Modified conjugated diene polymer, molded body, method for producing modified conjugated diene polymer, rubber composition, and tire

Abstract

Disclosed is a modified conjugated diene polymer which satisfies conditions (i) to (iii) described below. Condition (i): The molecular weight distribution curve by gel permeation chromatography (GPC) has a unimodal shape, and the molecular weight distribution (PDI; MWD) is 1.7-3.5. Condition (ii) > The modification rate is 40 mass% or more. Condition (iii): A DSC differential curve obtained by differentiating a DSC curve recorded by differential scanning calorimetry (DSC) measurement has two or more peaks.

Description

Modified conjugated diene polymer, molded product, method for producing modified conjugated diene polymer, rubber composition, and tire

[0001] The present invention relates to a modified conjugated diene polymer, a molded article, a method for producing a modified conjugated diene polymer, a rubber composition, and a tire.

[0002] In recent years, growing interest in energy conservation and environmental issues has led to demands for improved fuel efficiency in automobiles. Therefore, rubber materials used in automobile tires, particularly in tire treads that come into contact with the road surface, are required to have low rolling resistance and excellent abrasion resistance, as well as wet skid resistance and practically sufficient fracture properties from the viewpoint of safety.

[0003] Furthermore, in response to the trend toward lower fuel consumption in automobiles, progress is being made in reducing the weight of automobiles by using resin for automobile components and thinning tires. Thinning tires requires a reduction in the thickness of the tread, which requires high wear resistance.

[0004] Examples of rubber materials that meet the above-mentioned requirements include materials containing a rubber-like polymer and a reinforcing filler such as carbon black or silica. For example, the use of a material containing silica can improve the balance between low hysteresis loss and wet skid resistance. Furthermore, attempts have been made to improve the dispersibility of silica in the material by introducing functional groups that have affinity or reactivity with silica into the molecular terminals of highly mobile rubber, and further to reduce the mobility of the rubber molecular terminals by bonding with silica particles, thereby reducing hysteresis loss and improving abrasion resistance and fracture strength.

[0005] As the rubber-like polymer, a modified conjugated diene polymer is used. With regard to the conjugated diene polymer, the molecular weight of the modified conjugated diene polymer is being increased in order to improve breaking strength and abrasion resistance.

[0006] However, high-molecular-weight modified conjugated diene polymers have the problem that polymer particles tend to peel off from the surface of the bale of the modified conjugated diene polymer itself, contaminating the area around the molding machine and the area around the conveyor that transports the bale after molding, leaving room for improvement in terms of the working environment. Furthermore, increasing the molecular weight of the modified conjugated diene polymer is accompanied by an increase in the viscosity of the composition, which tends to result in poor dispersion of reinforcing fillers such as carbon black and silica during kneading, leaving room for improvement in terms of processability. When such materials are vulcanized, particularly when they are vulcanized to contain inorganic fillers such as silica, the low hysteresis loss, abrasion resistance, and fracture strength are insufficient.

[0007] One method for preventing such high-molecular-weight modified conjugated diene polymers from peeling off from the surface of a veil is to add a process oil. For example, Patent Document 1 discloses a method for preventing polymer particles from peeling off from the surface of a veil by adding a process oil to a solution of a conjugated diene polymer to form an oil-extended conjugated diene polymer.

[0008] Furthermore, as a method for improving the processability of such modified conjugated diene polymers during kneading, for example, Patent Documents 2 and 3 propose diene rubbers obtained by subjecting active terminals of the polymer to a coupling reaction with a polyfunctional silane compound.

[0009] Japanese Patent Application Publication No. 2019-131810 International Publication No. 07 / 114203 Pamphlet Japanese Patent Application No. 2018-534375

[0010] Conventionally, modified conjugated diene polymers have generally been oil-extended conjugated diene polymers to which process oil has been added in order to improve bale moldability and processability after kneading. On the other hand, in recent years, it has been desired to reduce the amount of process oil added to conjugated diene polymers as much as possible in order to improve the degree of freedom in compounding when preparing rubber compositions.

[0011] However, in the case of the conjugated diene polymer veil disclosed in Patent Document 1, there is a problem in that sufficient moldability may not be obtained when the amount of process oil added is reduced. For example, when the molecular weight of the modified conjugated diene polymer is increased to improve abrasion resistance, or when the glass transition temperature of the modified conjugated diene polymer is set low to improve low hysteresis loss, if the amount of process oil added is small or the process oil is not included in the formulation, the polymer particles tend to peel off from the surface of the veil. Furthermore, such modified conjugated diene polymers have the problem that the viscosity of the composition increases during kneading, resulting in poor processability.

[0012] Therefore, an object of the present invention is to provide a modified conjugated diene polymer which, even in the case of an un-oil-extended product to which no process oil is added, has excellent bale moldability, processability during kneading, and excellent abrasion resistance and breaking strength when vulcanized.

[0013] As a result of intensive research and investigation to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by a modified conjugated diene-based polymer which has a specific shape in the molecular weight distribution curve measured by gel permeation chromatography (GPC), has a predetermined molecular weight distribution and modification rate, and has two or more peaks in a differential scanning calorimetry (DSC) derivative curve obtained by differentiating the DSC curve recorded by DSC measurement, and have thereby completed the present invention.

[0014] [1] A modified conjugated diene polymer that satisfies the following <Condition (i)> to <Condition (iii)>. <Condition (i)> The molecular weight distribution curve measured by gel permeation chromatography (GPC) has a single peak, and the molecular weight distribution (PDI; MWD) is 1.7 to 3.5. <Condition (ii)> The modification rate is 40% by mass or more. <Condition (iii)> The DSC derivative curve, obtained by differentiating a DSC curve recorded by differential scanning calorimetry (DSC) measurement, has two or more peaks. [2] The modified conjugated diene polymer according to [1], wherein the molecular weight distribution curve measured by gel permeation chromatography (GPC) has a shoulder on the polymer side of the peak top. [3] A weight average molecular weight (Mw) of 40×10 measured by gel permeation chromatography (GPC) ４ Above 250 x 10 ４ [4] The modified conjugated diene polymer according to any one of [1] to [3], wherein the content of repeating units derived from aromatic vinyl monomers is 0% by weight or more and 30% by weight or less. [5] The modified conjugated diene polymer according to any one of [1] to [4], wherein the content of repeating units derived from aromatic vinyl monomers is 0% by weight or more and 30% by weight or less. [6] The modified conjugated diene polymer according to any one of [1] to [5], wherein the Mooney viscosity measured at 100°C is 80 to 170 and the Mooney relaxation ratio (MSR) measured at 100°C is 0.30 to 0.80. [7] The modified conjugated diene polymer according to any one of [1] to [5], wherein the difference (ΔTg) between the peak top positions of the highest and second highest peaks in a differential scanning calorimetry (DSC) differential curve obtained by differentiating a DSC curve recorded by DSC measurement is 15°C or more. [7] The modified conjugated diene-based polymer according to [6], wherein the ΔTg is 15° C. or more and 75° C. or less. [8] The weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) is 70×10 ４Above 200 x 10 ４ a modified conjugated diene polymer (A) having a molecular weight of 10×10 or less as measured by gel permeation chromatography (GPC); ４ Above 70 x 10 ４ [9] The modified conjugated diene polymer according to any one of [1] to [7], further comprising a modified conjugated diene polymer (B) having a weight average molecular weight difference (ΔMw) of less than 20 × 10 ４

[10] The modified conjugated diene polymer according to [8] or [9], wherein the mass ratio ((A) / (B)) of the modified conjugated diene polymer (A) to the modified conjugated diene polymer (B) in the modified conjugated diene polymer is 40 / 60 to 10 / 90.

[11] The modified conjugated diene polymer (A) and / or (B) comprises a conjugated diene polymer having a fork portion [A] in which a plurality of conjugated diene polymer chains are bonded to one end of a main chain branched structure portion and a single chain of another conjugated diene polymer is bonded to the other end of the main chain branched structure portion.

[12] The modified conjugated diene polymer (A) and / or (B) includes a conjugated diene polymer having a fork portion [A] in which a plurality of conjugated diene polymer chains are bonded to one end of a main-chain branched structure portion and a single chain of another conjugated diene polymer is bonded to the other end of the main-chain branched structure portion, and a three- or more branched star polymer structure portion [B] in which one or more fork portion [A] is bonded.

[13] A molded product comprising 100 parts by mass of the modified conjugated diene polymer according to any of [1] to

[12] , and less than 1 part by mass of a softener component.

[14] A method for producing the modified conjugated diene polymer according to any one of [8] to

[12] , comprising: obtaining the modified conjugated diene polymer (A) and the modified conjugated diene polymer (B) by continuous polymerization using one or more reactors, respectively; mixing a polymerization solution containing the modified conjugated diene polymer (A) with a polymerization solution containing the modified conjugated diene polymer (B); and then removing the solvent to obtain the modified conjugated diene polymer.

[15] The method for producing a modified conjugated diene polymer according to

[14] , wherein the modified conjugated diene polymer (A) and / or (B) is produced by a production method comprising: a polymerization step of polymerizing or copolymerizing a conjugated diene compound, or a conjugated diene compound and an aromatic vinyl compound, using an alkali metal compound or an alkaline earth metal compound as a polymerization initiator to obtain a conjugated diene polymer having an active end; a polymerization branching step of reacting a branching agent with the active end of the conjugated diene polymer to introduce a branched structure; and a modification step of reacting a polymerization-terminated end with a coupling modifier.

[16] The method for producing a modified conjugated diene polymer according to

[15] , wherein the branching agent is a compound represented by the following formula (1) or (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. ２ ~R ３ are each independently 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 ３ are each independent. 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 ４ ~R ７ are each independently 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. ４ ~R ７ are each independent. ２ ~X ３represents 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 3, b represents an integer of 0 to 2, and c represents an integer of 0 to 3. (a + b + c) represents an integer of 3.)

[17] A rubber composition comprising: 100 parts by mass of a rubber component; and 5.0 parts by mass or more and 150 parts by mass or less of a filler, wherein the rubber component contains 10 parts by mass or more of the modified conjugated diene-based polymer according to any one of [1] to

[12] per 100 parts by mass of the total amount of the rubber component.

[18] A tire comprising the rubber composition according to

[17] .

[0015] According to the present invention, it is possible to provide a modified conjugated diene polymer that is excellent in bale formability, processability during kneading, and fuel-saving performance, abrasion resistance, and breaking strength when vulcanized, even in the case of an unextended product to which no process oil is added.

[0016] Hereinafter, an embodiment for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that the present embodiment is an example for explaining the present invention, and the present invention is not limited to the following embodiment. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0017] [Modified Conjugated Diene Polymer] The modified conjugated diene polymer of this embodiment is a modified conjugated diene polymer that satisfies the following <Condition (i)> to <Condition (iii)>. <Condition (i)> The molecular weight distribution curve measured by gel permeation chromatography (GPC) has a single peak, and the molecular weight distribution (PDI; MWD) is 1.7 to 3.5. <Condition (ii)> The modification rate is 40% by mass or more. <Condition (iii)> The DSC differential curve obtained by differentiating the DSC curve recorded by differential scanning calorimetry (DSC) measurement has two or more peaks.

[0018] The modified conjugated diene polymer of the present embodiment has excellent processability during kneading, and when vulcanized, has excellent fuel-saving performance, abrasion resistance, and breaking strength, and is also excellent in bale formability even when it is an un-oil-extended product to which no process oil is added.

[0019] The modified conjugated diene polymer of the present embodiment may be any of a homopolymer of a single conjugated diene compound, a polymer (i.e., a copolymer) of different types of conjugated diene compounds, and a copolymer of a conjugated diene compound and a vinyl aromatic compound.

[0020] 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 effectively and reliably achieving the effects of the present embodiment. These conjugated diene compounds may be used alone or in combination of two or more.

[0021] Furthermore, examples of vinyl aromatic compounds include, but are not limited to, styrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred from the viewpoint of effectively and reliably achieving the effects of this embodiment. These vinyl aromatic compounds may be used alone or in combination of two or more.

[0022] The modified conjugated diene polymer may be a random copolymer or a block copolymer. Examples of random copolymers include, but are not limited to, random copolymers composed of two or more conjugated diene compounds, such as butadiene-isoprene random copolymers, butadiene-styrene random copolymers, isoprene-styrene random copolymers, and butadiene-isoprene-styrene random copolymers composed of conjugated dienes and vinyl-substituted aromatic compounds. The compositional distribution of each monomer in the copolymer chain is not particularly limited, and examples include completely random copolymers with a statistically random composition and tapered (gradient) random copolymers with a tapered composition. The bonding mode of the conjugated diene, i.e., the composition of 1,4-bonds, 1,2-bonds, etc., may be uniform or may have a distribution.

[0023] (Molecular Weight Distribution Curve of Modified Conjugated Diene Polymer) The modified conjugated diene polymer of this embodiment preferably has a molecular weight distribution curve obtained by gel permeation chromatography (GPC) analysis that is unimodal and has a shoulder on the polymer side of the peak top. Here, "the molecular weight distribution curve is unimodal and has a shoulder on the polymer side of the peak top" means that the molecular weight distribution curve has one peak top and three or more inflection points between the peak start point and the peak end point, and that there are two or more inflection points in the region from the peak top to the peak end point, i.e., the region from the peak top to the high molecular weight side. When such a molecular weight distribution curve is shown, the bale moldability of the modified conjugated diene polymer is improved for the following reasons, but is not limited to the reasons described below.

[0024] Generally, the higher the molecular weight of a polymer, the better the abrasion resistance and breaking strength of the polymer. However, at the same time, polymer particles tend to peel off easily from the surface of the bale, which tends to deteriorate the bale moldability. In addition, the viscosity during vulcanization tends to increase significantly, which tends to significantly deteriorate the processability during vulcanization. Therefore, in the case of a polymer with a high molecular weight, even if a large number of functional groups are introduced into the polymer in order to improve the affinity and / or reactivity with silica blended as a filler, it is not possible to sufficiently disperse silica in the polymer during the kneading process.

[0025] On the other hand, the modified conjugated diene polymer of this embodiment preferably has a single-peaked molecular weight distribution curve with a shoulder on the polymer side of the peak top. By containing a high-molecular-weight component (referred to as "conjugated diene polymer A") while using a component (referred to as "conjugated diene polymer B") with a lower molecular weight than that component as the main component, bale formability is improved, and processability is improved by suppressing the increase in viscosity during vulcanization. Furthermore, by containing the conjugated diene polymer A, the vulcanized product has excellent abrasion resistance and breaking strength. Such a modified conjugated diene polymer having a single-peaked molecular weight distribution curve with a shoulder on the polymer side of the peak top can be obtained by forming it from polymers of different molecular weights, with the aim of achieving an appropriate balance between molecular weight and viscosity. Specifically, it can be obtained by adjusting the molecular weights, branching degrees, and ratios of the conjugated diene polymer A and the conjugated diene polymer B, as described below. This makes it possible to improve the abrasion resistance, fuel economy and breaking properties of the vulcanizate without impairing the bale moldability of the conjugated diene polymer and the processability of the rubber composition.

[0026] (Average Molecular Weight and Molecular Weight Distribution of Modified Conjugated Diene Polymer) The modified conjugated diene polymer of the present embodiment preferably has a weight average molecular weight of 40×10 or less as measured by GPC. ４ More preferably, 50×10 ４ or more, and more preferably 55×10 ４ or more, and even more preferably 60×10 ４ or more, and even more preferably 65×10 ４or more, and most preferably 70×10 ４ The weight average molecular weight measured by GPC measurement method is 40×10 ４ When the weight average molecular weight is 250×10 or more, the vulcanizate has further excellent low hysteresis loss. ４ or less, and more preferably 200×10 ４ or less, and more preferably 150×10 ４ or less, and even more preferably 125×10 ４ or less, and even more preferably 100×10 ４ or less, and most preferably 95×10 ４ The weight average molecular weight is 250×10 or less. ４ When the weight average molecular weight is less than 1000 ppm, the dispersibility of the filler in the vulcanized product tends to be even better, and practically sufficient fracture properties tend to be obtained. The weight average molecular weight may be within a range that combines the above upper and lower limits. The weight average molecular weight of the modified conjugated diene polymer can be measured by the method described in the examples below.

[0027] The modified conjugated diene polymer of the present embodiment preferably has a number average molecular weight of 20×10 as measured by GPC. ４ More preferably, 25×10 ４ More preferably, 30×10 ４ The number average molecular weight is 35×10 ４ The number average molecular weight measured by GPC measurement method may be 20×10 or more. ４ When the number average molecular weight is 100×10 or more, the processability during vulcanization is more excellent, and the vulcanizate tends to have more excellent low hysteresis loss. ４ or less, more preferably 90×10 ４ or less, and more preferably 80×10 ４ or less, and even more preferably 70×10 ４ or less, and even more preferably 60×10 ４ or less, and most preferably 50×10 ４ The number average molecular weight is 100×10 or less. ４When the number average molecular weight is less than 100%, the dispersibility of the filler in the vulcanized product tends to be even better, and practically sufficient fracture properties tend to be obtained. The number average molecular weight may be within a range that combines the above upper and lower limits. The number average molecular weight of the modified conjugated diene polymer can be measured by the method described in the examples below.

[0028] In the modified conjugated diene polymer of this embodiment, the ratio (Mw / Mn) (molecular weight distribution) of the weight average molecular weight (Mw) measured by GPC to the number average molecular weight (Mn) measured by GPC is 1.7 or more, preferably 1.75 or more, more preferably 1.8 or more, even more preferably 1.85 or more, and most preferably 1.9 or more, from the viewpoints of processability during vulcanization and the abrasion resistance and breaking strength of the vulcanizate. The upper limit of the molecular weight distribution is 3.5 or less, preferably 3.0 or less, more preferably 2.8 or less, and even more preferably 2.5 or less. The molecular weight distribution of the modified conjugated diene polymer can be controlled within the above numerical range by adjusting the molecular weights and branching degrees of the conjugated diene polymers A and B, as well as the ratio thereof, as described below.

[0029] (Modifying Group) The modified conjugated diene polymer of this embodiment preferably has a modifying group. The term "modifying group" refers to a functional group having affinity or binding reactivity with a filler, and examples thereof include functional groups containing a nitrogen atom. The modified conjugated diene polymer of this embodiment has such a modifying group, which further improves the interaction with the filler. Therefore, when a composition of the modified conjugated diene polymer containing the modified conjugated diene polymer and a filler is prepared, the breaking strength of the composition is further improved. From the same viewpoint, the modified conjugated diene polymer of this embodiment preferably has a modifying group containing a nitrogen atom, and more preferably has a modifying group containing a nitrogen atom and a silicon atom. It is not necessary for one modifying group or coupling modifier to contain both a nitrogen atom and a silicon atom; a modifying group containing only one atom or a coupling modifier having a modifying group may be combined so that the polymer contains both nitrogen and silicon.

[0030] (Modification Ratio) In this specification, the term "modification ratio" refers to the content, expressed in mass %, of a modified conjugated diene polymer component having a specific functional group in the polymer molecule that has affinity or binding reactivity with a filler relative to the total amount of the conjugated diene polymer mixture when a mixture of a modified conjugated diene polymer and an unmodified conjugated diene polymer is obtained by modifying a conjugated diene polymer with a coupling modifier. Therefore, when the specific functional group contains a nitrogen atom, the term refers to the mass ratio of the nitrogen-containing conjugated diene polymer relative to the total amount of the conjugated diene polymer mixture. In this specification, unless otherwise specified or clearly distinguished, such as when used in conjunction with "conjugated diene polymer or modified conjugated diene polymer," the term "conjugated diene polymer" encompasses both unmodified conjugated diene polymers and modified conjugated diene polymers. Note that when used in conjunction with "conjugated diene polymer or modified conjugated diene polymer," the term "conjugated diene polymer" refers to an unmodified conjugated diene polymer.

[0031] For example, in a conjugated diene polymer including a modified conjugated diene polymer obtained by reacting a nitrogen atom-containing modifying agent at a terminal end, the modification rate is the mass ratio of the modified conjugated diene polymer having a nitrogen atom-containing functional group resulting from the nitrogen atom-containing modifying agent to the total amount of the conjugated diene polymer.

[0032] The conjugated diene polymer of this embodiment is preferably modified with at least a portion containing a nitrogen atom, more preferably with a functional group containing a nitrogen atom and a silicon atom. Such a modified conjugated diene polymer has better processability when blended with a filler or the like to form a rubber composition, and tends to have better abrasion resistance, breaking strength, and low hysteresis loss when the rubber composition is vulcanized. Note that, as described above, it is not necessary for one modifying group or coupling modifier to contain both a nitrogen atom and a silicon atom; modifying groups or coupling modifiers containing only one may be combined so that the final modified conjugated diene polymer contains both nitrogen and silicon.

[0033] From the viewpoint of improving the low hysteresis loss of the vulcanizate, the modification rate of the conjugated diene polymer of this embodiment is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, still more preferably 65% ​​by mass or more, still more preferably 70% by mass or more, and most preferably 75% by mass or more, based on the total amount of the conjugated diene polymer. The upper limit of the modification rate is not particularly limited, but may be 100% by mass, 98% by mass or less, 95% by mass or less, or 90% by mass or less. Furthermore, when modified conjugated diene polymers with the same glass transition temperature are compared, those with a higher modification rate tend to have better low hysteresis loss.

[0034] In the conjugated diene polymer of this embodiment, the modification rate can be measured by chromatography, which can separate functional group-containing modified components from unmodified components. Examples of methods using chromatography include a method (column adsorption GPC method) in which a gel permeation chromatography column filled with a polar substance such as silica that adsorbs specific functional groups is used to quantify the unadsorbed components using an internal standard for comparison.

[0035] More specifically, the modification rate can be obtained by calculating the amount of adsorption onto the silica-based column from the difference between a chromatogram obtained by measuring a sample solution containing the sample and a low-molecular-weight internal standard polystyrene on a polystyrene-based gel column and a chromatogram obtained by measuring the same sample solution on a silica-based column. Specifically, the modification rate can be measured by the method described in the Examples below.

[0036] In the conjugated diene polymer of this embodiment, the modification rate can be controlled within the above-mentioned numerical range by adjusting the ratio of the conjugated diene polymers A and B, the amount of coupling modifier added, and the method for reacting the conjugated diene compound with the modifier in the polymerization of the conjugated diene polymers A and B. For example, the conjugated diene polymers A and B may be obtained by combining a polymerization method using an organolithium compound having at least one nitrogen atom in the molecule as a polymerization initiator, as described below, a copolymerization method of a monomer having at least one nitrogen atom in the molecule, and a method using a modifier having the structural formula described below, and then adjusting the ratio thereof.

[0037] (DSC Differential Curve Obtained by Differential Scanning Calorimetry (DSC) Measurement of Modified Conjugated Diene Polymer) The modified conjugated diene polymer of this embodiment has two or more peak tops (inflection points) in a DSC differential curve obtained by differentiating a DSC curve recorded by performing differential scanning calorimetry (DSC) measurement while increasing the temperature within a predetermined temperature range in accordance with ISO 22768:2017. The peak tops (inflection points) in the DSC differential curve obtained in accordance with ISO 22768:2017 correspond to glass transition temperatures, and having two or more peak tops (inflection points) means that the modified conjugated diene polymer of this embodiment contains two or more components with different Tg's. By containing two or more components with different Tg, the modified conjugated diene polymer can contain a component with a high Tg that ensures processability and a component with a low Tg that ensures abrasion resistance, thereby improving the balance between processability and abrasion resistance. A modified conjugated diene polymer having two or more peak tops in a DSC differential curve can be obtained by forming it from two or more polymers with different Tg. Specifically, as described below, it can be obtained by adjusting the molecular weight, microstructure, degree of branching, and ratio thereof of the conjugated diene polymer A and the conjugated diene polymer B. The difference (ΔTg) between the peak top positions of the two highest peaks (i.e., the peak with the highest peak height and the peak with the second highest peak height) is not particularly limited, but from the viewpoints of improving the bale moldability of the modified conjugated diene polymer and the processability, abrasion resistance, and breaking strength when vulcanized, it is preferably 15°C or higher, more preferably 20°C or higher, even more preferably 25°C or higher, and particularly preferably 28°C or higher. ΔTg may be 30° C. or higher, 40° C. or higher, or 50° C. or higher. ΔTg is preferably 75° C. or lower, more preferably 70° C. or lower, and even more preferably 65° C. or lower. The above-mentioned lower and upper limits of ΔTg may be appropriately combined to define a numerical range.For example, ΔTg may be 15°C or higher and 75°C or lower, 20°C or higher and 75°C or lower, 25°C or higher and 70°C or lower, 28°C or higher and 70°C or lower, 30°C or higher and 65°C or lower, 40°C or higher and 65°C or lower, or 50°C or higher and 65°C or lower. When ΔTg is within the above range, the modified conjugated diene polymer tends to have a better balance of fuel economy, wet grip properties, and abrasion resistance when vulcanized. Specifically, two or more peak tops in a DSC differential curve can be measured by the method described in the examples below.

[0038] (Microstructure of Modified Conjugated Diene Polymer) The microstructure of the modified conjugated diene polymer (the amount of bound vinyl aromatic monomer units, the amount of bound conjugated diene monomer units, and the proportion of vinyl bonds in the bound conjugated diene monomer units) affects the glass transition temperature of the conjugated diene polymer, and therefore the amount of bound vinyl aromatic monomer units and the amount of vinyl bonds have preferred ranges from the viewpoint of controlling the glass transition temperature. In the microstructure of the conjugated diene polymer, the amount of bound vinyl aromatic monomer units is not particularly limited, but is preferably 0% by mass or more and 30% by mass or less, more preferably 1% by mass or more and 28% by mass or less, even more preferably 1% by mass or more and 26% by mass or less, still more preferably 2% by mass or more and 24% by mass or less, still more preferably 3% by mass or more and 22% by mass or less, and particularly preferably 5% by mass or more and 20% by mass or less, relative to the entire conjugated diene polymer. When the amount of bound vinyl aromatic monomer units is within the above range, the vulcanizate of the conjugated diene polymer tends to have even better breaking strength, abrasion resistance, and low hysteresis loss. Furthermore, as the amount of bound vinyl aromatic monomer units increases, the Tg of the conjugated diene polymer tends to increase, while as the amount of bound vinyl aromatic monomer units decreases, the Tg tends to decrease. Furthermore, as the amount of bound vinyl aromatic monomer units increases, the bale moldability tends to improve, while as the amount of bound vinyl aromatic monomer units decreases, the bale moldability tends to deteriorate. In this specification, the "amount of bound vinyl aromatic monomer units" refers to the content of the portion derived from the aromatic vinyl compound used as a monomer.

[0039] In the microstructure of the modified conjugated diene polymer, the amount of bound conjugated diene monomer units is not particularly limited, but is preferably 70% by mass or more and 100% by mass or less, more preferably 72% by mass or more and 99% by mass or less, even more preferably 74% by mass or more and 99% by mass or less, still more preferably 76% by mass or more and 98% by mass or less, still more preferably 78% by mass or more and 97% by mass or less, and particularly preferably 80% by mass or more and 95% by mass or less, based on the total amount of the conjugated diene polymer. When the amount of bound conjugated diene monomer units is within the above range, the vulcanizate of the conjugated diene polymer tends to have even better breaking strength, abrasion resistance, and low hysteresis loss. In this specification, the "amount of bound conjugated diene monomer units" refers to the content of the portion derived from the conjugated diene compound used as a monomer.

[0040] In the microstructure of the modified conjugated diene polymer, the amount of vinyl bonds in the bound conjugated diene monomer units (hereinafter simply referred to as "vinyl bond amount") is not particularly limited, but is preferably 11 mol% to 60 mol% of the total bound conjugated diene monomer units, more preferably 11 mol% to 40 mol%, even more preferably 12 mol% to 35 mol%, even more preferably 13 mol% to 30 mol%, still more preferably 14 mol% to 29 mol%, and particularly preferably 15 mol% to 28 mol%. When the vinyl bond amount is within the above range, the conjugated diene polymer tends to have better fracture strength and abrasion resistance due to increased linearity of the conjugated diene moiety structure and stronger entanglement of polymer chains. Furthermore, when the vinyl bond amount is within the above range, the vulcanizate thereof tends to have even lower hysteresis loss. In this specification, the term "vinyl bond content in a linked conjugated diene monomer unit" refers to the proportion of a portion having a vinyl bond among portions derived from a conjugated diene compound used as a monomer (hereinafter referred to as "linked conjugated diene monomer units").

[0041] (Branching Degree (Bn)) In this specification, the branching degree (Bn) is calculated using a contraction factor (g') from the formula g' = 6Bn / {(Bn+1)(Bn+2)}, where the contraction factor (g') has the following value:

[0042] In general, branched polymers tend to have smaller molecular sizes compared to linear polymers having the same absolute molecular weight. Here, "molecular size" refers to the volume substantially occupied by the molecule. The contraction factor (g') represents the relative molecular size of a target polymer and is an index of the ratio of the molecular size of the target polymer to the molecular size of a linear polymer having the same absolute molecular weight as the target polymer. In other words, when the degree of branching of a polymer is high, its size becomes relatively small, and therefore the contraction factor (g') tends to be small.

[0043] Here, since it is known that there is a correlation between the molecular size of a polymer and the ratio of intrinsic viscosity, in this embodiment, the shrinkage factor (g') is defined as the ratio of intrinsic viscosities. That is, the shrinkage factor (g') is the ratio of the intrinsic viscosity [η ０ ] to the intrinsic viscosity [η] of the target polymer ([η] / [η ０ ]).

[0044] The intrinsic viscosity of the linear polymer [η ０ ]is[η ０ ]=10 －３．４９８ M ０．７１１ It is known that the relationship follows the formula: where M is the absolute molecular weight. Therefore, the shrinkage factor (g') and the degree of branching (Bn) can be determined by measuring the absolute molecular weight and intrinsic viscosity of the target polymer using a GPC-light scattering method with a viscosity detector. The calculated degree of branching (Bn) accurately represents the number of polymer chains that are directly or indirectly bonded to each other with respect to the longest polymer main chain.

[0045] Here, "absolute molecular weight" refers to a molecular weight measured by a light scattering method. As mentioned above, generally, branched polymers tend to have smaller molecular sizes compared to linear polymers having the same absolute molecular weight. Therefore, the molecular weight of a branched polymer tends to be underestimated in GPC measurement, which is a method of determining the molecular weight by screening the polymer according to molecular size and comparing it relative to a standard polystyrene sample. On the other hand, light scattering measures the molecular weight by directly observing the molecules. Therefore, light scattering can accurately measure the molecular weight without being affected by the influence of the polymer structure or the interaction with the column packing material. The absolute molecular weight can be measured by the method described in the examples below.

[0046] Furthermore, the term "intrinsic viscosity" ideally means the viscosity [η] calculated by the following formula (I): １ indicates the viscosity when the target polymer is dissolved in a solvent at a concentration c, and η ２ In this specification, the intrinsic viscosity is a value measured by the method described in the Examples section below.

[0047]

[0048] The above shrinkage factor represents the rate of decrease in molecular size, but does not accurately represent the branched structure of the polymer.

[0049] Therefore, the degree of branching (Bn) of the modified conjugated diene polymer is calculated using the value of the shrinkage factor (g') at each absolute molecular weight of the modified conjugated diene polymer. The calculated "degree of branching (Bn)" accurately represents the number of polymers that are directly or indirectly bonded to each other with respect to the longest main chain structure.

[0050] The calculated degree of branching (Bn) is an index that represents the branched structure of the modified conjugated diene polymer. For example, in the case of a typical four-branched star polymer (four polymer chains connected to the center), two arms of the polymer chain are bonded to the longest highly branched main chain structure, and the degree of branching (Bn) is evaluated as 2.

[0051] In the case of a typical eight-branched star polymer, six polymer chain arms are attached to the longest highly branched main chain structure, and the degree of branching (Bn) is evaluated as six.

[0052] The modified conjugated diene polymer of the present embodiment has a degree of branching (Bn) of 2 or more, which means that the modified conjugated diene polymer has a star polymer structure with branches similar to a four-branched star polymer structure.

[0053] Here, "branch" refers to a structure formed by direct or indirect bonding of one polymer to another polymer. Furthermore, "degree of branching (Bn)" refers to the number of polymers that are directly or indirectly bonded to the longest main chain structure. In other words, it takes into consideration not only the side chains bonded to the longest polymer chain, but also the number of branches of the side chains, if the side chains are further branched. Therefore, if one polymer chain is bonded to the longest polymer chain as a side chain, and another polymer chain is further bonded to that side chain, the degree of branching is 2.

[0054] By having a branching degree (Bn) of 4 or more, the modified conjugated diene polymer of the present embodiment has extremely excellent processability when vulcanized, and when vulcanized, has excellent abrasion resistance and breaking strength.

[0055] Generally, an increase in absolute molecular weight tends to worsen processability. When the absolute molecular weight is increased in a linear polymer structure, the viscosity increases significantly when the polymer is vulcanized, significantly worsening processability.

[0056] Therefore, even if a large number of functional groups are introduced into the polymer to improve the affinity and / or reactivity with silica blended as a filler, the silica cannot be sufficiently dispersed in the polymer during the kneading process, and as a result, the functions of the introduced functional groups are not exerted, and the effects of improving the low hysteresis loss and wet skid resistance that should be expected from the introduction of functional groups are not exerted.

[0057] On the other hand, by specifying the branching degree (Bn) of the modified conjugated diene polymer of this embodiment to be 4 or more, the increase in viscosity during vulcanization associated with an increase in absolute molecular weight is significantly suppressed. Therefore, for example, the modified conjugated diene polymer is thoroughly mixed with silica or the like during the kneading process, making it possible to disperse silica around the modified conjugated diene polymer. As a result, for example, by setting the molecular weight of the modified conjugated diene polymer to be large, it is possible to improve abrasion resistance and fracture strength, and by thoroughly kneading the silica is dispersed around the polymer, allowing the functional groups to act and / or react. This makes it possible to obtain a modified conjugated diene polymer with low hysteresis loss and wet skid resistance that are sufficient for practical use.

[0058] The absolute molecular weight of the modified conjugated diene polymer can be measured by the method described in the examples below.

[0059] The degree of branching (Bn) of the modified conjugated diene polymer of the present embodiment is not particularly limited, but is preferably at least 4, more preferably at least 5, and even more preferably at least 6. A modified conjugated diene polymer having a degree of branching (Bn) within this range tends to have excellent bale moldability and excellent processability when made into a vulcanizate.

[0060] The upper limit of the degree of branching (Bn) is not particularly limited and may be equal to or greater than the detection limit, but is preferably equal to or less than 84, more preferably equal to or less than 80, even more preferably equal to or less than 60, particularly preferably equal to or less than 40, and even more preferably equal to or less than 20. When the modified conjugated diene polymer of the present embodiment has a degree of branching (Bn) of 84 or less, it tends to have excellent abrasion resistance when vulcanized.

[0061] The degree of branching of the modified conjugated diene polymer can be controlled to 4 or more by adjusting the combination of the amount of branching agent and the amount of terminal coupling agent added in each of the conjugated diene polymers A and B, and by adjusting the ratio of A to B. Specifically, the degree of branching can be controlled by the number of functional groups of the branching agent, the amount of branching agent added, the timing of adding the branching agent, the functionality of the coupling agent or nitrogen atom-containing modifier, and the amount of coupling agent or nitrogen atom-containing modifier added. More specifically, this will be described later in relation to the method for producing a modified conjugated diene polymer.

[0062] Generally, the abrasion resistance and breaking strength of a polymer tend to improve as the absolute molecular weight of the polymer increases. However, when the absolute molecular weight of a polymer with a low degree of branching is increased, polymer particles tend to peel off easily from the surface of the bale, resulting in poor bale moldability. In addition, the viscosity during vulcanization tends to increase significantly, significantly worsening the processability during vulcanization. Therefore, even if a large number of functional groups are introduced into a polymer with a low degree of branching in order to improve the affinity and / or reactivity with silica blended as a filler, the silica cannot be sufficiently dispersed in the polymer during the kneading process. As a result, the processability constraints lead to limited freedom in molecular weight design.

[0063] (Mooney Viscosity of Modified Conjugated Diene Polymer) Mooney viscosity is an index showing the overall characteristics of a conjugated diene polymer, including information on the molecular weight, molecular weight distribution, degree of branching, and softener content of the conjugated diene polymer. Furthermore, the method for measuring Mooney viscosity is specified in ISO 289, and since the measurement error due to instrumental differences is small, it is extremely effective in controlling the performance of the conjugated diene polymer. The Mooney viscosity (hereinafter also simply referred to as "Mooney viscosity" or "ML") of the conjugated diene polymer of this embodiment measured at 100°C is preferably 80 or more, and from the viewpoints of handling stability, breaking strength, and abrasion resistance when a rubber composition for crosslinking containing the conjugated diene polymer of this embodiment is used in a tire, it is more preferably 90 or more, and even more preferably 100 or more. On the other hand, the upper limit is preferably 170 or less, and from the viewpoints of moldability and productivity of molded articles of various shapes such as sheet-like or block-like shapes, and rubber compositions containing the conjugated diene-based polymer of this embodiment, and processability of rubber compositions blended with fillers and the like, it is more preferably 160 or less, even more preferably 150 or less, even more preferably 145 or less, and most preferably 140 or less.

[0064] The Mooney viscosity of the conjugated diene polymer was measured by using a sample of the conjugated diene polymer formed into a plate shape by a pressure press, setting it in the measuring device, preheating the sample at 100°C for 1 minute, rotating the rotor at 2 rpm, and measuring the torque after 4 minutes, and the measured value was taken as the Mooney viscosity (ML （１＋４） ) More specifically, it can be measured by the method described in the Examples below. The Mooney viscosity of the conjugated diene polymer of this embodiment can be controlled within the above-mentioned range by adjusting the type, use timing, and amount of the branching agent and coupling modifier, the molecular weight, molecular weight distribution, and branching degree of the conjugated diene polymer, and adjusting the ratio of the conjugated diene polymers A and B, respectively.

[0065] (Mooney Relaxation Rate of Conjugated Diene Polymer) The Mooney relaxation rate (hereinafter also simply referred to as "Mooney Relaxation Rate" or "MSR") of the conjugated diene polymer of this embodiment measured at 100°C is preferably 0.8 or less. From the viewpoint of processability of a rubber composition obtained by blending a filler or the like with the conjugated diene polymer, it is more preferably 0.75 or less, even more preferably 0.70 or less, even more preferably 0.65 or less, and most preferably 0.60 or less. On the other hand, the Mooney relaxation rate is preferably 0.25 or more. From the viewpoint of handling stability and breaking strength when the conjugated diene polymer of this embodiment is used as a tire material, it is more preferably 0.30 or more, even more preferably 0.32 or more, even more preferably 0.34 or more, and particularly preferably 0.36 or more. Like the Mooney viscosity, the Mooney relaxation rate is affected by the molecular weight, molecular weight distribution, degree of branching, and softener content of the conjugated diene polymer, and is an index showing the overall characteristics of the conjugated diene polymer.

[0066] The MSR can be measured using a Mooney viscometer as follows: First, a sample is preheated at 100°C for 1 minute, and then the rotor is rotated at 2 rpm. The Mooney viscosity (ML （１＋４） ) is measured, the rotation of the rotor is immediately stopped, and the torque is recorded in Mooney units every 0.1 seconds for 1.6 seconds to 5 seconds after stopping. The slope of the straight line obtained by plotting the torque against the time (seconds) logarithmically is determined, and the absolute value thereof is the Mooney relaxation rate (MSR). More specifically, it can be measured by the method described in the Examples below. The Mooney relaxation rate of the conjugated diene polymer of this embodiment can be controlled to be within the above-mentioned numerical range by adjusting the type, timing of use, and amount of the branching agent and coupling modifier, the molecular weight, molecular weight distribution, and degree of branching of the conjugated diene polymer, for each of the conjugated diene polymers A and B, and adjusting the ratio of the conjugated diene polymers A and B.

[0067] [Conjugated Diene Polymer A and Conjugated Diene Polymer B] The conjugated diene polymer A and the conjugated diene polymer B may be a homopolymer of a single conjugated diene compound, a polymer (i.e., a copolymer) of different types of conjugated diene compounds, or a copolymer of a conjugated diene compound and a vinyl aromatic compound.

[0068] 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 effectively and reliably achieving the effects of the present embodiment. These conjugated diene compounds may be used alone or in combination of two or more.

[0069] Furthermore, examples of vinyl aromatic compounds include, but are not limited to, styrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred from the viewpoint of effectively and reliably achieving the effects of this embodiment. These vinyl aromatic compounds may be used alone or in combination of two or more.

[0070] The conjugated diene polymer may be a random copolymer or a block copolymer. Examples of random copolymers include, but are not limited to, random copolymers composed of two or more conjugated diene compounds, such as butadiene-isoprene random copolymers, butadiene-styrene random copolymers, isoprene-styrene random copolymers, and butadiene-isoprene-styrene random copolymers composed of conjugated dienes and vinyl-substituted aromatic compounds. The compositional distribution of each monomer in the copolymer chain is not particularly limited, and examples include completely random copolymers with a statistically random composition and tapered (gradient) random copolymers with a tapered composition. The bonding mode of the conjugated diene, i.e., the composition of 1,4-bonds, 1,2-bonds, etc., may be uniform or may have a distribution.

[0071] (Weight-average molecular weight of conjugated diene polymer A and conjugated diene polymer B) The conjugated diene polymer (A) has a weight-average molecular weight (Mw) of 70×10 measured by GPC (gel permeation chromatography). ４ Above 250 x 10 ４ The modified conjugated diene polymer (B) has a Mw measured by GPC of 10 × 10 or less. ４ Above 70 x 10 ４ From the viewpoint of improving the bale moldability of the modified conjugated diene polymer, and the processability, abrasion resistance, and breaking strength when vulcanized, the weight average molecular weight (Mw) of the conjugated diene polymer (A) is preferably less than 70×10 ４ Above 200 x 10 ４ or less, and more preferably 70×10 ４ Above 150 x 10 ４ or less, and more preferably 75×10 ４ 140 x 10 ４ The weight average molecular weight (Mw) of the conjugated diene polymer (B) is preferably 30×10 or less. ４ Above 70 x 10 ４ and more preferably less than 40×10 ４ Above 70 x 10 ４ and more preferably less than 50×10 ４Above 70 x 10 ４ is less than.

[0072] The difference (ΔMw) in weight average molecular weight between the conjugated diene polymer (A) and the conjugated diene polymer (B) is not particularly limited. However, from the viewpoint of improving the bale moldability of the modified conjugated diene polymer, and the processability, abrasion resistance, and breaking strength when vulcanized, it is preferred that the difference (ΔMw) be 20×10 ４ It is preferable that the ratio is 25×10 or more, and more preferably 25×10 ４ More preferably, 30×10 ４ or more, and even more preferably 35×10 ４ or more, and most preferably 40×10 ４ That's all.

[0073] (Glass Transition Temperature of Conjugated Diene Polymer A and Conjugated Diene Polymer B) The difference between the glass transition temperatures of the conjugated diene polymers (A) and (B) is desirably 15°C or more. Either the conjugated diene polymer (A) or (B) may have a higher glass transition temperature. However, from the viewpoints of the bale moldability of the modified conjugated diene polymer, and the processability and abrasion resistance when vulcanized, it is preferable that the glass transition temperature of one of the polymers is -90°C or higher and -55°C or lower, and the glass transition temperature of the other is -55°C or higher and -10°C or lower. The glass transition temperatures of the conjugated diene polymers (A) and (B) can be measured in accordance with ISO 22768:2017. More specifically, a DSC curve is recorded by differential scanning calorimetry (DSC) measurement while increasing the temperature within a predetermined temperature range, and the peak top (inflection point) of the DSC differential curve is taken as the glass transition temperature. Specifically, the glass transition temperature can be measured by the method described in the Examples below.

[0074] (Modification Ratio of Conjugated Diene Polymer A and Conjugated Diene Polymer B) The modification ratio of the conjugated diene polymers (A) and (B) is not particularly limited, but is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, still more preferably 65% ​​by mass or more, still more preferably 70% by mass or more, and most preferably 75% by mass or more. The upper limit of the modification ratio is not particularly limited, but may be 100% by mass, 98% by mass or less, 95% by mass or less, or 90% by mass or less.

[0075] (Structures of Conjugated Diene Polymer A and Conjugated Diene Polymer B) The modified conjugated diene polymer of this embodiment is preferably an assembly of conjugated diene polymers A and B having substantially different molecular weights. Because it is an assembly of polymers having different molecular weights and different numbers of branches, the molecular weight distribution curve measured by gel permeation chromatography (GPC) has a single peak and exhibits a shoulder on the polymer side of the peak top. The conjugated diene polymer A and / or B may have a forked structure in which the polymer chain branches into multiple polymer chains. The branched portion of the forked structure is referred to as a "main chain branched structure" and is preferably an atomic group containing an alkoxysilyl group or halosilyl group heteroatom as described below. Multiple conjugated diene polymer chains are bonded to one end of the main chain branched structure, and a single chain of another conjugated diene polymer is bonded to the other end, thereby forming the forked portion [A]. A specific production method is described below. The "main chain branched structure" is formed by reacting a branching agent having a functional group reactive with the polymerization active ends of multiple polymer chains and a moiety for continuing polymerization, and continuing polymerization while the branching agent bonds to multiple conjugated diene polymer chains. The single chain of the conjugated diene polymer polymerized from the branching agent may be further reacted with a coupling modifier.

[0076] The conjugated diene polymer A and / or B may include a structure in which the single chain side of the forked portion [A] is long (referred to as a long-handled forked structure) by reacting a single chain of the conjugated diene polymer, which has been polymerized from a branching agent after the formation of the "main chain branched structure portion," with a bibranched coupling modifier.

[0077] After the conjugated diene polymer A and / or B has formed the "main chain branched structure portion," the conjugated diene polymer A and / or B may be polymerized from a branching agent, and then the polymerized single chain of the conjugated diene polymer may be bonded to one or more coupling modifiers that form a star-branched structure having three or more branches, thereby forming a star-branched structure (star-shaped polymer structure portion [B]).

[0078] As used herein, the term "main chain branched structure" refers to a structure in which a polymer chain forms branch points, and polymer chains (arms) extend from the branch points. Typically, the branch points, which are formed from a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, are two or more branch points, preferably three or more branch points, and more preferably four or more branch points.

[0079] As used herein, the term "long-handled forked structure" refers to a long-handled forked structure in which the single-stranded side of the forked portion [A] is long. This structure can also be formed by continued polymerization of a single strand, but is preferably formed by reacting the single strand of the forked portion [A] with a biantennary coupling modifier.

[0080] As used herein, the term "star polymer structure" refers to a structure in which three or more polymer chains (arms) are bonded to one central branch point. The number of branches derived from the star polymer structure is preferably three or more, more preferably four or more, even more preferably six or more, and even more preferably eight or more.

[0081] Furthermore, the central branch point referred to here is an assembly (atomic group) having an atom derived from the coupling modifier or a substituent containing a nitrogen atom derived from the modifier, and does not mean a single atom. For example, a typical central branch point is an assembly having an alkoxysilyl group separated by 1 to 5 carbon atoms, preferably 2 to 3 carbon atoms, from an amino group.

[0082] <Main Chain Branched Structure and Branching Agent> A vinyl monomer containing an alkoxysilyl group or a halosilyl group used in constructing the "main chain branched structure" as used herein is referred to as a "branching agent." As the branching agent, it is preferable to use a vinyl monomer containing an alkoxysilyl group or a halosilyl group represented by the following formula (1) or (2). In other words, it is preferable that the "main chain branched structure" is composed of an atomic group derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group represented by the following formula (1) or (2).

[0083]

[0084]

[0085] 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, and may partially have a branched structure. ２ ~R ３ are each independently 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 ３ are each independent. 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.

[0086] In formula (2), R ４ ~R ７ are each independently 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. ４ ~R ７ are each independent. 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 3, b represents an integer of 0 to 2, and c represents an integer of 0 to 3. (a+b+c) represents an integer of 3.

[0087] The conjugated diene polymer of the present embodiment is a polymer having R １ is a hydrogen atom and m = 0. This increases the overall number of branches of the conjugated diene copolymer, thereby achieving the effects of improving abrasion resistance and processability.

[0088] The conjugated diene polymer of the present embodiment is preferably a modified conjugated diene polymer having a monomer unit based on the compound represented by formula (2) in which m = 0 and b = 0. This provides an effect of improving abrasion resistance and processability.

[0089] In addition, the conjugated diene polymer of the present embodiment is a polymer having R １ is a hydrogen atom, m = 0, and l = 0. This improves the overall branching degree of the conjugated diene copolymer, and improves the abrasion resistance and processability.

[0090] The conjugated diene polymer of the present embodiment is preferably a conjugated diene polymer having a monomer unit based on a compound represented by formula (2) in which m = 0, l = 0, a = 0, and b = 0. This provides the effect of improving abrasion resistance and processability.

[0091] Furthermore, the conjugated diene polymer of the present embodiment is more preferably a polymer represented by the formula (1), wherein R １ is a hydrogen atom, l = 0, and n = 3. This improves the modification rate and branching degree, thereby achieving the effects of improving fuel economy performance, abrasion resistance, and processability.

[0092] <Long-Handled Fork-Shaped Conjugated Diene Polymer> A structure in which the single chain of the fork-shaped portion [A] is long is referred to as a long-handled fork-shaped structure. This structure can also be formed by continued polymerization of a single chain. However, when the long-handled fork-shaped conjugated diene polymer is produced simultaneously with a polymer having a three- or more-branched star polymer structure [B] to which one or more fork-shaped portions [A] are bonded, it is appropriate to adopt a method in which the single chain of the fork-shaped portion [A] is reacted with a bi-branched coupling modifier. A long-handled fork-shaped conjugated diene polymer is constructed by constructing a comb-shaped structural portion derived from a main chain branched structure, followed by continued polymerization to increase the molecular weight. After constructing the comb-shaped structural portion derived from a main chain branched structure, polymerization is continued to increase the molecular weight, and the polymer is preferably modified with a coupling modifier with less than two functionalities. More preferably, a bifunctional coupling modifier is used to further increase the molecular weight of the stem portion.

[0093] The long-handled, forked conjugated diene polymer in which the single-chain side of the forked portion [A] is long preferably contains, in the long handle, a structure having a nitrogen atom-containing group represented by any one of the following general formulas (3), (4-1), and (4-2):

[0094]

[0095] In formula (3), P １ , P ２ is a polymer chain, one of which is a forked portion [A] having a main chain branched structure, and the other is a linear polymer chain having no branched structure. ８ is a hydrocarbon or hydrocarbyl group having 1 to 20 carbon atoms, R １０ R is a hydrocarbon group having 1 to 20 carbon atoms, which contains S, O, or N and may be substituted with an organic group that does not have active hydrogen, and may have an unsaturated bond, and may be the same or different. １１ , R １２ are aliphatic hydrocarbon groups having 1 to 6 carbon atoms, which may contain unsaturated bonds, and may be the same or different; R １３is a hydrocarbon group containing Si, O, or N and having 1 to 20 carbon atoms which may be substituted with an organic group having no active hydrogen, and which may have an unsaturated bond.

[0096]

[0097]

[0098] In the formulas (4-1) and (4-2), P １ , P ２ is a polymer chain, one of which is a forked portion [A] having a main chain branched structure, and the other is a linear polymer chain having no branched structure. １４ , R １５ is a hydrocarbon or hydrocarbyl group having 1 to 20 carbon atoms, R １６ are hydrocarbon groups having 1 to 20 carbon atoms, which may have an unsaturated bond, may contain O or N, and may be substituted with an organic group that does not have active hydrogen, and may be the same or different. １７ , R １８ is a hydrocarbon group containing Si, O, or N and having 1 to 20 carbon atoms which may be substituted with an organic group having no active hydrogen, and which may have an unsaturated bond.

[0099] <Conjugated Diene Polymer Having Star Polymer Structure [B]> A conjugated diene polymer having a star polymer structure [B] is a conjugated diene polymer having a three- or more branched star polymer structure constructed by constructing a comb-shaped structure derived from a main chain branch structure, continuing polymerization to increase the molecular weight, and then modifying the conjugated diene polymer with a tri- or more functional coupling modifier. Such a conjugated diene polymer has a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group in at least one branched chain of the star structure. Regarding the method for obtaining a conjugated diene polymer having a further main chain branch structure in the moiety derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group, the "star polymer structure" can be formed by adjusting the number of functional groups of the modifier and the amount of the modifier added, and the "main chain branch structure" can be controlled by adjusting the number of functional groups of the branching agent, the amount of branching agent added, and the timing of adding the branching agent.

[0100] <Conjugated Diene Polymer Having Star-Shaped Polymer Structure [B]> The conjugated diene polymer of the present embodiment preferably contains, in its star-shaped branched structure, a structure having a nitrogen atom-containing group represented by any one of the following general formulas (5-1) to (5-4), (7-1) to (7-2), (8), and (9-1) to (9-2).

[0101]

[0102]

[0103]

[0104]

[0105] In the formulas (5-1) to (5-4), R is a divalent or higher hydrocarbon group, or a divalent or higher organic group having at least one polar group selected from polar groups containing oxygen such as ether, epoxy, and ketone, polar groups containing sulfur such as thioether and thioketone, and polar groups containing nitrogen such as tertiary amino and imino groups.

[0106] The divalent or higher valent hydrocarbon group is a saturated or unsaturated hydrocarbon group which may be linear, branched, or cyclic, and includes an alkylene group, an alkenylene group, a phenylene group, etc. Preferably, it is a hydrocarbon group having 1 to 20 carbon atoms. Examples include methylene, ethylene, butylene, cyclohexylene, 1,3-bis(methylene)-cyclohexane, 1,3-bis(ethylene)-cyclohexane, o-, m-, and p-phenylene, m- and p-xylene, and bis(phenylene)-methane.

[0107] In the formulas (5-1) to (5-4), R ２４ , R ２７ is a hydrocarbon group having 1 to 10 carbon atoms, and R ２４ , R ２７ may be the same or different from each other.

[0108] In the formulas (5-1) to (5-4), R ２５ , R ２８ is hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, and R ２５ , R ２８ may be the same or different from each other.

[0109] In the formulas (5-1) to (5-4), P ３ , P ４ is a polymer chain, which is a forked portion [A] having a main chain branched structure, or a linear polymer chain having no branched structure.

[0110] In the formulas (5-1) to (5-4), R ２６ is a hydrocarbon group having 1 to 10 carbon atoms or a structure of the following formulas (6-1) to (6-3).

[0111]

[0112]

[0113]

[0114] In the formulas (5-1) to (5-4), R ２４ , R ２５ , R ２６ may be bonded to each other to form a cyclic structure.

[0115] In addition, in the formulas (5-1) to (5-4), R ２６ When R is a hydrocarbon group, it may be bonded to R to form a cyclic structure. ２６ and R may be directly bonded to each other.

[0116] In the formulas (5-1) to (5-4), f is an integer of 1 or more, and g is 0 or an integer of 1 or more.

[0117] In the formulas (6-1) to (6-3), R ２９ , R ３０ are R in the formulas (5-1) to (5-4), respectively. ２４ , R ２５ In the formulas (6-1) to (6-3), P ５ is P in the formulas (5-1) to (5-4). ３ , P ４ is defined in the same way as R ２９ , R ３０ may be the same or different from each other.

[0118]

[0119]

[0120] In the formulas (7-1) to (7-2), P ６ , P ７ is a polymer chain, which is a forked portion [A] having a main chain branched structure or a linear polymer chain having no branched structure. ６ , P ７ When a plurality of each of the groups are bonded (when h, i, or j is an integer of 2 or more), P ６ , P ７ Each of them may be the same or different. ３３ , R ３４ each independently represents an alkyl group or hydrocarbyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms; R ３５ represents an alkylene group having 1 to 10 carbon atoms, and R ３６ represents an alkylene group having 1 to 20 carbon atoms, h represents an integer of 1 to 3, i represents an integer of 1 to 3, j represents an integer of 1 or 2, and (h+i) and (h+j) represent integers of 3 or more.

[0121]

[0122] In the formula (8), P ８ , P ９ , P １０ is a polymer chain, which is a forked portion [A] having a main chain branched structure or a linear polymer chain having no branched structure. ８ , P ９ , P １０ When a plurality of each of m, n, or l is bonded (when m, n, or l is an integer of 2 or more), P ８ , P ９ , P １０ Each of them may be the same or different. ４０ ~R ４２ each independently represents an alkyl group or hydrocarbyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms; R ４３ ~R ４５ each independently represents an alkylene group having 1 to 20 carbon atoms. m, n, and l each independently represent an integer of 1 to 3, and (m+n+l) represents an integer of 3 or greater.

[0123]

[0124]

[0125] In the formulas (9-1) and (9-2), P １１ ~P １４ is a polymer chain, which is a forked portion [A] having a main chain branched structure or a linear polymer chain having no branched structure. １１ , P １２ When a plurality of each of is bonded (when o or p is an integer of 2 or more), P １１ , P １２ Each of them may be the same or different. ４６ ~R ４８ each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms; R ４９ , and R ５１ each independently represents an alkyl group or a hydrocarbyl group having 1 to 20 carbon atoms; R ５３ and R ５６ each independently represents an alkylene group having 1 to 20 carbon atoms; R ５５ represents an alkyl group or trialkylsilyl group having 1 to 20 carbon atoms, and may contain S, O, or N and be substituted with an organic group not having active hydrogen, and may have an unsaturated bond, and may be the same or different. o represents an integer of 1 to 3, p represents 1 or 2, and t represents an integer of 1 to 3. When there are multiple R ４６ ~R ５６ , o, p, and t are each independent and may be the same or different. q represents an integer of 0 to 6, r represents an integer of 0 to 6, s represents an integer of 0 to 6, and (q + r + s) 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 oxygen atoms, nitrogen atoms, silicon atoms, sulfur atoms, and phosphorus atoms and having no active hydrogen atoms.

[0126] In the formulas (9-1) and (9-2), A is preferably represented by any one of the following general formulas (I) to (IV).

[0127]

[0128] In the formula (I), B １ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and u represents an integer of 1 to 10. １ are each independent of each other.

[0129]

[0130] In the formula (II), B ２ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, B ３ represents an alkyl group having 1 to 20 carbon atoms, and u represents an integer of 1 to 10. ２ and B ３ are each independent of each other.

[0131]

[0132] In the formula (III), B ４ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and u represents an integer of 1 to 10. ４ are each independent of each other.

[0133]

[0134] In the formula (IV), B ５ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and u represents an integer of 1 to 10. ５ are each independent of each other.

[0135] [Molded Product] The molded product of this embodiment is a molded product containing the conjugated diene-based polymer of this embodiment described above. From the viewpoint of handling, it is preferably a sheet-shaped or block-shaped molded product. The size and thickness of the sheet-shaped or block-shaped molded product are not particularly limited, but for example, a sheet-shaped molded product with a thickness of about 1 cm, a block-shaped molded product with a thickness of 1,000 cm, or a block-shaped molded product with a thickness of about 1,000 cm may be used. ３ The molded body of this embodiment is more preferably a block-shaped molded body, and the shape of the block is preferably a roughly rectangular parallelepiped, and the block size is preferably 1,000 cm or less. ３The above-mentioned block-shaped (bale) molded bodies are more preferable, and rectangular parallelepiped bales weighing 17.5 kg to 35 kg are even more preferable.

[0136] The molding method is to use a material with a specific surface area of ​​0.7 m ２ / g to 3.2m ２ / g and then compression-molding the crumbs. From the viewpoint of moldability, it is preferable to further carry out a step of sieving the crumbs before molding. Since the crumbs adhere to each other when compression-molding the crumbs, the specific surface area of ​​the molded product becomes smaller than the specific surface area of ​​the crumbs. The adhesion of the crumbs during compression molding can be adjusted by the molecular weight, composition, and structure of the conjugated diene polymer, the softener component composition, and the temperature and pressure during compression. For example, when it is desired to increase the adhesion of the crumbs and decrease the specific surface area of ​​the bale, it is preferable to reduce the molecular weight of the conjugated diene polymer, increase the amount of the softener component, and increase the temperature and pressure during compression.

[0137] The specific surface area of ​​the molded body of this embodiment is preferably 0.005 to 0.05 m ２ / g, and more preferably, from the viewpoint of film packaging properties, 0.01 to 0.04 m ２ / g. The specific surface area of ​​the molded body is 0.005 m ２ / g or more, the expansion of the bale is suppressed, and the specific surface area of ​​the molded body is 0.05 m ２ / g or less is preferable because it reduces the peeling of crumbs from the molded body. The specific surface area of ​​the molded body can be determined by the BET method. Usually, the specific surface area of ​​a large-sized molded body may vary depending on the location, so it is preferable to collect from near the center of the molded body.

[0138] It is preferable that the crumbs are sieved by particle size before molding and then mixed in an appropriate ratio. If the specific surface area of ​​a molded body molded using the crumbs after solvent removal as is exceeds the upper limit of the above range, it is preferable to increase the composition of large particle crumbs and decrease the composition of small particle crumbs among the sieved crumbs, and if it is below the lower limit, it is preferable to decrease the composition of large particle crumbs and increase the composition of small particle crumbs.

[0139] The molding compression pressure for the molded product is preferably 3 MPa to 30 MPa, more preferably 10 MPa to 20 MPa. When the molding compression pressure is 30 MPa or less, the device can be designed compactly and installation efficiency is good, while when the molding compression pressure is 3 MPa or more, moldability is good. When moldability is good, the surface of the molded product is smooth, there is no peeling of the polymer after the molding process, and expansion after molding tends to be suppressed.

[0140] The temperature of the conjugated diene polymer or the rubber composition containing the conjugated diene polymer during molding is preferably 30 to 120°C, and more preferably 50 to 100°C from the viewpoints of reducing residual solvent and suppressing thermal degradation. A molding temperature of 30°C or higher provides good moldability, while a temperature of 120°C or lower is preferred because it suppresses gel formation due to thermal degradation of the rubber composition. The higher the molding temperature and pressure, the smaller the specific surface area of ​​the bale. The pressure dwell time during molding is preferably 3 to 30 seconds, and more preferably 5 to 20 seconds. A pressure dwell time during compression of 30 seconds or less provides good production efficiency, and a pressure dwell time of 5 seconds or more provides good moldability.

[0141] It is preferable to package the molded articles in a resin film (packaging sheet) to prevent them from adhering to each other. Examples of resins that can be used for the film include polyethylene, ethylene copolymer resin, polystyrene, high-impact polystyrene, and PET. It is preferable that the adhesiveness of the packaging sheet is good from the viewpoints of ease of handling during transportation of the molded articles and preventing condensation from forming in the gap between the packaging sheet and the bale. The molded article of this embodiment is used, for example, for storage in a container for transportation. If the expansion rate of the molded article one day after molding is less than 5%, it is preferable because it is easy to store in a container.

[0142] A softener component, which will be described later, may be added to a sheet- or block-shaped molded product using the conjugated diene polymer of this embodiment. However, in the molded product of this embodiment, from the viewpoint of improving the degree of freedom in compounding during the production of a rubber composition, which will be described later, the amount of the softener component is preferably 2 parts by mass or less, more preferably 1.5 parts by mass or less, even more preferably 1 part by mass or less, even more preferably less than 1 part by mass, per 100 parts by mass of the conjugated diene polymer. It is most preferable that no softener component is added. Note that the softener component used during the production of a rubber composition, which will be described later, is sometimes referred to as a "rubber softener," but this is merely a literal distinction from the softener component used in a molded product of the conjugated diene polymer, and does not distinguish the material itself.

[0143] [Method for Producing Modified Conjugated Diene Polymer] The method for producing a conjugated diene polymer of this embodiment will be described in detail below. The method for producing a modified conjugated diene polymer of this embodiment includes continuously polymerizing a conjugated diene polymer (A) and a conjugated diene polymer (B) using one or more reactors, respectively, mixing a polymerization solution containing the modified conjugated diene polymer (A) with a polymerization solution containing the modified conjugated diene polymer (B), and then removing the solvent to obtain a modified conjugated diene polymer.

[0144] <Method for Producing Conjugated Diene Polymer (A) and Conjugated Diene Polymer (B)> The method for producing the conjugated diene polymer (A) or the conjugated diene polymer (B) comprises the steps of polymerizing a conjugated diene compound, optionally together with a vinyl aromatic compound, using an alkali metal compound or an alkaline earth metal compound (e.g., an organometallic compound such as an organolithium compound) as a polymerization initiator, adding a branching agent to obtain a conjugated diene polymer having a branched structure (hereinafter, these steps may be collectively referred to as a polymerization branching step), and adding a coupling modifier. In the production method, the conjugated diene polymer (A) and the conjugated diene polymer (B) do not necessarily need to undergo the polymerization branching step, but it is preferable that either the conjugated diene polymer (A) or the conjugated diene polymer (B) be produced via the polymerization branching step.

[0145] The polymerization reaction of the conjugated diene compound and the aromatic vinyl compound is preferably a propagation reaction due to a living anionic polymerization reaction, which allows a conjugated diene polymer having an active terminal to be obtained. As a result, when a branching agent is added, the conjugated diene polymer and the branching agent react efficiently. Furthermore, even when the production method of this embodiment includes a coupling step described below, the reaction tends to be highly efficient.

[0146] The polymerization reaction mode is not limited to the following, but examples thereof include a batchwise polymerization mode (hereinafter also referred to as a "batchwise polymerization mode") and a continuous polymerization mode.

[0147] In the continuous system, one or more connected reactors can be used. As the continuous reactor, for example, a tank type or a tubular type equipped with a stirrer can be used. In the continuous system, preferably, a monomer, an inert solvent described later, and a polymerization initiator described later are continuously fed into the reactor, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is continuously discharged.

[0148] As the batch reactor, for example, a tank-type reactor equipped with a stirrer is used. In the batch reactor, preferably, a monomer, an inert solvent described later, and a polymerization initiator described later are fed, and if necessary, a monomer is added continuously or intermittently during polymerization, to obtain a polymer solution containing a polymer in the reactor, and the polymer solution is discharged after the polymerization is completed.

[0149] In the method for producing the conjugated diene polymer (A) or the conjugated diene polymer (B), from the viewpoint of being able to obtain a conjugated diene polymer having an active end in a high proportion, it is preferable to carry out the polymerization reaction in a continuous polymerization reaction mode in which the polymer can be continuously discharged and subjected to the next reaction in a short period of time.

[0150] (Polymerization Branching Step) In the method for producing the conjugated diene polymer (A) or the conjugated diene polymer (B), the polymerization branching step is a step of polymerizing at least a conjugated diene compound, optionally together with a vinyl aromatic compound, using a polymerization initiator such as an organolithium compound described below, while adding a branching agent to obtain a conjugated diene polymer having a branched structure. Therefore, in the polymerization branching step, before the branching agent is added, the polymerization reaction of at least the conjugated diene compound and the aromatic vinyl compound is the main reaction, and after the branching agent is added, the branching reaction starts.

[0151] As the conjugated diene compound and the vinyl aromatic compound, which are the monomers used in the polymerization branching step, at least one of the above-mentioned conjugated diene compound and at least one of the above-mentioned vinyl aromatic compound may be used. Furthermore, from the viewpoint of being able to introduce a nitrogen atom into the conjugated diene polymer, the above-mentioned conjugated diene compound or the above-mentioned vinyl aromatic compound may be a derivative substituted so as to have at least one nitrogen atom in the molecule.

[0152] The polymerization initiator is not particularly limited, but for example, an organolithium compound such as an organomonolithium compound can be used.

[0153] The organic monolithium compound includes, for example, a compound having a carbon-lithium bond, a compound having a nitrogen-lithium bond, and a compound having a tin-lithium bond in terms of the bonding mode between the organic group and the lithium.

[0154] Among these, the organic monolithium compound is preferably an organic lithium compound having at least one nitrogen atom in the molecule, from the viewpoint of being able to introduce a nitrogen atom into the conjugated diene-based polymer, and more preferably an alkyllithium compound having a substituted amino group or a dialkylaminolithium.

[0155] The substituted amino group is an amino group that does not have an active hydrogen atom or an amino group in which the active hydrogen atom is protected.

[0156] Examples of the alkyllithium compound having an amino group that does not have active hydrogen include, but are not limited to, piperidinolithium, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium.

[0157] Examples of the alkyllithium compound having an amino group with an active hydrogen protected include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0158] Examples of dialkylaminolithiums 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.

[0159] These organomonolithium compounds having a substituted amino group can also be used as solubilized oligomeric organomonolithium compounds by reacting them with a small amount of a polymerizable monomer, such as 1,3-butadiene, isoprene, or styrene.

[0160] When the polymerization initiator has a nitrogen atom constituting an amino group, a chain transfer reaction is likely to occur during the anionic polymerization, and the amount of the coupling modifier reacting with the active terminal after the polymerization is completed tends to be small. As a result, when a polymerization initiator having a nitrogen atom constituting an amino group is used, the weight-average molecular weight tends to be small. Therefore, a weight-average molecular weight of 35×10 ４ That's it, 40 x 10 ４ That's it, 45 x 10 ４ or more, or 60 x 10 ４ In the above-mentioned relatively high molecular weight polymers, when it is desired to set a high modification rate, it is preferable to react nitrogen atoms at the polymerization termination end rather than the polymerization initiation end. That is, polymers that have a relatively high molecular weight and contain nitrogen atoms at both ends tend to be difficult to produce. Although it depends on the weight average molecular weight and the structure of the coupling modifier, when nitrogen atoms are present only at the termination end, the nitrogen content of the polymer is generally 3 ppm to 500 ppm by mass.

[0161] From the viewpoints of industrial availability and ease of control of the polymerization reaction, an alkyllithium compound may be used as the organomonolithium compound. When such an organomonolithium compound is used, a conjugated diene polymer having an alkyl group at the polymerization initiation terminal can be obtained.

[0162] Examples of alkyllithium compounds include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium. As the alkyllithium compound, n-butyllithium and sec-butyllithium are preferred from the viewpoints of industrial availability and ease of control of the polymerization reaction. These organomonolithium compounds may be used alone or in combination of two or more. Furthermore, they may be used in combination with other organometallic compounds.

[0163] Other organometallic compounds include, but are not limited to, alkaline earth metal compounds, alkali metal compounds other than lithium, and other organometallic compounds. Examples of alkaline earth metal compounds include, but are not limited to, organomagnesium compounds, organocalcium compounds, and organostrontium compounds. Examples of alkaline earth metal alkoxides, sulfonates, carbonates, and amides are also included. Examples of organomagnesium compounds include, but are not limited to, dibutylmagnesium and ethylbutylmagnesium. Examples of other organometallic compounds include, but are not limited to, organoaluminum compounds.

[0164] The amount of polymerization initiator added is preferably determined depending on the molecular weight of the target conjugated diene polymer. The number average molecular weight and / or weight average molecular weight can be controlled by the ratio of the amount of monomer added to the amount of polymerization initiator added. Specifically, when the proportion of the amount of polymerization initiator added is reduced, the molecular weight tends to increase, and when the proportion of the amount of polymerization initiator added is increased, the molecular weight tends to decrease.

[0165] From the viewpoint of reliably and simply obtaining the conjugated diene polymer (A) or the conjugated diene polymer (B), the polymerization branching step is preferably carried out in an inert solvent. Examples of such inert solvents include, but are not limited to, 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.

[0166] From the viewpoint of obtaining a conjugated diene-based polymer in which a conjugated diene compound and a vinyl aromatic compound are randomly polymerized, the polymerization reaction in the polymerization branching step may be carried out using, for example, the following method as described in JP-A-59-140211: That is, a method may be used in which the polymerization reaction is first initiated using the entire amount of the vinyl aromatic compound and a portion of the conjugated diene compound, and then the remaining conjugated diene compound is intermittently added during the polymerization reaction.

[0167] The polymerization temperature in the polymerization reaction in the polymerization branching step is not particularly limited, but is preferably a temperature at which living anionic polymerization proceeds. From the viewpoint of improving productivity, the polymerization temperature is more preferably 0°C or higher, and even more preferably 0°C or higher and 120°C or lower. When the polymerization temperature in the polymerization reaction is within the above range, the reactivity with the coupling modifier in the coupling step described below tends to be sufficiently enhanced. From the same viewpoint, the polymerization temperature in the polymerization reaction is even more preferably 50°C or higher and 100°C or lower.

[0168] In the polymerization branching step, a polar compound may be added. When a polar compound is added, a conjugated diene polymer in which a vinyl aromatic compound and a conjugated diene compound are copolymerized in a more random manner tends to be obtained. As such, the polar compound has an effective randomizing effect in the copolymerization of a conjugated diene compound and a vinyl aromatic compound, and can therefore be used as an agent for adjusting the distribution of the vinyl aromatic compound or the amount of styrene blocks. Furthermore, the polar compound can accelerate the polymerization reaction and can also be used as a vinylating agent for controlling the microstructure of the conjugated diene polymer.

[0169] Thus, since polar compounds are used as vinylating agents, randomizing agents, and polymerization accelerators, reducing the amount of polar compound, for example, to adjust the vinylation rate or randomization rate, tends to reduce the polymerization-accelerating effect. Therefore, in a method of adjusting the branching degree of a polymer by reacting a coupling modifier with a polymerization end terminal, reducing the amount of polar compound added increases the polymerization time and the proportion of deactivated polymerization end terminals. As a result, such a method tends to make it difficult to increase the modification rate. That is, when attempting to adjust the branching degree of a modified conjugated diene polymer by adjusting the amount of polar compound added and reacting it with a coupling modifier, it tends to be difficult to control the vinylation rate or randomization rate. In this regard, the production method of this embodiment can increase the branching degree of the polymer using a branching agent described below, thereby enabling the branching degree to be controlled independently of the vinylation rate or randomization rate, which is advantageous in terms of structural design of the conjugated diene polymer.

[0170] Examples of polar compounds 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.

[0171] The amount of polar compound added is not particularly limited, but can be adjusted depending on the amount of polymerization active terminals, i.e., the amount of polymerization initiator added. The amount of polar compound added is, for example, preferably 0.010 mol or more and 1.0 mol or less, and more preferably 0.10 mol or more and 0.70 mol or less, per mol of polymerization initiator. Within the above range, the amount of polar compound added may be 0.60 mol or less or 0.50 mol or less per mol of polymerization initiator. Alternatively, it may be 0.15 mol or more or 0.20 mol or more per mol of polymerization initiator. When the amount of polar compound added is equal to or less than the above upper limit, a conjugated diene polymer with a low Tg tends to be obtained. Furthermore, when the amount of polar compound added is equal to or greater than the above lower limit, deactivation of the polymerization active terminals is suppressed, and the coupling rate in the coupling step described below tends to be improved. The amount of polar compound added may be within a range that arbitrarily combines the above upper and lower limits.

[0172] The production method for the conjugated diene polymer (A) or the conjugated diene polymer (B) may include a step of removing impurities before the polymerization / branching step. In particular, when the above-mentioned monomer, polymerization initiator, and / or inert solvent contain allenes and acetylenes as impurities, it is preferable to include a step of removing impurities before the polymerization / branching step. By including the step of removing impurities, a conjugated diene polymer having a high concentration of active ends tends to be obtained, and a modified conjugated diene polymer with a high modification rate tends to be obtained in the coupling step described below. The step of removing such impurities is not particularly limited, but examples thereof include a step of treating with an organometallic compound. Examples of such organometallic compounds include, but are not particularly limited to, organolithium compounds, and examples of organolithium compounds include, but are not particularly limited to, n-butyllithium.

[0173] In the polymerization-branching step, a branching reaction is initiated in the conjugated diene polymer by adding a branching agent described below. After the branching agent is added, a polymerization reaction in which the conjugated diene polymer grows and a branching reaction in which the conjugated diene polymer branches occur in competition with each other in the reaction system. Therefore, by adjusting the type and amount of branching agent added and the timing of adding the branching agent, it is possible to control the weight-average molecular weight, number-average molecular weight, ratio thereof (Mw / Mn), and absolute molecular weight of the conjugated diene polymer obtained in the polymerization-branching step, as well as the branching degree, number of branching points, and number of branches at branching points of the conjugated diene polymer.

[0174] Furthermore, by adding a branching agent during polymerization of a conjugated diene polymer, the total amount of active ends of the conjugated diene polymer in the reaction system can be reduced compared to the amount of polymerization initiator added, and even if a small amount of polar compound is added, the reaction at the initial stage of polymerization can be promoted and the activity of the polymerization active ends can be maintained. As a result, for the conjugated diene polymer of this embodiment, whose amount of bound vinyl aromatic monomer units and vinyl bond amount are within the above-mentioned specified ranges, the coupling rate and / or modification rate of the polymerization terminal ends can be easily improved. However, it is not essential that the conjugated diene polymer of this embodiment be reacted with a coupling modifier.

[0175] As described above, in the method for producing a conjugated diene polymer of this embodiment, the amount of polar compound added can be adjusted to control the microstructure, such as the amount of bound vinyl aromatic monomer units and the amount of vinyl bonds. The amount of polar compound typically used to set the amount of bound vinyl aromatic monomer units and the amount of vinyl bonds within the above-mentioned ranges is insufficient from the perspective of maintaining the active terminals of the conjugated diene polymer in the reaction system, and it is not easy to sufficiently maintain the activity of the polymerization active terminals, unless a branching agent is added. Furthermore, such an amount of polar compound does not provide a sufficiently high randomization ability for the vinyl aromatic compound and the conjugated diene compound. Therefore, in the conjugated diene polymer of this embodiment, in which the amount of bound vinyl aromatic monomer units and the amount of vinyl bonds are within the above-mentioned ranges, the polymerization terminals tend to be vinyl aromatic monomer units. Under such conditions, it tends to be difficult to obtain a conjugated diene polymer with a high coupling rate or modification rate. That is, in the method for producing a conjugated diene-based polymer of the present embodiment, a branching agent is used, so that even with an added amount of a polar compound that normally does not easily maintain the activity of the polymerization active terminals sufficiently, the active terminals of the polymer can be sufficiently maintained, and a high coupling rate and modification rate can be achieved.

[0176] The timing of adding the branching agent in the branching step is not particularly limited and can be appropriately selected depending on the application of the conjugated diene polymer to be produced. From the viewpoint of improving the absolute molecular weight of the resulting conjugated diene polymer and improving the modification rate in the coupling step, the timing of adding the branching agent 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. In other words, the timing of adding the branching agent is preferably when the polymerization reaction is sufficiently stable. By setting the timing of adding the branching agent within the above range, a conjugated diene polymer with a higher modification rate in the coupling step can be obtained even if the amount of polar compound added is small or no.

[0177] The branching agent is not particularly limited, but for example, a compound represented by the following formula (10) or formula (11) can be used.

[0178]

[0179]

[0180] (In formula (10), 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, and may partially have a branched structure. ２ ~R ３ are each independently 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 ３ are each independent. 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 (11), R ４ ~R ７ are each independently 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. ４ ~R ７ are each independent. 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 3, b represents an integer of 0 to 2, and c represents an integer of 0 to 3. (a+b+c) represents 3.

[0181] In this embodiment, the branching agent used to construct the main chain branched structure of the conjugated diene polymer is, from the viewpoint of continuity of polymerization and improvement of the degree of branching, R １ is a hydrogen atom and m=0.

[0182] In addition, in the present embodiment, the branching agent used to construct a main chain branched structure of the conjugated diene polymer is preferably a compound in which m=0 and b=0 in the above formula (11), from the viewpoint of improving the degree of branching.

[0183] In this embodiment, the branching agent used to construct the main chain branched structure of the conjugated diene polymer is, from the viewpoint of continuity of polymerization, improvement of the modification rate and the degree of branching, R １ is a hydrogen atom, m=0, and l=0.

[0184] In the present embodiment, the branching agent used to construct a main chain branched structure of the conjugated diene polymer is more preferably a compound in which m = 0, l = 0, a = 0, and b = 0 in the above formula (11), from the viewpoint of improving the modification rate and the degree of branching.

[0185] In this embodiment, the branching agent used to construct the main chain branched structure of the conjugated diene polymer is, from the viewpoint of continuity of polymerization, improvement of the modification rate and the degree of branching, R １ is a hydrogen atom, l=0, and n=3.

[0186] Examples of the branching agent represented by the formula (10) 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, phenyl)silane, trimethoxy(2-vinylphenyl)silane, triethoxy(2-vinylphenyl)silane, tripropoxy(2-vinylphenyl)silane, tributoxy(2-vinylphenyl)silane, triisopropoxy(2-vinylphenyl)silane, dimethoxymethyl(4-vinylphenyl)silane, diethoxymethyl(4-vinylphenyl)silane, dipropoxymethyl(4-vinylphenyl)silane, dibutoxymethyl(4-vinylphenyl)silane, diisopropoxymethyl(4-vinylphenyl)silane, dimethoxymethyl (3-vinylphenyl)silane, diethoxymethyl(3-vinylphenyl)silane, dipropoxymethyl(3-vinylphenyl)silane, dibutoxymethyl(3-vinylphenyl)silane, diisopropoxymethyl(3-vinylphenyl)silane, dimethoxymethyl(2-vinylphenyl)silane, diethoxymethyl(2-vinylphenyl)silane, dipropoxymethyl(2-vinylphenyl)silane, dibutoxymethyl(2-vinylphenyl)silane, diisopropoxymethyl(2-vinylphenyl)silane, dimethylmethoxy(4-vinylphenyl) (vinylphenyl)silane, dimethylethoxy(4-vinylphenyl)silane, dimethylpropoxy(4-vinylphenyl)silane, dimethylbutoxy(4-vinylphenyl)silane, dimethylisopropoxy(4-vinylphenyl)silane, dimethylmethoxy(3-vinylphenyl)silane, dimethylethoxy(3-vinylphenyl)silane, dimethylpropoxy(3-vinylphenyl)silane, dimethylbutoxy(3-vinylphenyl)silane, dimethylisopropoxy(3-vinylphenyl)silane, dimethylmethoxy(2-vinylphenyl)silane,Examples include dimethylethoxy(2-vinylphenyl)silane, dimethylpropoxy(2-vinylphenyl)silane, dimethylbutoxy(2-vinylphenyl)silane, and dimethylisopropoxy(2-vinylphenyl)silane.

[0187] Further, examples of the branching agent represented by the formula (10) include 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, (3-isopropenylphenyl)silane, triisopropoxy(3-isopropenylphenyl)silane, trimethoxy(2-isopropenylphenyl)silane, triethoxy(2-isopropenylphenyl)silane, tripropoxy(2-isopropenylphenyl)silane, tributoxy(2-isopropenylphenyl)silane, triisopropoxy(2-isopropenylphenyl)silane, dimethoxymethyl(4-isopropenylphenyl)silane, diethoxymethyl(4-isopropenylphenyl)silane, dipropoxymethyl(4-isopropenylphenyl)silane, dibutoxy Dimethyl(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, dip propoxymethyl(2-isopropenylphenyl)silane, dibutoxymethyl(2-isopropenylphenyl)silane, diisopropoxymethyl(2-isopropenylphenyl)silane, dimethylmethoxy(4-isopropenylphenyl)silane, dimethylethoxy(4-isopropenylphenyl)silane, dimethylpropoxy(4-isopropenylphenyl)silane, dimethylbutoxy(4-isopropenylphenyl)silane, dimethylisopropoxy(4-isopropenylphenyl)silane, dimethylmethoxy(3-isopropenylphenyl)silane,Dimethylethoxy(3-isopropenylphenyl)silane, dimethylpropoxy(3-isopropenylphenyl)silane, dimethylbutoxy(3-isopropenylphenyl)silane, dimethylisopropoxy(3-isopropenylphenyl)silane, dimethylmethoxy(2-isopropenylphenyl)silane, dimethylethoxy(2-isopropenylphenyl)silane, dimethylpropoxy(2-isopropenylphenyl)silane, dimethylbutoxy(2-isopropenylphenyl)silane, dimethylisopropoxy(2-isopropenylphenyl)silane, trichloro(4-vinylphenyl)silane, trichloro(3-vinylphenyl)silane, trichloro(2-vinylphenyl)silane, tribromo(4-vinylphenyl)silane Examples of suitable silanes include tribromo(3-vinylphenyl)silane, tribromo(2-vinylphenyl)silane, dichloromethyl(4-vinylphenyl)silane, dichloromethyl(3-vinylphenyl)silane, dichloromethyl(2-vinylphenyl)silane, dibromomethyl(4-vinylphenyl)silane, dibromomethyl(3-vinylphenyl)silane, dibromomethyl(2-vinylphenyl)silane, dimethylchloro(4-vinylphenyl)silane, dimethylchloro(3-vinylphenyl)silane, dimethylchloro(2-vinylphenyl)silane, dimethylbromo(4-vinylphenyl)silane, dimethylbromo(3-vinylphenyl)silane, and dimethylbromo(2-vinylphenyl)silane.

[0188] 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.

[0189] Examples of the branching agent represented by the formula (11) include, but are not limited to, 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-trippropoxysilylphenyl)ethylene, 1,1-bis(3-tripentoxysilylphenyl)ethylene, 1,1-bis(3-triisopropoxysilylphenyl)ethylene, 1,1-bis(2-

[0033] Examples of such ethylene include 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.

[0190] Among these, 1,1-bis(4-trimethoxysilylphenyl)ethylene, 1,1-bis(4-triethoxysilylphenyl)ethylene, 1,1-bis(4-tripropoxysilylphenyl)ethylene, 1,1-bis(4-tripentoxysilylphenyl)ethylene, and 1,1-bis(4-triisopropoxysilylphenyl)ethylene are preferred, and 1,1-bis(4-trimethoxysilylphenyl)ethylene is more preferred.

[0191] The amount of branching agent added is not particularly limited and can be appropriately selected depending on the intended use of the conjugated diene polymer, but is preferably 0.020 mol or more and 0.50 mol or less, more preferably 0.025 mol or more and 0.40 mol or less, and even more preferably 0.030 mol or more and 0.25 mol or less, relative to 1 mol of polymerization initiator. Within the above range, the amount of branching agent added may be 0.040 mol or more or 0.045 mol or more, relative to 1 mol of polymerization initiator. Alternatively, it may be 0.20 mol or less or 0.18 mol or less, relative to 1 mol of polymerization initiator. The amount of branching agent added may be within a range that arbitrarily combines the above upper and lower limits. The amount of branching agent added affects the degree of branching of the entire conjugated diene polymer, and increasing the amount added increases the overall degree of branching and the degree of branching at the extreme values.

[0192] In the polymerization branching step, the reaction temperature may or may not be changed after the branching agent is added.

[0193] In the polymerization branching step, after adding the branching agent, a monomer that is a raw material for the conjugated diene polymer may be further added, and then the branching agent may be further added, or the addition of the branching agent and the monomer may be repeated.

[0194] The monomer to be added is not particularly limited, but from the viewpoint of improving the modification rate in the coupling step, it is preferable to add the same monomer as the initial monomer added in the polymerization / branching step. The amount of the added monomer may be 1.0% or more, 5.0% or more, 10% or more, 15% or more, or 20% or more of the total amount of monomers used in the conjugated diene polymer. The amount of the added monomer may be 50% or less, 40% or less, or 35% or less. When the amount of the added monomer is within the above range, the molecular weight between the branching point formed by adding the branching agent and the branching point formed by adding the coupling modifier is increased, and thus a highly linear molecular structure tends to be obtained. By providing the resulting conjugated diene polymer with such a structure, entanglement between molecular chains of the conjugated diene polymer increases when the polymer is vulcanized, and a vulcanizate excellent in abrasion resistance, handling stability, and breaking strength tends to be obtained.

[0195] (Coupling Step) In the method for producing a conjugated diene polymer of this embodiment, it is preferable to convert the conjugated diene polymer having a branched structure obtained in the polymerization-branching step described above into a modified conjugated diene polymer by reacting it with a coupling modifier. By this coupling step, the conjugated diene polymer having a branched structure obtained in the polymerization-branching step can be modified with a nitrogen-containing functional group that has affinity or binding reactivity with a filler. Furthermore, multiple conjugated diene polymers can be coupled together. Therefore, a production method including this coupling step can more reliably and simply produce the conjugated diene polymer of this embodiment that exhibits the above-mentioned effects.

[0196] The coupling modifier is not particularly limited as long as it is a reactive compound having a nitrogen atom-containing functional group that has affinity or bonding reactivity with the filler and is capable of reacting with the active terminal of the conjugated diene polymer and has two or more functional groups. Examples of such coupling modifiers include coupling modifiers that contain a nitrogen atom and further have a group containing a nitrogen atom and a silicon atom.

[0197] Examples of coupling modifiers having a group containing a nitrogen atom include, but are not limited to, isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, nitrogen-containing carbonyl compounds, nitrogen-containing vinyl compounds, nitrogen-containing epoxy compounds, imine compounds, and nitrogen-containing alkoxysilane compounds.

[0198] Preferable coupling modifiers having a nitrogen atom-containing group include, for example, amine compounds having no active hydrogen, protected amine compounds in which active hydrogen is substituted with a protecting group, imine compounds having a structure of the general formula -N=C, and alkoxysilane compounds bonded to these nitrogen atom-containing compounds. Examples of amine compounds having no active hydrogen include tertiary amine compounds.

[0199] Examples of the isocyanate compound 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.

[0200] Examples of the isothiocyanate compound include, but are not limited to, 2,4-tolylene diisothiocyanate, 2,6-tolylene diisothiocyanate, diphenylmethane diisothiocyanate, phenyl isothiocyanate, isophorone diisothiocyanate, hexamethylene diisothiocyanate, butyl isothiocyanate, and 1,3,5-benzene triisothiocyanate.

[0201] Examples of isocyanuric acid derivatives include, but are not limited to, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate, 1,3,5-tris(3-triethoxysilylpropyl)isocyanurate, 1,3,5-tri(oxiran-2-yl)-1,3,5-triazinane-2,4,6-trione, 1,3,5-tris(isocyanatomethyl)-1,3,5-triazinane-2,4,6-trione, and 1,3,5-trivinyl-1,3,5-triazinane-2,4,6-trione.

[0202] Examples of the nitrogen atom-containing carbonyl compound include, but are not limited to, 1,3-dimethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 1-methyl-3-(2-methoxyethyl)-2-imidazolidinone, N-methyl-2-pyrrolidone, N-methyl-2-piperidone, N-methyl-2-quinolone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, methyl-2-pyridinone, Examples of suitable methyl ketones 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-methyl diethylcarbamate, N,N-diethylacetamide, N,N-dimethyl-N',N'-dimethylaminoacetamide, N,N-dimethylpicolinic acid amide, and N,N-dimethylisonicotinic acid amide.

[0203] Examples of nitrogen atom-containing vinyl compounds include, but are not limited to, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N-methylmaleimide, N-methylphthalimide, N,N-bistrimethylsilyl acrylamide, morpholinoacrylamide, 3-(2-dimethylaminoethyl)styrene, (dimethylamino)dimethyl-4-vinylphenylsilane, 4,4′-vinylidenebis(N,N-dimethylaniline), 4,4′-vinylidenebis(N,N-diethylaniline), 1,1-bis(4-morpholinophenyl)ethylene, and 1-phenyl-1-(4-N,N-dimethylaminophenyl)ethylene.

[0204] Examples of nitrogen-containing epoxy compounds include, but are not limited to, hydrocarbon compounds containing an epoxy group bonded to an amino group. Furthermore, the hydrocarbon compounds containing an epoxy group bonded to an amino group may further have an epoxy group bonded to an ether group. Examples of such nitrogen-containing epoxy compounds include, but are not limited to, compounds represented by the following formula (12):

[0205]

[0206] In the formula (12), R is a divalent or higher organic group having at least one polar group selected from a divalent or higher hydrocarbon group, or a polar group having oxygen such as an ether, epoxy, or ketone, a polar group having sulfur such as a thioether or thioketone, or a polar group having nitrogen such as a tertiary amino group or an imino group.

[0207] The divalent or higher valent hydrocarbon group is a saturated or unsaturated hydrocarbon group which may be linear, branched, or cyclic, and includes an alkylene group, an alkenylene group, a phenylene group, etc. Preferably, it is a hydrocarbon group having 1 to 20 carbon atoms. Examples include methylene, ethylene, butylene, cyclohexylene, 1,3-bis(methylene)-cyclohexane, 1,3-bis(ethylene)-cyclohexane, o-, m-, and p-phenylene, m- and p-xylene, and bis(phenylene)-methane.

[0208] In the formula (12), R ２４ , R ２７ is a hydrocarbon group having 1 to 10 carbon atoms, and R ２４ , R ２７ may be the same or different. ２５ , R ２８ is hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, and R ２５ , R ２８ may be the same or different. ２６ R is a hydrocarbon group having 1 to 10 carbon atoms or a structure of the following formula (13): ２４ , R ２５ , R ２６may be bonded to each other to form a cyclic structure. ２６ When R is a hydrocarbon group, it may be bonded to R to form a cyclic structure. ２６ In the formula (12), f is an integer of 1 or more, and g is 0 or an integer of 1 or more.

[0209]

[0210] In the formula (13), R ２９ , R ３０ is R in the formula (12). ２４ , R ２５ is defined similarly to R ２９ , R ３０ may be the same or different from each other.

[0211] The nitrogen atom-containing epoxy compound is preferably a nitrogen atom-containing epoxy compound having one or more diglycidylamino groups and one or more glycidoxy groups in the molecule.

[0212] Examples of nitrogen atom-containing epoxy compounds include, but are not limited to, N,N-diglycidyl-4-glycidoxyaniline, 1-N,N-diglycidylaminomethyl-4-glycidoxycyclohexane, 4-(4-glycidoxyphenyl)-(N,N-diglycidyl)aniline, 4-(4-glycidoxyphenoxy)-(N,N-diglycidyl)aniline, 4-(4-glycidoxybenzyl)-(N,N-diglycidyl)aniline, 4-(N,N'-diglycidyl-2-piperazinyl)-glycidoxybenzene, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-m-xylylenediamine. , 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, preferred are N,N-diglycidyl-4-glycidoxyaniline and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

[0213] Examples of imine compounds that are coupling modifiers having a nitrogen atom-containing group include, but are not limited to, N-butylpropan-2-imine, N-butyl-4-methylpentan-2-imine, N,N'-(propane-1,3-diyl)bis(4-methylpentan-2-imine), N,N'-(hexane-1,6-diyl)bis(4-methylpentan-2-imine), tris[2-(propan-2-ylideneamino)methyl]- )ethyl]amine, tris[2-(propan-2-ylideneamino)propyl]amine, N,N'-(1,4-phenylene)bis(4-methylpentan-2-imine), 1,1'-(1,4-phenylene)bis(N-propylethane-1-imine), N,N'-(propane-1,3-diyl)bis(1-phenylmethanimine), and N,N'-(hexane-1,6-diyl)bis(1-phenylmethanimine).

[0214] Examples of the nitrogen atom-containing alkoxysilane compound, which is a coupling modifier having a group containing a nitrogen atom, include, but are not limited to, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropylmethyldimethoxysilane, 3-diethylaminopropyltriethoxysilane, 3-morpholinopropyltrimethoxysilane, 3-piperidinopropyltriethoxysilane, 3-hexamethyleneiminopropylmethyldiethoxysilane, 3-(4-methyl-1-piperazino)propyltriethoxysilane, 3-(4-methyl-1-piperazino)propyltriethoxysilane, 3-(4-trimethylsilyl-1-piperazino)propyltrimethoxysilane, 1-[3-(triethoxysilyl)propyl]-3-methylhexahydropyrimidine, 3-(4-trimethylsilyl-1-piperazino)propyltriethoxysilane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane, 3-(3-trimethylsilyl-1-hexahydropyrimidinyl)propyltrimethoxysilane, 3-dimethylamino-2-(dimethylaminomethyl)propyltrimethoxysilane, bis(3-dimethoxymethylsilylpropyl)-N-methylamine, bis(3-trimethoxysilylpropyl)-N-methylamine, bis(3-triethoxysilylpropyl)methylamine, tris(trimethoxysilyl)amine, tris(3-trimethoxysilylpropyl)amine, N,N,N',N'-tetra(3-trimethoxysilylpropyl)ethylenediamine, 3-isocyanatopropyltrimethoxysilane, 3-cyanopropyltrimethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl) propyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, and 2,2-dimethoxy-8-(N,N-diethylamino)methyl-1,6-dioxa-2-silacyclooctane.

[0215] Preferred nitrogen atom-containing alkoxysilane compounds include, but are not limited to, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-tripropoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine ("N,N,N',N'-tetrakis(3-trimethoxysilylpropyl)" silylpropyl)-1,3-propanediamine), tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexamethylenediamine, pentakis(3-trimethoxysilylpropyl)-1,6-hexamethylenediamine 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-trimethoxysilylpropyl)silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]silane, 3-tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-trimethoxysilylpropane, 1-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 1-[3-(2 ,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexyl-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]ether, (3-trimethoxysilylpropyl)phosphate, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate, Bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)phosphate, 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-benzylidine Examples of such amines include 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, and 2-methoxy-2-methyl-1-(4-methoxybenzylideneaminoethyl)-1-aza-2-silacyclopentane.

[0216] Among coupling modifiers having a group containing a nitrogen atom, protected amine compounds in which active hydrogen is substituted with a protecting group include compounds having an unsaturated bond and a protected amine in the molecule. Examples of such compounds include, but are not limited to, 4,4'-vinylidenebis[N,N-bis(trimethylsilyl)aniline], 4,4'-vinylidenebis[N,N-bis(triethylsilyl)aniline], 4,4'-vinylidenebis[N,N-bis(t-butyldimethylsilyl)aniline], 4,4'-vinylidenebis[N-methyl-N-(trimethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N-(trimethylsilyl)aniline], 4,4'-vinylidenebis[N-methyl-N-(triethylsilyl)aniline], Examples thereof include 4,4'-vinylidenebis[N-ethyl-N-(triethylsilyl)aniline], 4,4'-vinylidenebis[N-methyl-N-(t-butyldimethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N-(t-butyldimethylsilyl)aniline], 1-[4-N,N-bis(trimethylsilyl)aminophenyl]-1-[4-N-methyl-N-(trimethylsilyl)aminophenyl]ethylene, and 1-[4-N,N-bis(trimethylsilyl)aminophenyl]-1-[4-N,N-dimethylaminophenyl]ethylene.

[0217] Among coupling modifiers having a group containing a nitrogen atom, examples of protected amine compounds in which active hydrogen is substituted with a protecting group include compounds having alkoxysilanes and protected amines in the molecule.Examples of such compounds include, but are not limited to, 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)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane, N,N-bis(triethylsilyl)aminopropyltriethoxysilane, N,N-bis(triethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(triethyl ... propylmethyldiethoxysilane, 3-(4-trimethylsilyl-1-piperazino)propyltriethoxysilane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane, 3-(3-trimethylsilyl-1-hexahydropyrimidinyl)propyltrimethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-Dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclohexane, 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(diethoxy ... 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, and N-ethylidene-3-(trimethoxysilyl)-1-propanamine.

[0218] Also, 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-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 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-phenanthren-4-yl)benzyl ...(triethoxysilyl)propan-1-amine, 1,1-(1,4-phenanthren-4-yl)benzylamine, N-naphthylidene-3-methyl(dimethoxysilyl)propan-1-amine, 1,1-(1,4-phenanthren-4-yl)benzylamine, N-naphthylidene-3-(triethoxysilyl)propan-1-amine, 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, and 2-methoxy-2-methyl-1-(methylisobutylideneaminoethyl)-1-aza-2-silacyclopentane.

[0219] In the coupling step, it is more preferable to use a combination of two or more coupling modifiers selected from the nitrogen-containing alkoxysilane compounds represented by any one of the following formulas (14) to (18). As such coupling modifiers, a coupling modifier having two or less alkoxysilyl groups and a coupling modifier having more than two alkoxysilyl groups can be used in combination.

[0220]

[0221] In formula (14), R ８ ~R １０ are hydrocarbon groups having 1 to 20 carbon atoms, which may contain unsaturated bonds, and may be the same or different. １１ , R １２ are aliphatic hydrocarbon groups having 1 to 6 carbon atoms, which may contain unsaturated bonds, and may be the same or different; R １３ is a hydrocarbon group having 1 to 20 carbon atoms which contains Si, O, or N and may be substituted with an organic group having no active hydrogen, and may have an unsaturated bond. d is an integer of 1 to 3.

[0222]

[0223] In formula (15), R １４ ~R １６ are hydrocarbon groups having 1 to 20 carbon atoms, which may contain unsaturated bonds, and may be the same or different. １７ , R １８ is a hydrocarbon group containing Si, O, or N and having 1 to 20 carbon atoms, which may be substituted with an organic group having no active hydrogen, and which may have an unsaturated bond. e is an integer of 1 to 3.

[0224]

[0225] In formula (16), R ３１ ~R ３４ each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, R ３５ represents an alkylene group having 1 to 10 carbon atoms, and R ３６represents an alkylene group having 1 to 20 carbon atoms, h represents an integer of 1 to 3, i represents an integer of 1 or 2, and (h+i) represents an integer of 4 or more. ３１ ~R ３４ are each independent of each other.

[0226]

[0227] In formula (17), R ３７ ~R ４２ each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, R ４３ ~R ４５ Each of m, n, and l independently represents an alkylene group having 1 to 20 carbon atoms, and (m+n+l) represents an integer of 4 or greater. ３７ ~R ４２ are each independent of each other.

[0228]

[0229] In formula (18), R ４６ ~R ４８ each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms; R ４９ ~R ５２ each independently represents an alkyl group having 1 to 20 carbon atoms; R ５３ and R ５６ each independently represents an alkylene group having 1 to 20 carbon atoms; R ５４ represents an alkylene group or an alkoxy group having 1 to 20 carbon atoms, and R ５５ represents an alkyl group or a trialkylsilyl group having 1 to 20 carbon atoms, o represents an integer of 1 to 3, and p represents 1 or 2. When a plurality of R ４６ ~R ５６ , o, and p are each independent and may be the same or different. q represents an integer of 0 to 6, r represents an integer of 0 to 6, s represents an integer of 0 to 6, and (q + r + s) 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 oxygen atoms, nitrogen atoms, silicon atoms, sulfur atoms, and phosphorus atoms and having no active hydrogen.

[0230] The coupling modifier represented by the formula (14) is not limited to the following, but examples thereof include 1-methyl-4-(3-(trimethoxysilyl)propyl)piperazine, 1-methyl-4-(3-(triethoxysilyl)propyl)piperazine, 1-ethyl-4-(3-(trimethoxysilyl)propyl)piperazine, 1-ethyl-4-(3-(triethoxysilyl)propyl)piperazine, 1-propyl-4-(3-(trimethoxysilyl)propyl)piperazine, 1-propyl-4-(3-(triethoxysilyl)propyl)piperazine, 1-butyl-4-(3-(trimethoxysilyl)propyl)piperazine, 1-butyl-4-(3-(triethoxysilyl)propyl)piperazine, 1-trimethylsilyl- 4-(3-(trimethoxysilyl)propyl)piperazine, 1-trimethylsilyl-4-(3-(triethoxysilyl)propyl)piperazine, 1-triethylsilyl-4-(3-(trimethoxysilyl)propyl)piperazine, 1-triethylsilyl-4-(3-(triethoxysilyl)propyl)piperazine, 1-(t-butyldimethylsilyl)-4-(3-(trimethoxysilyl)propyl)piperazine, 1-(t-butyldimethylsilyl)-4-(3-(triethoxysilyl)propyl)piperazine, 1-triisopropylsilyl-4-(3-(trimethoxysilyl)propyl)piperazine, 1-triisopropylsilyl-4-(3-(triethoxysilyl)propyl)piperazine, and the like.

[0231] Among these, from the viewpoint of enhancing the reactivity and interaction between the conjugated diene polymer and the inorganic filler such as silica, and from the viewpoint of enhancing processability, those in which d in the formula (14) is 3 are preferred. Specifically, 1-methyl-4-(3-(trimethoxysilyl)propyl)piperazine and 1-methyl-4-(3-(triethoxysilyl)propyl)piperazine are preferred.

[0232] The reaction temperature, reaction time, and the like when reacting the coupling modifier having a nitrogen atom-containing group represented by formula (14) with the polymerization active terminal are not particularly limited, but it is preferable to carry out the reaction at 0°C or higher and 120°C or lower for 30 seconds or longer.

[0233] The amount of the coupling modifier represented by the formula (14) to be added is determined based on the amount of alkoxy groups (OR ８ The total number of moles of the polymerization initiators is preferably in the range of 0.2 to 2.5 times the number of moles of the polymerization initiator added, more preferably 0.5 to 2.0 times, and even more preferably 1.0 to 2.0 times. From the viewpoint of setting the modification rate and molecular weight of the resulting conjugated diene polymer within more preferred ranges, it is preferably 0.2 times or more. Furthermore, from the viewpoint of preventing a decrease in processability due to an excessive increase in the branching degree, it is preferably 2.5 times or less.

[0234] More specifically, the amounts of the polymerization initiator and the coupling modifier represented by the formula (14) added may be adjusted so that the number of moles of the polymerization initiator is preferably 1.5 times or more, more preferably 1.7 times or more, the number of moles of the coupling modifier represented by the formula (14).

[0235] The coupling modifier represented by the formula (15) 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(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-(trimeth N-(1-methylpropylidene)-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)propane -1-amine, N-4-methylbenzylidene-3-methyl(diethoxysilyl)propan-1-amine, N-naphthylidene-3-(triethoxysilyl)propan-1-amine, N-naphthylidene-3-(trimethoxysilyl)propan-1-amine, N-naphthylidene-3-methyl(dimethoxysilyl)propan-1-amine, 1,1-(1,4-phenylene)bis(N-(3(triethoxysilyl)propyl)methanamine), 1,1-(1,4-phenylene)bis(N-(3(trimethoxysilyl)propyl)methanamine), 1,1-(1,4-phenylene)bis(N-(3-methyl(dimethoxysilyl)propyl)methanamine), 1,1-(1,4-phenylene)bis(N-(3-methyl(diethoxysilyl)propyl)methanamine), 2-methoxy-2-methyl-1-(benzylideneaminoethyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-1-(p-methoxybenzylideneaminoethyl)-1-aza-2-silacyclopentane, 2-ethoxy-2-methyl-1-(benzylideneaminoethyl)-1-aza-2-silacyclopentane, and 2-methoxy-2-methyl-1-(methylisobutylideneaminoethyl)-1-aza-2-silacyclopentane.

[0236] The reaction temperature, reaction time, and the like when reacting the coupling modifier having a nitrogen atom-containing group represented by formula (15) with the polymerization active terminal are not particularly limited, but it is preferable to react at 0°C or higher and 120°C or lower for 30 seconds or longer.

[0237] The amount of the coupling modifier represented by the formula (15) to be added is determined based on the amount of alkoxy groups (OR １４ The total number of moles of the polymerization initiators is preferably in the range of 0.2 to 2.5 times the number of moles of the polymerization initiator added, more preferably 0.5 to 2.0 times, and even more preferably 1.0 to 2.0 times. From the viewpoint of setting the modification rate and molecular weight of the resulting conjugated diene polymer within more preferred ranges, it is preferably 0.2 times or more. Furthermore, from the viewpoint of preventing a decrease in processability due to an excessive increase in the branching degree, it is preferably 2.5 times or less.

[0238] More specifically, the amounts of the polymerization initiator and the coupling modifier represented by the formula (15) added may be adjusted so that the number of moles of the polymerization initiator is preferably 1.5 times or more, more preferably 1.7 times or more, the number of moles of the coupling modifier represented by the formula (15).

[0239] Examples of the coupling modifier having a nitrogen atom-containing group represented by the formula (16) include, but are not limited to, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacycloheptane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacycloheptane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacycloheptane, 2,2-dimethoxy-1-(5-trimethoxysilylpropyl)-1-aza-2-silacyclohexane ... Examples thereof include aza-2-silacyclopentane, 2,2-diethoxy-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy,2-methyl-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-ethoxy,2-ethyl-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy,2-methyl-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, and 2-ethoxy,2-ethyl-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane.

[0240] Among these, from the viewpoints of reactivity and interaction between the functional group of the coupling modifier having a group containing a nitrogen atom and an inorganic filler such as silica, as well as processability, those in which i is 2 and h is 3 in the formula (16) 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.

[0241] In the coupling step using the coupling modifier represented by formula (16), the reaction temperature and reaction time are not particularly limited, but the reaction is preferably carried out at a temperature of 0°C or higher and 120°C or lower, and for 30 seconds or longer.

[0242] The amount of the coupling modifier represented by formula (16) added is preferably in a range such that the total number of moles of alkoxy groups bonded to silyl groups in the compound represented by formula (16) is 0.2 to 2.5 times the number of moles of the polymerization initiator added, more preferably 0.5 to 2.0 times, and even more preferably 1.0 to 2.0 times. From the viewpoint of achieving more preferred ranges for the modification rate, molecular weight, and branched structure of the resulting conjugated diene polymer, the amount is preferably 0.2 times or more. Furthermore, from the viewpoint of preventing a decrease in processability due to an excessive increase in branching degree, the amount is preferably 2.5 times or less.

[0243] More specifically, the amounts of the polymerization initiator and the coupling modifier represented by the formula (16) added may be adjusted so that the number of moles of the polymerization initiator is preferably 3.0 times or more, more preferably 4.0 times or more, relative to the number of moles of the coupling modifier represented by the formula (16).

[0244] Examples of the modifying agent having a group containing a nitrogen atom represented by formula (17) include, but are not limited to, tris(3-trimethoxysilylpropyl)amine, tris(3-methyldimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-methyldiethoxysilylpropyl)amine, tris(trimethoxysilylmethyl)amine, tris(2-trimethoxysilylethyl)amine, and tris(4-trimethoxysilylbutyl)amine.

[0245] Among these, from the viewpoints of reactivity and interaction between the functional group of the modifier and an inorganic filler such as silica, as well as processability, it is preferable that n, m, and l all represent 3 in the formula (17). Preferred specific examples include tris(3-trimethoxysilylpropyl)amine and tris(3-triethoxysilylpropyl)amine.

[0246] The reaction temperature, reaction time, and the like when reacting the modifying agent having a nitrogen atom-containing group represented by the formula (17) with the polymerization active terminal are not particularly limited, but it is preferable to react at 0°C or higher and 120°C or lower for 30 seconds or longer.

[0247] The total number of moles of alkoxy groups bonded to silyl groups in the coupling modifier represented by formula (17) is preferably in the range of 0.2 to 2.0 times, more preferably 0.5 to 2.0 times, and even more preferably 0.6 to 1.6 times the number of moles of lithium constituting the polymerization initiator. From the viewpoint of obtaining a sufficient modification rate, molecular weight, and branched structure in the conjugated diene polymer, it is preferably 0.2 times or more, and from the viewpoint of the cost of the coupling modifier as well as the fact that it is preferable to couple polymer terminals together to obtain a branched polymer component for improving processability, it is preferably 2.0 times or less.

[0248] 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.

[0249] In the formula (18), A is preferably represented by any one of the following general formulae (i) to (iv).

[0250]

[0251] In the formula (i), B １ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and t represents an integer of 1 to 10. １ are each independent of each other.

[0252]

[0253] In the formula (ii), B ２ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, B ３ represents an alkyl group having 1 to 20 carbon atoms, and t represents an integer of 1 to 10. When a plurality of B ２ and B ３ are each independent of each other.

[0254]

[0255] In the formula (iii), B ４ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and t represents an integer of 1 to 10. ４ are each independent of each other.

[0256]

[0257] In the formula (iv), B ５ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and t represents an integer of 1 to 10. ５ are each independent of each other.

[0258] In the formula (18), when A is represented by the formula (i), examples of the coupling modifier having a group containing a nitrogen atom 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]amine, tris(3-ethoxysilylpropyl)amine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]amine, bis[3-(2,2 -diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)amine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-propanediamine.

[0259] Further, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3- Propanediamine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-triethoxysilylpropyl) )-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-1,3-propanediamine, tetrakis[3-(2,2-di ethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisamino Methylcyclohexane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane.

[0260] Further, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexan silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-triethoxysilylpropyl)-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-triethoxysilylpropyl)-bis[3- (2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-1,3-propanediamine, tetrakis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]- 1,3-bisaminomethylcyclohexane, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexamethylenediamine, and pentakis(3-trimethoxysilylpropyl)-diethylenetriamine.

[0261] In the formula (18), when A is represented by the formula (ii), examples of the coupling modifier having a group containing a nitrogen atom 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, N1,N1'-(propane-1,3-diyl)bis(N1-methyl-N3,N3-bis(3-(trimethoxysilyl)propyl)-1,3-propanediamine), and N1-(3-(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N1-methyl-N3-(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N3-(3-(trimethoxysilyl)propyl)-1,3-propanediamine.

[0262] In the formula (18), when A is represented by the formula (iii), examples of the coupling modifier having a group containing a nitrogen atom 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-trimethoxysilylpropyl)silane, silane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, (3-trimethoxysilyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, cyclopentane)propyl]silane, bis[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1 [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.

[0263] In the formula (18), when A is represented by formula (iv), examples of the modifying agent having a group containing a nitrogen atom 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.

[0264] In the formula (18), A is preferably represented by formula (i) or formula (ii), and s is 0.

[0265] Coupling modifiers having such a nitrogen atom-containing group tend to be easily available and also tend to provide better abrasion resistance and low hysteresis loss when the conjugated diene polymer is vulcanized. Examples of coupling modifiers having such a nitrogen atom-containing group include, but are not limited to, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis[3-(2,2-di 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.

[0266] In the formula (18), A is more preferably represented by formula (i) or formula (ii), s represents 0, and in formula (i) or formula (ii), t represents an integer of 2 to 10.

[0267] This tends to result in better abrasion resistance and low hysteresis loss performance when vulcanized.

[0268] Examples of coupling modifiers having a group containing a nitrogen atom include, but are not limited to, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, and N １ -(3-(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N １ -methyl-N ３ -(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N ３ -(3-(trimethoxysilyl)propyl)-1,3-propanediamine, and the like.

[0269] The amount of the compound represented by formula (18) added as a coupling modifier having a nitrogen atom-containing group can be adjusted so that the number of moles of the polymerization initiator and the number of moles of the coupling modifier react in a desired stoichiometric ratio, which tends to achieve a desired star-shaped highly branched structure.

[0270] Specifically, the number of moles of the polymerization initiator is preferably 5.0 times or more, more preferably 6.0 times or more, the number of moles of the coupling modifier.

[0271] In this case, in the formula (18), the number of functional groups of the coupling modifier ((o−1)×q+p×r+s) is preferably an integer of 5 to 10, and more preferably an integer of 6 to 10.

[0272] The method for producing the conjugated diene polymer (A) or the conjugated diene polymer (B) may include a condensation reaction step of causing a condensation reaction by adding a condensation promoter after the step of adding a coupling modifier and / or before the step of adding a coupling modifier.

[0273] The method for producing the conjugated diene polymer (A) or the conjugated diene polymer (B) may further include a modification step using a modifier other than the above-mentioned coupling modifier.

[0274] In the method for producing the conjugated diene polymer (A) or the conjugated diene polymer (B), two types of coupling modifiers may be added in the step of adding a coupling modifier, or three or more types may be added. When two types of coupling modifiers are added, the combination of coupling modifiers may be a combination of coupling modifiers with different numbers of functional groups. When three or more types of coupling modifiers are added, the combination may include a combination of coupling modifiers with different numbers of functional groups.

[0275] An example of a combination of two types of coupling modifiers with different numbers of functional groups is a combination of a bifunctional or less coupling modifier and a trifunctional or more coupling modifier. A long-stemmed fork polymer is formed by binding a fork-shaped portion [A] and a linear polymer to one end of a bifunctional coupling modifier, and a star-shaped branched structure is formed by a trifunctional coupling modifier. Therefore, a combination of coupling modifiers that is easy to design may be a combination of a bifunctional and a trifunctional or more coupling modifier, taking into account the number of active terminals after the branching agent reacts, so that the long-stemmed fork-shaped portion [A] and the star-shaped portion are in the desired ratio. Multiple types of coupling modifiers may be added simultaneously, or may or may not be mixed in advance.

[0276] Specific examples of coupling modifiers having two or less functionalities include coupling modifiers having the structures of the formula (14) and formula (15), and specific examples of coupling modifiers having three or more functionalities include coupling modifiers having the structures of the formula (16), formula (17), and formula (18), but are not particularly limited thereto.

[0277] The method for producing a conjugated diene polymer of the present embodiment may include a hydrogenation step of hydrogenating the conjugated diene portion. The method for hydrogenating the conjugated diene portion is not particularly limited, and known methods can be used.

[0278] A preferred hydrogenation step is a method in which gaseous hydrogen is blown into a polymer solution in the presence of a catalyst to hydrogenate the conjugated diene portion. The catalyst used is not particularly limited, but examples thereof include heterogeneous catalysts such as catalysts in which a noble metal is supported on a porous inorganic material; and homogeneous catalysts such as catalysts in which a salt of nickel, cobalt, or the like is solubilized and reacted with organoaluminum, and catalysts using metallocenes such as titanocene. Among these, titanocene catalysts are preferred from the viewpoint of being able to select milder hydrogenation conditions. In addition, a method in which a noble metal supported catalyst is used is an example of a method for hydrogenating an aromatic group.

[0279] Furthermore, a hydrogenation step that does not use gaseous hydrogen includes a method of contacting a polymer solution with a hydrogenation catalyst. Examples of such hydrogenation catalysts include, but are not limited to, (1) supported heterogeneous hydrogenation catalysts in which a metal such as Ni, Pt, Pd, or Ru is supported on carbon, silica, alumina, diatomaceous earth, or the like, (2) so-called Ziegler-type hydrogenation catalysts that use a transition metal salt such as an organic acid salt or an acetylacetone salt of Ni, Co, Fe, Cr, or the like and a reducing agent such as organoaluminum, and (3) so-called organometallic complexes such as organometallic compounds of Ti, Ru, Rh, Zr, or the like. Furthermore, other hydrogenation catalysts are not particularly limited, and examples thereof include known hydrogenation catalysts described in JP-B Nos. 42-8704, 43-6636, 63-4841, 1988-37970, 1-53851, 2-9041, and JP-A No. 8-109219. A preferred hydrogenation catalyst is a reaction mixture of a titanocene compound and a reducing organometallic compound.

[0280] In the method for producing a conjugated diene polymer of the present embodiment, after the coupling step using a coupling modifier, a stabilizer such as a deactivator and / or a neutralizer may be added to the polymer solution as needed.

[0281] Examples of the quenching agent include, but are not limited to, water and alcohols such as methanol, ethanol, and isopropanol.

[0282] Examples of the neutralizing agent include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a mixture of highly branched carboxylic acids having 9 to 11 carbon atoms and containing 10 carbon atoms as the main component), aqueous solutions of inorganic acids, and carbon dioxide gas.

[0283] As the stabilizer, it is preferable to add a rubber stabilizer from the viewpoint of preventing gel formation after polymerization and improving stability during processing. Known rubber stabilizers can be used, and examples thereof include, but are not limited to, antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (BHT), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol)propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol.

[0284] <Mixing Step> In the method for producing a modified conjugated diene polymer mixture of this embodiment, as described above, after obtaining polymerization solutions of the modified conjugated diene polymer (A) and the modified conjugated diene polymer (B), these are solution-mixed and the solvent is removed to obtain a modified conjugated diene polymer. Regarding the mixing step, it is preferable to provide storage tanks downstream of the reaction tank for the modified conjugated diene polymer (A) and the reaction tank for the modified conjugated diene polymer (B) to store the polymerization solution distilled from each reaction tank. By providing storage tanks for each polymer, it is possible to adjust the flow rate after the modification step and before the mixing step, making it easy to fine-tune the mixing ratio of the polymer solutions, and they can be stored in tanks separate from the reaction tanks. It is more preferable that the capacity of the storage tanks be larger than that of the reaction tanks.

[0285] The mixing means in this embodiment may be, but is not limited to, a tank equipped with a rotary agitator, or a pipe equipped with a rotary agitator or a static mixer. From the viewpoint of agitation capacity, it is preferable to use a tank equipped with a rotary agitator, and from the viewpoint of production efficiency, it is preferable to use a pipe equipped with a rotary agitator or a static mixer.

[0286] The temperature in the mixing step is not particularly limited, but is preferably from 0°C to 120°C, and more preferably from 50°C to 100°C. This is because a higher temperature reduces the viscosity of the polymerization solution, facilitating mixing. In a preferred embodiment, the solution distilled from the top of the polymerization reaction tank is temporarily stored and then mixed. If the storage time is short and the temperature of the solution is maintained even after distillation from the polymerization tank, heating is not necessary in the mixing step. However, if the storage time is long or the ambient temperature is low, or under conditions that make the solution temperature likely to decrease, the storage tank, mixing tank, piping, etc. may be kept warm or heated.

[0287] The mixing mass ratio of the conjugated diene polymer (A) to the conjugated diene polymer (B) in the mixing step ((A) / (B)) is preferably 10 / 90 to 50 / 50, more preferably 15 / 85 to 45 / 55, even more preferably 20 / 80 to 40 / 60, still more preferably 25 / 75 to 40 / 60, and particularly preferably 30 / 70 to 60 / 40. When the ratio is within this range, the balance between the abrasion resistance and the processability of the vulcanized product tends to be excellent. Note that the above ratio is the mass ratio of the modified conjugated diene polymers. When the concentrations of the polymerization solutions of the modified conjugated diene polymer (A) and the modified conjugated diene polymer (B) are the same, this ratio may be used as the mass ratio of the solutions. However, there are also cases where the concentrations of these solutions are different. This is because, when producing a polymer with a low molecular weight, adding a large amount of polymerization initiator tends to increase the heat of reaction, and therefore the concentration of the solution may be reduced to maintain the polymerization temperature. In this case, it is preferable to adjust the mixing ratio so as to obtain a preferable polymer mass ratio, taking into consideration the solution concentration.

[0288] The solvent removal step can be carried out by known methods such as drying, devolatilization, etc. Examples of such methods include a method in which the solvent is separated by steam stripping or the like, and then the polymer is filtered, and then dehydrated and dried to obtain a polymer, a method in which the polymer is concentrated in a flashing tank and then devolatilized using a vent extruder or the like, and a method in which the polymer is directly devolatilized using a drum dryer or the like.

[0289] [Rubber Composition] The rubber composition of this embodiment contains a rubber component containing the conjugated diene polymer of this embodiment. When the conjugated diene polymer of this embodiment is compounded into a tire, the oil contained in the bale molded product will inevitably be contained in the tire. However, if the amount of oil extension is reduced, the oil contained in the tire will also be reduced, which has the advantage of increasing the degree of freedom in tire composition design. The conjugated diene polymer of this embodiment and its sheet-like or block-like molded product (also referred to as a bale) may contain a softener component, as described below. From the viewpoint of improving the degree of freedom in compounding design during rubber composition production, the molded product (bale) preferably contains 2 parts by mass or less of a rubber softener per 100 parts by mass of the conjugated diene polymer, more preferably 1.5 parts by mass or less, even more preferably 1 part by mass or less, even more preferably less than 1 part by mass, and most preferably no softener is added.

[0290] The rubber softener is not particularly limited, but examples thereof include extender oil, liquid rubber, and resin.

[0291] It is preferable that the conjugated diene polymer and its sheet- or block-shaped molded product be provided without adding a rubber softener, from the viewpoint of improving the degree of freedom in compounding design when producing a rubber composition using the molded product. Generally, there is an upper limit to the total amount of rubber softener in the entire rubber composition. However, if a rubber softener is added to a sheet- or block-shaped molded product of a conjugated diene polymer, the rubber composition produced by compounding the molded product will also contain the rubber material softener. This reduces the total amount of rubber softener in the entire rubber composition and limits the degree of freedom in the type and amount of rubber softener that needs to be compounded when producing the rubber composition. From the viewpoint of improving the degree of freedom in selecting the type and amount of rubber softener to be compounded according to the performance desired for the rubber composition, it is preferable to reduce the amount of softener added to a sheet- or block-shaped molded product of a conjugated diene polymer.

[0292] Although not particularly limited, for example, by reducing the amount of extender oil added to the conjugated diene-based polymer of the present embodiment and its sheet- or block-shaped molded product, it becomes possible to compound a larger amount of resin such as extender oil when producing a rubber composition using them, which is preferable from the viewpoint of further improving the breaking strength of the rubber composition and its vulcanizate.

[0293] The rubber composition using the conjugated diene-based polymer of the present embodiment and its sheet- or block-shaped molded product may further contain a rubber stabilizer from the viewpoint of suppressing gel formation and improving stability during processing.

[0294] The rubber stabilizer is not limited to the following and known stabilizers can be used, but examples thereof include 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.

[0295] The veil of this embodiment contains 100 parts by mass of the modified conjugated diene-based polymer of this embodiment and less than 1 part by mass of a softener component. The rubber composition of this embodiment contains 100 parts by mass of a rubber component and 5.0 parts by mass or more and 150 parts by mass or less of a filler, and the rubber component contains 10 parts by mass or more of the modified conjugated diene-based polymer of this embodiment or the veil of this embodiment per 100 parts by mass of the total amount of the rubber component.

[0296] The rubber composition of this embodiment contains 100 parts by mass of a rubber component and 5.0 parts by mass or more and 150 parts by mass or less of a filler. The rubber component preferably contains 10 parts by mass or more of the conjugated diene-based polymer of this embodiment per 100 parts by mass of the total rubber component. By dispersing a filler in the rubber component containing the conjugated diene-based polymer of this embodiment, a rubber composition can be obtained that has even better processability during vulcanization and that produces a vulcanizate with even better low hysteresis loss, fracture properties, and abrasion resistance. Furthermore, by containing the conjugated diene-based polymer of this embodiment in a predetermined proportion in the rubber component, fuel economy performance, processability, and abrasion resistance are further improved.

[0297] Examples of fillers include, but are not limited to, silica-based inorganic fillers, carbon black, metal oxides, and metal hydroxides. Among these, silica-based inorganic fillers are preferred. In particular, when the rubber composition of this embodiment is used for vulcanized rubber applications such as tires, automobile parts such as anti-vibration rubber, and shoes, it is particularly preferred that the rubber composition contain a silica-based inorganic filler. Such fillers may be used alone or in combination of two or more.

[0298] The silica-based inorganic filler is not particularly limited, and known fillers can be used. ２ or Si ３ Solid particles containing Al as a constituent unit are preferred, and SiO ２ or Si ３ Solid particles containing Al as the main component of the structural units are more preferred. Here, the main component refers to a component contained in the silica-based inorganic filler in an amount of more than 50% by mass, preferably 70% by mass or more, and more preferably 80% by mass or more.

[0299] 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. Surface-hydrophobized silica-based inorganic fillers and mixtures of silica-based inorganic fillers with non-silica-based inorganic fillers may also be used. Among these, silica or glass fiber is preferred, and silica is more preferred, from the viewpoint of further improving the strength and abrasion resistance of the rubber composition. Examples of silica include, but are not limited to, dry silica, wet silica, and synthetic silicate silica. Among these silicas, wet silica is preferred from the viewpoint of further improving the breaking strength of the rubber composition.

[0300] From the viewpoint of more reliably obtaining a rubber composition having practically good abrasion resistance and breaking strength, the nitrogen adsorption specific surface area of ​​the silica-based inorganic filler determined by the BET adsorption method is 100 m ２ / g or more 300m ２ / g or less, and ２ / g or more 250m ２ / g or less. If necessary, a relatively small specific surface area (for example, a specific surface area of ​​200 m ２ / g) silica-based inorganic filler and a relatively large specific surface area (e.g., 200 m ２ In this embodiment, a silica-based inorganic filler having a relatively large specific surface area (for example, 200 m ２ When a silica-based inorganic filler (wt. / g or more) is used, the conjugated diene polymer further improves the dispersibility of the silica, and as a result, the resulting rubber composition tends to have even better abrasion resistance, fracture strength, and low hysteresis loss.

[0301] Examples of carbon black include, but are not limited to, carbon blacks of various classes such as SRF, FEF, HAF, ISAF, and SAF. Among these, carbon blacks having a nitrogen adsorption specific surface area of ​​50 m or more as determined by the BET adsorption method are preferred. ２ Carbon black having a carbon absorption of 80 mL / 100 g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100 g or less is preferred.

[0302] The metal oxides include those represented by the chemical formula M ｘ O ｙ (M represents a metal atom, and x and y each independently represent an integer of 1 to 6.) As long as the solid particles have as a main component a structural unit, there is no particular limitation, but examples thereof include alumina, titanium oxide, magnesium oxide, and zinc oxide.

[0303] Examples of metal hydroxides include, but are not limited to, aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0304] The content of the filler in the rubber composition of this embodiment is 5.0 parts by mass to 150 parts by mass, preferably 20 parts by mass to 100 parts by mass, and more preferably 30 parts by mass to 90 parts by mass, per 100 parts by mass of the rubber component. When the filler content is within the above range, the rubber composition tends to have better processability during vulcanization, and the vulcanizate tends to have better low hysteresis loss, fracture properties, and abrasion resistance.

[0305] From the viewpoint of reliably imparting the performance required for applications such as tires, such as dry grip performance and conductivity, the rubber composition of this embodiment preferably contains 0.5 parts by mass or more and 100 parts by mass or less of carbon black relative to 100 parts by mass of the rubber component containing the conjugated diene polymer. From the same viewpoint, the rubber composition preferably contains 3.0 parts by mass or more and 100 parts by mass or less of carbon black, and even more preferably 5.0 parts by mass or more and 50 parts by mass or less, relative to 100 parts by mass of the rubber component containing the conjugated diene polymer.

[0306] The rubber composition of this embodiment may further contain a silane coupling agent. By including a silane coupling agent in the rubber composition, the interaction between the rubber component and the filler can be further improved. Examples of silane coupling agents include, but are not limited to, compounds having a sulfur bond moiety and an alkoxysilyl group or silanol group moiety in one molecule. Examples of such compounds include, but are not limited to, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide.

[0307] In the rubber composition of this 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 filler. When the content of the silane coupling agent is within the above range, the interaction between the rubber component and the filler tends to be further improved.

[0308] The rubber composition of the present embodiment may contain, as a rubber component, a rubbery polymer other than the conjugated diene polymer of the present embodiment (hereinafter simply referred to as a "rubbery polymer"). The conjugated diene polymer of the present embodiment and the rubbery polymer are collectively referred to as the "rubber component."

[0309] Examples of rubbery polymers include, but are not limited to, conjugated diene polymers and hydrogenated products thereof, random copolymers of conjugated diene compounds and vinyl aromatic compounds and hydrogenated products thereof, block copolymers of conjugated diene compounds and vinyl aromatic compounds and hydrogenated products thereof, non-diene polymers, and natural rubber.

[0310] Examples of rubber-like polymers include, but are not limited to, styrene-based elastomers such as butadiene rubber and hydrogenated products thereof, isoprene rubber and hydrogenated products thereof, styrene-butadiene rubber and hydrogenated products thereof, styrene-butadiene block copolymers and hydrogenated products thereof, and styrene-isoprene block copolymers and hydrogenated products thereof; and acrylonitrile-butadiene rubber and hydrogenated products thereof.

[0311] 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.

[0312] Examples of natural rubber include, but are not limited to, smoked sheets RSS3 to 5, SMR, and epoxidized natural rubber.

[0313] The rubbery polymer may be a modified rubber to which a polar functional group such as a hydroxyl group, an amino group, etc. When the rubber composition of the present embodiment is used for a tire, the rubbery polymer is preferably at least one selected from the group consisting of butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber.

[0314] From the viewpoint of the balance between the abrasion resistance, breaking strength, low hysteresis loss, and processability of the rubber composition, the weight average molecular weight of the rubber polymer is preferably 2,000 to 2,000,000, and more preferably 5,000 to 1,500,000. Furthermore, a low molecular weight rubber polymer, so-called liquid rubber, can also be used as the rubber polymer. These rubber polymers may be used alone or in combination of two or more.

[0315] When the rubber composition of this embodiment contains a conjugated diene polymer and a rubbery polymer, the content ratio (mass ratio) of the conjugated diene polymer to the rubbery polymer (conjugated diene polymer / rubbery polymer) is preferably 10 / 90 to 100 / 0, more preferably 20 / 80 to 90 / 10, and even more preferably 30 / 70 to 80 / 20. That is, the rubber component contains preferably 10 to 100 parts by mass, more preferably 20 to 90 parts by mass, and even more preferably 30 to 80 parts by mass of the conjugated diene polymer of this embodiment per 100 parts by mass of the total rubber component. When the proportion of the conjugated diene polymer in the rubber component is within the above range, the vulcanizate of the rubber composition tends to have even better wear resistance and low hysteresis loss.

[0316] The rubber composition of this embodiment contains a softener component (e.g., a rubber softener) in addition to the rubber component, from the viewpoint of further improving its processability. The softener component is not particularly limited, but examples thereof include liquid rubber, resin, and extender oil. The liquid rubber is not particularly limited, but examples thereof include liquid polybutadiene and liquid styrene-butadiene rubber. When a liquid rubber is used as the softener component, in addition to the above-mentioned effects, the glass transition temperature of the conjugated diene polymer composition can be lowered, which tends to further improve the abrasion resistance, low hysteresis loss, and low-temperature properties of the vulcanizate. Examples of resins include, but are not limited to, aromatic petroleum resins, coumarone-indene resins, terpene resins, rosin derivatives (including tung oil resins), tall oil, tall oil derivatives, rosin ester resins, natural and synthetic terpene resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, mixed aliphatic-aromatic hydrocarbon resins, coumarin-indene resins, phenolic resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, monoolefin oligomers, diolefin oligomers, hydrogenated aromatic hydrocarbon resins, cyclic aliphatic hydrocarbon resins, hydrogenated hydrocarbon resins, hydrocarbon resins, hydrogenated tung oil resins, hydrogenated oil resins, and esters of hydrogenated oil resins with monofunctional or polyfunctional alcohols. These resins may be used alone or in combination of two or more. Furthermore, when these resins are hydrogenated, all of the unsaturated groups may be hydrogenated, or some may remain.

[0317] When a resin is used as a softener component, in addition to the above-mentioned effects, the breaking strength of the vulcanizate of the conjugated diene polymer composition tends to be further improved. From the viewpoint of further improving the breaking strength of the vulcanizate, it is preferable to add a resin as a softener component in addition to the rubber component to the rubber composition of this embodiment.

[0318] In order to further improve the processability of the rubber composition of this embodiment, a softener component may be added in addition to the rubber component, and mineral oil or a liquid or low-molecular-weight synthetic softener is preferred.

[0319] Examples of extender oils include aromatic oils, naphthenic oils, and paraffin oils. Among these, from the viewpoint of environmental safety, preventing oil bleeding, and improving wet grip performance, aromatic substitute oils having a polycyclic aromatic (PCA) content of 3% by mass or less according to the IP346 method are preferred. The aromatic substitute oil is not particularly limited, but examples 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).

[0320] Mineral oil-based rubber softeners, also known as process oils or extender oils, are used to soften rubber, increase its volume, and improve its processability. These softeners are mixtures of aromatic rings, naphthenic rings, and paraffin chains. Among these, softeners in which the number of carbon atoms belonging to paraffin chains is 50% or more of the total carbon atoms are called paraffinic, those in which the number of carbon atoms belonging to naphthenic rings is 30% to 45% of the total carbon atoms are called naphthenic, and those in which the number of carbon atoms belonging to aromatic carbons is more than 30% of the total carbon atoms are called aromatic. The rubber composition of this embodiment preferably contains a rubber softener with an appropriate aromatic content. The inclusion of such a rubber softener further improves compatibility with conjugated diene polymers.

[0321] The content of the softener component in the rubber composition of this embodiment is represented by the total amount of the softener component added in advance to the conjugated diene-based polymer of this embodiment and the above-mentioned rubber-like polymer, and the softener component added when preparing the rubber composition.

[0322] In the rubber composition of this embodiment, the content of the softener component 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 having the content of the rubber softener be 100 parts by mass or less per 100 parts by mass of the rubber component, bleeding out can be suppressed, and stickiness of the surface of the rubber composition can be further suppressed.

[0323] Regarding the method for producing the rubber composition of this embodiment, the method for mixing the conjugated diene polymer of this embodiment, a rubbery polymer other than the conjugated diene polymer of this embodiment, a filler, and optionally, a silane coupling agent and a rubber softener, etc., is not particularly limited. Examples include melt-kneading methods 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 methods in which the components are dissolved and mixed and then the solvent is removed by heating. Among these, melt-kneading methods using a roll, a Banbury mixer, a kneader, or an extruder are preferred from the viewpoints of productivity and good kneading ability. Furthermore, the rubber component, the filler, the silane coupling agent, and the additives may be kneaded all at once, or may be mixed in multiple batches.

[0324] The rubber composition of the present embodiment may be vulcanized with a vulcanizing agent to form a vulcanizate. Examples of vulcanizing agents include, but are not limited to, radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds. Examples of sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, and polymeric polysulfur compounds.

[0325] In the rubber composition of this embodiment, the content of the vulcanizing agent 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. A conventionally known method can be used as the vulcanization method. The vulcanization temperature is preferably 120°C or more and 200°C or less, and more preferably 140°C or more and 180°C or less.

[0326] When vulcanizing the rubber composition, a vulcanization accelerator and / or vulcanization aid may be used as necessary. As the vulcanization accelerator, conventionally known materials can be used, and examples thereof include, but are not limited to, sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators. Furthermore, examples of the vulcanization aid include, but are not limited to, zinc oxide and stearic acid. The content of each of the vulcanization accelerator and vulcanization aid 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.

[0327] The rubber composition of this embodiment may contain various additives other than those described above, such as softeners and fillers, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants, as long as the effects of this embodiment are not impaired. Known softeners can be used as softeners. Specific examples of fillers include, but are not limited to, calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. Known materials can be used as heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants.

[0328] [Tire] The tire of the present embodiment contains the rubber composition of the present embodiment described above. Examples of the tire of the present embodiment include, but are not limited to, various types of tires such as fuel-efficient tires, all-season tires, high-performance tires, and studless tires, and the rubber composition of the present embodiment can be suitably used in each part of the tire such as the tread, carcass, sidewall, and bead portion.

[0329] In addition, the numerical ranges described above as preferred ranges, etc., may be replaced with numerical ranges that arbitrarily combine the values ​​described as upper limits and the values ​​described as lower limits, unless otherwise specified.

[0330] The present embodiment will be described in more detail below with reference to specific examples and comparative examples, but the present invention is not limited to these examples and comparative examples. Various physical properties in the examples and comparative examples were measured by the methods shown below.

[0331] Hereinafter, a polymer before modification with a coupling modifier will be referred to as an “unmodified conjugated diene polymer,” and a polymer after modification with a coupling modifier will be referred to as a “modified conjugated diene polymer.” Furthermore, polymers before and after modification with a coupling modifier may be collectively referred to as “conjugated diene polymer.”

[0332] (Property 1) Molecular weight distribution curve, average molecular weight, and molecular weight distribution measured by gel permeation chromatography (GPC) Unmodified conjugated diene polymers and modified conjugated diene polymers were used as samples. GPC measurements were performed using a GPC measurement device (manufactured by Tosoh Corporation under the trade name "HLC-8320GPC") connected to two columns packed with polystyrene gel, and a refractive index (RI) detector (manufactured by Tosoh Corporation under the trade name "HLC8020"). The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were determined based on a calibration curve obtained using standard polystyrene. A 2 wt % triethylamine-THF (tetrahydrofuran) solution was used as the eluent. Two columns, manufactured by Tosoh Corporation under the trade name "TSKgel GMHHR-H(S)", were connected, and a Tosoh Corporation trade name "TSKguard column Super MP(HZ)-H" was connected in front of them as a guard column. 10 mg of the sample to be measured was dissolved in 10 mL of THF to prepare a measurement solution, and 10 μL of the measurement solution was injected into a GPC measurement device and measured at an oven temperature of 40 ° C. and a flow rate of 1.0 mL / min. The shape of the molecular weight distribution curve obtained as a result of the measurement and the presence or absence of a shoulder on the higher molecular weight side from the peak top were confirmed. The measurement results were also used as the average molecular weight of each sample.

[0333] (Physical Property 2) Polymer Mooney Viscosity Using an unmodified conjugated diene polymer and a modified conjugated diene polymer as samples, the Mooney viscosity was measured using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) with an L-shaped rotor in accordance with ISO 289. The measurement temperature was 110°C when an unmodified conjugated diene polymer was used as the sample, and 100°C when a modified conjugated diene polymer was used as the sample. After preheating the sample at the test temperature for 1 minute, the rotor was rotated at 2 rpm, and the torque was measured after 4 minutes to determine the Mooney viscosity (ML （１＋４） ) was measured.

[0334] (Physical Property 3) Mooney Relaxation Rate Using an unmodified conjugated diene polymer and a modified conjugated diene polymer as samples, the Mooney viscosity was measured using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) with an L-shaped rotor in accordance with ISO 289. The rotation of the rotor was then immediately stopped, and the torque was recorded in Mooney units every 0.1 seconds from 1.6 seconds to 5 seconds after the rotor was stopped. The slope of the straight line obtained by plotting the torque versus time (seconds) logarithmically was determined, and the absolute value was taken as the Mooney relaxation rate (MSR). The measurement temperature was 110°C when an unmodified conjugated diene polymer was used as the sample, and 100°C when a modified conjugated diene polymer was used as the sample.

[0335] (Physical Property 4) Absolute Molecular Weight and Degree of Branching Using a modified conjugated diene polymer as a sample, a GPC measurement apparatus (trade name "GPCmax VE-2001" manufactured by Malvern) in which three columns packed with polystyrene gel were connected was used to measure using three detectors connected in this order: a light scattering detector, an RI detector, and a viscometer (trade name "TDA305" manufactured by Malvern). Based on standard polystyrene, the absolute molecular weight was determined from the results of the light scattering detector and the RI detector, and the intrinsic viscosity was determined from the results of the RI detector and the viscometer. The linear polymer had an intrinsic viscosity [η ０ ]=10 －３．４９８ M ０．７１１The shrinkage factor (g') was calculated as the ratio of intrinsic viscosity corresponding to each molecular weight according to the following formula. In this formula, M is the absolute molecular weight. THF containing 5 mmol / L triethylamine was used as the eluent. Columns manufactured by Tosoh Corporation under the trade names "TSKgel G4000HXL," "TSKgel G5000HXL," and "TSKgel G6000HXL" were used. 20 mg of the sample to be measured was dissolved in 10 mL of THF to prepare a measurement solution, and 100 μL of the measurement solution was injected into a GPC measurement device and measured under conditions of an oven temperature of 40°C and a THF flow rate of 1 mL / min. From the measurement, the absolute molecular weight distribution curve and branching degree distribution curve of the modified conjugated diene polymer were obtained, and the branching degree (Bn), defined as g' = 6Bn / {(Bn + 1)(Bn + 2)}, was calculated using the shrinkage factor (g').

[0336] (Property 5) Modification Ratio The modification ratios of a polymer (unmodified conjugated diene polymer) before modification with a coupling modifier and a polymer (modified conjugated diene polymer) after modification with a coupling modifier were measured by column adsorption GPC as follows. The column adsorption GPC method utilizes the tendency of the modified basic polymer component in a modified conjugated diene polymer to be easily adsorbed onto a GPC column packed with silica gel to determine the modification ratio of the modified polymer. Each polymer was used as a sample, and a sample solution containing the sample and a low-molecular-weight internal standard polystyrene was measured using a polystyrene column. A similar sample solution was also measured using a silica column. The amount of adsorption onto the silica column was measured, and the modification ratio was determined by calculating the difference between the chromatograms obtained using the polystyrene column and the silica column.

[0337] <Preparation of sample solution>: 10 mg of a sample and 5 mg of standard polystyrene were dissolved in 10 mL of THF to prepare a sample solution. The modification rates of the unmodified conjugated diene polymer and the modified conjugated diene polymer were measured under the following measurement conditions.

[0338] <GPC measurement conditions using a polystyrene column> GPC measurements were performed using a Tosoh Corporation product name "HLC-8320GPC" and an RI detector (Tosoh Corporation product name "HLC8020"). A 2 wt% triethylamine-THF solution was used as the eluent, and 10 μL of the sample solution was injected into the GPC device. A chromatogram was obtained under the conditions of a column oven temperature of 40°C and a THF flow rate of 1.0 mL / min. Two Tosoh Corporation product name "TSKgel GMHHR-H(S)" columns were connected, and a Tosoh Corporation product name "TSKguard column SuperMP(HZ)-H" was connected in front of the columns as a guard column.

[0339] <GPC measurement conditions using a silica-based column> GPC measurements were performed using a Tosoh Corporation product name "HLC-8320GPC" and an RI detector (Tosoh Corporation product name "HLC8020"). THF was used as the eluent, and 50 μL of the sample solution was injected into the device. A chromatogram was obtained under the conditions of a column oven temperature of 40 ° C. and a THF flow rate of 0.5 ml / min. The columns were Agilent Corporation product names "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S" connected in this order, and a guard column "DIOL 4.6 × 12.5 mm 5 micron" was connected to the front stage.

[0340] Calculation method for modification rate: For a chromatogram obtained by measurement using a polystyrene column, the peak area P1 of the sample and the peak area P2 of the standard polystyrene were calculated, with the total peak area set to 100. Furthermore, for a chromatogram obtained by measurement using a silica column, the peak area P3 of the sample and the peak area P4 of the standard polystyrene were calculated, with the total peak area set to 100. The modification rate (mass %) was calculated using the following formula: Modification rate (mass %) = [1 - (P2 x P3) / (P1 x P4)] x 100 (where P1 + P2 = P3 + P4 = 100)

[0341] (Physical Property 6) Amount of Bound Vinyl Aromatic Monomer Units (Amount of Bound Styrene) 100 mg of the modified conjugated diene polymer was used as a sample, and dissolved in 100 mL of chloroform to prepare a measurement sample. Each sample was measured using a spectrophotometer (trade name "UV-2450" manufactured by Shimadzu Corporation) to obtain an absorption spectrum. The amount of bound styrene (mass%) relative to 100 mass% of the modified conjugated diene polymer was calculated from the amount of absorbance of ultraviolet light (near 254 nm) derived from the phenyl group of styrene.

[0342] (Physical Property 7) Amount of vinyl bond in bound conjugated diene (amount of 1,2-vinyl bond in bound butadiene) A modified conjugated diene polymer was used as a sample, and 50 mg of the sample was dissolved in 10 mL of carbon disulfide to prepare a measurement sample. The infrared spectrum of each sample was measured from 600 to 1000 cm －１ The absorbance at a predetermined wave number was measured using a Fourier transform infrared spectrophotometer (trade name "FT-IR230" manufactured by JASCO Corporation). The amount of 1,2-vinyl bonds (mol %) in the bound butadiene was determined from the absorbance at a predetermined wave number according to the Hampton method (described in R.R. Hampton, Analytical Chemistry 21, 923 (1949)).

[0343] (Physical Property 8) Differential Scanning Calorimetry (DSC) Differential Curve Obtained by Differentiating the DSC Curve Recorded by Measurement Using a modified conjugated diene polymer as a sample, DSC measurement was carried out in accordance with ISO 22768: 2006 using a differential scanning calorimeter (trade name "DSC3200S" manufactured by Mac Science). Under a helium flow of 50 mL / min, the temperature was lowered from 20°C to -120°C at 20°C / min, and the temperature was raised from -120°C at 20°C / min, while recording a DSC temperature rise curve. The presence or absence of a peak observed between -100°C and -5°C on the DSC differential curve was confirmed, and the temperature of the peak top (inflection point) (glass transition temperature or glass transition point) was recorded.

[0344] (Conjugated Diene Polymer A1) Two tank-type pressure vessels each 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 equipped with a stirrer and a jacket for temperature control were connected as polymerization branching reactors. 1,3-butadiene, styrene, and n-hexane, from which moisture had been removed in advance, were continuously fed to the bottom of the first reactor while being mixed at rates of 15.4 g / min, 7.0 g / min, and 121.1 g / min, respectively. During the feeding, n-butyllithium was continuously added at a rate of 0.064 mmol / min to inactivate remaining impurities while being mixed using a static mixer immediately before the mixed solution entered the first reactor. Simultaneously with the supply of 1,3-butadiene, styrene, n-hexane, and n-butyllithium, 2,2-bis(2-oxolanyl)propane as a polar compound and n-butyllithium as a polymerization initiator (shown as "d-1" in Table 1) were supplied to the bottom of the first reactor at rates of 0.052 mmol / min and 0.142 mmol / min, respectively, while the reaction solution was vigorously stirred with a stirrer. The temperature inside the first reactor was maintained at 78°C.

[0345] The conjugated diene polymer solution produced by the polymerization reaction in the first reactor was continuously withdrawn from the top of the first reactor and continuously supplied to the bottom of the second reactor. When the polymerization became sufficiently stable, a polymerization branching step was carried out by supplying trimethoxy(4-vinylphenyl)silane (shown as "c-1" in Table 1) as a branching agent from the bottom of the second reactor at a rate of 0.016 mmol / min while copolymerizing 1,3-butadiene and styrene, and further adding additional 1,3-butadiene at a rate of 5.1 g / min.

[0346] Next, the conjugated diene polymer solution flowing out from the top of the second reactor was supplied to a static mixer. Furthermore, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (shown as "b-1" in Table 1) was continuously added as a coupling modifier at a rate of 0.025 mmol / min to the conjugated diene polymer solution continuously flowing through the static mixer, thereby coupling the conjugated diene polymer. The time required for the coupling modifier to be added to the polymer solution flowing out from the outlet of the second reactor was 4.8 minutes, and the temperature of the polymer solution when the coupling modifier was added was 78°C. The difference between the temperature of the polymer solution at the outlet of the second reactor and the temperature of the polymer solution when the coupling modifier was added was 2°C.

[0347] Next, an n-hexane solution of antioxidant (BHT) was continuously added to the polymer solution flowing out of the static mixer at a rate of 0.055 g / min so that the amount of antioxidant (BHT) per 100 g of polymer was 0.2 g, thereby completing the coupling reaction. The modified conjugated diene polymer solution was subjected to steam stripping to remove the solvent, and the solution was formed into a bale, thereby obtaining a modified conjugated diene polymer A1. Various measurements were performed, and the results are shown in Table 1. The obtained polymer solution was then transferred to a tank-type pressure vessel with an internal volume of 100 L.

[0348] (Conjugated diene polymers A2 to A7, A9, conjugated diene polymers B1 to B11, B13 to B14) The production method was the same as for modified conjugated diene polymer A1, and the amounts of styrene, butadiene, and n-hexane added to the bottom of the first reactor, the amount of polymerization initiator added, the amount of polar substance added, the amount of branching agent and 1,3-butadiene added to the bottom of the second reactor, the type of modifier, the amount of modifier added, and the polymerization temperature were adjusted as shown in Table 1 below to obtain conjugated diene polymers A2 to A7, A9, and conjugated diene polymers B1 to B11, and B13 to B14. Various measurements were performed, and the results are shown in Table 1. Furthermore, the obtained modified conjugated diene polymer solutions were each transferred to a tank-type pressure vessel having an internal volume of 100 L.

[0349] (Conjugated Diene Polymer A8) A 40 L internal volume, temperature-controllable autoclave equipped with a stirrer and a jacket was used as a reactor. 1,440 g of 1,3-butadiene from which impurities had been removed, 1,200 g of styrene, 21,000 g of cyclohexane, and 8.5 g of tetrahydrofuran (THF) as a polar substance were placed in the reactor, and the internal temperature of the reactor was maintained at 50°C. 0.017 mmol of n-butyllithium was supplied as a polymerization initiator to the reactor. After the polymerization reaction started, the temperature inside the reactor began to rise due to heat generated by the polymerization, and after the temperature peaked, 360 g of 1,3-butadiene was added over 5 minutes, and the final temperature inside the reactor reached 75°C. Two minutes after the reaction temperature reached its peak, 0.74 g of 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane was added to the reactor as a coupling modifier, and a coupling modification reaction was carried out for 10 minutes. An antioxidant (BHT) was added to this polymer solution so that the amount was 0.2 g per 100 g of polymer. The modified conjugated diene polymer solution was subjected to steam stripping to remove the solvent, and the resulting solution was formed into a bale, yielding Modified Conjugated Diene Polymer A8. Various measurements were performed, and the results are shown in Table 2. The resulting polymerization solution was then transferred to a tank-type pressure vessel with an internal volume of 100 L.

[0350] (Conjugated diene polymer B12) Conjugated diene polymer B12 was obtained using the same production method as for modified conjugated diene polymer 8, with the amounts of styrene, butadiene, polymerization initiator, polar substance, and modifier added to the autoclave adjusted as shown in Table 2 below. Various measurements were carried out, and the results are shown in Table 2. Furthermore, the resulting modified conjugated diene polymer solutions were each transferred to a tank-type pressure vessel having an internal volume of 100 L.

[0351] In Table 1, when two values ​​are listed for the polymerization temperature, the former indicates the polymerization temperature of the first group and the latter indicates the polymerization temperature of the second group. The initiator, branching agent, and modifier are also listed. Initiator d-1: n-butyllithium Branching agent c-1: trimethoxy(4-vinylphenyl)silane Modifier a-1: 1-methyl-4-(3-(trimethoxysilyl)propyl)piperazine Modifier a-2: trimethoxy(propyl)silane Modifier b-1: tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine Modifier b-2: 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane Modifier b-3: 1,6-bis(trimethoxysilyl)hexane

[0352] (Modified Conjugated Diene Polymer Mixture C1) The polymer solution of modified conjugated diene polymer A1 and the polymer solution of modified conjugated diene polymer B1 produced by the method described above and delivered to a tank-type pressure vessel were delivered so that the mass ratio of modified conjugated diene polymer A1 to modified conjugated diene polymer B1 was (A1):(B1) = 30:70, and the mixtures were allowed to merge in the pipe. After merging, the mixture was stirred and mixed using a rotary stirrer. Next, the solvent was removed by steam stripping, and the mixture was formed into a bale. The various physical properties of the resulting modified conjugated diene polymer mixture C1 were measured. The results are shown in Table 3.

[0353] (Modified conjugated diene polymer mixtures C2 to C45) The production method was the same as for modified conjugated diene polymer mixture C1, but the combination and mixing mass ratio of modified conjugated diene polymer A and modified conjugated diene polymer B used were changed, and the content of modified conjugated diene polymer A in modified conjugated diene polymer mixture C was changed as shown in Table 3, to obtain modified conjugated diene polymer mixtures C2 to C45. Various measurements were carried out, and the results are shown in Table 3.

[0354]

[0355]

[0356]

[0357] [Examples 1 to 41 and Comparative Examples 1 to 23: Evaluation of Bales of Modified Conjugated Diene Polymers] (Evaluation 1) Bale Appearance (Presence or Absence of Cracks / Crumbles) The bales of modified conjugated diene polymers shown in Tables 1 to 3 were visually inspected for appearance, such as the presence or absence of external cracks and crumbles, and evaluated based on the following criteria, with each panelist giving a maximum score of 4 points. The appearance of the bale is an indicator of the bale formability of the modified conjugated diene polymer. The evaluation results are shown in Tables 4 and 5. IV: The crumbs did not come together and could not be formed into a bale. III: It could be formed into a bale, but crumbled over time. II: Cracks, crumbles, etc. of 5% or less were observed on the bale surface. I: No cracks, crumbles, etc. were observed on the bale surface.

[0358] [Preparation and Evaluation of Rubber Compositions] (Evaluation of Rubber Compositions) Using the modified conjugated diene polymers A1 to A7, B1 to B9, and C1 to C45 shown in Tables 1 to 3 as raw materials, rubber compositions were obtained according to the following formulations: Modified conjugated diene polymer (any of A1 to A7, B1 to B9, and C1 to C45): 100 parts by mass (oil excluded) Silica (trade name "Ultrasil 7000GR" manufactured by Evonik Degussa, nitrogen adsorption specific surface area 170 m ２ / g): 75.0 parts by mass Carbon black (trade name "SEAT KH (N339)" manufactured by Tokai Carbon Co., Ltd.): 5.0 parts by mass Silane coupling agent (trade name "Si75" manufactured by Evonik Degussa, bis(triethoxysilylpropyl) disulfide): 6.0 parts by mass S-RAE oil (trade name "Process NC140" manufactured by JX Nippon Oil & Energy Corporation): 32.0 parts by mass Zinc oxide: 2.5 parts by mass Stearic acid: 2.0 parts by mass Antioxidant (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 (diphenylguanidine): 2.0 parts by mass

[0359] Specifically, the above materials were kneaded by the following method to obtain rubber compositions. In the first stage of kneading, a modified conjugated diene polymer (any of A1 to A7, B1 to B9, or C1 to C45), a filler (silica, carbon black), a silane coupling agent, S-RAE oil, zinc oxide, and stearic acid were kneaded using an internal kneader (capacity: 0.5 L) equipped with a temperature control device at a filling rate of 65% and a rotor rotation speed of 30 to 50 rpm. The temperature of the internal kneader was controlled to obtain each rubber composition (compound) such that the discharge temperature was 155 to 160°C.

[0360] Next, in the second stage of mixing, the compound obtained above was cooled to room temperature, and then an antioxidant was added. The compound was mixed again under the same conditions as in the first stage of mixing to improve the dispersion of silica. Again, the temperature of the mixer was controlled so that the discharge temperature of the compound was 155-160°C. After cooling, in the third stage of mixing, sulfur and vulcanization accelerators 1 and 2 were added and mixed using an open roll set at 70°C. The mixture was then molded and vulcanized in a vulcanization press at 160°C for 20 minutes. The rubber compositions before and after vulcanization were evaluated. Specifically, the evaluations were performed using the following methods. The evaluation results are shown in Tables 4 and 5.

[0361] (Evaluation 2) Discharge Cohesion The unvulcanized modified conjugated diene polymers produced by the methods shown in the Examples and Comparative Examples were visually observed for cohesion (shape) immediately after being discharged from the pressure kneader (immediately after being discharged after kneading by the pressure kneader in the first stage of kneading was completed), and evaluated by each panelist on a scale of 4 points out of 10 based on the following criteria. Cohesion is an index of the processability of the vulcanized product. IV: The edge portions of the sheet are 60% or less smooth, resulting in very poor processability. III: The edge portions of the sheet are more than 60% but not more than 80% smooth, resulting in poor processability. II: The edge portions of the sheet are more than 80% but not more than 90% smooth, resulting in excellent processability. I: The edge portions of the sheet are more than 90% smooth, resulting in excellent processability.

[0362] (Evaluations 3 and 4) Viscoelastic parameters (fuel economy and wet grip performance) Viscoelastic parameters were measured in torsion mode using a viscoelasticity tester "ARES" manufactured by Rheometrics Scientific. Each measurement value was indexed, with the result for the rubber composition of Comparative Example 1 being set to 100. Here, tan δ measured at 50°C, a frequency of 10 Hz, and a strain of 3% was used as an index of low hysteresis loss, i.e., fuel economy, and the result of Comparative Example 1 was standardized as 100. A larger index indicates better fuel economy, and a value exceeding 65 was evaluated as having excellent fuel economy. Furthermore, 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, and the result of Comparative Example 1 was standardized as 100. A larger index indicates better wet grip performance, and a value exceeding 65 was evaluated as having excellent wet grip performance.

[0363] (Evaluations 5 and 6) Tensile strength and tensile elongation Tensile strength and tensile elongation were measured in accordance with the tensile testing method of JIS K6251. Each measured value was standardized with the result of Comparative Example 1 set at 100. The larger the value, the better the tensile strength and tensile elongation, and the more excellent the fracture properties.

[0364] (Evaluation 7) Abrasion Resistance Using an Acron abrasion tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), the amount of abrasion was measured after 1,000 revolutions under a load of 44.4 N in accordance with JIS K6264-2. Each measurement value was standardized with the result of Comparative Example 1 set at 100. A larger value indicates better abrasion resistance, and values ​​exceeding 80 were evaluated as having excellent abrasion resistance.

[0365]

[0366]

[0367] As shown in Tables 4 and 5, it was found that the conjugated diene polymer of the present invention has excellent bale moldability, excellent processability of the vulcanizate thereof, and an excellent balance of performance among abrasion resistance, fracture characteristics, wet grip properties, and low hysteresis loss.

[0368] The conjugated diene-based polymer and rubber composition of the present invention have excellent moldability and processability, and the vulcanizates thereof have an excellent balance of performance in terms of abrasion resistance, fracture characteristics, fuel economy, and wet grip properties. Therefore, the conjugated diene-based polymer and rubber composition of the present invention have industrial applicability in applications such as tires, resin modification, automobile interior and exterior parts, vibration-proof rubber, and footwear.

Claims

1. A modified conjugated diene polymer satisfying the following <Condition (i)> to <Condition (iii)>. <Condition (i)> The molecular weight distribution curve by gel permeation chromatography (GPC, Gel Permeation Chromatography) has a single peak shape, and the molecular weight distribution (PDI; MWD) is 1.7 to 3.

5. <Condition (ii)> The modification rate is 40% by mass or more. <Condition (iii)> It has two or more peaks in the DSC differential curve obtained by differentiating the DSC curve recorded by differential scanning calorimetry (DSC, Differential Scanning Calorimetry) measurement.

2. The modified conjugated diene polymer according to claim 1, which has a shoulder on the higher molecular weight side than the peak top in the molecular weight distribution curve by gel permeation chromatography (GPC, Gel Permeation Chromatography).

3. The modified conjugated diene polymer according to claim 1, having a weight average molecular weight (Mw) of 40 × 10 ４ or more and 250 × 10 ４ or less as determined by gel permeation chromatography (GPC, Gel Permeation Chromatography).

4. The modified conjugated diene polymer according to claim 1, wherein the content of the repeating unit derived from the aromatic vinyl monomer is 0% by weight or more and 30% by weight or less.

5. The modified conjugated diene polymer according to claim 1, wherein the Mooney viscosity measured at 100 ° C is 80 or more and 170 or less, and the Mooney relaxation rate (MSR) measured at 100 ° C is 0.30 or more and 0.80 or less.

6. The modified conjugated diene polymer according to claim 1, wherein in the DSC differential curve obtained by differentiating the DSC curve recorded by differential scanning calorimetry (DSC, Differential Scanning Calorimetry) measurement, the difference (ΔTg) in the peak top positions between the peak with the highest peak height and the peak with the second highest peak height is 15 ° C or more.

7. The modified conjugated diene polymer according to claim 6, wherein the ΔTg is 15 ° C or more and 75 ° C or less.

8. A modified conjugated diene polymer (A) having a weight average molecular weight (Mw) measured by gel permeation chromatography (GPC, Gel Permeation Chromatography) of 70 × 10 ４ or more and 200 × 10 ４ or less, and a modified conjugated diene polymer (B) having an Mw measured by gel permeation chromatography (GPC, Gel Permeation Chromatography) of 10 × 10 ４ or more and 70 × 10 ４ less than that, and the modified conjugated diene polymer according to claim 1.

9. The difference (ΔMw) in the weight average molecular weight between the modified conjugated diene polymer (A) and the modified conjugated diene polymer (B) is 20 × 10 ４ or more. The modified conjugated diene polymer according to claim 8.

10. In the modified conjugated diene polymer, the mass ratio ((A) / (B)) of the modified conjugated diene polymer (A) and the modified conjugated diene polymer (B) is 40 / 60 to 10 / 90. The modified conjugated diene polymer according to claim 8.

11. The modified conjugated diene polymer (A) and / or (B) includes a conjugated diene polymer having a fork type part [A] in which a plurality of conjugated diene polymer chains are bonded to one end side of the main chain branch structure part and a single chain of another conjugated diene polymer is bonded to the other end side of the main chain branch structure part. The modified conjugated diene polymer according to claim 8.

12. The modified conjugated diene polymer (A) and / or (B) includes a conjugated diene polymer having a fork-shaped part [A] in which a plurality of conjugated diene polymer chains are bonded to one end side of a main chain branched structure part and a single chain of another conjugated diene polymer is bonded to the other end side of the main chain branched structure part, and a star polymer structure part [B] having three or more branches to which one or more of the fork-shaped parts [A] are bonded. The modified conjugated diene polymer according to claim 8.

13. A molded article containing 100 parts by mass of the modified conjugated diene polymer according to claim 1 and a softening agent component of less than 1 part by mass.

14. A method for producing a modified conjugated diene polymer according to claim 8, which comprises continuously polymerizing a modified conjugated diene polymer (A) and a modified conjugated diene polymer (B) using one or more reactors respectively, solution-mixing a polymerization solution containing the modified conjugated diene polymer (A) and a polymerization solution containing the modified conjugated diene polymer (B), and then removing a solvent to obtain a modified conjugated diene polymer.

15. The modified conjugated diene polymer (A) and / or (B) is produced by a production method having a polymerization step of obtaining a conjugated diene polymer having an active end by polymerizing or copolymerizing a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound using an alkali metal compound or an alkaline earth metal compound as a polymerization initiator, a polymerization branching step of introducing a branched structure by reacting a branching agent with the active end of the conjugated diene polymer, and a modification step of reacting a coupling modifier with the polymerization-terminated end. The method for producing a modified conjugated diene polymer according to claim 14.

16. The method for producing a modified conjugated diene-based polymer according to claim 15, wherein the branching agent is a compound represented by the following formula (1) or (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, and may have a branched structure in a part thereof. R ２ to R ３ each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and may have a branched structure in a part thereof. When a plurality of R ２ to R ３ are present, they 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 ４ to R ７ each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and may have a branched structure in a part thereof. When a plurality of R ４ to R ７ are present, they are each independent. X ２ to X ３ represent independent halogen atoms. 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 3, b represents an integer of 0 to 2, and c represents an integer of 0 to 3. (a + b + c) represents an integer of 3.) 17. A rubber composition containing 100 parts by mass of a rubber component and 5.0 to 150 parts by mass of a filler, wherein the rubber component contains 10 parts by mass or more of the modified conjugated diene polymer according to any one of claims 1 to 12 based on 100 parts by mass of the total amount of the rubber component.

18. A tire containing the rubber composition according to claim 17.

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