Conjugated diene polymer, method for producing conjugated diene polymer, conjugated diene polymer composition, and rubber composition

Abstract

To provide a conjugated diene-based polymer which is excellent in tensile strength, abrasion resistance and low hysteresis loss properties when being formed into a vulcanizate.SOLUTION: A conjugated diene-based polymer has a branch degree (Bn) of 7 or more by a measurement method of a GPC-light scattering method with a viscosity detector, and a weight average molecular weight of 45×104 or more and 500×104 or less. In the conjugated diene-based polymer, a content of an aromatic vinyl monomer unit is 30-45 mass%, and a value of a content (mass%) of the aromatic vinyl monomer unit is larger than a value of a vinyl bond amount (mol%) in the conjugated monomer unit.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] 2. Description of the Related Art There has been an increasing demand for improved fuel economy in automobiles, and this has led to 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. In recent years, due to increasing fuel efficiency regulations for automobiles, there is a trend to reduce the weight of automobiles by using resin components, etc., and with regard to tires, there is also an increasing demand for thinner tire components from the perspective of weight reduction.

[0003] In order to reduce the weight of tires, it is necessary to reduce the thickness of the tread portion, which comes into contact with the road surface and has a high rubber material ratio. For this reason, rubber materials with superior tensile strength compared to conventional materials are required for the tread portion. Furthermore, in order to reduce energy loss caused by tires during running, the rubber material used in tire treads is required to have low rolling resistance, i.e., low hysteresis loss. On the other hand, from the viewpoint of safety, the material is required to have abrasion resistance sufficient for practical use.

[0004] As a rubber material that meets the above-mentioned requirements, for example, there is a rubber composition containing a rubber-like polymer having a predetermined structure and a reinforcing filler such as carbon black or silica. That is, by introducing a functional group having affinity or reactivity with silica to the molecular terminal of a rubber-like polymer having high mobility, the dispersibility of the silica in the rubber composition is improved, and further, the mobility of the molecular terminal of the rubber-like polymer is reduced by bonding with the silica particles, thereby reducing hysteresis loss and improving abrasion resistance and breaking strength.

[0005] For example, Patent Documents 1 to 3 propose rubber compositions containing silica and a modified conjugated diene polymer obtained by reacting an alkoxysilane containing an amino group with an active terminal of a conjugated diene polymer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-290355 A [Patent Document 2] Japanese Patent Application Publication No. 11-189616 [Patent Document 3] JP 2003-171418 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the rubber compositions proposed so far, silica has a hydrophilic surface in contrast to carbon black, which has a hydrophobic surface, and therefore has a low affinity with the conjugated diene polymer, resulting in a problem that the dispersibility of silica in the rubber composition is poorer than that of carbon black. Therefore, a rubber composition containing silica needs to contain a separate silane modifier or the like in order to provide a bond between the silica and the conjugated diene polymer and improve the dispersibility in the rubber composition.

[0008] Furthermore, when a functional group having high reactivity with silica is introduced to 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 rubber composition, which tends to deteriorate the processability, such as making kneading difficult, or causing rough skin or making the sheet more likely to break when made into a sheet after kneading.

[0009] Furthermore, the above-mentioned conventionally proposed rubber compositions containing silica have a problem in that when the rubber composition is vulcanized, the balance of tensile strength, abrasion resistance, and low hysteresis loss is not sufficient.

[0010] Therefore, an object of the present invention is to provide a conjugated diene polymer which, when vulcanized, gives a rubber composition excellent in tensile strength, abrasion resistance and low hysteresis loss. [Means for solving the problem]

[0011] As a result of intensive research and investigation to solve the problems of the above-mentioned conventional techniques, the present inventors have found that a conjugated diene-based copolymer having a branching degree (Bn) of a specific value or more, a weight average molecular weight in a specific numerical range, an aromatic vinyl monomer unit content in a specific numerical range, and a specific relationship between the aromatic vinyl monomer unit content (mass %) and the vinyl bond amount (mol %) in the conjugated diene monomer unit is excellent in tensile strength, abrasion resistance, and low hysteresis loss when vulcanized, thereby completing the present invention. That is, the present invention is as follows.

[0012] [1] The branching degree (Bn) measured by a GPC-light scattering method with a viscometer is 7 or more. Weight average molecular weight is 45 x 10 4 More than 500 x 10 4 A conjugated diene-based polymer having the following structure: The content of aromatic vinyl monomer units in the conjugated diene polymer is 30 to 45 mass %, A conjugated diene polymer in which the content (mass%) of aromatic vinyl monomer units is greater than the amount (mol%) of vinyl bonds in the conjugated diene monomer units. [2] The conjugated diene polymer according to [1] above, wherein the conjugated diene polymer has a modification rate of 60% by mass or more as measured by a column adsorption GPC method. [3] The conjugated diene polymer according to [1] or [2] above, which contains a nitrogen atom and a silicon atom. [4] The conjugated diene polymer has a star polymer structure with three or more branches, At least one branched chain of the star-shaped structure 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 further main chain branched structure. The conjugated diene polymer according to any one of [1] to [3] above. [5] The conjugated diene polymer according to [4] above, wherein the vinyl monomer containing an alkoxysilyl group or a halosilyl group is a compound represented by the following formula (1) or (2):

[0013] [ka]

[0014] [ka]

[0015] (In formula (1), R 1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, which may partially have a branched structure. 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 partially have a branched structure. R when multiple exist 1 ~R 3 are each independent. X 1 represents an independent halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3.) (In formula (2), R 2 ~R 5Each of R independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and may partially have a branched structure. 2 ~R 5 are each independent. X 2 ~X 3 represents an independent halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3. a represents an integer of 0 to 2, b represents an integer of 0 to 3, and c represents an integer of 0 to 3. (a+b+c) represents 3.)

[0016] [6] In the formula (1), R 1 is a hydrogen atom, and m=0. [7] The conjugated diene polymer according to [5] above, having a monomer unit based on a compound represented by formula (2), in which m=0 and b=0. [8] In the formula (1), R 1 is a hydrogen atom, m=0, l=0, and n=3. [9] The conjugated diene polymer according to [5] above, having a monomer unit based on a compound represented by formula (2), in which m=0, l=0, n=3, a=0, b=0, and c=3.

[10] A method for producing the conjugated diene polymer according to any one of [1] to [9], A method for polymerizing at least a conjugated diene compound and an aromatic vinyl compound in a solvent containing a polar compound by using an organolithium compound as a polymerization initiator, It is a vinyl monomer containing an alkoxysilyl group or a halosilyl group represented by the formula (1) or (2).A method for producing a conjugated diene polymer, comprising the step of adding a branching agent to obtain a conjugated diene polymer having a main chain branched structure.

[11] The conjugated diene polymer having a main chain branched structure is It is a reactive compound with two or more functional groups. The method for producing a conjugated diene polymer according to

[10] above, further comprising a step of reacting a coupling agent.

[12] 100 parts by mass of the conjugated diene polymer according to any one of [1] to [9] above; 1 to 60 parts by mass of a rubber softener; A conjugated diene polymer composition comprising:

[13] A rubber composition comprising a rubber component and 5.0 parts by mass or more and 150 parts by mass or less of a filler per 100 parts by mass of the rubber component, The rubber component comprises 10 parts by mass or more of the conjugated diene polymer according to any one of [1] to [9] above, relative to 100 parts by mass of the total amount of the rubber component. Effect of the Invention

[0017] According to the present invention, a conjugated diene polymer which, when vulcanized, is excellent in tensile strength, abrasion resistance, and low hysteresis loss can be obtained. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention (hereinafter, referred to as "the present embodiment") will be described in detail. It should be noted that the following embodiment is merely an example for explaining the present invention, and the present invention is not limited to the following embodiment. The present invention can be practiced with appropriate modifications within the scope of the gist of the present invention.

[0019] [Conjugated diene polymer] The conjugated diene polymer of the present embodiment is The branching degree (Bn) measured by a GPC-light scattering method with a viscometer is 7 or more. Weight average molecular weight is 45 x 10 4More than 500 x 10 4 The conjugated diene polymer is the following conjugated diene polymer, in which the content of aromatic vinyl monomer units in the conjugated diene polymer is 30 to 45 mass%, and the content (mass%) of the aromatic vinyl monomer units is greater than the amount of vinyl bonds (mol%) in the conjugated diene monomer units.

[0020] As described above, by specifying the degree of branching (Bn), the weight average molecular weight, the content of aromatic vinyl monomer units, and the magnitude relationship between the "value of the content of aromatic vinyl monomer units" and the "value of the vinyl bond amount in the conjugated diene monomer units", it is possible to obtain a conjugated diene-based polymer which has excellent processability when vulcanized and has excellent tensile strength and abrasion resistance when vulcanized.

[0021] (Branching degree (Bn)) From the viewpoints of processability, abrasion resistance, and breaking strength, the conjugated diene polymer of the present embodiment has a branching degree (Bn) measured by a GPC-light scattering method with a viscosity detector (hereinafter, sometimes simply referred to as the branching degree (Bn)) of 7 or more. The degree of branching (Bn) of 7 or more means that the conjugated diene polymer of the present embodiment substantially has 7 or more side polymer chains relative to the longest polymer main chain. The branching degree (Bn) of a conjugated diene polymer is defined as g'=6Bn / [(Bn+1)(Bn+2)], where g' is a shrinkage factor measured by a GPC-light scattering method with a viscosity detector. In general, a polymer having branches tends to have a smaller molecular size when compared to a linear polymer having the same absolute molecular weight. 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. In the conjugated diene polymer of the present embodiment, when the intrinsic viscosity is used as an index of molecular size with respect to this shrinkage factor, the linear polymer has an intrinsic viscosity [η]=−3.883M 0.771In the above formula, M is the absolute molecular weight. However, the shrinkage factor represents the rate of reduction in molecular size and does not accurately represent the branched structure of a polymer. Therefore, the branching degree (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 "branching degree (Bn)" accurately represents the number of polymers that are directly or indirectly bonded to each other with respect to the longest main chain structure. 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 bonded to the longest highly branched main chain structure, and the branching degree (Bn) is evaluated as 2. In the case of an 8-branched star polymer, six polymer chain arms are attached to the longest highly branched main chain structure, and the branching degree (Bn) is evaluated as 6. The conjugated diene polymer of the present embodiment has a branching degree (Bn) of 7 or more, which means that 7 polymer chain arms are bonded to the longest highly branched main chain structure, and the conjugated diene polymer has branches similar to those of a 9-branched star polymer structure. Here, "branch" refers to a structure formed by directly or indirectly bonding 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. Since the conjugated diene polymer of the present embodiment has a degree of branching (Bn) of 7 or more, the conjugated diene polymer has extremely excellent processability when vulcanized, and when vulcanized, has excellent abrasion resistance and puncture strength.

[0022] In general, as the absolute molecular weight of a conjugated diene polymer increases, its processability tends to deteriorate. When the absolute molecular weight of a conjugated diene polymer having a linear polymer structure is increased, the viscosity of the polymer when vulcanized increases significantly, and the processability deteriorates significantly. Therefore, even if a large number of functional groups are introduced into the conjugated diene polymer to improve the affinity and / or reactivity with the silica blended as a filler, the silica cannot be sufficiently dispersed in the conjugated diene polymer in the kneading step, and as a result, the function of the introduced functional groups is not exerted, and the effect of improving the low hysteresis loss property by introducing the functional groups, which should be expected, tends not to be exerted. On the other hand, the conjugated diene polymer of the present embodiment is specified to have a branching degree (Bn) of 7 or more, and thus the increase in viscosity during vulcanization due to an increase in absolute molecular weight is significantly suppressed. For example, the conjugated diene polymer is sufficiently mixed with silica or the like in the kneading process, and it becomes possible to disperse silica around the conjugated diene polymer. As a result, for example, by setting the molecular weight of the conjugated diene polymer to be large, it becomes possible to improve abrasion resistance and tensile strength, and by sufficiently kneading, it becomes possible to disperse silica around the polymer, and the functional group can act and / or react, and a rubber composition having low hysteresis loss sufficient for practical use can be obtained. The absolute molecular weight of the conjugated diene polymer can be measured by the method described in the examples below.

[0023] The degree of branching (Bn) of the conjugated diene polymer of the present embodiment is not less than 7, preferably not less than 8, and more preferably not less than 9. A conjugated diene polymer having a degree of branching (Bn) within this range tends to have excellent processability when made into a vulcanizate. The upper limit of the branching degree (Bn) of the conjugated diene polymer is not particularly limited and may be equal to or higher than the detection limit, but is preferably 84 or less, more preferably 80 or less, even more preferably 64 or less, and even more preferably 57 or less. The conjugated diene polymer of the present embodiment has a degree of branching (Bn) of 84 or less, and therefore tends to have excellent abrasion resistance when vulcanized.

[0024] The degree of branching of the conjugated diene polymer of the present embodiment can be controlled by adjusting the amount of the branching agent added, and can be controlled to 7 or more by adjusting the combination of the amount of the branching agent added and the amount of the terminal coupling agent added, or by adjusting the modifying agent having a nitrogen atom-containing group. Specifically, the degree of branching can be controlled by adjusting the number of functional groups of the branching agent, the amount of the branching agent added, the timing of adding the branching agent, the number of functional groups of the coupling agent or the nitrogen atom-containing modifier, and the amount of the coupling agent or the nitrogen atom-containing modifier added, as described in more detail in the method for producing a conjugated diene polymer described later.

[0025] (monomer) The conjugated diene polymer of the present embodiment contains a conjugated diene compound and an aromatic vinyl compound as compounds that form monomer units.

[0026] Examples of conjugated diene compounds include, but are not limited to, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. Among these, 1,3-butadiene and isoprene are preferred from the viewpoint of industrial availability. These may be used alone or in combination of two or more.

[0027] Examples of aromatic vinyl compounds include, but are not limited to, styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred from the viewpoint of industrial availability. These may be used alone or in combination of two or more.

[0028] (Coupling Agent) The conjugated diene polymer of the present embodiment may be one obtained by subjecting the active terminal of the conjugated diene polymer obtained in the polymerization step to a coupling reaction using a reactive compound (hereinafter also referred to as a coupling agent). The coupling agent used in the coupling reaction step may be a bifunctional or higher reactive compound of any structure, but is preferably a bifunctional or higher reactive compound having a silicon atom. More specifically, this will be described later in the method for producing a conjugated diene polymer. By using a reactive compound having a silicon atom as the coupling agent, the conjugated diene polymer of the present embodiment has a silicon atom.

[0029] The conjugated diene polymer of the present embodiment preferably contains a nitrogen atom. The nitrogen atom-containing conjugated diene polymer can be obtained, for example, by carrying out a coupling reaction using a modifying agent having a nitrogen atom-containing group described below, or by using an organomonolithium compound having a substituted amino group as a polymerization initiator.

[0030] (Nitrogen atom content) The conjugated diene polymer of the present embodiment preferably has a nitrogen atom content of 5 ppm by mass or more relative to the total amount of the conjugated diene polymer. The nitrogen atom content (hereinafter sometimes referred to as "nitrogen content") is the total amount of nitrogen atoms in the nitrogen-containing functional groups of the conjugated diene polymer, for example, in the initiation terminal, in the main chain, and at the terminal terminal. The nitrogen content of the conjugated diene polymer is more preferably 8 ppm by mass or more, further preferably 10 ppm by mass or more, and even more preferably 13 ppm by mass or more, based on the total amount of the conjugated diene polymer. By setting the content within the above range, when the conjugated diene-based polymer of the present embodiment is vulcanized, the balance between low hysteresis loss and wet skid resistance tends to be excellent. Furthermore, in the polymerization step of the conjugated diene polymer of this embodiment, when an organomonolithium compound having a substituted amino group is used as a polymerization initiator, from the viewpoint of suppressing a chain transfer reaction during polymerization, the nitrogen content of the conjugated diene polymer is preferably 150 ppm by mass or less, more preferably 100 ppm by mass or less, and even more preferably 80 ppm by mass or less. The nitrogen content can be measured by an oxidation combustion-chemiluminescence method (JIS-2609: Crude oil and crude oil products-Determination of nitrogen content). More specifically, it can be measured by the method described in the examples below.

[0031] (Modifier having a nitrogen atom-containing group) The conjugated diene polymer of the present embodiment is preferably a conjugated diene polymer obtained by subjecting an active terminal of a conjugated diene polymer obtained through a polymerization process and further a branching process to a coupling reaction with a reactive compound having a nitrogen atom-containing group (hereinafter, also referred to as a "modifier having a nitrogen atom-containing group"). In particular, it is more preferable to use a coupling agent having a nitrogen atom-containing group and a di- or higher functional group reacted with the polymerization termination terminal.

[0032] A conjugated diene polymer coupled with a modifier having a nitrogen atom-containing group tends to provide good dispersibility of silica and good processability when used in a rubber composition containing a filler such as silica, and also tends to provide a dramatically improved balance between low hysteresis loss and wet skid resistance when vulcanized. More specifically, this will be described later in the method for producing a conjugated diene polymer.

[0033] Examples of the modifying agent having a nitrogen atom-containing group include, but are not limited to, an isocyanate compound, an isothiocyanate compound, an isocyanuric acid derivative, a nitrogen group-containing carbonyl compound, a nitrogen group-containing vinyl compound, and a nitrogen group-containing epoxy compound. The modifying agent having a nitrogen atom-containing group preferably has a nitrogen atom-containing functional group, and the nitrogen atom-containing functional group is 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, and alkoxysilane compounds bonded to the nitrogen atom-containing group. More specifically, this will be described later in the method for producing a conjugated diene polymer.

[0034] (Modification rate of conjugated diene polymer) The conjugated diene polymer of the present embodiment preferably has a modification rate of 60% by mass or more as measured by column adsorption GPC method. In this specification, the "modification ratio" represents the mass ratio of the conjugated diene polymer having a nitrogen atom-containing functional group to the total amount of the conjugated diene polymer. For example, when a modifying agent having a nitrogen atom-containing group is reacted with the terminal end of a polymer, the mass ratio of the conjugated diene-based polymer having a nitrogen atom-containing functional group by the modifying agent having a nitrogen atom-containing group to the total amount of the conjugated diene-based polymer is expressed as the modification rate. On the other hand, when a polymer is branched by a branching agent containing a nitrogen atom, the resulting conjugated diene polymer has a nitrogen atom-containing functional group, and therefore, this branched polymer is also counted when calculating the modification rate. That is, in this specification, the "modification rate" refers to the total mass ratio of a polymer subjected to a coupling reaction with a modifying agent having a nitrogen atom-containing functional group and / or a polymer branched with a branching agent having a nitrogen atom-containing functional group.

[0035] The conjugated diene polymer of the present embodiment has at least one end modified with a modifier having a nitrogen atom-containing group, which improves processability when made into a rubber composition containing a filler or the like, and tends to provide a dramatic improvement in low hysteresis loss while maintaining the abrasion resistance and fracture strength when the rubber composition is made into a vulcanizate.

[0036] 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. The modification rate is preferably 70% by mass or more, more preferably 75% by mass or more, and further preferably 80% by mass or more. The upper limit of the modification rate is not particularly limited, but is, for example, 98% by mass. When the modification rate is within the above range, the dispersibility of silica in the vulcanized product is improved, and the product has excellent low hysteresis loss.

[0037] The degree of modification can be measured by chromatography, which is capable of separating the functional group-containing modified and unmodified components. Examples of methods using chromatography include a method in which a column for gel permeation chromatography is used, packed with a polar substance such as silica that adsorbs specific functional groups, and the non-adsorbed components are quantified using an internal standard for comparison (column adsorption GPC method). More specifically, the modification rate can be obtained by measuring the amount of a sample adsorbed to a silica column from the difference between a chromatogram measured using a polystyrene-based gel column and a chromatogram measured using a silica-based column, using a sample solution containing the sample and a low-molecular-weight internal standard polystyrene. More specifically, the modification rate can be measured by the method described in the Examples.

[0038] In the conjugated diene polymer of the present embodiment, the modification rate can be controlled to 60% by mass or more by adjusting the amount of modifier added and the reaction method, and the amount of branching agent added and the reaction method. For example, the above modification rate can be controlled by appropriately 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, a method of using a branching agent having at least one nitrogen atom in the molecule, and a method of using a modifying agent having a structural formula described below, and adjusting the polymerization conditions and reaction conditions.

[0039] (Branched Structure of Conjugated Diene Polymer) From the viewpoint of a balance between processability and abrasion resistance, the conjugated diene polymer of the present embodiment is preferably a conjugated diene polymer having a star polymer structure with three or more branches, at least one branched chain of the star structure having 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 further main chain branched structure.

[0040] The portion derived from the vinyl monomer containing the alkoxysilyl group or halosilyl group is a portion containing silylbenzene in the conjugated diene polymer. When the vinyl monomer, which is a branching agent, reacts with the polymer chain, the OH of the alkoxysilyl group or the halogen of the halosilyl group contained in the branching agent becomes a leaving group, and the polymer active end is substituted and bonded. In addition, the vinyl structure of the vinyl monomer is polymerized as a conjugated diene to generate a branched structure. As a result, a structure in which a polymer chain is bonded to the silicon of the silylbenzene is generated, and this structure is called the portion derived from the vinyl monomer. When the vinyl monomer has multiple leaving groups, multiple polymer chains can be bonded to the silicon of the silylbenzene, and the silylbenzene to which multiple polymer chains are bonded is also naturally a portion derived from the vinyl monomer.

[0041] As used herein, the term "star polymer structure" refers to a structure in which multiple polymer chains (arms) are bonded to one central branch point. Furthermore, one of the central branch points herein has a substituent containing an atom derived from a coupling agent or a nitrogen atom derived from a modifier. The term "main chain branched structure" as used herein refers to a structure in which a polymer chain forms a branch point at a portion derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and the polymer chain (arm) further extends from the branch point. In particular, in the case of a main chain branched structure consisting of a vinyl monomer containing an alkoxysilyl group or a halosilyl group, 29 When signal detection is performed by Si-NMR, peaks derived from the main chain 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.

[0042] From the viewpoint of improving the branching degree (Bn), the conjugated diene polymer of the present embodiment preferably has two or more main chain branching points constituted by the portion derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group, and the branched structure derived from the star polymer structure formed by the coupling agent in the reaction step carried out after the polymerization and branching steps preferably has three or more branches, more preferably has four or more branches, and even more preferably has eight or more branches. As described above, the portion derived from the vinyl monomer refers to a structure containing silylbenzene. In addition, the degree of branching (Bn) increases both when the polymer is modified with a coupling agent that forms a star structure and when a branching agent is introduced into the polymer, but branching the entire polymer chain with a coupling agent contributes more to the degree of branching (Bn). In designing a polymer, the degree of branching (Bn) can be controlled by selecting a coupling agent and the type and amount of branching agent added, but it is often easier to control the degree of branching (Bn) by taking into account the contribution rate.

[0043] (Main chain branched structure) In the conjugated diene polymer of the present embodiment, the main chain branched structure preferably has two or more branch points, more preferably three or more branch points, and further preferably four or more branch points, in a portion derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group. In addition, the branch points forming the main chain branched structure preferably have at least two or more polymer chains, more preferably have three 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.

[0044] (star-shaped polymer structure) The conjugated diene polymer of the present embodiment preferably has a star polymer structure, and the number of branches derived from the star polymer structure is preferably 3 or more, more preferably 4 or more, even more preferably 6 or more, and even more preferably 8 or more. A preferred embodiment of the conjugated diene polymer of the present invention is a conjugated diene polymer having a star-shaped polymer structure with three or more branches, in which at least one branch chain of the star-shaped structure has a portion 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 has a further main chain branch structure. Regarding the method for obtaining a conjugated diene polymer having such a structure, the "star-shaped polymer structure" can be formed by adjusting the number of functional groups of the coupling agent and the amount of the coupling agent added, and the "main chain branch structure" can be controlled by adjusting the number of functional groups of the branching agent, the amount of the branching agent added, and the timing of adding the branching agent. A specific production method includes a method in which an organolithium compound is used as a polymerization initiator to carry out polymerization, a branching agent which provides specific branching points is added during or after the polymerization, and the polymerization is continued, followed by modification with a modifying agent which provides a specific branching rate. Such means for controlling the polymerization conditions will be described in the production method in the examples given below.

[0045] (Details of main chain branch structure) In the conjugated diene polymer of the present embodiment, the portion derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group is preferably a monomer unit based on a compound represented by the following formula (1) or (2), and the polymer chain preferably has a branching point due to the monomer unit based on a compound represented by the following formula (1) or (2). The conjugated diene polymer of the present embodiment is more preferably a conjugated diene polymer obtained by using a coupling agent, 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.

[0046] [ka]

[0047] [ka]

[0048] (In formula (1), R 1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, which may partially have a branched structure. 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 partially have a branched structure. R when multiple exist 1 ~R 3 are each independent. X 1 represents an independent halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3.) (In formula (2), 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 partially have a branched structure. R when multiple exist 2 ~R 5are each independent. X 2 ~X 3 represents an independent halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) means 3. a represents an integer of 0 to 2, b represents an integer of 0 to 3, and c represents an integer of 0 to 3. (a+b+c) represents 3.)

[0049] The conjugated diene polymer of the present embodiment is represented by the formula (1) above, R 1 is a hydrogen atom and m = 0. This increases the number of branches, and provides the effect of improving abrasion resistance and processability.

[0050] Moreover, the conjugated diene polymer of the present embodiment is preferably a conjugated diene polymer having a monomer unit based on the compound represented by the formula (2) in which m = 0 and b = 0. This provides an effect of improving abrasion resistance and processability.

[0051] The conjugated diene polymer of the present embodiment is preferably a conjugated diene polymer having monomer units based on the compound represented by formula (2) in which m = 0, l = 0, n = 3, a = 0, b = 0, and c = 3. This provides the effect of improving abrasion resistance and processability.

[0052] In addition, the conjugated diene polymer of the present embodiment is a polymer represented by the formula (1), 1 It is more preferable that the polymer is a conjugated diene-based polymer having monomer units based on the compound represented by formula (1) in which m is a hydrogen atom, m is 0, l is 0, and n is 3. This improves the modification rate and the degree of branching, and provides the effects of improving fuel saving performance, abrasion resistance, and processability.

[0053] (Branching Agent) In the conjugated diene polymer of the present embodiment, when constructing a main chain branched structure, it is preferable to use a branching agent represented by the following formula (1) or formula (2) as a branching agent. The portion derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group is a monomer unit based on a compound represented by the following formula (1) or (2), and the conjugated diene polymer of the present embodiment preferably has a structure having a polymer chain branching point due to a monomer unit based on a compound represented by the following formula (1) or (2).

[0054] [ka]

[0055] [ka]

[0056] (In formula (1), R 1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, which may partially have a branched structure. 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 partially have a branched structure. R when multiple exist 1 ~R 3 are each independent. X 1 represents an independent halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3.) (In formula (2), 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 partially have a branched structure. R when multiple exist 2 ~R 5 are each independent. X2 ~X 3 represents an independent halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) means 3. a represents an integer of 0 to 2, b represents an integer of 0 to 3, and c represents an integer of 0 to 3. (a+b+c) represents 3.)

[0057] In the present embodiment, the branching agent used in constructing the main chain branched structure of the conjugated diene polymer is preferably a branching agent represented by the formula (1) R 1 is a hydrogen atom and m=0.

[0058] In addition, in the present embodiment, the branching agent used when constructing a main chain branched structure of the conjugated diene polymer is preferably a compound in which m=0 and b=0 in formula (2), from the viewpoint of improving the degree of branching.

[0059] In the present embodiment, the branching agent used in constructing the main chain branched structure of the conjugated diene polymer is, from the viewpoints of continuity of polymerization and improvement of the modification rate and the branching degree, R 1 is a hydrogen atom, m=0, l=0, and n=3.

[0060] In the present embodiment, the branching agent used in constructing a main chain branched structure of the conjugated diene polymer is preferably a compound in which m=0, l=0, n=3, a=0, b=0, and c=3 in the above formula (2), from the viewpoint of improving the modification rate and the degree of branching.

[0061] Examples of the branching agent represented by the formula (1) include, but are not limited to, trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane, trimethoxy(3-vinylphenyl)silane, triethoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)silane, tributoxy(3-vinylphenyl)silane, triisopropoxy(3-vinylphenyl)silane, 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, and diisopropoxymethyl(2-vinylphenyl)silane.

[0062] Examples of the branching agent represented by the formula (1) include 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, and dimethylisopropoxy(3-vinylphenyl)silane. dimethyl(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)silane, tripropoxy(3-isopropenylphenyl)silane, tributoxy(3-isopropenylphenyl)silane, triisopropoxy(3-isopropenylphenyl)silane, trimethoxy(2-isopropenylphenyl)silane, triethoxy(2-isopropenylphenyl)silane, tripropoxy(2-isopropenylphenyl)silane, tributoxy(2-isopropenylphenyl)silane, tri triisopropoxy(2-isopropenylphenyl)silane, dimethoxymethyl(4-isopropenylphenyl)silane, diethoxymethyl(4-isopropenylphenyl)silane, dipropoxymethyl(4-isopropenylphenyl)silane, dibutoxymethyl(4-isopropenylphenyl)silane, diisopropoxymethyl(4-isopropenylphenyl)silane, dimethoxymethyl(3-isopropenylphenyl)silane, diethoxymethyl(3-isopropenylphenyl)silane, dipropoxymethyl(3-isopropenylphenyl)silane,Dibutoxymethyl(3-isopropenylphenyl)silane, diisopropoxymethyl(3-isopropenylphenyl)silane, dimethoxymethyl(2-isopropenylphenyl)silane, diethoxymethyl(2-isopropenylphenyl)silane, dipropoxymethyl(2-isopropenylphenyl)silane, dibutoxymethyl(2-isopropenylphenyl)silane, diisopropoxymethyl(2-isopropenylphenyl)silane, dimethylmethoxy(4-isopropenylphenyl)silane, dimethylethoxy(4-isopropenylphenyl)silane dimethylpropoxy(4-isopropenylphenyl)silane, dimethylbutoxy(4-isopropenylphenyl)silane, dimethylisopropoxy(4-isopropenylphenyl)silane, dimethylmethoxy(3-isopropenylphenyl)silane, dimethylethoxy(3-isopropenylphenyl)silane, dimethylpropoxy(3-isopropenylphenyl)silane, dimethylbutoxy(3-isopropenylphenyl)silane, dimethylisopropoxy(3-isopropenylphenyl)silane, dimethylmethoxy(2-isopropenylphenyl)silane propenylphenyl)silane, dimethylethoxy(2-isopropenylphenyl)silane, dimethylpropoxy(2-isopropenylphenyl)silane, dimethylbutoxy(2-isopropenylphenyl)silane, dimethylisopropoxy(2-isopropenylphenyl)silane, trichloro(4-vinylphenyl)silane, trichloro(3-vinylphenyl)silane, trichloro(2-vinylphenyl)silane, tribromo(4-vinylphenyl)silane, tribromo(3-vinylphenyl)silane, tribromo(2-vinylphenyl)silane , dichloromethyl(4-vinylphenyl)silane, dichloromethyl(3-vinylphenyl)silane, dichloromethyl(2-vinylphenyl)silane, dibromomethyl(4-vinylphenyl)silane, dibromomethyl(3-vinylphenyl)silane, dibromomethyl(2-vinylphenyl)silane, dimethylchloro(4-vinylphenyl)silane, dimethylchloro(3-vinylphenyl)silane, dimethylchloro(2-vinylphenyl)silane, dimethylbromo(4-vinylphenyl)silane, dimethylbromo(3-vinylphenyl)silane,Dimethylbromo(2-vinylphenyl)silane.

[0063] 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, tributoxy(4-vinylphenyl)silane, and triisopropoxy(4-vinylphenyl)silane are more preferred.

[0064] The branching agent represented by the formula (2) is not limited to the following, but examples thereof include 1,1-bis(4-trimethoxysilylphenyl)ethylene, 1,1-bis(4-triethoxysilylphenyl)ethylene, 1,1-bis(4-tripropoxysilylphenyl)ethylene, 1,1-bis(4-tripentoxysilylphenyl)ethylene, 1,1-bis(4-triisopropoxysilylphenyl)ethylene, 1,1-bis(3-trimethoxysilylphenyl)ethylene, 1,1-bis(3-triethoxysilylphenyl)ethylene, 1,1-bis(3-tripoxysilylphenyl)ethylene, 1,1-bis(3-tripentoxysilylphenyl)ethylene, 1,1-bis(3-triisopropoxysilylphenyl)ethylene, 1,1-bis(2 -trimethoxysilylphenyl)ethylene, 1,1-bis(2-triethoxysilylphenyl)ethylene, 1,1-bis(3-tripropoxysilylphenyl)ethylene, 1,1-bis(2-tripentoxysilylphenyl)ethylene, 1,1-bis(2-triisopropoxysilylphenyl)ethylene, 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(diethylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(dipropylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(dimethylethoxysilyl)phenyl)ethylene, 1,1-bis(4-(diethylethoxysilyl)phenyl)ethylene, and 1,1-bis(4-(dipropylethoxysilyl)phenyl)ethylene.

[0065] 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, with 1,1-bis(4-trimethoxysilylphenyl)ethylene being more preferred.

[0066] (Weight average molecular weight) The weight average molecular weight of the conjugated diene copolymer of this embodiment is 45×104 More than 500 x 10 4 or less, preferably 50×10 4 More preferably, it is 60×10 4 The weight average molecular weight is preferably 450×10 4 More preferably, it is 400×10 or less. 4 or less, and more preferably 350×10 4 The following is the result. Weight average molecular weight is 45 x 10 4 When the weight average molecular weight is 500×10 or more, the abrasion resistance of the vulcanized product is excellent. 4 When the content is equal to or less than this, the processability and dispersibility of the filler when made into a vulcanizate are excellent, and sufficient breaking properties for practical use can be obtained. The weight average molecular weight of the conjugated diene polymer can be measured by the method described in the examples below. The weight average molecular weight of the conjugated diene polymer of the present embodiment can be controlled within the above numerical range by adjusting the amount of polymerizable monomer added, the polymerization temperature, the polymerization time, and the like.

[0067] (absolute molecular weight) The absolute molecular weight is measured by a GPC-light scattering method equipped with a viscosity detector. Generally, polymers with branched structures tend to have smaller molecular size compared to linear polymers with the same molecular weight. Therefore, the molecular weight of a polymer with branched structures tends to be underestimated when it is screened by molecular size and measured in terms of polystyrene using gel permeation chromatography (hereinafter also referred to as "GPC"), which is a relative comparison method with a standard polystyrene sample. On the other hand, the light scattering method directly observes the molecular size and measures the molecular weight (absolute molecular weight), and therefore tends to enable accurate measurement of the molecular weight 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. The absolute molecular weight of the conjugated diene polymer of the present embodiment is 70×10 4 ~100×105 Preferably, 80×10 4 ~500×10 4 More preferably, it is 90×10 4 ~350×10 4 It is even more preferable that: The absolute molecular weight of the conjugated diene polymer can be controlled within the above numerical range by adjusting the amount of polymerization initiator added, polymerization temperature, polymerization time, amount of branching agent added, and the like.

[0068] (Aromatic vinyl monomer unit content) The conjugated diene polymer of the present embodiment may be a polymer of a conjugated diene compound, an aromatic vinyl compound and a branching agent, or may be a copolymer with 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 polymer chain is a so-called polybutadiene or polyisoprene, and the branched portion is a polymer containing a structure derived from a vinyl aromatic. By having such a structure, the linearity per polymer chain is improved, and the crosslinking density after vulcanization can be improved, thereby improving the wear resistance. Therefore, the conjugated diene polymer of this embodiment is suitable for applications such as tires, resin modification, automobile interior and exterior parts, anti-vibration rubber, and footwear. When the conjugated diene polymer is used for tire tread applications, a copolymer of a conjugated diene compound, an aromatic vinyl compound, and a branching agent is suitable. From this viewpoint, the content of aromatic vinyl monomer units in the conjugated diene polymer of this embodiment is 30 to 45 mass%, and from the viewpoints of wear resistance and tensile strength, it is preferably 32 mass% or more, more preferably 34 mass% or more, and even more preferably 36 mass% or more. Moreover, from the viewpoint of fuel economy, the content is preferably 43% by mass or less, and more preferably 41% by mass or less. The content of the aromatic vinyl monomer unit in the conjugated diene polymer can be controlled within the above numerical range by adjusting the amount of the aromatic vinyl monomer added in the polymerization step.

[0069] In addition, in the conjugated diene polymer of the present embodiment, the content (mass%) of the aromatic vinyl monomer unit in the conjugated diene polymer is greater than the amount of vinyl bonds (mol%) in the conjugated diene monomer unit. From this viewpoint, it is preferable that the vinyl bond amount is small. An effective method for reducing the vinyl bond amount (mol%) is to add a branching agent during polymerization of the conjugated diene polymer and perform the polymerization process while maintaining the randomization performance. This allows the content (mass%) of aromatic vinyl monomer units to be controlled to be larger than the vinyl bond amount (mol%) in the conjugated diene monomer units. By decreasing the amount of vinyl bonds in the conjugated diene monomer units, the molecular chain length of the conjugated diene compound can be increased, and the resulting vulcanizate tends to have excellent tensile strength. The amount of vinyl bonds in the conjugated diene monomer units is preferably 45 mol % or less, more preferably 40 mol % or less, even more preferably 35 mol % or less, and even more preferably 30 mol % or less.

[0070] Here, the content (mass%) of the aromatic vinyl monomer unit in the conjugated diene polymer of the present embodiment can be measured by ultraviolet absorption of the phenyl group, and the content (mass%) of the conjugated diene monomer unit can also be obtained from this. Specifically, it is measured according to the method described in the examples below.

[0071] By making the content (mass%) of the aromatic vinyl monomer unit larger than the amount of vinyl bonds (mol%) in the conjugated diene monomer unit, the tensile strength and abrasion resistance of the vulcanized product tend to be excellent. Here, when the modified diene polymer is a copolymer of butadiene and styrene, the vinyl bond amount (1,2-bond amount) in the butadiene bond unit can be determined by the Hampton method (RR Hampton, Analytical Chemistry, 21, 923 (1949)). Specifically, it can be measured by the method described in the examples below.

[0072] When the conjugated diene polymer of the present embodiment is a conjugated diene-aromatic vinyl copolymer, it is preferable that the number of blocks in which 30 or more aromatic vinyl units are linked is small or that there is no block. More specifically, when the copolymer is a butadiene-styrene copolymer, in a known method in which the copolymer is decomposed by the Kolthoff method (the method described in I.M.Kolthoff, et al., J.Polym.Sci.1,429(1946)) and the amount of polystyrene insoluble in methanol is analyzed, the amount of blocks in which 30 or more aromatic vinyl units are linked is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, based on the total amount of the copolymer.

[0073] When the conjugated diene polymer of the present embodiment is a conjugated diene-aromatic vinyl copolymer, it is preferable that the proportion of aromatic vinyl units present independently is high, from the viewpoint of improving fuel economy performance. Specifically, when the copolymer is a butadiene-styrene copolymer, when the copolymer is decomposed by an ozonolysis method known as the Tanaka et al. method (Polymer, 22, 1721 (1981)) and the styrene chain distribution is analyzed by GPC, it is preferable that the amount of isolated styrene is 40% by mass or more relative to the total amount of bound styrene, and the amount of chain styrene structures having 8 or more styrene chains is 5.0% by mass or less. In this case, the resulting vulcanized rubber has excellent performance, particularly low hysteresis loss.

[0074] [Method for producing conjugated diene polymer] The method for producing a conjugated diene polymer of the present embodiment is a method for obtaining a conjugated diene polymer having the above-mentioned weight average molecular weight, a branching degree (Bn) of 7 or more, a content of aromatic vinyl monomer units of 30 to 45 mass%, and a value of the content (mass%) of the aromatic vinyl monomer units being greater than a value of a vinyl bond amount (mol%) in the conjugated diene monomer units, and includes a step of polymerizing at least a conjugated diene compound and an aromatic vinyl compound in a solvent containing a polar compound using an organolithium compound as a polymerization initiator while adding a branching agent to obtain a conjugated diene polymer having a main chain branched structure.

[0075] The method for producing a conjugated diene polymer of the present embodiment preferably includes a polymerization and branching step of polymerizing at least a conjugated diene compound and an aromatic vinyl compound using an organolithium compound as a polymerization initiator and obtaining a conjugated diene polymer having a main chain branched structure using at least one of the various branching agents described above, and a coupling step of reacting the conjugated diene polymer having a main chain branched structure with a coupling agent or a modifying agent having a nitrogen atom-containing group to couple the conjugated diene polymer.

[0076] (Polymerization and branching process) The polymerization and branching step in the method for producing a conjugated diene polymer of the present embodiment is, for example, a step of using an organolithium compound as a polymerization initiator, polymerizing at least a conjugated diene compound and an aromatic vinyl compound, and adding a branching agent to obtain a conjugated diene polymer having a main chain branched structure.

[0077] In the polymerization step, it is preferable to carry out polymerization by a propagation reaction due to a living anionic polymerization reaction, which makes it possible to obtain a conjugated diene-based polymer having an active terminal. Thereafter, in the branching step using a branching agent, main chain branching can be appropriately controlled, and further, by carrying out a coupling step, it tends to be possible to obtain a conjugated diene-based polymer with a high modification rate.

[0078] <Polymerization initiator> As the polymerization initiator, an organolithium compound is used, and it is preferable to use at least an organomonolithium compound. The organomonolithium compound is not limited to the following, but examples thereof include low molecular weight compounds and solubilized oligomeric organomonolithium compounds. In addition, examples of the organomonolithium compound include compounds having a carbon-lithium bond, a nitrogen-lithium bond, and a tin-lithium bond in terms of the bonding mode between the organic group and the lithium.

[0079] The amount of the organic monolithium compound used as the polymerization initiator is preferably determined depending on 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 relates to the degree of polymerization of the target conjugated diene polymer, i.e., tends to relate to the number average molecular weight and / or weight average molecular weight. Therefore, in order to increase the molecular weight of the conjugated diene polymer, the amount of the polymerization initiator used should be adjusted to decrease, and in order to decrease the molecular weight, the amount of the polymerization initiator used should be adjusted to increase.

[0080] From the viewpoint of being used as one method for introducing nitrogen atoms into a conjugated diene-based polymer, the organomonolithium compound is preferably an organomonolithium compound having a substituted amino group, for example, an alkyllithium compound having a substituted amino group, or a dialkylaminolithium. In this case, a conjugated diene polymer having a nitrogen atom consisting of an amino group at the polymerization initiation end is obtained. When the conjugated diene polymer obtained in the polymerization step has a nitrogen atom consisting of an amino group at the polymerization initiation end, a chain transfer reaction is likely to occur when anionic polymerization proceeds, and it is difficult to obtain a sufficient amount of reaction by a coupling agent or a modifier for the active end after the polymerization is completed, and the absolute molecular weight tends to be small. Therefore, from the viewpoint of the tensile strength and abrasion resistance when the conjugated diene copolymer of this embodiment is made into a vulcanizate, it is preferable to select a polymerization temperature that can control the chain transfer reaction and polymerize it.

[0081] The substituted amino group is an amino group that does not have an active hydrogen or has a structure in which the active hydrogen is protected. Examples of alkyllithium compounds having an amino group that does not have an active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium. Examples of alkyllithium compounds having an amino group with an active hydrogen protected structure include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0082] Examples of dialkylaminolithium include, but are not limited to, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium di-n-hexylamide, lithium diheptylamide, lithium diisopropylamide, lithium dioctylamide, lithium-di-2-ethylhexylamide, lithium didecylamide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, lithium methylphenethylamide, lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithio-1,2,3,6-tetrahydropyridine.

[0083] These organomonolithium compounds having a substituted amino group can also be used as oligomeric organomonolithium compounds solubilized in normal hexane or cyclohexane by reacting them with a small amount of a polymerizable monomer, such as 1,3-butadiene, isoprene, or styrene. The organomonolithium compound is preferably an alkyllithium compound from the viewpoints of industrial availability and ease of control of the polymerization reaction, in which case a conjugated diene-based polymer having an alkyl group at the polymerization initiation terminal can be obtained. Examples of the alkyl lithium compound include, but are not limited to, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, n-hexyl lithium, benzyl lithium, phenyl lithium, and stilbene lithium. As the alkyllithium compound, n-butyllithium and sec-butyllithium are preferred from the viewpoints of industrial availability and ease of control of the polymerization reaction.

[0084] These organomonolithium compounds may be used alone or in combination of two or more, and may also be used in combination with other organometallic compounds. Examples of the other organometallic compounds include alkaline earth metal compounds, other alkali metal compounds, and other organometallic compounds. Alkaline earth metal compounds include, but are not limited to, organomagnesium compounds, organocalcium compounds, and organostrontium compounds, as well as alkaline earth metal alkoxides, sulfonates, carbonates, and amides. Examples of organomagnesium compounds include dibutylmagnesium and ethylbutylmagnesium. Other organometallic compounds include organoaluminum compounds.

[0085] In the polymerization step, the polymerization reaction mode is not limited to the following, but examples thereof include a batchwise polymerization mode (also called a "batch type") and a continuous polymerization mode. In the continuous system, one or more connected reactors can be used. The continuous reactor is, for example, a tank type or a tube type equipped with an agitator. In the continuous system, preferably, the monomer, the inert solvent, and the polymerization initiator are continuously fed into the reactor, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is continuously discharged. The batch reactor may be, for example, a tank-type reactor equipped with a stirrer. In the batch reactor, preferably, a monomer, an inert solvent, and a polymerization initiator are fed, and if necessary, a monomer is added continuously or intermittently during polymerization to obtain a polymer solution in the reactor, and the polymer solution is discharged after the polymerization is completed. In the method for producing a 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 period of time.

[0086] The polymerization step of the conjugated diene polymer is preferably carried out in an inert solvent, more preferably a solvent compatible with the conjugated diene polymer. Preferred solvents include, for example, hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific hydrocarbon solvents include, but are not limited to, aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene, and hydrocarbons consisting of mixtures thereof. By treating the impurities, that is, allenes and acetylenes, with an organometallic compound before subjecting the polymer to the polymerization reaction, a conjugated diene-based polymer having a high concentration of active ends tends to be obtained, which is preferable since a modified conjugated diene-based polymer having a high modification rate tends to be obtained.

[0087] <Polar compounds (polar substances)> In the polymerization step, the above-mentioned organolithium compound is used as a polymerization initiator to polymerize at least a conjugated diene compound and an aromatic vinyl compound in a solvent containing a polar compound (sometimes referred to as a polar substance in this specification), while adding a branching agent, to obtain a conjugated diene-based polymer having a main chain branched structure. By adding a polar compound to the solvent, the aromatic vinyl compound can be randomly copolymerized with the conjugated diene compound, and the polar compound also tends to function effectively as a vinylating agent for controlling the microstructure of the conjugated diene portion.

[0088] In addition, polar compounds tend to be effective in promoting polymerization reactions in the polymerization of conjugated diene compounds, etc. Therefore, when industrially producing conjugated diene polymers, it is common to add a certain amount of polar compounds to improve productivity. In addition to the production efficiency, if the amount of polar compound added is reduced, the polymerization time may be too long, increasing the proportion of active polymer ends that are deactivated during the polymerization, resulting in a high proportion of low molecular weight components, or the coupling rate and / or modification rate of the polymerization end end may not be increased. Conventionally, a polymer design has been used in which a multifunctional coupling agent containing nitrogen or the like is reacted with the polymerization end end to branch the polymer chain, but in this method, if the polymerization activity is deactivated during the polymerization, the branching degree and modification rate cannot be set as set. In other words, because the vinylizing agent also serves as a polymerization accelerator, it was difficult to independently control the amount of vinyl bonds and the branching degree and / or modification rate. In contrast, in the production method of the present embodiment, by branching the polymer chain with a branching agent, the formation of the branched structure does not depend only on the coupling reaction of the active terminals of the polymer, so that it is possible to produce a polymer with a high degree of branching even if the amount of vinylating agent added is reduced in order to produce a polymer with a low vinyl bond content. 4 More than 500 x 10 4By controlling as follows, it is possible to industrially produce a conjugated diene polymer in which the content of aromatic vinyl monomer units in the conjugated diene polymer is in the range of 30 to 45 mass%, the degree of branching (Bn) is 7 or more, and the content (mass%) of aromatic vinyl monomer units is larger than the amount of vinyl bonds (mol%) in the conjugated diene monomer units.

[0089] Examples of polar compounds that can be used include, but are not limited to, ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butylate, sodium tert-butylate, and sodium amylate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used alone or in combination of two or more.

[0090] Many polar compounds have an effective randomizing effect in the copolymerization of a conjugated diene compound and an aromatic vinyl compound, and tend to be usable as an agent for adjusting the distribution of aromatic vinyl monomer units or the amount of styrene blocks.

[0091] The amount of the polar compound used correlates with the amount of active terminals of the polymer, and the amount of active terminals of the polymer depends on the amount of the polymerization initiator. The amount of the polar compound used is preferably 0.01 mol or more and 1 mol or less, and more preferably 0.1 mol or more and 0.8 mol or less, per mol of the polymerization initiator. By setting the content to the upper limit or less, the content (mass%) of the aromatic vinyl monomer unit in the conjugated diene polymer of this embodiment is 30 to 45 mass%, and the content (mass%) of the aromatic vinyl monomer unit is greater than the vinyl bond amount (mol%) in the conjugated diene monomer unit. By setting the content to the lower limit or more, the polymer active terminal is easily maintained, the polymerization reaction is promoted, and the coupling rate of the terminal is improved. The content of the aromatic vinyl monomer unit in the conjugated diene polymer is 30 mass% or more from the viewpoint of abrasion resistance and tensile strength, preferably 32 mass% or more, more preferably 34 mass% or more, and even more preferably 36 mass% or more.

[0092] As a method for randomizing the conjugated diene compound and the aromatic vinyl compound, for example, as described in JP-A-59-140211, a copolymerization reaction may be initiated with the total amount of styrene and a portion of 1,3-butadiene, and the remaining 1,3-butadiene may be intermittently added during the copolymerization reaction.

[0093] <Addition of branching agent> In the method for producing a conjugated diene polymer of the present embodiment, as described above, a branching agent is added while polymerizing a conjugated diene compound and an aromatic vinyl compound to obtain a conjugated diene polymer having a main chain branched structure. The amount of the branching agent to be added 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. The branching agent can be used in an appropriate amount depending on the number of branching points in the main chain branched structure of the conjugated diene portion of the intended conjugated diene-based polymer.

[0094] Also, by adding a branching agent during polymerization of a conjugated diene polymer, the active terminal of the conjugated diene polymer can be reduced from the amount of polymerization initiator added, and the polar compound promotes the reaction at least in the early stages of polymerization, thereby maintaining the active terminal of the polymer. This makes it possible to obtain a conjugated diene polymer in which the content (mass%) of aromatic vinyl monomer units is greater than the vinyl bond amount (mol%) of the conjugated diene monomer units, and thus to obtain a conjugated diene polymer with a high coupling rate or modification rate, and further to make the branching degree (Bn) of the conjugated diene polymer 7 or more.

[0095] When the branching agent is not added, even if the amount of polar compound added is selected to obtain a predetermined microstructure ratio, the randomization ability of the aromatic vinyl compound and the conjugated diene compound is reduced, and in the conjugated diene polymer having the above-mentioned aromatic vinyl monomer unit content of 30 to 45 mass%, the polymerization terminal tends to be an aromatic vinyl monomer unit. In such a state, it tends to be difficult to obtain a conjugated diene polymer with a high coupling rate or modification rate, and it tends to be difficult to make the branching degree (Bn) 7 or more.

[0096] As described above, the present inventors have conducted an investigation by varying the amount of polar compound added to a conjugated diene polymer having an aromatic vinyl monomer unit content of 30 to 45 (mass%), and have found that the smaller the vinyl bond amount (mol%) of the conjugated diene monomer unit, the more excellent the tensile strength and abrasion resistance tend to be. In particular, they discovered that when compared with conjugated diene polymers having the same glass transition temperature, conjugated diene polymers in which the content (mass%) of aromatic vinyl monomer units is greater than the vinyl bond amount (mol%) of the conjugated diene monomer units have superior tensile strength and abrasion resistance. In the process of designing and producing a normal conjugated diene polymer, the content of the aromatic vinyl monomer unit is set by mass, and the vinyl bond amount is set by mol%, so it is difficult to think that there is any mathematical significance in comparing these absolute values. However, as a result of carrying out repeated experiments in which the amount of the polar compound added in the polymerization process was widely changed, it was found that the tensile strength and abrasion resistance of the polymer of this embodiment are high when the content value of the aromatic vinyl monomer unit is large, by comparing the values ​​of the aromatic vinyl monomer unit (mass%) and the vinyl bond amount (mol%) of the conjugated diene monomer unit.

[0097] 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 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, even more preferably 65% ​​or more, and even more preferably 75% or more. By adjusting the amount of the polar compound to fall within the above range, a conjugated diene polymer with a high degree of modification can be obtained even when the amount of the polar compound is small.

[0098] After the branching agent is added, the desired monomer may be further added to continue the polymerization step after branching, or the above-described process may be repeated. 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. 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 coupling agent becomes long, and a molecular structure with high linearity tends to be obtained. By making the molecular structure highly linear, entanglement between molecular chains of the conjugated diene polymer increases when the polymer is vulcanized, and a rubber composition having excellent abrasion resistance, handling stability and breaking strength tends to be obtained.

[0099] 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 being in such a range, there is a tendency that the amount of the modifying agent reacting with the active terminal after the polymerization is completed can be sufficiently ensured. Even more preferably, it is 50°C or higher and 100°C or lower. From the viewpoint of sufficiently completing the polymerization reaction of the aromatic vinyl monomer in the conjugated diene polymer of the present embodiment and controlling the content of the aromatic vinyl monomer unit to 30 to 45 mass %, the temperature is preferably 60°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher.

[0100] In the method for producing a conjugated diene-based polymer of this embodiment, the amount of branching agent added in the branching step for forming a main chain branched structure is as described above. The branching agent can be used in an appropriate amount according to the desired number of branching points as branching points of the main chain branched structure of the conjugated diene portion of the conjugated diene polymer.

[0101] (Coupling process) The method for producing a conjugated diene polymer of the present embodiment preferably includes a coupling step of coupling the conjugated diene polymer obtained through the above-mentioned polymerization and branching steps with a coupling agent. As the coupling step, for example, a coupling step is preferably performed using a reactive compound having two or more functionalities (hereinafter also referred to as a "coupling agent") for the active terminal of the conjugated diene polymer, or using a modifying agent having a nitrogen atom-containing group.

[0102] In the coupling step, for example, one active end of the conjugated diene polymer is subjected to a coupling reaction with a coupling agent or a modifying agent having a nitrogen atom-containing group to obtain a conjugated diene polymer.

[0103] <Coupling Agent> When the method for producing a conjugated diene polymer of the present embodiment includes a coupling step, the coupling agent is not particularly limited, and any reactive compound having any structure and functionality may be preferably used as long as the reactive compound has two or more functionalities, and a reactive compound having two or more functionalities and a nitrogen atom is more preferable.

[0104] <Modifiers Having Nitrogen Atom-Containing Groups> Examples of the modifying agent having a nitrogen atom-containing group include, but are not limited to, an isocyanate compound, an isothiocyanate compound, an isocyanuric acid derivative, a carbonyl compound having a nitrogen atom-containing group, a vinyl compound having a nitrogen atom-containing group, and an epoxy compound having a nitrogen atom-containing group.

[0105] In the modifying agent having a nitrogen atom-containing group, the nitrogen atom-containing group is preferably an amine compound having no active hydrogen, and examples of the modifying agent having a nitrogen atom-containing group include a tertiary amine compound, a protected amine compound in which the above-mentioned active hydrogen is substituted with a protecting group, an imine compound represented by the general formula -N=C, and an alkoxysilane compound bonded to the above-mentioned nitrogen atom-containing group.

[0106] Examples of isocyanate compounds that are modifying agents having a nitrogen atom-containing group include, but are not limited to, 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.

[0107] Examples of isocyanuric acid derivatives, which are modifying agents having a nitrogen atom-containing group, include, but are not limited to, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate, 1,3,5-tris(3-triethoxysilylpropyl)isocyanurate, 1,3,5-tri(oxiran-2-yl)-1,3,5-triazinane-2,4,6-trione, 1,3,5-tris(isocyanatomethyl)-1,3,5-triazinane-2,4,6-trione, and 1,3,5-trivinyl-1,3,5-triazinane-2,4,6-trione.

[0108] Examples of carbonyl compounds that are modifying agents having a nitrogen atom-containing group include, but are not limited to, 1,3-dimethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 1-methyl-3-(2-methoxyethyl)-2-imidazolidinone, N-methyl-2-pyrrolidone, N-methyl-2-piperidone, N-methyl-2-quinolone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, Examples of the methyl-2-pyridyl ketone include 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-diethylmethylcarbamate, N,N-diethylacetamide, N,N-dimethyl-N',N'-dimethylaminoacetamide, N,N-dimethylpicolinic acid amide, and N,N-dimethylisonicotinic acid amide.

[0109] Examples of vinyl compounds that are modifying agents having a nitrogen atom-containing group include, but are not limited to, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N-methylmaleimide, N-methylphthalimide, N,N-bistrimethylsilylacrylamide, morpholinoacrylamide, 3-(2-dimethylaminoethyl)styrene, (dimethylamino)dimethyl-4-vinylphenylsilane, 4,4'-vinylidenebis(N,N-dimethylaniline), 4,4'-vinylidenebis(N,N-diethylaniline), 1,1-bis(4-morpholinophenyl)ethylene, and 1-phenyl-1-(4-N,N-dimethylaminophenyl)ethylene.

[0110] The epoxy compound, which is a modifier having a nitrogen atom-containing group, is, for example, but not limited to, an epoxy group-containing hydrocarbon compound bonded to an amino group, which may further have an epoxy group bonded to an ether group. Such an epoxy compound is, for example, but not limited to, an epoxy compound represented by the general formula (i):

[0111] [ka]

[0112] In the formula (i), R 7 is a divalent hydrocarbon group, or a divalent organic group having at least one polar group selected from the group consisting of oxygen-containing polar groups such as ether, epoxy, ketone, and ketone, sulfur-containing polar groups such as thioether and thioketone, and nitrogen-containing polar groups such as tertiary amino group and imino group.

[0113] The divalent hydrocarbon group is a saturated or unsaturated, linear, branched or cyclic hydrocarbon group, and includes an alkylene group, an alkenylene group, a phenylene group, etc. A divalent hydrocarbon group having 1 to 20 carbon atoms is preferable. Examples thereof 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.

[0114] In the formula (i), R 8 and R 6 represents a hydrogen atom, a monovalent alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R 8 and R 6 may be the same or different from each other. R 9 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a structure represented by the following formula (ii): R 8 and R 6 may be bonded to each other to form a cyclic structure. Also, R 9 When is a monovalent hydrocarbon group, R 8 and R may be bonded to each other to form a ring structure. 9 N and R bonded to 8 Only when and are directly bonded, R 9 may be a hydrogen atom. In the formula (i), o is an integer of 1 or more.

[0115] [ka]

[0116] In the formula (ii), R 1 , R 2 are R in the formula (i), 7 , R 8 It is defined similarly to R 1 , R 2 are R 7 , R 8may be the same as or different from.

[0117] 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.

[0118] The epoxy compound used as the modifying agent having a nitrogen atom-containing group is not limited to the following, but examples thereof include N,N-diglycidyl-4-glycidoxyaniline, 1-N,N-diglycidylaminomethyl-4-glycidoxy-cyclohexane, 4-(4-glycidoxyphenyl)-(N,N-diglycidyl)aniline, 4-(4-glycidoxyphenoxy)-(N,N-diglycidyl)aniline, 4-(4-glycidoxybenzyl)-(N,N-diglycidyl)aniline, 4-(N,N'-diglycidyl-2-piperazinyl)-glycidoxybenzene, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m -xylenediamine, 4,4-methylene-bis(N,N-diglycidylaniline), 1,4-bis(N,N-diglycidylamino)cyclohexane, N,N,N',N'-tetraglycidyl-p-phenylenediamine, 4,4'-bis(diglycidylamino)benzophenone, 4-(4-glycidylpiperazinyl)-(N,N-diglycidyl)aniline, 2-[2-(N,N-diglycidylamino)ethyl]-1-glycidylpyrrolidine, N,N-diglycidylaniline, 4,4'-diglycidyl-dibenzylmethylamine, N,N-diglycidylaniline, N,N-diglycidylorthotoluidine, and N,N-diglycidylaminomethylcyclohexane. Among these, particularly preferred ones include N,N-diglycidyl-4-glycidoxyaniline and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

[0119] Examples of alkoxysilane compounds that are modifiers having a nitrogen atom-containing group include, but are not limited to, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropylmethyldimethoxysilane, 3-diethylaminopropyltriethoxysilane, 3-morpholinopropyltrimethoxysilane, 3-piperidinopropyltriethoxysilane, 3-hexamethyleneiminopropylmethyldiethoxysilane, 3-(4-methyl-1-piperazino)propyltrimethoxysilane, 3-(4-methyl-1-piperazino)propyltrimethoxysilane, 3-(4-methyl-1-piperazino)propyltriethoxy ... 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-trimethylsilylpropyl)-N-methylamine, 2,2-Dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-Diethoxy-1-(3-trimethoxysilylpropyl)-N-methylamine, bis(3-triethoxysilylpropyl)methylamine, tris(trimethoxysilyl)amine, tris(3-trimethoxysilylpropyl)amine, N,N,N',N'-tetra(3-trimethoxysilylpropyl)ethylenediamine, 3-isocyanatopropyltrimethoxysilane, 3-cyanopropyltrimethoxysilane, 2,2-Dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-Diethoxy-1-(3-triethoxysilylpropyl)- 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, etc.

[0120] Modifiers having a nitrogen atom-containing group and protected amine compounds capable of forming primary or secondary amines include compounds having an unsaturated bond and a protected amine in the molecule, but are not limited to the following: 4,4'-vinylidenebis[N,N-bis(trimethylsilyl)aniline], 4,4'-vinylidenebis[N,N-bis(triethylsilyl)aniline], 4,4'-vinylidenebis[N,N-bis(t-butyldimethylsilyl)aniline], 4,4'-vinylidenebis[N-methyl-N-(trimethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N-(trimethylsilyl)aniline], 4,4' 4,4'-vinylidenebis[N-methyl-N-(triethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N-(triethylsilyl)aniline], 4,4'-vinylidenebis[N-methyl-N-(t-butyldimethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N-(t-butyldimethylsilyl)aniline], 1-[4-N,N-bis(trimethylsilyl)aminophenyl]-1-[4-N-methyl-N-(trimethylsilyl)aminophenyl]ethylene, 1-[4-N,N-bis(trimethylsilyl)aminophenyl]-1-[4-N,N-dimethylaminophenyl]ethylene, and the like.

[0121] Modifiers having a nitrogen atom-containing group and protected amine compounds capable of forming a primary or secondary amine include, but are not limited to, compounds having an alkoxysilane and a protected amine in the molecule, such as 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)propyltriethoxysilane, 3-(4-trimethylsilyl-1-piperazino)propyltriethoxysilane, 3-(4-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, 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane, N-(1,3-dimethylbutylidene)-3-methyl(dimethoxysilyl)-1-propanamine, N-(1,3-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-(trimethoxysilyl)-1-propanamine, N-ethylidene-3-methyl(dimethoxysilyl)-1-propanamine, N-ethylidene-3-methyl(diethoxysilyl)-1-propanamine.

[0122] In addition, as a modifying agent having a nitrogen atom-containing group and a protected amine compound capable of forming a primary or secondary amine, a compound having an alkoxysilane and a protected amine in the molecule includes N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(trimethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-methyl(dimethoxysilyl)-1-propanamine, and N-(1-methylpropylidene)-3-methyl(dimethoxysilyl)-1-propanamine. Propanamine, N-(1-methylpropylidene)-3-methyl(diethoxysilyl)-1-propanamine, 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)propan-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- 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-ethoxy-2-methyl-1-(benzylideneaminoethyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-1-(methylisobutylideneaminoethyl)-1-aza-2-silacyclopentane, and the like.

[0123] Particularly preferred alkoxysilane compounds that are modifiers having a nitrogen atom-containing group include, but are not limited to, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-tripropoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, 3-(4-methylpiperazin-1-yl)propyltrimethoxysilane, 3-(4-methylpiperazin-1-yl)propyltriethoxysilane, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-a 2,2-Diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane.

[0124] Particularly preferred examples of the alkoxysilane compound, which is a modifying agent having a nitrogen atom-containing group, include 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-trimethylsilylpropyl)-cyclohexane, 3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)phosphate, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-(trimethoxysilyl)-1-propanamine, N-benzylidene-3-(triethoxysilyl)propan-1-amine, N-benzylidene-3-(trimethoxysilyl)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), 2-methoxy-2-methyl-1-(benzylideneaminoethyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-1-(4-methoxybenzylideneaminoethyl)-1-aza-2-silacyclopentane. These modifying agents may be used alone or in combination of two or more.

[0125] (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).

[0126] [ka]

[0127] In the formula (i), R 7 is a divalent hydrocarbon group, or a divalent organic group having at least one polar group selected from the group consisting of oxygen-containing polar groups such as ether, epoxy, ketone, and ketone, sulfur-containing polar groups such as thioether and thioketone, and nitrogen-containing polar groups such as tertiary amino group and imino group.

[0128] The divalent hydrocarbon group is a saturated or unsaturated, linear, branched or cyclic hydrocarbon group, and includes an alkylene group, an alkenylene group, a phenylene group, etc. A divalent hydrocarbon group having 1 to 20 carbon atoms is preferable. Examples thereof 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.

[0129] In the formula (i), R 8 , and R 6 represents a hydrogen atom, a monovalent alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R 8 , and R 6 may be the same or different from each other. R 9 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a structure represented by the following formula (ii): R 8 and R 6 may be bonded to each other to form a cyclic structure. Also, R 9 When is a monovalent hydrocarbon group, R 8 and R may be bonded to each other to form a ring structure. 9 N and R bonded to 8 Only when and are directly bonded, R 9 may be a hydrogen atom. In formula (i), o is an integer of 1 or more.

[0130] [ka]

[0131] In the formula (ii), R 1 , R 2 are R in the formula (i), 7 , R 8 It is defined similarly to R 1 , R 2 are R 7 , R 8 may be the same as or different from.

[0132] [ka]

[0133] (In formula (A), R 12 ~R 15 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms; R 16 represents an alkylene group having 1 to 10 carbon atoms; R 17 represents an alkylene group having 1 to 20 carbon atoms. q represents an integer of 1 or 2, r represents an integer of 2 or 3, and (q+r) represents an integer of 4 or more. 12 ~R 15 are independent of each other.)

[0134] [ka]

[0135] (In formula (B), R 18 ~R 23 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms; R 24 ~R 26 each independently represents an alkylene group having 1 to 20 carbon atoms. Each of s, t, and u independently represents an integer of 1 to 3, and (s+t+u) represents an integer of 4 or more. 18 ~R 23 are independent of each other.)

[0136] [ka]

[0137] (In formula (C), R 27 ~R 29 each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms; R 30 ~R 33 , and R35 each independently represents an alkyl group having 1 to 20 carbon atoms; R 34 and R 37 each independently represents an alkylene group having 1 to 20 carbon atoms; R 36 represents an alkyl group having 1 to 20 carbon atoms or a trialkylsilyl group. w represents an integer of 1 to 3; x represents 1 or 2. R when there are multiple of each 27 ~R 37 , w and k 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.

[0138] [ka]

[0139] (In formula (D), R 36 represents an alkylene group having 1 to 20 carbon atoms; R 37 , R 39 , and R 40 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms; R 38 represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and z represents an integer of 1 to 3.

[0140] [ka]

[0141] R in formula (E) 41 ~R 44 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms; R 45 ~R 47each independently represents an alkylene group having 1 to 20 carbon atoms. m and n represent integers of 1 to 3 and may be the same or different. R when multiple exist 41 ~R 47 are each independent.

[0142] The modifying agent having a nitrogen atom-containing group represented by the formula (A) is not limited to the following, but 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- Examples include 2-silacyclopentane, 2,2-diethoxy-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-ethoxy,2-ethyl-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, and 2-ethoxy-2-ethyl-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane. Among these, from the viewpoints of reactivity and interaction between the functional group of the modifying agent having a nitrogen atom-containing group and an inorganic filler such as silica, and from the viewpoint of processability, those in which q is 2 and r 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.

[0143] The reaction temperature, reaction time, and the like when reacting the modifying agent having a nitrogen atom-containing group represented by the formula (A) with the active terminal of the polymer 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.

[0144] The total number of moles of alkoxy groups bonded to silyl groups in the modifying agent compound having a 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. From the viewpoint of obtaining a sufficient modification rate, molecular weight, and branched structure in the obtained conjugated diene polymer, it is preferably 0.6 times or more, and from the viewpoint of obtaining a branched polymer component by coupling polymer ends to improve processability, and from the viewpoint of the cost of the modifying agent, it is preferably 3.0 times or less. More specifically, the number of moles of the polymerization initiator is preferably 3.0 times or more, more preferably 4.0 times or more, by mole relative to the number of moles of the modifying agent.

[0145] The modifying agent having a nitrogen atom-containing group represented by the formula (B) includes, but is not limited to, tris(3-trimethoxysilylpropyl)amine, tris(3-methyldimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-methyldiethoxysilylpropyl)amine, tris(trimethoxysilylmethyl)amine, tris(2-trimethoxysilylethyl)amine, and tris(4-trimethoxysilylbutyl)amine. Among these, from the viewpoints of reactivity and interactivity between the functional group of the modifier and an inorganic filler such as silica, and from the viewpoint of processability, it is preferable that s, t, and u all represent 3. Preferable specific examples include tris(3-trimethoxysilylpropyl)amine and tris(3-triethoxysilylpropyl)amine.

[0146] The reaction temperature, reaction time, and the like when reacting the modifying agent having a nitrogen atom-containing group represented by the formula (B) with the active terminal of the polymer 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. The total number of moles of alkoxy groups bonded to silyl groups in the compound of the modifying agent represented by the formula (B) is preferably in the range of 0.6 to 3.0 times the number of moles of lithium constituting the above-mentioned 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. From the viewpoint of obtaining a sufficient modification rate, molecular weight, and branched structure in the conjugated diene polymer, it is preferably 0.6 times or more, and from the viewpoint of the cost of the modifying agent, it is preferable to couple the polymer terminals to each other to obtain a branched polymer component for improving processability, and it is preferably 3.0 times or less. 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.

[0147] In the above formula (C), A is preferably represented by any one of the following general formulae (II) to (V).

[0148] [ka]

[0149] (In formula (II), B 1 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. 1 are independent of each other.)

[0150] [ka]

[0151] (In formula (III), B 2 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms; B 3represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. 2 and B. 3 are independent of each other.)

[0152] [ka]

[0153] (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. 4 are independent of each other.)

[0154] [ka]

[0155] (In formula (V), B 5 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. 5 are independent of each other.)

[0156] In the formula (C), when A is represented by formula (II), examples of the modifying agent having a nitrogen atom-containing group include, but are not limited to, 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]-(3-trimethoxysilylpropyl)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, tetramethylsilyl Troxi(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-silacic Tetrakis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-di ethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine.

[0157] In addition, in the formula (C), examples of the modifying agent having a nitrogen atom-containing group when A is represented by formula (II) include 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-propanediamine, cyclohexane, 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)-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-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-trimethylsilyl-1-sila-2-azacyclopentane)propyl]- tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-triethoxysilylpropyl)-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-triethoxysilylpropyl)-bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-1,3-propane 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-silane cyclohexane, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane Cyclohexane, 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.

[0158] In the formula (C), when A is represented by formula (III), examples of the modifying agent having a nitrogen atom-containing group include, but are not limited to, 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.

[0159] In the formula (C), when A is represented by formula (IV), examples of the modifying agent having a nitrogen atom-containing group include, but are not limited to, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane )propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]silane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, (3-trimethoxysilyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane 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 bis(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.

[0160] In the formula (C) above, when A is represented by formula (V), examples of the modifying agent having a nitrogen atom-containing 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.

[0161] In the formula (C), A is preferably represented by formula (II) or formula (III), and k is 0. Modifiers having such nitrogen atom-containing groups tend to be easily available, and tend to provide better abrasion resistance and low hysteresis loss performance when the conjugated diene polymer is vulcanized. Modifiers having such nitrogen atom-containing groups include, but are not limited to, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis[3-(2,2-di ... bis[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.

[0162] In the formula (C), A is more preferably represented by formula (II) or formula (III), k represents 0, and in formula (II) or formula (III), a represents an integer of 2 to 10. This tends to result in better abrasion resistance and low hysteresis loss performance when vulcanized. Such a modifying agent having a nitrogen atom-containing group includes, but is not limited to, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, and N 1 -(3-(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N 1 -Methyl-N 3 -(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N 3 -(3-(trimethoxysilyl)propyl)-1,3-propanediamine.

[0163] 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 modifier reacts with the number of moles of lithium constituting the above-mentioned polymerization initiator in a desired stoichiometric ratio, which tends to achieve a desired star-shaped highly branched structure. Specifically, the number of moles of lithium constituting the polymerization initiator is preferably 5.0 times or more, more preferably 6.0 times or more, by mole 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 ((w-1)xi+xxj+k) is preferably an integer of 5-10, and more preferably an integer of 6-10.

[0164] The modifying agent having a nitrogen atom-containing group represented by the formula (D) is not limited to the following, but 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(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-(trimethoxysilyl)-1-propanamine Silyl)-1-propanamine, N-ethylidene-3-methyl(dimethoxysilyl)-1-propanamine, N-ethylidene-3-methyl(diethoxysilyl)-1-propanamine, 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)propan-1-amine 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, etc., 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, 2-methoxy-2-methyl-1-(methylisobutylideneaminoethyl)-1-aza-2-silacyclopentane.

[0165] The reaction temperature, reaction time, and the like when reacting the modifying agent having a nitrogen atom-containing group represented by the formula (D) with the active terminal of the polymer 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.

[0166] The total number of moles of alkoxy groups bonded to silyl groups in the compound of the modifying agent represented by the 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 above-mentioned 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. More specifically, the number of moles of the polymerization initiator is preferably 0.5 times or more by mole, more preferably 1.0 times or more by mole, relative to the number of moles of the modifying agent.

[0167] The modifying agent having a nitrogen atom-containing group represented by the formula (E) is not limited to the following, but 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, amines, N-(3-(1H-imidazol-1-yl)propyl)-3-(diethylethoxysilyl)-N-(3-(diethylethoxysilyl)propyl)propan-1-amine, N-(3-(1H-imidazol-1-yl)propyl)-3-(dimethylmethoxysilyl)-N-(3-(dimethylmethoxysilyl)propyl)propan-1-amine.

[0168] The reaction temperature, reaction time, and the like when reacting the modifying agent having a nitrogen atom-containing group represented by the formula (E) with the active terminal of the polymer 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.

[0169] The total number of moles of alkoxy groups bonded to silyl groups in the compound of the modifying agent represented by the 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 above-mentioned 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.

[0170] In the conjugated diene polymer of the present embodiment, the proportion of the nitrogen atom-containing polymer in the conjugated diene polymer is represented by a modification rate. The modification rate is preferably 60% by mass or more, more preferably 65% ​​by mass or more, even more preferably 70% by mass or more, still more preferably 75% by mass or more, even more preferably 80% by mass or more, and particularly preferably 82% by mass or more. By setting the modification rate to 60% by mass or more, the processability when vulcanized is excellent, and the vulcanized product tends to have better abrasion resistance and low hysteresis loss performance.

[0171] In this embodiment, a condensation reaction step in which a condensation reaction is carried out in the presence of a condensation promoter may be carried out after the coupling step or before the coupling step.

[0172] In the conjugated diene polymer of the present embodiment, the conjugated diene portion may be hydrogenated. The method for hydrogenating the conjugated diene portion of the conjugated diene polymer is not particularly limited, and any known method can be used. A suitable hydrogenation method is to blow gaseous hydrogen into a polymer solution in the presence of a catalyst. The catalyst is not particularly limited, but examples thereof include heterogeneous catalysts such as a catalyst in which a precious metal is supported on a porous inorganic material, a catalyst in which a salt of nickel, cobalt, or the like is solubilized and reacted with an organoaluminum, or a homogeneous catalyst such as a catalyst using a metallocene such as titanocene, etc. Among these, a titanocene catalyst is preferred from the viewpoint of being able to select mild hydrogenation conditions. Hydrogenation of aromatic groups can also be carried out using supported noble metal catalysts.

[0173] Examples of the hydrogenation catalyst include, but are not limited to, (1) supported heterogeneous hydrogenation catalysts in which metals such as Ni, Pt, Pd, Ru, etc. are supported on carbon, silica, alumina, diatomaceous earth, etc., (2) so-called Ziegler-type hydrogenation catalysts that use transition metal salts such as organic acid salts or acetylacetone salts of Ni, Co, Fe, Cr, etc. and reducing agents such as organoaluminum, and (3) so-called organometallic complexes such as organometallic compounds of Ti, Ru, Rh, Zr, etc. Furthermore, examples of the hydrogenation catalyst include, but are not limited to, known hydrogenation catalysts described in JP-B-42-8704, JP-B-43-6636, JP-B-63-4841, JP-B-1-37970, JP-B-1-53851, JP-B-2-9041, and JP-A-8-109219. Preferred hydrogenation catalysts include a reaction mixture of a titanocene compound and a reducing organometallic compound.

[0174] In the method for producing a conjugated diene polymer of the present embodiment, after the coupling step, a deactivator, a neutralizer, and the like may be added to the polymer solution, if necessary. The quenching agent is not limited to the following, but examples thereof include water; alcohols such as methanol, ethanol, isopropanol, and the like; and the like. Examples of neutralizing agents include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture having 9 to 11 carbon atoms, with the majority having 10 carbon atoms); aqueous solutions of inorganic acids, and carbon dioxide gas.

[0175] In the method for producing a conjugated diene polymer of the present embodiment, it is preferable to add a rubber stabilizer from the viewpoint of preventing gel formation after polymerization and improving stability during processing. The rubber stabilizer is not limited to the following ones, and known ones can be used. For example, antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (hereinafter also referred to as "BHT"), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol)propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol are preferred.

[0176] [Conjugated diene polymer composition] In order to further improve the productivity of the conjugated diene polymer of the present embodiment and the processability when the conjugated diene polymer is made into a rubber composition containing a filler or the like, a rubber softener may be added to the conjugated diene polymer composition as necessary. The rubber softener is not particularly limited, but examples thereof include extender oil, liquid rubber, and resin. The method of adding a rubber softener to a conjugated diene polymer is not limited to the following, but a preferred method is to add a rubber softener to a conjugated diene polymer solution, mix, and remove the solvent from the resulting polymer solution containing the rubber softener.

[0177] Examples of preferred extender oils include aromatic oils, naphthenic oils, and paraffinic oils. Among these, aromatic substitute oils having a polycyclic aromatic (PCA) content of 3% by mass or less according to the IP346 method are preferred from the viewpoints of environmental safety, oil bleeding prevention, and wet grip properties. Examples of aromatic substitute oils include TDAE (Treated Distillate Aromatic Extracts), MES (Mild Extraction Solvate), and RAE (Residual Aromatic Extracts) as shown in Kautschuk Gummi Kunststoffe 52(12)799(1999).

[0178] Preferred liquid rubbers include, but are not limited to, liquid polybutadiene, liquid styrene-butadiene rubber, and the like. The effect of adding liquid rubber is that it improves the processability of a rubber composition containing a conjugated diene polymer and a filler, etc., and also shifts the glass transition temperature of the rubber composition to a lower temperature, which tends to improve the abrasion resistance, low hysteresis loss, and low temperature properties of the vulcanized product.

[0179] The preferred resins as the rubber softener include, but are not limited to, aromatic petroleum resins, coumarone-indene resins, terpene resins, rosin derivatives (including paulownia oil resins), tall oil, tall oil derivatives, rosin ester resins, natural and synthetic terpene resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, mixed aliphatic / aromatic hydrocarbon resins, coumarin-indene resins, phenolic resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, monoolefin oligomers, diolefin oligomers, hydrogenated aromatic hydrocarbon resins, cyclic aliphatic hydrocarbon resins, hydrogenated hydrocarbon resins, hydrocarbon resins, hydrogenated paulownia oil resins, hydrogenated oil resins, esters of hydrogenated oil resins and monofunctional or polyfunctional alcohols, etc. These resins may be used alone or in combination of two or more. When hydrogenating, all unsaturated groups may be hydrogenated, or some may be left.

[0180] The effect of adding the resin as a rubber softener is to improve the processability of a rubber composition containing the conjugated diene polymer and a filler, etc., and also to improve the breaking strength of a vulcanized product.

[0181] In the conjugated diene polymer composition of the present embodiment, the amount of the rubber softener, such as an extender oil, liquid rubber, or resin, added is not particularly limited, but is 1 part by mass or more and 60 parts by mass or less, preferably 5 parts by mass or more and 50 parts by mass or less, and more preferably 10 parts by mass or more and 37.5 parts by mass or less, relative to 100 parts by mass of the conjugated diene polymer of the present embodiment. When the rubber softener is added within the above range, the processability of the rubber composition containing the conjugated diene polymer and a filler, etc. is improved, and the breaking strength and abrasion resistance of the vulcanized product tend to be improved.

[0182] (Desolvation process) As described above, a rubber softener (e.g., extender oil) is added to a conjugated diene polymer solution and mixed to obtain a rubber softener-containing polymer solution, and a conjugated diene polymer composition can be obtained by a known method. For example, the method includes a method of separating the solvent by steam stripping or the like, filtering the polymer, and then dehydrating and drying it to obtain a polymer, a method of concentrating the polymer in a flashing tank and then devolatilizing the polymer with a vent extruder or the like, and a method of directly devolatilizing the polymer with a drum dryer or the like.

[0183] [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. From the viewpoint of improving fuel economy performance, processability, and abrasion resistance, the rubber component contains 10 parts by mass or more of the above-mentioned conjugated diene polymer or the above-mentioned conjugated diene polymer composition relative to the total amount (100 parts by mass) of the rubber component.

[0184] (Silica-based inorganic filler) The filler preferably includes a silica-based inorganic filler. By dispersing the silica-based inorganic filler in the rubber composition of the present embodiment, the processability when vulcanized tends to be excellent, and the vulcanized product tends to have low hysteresis loss, tensile strength, and abrasion resistance. 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 particularly preferable that the rubber composition contains a silica-based inorganic filler.

[0185] (rubber polymer) The rubber composition of this embodiment can use a rubbery polymer other than the conjugated diene-based polymer of this embodiment described above (hereinafter simply referred to as "other rubbery polymers") in combination with the conjugated diene-based polymer of this embodiment described above. Examples of the other rubber-like polymers include, but are not limited to, conjugated diene polymers or hydrogenated products thereof, random copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, block copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, non-diene polymers, and natural rubber. Specific examples of the rubber include styrene-based elastomers such as butadiene rubber or hydrogenated products thereof, isoprene rubber or hydrogenated products thereof, styrene-butadiene rubber or hydrogenated products thereof, styrene-butadiene block copolymer or hydrogenated products thereof, and styrene-isoprene block copolymer or hydrogenated products thereof; and acrylonitrile-butadiene rubber or hydrogenated products thereof. Examples of non-diene polymers include, but are not limited to, olefin elastomers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, and ethylene-octene rubber, butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylate-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber. Examples of natural rubber include, but are not limited to, smoked sheets such as RSS3 to 5, SMR, and epoxidized natural rubber. The various other rubber-like polymers mentioned above may be modified rubbers to which a polar functional group such as a hydroxyl group, an amino group, etc. When used for tires, butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber are preferably used.

[0186] From the viewpoint of the balance between performance and processing characteristics, the weight average molecular weight of the other rubber-like polymer is preferably from 2000 to 2,000,000, and more preferably from 5000 to 1,500,000. As the other rubber-like polymer, a low molecular weight rubber-like polymer, so-called liquid rubber, can also be used. The other rubber-like polymers may be used alone or in combination of two or more. When the rubber composition of this embodiment is a rubber composition containing the conjugated diene polymer of this embodiment and other rubbery polymers, the content ratio (mass ratio) of the above-mentioned conjugated diene polymer to the other rubbery polymers (the above-mentioned conjugated diene polymer / other rubbery polymers) is 10 / 90 or more and 100 / 0 or less, preferably 20 / 80 or more and 90 / 10 or less, and more preferably 30 / 70 or more and 80 / 20 or less. Therefore, the rubber component contains 10 parts by mass or more and 100 parts by mass or less, preferably 20 parts by mass or more and 90 parts by mass or less, and more preferably 30 parts by mass or more and 80 parts by mass or less, of the conjugated diene-based polymer of the present embodiment described above relative to the total amount (100 parts by mass) of the rubber component. When the content ratio of (the above-mentioned conjugated diene polymer / other rubber-like polymer) is within the above range, the vulcanizate has excellent tensile strength, abrasion resistance, and low hysteresis loss.

[0187] (Filler) The filler contained in the rubber composition of the present embodiment is not limited to the following, but examples thereof include the above-mentioned silica-based inorganic filler, carbon black, metal oxides, and metal hydroxides. Among these, silica-based inorganic fillers are preferred. The fillers may be used alone or in combination of two or more. The content of the filler in the rubber composition 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 above-mentioned conjugated diene-based polymer. 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 expressing the effect of adding the filler, and is 150 parts by mass or less per 100 parts by mass of the rubber component from the viewpoint of sufficiently dispersing the filler and making the processability and mechanical strength of the composition practically sufficient.

[0188] The silica-based inorganic filler is not particularly limited and any known filler can be used. 2 or Si 3 Solid particles containing Al as a constituent unit are preferred, and SiO 2 or Si 3 More preferred are solid particles containing Al as the main component of the structural units. Here, the main component refers to a component contained in the silica-based inorganic filler at 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more.

[0189] Specific silica-based inorganic fillers include, but are not limited to, inorganic fibrous materials such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber. Further examples include silica-based inorganic fillers whose surfaces have been made hydrophobic, and mixtures of silica-based inorganic fillers and inorganic fillers other than silica-based inorganic fillers. Among these, silica and glass fiber are preferred from the viewpoints of strength, abrasion resistance, and the like, and silica is more preferred. Examples of silica include dry silica, wet silica, and synthetic silicate silica. Among these silicas, wet silica is preferred from the viewpoint of improving tensile strength.

[0190] In order to obtain practically good abrasion resistance and breaking strength in the rubber composition of the present embodiment, the silica-based inorganic filler is preferably a filler having a nitrogen adsorption specific surface area of ​​100 m2 or less as determined by the BET adsorption method. 2 / g or more 300m 2 / g or less, and 2 / g or more 250m 2 / g or less. If necessary, the specific surface area is relatively small (for example, the specific surface area is 200 m 2 / g) and silica-based inorganic fillers with a relatively large specific surface area (e.g., 200 m 2 In particular, silica-based inorganic fillers with a relatively large specific surface area (e.g., 200 m 2 / g or more), the rubber composition containing the conjugated diene polymer of the present embodiment has improved dispersibility of the silica-based inorganic filler, which is particularly effective in improving abrasion resistance, and tends to achieve a high level of balance between good fracture strength and low hysteresis loss.

[0191] The content of the silica-based inorganic filler in the rubber composition of the present embodiment is preferably 5.0 parts by mass or more to 150 parts by mass, more preferably 20 parts by mass or more to 100 parts by mass or less, based on 100 parts by mass of the rubber component containing the conjugated diene polymer of the present embodiment described above. In the rubber composition of the present embodiment, the content of the silica-based inorganic filler is preferably 5.0 parts by mass or more based on 100 parts by mass of the rubber component from the viewpoint of expressing the effect of adding the silica-based inorganic filler, and is preferably 150 parts by mass or less based on 100 parts by mass of the rubber component from the viewpoint of dispersing the silica-based inorganic filler sufficiently and making the processability and mechanical strength of the rubber composition practically sufficient.

[0192] The rubber composition of the present embodiment may contain carbon black. Examples of carbon black include, but are not limited to, SRF, FEF, HAF, ISAF, SAF, and other classes of carbon black. 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.

[0193] In the rubber composition of the present embodiment, the content of carbon black is preferably 0.5 parts by mass or more and 100 parts by mass or less, more preferably 3.0 parts by mass or more and 100 parts by mass or less, and even more preferably 5.0 parts by mass or more and 50 parts by mass or less, per 100 parts by mass of the rubber component containing the conjugated diene polymer of the present embodiment. In the rubber composition of the present 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 realizing the 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 of the rubber component from the viewpoint of dispersibility.

[0194] (Metal oxides, metal hydroxides) The rubber composition of the present embodiment may contain a metal oxide or a metal hydroxide in addition to the silica-based inorganic filler and carbon black. Metal oxide refers to solid particles whose main component is a structural unit represented by the chemical formula MxOy (M represents a metal atom, and x and y each independently represent an integer of 1 to 6). Examples of metal oxides include, but are not limited to, alumina, titanium oxide, magnesium oxide, and zinc oxide. Examples of metal hydroxides include, but are not limited to, aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0195] (Silane coupling agent) The rubber composition of the present embodiment may contain a silane coupling agent. The silane coupling agent has the function of strengthening the interaction between the rubber component and the inorganic filler. In particular, when a silica-based inorganic filler is used as the inorganic filler, the silane coupling agent is preferably a compound having an affinity or binding group for each of the rubber component and the silica-based inorganic filler, and having a sulfur bond portion and an alkoxysilyl group or a silanol group portion in one molecule. Examples of such compounds include, but are not limited to, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide. In the rubber composition of the present embodiment, the content of the silane coupling agent is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, and even more preferably 1.0 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the inorganic filler. When the content of the silane coupling agent is within the above range, the above-mentioned addition effect of the silane coupling agent tends to be more remarkable.

[0196] (rubber softener) From the viewpoint of improving the processability of the rubber composition of the present embodiment, a rubber softener may be added in a separate step from the rubber softener added to the conjugated diene polymer of the present embodiment described above. The amount of rubber softener added is expressed as the total amount including the amount of rubber softener already contained in the above-mentioned 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 above-mentioned conjugated diene polymer. As the rubber softener, mineral oil or a liquid or low molecular weight synthetic softener is preferable. Mineral oil-based rubber softeners, called process oils or extender oils, which are used to soften rubber, increase its volume, and improve its processability, are mixtures of aromatic rings, naphthene rings, and paraffin chains, and those in which the carbon number of the paraffin chain is 50% or more of the total carbon are called paraffin-based, those in which the carbon number of the naphthene ring is 30% to 45% of the total carbon are called naphthene-based, and those in which the aromatic carbon number is more than 30% of the total carbon are called aromatic. When the conjugated diene polymer of the present embodiment is a copolymer of a conjugated diene compound and a vinyl aromatic compound, it is preferable to use a rubber softener having a moderate aromatic content, since it tends to be compatible with the copolymer. In the rubber composition of the present 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. By making the content of the rubber softener 100 parts by mass or less per 100 parts by mass of the rubber component, bleeding out is suppressed, and stickiness of the surface of the rubber composition tends to be suppressed.

[0197] [Method for producing rubber composition] The rubber composition of the present embodiment can be produced by mixing the rubber component consisting of the conjugated diene polymer of the present embodiment and other rubber-like polymers, silica-based inorganic fillers, carbon black and other fillers, silane coupling agents, rubber softeners, and other additives. The mixing methods are not limited to the following, but include, for example, a melt-kneading method using a general mixer such as an open roll, a Banbury mixer, a kneader, a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, and a method in which the components are dissolved and mixed and then the solvent is removed by heating. Among these, the melt-kneading method using a roll, a Banbury mixer, a kneader, or an extruder is preferred from the viewpoints of productivity and good kneadability. In addition, both a method of kneading the rubber component with the filler, the silane coupling agent, and the additives at once and a method of mixing them in multiple batches can be applied.

[0198] The rubber composition of the present embodiment may be a vulcanized composition that has been subjected to a vulcanization treatment with a vulcanizing agent. Examples of the vulcanizing agent include, but are not limited to, radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds. Examples of the sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, and polymeric polysulfur compounds. In the rubber composition of the present embodiment, the content of the vulcanizing agent is preferably 0.01 parts by mass to 20 parts by mass, more preferably 0.1 parts by mass to 15 parts by mass, based on 100 parts by mass of the rubber component. As the vulcanization method, a conventionally known method can be applied, and the vulcanization temperature is preferably 120°C to 200°C, more preferably 140°C to 180°C.

[0199] In vulcanization, a vulcanization accelerator may be used as necessary. As the vulcanization accelerator, a conventionally known material may be used, and examples thereof include, but are not limited to, sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators. In addition, a vulcanization aid may be used in the vulcanization, if necessary. Examples of the vulcanization aid include, but are not limited to, zinc oxide and stearic acid. The content of the vulcanization accelerator is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the rubber component.

[0200] In the rubber composition of the present embodiment, various additives such as softeners and fillers other than those described above, heat stabilizers, antistatic agents, weather stabilizers, antiaging agents, colorants, and lubricants may be used within the scope of the present embodiment. As the other softeners, known softeners can be used. As the other fillers, there are, but are not limited to, calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. As the above-mentioned heat stabilizers, antistatic agents, weather stabilizers, antiaging agents, colorants, and lubricants, known materials can be used.

[0201] 〔tire〕 The rubber composition of the present embodiment is suitably used as a rubber composition for tires. The rubber composition for tires is not limited to the following, but can be used in various tire parts such as fuel-efficient tires, all-season tires, high-performance tires, studless tires, etc., such as treads, carcasses, sidewalls, beads, etc. In particular, the rubber composition for tires is excellent in abrasion resistance, tensile strength, and low hysteresis loss when vulcanized, and is therefore suitably used for the treads of fuel-efficient tires and high-performance tires. EXAMPLES

[0202] Hereinafter, the present embodiment will be described in more detail with reference to specific examples and comparative examples, but the present embodiment is not limited in any way to the following examples and comparative examples. Various physical properties in the examples and comparative examples were measured by the methods shown below. In the following, the conjugated diene polymer before the coupling reaction will be referred to as the "conjugated diene polymer before the coupling reaction", and the coupled conjugated diene polymer will be referred to as the "coupled conjugated diene polymer", but these may be collectively referred to as the "conjugated diene polymer".

[0203] (Physical properties 1) Molecular weight Measurement condition 1: The conjugated diene polymer before the coupling reaction or the coupled conjugated diene polymer was used as a sample, and a chromatogram was measured using a GPC measurement device (manufactured by Tosoh Corporation under the trade name "HLC-8320GPC") in which three columns packed with polystyrene gel were connected together, and an RI detector (manufactured by Tosoh Corporation under the trade name "HLC8020") was used. Based on a calibration curve obtained using standard polystyrene, the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were determined. The eluent used was tetrahydrofuran (THF) containing 5 mmol / L triethylamine. Three columns, Tosoh Corporation's "TSKgel SuperMultiporeHZ-H" (trade name), were connected, and a Tosoh Corporation's "TSKguardcolumn SuperMP(HZ)-H" (trade name) was connected in front of them as a guard column. 10 mg of the measurement sample was dissolved in 10 mL of THF to prepare a measurement solution, and 10 μL of the measurement solution was injected into a GPC measurement device and measured under conditions of an oven temperature of 40° C. and a THF flow rate of 0.35 mL / min. Among the various samples measured under the above measurement condition 1, samples whose molecular weight distribution (Mw / Mn) was less than 1.6 were measured again under the following measurement condition 2. For samples that were measured under measurement condition 1 and had a molecular weight distribution value of 1.6 or more, measurement was performed under measurement condition 1 and the measured value was adopted. Measurement condition 2: The conjugated diene polymer before the coupling reaction or the coupled conjugated diene polymer was used as a sample, and a chromatogram was measured using a GPC measuring device having 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 following: guard column: Tosoh Corporation's product name "TSKguardcolumn SuperH-H"; columns: Tosoh Corporation's product names "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000". An RI detector (manufactured by Tosoh Corporation under the trade name "HLC8020") was used under the conditions of an oven temperature of 40° C. and a THF flow rate of 0.6 mL / min. 10 mg of a sample to be measured was dissolved in 20 mL of THF to prepare a measurement solution, and 20 μL of the measurement solution was injected into a GPC measurement device for measurement. For samples that were measured under measurement condition 1 and had a molecular weight distribution value of less than 1.6, measurement was performed under measurement condition 2, and the measured value was adopted.

[0204] (Physical Property 2) Polymer Mooney Viscosity The conjugated diene polymer before the coupling reaction or the coupled conjugated diene polymer was used as a sample, and the Mooney viscosity was measured using a Mooney viscometer (manufactured by Ueshima Seisakusho Co., Ltd., product name "VR1132") in accordance with ISO 289 using an L-type rotor. The measurement temperature was 110° C. when the conjugated diene polymer before the coupling reaction was used as the sample, and 120° C. when the coupled conjugated diene polymer was used as the sample. First, the sample was preheated at the test temperature for 1 minute, and then the rotor was rotated at 2 rpm. The torque was measured after 4 minutes to determine the Mooney viscosity (ML (1+4) ) was decided.

[0205] (Physical property 3) Branching degree (Bn) The branching degree (Bn) of the conjugated diene polymer was measured by a GPC-light scattering method equipped with a viscosity detector as follows. A coupling conjugated diene polymer was used as a sample, and measurements were performed using a gel permeation chromatography (GPC) measuring device (manufactured by Malvern under the trade name "GPCmax VE-2001") in which three columns packed with polystyrene gel were connected together, and three detectors were connected in that order: a light scattering detector, an RI detector, and a viscosity detector (manufactured by Malvern under the trade name "TDA305"). Based on standard polystyrene, the absolute molecular weight was calculated from the results of the light scattering detector and the RI detector, and the intrinsic viscosity was calculated from the results of the RI detector and the viscosity detector. Linear polymer has an intrinsic viscosity [η] = -3.883M 0.771 The shrinkage factor (g') was calculated as the ratio of the intrinsic viscosity corresponding to each molecular weight, where M represents the absolute molecular weight. The obtained shrinkage factor (g') was then used to calculate the branching degree (Bn), defined as g' = 6Bn / [(Bn+1)(Bn+2)]. The eluent used was tetrahydrofuran (hereinafter also referred to as "THF") containing 5 mmol / L triethylamine. The columns used were "TSKgel G4000HXL", "TSKgel G5000HXL", and "TSKgel G6000HXL" manufactured by Tosoh Corporation. 20 mg of the measurement sample was dissolved in 10 mL of THF to prepare a measurement solution, and 100 μL of the measurement solution was injected into a GPC measurement device and measured under conditions of an oven temperature of 40° C. and a THF flow rate of 1 mL / min.

[0206] (Physical property 4) Modification rate The modification rate of the conjugated diene polymer was measured by column adsorption GPC as follows. The coupling conjugated diene polymer was used as a sample, and the measurement was carried out by utilizing the adsorption property of the modified basic polymer component in a GPC column packed with silica gel. The amount of a sample solution containing a sample and low molecular weight internal standard polystyrene was adsorbed onto the silica-based column by measuring the difference between the chromatogram measured using a polystyrene-based column and the chromatogram measured using a silica-based column, and the modification rate was calculated. Specifically, the measurements are as follows: In addition, the above-mentioned (Physical property 1) was performed under measurement condition 1. For samples whose molecular weight distribution was 1.6 or more, the measurements were performed under measurement condition 3 below, and for samples whose molecular weight distribution was less than 1.6, the measurements were performed under measurement condition 4 below. <Preparation of sample solution>: 10 mg of the sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF to prepare a sample solution. GPC measurement conditions using polystyrene column: Measurement condition 3: Using a Tosoh Corporation product name "HLC-8320GPC," 10 μL of the sample solution was injected into the device using 5 mmol / L triethylamine-containing THF as the eluent, and a chromatogram was obtained using an RI detector under the conditions of a column oven temperature of 40°C and a THF flow rate of 0.35 mL / min. Three Tosoh Corporation product name "TSKgel SuperMultiporeHZ-H" columns were connected, and a Tosoh Corporation product name "TSKguardcolumn SuperMP(HZ)-H" was connected in front of them as a guard column. Measurement condition 4: THF containing 5 mmol / L triethylamine was used as the eluent, and 20 μL of the sample solution was injected into the device for measurement. The guard column was Tosoh Corporation's product name "TSKguardcolumn SuperH-H", and the columns were Tosoh Corporation's product names "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000". The chromatogram was obtained by measurement using an RI detector (Tosoh Corporation's HLC8020) under the conditions of a column oven temperature of 40°C and a THF flow rate of 0.6 mL / min. GPC measurement conditions using a silica column: A Tosoh Corporation product name "HLC-8320GPC" was used, THF was used as the eluent, 50 μL of the sample solution was injected into the device, and a chromatogram was obtained using an RI detector under the conditions of a column oven temperature of 40°C and a THF flow rate of 0.5 ml / min. The columns used were Zorbax PSM-1000S, PSM-300S, and PSM-60S, and a guard column "DIOL 4.6 × 12.5 mm 5 micron" was connected to the front of the columns. How to calculate the denaturation rate: The total peak area of ​​the chromatogram using the polystyrene column was set as 100, the peak area of ​​the sample was set as P1, the peak area of ​​the standard polystyrene was set as P2, the total peak area of ​​the chromatogram using the silica column was set as 100, the peak area of ​​the sample was set as P3, and the peak area of ​​the standard polystyrene was set as P4, and the modification rate (%) was calculated using the following formula. Denaturation rate (%) = [1-(P2 x P3) / (P1 x P4)] x 100 (where P1+P2=P3+P4=100)

[0207] (Physical property 5) Bound styrene content A coupling conjugated diene polymer not containing a rubber softener was used as a sample, and 100 mg of the sample was dissolved in chloroform up to 100 mL to prepare a measurement sample. The amount of bound styrene (mass%) relative to 100 mass% of the sample coupled conjugated diene polymer was measured based on the amount of absorption of ultraviolet light (around 254 nm) by the phenyl group of styrene (measuring device: Shimadzu Corporation spectrophotometer "UV-2450").

[0208] (Physical property 6) Microstructure of butadiene part (1,2-vinyl bond amount) A coupling conjugated diene polymer not containing a rubber softener was used as a sample, and 50 mg of the sample was dissolved in 10 mL of carbon disulfide to prepare a measurement sample. -1 The absorbance at a predetermined wave number was measured in the range of 100 nm to 150 nm, and the microstructure of the butadiene portion, i.e., the amount of 1,2-vinyl bonds (mol%) was calculated according to the formula of Hampton's method (method described in R.R. Hampton, Analytical Chemistry 21, 923 (1949)) (measuring device: Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation).

[0209] (Physical Property 7) Molecular weight (absolute molecular weight) measured by GPC-light scattering method The coupling conjugated diene polymer was used as a sample, and a chromatogram was measured using a GPC-light scattering measuring device in which three columns packed with polystyrene gel were connected, and the weight average molecular weight (Mw-i) was calculated based on the solution viscosity and the light scattering method (also referred to as "absolute molecular weight"). The eluent used was a mixed solution of tetrahydrofuran and triethylamine (THF in TEA: prepared by mixing 5 mL of triethylamine in 1 L of tetrahydrofuran). The columns used were a guard column (manufactured by Tosoh Corporation under the trade name "TSKguardcolumn HHR-H") and columns (manufactured by Tosoh Corporation under the trade names "TSKgel G6000HHR", "TSKgel G5000HHR", and "TSKgel G4000HHR"). A GPC-light scattering measurement device (trade name "Viscotek TDAmax" manufactured by Malvern Instruments) was used under the conditions of an oven temperature of 40° C. and a THF flow rate of 1.0 mL / min. 10 mg of a sample to be measured was dissolved in 20 mL of THF to prepare a measurement solution, and 200 μL of the measurement solution was injected into the GPC measurement device for measurement.

[0210] (Physical property 8) Glass transition temperature (Tg) When the coupling conjugated diene polymer is an oil-extended product, the coupling conjugated diene polymer after the extension oil is extracted is used as a sample, and a DSC curve is recorded using a differential scanning calorimeter "DSC3200S" manufactured by Mac Science Co., Ltd. in accordance with ISO 22768:2006 while heating from -100°C at 20°C / min under a helium flow of 50 mL / min, and the peak top (inflection point) of the DSC differential curve is taken as the glass transition temperature.

[0211] (Physical property 9) Nitrogen content When the coupling conjugated diene polymer is an oil-extended product, the coupling conjugated diene polymer after the extension oil is extracted is used as a sample, and the nitrogen content is determined using a total nitrogen trace analyzer ("TN-2100H" manufactured by Mitsubishi Chemical Analytech Co., Ltd.) in accordance with JIS-2609: Crude oil and petroleum products - Nitrogen content test method, chemiluminescence method.

[0212] [Production of Conjugated Diene Polymer] (Example 1) Coupling conjugated diene polymer (A1) Two tank-type pressure vessels having an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom and an outlet at the top, and an agitator as a tank-type reactor and a jacket for temperature control were connected together as polymerization reactors. 1,3-butadiene, which had been previously dehydrated, was mixed at 17.7 g / min, styrene at 10.9 g / min, and cyclohexane at 175.2 g / min. In a static mixer installed in the middle of the pipe supplying this mixed solution to the inlet of the reactor, n-butyllithium for inactivating remaining impurities was added at 0.103 mmol / min, mixed, and then continuously supplied to the bottom of the reactor. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance was supplied at a rate of 0.064 mmol / min, and n-butyllithium as a polymerization initiator was supplied at a rate of 0.134 mmol / min to the bottom of the first reactor, which was vigorously mixed with a stirrer, and the temperature inside the reactor was maintained at 77°C. The polymer solution was continuously withdrawn from the top of the first reactor and continuously fed to the bottom of the second reactor, where the reaction was continued at 82°C, and further fed to a static mixer from the top of the second reactor. When the polymerization was sufficiently stable, trimethoxy(4-vinylphenyl)silane was added as a branching agent at a rate of 0.007mmol / min from the bottom of the second reactor while copolymerizing 1,3-butadiene and styrene, and a polymerization reaction and a branching reaction were carried out to obtain a conjugated diene polymer having a main chain branched structure. When the polymerization reaction and the branching reaction were further stabilized, a small amount of the conjugated diene polymer solution before the addition of the coupling agent was withdrawn, and an antioxidant (BHT) was added so that the amount was 0.2g per 100g of polymer, after which the solvent was removed, and various molecular weights (physical property 1) and Mooney viscosity (physical property 2) were measured. The physical properties are shown in Table 1. Next, N-benzylidene-3-(triethoxysilyl)propan-1-amine (abbreviated as "a" in the table) was added continuously as a coupling agent to the polymer solution flowing out from the outlet of the reactor at a rate of 0.043 mmol / min, and the mixture was mixed using a static mixer to carry out a coupling reaction. At this time, the time until the coupling agent was added to the polymer solution flowing out from the outlet of the reactor was 4.8 minutes, the temperature was 68°C, and the difference between the temperature in the polymerization process and the temperature before the coupling agent was added was 2°C. A small amount of the conjugated diene polymer solution after the coupling reaction was withdrawn, and an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of polymer, and then the solvent was removed, and the amount of bound styrene (physical property 5) and the microstructure of the butadiene portion (1,2-vinyl bond amount: physical property 6) were measured. The measurement results are shown in Table 1. Next, an antioxidant (BHT) was continuously added to the polymer solution after the coupling reaction at 0.055 g / min (n-hexane solution) so that the amount was 0.2 g per 100 g of polymer, and the coupling reaction was terminated. Simultaneously with the antioxidant, SRAE oil (JOMO Process NC140 manufactured by JX Nippon Oil & Energy Corporation) was continuously added as a rubber softener so that the amount was 25.0 g per 100 g of polymer, and mixed with a static mixer. The solvent was removed by steam stripping to obtain a coupling conjugated diene polymer (A1) having a 4-branch structure derived from a branching agent (hereinafter also referred to as "branching agent structure (1)"), which is a compound represented by the following formula (1), in a part of the main chain and a 3-branch star polymer structure derived from the coupling agent. The physical properties of A1 are shown in Table 1. The structure of the coupling conjugated diene polymer was identified by comparing the molecular weight measured by GPC and the branching degree measured by GPC with a viscometer for the polymer before the addition of the branching agent, the polymer after the addition of the branching agent, and the polymer in each step after the addition of the coupling agent. The structure of each sample was similarly identified.

[0213] [ka]

[0214] (In formula (1), R1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, which may partially have a branched structure. 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 partially have a branched structure. R when multiple exist 1 ~R 3 are each independent. X 1 represents an independent halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3.)

[0215] (Example 2) Coupling conjugated diene polymer (A2) Except for changing the polar substance 2,2-bis(2-oxolanyl)propane to 0.055 mmol / min, the procedure was the same as in Example 1 to obtain a coupling diene copolymer (A2). The physical properties of A2 are shown in Table 1.

[0216] (Example 3) Coupling conjugated diene polymer (A3) A coupling conjugated diene copolymer (A3) was obtained in the same manner as in Example 1, except that the polymerization initiator n-butyllithium was 0.152 mmol / min, 2,2-bis(2-oxolanyl)propane was 0.070 mmol / min, the branching agent trimethoxy(4-vinylphenyl)silane was 0.008 mmol / min, the coupling agent was changed from N-benzylidene-3-(triethoxysilyl)propane-1-amine to tetrakis(3-trimethoxysilylpropyl-1,3propanediamine (abbreviated as "b" in the table), and the amount of the coupling agent added was 0.015 mmol / min. The physical properties of A3 are shown in Table 1.

[0217] (Example 4) Coupling conjugated diene polymer (A4) A coupling conjugated diene copolymer (A4) was obtained in the same manner as in Example 1, except that the coupling agent was changed from N-benzylidene-3-(triethoxysilyl)propan-1-amine to tetraethoxysilane (abbreviated as "c" in the table) and the amount of the coupling agent added was 0.018 mmol / min. The physical properties of A4 are shown in Table 1.

[0218] (Example 5) Coupling conjugated diene polymer (A5) A coupling conjugated diene copolymer (A5) was obtained in the same manner as in Example 1, except that 1,3-butadiene, styrene, and 2,2-bis(2-oxolanyl)propane were fed at rates of 15.8 g / min, 12.8 g / min, and 0.070 mmol / min, respectively. The physical properties of A5 are shown in Table 1.

[0219] (Example 6) Coupling conjugated diene polymer (A6) A coupling conjugated diene copolymer (A6) was obtained in the same manner as in Example 1, except that 1,3-butadiene was 20.0 g / min, styrene was 8.6 g / min, 2,2-bis(2-oxolanyl)propane was 0.058 mmol / min, and the rubber softener was 37.5 g of SRAE oil per 100 g of polymer. The physical properties of A6 are shown in Table 1.

[0220] (Example 7) Coupling conjugated diene polymer (A7) A coupling conjugated diene copolymer (A7) was obtained in the same manner as in Example 1, except that the polymerization initiator n-butyllithium was 0.103 mmol / min, 2,2-bis(2-oxolanyl)propane was 0.045 mmol, the branching agent trimethoxy(4-vinylphenyl)silane was 0.005 mmol / min, and the amount of the coupling agent added was 0.033 mmol / min. The physical properties of A7 are shown in Table 2.

[0221] (Example 8) Coupling conjugated diene polymer (A8) A coupling conjugated diene copolymer (A8) was obtained in the same manner as in Example 1, except that the polymerization initiator n-butyllithium was 0.188 mmol / min, 2,2-bis(2-oxolanyl)propane was 0.089 mmol / min, the branching agent trimethoxy(4-vinylphenyl)silane was 0.009 mmol / min, and the amount of coupling agent added was 0.060 mmol / min. The physical properties of A8 are shown in Table 2.

[0222] (Example 9) Coupling conjugated diene polymer (A9) A coupling conjugated diene copolymer (A9) was obtained in the same manner as in Example 1, except that the polymerization initiator n-butyllithium was 0.152 mmol / min, 2,2-bis(2-oxolanyl)propane was 0.016 mmol / min, the branching agent trimethoxy(4-vinylphenyl)silane was 0.008 mmol / min, the coupling agent was changed from N-benzylidene-3-(triethoxysilyl)propane-1-amine to tetrakis(3-trimethoxysilylpropyl-1,3propanediamine (abbreviated as "b" in the table), and the amount of the coupling agent added was 0.015 mmol / min. The physical properties of A9 are shown in Table 2.

[0223] (Example 10) Coupling conjugated diene polymer (A10) A coupling diene copolymer (A10) was obtained in the same manner as in Example 8, except that the polymerization initiator was a mixed solution of piperidinolithium (also called "1-lithiopiperidine") and n-butyllithium (the molar ratio of the mixed solution was 0.75:0.25) as a lithium amide prepared in advance. The physical properties of A10 are shown in Table 2.

[0224] (Example 11) Coupling conjugated diene polymer (A11) A coupling diene copolymer (A11) was obtained in the same manner as in Example 1, except that the coupling agent was a mixed solution (abbreviated as "a / b" in the table) previously prepared so that the addition rate of N-benzylidene-3-(triethoxysilyl)propan-1-amine was 0.0130 mmol / min and the addition rate of tetrakis(3-trimethoxysilylpropyl-1,3propanediamine was 0.0075 mmol / min. The physical properties of A11 are shown in Table 2.

[0225] (Example 12) Coupling conjugated diene polymer (A12) A mixed solution with tetrakis(3-trimethoxysilylpropyl-1,3propanediamine (abbreviated as "d / b" in the table) was prepared in the same manner as in Example 11, except that the coupling agent was changed from N-benzylidene-3-(triethoxysilyl)propan-1-amine to 3-(4-methylpiperazin-1-yl)propyltrimethoxysilane. The other conditions were the same as in Example 1, and a coupling diene copolymer (A12) was obtained. The physical properties of A12 are shown in Table 2.

[0226] (Comparative Example 1) Coupling Conjugated Diene Polymer (B1) Two tank-type pressure vessels having an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom and an outlet at the top, and an agitator as a tank-type reactor and a jacket for temperature control were connected together as polymerization reactors. 1,3-butadiene, from which moisture had been removed in advance, was mixed at 18.6 g / min, styrene at 10.0 g / min, and cyclohexane at 175.2 g / min to obtain a mixed solution. In a static mixer installed in the middle of the pipe supplying this mixed solution to the inlet of the reactor, n-butyllithium for inactivating remaining impurities was added at 0.103 mmol / min, mixed, and then continuously supplied to the bottom of the reactor. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance at a rate of 0.072 mmol / min and n-butyllithium as a polymerization initiator at a rate of 0.134 mmol / min were supplied to the bottom of the first reactor, which was vigorously mixed with a stirrer, and the temperature inside the reactor was maintained at 77°C. The polymer solution was continuously withdrawn from the top of the first reactor and continuously fed to the bottom of the second reactor to continue the reaction at 82°C, and then fed to a static mixer from the top of the second reactor. A small amount of the conjugated diene polymer solution before the addition of the coupling agent was withdrawn, and an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of polymer, after which the solvent was removed and the Mooney viscosity at 110°C and various molecular weights were measured. The physical properties are shown in Table 3. Next, N-benzylidene-3-(triethoxysilyl)propan-1-amine was added continuously as a coupling agent at a rate of 0.043 mmol / min to the polymer solution flowing out from the outlet of the reactor, and the mixture was mixed using a static mixer to carry out a coupling reaction. At this time, the time until the coupling agent was added to the polymer solution flowing out from the outlet of the reactor was 4.8 minutes, the temperature was 68°C, and the difference between the temperature in the polymerization process and the temperature before the coupling agent was added was 2°C. A small amount of the conjugated diene polymer solution after the coupling reaction was extracted, and an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of polymer, and then the solvent was removed, and the amount of bound styrene (physical property 5) and the microstructure of the butadiene portion (1,2-vinyl bond amount: physical property 6) were measured. The measurement results are shown in Table 3. Next, an antioxidant (BHT) was continuously added to the polymer solution after the coupling reaction at 0.055 g / min (n-hexane solution) so that the amount was 0.2 g per 100 g of polymer, and the coupling reaction was terminated. Simultaneously with the antioxidant, SRAE oil (JOMO Process NC140 manufactured by JX Nippon Oil & Energy Corporation) was continuously added as a rubber softener so that the amount was 25.0 g per 100 g of polymer, and mixed with a static mixer. The solvent was removed by steam stripping to obtain a coupling conjugated diene polymer (B1). The physical properties of B1 are shown in Table 3. The structure of the coupling conjugated diene polymer was identified by comparing the molecular weight measured by GPC and the branching degree measured by GPC with a viscometer for the polymer in each process after the addition of the coupling agent.

[0227] (Comparative Example 2) Coupling Conjugated Diene Polymer (B2) The flow rates were 17.7 g / min for 1,3-butadiene, 10.9 g / min for styrene, 0.152 mmol / min for the polymerization initiator n-butyllithium, and 0.070 mmol / min for 2,2-bis(2-oxolanyl)propane, and no branching agent was added. In addition, the coupling agent was changed from N-benzylidene-3-(triethoxysilyl)propane-1-amine to tetrakis(3-trimethoxysilylpropyl-1,3propanediamine (abbreviated as "b" in the table), and the amount of the coupling agent added was 0.015 mmol / min. The procedure was the same as in Comparative Example 1 to obtain a coupling conjugated diene copolymer (B2). The physical properties of B2 are shown in Table 3.

[0228] (Comparative Example 3) Coupling Conjugated Diene Polymer (B3) The polymerization initiator n-butyllithium was 0.152 mmol / min, 2,2-bis(2-oxolanyl)propane was 0.093 mmol / min, and no branching agent was added. In addition, the coupling agent was changed from N-benzylidene-3-(triethoxysilyl)propane-1-amine to tetrakis(3-trimethoxysilylpropyl-1,3-propanediamine (abbreviated as "b" in the table), and the amount of the coupling agent added was 0.015 mmol / min. Except for this, a coupling conjugated diene copolymer (B3) was obtained in the same manner as in Comparative Example 1. The physical properties of B3 are shown in Table 3.

[0229] (Comparative Example 4) Coupling Conjugated Diene Polymer (B4) The 1,3-butadiene was 14.3 g / min, the styrene was 14.3 g / min, the polymerization initiator n-butyllithium was 0.152 mmol / min, 2,2-bis(2-oxolanyl)propane was 0.103 mmol / min, the branching agent trimethoxy(4-vinylphenyl)silane was 0.008 mmol / min, the coupling agent was changed from N-benzylidene-3-(triethoxysilyl)propane-1-amine to tetrakis(3-trimethoxysilylpropyl-1,3propanediamine (abbreviated as "b" in the table), and the amount of the coupling agent added was 0.015 mmol / min. Except for this, a coupling conjugated diene copolymer (B4) was obtained in the same manner as in Comparative Example 1. The physical properties of B4 are shown in Table 3.

[0230] (Comparative Example 5) Coupling Conjugated Diene Polymer (B5) A coupling conjugated diene copolymer (B5) was obtained in the same manner as in Comparative Example 4, except that 1,3-butadiene was fed at 21.4 g / min, styrene at 7.2 g / min, and 2,2-bis(2-oxolanyl)propane at 0.042 mmol / min. The physical properties of B5 are shown in Table 3.

[0231] [Table 1]

[0232] [Table 2]

[0233] [Table 3]

[0234] (Examples 13 to 24 and Comparative Examples 6 to 10) Using samples A1 to A12 and B1 to B5 shown in Tables 1 to 3 as raw rubbers, rubber compositions containing each raw rubber were obtained according to the formulations shown below.

[0235] Coupling conjugated diene polymer (A1 to A12 and B1 to B5: 100 parts by mass (excluding oil) Silica 1 (product name "Ultrasil 7000GR" manufactured by Evonik Degussa, nitrogen adsorption specific surface area 170 m2 / g): 75.0 parts by mass Carbon black (product name "Seast KH (N339)" manufactured by Tokai Carbon Co., Ltd.): 5.0 parts by mass Silane coupling agent (product name "Si75" manufactured by Evonik Degussa, bis(triethoxysilylpropyl)disulfide): 6.0 parts by mass S-RAE oil (product name "Process NC140" manufactured by JX Nippon Oil & Energy Corporation): 37.5 parts by mass (This includes the amount previously added as a rubber softener contained in samples A1 to A12 and B1 to B5.) Zinc white: 2.5 parts by mass Stearic acid: 2.0 parts by weight Antiaging agent (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 2.0 parts by mass Sulfur: 1.7 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

[0236] The above materials were kneaded by the following method to obtain rubber compositions. Using an internal mixer (capacity 0.3 L) equipped with a temperature control device, the raw rubber (samples A1 to A12, B1 to B5), fillers (silica 1, silica 2, carbon black), silane coupling agent, process oil, zinc oxide, and stearic acid were kneaded in the first stage of kneading under conditions of a filling rate of 65% and a rotor rotation speed of 30 to 50 rpm. At this time, the temperature of the internal mixer was controlled, and each rubber composition (compound) was obtained at a discharge temperature of 155 to 160°C.

[0237] Next, in the second stage of kneading, the compound obtained above was cooled to room temperature, and then an antioxidant was added and kneaded again to improve the dispersion of silica. In this case, the discharge temperature of the compound was adjusted to 155 to 160°C by controlling the temperature of the mixer. After cooling, in the third stage of kneading, sulfur and vulcanization accelerators 1 and 2 were added and kneaded with an open roll set at 70°C. Then, the product was molded and vulcanized at 160°C for 20 minutes in a vulcanization press. The rubber composition before vulcanization and the rubber composition after vulcanization were evaluated. Specifically, the evaluation was performed by the following method. The results are shown in Tables 4 to 6.

[0238] (Rating 1) Tensile strength The tensile strength was measured according to the tensile testing method of JIS K6251, and the result of Comparative Example 6 was indexed to 100. A larger index indicates better tensile strength and tensile elongation.

[0239] (Evaluation 2) Abrasion resistance Using an Acron abrasion tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), the amount of wear was measured at a load of 44.4 N and 1000 revolutions in accordance with JIS K6264-2, and indexed with the result of Comparative Example 6 set at 100. A higher index indicates better abrasion resistance.

[0240] (Rating 3) Fuel efficiency The viscoelastic parameters were measured in torsion mode using a viscoelasticity tester "ARES" manufactured by Rheometrics Scientific. Each measured value was indexed with the result for the rubber composition of Comparative Example 6 being 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. The higher the index, the better the 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 (RR performance). The higher the index, the better the fuel economy.

[0241] [Table 4]

[0242] [Table 5]

[0243] [Table 6]

[0244] As shown in Tables 4 to 6, it was confirmed that Examples 13 to 24, which used the coupling conjugated diene polymers (A1 to A12) of Examples 1 to 12, had an excellent balance of tensile strength, abrasion resistance, and low hysteresis loss when vulcanized, compared with Comparative Examples 6 to 10, which used the coupling conjugated diene polymers of Comparative Examples 1 to 5. [Industrial Applicability]

[0245] The rubber composition according to the present invention has industrial applicability in the fields of tire treads, interior and exterior parts of automobiles, anti-vibration rubber, belts, footwear, foams, various industrial goods, and the like.

Claims

1. The branching degree (Bn) measured by a GPC-light scattering method with a viscosity detector is 7 or more, Weight average molecular weight is 45×10 4 Above 500 x 10 4 A conjugated diene-based polymer having the following structure: The content of aromatic vinyl monomer units in the conjugated diene polymer is 30 to 45 mass %, The content (mass%) of the aromatic vinyl monomer unit is greater than the amount (mol%) of the vinyl bond in the conjugated diene monomer unit. Conjugated diene polymer.

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

3. The conjugated diene polymer according to claim 1 or 2, which contains a nitrogen atom and a silicon atom.

4. The conjugated diene polymer has a star polymer structure with three or more branches, At least one branched chain of the star-shaped structure 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 further main chain branched structure. The conjugated diene polymer according to any one of claims 1 to 3.

5. The vinyl monomer containing an alkoxysilyl group or a halosilyl group is A compound represented by the following formula (1) or (2): The conjugated diene polymer according to claim 4. 【Chemistry 1】 【Chemistry 2】 (In formula (1), R 1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, which may partially have a branched structure. 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 partially have a branched structure. R when there are multiple 1 ~R 3 are each independent. X 1 represents an independent halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3. (In formula (2), 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 partially have a branched structure. 2 ~R 5 are each independent. X 2 ~X 3 represents an independent halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3. a represents an integer from 0 to 2, b represents an integer from 0 to 3, and c represents an integer from 0 to 3. (a+b+c) represents 3.)

6. In the formula (1), R 1 The conjugated diene polymer according to claim 5 , which has a monomer unit based on the compound represented by formula (1) in which m is a hydrogen atom and m=0.

7. The conjugated diene polymer according to claim 5 , which has a monomer unit based on a compound represented by formula (2) in which m=0 and b=0.

8. In the formula (1), R 1 The conjugated diene polymer according to claim 5 , having a monomer unit based on the compound represented by formula (1) in which:

9. The conjugated diene polymer according to claim 5, having a monomer unit based on a compound represented by formula (2), in which m = 0, l = 0, n = 3, a = 0, b = 0, and c = 3.

10. A method for producing the conjugated diene polymer according to any one of claims 1 to 9, A method for producing a conjugated diene polymer, comprising the steps of: polymerizing at least a conjugated diene compound and an aromatic vinyl compound in a solvent containing a polar compound using an organolithium compound as a polymerization initiator; and adding a branching agent which is a vinyl monomer containing an alkoxysilyl group or a halosilyl group represented by the following formula (1) or (2), to obtain a conjugated diene polymer having a main chain branched structure: 【Chemistry 3】 【Chemistry 4】 In formula (1), R 1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, which may partially have a branched structure. R 2 and R 3 each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, which may partially have a branched structure. When a plurality of R 1 to R 3 are present, they are each independent. X 1 independently represents a halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3. In formula (2), R 2 to R 5 each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and may partially have a branched structure. When a plurality of R 2 to R 5 are present, each is independent of each other. X 2 and X 3 each independently represent a halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3. a represents an integer from 0 to 2, b represents an integer from 0 to 3, and c represents an integer from 0 to 3. (a+b+c) represents 3.)

11. The method for producing a conjugated diene polymer according to claim 10, further comprising a step of reacting the conjugated diene polymer having a main chain branched structure with a coupling agent which is a reactive compound having two or more functionalities.

12. 100 parts by mass of the conjugated diene polymer according to any one of claims 1 to 9; 1 to 60 parts by mass of a rubber softener; A conjugated diene polymer composition comprising:

13. A rubber composition comprising a rubber component and 5.0 parts by mass or more and 150 parts by mass or less of a filler per 100 parts by mass of the rubber component, A rubber composition comprising the rubber component comprising 10 parts by mass or more of the conjugated diene-based polymer according to claim 1 relative to 100 parts by mass of the total amount of the rubber component.

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