1-[3 -(triethoxysilyl)-propyl]-3-methylhexahydropyrimidine, 3-(4-trimethylsilyl-1-piperazino)propyltriethoxysilane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane , 3-(3-trimethylsilyl-1-hexahydropyrimidinyl)propyltrimethoxysilane, 3-dimethylamino-2-(dimethylaminomethyl)propyltrimethoxysilane, bis(3-dimethoxymethylsilylpropyl)-N-methylamine , bis(3-trimethoxysilylpropyl)-N-methylamine, bis(3-triethoxysilylpropyl)methylamine, tris(trimethoxysilyl)amine, tris(3-trimethoxysilylpropyl)amine, N,N , N',N'-tetra(3-trimethoxysilylpropyl)ethylenediamine, 3-isocyanatopropyltrimethoxysilane, 3-cyanopropyltrimethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl) )-1-Aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4- trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1- Phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-methyl-1-aza-2-silacyclo Pentane, 2,2-dimethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-dimethoxy-8-(N,N-diethylamino)methyl-1 , 6-dioxa-2-silacyclooctane and the like.

A protected amine compound that is a coupling agent having a nitrogen atom-containing group and can form a primary or secondary amine, and has an unsaturated bond and a protected amine in its molecule, but is not limited to the following: For example, 4,4'-vinylidenebis[N,N-bis(trimethylsilyl)aniline], 4,4'-vinylidenebis[N,N-bis(triethylsilyl)aniline], 4,4'-vinylidenebis[N,N-bis(triethylsilyl)aniline], [N,N-bis(t-butyldimethylsilyl)aniline], 4,4'-vinylidenebis[N-methyl-N-(trimethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N- (trimethylsilyl)aniline], 4,4'-vinylidenebis[N-methyl-N-(triethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N-(triethylsilyl)aniline], 4, 4'-vinylidenebis[N-methyl-N-(t-butyldimethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N-(t-butyldimethylsilyl)aniline], 1-[4 -N,N-bis(trimethylsilyl)aminophenyl]-1-[4-N-methyl-N-(trimethylsilyl)aminophenyl]ethylene, 1-[4-N,N-bis(trimethylsilyl)aminophenyl]-1 -[4-N,N-dimethylaminophenyl]ethylene and the like.

Examples of protected amine compounds that can form primary or secondary amines with a coupling agent having a nitrogen atom-containing group and that have an alkoxysilane and a protected amine in the molecule include, but are not limited to, the following: , for example, N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, (trimethylsilyl)aminopropylmethyldiethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane, N,N-bis(triethylsilyl)aminopropyl Methyldiethoxysilane, 3-(4-trimethylsilyl-1-piperazino)propyltriethoxysilane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane, 3-(3-trimethylsilyl-1-hexahydro) pyrimidinyl)propyltrimethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl) -1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethyl silylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2- silacyclopentane, 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N -(1-methylethylidene)-3-(triethoxysilyl)-1-propanamine, N-ethylidene-3-(triethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3- (triethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)-3-(triethoxysilyl)-1-propanamine, etc. )-3-(triethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, 3-(benzylideneamino)propyltrimethoxysilane , 3-(benzylideneamino)propyltrimethoxysilane, 3-(benzylideneamino)propyltriethoxysilane, 3-(benzylideneamino)propyltripropylsilane, and the like.

Particularly preferred alkoxysilane compounds which are coupling agents having a nitrogen atom-containing group include, but are not limited to, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, Tris(3-tripropoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-tripropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, methoxysilylpropyl)-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3 -Propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3- triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane) ) propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy- 1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexamethylenediamine, pentakis(3-trimethoxysilylpropyl)- Diethylenetriamine, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis(3- trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclo) pentane)propyl]-(3-trimethoxysilylpropyl)silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl) -1-sila-2-azacyclopentane)propyl]silane, 3-tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-trimethoxysilylpropane, 1 -[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 1-[3-( 2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 3,4,5-tris(3-trimethoxysilyl) propyl)-cyclohexyl-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]ether, (3-trimethoxysilylpropyl)phosphate, bis(3-trimethoxysilylpropyl)-[ 3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3- Trimethoxysilylpropyl) phosphate, and tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate.

<Branched conjugated diene polymer obtained through polymerization step, branching step, and reaction step>
In the method for producing a branched conjugated diene polymer of the present embodiment, the branched conjugated diene polymer obtained through the above-mentioned reaction step, particularly the step of reacting a coupling agent, has the following general formula (i) or , (A) to (C), which is derived from a compound having a nitrogen atom-containing group.

In the formula (i), R is a divalent or higher hydrocarbon group, a polar group containing oxygen such as ether, epoxy, or ketone, a polar group containing sulfur such as thioether or thioketone, a tertiary amino group, or an imino group. It is a divalent or higher organic group having at least one kind of polar group selected from nitrogen-containing polar groups such as Nitrogen groups.

The divalent or higher-valent hydrocarbon group is a saturated or unsaturated hydrocarbon group that may be linear, branched, or cyclic, and includes an alkylene group, an alkenylene group, a phenylene group, and the like. Preferably, it is a hydrocarbon group having 1 to 20 carbon atoms. For example, methylene, ethylene, butylene, cyclohexylene, 1,3-bis(methylene)-cyclohexane, 1,3-bis(ethylene)-cyclohexane, o-, m-, p-phenylene, m-, p-xylene, Examples include bis(phenylene)-methane.

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

In the formula (ii), R ¹ and R ² are defined in the same manner as R ¹ and R ² in the formula (i), and R ¹ and R ² may be the same or different.

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

(In formula (B), R ¹ to R ⁶ each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R ⁷ to R ⁹ each independently , represents an alkylene group having 1 to 20 carbon atoms.
m, n, and l each independently represent an integer of 1 to 3, and (m+n+l) represents an integer of 4 or more. When a plurality of R ¹ to R ⁶ exist, each of them is independent. )

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

Coupling agents having a nitrogen atom-containing group represented by formula (A) include, but are not limited to, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza- 2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)- 1-Aza-2-silacyclohexane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacycloheptane, 2,2-dimethoxy-1-(3-dimethoxymethylsilyl) propyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy,2-methyl-1 -(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-ethoxy,2-ethyl-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2 -methoxy,2-methyl-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, and 2-ethoxy,2-ethyl-1-(3-diethoxyethylsilylpropyl)-1 -aza-2-silacyclopentane.

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

The reaction temperature, reaction time, etc. when reacting the coupling agent having a nitrogen atom-containing group represented by the above formula (A) with the polymerization active terminal are not particularly limited, but at a temperature of 0°C or higher and 120°C or lower. , it is preferable to react for 30 seconds or more.

The total number of moles of alkoxy groups bonded to silyl groups in the compound of the coupling agent having a nitrogen atom-containing group represented by formula (A) is the same as that of the alkali metal compound and/or alkaline earth metal compound of the polymerization initiator. The number of moles added is preferably in a range of 0.6 times or more and 3.0 times or less, more preferably 0.8 times or more and 2.5 times or less, and 0.8 times or more and 2.5 times or less. It is more preferable to be within a range of .0 times or less. From the viewpoint of obtaining a sufficient modification rate, molecular weight, and branched structure of the resulting branched conjugated diene polymer, it is preferable that the ratio is 0.6 times or more, and the polymer terminals are coupled to each other in order to improve processability. In addition to it being preferable to obtain a branched conjugated diene polymer component, from the viewpoint of coupling agent cost, it is preferable to make it 3.0 times or less.

The number of moles of the polymerization initiator is preferably 3.0 times or more, more preferably 4.0 times the mole of the coupling agent having a nitrogen atom-containing group represented by formula (A) above. That's all.

Coupling agents having a nitrogen atom-containing group represented by the formula (B) include, but are not limited to, for example, tris(3-trimethoxysilylpropyl)amine, tris(3-methyldimethoxysilylpropyl)amine , tris(3-triethoxysilylpropyl)amine, tris(3-methyldiethoxysilylpropyl)amine, tris(trimethoxysilylmethyl)amine, tris(2-trimethoxysilylethyl)amine, and tris(4-trimethoxysilylpropyl)amine. methoxysilylbutyl)amine.

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

Reaction temperature, reaction time, etc. when reacting a coupling agent having a nitrogen atom-containing group represented by the formula (B) with the active end of the branched conjugated diene polymer obtained in the branching step. Although not particularly limited, it is preferable to react at a temperature of 0° C. or higher and 120° C. or lower for 30 seconds or longer.

The total number of moles of alkoxy groups bonded to silyl groups in the compound of the coupling agent represented by formula (B) is 0.6 times or more the number of moles of lithium constituting the polymerization initiator described above, or 3.0 It is preferably within a range of 0.8 times or more and 2.5 times or less, and even more preferably within a range of 0.8 times or more and 2.0 times or less. . From the viewpoint of obtaining a sufficient modification rate, molecular weight, and branched structure in the branched conjugated diene polymer obtained by the production method of this embodiment, it is preferable to set the ratio to 0.6 times or more, and to improve processability, In addition to it being preferable to couple the combined terminals to obtain a branched conjugated diene polymer component, from the viewpoint of coupling agent cost, it is preferable to make it 3.0 times or less.

The number of moles of the polymerization initiator is preferably 4.0 times or more, more preferably 5.0 times the mole of the coupling agent having a nitrogen atom-containing group represented by the above formula (B). That's all.

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

(In formula (II), B ¹ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. When a plurality of B 1 exist, each B ¹ is independently )

(In formula (III), B ² represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, B ³ represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. (B ² and B ³ are independent when there are multiple B 2 and B 3.)

(In formula (IV), B ⁴ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. When a plurality of B ⁴ exist, each independently )

(In formula (V), B ⁵ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. When there is a plurality of B ⁵ s, each independently )

In formula (C), the coupling agent having a nitrogen atom-containing group when A is represented by formula (II) is not limited to the following, but includes, for example, tris(3-trimethoxysilylpropyl)amine, Bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, bis[3-(2,2-dimethoxy-1-aza-2) -silacyclopentane)propyl]-(3-trimethoxysilylpropyl)amine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tris(3-ethoxysilylpropyl) ) amine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]amine, bis[3-(2,2-diethoxy-1- aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)amine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3- Tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3- Propanediamine, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris[3-(2 ,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1-aza-2) -silacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]- 1,3-Propanediamine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2- trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-tri methoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tris[3-(2,2-dimethoxy-1- aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-triethoxysilyl propyl)-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, Bis(3-triethoxysilylpropyl)-bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine is mentioned.

Also, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-1,3-propanediamine, tetrakis[3-(2,2 -diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2) -azacyclopentane)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3 -(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane) )propyl]-(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tris[3-( 2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine , tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane) propyl]-1,3-bisaminomethylcyclohexane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3- Bisaminomethylcyclohexane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tetrakis[3 -(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl- 1-Sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclo pentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis[3-(2,2-dimethoxy- 1-Aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3 -bisaminomethylcyclohexane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclo) pentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-triethoxysilylpropyl)-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(2,2-diethoxy) -1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-triethoxysilylpropyl)-bis[3-(2,2-diethoxy-1-aza-2- silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-1 ,3-propanediamine, tetrakis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3- (1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy -1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis[ 3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-aza cyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl) -1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexamethylenediamine, and pentakis(3-trimethoxysilylpropyl) )-diethylenetriamine.

In the above formula (C), when A is represented by formula (III), the coupling agent having a nitrogen atom-containing group is not limited to the following, but for example, tris(3-trimethoxysilylpropyl)-methyl -1,3-propanediamine, bis(2-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3-propanediamine, Bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, tris(3-triethoxysilylpropyl) )-Methyl-1,3-propanediamine, bis(2-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3- Propanediamine, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-methyl-1,3-propanediamine, N ¹ ,N ¹ '-(propane-1,3-diyl)bis(N ¹ -methyl- ^{N 3} ,N ³ -bis(3-(trimethoxysilyl)propyl)-1,3-propanediamine), and N ¹ -(3 -(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N ¹ -methyl-N ³ -(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl) -N ³ -( 3-(trimethoxysilyl)propyl)-1,3-propanediamine is mentioned.

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

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

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

Such a coupling agent having a nitrogen atom-containing group having a structure represented by the above formula (C) tends to be easily available, and is also suitable for branched conjugated diene obtained by the production method of the present embodiment. When the polymer is used as a vulcanizate, the wear resistance and low hysteresis loss performance tend to be better. Coupling agents having such a nitrogen atom-containing group include, but are not limited to, for example, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silyl). cyclopentane)propyl]amine, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1 -aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, Tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, Tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, Tris(3-trimethoxysilylpropyl)-methyl-1, 3-propanediamine, and bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trismethoxysilylpropyl)-methyl-1,3-propanediamine. .

In the formula (C), A is more preferably represented by formula (II) or formula (III), k represents 0, and in formula (II) or formula (III), a is 2 to 10. Indicates an integer.
As a result, the branched conjugated diene polymer tends to have better wear resistance and low hysteresis loss performance when vulcanized.
Coupling agents having a nitrogen atom-containing group include, but are not limited to, for example, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3 -propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, and N ₁ -(3-(bis( 3-(trimethoxysilyl)propyl)amino)propyl)-N ₁ -methyl-N ₃ -(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N ₃ -(3-(trimethoxysilyl)propyl)amino)propyl) Methoxysilyl)propyl)-1,3-propanediamine is mentioned.

The amount of the compound represented by formula (C) as a coupling agent having a nitrogen atom-containing group is determined by the ratio of the number of moles of the branched conjugated diene polymer to the number of moles of the coupling agent before the coupling reaction: The reaction can be adjusted to the desired stoichiometric ratio, which tends to achieve the desired star-shaped hyperbranched structure.

The number of moles of the polymerization initiator is preferably 5.0 times or more, more preferably 6.0 times the mole of the coupling agent having a nitrogen atom-containing group represented by the above formula (C). That's all.

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

In the branched conjugated diene polymer obtained by the production method of the present embodiment, the proportion of the polymer having a nitrogen atom-containing group in the polymer is expressed as a modification rate.
The modification rate is preferably 60% by mass or more, more preferably 65% by mass or more, even more preferably 70% by mass or more, even more preferably 75% by mass or more, even more preferably 80% by mass or more, particularly preferably 82% by mass or more. % by mass or more.
By setting the modification rate to 60% by mass or more, the processability when forming a vulcanizate tends to be excellent, and the abrasion resistance and low hysteresis loss performance when forming a vulcanizate tend to be excellent.

<Step of reacting a polymerization terminator>
In the method for producing a branched conjugated diene polymer according to the present embodiment, the above-mentioned coupling agent or polymerization termination agent is added to the active end of the branched conjugated diene polymer obtained through the above-described polymerization step and branching step. A reaction step can be carried out in which the agent is reacted.
Examples of the polymerization termination step include a polymerization termination step performed using a bifunctional reactive compound on the active terminal of the branched conjugated diene polymer, or a polymerization termination step having a nitrogen atom-containing group (hereinafter referred to as It is preferable to perform a polymerization termination step using a polymerization terminator (sometimes also referred to as a "polymerization terminator").

In the polymerization termination step, for example, the active end of the branched conjugated diene polymer obtained in the above-mentioned branching step is treated with a bifunctional reactive compound or a polymerization termination agent having a nitrogen atom-containing group. , the desired branched conjugated diene polymer can be obtained by carrying out a polymerization termination reaction.

[Bifunctional reactive compound]
In the method for producing a branched conjugated diene polymer of the present embodiment, the bifunctional reactive compound used in the polymerization termination step may have any structure, but is a difunctional reactive compound having a silicon atom. It is preferable.
Examples of the difunctional reactive compound having a silicon atom include, but are not limited to, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, etc. It will be done.

[Polymerization terminator having nitrogen atom-containing group]
In the method for producing a branched conjugated diene polymer of the present embodiment, the polymerization terminator having a nitrogen atom-containing group used in the polymerization termination step may have any structure; It is preferable to have a functional group that reacts with the system polymer.

As the polymerization terminator having a nitrogen atom-containing group, an alkoxy compound having a nitrogen atom-containing group is preferable from the viewpoint of improving fuel efficiency performance.
Examples of the polymerization terminator having a nitrogen atom-containing group include, but are not limited to, 3-(N,N-dimethylaminopropyl)dimethoxymethylsilane, 3-(N,N-diethylaminopropyl)dimethoxymethylsilane, and 3-(N,N-dimethylaminopropyl)dimethoxymethylsilane. -(N,N-dipropylaminopropyl)dimethoxymethylsilane, 3-(N,N-dimethylaminopropyl)diethoxymethylsilane, 3-(N,N-diethylaminopropyl)diethoxymethylsilane, 3-(N-dimethylaminopropyl)diethoxymethylsilane, , N-dipropylaminopropyl)diethoxymethylsilane, 3-(N,N-dimethylaminopropyl)dimethoxyethylsilane, 3-(N,N-diethylaminopropyl)dimethoxyethylsilane, 3-(N,N-dimethylaminopropyl)dimethoxyethylsilane, propylaminopropyl)dimethoxyethylsilane, 3-(N,N-dimethylaminopropyl)diethoxyethylsilane, 3-(N,N-diethylaminopropyl)diethoxyethylsilane, 3-(N,N-dipropylaminopropyl) ) diethoxyethylsilane and the like.

The branched structure of the branched conjugated diene polymer obtained by the production method of the present embodiment through the above-mentioned polymerization step, branching step, and reaction step is preferably 8 branches or more and 36 branches or less, and more preferably Preferably, the number of branches is 10 or more and 24 or less, and more preferably 12 or more and 20 or less.
The total number of branch points in the branched conjugated diene polymer obtained by the production method of the present embodiment is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and even more preferably 5 or more. preferable.
When the branch structure and the total number of branch points are within the above-mentioned range, workability, fuel efficiency, and wear resistance tend to be excellent.
The branched conjugated diene polymer has a branch structure of 8 branches or more and 36 branches or less, and in the case of a branched conjugated diene polymer containing a modifier, the total number of branch points is 2 or more and 15 or less. In order to construct this, it is necessary to use a molar ratio of the branching agent that is less than 1/2 and more than 1/100 of the polymerization initiator, and a coupling agent that has three or more functional groups. In the case of a polymer that does not require modification, there may be one or more branch points.
In order to construct a branched structure with 8 to 36 branches and a total number of branching points of 3 to 12, the molar ratio of the branching agent must be one-third or less of the polymerization initiator. It is preferable to use a coupling agent in which the number of functional groups is 4 or more.
In order to construct a branched structure with 10 to 24 branches and a total number of branching points of 4 to 10, the molar ratio of the branching agent is 1/6 or less of the polymerization initiator, and 25 minutes It is preferable to use a coupling agent in which the number of functional groups is 5 or more.
In order to construct a branched structure with 12 to 20 branches and a total number of branching points of 5 to 9, the molar ratio of the branching agent should be 1/8 or less of the polymerization initiator. It is preferable to use a coupling agent in which the number of functional groups is 6 or more.

(Condensation reaction step)
In the method for producing a branched conjugated diene polymer of the present embodiment, a condensation reaction step may be carried out in the presence of a condensation promoter after or before the above-described coupling step.

(Hydrogenation process)
In the method for producing a branched conjugated diene polymer of this embodiment, a hydrogenation step of hydrogenating the conjugated diene moiety may be performed.
The method for hydrogenating the conjugated diene moiety of the branched conjugated diene polymer is not particularly limited, and any known method can be used.
A suitable hydrogenation method includes a hydrogenation method in which gaseous hydrogen is blown into the polymer solution in the presence of a catalyst.
The catalyst is not particularly limited, but includes, for example, a heterogeneous catalyst such as a catalyst in which a noble metal is supported on a porous inorganic substance; a catalyst in which a salt such as nickel or cobalt is solubilized and reacted with an organoaluminium, etc., titanocene, etc. Examples include homogeneous catalysts such as catalysts using metallocenes. Among these, titanocene catalysts are preferred from the viewpoint of being able to select mild hydrogenation conditions. Further, hydrogenation of aromatic groups can be carried out by using a supported noble metal catalyst.

Hydrogenation catalysts include, but are not limited to, (1) supported heterogeneous hydrogenation catalysts in which metals such as Ni, Pt, Pd, and Ru are supported on carbon, silica, alumina, diatomaceous earth, etc.; (2) A so-called Ziegler hydrogenation catalyst using an organic acid salt such as Ni, Co, Fe, or Cr or a transition metal salt such as an acetylacetone salt and a reducing agent such as an organic aluminum; (3) Ti, Ru, Rh, Examples include so-called organometallic complexes such as organometallic compounds such as Zr. Furthermore, the hydrogenation catalyst is not particularly limited, but examples include, but are not limited to, Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, Japanese Patent Publication No. 63-4841, Japanese Patent Publication No. 1-37970, Japanese Patent Publication No. Also mentioned are known hydrogenation catalysts described in Japanese Patent Publication No. 53851, Japanese Patent Publication No. 2-9041, and Japanese Patent Application Laid-Open No. 8-109219. Preferred hydrogenation catalysts include reaction mixtures of titanocene compounds and reducing organometallic compounds.

(Addition process of deactivating agent and neutralizing agent)
In the method for producing a branched conjugated diene polymer of the present embodiment, after the above-described coupling step, a deactivator, a neutralizing agent, etc. may be added to the polymer solution as necessary.
Examples of the deactivator include, but are not limited to, water; alcohols such as methanol, ethanol, and isopropanol; and the like.
Examples of the neutralizing agent include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a mixture of highly branched carboxylic acids with 9 to 11 carbon atoms, mainly 10 carbon atoms). Acids: Examples include aqueous solutions of inorganic acids and carbon dioxide gas.

(Rubber stabilizer addition process)
In the method for producing a branched 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 from the viewpoint of improving stability during processing.
The stabilizer for rubber is not limited to the following, and any known stabilizer can be used, such as 2,6-di-tert-butyl-4-hydroxytoluene (hereinafter also referred to as "BHT"), n Antioxidants such as -octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol)propinate and 2-methyl-4,6-bis[(octylthio)methyl]phenol are preferred.

(Rubber softener addition process)
In the method for producing a branched conjugated diene polymer according to the present embodiment, the productivity of the branched conjugated diene polymer and the processability of the branched conjugated diene polymer when compounded with fillers and the like to form a rubber composition are improved. A rubber softener can be added as needed.
Rubber softeners include, but are not particularly limited to, extender oils, liquid rubbers, resins, and the like.
Methods for adding the rubber softener to the branched conjugated diene polymer include, but are not limited to, the following methods: Add the rubber softener to the branched conjugated diene polymer solution, mix, and add the rubber softener to the branched conjugated diene polymer solution. A preferred method is to remove the solvent from a polymer solution.

Preferred extender oils include, for example, aroma oils, naphthenic oils, paraffin oils, and the like. Among these, from the viewpoint of environmental safety, oil bleed prevention and wet grip properties, aromatic alternative oils containing 3% by mass or less of polycyclic aromatic (PCA) components according to the IP346 method are preferred. Examples of aroma substitute oils include TDAE (Treated Distillate Aromatic Extracts) and MES (Mild Extraction Sol) shown in Kautschuk Gummi Kunststoffe 52 (12) 799 (1999). vate), as well as RAE (Residual Aromatic Extracts).

Preferred liquid rubbers include, but are not limited to, liquid polybutadiene, liquid styrene-butazine rubber, and the like.
The effect of adding liquid rubber is that it can improve the processability of a resin composition containing a branched conjugated diene polymer and a filler, as well as improve the glass transition of the resin composition. Being able to shift the temperature to the lower temperature side tends to improve the wear resistance, low hysteresis loss, and low temperature properties when made into a vulcanizate.
Examples of resins used as rubber softeners include, but are not limited to, aromatic petroleum resins, coumaron-indene resins, terpene resins, rosin derivatives (including tung 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 resin, xylene-formaldehyde resin, monoolefin oligomer, diolefin oligomer, hydrogenated aromatic hydrocarbon resin, cycloaliphatic hydrocarbon resin, hydrogenated hydrocarbon resin, hydrocarbon resin, hydrogenated tung oil resin , hydrogenated oil resins, esters of hydrogenated oil resins and monofunctional or polyfunctional alcohols, and the like. These resins may be used alone or in combination of two or more. When hydrogenating, all unsaturated groups may be hydrogenated, or some may remain.
The effect of adding a resin as a rubber softener is that in addition to improving the processability of a resin composition containing a conjugated diene polymer and a filler, it also improves the processability of vulcanizates. It tends to improve the breaking strength when the resin composition is heated, and it tends to improve the wet skid resistance by shifting the glass transition temperature of the resin composition to a higher temperature side.

The amount of extender oil, liquid rubber, resin, etc. added as a rubber softener is not particularly limited, but is preferably 1 part by mass per 100 parts by mass of the branched conjugated diene polymer obtained by the production method of this embodiment. The amount is at least 5 parts by mass and at most 60 parts by mass, more preferably at least 5 parts by mass and at most 50 parts by mass, and even more preferably at least 10 parts by mass and at most 37.5 parts by mass.
When the rubber softener is added within the above range, the resin composition containing the branched conjugated diene polymer obtained by the production method of this embodiment and a filler etc. will have good processability, and When made into sulfur, the fracture strength and wear resistance tend to be good.

(Desolvation step)
In the method for producing a branched conjugated diene polymer of the present embodiment, a known method can be used to obtain the obtained branched conjugated diene polymer from a polymer solution. The method is not particularly limited, but for example, after separating the solvent by steam stripping etc., the polymer is filtered, and then dehydrated and dried to obtain the polymer, or concentrated in a flushing tank. Further, there are methods of devolatilizing with a vent extruder or the like, and methods of directly devolatilizing with a drum dryer or the like.

[Branched conjugated diene polymer]
The branched conjugated diene polymer of this embodiment is a branched conjugated diene polymer obtained by the method for producing a branched conjugated diene polymer of this embodiment described above, and has the following formula in the polymer main chain. It has a main chain branched structure derived from a nitrogen atom-containing branching agent, which is a compound represented by (1).

In formula (1), R ¹ to R ² each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms.
X ¹ is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen.
Y ¹ represents one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be independent and the same, or may be different.

[Rubber composition and method for producing the rubber composition]
The rubber composition of this embodiment includes a rubber component containing 10% by mass or more of the branched conjugated diene polymer of this embodiment produced by the production method of this embodiment described above, and 100 parts by mass of the rubber component. On the other hand, it contains 5.0 parts by mass or more and 150 parts by mass or less of a filler.
The method for producing a rubber composition of the present embodiment includes a step of obtaining a branched conjugated diene polymer by the above-described production method, a step of obtaining a rubber component containing 10% by mass or more of the branched conjugated diene polymer, It includes a step of containing 5.0 parts by mass or more and 150 parts by mass or less of a filler with respect to 100 parts by mass of the rubber component.
Furthermore, by including 10% by mass of the branched conjugated diene polymer obtained by the manufacturing method of the present embodiment in the rubber component, excellent fuel efficiency, processability, and improved wear resistance can be obtained. .

The filler preferably includes a silica-based inorganic filler.
By dispersing a silica-based inorganic filler as a filler, rubber compositions tend to have better processability when made into a vulcanizate, and when made into a vulcanizate, the abrasion resistance, fracture strength, and low They tend to have a better balance between hysteresis loss and wet skid resistance.
Also when the rubber composition is used for vulcanized rubber applications such as tires, automobile parts such as anti-vibration rubber, and shoes, it is preferable that the rubber composition contains a silica-based inorganic filler.

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

Examples of the rubbery polymer include, but are not limited to, butadiene rubber or its hydrogenated product, isoprene rubber or its hydrogenated product, styrene-butadiene rubber or its hydrogenated product, styrene-butadiene block copolymer or its hydrogenated product, etc. Examples include hydrogenated products, styrene elastomers such as styrene-isoprene block copolymers or hydrogenated products thereof, acrylonitrile-butadiene rubber or hydrogenated products thereof.

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; Examples include butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylic acid ester-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber. It will be done.

Examples of natural rubber include, but are not limited to, smoked sheets RSS No. 3 to 5, SMR, and epoxidized natural rubber.

The various rubbery polymers mentioned above may be modified rubbers to which polar functional groups such as hydroxyl groups and amino groups are added. When used for tires, butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber are preferably used.

The weight average molecular weight of the rubbery polymer is preferably 2,000 or more and 2,000,000 or less, and more preferably 5,000 or more and 1,500,000 or less, from the viewpoint of the balance between various performances and processing characteristics of the rubber composition of the present embodiment. . Furthermore, a low molecular weight rubbery polymer, a so-called liquid rubber, can also be used.
These rubbery polymers may be used alone or in combination of two or more.

When the rubber composition using the branched conjugated diene polymer of this embodiment is a rubber composition containing the above-mentioned rubber-like polymer, the above-mentioned branched conjugated diene-based polymer is added to the rubber-like polymer. The content ratio (mass ratio) (branched conjugated diene polymer/rubber-like polymer) is preferably 10/90 or more and 100/0 or less, more preferably 20/80 or more and 90/10 or less, and 50/50. More preferably, the ratio is 80/20 or less.
Therefore, the rubber component preferably contains 10% by mass or more and 100% by mass or less, more preferably 20% by mass or more, of the above-mentioned branched conjugated diene polymer based on the total amount (100% by mass) of the rubber component. It contains 90% by mass or less, more preferably 50% by mass or more and 80% by mass or less.

When the content ratio of (branched conjugated diene polymer/rubber-like polymer) is within the above range, the vulcanized product has excellent wear resistance and fracture strength, and has low hysteresis loss and wet skid resistance. There also tends to be a good balance.

The filler contained in the rubber composition of the present embodiment is not limited to the following, but includes, for example, carbon black, metal oxides, and metal hydroxides in addition to the silica-based inorganic filler. Among these, silica-based inorganic fillers are preferred.
One type of filler may be used alone, or two or more types may be used in combination.
The content of the filler in the rubber composition is 5.0 parts by mass or more and 150 parts by mass, and 20 parts by mass or more and 100 parts by mass with respect to 100 parts by mass of the rubber component containing the above-mentioned branched conjugated diene polymer. Parts or less are preferred, and more preferably 30 parts by mass or more and 90 parts by mass or less.
In the rubber composition, the content of the filler is 5.0 parts by mass or more based on 100 parts by mass of the rubber component, from the viewpoint of exhibiting the effect of adding the filler, so that the filler is sufficiently dispersed and the rubber composition is From the viewpoint of ensuring practically sufficient workability and mechanical strength of the product, the amount is 150 parts by mass or less per 100 parts by mass of the rubber component.

The silica-based inorganic filler is not particularly limited and any known one can be used, but solid particles containing SiO ₂ or Si ₃ Al as a constituent unit are preferable, and SiO ₂ or Si ₃ Al is the main constituent unit. Solid particles contained as a component 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.

Examples of the silica-based inorganic filler include, but are not limited to, inorganic fibrous substances such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber. Also included are silica-based inorganic fillers whose surfaces have been made hydrophobic, and mixtures of silica-based inorganic fillers and inorganic fillers other than silica-based fillers.
Among these, silica and glass fiber are preferred, and silica is more preferred, from the viewpoint of strength, abrasion resistance, and the like.
Examples of silica include dry silica, wet silica, and synthetic silicate silica. Among these silicas, wet silica is preferred from the viewpoint of improving the breaking strength and having an excellent balance of wet skid resistance.

From the viewpoint of obtaining practically good wear resistance and fracture strength in the rubber composition, the nitrogen adsorption specific surface area of the silica-based inorganic filler determined by the BET adsorption method should be 100 m ² /g or more and 300 m ² /g or less. is preferable, and more preferably 170 m ² /g or more and 250 m ² /g or less.
In addition, if necessary, a silica-based inorganic filler with a relatively small specific surface area (for example, a specific surface area of less than 200 m ² /g) and a silica-based filler with a relatively large specific surface area (for example, a specific surface area of 200 m ² /g or more) may be used. (inorganic filler) can be used in combination.
In particular, when using a silica-based inorganic filler with a relatively large specific surface area (for example, 200 m ² /g or more), the rubber composition containing the branched conjugated diene polymer described above improves the dispersibility of silica. , is particularly effective in improving wear resistance, and tends to be able to achieve a high balance between good fracture strength and low hysteresis loss.

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

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

The content of carbon black in the rubber composition is 0.5 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the rubber component containing the branched conjugated diene polymer obtained by the production method of the present embodiment. It is preferably 3.0 parts by mass or more and 100 parts by mass or less, more preferably 5.0 parts by mass or more and 50 parts by mass or less. In the rubber composition, the content of carbon black is 0.5 parts by mass or more based on 100 parts by mass of the rubber component, from the viewpoint of expressing the performance required for uses such as tires, such as dry grip performance and conductivity. From the viewpoint of dispersibility, the amount is preferably 100 parts by mass or less per 100 parts by mass of the rubber component.

Metal oxide refers to solid particles whose main component is the chemical formula MxOy (M represents a metal atom, and x and y each independently represent an integer from 1 to 6). .

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

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

The rubber composition of this embodiment may contain a silane coupling agent.
The silane coupling agent has the function of enhancing the interaction between the rubber component and the inorganic filler. Specifically, compounds having affinity or binding groups for each of the rubber component and the silica-based inorganic filler, and having a sulfur bonding moiety and an alkoxysilyl group or a silanol group moiety in one molecule are preferred. .
Examples of such compounds include, but are not limited to, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[3-(triethoxysilyl)-propyl]-disulfide. 2-(triethoxysilyl)-ethyl]-tetrasulfide is mentioned.

In the rubber composition, the content of the silane coupling agent is preferably 0.1 parts by mass or more and 30 parts by mass or less, and 0.5 parts by mass or more and 20 parts by mass or less, based on 100 parts by mass of the above-mentioned inorganic filler. More preferably, it is 1.0 parts by mass or more and 15 parts by mass or less. When the content of the silane coupling agent is within the above range, the effect of the addition of the silane coupling agent tends to be more pronounced.

The rubber composition of this embodiment may contain a rubber softener from the viewpoint of improving its processability.
The amount of the rubber softener to be added is determined by adding the above-mentioned branched conjugated diene-based polymer and others in advance to 100 parts by mass of the rubber component containing the branched conjugated diene-based polymer obtained by the production method of the present embodiment described above. It is expressed by the amount including the rubber softener contained in the rubbery polymer and the total amount of the rubber softener added when producing the rubber composition.
As the rubber softener, mineral oil or a liquid or low molecular weight synthetic softener is suitable.
Mineral oil-based rubber softeners called process oils or extender oils, which are used to soften, increase volume, and improve processability of rubber, are a mixture of aromatic rings, naphthenic rings, and paraffin chains. Those in which the number of carbon atoms in the paraffin chain accounts for 50% or more of the total carbons are called paraffin series, and those in which the number of carbon atoms in the naphthene ring accounts for 30% or more and 45% or less of the total carbons are called naphthenic series, and aromatic carbons. Carbons that account for more than 30% of the total carbon are called aromatic.
When the branched conjugated diene polymer of this embodiment contains a conjugated diene compound and an aromatic vinyl compound as polymerized monomers, the rubber softener to be used is one having an appropriate aromatic content. It is preferable because it tends to be compatible with branched conjugated diene copolymers.
In the rubber composition, the content of the rubber softener is preferably 0 parts by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more and 90 parts by mass or less, and 30 parts by mass or more, based on 100 parts by mass of the rubber component. More preferably, it is 90 parts by mass or less. When the content of the rubber softener is 100 parts by mass or less based on 100 parts by mass of the rubber component, bleed-out tends to be suppressed and stickiness on the surface of the rubber composition is suppressed.

Branched conjugated diene polymers and other rubber-like polymers obtained by the production method of this embodiment, silica-based inorganic fillers, carbon black and other fillers, silane coupling agents, rubber softeners, etc. The method for mixing the additives is not limited to the following, but for example, common mixing machines such as open rolls, Banbury mixers, kneaders, single screw extruders, twin screw extruders, and multi-screw extruders can be used. Examples of the melt-kneading method used include a method in which each component is dissolved and mixed and then the solvent is removed by heating.
Among these, melt-kneading methods using rolls, Banbury mixers, kneaders, and extruders are preferred from the viewpoint of productivity and good kneading properties. Moreover, either a method of kneading the rubber component, other fillers, silane coupling agents, and additives at once, or a method of mixing them in a plurality of batches can be applied.

The rubber composition of this embodiment may be a vulcanized composition subjected to vulcanization treatment using 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. Sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, polymeric polysulfur compounds, and the like.
In the rubber composition of the present embodiment, the content of the vulcanizing agent is preferably 0.01 parts by mass or more and 20 parts by mass or less, and 0.1 parts by mass or more and 15 parts by mass or less, based on 100 parts by mass of the rubber component. More preferred. As the vulcanization method, conventionally known methods can be applied, and the vulcanization temperature is preferably 120°C or more and 200°C or less, more preferably 140°C or more and 180°C or less.

During vulcanization, a vulcanization accelerator may be used if necessary.
As the vulcanization accelerator, conventionally known materials can be used, including, but not limited to, sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based. , thiourea-based, and dithiocarbamate-based vulcanization accelerators.
Further, the vulcanization aid is not limited to the following, but examples thereof include zinc white 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, more preferably 0.1 parts by mass or more and 15 parts by mass or less, based on 100 parts by mass of the rubber component.

The rubber composition of the present embodiment may include other softeners and fillers other than those mentioned above, a heat stabilizer, an antistatic agent, a weather stabilizer, an anti-aging agent, within a range that does not impair the purpose of the present embodiment. Various additives such as colorants and lubricants may also be used.
As other softeners, known softeners can be used.
Other fillers include, but are not particularly limited to, calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. As the above-mentioned heat stabilizer, antistatic agent, weather stabilizer, anti-aging agent, colorant, and lubricant, known materials can be used.

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

Rubber compositions for tires include, but are not limited to, various tires such as fuel-efficient tires, all-season tires, high-performance tires, and studless tires: to various parts of tires such as treads, carcass, sidewalls, and bead parts. It is possible to use In particular, rubber compositions for tires have an excellent balance between abrasion resistance, breaking strength, low hysteresis loss, and wet skid resistance when made into a vulcanizate. It is suitably used for treads.

Hereinafter, the present embodiment will be described in more detail with reference to specific examples and comparative examples, but the present invention is not limited to the following examples and comparative examples.
Various physical properties in Examples and Comparative Examples were measured by the methods shown below.
In the following, a conjugated diene polymer coupled with a coupling agent will be referred to as a "coupled conjugated diene polymer."
Furthermore, a conjugated diene polymer having a branched structure derived from a nitrogen atom-containing branching agent is referred to as a "modified branched conjugated diene polymer."
Furthermore, "conjugated diene polymer" is a general term for coupled conjugated diene polymer, modified branched conjugated diene polymer, and conjugated diene polymer that does not have a branched structure derived from a nitrogen atom-containing branching agent. It may be written as
In the Examples described later, a conjugated diene polymer having a branched structure derived from a nitrogen atom-containing branching agent is referred to as a "modified branched conjugated diene polymer", but such a description does not apply to the present invention. The branched conjugated diene polymer produced by the method for producing a branched conjugated diene polymer is not limited in any way.

Various physical properties in Examples and Comparative Examples were measured by the methods shown below.

(Physical properties 1) Polymer Mooney viscosity Using various conjugated diene polymers as samples, the Mooney viscosity was measured using a Mooney viscometer (product name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) in accordance with ISO 289 and using an L-shaped rotor. was measured.
The measurement temperature is 110°C when the sample is a modified branched conjugated diene polymer or a conjugated diene polymer without a nitrogen atom-containing branching agent, and when the sample is a coupled conjugated diene polymer. In this case, the temperature was set at 100°C.
First, after preheating the sample at the test temperature for 1 minute, the rotor was rotated at 2 rpm, and the torque after 4 minutes was measured and defined as the Mooney viscosity (ML ₍₁₊₄₎ ).

(Physical property 2) Mooney relaxation rate Using a coupled conjugated diene polymer as a sample, the Mooney viscosity was measured using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) in accordance with ISO 289 and using an L-shaped rotor. After measuring, immediately stop the rotation of the rotor, record the torque every 0.1 seconds for 1.6 seconds to 5 seconds after stopping, and plot the torque and time (seconds) log-logarithmically. The slope of the straight line was determined, and its absolute value was taken as the Mooney relaxation rate (MSR).

(Physical property 3) Degree of branching (Bn)
The degree of branching (Bn) of the coupled conjugated diene polymer was measured as follows by GPC-light scattering measurement method equipped with a viscosity detector.
Using a coupled conjugated diene polymer as a sample, a gel permeation chromatography (GPC) measuring device (product name: "GPCmax VE-2001" manufactured by Malvern) consisting of three columns connected with polystyrene gel as a packing material was used. The measurement was performed using three detectors connected in this order: a light scattering detector, an RI detector, and a viscosity detector (trade name "TDA305" manufactured by Malvern). The absolute molecular weight was determined from the measurement results of the scattering detector and the RI detector, and the intrinsic viscosity was determined from the measurement results of the RI detector and the viscosity detector.
The linear polymer was used as having an intrinsic viscosity [η]=10 ^−3.883 M ^0.771 , and the shrinkage factor (g′) as a ratio of the intrinsic viscosity corresponding to each molecular weight was calculated. In addition, in the formula, M represents an absolute molecular weight.
Thereafter, the degree of branching (Bn) defined as g'=6Bn/{(Bn+1)(Bn+2)} was calculated using the obtained contraction factor (g').
Tetrahydrofuran (hereinafter also referred to as "THF") containing 5 mmol/L of triethylamine was used as the eluent.
The columns used were those manufactured by Tosoh Corporation under the trade names "TSKgel G4000HXL,""TSKgelG5000HXL," and "TSKgel G6000HXL."
20 mg of a sample for measurement was dissolved in 10 mL of THF to prepare a measurement solution, and 100 μL of the measurement solution was injected into a GPC measuring device, and measurement was performed under the conditions of an oven temperature of 40° C. and a THF flow rate of 1 mL/min.

(Physical property 4) Molecular weight <Measurement conditions 1>:
Using various conjugated diene polymers as samples, we used a GPC measuring device (product name: "HLC-8320GPC" manufactured by Tosoh Corporation) consisting of three columns connected with polystyrene gel as a filler, and measured an RI detector ( The chromatogram was measured using Tosoh Corporation's product name "HLC8020"), and the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution ( Mw/Mn) was calculated.
THF (tetrahydrofuran) containing 5 mmol/L of triethylamine was used as the eluent. Three columns, manufactured by Tosoh Corporation under the trade name "TSKgel SuperMultiporeHZ-H", were connected, and a guard column manufactured by Tosoh Corporation under the trade name "TSKguardcolumn SuperMP (HZ)-H" was connected in front of the column.
10 mg of a measurement sample was dissolved in 10 mL of THF to obtain a measurement solution, and 10 μL of the measurement solution was injected into a GPC measuring device, and measurement was performed under the conditions of an oven temperature of 40° C. and a THF flow rate of 0.35 mL/min.
Among the various samples measured under measurement condition 1 above, samples whose molecular weight distribution (Mw/Mn) value was less than 1.6 were measured again under measurement condition 2 below. For samples whose molecular weight distribution value was 1.6 or more when measured under measurement condition 1, the measurement was performed under measurement condition 1 and the measured value was adopted.
<Measurement conditions 2>:
Using various conjugated diene polymers as samples, measure the chromatogram using a GPC measurement device that connects three columns with polystyrene gel as a packing material, and calculate the weight based on a calibration curve using standard polystyrene. The average molecular weight (Mw) and number average molecular weight (Mn) were determined.
THF containing 5 mmol/L of triethylamine was used as the eluent. The columns used were guard columns 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".
An RI detector (trade name "HLC8020" manufactured by Tosoh Corporation) 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 for measurement was dissolved in 20 mL of THF to prepare a measurement solution, and 20 μL of the measurement solution was injected into a GPC measuring device for measurement.
For samples whose molecular weight distribution value was less than 1.6 when measured under measurement condition 1, the sample was measured under measurement condition 2 and the measured value was adopted.

(Physical Property 5) Modification Rate The modification rate of the modified branched conjugated diene polymer and the coupled conjugated diene polymer was measured by column adsorption GPC method as follows.
By using modified branched conjugated diene polymers and coupled conjugated diene polymers as samples, and applying the property of adsorption of modified basic polymer components to a GPC column using silica gel as a packing material, It was measured.
The amount of adsorption to the silica column is measured from the difference between the chromatogram measured using a polystyrene column and the chromatogram measured using a silica column for a sample solution containing a sample and a low molecular weight internal standard polystyrene, and the denaturation rate is determined. I asked for it.
Specifically, it is as shown below.
In addition, for samples whose molecular weight distribution value was 1.6 or more when measured under measurement condition 1 of (physical property 4) above, measurement was performed under measurement condition 3 below, and the measured value was adopted. For samples whose molecular weight distribution value was less than 1.6 when measured under measurement condition 1 in (physical property 4) above, measurement was performed under measurement condition 4 below, and the measured value was adopted.

<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 conditions 3>:
GPC measurement conditions using polystyrene column:
Using Tosoh Corporation's product name "HLC-8320GPC", 10 μL of the sample solution was injected into the device using THF containing 5 mmol/L triethylamine as the eluent, the column oven temperature was 40°C, and the THF flow rate was 0.35 mL/L. A chromatogram was obtained using an RI detector under the conditions of 10 minutes.
Three columns, manufactured by Tosoh Corporation under the trade name "TSKgel SuperMultiporeHZ-H", were connected, and a guard column manufactured by Tosoh Corporation under the trade name "TSKguardcolumn SuperMP (HZ)-H" was connected in front of the column.

<Measurement conditions 4>:
GPC measurement conditions using polystyrene column:
Using THF containing 5 mmol/L triethylamine as an eluent, 20 μL of the sample solution was injected into the device for measurement.
The columns used were guard columns 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 (HLC8020 manufactured by Tosoh Corporation) under the conditions of a column oven temperature of 40° C. and a THF flow rate of 0.6 mL/min to obtain a chromatogram.

GPC measurement conditions using silica column:
Using Tosoh Corporation's product name "HLC-8320GPC," 50 μL of the sample solution was injected into the device using THF as the eluent, and RI was performed under the conditions of a column oven temperature of 40°C and a THF flow rate of 0.5 ml/min. A chromatogram was obtained using a detector. Columns with the product name "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S" are connected and used, and the product name "DIOL 4.6 x 12.5 mm 5 micron" is used as a guard column in the preceding stage. Connected and used.

How to calculate denaturation rate:
The peak area of the sample is P1, the peak area of the standard polystyrene is P2, the total peak area of the chromatogram using the silica column is 100, the total peak area of the chromatogram using the polystyrene column is 100, and the peak area of the sample is P1. The modification rate (%) was determined from the following formula, with the peak area of P3 as P3 and the peak area of standard polystyrene as P4.
Denaturation rate (%) = [1-(P2×P3)/(P1×P4)]×100
(However, P1+P2=P3+P4=100)

(Physical property 6) Amount of bound styrene A coupled conjugated diene polymer containing no rubber softener was used as a sample, and 100 mg of the sample was diluted to 100 mL with chloroform and dissolved to obtain a measurement sample.
The amount of bound styrene (mass %) with respect to 100 mass % of the coupled conjugated diene polymer sample was measured based on the absorption amount of ultraviolet absorption wavelength (around 254 nm) by the phenyl group of styrene (measuring device: Shimadzu Corporation Spectrophotometer "UV-2450" manufactured by Co., Ltd.).

(Physical property 7) Microstructure of butadiene moiety (1,2-vinyl bond amount)
A coupled conjugated diene polymer containing no 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.
Hampton's method (method described in R.R. Hampton, Analytical Chemistry 21, 923 (1949)) is performed by measuring the infrared spectrum in the range of 600 to 1000 cm ^-1 using a solution cell and determining the absorbance at a predetermined wave number. The microstructure of the butadiene moiety, that is, the amount of 1,2-vinyl bonds (also referred to as the amount of 1,2-bonds in the table) (mol%) was determined according to the calculation formula (measuring device: JASCO Corporation). Fourier transform infrared spectrophotometer "FT-IR230").

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

[Conjugated diene polymer]
(Example 1) Coupled conjugated diene polymer (Sample 1)
A tank-type reactor with an internal volume of 10 L, a ratio of internal height (L) to diameter (D) (L/D) of 4.0, an inlet at the bottom, an outlet at the top, and a stirrer. Two tank-type pressure vessels each having a stirrer and a jacket for temperature control were connected as a polymerization reactor.
1,3-butadiene, from which water had been removed in advance, 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 that supplies this mixed solution to the inlet of the polymerization reactor, n-butyllithium for inactivating residual impurities was added at a rate of 0.103 mmol/min and mixed, and then the bottom of the reaction group was continuously supplied. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance was mixed vigorously with a stirrer at a rate of 0.081 mmol/min, and n-butyllithium was mixed as a polymerization initiator at a rate of 0.143 mmol/min. The mixture was supplied to the bottom of the polymerization reactor, and the internal temperature of the polymerization reactor was maintained at 67°C.
The polymer solution is continuously extracted from the top of the first polymerization reactor and continuously supplied to the bottom of the second polymerization reactor to continue the reaction at 70°C, and then a static mixer is added from the top of the second reactor. supplied to. When the polymerization was sufficiently stabilized, while copolymerizing 1,3-butadiene and styrene, compound M-1 (in the table, "M -1" was added at a rate of 0.0190 mmol/min to carry out a polymerization reaction and a branching reaction to obtain a modified branched conjugated diene polymer having a main chain branched structure.
Furthermore, when the polymerization reaction and branching reaction were stabilized, a small amount of the modified branched conjugated diene polymer before addition of the coupling agent was extracted, and an antioxidant (BHT) was added at a concentration of 0.2 g per 100 g of the polymer. Afterwards, the solvent was removed, and the Mooney viscosity at 110°C, various molecular weights, and modification rates were measured. The physical properties are shown in Table 1.
Next, tetraethoxysilane (abbreviated as "A" in the table) was continuously added as a coupling agent to the polymer solution flowing out from the outlet of the polymerization reactor at a rate of 0.0480 mmol/min. The mixture was mixed using a static mixer to perform 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 polymerization reactor was 4.8 minutes, and the temperature was 68°C. The difference between the temperature and the previous one was 2°C. After the coupling reaction, a small amount of the conjugated diene polymer solution is taken out, and an antioxidant (BHT) is added in an amount of 0.2 g per 100 g of the polymer, and then the solvent is removed and the amount of bound styrene (physical property 6) and The microstructure (1,2-vinyl bond amount: physical property 7) of the butadiene moiety was measured. The measurement results are shown in Table 1.
Next, an antioxidant (BHT) was continuously added to the coupling-reacted polymer solution at a rate of 0.055 g/min (n-hexane solution) at a rate of 0.2 g per 100 g of the polymer. The reaction has ended. At the same time as 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 is removed by steam stripping, and a part of the main chain contains a nitrogen atom-containing branching agent (hereinafter also referred to as "branching agent structure (1)") which is a compound represented by the following formula (M-1). A coupled conjugated diene polymer (Sample 1) having a branched structure derived from ) and a tri-branched star-shaped polymer structure derived from a coupling agent was obtained.
Table 1 shows the physical properties of Sample 1.
In addition, for the polymer before addition of the nitrogen atom-containing branching agent, the polymer after the addition of the nitrogen atom-containing branching agent, and the polymer in each step after the addition of the coupling agent, the molecular weight by GPC measurement and GPC with a viscometer were determined. The structure of the coupled conjugated diene polymer was identified by comparing the measured degree of branching. Below, the structure of each sample was similarly identified.

In formula (M-1), Me represents a methyl group.

(Example 2) Coupled conjugated diene polymer (Sample 2)
Example except that the coupling agent was changed from tetraethoxysilane to 1,2-bis(triethoxysilyl)ethane (abbreviated as "B" in the table) and the amount added was changed to 0.0360 mmol/min. In the same manner as 1, a coupled conjugated diene polymer having an 8-branched structure derived from the branching agent structure (1) in part of the main chain and a 4-branched star-shaped polymer structure derived from the coupling agent. (Sample 2) was obtained. Table 1 shows the physical properties of Sample 2.

(Example 3) Coupled conjugated diene polymer (Sample 3)
The coupling agent was changed from tetraethoxysilane to 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (abbreviated as "C" in the table), and the amount added was changed to 0.0360 mmol/min. Other than that, the same procedure as in Example 1 was carried out, with some of the main chains having an 8-branched structure derived from the branching agent structure (1) and a 4-branched star-shaped polymer structure derived from the coupling agent. A conjugated diene polymer (sample 3) was obtained. Table 1 shows the physical properties of Sample 3.

(Example 4) Coupled conjugated diene polymer (Sample 4)
The coupling agent was changed from tetraethoxysilane to 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (abbreviated as "D" in the table), and the addition of The procedure was the same as in Example 1 except that the amount was changed to 0.0360 mmol/min, but some of the main chains had a 4-branched structure derived from the branching agent structure (1), and an 8-branched structure derived from the coupling agent. A coupled conjugated diene polymer (sample 4) having a star-shaped polymer structure was obtained. Table 1 shows the physical properties of Sample 4.

(Example 5) Coupled conjugated diene polymer (Sample 5)
Example 1 except that the coupling agent was changed from tetraethoxysilane to tris(3-trimethoxysilylpropyl)amine (abbreviated as "E" in the table) and the amount added was changed to 0.0250 mmol/min. Similarly, a coupled conjugated diene polymer ( Sample 5) was obtained. Table 1 shows the physical properties of Sample 5.

(Example 6) Coupled conjugated diene polymer (Sample 6)
The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), and the amount added was changed to 0.0190 mmol/min. Other than that, the same procedure as in Example 1 was carried out, with some of the main chains having an 8-branched structure derived from the branching agent structure (1) and a coupling agent having an 8-branched star-shaped polymer structure derived from the coupling agent. A conjugated diene polymer (Sample 6) was obtained. Table 1 shows the physical properties of Sample 6.

(Example 7) Coupled conjugated diene polymer (Sample 7)
The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), and the amount added was changed to 0.0160 mmol/min. Other than that, a coupling agent having a 4-branched structure derived from the branching agent structure (1) in part of the main chain and an 8-branched star-shaped polymer structure derived from the coupling agent was prepared in the same manner as in Example 1. A conjugated diene polymer (Sample 7) was obtained. Table 1 shows the physical properties of Sample 7.

(Example 8) Coupled conjugated diene polymer (Sample 8)
The addition rate of 1,3-butadiene was changed from 18.6 g/min to 24.3 g/min, the addition rate of styrene was changed from 10.0 g/min to 4.3 g/min, and 2,2-bis( The addition rate of 2-oxolanyl)propane was changed from 0.081 mmol/min to 0.044 mmol/min, and the coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (in the table). , abbreviated as "F") and the amount added was changed to 0.0160 mmol/min. A coupled conjugated diene polymer (Sample 8) having a branched structure and an 8-branched star-shaped polymer structure derived from a coupling agent was obtained. Table 1 shows the physical properties of Sample 8.

(Example 9) Coupled conjugated diene polymer (Sample 9)
The addition rate of 1,3-butadiene was changed from 18.6 g/min to 17.1 g/min, the addition rate of styrene was changed from 10.0 g/min to 11.5 g/min, and 2,2-bis( The addition rate of 2-oxolanyl)propane was changed from 0.081 mmol/min to 0.089 mmol/min, and the coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (in the table). , abbreviated as "F") and the amount added was changed to 0.0160 mmol/min. A coupled conjugated diene polymer (Sample 9) having a branched structure and an 8-branched star polymer structure derived from a coupling agent was obtained. Table 1 shows the physical properties of Sample 9.

(Example 10) Coupled conjugated diene polymer (Sample 10)
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, and the coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)- Branched some of the main chains in the same manner as in Example 1, except that 1,3-propanediamine (abbreviated as "F" in the table) was used and the amount added was changed to 0.0160 mmol/min. A coupled conjugated diene polymer (Sample 10) having a four-branched structure derived from the coupling agent structure (1) and an eight-branched star polymer structure derived from the coupling agent was obtained. Table 1 shows the physical properties of sample 10.

(Comparative Example 1) Coupled conjugated diene polymer (Sample 11)
A tank-type reactor with an internal volume of 10 L, a ratio of internal height (L) to diameter (D) (L/D) of 4.0, an inlet at the bottom, an outlet at the top, and a stirrer. Two tank-type pressure vessels each having a stirrer and a jacket for temperature control were connected as a polymerization reactor.
1,3-butadiene, from which water had been removed in advance, 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 piping that supplies this mixed solution to the inlet of the polymerization reactor, n-butyllithium for inactivating residual impurities was added and mixed at a rate of 0.103 mmol/min, and then the inlet of the polymerization reactor was mixed. Continuously fed to the bottom. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance was mixed vigorously with a stirrer at a rate of 0.081 mmol/min, and n-butyllithium was mixed as a polymerization initiator at a rate of 0.143 mmol/min. The mixture was supplied to the bottom of the polymerization reactor, and the internal temperature of the polymerization reactor was maintained at 67°C.
The polymer solution is continuously extracted from the top of the first polymerization reactor and continuously supplied to the bottom of the second polymerization reactor to continue the reaction at 70°C, and then a static mixer is added from the top of the second reactor. supplied to. When the polymerization was sufficiently stabilized, a small amount of the polymer solution before the addition of the coupling agent was taken out, an antioxidant (BHT) was added at a concentration of 0.2 g per 100 g of the polymer, the solvent was removed, and the solution was heated at 110°C. Mooney viscosity and various molecular weights were measured. The polymer before addition of the coupling agent was referred to as a conjugated diene polymer, and its physical properties are shown in Table 2.
Next, tetraethoxysilane (abbreviated as "A" in the table) was continuously added as a coupling agent to the polymer solution flowing out from the outlet of the reactor at a rate of 0.0480 mmol/min. The mixture was mixed using a mixer to perform 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, and the temperature was 68°C. The difference from the temperature was 2°C. After the coupling reaction, a small amount of the conjugated diene polymer solution is taken out, and an antioxidant (BHT) is added in an amount of 0.2 g per 100 g of the polymer, and then the solvent is removed and the amount of bound styrene (physical property 6) and The microstructure (1,2-vinyl bond amount: physical property 7) of the butadiene moiety was measured. The measurement results are shown in Table 2.
Next, an antioxidant (BHT) was continuously added to the coupling-reacted polymer solution at a rate of 0.055 g/min (n-hexane solution) at a rate of 0.2 g per 100 g of the polymer. The reaction has ended. At the same time as the antioxidant, as a rubber softener, SRAE oil (JOMO Process NC140 manufactured by JX Nippon Oil & Energy Corporation) was continuously added in an amount of 25.0 g per 100 g of polymer, and mixed with a static mixer. did. The solvent was removed by steam stripping to obtain a coupled conjugated diene polymer (sample 11) that had no main chain branches derived from the branching agent and had a 3-branched star-shaped polymer structure derived from the coupling agent. . Table 2 shows the physical properties of Sample 11.

(Comparative Example 2) Coupled conjugated diene polymer (Sample 12)
The coupling agent was changed from tetraethoxysilane to 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (abbreviated as "D" in the table), and the addition of Except that the amount was changed to 0.0360 mmol/min, the same procedure as in Comparative Example 1 was carried out, with no main chain branching derived from the nitrogen atom-containing branching agent and a four-branched star-shaped polymer structure derived from the coupling agent. A coupled conjugated diene polymer (Sample 12) was obtained.
Table 2 shows the physical properties of Sample 12.

(Comparative Example 3) Coupled conjugated diene polymer (Sample 13)
The coupling agent was changed from tetraethoxysilane to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "F" in the table), and the amount added was changed to 0.0190 mmol/min. In the same manner as in Comparative Example 1 except for this, a coupled conjugated diene polymer (Sample 13) having no main chain branching derived from the branching agent and having an 8-branched star-shaped polymer structure derived from the coupling agent was obtained. Ta. Table 2 shows the physical properties of Sample 13.

(Comparative Example 4) Coupled conjugated diene polymer (Sample 14)
The nitrogen atom-containing branching agent was changed to trimethoxy(4-vinylphenyl)silane (denoted as BS-1 in the table), which is a non-nitrogen atom-containing branching agent, and the amount added was 0.0190 mmol/min. and the coupling agent was changed to 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (abbreviated as "D" in the table), and the amount added. A coupling conjugate having a main chain branch derived from a branching agent and a four-branched star-shaped polymer structure derived from a coupling agent was prepared in the same manner as in Example 1, except that the amount was changed to 0.0360 mmol/min. A diene polymer (sample 14) was obtained. Table 2 shows the physical properties of Sample 14.
In Comparative Example 4, since a nitrogen atom-containing branching agent was not used as a branching agent, "modified branched conjugated diene polymer" is not described in the table, and "conjugated diene polymer" is not described in the table. ” to distinguish it from Examples 1 to 10 described above.

(Examples 11-20), (Comparative Examples 5-8)
Using Samples 1 to 14 shown in Tables 1 to 2 as raw material rubbers, rubber compositions containing the respective raw material rubbers were obtained according to the formulations shown below.

(rubber component)
・Coupled conjugated diene polymer (Samples 1 to 14)
:80 parts by mass (parts by mass excluding rubber softener)
・High-cis polybutadiene (trade name “UBEPOL BR150” manufactured by Ube Industries, Ltd.)
:20 parts by mass

(Combination conditions)
The amount of each compounding agent added was expressed in parts by mass relative to 100 parts by mass of the rubber component not containing the rubber softener.
・Silica 1 (product name: “Ultrasil 7000GR” manufactured by Evonik Degussa)
Nitrogen adsorption specific surface area 170 m ² /g): 50.0 parts by mass - Silica 2 (trade name "Zeosil Premium 200MP" manufactured by Rhodia)
Nitrogen adsorption specific surface area 220 m ² /g): 25.0 parts by mass - Carbon black (trade name "SEAST KH (N339)" manufactured by Tokai Carbon Co., Ltd.)
: 5.0 parts by mass - Silane coupling agent (trade name "Si75" manufactured by Evonik Degussa, bis(triethoxysilylpropyl) disulfide): 6.0 parts by mass - SRAE oil (manufactured by JX Nippon Oil & Energy Corporation) Product name “Process NC140”)
: 42.0 parts by mass (including the amount added in advance as a rubber softener contained in Samples 1 to 40)
・Zinc white: 2.5 parts by mass ・Stearic acid: 1.0 parts by mass ・Antioxidant (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 2.0 parts by mass・Sulfur: 2.2 parts by mass ・Vulcanization accelerator 1 (N-cyclohexyl-2-benzothiazylsulfinamide)
: 1.7 parts by mass - Vulcanization accelerator 2 (diphenylguanidine): 2.0 parts by mass - Total: 239.4 parts by mass

(Kneading method)
The above materials were kneaded by the following method to obtain a rubber composition.
Using a closed kneader (inner capacity 0.3 L) equipped with a temperature control device, raw rubber (samples 1 to 14), Fillers (silica 1, silica 2, carbon black), silane coupling agent, SRAE oil, zinc white and stearic acid were kneaded. At this time, the temperature of the closed 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, an antiaging agent was added, and the mixture was kneaded again in order to improve the dispersion of silica. In this case as well, the discharge temperature of the blend was adjusted to 155-160° C. by temperature control of the mixer.
After cooling, sulfur and vulcanization accelerators 1 and 2 were added and kneaded using open rolls set at 70° C. as the third stage of kneading.
Thereafter, it was molded and vulcanized in a vulcanization press at 160° C. for 20 minutes.
The rubber composition before vulcanization and the rubber composition after vulcanization were evaluated. Specifically, it was evaluated by the following method. The results are shown in Tables 3 and 4.

[Evaluation of characteristics]
(Evaluation 1) Mooney viscosity of the compound The compound obtained above after the second stage kneading and before the third stage kneading was used as a sample, using a Mooney viscometer, and measured at 130°C in accordance with ISO 289. After preheating for 1 minute, the viscosity was measured after rotating the rotor at 2 revolutions per minute for 4 minutes.
The results of Comparative Example 5 were set as 100 and indexed.
The smaller the index, the better the workability.

(Evaluation 2) Tensile strength and tensile elongation Tensile strength and tensile elongation were measured according to the tensile test method of JIS K6251, and the results of Comparative Example 5 were set as 100 and indexed.
The larger the index, the better the tensile strength and tensile elongation (fracture strength).

(Evaluation 3) Wear resistance Using an Akron 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 the results of Comparative Example 5 were was set as 100 and indexed.
The larger the index, the better the wear resistance.

(Evaluation 4) Viscoelastic parameters Viscoelastic parameters were measured in torsion mode using a viscoelasticity tester "ARES" manufactured by Rheometrics Scientific. Each measured value was expressed as an index, with the result for the rubber composition of Comparative Example 5 set as 100.
The tan δ measured at 0° C. at a frequency of 10 Hz and a strain of 1% was used as an index of wet skid property. The larger the index, the better the wet skid properties.
Further, tan δ measured at 50° C., frequency of 10 Hz, and strain of 3% was used as an index of fuel efficiency. The smaller the index, the better the fuel efficiency.
Furthermore, the elastic modulus (G') measured at 50° C. at a frequency of 10 Hz and a strain of 3% was used as an index of steering stability. The larger the index, the better the steering stability.

As shown in Tables 3 and 4, Examples 11 to 20 had a lower compound Mooney viscosity when made into a vulcanizate and exhibited good processability compared to Comparative Examples 5 to 8. It was confirmed that the material had excellent wear resistance, handling stability, and breaking strength when the material was used, and also had an excellent balance between low hysteresis loss and wet skid resistance.

The branched conjugated diene polymer obtained by the production method of the present invention has industrial applications in fields such as tire treads, automobile interior and exterior products, anti-vibration rubber, belts, footwear, foams, and various industrial products. there is a possibility.

Claims (10)

By polymerizing or copolymerizing a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound using an alkali metal compound or an alkaline earth metal compound as a polymerization initiator, a conjugated diene polymer having an active end can be produced. a polymerization step to obtain;
A branching step of introducing a branched structure by reacting a nitrogen atom-containing branching agent, which is a compound represented by the following formula (1), with the active end of the conjugated diene polymer;
have,
A method for producing a branched conjugated diene polymer.

(In formula (1), R ¹ to R ² each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms.
X ¹ is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen.
Y ¹ represents one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be independent and the same, or may be different. ) Further comprising a step of adding a conjugated diene compound and/or an aromatic vinyl compound to the reaction system during and/or after the branching step,
A method for producing a branched conjugated diene polymer according to claim 1. Further comprising a reaction step of reacting a coupling agent or a polymerization terminator with the active end of the branched conjugated diene polymer obtained in the branching step.
A method for producing a branched conjugated diene polymer according to claim 1 or 2. the coupling agent has a nitrogen atom-containing group,
A method for producing a branched conjugated diene polymer according to claim 3. The polymerization terminator has a nitrogen atom-containing group,
A method for producing a branched conjugated diene polymer according to claim 3. The polymerization terminator is an alkoxy compound having a nitrogen atom-containing group,
A method for producing a branched conjugated diene polymer according to any one of claims 3 to 5. A branched conjugated diene polymer obtained by the method for producing a branched conjugated diene polymer according to any one of claims 1 to 6,
Having a main chain branched structure derived from a nitrogen atom-containing branching agent, which is a compound represented by formula (1), in the polymer main chain,
Branched conjugated diene polymer.

(In formula (1), R ¹ to R ² each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms.
X ¹ is a single bond or an organic group containing any one selected from the group consisting of carbon, hydrogen, nitrogen, sulfur, and oxygen.
Y ¹ represents one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom. They may be independent and the same, or may be different. ) A rubber component containing 10% by mass or more of the branched conjugated diene polymer according to claim 7;
A rubber composition containing 5.0 parts by mass or more and 150 parts by mass or less of a filler based on 100 parts by mass of the rubber component. Obtaining a branched conjugated diene polymer by the production method according to any one of claims 1 to 6;
obtaining a rubber component containing 10% by mass or more of the branched conjugated diene polymer;
A step of containing a filler in an amount of 5.0 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the rubber component to obtain a rubber composition;
A method for producing a rubber composition, comprising: Obtaining a rubber composition by the method for producing a rubber composition according to claim 9;
A step of molding the rubber composition to obtain a tire;
A method for manufacturing a tire, comprising: