JP7315409B2 - rubber composition - Google Patents

Description

The present invention relates to rubber compositions.

In recent years, the demand for low fuel consumption of automobiles has increased, and improvement of materials used for automobile tires, especially tire treads that come into contact with the ground, has been demanded.
In addition, in order to reduce the weight of the tire, it is necessary to reduce the thickness of the tread portion of the tire, and materials with high wear resistance are also required.
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 such demands include materials containing rubber-like polymers and reinforcing fillers such as carbon black and silica.
For example, using a material containing silica can improve the balance between low hysteresis loss and wet skid resistance.
Attempts have also been made to improve the dispersibility of silica in the material by introducing a functional group having affinity or reactivity with silica to the molecular terminal of a highly mobile rubber-like polymer, and to reduce the hysteresis loss by reducing the mobility of the molecular terminal of the rubber-like polymer by bonding with silica particles.

For example, Patent Documents 1 and 2 propose a polymer functionalized by reacting a cyclic azasilacycle compound with a polymer active terminal.
Further, Patent Document 3 proposes a diene rubber obtained by a coupling reaction between an active terminal of a polymer and a polyfunctional silane compound.

Japanese Patent Publication No. 2008-527150 WO 11/129425 pamphlet WO 07/114203 pamphlet

As described above, silica is blended as a filler with the aim of improving the balance between low hysteresis loss and wet skid resistance, but since silica has a hydrophilic surface, the affinity between the conjugated diene rubber and the filler with respect to carbon black having a hydrophobic surface is low, and the dispersibility is poor compared to carbon black. Therefore, silica-containing conjugated diene-based rubber materials are provided with a bond between silica and rubber, and in order to improve dispersibility, a silane coupling agent or the like is added separately, or a modified group having an affinity with silica is introduced into the polymer to improve the dispersibility of silica. Recently, improvements such as increasing the molecular weight of the polymer in order to increase the dispersibility of silica by branching the polymer and increasing the number of terminal modified groups or adopting a modified group with higher affinity, and to improve the wear resistance of the tire have been investigated.
On the other hand, a conjugated diene rubber material in which a functional group highly reactive with silica is introduced at the molecular end of the rubber has a problem that the reaction with silica particles progresses during the kneading process, but if the progress of the reaction is slow, it takes time for the torque to rise.
When such a conjugated diene rubber material is used as a vulcanizate, particularly when it is used as a vulcanizate containing an inorganic filler such as silica, there is room for improvement in terms of the balance between low hysteresis loss and wet skid resistance, and abrasion resistance.

Therefore, in the present invention, it is an object of the present invention to provide a rubber composition having good dispersibility of fillers and excellent low hysteresis loss by making it a composition that has relatively high torque increase rate and is easy to knead when kneading a rubber-like polymer and a filler with a mixer.

As a result of intensive studies to solve the above-described problems of the prior art, the present inventors have found that a modified conjugated diene polymer (A) having a weight average molecular weight, a molecular weight distribution, and a shrinkage factor within specific ranges and a modification rate of not less than a specific value, and a modified conjugated diene polymer (B) having two or more peak tops in a molecular weight curve by GPC, having a molecular weight distribution and a peak area of a low molecular weight peak within a specific range, and having a modification rate not less than a specific value. The inventors have found that the rubber composition containing the above-mentioned compound can solve the above-described problems of the prior art, and have completed the present invention.
That is, the present invention is as follows.

[1]
A rubber composition containing 100 parts by mass of a rubber-like polymer and 5 to 150 parts by mass of a filler,
A rubber composition in which the rubber-like polymer contains at least two types of modified conjugated diene-based polymers (A) and (B), the content of the modified conjugated diene-based polymer (A) in the rubber-like polymer is 30% by mass or more, and the modified conjugated diene-based polymers (A) and (B) each have the following characteristics.
[Modified conjugated diene polymer (A):
A modified conjugated diene polymer having a weight average molecular weight of 20×10 ⁴ or more and 300×10 ⁴ or less, a molecular weight distribution Mw/Mn of 1.6 or more and 4.0 or less, a modification rate of 50% by mass or more relative to the total amount of the conjugated diene polymer, and a shrinkage factor (g′) measured by gel permeation chromatography with a viscosity detector-light scattering method measurement (3D-GPC) of less than 0.86. ]
[Modified conjugated diene polymer (B):
A modified conjugated diene-based polymer having two or more peak tops in a gel permeation chromatography (GPC) curve, having a molecular weight distribution Mw/Mn of 1.0 or more and less than 1.6 for the peak with the lowest molecular weight and having a peak area of 2 to 50% relative to the total peak area, and a modified conjugated diene-based polymer having a modification rate of 50% by mass or more relative to the total amount of the conjugated diene-based polymer. ]
[2]
The rubber composition according to [1], wherein the modification rate of the peak top in the gel permeation chromatography (GPC) curve of the modified conjugated diene-based polymer (A), or the molecular weight of the peak top with the smallest molecular weight when there are a plurality of peak tops, is 1/2 or more of the modification rate of the component with a molecular weight of 1/2 or more relative to the total amount of the conjugated diene-based polymer (A).
[3]
The modified conjugated diene polymer (A) and/or (B) contains nitrogen and silicon, and the nitrogen and silicon contents in the modified conjugated diene polymer are each 3 mass ppm or more [1] or [2] The rubber composition according to.
[4]
The rubber composition according to any one of [1] to [3], wherein the modified conjugated diene polymer (A) and/or (B) contains nitrogen, and the nitrogen content in the modified conjugated diene polymer is 25 ppm by mass or more.
[5]
The rubber composition according to any one of [1] to [4], wherein the polymerization initiator residue of the modified conjugated diene polymer (A) does not contain nitrogen.
[6]
The rubber composition according to any one of [1] to [5], wherein the modified conjugated diene polymer (A) and/or (B) has a 3D-GPC shrinkage factor (g') of 0.70 or less.
[7]
The rubber composition according to any one of [1] to [6], wherein the modified conjugated diene polymer (A) and/or (B) is represented by the following general formula (I).
(In formula (I), D ₁ represents a diene polymer chain, R ¹ to R ³ each independently represent a single bond or an alkylene group having 1 to 20 carbon atoms, R ⁴ and R ⁷ each independently represent an alkyl group having 1 to 20 carbon atoms, R ⁵ , R ⁸ , and R ⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and R ⁶ and R ¹⁰ each independently It represents an alkylene group having 1 to 20 carbon atoms, and R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.
m and x represent an integer of 1 to 3, x≦m, p represents 1 or 2, y represents an integer of 1 to 3, y≦(p+1), and z represents an integer of 1 or 2.
D ₁ , R ¹ to R ¹¹ , m, p, x, y, and z when there are a plurality of them are each independent.
i represents an integer of 0 to 6, j represents an integer of 0 to 6, k represents an integer of 0 to 6, (i + j + k) is an integer of 1 to 10, and ((x x i) + (y x j) + (z x k)) is an integer of 1 to 30.
A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom and a phosphorus atom and having no active hydrogen. However, when (i+j+k) is 1, A may be absent. )

According to the present invention, it is possible to provide a rubber composition having good processability, especially when kneading a rubber-like polymer and a filler with a mixer, the torque increase rate is relatively high and the composition is easy to knead, so that the dispersibility of the filler is good and the rubber composition is excellent in low hysteresis loss.

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

The rubber composition of the present embodiment is a rubber composition containing 100 parts by mass of a rubber-like polymer and 5 to 150 parts by mass of a filler, wherein the rubber-like polymer contains at least two modified conjugated diene-based polymers (A) and (B), the content of the modified conjugated diene-based polymer (A) in the rubber-like polymer is 30% by mass or more, and the modified conjugated diene-based polymers (A) and (B) each have the following characteristics.
[Modified conjugated diene polymer (A):
A modified conjugated diene polymer having a weight average molecular weight of 20×10 ⁴ or more and 300×10 ⁴ or less, a molecular weight distribution Mw/Mn of 1.6 or more and 4.0 or less, a modification rate of 50% by mass or more relative to the total amount of the conjugated diene polymer, and a shrinkage factor (g′) measured by gel permeation chromatography with a viscosity detector-light scattering method measurement (3D-GPC) of less than 0.86. ]
[Modified conjugated diene polymer (B):
A modified conjugated diene-based polymer having two or more peak tops in a gel permeation chromatography (GPC) curve, having a molecular weight distribution Mw/Mn of 1.0 or more and less than 1.6 for the peak with the lowest molecular weight and having a peak area of 2 to 50% relative to the total peak area, and a modified conjugated diene-based polymer having a modification rate of 50% by mass or more relative to the total amount of the conjugated diene-based polymer. ]

[Modified conjugated diene polymer (A)]
The modified conjugated diene polymer (A) used in the present embodiment is a modified conjugated diene polymer having a weight average molecular weight of 20×10 ⁴ or more and 300×10 ⁴ or less, a molecular weight distribution Mw/Mn of 1.6 or more and 4.0 or less, a modified conjugated diene having a modification rate of 50% by mass or more relative to the total amount of the conjugated diene polymer, and a shrinkage factor (g′) by 3D-GPC of less than 0.86. It is a system polymer.

(Weight average molecular weight)
The weight average molecular weight of the modified conjugated diene polymer (A) used in the present embodiment is 20×10 ⁴ or more and 300×10 4 or less, preferably 30×10 4 or more and 270×10 ⁴ or less, more preferably 40× ^{10 4 or} more and 250×10 ⁴ or less, and even more preferably 50× ^{10 4 or} more and 250×10 ⁴ or less.
When the modified conjugated diene polymer (A) has a weight average molecular weight of 20×10 ⁴ or more and 300×10 ⁴ or less, the resulting vulcanizate has an excellent balance between low hysteresis loss and wet skid resistance and abrasion resistance.
Further, when the modified conjugated diene-based polymer (A) has a weight average molecular weight of 300×10 ⁴ or less, the vulcanizate has excellent filler dispersibility and excellent breaking properties.
Furthermore, when the modified conjugated diene-based polymer (A) has a high molecular weight, that is, when the weight-average molecular weight of the modified conjugated diene-based polymer (A) is greater than 50×10 ⁴ , the amount of polymerization initiator to be used is reduced. Therefore, termination of the growth reaction or chain transfer has a greater effect on the denaturation rate of the component with a molecular weight that is 1/2 the molecular weight at the top of the peak in the GPC curve. In this case, a modified conjugated diene polymer with a desired modification rate can be obtained by achieving ultra-high purity of the monomer and solvent introduced into the polymerization reactor, low-temperature polymerization, and a monomer conversion rate of less than 99% by mass.
The weight average molecular weight of the modified conjugated diene polymer (A) can be controlled within the above numerical range by adjusting the amount of the polymerization initiator relative to the monomer. Specifically, the weight average molecular weight can be lowered by increasing the amount of polymerization initiator relative to the monomer.
The weight average molecular weight of the modified conjugated diene-based polymer (A) can be measured by the method described in Examples below.

(Molecular weight distribution)
The modified conjugated diene polymer (A) used in the present embodiment has a molecular weight distribution Mw/Mn, which is represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), of 1.6 or more and 4.0 or less. The modified conjugated diene-based polymer (A) having a molecular weight distribution within this range tends to be more excellent in workability when forming a vulcanizate compared to polymers having similar molecular weights and modification ratios. It is preferably 1.8 or more and 3.0 or less, more preferably 1.9 or more and 2.5 or less.
The modified conjugated diene-based polymer (A) having such a molecular weight distribution can be preferably obtained by continuous polymerization.
The molecular weight distribution is preferably such that the molecular weight curve by GPC has a monomodal shape, or a trapezoidal or mountain range shape in the case of multiple peaks. A mountain range means a shape in which the height of the bottom between peaks is 50% or more of the height of the peaks on both sides. The modified conjugated diene-based polymer (A) having such a molecular weight distribution tends to be more excellent in workability when forming a vulcanizate.

Further, the modified conjugated diene-based polymer (A) used in the present embodiment preferably contains a modified conjugated diene-based polymer having a molecular weight of 2,000,000 or more and 5,000,000 or less (hereinafter also referred to as "specific high molecular weight component") in an amount of 0.3% by mass or more and 20% by mass or less. As a result, the vulcanizate tends to have a better balance between low hysteresis loss and wet skid resistance, and better wear resistance.
The content of the specific high molecular weight component is more preferably 1.0% by mass or more and 18% by mass or less, and still more preferably 2.0% by mass or more and 15% by mass or less.
In order to obtain a modified conjugated diene-based polymer (A) in which the content of the specific high-molecular-weight component is within such a range, for example, the amount of the organic monolithium compound used as a polymerization initiator, which will be described later, may be adjusted.
Specific methods in the continuous system are not particularly limited, but examples thereof include a method of using a tank-type reactor with a stirrer and using it as a back-mixing reactor in which the reactor is vigorously mixed with a stirrer, preferably a method of using a complete mixing-type reactor, a method of using a tubular reactor and partly recirculating it, a method of providing an inlet in the middle of the polymerization vessel in addition to the monomer inlet or its vicinity as a feed location for the polymerization initiator, and a method of using a combination of tank-type and tubular-type reactors.
According to these methods, the residence time distribution can be widened, and a polymer component having a long residence time can be made into a high molecular weight component.
Further, the specific method in the batch system is not particularly limited, but examples thereof include a method of feeding the polymerization initiator continuously or intermittently from the start of polymerization to the middle of polymerization, and a method of continuously or intermittently feeding at the start of polymerization and/or during polymerization.
According to this method, the polymer polymerized from the start of polymerization when the polymerization initiator is first fed becomes a high-molecular-weight component, and a difference in molecular weight occurs between the polymer that starts polymerization later. More specifically, if the amount of polymerization initiator corresponding to the target molecular weight is continuously fed to the monomer, for example, the conversion rate is from 0% by mass to 95% by mass, there is a tendency that a polymer having an expanded molecular weight distribution can be obtained.
By using the above-described method, the active ratio of the living terminal of the conjugated diene-based polymer before the modification step tends to increase, and the coupling rate after coupling, that is, the modified conjugated diene-based polymer with a high modification rate tends to be obtained. Among these methods, more preferred is the method of using a tank-type reactor with a stirrer as a back-mix reactor in which the materials are vigorously mixed with a stirrer.

In addition, in this specification, "molecular weight" is a standard polystyrene conversion molecular weight obtained by GPC (gel permeation chromatography).
The number average molecular weight, weight average molecular weight and molecular weight distribution can be measured by the methods described in Examples below.

(denaturation rate)
The modified conjugated diene-based polymer (A) used in the present embodiment has a modification rate of 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, relative to the total amount of the conjugated diene-based polymer. Although the upper limit of the modification rate is not particularly limited, it is, for example, 98% by mass or less.
When the modification rate is 50% by mass or more, the vulcanizate has a better balance between low hysteresis loss and wet skid resistance.
In addition, when the modification rate is 50% by mass or more, the rate of increase in torque when kneading with a filler tends to be high and the maximum value reached by the torque tends to be high when compared to a polymer with a low modification rate (modification rate of less than 50% by mass) with respect to the total amount of conjugated diene-based polymers having the same Mooney viscosity, microstructure, modifier used, kneading conditions, etc.

The modification rate is the percentage by mass of the content of the polymer component having a specific functional group having affinity or binding reactivity with the filler relative to the total amount of the conjugated diene polymer.
The polymer component having a specific functional group having affinity or bonding reactivity with the filler in the polymer molecule preferably includes a polymer having a functional group containing a nitrogen atom, a silicon atom or an oxygen atom. More preferably, it is a modified conjugated diene polymer having the functional group at the end of the polymer. Examples thereof include a modified conjugated diene-based polymer modified with a functional group having a functional group containing a nitrogen atom, a silicon atom, and an oxygen atom, typically as a modifier residue, at the polymerization initiation end and/or at the end of the polymerization.
Modification rate can be measured by chromatography that can separate functional group-containing modified and non-modified components. As a method using this chromatography, a column for gel permeation chromatography filled with a polar substance such as silica that adsorbs a specific functional group is used, and an internal standard of non-adsorbed components is used for comparison. More specifically, the modification rate is calculated by calculating the difference between the chromatogram measured with a polystyrene gel column and the chromatogram measured with a silica column for a sample solution containing a measurement sample and a low-molecular-weight internal standard polystyrene. Therefore, the adsorption amount to a silica column can be measured.
The modification rate can be measured by the method described in Examples below.
The modification rate of the modified conjugated diene-based polymer (A) used in the present embodiment with respect to the total amount of the conjugated diene-based polymer tends to be controllable within the above numerical range depending on the amount of the modifier added and the reaction. Specifically, the modification rate increases by increasing the amount of the modifier added, and/or lowering the polymerization temperature, and/or performing polymerization using an organolithium compound having at least one nitrogen atom in the molecule described later as a polymerization initiator.

(Modification rate of low molecular weight component)
In the modified conjugated diene polymer (A) used in the present embodiment, when there is one peak in the GPC curve, the peak top of that peak, or when there are multiple peak tops, the molecular weight is 1/2 of the molecular weight of the peak top with the smallest molecular weight (hereinafter sometimes referred to as a low molecular weight component). It is more preferable to have It is preferably 0.55 or more, more preferably 0.57 or more. Although the upper limit of the modification rate of the low-molecular-weight component in the modified conjugated diene polymer (A) is not particularly limited, it is, for example, 0.95 or less of the modification rate with respect to the total amount of the modified conjugated diene polymer (A).
As a result, it is possible to obtain a modified conjugated diene polymer (A) that has good processability, particularly when kneaded with a filler, a rubber composition having better filler dispersibility can be obtained in a shorter time.
Since the kneading time is short, the heat deterioration of the polymer can be minimized, and the heat stabilizer to be blended can be reduced. In addition, since the kneading time is short, the productivity is improved.

The following mechanism is presumed as how the torque is transmitted when the polymer and filler are kneaded.
First, focusing on the modification ratio of the modified conjugated diene-based polymer (A) to the total amount of the conjugated diene-based polymer, when the Mooney viscosity of the polymer, the microstructure, the modifier used, the kneading conditions, etc. are the same, a polymer with a high modification ratio (modification ratio of 50% or more) relative to the total amount of the conjugated diene-based polymer has a faster rate of torque increase when kneaded with a filler compared to a polymer with a low modification ratio, but on the other hand, the maximum torque reaches is also high. Therefore, the time taken to reach the maximum torque value is almost the same even if the overall transformation rate is changed. In other words, the modification rate of the polymer as a whole affects both the maximum torque value and the rate of increase in torque. As a result, even if the modification rate as a whole increases or decreases, it is thought that the length of time required to reach the maximum torque value is not significantly affected.
On the other hand, when focusing on the modification rate of the low-molecular weight component, that is, the 1/2 modification rate, the lower the 1/2 modification rate with respect to the total amount of the conjugated diene polymer, the slower the torque increase rate when kneading the polymer with the filler, and the higher the 1/2 modification rate with respect to the total amount of the conjugated diene polymer, the faster the torque increase rate.
As described above, the rate of increase in torque is also affected by the rate of modification with respect to the total amount of the conjugated diene-based polymer, but regardless of whether the "rate of modification with respect to the total amount of the conjugated diene-based polymer" is high or low, the higher the "1/2 modification rate", the faster the rate of torque increase. That is, the influence of the "1/2 modification rate" relative to the "modification rate relative to the total amount of the conjugated diene polymer" on the torque increase rate is constant regardless of the "modification rate relative to the total amount of the conjugated diene polymer".
On the other hand, when the modified conjugated diene-based polymer is only one component (polymer A only) and the polymer and the filler are kneaded, the maximum value of torque is determined depending on the modification rate of the entire modified conjugated diene-based polymer. Therefore, the time until the torque reaches the maximum value can be controlled by the height of the 1/2 modification rate with respect to the total amount of the conjugated diene polymer, regardless of the modification rate with respect to the total amount of the conjugated diene polymer.
Specifically, by setting the 1/2 modification rate to 1/2 or more of the modification rate with respect to the total amount of the conjugated diene polymer, processability, particularly when kneading with the filler, the dispersibility of the filler is improved in a short time. In addition, by setting the modification rate of the low-molecular weight component to 1/2 or more of the modification rate with respect to the total amount of the conjugated diene-based polymer, when a vulcanized composition containing the modified conjugated diene-based polymer (A) used in the present embodiment is formed, the composition has a high degree of freedom in designing a composition that has a good balance between low hysteresis loss and wet skid resistance, excellent fracture characteristics and wear resistance, and is particularly excellent in fuel efficiency for tires.
When producing a rubber composition for tires, it is effective to use a modified conjugated diene-based polymer with a higher degree of branching and/or a higher molecular weight in order to improve fuel efficiency. However, by adopting a technique for improving the processability of the modified conjugated diene-based polymer, even if a modified conjugated diene-based polymer with a higher degree of branching and/or a high molecular weight is used, problems in the kneading process or the like can be prevented from occurring, and as a result, it becomes easier to prepare a composition more suitable for tires.
From this point of view, in the modified conjugated diene polymer (A) used in the present embodiment, the modified conjugated diene polymer (A) is such that the peak top in the GPC curve, or when there are a plurality of peak tops, the molecular weight of the component having a molecular weight that is 1/2 of the molecular weight of the peak top with the smallest molecular weight, that is, the modification rate of the low molecular weight component, is set to 1/2 or more of the modification rate with respect to the total amount of the conjugated diene polymer. is preferred.
The modified conjugated diene-based polymer (A) used in the present embodiment can be obtained by a polymerization method that causes very little termination of the growth reaction or chain transfer, and therefore can be achieved with ultra-high purity of the monomer and solvent introduced into the polymerization reactor, low-temperature polymerization, and a monomer conversion rate of less than 99% by mass.
The modified conjugated diene polymer (A) used in the present embodiment can also be obtained by kneading a high molecular weight modified conjugated diene polymer and a low molecular weight modified conjugated diene polymer.
The modification rate for each molecular weight component can be measured by chromatography capable of separating functional group-containing modified components from non-modified components. As a method using this chromatography, a column for gel permeation chromatography filled with a polar substance such as silica that adsorbs a specific functional group is used, and an internal standard of non-adsorbed components is used for comparison. More specifically, the modification rate of each molecular weight component is obtained by measuring the amount of adsorption to a silica-based column from the difference between the chromatogram of a sample solution containing a measurement sample and a low-molecular-weight internal standard polystyrene measured with a polystyrene-based gel column and a chromatogram measured with a silica-based column for each molecular weight component. In addition, the modification rate can be measured by the method described in Examples below.
In order to obtain a modified conjugated diene-based polymer (A) in which the modification rate of the peak top in the GPC curve, or the molecular weight of the component with the molecular weight that is 1/2 of the molecular weight of the peak top with the smallest molecular weight when there are multiple peak tops, is 1/2 or more of the modification rate with respect to the total amount of the conjugated diene-based polymer, it is effective to adopt a method of increasing the purity of the monomer and solvent introduced into the reactor and reducing the amount of the terminal deactivated during polymerization.

(Nitrogen content)
In the modified conjugated diene-based polymer (A) used in the present embodiment, the nitrogen content in the modified conjugated diene-based polymer measured using a trace total nitrogen analyzer is 3 ppm by mass or more and 70 mass ppm or less, preferably 6 mass ppm or more and 60 mass ppm or less, more preferably 10 mass ppm or more and 50 mass ppm or less.
When the nitrogen content is 3 ppm by mass or more, the vulcanizate has a better balance between low hysteresis loss and wet skid resistance. In addition, when the nitrogen content is 70 ppm by mass or less, it is possible to suppress deterioration in rigidity due to excessive dispersion of silica in the formulation. By employing a nitrogen-containing compound as a modifier, there is a tendency that the nitrogen content can be increased to 3 ppm by mass or more.

Further, in the modified conjugated diene-based polymer (A) used in the present embodiment, another preferred embodiment is that the nitrogen content in the modified conjugated diene-based polymer measured using a trace total nitrogen analyzer is 25 ppm by mass or more. The nitrogen content in the modified conjugated diene-based polymer (A) is more preferably 40 mass ppm or more, more preferably 70 mass ppm or more, and preferably 500 mass ppm or less, more preferably 400 mass ppm or less, and further preferably 250 mass ppm or less. When such a modified conjugated diene polymer (A) is made into a vulcanizate, it has a better balance between low hysteresis loss and wet skid resistance. Examples of the modified conjugated diene-based polymer (A) having a nitrogen content of 25 ppm by mass or more include polymers in which nitrogen-containing modifying groups are bonded to both the polymerization initiation terminal and the polymerization termination terminal. Such a polymer can be produced, for example, by continuously polymerizing a conjugated diene-based polymer using an organolithium compound having at least one nitrogen atom in the molecule as a polymerization initiator, and then reacting with a modifier having at least one nitrogen atom in the molecule.
By using a polymerization initiator containing a nitrogen atom and reacting a modifier having a nitrogen atom at the polymerization termination terminal, the nitrogen content tends to be 25 mass ppm or more, while the polymerization initiation terminal side is also modified. Therefore, the modification rate of the low molecular weight component is also increased. That is, the use of a nitrogen-containing polymerization initiator is one of the methods for obtaining a polymer with a high modification rate of low-molecular-weight components without using highly purified raw materials as described above. On the other hand, when a modifier having a nitrogen atom on the polymerization end side is reacted without using a nitrogen-containing polymerization initiator, particularly when the modifier acts as a coupling agent to form a branched polymer, the higher the molecular weight component, the higher the modification rate.

(contraction factor)
In the modified conjugated diene-based polymer (A) used in the present embodiment, a modified conjugated diene-based polymer having a shrinkage factor (g′) measured by gel permeation chromatography with a viscosity detector-light scattering method (3D-GPC) (hereinafter simply referred to as shrinkage factor (g′)) of less than 0.86 is preferred.
Such a modified conjugated diene-based polymer (A) reduces the viscosity of a rubber composition to which a filler is added, and provides excellent workability.
The shrinkage factor (g′) is an index of the branched structure of the modified conjugated diene copolymer, and the modified conjugated diene polymer (A) having a shrinkage factor (g′) of less than 0.86 includes a modified conjugated diene polymer containing a molecule having four or more branches per molecule of the modified diene polymer.
In order to obtain the modified conjugated diene-based copolymer (A) having the predetermined shrinkage factor (g′), for example, it is effective to add a modifying agent having four or more reaction points with the living active terminal at a molar number of 1/4 or less with respect to the total number of moles of the polymerization initiator to obtain a modified conjugated diene-based copolymer having four or more branches.

Furthermore, the modified conjugated diene-based polymer (A) used in the present embodiment more preferably has a shrinkage factor (g') determined by 3D-GPC of 0.70 or less.
With such a modified conjugated diene polymer (A), the viscosity of the composition to which a filler is added becomes lower, and the workability becomes more excellent.
The shrinkage factor (g′) is an index of the branched structure of the modified conjugated diene copolymer, and the modified conjugated diene polymer (A) having a shrinkage factor (g′) of 0.70 or less is a modified conjugated diene polymer containing a molecule having 5 or more branches per molecule of the modified diene polymer.
In order to obtain a modified conjugated diene copolymer (A) having a shrinkage factor (g') within the above range, for example, a method of adding a modifier having five or more reaction points with living active terminals in a molar number of 1/5 or less of the total number of moles of the polymerization initiator to obtain a modified conjugated diene copolymer having five or more branches is effective.
Although the lower limit of the shrinkage factor (g') of the modified conjugated diene copolymer (A) is not particularly limited, it is, for example, 0.25 or more.

The shrinkage factor (g′) measured by GPC with a viscosity detector-light scattering method measurement (hereinafter also simply referred to as “GPC with a viscosity detector-light scattering method measurement” or “3D-GPC measurement”) is an index of the number of branches of the modified conjugated diene polymer. For example, as the shrinkage factor (g′) decreases, the number of branches of the modified conjugated diene-based polymer (for example, the number of branches of the star polymer (also referred to as “the arm number of the star polymer”)) tends to increase.
When comparing modified conjugated diene-based polymers having the same molecular weight, the shrinkage factor (g′) decreases as the number of branches of the modified conjugated diene-based polymer increases. Therefore, the shrinkage factor (g′) in this case can be used as an index of the degree of branching.
Contraction factor (g') is measured using 3D-GPC measurements.
Constants (K, α) in the relational expression between intrinsic viscosity and molecular weight ([η] = KMα ([η]: intrinsic viscosity, M: molecular weight) are set to log K = -3.883, α = 0.771. Enter the range of molecular weight M from 1000 to 20000000, and create a graph of the relationship between standard intrinsic viscosity [η] ₀ and molecular weight M.
With respect to this standard intrinsic viscosity [η] ₀ , the intrinsic viscosity [η] at each molecular weight M of the sample obtained by 3D-GPC measurement is calculated as the relationship between the intrinsic viscosity [η] to the standard intrinsic viscosity [η] ₀ [η]/[η] ₀ at each molecular weight M, and the average value is taken as the shrinkage factor (g').
More specifically, it can be measured by the method described in Examples below.

(Structure of modified conjugated diene polymer (A))
The modified conjugated diene-based polymer (A) may have a branched structure.
The modified conjugated diene-based polymer (A) having a branched structure may have one branch point or a plurality of branch points in one polymer.
The modified conjugated diene-based polymer (A) used in the present embodiment is preferably a modified conjugated diene-based polymer having a functional group having affinity or reactivity with the filler in the polymerization initiator residue and/or the modifier residue.
That is, the modified conjugated diene-based polymer (A) used in this embodiment preferably comprises a modifier residue having a functional group and a conjugated diene-based polymer chain.
In the modified conjugated diene-based polymer (A), the polymerization initiator residue preferably does not contain nitrogen. In the modified conjugated diene-based polymer (A), when the polymerization initiator residue does not contain nitrogen, it reacts with the filler at a moderate rate, so sheet processability tends to be good even in the initial stage of multi-stage kneading.

(denaturant residue)
The modifier residue in the modified conjugated diene-based polymer (A) used in the present embodiment is a structural unit of the modified conjugated diene-based polymer that is bonded to the conjugated diene-based polymer chain.
The modifier residue preferably has a specific functional group that has affinity or binding reactivity with the filler.
When the modified conjugated diene-based polymer (A) used in the present embodiment is a modified conjugated diene-based polymer having a functional group bonded to the polymerization initiation terminal, the modified conjugated diene-based polymer (A) can be obtained by performing a polymerization reaction using a polymerization initiator having a functional group.

<Terminal>
When the modified conjugated diene-based polymer (A) does not have a branched structure, the modified conjugated diene-based polymer (A) has a linear structure, and the term "terminal" means both ends of the linear chain, one of which is bound to the modifier residue and the other is bound to the polymerization initiator residue.
When the modified conjugated diene-based polymer (A) has a branched structure and at least one of the branch points is a modifier residue, the "end" in the modified conjugated diene-based polymer (A) refers to the end of the conjugated diene-based polymer chain that is not bonded to the branch point, for example, the "modifier residue". First, a monomer is polymerized using a polymerization initiator, and then a modifying agent is bonded to the terminal end of polymerization to form a branch point. When the modified conjugated diene-based polymer (A) has a branched structure and does not have a branch point due to a modifier residue, the "end" in the modified conjugated diene-based polymer (A) means the end of the conjugated diene-based polymer chain that is not bonded to the branch point, and has a modifier residue or a polymerization initiator residue.

(Preferred embodiment for functional groups)
The specific functional group having affinity or bonding reactivity with the filler preferably includes a functional group containing a nitrogen atom or a silicon atom.
More preferably, the ratio of the number of moles of nitrogen atoms (N) to the number of moles of silicon atoms (Si) in the modified conjugated diene polymer (A), that is, the molar ratio of N/Si is preferably 0.1 to 10.0, more preferably 0.2 to 7.0.
When N / Si is in the above range, the affinity with the silica-based filler is particularly good, the hysteresis loss of the rubber composition using the silica-based filler is small, and the rubber composition for fuel-efficient tires exhibits good performance.
Examples of functional groups containing silicon atoms include, but are not limited to, methoxysilyl groups, ethoxysilyl groups, propoxysilyl groups, and the like.
Moreover, the functional group containing a nitrogen atom is not limited to the following, but examples thereof include a secondary amino group and a tertiary amino group.
Moreover, the modified conjugated diene polymer (A) used in the present embodiment is preferably a modified conjugated diene polymer having a functional group containing a nitrogen atom in the polymer molecule. In such a case, as the functional group containing a nitrogen atom, it is particularly preferred that the nitrogen atom contains at least -NH- type secondary amine. In that case, a rubber composition using a silica-based filler and carbon black as fillers has a low hysteresis loss and exhibits good performance as a fuel-efficient tire composition.
When the modifier residue has a silicon atom, at least one of the silicon atoms preferably constitutes an alkoxysilyl group or silanol group having 1 to 20 carbon atoms. This tends to improve the dispersibility of the filler and improve the fuel economy.
In the modified conjugated diene-based polymer (A) used in this embodiment, a plurality of conjugated diene-based polymer chain terminals may be bonded to one silicon atom. Also, the end of the conjugated diene polymer chain and the alkoxy group or hydroxyl group may be bonded to one silicon atom, and as a result, the one silicon atom may constitute an alkoxysilyl group or a silanol group.

(Monomer constituting conjugated diene polymer)
The conjugated diene-based polymer before modification of the modified conjugated diene-based polymer (A) used in the present embodiment is obtained by polymerizing at least a conjugated diene compound, and optionally by copolymerizing both a conjugated diene compound and a vinyl-substituted aromatic compound.
The conjugated diene compound is not particularly limited as long as it is a polymerizable monomer, but a conjugated diene compound containing 4 to 12 carbon atoms per molecule is preferred, and a conjugated diene compound containing 4 to 8 carbon atoms is more preferred. Examples of such conjugated diene compounds include, but are not limited to, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. 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.
The vinyl-substituted aromatic compound is not particularly limited as long as it is a monomer copolymerizable with the conjugated diene compound, but a monovinyl aromatic compound is preferred. Examples of monovinyl aromatic compounds include, but are not limited to, styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. 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.

(preferred embodiment for SBR)
When the modified conjugated diene polymer (A) used in the present embodiment is a butadiene-styrene random copolymer (SBR), the bound styrene content is preferably 5% by mass to 50% by mass, and the vinyl bond content is preferably 10% to 75% by mass. Within this range, an SBR suitable for all uses other than tires can be industrially obtained.
In particular, when the bound styrene content is 25 mass % to 45 mass % and the vinyl bond content is 18 mol % to 30 mol %, a rubber composition with small hysteresis loss and excellent abrasion resistance can be obtained.
Further, when the bound styrene content is 18% by mass to 28% by mass and the vinyl bond content is 45% by mass to 65% by mass, a rubber composition for a fuel-saving tire having small hysteresis loss and excellent strength in a rubber composition blended with natural rubber can be obtained.
The amount of bound styrene is mass % of styrene in the total monomer components, and the amount of vinyl bonds is mol % of vinyl bond components in the butadiene component.

(Glass-transition temperature)
The glass transition temperature of the modified conjugated diene-based polymer (A) used in the present embodiment, that is, Tg, is the temperature at which the molecular chains of the modified conjugated diene-based polymer start rotational motion, and greatly affects fuel economy and wet grip performance.
When the Tg is low, the fuel efficiency is improved, and when the Tg is high, the wet grip is improved.
The modified conjugated diene polymer (A) used in the present embodiment preferably has a Tg of -20°C or higher and 0°C or lower. As a result, wet grip properties and rigidity become extremely good. This modified conjugated diene-based polymer is extremely useful for high-performance tires and ultra-high-performance tires.

Further, the modified conjugated diene-based polymer (A) used in the present embodiment has a Tg of -50°C or more and less than -20°C as another preferable form. As a result, the balance between fuel economy and wet grip is extremely excellent. This modified conjugated diene-based polymer is extremely useful for summer tires and all-season tires.

Further, the modified conjugated diene polymer (A) used in the present embodiment has a Tg of −70° C. or more and less than −50° C. as another preferable form. This results in very good low temperature performance and wear resistance.
This modified conjugated diene polymer is extremely useful for winter tires.
It is also used in various tire tread formulations to improve wear resistance.
The Tg of the modified conjugated diene polymer (A) can be controlled within the above desired range by adjusting the styrene content and/or the amount of 1,2-vinyl bonds. Specifically, the Tg can be increased by increasing the styrene content and the amount of 1,2-vinyl bonds.
The Tg of the modified conjugated diene polymer (A) can be measured according to ISO 22768:2006.

(Preferred form of random SBR)
When the modified conjugated diene-based polymer (A) used in the present embodiment is a butadiene-styrene random copolymer (SBR), it is preferable that the proportion of styrene units present alone is large, and that the number of long styrene chains is small.
Specifically, when the modified conjugated diene-based polymer (A) is a butadiene-styrene copolymer, the modified conjugated diene-based polymer (A) is decomposed by an ozonolysis method known as the method of Tanaka et al. (Polymer, 22, 1721 (1981)), and the styrene chain distribution is analyzed by GPC. The following are preferred. In this case, the resulting vulcanized rubber is a rubber composition for a fuel-saving tire with excellent performance, particularly small hysteresis loss.

(Hydrogenated conjugated diene polymer)
The modified conjugated diene-based polymer (A) used in the present embodiment may be obtained by further hydrogenating the modified conjugated diene-based polymer or the conjugated diene-based polymer before modification in an inert solvent. All or part of the double bonds can thereby be converted to saturated hydrocarbons. In such a case, the heat resistance and weather resistance are improved, the deterioration of the product when processed at high temperatures can be prevented, and the movement performance of the rubber tends to be improved. In addition, as a result, it exhibits even better performance in various applications such as automobile applications.
The degree of hydrogenation of the unsaturated double bond based on the conjugated diene compound can be arbitrarily selected according to the purpose and is not particularly limited. When used as a vulcanizate, it is preferred that the double bonds of the conjugated diene part remain partially. From this point of view, the hydrogenation rate of the conjugated diene portion in the conjugated diene polymer is preferably 3.0 mol% or more and 70 mol% or less, more preferably 5.0 mol% or more and 65 mol% or less, and even more preferably 10 mol% or more and 60 mol% or less. In particular, selective hydrogenation of vinyl groups tends to improve heat resistance and exercise performance. The hydrogenation rate can be determined by a nuclear magnetic resonance spectrometer (NMR).

(Oil-extended polymer, Mooney viscosity)
The modified conjugated diene-based polymer (A) used in this embodiment may be an oil-extended polymer added with an extender oil.
In addition, from the viewpoint of processability when forming a rubber vulcanizate and wear resistance when forming a vulcanizate, the modified conjugated diene polymer (A) used in the present embodiment preferably has a Mooney viscosity measured at 100° C. of 20 or more and 100 or less, more preferably 30 or more and 80 or less. The Mooney viscosity can be measured by the method described in Examples below.

(Nitrogen and silicon content)
The modified conjugated diene-based copolymer (A) used in the present embodiment contains nitrogen and silicon, and the contents of nitrogen and silicon are each preferably 3 mass ppm or more from the viewpoint of improving fuel efficiency, more preferably 7 mass ppm or more, and further preferably 10 mass ppm or more. Although the upper limits of the contents of nitrogen and silicon are not particularly limited, they are each 500 mass ppm or less, for example.
It is believed that the modified conjugated diene-based copolymer (A) used in the present embodiment is physically adsorbed by nitrogen during kneading with a filler and chemically bonded by silicon.
In the modified conjugated diene-based copolymer (A) used in the present embodiment, the molar ratio of nitrogen to silicon contained is important, and the molar ratio of nitrogen to silicon (N/Si) is preferably 1.1 or more and less than 10 from the viewpoint of dispersing silica in a short time during kneading, more preferably 1.3 or more and 7 or less, and further preferably 1.5 or more and 5 or less. The reason why the N / Si molar ratio is preferably in the above range is that the physical adsorption by nitrogen has a faster reaction rate than the chemical bond by silicon, so it is presumed that the molar ratio of nitrogen to silicon is equimolar or more.

Another preferred embodiment of the modified conjugated diene-based copolymer (A) used in the present embodiment has a molar ratio of nitrogen to silicon (N/Si) of 0.1 or more and less than 0.9. As a result, silica can be dispersed in a short time during kneading. In such a case, it is more preferably 0.2 or more and 0.75 or less, and further preferably 0.3 or more and 0.6 or less.
The reason why it is preferable that the molar ratio of nitrogen to silicon is 0.1 or more and less than 0.9 is not clear at this time, but it is presumed that the molar ratio of nitrogen to silicon is preferably less than equimolar because the physical adsorption by nitrogen is stronger than the chemical bond by silicon. In this case, the content of silicon is preferably 7 mass ppm or more.

In the modified conjugated diene copolymer (A) used in the present embodiment, the molar ratio of nitrogen to silicon can be controlled by the modifier used in the modification reaction of the conjugated diene copolymer.
For example, it is possible to increase the molar ratio of nitrogen to silicon in the modified conjugated diene-based copolymer by increasing the molar ratio of nitrogen to silicon in the modifier.
In the present embodiment, the contents of nitrogen and silicon, and the molar ratio of nitrogen to silicon can be measured by the methods described in Examples below.

(Preferred structure of modified conjugated diene polymer (A))
The structure of the modified conjugated diene-based polymer (A) used in the present embodiment is preferably a star structure in which a plurality of diene-based polymer chains are bonded around a modifier, from the viewpoint of workability. Due to the star structure, the viscosity is lowered even though the weight average molecular weight is the same as that of the straight chain structure, and the processability during kneading is good.
The modified conjugated diene-based polymer (A) used in this embodiment is preferably represented by the following general formula (I).

In formula (I), D ₁ represents a diene polymer chain, R ¹ to R ³ each independently represent a single bond or an alkylene group having 1 to 20 carbon atoms, R ⁴ and R ⁷ each independently represent an alkyl group having 1 to 20 carbon atoms, R ⁵ , R ⁸ and R ⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and R ⁶ and R ¹⁰ each independently It represents an alkylene group having 1 to 20 carbon atoms, and R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.
m and x represent an integer of 1 to 3, x≦m, p represents 1 or 2, y represents an integer of 1 to 3, y≦(p+1), and z represents an integer of 1 or 2.
D ₁ , R ¹ to R ¹¹ , m, p, x, y, and z when there are more than one are each independent.
i represents an integer of 0 to 6, j represents an integer of 0 to 6, k represents an integer of 0 to 6, (i + j + k) is an integer of 1 to 10, and ((x x i) + (y x j) + (z x k)) is an integer of 1 to 30.
A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom and a phosphorus atom and having no active hydrogen. However, when (i+j+k) is 1, A may be absent. As a result, the modified conjugated diene-based polymer tends to have a better balance between low hysteresis loss and wet skid resistance and wear resistance when vulcanized.

In the modified conjugated diene polymer (A) used in the present embodiment, A in the formula (I) preferably represents 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, a represents an integer of 1 to 10, and when multiple B ¹ are present, each is independent.

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, a represents an integer of 1 to 10, and B ² and B ³ are each 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, a represents an integer of 1 to 10, and when multiple B ⁴ are present, they are each independent.

In formula (V), B ⁵ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, a represents an integer of 1 to 10, and when multiple B ⁵ are present, each is independent. As a result, the vulcanizate tends to have a better balance between low hysteresis loss and wet skid resistance, and better wear resistance. In addition, it tends to be easily available for practical use.

[Method for producing modified conjugated diene polymer (A)]
The method for producing the modified conjugated diene-based polymer (A) used in the present embodiment preferably includes a polymerization step of polymerizing at least a conjugated diene compound using an organic monolithium compound as a polymerization initiator to obtain a conjugated diene-based polymer, and a modifying step of reacting the conjugated diene-based polymer with a modifier having a specific functional group having an affinity or binding reactivity with a filler and having a binding group that reacts with the active terminal of the conjugated diene-based polymer.

(Polymerization process)
In the method for producing the modified diene-based polymer (A) used in the present embodiment, preferably, in the polymerization step, at least a conjugated diene compound is polymerized using an organic monolithium compound as a polymerization initiator to obtain a conjugated diene-based polymer.
In the polymerization step, it is preferable to carry out polymerization by the growth reaction of the living anion polymerization reaction, whereby a conjugated diene-based polymer having an active terminal can be obtained, and a modified diene-based polymer with a high modification rate tends to be obtained in the modification step described later.

The modified conjugated diene-based polymer (A) preferably used in the present embodiment has a peak top in the GPC curve, or when there are a plurality of peak tops, a molecular weight component that is half the molecular weight of the peak top with the smallest molecular weight, that is, the modification rate of the low-molecular-weight component is 1/2 or more of the modification rate with respect to the total amount of the conjugated diene-based polymer.
In order to obtain such a modified conjugated diene polymer (A), it is effective to obtain a conjugated diene polymer by a polymerization method that causes very little termination of the growth reaction or chain transfer.
Therefore, the monomers and solvents to be introduced into the polymerization reactor must be made to a higher level than before.
Therefore, in the monomer component used, the total amount of impurities is preferably 30 ppm or less, and the content concentration (mass) of impurities such as allenes, acetylenes, primary and secondary amines is preferably 20 ppm or less for allenes, more preferably 10 ppm or less, preferably 20 ppm or less for acetylenes, more preferably 10 ppm or less, and the total nitrogen content of primary and secondary amines is preferably 4 ppm or less and 2 ppm or less. It is more preferable to have
Examples of allenes include, but are not limited to, propadiene and 1,2-butadiene. Examples of acetylenes include, but are not limited to, ethylacetylene and vinylacetylene. Examples of primary and secondary amines include, but are not limited to, methylamine and dimethylamine.

Ultra-high purification of monomers and solvents can be achieved by sufficiently purifying all monomers and solvents used in the polymerization.
In the purification of the monomer butadiene, it is important to remove not only polymerization inhibitors but also dimethylamine, N-methyl-γ-aminobutyric acid, etc., which may adversely affect anionic polymerization. Methods for removing these include, for example, washing 1,3-butadiene containing a polymerization inhibitor with low-oxygen water having an oxygen concentration of less than 2 mg/L as washing water, and then removing the polymerization inhibitor in 1,3-butadiene.
In the purification of styrene, which is a monomer, it is important to remove phenylacetylenes and the like, which may adversely affect anionic polymerization. As a method for removing phenylacetylenes, for example, a method of carrying out a hydrogenation reaction using a palladium-supported alumina catalyst can be mentioned.
In refining normal hexane, which is a polymerization solvent, it is important to remove water that may adversely affect anionic polymerization. The method for removing this is not particularly limited, but examples thereof include a method using γ-alumina, synthetic zeolite, and the like. Among these methods, the method using synthetic zeolite is preferred, and the synthetic zeolite preferably has a large pore size, more preferably 0.35 nm or more, and even more preferably 0.42 nm or more.
Since the ultra-high purification treatment required to obtain the desired impurity concentration varies depending on the state before treatment, it is preferable to measure the impurity concentration of the monomer and solvent after the ultra-high purification treatment of the monomer and solvent and prior to the polymerization reaction.
If the desired impurity levels of monomer and/or solvent were not obtained, then either treatment was considered insufficient. When it is desired to reduce the amount of primary and secondary amines, it is preferable to wash again with low-oxygen water having an oxygen concentration of less than 2 mg/L as washing water because the purification of butadiene is insufficient. When it is desired to reduce the amount of acetylenes, it is preferable, for example, to carry out the hydrogenation reaction again using a palladium-supported alumina catalyst because the purification of styrene is insufficient. At this time, it is more preferable to perform a treatment such as increasing the amount of the palladium-supported alumina catalyst or lengthening the contact time with the palladium-supported alumina catalyst.

As a polymerization method that causes very little termination of the growth reaction or chain transfer, it is effective to control the polymerization temperature and the monomer conversion rate.
From the viewpoint of terminating the growth reaction or suppressing chain transfer, the lower the polymerization temperature is, the more preferable it is. However, from the viewpoint of productivity, the polymerization temperature is preferably a temperature at which living anionic polymerization sufficiently proceeds, specifically, preferably 0° C. or higher, and preferably 80° C. or lower. More preferably, it is 50°C or higher and 75°C or lower. In addition, it is preferable to react the modifier with the conversion rate of the entire monomer of less than 99% by mass. By adding the modifier when the monomer remains in the polymerization vessel and allowing the growing polymer chain to react with the modifier before the monomer is completely consumed, it is possible to suppress the formation of a polymer whose end of polymerization is not modified and the occurrence of other side reactions. More preferably the conversion is less than 98% by mass.

The conjugated diene-based polymer may be a random copolymer or a block copolymer. In order to make the conjugated diene-based polymer into a rubber-like polymer, it is preferable to use 40% by mass or more, more preferably 55% by mass or more, of the conjugated diene compound with respect to the total monomers of the conjugated diene-based polymer.
Examples of random copolymers include, but are not limited to the following, random copolymers composed of two or more conjugated diene compounds such as butadiene-isoprene random copolymers, butadiene-styrene random copolymers, isoprene-styrene random copolymers, and random copolymers composed of conjugated dienes of butadiene-isoprene-styrene random copolymers and vinyl-substituted aromatic compounds.
The composition distribution of each monomer in the copolymer chain is not particularly limited, and includes, for example, a completely random copolymer close to a statistical random composition, and a tapered (gradient) random copolymer in which the composition is distributed in a tapered manner. The bonding mode of the conjugated diene, ie, the composition of 1,4-bonds, 1,2-bonds, etc. may be uniform or may be distributed.
Examples of block copolymers include, but are not limited to, type 2 block copolymers (diblock) consisting of two blocks, type 3 block copolymers (triblock) consisting of three blocks, and type 4 block copolymers (tetrablock) consisting of four blocks. A polymer constituting one block may be a polymer composed of one type of monomer or a copolymer composed of two or more types of monomers. For example, a polymer block composed of 1,3-butadiene is represented by "B", a copolymer of 1,3-butadiene and isoprene is represented by "B/I", a copolymer of 1,3-butadiene and styrene is represented by "B/S", and a polymer block composed of styrene is represented by "S". It is represented by a 3-type block copolymer, an SB-S 3-type block copolymer, an SB-S-B 4-type block copolymer, and the like.
In the above formula, the boundaries of each block do not necessarily need to be clearly distinguished. Further, when one polymer block is a copolymer composed of two types of monomers A and B, A and B in the block may be uniformly distributed or tapered.

<Polymerization initiator>
At least an organic monolithium compound is preferably used as the polymerization initiator.
Examples of organic monolithium compounds include, but are not limited to, low-molecular-weight compounds and solubilized oligomeric organic monolithium compounds. Further, the organic monolithium compound includes, for example, a compound having a carbon-lithium bond, a compound having a nitrogen-lithium bond, and a compound having a tin-lithium bond in terms of the bonding mode between the organic group and the lithium.
The amount of the organic monolithium compound used as a polymerization initiator can be appropriately determined according to the target molecular weight of the conjugated diene polymer or modified conjugated diene polymer. The amount of the monomer such as the conjugated diene compound used relative to the amount of the polymerization initiator used tends to relate to the degree of polymerization, that is, to the number average molecular weight and/or the weight average molecular weight. Therefore, in order to increase the molecular weight of the conjugated diene-based polymer, it is preferable to adjust in the direction of decreasing the polymerization initiator, and in order to decrease the molecular weight, it is preferable to adjust in the direction of increasing the amount of the polymerization initiator.
The organic monolithium compound is an alkyllithium compound or dialkylaminolithium having a substituted amino group. 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. Alkyllithium compounds having a substituted amino group having no active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium. Examples of the alkyllithium compound having a substituted 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 ethylbutylamide, lithium ethylbenzylamide, lithium methylphenethylamide, lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, 1-lithio-1,2,3,6-tetrahydropyridine.
These organomonolithium compounds having a substituted amino group can also be used as solubilized oligomeric organomonolithium compounds by reacting a small amount of monomers such as 1,3-butadiene, isoprene, and styrene.
The organomonolithium compound is preferably an alkyllithium compound. In this case, a conjugated diene polymer having an alkyl group at the polymerization initiation terminal is obtained.
Examples of alkyllithium compounds include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, 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 alone or in combination of two or more.

Moreover, the organomonolithium compound may be used in combination with another organometallic compound.
Examples of the organometallic compound include, but are not limited to, alkaline earth metal compounds, alkali metal compounds other than lithium, and other organometallic compounds.
Examples of alkaline earth metal compounds include, but are not limited to, organomagnesium compounds, organocalcium compounds, and organostrontium compounds. Also included are compounds of alkaline earth metal alkoxides, sulfonates, carbonates and amides. Examples of organomagnesium compounds include dibutylmagnesium and ethylbutylmagnesium. Other organometallic compounds include, for example, organoaluminum compounds.

The polymerization reaction mode in the polymerization step is not limited to the following, but examples thereof include a batch system (also referred to as a "batch system") and a continuous polymerization reaction system.
In continuous mode, one or more connected reactors can be used.
As the continuous reactor, for example, a vessel-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 into a reactor, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is continuously 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 to obtain a polymer-containing polymer solution in the reactor, and the polymer solution is discharged after completion of the polymerization.
In the production process of the modified conjugated diene-based polymer (A) used in the present embodiment, continuous polymerization is preferred from the viewpoint of stably producing the modified conjugated diene-based polymer containing the aforementioned specific polymer component.

In the polymerization step, it is preferred to carry out the polymerization in an inert solvent.
Examples of inert solvents include, but are not limited to, hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons.
Examples of hydrocarbon solvents include, but are not limited to the following: aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene, and hydrocarbons composed of mixtures thereof.
By treating allenes and acetylenes, which are impurities, with an organometallic compound before being subjected to a polymerization reaction, a conjugated diene polymer having a high concentration of active terminals tends to be obtained, and a modified conjugated diene polymer with a high modification rate tends to be obtained, which is preferable.

A polar compound may be added in the polymerization step. As a result, the aromatic vinyl compound and the conjugated diene compound can be randomly copolymerized, and the polar compound tends to be used as a vinylating agent for controlling the microstructure of the conjugated diene portion. In addition, it tends to be effective in promoting the polymerization reaction.
Examples of polar compounds include, but are not limited to the following, ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; potassium-tert-amylate; , potassium-tert-butylate, sodium-tert-butylate, sodium amylate and other alkali metal alkoxide compounds; and triphenylphosphine and other phosphine compounds.
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 (vinylating agent) can be used as a microstructure modifier of the conjugated diene portion of the polymer in an appropriate amount according to the desired amount of vinyl bonds.
Many polar compounds tend to have an effective randomization effect in the copolymerization of a conjugated diene compound and an aromatic vinyl compound at the same time, and can be used as an agent for adjusting the distribution of the aromatic vinyl compound and the amount of styrene blocks. As a method for randomizing the conjugated diene compound and the aromatic vinyl compound, for example, a method as described in JP-A-59-140211 may be used in which a copolymerization reaction is initiated with the total amount of styrene and a part of 1,3-butadiene, and the remaining 1,3-butadiene is intermittently added during the copolymerization reaction.

The conjugated diene-based polymer obtained in the polymerization step before the reaction step described later preferably has a Mooney viscosity measured at 110° C. of 10 or more and 90 or less, more preferably 15 or more and 85 or less, and even more preferably 20 or more and 60 or less.
When the Mooney viscosity is within the above range, the modified conjugated diene polymer (A) used in the present embodiment tends to be excellent in workability and wear resistance.

The amount of bonded conjugated diene in the modified conjugated diene-based polymer (A) used in the present embodiment is not particularly limited, but is preferably 40% by mass or more and 100% by mass or less, and more preferably 55% by mass or more and 80% by mass or less.
The amount of bonded aromatic vinyl in the modified conjugated diene polymer (A) used in the present embodiment is not particularly limited, but is preferably 0% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 45% by mass or less.
When the amount of bound conjugated diene and the amount of bound aromatic vinyl are within the above ranges, the resulting vulcanizate tends to have a better balance between low hysteresis loss and wet skid resistance, as well as fracture properties and abrasion resistance.
Here, the amount of bound aromatic vinyl can be measured by the 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 modified conjugated diene-based polymer (A) used in 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 more preferably 20 mol% or more and 65 mol% or less.
When the amount of vinyl bonds is within the above range, the resulting vulcanizate tends to have a better balance between low hysteresis loss and wet skid resistance, as well as better abrasion resistance and breaking strength. Here, when the branch-modified diene polymer is a copolymer of butadiene and styrene, the vinyl bond content (1,2-bond content) in the butadiene bond unit can be determined by Hampton's method (RR Hampton, Analytical Chemistry, 21, 923 (1949)). Specifically, it can be measured by the method described in Examples described later.

Regarding the microstructure of the modified conjugated diene-based polymer (A), when the amount of each bond in the modified conjugated diene-based polymer (A) used in the present embodiment is within the above-described numerical range, and the glass transition temperature of the modified conjugated diene-based polymer is in the range of −50° C. or more and less than −20° C., a more excellent vulcanizate tends to be obtained due to the balance between low hysteresis loss and wet skid resistance. 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. Specifically, it can be measured by the method described in Examples described later.

When the modified conjugated diene-based polymer (A) used in the present embodiment is a conjugated diene-aromatic vinyl copolymer, the number of blocks in which 30 or more aromatic vinyl units are linked is preferably small or absent. More specifically, when the copolymer is a butadiene-styrene copolymer, the copolymer is decomposed by Kolthoff's method (the method described in IM KOLTHOFF, et al., J. Polym. Sci. 1, 429 (1946)), and a known method of analyzing the amount of polystyrene insoluble in methanol is used. 0% by mass or less, more preferably 3.0% by mass or less.

(denaturation step)
In the modification step, the conjugated diene-based polymer obtained by the method described above is reacted with a modifying agent having a predetermined functional group having a bonding group that reacts with the active terminal of the conjugated diene-based polymer and having affinity or binding reactivity to the filler.
Moreover, it is preferable to carry out the modification step immediately after the polymerization step. In that case, a modified conjugated diene polymer with a high modification rate tends to be obtained.
When a compound having a monofunctional or difunctional bonding group is used as the modifying agent, a linear terminal-modified diene-based polymer is obtained, and when a polyfunctional compound having a trifunctional or higher bonding group is used, a branched modified diene-based polymer is obtained.
As the modifier, a monofunctional or polyfunctional compound containing at least one element selected from nitrogen, silicon, tin, phosphorus, oxygen, sulfur and halogen is preferably used. Moreover, an onium structure can be introduced into the modified conjugated diene-based polymer by adding a terminal modifying agent containing an onium forming agent and reacting it. Modifiers containing a plurality of functional groups containing these elements in the molecule or modifiers containing a plurality of functional groups containing these elements can also be used.
As modifiers, those having functional groups with little or no active hydrogen, such as hydroxyl groups, carboxyl groups, primary and secondary amino groups, are preferred. Active hydrogen tends to deactivate the active terminal of the conjugated diene polymer.

<Specific description of modifier>
Examples of nitrogen-containing compounds include, but are not limited to, isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, nitrogen group-containing carbonyl compounds, nitrogen group-containing vinyl compounds, and nitrogen group-containing epoxy compounds.
Examples of silicon-containing compounds include, but are not limited to, halogenated silicon compounds, epoxidized silicon compounds, vinylated silicon compounds, alkoxy silicon compounds, and alkoxy silicon compounds containing a nitrogen-containing group.
Examples of tin-containing compounds include, but are not limited to, halogenated tin compounds, organic tin carboxylate compounds, and the like.
Examples of phosphorus-containing compounds include, but are not limited to, phosphite ester compounds, phosphino compounds, and the like.
Examples of oxygen-containing compounds include, but are not limited to, epoxy compounds, ether compounds, ester compounds, and the like.
Examples of sulfur-containing compounds include, but are not limited to, mercapto group derivatives, thiocarbonyl compounds, isothiocyanates, and the like.
Examples of halogen-containing compounds include, but are not limited to, the aforementioned halogenated silicon compounds and halogenated tin compounds.
The onium-generating agent includes a protected amine compound capable of forming a primary or secondary amine (generating ammonium), a protected phosphine compound capable of forming hydrophosphine (generating phosphonium), a hydroxyl group, a compound capable of forming a thiol (generating oxonium and sulfonium), and the like. It is preferable to use a terminal modifier having a functional group in the molecule for bonding the onium-generating agent and the modified conjugated diene-based polymer. Examples of functional groups for bonding the modified conjugated diene-based polymer include carbonyl groups (ketones, esters, etc.), unsaturated groups such as vinyl groups, epoxy groups, halogenated silicon groups, alkoxy silicon groups, and the like.

The modifier preferably has a nitrogen-containing functional group, and the nitrogen-containing functional group is preferably an amine compound having no active hydrogen. Examples thereof include tertiary amine compounds, protected amine compounds obtained by substituting the active hydrogen with a protecting group, and imine compounds represented by the general formula -N=C.
Examples of the isocyanate compound of the nitrogen-containing compound that is the modifier include, but are not limited to, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, polymeric type diphenylmethane diisocyanate (C-MDI), phenyl isocyanate, isophorone diisocyanate, hexamethylene diisocyanate, butyl isocyanate, 1,3,5-benzene triisocyanate, and the like. mentioned.
Examples of isocyanuric acid derivatives 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 nitrogen group-containing carbonyl compounds include, but are not limited to, 1,3-dimethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 1-methyl-3-(2-methoxyethyl)-2-imidazolidinone, N-methyl-2-pyrrolidone, N-methyl-2-piperidone, N-methyl-2-quinolone, 4,4′-bis(diethylamino)benzophenone, 4 , 4′-bis(dimethylamino)benzophenone, methyl-2-pyridyl ketone, methyl-4-pyridyl ketone, propyl-2-pyridyl ketone, di-4-pyridyl ketone, 2-benzoylpyridine, N,N,N′,N′-tetramethylurea, N,N-dimethyl-N′,N′-diphenylurea, methyl N,N-diethylcarbamate, N,N-diethylacetamide, N,N-dimethyl-N′, N'-dimethylaminoacetamide, N,N-dimethylpicolinamide, N,N-dimethylisonicotinamide, N-(methoxycarbonylethyl)-N,N-bis(3-trimethoxysilylpropyl)amine, N-(ethoxycarbonylethyl)-N,N-bis(3-triethoxysilylpropyl)amine, N-(methoxycarbonylpropyl)-N,N-bis(3-trimethoxysilylpropyl)amine, N-(ethoxycarbonylpropyl)-N,N-bis(3- and triethoxysilylpropyl)amine.
Examples of the nitrogen group-containing vinyl compound 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'-vinyl denbis(N,N-diethylaniline), 1,1-bis(4-morpholinophenyl)ethylene, 1-phenyl-1-(4-N,N-dimethylaminophenyl)ethylene and the like.
Examples of the nitrogen group-containing epoxy compound include, but are not limited to, an epoxy group-containing hydrocarbon compound bonded to an amino group, which may further have an epoxy group bonded to an ether group. For example, it is represented by general formula (1).

In the above formula (1), R is a divalent or higher valent hydrocarbon group, or a divalent or higher organic group having at least one polar group selected from a polar group having oxygen such as ether, epoxy, ketone, etc., a polar group having sulfur such as thioether, thioketone, a tertiary amino group, and a polar group having nitrogen such as an imino group.
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. Examples include methylene, ethylene, butylene, cyclohexylene, 1,3-bis(methylene)-cyclohexane, 1,3-bis(ethylene)-cyclohexane, o-, m-, p-phenylene, m-, p-xylene and bis(phenylene)-methane.
In formula (1), 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.
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.
R ³ is a hydrocarbon group having 1 to 10 carbon atoms or a structure represented by the following formula (2).
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 (1), n is an integer of 1 or more, and m is 0 or an integer of 1 or more.

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

The nitrogen group-containing epoxy compound used as the modifier preferably has an epoxy group-containing hydrocarbon group, and more preferably has a glycidyl group-containing hydrocarbon group.
Examples of the epoxy group-containing hydrocarbon group bonded to an amino group or ether group include, but are not particularly limited to, a glycidylamino group, a diglycidylamino group and a glycididoxy group. 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 (3).

In formula (3), R is defined in the same manner as R in formula (1), and R ⁶ is a hydrocarbon group having 1 to 10 carbon atoms or a structure of formula (4) below.
When R ⁶ is a hydrocarbon group, it may be combined with R to form a cyclic structure, in which case N and R may be ^directly bonded to each other.
In formula (3), n is an integer of 1 or more, and m is 0 or an integer of 1 or more.

The nitrogen group-containing epoxy compound used as the modifier is most preferably a compound having one or more diglycidylamino groups and one or more glycidoxy groups in the molecule.
Nitrogen group-containing epoxy compounds used as modifiers include, but are not limited to the following, for example, N,N-diglycidyl-4-glycidoxyaniline, 1-N,N-diglycidylaminomethyl-4-glycidoxy-cyclohexane, 4-(4-glycidoxyphenyl)-(N,N-diglycidyl)aniline, 4-(4-glycidoxyphenoxy)-(N,N-diglycidyl)aniline, 4-(4-glycidyl)aniline. Sidoxybenzyl)-(N,N-diglycidyl)aniline, 4-(N,N'-diglycidyl-2-piperazinyl)-glycidoxybenzene, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylenediamine, 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-diglycidylaniline, 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 silicon halide compounds as modifiers include, but are not limited to, dibutyldichlorosilane, methyltrichlorosilane, dimethyldichlorosilane, methyldichlorosilane, trimethylchlorosilane, 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 silicon compound as a modifier include, but are not limited to, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, epoxy-modified silicone, and the like.

Alkoxy silicon compounds as modifiers include, but are not limited to, tetramethoxysilane, tetraethoxysilane, triphenoxymethylsilane, methoxy-substituted polyorganosiloxane, and the like.

Examples of alkoxy silicon compounds containing nitrogen-containing groups as modifiers 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-di methoxymethylsilylpropyl)-N-methylamine, bis(3-trimethoxysilylpropyl)-N-methylamine, bis(3-triethoxysilylpropyl)methylamine, tris(trimethoxysilyl)amine, tris(triethoxysilyl)amine, tris(3-trimethoxysilylpropyl)amine, N,N,N',N'-tetra(3-trimethoxysilylpropyl)ethylenediamine, 3-isocyanatopropyltrimethoxysilane, 3-cyanopropyltrimethoxysilane, 2 , 2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane,
2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-dimethoxy- 1-methyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-dimethoxy-8-(N,N-diethylamino)methyl-1,6-dioxa-2-silacyclooctane and the like.

As a protected amine compound capable of forming a primary or secondary amine which is a modifier, the compound having an unsaturated bond and a protected amine in the molecule is not limited to the following, but examples include 4,4'-vinylidenebis[N,N-bis(trimethylsilyl)aniline], 4,4'-vinylidenebis[N,N-bis(triethylsilyl)aniline], 4,4'-vinylidenebis[N,N-bis(t-butyldimethylsilyl) aryl)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'-vinylidene bis[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 ] and ethylene.

As a protected amine compound capable of forming a primary or secondary amine which is a modifier, the compound having an alkoxysilane and a protected amine in the molecule is not limited to the following, but examples include N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, N , N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane, N,N-bis(triethylsilyl)aminopropylmethyldiethoxysilane, 3-(4-trimethylsilyl-1-piperazino)propyltriethoxysilane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane, 3-(3-trimethylsilyl-1-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-dimethoxy methoxymethylsilylpropyl)-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 and the like.

Modifier tin halide compounds include, but are not limited to, tetrachlorotin, tetrabromtin, trichlorobutyltin, trichlorooctyltin, dibromodimethyltin, dichlorodibutyltin, chlorotributyltin, chlorotrioctyltin, chlorotriphenyltin, 1,2-bis(trichlorostanyl)ethane, 1,2-bis(methyldichlorostanyl)ethane, 1,4-bis(trichlorostanyl)butyltin, tane, 1,4 bis(methyldichlorostanyl)butane, and the like.

Examples of organotin carboxylate compounds as modifiers include, but are not limited to, ethyltin tristearate, butyltin trioctanoate, butyltin trisstearate, butyltin trilaurate, and dibutyltin bisoctanoate.

Examples of the phosphite ester compound as the modifier include, but are not limited to, trimethyl phosphite, tributyl phosphite, triphenoxide phosphite, and the like.

Examples of the phosphino compound as a modifier include, but are not limited to, protected phosphino compounds such as P,P-bis(trimethylsilyl)phosphinopropyltrimethoxysilane, P,P-bis(triethylsilyl)phosphinopropylmethylethoxysilane, 3-dimethylphosphinopropyltrimethoxysilane, 3-diphenylphosphinopropyltrimethoxysilane, and the like.

Examples of oxygen-containing compounds that are modifiers include, but are not limited to, polyglycidyl ethers such as ethylene glycol diglycidyl ether and glycerin triglycidyl ether; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, polyepoxidized liquid polybutadiene, epoxidized soybean oil and epoxidized linseed oil; and ester compounds such as dimethyl adipate, diethyl adipate, dimethyl terephthalate, and diethyl terephthalate. and these generate hydroxyl groups at the ends of the polymer.

Examples of sulfur-containing compounds that are modifiers include, but are not limited to, protected thiol compounds such as S-trimethylsilylthiopropyltrimethoxysilane, S-triethylsilylthiopropylmethyldiethylsilane, S-methylthiopropyltrimethoxysilane, S-ethylthiopropylmethyldiethoxysilane, ethyl N,N-diethyldithiocarbamate, phenylisothiocyanate, phenyl-1,4-diisothiocyanate, hexamethylenediisothiocyanate, butyl isothiocyanate, thiocyanate and the like.

The modifier preferably has a silicon-containing functional group, which preferably has an alkoxysilyl group or a silanol group.
The alkoxysilyl group of the modifier, for example, reacts with the active terminal of the conjugated diene polymer, dissociates alkoxylithium, and tends to form a bond between the terminal of the conjugated diene polymer chain and the silicon of the modifier residue. A value obtained by subtracting the number of SiORs reduced by the reaction from the total number of SiORs possessed by one modifier molecule is the number of alkoxysilyl groups possessed by the modifier residue. In addition, the azasilacycle group possessed by the modifier forms a >N—Li bond and a bond between the end of the conjugated diene polymer and the silicon of the modifier residue. The >N--Li bond tends to easily become >NH and LiOH with water or the like during finishing. Further, in the modifying agent, unreacted alkoxysilyl groups tend to easily become silanol (Si—OH groups) with water or the like during finishing.
If the modifier has a structure in which a nitrogen atom and a silicon atom are directly bonded, the following reaction tends to occur when the polymer after the modification reaction is brought into contact with water, so the polymer after solvent separation may not have the desired degree of branching. In that case, it is preferable to finish by a method that does not use water.
((RO)--Si--D ₂ ) ₃ --N+H ₂ O→3(RO)--Si(OH)--D ₂ )+NH ₃
(In the above formula, D ₂ represents a diene polymer and R represents a single bond or an alkyl group having 1 to 20 carbon atoms.)
In the modification step, when a modifier having three alkoxy groups per silicon atom is used, that is, when 3 mol of the active terminal of the conjugated diene-based polymer is reacted with 1 mol of the trialkoxysilane group, up to 2 mol of the conjugated diene-based polymer react with each other, but 1 mol of the alkoxy group tends to remain unreacted. This can be confirmed from the fact that 1 mol of the conjugated diene polymer remains as an unreacted polymer without reacting. By reacting many alkoxy groups, it tends to be possible to suppress a large change in polymer viscosity due to a condensation reaction during finishing and storage. Preferably, modifiers with one alkoxysilyl group per silicon atom are used.

The reaction temperature in the modification step is preferably the same temperature as the polymerization temperature of the conjugated diene-based polymer, and particularly preferably the temperature without heating after the polymerization. It is more preferably 0° C. or higher and 120° C. or lower, and still more preferably 50° C. or higher and 100° C. or lower.
The reaction time in the modification step is preferably 10 seconds or longer, more preferably 30 seconds or longer.
Any mixing method such as mechanical stirring or stirring using a static mixer may be applied to the mixing in the modification step. When the polymerization step is continuous, the modification step is also preferably continuous. The reactor used in the modification step is, for example, a vessel-type vessel equipped with a stirrer or a tubular type. The modifier may be diluted with an inert solvent and fed continuously to the reactor. When the polymerization process is a batch system, the modifier may be charged into the polymerization reactor or may be transferred to another reactor for the reaction process.

A compound represented by the following general formula (VI) is preferable as the modifier.

In formula (VI), R ¹² to R ¹⁴ each independently represent a single bond or an alkylene group having 1 to 20 carbon atoms, R ¹⁵ to R ¹⁸ and R ²⁰ each independently represent an alkyl group having 1 to 20 carbon atoms, R ¹⁹ and R ²² each independently represent an alkylene group having 1 to 20 carbon atoms, and R ²¹ represents an alkyl group 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 are each independent when a plurality of R 12 to R 22 are present.
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 1-10.
A is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom and a phosphorus atom and having no active hydrogen.
The hydrocarbon group represented by A includes saturated, unsaturated, aliphatic and aromatic hydrocarbon groups. The organic group having no active hydrogen is an organic group that deactivates the active terminal of the conjugated diene polymer. The organic group is an organic group that does not have a functional group having an active hydrogen such as a hydroxyl group (--OH), a secondary amino group (>NH), a primary amino group (--NH ₂ ), or a sulfhydryl group (--SH). Note that when (i+j+k) is 1, A may be absent.
In the above formula (VI), A preferably represents 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, a represents an integer of 1 to 10, and when multiple B ¹ are present, each is independent.

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, a represents an integer of 1 to 10, and B ² and B ³ are each 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, a represents an integer of 1 to 10, and when multiple B ⁴ are present, they are each independent.

In formula (V), B ⁵ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, a represents an integer of 1 to 10, and when multiple B ⁵ are present, they are each independent.

In the formula (VI), when A represents any one of the following general formulas (II) to (V), it tends to be possible to obtain a modified conjugated diene-based polymer with better performance.

As modifiers of formula (VI), those having (i+j+k) of 1 to 2 include those overlapping with the modifiers described above and are not limited to the following, for example, 3-dimethoxymethylsilylpropyldimethylamine (monofunctional), 3-trimethoxysilylpropyldimethylamine (bifunctional), bis(3-trimethoxysilylpropyl)methylamine (tetrafunctional), bis(3-dimethoxymethylsilylpropyl)methylamine (bifunctional), (3-trimethoxysilylpropyl)- [3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]ethylamine (tetrafunctional), [3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)methylamine (tetrafunctional), bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]methylamine (tetrafunctional), bis(3-triethoxysilylpropyl)ethyl Amine (tetrafunctional), 1-(3-triethoxysilylpropyl)-2,2-diethoxy-1-aza-2-silacyclopentane (tetrafunctional), 1-(3-dimethoxymethylsilylpropyl)-2,2-dimethoxy-1-aza-2-silacyclopentane (trifunctional), [3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-diethoxyethylsilylpropyl) ) methylamine (trifunctional), bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]methylamine (tetrafunctional), (3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-methylamine (trifunctional).

Hereinafter, as the polyfunctional compound, (i+j+k) is 3 or more, and the modifier when A is represented by the formula (II) in the formula (VI) is not limited to the following, for example, tris(trimethoxysilyl)amine, tris(triethoxysilyl)amine, 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-sila Cyclopentane)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 amine, 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-trimethoxysilylpropyl)-[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-triethoxysilylpropyl)-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, tris[3-(2,2-diethoxy-1-a the-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 amine, 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, tri Su[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-azacyclo pentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)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-azacyclopentane)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-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1, 3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexamethylenediamine, pentakis(3-trimethoxysilylpropyl)-diethylenetriamine.

In the above formula (VI), when A is represented by the above formula (III), the modifier is not limited to the following; the-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-die Toxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-methyl-1,3-propanediamine, N¹, N^1'-(propane-1,3-diyl)bis(N¹-methyl-N³, N³-bis(3-(trimethoxysilyl)propyl)-1,3-propanediamine), N¹-(3-(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N¹-methyl-N³-(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N³-(3-(Trimethoxysilyl)propyl)-1,3-propanediamine.

In the above formula (VI), when A is represented by formula (IV), the modifier is not limited to the following, but examples include 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, bis(3-trimethoxy silylpropyl)-bis[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]silane.

In the above formula (VI), when A is represented by the above formula (V), the modifier is not limited to the following; tan)ethoxy]silyl-1-trimethoxysilylpropane.

In the above formula (VI), when A represents an organic group having an oxygen atom and no active hydrogen, the modifier is not limited to the following, for example, (3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]ether (tetrafunctional), 3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexyl-[3-(2,2-dimethoxy-1 -Aza-2-silacyclopentane)propyl]ether (octafunctional).

In the above formula (VI), when A represents an organic group having a phosphorus atom and no active hydrogen, the modifier is not limited to the following, but for example, (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, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl] phosphate.

In the formula (VI), A preferably represents the formula (II) or the formula (III), and k represents 0. As a result, the modified conjugated diene polymer tends to be an easily available modifier, and when the modified conjugated diene polymer is vulcanized, it tends to be more excellent in wear resistance and low hysteresis loss performance. Examples of such modifiers include, but are not limited to, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]. -1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, bis[3-(2,2- Dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trismethoxysilylpropyl)-methyl-1,3-propanediamine.

In formula (VI), A more preferably represents formula (II) or formula (III), k represents 0, and a represents an integer of 2-10 in formula (II) or formula (III). The use of such modifiers tends to result in better wear resistance and low hysteresis loss performance when vulcanized.
このような変性剤としては、以下のものに限定されないが、例えば、テトラキス［３－（２，２－ジメトキシ－１－アザ－２－シラシクロペンタン）プロピル］－１，３－プロパンジアミン、テトラキス（３－トリメトキシシリルプロピル）－１，３－プロパンジアミン、テトラキス（３－トリメトキシシリルプロピル）－１，３－ビスアミノメチルシクロヘキサン、Ｎ ¹ －（３－（ビス（３－（トリメトキシシリル）プロピル）アミノ）プロピル）－Ｎ ¹ －メチル－Ｎ ³ －（３－（メチル（３－（トリメトキシシリル）プロピル）アミノ）プロピル）－Ｎ ³ －（３－（トリメトキシシリル）プロピル）－１，３－プロパンジアミンが挙げられる。

The amount of the compound represented by formula (VI) added as a modifier can be adjusted so that the number of moles of polymerization initiator to the number of moles of modifier are reacted in the desired stoichiometric ratio, thereby achieving the desired degree of branching. Specifically, the number of moles of the polymerization initiator is preferably 1.0 times or more, more preferably 2.0 times or more, with respect to the number of moles of the modifier. In this case, in formula (VI), the functional group number ((m−1)×i+p×j+k) of the modifier is preferably an integer of 1 to 10, more preferably an integer of 2 to 10.

(Hydrogenation process)
The modified conjugated diene-based polymer (A) used in the present embodiment may be obtained by hydrogenating the conjugated diene portion. A method for hydrogenating the conjugated diene portion is not particularly limited, and a known method 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 examples thereof include heterogeneous catalysts such as catalysts in which noble metals are supported on porous inorganic substances; catalysts in which salts such as nickel and cobalt are solubilized and reacted with organic aluminum and the like; and homogeneous catalysts such as catalysts using metallocenes such as titanocene. 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 the following: (1) supported heterogeneous hydrogenation catalysts in which metals such as Ni, Pt, Pd, and Ru are supported on carbon, silica, alumina, diatomaceous earth, etc.; (2) so-called Ziegler-type hydrogenation catalysts using organic acid salts such as Ni, Co, Fe, and Cr or transition metal salts such as acetylacetone salts and reducing agents such as organic aluminum; and (3) organometallic compounds such as Ti, Ru, Rh, and Zr. So-called organometallic complexes and the like are included. Furthermore, the hydrogenation catalyst is not particularly limited, but for example, JP-B-42-8704, JP-B-43-6636, JP-B-63-4841, JP-B-1-37970, JP-B-1-53851, JP-B-2-9041, and JP-A-8-109219 also include known hydrogenation catalysts. Preferred hydrogenation catalysts include reaction mixtures of titanocene compounds and reducing organometallic compounds.

In the production process of the modified conjugated diene polymer (A) used in the present embodiment, after the modification process, a deactivator, a neutralizer, etc. may be added to the modified conjugated diene 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 having 9 to 11 carbon atoms, mainly 10 carbon atoms); an aqueous solution of an inorganic acid, and carbon dioxide gas.

A rubber stabilizer is preferably added to the modified conjugated diene polymer (A) used in the present embodiment from the viewpoint of preventing gel formation after polymerization and improving the stability during processing.
As the rubber stabilizer, a known one can be used, and it is not limited to the following. Examples include antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (BHT), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol) propinate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol.

In order to further improve the processability of the modified conjugated diene-based polymer (A) used in this embodiment, an extender oil can be added to the modified conjugated diene-based copolymer, if necessary.
The method of adding the extender oil to the modified conjugated diene polymer is not limited to the following method, but the method of adding the extender oil to the polymer solution and mixing to obtain an oil-extended copolymer solution and desolvating the solution is preferable.
Examples of extender oils include aromatic oils, naphthenic oils, paraffin 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 Extract). tracts).
The amount of the extender oil to be added is not particularly limited, but is preferably 10 parts by mass or more and 60 parts by mass or less, more preferably 20 parts by mass or more and 37.5 parts by mass or less with respect to 100 parts by mass of the modified conjugated diene polymer.

A known method can be used as a method for obtaining the modified conjugated diene polymer (A) used in the present embodiment from a polymer solution. The method is not particularly limited, but examples thereof include a method of separating the solvent by steam stripping or the like, followed by filtering the polymer, followed by dehydration and drying to obtain a polymer, a method of concentrating in a flushing tank and further devolatilizing with a vent extruder or the like, and a method of directly devolatilizing with a drum dryer or the like.
However, when a modifying agent in which silicon is directly bonded to a nitrogen atom is used, the following reaction with water tends to occur easily, so a method that does not use water is preferred.
((RO)--Si--D ₂ ) ₃ --N+H ₂ O→3(RO)--Si(OH)--D ₂ )+NH ₃
Methods that do not use water include, but are not particularly limited to, a method of concentrating in a flushing tank and further devolatilizing with a vent extruder or the like, and a method of directly devolatilizing with a drum dryer or the like.
(In the above formula, D ₂ represents a diene polymer and R represents a single bond or an alkyl group having 1 to 20 carbon atoms.)

[Modified conjugated diene polymer (B)]
The modified conjugated diene-based polymer (B) used in the present embodiment has two or more peak tops in the gel permeation chromatography (GPC) curve, the molecular weight distribution Mw/Mn of the peak with the lowest molecular weight is 1.0 or more and less than 1.6, the peak area is 2 to 50% of the total peak area, and the modification rate relative to the total amount of the conjugated diene-based polymer is 50% by mass or more.

The modified conjugated diene-based polymer (B) used in the present embodiment preferably has the same characteristics as the modified conjugated diene-based polymer (A) within the range that satisfies the above conditions, so the points different from the modified conjugated diene-based polymer (A) will be described below.

(peak molecular weight)
The modified conjugated diene-based polymer (B) used in this embodiment has two or more peak tops in the GPC curve. When there is one peak top, the strength of the rubber composition tends to decrease. On the other hand, when it has two or more peak tops, it is possible to provide a rubber composition having excellent balance between wear resistance and workability and low hysteresis loss. Moreover, having two or more peak tops tends to increase the weight average molecular weight of the modified conjugated diene copolymer, and tends to maintain the strength of the rubber composition. Although the upper limit of the number of peak tops is not particularly limited, it is, for example, five or less.
The number of peak tops of the modified conjugated diene-based polymer (B) used in the present embodiment can be controlled by the type of modifier, the amount of modifier, the number of modifiers to be added, the timing of addition of the modifier, or by mixing modified conjugated diene-based polymers with different peak molecular weights.

(Weight average molecular weight)
The weight average molecular weight of the modified conjugated diene polymer (B) used in the present embodiment is preferably 2×10 ⁴ or more and 200×10 ⁴ or less, more preferably 4×10 ⁴ or more and 150×10 ⁴ or less, and even more preferably 6×10 ⁴ or more and 120×10 ⁴ or less, from the viewpoint of the balance between low hysteresis performance and processability.
When the modified conjugated diene-based polymer (B) has a weight average molecular weight of 2×10 ⁴ or more and 200×10 ⁴ or less, the vulcanizate has excellent low hysteresis loss properties. Further, when the weight average molecular weight of the modified conjugated diene polymer (B) is 200×10 ⁴ or less, the dispersibility of the filler in the vulcanizate is excellent.

(Molecular weight distribution)
The modified conjugated diene-based polymer (B) used in the present embodiment has a molecular weight distribution Mw/Mn, which is represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the lowest molecular weight peak, of 1.0 or more and less than 1.6. The modified conjugated diene-based polymer (B) having a molecular weight distribution within this range tends to be superior in low hysteresis loss when vulcanized as compared with a polymer having a similar molecular weight and modification rate. The molecular weight distribution Mw/Mn of the peak with the lowest molecular weight of the modified conjugated diene polymer (B) is preferably 1.0 or more and 1.4 or less, more preferably 1.0 or more and 1.2 or less.
A modified conjugated diene-based polymer (B) having such a molecular weight distribution can preferably be obtained by batch polymerization.
The molecular weight distribution of the modified conjugated diene-based polymer (B) is preferably such that the molecular weight curve by GPC has a mountain range shape with multiple peaks, and the molecular weight distribution Mw/Mn of each peak is 1.0 or more and less than 1.6.
The modified conjugated diene polymer (B) having such a molecular weight distribution tends to be excellent in low hysteresis loss when vulcanized.

(peak area)
The area of the peak having the smallest molecular weight of the modified conjugated diene polymer (B) used in this embodiment is 2 to 50% of the total peak area. The smaller the area of the peak with the smallest molecular weight of the modified conjugated diene polymer (B), the better the abrasion resistance, while the larger the area of the peak with the smallest molecular weight of the modified conjugated diene polymer (B), the better the workability. From the viewpoint of the balance between abrasion resistance and workability, the area of the peak with the smallest molecular weight of the modified conjugated diene polymer (B) is more preferably 2 to 40%, more preferably 2 to 30% of the total peak area. Further, when the modified conjugated diene-based polymer (B) has the smallest molecular weight peak area within the above range, the rubber-like polymer has an excellent balance between abrasion resistance and workability.
The peak area can be controlled by the type of modifier, the amount of modifier, the number of modifiers to be added, the timing of addition of the modifier, or the amount of mixed modified conjugated diene polymers with different peak molecular weights.

The area of peaks excluding the peak having the lowest molecular weight of the modified conjugated diene polymer (B) used in this embodiment is 50 to 98% of the total peak area. By having a plurality of peak tops, the weight average molecular weight of the modified conjugated diene copolymer (B) tends to increase, and the area of the peaks excluding the peak with the lowest molecular weight of the modified conjugated diene polymer (B) is 50% or more of the total peak area, resulting in excellent abrasion resistance. On the other hand, as described above, as the peak area increases, the workability tends to deteriorate, and from the balance between wear resistance and workability, the peak area is more preferably 60 to 98% of the total peak area. More preferably, 70 to 98%.
As described above, this peak area can be controlled by the type of modifier, the amount of modifier, the number of modifiers to be added, the timing of addition of the modifier, or the amount of modified conjugated diene-based polymers with different peak molecular weights mixed.

The modified conjugated diene-based polymer (B) is preferably represented by the general formula (I). As a result, the modified conjugated diene-based polymer tends to have a better balance between low hysteresis loss and wet skid resistance and wear resistance when vulcanized.
The mixing method when the modified conjugated diene-based polymerizations (A) and (B) used in the present embodiment are mixed in advance is not particularly limited, but various methods such as a method of mixing solutions of the respective modified conjugated diene-based polymers and a method of mechanically mixing the respective modified conjugated diene-based polymers can be mentioned.

[Rubber-like polymer]
The rubber-like polymer used in the present embodiment is a rubber-like polymer containing at least two types of modified conjugated diene-based polymers (A) and (B) and containing 30% by mass or more of the modified conjugated diene-based polymer (A). In the rubber-like polymer, the modified conjugated diene polymer (A) is more preferably contained in an amount of 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, from the viewpoint of abrasion resistance. In the rubber-like polymer, the upper limit of the content of the modified conjugated diene polymer (A) is preferably 90% by mass or less. When the rubber-like polymer contains the modified conjugated diene-based polymer (B) in an amount of preferably 10% by mass or more, the low hysteresis property is improved. More preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more. In the rubber-like polymer, the upper limit of the content of the modified conjugated diene polymer (B) is preferably 70% by mass or less.
Since the modification rate having affinity or binding reactivity with the filler is 50% by mass or more, even when the modified conjugated diene polymer (A) and the filler are kneaded, it is possible to provide a rubber composition excellent in low hysteresis loss while maintaining workability.

Further, the rubber-like polymer may contain a polymer other than the modified conjugated diene-based polymers (A) and (B). Polymers other than the modified conjugated diene-based polymers (A) and (B) used in the present embodiment are not limited to the following, but include, for example, a conjugated diene-based polymer or a hydrogenated product thereof, a random copolymer of a conjugated diene-based compound and a vinyl aromatic compound or a hydrogenated product thereof, a block copolymer of a conjugated diene-based compound and a vinyl aromatic compound or a hydrogenated product thereof, a non-diene-based polymer, and a natural rubber. Specific polymers include, but are not limited to the following, butadiene rubber or hydrogenated products thereof, isoprene rubber or hydrogenated products thereof, styrene-butadiene rubber or hydrogenated products thereof, styrene-butadiene block copolymers or hydrogenated products thereof, styrene elastomers such as styrene-isoprene block copolymers or hydrogenated products thereof, acrylonitrile-butadiene rubbers or hydrogenated products thereof.
Examples of the non-diene polymer include, but are not limited to the following, olefin elastomers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, ethylene-octene rubber, butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylic acid ester-conjugated diene copolymer rubber, urethane rubber. , and polysulfide rubbers. The mixing method when a polymer other than the modified conjugated diene-based polymers (A) and (B) used in the present embodiment (referred to as another polymer) is mixed and used is not particularly limited. Examples include a method of mixing a solution of the modified conjugated diene-based polymers (A) and (B) with a solution of another polymer, a method of mechanically mixing the modified conjugated diene-based polymers (A) and (B) and the other polymer, and the like.
The other polymer mentioned above may be a modified rubber to which a polar functional group such as a hydroxyl group or an amino group is added. When used for tires, butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber and butyl rubber are preferably used.
Examples of the natural rubber include, but are not limited to, smoked sheet RSS Nos. 3 to 5, SMR, and epoxidized natural rubber.

[Rubber composition]
The rubber composition of the present embodiment contains the modified conjugated diene polymers (A) and (B), and 100 parts by mass of a rubber-like polymer containing 30% by mass or more of the modified conjugated diene polymer (A), and 5 to 150 parts by mass of a filler.
As described above, when kneading the modified conjugated diene-based polymer (A) and the filler, the higher the modification rate of the modified conjugated diene-based polymer (A), the higher the maximum torque reaches, and the higher the "1/2 modification rate", the faster the torque rise time. This is the same result even when a rubber composition containing a plurality of modified conjugated diene polymers (A) within the scope of the present embodiment is used. Focusing on the torque rise time, the higher the "1/2 modification rate", the faster the torque rise time.
On the other hand, since the modified conjugated diene-based polymer (B) has a molecular weight distribution Mw/Mn of less than 1.6 and a plurality of peak tops, it is difficult to ensure that the modification rate of the component having a molecular weight of 1/2 of the peak top with the smallest molecular weight is 1/2 or more of the modification rate with respect to the total amount of the modified conjugated diene-based polymer (B) unless, for example, an organic lithium compound having at least one functional group such as a nitrogen atom in the molecule is used as a polymerization initiator.
However, the rubber composition containing the modified conjugated diene-based polymers (A) and (B) having physical properties within the predetermined range of the present embodiment tends to have a relatively high torque increase rate. The mechanism is considered as follows.
The reaction between the filler such as silica and the modifying groups in the modified conjugated diene-based polymer progresses sequentially from the modified conjugated diene-based polymer with the smaller molecular weight during the kneading process. Therefore, even if the "1/2 modification rate" is not high, the modified conjugated diene-based polymer (B), which has a relatively narrow molecular weight distribution, will quickly complete the reaction once the reaction occurs.
Since the rubber composition of the present embodiment is easy to knead, the filler tends to be dispersed well, and since it contains a modified conjugated diene polymer (B) having a relatively narrow molecular weight distribution, it tends to be an excellent rubber composition with low hysteresis loss.
Furthermore, the modified conjugated diene-based polymer (B) has a peak area excluding the peak with the lowest molecular weight of 50 to 98% of the total peak area, that is, it contains a large amount of high-molecular components, so the rubber composition also maintains abrasion resistance.
The rubber composition of this embodiment is suitably used as a vulcanizate. Examples of the vulcanizate include, but are not limited to, tires, hoses, shoe soles, anti-vibration rubbers, automobile parts, anti-vibration rubbers, and resin-reinforced rubbers such as impact-resistant polystyrene and ABS resins. In particular, it is suitably used in tread rubber compositions for tires. The vulcanizate can be obtained, for example, by kneading the rubber-like polymer used in the present embodiment with a silica-based inorganic filler, an inorganic filler such as carbon black, a polymer other than the modified conjugated diene-based polymers (A) and (B) used in the present embodiment, a silane coupling agent, a rubber softener, a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, and the like to form a rubber composition containing the modified conjugated diene-based polymers (A) and (B), followed by vulcanization by heating.
Moreover, the filler preferably contains a silica-based inorganic filler. By dispersing the silica-based inorganic filler, the rubber composition tends to be more excellent in processability when vulcanized, and when vulcanized, the balance between low hysteresis loss and wet skid resistance, breaking strength, and abrasion resistance tend to be excellent. Also when the rubber composition of the present embodiment 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.
Examples of fillers include, but are not limited to, silica-based inorganic fillers, carbon black, metal oxides, and metal hydroxides. Among these, silica-based inorganic fillers are preferred. These may be used individually by 1 type, and may use 2 or more types together.
The content of the filler in the rubber composition of the present embodiment is 5 parts by mass or more and 150 parts by mass or less, preferably 10 parts by mass or more and 120 parts by mass or less, and more preferably 20 parts by mass or more and 100 parts by mass or less, relative to 100 parts by mass of the rubber-like polymer.
The content of the filler is 5 parts by mass or more with respect to 100 parts by mass of the rubber-like polymer from the viewpoint of expressing the effect of adding the filler, and is 150 parts by mass or less from the viewpoint of sufficiently dispersing the filler and making the processability and mechanical strength of the rubber composition practically sufficient.
The silica-based inorganic filler is not particularly limited, and known ones can be used, but solid particles containing SiO ₂ or Si ₃ Al as a structural unit are preferable, and solid particles containing SiO ₂ or Si ₃ Al as a main component of the structural unit are more preferable. 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 specific 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 an excellent balance between the effect of improving fracture properties and wet skid resistance.
From the viewpoint of obtaining practically good wear resistance and fracture characteristics of the rubber composition, the nitrogen adsorption specific surface area of the silica-based inorganic filler determined by the BET adsorption method is preferably 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. If necessary, a silica-based inorganic filler having a relatively small specific surface area (for example, a specific surface area of 200 m ² /g or less) and a silica-based inorganic filler having a relatively large specific surface area (for example, 200 m ² /g or more) can be used in combination. In the present embodiment, especially when using a silica-based inorganic filler having a relatively large specific surface area (e.g., 200 m ² /g or more), the modified conjugated diene-based polymer improves the dispersibility of silica, is particularly effective in improving wear resistance, and tends to be able to achieve a high balance between good fracture characteristics and low hysteresis loss.
The content of the silica-based inorganic filler in the rubber composition of the present embodiment is 5 parts by mass or more and 150 parts by mass, and preferably 20 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the rubber-like polymer. The content of the silica-based inorganic filler is 5 parts by mass or more with respect to 100 parts by mass of the rubber-like polymer from the viewpoint of expressing the effect of adding the inorganic filler, and is 150 parts by mass or less from the viewpoint of sufficiently dispersing the inorganic filler and making the processability and mechanical strength of the composition practically sufficient.
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 is preferably 0.5 parts by mass or more and 100 parts by mass or less, more preferably 3.0 parts by mass or more and 100 parts by mass or less, and even more preferably 5.0 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the rubber-like polymer. The content of carbon black is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the rubber-like polymer from the viewpoint of expressing the performance required for tire applications such as dry grip performance and conductivity. From the viewpoint of dispersibility, it is preferably 100 parts by mass or less.
A metal oxide is a solid particle having a structural unit 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 the present embodiment may contain a silane coupling agent. The silane coupling agent has the function of making the interaction between the rubber-like polymer and the inorganic filler closer, and has groups with affinity or bonding to the rubber-like polymer and the silica-based inorganic filler, respectively. A compound having a sulfur-bonding portion and an alkoxysilyl group or a silanol group portion in one molecule is preferred. Examples of such compounds include, but are not limited to, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide.
The content of the silane coupling agent is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, and 1.0 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the inorganic filler described above. 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. 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, which are used to soften, increase the volume, and improve processability of rubber, are mixtures of aromatic rings, naphthenic rings, and paraffin chains. Those with a paraffin chain carbon number of 50% by mass or more are called paraffinic. are called aromatic systems. When the conjugated diene-based polymer used in the present embodiment is a copolymer of a conjugated diene compound and a vinyl aromatic compound, the rubber softener to be used has an appropriate aromatic content and tends to be compatible with the copolymer, so it is preferable.
The content of the softener for rubber is preferably 0 to 100 parts by mass, more preferably 10 to 90 parts by mass, and even more preferably 30 to 90 parts by mass with respect to 100 parts by mass of the rubber-like polymer. When the content of the softening agent for rubber is 100 parts by mass or less with respect to 100 parts by mass of the rubber-like polymer, bleeding out is suppressed and stickiness of the surface of the rubber composition tends to be suppressed.
The method of mixing the modified conjugated diene-based polymer with other rubber-like polymers, silica-based inorganic fillers, carbon black and other fillers, silane coupling agents, and additives such as rubber softeners is not limited to the following. Among these, melt-kneading methods using rolls, Banbury mixers, kneaders, and extruders are preferred from the viewpoint of productivity and good kneading properties. Also, a method of kneading the rubber-like polymer and other fillers, a silane coupling agent, and additives at once or a method of mixing them in multiple batches can be applied.
The rubber composition of the present embodiment may be a vulcanized composition that is 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. The content of the vulcanizing agent 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-like polymer. 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 examples thereof include, but are not limited to, sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators. 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, relative to 100 parts by mass of the rubber-like polymer.
In the rubber composition of the present embodiment, various additives such as softeners and fillers other than those described above, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants may be used within a range that does not impair the purpose of the present embodiment. As other softening agents, known softening agents can be used. Specific examples of other fillers include, but are not limited to, calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. As the heat stabilizer, antistatic agent, weather stabilizer, anti-aging agent, colorant, and lubricant, known materials can be used.

[Method for producing rubber composition]
The method for producing the rubber composition of the present embodiment is not particularly limited. Examples thereof include a method of melt-kneading the rubber-like polymer described above, a filler, and optionally a vulcanizing agent and a vulcanization accelerator, and the various materials described above using a general kneader such as an open roll, Banbury mixer, kneader, single-screw extruder, twin-screw extruder, multi-screw extruder, etc., and a method of dissolving and mixing each component and then removing the solvent by heating.
Among these, melt-kneading methods using rolls, Banbury mixers, kneaders, and extruders are preferred from the viewpoint of productivity and good kneading properties.
The above-mentioned rubber-like polymer may be mixed in advance and used, and the mixing method is not particularly limited. Examples include a method of mixing solutions of the respective modified conjugated diene-based polymers, a method of mechanically mixing the respective modified conjugated diene-based polymers, and the like.
In addition, both a method of kneading the rubber-like polymer, the filler, and various compounding agents at once, and a method of mixing them a plurality of times are applicable.

〔tire〕
The rubber composition of the present embodiment is suitably used as a rubber composition for tires.
The rubber composition for tires of the present embodiment is not limited to the following, but for example, various tires such as fuel-saving tires, all-season tires, high-performance tires, and studless tires: tread, carcass, sidewall, bead, etc. It is possible to use it for each part of the tire. In particular, the rubber composition for tires of the present embodiment has excellent balance between low hysteresis loss and wet skid resistance and wear resistance when vulcanized, so it is more suitable for treads of fuel-saving tires and high-performance tires.

EXAMPLES Hereinafter, the present embodiment will be described in detail with specific examples and comparative examples, but the present embodiment is not limited to the following examples and comparative examples.
Raw materials purified by the methods shown below were used as raw materials for modified conjugated diene-based polymers, and various physical properties were measured by the methods shown below.

<Purification of 1,3-butadiene>
1,3-butadiene used for polymerization of the modified conjugated diene polymer was purified by the following steps.
(Water washing process)
It was operated under conditions of a circulating water amount of 1 m ³ /hour and a renewal (makeup) water amount of 0.1 m ³ /hour.
1,3-butadiene and washing water were mixed using a static mixer (static mixer N60 series manufactured by Noritake Co., Ltd.), then transferred to a decanter, and the 1,3-butadiene phase and water phase were separated in the decanter.
The operation was performed under conditions of a liquid temperature of 30° C. and a decanter pressure of 1.0 MPaG.
The residence time of the 1,3-butadiene phase in the decanter was 30 minutes.
The water phase separated by the decanter was introduced into the 1,3-butadiene removal tank, mixed with steam and heated to 89° C., and at the same time, the total pressure was set to 0.01 MPaG to separate 1,3-butadiene from the water phase.

(Oxygen removal step with oxygen scavenger)
Subsequently, a 10% by mass aqueous solution of Diclean F-504 (manufactured by Kurita Water Industries) was used as the oxygen scavenger, and the 1,3-butadiene after the above (washing step) and the aqueous solution of the oxygen scavenger were mixed using a static mixer at a circulation flow rate of 1 m ³ /hour to perform liquid-liquid extraction. After that, it was moved to a decanter, and the 1,3-butadiene phase and the aqueous phase were separated in the decanter.
The residence time of the 1,3-butadiene phase in the decanter was 30 minutes. The operation was performed under conditions of a liquid temperature of 30° C. and a decanter pressure of 1.0 MPaG.

(Polymerization inhibitor removal step)
Subsequently, a 10% by mass caustic soda aqueous solution was mixed with 1,3-butadiene after the above (oxygen removal step with a deoxidizing agent) at a circulation flow rate of 1 m ³ /hour using a packed tower with a pole ring, subjected to liquid-liquid extraction, transferred to another decanter, and separated into a 1,3-butadiene phase and an aqueous phase in the other decanter.
The residence time of the 1,3-butadiene phase in the other decanter was 60 minutes. In addition, in the polymerization inhibitor removing step, the operation was performed under the conditions of a liquid temperature of 30° C. and a decanter pressure of 1.0 MPaG.

(Dehydration tower process)
Mixed hexane was added to the 1,3-butadiene phase separated by the other decanter to adjust the 1,3-butadiene concentration to 50% by mass, and the mixture was supplied to the dehydration tower.
After cooling and condensing the azeotropic mixture of 1,3-butadiene and water distilled from the top of the dehydration tower, it was transferred to a decanter, where the 1,3-butadiene phase and water phase were separated.
The aqueous phase was removed, and the 1,3-butadiene phase was returned to the inlet of the dehydration tower to continuously carry out the dehydration tower process.
A mixture of dehydrated 1,3-butadiene and hexane was taken out from the bottom of the dehydration tower.

(Adsorption process)
The mixture of 1,3-butadiene and hexane was passed through a 500 L desiccant dryer containing activated alumina (a vertical cylindrical tank manufactured by Hitachi, Ltd.) to adsorb and remove trace amounts of residual impurities in 1,3-butadiene to obtain purified 1,3-butadiene.

<Refinement of styrene>
Styrene used for polymerization of the modified conjugated diene polymer was purified by the following steps.
γ-alumina molded into a cylindrical shape of 3 mmΦ×3 mm was impregnated with an aqueous solution of palladium chloride having a concentration of 0.6% by mass and dried at 100° C. for one day. Then, the dried product was subjected to a reduction treatment at a temperature of 400° C. for 16 hours under a stream of hydrogen to obtain a hydrogenation catalyst having a composition of Pd (0.3 mass %)/γ-Al ₂ O ₃ . 2000 g of the obtained catalyst was packed in a tubular reactor and circulated for 8 hours while maintaining the temperature of this catalyst at 80° C. to obtain purified styrene.

<Purification of normal hexane>
Normal hexane used for polymerization of the modified conjugated diene polymer was purified by the following steps.
A tubular reactor was filled with 2000 g of molecular sieve 13-X (Union Showa) and circulated at room temperature for 24 hours to obtain purified normal hexane.

<Purification of Cyclohexane>
Cyclohexane used for polymerization of the modified conjugated diene polymer was purified by the following steps.
A tubular reactor was filled with 2000 g of molecular sieve 13-X (Union Showa) and circulated at room temperature for 24 hours to obtain purified cyclohexane.

<Purity analysis of raw materials>
Allenes, acetylenes, and amines were quantitatively analyzed as impurities in the raw material. Allenes and acetylenes were qualitatively and quantified by gas chromatography. The column used was Rt-Alumina BOND/MAPD (Shimadzu Corporation). Amines were extracted with boric acid and quantified by a titration method to calculate the total amount (ppm) of impurities.

<(Physical property 1) Amount of bound styrene>
Using a modified conjugated diene polymer as a sample, 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 modified conjugated diene polymer as a sample was measured from the absorption amount of the ultraviolet absorption wavelength (around 254 nm) by the phenyl group of styrene (spectrophotometer "UV-2450" manufactured by Shimadzu Corporation).

<(Physical property 2) Microstructure of butadiene portion (1,2-vinyl bond amount)>
Using a modified conjugated diene polymer as a sample, 50 mg of the sample was dissolved in 10 mL of carbon disulfide to obtain a measurement sample.
Using a solution cell, the infrared spectrum was measured in the range of 600 to 1000 cm ⁻¹ , and the absorbance at a predetermined wave number was calculated according to the formula of Hampton's method (RR Hampton, Analytical Chemistry 21, 923 (1949)). Rie transform infrared spectrophotometer "FT-IR230").

<(Physical property 3) molecular weight>
［測定条件１］：共役ジエン系重合体又は変性共役ジエン系重合体を試料として、ポリスチレン系ゲルを充填剤としたカラムを３本連結したＧＰＣ測定装置（東ソー社製の商品名「ＨＬＣ－８３２０ＧＰＣ」）を使用して、示差屈折率（ＲＩ）検出器（東ソー社製の商品名「ＨＬＣ８０２０」）を用いてクロマトグラムを測定し、標準ポリスチレンを使用して得られる検量線に基づいて、重量平均分子量（Ｍｗ）と数平均分子量（Ｍｎ）と分子量分布（Ｍｗ／Ｍｎ）と、変性共役ジエン系重合体のピークトップ分子量（Ｍｐ ₁ ）と、分子量２００×１０ ⁴以上５００×１０ ⁴以下の割合と、を求めた。 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 the measurement conditions 1, the samples whose molecular weight distribution (Mw/Mn) value was less than 1.6 were measured again under the following measurement conditions 2. Table 1 shows the results of measurement under measurement conditions 1 for samples having a molecular weight distribution value of 1.6 or more measured under measurement conditions 1.
The peak top molecular weight (Mp ₁ ) was determined as follows.
In the GPC curve obtained by measurement, the peak detected as the component with the highest molecular weight was selected. For the selected peak, the molecular weight corresponding to the maximum value of the peak was calculated and defined as the peak top molecular weight (Mp ₁ ).
The ratio of the molecular weight of 200×10 ⁴ to 500×10 ⁴ was determined as the ratio of the molecular weight of 200×10 ⁴ to 500×10 ⁴ to the total weight of the polymer.
[Measurement condition 2]: A conjugated diene polymer or modified conjugated diene polymer is used as a sample, and a chromatogram is measured using a GPC measurement apparatus in which three columns filled with polystyrene gel are connected, and based on a calibration curve using standard polystyrene, the weight average molecular weight (Mw) and number average molecular weight (Mn), the peak top molecular weight (Mp ₁ ) of the modified conjugated diene polymer, and the molecular weight of the peak with the lowest molecular weight (minimum molecular weight). The distribution (Mw/Mn) and the ratio of the peak area with the lowest molecular weight to the total peak area were determined. 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. Table 2 shows the results of measurement under measurement conditions 2 for the samples whose molecular weight distribution values were less than 1.6 when measured under measurement conditions 1 as described above.

<(Physical Property 4) Polymer Mooney Viscosity>
Using a conjugated diene-based polymer or a modified conjugated diene-based polymer as a sample, a Mooney viscometer (trade name “VR1132” manufactured by Ueshima Seisakusho Co., Ltd.) was used to measure the Mooney viscosity using an L-shaped rotor in accordance with JIS K6300.
The measurement temperature was 100°C.
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 5) glass transition temperature (Tg)>
Using a modified conjugated diene-based polymer as a sample, a differential scanning calorimeter "DSC3200S" manufactured by Mac Science Co., Ltd. was used in accordance with ISO 22768:2006 to record a DSC curve while increasing the temperature from -100 ° C. to 20 ° C./min under a helium flow of 50 mL / min, and the peak top (Inflection point) of the DSC differential curve was taken as the glass transition temperature.

<(Physical property 6) Modification rate with respect to total amount of conjugated diene polymer>
Using a modified conjugated diene-based polymer as a measurement sample, measurement was performed by applying the characteristics of adsorption of the modified basic polymer component to a GPC column filled with silica gel.
A sample solution containing a measurement sample and a low-molecular-weight internal standard polystyrene was measured with a polystyrene column and a chromatogram measured with a silica column. The amount of adsorption to the silica column was measured from the difference between the chromatograms, and the modification rate was obtained.
Specifically, it is as shown below.
Preparation of sample solution for measurement: 10 mg of sample for measurement and 5 mg of standard polystyrene were dissolved in 20 mL of THF (tetrahydrofuran) to prepare a sample solution for measurement.
GPC measurement conditions using a polystyrene column:
[Measurement condition 1]: A sample in which the molecular weight distribution of the modified conjugated diene-based polymer measured in physical property 3 was 1.6 or more A chromatogram was obtained using an RI detector under the conditions of a column oven temperature of 40 ° C. and a THF flow rate of 0.35 mL / min using a product name "HLC-8320GPC" manufactured by Tosoh Corporation, using THF containing 5 mmol / L triethylamine as an eluent, injecting 10 μL of the sample solution for measurement into the apparatus. 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.
[Measurement condition 2]: A sample in which the molecular weight distribution of the modified conjugated diene-based polymer measured in physical property 3 was less than 1.6 Using THF containing 5 mmol/L triethylamine as an eluent and measuring by injecting 20 μL of the sample solution into the apparatus, the product name "HLC-8320GPC" manufactured by Tosoh Corporation was used. 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. A chromatogram was obtained by measurement using an RI detector under conditions of a column oven temperature of 40° C. and a THF flow rate of 0.6 mL/min.
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, RI detector was used to obtain a chromatogram. Columns were used by connecting the product names "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S", and connected and used the product name "DIOL 4.6×12.5 mm 5 micron" as a guard column in front of them.
Modification rate calculation method: The total peak area of the chromatogram using a polystyrene column is set to 100, the peak area of the sample is P1, the peak area of standard polystyrene is P2, the total peak area of the chromatogram using a silica column is set to 100, the peak area of the sample is P3, and the peak area of standard polystyrene is P4.
Modification rate (mass%) = [1-(P2 × P3) / (P1 × P4)] × 100
(In the above formula, P1+P2=P3+P4=100.)

<(Physical property 7) Low molecular weight modification rate>
According to the measurement of (Physical property 3), the peak top in the GPC curve of the modified conjugated diene polymer having a molecular weight distribution (Mw/Mn) of 1.6 or more, or the peak top molecular weight (Mp _min ), which is the minimum molecular weight when there are multiple peak tops, was measured. The height of the chart for the molecular weight obtained by dividing the peak top molecular weight (Mp _min ) by 2 was defined as L1.
The height of the molecular weight obtained by dividing Mp _min by 2 in the chart measured according to the measurement of (physical property 6) using a silica-based column was defined as L2.
The denaturation rate (low molecular weight denaturation rate (FL)) of the component with a molecular weight that is half the peak top molecular weight (Mp _min ) was calculated by the following formula.
Low molecular weight modification rate (%) = (1-L2/L1) x 100

[Degree of denaturation of low molecular weight component]
The degree of modification (%) of the low-molecular-weight component was calculated by dividing (Physical Property 7) Low-molecular-weight modification rate (FL) by (Physical Property 6) Modification rate (FT) relative to the total amount of the conjugated diene polymer.
Modification degree of low molecular weight component (%) = FL/FT x 100

<(Physical Property 8) Shrinkage Factor (g′)>
Using a modified conjugated diene-based polymer as a sample, a chromatogram was measured using a GPC-light scattering measurement device with a viscosity detector in which three columns filled with polystyrene gel were connected, and the molecular weight was determined based on the solution viscosity and light scattering method.
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 an 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) with a viscosity detector 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.
The intrinsic viscosity and molecular weight of the obtained measurement sample are calculated by setting the constants (K, α) in the relational expression between intrinsic viscosity and molecular weight ([η] [η] = KMα ([η]: intrinsic viscosity, M: molecular weight) to log K = -3.883, _α = 0.771, and inputting the range of molecular weight M from 1000 to 20000000. The relationship between standard intrinsic viscosity [η] ₀ and molecular weight M is calculated for each molecular weight M. [η]/[η] ₀ was calculated for each molecular weight M, and the average value was taken as the shrinkage factor (g').

<(Physical property 9) Silicon content>
When the modified conjugated diene-based polymer is an oil-extended polymer, after extracting the extended oil, an inductively coupled plasma (ICP) mass spectrometer (Agilent 7700s manufactured by Agilent Technologies) was used to measure the silicon content in the modified conjugated diene-based polymer.

<(Physical property 10) Nitrogen content>
When the modified conjugated diene-based polymer is an oil-extended polymer, the nitrogen content in the modified conjugated diene-based polymer was measured using a trace total nitrogen analyzer (TN-2100H manufactured by Mitsubishi Chemical Analytic Tech) after extracting the extended oil.

[Modified conjugated diene-based polymer (Sample 1)]
A tank-type pressure vessel having an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L/D) of 4.0, an inlet at the bottom, an outlet at the top, and a jacket for temperature control and a stirrer was used as a polymerization reactor.
18.1 g/min of 1,3-butadiene, 9.9 g/min of styrene, and 150.1 g/min of n-hexane, which had been previously dehydrated, were supplied to the polymerization reactor and mixed. The allenes contained in this mixed solution were 10 ppm, the acetylenes were 12 ppm, and the amines were 1 ppm. Total impurities were 23 ppm.
In a static mixer installed in the middle of the pipe that supplies this mixed solution to the inlet of the polymerization reactor, n-butyllithium for deactivation treatment of residual impurities was added at 0.104 mmol/min, mixed, and then continuously supplied to the bottom of the polymerization reactor. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance at a rate of 0.0087 g/min and n-butyllithium as a polymerization initiator at a rate of 0.10 mmol/min were supplied to the bottom of the polymerization reactor, which was vigorously mixed with a stirrer, to continuously continue the polymerization reaction. The temperature was controlled so that the temperature of the polymerization solution at the top outlet of the polymerization reactor was 70°C.
Next, bis(3-trimethoxysilylpropyl)-N-methylamine (abbreviated as “A” in the table) was continuously added as a modifier to the polymer solution flowing out from the outlet of the polymerization reactor at a rate of 0.026 mmol/min.
An antioxidant (BHT) was continuously added to the modified polymer solution at a rate of 0.2 g per 100 g of polymer at a rate of 0.055 g/min (n-hexane solution) to terminate the coupling reaction. At the same time as the antioxidant, 37.5 g of oil (JOMO Process NC140 manufactured by JX Nippon Oil & Energy Corporation) was continuously added to 100 g of the polymer, and mixed with a static mixer. The solvent was removed by steam stripping to obtain a modified conjugated diene polymer (Sample 1). Table 1 shows the physical properties of Sample 1. The polymerization initiator residue of the obtained modified conjugated diene polymer (Sample 1) did not contain nitrogen.

[Modified conjugated diene polymer (Sample 2)]
In the purification of 1,3-butadiene, the residence time of the 1,3-butadiene phase in the decanter during the water washing step was adjusted to 10 minutes. Also, the residence time of the 1,3-butadiene phase in the decanter in the polymerization inhibitor removing step was adjusted to 20 minutes.
Also, in the purification of styrene, a Pd (0.3%)/γ-Al ₂ O ₃ hydrogenation catalyst was obtained. 2000 g of the obtained catalyst was packed in a tubular reactor, and styrene purified by circulation for 4 hours was used while maintaining the temperature of this catalyst at 80°C. In refining normal hexane, the above refining was carried out.
Allenes contained in the mixture of 1,3-butadiene, styrene and n-hexane were 25 ppm, acetylenes were 20 ppm, and amines were 9 ppm. Total impurities were 54 ppm.
The polymerization initiator was changed to a mixed solution of lithium piperidide (also referred to as "1-lithiopiperidine") and n-butyllithium (lithium piperidide: n-butyllithium (molar ratio) = 0.75: 0.25) as lithium amide prepared in advance, and the polymerization initiator was added at a rate of 0.10 mmol/min. Other conditions were the same as for (Sample 1) to obtain a modified conjugated diene-based polymer (Sample 2). Table 1 shows the physical properties of Sample 2.

[Modified conjugated diene polymer (Sample 3)]
The polymerization initiator was added at a rate of 0.252 mmol/min, and the polar substance was added at a rate of 0.0216 mmol/min. Also, the modifier was changed to tris(3-trimethoxysilylpropyl)amine (abbreviated as "B" in the table), and the addition rate of the modifier was changed to 0.043 mmol/min. A modified conjugated diene polymer (Sample 3) was obtained under the same conditions as (Sample 1) except for the above conditions. Table 1 shows the physical properties of Sample 3. The polymerization initiator residue of the obtained modified conjugated diene polymer (Sample 3) did not contain nitrogen.

[Modified conjugated diene-based polymer (Sample 4)]
In the purification of 1,3-butadiene, the residence time of the 1,3-butadiene phase in the decanter during the water washing step was adjusted to 10 minutes. Also, the residence time of the 1,3-butadiene phase in the decanter in the polymerization inhibitor removing step was adjusted to 20 minutes.
Also, in the purification of styrene, a Pd (0.3%)/γ-Al ₂ O ₃ hydrogenation catalyst was obtained. 2000 g of the obtained catalyst was packed in a tubular reactor, and styrene purified by circulation for 4 hours was used while maintaining the temperature of this catalyst at 80°C. In refining normal hexane, the above refining was carried out.
Allenes contained in the mixture of 1,3-butadiene, styrene and n-hexane were 25 ppm, acetylenes were 20 ppm, and amines were 9 ppm. Total impurities were 54 ppm.
The polymerization initiator was replaced with a mixed solution of lithium piperidide (also referred to as “1-lithiopiperidine”) and n-butyllithium (lithium piperidide:n-butyllithium (molar ratio)=0.75:0.25) as lithium amide prepared in advance. A modified conjugated diene polymer (Sample 4) was obtained under the same conditions as (Sample 3) except for the above conditions. Table 1 shows the physical properties of Sample 4.

[Modified conjugated diene polymer (Sample 5)]
The polymerization initiator was added at a rate of 0.252 mmol/min, and the polar substance was added at a rate of 0.0216 mmol/min. The modifier was replaced with N,N,N',N'-tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine (abbreviated as "C" in the table), and the modifier was added at a rate of 0.033 mmol/min. A modified conjugated diene polymer (Sample 5) was obtained under the same conditions as (Sample 1) except for the above conditions. Table 1 shows the physical properties of Sample 5. The polymerization initiator residue of the obtained modified conjugated diene polymer (Sample 5) did not contain nitrogen.

[Modified conjugated diene-based polymer (Sample 6)]
In the purification of 1,3-butadiene, the residence time of the 1,3-butadiene phase in the decanter during the water washing step was adjusted to 10 minutes. Further, the residence time of the 1,3-butadiene phase in the decanter in the polymerization inhibitor removing step was adjusted to 20 minutes.
Also, in the purification of styrene, a Pd (0.3%)/γ-Al ₂ O ₃ hydrogenation catalyst was obtained. 2000 g of the obtained catalyst was packed in a tubular reactor, and styrene purified by circulation for 4 hours was used while maintaining the temperature of this catalyst at 80°C. In refining normal hexane, the same refining as described above was performed.
Allenes contained in the mixture of 1,3-butadiene, styrene and n-hexane were 25 ppm, acetylenes were 20 ppm, and amines were 9 ppm. Total impurities were 54 ppm.
The polymerization initiator was replaced with a mixed solution of lithium piperidide (also referred to as “1-lithiopiperidine”) and n-butyllithium (piperidinolithium:n-butyllithium (molar ratio)=0.75:0.25) as lithium amide prepared in advance. A modified conjugated diene-based polymer (Sample 6) was obtained under the same conditions as (Sample 5) except for the above conditions. Table 1 shows the physical properties of Sample 6.

[Modified conjugated diene-based polymer (Sample 7)]
In the purification of 1,3-butadiene, the residence time of the 1,3-butadiene phase in the decanter during the water washing step was adjusted to 10 minutes. Also, the residence time of the 1,3-butadiene phase in the decanter in the polymerization inhibitor removing step was adjusted to 20 minutes.
Also, in the purification of styrene, a Pd (0.3%)/γ-Al ₂ O ₃ hydrogenation catalyst was obtained. 2000 g of the obtained catalyst was packed in a tubular reactor, and styrene purified by circulation for 4 hours was used while maintaining the temperature of this catalyst at 80°C. In refining normal hexane, the same refining as described above was performed.
Allenes contained in the mixture of 1,3-butadiene, styrene and n-hexane were 25 ppm, acetylenes were 20 ppm, and amines were 9 ppm. Total impurities were 54 ppm. A modified conjugated diene-based polymer (Sample 7) was obtained in the same manner as (Sample 1) except that these starting materials were used. Table 1 shows the physical properties of Sample 7. The polymerization initiator residue of the obtained modified conjugated diene polymer (Sample 7) did not contain nitrogen.

[Modified conjugated diene-based polymer (Sample 8)]
The polymerization initiator was added at a rate of 0.20 mmol/min, and the polar substance was added at a rate of 0.0174 mmol/min. Also, the modifier was changed to bis(3-trimethoxysilylpropyl)-N-methylamine (abbreviated as "A" in the table), and the addition rate of the modifier was changed to 0.052 mmol/min. A modified conjugated diene polymer (Sample 8) was obtained under the same conditions as (Sample 1) except for the above conditions. Table 1 shows the physical properties of Sample 8. The polymerization initiator residue of the obtained modified conjugated diene polymer (Sample 8) did not contain nitrogen.

[Modified conjugated diene-based polymer (Sample 9)]
A tank-type pressure vessel having an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L/D) of 4.0, an inlet at the bottom, an outlet at the top, and a jacket for temperature control and a stirrer was used as a polymerization reactor.
592 g of 1,3-butadiene, 208 g of styrene, 5200 g of cyclohexane, and 0.83 g of 2,2-bis(2-oxolanyl)propane as a polar substance, which had been preliminarily removed of moisture, were placed in a polymerization reactor, and the reactor temperature was maintained at 50°C. 9.24 mmol of n-butyllithium as a polymerization initiator was supplied to the polymerization reactor. After the start of the polymerization reaction, the temperature inside the polymerization reactor started to rise due to the heat generated by the polymerization, and the final temperature inside the polymerization reactor reached 76°C. Two minutes after reaching the reaction temperature peak, 1.22 mmol of bis(trimethoxysilylpropyl)methylamine (abbreviated as "A" in the table) as a modifier was added to the polymerization reactor, and a modification reaction was carried out for 5 minutes.
To the modified polymer solution, an antioxidant (BHT)/cyclohexane solution was added so that the antioxidant (BHT) was 0.2 g per 100 g of the polymer to complete the coupling reaction. The solvent was removed by steam stripping to obtain a modified conjugated diene polymer (Sample 9). Table 2 shows the physical properties of Sample 9.

[Modified conjugated diene polymer (Sample 10)]
A modified conjugated diene polymer (Sample 10) was obtained in the same manner as in (Sample 9) except that 11.50 mmol of n-butyllithium as the polymerization initiator was replaced with 1.14 g of 2,2-bis(2-oxolanyl)propane as the polar substance, and 1.12 mmol of tris(3-trimethoxysilylpropyl)amine (abbreviated as "B" in the table) was replaced as the modifying agent. The final temperature in the polymerization reactor reached 77°C.

[Modified conjugated diene polymer (Sample 11)]
The polymerization initiator was replaced with a mixed solution of lithium piperidide (also referred to as "1-lithiopiperidine") and n-butyllithium (lithium piperidide: n-butyllithium (molar ratio) = 0.75: 0.25) as lithium amide prepared in advance, and 9.24 mmol was supplied to the polymerization reactor. After the start of the polymerization reaction, the temperature in the polymerization reactor started to rise due to the heat generated by the polymerization, and the final temperature in the polymerization reactor reached 75°C. A modified conjugated diene polymer (Sample 11) was obtained in the same manner as (Sample 9) except for the conditions. Table 2 shows the physical properties of Sample 11.

[Modified conjugated diene-based polymer (Sample 12)]
Instead of the modifier, 0.60 mmol of tetramethoxysilane (abbreviated as "D" in the table) was supplied to the polymerization reactor as a coupling agent. A conjugated diene polymer (Sample 12) was obtained in the same manner as (Sample 9) except for the conditions. Table 2 shows the physical properties of Sample 12.

[Modified conjugated diene-based polymer (Sample 13)]
The amount of modifier bis(trimethoxysilylpropyl)methylamine (abbreviated as “A” in the table) was changed to 0.60 mmol. A modified conjugated diene polymer (Sample 13) was obtained under the same conditions as (Sample 11) except for the above conditions. Table 2 shows the physical properties of Sample 13.

[Modified conjugated diene-based polymer (Sample 14)]
Instead of the modifying agent, 1.22 mmol of tetramethoxysilane (abbreviated as "D" in the table) was supplied to the polymerization reactor as a coupling agent. A conjugated diene polymer (Sample 14) was obtained in the same manner as (Sample 9) except for the conditions. Table 2 shows the physical properties of Sample 14.

[(Examples 1 to 17) and (Comparative Examples 1 to 8)]
Using the rubber-like polymers shown in Tables 1 and 2 (Samples 1 to 14) as raw materials, according to the formulations shown below and Table 3, rubber compositions containing the respective raw rubber-like polymers were obtained.
Modified conjugated diene polymer (samples 1 to 14): 100 parts by mass (without oil)
Silica 1 (trade name “Ultrasil 7000 GR” nitrogen adsorption specific surface area 170 m / g manufactured by Evonik Degussa): 50.0 parts by mass Silica 2 (trade name “Zeosil Premium 200MP” nitrogen adsorption specific surface area 220 m / g manufactured by Rhodia): 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 S-RAE oil (trade name "Process NC140" manufactured by JX Nippon Oil & Energy Co., Ltd.): 37.5 parts by mass Zinc oxide: 2.5 parts by mass Stearic acid: 1.0 parts by mass Antiaging agent (N-(1,3-dimethylbutyl)-N'- Phenyl-p-phenylenediamine): 2.0 parts by mass Sulfur: 2.2 parts by mass Vulcanization accelerator 1 (N-cyclohexyl-2-benzothiazylsulfinamide): 1.7 parts by mass Vulcanization accelerator 2 (diphenylguanidine): 2.0 parts by mass Total: 234.9 parts by mass A rubber composition was obtained by kneading the above materials by the following method.
Using a closed kneader (inner volume 0.3 L) equipped with a temperature control device, the raw material rubber-like polymers (Samples 1 to 14), fillers (silica 1, silica 2, carbon black), silane coupling agent, process oil (S-RAE oil), zinc oxide, and stearic acid were kneaded for the first stage kneading at a filling rate of 65% and a rotor rotation speed of 30 to 50 rpm to obtain each rubber composition (compound).
At this time, the temperature of the closed mixer was controlled to set the discharge temperature to 155 to 160°C.

(Evaluation 1) Rise Time and Maximum Value of Torque At the time of kneading in the first stage, the time required for the torque to reach the maximum value after the start of kneading in the closed kneader was measured. Each measured value was indexed with the result of Comparative Example 1 as 100.
As for the torque rise time, the smaller the index, the shorter the rise time and the better the moldability.
Regarding the maximum value of torque, the larger the index, the larger the maximum torque applied to kneading.

(Evaluation 2) Sheet processability Using the rubber composition (compound) obtained through the first stage of kneading as described above, a sheet-like composition was processed with an open roll set at 70°C.
The state of the sheet of the obtained sheet-like composition was visually observed and evaluated on a 5-point scale according to the following criteria.
A higher score indicates better sheet processability.
5: Good bundling during rolling operation, smooth sheet texture, and no jagged sheet edges.
4: Good bundling during rolling operation, but the sheet surface is slightly rough and the sheet edge is also slightly jagged.
3: Slightly poor coherence during rolling operation, the sheet surface is slightly rough, and the sheet edge is also slightly jagged.
2: Cohesiveness during rolling operation is somewhat poor, the sheet surface is rough, and the sheet edge is jagged.
1: Poor coherence during rolling operation, rough sheet surface, and jagged sheet edges.

Next, as the second step of kneading, after cooling the mixture obtained above to room temperature, an antioxidant was added and kneaded again in order to improve the 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. for 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. Table 3 shows the evaluation results.

(Evaluation 3) Compound Mooney Viscosity (Compound ML)
After the second-stage kneading, the conjugated diene-based polymer or modified conjugated diene-based polymer before cross-linking was used as a sample, and a Mooney viscometer (trade name “VR1132” manufactured by Ueshima Seisakusho Co., Ltd.) was used to measure the Mooney viscosity using an L-shaped rotor in accordance with JIS K6300. The measurement temperature was 100°C.
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₎ ).
Each measured value was indexed with the result of Comparative Example 1 as 100. The smaller the index, the smaller the compound Mooney viscosity and the better the workability.

(Evaluation 4) Viscoelasticity parameter (fuel efficiency)
A viscoelasticity tester "ARES" manufactured by Rheometrics Scientific Co., Ltd. was used to measure the viscoelasticity parameters of the vulcanized rubber composition in a torsion mode. Each measured value was indexed by setting the result for the rubber composition of Comparative Example 1 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 grip properties. A larger value indicates better wet grip. 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 larger value indicates better fuel economy.

(Evaluation 5) Abrasion resistance For the rubber composition after vulcanization, an Akron abrasion tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) was used to measure the amount of abrasion at 1000 rotations at a load of 44.4 N according to JIS K6264-2, and the result of Comparative Example 1 was indexed as 100. A larger index indicates better wear resistance.

As shown in Table 3, the rubber compositions of Examples 1 to 17 had a relatively rapid torque rise during kneading, a short torque rise time, and good processability compared to the rubber compositions of Comparative Examples 1 to 8. As a result, it was confirmed that when vulcanized, the fuel efficiency (low fuel consumption) was excellent. In addition, it was confirmed that the wear resistance was sufficient for practical use.

INDUSTRIAL APPLICABILITY The rubber composition according to the present invention has industrial applicability in fields such as tire treads, automobile interior/exterior parts, anti-vibration rubber, belts, footwear, foam bodies, and various industrial products.

Claims (7)

A rubber composition containing 100 parts by mass of a rubber-like polymer and 5 to 150 parts by mass of a filler,
A rubber composition in which the rubber-like polymer contains at least two types of modified conjugated diene-based polymers (A) and (B), the content of the modified conjugated diene-based polymer (A) in the rubber-like polymer is 30% by mass or more, and the modified conjugated diene-based polymers (A) and (B) each have the following characteristics.
[Modified conjugated diene polymer (A):
A modified conjugated diene polymer having a weight average molecular weight of 20×10 ⁴ or more and 300×10 ⁴ or less, a molecular weight distribution Mw/Mn of 1.6 or more and 4.0 or less, a modification rate of 50% by mass or more relative to the total amount of the conjugated diene polymer, and a shrinkage factor (g′) measured by gel permeation chromatography with a viscosity detector-light scattering method measurement (3D-GPC) of less than 0.86. ]
[Modified conjugated diene polymer (B):
A modified conjugated diene-based polymer having two or more peak tops in a gel permeation chromatography (GPC) curve, having a molecular weight distribution Mw/Mn of 1.0 or more and less than 1.6 for the peak with the lowest molecular weight and having a peak area of 2 to 50% relative to the total peak area, and a modified conjugated diene-based polymer having a modification rate of 50% by mass or more relative to the total amount of the conjugated diene-based polymer. ] The rubber composition according to claim 1, wherein the modification rate of the peak top in the gel permeation chromatography (GPC) curve of the modified conjugated diene-based polymer (A), or the molecular weight of the peak top with the smallest molecular weight when there are a plurality of peak tops, is 1/2 or more of the modification rate of the component with a molecular weight of 1/2 or more relative to the total amount of the conjugated diene-based polymer (A). The rubber composition according to claim 1 or 2, wherein the modified conjugated diene polymer (A) and/or (B) contains nitrogen and silicon, and the nitrogen and silicon contents in the modified conjugated diene polymer are each 3 mass ppm or more. The rubber composition according to any one of claims 1 to 3, wherein the modified conjugated diene polymer (A) and/or (B) contains nitrogen, and the nitrogen content in the modified conjugated diene polymer is 25 ppm by mass or more. The rubber composition according to any one of claims 1 to 4, wherein the polymerization initiator residue of the modified conjugated diene polymer (A) does not contain nitrogen. The rubber composition according to any one of claims 1 to 5, wherein the modified conjugated diene polymer (A) and/or (B) has a 3D-GPC shrinkage factor (g') of 0.70 or less. The rubber composition according to any one of claims 1 to 6, wherein the modified conjugated diene polymer (A) and/or (B) is represented by the following general formula (I).
(In formula (I), D ₁ represents a diene polymer chain, R ¹ to R ³ each independently represent a single bond or an alkylene group having 1 to 20 carbon atoms, R ⁴ and R ⁷ each independently represent an alkyl group having 1 to 20 carbon atoms, R ⁵ , R ⁸ , and R ⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and R ⁶ and R ¹⁰ each independently It represents an alkylene group having 1 to 20 carbon atoms, and R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.
m and x represent an integer of 1 to 3, x≦m, p represents 1 or 2, y represents an integer of 1 to 3, y≦(p+1), and z represents an integer of 1 or 2.
D ₁ , R ¹ to R ¹¹ , m, p, x, y, and z when there are more than one are each independent.
i represents an integer of 0 to 6, j represents an integer of 0 to 6, k represents an integer of 0 to 6, (i + j + k) is an integer of 1 to 10, and ((x x i) + (y x j) + (z x k)) is an integer of 1 to 30.
A is a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom and a phosphorus atom and having no active hydrogen. However, when (i+j+k) is 1, A may be absent. )