JP2023117650A - Production method of branched conjugated diene polymer, branched conjugated diene polymer, rubber composition, production method of rubber composition and production method of tire - Google Patents

Abstract

To provide a production method of a branched conjugated diene polymer capable of producing a branched conjugated diene polymer having a higher degree of branching than in a case when a branch structure is introduced to a conjugated diene polymer using merely a coupling agent, and in which a functional group is introduced into a principal chain of a conjugated diene polymer, the production method of a branched conjugated diene polymer capable of obtaining a rubber composition excellent in dispersibility of silica when made into a compound with the silica, and excellent in high mileage properties, abrasion resistance, wet skid resistance, rupture strength etc. when made into a compound of a vulcanizate.SOLUTION: A production method of a branched conjugated diene polymer includes: a polymerization step of polymerizing or copolymerizing a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound using an alkali metal compound or an alkaline-earth metal compound as a polymerization initiator, to obtain a conjugated diene polymer having an active terminal; and a branching step of reacting a branching agent containing a nitrogen atom with the active terminal of the conjugated diene polymer to introduce a branch structure.SELECTED DRAWING: None

Description

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

2. Description of the Related Art Conventionally, from the viewpoint of environmental load, there has been an increasing demand for low fuel consumption of automobiles. In particular, for automobile tires, improvements in fuel efficiency are required for materials used in the tread portion that is in direct contact with the ground.
In recent years, the development of materials with low rolling resistance, that is, low hysteresis loss has been desired.
In addition, there is a demand to reduce the weight of the tire, and it is demanded to reduce the thickness of the tire tread portion and to use a highly wear-resistant material for the tire tread portion.
On the other hand, from the viewpoint of safety, materials used for tire treads are required to have excellent wet skid resistance and practically sufficient breaking properties.

Materials that meet the above-mentioned various requirements include rubber materials containing rubber-like polymers and reinforcing fillers such as carbon black and silica.
By using a rubber material containing silica, it is possible to improve the balance between low hysteresis loss (indicator of low fuel consumption) and wet skid resistance. In addition, by introducing a functional group having affinity or reactivity with silica to the end of the molecule of the highly mobile rubber-like polymer, the dispersibility of silica in the rubber material is improved. Bonding with particles can reduce the mobility of the molecular ends of the rubber-like polymer, thereby reducing the hysteresis loss.
On the other hand, as a method of improving abrasion resistance, there is a method of increasing the molecular weight of the rubber-like polymer. However, increasing the molecular weight of the rubber-like polymer tends to deteriorate the workability when kneading the rubber-like polymer and the reinforcing filler.
In view of such circumstances, attempts have been made to introduce a branched structure into rubber-like polymers in order to increase the molecular weight without impairing processability.

For example, conventionally, a resin composition of silica and a modified conjugated diene-based polymer obtained by reacting an alkoxysilane containing an amino group with an active terminal of a conjugated diene-based polymer has been proposed.
Further, a modified conjugated diene-based polymer having a branched structure obtained by coupling reaction between an active terminal of the polymer and a polyfunctional silane compound has been proposed (see, for example, Patent Documents 1 and 2).
Furthermore, a technique has 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).

WO 2007/114203 Pamphlet International Publication No. 2016/133154 pamphlet WO2020/070961 Pamphlet

However, in the method of introducing a branched structure into a conjugated diene-based polymer by subjecting a polymer active terminal and a polyfunctional silane compound to a coupling reaction 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 capable of reacting with the active terminal of the polymer possessed by the polyfunctional silane compound, and does not exceed the number of groups capable of reacting. From the viewpoint of synthesizability, there is a problem that the number of reactive groups that can be imparted to one polyfunctional silane is limited, and thus the degree of branching of the resulting modified conjugated diene-based polymer is also limited. are doing.
In addition, in the technique of introducing a branched structure into the main chain by utilizing a styrene derivative as a branching agent disclosed in Patent Document 3, the resulting modified conjugated diene-based polymer has a functional group in the main chain. Therefore, when the modified conjugated diene-based polymer is blended with silica, etc., there is room for improvement in the dispersibility of silica, and when the blend is made into a vulcanizate, fuel efficiency and wear resistance are also improved. There is a problem that there is room for improvement.

Therefore, in the present invention, a conjugated diene polymer having a higher degree of branching can be produced than when a branched structure is introduced into a conjugated diene polymer using only a coupling agent. In addition to providing a method for producing a branched conjugated diene-based polymer, the length of which can be adjusted and the degree of freedom in polymer design is high. By providing a production method capable of introducing a functional group, silica has good dispersibility when made into a compound with silica or the like, and when the compound is made into a vulcanizate, fuel efficiency, wear resistance, An object of the present invention is to provide a method for producing a conjugated diene polymer having excellent wet skid resistance and breaking strength.

The present inventors have made intensive research and studies to solve the above-described problems of the prior art, and found that a conjugated diene-based polymer is reacted with a branching agent containing a nitrogen atom to form a branch point and a nitrogen atom in the main chain. The inventors have found that a branched conjugated diene-based polymer that can solve the above-described conventional problems can be obtained by introducing them simultaneously, and have completed the present invention.
That is, the present invention is as follows.

[1]
A conjugated diene-based polymer having an active terminal is obtained 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 polymerization step to obtain;
A branching step of reacting a branching agent containing a nitrogen atom with the active terminal of the conjugated diene-based polymer to introduce a branched structure;
have
A method for producing a branched conjugated diene-based polymer.
[2]
The method for producing a branched conjugated diene-based polymer according to [1] above, further comprising adding a conjugated diene compound and/or an aromatic vinyl compound to the reaction system during and/or after the branching step.
[3]
The method for producing a branched conjugated diene-based polymer according to [1] or [2] above, wherein the branching agent is a compound represented by the following formula (1) or (2).

(In Formula (1), R ¹ to R ⁵ each independently represent hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and R ⁶ and R ⁷ each independently represents an alkylene group having 1 to 20 carbon atoms.
m and n each independently represent an integer of 1 to 3, and (m+n) represents an integer of 2 or more. Each of R ² to R ⁵ is independent when a plurality of R 2 to R 5 are present. )

(In formula (2), R ⁸ to R ¹⁰ and R ¹² each independently represent hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to ²⁰ carbon atoms; It represents 1 to 20 alkylene groups.
m represents an integer of 1 to 3, and R ⁹ and R ¹⁰ are each independent when a plurality of R 9 and R 10 are present. )

[4]
Any one of the above [1] to [3], further comprising a reaction step of reacting a coupling agent or a polymerization terminator with the active terminal of the branched conjugated diene-based polymer obtained in the branching step. A method for producing the branched conjugated diene-based polymer described.
[5]
The method for producing a branched conjugated diene-based polymer according to [4] above, wherein the coupling agent has a nitrogen atom-containing group.
[6]
The method for producing a branched conjugated diene-based polymer according to [4] above, wherein the polymerization terminator has a nitrogen atom-containing group.
[7]
The method for producing a branched conjugated diene-based polymer according to any one of [4] to [6], wherein the polymerization terminator is an alkoxy compound having a nitrogen atom-containing group.
[8]
A branched conjugated diene-based polymer obtained by the method for producing a branched conjugated diene-based polymer according to any one of the above [1] to [7], wherein the polymer main chain contains the nitrogen atom. A branched conjugated diene-based polymer having a main chain branched structure derived from a branching agent.
[9]
a rubber component containing 10% by mass or more of the branched conjugated diene-based polymer according to [8];
A rubber composition containing 5.0 parts by mass or more and 150 parts by mass or less of a filler with respect to 100 parts by mass of the rubber component.
[10]
a step of obtaining a branched conjugated diene-based polymer by the production method according to any one of [1] to [7];
a step of obtaining a rubber component containing 10% by mass or more of the branched conjugated diene-based polymer;
A step of adding 5.0 parts by mass or more and 150 parts by mass or less of a filler to 100 parts by mass of the rubber component to obtain a rubber composition;
A method for producing a rubber composition.
[11]
A step of obtaining a rubber composition by the method for producing a rubber composition according to [10];
A step of molding the rubber composition to obtain a tire;
A method for manufacturing a tire.

According to the present invention, a branched conjugated diene polymer having a higher degree of branching can be produced than when a branched structure is introduced into a conjugated diene polymer using only a coupling agent. A method for producing a branched conjugated diene-based polymer in which a functional group is introduced into the chain can be provided. As a result, the dispersibility of silica is good when it is made into a compound with silica, etc., and when the compound is made into a vulcanized product, it is excellent in fuel efficiency, wear resistance, wet skid resistance, and breaking strength. It is possible to provide a method for producing a branched conjugated diene-based polymer from which a rubber composition obtained by the present invention can be obtained.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail.
It should be noted that the following embodiments are examples for explaining the present invention, and the present invention is not limited to the following embodiments. The present invention can be appropriately modified and implemented within the scope of the gist thereof.

[Method for producing branched conjugated diene-based polymer]
The method for producing a branched conjugated diene-based polymer of the present embodiment includes:
A conjugated diene-based polymer having an active terminal is obtained 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 polymerization step to obtain;
and a branching step of reacting the active terminal of the conjugated diene-based polymer with a branching agent containing a nitrogen atom to introduce a branched structure.

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

(Polymerization process)
In the polymerization step in the method for producing a branched conjugated diene-based polymer of the present embodiment, an alkali metal compound or an alkaline earth metal compound is used as a polymerization initiator, and a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound are produced. , polymerization or copolymerization to obtain a conjugated diene-based polymer having an active terminal.
In the polymerization step, it is preferable to carry out polymerization by a growth reaction based on a living anionic polymerization reaction, whereby a conjugated diene-based 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.
As the alkali metal compound, an organic lithium compound is preferably used, and an organic monolithium compound is more preferably used.
Alkaline earth metal compounds include, for example, organomagnesium compounds, organocalcium compounds, and organostrontium compounds. Also included are compounds of alkaline earth metal alkoxides, sulfonates, carbonates and amides.
Examples of organomonolithium compounds include, but are not limited to, low-molecular-weight compounds and solubilized oligomeric organomonolithium compounds.
In addition, the organic monolithium compound, in the bonding mode of the organic group and its lithium, for example, a compound having a carbon-lithium bond, a compound having a nitrogen-lithium bond, and a compound having a tin-lithium bond can be used. can be done.

The amount of the polymerization initiator to be used is preferably determined according to the target molecular weight of the conjugated diene polymer.
The amount of the monomer such as the conjugated diene compound used relative to the amount of the polymerization initiator used relates to the desired degree of polymerization of the 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-based polymer, the polymerization initiator should be adjusted in the direction of decreasing, and in order to lower the molecular weight, the polymerization initiator amount should be adjusted in the direction of increasing.

The organomonolithium compound is preferably an alkyllithium compound having a substituted amino group or a dialkylaminolithium from the viewpoint of being used as one method of 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 having no active hydrogen or having a structure in which the active hydrogen is protected.
Examples of the alkyllithium compound having an amino group having no active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexa Methyleneiminobutyllithium may be mentioned.
Examples of the alkyllithium compound having an amino group with a protected active hydrogen include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

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

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

The organomonolithium compound is preferably an alkyllithium compound from the viewpoint 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 compounds 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 preferable from the viewpoint of industrial availability and ease of control of the polymerization reaction.

These organic monolithium compounds may be used singly or in combination of two or more. Moreover, you may use together with another organometallic compound as a polymerization initiator.
Other organometallic compounds include, for example, alkaline earth metal compounds, other alkali metal compounds, and other organometallic compounds.
Alkaline earth metal compounds include, for example, organomagnesium compounds, organocalcium compounds, and organostrontium compounds, as described above. Also included are compounds of alkaline earth metal alkoxides, sulfonates, carbonates and amides.
Organomagnesium compounds include, for example, dibutylmagnesium and ethylbutylmagnesium.
Other organometallic compounds include, for example, organoaluminum compounds.

In the polymerization step, the polymerization reaction mode is not limited to the following, but includes, for example, a batch system (also referred to as a "batch system") and a continuous polymerization reaction mode.
In continuous mode, one or more connected reactors can be used. As the continuous reactor, for example, a tank-type or tubular-type reactor equipped with a stirrer is used. In the continuous system, preferably, a monomer, an inert solvent, and a polymerization initiator are continuously fed to a reactor, a polymer solution containing a polymer is obtained in the reactor, and the polymerization is continuously performed. The combined solution is discharged.
As the batch type reactor, for example, a tank type reactor equipped with a stirrer is used. In the batch system, the monomer, inert solvent, and polymerization initiator are preferably fed, and if necessary, the monomer is added continuously or intermittently during the polymerization, and the polymer is produced in the reactor. A polymer solution is obtained containing the polymer, and the polymer solution is discharged after completion of the polymerization.
In the method for producing a branched conjugated diene-based polymer of the present embodiment, in order to obtain a conjugated diene-based polymer having a high proportion of active terminals in the polymerization step, the polymer is continuously discharged and A continuous system is preferred because it can be subjected to the next reaction. In the continuous system, the number of reactors is not particularly limited, and one or two or more connected reactors can be used. The reactor is preferably one that allows sufficient contact between the monomer and the polymerization initiator in the solution, and may be of a vessel type equipped with a stirrer, a tubular type, or the like. Although the number of reactors can be selected as appropriate, the number of reactors is preferably one from the viewpoint of space saving of production equipment, and preferably two or more from the viewpoint of productivity improvement. When using two or more reactors, it is more preferable to add the branching agent after the second reactor.

In the polymerization step of the conjugated diene-based polymer, the polymerization is preferably carried out in an inert solvent.
Examples of inert solvents include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific 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; ; aromatic hydrocarbons such as benzene, toluene and xylene, and hydrocarbons consisting of mixtures thereof.
By treating allenes and acetylenes, which are impurities, with an organometallic compound before being subjected to a polymerization reaction, there is a tendency to obtain a conjugated diene polymer having a high concentration of active terminals, and a high modification rate. It is preferred because it tends to yield a conjugated diene polymer with a conjugated diene polymer.

A polar compound (polar substance) may be added in the polymerization step. Thereby, the aromatic vinyl compound and the conjugated diene compound can be randomly copolymerized. Polar compounds also tend to be used as vinylating agents to control the microstructure of the conjugated diene moiety. Furthermore, it tends to be effective in promoting the polymerization reaction and the like.
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. Ethers such as; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, quinuclidine; potassium-tert-amylate, potassium-tert-butylate, sodium-tert-butylate, sodium amine Alkali metal alkoxide compounds such as phosphate; phosphine compounds such as triphenylphosphine; and the like can be used.
These polar compounds may be used individually by 1 type, and may use 2 or more types together.

The amount of the polar compound to be used is not particularly limited and can be selected depending on the purpose, etc., but is preferably 0.01 mol or more and 100 mol or less per 1 mol of the polymerization initiator.
Such a polar compound also functions as a vinylating agent, and can be used in an appropriate amount as a microstructure adjusting agent for the conjugated diene portion of the conjugated diene polymer, depending on the desired amount of vinyl bonds.
Many polar compounds simultaneously have an effective randomization effect in the copolymerization of conjugated diene compounds and aromatic vinyl compounds, and can be used as agents for adjusting the distribution of aromatic vinyl monomer units and adjusting the amount of styrene blocks. tends to be possible.
As a method for 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 mixed. A method of starting the polymerization reaction and intermittently adding the remaining 1,3-butadiene during the copolymerization reaction may also be used.

The polymerization temperature in the polymerization step is preferably a temperature at which living anionic polymerization proceeds, and from the viewpoint of productivity, it is more preferably 0° C. or higher and 120° C. or lower.
With such a range, there is a tendency that a reaction amount of a branching agent or a coupling agent, which will be described later, with respect to the active terminal of the conjugated diene-based polymer after the completion of the polymerization process can be sufficiently ensured. Even more preferably, the temperature is 50°C or higher and 100°C or lower.

The conjugated diene-based 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 is not limited to the following. 3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-heptadiene, 1,3-hexadiene and the like. Among these, 1,3-butadiene and isoprene are preferred from the viewpoint of industrial availability. These may be used individually by 1 type, and may use 2 or more types together.

<Aromatic vinyl compound>
The aromatic vinyl compound is not particularly limited as long as it is a monomer copolymerizable with the conjugated diene compound. Examples include styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinyl xylene, vinylnaphthalene, diphenylethylene and the like. Among these, styrene is preferable from the viewpoint of industrial availability. These may be used individually by 1 type, and may use 2 or more types together.

(Branching step)
In the method for producing a branched conjugated diene-based polymer of the present embodiment, the active terminal of the conjugated diene-based polymer obtained in the polymerization step is reacted with a branching agent containing a nitrogen atom as a branching agent. , carrying out the branching step.
While the branching agent maintains its polymerization activity and polymerizes with the monomer, the functional group of the branching agent reacts with the active terminal of another polymer chain to form a branched structure in the polymer.
Further branched structures can be formed by polymerizing and reacting a conjugated diene-based polymer into which a branched structure has been introduced with a monomer and a branching agent. It is also possible to react with an agent to form a modified conjugated diene-based polymer, or to extend the polymer chain further by coupling.
In this embodiment, a branched conjugated diene-based polymer is produced using a branching agent, and the branched conjugated diene-based polymer has a portion derived from the branching agent containing a nitrogen atom.
In the present specification, "a portion derived from a branching agent containing a nitrogen atom" is, for example, a portion starting from a vinylsilane compound containing a nitrogen atom, which is a branching agent. Specifically, an alkoxy group and/or a halogen of an alkoxysilyl group and/or a halosilyl group of a vinylsilane compound containing a nitrogen atom becomes a leaving group, and a structure in which the polymerization active terminal is substituted; In addition, a vinylsilane compound containing a nitrogen atom is copolymerized with a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound.

<Branching agent>
The nitrogen atom-containing branching agent used in the branching step has a main skeleton in which only one active terminal remains at the branching site after the branching reaction, from the viewpoint of continuity of polymerization and prevention of gelation. Further, it preferably has reactivity sufficient to react with the polymerization active terminal during the branching reaction.
That is, the reaction of the branching agent causes the branching agent to be incorporated into the main chain while maintaining the polymerization activity, and another monomer is polymerized at the end where the activity is maintained, thereby further extending the polymer chain. In addition, the functional group of the incorporated branching agent reacts with the active terminal of another polymer chain to form a bond, 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 the polymer structure, it is also necessary that the functional group that is released after reacting with the active terminal of another polymer chain has little polymerization inhibitory effect. Here, the phrase "having little polymerization inhibitory action" includes little side reaction of anionic polymerization, such as chain transfer reaction, deactivation during polymerization, and decrease in activity due to an increase in the degree of association of the polymer.
The functional group possessed by the branching agent must not excessively improve the polymerization activity, and further must not deactivate the polymerization activity. When a polymer is polymerized by living anionic polymerization, it is important that it does not have a hydrogen atom as a functional group that does not deactivate the active terminal and is a hard base as defined by Pearson's HASB rule. A specific example is an alkoxy group. From among these, the structure of the branching agent used in the production method of the present embodiment should be selected from the viewpoint of reactivity with the active terminal and that the released functional group does not inhibit polymerization. can be done.

The branching agent used in the production method of this embodiment contains a nitrogen atom.
A preferred form of binding of the nitrogen atom of the nitrogen atom-containing branching agent used in the production method of the present embodiment is, for example, directly at the ortho, meta or para position of the benzene ring in the nitrogen atom-containing vinylsilane compound. It is preferably bound in the form of an amino group, and more preferably in the form of a tertiary amino group containing no active hydrogen from the viewpoint of not deactivating the polymerization active terminal.

The branching agent used in the production method of the present embodiment is preferably a vinylsilane compound containing a nitrogen atom. A compound having a form in which a silicon atom is bonded via is more preferable. That is, it preferably has a structure represented by Sty-NR-Si (Sty is a benzene ring structure having a vinyl group, and R represents an alkylene group having 1 to 20 carbon atoms). In the case of a form in which a silicon atom is directly bonded to a nitrogen atom, the silicon-nitrogen bond tends to break due to hydrolysis when it comes into contact with water by steam stripping or the like in the solvent removal step described later. The presence of an alkylene group (R in the above formula) between nitrogen and silicon prevents cleavage by hydrolysis, making it possible to form a desired branched structure.

In the branching agent having a nitrogen atom used in the production method of the present embodiment, the substituent that reacts with the polymerization active terminal of the conjugated diene polymer after the polymerization step is preferably, for example, a halogen group, an epoxy group, an alkoxy group, etc. Alkoxy groups are more preferred. When the substituent is an alkoxysilyl group, the branching agent is Sty-N-R-Si-ORn (Sty is a benzene ring structure having a vinyl group, R is an alkylene group having 1 to 20 carbon atoms, and OR is an alkoxy group. and n is an integer of 1 to 3.). In the branching step in the production method of the present embodiment, for example, when a branching agent having three alkoxy groups per silicon atom is used, i.e., 1 mol of trialkoxysilane group, 3 mol of conjugated diene When the active terminal of the silyl group is reacted, up to 2 mol of the conjugated diene polymer react with the conjugated diene polymer due to the decrease in basicity of the silyl group, but 1 mol of the alkoxy group tends to remain unreacted. Accordingly, when the number of alkoxy groups bonded to one silicon is one, the resulting polymer is unlikely to have a branched structure, so the number of alkoxy groups bonded to one silicon is preferably two or three. That is, Sty-NR-Si-ORn (Sty is a benzene ring structure having a vinyl group, R represents an alkylene group having 1 to 20 carbon atoms, OR represents an alkoxy group, and n is 2 or 3. ) is preferably represented. The remaining alkoxysilyl groups tend to easily become silanol (Si—OH groups) with moisture by steam stripping or the like in the solvent removal step described later.
The remaining silanol groups have the function of enhancing the dispersibility of silica when compounded with silica or the like, and tend to improve fuel economy and wear resistance.

In the production method of the present embodiment, the timing of adding the nitrogen atom-containing branching agent is not particularly limited, and can be selected according to the purpose. From the viewpoint of improving the coupling rate, the timing at which the raw material conversion rate after addition of the polymerization initiator is 20% or more is preferable, 40% or more is more preferable, 50% or more is further preferable, and 65% or more is preferable. and even more preferably 75% or more.

<Step of adding monomer>
In the production method of the present embodiment, during and/or after the branching step, a desired raw material monomer may be additionally added, and the polymerization step may be continued after the branching step, and the above-described contents may be repeated. good too.
Here, "after the branching step" means after adding the branching agent.
The monomer to be added is not particularly limited, but is preferably a conjugated diene compound and/or an aromatic vinyl compound. From the viewpoint of improving the modification rate by alleviating steric hindrance, the total amount of conjugated diene-based monomers used in the polymerization step, for example, the total amount of butadiene is preferably 5% or more, more preferably 10% or more. % or more, even more preferably 20% or more, and even more preferably 25% or more. In such a case, in particular, using a continuous polymerization process, during the branching step, the total amount of conjugated diene monomers used in the polymerization step, for example, adding monomers in an amount of 5% or more of the total amount of butadiene improves the modification rate. preferable from this point of view.
Since the length of the main chain and side chains can be adjusted by adjusting the timing of adding the branching agent and the amount of the added monomer, the degree of freedom in polymer design is high.

<Preferred Structure of Branching Agent>
The branching agent used in the production method of the present embodiment is a compound represented by the following formula (1) or (2), from the viewpoint of suppressing the chain transfer reaction, suppressing deactivation of the active terminal, and preventing gelation. preferable.

(In Formula (1), R ¹ to R ⁵ each independently represent hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and R ⁶ and R ⁷ each independently represents an alkylene group having 1 to 20 carbon atoms.
m and n each independently represent an integer of 1 to 3, and (m+n) represents an integer of 2 or more. Each of R ² to R ⁵ is independent when a plurality of R 2 to R 5 are present. )

Examples of the branching agent represented by formula (1) include, but are not limited to, compounds represented by the following formulas (M-1) to (M-4).
In formulas (M-1) to (M-4), Me represents a methyl group and Et represents an ethyl group.

(In formula (2), R ⁸ to R ¹⁰ and R ¹² each independently represent hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to ²⁰ carbon atoms; It represents 1 to 20 alkylene groups.
m represents an integer of 1 to 3, and R ⁹ and R ¹⁰ are each independent when a plurality of R 9 and R 10 are present. )

Examples of the branching agent represented by the formula (2) include, but are not limited to, compounds represented by the following formulas (M-5) to (M-8).
In formulas (M-5) to (M-8), Me represents a methyl group and Et represents an ethyl group.

The above branching agents may be used singly or in combination of two or more.

<Preferred form of branched conjugated diene-based polymer obtained in the branching step>
The branched structure of the branched conjugated diene-based polymer obtained in the branching step in the method for producing a branched conjugated diene-based polymer of the present embodiment preferably has 3 or more branches and 24 or less branches, more preferably 4 branches. It is more than 20 branches and more preferably more than 5 branches and less than 18 branches.
By making it 24 or less branches, it tends to be easy to react with a modifier having a functional group to form a modified conjugated diene-based polymer, or to further extend the polymer chain by a coupling reaction, and 3 or more branches. By doing so, the obtained branched conjugated diene-based polymer tends to be excellent in workability and abrasion resistance.

The amount of the branching agent to be added in the branching step is not particularly limited, and the amount to be added can be selected according to the purpose. From the viewpoint of continuity of polymerization after branching, the molar ratio of the branching agent to the amount of the active polymerization initiator is 1/2 or less, preferably 1/100 or more, and 1/3 or less. 1/50 or more is more preferable, 1/4 or less and 1/30 or more is more preferable, 1/6 or less and 1/25 or more is even more preferable, 1/8 or less 1/12 or more is even more preferred.

Further, as described above, additional monomer may be added during and/or after the branching step, and the polymerization step may be continued after branching, and the branching agent may be added after the additional addition of the monomer. , addition of monomer may be repeated.
By adding a monomer, steric hindrance around the branch point is alleviated, and effects such as improvement of polymerization continuity and improvement of coupling rate and modification rate can be obtained. This allows the formation of branches 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. A conjugated diene compound is preferable from the point of view. 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-based polymer containing a nitrogen atom into which a branched structure is introduced, obtained in the branching step in the production method of the present embodiment, has a Mooney viscosity of 10 or more and 150 or less measured at 110°C. is preferably 15 or more and 140 or less, still more preferably 20 or more and 130 or less, and even more preferably 30 or more and 100 or less.
When the Mooney viscosity is within the above range, the branched conjugated diene-based polymer obtained by the production method of the present embodiment tends to be excellent in workability and abrasion resistance.

The weight-average molecular weight of the branched conjugated diene-based polymer containing nitrogen atoms 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-based polymer obtained by the production method of the present embodiment tends to be excellent in workability, wear resistance, and a balance of these properties.
When a branched conjugated diene-based polymer modified by further performing a coupling step after the branching step and then reacting with a modifying agent is produced, the range of the weight average molecular weight is surely reached to 100,000 or more and 1,000,000 or less. For this purpose, the addition amount of the branching agent containing a nitrogen atom is controlled in a range of 1/3 or less and 1/50 or more in terms of molar ratio to the polymerization initiator to form branches while polymerizing. While preventing the initiator from being completely consumed before the coupling step, it is necessary to make the number of functional groups of the coupling agent more than two, and the weight average molecular weight range of the modified branched conjugated diene polymer In order to reach 200,000 or more and 900,000 or less, the amount of the nitrogen atom-containing branching agent added is controlled in the range of 1/3 or less and 1/50 or more in terms of molar ratio with respect to the polymerization initiator. At the same time, it is necessary that the number of functional groups of the coupling agent is 3 or more.

The branched conjugated diene-based polymer obtained by the production method of the present embodiment may be a polymer of a conjugated diene compound and a branching agent, or a polymer of an aromatic vinyl compound, a conjugated diene compound and a branching agent. They may be polymers or copolymers of these and other monomers.
For example, when the conjugated diene compound is butadiene or isoprene, and this is polymerized with a branching agent containing an aromatic vinyl portion, the polymer chain is so-called polybutadiene or polyisoprene, and the branch portion contains a structure derived from the aromatic vinyl. polymer. By having such a structure, it is possible to improve the linearity of each polymer chain and to improve the crosslink density after vulcanization, thereby achieving the effect of improving the wear resistance of the polymer. Therefore, it is suitable for applications such as tires, resin modification, automobile interior/exterior parts, anti-vibration rubber, and footwear.
When the branched conjugated diene-based polymer is used for tire treads, a copolymer of a conjugated diene compound, an aromatic vinyl compound, and a branching agent is suitable. It 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.
The amount of bound aromatic vinyl in the branched conjugated diene-based 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 more. It is more preferably 45% by mass or less.
When the amount of bound conjugated diene and the amount of bound aromatic vinyl are within the above ranges, the resulting vulcanizate tends to be excellent in balance between low hysteresis loss and wet skid resistance, abrasion resistance, and fracture properties.
Here, the amount of bound aromatic vinyl can be measured by ultraviolet absorption of the phenyl group, and the amount of bound conjugated diene can also be obtained from this. Specifically, it can be measured according to the method described in the examples below.

In the branched conjugated diene-based 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 vinyl bond content is within the above range, the vulcanizate tends to have a better balance between low hysteresis loss and wet skid resistance, wear resistance, and breaking strength.
Here, when the conjugated diene-based polymer is a copolymer of butadiene and styrene, by Hampton's method (RR Hampton, Analytical Chemistry, 21, 923 (1949)), The vinyl bond content (1,2-bond content) can be determined. Specifically, it can be measured by the method described in Examples described later.

Regarding the microstructure of the conjugated diene-based polymer, the amount of vinyl bonds, the amount of bound aromatic vinyl, and the amount of bound conjugated diene in the branched conjugated diene-based polymer obtained by the production method of the present embodiment are within the numerical ranges described above. Furthermore, when the glass transition temperature of the conjugated diene-based polymer is in the range of −80° C. or more and −15° C. or less, a vulcanizate having a better balance between low hysteresis loss and wet skid resistance is obtained. tend to be able to
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-based polymer obtained by the production method of the present embodiment is a conjugated diene-aromatic vinyl copolymer, the branched conjugated diene-based polymer has 30 or more aromatic vinyl units chained together. It is preferred that there are few or no blocks. More specifically, when the branched conjugated diene-based polymer obtained by the production method of the present embodiment is a butadiene-styrene copolymer, Kolthoff's method (IM KOLTHOFF, et al., J. Polym. Sci., 1, 429 (1946)) to decompose the polymer and analyze the amount of polystyrene insoluble in methanol. It is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, relative to the total amount of the conjugated diene polymer.

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

(Reaction step)
In the method for producing a branched conjugated diene-based polymer of the present embodiment, a coupling agent, for example, 3 Carrying out a step of coupling using a reactive compound having a functionality or higher, or a step of reacting the active terminal of the branched conjugated diene-based polymer with a polymerization terminator, for example, a reactive compound having a functionality of 2 or less. is preferred.
Hereinafter, the step of reacting a coupling agent (coupling step) or the step of reacting polymerization termination (polymerization termination step) are collectively referred to as a reaction step.
In the reaction step, one end of the active terminal of the 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-based polymer of the present embodiment, as a reaction step, the branched conjugated diene-based polymer obtained through the above-described polymerization step and branching step is coupled with a coupling agent. It is preferable to have a ring process.
The coupling step can efficiently lengthen the molecular chain, and the use of a tri- or higher-functional coupling agent can introduce branches into the polymer. Although the function of introducing branches is common to the step of using a branching agent, the coupling step uses a known coupling agent to introduce desired elements such as nitrogen, sulfur, and silicon. It is preferable from the viewpoint of being able to form a branch.
The coupling step includes, for example, a coupling step using a trifunctional or higher reactive compound to the active terminal of the branched conjugated diene polymer, or a coupling agent having a nitrogen atom-containing group ( Hereinafter, it may be collectively described as a “coupling agent”.) is preferably performed.

In the coupling step, for example, one end of the active terminal of the conjugated diene-based polymer is subjected to a coupling reaction with a reactive compound having a functionality of three or more, or a coupling agent having a nitrogen atom-containing group, thereby branching. It is possible to obtain a conjugated diene polymer into which the is introduced.

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

Examples of trifunctional or more reactive compounds having silicon atoms include, but are not limited to, halogenated silane compounds, epoxidized silane compounds, vinylated silane compounds, alkoxysilane compounds, alkoxysilane compounds containing a nitrogen-containing group, and the like. is mentioned.

Halogenated silane compounds as coupling agents include, but are not limited to, methyltrichlorosilane, tetrachlorosilane, tris(trimethylsiloxy)chlorosilane, tris(dimethylamino)chlorosilane, hexachlorodisilane, bis(trichlorosilyl)methane. , 1,2-bis(trichlorosilyl)ethane, 1,2-bis(methyldichlorosilyl)ethane, 1,4-bis(trichlorosilyl)butane, 1,4-bis(methyldichlorosilyl)butane and the like. .

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 that is a coupling agent include, but are not limited to, vinyltrimethoxysilane, vinyltriethoxysilane, and the like.

Alkoxysilane compounds that are coupling agents include, but are not limited to, tetramethoxysilane, tetraethoxysilane, triphenoxymethylsilane, 1,2-bis(triethoxysilyl)ethane, methoxy-substituted polyorganosiloxane, and the like. is mentioned.

[Coupling agent having nitrogen atom-containing group]
Examples of the coupling agent having a nitrogen atom-containing group include, but are not limited to, 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 preferably includes a functional group derived from an amine compound having no active hydrogen, and the amine compound includes, for example, tertiary Examples include amine compounds and protected amine compounds in which the above active hydrogen is substituted with a protecting group. Other compounds capable of forming a nitrogen atom-containing group include imine compounds represented by the general formula -N=C and alkoxysilane compounds bonded to the nitrogen atom-containing group.

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

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

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

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

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

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

In 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.
In 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.
In formula (i) above, R ³ is a hydrocarbon group having 1 to 10 carbon atoms or a structure represented by formula (ii) below.
R ¹ , R ² and R ³ may be cyclic structures bonded together.
Moreover, when R ³ is a hydrocarbon group, it may be a cyclic structure in which R is bonded to each other. In the case of the above cyclic structure, the form in which N bonded to R ³ and R are directly bonded may be used.
In the above formula (i), n is an integer of 1 or more, and m is 0 or an integer of 1 or more.

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

The epoxy compound, which is a coupling agent having a nitrogen atom-containing group, preferably has an epoxy group-containing hydrocarbon group, and more preferably has a glycidyl group-containing hydrocarbon group.

Epoxy group-containing hydrocarbon groups bonded to amino groups or ether groups include, but are not limited to, glycidylamino groups, diglycidylamino groups, or glycididoxy groups. A more preferred molecular structure is an epoxy group-containing compound having a glycidylamino group or diglycidylamino group and a glycididoxy group, respectively, and examples thereof include compounds represented by the following general formula (iii).

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

As the epoxy compound which is a coupling agent having a nitrogen atom-containing group, compounds having one or more diglycidylamino groups and one or more glycidoxy groups in the molecule are particularly preferred.

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) 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-xylylenediamine, 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 glycidylaniline, N,N-diglycidylorthotoluidine, 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 the alkoxysilane compound, which is a coupling agent having a nitrogen atom-containing group, include, but are not limited to, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropylmethyldimethoxysilane, 3-diethylaminopropyltriethoxysilane. , 3-morpholinopropyltrimethoxysilane, 3-piperidinopropyltriethoxysilane, 3-hexamethyleneiminopropylmethyldiethoxysilane, 3-(4-methyl-1-piperazino)propyltriethoxysilane, 1-[3 -(triethoxysilyl)-propyl]-3-methylhexahydropyrimidine, 3-(4-trimethylsilyl-1-piperazino)propyltriethoxysilane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane , 3-(3-trimethylsilyl-1-hexahydropyrimidinyl)propyltrimethoxysilane, 3-dimethylamino-2-(dimethylaminomethyl)propyltrimethoxysilane, bis(3-dimethoxymethylsilylpropyl)-N-methylamine , bis(3-trimethoxysilylpropyl)-N-methylamine, bis(3-triethoxysilylpropyl)methylamine, tris(trimethoxysilyl)amine, tris(3-trimethoxysilylpropyl)amine, N,N ,N′,N′-tetra(3-trimethoxysilylpropyl)ethylenediamine, 3-isocyanatopropyltrimethoxysilane, 3-cyanopropyltrimethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl )-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4- trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1- Phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane 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 capable of forming a primary or secondary amine and has an unsaturated bond and a protected amine in the molecule is not limited to the following: are, for example, 4,4′-vinylidenebis[N,N-bis(trimethylsilyl)aniline], 4,4′-vinylidenebis[N,N-bis(triethylsilyl)aniline], 4,4′-vinylidenebis [N,N-bis(t-butyldimethylsilyl)aniline], 4,4'-vinylidenebis[N-methyl-N-(trimethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N- (trimethylsilyl)aniline], 4,4′-vinylidenebis[N-methyl-N-(triethylsilyl)aniline], 4,4′-vinylidenebis[N-ethyl-N-(triethylsilyl)aniline], 4, 4′-vinylidenebis[N-methyl-N-(t-butyldimethylsilyl)aniline], 4,4′-vinylidenebis[N-ethyl-N-(t-butyldimethylsilyl)aniline], 1-[4 -N,N-bis(trimethylsilyl)aminophenyl]-1-[4-N-methyl-N-(trimethylsilyl)aminophenyl]ethylene, 1-[4-N,N-bis(trimethylsilyl)aminophenyl]-1 -[4-N,N-dimethylaminophenyl]ethylene and the like.

A protected amine compound that is a coupling agent having a nitrogen atom-containing group and capable of forming a primary or secondary amine and has an alkoxysilane and a protected amine in its molecule is 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)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 and the like, N-(1-methylpropylidene )-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-tri 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-based polymer obtained through polymerization step, branching step, and reaction step>
In the method for producing a branched conjugated diene-based polymer of the present embodiment, the branched conjugated diene-based polymer obtained through the above-described reaction step, particularly the step of reacting a coupling agent, has the following general formula (i), or , (A) to (C), and preferably contain a structure derived from a compound having a nitrogen atom-containing group.

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

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

In 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.
In 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.
In formula (i) above, R ³ is a hydrocarbon group having 1 to 10 carbon atoms or a structure represented by formula (ii) below.
R ¹ , R ² and R ³ may be cyclic structures bonded together.
Moreover, when R ³ is a hydrocarbon group, it may be a cyclic structure in which R is bonded to each other. In the case of the above cyclic structure, the form in which N bonded to R ³ and R are directly bonded may be used.
In the above formula (i), n is an integer of 1 or more, and m is 0 or an integer of 1 or more.

In formula (ii), R ¹ and R ² are defined in the same manner as R ¹ and R ² in formula (i) above, 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 is a 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 are present, they are each 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 are present, they are each 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 a R ¹⁹ and R ²² each independently represent an alkylene group having 1 to 20 carbon atoms, and R ²¹ represents an alkyl group having 1 to 20 carbon atoms or a trialkylsilyl group.
m represents an integer of 1 to 3, p represents 1 or 2;
R ¹² to R ²² , m and p when there are a plurality of each may be independent and may be the same or different.
i represents an integer of 0-6, j represents an integer of 0-6, k represents an integer of 0-6, and (i+j+k) represents an integer of 4-10.
A is a hydrocarbon group having 1 to 20 carbon atoms, or has at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom, and a phosphorus atom, and does not have active hydrogen. represents an organic group. )

Examples of the coupling agent 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 workability. things are preferred. 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 formula (A) with the polymerization active terminal are not particularly limited, but at 0 ° C. or higher and 120 ° C. or lower. , it is preferable to react for 30 seconds or longer.

The total number of moles of alkoxy groups bonded to silyl groups in the coupling agent compound having a nitrogen atom-containing group represented by formula (A) is the alkali metal compound and/or alkaline earth metal compound of the polymerization initiator. The range is preferably 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 2 It is more preferable to be in the range of 0.0 times or less. From the viewpoint of obtaining a sufficient modification rate, molecular weight, and branched structure of the obtained branched conjugated diene-based polymer, it is preferably 0.6 times or more. In addition to the fact that it is preferable to obtain the branched conjugated diene-based polymer component, from the viewpoint of the cost of the coupling agent, the ratio is preferably 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 number of moles of the coupling agent having a nitrogen atom-containing group represented by the formula (A). That's it.

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

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

Reaction temperature, reaction time, etc. when reacting the coupling agent having a nitrogen atom-containing group represented by the formula (B) with the active terminal of the branched conjugated diene-based polymer obtained in the branching step is not particularly limited, but it is preferable to react at 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 the formula (B) is 0.6 times or more the number of moles of lithium constituting the polymerization initiator described above, and 3.0. It is preferably in the range of 0.8 times or more and 2.5 times or less, more preferably in the 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-based polymer obtained by the production method of the present embodiment, it is preferably 0.6 times or more. In addition to preferably obtaining a branched conjugated diene-based polymer component by coupling the coalesced ends, it is preferable to reduce the coupling agent cost to 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 number of moles of the coupling agent having a nitrogen atom-containing group represented by the formula (B). That's it.

In the above 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 there are multiple B ¹ s, each independently there is.)

(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 is an integer of 1 to 10. Each of ^B2 and ^B3 is independent when there are a plurality of each.)

(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 there are a plurality of B ⁴ , each independently there is.)

(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 are a plurality of B ⁵ , each independently there is.)

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

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 formula (C), when A is represented by formula (III), the coupling agent having a nitrogen atom-containing group is not limited to the following, 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)-N1-methyl-N3-(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N3-(3-( trimethoxysilyl)propyl)-1,3-propanediamine.

In the above 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, 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 formula (C) above, 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 the structure represented by the formula (C) tends to be readily available, and the branched conjugated diene obtained by the production method of the present embodiment There is a tendency for the abrasion resistance and low hysteresis loss performance to become more excellent when the system polymer is made into a vulcanizate. Coupling agents having such a nitrogen atom-containing group include, but are not limited to, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2 -silacyclopentane)propyl]amine, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy -1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propane Diamine, 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 mentioned.

In 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-based polymer tends to be more excellent in wear resistance and low hysteresis loss performance when vulcanized.
Coupling agents having such a nitrogen atom-containing group include, but are not limited to, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1 ,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, and N ₁ -(3-( Bis(3-(trimethoxysilyl)propyl)amino)propyl)-N ₁ -methyl-N ₃ -(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N ₃ -(3- (Trimethoxysilyl)propyl)-1,3-propanediamine.

The addition amount of the compound represented by the formula (C) as the coupling agent having a nitrogen atom-containing group is determined by the molar number of the branched conjugated diene-based polymer before the coupling reaction versus the molar number of the coupling agent. It can be tailored to react in desired stoichiometric proportions, 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 number of moles of the coupling agent having a nitrogen atom-containing group represented by the formula (C). That's it.

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-based polymer obtained by the production method of the present embodiment, the ratio of the polymer having a nitrogen atom-containing group in the polymer is represented by the modification rate.
The modification rate is preferably 60% by mass or more, more preferably 65% by mass or more, still more preferably 70% by mass or more, even more preferably 75% by mass or more, still more preferably 80% by mass or more, and particularly preferably 82% by mass. It is mass % or more.
By setting the modification rate to 60% by mass or more, the vulcanizate tends to be excellent in workability, and the vulcanizate tends to be excellent in wear resistance and low hysteresis loss performance.

<Step of reacting polymerization terminator>
In the method for producing a branched conjugated diene-based polymer of the present embodiment, the above-described coupling agent or polymerization terminator is added to the active terminal of the branched conjugated diene-based polymer obtained through the above-described polymerization step and branching step. A reaction step of reacting the agents can be performed.
As the polymerization termination step, for example, a polymerization termination step performed using a bifunctional reactive compound on the active terminal of the branched conjugated diene polymer, or a polymerization termination agent having a nitrogen atom-containing group (hereinafter referred to as In addition, it may be described as a "polymerization terminator".) is preferable.

In the polymerization termination step, for example, a bifunctional reactive compound or a polymerization terminator having a nitrogen atom-containing group is applied to the active terminal of the branched conjugated diene-based polymer obtained in the above branching step. , the polymerization termination reaction can be carried out to obtain the desired branched conjugated diene polymer.

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

[Polymerization terminator having nitrogen atom-containing group]
In the method for producing a branched conjugated diene-based 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 preferably has 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 economy 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, 3 -(N,N-dipropylaminopropyl)dimethoxymethylsilane, 3-(N,N-dimethylaminopropyl)diethoxymethylsilane, 3-(N,N-diethylaminopropyl)diethoxymethylsilane, 3-(N ,N-dipropylaminopropyl)diethoxymethylsilane, 3-(N,N-dimethylaminopropyl)dimethoxyethylsilane, 3-(N,N-diethylaminopropyl)dimethoxyethylsilane, 3-(N,N-di 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-based polymer obtained through the above-described polymerization step, branching step, and reaction step by the production method of the present embodiment preferably has 8 branches or more and 36 branches or less, and more It preferably has 10 or more and 24 or less branches, more preferably 12 or more and 20 or less branches.
The total number of branch points in the branched conjugated diene-based 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 ranges described above, the workability, fuel economy, and wear resistance tend to be excellent.
When the branched conjugated diene-based polymer has a branched structure of 8 or more and 36 or less branches, and the modified polymer is obtained by reacting a modifier after the branching step and the coupling step, the total number of branch points is In order to construct one with 2 or more and 15 or less sites, the molar ratio of the branching agent is 1/2 or less and 1/100 or more of the polymerization initiator, and the number of functional groups of the coupling agent is 3. It is necessary to use more than sensuality. A polymer that does not require modification may have one or more branch points.
In order to construct a branched structure having 8 branches or more and 36 branches or less and a total number of branch points of 3 or more and 12 or less, the molar ratio of the branching agent is 1/3 or less of that of the polymerization initiator. It is preferable to use a coupling agent having 1/50 or more of the functional group and the number of functional groups of the coupling agent is 4 or more.
In order to construct a branched structure of 10 or more and 24 or less branches and a total number of branch points of 4 or more and 10 or less, the molar ratio of the branching agent is 1/6 or less of that of the polymerization initiator, and the reaction time is 25 minutes. is 1 or more, and the number of functional groups of the coupling agent is preferably 5 or more.
In order to construct a structure having a branched structure of 12 to 20 branches and a total number of branch points of 5 to 9, the molar ratio of the branching agent to that of the polymerization initiator is 1/8 or less. It is preferable to use a coupling agent having a functionality of 1/12 or more and a coupling agent having 6 or more functional groups.

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

(Hydrogenation process)
In the method for producing a branched conjugated diene-based polymer of the present embodiment, a hydrogenation step of hydrogenating the conjugated diene portion may be carried out.
The method for hydrogenating the conjugated diene portion of the branched conjugated diene-based polymer is not particularly limited, and known methods can be used.
A suitable hydrogenation method includes a method of hydrogenating by blowing gaseous hydrogen into a polymer solution in the presence of a catalyst.
The catalyst is not particularly limited, but for example, a heterogeneous catalyst such as a catalyst in which a noble metal is supported on a porous inorganic material; a catalyst in which a salt such as nickel or cobalt is solubilized and reacted with organic aluminum or the like; titanocene; homogeneous catalysts such as catalysts using the metallocene of Among these, a titanocene catalyst is preferable from the viewpoint of being able to select mild hydrogenation conditions. Hydrogenation of the aromatic group can also be carried out using a noble metal-supported catalyst.

Examples of 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-type hydrogenation catalyst using an organic acid salt such as Ni, Co, Fe, Cr or a transition metal salt such as acetylacetone salt and a reducing agent such as organic aluminum; So-called organometallic complexes such as organometallic compounds such as Zr can be used. Furthermore, the hydrogenation catalyst is not particularly limited, but for example, 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. 1 -53851, JP-B-2-9041 and JP-A-8-109219. Preferred hydrogenation catalysts include reaction mixtures of titanocene compounds and reducing organometallic compounds.

(Step of adding deactivator and neutralizer)
In the method for producing a branched conjugated diene-based polymer of the present embodiment, after the coupling step described above, a deactivator, a neutralizer, or the like may be added to the polymer solution, if necessary.
Examples of deactivators include, but are not limited to, water; alcohols such as methanol, ethanol, 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 (mixture of highly branched carboxylic acids containing 9 to 11 carbon atoms, mainly 10 carbon atoms). Acid; aqueous solution of inorganic acid, carbon dioxide gas.

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

(Step of adding softener for rubber)
In the method for producing a branched conjugated diene-based polymer of the present embodiment, the viewpoint of further improving the productivity of the branched conjugated diene-based polymer and the processability when blending a filler or the like to make a rubber composition. Therefore, if necessary, a rubber softener can be added.
Examples of rubber softeners include, but are not limited to, extender oils, liquid rubbers, resins, and the like.
The method of adding the rubber softener to the branched conjugated diene-based polymer is not limited to the following, but the rubber softener is added to the branched conjugated diene-based polymer solution and mixed to obtain a solution containing the rubber softener. A method of removing the solvent from the polymer solution of (1) is preferred.

Preferred extender oils include, for example, aromatic oils, naphthenic oils, paraffin oils, vegetable oils and the like. Among these, from the viewpoints of environmental safety, prevention of oil bleed and wet grip properties, aromatic alternative oils containing 3% by mass or less of polycyclic aromatic (PCA) components according to the IP346 method are preferable. Examples of alternative aromatic oils include TDAE (Treated Distillate Aromatic Extracts) and MES (Mild Extraction Solvate) shown in Kautschuk Gummi Kunststoffe 52 (12) 799 (1999), as well as RAE (Residual Aromatic Extracts). Extracts).
Preferred liquid rubbers include, but are not limited to, liquid polybutadiene, liquid, styrene-butadiene rubber, and the like.
The effect of adding a liquid rubber is that the processability of a resin composition containing a branched conjugated diene polymer and a filler or the like can be improved, and the glass transition of the resin composition can be improved. The ability to shift the temperature to the low temperature side tends to improve the wear resistance, low hysteresis loss, and low-temperature properties of the vulcanizate.
Resins used as rubber softeners include, but are not limited to, aromatic petroleum resins, coumarone-indene resins, terpene-based 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, and esters of hydrogenated oil resins and monofunctional or polyfunctional alcohols. These resins may be used alone or in combination of two or more. When hydrogenating, all of the unsaturated groups may be hydrogenated, or some of them may remain.
The effect of adding a resin as a softening agent for rubber is that it is possible to improve the processability of a resin composition containing a conjugated diene polymer and a filler, etc., and to improve the vulcanizate. and that the glass transition temperature of the resin composition can be shifted to a higher temperature side, thereby tending to improve the wet skid resistance.

The amount of the extender oil, liquid rubber, resin, or the like added as a softening agent for rubber is not particularly limited, but is preferably 1 part per 100 parts by mass of the branched conjugated diene-based polymer obtained by the production method of the present embodiment. The content is from 5 parts by mass to 60 parts by mass, more preferably from 5 parts by mass to 50 parts by mass, and even more preferably from 10 parts by mass to 37.5 parts by mass.
When the rubber softening agent is added within the above range, the processability of the resin composition obtained by blending the branched conjugated diene-based polymer obtained by the production method of the present embodiment with a filler and the like is improved, and Fracture strength and wear resistance tend to be good when converted to sulfide.

(Desolvation step)
In the method for producing a branched conjugated diene-based polymer of the present embodiment, a known method can be used as a method for obtaining the obtained branched conjugated diene-based polymer from a polymer solution. The method is not particularly limited, but for example, after the solvent is separated by steam stripping or the like, the polymer is separated by filtration, dehydrated and dried to obtain the polymer, concentrated in a flushing tank, Furthermore, a method of devolatilizing with a vent extruder or the like and a method of directly devolatilizing with a drum dryer or the like can be mentioned.

[Branched conjugated diene-based polymer]
The branched conjugated diene-based polymer of the present embodiment is a branched conjugated diene-based polymer obtained by the above-described method for producing a branched conjugated diene-based polymer of the present embodiment. It has a main chain branched structure derived from a branching agent containing atoms.

[Rubber composition and method for producing rubber composition]
The rubber composition of the present embodiment comprises a rubber component containing 10% by mass or more of the branched conjugated diene-based polymer of the present embodiment, which is produced by the above-described production method of the present embodiment, 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 the rubber composition of the present embodiment includes the steps of obtaining a branched conjugated diene-based polymer by the above-described production method, obtaining a rubber component containing 10% by mass or more of the branched conjugated diene-based polymer, A step of adding 5.0 parts by mass or more and 150 parts by mass or less of a filler to 100 parts by mass of the rubber component is included.
In addition, by including 10% by mass of the branched conjugated diene-based polymer obtained by the production method of the present embodiment in the rubber component, excellent fuel saving performance, workability, and abrasion resistance can be improved. .

The filler preferably contains a silica-based inorganic filler.
By dispersing a silica-based inorganic filler as a filler, the rubber composition tends to be more excellent in processability when vulcanized, and wear resistance, breaking strength, and low resistance when vulcanized. It tends 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 automobile parts such as tires and anti-vibration rubber, and shoes and the like, it preferably contains a silica-based inorganic filler.

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

Examples of rubber-like polymers include, but are not limited to, butadiene rubber or hydrogenated products thereof, isoprene rubber or hydrogenated products thereof, styrene-butadiene rubber or hydrogenated products thereof, styrene-butadiene block copolymers or their hydrogenated products, styrene-based elastomers such as styrene-isoprene block copolymers or hydrogenated products thereof, acrylonitrile-butadiene rubbers 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; Butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylate-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber. be done.

Examples of natural rubber include, but are not limited to, smoked sheet RSS Nos. 3-5, SMR, and epoxidized natural rubber.

The various rubber-like polymers described above may be modified rubbers to which polar functional groups such as hydroxyl groups and amino groups have been 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 rubber-like polymer is preferably 2,000 or more and 2,000,000 or less, more preferably 5,000 or more and 1,500,000 or less, from the viewpoint of the balance between various performances and processability of the rubber composition of the present embodiment. . Low-molecular-weight rubber-like polymers, so-called liquid rubbers, can also be used.
These rubber-like polymers may be used singly or in combination of two or more.

When the rubber composition using the branched conjugated diene-based polymer of the present embodiment is used as a rubber composition containing the above-described rubber-like polymer, the above-described branched conjugated diene-based polymer for the rubber-like polymer The content ratio (mass ratio) is preferably 10/90 or more and 100/0 or less, more preferably 20/80 or more and 90/10 or less, as (branched conjugated diene polymer/rubber-like polymer), and 50/50. 80/20 or less is more preferable.
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-described branched conjugated diene polymer relative to the total amount (100% by mass) of the rubber component. It contains 90 mass % or less, more preferably 50 mass % or more and 80 mass % or less.

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

Examples of fillers contained in the rubber composition of the present embodiment include, but are not limited to, carbon black, metal oxides, and metal hydroxides in addition to the silica-based inorganic fillers. Among these, silica-based inorganic fillers are preferred.
A filler may be used individually by 1 type, and may use 2 or more types together.
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 branched conjugated diene polymer. Part or less is preferable, and 30 to 90 parts by mass is more preferable.
In the rubber composition, the content of the filler is 5.0 parts by mass or more with respect to 100 parts by mass of the rubber component, from the viewpoint of expressing the effect of adding the filler. From the viewpoint of making the workability and mechanical strength of the product practically sufficient, 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 known ones can be used. Solid particles containing SiO 2 or Si 3 Al as} a _structural unit are preferable, and Solid particles included as a component are more preferred. Here, the main component means a component contained in the silica-based inorganic filler in an amount of 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more.

Examples of silica-based inorganic fillers include, but are not limited to, inorganic fibrous substances such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber. In addition, a silica-based inorganic filler having a hydrophobized surface, and a mixture of a silica-based inorganic filler and a non-silica-based inorganic filler may also be used.
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 preferable from the viewpoint of excellent balance of breaking strength improving effect and wet skid resistance.

From the viewpoint of obtaining practically good abrasion resistance and breaking strength in the rubber composition, the nitrogen adsorption specific surface area of the silica-based inorganic filler obtained by the BET adsorption method should be 100 m ² /g or more and 300 m ² /g or less. 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, 200 m ² /g or more) inorganic filler) can be used in combination.
Especially when using a silica-based inorganic filler having a relatively large specific surface area (for example, 200 m ² /g or more), the rubber composition containing the branched conjugated diene-based polymer improves silica dispersibility. In particular, it is effective in improving wear resistance, and tends to achieve a high balance between good breaking 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 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. parts are preferred, and 20 parts by mass or more and 100 parts by mass or less are more preferred. In the rubber composition, the content of the silica-based inorganic filler is preferably 5.0 parts by mass or more with respect to 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 with respect to 100 parts by mass of the rubber component.

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

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, and even 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 with respect to 100 parts by mass of the rubber component from the viewpoint of expressing the performance required for applications such as tires, such as dry grip performance and conductivity. From the viewpoint of dispersibility, it is preferably 100 parts by mass or less per 100 parts by mass of the rubber component.

A metal oxide is a solid particle whose structural unit is a main component of the chemical formula MxOy (M represents a metal atom, and x and y each independently represent an integer of 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 making the interaction between the rubber component and the inorganic filler closer. Specifically, it is preferable to use a compound that has an affinity or binding group for each of the rubber component and the silica-based inorganic filler, and has a sulfur-bonding portion and an alkoxysilyl group or silanol group portion in one molecule. .
Examples of such compounds include, but are not limited to, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, bis-[ 2-(Triethoxysilyl)-ethyl]-tetrasulfide.

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 with respect to 100 parts by mass of the inorganic filler described above. More preferably 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 adding the silane coupling agent tends to be more pronounced.

The rubber composition of the present embodiment may contain a rubber softening agent from the viewpoint of improving its processability.
The amount of the rubber softening agent to be added is such that the above-described branched conjugated diene-based polymer or other It is represented by the total amount of the softener for rubber contained in the rubber-like polymer and the softener for rubber added during the production of the rubber composition.
Suitable rubber softeners are mineral oils or liquid or low molecular weight synthetic softeners.
Mineral oil-based rubber softeners called process oils or extender oils used to soften, expand, and improve the processability of rubber are mixtures of aromatic rings, naphthenic rings, and paraffin chains. , The number of carbon atoms in the paraffin chain accounts for 50% or more of the total carbon is called paraffinic. Those whose number accounts for more than 30% of the total carbon are called aromatic systems.
When the branched conjugated diene-based polymer of the present embodiment contains a conjugated diene compound and an aromatic vinyl compound as polymerization monomers, the rubber softener to be used has 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 softener for rubber 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 with respect to 100 parts by mass of the rubber component. 90 parts by mass or less is more preferable. When the content of the softening agent for rubber is 100 parts by mass or less per 100 parts by mass of the rubber component, bleeding out is suppressed and stickiness on the surface of the rubber composition tends to be suppressed.

Branched conjugated diene polymers and other rubber-like polymers obtained by the production method of the present embodiment, silica-based inorganic fillers, carbon black and other fillers, silane coupling agents, rubber softeners, etc. The method of mixing the additives is not limited to the following, but for example, a general kneader such as an open roll, a Banbury mixer, a kneader, a single screw extruder, a twin screw extruder, a multi-screw extruder, etc. The melt-kneading method used and the method of removing the solvent by heating after dissolving and mixing the components can be mentioned.
Among these, melt-kneading methods using rolls, Banbury mixers, kneaders, and extruders are preferred from the viewpoint of productivity and good kneading properties. In addition, both a method of kneading the rubber component, other fillers, silane coupling agent, and additives at once, and a method of mixing them in multiple batches can be applied.

The rubber composition of the present embodiment may be a vulcanized composition that has been vulcanized with a vulcanizing agent. Examples of vulcanizing agents 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 with respect to 100 parts by mass of the rubber component, and 0.1 parts by mass or more and 15 parts by mass or less. more preferred. As the vulcanization method, a conventionally known method can be applied, and the vulcanization temperature is preferably 120° C. or higher and 200° C. or lower, more preferably 140° C. or higher and 180° C. or lower.

For vulcanization, a vulcanization accelerator may be used as necessary.
As the vulcanization accelerator, conventionally known materials can be used, and are not limited to the following; , thiourea-based and dithiocarbamate-based vulcanization accelerators.
Examples of vulcanizing aids include, but are not limited to, 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 with respect to 100 parts by mass of the rubber component.

In the rubber composition of the present embodiment, other softening agents and fillers than those mentioned above, heat stabilizers, antistatic agents, weather stabilizers, anti-aging agents, Various additives such as coloring agents and lubricants may be used.
As other softening agents, known softening agents can be used.
Examples of other fillers include, but are not particularly limited to, calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. Known materials can be used as the heat stabilizer, antistatic agent, weather stabilizer, anti-aging agent, colorant, and lubricant.

[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 comprises steps of obtaining a branched conjugated diene-based polymer by the manufacturing method of the present embodiment, obtaining a rubber composition containing the branched conjugated diene-based polymer, It has a step of molding the composition.
The rubber composition containing the branched conjugated diene-based polymer obtained by the production method of the present embodiment described above is suitably used as a rubber composition for tires.

Examples of rubber compositions for tires include, but are not limited to, various tires such as fuel-saving tires, all-season tires, high-performance tires, and studless tires: tread, carcass, sidewall, bead, etc. is available. In particular, the rubber composition for tires has an excellent balance between wear resistance, breaking strength, low hysteresis loss, and wet skid resistance when vulcanized, so it can be used for fuel-saving tires and high-performance tires. It is preferably used for treads.

EXAMPLES 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 by the following examples and comparative examples.
Various physical properties in Examples and Comparative Examples were measured by the methods described below.
A conjugated diene-based polymer coupled with a coupling agent is hereinafter referred to as a "coupling conjugated diene-based polymer".
A conjugated diene-based polymer having a branched structure derived from a branching agent containing a nitrogen atom is referred to as a "modified branched conjugated diene-based polymer".
Furthermore, coupling conjugated diene-based polymer, modified branched conjugated diene-based polymer, conjugated diene-based polymer that does not have a branched structure due to a branching agent, and conjugated diene-based polymer before coupling are collectively referred to as "conjugated diene It may be described as "system polymer".
In the examples described later, a conjugated diene-based polymer having a branched structure derived from a branching agent containing a nitrogen atom is referred to as a "modified branched conjugated diene-based polymer". The branched conjugated diene-based polymer produced by the method for producing a branched conjugated diene-based polymer of the invention is not limited at all.

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

(Physical properties 1) Polymer Mooney viscosity Using various conjugated diene polymers as samples, a Mooney viscometer (manufactured by Ueshima Seisakusho Co., Ltd., trade name “VR1132”) was used to measure Mooney viscosity using an L-shaped rotor in accordance with ISO 289 Viscosity was measured.
In Tables 1 and 2, the measurement temperature is 110° C. when the sample is the modified branched conjugated diene polymer before the addition of the coupling agent, and 110° C. when the sample is the coupling conjugated diene polymer. It was set to 100°C.
In Table 3, when a conjugated diene-based polymer without a branching agent is used as a sample and a branching agent that does not contain a nitrogen atom is used, the branching agent is replaced with a predetermined In the case of using the compound of , the temperature was set at 110° C. when the conjugated diene-based polymer before addition of the coupling agent was used as the sample.
First, after preheating the sample for 1 minute at the test temperature, the rotor was rotated at 2 rpm, and the torque after 4 minutes was measured to obtain the Mooney viscosity (ML ₍₁₊₄₎ ).

(Physical property 2) Mooney relaxation rate Using a coupling conjugated diene polymer as a sample, a Mooney viscometer (trade name “VR1132” manufactured by Ueshima Seisakusho Co., Ltd.) was used to measure the Mooney viscosity according to ISO 289 using an L-shaped rotor. After measuring, immediately stop the rotation of the rotor, record the torque every 0.1 seconds from 1.6 seconds to 5 seconds after stopping, and plot the torque and time (seconds) double logarithm was obtained, and the 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 by the GPC-light scattering method with a viscosity detector as follows.
Using a coupled conjugated diene polymer as a sample, a gel permeation chromatography (GPC) measurement device (manufactured by Malvern, trade name "GPCmax VE-2001") in which three columns filled with polystyrene gel are connected is used. Then, a light scattering detector, an RI detector, and a viscosity detector (manufactured by Malvern, trade name “TDA305”) are used for measurement using three detectors connected in that order. The absolute molecular weight was obtained from the measurement results of the scattering detector and the RI detector, and the intrinsic viscosity was obtained from the measurement results of the RI detector and the viscosity detector.
A linear polymer was used according to intrinsic viscosity [η]=10 ^−3.883 M ^0.771 and the shrinkage factor (g′) was calculated as the ratio of intrinsic viscosities corresponding to each molecular weight. In the formula, M represents an absolute molecular weight.
After that, the obtained shrinkage factor (g') was used to calculate the degree of branching (Bn) defined as g'=6Bn/[(Bn+1)(Bn+2)].
Tetrahydrofuran (hereinafter also referred to as “THF”) containing 5 mmol/L triethylamine was used as an eluent.
As the columns, Tosoh's trade names "TSKgel G4000HXL", "TSKgel G5000HXL" and "TSKgel G6000HXL" were connected and used.
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 measurement device and measured 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 condition 1>:
Various conjugated diene-based polymers such as modified branched conjugated diene-based polymers or coupling conjugated diene-based polymers are used as samples. Using the product name "HLC-8320GPC"), the chromatogram is measured using an RI detector (manufactured by Tosoh Corporation, product name "HLC8020"), and based on the calibration curve obtained using standard polystyrene, The weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) were determined.
THF (tetrahydrofuran) containing 5 mmol/L triethylamine was used as an eluent. As the columns, three columns of Tosoh's product name "TSKgel Super MultiporeHZ-H" were connected, and a Tosoh company's product name "TSKguardcolumn SuperMP(HZ)-H" was connected as a guard column in front of them.
10 mg of a sample for measurement was dissolved in 10 mL of THF to prepare a measurement solution, and 10 μL of the measurement solution was injected into a GPC measurement device and measured under the conditions of an oven temperature of 40° C. and a THF flow rate of 0.35 mL/min.
Among the various samples measured under measurement conditions 1 above, samples with a molecular weight distribution (Mw/Mn) value of less than 1.6 were measured again under measurement conditions 2 below. The measurement conditions 1 were used for the samples whose molecular weight distribution value was 1.6 or more.
<Measurement condition 2>:
Various conjugated diene-based polymers such as modified branched conjugated diene-based polymers or coupling conjugated diene-based polymers are used as samples, and using a GPC measurement apparatus in which three columns filled with polystyrene gel are connected, Chromatograms were measured to determine the weight average molecular weight (Mw) and number average molecular weight (Mn) based on a calibration curve using standard polystyrene.
THF containing 5 mmol/L triethylamine was used as the eluent. As the columns, guard columns: trade name "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation, columns: trade names "TSKgel SuperH5000", "TSKgel SuperH6000" and "TSKgel SuperH7000" manufactured by Tosoh Corporation were used.
An RI detector (trade name “HLC8020” manufactured by Tosoh Corporation) was used under 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 measurement device for measurement.
Measurement conditions 1 were used for measurement, and measurement conditions 2 were used for samples whose molecular weight distribution value was less than 1.6.

(Physical property 5) Modification rate The modification rate of the coupling conjugated diene polymer was measured by the column adsorption GPC method as follows.
Using a coupled conjugated diene-based polymer as a sample, measurement was performed by applying the characteristics of adsorption of a modified basic polymer component to a GPC column filled with silica-based gel.
A sample solution containing a sample and a low-molecular-weight internal standard polystyrene was measured with a polystyrene column and a chromatogram measured with a silica column, and the amount of adsorption to the silica column was measured from the difference. asked.
Specifically, it is as shown below.
In addition, the sample was measured under measurement condition 1 of (physical property 4) above, and the sample whose molecular weight distribution value was 1.6 or more was measured under measurement condition 3 below, and the measured value was adopted. Measurement was performed under measurement condition 1 of (physical property 4) above, and the sample whose molecular weight distribution value was less than 1.6 was measured under measurement condition 4 below, and the measured value was adopted.

<Preparation of sample solution>:
10 mg of sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF to prepare a sample solution.

<Measurement condition 3>:
GPC measurement conditions using a polystyrene column:
Using Tosoh's product name "HLC-8320GPC", using THF containing 5 mmol / L triethylamine as an eluent, injecting 10 μL of the sample solution into the device, column oven temperature 40 ° C., THF flow rate 0.35 mL / Chromatograms were obtained using an RI detector under conditions of minutes.
As for the columns, three columns manufactured by Tosoh under the trade name of "TSKgel SuperMultiporeHZ-H" were connected, and a guard column manufactured by Tosoh under the trade name of "TSKguardcolumn SuperMP (HZ)-H" was connected to the preceding column.
<Measurement condition 4>:
THF containing 5 mmol/L triethylamine was used as an eluent, and 20 μL of the sample solution was injected into the apparatus for measurement.
As the columns, guard columns: trade name "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation, columns: trade names "TSKgel SuperH5000", "TSKgel SuperH6000" and "TSKgel SuperH7000" manufactured by Tosoh Corporation were used. Under the conditions of a column oven temperature of 40° C. and a THF flow rate of 0.6 mL/min, measurement was performed using an RI detector (HLC8020 manufactured by Tosoh Corporation) to obtain a chromatogram.

GPC measurement conditions using a silica-based column:
Using Tosoh's trade name "HLC-8320GPC", using THF as an eluent, injecting 50 μL of the sample solution into the device, column oven temperature 40 ° C., THF flow rate 0.5 ml / min. A chromatogram was obtained using the detector. The columns are used by connecting the product names "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S". connected and used.

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

(Physical Property 6) Amount of Bound Styrene A coupling conjugated diene polymer containing no softener for rubber 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 (% by mass) with respect to 100% by mass of the coupling conjugated diene-based polymer as a sample was measured from the absorption amount of the ultraviolet absorption wavelength (around 254 nm) by the phenyl group of styrene (measuring device: Shimadzu Corporation). Spectrophotometer "UV-2450" manufactured by the company).

(Physical property 7) Microstructure of butadiene portion (1,2-vinyl bond content)
A coupling conjugated diene-based 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.
Using a solution cell, the infrared spectrum is measured in the range of 600 to 1000 cm ⁻¹ , and the absorbance at a predetermined wave number is measured by Hampton's method (RR Hampton, Analytical Chemistry 21, 923 (1949)). According to the formula, the microstructure of the butadiene portion, 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 (measuring device: Fourier manufactured by JASCO Corporation Conversion infrared spectrophotometer "FT-IR230").

(Physical property 8) GPC-Molecular weight by light scattering method measurement (absolute molecular weight)
Using a coupled conjugated diene-based polymer as a sample, a GPC-light scattering measurement device in which three columns filled with polystyrene gel are connected to measure a chromatogram, based on the solution viscosity and the light scattering method. The weight-average molecular weight (Mw-i) was determined by the method (also referred to as "absolute molecular weight").
A mixed solution of tetrahydrofuran and triethylamine (THF in TEA: prepared by mixing 5 mL of triethylamine with 1 L of tetrahydrofuran) was used as the eluent.
As the columns, a guard column (trade name: "TSKguardcolumn HHR-H" manufactured by Tosoh Corporation) and columns: trade names (trade names: "TSKgel G6000HHR", "TSKgel G5000HHR", and "TSKgel G4000HHR" manufactured by Tosoh Corporation) were connected and used.
A GPC-light scattering measurement device (trade name “Viscotek TDAmax” manufactured by Malvern) was used under 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 measurement device for measurement.

[Conjugated diene polymer]
(Example 1) Coupling conjugated diene polymer (Sample 1)
A tank reactor with an internal volume of 10 L, a ratio (L/D) of internal height (L) to diameter (D) of 4.0, an inlet at the bottom and an outlet at the top, and equipped with a stirrer. Two tank-type pressure vessels having a stirrer and a jacket for temperature control were connected as polymerization reactors.
18.6 g/min of 1,3-butadiene, 10.0 g/min of styrene, and 175.2 g/min of n-hexane, all of which had previously been dehydrated, were mixed. In a static mixer provided in the middle of the pipe for supplying this mixed solution to the inlet of the polymerization reactor, n-butyllithium for inactivation treatment of residual impurities was added at 0.103 mmol/min and mixed, and then the mixture was added to the polymerization reactor. Continuously fed to the bottom. Further, 2,2-bis(2-oxolanyl)propane as a polar substance at a rate of 0.081 mmol/min and n-butyllithium as a polymerization initiator at a rate of 0.143 mmol/min are vigorously mixed with a stirrer 1. It was supplied to the bottom of the primary reactor, and the internal temperature of the reactor was kept at 67°C.
The polymer solution was continuously withdrawn from the top of the first reactor, continuously supplied to the bottom of the second reactor, the reaction was continued at 70°C, and further supplied to the static mixer from the top of the second reactor.
When the polymerization was sufficiently stabilized, while copolymerizing 1,3-butadiene and styrene, the compound shown below as a branching agent (abbreviated as "M-1" in the table) was added from the bottom of the second reactor. ) was added at a rate of 0.0122 mmol/min to carry out a polymerization reaction and a branching reaction to obtain a modified branched conjugated diene-based polymer having a nitrogen atom-containing main chain branched structure.
Further, when the polymerization reaction and the branching reaction are stabilized, a small amount of the modified branched conjugated diene polymer solution before addition of the coupling agent is taken out, and an antioxidant (BHT) is added so as to be 0.2 g per 100 g of the polymer. After that, the solvent was removed and the Mooney viscosity at 110° C. and various molecular weights were measured. Physical properties are shown in Table 1.
Next, tetraethoxysilane (abbreviated as "A" in the table) is continuously added as a coupling agent to the polymer solution discharged from the outlet of the polymerization reactor at a rate of 0.0480 mmol/min, They were mixed using a static mixer and subjected to 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 from the temperature to was 2°C. A small amount of the coupling conjugated diene-based polymer solution after the coupling reaction was extracted, an antioxidant (BHT) was added to 0.2 g per 100 g of the polymer, the solvent was removed, and the amount of bound styrene (physical property 6) , and the microstructure of the butadiene portion (1,2-vinyl bond content: physical property 7). Table 1 shows the measurement results.
Next, an antioxidant (BHT) was continuously added to the coupling-reacted polymer solution at 0.055 g/min (n-hexane solution) so as to be 0.2 g per 100 g of the polymer, and coupling was performed. The reaction was finished. Simultaneously with the antioxidant, 25.0 g of SRAE oil (JOMO Process NC140 manufactured by JX Nippon Oil & Energy Co., Ltd.) was continuously added to 100 g of the polymer as a softener for rubber, and mixed with a static mixer. . The solvent is removed by steam stripping, and a branching agent containing a nitrogen atom (hereinafter referred to as "branching agent structure (M-1 )”.) and a tri-branched star polymer structure derived from the coupling agent (Sample 1) was obtained.
Table 1 shows the physical properties of Sample 1.
Regarding the polymer before adding the branching agent, the polymer after adding the branching agent, and the polymer in each step after adding the coupling agent, the molecular weight by GPC measurement and the GPC measurement with a viscometer The structure of the coupled conjugated diene-based polymer was identified by comparing with the degree of branching by . Hereinafter, the structure of each sample was identified in the same manner.

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

(Examples 2 to 6) Coupling conjugated diene polymers (Samples 2 to 6)
Same as Example 1, except that the coupling agent was changed from tetraethoxysilane to compounds "B" to "F" below, and the amount of each coupling agent added was changed to the amount shown in Table 1 below. Coupling conjugated diene polymers (Samples 2 to 6) were thus obtained.
The physical properties of Samples 2 to 6 are shown in Table 1 below.
"B": 1,2-bis (triethoxysilyl) ethane "C": 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane "D": 2-dimethoxy-1-(3-trimethoxy silylpropyl)-1-aza-2-silacyclopentane "E": tris (3-trimethoxysilylpropyl) amine "F": tetrakis (3-trimethoxysilylpropyl) -1,3-propanediamine

(Examples 7-8) Coupling conjugated diene polymer (Samples 7-8)
The branching agent was changed from "M-1" to the compound shown below (abbreviated as "M-2" in the table), and the coupling agent was changed from tetraethoxysilane to the above "D" and "F" compounds. Coupling conjugated diene polymers (Samples 7 and 8) were obtained in the same manner as in Example 1, except that the amount of each coupling agent added was changed to the amount shown in Table 1 below.
The physical properties of Samples 7 and 8 are shown in Table 1 below.

In formula (M-2), Et represents an ethyl group.

(Examples 9-10) Coupling conjugated diene polymers 9-10
The branching agent was changed from "M-1" to the compound shown below (abbreviated as "M-3" in the table), and the amount of the branching agent added was changed from 0.0122 mmol/min to 0.0203 mmol/min, Same as Example 1, except that the coupling agent was changed from tetraethoxysilane to the compounds "D" and "F" above, and the amount of each coupling agent added was changed to the amount shown in Table 1 below. Coupling conjugated diene polymers (Samples 9 and 10) were thus obtained.
The physical properties of Samples 9-10 are shown in Table 1 below.

In formula (M-3), Me represents a methyl group.

(Examples 11-12) Coupling conjugated diene polymers 11-12
The branching agent was changed from "M-1" to the compound shown below (abbreviated as "M-4" in the table), and the addition amount of the branching agent was changed from 0.0122 mmol/min to 0.0203 mmol/min, Same as Example 1, except that the coupling agent was changed from tetraethoxysilane to the compounds "D" and "F" above, and the amount of each coupling agent added was changed to the amount shown in Table 1 below. Coupling conjugated diene polymers (Samples 11 and 12) were thus obtained.
The physical properties of Samples 11 and 12 are shown in Table 1 below.

In formula (M-4), Et represents an ethyl group.

(Examples 13-18)
The branching agent was changed from "M-1" to the compound shown below (abbreviated as "M-5" in the table), and the addition amount of the branching agent was changed from 0.0122 mmol/min to 0.0203 mmol/min, Coupling was carried out in the same manner as in Example 1, except that the coupling agent was changed to the above compounds "A" to "F" and the amount of each coupling agent added was changed to the amount shown in Table 2 below. Conjugated diene polymers (Samples 13 to 18) were obtained.
The physical properties of Samples 13 to 18 are shown in Table 2 below.

In formula (M-5), Me represents a methyl group.

(Examples 19-20)
The branching agent was changed from "M-1" to the compound shown below (abbreviated as "M-6" in the table), and the addition amount of the branching agent was changed from 0.0122 mmol/min to 0.0203 mmol/min, Same as Example 1, except that the coupling agent was changed from tetraethoxysilane to the compounds "D" and "F" above, and the amount of each coupling agent added was changed to the amount shown in Table 2 below. Coupling conjugated diene polymers (Samples 19 and 20) were thus obtained.
The physical properties of Samples 19-20 are shown in Table 2 below.

In formula (M-6), Et represents an ethyl group.

(Examples 21-22)
The branching agent was changed from "M-1" to the compound shown below (abbreviated as "M-7" in the table), and the addition amount of the branching agent was changed from 0.0122 mmol/min to 0.0304 mmol/min, Example 1 was repeated except that the coupling agent was changed from tetraethoxysilane to the compounds "D" and "F" above, and the amount of each coupling agent added was changed to the amount shown in Table 2 below. Coupling conjugated diene polymers (Samples 21 and 22) were obtained.
The physical properties of Samples 21 and 22 are shown in Table 2 below.

In formula (M-7), Me represents a methyl group.

(Examples 23-24)
The branching agent was changed from "M-1" to the compound shown below (abbreviated as "M-8" in the table), and the addition amount of the branching agent was changed from 0.0122 mmol/min to 0.0304 mmol/min, Example 1 was repeated except that the coupling agent was changed from tetraethoxysilane to the compounds "D" and "F" above, and the amount of each coupling agent added was changed to the amount shown in Table 2 below. Coupling conjugated diene polymers (Samples 23 and 24) were obtained.
The physical properties of Samples 23 and 24 are shown in Table 2 below.

In formula (M-8), Et represents an ethyl group.

(Comparative Example 1) Coupling conjugated diene polymer (Sample 25)
A tank reactor with an internal volume of 10 L, a ratio (L/D) of internal height (L) to diameter (D) of 4.0, an inlet at the bottom and an outlet at the top, and equipped with a stirrer. Two tank-type pressure vessels having a stirrer and a jacket for temperature control were connected as polymerization reactors.
18.6 g/min of 1,3-butadiene, 10.0 g/min of styrene, and 175.2 g/min of n-hexane, all of which had previously been dehydrated, were mixed. In a static mixer provided in the middle of the pipe for supplying this mixed solution to the inlet of the polymerization reactor, n-butyllithium for inactivation treatment of residual impurities was added at 0.103 mmol/min and mixed, and then the mixture was added to the polymerization reactor. Continuously fed to the bottom. Further, 2,2-bis(2-oxolanyl)propane as a polar substance at a rate of 0.081 mmol/min and n-butyllithium as a polymerization initiator at a rate of 0.143 mmol/min are vigorously mixed with a stirrer 1. It was supplied to the bottom of the primary reactor, and the internal temperature of the polymerization reactor was kept at 67°C.
A polymer solution was continuously withdrawn from the top of the first reactor and continuously supplied to the bottom of the second reactor, and the reaction was continued at 70° C. without adding a branching agent.
Further, when the polymerization reaction is stabilized, a small amount of the conjugated diene polymer solution before the addition of the coupling agent is extracted, and an antioxidant (BHT) is added so as to be 0.2 g per 100 g of the polymer, and then the solvent is removed. Mooney viscosity at 110° C. and various molecular weights were measured. Physical properties are shown in Table 3.
Next, tetraethoxysilane (abbreviated as "A" in the table) is continuously added as a coupling agent to the polymer solution discharged from the outlet of the polymerization reactor at a rate of 0.0480 mmol/min, They were mixed using a static mixer and subjected to 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 from the temperature to was 2°C. A small amount of the coupling conjugated diene-based polymer solution after the coupling reaction was extracted, an antioxidant (BHT) was added to 0.2 g per 100 g of the polymer, the solvent was removed, and the amount of bound styrene (physical property 6) , and the microstructure of the butadiene portion (1,2-vinyl bond content: physical property 7). Table 3 shows the measurement results.
Next, an antioxidant (BHT) was continuously added to the coupling-reacted polymer solution at 0.055 g/min (n-hexane solution) so as to be 0.2 g per 100 g of the polymer, and coupling was performed. The reaction was finished. Simultaneously with the antioxidant, 25.0 g of SRAE oil (JOMO Process NC140 manufactured by JX Nippon Oil & Energy Co., Ltd.) was continuously added to 100 g of the polymer as a softener for rubber, and mixed with a static mixer. . The solvent was removed by steam stripping to obtain a coupled conjugated diene-based polymer (Sample 25) having a tri-branched star polymer structure derived from the coupling agent.
Table 3 shows the physical properties of Sample 25.
Regarding the polymer before the addition of the branching agent, the polymer after the addition of the branching agent, and the polymer in each step after the addition of the coupling agent, the molecular weight measured by GPC and the degree of branching measured by GPC with a viscometer. By comparison, the structure of the coupling conjugated diene polymer was identified. Hereinafter, the structure of each sample was identified in the same manner.

(Comparative Examples 2-3) Coupling conjugated diene polymers (Samples 26-27)
The same procedure as in Comparative Example 1 was repeated except that the coupling agent was changed from tetraethoxysilane to compounds "D" and "F" below, and the amount of each coupling agent added was changed to the amount shown in Table 3 below. Coupling conjugated diene polymers (Samples 26 and 27) were obtained.
The physical properties of Samples 26 and 27 are shown in Table 3 below.
"D": 2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane "F": tetrakis (3-trimethoxysilylpropyl)-1,3-propanediamine

(Comparative Examples 4-6) Coupling conjugated diene polymers (Samples 28-30)
As a branching agent containing no nitrogen atom, the compound shown below (abbreviated as "M-9" in the table) is added at 0.0152 mmol/min, and the coupling agent is added to the above "A", "D", Coupling conjugated diene polymers (Samples 28 to 30) were produced in the same manner as in Comparative Example 1, except that the compound of "F" was used and the amount of each coupling agent added was changed to the amount shown in Table 3 below. got
The physical properties of Samples 28-30 are shown in Table 3 below.

In formula (M-9), Me represents a methyl group.

(Comparative Examples 7-8) Coupling conjugated diene polymers (Samples 31-32)
As a branching agent containing no nitrogen atom, the compound shown below (abbreviated as "M-10" in the table) is added at 0.0203 mmol/min, and the coupling agent is added to the above "D" and "F". Coupling conjugated diene polymers (Samples 31 to 32) were obtained in the same manner as in Comparative Example 1, except that the amount of each coupling agent added was changed to that shown in Table 3 below. The physical properties of Samples 31 and 32 are shown in Table 3 below.

In formula (M-10), Me represents a methyl group.

(Comparative Examples 9-10) Coupling conjugated diene polymers (Samples 33-34)
A compound shown below containing a nitrogen atom and having no branching effect (abbreviated as "M-11" in the table) was added at 0.0152 mmol/min, and the coupling agent was added to the above "D" and "F". Coupling conjugated diene-based polymers (Samples 33 and 34) were obtained in the same manner as in Comparative Example 1, except that the compound was changed and the amount of each coupling agent added was changed to the amount shown in Table 3 below. The physical properties of Samples 33 and 34 are shown in Table 3 below.

(Comparative Examples 11-12) Coupling conjugated diene polymer (Samples 35-36)
A compound shown below containing a nitrogen atom and having no branching effect (abbreviated as "M-12" in the table) was added at 0.0152 mmol/min, and the coupling agent was added to the above "D" and "F". Coupling conjugated diene polymers (Samples 35 and 36) were obtained in the same manner as in Comparative Example 1, except that the amount of each coupling agent added was changed to that shown in Table 3 below. The physical properties of Samples 35-36 are shown in Table 3 below.

[Rubber composition]
(Examples 25-48), (Comparative Examples 13-25)
Using Samples 1 to 36 shown in Tables 1 to 3 as raw material rubbers, rubber compositions containing the respective raw rubbers were obtained according to the formulations shown below.

<Rubber component>
・Coupling conjugated diene polymer (Samples 1 to 36)
: 80 parts by mass (parts by mass without rubber softener)
・ Hi-cis polybutadiene (trade name “UBEPOL BR150” manufactured by Ube Industries, Ltd.)
: 20 parts by mass

<Combination conditions>
The amount of each compounding agent added is shown in parts by mass with respect to 100 parts by mass of the rubber component that does not contain a softening agent for rubber.
・ Silica 1 (trade name “Ultrasil 7000GR” manufactured by Evonik Degussa
Nitrogen adsorption specific surface area: 170 m / g): 50.0 parts by mass Silica 2 (trade name "Zeosil Premium 200MP" manufactured by Rhodia)
Nitrogen adsorption specific surface area: 220 m / g): 25.0 parts by mass ・Carbon black (trade name “Seist 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 (trade name “Process NC140” manufactured by JX Nippon Oil & Energy Corporation)
: 42.0 parts by mass (including the amount previously added as a rubber softener contained in samples 1 to 36)
Zinc white: 2.5 parts by mass Stearic acid: 1.0 parts by mass Anti-aging agent (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 2.0 parts by mass Parts 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 (contents 0.3 L) equipped with a temperature control device, raw rubber (Samples 1 to 36), Fillers (silica 1, silica 2, carbon black), silane coupling agent, SRAE oil, zinc oxide and stearic acid were kneaded. At this time, the temperature of the closed mixer was controlled, and each rubber composition (mixture) was obtained at a discharge temperature of 155 to 160°C.
Next, as the second step of kneading, after cooling the mixture obtained above to room temperature, an anti-aging agent was added, and kneading was performed again in order to improve dispersion of silica. Again, the temperature control of the mixer adjusted the discharge temperature of the formulation to 155-160°C.
After cooling, sulfur and vulcanization accelerators 1 and 2 were added and kneaded with an open roll set at 70° C. as the third stage of kneading.
After that, it was molded and vulcanized with a vulcanizing press at 160° C. for 20 minutes.
A rubber composition before vulcanization and a rubber composition after vulcanization were evaluated.
Specifically, it was evaluated by the following method. The results are shown in Tables 4 to 6.

[Evaluation of characteristics]
(Evaluation 1) Formulation Mooney Viscosity After the second stage kneading and before the third stage kneading obtained above as a sample, using a Mooney viscometer, 130 ° C. in accordance with ISO 289 , and after preheating for 1 minute, the viscosity was measured after rotating the rotor at 2 revolutions per minute for 4 minutes.
The result of Comparative Example 13 was indexed as 100. A smaller index indicates better workability.

(Evaluation 2) Tensile strength and tensile elongation The tensile strength and tensile elongation were measured according to the tensile test method of JIS K6251, and indexed with the result of Comparative Example 13 as 100. A larger index indicates better tensile strength and tensile elongation (breaking strength).

(Evaluation 3) Abrasion resistance Akron abrasion tester (manufactured by Yasuda Seiki Seisakusho) was used to measure the amount of abrasion at a load of 44.4 N and 1000 rotations in accordance with JIS K6264-2. was indexed as 100. A larger index indicates better wear resistance.

(Evaluation 4) Viscoelasticity parameter A viscoelasticity tester "ARES" manufactured by Rheometrics Scientific was used to measure the viscoelasticity parameter in torsional mode. Each measured value was indexed with the result for the rubber composition of Comparative Example 13 set to 100.
Tan δ measured at 0° C. with a frequency of 10 Hz and a strain of 1% was used as an index of wet skid resistance. A larger index indicates better wet skid resistance.
Also, tan δ measured at 50° C. with a frequency of 10 Hz and a strain of 3% was used as an index of fuel saving. A smaller index indicates better fuel economy.
Furthermore, the modulus of elasticity (G') measured at 50°C at a frequency of 10 Hz and a strain of 3% was used as an index of steering stability. A larger index indicates better steering stability.

(Evaluation 5) Silica dispersibility After the second stage of kneading and before the third stage of kneading, the sample was measured using a rotorless die rheometer, RPA2000 manufactured by Alpha Technologies, at a temperature of 100 ° C. and a frequency of 0.5 Hz. The elastic modulus (G') of the compound was measured by changing the strain from 0.1% to 1200% under the conditions of . ΔG′ obtained by subtracting the G′ value at a strain of 1200% from the G′ value at a strain of 0.5% was used as an index of silica dispersibility, and the result for the rubber composition of Comparative Example 13 was indexed as 100.
A smaller index indicates better dispersibility of silica.

As shown in Tables 4 to 6, Examples 25 to 48, as compared with Comparative Examples 13 to 25, exhibited good processability with low Mooney viscosity of the formulations when vulcanizates were obtained. It was confirmed that the wear resistance, steering stability, and breaking strength are excellent when the tire is crushed, and that the balance between low hysteresis loss and wet skid resistance is excellent.

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

Claims (11)

A conjugated diene-based polymer having an active terminal is obtained 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 polymerization step to obtain;
A branching step of reacting a branching agent containing a nitrogen atom with the active terminal of the conjugated diene-based polymer to introduce a branched structure;
have
A method for producing a branched conjugated diene-based polymer. further comprising adding a conjugated diene compound and/or an aromatic vinyl compound to the reaction system during and/or after the branching step;
The method for producing the branched conjugated diene-based polymer according to claim 1. The branching agent is a compound represented by the following formula (1) or (2),
The method for producing the branched conjugated diene-based polymer according to claim 1 or 2.

(In Formula (1), R ¹ to R ⁵ each independently represent hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and R ⁶ and R ⁷ each independently represents an alkylene group having 1 to 20 carbon atoms.
m and n each independently represent an integer of 1 to 3, and (m+n) represents an integer of 2 or more. Each of R ² to R ⁵ is independent when a plurality of R 2 to R 5 are present. )

(In formula (2), R ⁸ to R ¹⁰ and R ¹² each independently represent hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to ²⁰ carbon atoms; It represents 1 to 20 alkylene groups.
m represents an integer of 1 to 3, and R ⁹ and R ¹⁰ are each independent when a plurality of R 9 and R 10 are present. ) A reaction step of reacting a coupling agent or a polymerization terminator with the active terminal of the branched conjugated diene-based polymer obtained in the branching step,
further have
The method for producing a branched conjugated diene-based polymer according to any one of claims 1 to 3. The coupling agent has a nitrogen atom-containing group,
The method for producing the branched conjugated diene-based polymer according to claim 4. The polymerization terminator has a nitrogen atom-containing group,
The method for producing the branched conjugated diene-based polymer according to claim 4. The polymerization terminator is an alkoxy compound having a nitrogen atom-containing group,
The method for producing a branched conjugated diene-based polymer according to any one of claims 4 to 6. A branched conjugated diene-based polymer obtained by the method for producing a branched conjugated diene-based polymer according to any one of claims 1 to 7,
Having a main chain branched structure derived from the branching agent containing the nitrogen atom in the polymer main chain,
Branched conjugated diene polymer. A rubber component containing 10% by mass or more of the branched conjugated diene-based polymer according to claim 8;
A rubber composition containing 5.0 parts by mass or more and 150 parts by mass or less of a filler with respect to 100 parts by mass of the rubber component. A step of obtaining a branched conjugated diene-based polymer by the production method according to any one of claims 1 to 7;
a step of obtaining a rubber component containing 10% by mass or more of the branched conjugated diene-based polymer;
A step of adding 5.0 parts by mass or more and 150 parts by mass or less of a filler to 100 parts by mass of the rubber component to obtain a rubber composition;
A method for producing a rubber composition. A step of obtaining a rubber composition by the method for producing a rubber composition according to claim 10;
A step of molding the rubber composition to obtain a tire;
A method for manufacturing a tire.