Conjugated diene polymer, production method thereof, and rubber composition.

Abstract

To provide a conjugated diene-based polymer which, after suppressing cold flowability after molding into a bale, has excellent workability when made into a vulcanizate, and when made into a vulcanizate, has excellent fracture characteristics and abrasion resistance and has an excellent balance between a low hysteresis loss property and wet skid resistance.SOLUTION: A conjugated diene-based polymer has a Mooney viscosity measured at 100°C of 30 to 120, has a 1,2-vinyl bond amount of 25 mole% or less, has a 1,4-cis bond amount of 40 mole% or less, has a branching degree (Bn) according to a GPC-light scattering measurement method with a viscosity detector attached is 4 to 25, and contains a nitrogen atom.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] BACKGROUND ART There has been an increasing demand for improved fuel economy in automobiles, and there has been a demand for improvements in the rubber materials used in automobile tires, particularly in the tire treads that come into contact with the road surface.

[0003] In recent years, increasing demands for fuel economy regulations for automobiles have led to a demand for tires that have low energy loss during driving. In particular, the rubber material used in the tire tread, which comes into contact with the road surface, needs to have low rolling resistance, i.e., low hysteresis loss.

[0004] In particular, tires for heavy loads used on large vehicles such as trucks and buses are required to have improved fuel efficiency with low energy loss in addition to the conventional properties of high strength and wear resistance required to support heavy loads. Specifically, rubber materials used in tire treads for heavy loads are required to have high fracture strength, excellent wear resistance, low hysteresis loss, and, from the perspective of safety, excellent wet skid resistance.

[0005] Examples of rubber materials that meet the above-mentioned requirements include rubber compositions containing a rubbery polymer and a reinforcing filler such as carbon black, silica, etc. In particular, natural rubber and conjugated diene polymers, which have good fracture strength and abrasion resistance, are preferably used as rubbers for highly loaded tire treads.

[0006] Furthermore, as improvements to the rubber-like polymer itself, for example, a modified conjugated diene polymer having a hydroxyl group at the end of the polymer chain and a composition thereof, and a method for producing a conjugated diene polymer in which a hydrocarbyloxysilane compound is reacted with the end of the polymer chain and then a specific compound such as a hydrocarbyloxysilane compound is further reacted, and a composition thereof have been proposed (see, for example, Patent Documents 1 and 2).

[0007] Furthermore, a method for producing a branched butadiene polymer has been proposed in which an organolithium compound is used as an initiator and the ends of the polymer chain are coupled with a specific compound (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2017-171806 [Patent Document 2] International Publication No. 03 / 046020 Brochure [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-108977 Summary of the Invention [Problem to be solved by the invention]

[0009] Here, the use of a rubber composition containing silica improves the balance between low hysteresis loss and wet skid resistance. Also, by introducing functional groups having affinity or reactivity with silica into the molecular terminals of a highly mobile rubber-like polymer, the dispersibility of silica in the rubber composition is improved, and further, the mobility of the molecular terminals of the rubber-like polymer is reduced by bonding with silica particles, thereby reducing hysteresis loss and improving abrasion resistance and fracture strength.

[0010] However, since silica has a hydrophilic surface while carbon black has a hydrophobic surface, it has a drawback in that it has poorer dispersibility in the composition than carbon black due to its low affinity with the conjugated diene polymer. Therefore, a composition containing silica needs to contain a separate silane modifier or the like to provide a bond between the silica and the conjugated diene polymer and improve dispersibility in the composition.

[0011] Furthermore, when a functional group highly reactive with silica is introduced into the molecular end of a conjugated diene polymer, the reaction with the silica particles proceeds during the kneading step, causing an increase in the viscosity of the composition, which tends to deteriorate processability, such as making kneading difficult or causing roughness in the surface when forming the composition into a sheet after kneading or making the sheet more susceptible to tearing.

[0012] Furthermore, when such a composition is vulcanized, particularly when it contains an inorganic filler such as silica, the balance between abrasion resistance, low hysteresis loss, and wet skid resistance is insufficient.

[0013] In addition, conjugated diene polymers, which are preferably used in highly loaded tire treads, have the problem that the bales, which are the product form, tend to flow easily (hereinafter referred to as cold flow), making the bales difficult to handle after storage.

[0014] Therefore, an object of the present invention is to provide a conjugated diene polymer which, after being molded into a bale, exhibits excellent processability when vulcanized, has excellent fracture properties and abrasion resistance when vulcanized, and has an excellent balance between low hysteresis loss and wet skid resistance. [Means for solving the problem]

[0015] As a result of intensive research and investigation to solve the above-mentioned problems of the conventional art, the present inventors have found that a conjugated diene copolymer having a Mooney viscosity measured at 100°C within a predetermined range, a specific microstructure of the conjugated diene polymer, and a nitrogen atom in the polymer chain of the conjugated diene polymer, suppresses cold flow after molding into a bale, has excellent processability when vulcanized, and has excellent fracture properties and abrasion resistance when vulcanized, and has an excellent balance between low hysteresis loss and wet skid resistance, thereby completing the present invention.

[0016] That is, the present invention is as follows. [1] The Mooney viscosity measured at 100°C is 30 or more and 120 or less, the amount of 1,2 vinyl bonds is 25 mol% or less, and the amount of 1,4 cis bonds is 40 mol% or less, A conjugated diene polymer containing a nitrogen atom, having a branching degree (Bn) of 4 or more and 25 or less as measured by a GPC-light scattering method with a viscosity detector. [2] The branching degree (Bn) of the 1 / 2Hi polymer is 7 or more as determined by a GPC-light scattering measurement method with a viscosity detector, The degree of branching (Bn) of the polymer at 1 / 2Hi is, based on the height of a peak top in an absolute molecular weight curve (however, when there are multiple peak tops in the absolute molecular weight curve, the height of the peak top with the largest absolute molecular weight: Hi), the degree of branching (Bn) of the polymer at the highest absolute molecular weight among at least two absolute molecular weights when the height in the absolute molecular weight curve is half the height (1 / 2Hi) of Hi. [3] The conjugated diene polymer according to [1] or [2], which has a modification rate of 60% by mass or more as measured by column adsorption GPC. [4] The conjugated diene polymer according to any one of [1] to [3], which has a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and the moiety derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group has a branched structure. [5] The moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group is a monomer unit derived from a compound represented by the following formula (1) or (2): The conjugated diene polymer according to [4], having a polymer chain branching point due to a monomer unit derived from a compound represented by the following formula (1) or (2): [ka] (In the formula, R 1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may have a branched structure in part, or an aryl group having 6 to 20 carbon atoms, R 2 ~R 3 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, which may have a branched structure in part, When there are a plurality of R1 to R3, they are independent of each other. X 1 indicates an independent halogen atom, m represents an integer of 0 to 2, n represents an integer of 0 to 3, l represents an integer of 0 to 3, and (m+n+l) is 3. [ka] (In the formula, R 2 ~R 5 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, which may have a branched structure in part, and when there are a plurality of R 2 ~R 5 are independent of each other, X 2 ~X 3 each represents an independent halogen atom, m represents an integer of 0 to 2, n represents an integer of 0 to 3, l represents an integer of 0 to 3, and (m+n+l) is 3; a represents an integer of 0 to 2, b represents an integer of 0 to 3, c represents an integer of 0 to 3, and (a+b+c) is 3. [6] The compound has a monomer unit derived from the compound represented by formula (1), and in formula (1), R 1 [6] The conjugated diene polymer according to [5], wherein represents a hydrogen atom and m represents 0. [7] The conjugated diene polymer according to [4], which has a monomer unit derived from a compound represented by the formula (2), wherein m and b are 0 in the formula (2). [8] The compound has a monomer unit derived from the compound represented by formula (1), and in formula (1), R 1 represents a hydrogen atom, m represents 0, n represents 3, and 1 represents 0. The conjugated diene polymer according to [5]. [9] The conjugated diene polymer according to [5], which has a monomer unit derived from a compound represented by the formula (2), wherein in the formula (2), m represents 0, n represents 3, l represents 0, a represents 0, b represents 0, and c represents 3.

[10] a polymerization and branching step of polymerizing a conjugated diene compound using an organolithium compound as a polymerization initiator while adding a branching agent to obtain a conjugated diene-based polymer having a branched structure; The method for producing a conjugated diene polymer according to any one of [1] to [9], further comprising a modification step of modifying the conjugated diene polymer with a modifying agent.

[11] The rubber composition includes a rubber component and a filler in an amount of 5.0 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the rubber component, The rubber composition contains 10% by mass or more of the conjugated diene polymer according to any one of [1] to

[10] , relative to 100% by mass of the total amount of the rubber component. [Effects of the Invention]

[0017] The conjugated diene polymer according to the present invention suppresses cold flow after molding into a bale, and has excellent processability when vulcanized. The vulcanized product has excellent fracture properties and abrasion resistance, and is well-balanced between low hysteresis loss and wet skid resistance. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is an image diagram showing an example of the relationship between the absolute molecular weight curve and the branching degree distribution measured by GPC-light scattering measurement method with a viscosity detector. DETAILED DESCRIPTION OF THE INVENTION

[0019] The following describes in detail the form for implementing the present invention (hereinafter referred to as the "present embodiment"); however, the present invention is not limited to this, and various modifications are possible within the scope of the gist of the present invention.

[0020] [Conjugated diene polymer] The conjugated diene polymer of the present embodiment has a Mooney viscosity measured at 100°C of 30 or more and 120 or less, a 1,2 vinyl bond content of 25 mol% or less, a 1,4 cis bond content of 40 mol% or less, a branching degree (hereinafter also referred to as "Bn") measured by a GPC-light scattering method with a viscosity detector of 4 or more and 25 or less, and contains a nitrogen atom.

[0021] As described above, a conjugated diene polymer having a degree of branching (Bn) within a specific range, a specified microstructure, and a specific Mooney viscosity measured at 100°C suppresses cold flow after bale molding, exhibits excellent processability when vulcanized, and exhibits excellent fracture properties and wear resistance when vulcanized. Furthermore, the presence of nitrogen atoms in the polymer chain results in an excellent balance between low hysteresis loss and wet skid resistance when vulcanized.

[0022] (Mooney viscosity) The conjugated diene polymer of this embodiment has a structure with a specific degree of branching (Bn), as described below. Generally, polymers having a branched structure tend to have smaller molecular size compared to linear polymers of the same molecular weight. Therefore, the molecular weight of a polymer having a branched structure tends to be underestimated when the molecular weight is determined in terms of polystyrene by gel permeation chromatography (hereinafter also referred to as "GPC") measurement, which is a relative comparison method with a standard polystyrene sample, after sorting the polymer based on its molecular size.

[0023] Furthermore, compared to the polystyrene-equivalent molecular weight determined by gel permeation chromatography (GPC), the absolute molecular weight measured by GPC-light scattering measurement with a viscosity detector tends to be able to accurately measure the molecular weight because the molecular size is directly observed by light scattering and the molecular weight (absolute molecular weight) is measured without being affected by the polymer structure or interactions with the column packing material, and without being affected by the polymer structure such as the branched structure of the conjugated diene polymer. However, it is easily affected by the detection method of the light scattering detector, and although it is effective for relative comparison under specific measurement conditions, it is difficult to identify the true structure of the conjugated diene polymer.

[0024] On the other hand, Mooney viscosity is an index showing the overall characteristics of a conjugated diene polymer, including information on the molecular weight, molecular weight distribution, degree of branching, and softener content of the conjugated diene polymer. The method for measuring Mooney viscosity is specified in ISO 289, and the measurement error due to instrumental differences is small, making it extremely effective in controlling the performance of conjugated diene polymers.

[0025] As described above, while viscosity is generally regarded as an index that can substitute for molecular weight, it is difficult to accurately determine molecular weight in certain cases, and therefore Mooney viscosity is set as one of the requirements for the conjugated diene polymer of this embodiment. More specifically, the conjugated diene polymer of this embodiment has a Mooney viscosity (hereinafter simply referred to as "Mooney viscosity" or "ML") measured at 100°C of 30 to 120. However, in the region near the lower limit, simply lowering the molecular weight to adjust the ML or adding a softener (oil, etc.) to adjust the ML tends to impair the abrasion resistance and breaking strength of the vulcanized product.

[0026] That is, in order to obtain a conjugated diene-based polymer exhibiting the desired performance, it is necessary not only to control the molecular weight or the Mooney viscosity, but also to set the degree of branching within a specific range (which can be controlled by adjusting the type and amount of branching agent and the type and amount of modifier) ​​from the viewpoint of increasing the rigidity when the polymer is prepared into a composition. By combining these factors, the abrasion resistance and breaking strength of the vulcanized product can be improved without impairing the processability when the polymer is prepared into a composition.

[0027] The conjugated diene polymer of the present embodiment has a Mooney viscosity measured at 100°C of 30 or more and 120 or less, preferably 35 or more and 100 or less, and more preferably 40 or more and 90 or less, from the viewpoints of the productivity of the conjugated diene polymer, the processability when the polymer is made into a composition containing a filler or the like, and the abrasion resistance and breaking strength when the composition is made into a vulcanizate.

[0028] When the Mooney viscosity measured at 100°C is 30 or more, the abrasion resistance and breaking strength of the vulcanized product are improved, and when the Mooney viscosity measured at 100°C is 120 or less, problems in the production of the conjugated diene polymer are suppressed, and the processability is improved when the polymer is made into a composition containing a filler or the like.

[0029] The Mooney viscosity is measured by using a conjugated diene polymer as a plate-shaped sample formed by a pressure press, setting the sample in the apparatus, preheating the sample to 100°C for 1 minute, then rotating the rotor at 2 rpm, measuring the torque after 4 minutes, and taking the measured value as the Mooney viscosity (ML(1+4)). More specifically, it can be measured by the method described in the Examples below. The Mooney viscosity of the conjugated diene polymer can be controlled within the above range, for example, by controlling the temperature and other conditions in the polymerization step or adjusting the degree of branching in the branching step. More specifically, this will be described in the method for producing a modified conjugated diene polymer described below.

[0030] (microstructure) The conjugated diene polymer of this embodiment has a microstructure in which the amount of 1,2 vinyl bonds is specified to be 25 mol % or less and the amount of 1,4 cis bonds is specified to be 40 mol % or less.

[0031] The microstructure of the conjugated diene polymer can be measured using a Fourier transform infrared spectrophotometer by the method described in the examples below.

[0032] The 1,2 vinyl bond content of the conjugated diene polymer of this embodiment is 25 mol % or less, preferably 23 mol % or less, more preferably 22 mol % or less, and even more preferably 20 mol % or less. The lower limit of the 1,2-vinyl bond content is not particularly limited, but is preferably 7 mol % or more, more preferably 10 mol % or more, and even more preferably 12 mol % or more.

[0033] The amount of 1,2 vinyl bonds can be controlled within the above-mentioned specific range by adjusting the amount of polar substance added in the polymerization step. While increasing the amount of polar compound added not only increases the amount of 1,2 vinyl bonds but also has the effect of accelerating the polymerization reaction, when a composition containing a filler or the like is formed, the breaking strength and abrasion resistance tend to deteriorate, and it is therefore necessary to adjust the amount of polar substance added to control the amount of 1,2 vinyl bonds within a specific range. More specific details will be described in the Examples below.

[0034] The 1,4 cis bond content of the conjugated diene polymer of this embodiment is 40 mol % or less, preferably 38 mol % or less, and more preferably 36 mol % or less.

[0035] The 1,4-cis bond content within the above-mentioned specific range can be achieved by carrying out polymerization by living anionic polymerization using an organic alkali metal or organic alkaline earth metal as a polymerization initiator. This makes it possible to obtain a conjugated diene polymer having an active terminal, and then, in the branching step using a branching agent described below, the branched structure can be appropriately controlled. Furthermore, the addition of a nitrogen-containing modifier described below tends to make it easier to obtain a conjugated diene polymer with a high modification rate, and when a composition containing a filler or the like is formed, a composition with a better balance between low hysteresis loss and wet skid resistance tends to be obtained.

[0036] (Branching degree (Bn)) The conjugated diene polymer of this embodiment has a branching degree (Bn) of 4 or more and 25 or less, as measured by a GPC-light scattering method with a viscosity detector, from the viewpoints of processability, abrasion resistance, and breaking strength.

[0037] The degree of branching (Bn) of 4 or more means that the conjugated diene polymer of the present embodiment has substantially four or more polymer chains with a branched structure relative to the longest polymer main chain.

[0038] The branching degree (Bn) of a conjugated diene polymer is defined as g'=6Bn / {(Bn+1)(Bn+2)}, where g' is the shrinkage factor measured by GPC-light scattering method with a viscosity detector.

[0039] In general, a polymer having branches tends to have a smaller molecular size compared to a linear polymer having the same absolute molecular weight.

[0040] The shrinkage factor (g') is a measure of the ratio of the molecular size to that of a linear polymer of the same assumed absolute molecular weight. In other words, the greater the degree of branching of a polymer, the smaller the shrinkage factor (g') tends to be.

[0041] In this embodiment, the intrinsic viscosity is used as an index of molecular size for this shrinkage factor. For linear polymers, the intrinsic viscosity [η] is -3.883M 0.771 In the above formula, M is the absolute molecular weight.

[0042] However, the shrinkage factor represents the rate of decrease in molecular size and does not accurately represent the branched structure of the polymer.

[0043] Therefore, the degree of branching (Bn) of the conjugated diene polymer is calculated using the value of the shrinkage factor (g') at each absolute molecular weight of the conjugated diene polymer. The calculated "degree of branching (Bn)" accurately represents the number of polymers that are directly or indirectly bonded to each other with respect to the longest main chain structure.

[0044] The calculated branching degree (Bn) is an index that expresses the branching structure of a conjugated diene polymer. For example, in the case of a typical four-branched star polymer (four polymer chains connected to the center), two polymer chain arms are connected to the longest highly branched main chain structure, and the branching degree (Bn) is evaluated as 2.

[0045] In the case of a typical six-branched star polymer, four polymer chain arms are attached to the longest highly branched main chain structure, and the branching degree (Bn) is evaluated as 4.

[0046] The conjugated diene polymer of the present embodiment has a degree of branching (Bn) of 4 or more and 25 or less, which means that the conjugated diene polymer is a modified conjugated diene polymer having a star polymer structure with 6 or more branches and 27 or less branches similar to the star polymer structure.

[0047] Here, "branch" refers to a structure formed by direct or indirect bonding of one polymer to another polymer, and "degree of branching (Bn)" refers to the number of polymers that are directly or indirectly bonded to each other in the longest main chain structure.

[0048] The conjugated diene-based polymer of the present embodiment, having a branching degree (Bn) of 4 or more and 25 or less, suppresses the cold flow of bales, which are the product form of the conjugated diene copolymer, and has extremely excellent processability when vulcanized, and when vulcanized, has excellent abrasion resistance and breaking strength.

[0049] Generally, an increase in absolute molecular weight tends to worsen processability. When the absolute molecular weight is increased in a linear polymer structure, the viscosity increases significantly when the polymer is vulcanized, significantly worsening processability.

[0050] Therefore, even if a large number of functional groups are introduced into the polymer to improve the affinity and / or reactivity with the silica blended as a filler, the silica cannot be sufficiently dispersed in the polymer during the kneading process, and as a result, the functions of the introduced functional groups are not exerted, and the effect of improving the balance between low hysteresis loss and wet skid resistance that should be expected from the introduction of functional groups is not exerted.

[0051] On the other hand, since the conjugated diene polymer of this embodiment has a branching degree (Bn) of 4 or more and 25 or less, an increase in viscosity when vulcanized due to an increase in absolute molecular weight is significantly suppressed, and therefore, for example, the conjugated diene polymer can be sufficiently mixed with silica or the like in a kneading step, and silica can be dispersed around the conjugated diene polymer. As a result, for example, by setting the molecular weight of the conjugated diene polymer to be large, it is possible to improve abrasion resistance and fracture strength, and by sufficiently kneading, silica can be dispersed around the polymer, allowing functional groups to act and / or react, thereby enabling the conjugated diene polymer to have low hysteresis loss and wet skid resistance that are sufficient for practical use.

[0052] The degree of branching (Bn) of the conjugated diene polymer of the present embodiment is 4 or more and 25 or less, preferably 5 or more and 23 or less, more preferably 6 or more and 20 or less, and even more preferably 7 or more and 18 or less. A conjugated diene polymer having a degree of branching (Bn) within this range tends to have excellent processability when vulcanized, and tends to have excellent abrasion resistance when vulcanized.

[0053] The degree of branching of the conjugated diene polymer can be controlled to 4 or more and 25 or less by combining the amount of branching agent and the amount of terminal modifier added. Specifically, the degree of branching can be controlled by the number of functional groups of the branching agent, the amount of branching agent added, the timing of adding the branching agent, and the number of functional groups and the amount of nitrogen-containing modifier added. More specifically, this will be described later in relation to the method for producing a conjugated diene polymer.

[0054] (Degree of branching in the polymer region (Bn)) The conjugated diene polymer of this embodiment preferably has a branching degree (Bn) of 7 or more for a polymer having the highest absolute molecular weight among at least two absolute molecular weights when the height of the peak top in the absolute molecular weight curve measured by GPC-light scattering measurement method with a viscosity detector (wherein, when there are multiple peak tops in the absolute molecular weight curve, the height of the peak top with the largest absolute molecular weight) Hi (hereinafter also referred to as a "1 / 2Hi polymer") is half the height Hi in the absolute molecular weight curve. That is, a branching degree (Bn) of 7 or more for a 1 / 2Hi polymer means that the degree of branching in the high molecular weight region is higher than the average branching degree (Bn) of the entire polymer chain described above, and the polymer has a branching degree distribution. In the above absolute molecular weight curve, at least two 1 / 2Hi exist on the lower and higher molecular weight sides of the peak top. However, "a polymer having the highest absolute molecular weight among at least two absolute molecular weights at a height (1 / 2Hi) that is half the peak top height Hi" refers to a polymer whose absolute molecular weight is 1 / 2Hi on the higher molecular weight side when two 1 / 2Hi exist on the lower and higher molecular weight sides of the peak top. Furthermore, when there are multiple peak tops and multiple 1 / 2Hi on the higher molecular weight side of the peak top, it refers to a polymer whose absolute molecular weight is 1 / 2Hi, the highest.

[0055] FIG. 1 is an image diagram showing an example of the relationship between the absolute molecular weight curve and the branching degree distribution, as determined by the GPC-light scattering measurement method with a viscosity detector. In general, in the case of a simple star-shaped conjugated diene polymer that has been subjected to a coupling reaction with a coupling agent or a coupling agent having a nitrogen atom-containing group at one active end of the conjugated diene polymer, the degree of branching (Bn) in the region higher in molecular weight than the molecular weight of the 1 / 2Hi polymer (hereinafter also referred to as the "high molecular weight region") changes slightly due to the condensation reaction of some of the coupling agent residues, as shown in Figure 1, but basically the degree of branching (Bn) in the high molecular weight region tends to be constant depending on the functionality of the coupling agent. On the other hand, in the case of the conjugated diene polymer of this embodiment in which the branching degree (Bn) of the 1 / 2Hi polymer is 7 or more, the branching degree distribution of the main-chain branched polymer is higher as the molecular weight becomes higher than the average for the entire polymer, as shown in Figure 1. That is, although the branching degree (Bn) in the high molecular weight region can be increased to some extent by introducing a star structure by coupling at the polymerization terminal, the conjugated diene polymer of this embodiment in which the branching degree (Bn) of the 1 / 2Hi polymer is 7 or more is more likely to undergo a uniform condensation reaction and less likely to fluctuate in the Mooney viscosity even after polymerization, which is preferable in terms of quality control of the resulting conjugated diene polymer, compared to a method of controlling the branching degree (Bn) in the high molecular weight region by condensation of coupling agent residues.

[0056] The conjugated diene polymer of this embodiment is preferably a conjugated diene polymer having a preferred branching distribution in which the branching degree (Bn) of the 1 / 2Hi polymer is 7 or more, specifically, for example, a conjugated diene polymer in which each polymer chain constituting a star structure is further branched. A conjugated diene polymer having such a preferred branching distribution can be obtained, for example, by, but not limited to, the following method. A branched structure is first introduced into a portion of a polymer chain having an active terminal, and then a coupling reaction is carried out with a coupling agent (preferably having a nitrogen atom-containing group). This results in a conjugated diene polymer having a branching degree (Bn) in the high molecular weight region that is higher than the functionality of the coupling agent and a broader branching distribution on the higher molecular weight side than the peak top of the molecular weight distribution.

[0057] A conjugated diene polymer having a high degree of branching (Bn) in the high molecular weight region means, for example, that the proportion of conjugated diene polymers having a branched structure in the main chain in the high molecular weight region is high, and that the coupling efficiency by a coupling agent is high.

[0058] The branching degree (Bn) of the 1 / 2Hi polymer and the branching degree (Bn) of the polymer in the high molecular weight region can be controlled by the number of functional groups of the branching agent, the amount of branching agent added, the timing of adding the branching agent, and the number of functional groups of the coupling agent or nitrogen-containing modifier and the amount of coupling agent or nitrogen-containing modifier added. Regarding the conjugated diene polymer of this embodiment, the height of the peak top Hi in an absolute molecular weight curve measured by GPC-light scattering measurement with a viscosity detector (however, if there are multiple peak tops in the absolute molecular weight curve, the height of the peak top with the highest absolute molecular weight) is used as the reference. When the height of the absolute molecular weight curve is half the height of Hi (1 / 2Hi), the branching degree (Bn) of the polymer with the highest absolute molecular weight among at least two absolute molecular weights is preferably 7 or more, more preferably 8 or more, even more preferably 10 or more, and even more preferably 12 or more. Regarding the conjugated diene polymer of this embodiment, the upper limit of the branching degree (Bn) of the 1 / 2Hi polymer is not particularly limited, but is, for example, 50 or less.

[0059] In this embodiment, the branching degree (Bn) of the 1 / 2Hi polymer can be measured by the method described in the examples below.

[0060] Conjugated diene polymers with a preferred structure and a branching distribution in which the branching degree (Bn) is 4 or greater and the branching degree (Bn) of the 1 / 2Hi polymer is 7 or greater tend to have low melt viscosity and are extremely easy to process when compounding with silica or other additives in high-temperature, high-shear kneading processes. Generally, polymers with many branches tend to exhibit a greater decrease in viscosity in the high-shear region than linear polymers at the same molecular weight, making them easier to knead (good processability). This is thought to be due to the small molecular weight per single chain of the base polymer, even at high molecular weights. By increasing the branching degree (Bn) of the 1 / 2Hi polymer in the high-molecular-weight region, such as 7 or greater, the effects of shortening the length of each base polymer are more pronounced. Although increasing the molecular weight is preferable to improve abrasion resistance and breaking strength, the high viscosity of the polymer, which makes it difficult to mix with fillers, tends to be a constraint on designing a high molecular weight, but as mentioned above, the degree of branching (Bn) of the 1 / 2Hi polymer is 7 or more, and the high degree of branching in the high molecular weight region provides good processability, which increases the room for increasing the molecular weight. That is, a conjugated diene-based polymer having a degree of branching (Bn) of 1 / 2Hi polymer of 7 or more and a high degree of branching in the high molecular weight region has good processability when obtaining a compound, making it possible to design a conjugated diene-based polymer with a high molecular weight, and when vulcanized, it tends to be easy to obtain a conjugated diene-based polymer with excellent abrasion resistance and breaking properties.

[0061] (Nitrogen-containing conjugated diene polymer) The conjugated diene polymer of this embodiment contains a nitrogen atom in the polymer chain. The nitrogen-containing conjugated diene polymer has an excellent balance between low hysteresis loss and wet skid resistance. Such a conjugated diene polymer can be obtained, for example, by a modification reaction using a modifier having a nitrogen atom-containing group described below.

[0062] From the viewpoint of making the conjugated diene polymer obtained through the polymerization and branching steps more highly branched, the modifier is more preferably a reactive compound having a nitrogen atom-containing group with two or more functionalities at the active terminal of the conjugated diene polymer (hereinafter also referred to as a "modifier having a nitrogen atom-containing group").

[0063] In the modification step described below, one active end of the conjugated diene polymer is subjected to a modification reaction with a modifying agent having a nitrogen atom-containing group to obtain a conjugated diene polymer.

[0064] The modified conjugated diene polymer modified with a modifier having a nitrogen atom-containing group tends to have good silica dispersibility when mixed with a filler or the like, and the processability of the composition mixed with the filler or the like is good, and when the composition is vulcanized, the abrasion resistance and breaking strength are good, and the balance between low hysteresis loss and wet skid resistance is dramatically improved. More specific details will be described later in the method for producing the conjugated diene polymer.

[0065] The modifying agent having a nitrogen atom-containing group is not particularly limited, but examples thereof include isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, nitrogen group-containing carbonyl compounds, nitrogen group-containing vinyl compounds, and nitrogen group-containing epoxy compounds.

[0066] The nitrogen atom-containing functional group of the modifying agent is preferably an amine compound having no active hydrogen, and examples thereof include tertiary amine compounds, protected amine compounds in which the active hydrogen is substituted with a protecting group, imine compounds represented by the general formula -N=C, and alkoxysilane compounds bonded to the nitrogen atom-containing group. More specific examples are described in the method for producing a conjugated diene polymer below.

[0067] The conjugated diene polymer of this embodiment has a number average molecular weight and a weight average molecular weight (hereinafter simply referred to as "number average molecular weight" and "weight average molecular weight") that are determined as polystyrene-equivalent molecular weights by gel permeation chromatography (hereinafter also referred to as "GPC"), which is a relative comparison method with a standard polystyrene sample. 4 g / mol or more 100×10 4 g / mol or less, and preferably 10 × 10 4 g / mol or more 50×10 4 g / mol or less is more preferable, and 20×10 4 g / mol or more 35×10 4 It is more preferable that the weight average molecular weight is 10×10 g / mol or less. 4 g / mol or more 200×10 4 g / mol or less is preferable, and 20×10 4 g / mol or more 125×10 4 g / mol or less is more preferable, and 30×10 4 g / mol or more 75×10 4 It is more preferably g / mol or less.

[0068] The conjugated diene polymer of this embodiment preferably has a molecular weight distribution (Mw / Mn), expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), of 1.60 to 2.30. A conjugated diene polymer with a molecular weight distribution in this range tends to exhibit excellent abrasion resistance and breaking strength when vulcanized with a filler or the like. The molecular weight distribution is more preferably 1.65 to 2.20, even more preferably 1.70 to 2.00, and even more preferably 1.75 to 1.95.

[0069] The number average molecular weight, weight average molecular weight, and molecular weight distribution of the conjugated diene polymer can be measured by the method described in the Examples below. The number average molecular weight, weight average molecular weight, and molecular weight distribution of the conjugated diene polymer can be controlled within the above ranges, for example, by controlling conditions such as temperature in the polymerization step or by adjusting the branching degree in the branching step. More specific details will be described in the method for producing a modified conjugated diene polymer described below.

[0070] (denaturation rate) In this specification, the "modification ratio" represents the mass ratio of a conjugated diene polymer having a nitrogen atom-containing functional group to the total amount of a conjugated diene polymer.

[0071] For example, when a nitrogen atom-containing modifier is reacted at the terminal end, the mass ratio of the conjugated diene polymer having a nitrogen atom-containing functional group due to the nitrogen atom-containing modifier to the total amount of the conjugated diene polymer is expressed as the modification rate.

[0072] On the other hand, when a polymer is branched using a branching agent containing a nitrogen atom, the resulting conjugated diene polymer will have a nitrogen atom-containing functional group, and therefore this branched polymer will also be counted when calculating the modification rate.

[0073] That is, in this specification, the total mass ratio of a coupling polymer formed by a modifying agent having a nitrogen atom-containing functional group and / or a branched polymer formed by a branching agent having a nitrogen atom-containing functional group is referred to as the "modification rate."

[0074] By modifying at least one end of the conjugated diene polymer of the present embodiment with a nitrogen atom-containing group, the balance between low hysteresis loss and wet skid resistance tends to be dramatically improved while maintaining the processability when the polymer is made into a composition containing a filler or the like, and the abrasion resistance and breaking strength when the composition is made into a vulcanizate.

[0075] From the viewpoint of processability, abrasion resistance, breaking strength, and a balance between low hysteresis loss and wet skid resistance, the conjugated diene polymer of the present embodiment preferably has a modification rate measured by a column adsorption GPC method (hereinafter also simply referred to as "modification rate") of 60 mass% or more relative to the total amount of the conjugated diene polymer.

[0076] The modification rate is more preferably 65% ​​by mass or more, even more preferably 70% by mass or more, still more preferably 75% by mass or more, and even more preferably 80% by mass or more. The upper limit of the modification rate is not particularly limited, but is, for example, 98% by mass.

[0077] By setting the modification rate to 60% by mass or more, the processability when vulcanized tends to be excellent, and the abrasion resistance and low hysteresis loss performance when vulcanized tends to be even better.

[0078] The degree of modification can be measured by chromatography, which can separate functional group-containing modified components from unmodified components.

[0079] Examples of methods using this type of chromatography include a method in which a gel permeation chromatography column filled with a polar substance such as silica that adsorbs specific functional groups is used, and the non-adsorbed components are quantified using an internal standard for comparison (column adsorption GPC method).

[0080] More specifically, the modification rate can be obtained by measuring the amount of a sample solution containing the sample and a low-molecular-weight internal standard polystyrene adsorbed to the silica column from the difference between a chromatogram measured on a polystyrene gel column and a chromatogram measured on a silica column.

[0081] More specifically, the modification rate can be measured by the method described in the Examples.

[0082] In the conjugated diene polymer of this embodiment, the modification rate can be controlled by adjusting the amount of modifier added and the reaction method, and can thereby be controlled to 60% by mass or more.

[0083] For example, the above modification rate can be achieved by combining a method of polymerization using an organolithium compound having at least one nitrogen atom in the molecule described below as a polymerization initiator, a method of copolymerizing a monomer having at least one nitrogen atom in the molecule, and a method of using a modifying agent having a structural formula described below, and controlling the polymerization conditions.

[0084] The conjugated diene polymer of the present embodiment preferably has a portion of the polymer chain derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and the portion derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group preferably has a branched structure.

[0085] The branched structure has one or more branching points, preferably three or more branching points, and more preferably four or more branching points, in the portion derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group.

[0086] Furthermore, the branch points forming the branched structure preferably have at least one polymer chain, more preferably have two or more polymer chains that are not the main chain, and even more preferably have four or more polymer chains that are not the main chain.

[0087] In particular, in the case of a branched structure consisting of a vinyl monomer containing an alkoxysilyl group or a halosilyl group, when signal detection is performed by 29Si-NMR, peaks derived from the branched structure are detected in the range of -45 ppm to -65 ppm, and more specifically in the range of -50 ppm to -60 ppm.

[0088] In a preferred aspect of the conjugated diene polymer of this embodiment, the terminal of the polymer chain is modified with a nitrogen-containing modifying agent, and a portion of the polymer chain has a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group. The method for obtaining a modified conjugated diene polymerization having a further branched structure in the moiety derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group can be achieved by adjusting the number of functional groups of the nitrogen-containing modifying agent and the amount added. The branched structure can be controlled by adjusting the number of functional groups of the branching agent, the amount added of the branching agent, and the timing of addition of the branching agent. That is, in this specification, the "moiety derived from a vinyl monomer" refers to a structure in which the alkoxy group and / or halogen of the vinyl monomer, which is the branching agent described below, serves as a leaving group to substitute the polymerization active terminal, and the polymer chain is bonded to the silicon of the vinylsilane, and the vinyl group of the vinylsilane is polymerized as an aromatic vinyl compound. When a vinyl monomer containing multiple alkoxy groups and / or halogens is used as a branching agent, the resulting "portion derived from the vinyl monomer" may have multiple polymer chains bonded to the silicon of the vinylsilane.

[0089] In order to obtain a conjugated diene polymerization having a portion derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group in a part of the polymer chain, and having a further branched structure in the portion derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group, for example, there can be mentioned a method in which polymerization is carried out using an organolithium compound as a polymerization initiator, a branching agent that imparts a specific branching point is added during or after the polymerization, and after the polymerization is continued, modification is carried out using a modifying agent that imparts a specific branching rate.

[0090] Such means for controlling the polymerization conditions will be described in the production method in the examples below.

[0091] In the conjugated diene polymer of the present embodiment, the moiety derived from the vinyl monomer containing the above-mentioned alkoxysilyl group or halosilyl group is preferably a monomer unit derived from a compound represented by the following formula (1) or (2), and the polymer chain preferably has a branching point due to the monomer unit derived from the compound represented by the following formula (1) or (2). The conjugated diene polymer is more preferably a conjugated diene polymer obtained using a branching agent described below, and even more preferably a modified conjugated diene polymer in which at least one end of the conjugated diene polymer is modified with a nitrogen atom-containing group. [ka] In the formula, R 1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may have a branched structure in part, or an aryl group having 6 to 20 carbon atoms, R 2 ~R 3 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, which may have a branched structure in part, When there are a plurality of R1 to R3, they are independent of each other. X 1 indicates an independent halogen atom, m represents an integer of 0 to 2, n represents an integer of 0 to 3, l represents an integer of 0 to 3, and (m+n+l) is 3. [ka] In the formula, R 2 ~R 5 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, which may have a branched structure in part, and when there are a plurality of R 2 ~R 5 are independent of each other, X 2 ~X 3 each represents an independent halogen atom, m represents an integer of 0 to 2, n represents an integer of 0 to 3, l represents an integer of 0 to 3, and (m+n+l) is 3; a represents an integer of 0 to 2, b represents an integer of 0 to 3, c represents an integer of 0 to 3, and (a+b+c) is 3.

[0092] The conjugated diene polymer of the present embodiment has a monomer unit derived from the compound represented by the above formula (1), and in formula (1), R 1 It is preferred that m represents a hydrogen atom and m represents 0. This increases the number of branches, suppresses cold flow of bales, which are the product form of the conjugated diene polymer, and provides excellent processability when vulcanized, resulting in excellent abrasion resistance and breaking strength when vulcanized.

[0093] The conjugated diene polymer of the present embodiment has a monomer unit derived from the compound represented by the above formula (2), and in formula (2), it is preferable that m represents 0 and b represents 0. This provides an effect of improving abrasion resistance and processability.

[0094] The conjugated diene polymer of the present embodiment has a monomer unit derived from a compound represented by the above formula (2), and in formula (2), it is preferable that m represents 0, n represents 3, l represents 0, a represents 0, b represents 0, and c represents 3. This suppresses cold flow of bales, which are the finished product form of the conjugated diene polymer, and also provides the effects of improving abrasion resistance and processability.

[0095] The conjugated diene polymer of the present embodiment has a monomer unit derived from the compound represented by the above formula (1), and in formula (1), R 1 It is more preferable that represents a hydrogen atom, m represents 0, n represents 3, and 1 represents 0. This improves the modification rate and the degree of branching, suppresses cold flow in bales that are the product form of the conjugated diene polymer, and also provides the effects of improving fuel-saving performance, abrasion resistance, and processability.

[0096] [Method for producing conjugated diene polymer] The method for producing a conjugated diene polymer of the present embodiment is a method for producing the above-mentioned conjugated diene polymer, and includes a polymerization and branching step of polymerizing a conjugated diene compound using an organolithium compound as a polymerization initiator while adding a branching agent to produce a conjugated diene polymer having a branched structure, and a modification step of modifying the conjugated diene polymer with a modifying agent.

[0097] (Polymerization and branching process) The polymerization and branching step in the method for producing a conjugated diene polymer of this embodiment (hereinafter also simply referred to as the "polymerization and branching step") is a step in which, for example, an organic monolithium compound is used as a polymerization initiator to polymerize at least one conjugated diene compound, and a branching agent is added to obtain a conjugated diene polymer having a branched structure. Hereinafter, the polymerization reaction in the polymerization and branching step will be described as the "polymerization step," and the reaction with the branching agent will be described as the "branching step."

[0098] In the polymerization step, it is preferable to carry out polymerization by a propagation reaction through a living anionic polymerization reaction, which can produce a conjugated diene polymer having an active terminal. In the subsequent branching step using a branching agent, main chain branching can be appropriately controlled, and a conjugated diene polymer with a high modification rate can be obtained.

[0099] The conjugated diene polymer may be a homopolymer obtained using a single conjugated diene compound as a monomer, or a polymer obtained using different types of conjugated diene compounds as monomers, that is, a copolymer.

[0100] Specific examples of the conjugated diene compound 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 compounds may be used alone or in combination of two or more.

[0101] In the conjugated diene polymer of this embodiment, the Mooney viscosity and degree of branching are mainly controlled by the amount of polymerization initiator added, the type (functionality) and amount of branching agent added, and the type (functionality) and amount of modifier having a nitrogen atom-containing group added, and the influence of the microstructure is relatively small. Therefore, it can be appropriately designed within the range of a typical microstructure. However, since the amount of 1,4 cis bonds and the amount of 1,2 vinyl bonds affect the Tg of the conjugated diene polymer, it is preferable to set them within the above ranges from the viewpoint of fuel economy performance and braking performance.

[0102] Regarding the microstructure of the conjugated diene polymer of this embodiment, when the bond amounts in the conjugated diene polymer are within the above-described ranges and the glass transition temperature of the conjugated diene polymer is within the range of −110° C. or higher and −80° C. or lower, a vulcanizate excellent in breaking strength and abrasion resistance tends to be obtained. Regarding the glass transition temperature, a DSC curve is recorded while increasing the temperature within a predetermined temperature range in accordance with ISO 22768:2006, and the peak top (inflection point) of the DSC differential curve is taken as the glass transition temperature.

[0103] <Polymerization initiator> As the polymerization initiator, at least an organic monolithium compound can be used. The organic monolithium compound is not particularly limited, but examples thereof include low molecular weight compounds and solubilized oligomeric organic monolithium compounds. Furthermore, examples of the organic monolithium compound include compounds having a carbon-lithium bond, compounds having a nitrogen-lithium bond, and compounds 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 the polymerization initiator is preferably determined depending on the molecular weight of the target conjugated diene polymer. The amount of a monomer such as a conjugated diene compound used relative to the amount of a polymerization initiator used is related to the degree of polymerization, that is, tends to be related to the number average molecular weight and / or weight average molecular weight. Therefore, in order to increase the molecular weight, it is advisable to adjust the amount of polymerization initiator used in a direction to decrease it, and in order to decrease the molecular weight, it is advisable to adjust the amount of polymerization initiator used in a direction to increase it.

[0104] The organomonolithium compound is preferably an alkyllithium compound having a substituted amino group or a dialkylaminolithium compound, from the viewpoint that it can be used as one method for introducing nitrogen atoms into a conjugated diene polymer.

[0105] In this case, a conjugated diene polymer having a nitrogen atom consisting of an amino group at the polymerization initiation terminal is obtained.

[0106] The substituted amino group is an amino group that does not have an active hydrogen or has a structure in which the active hydrogen is protected.

[0107] The alkyllithium compound having an amino group without active hydrogen is not particularly limited, but examples thereof include 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium.

[0108] The alkyllithium compound having an amino group with a structure in which an active hydrogen is protected is not particularly limited, but examples thereof include 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0109] The dialkylaminolithium is not particularly limited, but examples thereof include lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium di-n-hexylamide, lithium diheptylamide, lithium diisopropylamide, lithium dioctylamide, lithium-di-2-ethylhexylamide, lithium didecylamide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, lithium methylphenethylamide, lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithio-1,2,3,6-tetrahydropyridine.

[0110] These organomonolithium compounds having a substituted amino group can also be used as solubilized oligomeric organomonolithium compounds by reacting them with a small amount of a polymerizable monomer, such as 1,3-butadiene, isoprene, or styrene.

[0111] The organic monolithium compound is preferably an alkyllithium compound from the viewpoints of industrial availability and ease of control of the polymerization reaction, in which case a conjugated diene polymer having an alkyl group at the polymerization initiation terminal can be obtained.

[0112] Examples of alkyllithium compounds include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium.

[0113] As the alkyllithium compound, n-butyllithium and sec-butyllithium are preferred from the viewpoints of industrial availability and ease of control of the polymerization reaction.

[0114] These organomonolithium compounds may be used alone or in combination of two or more, or may be used in combination with other organometallic compounds.

[0115] Examples of other organometallic compounds include alkaline earth metal compounds, other alkali metal compounds, and other organometallic compounds.

[0116] Examples of alkaline earth metal compounds include, but are not limited to, organomagnesium compounds, organocalcium compounds, and organostrontium compounds, as well as alkaline earth metal alkoxides, sulfonates, carbonates, and amides.

[0117] Examples of organomagnesium compounds include dibutylmagnesium and ethylbutylmagnesium. Examples of other organometallic compounds include organoaluminum compounds.

[0118] In the polymerization step, the polymerization reaction mode is not particularly limited, but examples thereof include a batchwise polymerization mode (also called a "batch type") and a continuous polymerization mode.

[0119] In the continuous system, one or more connected reactors can be used. The continuous reactor may be, for example, a tank-type or tubular reactor equipped with a stirrer. In the continuous system, preferably, the monomer, the inert solvent, and the polymerization initiator are continuously fed into the reactor, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is continuously discharged.

[0120] The batch reactor may be, for example, a tank-type reactor equipped with a stirrer. In the batch reactor, preferably, a monomer, an inert solvent, and a polymerization initiator are fed, and if necessary, a monomer is added continuously or intermittently during polymerization to obtain a polymer solution in the reactor, which is then discharged after the polymerization is completed.

[0121] In the method for producing a conjugated diene polymer of the present embodiment, in order to obtain a conjugated diene polymer having active ends at a high rate, a continuous method is preferred, which allows the polymer to be continuously discharged and subjected to the next reaction in a short time.

[0122] The polymerization step of the conjugated diene polymer is preferably carried out in an inert solvent. The solvent is not particularly limited, but examples thereof include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific hydrocarbon solvents are not particularly limited, but examples thereof include aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; and hydrocarbons consisting of mixtures thereof.

[0123] By treating the impurities, that is, allenes and acetylenes, with an organometallic compound before subjecting the polymer to the polymerization reaction, a conjugated diene-based polymer having a high concentration of active ends tends to be obtained, and a modified conjugated diene-based polymer with a high modification rate tends to be obtained, which is preferable.

[0124] In the polymerization step, a polar compound may be added. It tends to be used as a vinylating agent to control the amount of 1,2-vinyl bonds in the conjugated diene polymer. It also tends to be effective in accelerating the polymerization reaction.

[0125] The polar compound is not particularly limited, but examples thereof include ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butylate, sodium tert-butylate, and sodium amylate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used alone or in combination of two or more.

[0126] The amount of polar compound used is not particularly limited and can be selected depending on the purpose, but is preferably 0.01 mol or more and 100 mol or less per mol of the polymerization initiator. Such polar compounds (vinylating agents) can be used as modifiers for the microstructure of the conjugated diene polymer in an appropriate amount depending on the desired amount of 1,2 vinyl bonds.

[0127] The polymerization temperature in the polymerization step is preferably a temperature at which living anionic polymerization proceeds, and from the viewpoint of productivity, is more preferably 0°C or higher, and even more preferably 120°C or lower. By keeping the temperature in this range, it tends to be possible to ensure a sufficient amount of modifying agent reacting with the active terminals after the polymerization is completed. Even more preferably, it is 50°C or higher and 100°C or lower.

[0128] (branching agent) In the conjugated diene polymer of the present embodiment, a branching agent represented by the following formula (1) or (2) is used as a branching agent when constructing a branched structure. [ka] In the formula, R 1represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may have a branched structure in part, or an aryl group having 6 to 20 carbon atoms, R 2 ~R 3 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, which may have a branched structure in part, When there are a plurality of R1 to R3, they are independent of each other. X 1 indicates an independent halogen atom, m represents an integer of 0 to 2, n represents an integer of 0 to 3, l represents an integer of 0 to 3, and (m+n+l) is 3. [ka] In the formula, R 2 ~R 5 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, which may have a branched structure in part, and when there are a plurality of R 2 ~R 5 are independent of each other, X 2 ~X 3 each represents an independent halogen atom, m represents an integer of 0 to 2, n represents an integer of 0 to 3, l represents an integer of 0 to 3, and (m+n+l) is 3; a represents an integer of 0 to 2, b represents an integer of 0 to 3, c represents an integer of 0 to 3, and (a+b+c) is 3.

[0129] The branching agent represented by formula (1) is not particularly limited, but examples thereof include trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane, trimethoxy(3-vinylphenyl)silane, triethoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)silane, tributoxy(3-vinylphenyl)silane, triisopropoxy(3-vinylphenyl)silane, Trimethoxy(2-vinylphenyl)silane, triethoxy(2-vinylphenyl)silane, tripropoxy(2-vinylphenyl)silane, tributoxy(2-vinylphenyl)silane, triisopropoxy(2-vinylphenyl)silane, dimethoxymethyl(4-vinylphenyl)silane, diethoxymethyl(4-vinylphenyl)silane, dipropoxymethyl(4-vinylphenyl)silane, dibutoxymethyl(4-vinylphenyl)silane, diisopropoxymethyl(4-vinylphenyl)silane, dimethoxymethyl(3-vinylphenyl)silane , diethoxymethyl(3-vinylphenyl)silane, dipropoxymethyl(3-vinylphenyl)silane, dibutoxymethyl(3-vinylphenyl)silane, diisopropoxymethyl(3-vinylphenyl)silane, dimethoxymethyl(2-vinylphenyl)silane, diethoxymethyl(2-vinylphenyl)silane, dipropoxymethyl(2-vinylphenyl)silane, dibutoxymethyl(2-vinylphenyl)silane, diisopropoxymethyl(2-vinylphenyl)silane, dimethylmethoxy(4-vinylphenyl)silane, dimethylethoxy(4- (vinylphenyl)silane, dimethylpropoxy(4-vinylphenyl)silane, dimethylbutoxy(4-vinylphenyl)silane, dimethylisopropoxy(4-vinylphenyl)silane, dimethylmethoxy(3-vinylphenyl)silane, dimethylethoxy(3-vinylphenyl)silane, dimethylpropoxy(3-vinylphenyl)silane, dimethylbutoxy(3-vinylphenyl)silane, dimethylisopropoxy(3-vinylphenyl)silane, dimethylmethoxy(2-vinylphenyl)silane, dimethylethoxy(2-vinylphenyl)silane,Dimethylpropoxy(2-vinylphenyl)silane, dimethylbutoxy(2-vinylphenyl)silane, dimethylisopropoxy(2-vinylphenyl)silane, trimethoxy(4-isopropenylphenyl)silane, triethoxy(4-isopropenylphenyl)silane, tripropoxy(4-isopropenylphenyl)silane, tributoxy(4-isopropenylphenyl)silane, triisopropoxy(4-isopropenylphenyl)silane, trimethoxy(3-isopropenylphenyl)silane, triethoxy(3-isopropenylphenyl) Tripropoxy(3-isopropenylphenyl)silane, Tributoxy(3-isopropenylphenyl)silane, Triisopropoxy(3-isopropenylphenyl)silane, Trimethoxy(2-isopropenylphenyl)silane, Triethoxy(2-isopropenylphenyl)silane, Tripropoxy(2-isopropenylphenyl)silane, Tributoxy(2-isopropenylphenyl)silane, Triisopropoxy(2-isopropenylphenyl)silane, Dimethoxymethyl(4-isopropenylphenyl)silane, Diethoxymethyl Dimethyl(4-isopropenylphenyl)silane, dipropoxymethyl(4-isopropenylphenyl)silane, dibutoxymethyl(4-isopropenylphenyl)silane, diisopropoxymethyl(4-isopropenylphenyl)silane, dimethoxymethyl(3-isopropenylphenyl)silane, diethoxymethyl(3-isopropenylphenyl)silane, dipropoxymethyl(3-isopropenylphenyl)silane, dibutoxymethyl(3-isopropenylphenyl)silane, diisopropoxymethyl(3-isopropenylphenyl)silane, di Methoxymethyl(2-isopropenylphenyl)silane, diethoxymethyl(2-isopropenylphenyl)silane, dipropoxymethyl(2-isopropenylphenyl)silane, dibutoxymethyl(2-isopropenylphenyl)silane, diisopropoxymethyl(2-isopropenylphenyl)silane, dimethylmethoxy(4-isopropenylphenyl)silane, dimethylethoxy(4-isopropenylphenyl)silane, dimethylpropoxy(4-isopropenylphenyl)silane, dimethylbutoxy(4-isopropenylphenyl)silane,Dimethylisopropoxy(4-isopropenylphenyl)silane, dimethylmethoxy(3-isopropenylphenyl)silane, dimethylethoxy(3-isopropenylphenyl)silane, dimethylpropoxy(3-isopropenylphenyl)silane, dimethylbutoxy(3-isopropenylphenyl)silane, dimethylisopropoxy(3-isopropenylphenyl)silane, dimethylmethoxy(2-isopropenylphenyl)silane, dimethylethoxy(2-isopropenylphenyl)silane, dimethylpropoxy(2-isopropenylphenyl)silane, dimethylbutoxy(2-isopropenylphenyl)silane, dimethylisopropoxy(2-isopropenylphenyl)silane, trichloro(4-vinylphenyl)silane, trichloro(3-vinylphenyl)silane, tri Examples of suitable silanes include chloro(2-vinylphenyl)silane, tribromo(4-vinylphenyl)silane, tribromo(3-vinylphenyl)silane, tribromo(2-vinylphenyl)silane, dichloromethyl(4-vinylphenyl)silane, dichloromethyl(3-vinylphenyl)silane, dichloromethyl(2-vinylphenyl)silane, dibromomethyl(4-vinylphenyl)silane, dibromomethyl(3-vinylphenyl)silane, dibromomethyl(2-vinylphenyl)silane, dimethylchloro(4-vinylphenyl)silane, dimethylchloro(3-vinylphenyl)silane, dimethylchloro(2-vinylphenyl)silane, dimethylbromo(4-vinylphenyl)silane, dimethylbromo(3-vinylphenyl)silane, and dimethylbromo(2-vinylphenyl)silane.

[0130] Among these, trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane, trimethoxy(3-vinylphenyl)silane, triethoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)silane, tributoxy(3-vinylphenyl)silane, triisopropoxy(3-vinylphenyl)silane, and trichloro(4-vinylphenyl)silane are preferred, and trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, and tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane are more preferred.

[0131] The branching agent represented by formula (2) is not particularly limited, and examples thereof include 1,1-bis(4-trimethoxysilylphenyl)ethylene, 1,1-bis(4-triethoxysilylphenyl)ethylene, 1,1-bis(4-trippropoxysilylphenyl)ethylene, 1,1-bis(4-tripentoxysilylphenyl)ethylene, 1,1-bis(4-triisopropoxysilylphenyl)ethylene, 1,1-bis(3-trimethoxysilylphenyl)ethylene, 1,1-bis(3-triethoxysilylphenyl)ethylene, 1,1-bis(3-trippropoxysilylphenyl)ethylene, 1,1-bis(3-tripentoxysilylphenyl)ethylene, 1,1-bis(3-triisopropoxysilylphenyl)ethylene, 1,1-bis(2-trimethoxysilylphenyl)ethylene, 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(diethylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(dipropylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(dimethylethoxysilyl)phenyl)ethylene, 1,1-bis(4-(diethylethoxysilyl)phenyl)ethylene, and 1,1-bis(4-(dipropylethoxysilyl)phenyl)ethylene.

[0132] Among these, 1,1-bis(4-trimethoxysilylphenyl)ethylene, 1,1-bis(4-triethoxysilylphenyl)ethylene, 1,1-bis(4-tripropoxysilylphenyl)ethylene, 1,1-bis(4-tripentoxysilylphenyl)ethylene, and 1,1-bis(4-triisopropoxysilylphenyl)ethylene are preferred, and 1,1-bis(4-trimethoxysilylphenyl)ethylene is more preferred.

[0133] In the method for producing a conjugated diene-based polymer of the present embodiment, the amount of branching agent added in the branching step for forming a branched structure is not particularly limited and can be selected depending on the purpose, etc., but is preferably 0.03 mol or more and 0.5 mol or less, more preferably 0.05 mol or more and 0.4 mol or less, and even more preferably 0.01 mol or more and 0.25 mol or less, relative to 1 mol of the polymerization initiator.

[0134] The branching agent can be used in an appropriate amount depending on the desired number of branching points as branching points of the branched structure of the conjugated diene portion of the conjugated diene polymer.

[0135] In the branching step, the timing of adding the branching agent is not particularly limited and can be selected depending on the purpose, etc., but from the viewpoint of improving the absolute molecular weight and the modification rate of the conjugated diene-based polymer, the timing is preferably when the raw material conversion rate after addition of the polymerization initiator is 20% or more, more preferably 40% or more, even more preferably 50% or more, still more preferably 65% ​​or more, and even more preferably 75% or more. After the branching agent is added, the desired raw materials may be further added, and the polymerization step may be continued after branching, or the above-described process may be repeated.

[0136] The monomer to be added is not particularly limited, but from the viewpoint of improving the modification rate of the conjugated diene polymer, it is preferably 5% or more of the total amount of conjugated diene monomers used in the polymerization step, for example, the total amount of butadiene, more preferably 10% or more, even more preferably 15% or more, even more preferably 20% or more, and even more preferably 25% or more and 30% or less.

[0137] When the amount of the added monomer is within the above range, the molecular weight between the branching point of the branching agent and the branching point of the modifier becomes long, and a highly linear molecular structure tends to be easily obtained. The highly linear molecular structure increases the entanglement of molecular chains of the conjugated diene polymer when vulcanized, which tends to suppress cold flow of the bale and make it easier to obtain a rubber composition excellent in abrasion resistance, handling stability, and breaking strength.

[0138] The conjugated diene polymer of this embodiment is not particularly limited and may be a polymer of a conjugated diene monomer and a branching agent, or a copolymer of a conjugated diene monomer, a branching agent, and a monomer other than these. For example, when the conjugated diene monomer is butadiene or isoprene and is polymerized with a branching agent containing a vinyl aromatic moiety, the resulting polymer chain is a so-called polybutadiene or polyisoprene, and the branched portion contains a structure derived from a vinyl aromatic. Having such a structure improves the linearity of each polymer chain and improves the crosslink density after vulcanization, thereby improving abrasion resistance. Therefore, the conjugated diene polymer of this embodiment is suitable for applications such as tires, resin modification, automotive interior and exterior parts, vibration-damping rubber, and footwear.

[0139] When the conjugated diene polymer is used for the tread of a highly loaded tire, a copolymer of a conjugated diene monomer and a branching agent is preferred.

[0140] (Denaturation process) The method for producing a conjugated diene polymer of the present embodiment includes a modification step (hereinafter also simply referred to as the "modification step") of modifying the conjugated diene polymer obtained through the above-described polymerization and branching steps with a modifying agent having a nitrogen-containing group.

[0141] In the modification step, one active end of the conjugated diene polymer is subjected to a modification reaction with a modifying agent having a nitrogen-containing group to obtain a conjugated diene polymer.

[0142] The reaction temperature in the modification step is preferably the same as the polymerization temperature of the conjugated diene polymer, more preferably 0°C or higher and 120°C or lower, and even more preferably 50°C or higher and 100°C or lower.

[0143] The reaction time in the modification step is preferably 10 seconds or more, more preferably 30 seconds or more.

[0144] The mixing in the modification step may be carried out by mechanical stirring, stirring with a static mixer, or the like.

[0145] When the polymerization step is continuous, it is preferred that the modification step is also continuous.

[0146] The reactor used in the modification step may be, for example, a tank type or a tubular type equipped with a stirrer. The modifying agent may be diluted with an inert solvent and continuously fed to the reactor. When the polymerization process is a batch process, the modifying agent may be directly added to the polymerization reactor, or may be transferred to a separate reactor for the modification process.

[0147] The time from the polymerization step to the modification step is preferably short, preferably within 10 minutes, more preferably within 5 minutes, in which case a conjugated diene polymer with high modification efficiency tends to be obtained.

[0148] The time from the polymerization step to the modification step refers to, for example, the time from when the polymerization temperature reaches the peak temperature to when the modifier is added when the polymerization step is a batch process, and refers to the time from when the modifier is added to the solution containing the conjugated diene polymer that has left the polymerization reactor when the polymerization step is a continuous process.

[0149] <Denaturant> The nitrogen atom-containing modifying agent is not particularly limited, but examples thereof include isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, nitrogen atom group-containing carbonyl compounds, nitrogen atom group-containing vinyl compounds, and nitrogen atom group-containing epoxy compounds.

[0150] The isocyanate compound that is a modifying agent having a nitrogen atom-containing group is not particularly limited, but examples thereof include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate (C-MDI), phenyl isocyanate, isophorone diisocyanate, hexamethylene diisocyanate, butyl isocyanate, and 1,3,5-benzene triisocyanate.

[0151] The isothiocyanate compound, which is a modifying agent having a nitrogen atom-containing group, is not particularly limited, and examples thereof include butyl isothiocyanate, cyclohexyl isothiocyanate, phenyl isothiocyanate, 2-chlorophenyl isothiocyanate, benzyl isothiocyanate, 2,6-diisopropylphenyl isothiocyanate, and 1,4-phenylenediisothiocyanate.

[0152] The isocyanuric acid derivative, which is a modifying agent having a nitrogen atom-containing group, is not particularly limited, and examples thereof include 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, and 1,3,5-trivinyl-1,3,5-triazinane-2,4,6-trione.

[0153] The nitrogen atom group-containing carbonyl compound, which is a modifying agent having a nitrogen atom group, is not particularly limited, and examples thereof include 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, and the like. Examples of pyridine include non-pyridyl ketone, methyl-2-pyridyl ketone, methyl-4-pyridyl ketone, propyl-2-pyridyl ketone, di-4-pyridyl ketone, 2-benzoylpyridine, N,N,N',N'-tetramethylurea, N,N-dimethyl-N',N'-diphenylurea, N,N-methyl diethylcarbamate, N,N-diethylacetamide, N,N-dimethyl-N',N'-dimethylaminoacetamide, N,N-dimethylpicolinic acid amide, and N,N-dimethylisonicotinic acid amide.

[0154] The vinyl compound that is a modifying agent having a nitrogen atom-containing group is not particularly limited, but examples thereof include N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N-methylmaleimide, N-methylphthalimide, N,N-bistrimethylsilyl acrylamide, morpholinoacrylamide, 3-(2-dimethylaminoethyl)styrene, (dimethylamino)dimethyl-4-vinylphenylsilane, 4,4'-vinylidenebis(N,N-dimethylaniline), 4,4'-vinylidenebis(N,N-diethylaniline), 1,1-bis(4-morpholinophenyl)ethylene, and 1-phenyl-1-(4-N,N-dimethylaminophenyl)ethylene.

[0155] The epoxy compound, which is a modifying agent having a nitrogen atom-containing group, is not particularly limited, but examples thereof include hydrocarbon compounds containing an epoxy group bonded to an amino group, and may further have an epoxy group bonded to an ether group. Examples of such epoxy compounds include, but are not limited to, epoxy compounds represented by general formula (i):

[0156] [ka] In the formula, R represents a divalent or higher organic group having at least one polar group selected from a divalent or higher hydrocarbon group, or a polar group containing oxygen such as an ether, epoxy, or ketone, a polar group containing sulfur such as a thioether or thioketone, or a polar group containing nitrogen such as a tertiary amino group or an imino group.

[0157] The divalent or higher valent hydrocarbon group is a saturated or unsaturated hydrocarbon group that may be linear, branched, or cyclic, and includes an alkylene group, an alkenylene group, a phenylene group, etc. Preferably, it is a hydrocarbon group having 1 to 20 carbon atoms. 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.

[0158] In formula (i), R 1 and R 4 each represents a hydrocarbon group having 1 to 10 carbon atoms, and R 1 and R 4 may be the same or different from each other.

[0159] In formula (i), R 2 and R 5 each represents hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, and R 2 and R 5 may be the same or different from each other.

[0160] In formula (i), R 3 represents a hydrocarbon group having 1 to 10 carbon atoms, or a structure of the following formula (ii):

[0161] R 1 , R 2 , and R 3 may be bonded to each other to form a cyclic structure.

[0162] Also, R 3When R represents a hydrocarbon group, it may be bonded to R to form a cyclic structure. In the case of the cyclic structure, R 3 The N bonded to R may be directly bonded to the N bonded to R.

[0163] In formula (i), n represents an integer of 1 or more, and m represents 0 or an integer of 1 or more. [ka]

[0164] In formula (ii), R 1 and R 2 is R in formula (i). 1 and R 2 is defined similarly to R 1 and R 2 may be the same or different from each other.

[0165] The epoxy compound, which is a modifying agent having a nitrogen atom-containing group, is preferably one having an epoxy group-containing hydrocarbon group, more preferably one having a glycidyl group-containing hydrocarbon group.

[0166] The epoxy group-containing hydrocarbon group bonded to an amino group or an ether group is not particularly limited, but examples thereof include a glycidylamino group, a diglycidylamino group, and a glycidoxy group. More preferred molecular structures are epoxy group-containing compounds having a glycidylamino group or a diglycidylamino group, and a glycidoxy group, respectively, and examples thereof include compounds represented by the following general formula (iii):

[0167] [ka] In formula (iii), R is defined as R in formula (i) above, and R 6 represents a hydrocarbon group having 1 to 10 carbon atoms or a structure of the following formula (iv):

[0168] R 6 When R represents a hydrocarbon group, it may be bonded to R to form a cyclic structure. In this case, R6 The N bonded to R may be directly bonded to the N bonded to R. In formula (iii), n represents an integer of 1 or more, and m represents 0 or an integer of 1 or more.

[0169] [ka]

[0170] As the epoxy compound which is a modifying agent having a nitrogen atom-containing group, a compound having one or more diglycidylamino groups and one or more glycidoxy groups in the molecule is particularly preferred.

[0171] Specific examples of epoxy compounds used as modifiers having a nitrogen atom-containing group include N,N-diglycidyl-4-glycidoxyaniline, 1-N,N-diglycidylaminomethyl-4-glycidoxycyclohexane, 4-(4-glycidoxyphenyl)-(N,N-diglycidyl)aniline, 4-(4-glycidoxyphenoxy)-(N,N-diglycidyl)aniline, 4-(4-glycidoxybenzyl)-(N,N-diglycidyl)aniline, 4-(N,N'-diglycidyl-2-piperazinyl)-glycidoxybenzene, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-m-xylylenediamine. amine, 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, and N,N-diglycidylaminomethylcyclohexane. Of these, preferred are N,N-diglycidyl-4-glycidoxyaniline and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

[0172] The modifier having a nitrogen atom-containing group is also preferably an amine compound having no active hydrogen, and examples thereof include tertiary amine compounds, protected amine compounds in which the above-mentioned active hydrogen is substituted with a protecting group, imine compounds represented by the general formula -N=C (compounds represented by general formula (D) described below), and alkoxysilane compounds bonded to a nitrogen atom-containing group.

[0173] As a modifying agent having a nitrogen atom-containing group, a protected amine compound capable of forming a primary or secondary amine, a compound having an unsaturated bond and a protected amine in the molecule is not particularly limited, but examples thereof 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)aniline], 4,4'-vinylidenebis[N-methyl-N-(trimethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl ... vinylidenebis[N-methyl-N-(triethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N-(triethylsilyl)aniline], 4,4'-vinylidenebis[N-methyl-N-(t-butyldimethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N-(t-butyldimethylsilyl)aniline], 1-[4-N,N-bis(trimethylsilyl)aminophenyl]-1-[4-N-methyl-N-(trimethylsilyl)aminophenyl]ethylene, and 1-[4-N,N-bis(trimethylsilyl)aminophenyl]-1-[4-N,N-dimethylaminophenyl]ethylene.

[0174] As a modifying agent having a nitrogen atom-containing group, a protected amine compound capable of forming a primary or secondary amine, a compound having an alkoxysilane and a protected amine in the molecule is not particularly limited, but examples thereof 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-hexahydropyrimidinyl)propyltrimethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4- trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, and 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane.

[0175] The alkoxysilane compound having a tertiary amine, which is a modifying agent having a nitrogen atom-containing group, is not particularly limited, and examples thereof include 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropylmethyldimethoxysilane, 3-diethylaminopropyltriethoxysilane, 3-morpholinopropyltrimethoxysilane, 3-piperidinopropyltriethoxysilane, 3-hexamethyleneiminopropylmethyldiethoxysilane, 3-(4-methyl-1-piperazino)propyltriethoxysilane, 1-[3-(triethoxysilyl) -propyl]-3-methylhexahydropyrimidine, 3-(4-trimethylsilyl-1-piperazino)propyltriethoxysilane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane, 3-(3-trimethylsilyl-1-hexahydropyrimidinyl)propyltrimethoxysilane, 3-dimethylamino-2-(dimethylaminomethyl)propyltrimethoxysilane, bis(3-dimethoxymethylsilylpropyl)-N-methylamine, bis(3-trimethoxysilylpropyl)-N-methylamine, bis(3-trimethylsilylpropyl)-N-methylamine, 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.

[0176] Particularly preferred examples of the alkoxysilane compound having a tertiary amine as a modifier having a nitrogen atom-containing group include tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-tripropoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-meth bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3 -trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexamethylenediamine, pentakis(3-trimethoxysilylpropyl)-diethylenetriamine, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1- aza-2-silacyclopentane)propyl]silane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]silane, 3-tris[2-(2,2-Dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-trimethoxysilylpropane, 1-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 1-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexyl-[3 -(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]ether, (3-trimethoxysilylpropyl)phosphate, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)phosphate, and tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate.

[0177] (Preferred Structure of Conjugated Diene Polymer) The conjugated diene polymer of the present embodiment preferably contains a structure derived from a compound having a nitrogen atom-containing group, represented by the following general formula (i) or any one of (A) to (E): Hereinafter, the general formula (i) is the same as the general formula (i) described above for the epoxy compound represented by general formula (i), including the description of general formula (ii). From the viewpoint of obtaining a conjugated diene-based polymer having a desired degree of branching, the above-mentioned compound having a nitrogen atom-containing group may be used alone or in combination of two or more types of compounds having a nitrogen atom-containing group.

[0178] [ka] In the formula, R 1 ~R 4 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R 5represents an alkylene group having 1 to 10 carbon atoms, and R 6 represents an alkylene group having 1 to 20 carbon atoms. m represents an integer of 1 or 2, n represents an integer of 2 or 3, and (m+n) represents an integer of 4 or more. 1 ~R 4 are each independent of each other.

[0179] [ka] In the formula, R 1 ~R 6 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R 7 ~R 9 are each independently an alkylene group having 1 to 20 carbon atoms. m, n, and l each independently represent an integer of 1 to 3, and (m+n+l) represents an integer of 4 or more. 1 ~R 6 are each independent of each other.

[0180] [ka] In the formula, R 12 ~R 14 each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms, and R 15 ~R 18 and R20 each independently represent an alkyl group having 1 to 20 carbon atoms; R 19 and R 22 each independently represents an alkylene group having 1 to 20 carbon atoms; 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 when there are multiple of each 12 ~R 22 , m, and p are each independent and may be the same or different. i represents an integer of 0 to 6, j represents an integer of 0 to 6, k represents an integer of 0 to 6, and (i+j+k) is an integer of 4 to 10. A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom, and a phosphorus atom and having no active hydrogen, or represents any of the general formulae (II) to (V) described below.

[0181] [ka] R in the formula 1 and R 4 each independently represents an alkylene group having 1 to 20 carbon atoms or an alkyl group having 1 to 20 carbon atoms, and R 2 and R 5 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R 3 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms. n represents an integer of 1 to 3. When a plurality of R 1 ~R 5 are each independent of each other.

[0182] [ka] R in the formula 1 ~R 4 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R 5 ~R 7 each independently represents an alkylene group having 1 to 20 carbon atoms. m and n each represent an integer of 1 to 3 and may be the same or different. 1 ~R 7 are each independent of each other.

[0183] The modifying agent having a nitrogen atom-containing group represented by formula (A) is not particularly limited, and examples thereof include 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacycloheptane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclohexane, and the like. 2-methoxy,2-methyl-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-ethoxy,2-ethyl-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy,2-methyl-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, and 2-ethoxy,2-ethyl-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane.

[0184] Among these, from the viewpoints of reactivity and interaction between the functional group of the nitrogen atom-containing modifier and an inorganic filler such as silica, as well as processability, those in which m is 2 and n is 3 are preferred. Specifically, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane and 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane are preferred.

[0185] The reaction temperature, reaction time, etc. when reacting the modifying agent having a nitrogen atom-containing group represented by formula (A) with the polymerization active terminal are not particularly limited, but it is preferable to react at 0°C or higher and 120°C or lower for 30 seconds or longer.

[0186] The total number of moles of alkoxy groups bonded to silyl groups in the modifying compound having the nitrogen atom-containing group represented by formula (A) is preferably in the range of 0.6 to 3.0 times the number of moles of the alkali metal compound and / or alkaline earth metal compound added as the polymerization initiator, more preferably in the range of 0.8 to 2.5 times, and even more preferably in the range of 0.8 to 2.0 times. A ratio of 0.6 or more is preferred from the viewpoint of obtaining a sufficient modification rate, molecular weight, and branched structure in the resulting conjugated diene polymer, and a ratio of 3.0 or less is preferred from the viewpoint of obtaining a branched polymer component by coupling polymer ends to improve processability and from the viewpoint of modifier costs.

[0187] More specifically, the number of moles of the polymerization initiator is preferably 3.0 times or more, more preferably 4.0 times or more, relative to the number of moles of the modifying agent.

[0188] The modifying agent having a nitrogen atom-containing group represented by formula (B) is not particularly limited, but examples thereof include tris(3-trimethoxysilylpropyl)amine, tris(3-methyldimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-methyldiethoxysilylpropyl)amine, tris(trimethoxysilylmethyl)amine, tris(2-trimethoxysilylethyl)amine, and tris(4-trimethoxysilylbutyl)amine.

[0189] Among these, from the viewpoints of reactivity and interaction between the functional group of the modifier and an inorganic filler such as silica, as well as processability, it is preferable that n, m, and l all represent 3. Preferred specific examples include tris(3-trimethoxysilylpropyl)amine and tris(3-triethoxysilylpropyl)amine.

[0190] The reaction temperature, reaction time, etc. when reacting the modifying agent having a nitrogen atom-containing group represented by formula (B) with the polymerization active terminal are not particularly limited, but it is preferable to react at 0°C or higher and 120°C or lower for 30 seconds or longer.

[0191] The total number of moles of alkoxy groups bonded to silyl groups in the modifying compound represented by formula (B) is preferably in the range of 0.6 to 3.0 times, more preferably 0.8 to 2.5 times, and even more preferably 0.8 to 2.0 times, the number of moles of lithium constituting the polymerization initiator. From the viewpoint of obtaining a sufficient modification rate, molecular weight, and branched structure in the conjugated diene polymer, a ratio of 0.6 or more is preferred, and from the viewpoint of obtaining a branched polymer component by coupling polymer terminals to improve processability and from the viewpoint of modifier costs, a ratio of 3.0 or less is preferred.

[0192] More specifically, the number of moles of the polymerization initiator is preferably 4.0 times or more, more preferably 5.0 times or more, relative to the number of moles of the modifying agent.

[0193] In formula (C), A is preferably represented by any one of the following general formulae (II) to (V): do. [ka] In the formula, B 1 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. When a plurality of B 1 are each independent of each other.

[0194] [ka] In formula (III), B 2 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, B 3 represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. When a plurality of B 2 and B 3 are each independent of each other.

[0195] [ka] In formula (IV), B 4 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. When a plurality of B 4 are each independent of each other.

[0196] [ka] In formula (V), B 5 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents 1 to 10 If there are multiple integers, B 5 are each independent of each other.

[0197] In formula (C), when A is represented by formula (II), the modifying agent having a nitrogen atom-containing group is not particularly limited, and examples thereof include tris(3-trimethoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)amine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane )propyl]amine, tris(3-ethoxysilylpropyl)amine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]amine, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)amine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tris (3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1-aza -2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis[3-(2,2-Dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-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-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-1,3-propanediamine, tetrakis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl 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 tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane )propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-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-propane Diamine, 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-silacyclo Examples of the silyl groups include tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexamethylenediamine, and pentakis(3-trimethoxysilylpropyl)-diethylenetriamine.

[0198] In formula (C), when A is represented by formula (III), the modifying agent having a nitrogen atom-containing group is not particularly limited, and examples thereof include tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, bis(2-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3-propanediamine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, Tris(3-triethoxysilylpropyl)-methyl-1,3-propanediamine, Bis(2-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3-propanediamine, Bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-methyl-1,3-propanediamine, N 1 ,N 1 '-(Propane-1,3-diyl)bis(N 1 -methyl-N 3 ,N 3 -bis(3-(trimethoxysilyl)propyl)-1,3-propanediamine), and N 1 -(3-(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N 1 -methyl-N 3 -(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N 3 -(3-(trimethoxysilyl)propyl)-1,3-propanediamine.

[0199] In the formula (C), when A is represented by the formula (IV), the modifying agent having a nitrogen atom-containing group is not particularly limited, and examples thereof 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-trimethoxysilylpropyl)silane, yl]-[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 propyl]silane, bis[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila- 2-azacyclopentane)propyl]-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-bis(3-trimethoxysilylpropyl)silane, and bis(3-trimethoxysilylpropyl)-bis[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]silane.

[0200] In the formula (C), when A is represented by the formula (V), the modifying agent having a nitrogen atom-containing group is Examples of the silyl group include, but are not limited to, 3-tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-(2,2-dimethoxy-1-aza-2-silacyclopentane)propane and 3-tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-trimethoxysilylpropane.

[0201] In formula (C), A is preferably represented by formula (II) or formula (III), and k is 0.

[0202] Modifiers having such nitrogen atom-containing groups tend to be easily available and tend to provide better abrasion resistance and low hysteresis loss when the conjugated diene polymer is vulcanized. Modifiers having such nitrogen atom-containing groups are not particularly limited, but examples thereof include bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy- 1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, and bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trismethoxysilylpropyl)-methyl-1,3-propanediamine.

[0203] In formula (C), A is more preferably represented by formula (II) or formula (III), k represents 0, and in formula (II) or formula (III), a represents an integer of 2 to 10.

[0204] This tends to result in better abrasion resistance and low hysteresis loss performance when vulcanized.

[0205] The modifying agent having such a nitrogen atom-containing group is not particularly limited, but examples thereof include tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, and N 1 -(3-(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N 1 -methyl-N 3 -(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N 3 -(3-(trimethoxysilyl)propyl)-1,3-propanediamine.

[0206] The amount of the compound represented by formula (C) added as a modifier having a nitrogen atom-containing group can be adjusted so that the number of moles of the conjugated diene polymer to the number of moles of the modifier react in a desired stoichiometric ratio, which tends to achieve a desired star-shaped highly branched structure.

[0207] Specifically, the number of moles of the polymerization initiator is preferably 5.0 times or more, more preferably 6.0 times or more, relative to the number of moles of the modifying agent. In this case, in formula (C), the number of functional groups of the modifying agent ((m-1)xi+pxj+k) is preferably an integer of 5-10, and more preferably an integer of 6-10.

[0208] The modifying agent having a nitrogen atom-containing group represented by formula (D) is not particularly limited, and examples thereof include N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-(trimethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-methyl(dimethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-methyl(dimethoxysilyl)-1-propanamine,3-dimethylbutylidene)-3-methyl(diethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(trimethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-methyl(dimethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-methyl(diethoxysilyl)-1-propanamine, N-ethylidene-3-(triethoxysilyl)-1-propanamine, N-ethylidene-3-(trimeth N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(trimethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-methyl(dimethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-methyl(diethoxysilyl)-1-propanamine N-benzylidene-3-(triethoxysilyl)propan-1-amine, N-benzylidene-3-(trimethoxysilyl)propan-1-amine, N-benzylidene-3-methyl(dimethoxysilyl)propan-1-amine, N-benzylidene-3-methyl(diethoxysilyl)propan-1-amine, N-4-methylbenzylidene-3-(triethoxysilyl)propan-1-amine, N-4-methylbenzylidene-3-(trimethoxysilyl)propan-1-amine, N-4-methylbenzylidene-3-methyl(dimethoxysilyl)propane -1-amine, N-4-methylbenzylidene-3-methyl(diethoxysilyl)propan-1-amine, N-naphthylidene-3-(triethoxysilyl)propan-1-amine, N-naphthylidene-3-(trimethoxysilyl)propan-1-amine, N-naphthylidene-3-methyl(dimethoxysilyl)propan-1-amine, 1,1-(1,4-phenylene)bis(N-(3(triethoxysilyl)propyl)methanamine), 1,1-(1,4-phenylene)bis(N-(3(trimethoxysilyl)propyl)methanamine), 1,1-(1,4-phenylene)bis(N-(3-methyl(dimethoxysilyl)propyl)methanamine), 1,1-(1,4-phenylene)bis(N-(3-methyl(diethoxysilyl)propyl)methanamine), 2-methoxy-2-methyl-1-(benzylideneaminoethyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-1-(p-methoxybenzylideneaminoethyl)-1-aza-2-silacyclopentane, 2-ethoxy-2-methyl-1-(benzylideneaminoethyl)-1-aza-2-silacyclopentane, and 2-methoxy-2-methyl-1-(methylisobutylideneaminoethyl)-1-aza-2-silacyclopentane.

[0209] The reaction temperature, reaction time, etc. when reacting the modifying agent having a nitrogen atom-containing group represented by formula (D) with the polymerization active terminal are not particularly limited, but it is preferable to react at 0°C or higher and 120°C or lower for 30 seconds or longer.

[0210] The total number of moles of alkoxy groups bonded to silyl groups in the modifying compound represented by formula (D) is preferably in the range of 0.2 to 2.0 times, more preferably 0.3 to 1.5 times, the number of moles of lithium constituting the polymerization initiator. From the viewpoint of obtaining a sufficient modification rate and molecular weight in the conjugated diene polymer, it is preferably 0.3 times or more, and from the viewpoint of the cost of the modifying agent, it is preferably 2.0 times or less.

[0211] The modifying agent having a nitrogen atom-containing group represented by formula (E) is not particularly limited, and examples thereof include N-(3-(1H-imidazol-1-yl)propyl)-3-(triethoxysilyl)-N-(3-(triethoxysilyl)propyl)propan-1-amine, N-(3-(1H-imidazol-1-yl)propyl)-3-(trimethoxysilyl)-N-(3-(trimethoxysilyl)propyl)propan-1-amine, N-(3-(1H-imidazol-1-yl)propyl)-3-(ethyldiethoxysilyl)-N-(3-(ethyldiethoxysilyl)propyl) propan-1-amine, N-(3-(1H-imidazol-1-yl)propyl)-3-(methyldimethoxysilyl)-N-(3-(methyldimethoxysilyl)propyl)propan-1-amine, N-(3-(1H-imidazol-1-yl)propyl)-3-(diethylethoxysilyl)-N-(3-(diethylethoxysilyl)propyl)propan-1-amine, and N-(3-(1H-imidazol-1-yl)propyl)-3-(dimethylmethoxysilyl)-N-(3-(dimethylmethoxysilyl)propyl)propan-1-amine.

[0212] The reaction temperature, reaction time, etc. when reacting the modifying agent having a nitrogen atom-containing group represented by formula (E) with the polymerization active terminal are not particularly limited, but it is preferable to react at 0°C or higher and 120°C or lower for 30 seconds or longer.

[0213] The total number of moles of alkoxy groups bonded to silyl groups in the modifying compound represented by formula (E) is preferably in the range of 0.2 to 2.0 times, more preferably 0.3 to 1.5 times, the number of moles of lithium constituting the polymerization initiator. From the viewpoint of obtaining a sufficient modification rate and molecular weight in the conjugated diene polymer, it is preferably 0.3 times or more, and from the viewpoint of the cost of the modifying agent, it is preferably 2.0 times or less.

[0214] In this embodiment, after the modification step, a condensation reaction step of carrying out a condensation reaction in the presence of a condensation promoter may be further carried out.

[0215] In the conjugated diene polymer of the present embodiment, the conjugated diene moiety in the conjugated diene polymer chain may be hydrogenated.

[0216] The method for hydrogenating the conjugated diene portion of the conjugated diene polymer is not particularly limited, and known methods can be used.

[0217] A suitable hydrogenation method is to inject 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 materials; catalysts in which salts of nickel, cobalt, etc. are solubilized and reacted with organoaluminum, etc.; and homogeneous catalysts such as catalysts using metallocenes such as titanocene. Among these, titanocene catalysts are preferred from the viewpoint of being able to select mild hydrogenation conditions. Furthermore, the hydrogenation of aromatic groups can be carried out by using a supported catalyst of a noble metal.

[0218] The hydrogenation catalyst is not particularly limited, but examples thereof include (1) supported heterogeneous hydrogenation catalysts in which a metal such as Ni, Pt, Pd, or Ru is supported on carbon, silica, alumina, diatomaceous earth, or the like, (2) so-called Ziegler-type hydrogenation catalysts which use a transition metal salt such as an organic acid salt or an acetylacetone salt of Ni, Co, Fe, Cr, or the like and a reducing agent such as organoaluminum, and (3) so-called organometallic complexes such as organometallic compounds of Ti, Ru, Rh, Zr, etc. Furthermore, the hydrogenation catalyst is not particularly limited, but examples thereof include known hydrogenation catalysts described in JP-B Nos. 42-8704, 43-6636, 63-4841, 1-37970, 1-53851, 2-9041, and 8-109219. Preferred hydrogenation catalysts include reaction mixtures of titanocene compounds and reducing organometallic compounds.

[0219] In the method for producing a conjugated diene polymer of this embodiment, after the modification step, a deactivator, a neutralizer, etc. may be added to the polymer solution as needed.

[0220] The quenching agent is not particularly limited, but examples thereof include water; alcohols such as methanol, ethanol, and isopropanol; and the like.

[0221] The neutralizing agent is not particularly limited, but examples thereof include carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture having 9 to 11 carbon atoms, mainly 10 carbon atoms); aqueous solutions of inorganic acids, and carbon dioxide gas.

[0222] In the method for producing a conjugated diene polymer of this embodiment, it is preferable to add a rubber stabilizer from the viewpoint of preventing gel formation after polymerization and improving stability during processing.

[0223] The rubber stabilizer is not limited to the following and known stabilizers can be used, but preferred are antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (hereinafter also referred to as "BHT"), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol) propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol.

[0224] In order to further improve the productivity of the conjugated diene polymer of the present embodiment and the processability when it is made into a composition containing a filler or the like, a rubber softener can be added as needed.

[0225] The rubber softener is not particularly limited, but examples thereof include extender oil, liquid rubber, and resin.

[0226] The method for adding the rubber softener to the conjugated diene polymer is not particularly limited, but a preferred method is to add the rubber softener to a conjugated diene polymer solution, mix them, and then remove the solvent from the resulting polymer solution containing the rubber softener.

[0227] Preferred extender oils include, for example, aromatic oils, naphthenic oils, and paraffinic oils. Among these, aromatic substitute oils having a polycyclic aromatic (PCA) content of 3% by mass or less according to the IP346 method are preferred from the viewpoints of environmental safety, oil bleeding prevention, and wet grip properties. Examples of aromatic substitute oils include TDAE (Treated Distillate Aromatic Extracts), MES (Mild Extraction Solvate), and RAE (Residual Aromatic Extracts), as shown in Kautschuk Gummi Kunststoffe 52(12)799(1999).

[0228] Preferred liquid rubbers are not particularly limited, but examples thereof include liquid polybutadiene and liquid styrene-butadiene rubber.

[0229] The effect of adding liquid rubber is that it improves the processability of a composition prepared by blending a conjugated diene polymer with a filler or the like, and also shifts the glass transition temperature of the composition to a lower temperature, which tends to improve the abrasion resistance, low hysteresis loss, and low-temperature properties of the vulcanized product.

[0230] Preferred resins include, but are not limited to, aromatic petroleum resins, coumarone-indene resins, terpene resins, rosin derivatives (including tung oil resins), tall oil, tall oil derivatives, rosin ester resins, natural and synthetic terpene resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, mixed aliphatic-aromatic hydrocarbon resins, coumarin-indene resins, phenolic resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, monoolefin oligomers, diolefin oligomers, aromatic hydrocarbon resins, aromatic petroleum resins, hydrogenated aromatic hydrocarbon resins, cycloaliphatic hydrocarbon resins, hydrogenated hydrocarbon resins, hydrocarbon resins, hydrogenated tung oil resins, hydrogenated oil resins, and esters of hydrogenated oil resins with monofunctional or polyfunctional alcohols. These resins may be used alone or in combination. When hydrogenating, all unsaturated groups may be hydrogenated, or some may remain.

[0231] The effect of adding a resin is to improve the processability of a composition obtained by blending a conjugated diene polymer with a filler or the like, and also to tend to improve the breaking strength of a vulcanized product. Furthermore, the glass transition temperature of the composition can be shifted to a higher temperature, which tends to improve wet skid resistance.

[0232] The amount of the rubber softener, such as an extender oil, liquid rubber, or resin, added is not particularly limited, but is preferably 1 part by mass or more and 60 parts by mass or less, more preferably 5 parts by mass or more and 50 parts by mass or less, and even more preferably 10 parts by mass or more and 37.5 parts by mass or less, relative to 100 parts by mass of the modified conjugated diene-based polymer of the present embodiment.

[0233] When the rubber softener is added within the above range, the processability of a composition containing the conjugated diene polymer and a filler, etc., is improved, and the breaking strength and abrasion resistance of a vulcanized product tend to be improved.

[0234] (Desolvation process) In the method for producing a conjugated diene polymer of this embodiment, a known method can be used to obtain the resulting conjugated diene polymer from the polymer solution. The method is not particularly limited, and examples thereof include a method in which the solvent is separated by steam stripping or the like, the polymer is filtered, and then the polymer is dehydrated and dried to obtain the polymer, a method in which the polymer is concentrated in a flashing tank and then devolatilized using a vent extruder or the like, and a method in which the polymer is directly devolatilized using a drum dryer or the like.

[0235] (Rubber composition) The rubber composition of the present embodiment contains a rubber component and 5.0 parts by mass or more and 150 parts by mass or less of a filler relative to 100 parts by mass of the rubber component. Furthermore, from the viewpoint of improving fuel economy performance, processability, and abrasion resistance, the rubber component contains 10 mass% or more of the above-mentioned conjugated diene polymer or the above-mentioned conjugated diene polymer composition relative to the total amount (100 mass%) of the rubber component.

[0236] The filler preferably includes a silica-based inorganic filler. By including the silica-based inorganic filler, the rubber composition of the present embodiment tends to have better processability when vulcanized, and the vulcanized product tends to have a better balance of abrasion resistance, breaking strength, low hysteresis loss, and wet skid resistance.

[0237] When the rubber composition of the present embodiment is used for vulcanized rubber applications such as tires, automobile parts such as anti-vibration rubber, and shoes, it is also preferable that the rubber composition contain a silica-based inorganic filler.

[0238] In the rubber composition of the present embodiment, a rubbery polymer other than the above-mentioned conjugated diene-based polymer (hereinafter simply referred to as a "rubbery polymer") can be used in combination with the above-mentioned conjugated diene-based polymer.

[0239] Such rubbery polymers are not particularly limited, but examples thereof include conjugated diene polymers or hydrogenated products thereof, random copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, block copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, non-diene polymers, and natural rubber.

[0240] Specific examples of rubber-like polymers include, but are not limited to, styrene-based elastomers such as butadiene rubber or hydrogenated products thereof, isoprene rubber or hydrogenated products thereof, styrene-butadiene rubber or hydrogenated products thereof, styrene-butadiene block copolymers or hydrogenated products thereof, and styrene-isoprene block copolymers or hydrogenated products thereof, and acrylonitrile-butadiene rubber or hydrogenated products thereof.

[0241] The non-diene polymer is not particularly limited, but examples thereof include olefin elastomers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, and ethylene-octene rubber, butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylate-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber.

[0242] The natural rubber is not particularly limited, but examples thereof include smoked sheets RSS3 to RSS5, SMR, and epoxidized natural rubber.

[0243] The various rubbery polymers described above may be modified rubbers to which polar functional groups such as hydroxyl groups, amino groups, etc. When used for tires, butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber are preferably used.

[0244] From the viewpoint of the balance between performance and processing characteristics, the weight-average molecular weight of the rubbery polymer is preferably 2,000 to 2,000,000, and more preferably 5,000 to 1,500,000. Low-molecular-weight rubbery polymers, so-called liquid rubbers, can also be used. These rubbery polymers may be used alone or in combination of two or more.

[0245] When the rubber composition of this embodiment is a rubber composition containing the above-mentioned conjugated diene polymer and rubbery polymer, the content ratio (mass ratio) of the above-mentioned conjugated diene polymer to the rubbery polymer (the above-mentioned conjugated diene polymer / rubbery polymer) is preferably 10 / 90 or more and 100 / 0 or less, more preferably 20 / 80 or more and 90 / 10 or less, and even more preferably 50 / 50 or more and 80 / 20 or less.

[0246] Therefore, the rubber component preferably contains 10 parts by mass or more and 100 parts by mass or less of the above-mentioned conjugated diene polymer relative to the total amount (100 parts by mass) of the rubber component, more preferably 20 parts by mass or more and 90 parts by mass or less, and even more preferably 50 parts by mass or more and 80 parts by mass or less.

[0247] When the content ratio (the above-mentioned conjugated diene polymer / rubber-like polymer) is within the above range, the vulcanizate has excellent abrasion resistance and breaking strength, and also has a satisfactory balance between low hysteresis loss and wet skid resistance.

[0248] The filler contained in the rubber composition of the present embodiment is not particularly limited, but examples thereof include silica-based inorganic fillers, carbon black, metal oxides, and metal hydroxides. Among these, silica-based inorganic fillers are preferred. The fillers may be used alone or in combination of two or more.

[0249] The content of the filler in the rubber composition of this embodiment is 5.0 parts by mass or more and 150 parts by mass or less, preferably 20 parts by mass or more and 100 parts by mass or less, and more preferably 30 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the rubber component containing the conjugated diene-based polymer.

[0250] In the rubber composition of the present embodiment, the content of the filler is 5.0 parts by mass or more per 100 parts by mass of the rubber component from the viewpoint of exhibiting the effect of adding the filler, and is 150 parts by mass or less per 100 parts by mass of the rubber component from the viewpoint of sufficiently dispersing the filler and ensuring that the processability and mechanical strength of the composition are practically sufficient.

[0251] The silica-based inorganic filler is not particularly limited and any known filler can be used, but solid particles containing SiO2 or Si3Al as a structural unit are preferred, and solid particles containing SiO2 or Si3Al as a main component of the structural unit are more preferred. Here, the main component refers to a component contained in the silica-based inorganic filler in an amount of 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more.

[0252] Specific silica-based inorganic fillers are not particularly limited, but examples thereof include inorganic fibrous materials such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber. Other examples include silica-based inorganic fillers with hydrophobic surfaces and mixtures of silica-based inorganic fillers with non-silica-based inorganic fillers. Among these, silica and glass fiber are preferred from the viewpoints of strength and abrasion resistance, and silica is more preferred. Examples of silica include dry silica, wet silica, and synthetic silicate silica. Among these silicas, wet silica is preferred from the viewpoint of achieving an excellent balance between the effect of improving fracture strength and wet skid resistance.

[0253] From the viewpoint of obtaining practically good abrasion resistance and breaking strength of the rubber composition, the nitrogen adsorption specific surface area determined by the BET adsorption method of the silica-based inorganic filler is 100 m 2 / g or more 300m 2 / g or less, and 170m 2 / g or more 250m 2 / g or less. If necessary, a relatively small specific surface area (for example, a specific surface area of ​​200 m 2 / g or less) and silica-based inorganic fillers with a relatively large specific surface area (e.g., 200 m 2 In this embodiment, a silica-based inorganic filler having a relatively large specific surface area (for example, 200 m 2 / g or more), the composition containing the conjugated diene polymer improves the dispersibility of the silica, is particularly effective in improving abrasion resistance, and tends to achieve a high level of balance between good fracture strength and low hysteresis loss.

[0254] The content of the silica-based inorganic filler in the rubber composition is preferably 5.0 parts by mass or more and 150 parts by mass or less, and more preferably 20 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of the rubber component containing the conjugated diene polymer. In the rubber composition of this embodiment, the content of the silica-based inorganic filler is 5.0 parts by mass or more per 100 parts by mass of the rubber component from the viewpoint of exhibiting the effect of adding the inorganic filler, and is 150 parts by mass or less per 100 parts by mass of the rubber component from the viewpoint of sufficiently dispersing the inorganic filler and making the processability and mechanical strength of the composition practically sufficient.

[0255] The carbon black is not particularly limited, but examples thereof include carbon blacks of various classes such as SRF, FEF, HAF, ISAF, and SAF. Among these, carbon blacks having a nitrogen adsorption specific surface area of ​​50 m 2 / g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100 g or less is preferred.

[0256] In the rubber composition of this embodiment, the content of carbon black is preferably 0.5 parts by mass to 100 parts by mass, more preferably 3.0 parts by mass to 100 parts by mass, and even more preferably 5.0 parts by mass to 50 parts by mass, per 100 parts by mass of the rubber component containing the conjugated diene polymer. In the rubber composition of this embodiment, the content of carbon black is preferably 0.5 parts by mass or more per 100 parts by mass of the rubber component from the viewpoint of exhibiting performance required for applications such as tires, such as dry grip performance and electrical conductivity, and is preferably 100 parts by mass or less per 100 parts by mass from the viewpoint of dispersibility.

[0257] Metal oxide refers to solid particles whose main constituent is 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).

[0258] The metal oxide is not particularly limited, but examples thereof include alumina, titanium oxide, magnesium oxide, and zinc oxide.

[0259] The metal hydroxide is not particularly limited, but examples thereof include aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0260] The rubber composition of this embodiment may contain a silane coupling agent. The silane coupling agent functions to strengthen the interaction between the rubber component and the inorganic filler, and has groups that have affinity or bonding properties for both the rubber component and the silica-based inorganic filler. A preferred example is a compound that has a sulfur-bonding moiety and an alkoxysilyl or silanol group moiety in one molecule. Examples of such compounds include, but are not limited to, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide.

[0261] In the rubber composition of this embodiment, the content of the silane coupling agent is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, and even more preferably 1.0 to 15 parts by mass, relative to 100 parts by mass of the inorganic filler. When the content of the silane coupling agent is within the above range, the effect of the addition of the silane coupling agent tends to be more pronounced.

[0262] The rubber composition of the present embodiment may contain a rubber softener from the viewpoint of improving its processability.

[0263] The amount of rubber softener added is expressed as the total amount of rubber softener including the amount of rubber softener previously contained in the conjugated diene polymer or other rubber-like polymers, and the amount of rubber softener added when preparing the rubber composition, per 100 parts by mass of the rubber component containing the conjugated diene polymer.

[0264] As the rubber softener, mineral oil or a liquid or low molecular weight synthetic softener is suitable.

[0265] Mineral oil-based rubber softeners, known as process oils or extender oils, which are used to soften rubber, increase its volume, and improve its processability, are mixtures of aromatic rings, naphthenic rings, and paraffin chains. Those in which the carbon number of the paraffin chains accounts for 50% or more of the total carbon atoms are called paraffinic, those in which the carbon number of the naphthenic rings accounts for 30% to 45% of the total carbon atoms are called naphthenic, and those in which the aromatic carbon number accounts for more than 30% of the total carbon atoms are called aromatic. When the conjugated diene polymer of this embodiment is a copolymer of a conjugated diene compound and a vinyl aromatic compound, it is preferable to use a rubber softener with an appropriate aromatic content, as this tends to be compatible with the copolymer.

[0266] In the rubber composition of this embodiment, the content of the rubber softener is preferably 0 to 100 parts by mass, more preferably 10 to 90 parts by mass, and even more preferably 30 to 90 parts by mass, per 100 parts by mass of the rubber component. When the content of the rubber softener is 100 parts by mass or less per 100 parts by mass of the rubber component, bleeding out tends to be suppressed and stickiness of the surface of the rubber composition tends to be suppressed.

[0267] The method for mixing the conjugated diene polymer with other rubber-like polymers, silica-based inorganic fillers, carbon black or other fillers, and additives such as silane coupling agents and rubber softeners is not particularly limited, but examples include melt-kneading methods using common mixers such as open rolls, Banbury mixers, kneaders, single-screw extruders, twin-screw extruders, and multi-screw extruders, and methods in which the components are dissolved and mixed and then the solvent is removed by heating. Of these, melt-kneading methods using rolls, Banbury mixers, kneaders, and extruders are preferred from the standpoints of productivity and good kneading ability. Furthermore, either a method in which the rubber component, other fillers, silane coupling agents, and additives are kneaded all at once, or a method in which they are mixed in multiple batches, can be used.

[0268] The rubber composition of this embodiment may be vulcanized using a vulcanizing agent to form a vulcanized composition. The vulcanizing agent is not particularly limited, but examples include radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds. Examples of sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, and polymeric polysulfur compounds. In the rubber composition of this embodiment, the content of the vulcanizing agent is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, per 100 parts by mass of the rubber component. Conventional vulcanization methods can be used, and the vulcanization temperature is preferably 120°C to 200°C, more preferably 140°C to 180°C.

[0269] During vulcanization, a vulcanization accelerator may be used as needed. Conventionally known vulcanization accelerators can be used, and are not particularly limited. Examples of the vulcanization accelerator include sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators. Furthermore, the vulcanization aid is not particularly limited. Examples of the vulcanization accelerator include zinc oxide and stearic acid. The content of the vulcanization accelerator is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, per 100 parts by mass of the rubber component.

[0270] The rubber composition of this embodiment may contain various additives other than those described above, such as softeners and fillers, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants, as long as they do not impair the object of the present invention. Known softeners can be used as the other softeners. Specific examples of other fillers include, but are not limited to, calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. Known materials can be used as the heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants.

[0271] The rubber composition of the present embodiment is suitably used as a rubber composition for tires, that is, the tire of the present embodiment contains the rubber composition of the present embodiment.

[0272] The rubber composition for tires is not particularly limited, and can be used in various tire parts such as treads, carcasses, sidewalls, and beads of various tires, including fuel-efficient tires, all-season tires, high-performance tires, studless tires, and tires for vehicles carrying heavy loads. In particular, the rubber composition for tires has an excellent balance of abrasion resistance, breaking strength, low hysteresis loss, and wet skid resistance when vulcanized, and is therefore suitably used for the treads of fuel-efficient tires, high-performance tires, and tires for vehicles carrying heavy loads. [Example]

[0273] Hereinafter, the present embodiment will be described in more detail with reference to specific examples and comparative examples, but the present embodiment is not limited to the following examples and comparative examples. Various physical properties in the examples and comparative examples were measured by the methods shown below.

[0274] (Physical Property 1) Mooney Viscosity Using a conjugated diene polymer or a conjugated diene polymer modified with a nitrogen atom-containing modifier (hereinafter also referred to as a "modified conjugated diene polymer", and collectively referred to as a "(modified) conjugated diene polymer") as a sample, the Mooney viscosity was measured using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) with an L-shaped rotor in accordance with ISO 289. The measurement temperature was 110°C when a conjugated diene polymer was used as the sample, and 100°C when a modified conjugated diene polymer was used as the sample. First, the sample was preheated at the test temperature for 1 minute, and then the rotor was rotated at 2 rpm. The torque after 4 minutes was measured and used as the Mooney viscosity (ML (Property 1)).

[0275] (Physical Property 2) Microstructure of Conjugated Diene Polymers A (modified) conjugated diene polymer was used as a sample, and 50 mg of the sample was dissolved in 10 mL of carbon disulfide to prepare a measurement sample. Using a solution cell, the infrared spectrum was measured in the range of 600 to 1000 cm-1, and the 1,4-cis bond content (mol %) and 1,2-vinyl bond content (mol %) of the conjugated diene polymer were determined from the absorbance at a predetermined wavenumber according to the calculation formula of Morero's method (described in D. Morero, A. Santambrogio, L. Porri, F. Clampelli: Chim. e Ind., 41, 758 (1959)). (Measuring device: Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation.)

[0276] (Physical Property 3) Branching Degree (Bn) The degree of branching (Bn) of the (modified) conjugated diene polymer was measured by a GPC-light scattering method with a viscosity detector as follows: Using a (modified) conjugated diene polymer as a sample, a gel permeation chromatography (GPC) measuring device (manufactured by Malvern under the trade name "GPCmax VE-2001") with three columns connected together, each packed with a polystyrene gel, was used to measure the polymer using three detectors connected in that order: a light scattering detector, an RI detector, and a viscosity detector (manufactured by Malvern under the trade name "TDA305"). Based on a polystyrene standard, the absolute molecular weight was determined from the results of the light scattering detector and the RI detector, and the intrinsic viscosity was determined from the results of the RI detector and the viscosity detector. The linear polymer has an intrinsic viscosity [η] = -3.883M 0.771 The shrinkage factor (g') was calculated as the ratio of the intrinsic viscosity corresponding to each molecular weight, where M represents the absolute molecular weight. The obtained contraction factor (g') was then used to calculate the branching degree (Bn), which is defined as g' = 6Bn / [(Bn+1)(Bn+2)]. The eluent used was tetrahydrofuran (hereinafter also referred to as "THF") containing 5 mmol / L triethylamine. The columns used were "TSKgel G4000HXL," "TSKgel G5000HXL," and "TSKgel G6000HXL," both manufactured by Tosoh Corporation. 20 mg of the sample to be measured was dissolved in 10 mL of THF to prepare a measurement solution, and 100 μL of the measurement solution was injected into a GPC measurement device and measured under conditions of an oven temperature of 40° C. and a THF flow rate of 1 mL / min.

[0277] (Property 3) Branching degree (Bn) of 1 / 2Hi polymer Under the same conditions as those for measuring the degree of branching (Bn) as described above, a chromatogram of the absolute molecular weight was obtained based on the solution viscosity and light scattering using a GPC-light scattering method with a viscosity detector. Using the height of the peak top Hi in the chromatogram of absolute molecular weight (absolute molecular weight curve) (however, when there are multiple peak tops in the absolute molecular weight curve, the height of the peak top with the maximum absolute molecular weight) as a reference, the branching degree of the polymer having the highest absolute molecular weight among at least two absolute molecular weights when the height in the absolute molecular weight curve is half the height Hi (1 / 2Hi) was calculated according to the above-mentioned method for measuring the branching degree (Bn) of the polymer of 1 / 2Hi.

[0278] (Physical property 4) Molecular weight Measurement condition 1: A (modified) conjugated diene polymer was used as a sample, and a chromatogram was measured using a GPC measurement device (manufactured by Tosoh Corporation, trade name "HLC-8320GPC") equipped with three columns connected together, each packed with a polystyrene gel, and an RI detector (manufactured by Tosoh Corporation, trade name "HLC8020"), and the weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were determined based on a calibration curve obtained using standard polystyrene. The eluent used was tetrahydrofuran (THF) containing 5 mmol / L triethylamine. Three columns, manufactured by Tosoh Corporation under the trade name "TSKgel SuperMultiporeHZ-H," were connected, and a guard column, manufactured by Tosoh Corporation under the trade name "TSKguardcolumn SuperMP(HZ)-H," was connected in front of each column. 10 mg of the sample to be measured was dissolved in 10 mL of THF to prepare a measurement solution, and 10 μL of the measurement solution was injected into a GPC measurement device and measured under conditions of an oven temperature of 40° C. and a THF flow rate of 0.35 mL / min. Among the various samples measured under the above measurement condition 1, samples whose molecular weight distribution (Mw / Mn) value was less than 1.6 were measured again under the following measurement condition 2. Samples whose molecular weight distribution value was 1.6 or more after measurement under measurement condition 1 were measured again under measurement condition 1. Measurement condition 2: A conjugated diene polymer or a coupled conjugated diene polymer was used as a sample, and a chromatogram was measured using a GPC measurement device equipped with three columns connected together, each column using a polystyrene gel as a packing material. The weight-average molecular weight (Mw) and number-average molecular weight (Mn) were determined based on a calibration curve using standard polystyrene. The eluent used was THF containing 5 mmol / L triethylamine. The columns used were the guard column "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation, and the columns "TSKgel SuperH5000," "TSKgel SuperH6000," and "TSKgel SuperH7000" manufactured by Tosoh Corporation. An RI detector (trade name "HLC8020" manufactured by Tosoh Corporation) was used under the conditions of an oven temperature of 40°C and a THF flow rate of 0.6 mL / min. 10 mg of the sample to be measured was dissolved in 20 mL of THF to prepare a measurement solution, and 20 μL of the measurement solution was injected into the GPC measurement device for measurement. For samples that were measured under measurement condition 1 and had a molecular weight distribution value of less than 1.6, measurement was carried out under measurement condition 2.

[0279] (Physical Property 5) Modification rate The modification rate of the (modified) conjugated diene polymer was measured by the column adsorption GPC method as follows: The measurement was carried out by using a coupled conjugated diene polymer as a sample and applying the adsorption property of the modified basic polymer component to a GPC column packed with silica gel. The amount of a sample solution containing the sample and low-molecular-weight internal standard polystyrene adsorbed onto the silica-based column was measured by subtracting the chromatogram measured on the polystyrene-based column from the chromatogram measured on the silica-based column, and the modification rate was calculated. Specifically, the measurements were performed under the measurement condition 1 in (Property 4) above. For samples whose molecular weight distribution was 1.6 or more, the measurements were performed under the measurement condition 3 below, and for samples whose molecular weight distribution was less than 1.6, the measurements were performed under the measurement condition 4 below. Preparation of sample solution: 10 mg of sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF to prepare a sample solution. Measurement condition 3: GPC measurement conditions using a polystyrene column: Using a Tosoh Corporation "HLC-8320GPC" column, 10 μL of sample solution was injected into the column using 5 mmol / L triethylamine in THF as the eluent, and a RI detector was used to obtain a chromatogram under the following conditions: column oven temperature 40°C, THF flow rate 0.35 mL / min. Three Tosoh Corporation "TSKgel SuperMultiporeHZ-H" columns were connected, with a Tosoh Corporation "TSKguardcolumn SuperMP(HZ)-H" guard column connected in front of them. Measurement condition 4: 20 μL of sample solution was injected into the instrument using THF containing 5 mmol / L triethylamine as the eluent. The guard column was a Tosoh Corporation "TSKguardcolumn SuperH-H" and the columns were Tosoh Corporation "TSKgel SuperH5000," "TSKgel SuperH6000," and "TSKgel SuperH7000." The column oven temperature was 40°C, and the THF flow rate was 0.6 mL / min. A chromatogram was obtained using an RI detector (Tosoh Corporation HLC8020). GPC measurement conditions using a silica column: A Tosoh HLC-8320GPC column was used, with THF as the eluent. 50 μL of sample solution was injected into the column oven at 40°C and a THF flow rate of 0.5 mL / min. Chromatograms were obtained using an RI detector. Zorbax PSM-1000S, PSM-300S, and PSM-60S columns were used, with a DIOL 4.6 x 12.5 mm 5-micron guard column connected to the column. Calculation method for modification rate: The total peak area of ​​the chromatogram using a polystyrene-based column was set to 100, the peak area of ​​the sample was set to P1, the peak area of ​​the standard polystyrene was set to P2, and the total peak area of ​​the chromatogram using a silica-based column was set to 100, the peak area of ​​the sample was set to P3, and the peak area of ​​the standard polystyrene was set to P4. The modification rate (%) was calculated using the following formula. Denaturation rate (%) = [1-(P2 x P3) / (P1 x P4)] x 100 (However, P1+P2=P3+P4=100)

[0280] (Example 1) Modified conjugated diene polymer (sample 1) Two tank-type pressure vessels with an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom and an outlet at the top, and an agitator-equipped tank-type reactor equipped with an agitator and a jacket for temperature control were connected together as polymerization reactors. 1,3-butadiene, which had been previously dehydrated, was mixed at 30.8 g / min and n-hexane at 189.3 g / min. In a static mixer installed midway through the pipe supplying this mixed solution to the reactor inlet, n-butyllithium, used for inactivating remaining impurities, was added at 0.072 mmol / min, mixed, and then continuously fed to the bottom of the reactor. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance at a rate of 0.012 mmol / min and n-butyllithium as a polymerization initiator at a rate of 0.279 mmol / min were fed to the bottom of the first reactor, which was being vigorously mixed with a stirrer, and the internal temperature of the reactor was maintained at 73 °C.

[0281] The polymer solution was continuously withdrawn from the top of the first reactor and fed continuously to the bottom of the second reactor, where the reaction continued at 73 °C. It was then fed to a static mixer from the top of the second reactor. Once the polymerization was sufficiently stable, trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was added as a branching agent at a rate of 0.027 mmol / min from the bottom of the second reactor while 1,3-butadiene was polymerizing. This allowed for the polymerization and branching reactions to proceed, yielding a branched conjugated diene polymer. Once the polymerization and branching reactions were stable, a small amount of the conjugated diene polymer solution before the addition of the modifier was withdrawn, and an antioxidant (BHT) was added at 0.2 g per 100 g of polymer. The solvent was then removed, and the Mooney viscosity of the resulting conjugated diene polymer was measured. The results are shown in Table 1. Next, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (abbreviated as "B" in the table) was continuously added as a modifier at a rate of 0.050 mmol / min to the polymer solution flowing out of the reactor outlet, and the mixture was mixed using a static mixer to carry out a modification reaction. It took 4.8 minutes for the modifier to be added to the polymer solution flowing out of the reactor outlet, and the temperature was 71°C. The difference between the temperature during the polymerization process and the temperature before the modifier was added was 2°C. After the modification reaction, a small amount of the conjugated diene polymer solution was withdrawn, and an antioxidant (BHT) was added in an amount of 0.2 g per 100 g of polymer, after which the solvent was removed.

[0282] Next, an antioxidant (BHT) was continuously added to the modified polymer solution at a rate of 0.055 g / min (n-hexane solution) to give 0.2 g per 100 g of polymer, terminating the modification reaction. The solvent was then removed by steam stripping to obtain a modified conjugated diene polymer (Sample 1) having a 4-branched structure derived from the branching agent (hereinafter also referred to as "branching agent structure"), a compound represented by formula (1) below, in a portion of the main chain, and a 4-branched star polymer structure derived from the modifier. Various physical properties of the sample were measured. The measurement results are shown in Table 1.

[0283] The structure of the modified conjugated diene polymer was identified by comparing the molecular weight measured by GPC with the branching degree measured by GPC with a viscometer for the polymer before the addition of the branching agent, the polymer before modification after the addition of the branching agent, and the polymer in each step after the addition of the modifier. The structure of each sample was identified in the same manner.

[0284] [ka] (In the formula, R 1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may have a branched structure in part, or an aryl group having 6 to 20 carbon atoms, R 2 ~R 3 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, which may have a branched structure in part, When there are a plurality of R1 to R3, they are independent of each other. X 1 indicates an independent halogen atom, m represents an integer of 0 to 2, n represents an integer of 0 to 3, l represents an integer of 0 to 3, and (m+n+l) is 3.

[0285] (Examples 2 to 29) Modified conjugated diene polymers (samples 2 to 29) Modified conjugated diene polymers (samples 2 to 29) were obtained in the same manner as in Example 1, except that the production conditions of Examples 2 to 29 shown in Tables 1 to 4 were changed from those of Example 1. Various physical properties of the samples were measured. The measurement results are shown in Tables 1 to 4. In the tables, "BS-2" to "BS-5" and "A," "C," to "G," and "J" shown as branching agents and modifiers respectively represent the following compounds (the same applies to Table 5). "BS-2": dimethylmethoxy(4-vinylphenyl)silane "BS-3": 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene (compound represented by the following formula (2)) "BS-4": 1,1-bis(4-trimethoxysilylphenyl)ethylene "BS-5": Trichloro(4-vinylphenyl)silane "A": 1,3-dimethylimidazolidinone "C": 1-[3-(trimethoxysilyl)-propyl]-4-methylpiperazine "D": N-benzylidene-3-(triethoxysilyl)propan-1-amine "E": 2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane "F": Tris(3-trimethoxysilylpropyl)amine "G": tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine "J": N-(3-(1H-imidazol-1-yl)propyl)-3-(triethoxysilyl)-N-(3-(triethoxysilyl)propyl)propan-1-amine [ka] (In the formula, R 2 ~R 5 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, which may have a branched structure in part, and when there are a plurality of R 2 ~R 5 are independent of each other, X 2 ~X 3 each represents an independent halogen atom, m represents an integer of 0 to 2, n represents an integer of 0 to 3, l represents an integer of 0 to 3, and (m+n+l) is 3; a represents an integer of 0 to 2, b represents an integer of 0 to 3, c represents an integer of 0 to 3, and (a+b+c) is 3.

[0286] (Comparative Example 1) Modified conjugated diene polymer (Sample 30) Two tank-type pressure vessels with an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom and an outlet at the top, and an agitator-equipped tank-type reactor equipped with an agitator and a jacket for temperature control were connected together as polymerization reactors. Pre-dehydrated 1,3-butadiene and n-hexane were mixed at 30.8 g / min and 189.3 g / min, respectively. A static mixer was installed in the pipe supplying this mixed solution to the reactor inlet, and n-butyllithium (used to inactivate remaining impurities) was added at 0.072 mmol / min. The mixture was then continuously fed to the bottom of the reactor. Furthermore, 2,2-bis(2-oxolanyl)propane (polar substance) was added at 0.012 mmol / min, and n-butyllithium (polymerization initiator) was added at 0.279 mmol / min. The mixture was vigorously mixed with a stirrer at the bottom of the first reactor, and the reactor temperature was maintained at 73 °C.

[0287] The polymer solution was continuously withdrawn from the top of the first reactor and continuously fed to the bottom of the second reactor, where the reaction continued at 73°C. It was then fed to a static mixer from the top of the second reactor. When the polymerization reaction was sufficiently stabilized, a small amount of the conjugated diene polymer solution before the addition of the modifier was withdrawn, and an antioxidant (BHT) was added in an amount of 0.2 g per 100 g of polymer. The solvent was then removed, and the Mooney viscosity of the conjugated diene polymer was measured. The measurement results are shown in Table 4.

[0288] Next, the polymer solution flowing out of the reactor outlet was continuously added with 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (abbreviated as "B" in the table) as a modifier at a rate of 0.073 mmol / min, and the mixture was mixed using a static mixer to carry out the modification reaction. The time required for the modifier to be added to the polymer solution flowing out of the reactor outlet was 4.8 minutes, and the temperature was 71°C. The temperature difference between the polymerization step and the temperature before the modifier was added was 2°C. After the modification reaction, a small amount of the conjugated diene polymer solution was withdrawn, and an antioxidant (BHT) was added in an amount of 0.2 g per 100 g of polymer. The solvent was then removed, and the microstructure of the butadiene moiety (1,2 vinyl bond content, 1,4 cis bond content: physical property 2) was measured. The measurement results are shown in Table 4.

[0289] Next, an antioxidant (BHT) was continuously added to the modified polymer solution at a rate of 0.055 g / min (n-hexane solution) to give 0.2 g per 100 g of polymer, and the modification reaction was terminated. The solvent was then removed by steam stripping to obtain a modified conjugated diene polymer (Sample 30), and various physical properties were measured. The measurement results are shown in Table 4.

[0290] (Comparative Examples 2 to 4) Modified conjugated diene polymers (Samples 31 to 33) Modified conjugated diene polymers (samples 31 to 33) were obtained and various physical properties were measured in the same manner as in Comparative Example 1, except that the production conditions of Comparative Examples 2 to 12 shown in Table 4 were changed from those of Comparative Example 1. The measurement results are shown in Table 4.

[0291] (Comparative Example 5) Conjugated diene polymer (Sample 34) The production conditions of Comparative Example 1 were changed to those of Comparative Example 5 shown in Table 5, and when the polymerization reaction was sufficiently stabilized, a branching agent was added to carry out a polymerization reaction and a branching reaction to obtain a conjugated diene-based polymer having a branched structure. Thereafter, a conjugated diene-based polymer (Sample 34) was obtained in the same manner as Comparative Example 1, except that no modifier was added, and various physical properties were measured. The measurement results are shown in Table 5.

[0292] (Comparative Examples 6 and 7) Conjugated diene polymers (Samples 35 and 36) Conjugated diene polymers (samples 35 and 36) were obtained and measured for various physical properties in the same manner as in Comparative Example 6, except that the production conditions of Comparative Example 5 were changed to those of Comparative Examples 7 and 8 shown in Table 5. The measurement results are shown in Table 5.

[0293] (Comparative Example 8) Modified conjugated diene polymer (Sample 37) The production conditions of Comparative Example 9 shown in Table 5 were changed from those of Comparative Example 1, and when the polymerization reaction was sufficiently stable, a branching agent was added to carry out a polymerization reaction and branching reaction to obtain a conjugated diene polymer having a branched structure. Thereafter, a modified conjugated diene polymer (Sample 37) was obtained in the same manner as Comparative Example 1, except that a modifier was added when the polymerization reaction and branching reaction were sufficiently stable, and various physical properties were measured. The measurement results are shown in Table 5. In the table, "H" shown as a modifier represents the following compound. "H": Tetraethoxysilane

[0294] (Comparative Examples 9 to 13) Modified conjugated diene polymers (Samples 38 to 42) Modified conjugated diene polymers (samples 38 to 42) were obtained and their physical properties were measured in the same manner as in Comparative Example 8, except that the production conditions of Comparative Examples 9 to 13 shown in Table 5 were changed from those of Comparative Example 8. The measurement results are shown in Table 5. In the table, "I" shown as a modifier represents the following compound. "I": 1,2-bis(triethoxysilyl)ethane

[0295] (Comparative Example 15) Conjugated diene polymer (Sample 43) A product name "Buna CB24" manufactured by ARLANXEO (Nd-based high cis BR, ML viscosity (100°C) 45) was prepared as sample 43.

[0296] [Table 1]

[0297] [Table 2]

[0298] [Table 3]

[0299] [Table 4]

[0300] [Table 5]

[0301] (Examples 30 to 58 and Comparative Examples 15 to 28) Using samples 1 to 43 shown in Tables 1 to 5 as raw rubbers, rubber compositions containing each raw rubber were obtained according to the formulations shown below.

[0302] (rubber component) (Modified) conjugated diene polymers (samples 1-43) :50 parts by mass Natural rubber RSS#3 :50 parts by mass

[0303] (Combination conditions) The amount of each compounding ingredient added is shown in parts by mass per 100 parts by mass of the rubber component. Silica (product name "Ultrasil 7000GR" manufactured by Evonik Degussa) Nitrogen adsorption specific surface area 170m2 / g): 50.0 parts by mass Carbon black (product name "Seat 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): 4.5 parts by mass SRAE oil (product name "Process NC140" manufactured by JX Nippon Oil & Energy Corporation) :30.0 parts by mass ·Zinc white: 2.5 parts by mass Stearic acid: 1.0 parts by weight Antioxidant (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 2.0 parts by mass ·Sulfur: 2.2 parts by mass Vulcanization accelerator 1 (N-cyclohexyl-2-benzothiazylsulfinamide) :1.7 parts by mass Vulcanization accelerator 2 (diphenyl guanidine): 2.0 parts by mass ·Total: 200.9 parts by mass

[0304] (Kneading method) The above materials were kneaded by the following method to obtain rubber compositions. Using an internal kneader (0.3 L capacity) equipped with a temperature control device, the raw rubber (samples 1 to 43), fillers (silica, carbon black), silane coupling agent, SRAE oil, zinc oxide, and stearic acid were kneaded in the first stage at a filling rate of 65% and a rotor rotation speed of 30 to 50 rpm. The temperature of the internal mixer was controlled, and each rubber composition (compound) was obtained at a discharge temperature of 155 to 160°C. Next, in the second stage of mixing, the compound obtained above was cooled to room temperature, and then an antioxidant was added. The compound was then mixed again to improve dispersion of the silica. Again, the temperature of the mixer was controlled to 155-160°C to adjust the discharge temperature of the compound to 155-160°C. After cooling, in the third stage of mixing, sulfur and vulcanization accelerators 1 and 2 were added and mixed using an open roll set at 70°C. The mixture was then molded and vulcanized in a vulcanization press at 160°C for 20 minutes. The rubber compositions before and after vulcanization were evaluated. Specifically, the evaluations were performed using the following methods. The results are shown in Tables 6 to 8.

[0305] (Rating 1) Cold flow property Samples 1 to 43 were cut from the bale to a sample size of L x W x H = 40 mm x 40 mm x 50 mm, a 1 kg load was placed on each sample, and the sample was left to stand for 24 hours in an environment at 40°C. After leaving the sample to stand for 24 hours, the height (H) of each sample was measured, and the average retention rate of two samples was calculated. The result of Comparative Example 15 was set at 100, and the result was indexed. A higher index indicates better cold flow properties.

[0306] (Evaluation 2) Compound Mooney Viscosity The compound obtained above after the second stage mixing but before the third stage mixing was used as a sample, and after preheating at 130°C for 1 minute, the rotor was rotated at 2 revolutions per minute for 4 minutes, and the viscosity was measured using a Mooney viscometer in accordance with ISO 289. The result of Comparative Example 15 was set to 100 and indexed. A smaller index indicates better processability.

[0307] (Evaluation 3) Tensile strength and tensile elongation The tensile strength and tensile elongation were measured in accordance with the tensile testing method of JIS K6251, and the result of Comparative Example 15 was indexed as 100. A larger index indicates better tensile strength and tensile elongation (breaking strength).

[0308] (Rating 4) Abrasion resistance Using an Acron abrasion tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), the amount of wear was measured at a load of 44.4 N and 1,000 revolutions in accordance with JIS K6264-2, and the result of Comparative Example 15 was indexed as 100. A larger index indicates better abrasion resistance.

[0309] (Evaluation 5) Viscoelastic parameters Viscoelastic parameters were measured in torsion mode using an ARES viscoelasticity tester manufactured by Rheometrics Scientific Inc. Each measurement value was indexed, with the result for the rubber composition of Comparative Example 15 being set at 100. Tan δ measured at 0°C, a frequency of 10 Hz, and a strain of 1% was used as an index of wet grip performance. A higher index indicates better wet grip performance. In addition, tan δ measured at 50°C, a frequency of 10 Hz, and a strain of 3% was used as an index of fuel economy. A larger index indicates better fuel economy.

[0310] [Table 6]

[0311] [Table 7]

[0312] [Table 8]

[0313] As shown in Tables 6 to 8, compared with Comparative Examples 15 to 28, Examples 30 to 58 exhibited low Mooney viscosity of the compound when vulcanized, exhibiting good processability, and it was confirmed that when vulcanized, they had an excellent balance between low hysteresis loss and wet skid resistance. [Industrial Applicability]

[0314] The conjugated diene polymer according to the present invention has industrial applicability in the fields of tire treads, interior and exterior parts of automobiles, vibration-proof rubber, belts, footwear, foams, various industrial products, and the like. [Explanation of symbols]

[0315] A...Branching degree of 1 / 2Hi polymer, B...Image of branching degree distribution of main chain branched polymer (distribution in which the higher the molecular weight than the average for the entire polymer, the higher the branching), C...Image of branching degree distribution of simple star branching (distribution that is basically constant depending on the number of functions of the modifier).

Claims

1. the degree of branching (Bn) of the polymer at 1 / 2Hi as measured by GPC-light scattering method with a viscosity detector is 7 or more; The degree of branching (Bn) of the polymer at ½ Hi is, based on the height of a peak top in an absolute molecular weight curve (provided that, in the case where a plurality of peak tops exist in the absolute molecular weight curve, the height of the peak top having the maximum absolute molecular weight: Hi), and is the degree of branching (Bn) of the polymer at the highest absolute molecular weight among at least two absolute molecular weights when the height in the absolute molecular weight curve is ½ the height (½ Hi) of Hi, It has a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and the moiety derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group has a branched structure, The Mooney viscosity measured at 100°C is 30 or more and 120 or less, the amount of 1,2 vinyl bonds is 25 mol% or less, and the amount of 1,4 cis bonds is 40 mol% or less, A nitrogen atom-containing conjugated diene polymer having a branching degree (Bn) of 4 or more and 25 or less as measured by a GPC-light scattering method with a viscosity detector.

2. The conjugated diene polymer according to claim 1, wherein the modification rate measured by column adsorption GPC is 60% by mass or more.

3. The moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group is a monomer unit derived from a compound represented by the following formula (1) or (2):

2. The conjugated diene polymer according to claim 1, having a polymer chain branching point due to a monomer unit derived from a compound represented by the following formula (1) or (2): 【Chemistry 1】 (In the formula, R 1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may have a branched structure in part, or an aryl group having 6 to 20 carbon atoms, R 2 ~R 3 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, which may have a branched structure in part, When there are a plurality of R1 to R3, they are independent of each other. X 1 indicates an independent halogen atom, m represents an integer of 0 to 2, n represents an integer of 0 to 3, l represents an integer of 0 to 3, and (m+n+l) is 3. 【Chemistry 2】 (In the formula, R 2 ~R 5 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, which may have a branched structure in part, and when there are a plurality of R 2 ~R 5 are independent of each other, X 2 ~X 3 each represents an independent halogen atom, m represents an integer of 0 to 2, n represents an integer of 0 to 3, l represents an integer of 0 to 3, and (m+n+l) is 3; a represents an integer of 0 to 2, b represents an integer of 0 to 3, c represents an integer of 0 to 3, and (a+b+c) is 3.

4. The compound has a monomer unit derived from the compound represented by formula (1), and in formula (1), R 1 The conjugated diene polymer according to claim 3 , wherein represents a hydrogen atom and m represents 0.

5. The conjugated diene polymer according to claim 3 , which has a monomer unit derived from a compound represented by formula (2), wherein m is 0 and b is 0.

6. The compound has a monomer unit derived from the compound represented by formula (1), and in formula (1), R 1 The conjugated diene polymer according to claim 3 , wherein: represents a hydrogen atom; m represents 0; n represents 3; and 1 represents 0.

7. The conjugated diene-based polymer according to claim 3, which has a monomer unit derived from a compound represented by formula (2), wherein in formula (2), m represents 0, n represents 3, 1 represents 0, a represents 0, b represents 0, and c represents 3.

8. a polymerization and branching step of polymerizing a conjugated diene compound using an organolithium compound as a polymerization initiator while adding a branching agent to obtain a conjugated diene-based polymer having a branched structure; The method for producing a conjugated diene polymer according to any one of claims 1 to 7, further comprising: a modification step of modifying the conjugated diene polymer with a modifying agent.

9. The rubber composition includes a rubber component and a filler in an amount of 5.0 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the rubber component, A rubber composition, wherein the rubber component contains 10% by mass or more of the conjugated diene polymer according to any one of claims 1 to 7, relative to 100% by mass of the total amount of the rubber component.

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