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

Abstract

Disclosed is a modified conjugated diene polymer which satisfies the condition (i) to condition (vi) described below. Condition (i): The Mooney viscosity measured at 100ºC is 100 to 180 inclusive. Condition (ii): The Mooney relaxation rate measured at 100°C is within the range of 0.10 to 0.40. Condition (iii): The glass transition temperature is -95°C to -45°C. Condition (iV): The content of silicon atoms is 100 ppm by mass or more relative to the total amount of the modified conjugated diene polymer. Condition (V): The content of nitrogen atoms is 50 ppm by mass or more relative to the total amount of the modified conjugated diene polymer. Condition (Vi): The content of an antioxidant is 0.5 part by mass or less relative to 100 parts by mass of the modified conjugated diene polymer.

Description

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

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

[0002] In recent years, there has been an increasing demand for improved fuel economy for automobiles, and this has led to a demand for improvements in the rubber materials used in automobile tires, particularly in tire treads that come into contact with the road surface. In response to increasing fuel economy regulations for automobiles, there is an increasing demand for the use of resin for automobile components and for thinner tires in order to reduce the weight of automobiles.

[0003] Materials that meet the above-mentioned requirements include materials containing rubber and reinforcing fillers such as carbon black and silica. For example, the use of a material containing silica can improve the balance between low hysteresis loss and wet skid resistance. Attempts have also been made to improve the dispersibility of silica in materials by introducing functional groups with affinity or reactivity with silica into the molecular terminals of highly mobile rubber, thereby reducing the mobility of the rubber molecular terminals through bonding with silica particles and thereby reducing hysteresis loss. In particular, attempts have been made to further reduce hysteresis by introducing modifying groups into both ends of the polymer chain. Furthermore, efforts have been made to increase the molecular weight of modified conjugated diene polymers in order to improve breaking strength and abrasion resistance. However, high-molecular-weight modified conjugated diene polymers have a problem in 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, by introducing modifying groups into both ends of the polymer chain, the nitrogen atom content in the modified conjugated diene polymer increases, which reduces thermal stability and requires the addition of a large amount of antioxidant. However, there is room for reducing the amount used from the viewpoints of reducing product costs and environmental load.

[0004] 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. Furthermore, Patent Documents 2 and 3 propose polymers functionalized by reacting a cyclic azasilacycle compound with an active terminal of a polymer. Furthermore, Patent Documents 4 and 5 propose diene rubbers obtained by coupling a polymer active terminal with a polyfunctional silane compound.

[0005] Japanese Patent Application Publication No. 2019-131810 Japanese Patent Application Publication No. 2005-290355 Japanese Patent Application Publication No. 11-189616 International Publication No. 07 / 114203 Pamphlet Japanese Patent Application No. 2018-534375

[0006] 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.

[0007] However, in the case of the conjugated diene polymer veil disclosed in Patent Document 1, there is a problem in that reducing the amount of process oil added may result in insufficient moldability. For example, when increasing the molecular weight of the modified conjugated diene polymer to improve abrasion resistance or setting the glass transition temperature of the modified conjugated diene polymer to a low value to improve low hysteresis loss, if the amount of process oil added is small or the polymer is formulated without any process oil, the polymer particles are likely to peel off from the surface of the veil. Furthermore, increasing the nitrogen content tends to deteriorate thermal stability, which necessitates the need to increase the amount of antioxidant added when preparing the veil-forming body.

[0008] As a result of extensive research and investigation to solve the above-mentioned problems, the present inventors have found that a modified conjugated diene polymer having a predetermined Mooney viscosity, Mooney relaxation rate (MSR), a glass transition temperature within a predetermined range, and a predetermined silicon atom content and nitrogen atom content can be molded into a bale with a reduced antioxidant content, thereby solving the above-mentioned problems and completing the present invention.

[0009] [1] A modified conjugated diene polymer satisfying the following conditions (i) to (vi): <Condition (i)> The Mooney viscosity measured at 100°C is 100 or more and 180 or less. <Condition (ii)> The Mooney relaxation coefficient measured at 100°C is in the range of 0.10 to 0.40. <Condition (iii)> The glass transition temperature is -95°C to -45°C. <Condition (iv)> The silicon atom content is 100 ppm by mass or more, based on the total amount of the modified conjugated diene polymer. <Condition (V)> The nitrogen atom content is 50 ppm by mass or more, based on the total amount of the modified conjugated diene polymer. <Condition (Vi)> The antioxidant content is 0.5 parts by mass or less, based on 100 parts by mass of the modified conjugated diene polymer. [2] The modified conjugated diene polymer according to [1], wherein the Mooney viscosity measured at 100°C in the <Condition (i)> is 105 or more and 180 or less. [3] The modified conjugated diene polymer according to [1] or [2], wherein the Mooney relaxation coefficient measured at 100°C in the <Condition (ii)> is 0.10 to 0.35. [4] The modified conjugated diene polymer according to any one of [1] to [3], wherein the glass transition temperature in the <Condition (iii)> is -95°C to -55°C. [5] The modified conjugated diene polymer according to any one of [1] to [4], wherein the nitrogen atom content in the <Condition (V)> is 80 ppm by mass or more relative to the total amount of the modified conjugated diene polymer. [6] The modified conjugated diene polymer according to any one of [1] to [5], wherein the molecular weight distribution (PDI; MWD) is 1.4 to 2.5. [7] The modified conjugated diene polymer according to any one of [1] to [6], wherein the amount of 1,2-vinyl bonds relative to the total mass of the modified conjugated diene polymer is 45.0 mol % or less. [8] The modified conjugated diene polymer according to any one of [1] to [7], wherein the branching degree (Bn) measured by a GPC-light scattering method with a viscosity detector is 2 or more.[9] The modified conjugated diene polymer according to any one of [1] to [8], having a nitrogen atom at at least one terminal, and having at least one branched chain in a star-shaped structure, the branched chain in the star-shaped structure having a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, the moiety derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group having a further branched structure in the main chain, and having a coupling structure centered on a nitrogen-containing alkoxysilane substituent.

[10] The modified conjugated diene polymer according to any one of [1] to [9], wherein the coupling structure centered on the nitrogen-containing alkoxysilane substituent is such that a nitrogen-containing alkoxysilane modifier residue has at least four silicon atoms and an alkoxy group and / or a hydroxy group, a modified conjugated diene polymer chain having a branched structure in the main chain is bonded to the silicon atom, and the number of the alkoxy groups and / or the hydroxy groups in the modifier residue is greater on average than the number of the silicon atoms.

[11] A veil containing 100 parts by mass of the modified conjugated diene polymer according to any one of [1] to

[10] and 2 parts by mass or less of a softener component.

[12] A veil containing 100 parts by mass of the modified conjugated diene polymer according to any one of [1] to

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

[13] A method for producing the modified conjugated diene polymer according to any one of [1] to

[10] , comprising: a step of polymerizing at least a conjugated diene compound in the presence of an organolithium compound having at least one nitrogen atom in the molecule; and a branching step of obtaining a branched conjugated diene polymer having a main chain branched structure using a branching agent, wherein in the step of coupling the branched conjugated diene polymer using a coupling agent and / or the step of modifying the branched conjugated diene polymer with a modifier having a nitrogen atom-containing group, the coupling agent and / or the modifier are added in excess.

[14] 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

[10] or the veil according to

[11] or

[12] , relative to 100 parts by mass of the total amount of the rubber component.

[15] A tire containing the rubber composition according to

[14] .

[0010] According to the present invention, it is possible to provide a modified conjugated diene polymer that has excellent fuel-saving performance and processability, and that has excellent bale formability even when it is an un-oil-extended product to which no process oil is added.

[0011] 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.

[0012] [Modified Conjugated Diene Polymer] The modified conjugated diene polymer of this embodiment satisfies the following <Condition (i)> to <Condition (vi)>. <Condition (i)> The Mooney viscosity measured at 100°C is 100 or more and 180 or less. <Condition (ii)> The Mooney relaxation coefficient measured at 100°C is in the range of 0.10 to 0.40. <Condition (iii)> The glass transition temperature is -95°C to -45°C. <Condition (iv)> The silicon atom content is 100 ppm by mass or more, based on the total amount of the modified conjugated diene polymer. <Condition (V)> The nitrogen atom content is 50 ppm by mass or more, based on the total amount of the modified conjugated diene polymer. <Condition (Vi)> The antioxidant content is 0.5 parts by mass or less, based on 100 parts by mass of the modified conjugated diene polymer.

[0013] The modified conjugated diene polymer of this embodiment has excellent fuel-saving performance and processability, and even when it is an un-oil-extended product without adding process oil, it suppresses a decrease in thermal stability and has excellent bale formability. The modified conjugated diene polymer of this embodiment has extremely excellent processability when vulcanized, and when vulcanized, it tends to achieve a particularly excellent balance between low hysteresis loss and wet skid resistance. Furthermore, when vulcanized, the modified conjugated diene polymer of this embodiment tends to have excellent abrasion resistance, good strain dispersibility at 50°C, excellent repeated strain strength, and fracture properties sufficient for practical use.

[0014] 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 modified conjugated diene compounds, and a copolymer of a conjugated diene compound and a vinyl aromatic compound.

[0015] 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.

[0016] Examples of vinyl aromatic compounds include, but are not limited to, styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred from the viewpoint of effectively and reliably achieving the effects of the present embodiment. These vinyl aromatic compounds may be used alone or in combination of two or more.

[0017] (Condition (i): Mooney viscosity of modified conjugated diene polymer) Mooney viscosity is an index showing the overall characteristics of a modified conjugated diene polymer, including information such as the molecular weight, molecular weight distribution, degree of branching, and content of a softener of the modified conjugated diene polymer. The method for measuring Mooney viscosity is specified in ISO 289, and since the measurement error due to differences in instruments is small, it is extremely effective in controlling the performance of the modified conjugated diene polymer. The Mooney viscosity (hereinafter also simply referred to as "Mooney viscosity" or "ML") of the modified conjugated diene polymer of this embodiment measured at 100°C is 100 or more, and from the viewpoints of handling stability, breaking strength, and abrasion resistance when the rubber composition for crosslinking is used in a tire, it is preferably 105 or more, and more preferably 115 or more. On the other hand, the upper limit is 180 or less, and from the viewpoints of moldability and productivity of molded articles of various shapes such as sheet-like or block-like shapes, the moldability of the rubber composition of this embodiment, and the processability of rubber compositions blended with fillers and the like, the upper limit is preferably 170 or less, more preferably 160 or less, and even more preferably 150 or less.

[0018] Generally, the higher the Mooney viscosity, the better the handling stability, breaking strength, and abrasion resistance when a modified conjugated diene polymer and a rubber composition thereof are used in a tire. On the other hand, the moldability of a sheet- or block-shaped molded body and a rubber composition containing the modified conjugated diene polymer tends to deteriorate. Generally, when the Mooney viscosity is 100 or higher, the blending of a process oil is required for molding into a bale. However, the modified conjugated diene polymer of this embodiment is specified to have specific Mooney viscosity, Mooney relaxation rate, glass transition temperature, silicon atom content, and nitrogen atom content, as described below. As a result, the modified conjugated diene polymer of this embodiment has a significant feature in that it can be molded into a bale, even if the polymer has a Mooney viscosity of 100 or higher, which is normally difficult to mold into a bale without the addition of a process oil. Furthermore, by specifying the Mooney viscosity to 180 or less, peeling of the modified conjugated diene polymer from the bale is suppressed, resulting in good bale moldability.

[0019] The Mooney viscosity of the modified conjugated diene polymer is measured by the following method. First, a sample of the modified conjugated diene polymer is formed into a plate shape using a pressure press and set in the apparatus. The sample is preheated at 100°C for 1 minute. Then, the rotor is rotated at 2 rpm, and the torque is measured after 4 minutes. The measured value is 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 modified conjugated diene polymer of this embodiment can be controlled to be within the above-mentioned range by adjusting the type, timing of use, and amount of the branching agent and coupling modifier, and the molecular weight, molecular weight distribution, and degree of branching of the modified conjugated diene polymer.

[0020] (Condition (ii): Mooney Relaxation Rate of Modified Conjugated Diene Polymer) The Mooney relaxation rate of the modified conjugated diene polymer of this embodiment measured at 100°C (hereinafter also simply referred to as "Mooney Relaxation Rate" or "MSR") is 0.40 or less, and from the viewpoint of processability of a rubber composition blended with a filler or the like, it is preferably 0.35 or less, and more preferably 0.30 or less. On the other hand, it is 0.10 or more, and 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 preferably 0.15 or more, and more preferably 0.20 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 modified conjugated diene polymer, and is an index showing the overall characteristics of the modified conjugated diene polymer.

[0021] The MSR can be measured using a Mooney viscometer as follows: The Mooney relaxation rate is measured at a temperature of 100°C. First, the sample is preheated for 1 minute, and then the rotor is rotated at 2 rpm. The Mooney viscosity (ML （１＋４）) is measured, and the rotation of the rotor is immediately stopped. The torque is recorded in Mooney units every 0.1 seconds for 1.6 seconds to 5 seconds after the rotation has stopped, and the slope of the straight line obtained by plotting the torque against the time (seconds) logarithmically is determined, and the absolute value of this slope is taken as 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 modified conjugated diene polymer of this embodiment can be controlled to fall within the above-mentioned range by adjusting the type, timing of use, and amount of the branching agent and coupling modifier, and the molecular weight, molecular weight distribution, and degree of branching of the modified conjugated diene polymer.

[0022] (Condition (iii) Glass Transition Temperature of Modified Conjugated Diene Polymer) The modified conjugated diene polymer of this embodiment has a glass transition temperature (hereinafter also referred to as "Tg") of -95°C or higher, preferably -78°C or higher, and more preferably -65°C or higher. A glass transition temperature of -95°C or higher results in excellent processability during vulcanization. The modified conjugated diene polymer of this embodiment also has a glass transition temperature of -45°C or lower, preferably -55°C or lower, more preferably -58°C or lower, and even more preferably -60°C or lower. A glass transition temperature of -45°C or lower results in excellent breaking strength, abrasion resistance, and low hysteresis loss of the vulcanized product of the modified conjugated diene polymer. The glass transition temperature may be within a range that combines any of the above upper and lower limits. The glass transition temperature of the modified conjugated diene polymer can be measured in accordance with ISO 22768:2017. More specifically, a differential scanning calorimetry (DSC) measurement is performed while increasing the temperature within a predetermined temperature range, a DSC curve is recorded, 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.

[0023] (Condition (iv): Silicon Atom Content) From the viewpoint of providing the modified conjugated diene polymer of the present embodiment with excellent fuel-saving performance even in the case of an un-oil-extended product to which no process oil is added, the silicon atom content is 100 ppm by mass or more relative to the total amount of the modified conjugated diene polymer. The silicon atom content can be measured using 0.5 g of the modified conjugated diene polymer as a sample in accordance with JIS K 0101 44.3.1 using an ultraviolet-visible spectrophotometer (trade name "UV-1800" manufactured by Shimadzu Corporation), and quantified by molybdenum blue absorptiometry.

[0024] Generally, the silicon atom content serves as an indicator of the amount of coupling agent and modifier added to the modified conjugated diene polymer. For example, modified conjugated diene polymers with low molecular weights generally have a high silicon content, and as the molecular weight increases, the amount of coupling agent and modifier added to the modified conjugated diene polymer decreases, so the silicon content tends to decrease. The inclusion of silicon atoms tends to strengthen the interaction with fillers, such as silica, added when preparing the composition. The silicon atom content in the modified conjugated diene polymer of this embodiment is 100 ppm by mass or more, preferably 130 ppm by mass or more, and more preferably 150 ppm by mass or more. The silicon atom content in the modified conjugated diene polymer of this embodiment is preferably 500 ppm by mass or less, more preferably 400 ppm by mass or less, and even more preferably 350 ppm by mass or less. The silicon atom content tends to be controlled within the above range by adjusting the amount of modifier and coupling agent added and the reaction method.

[0025] (Condition (v): Nitrogen Atom Content) The modified conjugated diene polymer of this embodiment has a nitrogen atom content of 50 ppm by mass or more relative to the total amount of the modified conjugated diene polymer. The nitrogen atom content (hereinafter also referred to as "nitrogen content") is the total number of nitrogen atoms in nitrogen-containing functional groups of the modified conjugated diene polymer, for example, the nitrogen-containing functional groups at the initiation end, in the main chain, and at the terminal end. From the viewpoints of processability, the balance between low hysteresis loss and wet skid resistance, abrasion resistance, and fracture properties, the nitrogen content of the modified conjugated diene polymer is 50 ppm by mass or more relative to the total amount of the modified conjugated diene polymer, preferably 60 ppm by mass or more, more preferably 70 ppm by mass or more, and even more preferably 80 ppm by mass or more. From the viewpoint of processability, the nitrogen content is preferably 800 ppm by mass or less, more preferably 700 ppm by mass or less, even more preferably 600 ppm by mass or less, and even more preferably 500 ppm by mass or less. The nitrogen atom content can be measured by an oxidative combustion-chemiluminescence method (JIS-2609: Crude oil and crude oil products - Nitrogen content test method). More specifically, the nitrogen atom content can be measured by the method described in the examples below.

[0026] The nitrogen content tends to be controllable by adjusting the amount of modifier added and the reaction method, and can be made 50 ppm by mass or more by this method. Examples include a polymerization method using an organolithium compound having at least one nitrogen atom in the molecule as a polymerization initiator, as described below, and a method in which a modified conjugated diene polymer having a nitrogen atom, obtained by copolymerizing a monomer having at least one nitrogen atom in the molecule, is reacted with a modifier having at least one nitrogen atom in the molecule. Furthermore, an example of a method for obtaining a modified conjugated diene polymer having a nitrogen content of 500 ppm by mass or less is a method in which the molecular weight of the modified conjugated diene polymer chain is controlled so as not to be too small.

[0027] <Condition (vi): Antioxidant Content> The modified conjugated diene polymer of this embodiment has an antioxidant content of 0.5 parts by mass or less per 100 parts by mass of the modified conjugated diene polymer. The antioxidant content (hereinafter also referred to as "antioxidant content") refers to the total content of antioxidants contained in the modified conjugated diene polymer and is added to ensure thermal stability. For example, modified conjugated diene polymers generally have high molecular weights and high Mooney viscosities, and the amount of antioxidant added tends to increase as the molecular weight increases. Furthermore, introducing modifying groups to both ends of the polymer chain and increasing the nitrogen atom content in the modified conjugated diene polymer can reduce thermal stability and require the addition of a large amount of antioxidant. On the other hand, from the perspectives of reducing product costs and environmental impact, it is preferable to reduce the amount of antioxidant used. The modified conjugated diene polymer of this embodiment can be bale-molded with a reduced amount of antioxidant added by satisfying certain conditions. From the above viewpoints, the content of the antioxidant per 100 parts by mass of the modified conjugated diene polymer is 0.5 parts by mass or less, preferably 0.45 parts by mass or less, more preferably 0.40 parts by mass or less, and even more preferably 0.35 parts by mass or less. From the viewpoint of thermal stability, it is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and even more preferably 0.3 parts by mass or more. The content of the antioxidant can be measured by the HPLC analysis method described below.

[0028] (Average Molecular Weight and Molecular Weight Distribution) The modified conjugated diene polymer of the present embodiment preferably has a weight average molecular weight of 45×10 as measured by GPC. ４ More preferably, 50×10 ４ More preferably, 60×10 ４ or more, and even more preferably 65×10 ４ More than this, and even more than 70 x 10 ４ The weight average molecular weight measured by GPC measurement method is 45×10 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 120×10 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.

[0029] 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 The number average molecular weight is 20×10 or less. ４ When the number average molecular weight is 100 or more, the dispersibility of the filler in the vulcanized product is more excellent, and practically sufficient fracture properties tend to be obtained. The number average molecular weight may be set within a range that combines any of 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.

[0030] In the modified conjugated diene polymer of this embodiment, the ratio (Mw / Mn) of the weight average molecular weight (Mw) measured by GPC measurement to the number average molecular weight (Mn) measured by GPC measurement (molecular weight distribution, PDI (Poly Dispersity Index); MWD (molecular weight distribution)) is preferably 1.4 or more, more preferably 1.5 or more, even more preferably 1.6 or more, and still more preferably 1.7 or more, from the viewpoints of processability during vulcanization and the abrasion resistance and breaking strength of the vulcanizate. Furthermore, the upper limit of the molecular weight distribution is not particularly limited, but is generally preferably 2.5 or less, more preferably 2.2 or less, even more preferably 2.0 or less, and still more preferably 1.9 or less. The molecular weight distribution of the modified conjugated diene polymer can be controlled within the above-mentioned numerical range by adjusting polymerization conditions such as the types and amounts of monomers, polymerization initiators, and polar compounds, polymerization time, polymerization temperature, and the amount and type of coupling modifier added, and the combination when two or more types are used.

[0031] (Microstructure of Modified Conjugated Diene Polymer) The microstructure of the modified conjugated diene polymer (the amount of bound vinyl aromatic compound, the amount of bound conjugated diene compound, and the proportion of vinyl bonds in the bound conjugated diene compound) affects the glass transition temperature of the modified conjugated diene polymer. Therefore, there are preferred ranges for the amount of vinyl aromatic compound and the amount of vinyl bonds from the viewpoint of controlling the glass transition temperature. In the microstructure of the modified conjugated diene polymer, the amount of bound vinyl aromatic compound is not particularly limited, but is preferably 1% by mass or more and 40% by mass or less, more preferably 1% by mass or more and 36% by mass or less, even more preferably 1% by mass or more and 30% by mass or less, still more preferably 2% by mass or more and 29% by mass or less, still more preferably 3% by mass or more and 28% by mass or less, and particularly preferably 5% by mass or more and 27% by mass or less, based on the entire modified conjugated diene polymer. When the amount of bound vinyl aromatic compound is within the above range, the vulcanizate of the modified conjugated diene polymer tends to have even better breaking strength, abrasion resistance, and low hysteresis loss. In addition, an increase in the amount of bound vinyl aromatic compound tends to increase the Tg of the modified conjugated diene polymer, while a decrease in the amount of bound vinyl aromatic compound tends to decrease the Tg. In this specification, the "amount of bound vinyl aromatic compound" means the content of the portion derived from the aromatic vinyl compound used as a monomer.

[0032] In modified conjugated diene polymers containing a vinyl aromatic compound, if the vinyl bond content in the conjugated diene bond units or the vinyl aromatic compound content is low, the Tg of the modified conjugated diene polymer tends to decrease, resulting in improved abrasion resistance and low hysteresis when vulcanized. Therefore, there is a need to design polymers with such structures. On the other hand, low vinyl bond content or low vinyl aromatic compound content can have a negative impact on moldability when forming a block-shaped bale and processability when forming a vulcanized product. In particular, for non-oil-extended products, which are difficult to form into bales, reduction in the vinyl bond content or vinyl aromatic compound content tends to be practically limited. In response to these issues, the present inventors have found that by using the modified conjugated diene polymer of this embodiment, good bale molding can be achieved even when the modified conjugated diene polymer is not oil-extended. Therefore, in the microstructure design of non-oil-extended products, the constraints of being unable to reduce the vinyl bond content or the vinyl aromatic compound content are alleviated, making it possible to set a low glass transition temperature.

[0033] In the microstructure of the modified conjugated diene polymer, the amount of the bound conjugated diene compound is not particularly limited, but is preferably 60% by mass to 99% by mass, more preferably 64% by mass to 99% by mass, even more preferably 70% by mass to 99% by mass, even more preferably 71% by mass to 98% by mass, still more preferably 72% by mass to 97% by mass, and particularly preferably 73% by mass to 95% by mass. When the amount of the bound conjugated diene compound is within the above range, the vulcanizate of the modified conjugated diene polymer tends to be even more excellent in fracture strength, abrasion resistance, and low hysteresis loss. In this specification, the "amount of bound conjugated diene compound" means the content of the portion derived from the conjugated diene compound as a monomer.

[0034] In the microstructure of the modified conjugated diene polymer, the 1,2-vinyl bond content relative to the total mass of the modified conjugated diene polymer (hereinafter simply referred to as "vinyl bond amount") is not particularly limited, but is preferably 11.0 mol% to 60.0 mol%, more preferably 11.0 mol% to 45.0 mol%, even more preferably 12.0 mol% to 35.0 mol%, still more preferably 13.0 mol% to 34.0 mol%, still more preferably 14.0 mol% to 33.0 mol%, and particularly preferably 15.0 mol% to 30.0 mol%. When the vinyl bond amount is within the above range, the modified conjugated diene polymer tends to have better breaking strength and abrasion resistance due to increased linearity of the structure of the conjugated diene moiety and stronger entanglement of polymer chains. Furthermore, when the vinyl bond content is within the above range, the vulcanizate tends to have even better low hysteresis loss properties. An increase in the vinyl bond content increases Tg, while a decrease in the vinyl bond content decreases Tg. In this specification, the "vinyl bond content in the bound conjugated diene" refers to the proportion of the portion having a vinyl bond among the portion derived from a conjugated diene compound (hereinafter referred to as "bound conjugated diene").

[0035] (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:

[0036] 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.

[0037] 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 ]).

[0038] 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.

[0039] 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.

[0040] 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 ２In this specification, the intrinsic viscosity is a value measured by the method described in the Examples section below.

[0041]

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

[0043] 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.

[0044] 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.

[0045] 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.

[0046] The modified conjugated diene polymer of the present embodiment preferably has a degree of branching (Bn) of 2 or more, which means that the modified conjugated diene polymer has a star polymer structure having branches similar to a four-branched star polymer structure.

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

[0048] By having a branching degree (Bn) of 2 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.

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

[0050] Therefore, even if a large number of functional groups are introduced into the polymer to improve the affinity and / or reactivity with 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 low hysteresis loss and improved wet skid resistance that should be expected from the introduction of functional groups are not exerted.

[0051] On the other hand, by setting the branching degree (Bn) of the modified conjugated diene polymer of this embodiment to 2 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 a large value, 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 enables the modified conjugated diene polymer to have sufficiently low hysteresis loss and wet skid resistance for practical use.

[0052] The absolute molecular weight of the modified conjugated diene polymer can be measured by the method described in the examples below.

[0053] The degree of branching (Bn) of the modified conjugated diene polymer of the present embodiment is preferably at least 2, more preferably at least 3, even more preferably at least 4, still more preferably at least 5, particularly preferably at least 6, and even more preferably at least 8. A modified conjugated diene polymer having a degree of branching (Bn) within this range tends to be excellent in processability and bale moldability when made into a vulcanizate.

[0054] 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.

[0055] The degree of branching of the modified conjugated diene polymer can be controlled to 2 or more by combining the amount of branching agent added and the amount of terminal coupling agent added. Specifically, the degree of branching can be controlled by the number of functional groups of the branching agent, the amount of branching agent added, the timing of adding the branching agent, the number of functional groups 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.

[0056] 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.

[0057] (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; modifying groups containing only one atom or coupling modifiers having a modifying group may be combined so that the polymer contains both nitrogen and silicon.

[0058] (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 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 using a nitrogen-containing lithium compound as an initiator, as described below. Therefore, when the specific functional group contains a nitrogen atom, the term refers to the mass ratio of the nitrogen-containing modified 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 they are referred to in parallel as "conjugated diene polymer or modified conjugated diene polymer," the term "conjugated diene polymer" encompasses both unmodified conjugated diene polymers and modified conjugated diene polymers. In addition, when the terms "conjugated diene polymer or modified conjugated diene polymer" are used in parallel, the term "conjugated diene polymer" means an unmodified conjugated diene polymer.

[0059] For example, in a conjugated diene polymer including a modified conjugated diene polymer modified 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.

[0060] The modified conjugated diene polymer of this embodiment preferably has a nitrogen atom at least at its terminal, and more preferably is modified with a functional group containing a nitrogen atom and a silicon atom in addition to the terminal nitrogen 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.

[0061] From the viewpoint of improving the low hysteresis loss properties of the vulcanizate, the modification rate of the modified conjugated diene polymer of this embodiment is preferably 85% by mass or more, more preferably 88% by mass or more, even more preferably 89% by mass or more, still more preferably 90% by mass or more, and still more preferably 91% by mass or more, based on the total amount of the modified 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, 96% by mass or less, or 95% 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 properties.

[0062] In the modified 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 such a method 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.

[0063] 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.

[0064] In the modified conjugated diene polymer of this embodiment, the modification rate can be controlled within the above-mentioned range by adjusting the amount of coupling modifier added and the method for reacting the modified conjugated diene compound with the modifier. For example, two or more of the following may be combined: 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 using a monomer having at least one nitrogen atom in the molecule; and a method using a modifier of the structural formula described below.

[0065] (Structure of Modified Conjugated Diene Polymer) The modified conjugated diene polymer of this embodiment has a nitrogen atom at at least one terminal and at least one branched chain with a star structure, and the branched chain with the star structure has a portion derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, as described below, and the portion derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group preferably has a further main chain branched structure and a coupling structure centered on a nitrogen-containing alkoxysilane substituent. In this specification, the phrase "the modified conjugated diene polymer chain is bonded to the modifier" refers to the state of a compound formed by bonding the polymer chain to a so-called coupling agent (modifier) ​​during the polymer production process. Therefore, the structure of the "modifier" (also referred to as "modifier residue") in the polymer differs from the initial structure of the modifier before the reaction, in that the leaving group is gone from the modifier and the polymer chain is bonded. That is, the modifier (residue) contained in the modified conjugated diene polymer is a structural unit of the modified conjugated diene polymer bonded to the modified conjugated diene polymer chain, and is, for example, a structural unit derived from the modifier produced by reacting the conjugated diene polymer described below with a modifier. The modified conjugated diene polymer containing a nitrogen atom and a silicon atom in the modifier tends to have a stronger interaction with a filler, such as silica, added when preparing the composition, compared to a polymer containing only one of the nitrogen atom and the silicon atom.

[0066] <Star-shaped branched structure having a main chain branched structure in a nitrogen-containing conjugated diene polymer chain> The modified conjugated diene polymer chain has a nitrogen atom at at least one terminal and at least one star-shaped branched chain, and the star-shaped branched chain has a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and the moiety derived from the vinyl monomer containing the alkoxysilyl group or the halosilyl group preferably has a further main chain branched structure and a coupling structure centered on a nitrogen-containing alkoxysilane substituent. The structural unit derived from the modified conjugated diene polymer of this embodiment is a constituent unit of the modified conjugated diene polymer, and may be, for example, a modified conjugated diene polymer chain derived from an organolithium compound having at least one nitrogen atom in the molecule, having a nitrogen atom introduced at one terminal, and having a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and the moiety derived from the vinyl monomer containing the alkoxysilyl group or the halosilyl group preferably has a further main chain branched structure, and may be obtained by reacting the modified conjugated diene polymer with a modifier. In the modified conjugated diene polymer of this embodiment, preferably, the modified conjugated diene polymer chain having a nitrogen atom at its terminal has a portion derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and in the portion derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group, a further main chain branched structure is formed, and it is preferable that the portion further has a star-shaped branched structure bonded to one modifier, and more preferably, the number of alkoxysilane residues of the modifier is greater than the number of conjugated diene polymer chains bonded to the modifier. By having this structure, excellent processability when vulcanized tends to be obtained, and fuel economy performance tends to be significantly improved.

[0067] <Nitrogen-Containing Conjugated Diene Polymer Chain> The conjugated diene polymer chain preferably has a nitrogen atom in at least one conjugated diene polymer chain. For example, it is a conjugated diene polymer chain having a functional group containing a nitrogen atom at any position, and the position of the functional group may be at the terminal or in the middle of the main chain. The conjugated diene polymer chain having a nitrogen atom can be obtained, for example, by a polymerization method using an organolithium compound having at least one nitrogen atom in the molecule as a polymerization initiator, as described below, or by a method of copolymerizing a monomer having at least one nitrogen atom in the molecule.

[0068] The modified conjugated diene polymer of this embodiment or the conjugated diene polymer described below may be further hydrogenated in an inert solvent to convert all or part of the double bonds into saturated hydrocarbons. In this case, heat resistance and weather resistance are improved, product deterioration during processing at high temperatures can be prevented, and the driving performance of the rubber tends to be improved. As a result, the polymer exhibits even better performance in various applications, such as automotive applications. More specifically, the hydrogenation rate of the unsaturated double bonds based on the conjugated diene compound can be selected arbitrarily depending on the purpose and is not particularly limited. When used as a vulcanizate, it is preferable that the double bonds of the conjugated diene moiety remain partially. From this perspective, the hydrogenation rate of the conjugated diene moiety in the conjugated diene polymer is preferably 3.0% to 70% inclusive, more preferably 5.0% to 65% inclusive, and even more preferably 10% to 60% inclusive. In particular, selective hydrogenation of vinyl groups tends to improve heat resistance and driving performance. The hydrogenation rate can be determined by nuclear magnetic resonance (NMR) spectroscopy.

[0069] <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" 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).

[0070]

[0071]

[0072] 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. １ ~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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] In the modified conjugated diene polymer of the present embodiment, the coupling structure centered on a nitrogen-containing alkoxysilane substituent is such that the nitrogen-containing alkoxysilane modifier residue has at least four silicon atoms and an alkoxy group and / or a hydroxy group, and a modified conjugated diene polymer chain having a main chain branched structure is bonded to the silicon atom, and it is preferable that the number of the alkoxy groups and / or the hydroxy groups in the modifier residue described below is greater on average than the number of the silicon atoms.

[0080] <Modifier Residue Having Silicon Atom> The modified conjugated diene polymer of the present embodiment preferably has a silicon atom in the modifier residue. For example, the modified conjugated diene polymer has a structural unit derived from a modifier, which is obtained by adding a silicon atom to a modifier described below.

[0081] The modified conjugated diene polymer of this embodiment preferably has a silicon atom at any position. The silicon atom is preferably bonded as a silicon-atom-containing functional group to the end of the conjugated diene polymer chain or in the middle of the main chain, or is preferably contained in a modifier residue. It is more preferable that at least one silicon atom possessed by this modified conjugated diene polymer constitutes an alkoxysilyl group or silanol group having 1 to 20 carbon atoms. This tends to strengthen the interaction with a filler, such as silica, added when forming a vulcanizate. Furthermore, from the viewpoint of the possibility of generating hydrogen halide upon reaction with air, the modified conjugated diene polymer preferably does not contain a halogen.

[0082] It is preferable that at least one end of the eight or more conjugated diene polymer chains is bonded to a silicon atom possessed by the modifier residue. This tends to make the effects of this embodiment more pronounced. In this case, the ends of a plurality of conjugated diene polymer chains may be bonded to one silicon atom. Alternatively, an end of a conjugated diene polymer chain and an alkoxy group or hydroxyl group having 1 to 20 carbon atoms may be bonded to one silicon atom, and as a result, that one silicon atom may constitute an alkoxysilyl group or silanol group having 1 to 20 carbon atoms. From the viewpoint that hydrogen halide may be generated upon reaction with air or moisture, it is preferable that the modifier residue does not contain a halogen.

[0083] 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.

[0084] <Modified Conjugated Diene Polymer Having a Star Polymer Structure> A modified conjugated diene polymer having a star polymer structure is a conjugated diene polymer having a three- or more branched star polymer structure constructed by constructing a branched structure derived from a main chain branch structure, continuing polymerization to increase the molecular weight, and then modifying with a tri- or higher functional coupling modifier. Such a modified 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 a method for obtaining a conjugated diene polymer having a further main chain branched 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 branched 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.

[0085] The modified conjugated diene polymer of the present embodiment preferably contains, in its star-branched structure portion, 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).

[0086]

[0087]

[0088]

[0089]

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] (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.

[0095] 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).

[0096]

[0097]

[0098]

[0099] R ２４ , R ２５ , R ２６ may be bonded to each other to form a cyclic structure.

[0100] Also, R ２６When 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.

[0101] 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.

[0102] 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.

[0103]

[0104]

[0105] In 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 portion 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.

[0106]

[0107] In formula (8), P ８ , P ９ , P １０ is a polymer chain, which is a forked portion [A] having a main chain branched structure portion 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.

[0108]

[0109]

[0110] In formulas (9-1) to (9-2), P １１ ~P １４ is a polymer chain, which is a forked portion [A] having a main chain branched structure portion 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 ５５represents 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.

[0111] In the formulas (9-1) and (9-2), A is preferably represented by any one of the following general formulas (I) to (IV).

[0112]

[0113] In 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.

[0114]

[0115] In 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.

[0116]

[0117] In 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.

[0118]

[0119] In 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.

[0120] [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 product of the present embodiment is more preferably a block-shaped molded product, and the shape of the block is preferably a roughly rectangular parallelepiped, and the block shape is preferably 1,000 cm or less. ３ The 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] The molding compression pressure for the molded body 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. When the molding compression pressure is 3 MPa or more, moldability is good. When moldability is good, the surface of the molded body is smooth, there is no peeling of the polymer after the molding process, and expansion after molding tends to be suppressed.

[0125] 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.

[0126] 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 (polyethylene terephthalate). 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.

[0127] [Method for producing modified conjugated diene polymer] The method for producing the modified conjugated diene polymer of this embodiment will be described in detail below. By using the method for producing the modified conjugated diene polymer of this embodiment, the above-mentioned conjugated diene polymer can be obtained reliably and simply, but the modified conjugated diene polymer of this embodiment is not limited to those produced by the following production method.

[0128] The method for producing a modified conjugated diene polymer of this embodiment includes: a step of polymerizing at least a conjugated diene compound in the presence of an organolithium compound having at least one nitrogen atom in the molecule; and a branching step of using a branching agent to obtain a branched modified conjugated diene polymer having a main chain branched structure (hereinafter, these steps may be collectively referred to as a polymerization branching step). In the step of coupling the branched modified conjugated diene polymer using a coupling agent and / or the step of modifying the branched modified conjugated diene polymer with a modifier having a nitrogen atom-containing group, the coupling agent and / or the modifier are added in excess. The step of coupling using a coupling agent and / or the step of modifying the branched modified conjugated diene polymer with a modifier having a nitrogen atom-containing group may be a step of adding a coupling modifier. In the method for producing a conjugated diene polymer of this embodiment, it is preferable to add an excess of a modifier having a coupling number of 4 or more as the coupling modifier.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] In the production method of the present embodiment, from the viewpoint of being able to obtain a conjugated diene-based polymer having an active end at a high rate, 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.

[0134] (Polymerization-branching step) In the method for producing a conjugated diene polymer of this embodiment, the polymerization-branching step is a step of obtaining a conjugated diene polymer having a branched structure by polymerizing at least a conjugated diene compound and, if necessary, a vinyl aromatic compound using an organolithium compound having at least one nitrogen atom in the molecule as described below as a polymerization initiator, while adding a branching agent. 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.

[0135] 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.

[0136] <Polymerization Initiator> A specific polymerization initiator is used in the polymerization step. As the polymerization initiator, as described above, an organolithium compound is used, and preferably, an organolithium compound having at least one nitrogen atom in the molecule is used. The organolithium compound is an organomonolithium compound, and other polymerization initiators may be used in combination. The organolithium compound is not limited to the following, but examples thereof include low molecular weight compounds and solubilized oligomeric organomonolithium compounds. Furthermore, examples of the organomonolithium compound include, in terms of the bonding mode between the organic group and the lithium, compounds having a carbon-lithium bond, compounds having a nitrogen-lithium bond, and compounds having a tin-lithium bond.

[0137] The amount of the organic monolithium compound used as a polymerization initiator is preferably determined based on the molecular weight of the target conjugated diene polymer or modified conjugated diene polymer. The amount of the monomer, such as the conjugated diene compound, used relative to the amount of the polymerization initiator tends to be related to the degree of polymerization, i.e., the number average molecular weight and / or the weight average molecular weight. Therefore, to increase the molecular weight, it is advisable to adjust the amount of the polymerization initiator to decrease, and to decrease the molecular weight, it is advisable to adjust the amount of the polymerization initiator to increase.

[0138] The organic monolithium compound is preferably an alkyllithium compound having a substituted amino group or a substituted aminolithium compound, from the viewpoint that it can be used as one method for introducing nitrogen atoms into a conjugated diene polymer. In this case, a conjugated diene polymer having a nitrogen atom at the polymerization initiation terminal resulting from the amino group is obtained. The substituted amino group is an amino group that does not have an active hydrogen or has a structure in which the active hydrogen is protected.

[0139] The organolithium compound having at least one nitrogen atom in the molecule as the polymerization initiator includes organolithium compounds represented by any of the following general formulas (1) to (5).

[0140]

[0141] (In formula (1), R １０ and R １１ each independently represents at least one selected from the group consisting of an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 14 carbon atoms, an aralkyl group having 6 to 20 carbon atoms, and a protecting group; R １０ and R １１ may be bonded to form a ring structure together with the adjacent nitrogen atom, in which case R １０ and R １１ represents an alkyl group having 5 to 12 carbon atoms, which may partially contain an unsaturated bond or a branched structure. The protecting group is an alkyl-substituted silyl group.

[0142]

[0143] (In formula (2), R １２ and R １３each independently represents at least one selected from the group consisting of an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 14 carbon atoms, an aralkyl group having 6 to 20 carbon atoms, and a protecting group; R １２ and R １３ may be bonded to form a ring structure together with the adjacent nitrogen atom, in which case R １２ and R １３ represents an alkyl group having 5 to 12 carbon atoms, which may partially contain an unsaturated bond or a branched structure. The protecting group is an alkyl-substituted silyl group. R １４ represents an alkylene group having 1 to 30 carbon atoms which may have an aliphatic or aromatic substituent, or a conjugated diene polymer having 1 to 20 carbon atoms.

[0144]

[0145] (In formula (3), R １２ and R １３ each independently represents at least one selected from the group consisting of an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 14 carbon atoms, an aralkyl group having 6 to 20 carbon atoms, and a protecting group; R １２ and R １３ may be bonded to form a ring structure together with the adjacent nitrogen atom, in which case R １２ and R １３ represents an alkyl group having 5 to 12 carbon atoms, which may partially contain an unsaturated bond or a branched structure. The protecting group is an alkyl-substituted silyl group. R １９ represents a hydrocarbon group having 1 to 30 carbon atoms which may have an aliphatic or aromatic substituent. ２０ represents a hydrocarbon group having 1 to 12 carbon atoms which may have a substituted amino group, and n represents an integer of 1 to 10.

[0146]

[0147] (In formula (4), R １５ and R １６ each independently represents at least one selected from the group consisting of an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 14 carbon atoms, an aryl group having 6 to 20 carbon atoms, and a protecting group; R １５ and R １６may be bonded to form a ring structure together with the adjacent nitrogen atom, in which case R １５ and R １６ represents an alkyl group having 5 to 12 carbon atoms, which may have a branched structure in part. The protecting group is an alkyl-substituted silyl group.

[0148]

[0149] (In formula (5), R １７ represents a hydrocarbon group having 2 to 10 carbon atoms, which may partially contain an unsaturated bond or a branched structure. １８ represents an alkyl group having 1 to 12 carbon atoms or a protecting group, which may have a branched structure in part. The protecting group is an alkyl-substituted silyl group.

[0150] In the formula (1), R １０ and R １１ R represents, for example, a methyl group, an ethyl group, a propyl group, a butyl group, an octyl group, a benzyl group, a cyclopropyl group, a cyclohexyl group, a 3-phenyl-1-propyl group, an isobutyl group, a decyl group, a heptyl group, and a phenyl group. １０ and R １１ is not limited to these and includes analogs thereof as long as the above conditions are satisfied. From the viewpoints of solubility in a solvent, reducing the hysteresis loss of the modified conjugated diene polymer composition described later, and controlling the chain transfer reaction described later, a butyl group and a hexyl group are preferred, and a butyl group is more preferred.

[0151] The organolithium compound having at least one nitrogen atom in the molecule represented by formula (1) is not limited to the following, but examples thereof include ethylpropylaminolithium, ethylbutylaminolithium, ethylbenzylaminolithium, dibutylaminolithium, dihexylaminolithium, etc., and among these, dibutylaminolithium and dihexylaminolithium are preferred, with dibutylaminolithium being more preferred.

[0152] In the formula (1), R １０ and R １１is bonded to form a cyclic structure together with the adjacent nitrogen atom, examples of the organolithium compound represented by formula (1) include, but are not limited to, piperidinolithium, hexamethyleneiminolithium, lithium azacyclooctane, lithium-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, 1,2,3,6-tetrahydropyridinolithium, and 3,5-dimethylpiperidinolithium. The organolithium compound having at least one nitrogen atom in the molecule is not limited to these and includes analogs thereof as long as the above conditions are met. From the viewpoints of solubility of the polymerization initiator in the solvent, reduction of the unpleasant odor of the modified conjugated diene polymer described below, and inhibition of chain transfer reactions, piperidinolithium, hexamethyleneiminolithium, lithium azacyclooctane, and lithium-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane are preferred, more preferably piperidinolithium, hexamethyleneiminolithium, and 3,5-dimethylpiperidinolithium, and even more preferably piperidinolithium.

[0153] In the formula (2), R １４ represents an alkylene group having 1 to 30 carbon atoms which may have an aliphatic or aromatic substituent, or a conjugated diene polymer having 1 to 20 carbon atoms. The conjugated diene polymer preferably represents a polymer having a conjugated diene compound having 4 to 12 carbon atoms as a repeating unit. Examples of conjugated diene compounds include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. Among these, 1,3-butadiene and isoprene are preferred from the viewpoint of industrial availability. These may be used alone or in combination of two or more.

[0154] In the formula (2), R １４ When R represents an alkylene group having 1 to 30 carbon atoms, in terms of reactivity and interaction with inorganic fillers such as carbon and silica, R １４preferably represents an alkylene group having 2 to 20 carbon atoms, and more preferably represents an alkylene group having 3 to 16 carbon atoms. １４ represents an alkylene group having 1 to 30 carbon atoms, examples of the organolithium compound represented by formula (2) include, but are not limited to, (3-(dimethylamino)-propyl)lithium, (3-(diethylamino)-propyl)lithium, (3-(dipropylamino)-propyl)lithium, (3-(dibutylamino)-propyl)lithium, (3-(dipentylamino)-propyl)lithium, (3-(dihexylamino)-propyl)lithium, (3-(dioctylamino)-propyl)lithium, (3-(ethylhexylamino)-propyl)lithium, (3-(didecylamino)-propyl)lithium, (3-(ethylpropylamino)-propyl)lithium, (3-(ethylbutylamino)-propyl)lithium, Examples of suitable organolithium compounds include (N,N-bistrimethylsilylaminopropyl)lithium, (3-(ethylbenzylamino)propyl)lithium, (3-(methylphenethylamino)propyl)lithium, (4-(dibutylamino)butyl)lithium, (5-(dibutylamino)pentyl)lithium, (6-(dibutylamino)hexyl)lithium, (10-(dibutylamino)decyl)lithium, (5-(dibutylamino)-1-phenylpentyl)lithium, (5-(dibutylamino)-1,1-diphenylpentyl)lithium, 3-N,N-bistrimethylsilylaminopropyllithium, 4-N-trimethylsilyl-N-methylaminobutyllithium, and 6-N-trimethylsilyl-N-butylaminohexyllithium. Organolithium compounds having at least one nitrogen atom in the molecule are not limited to these compounds, and include analogs thereof as long as they satisfy the above conditions. From the viewpoint of reactivity and interactivity with inorganic fillers such as carbon and silica, (3-(dibutylamino)propyl)lithium is more preferred.

[0155] In the formula (2), R １４When represents a conjugated diene polymer, examples of the organolithium compound represented by formula (2) include, but are not limited to, (4-(dimethylamino)-2-butenyl)lithium, (4-(diethylamino)-2-butenyl)lithium, (4-(dibutylamino)-2-butenyl)lithium, (4-(dipropylamino)-2-butenyl)lithium, (4-(diheptylamino)-2-butenyl)lithium, (4-(dihexylamino)-2-butenyl)lithium, (4-(dioctylamino)-2-butenyl)lithium, (4-(di-2-ethylhexylamino)-2-butenyl)lithium, (4-(didecylamino)-2-butenyl)lithium, (4-(ethylpropylamino)-2-butenyl)lithium, (4-(ethylbutylamino)-2-butenyl)lithium, (4-(ethylbenzylamino)-2-butenyl)lithium, (4-(methylphenethylamino)-2-butenyl)lithium, (4-(dimethylamino)-2-methyl-2-butenyl)lithium (4-(diethylamino)-2-methyl-2-butenyl)lithium, (4-(dibutylamino)-2-methyl-2-butenyl)lithium, (4-(dipropylamino)-2-methyl-2-butenyl)lithium, (4-(diheptylamino)-2-methyl-2-butenyl)lithium, (4-(dihexylamino)-2-methyl-2-butenyl)lithium, (4-(dimethylamino)-3-methyl-2-butenyl)lithium, (4-(diethylamino)-3-methyl-2-butenyl) Examples of organolithium compounds include lithium, (4-(dibutylamino)-3-methyl-2-butenyl)lithium, (4-(dipropylamino)-3-methyl-2-butenyl)lithium, (4-(diheptylamino)-3-methyl-2-butenyl)lithium, (4-(dihexylamino)-3-methyl-2-butenyl)lithium, a reaction product of 1 mole of piperidinolithium with 3 moles of 1,3-butadiene, and a reaction product of 3-N,N-bistrimethylsilylaminopropyllithium with 3 moles of 1,3-butadiene. The organolithium compounds having at least one nitrogen atom in the molecule are not limited to these compounds, and include analogs thereof as long as they satisfy the above conditions.From the viewpoint of reactivity as an initiator and control of a chain transfer reaction, which will be described later, 4-(dimethylamino)-2-butenyl)lithium, (4-(diethylamino)-2-butenyl)lithium, and (4-(dibutylamino)-2-butenyl)lithium are preferred, and (4-(dibutylamino)-2-butenyl)lithium is more preferred.

[0156] In formula (2), R １２ and R １３are bonded to form a cyclic structure together with the adjacent nitrogen atom, examples of the organolithium compound represented by formula (2) include (3-(piperidinyl)propyl)lithium, (3-(hexamethyleneiminyl)propyl)lithium, (3-(heptamethyleneiminyl)propyl)lithium, (3-(octamethyleneiminyl)propyl)lithium, (3-(1,3,3-trimethyl-6-azabicyclo[3.2.1]octanyl)propyl)lithium, (3-(1,2,3,6-tetrahydropyridinyl)propyl)lithium, (2-(hexamethyleneiminyl)ethyl)lithium, (4-(hexamethyleneiminyl)butyl)lithium, (5-(hexamethyleneiminyl)pentyl)lithium, (6-(hexamethyleneiminyl)propyl)lithium, (4-(hexamethyleniminyl)hexyl)lithium, (10-(hexamethyleniminyl)decyl)lithium, (4-(piperidinyl)-2-butenyl)lithium, (4-(hexamethyleniminyl)-2-butenyl)lithium, (4-(heptamethyleneiminyl)-2-butenyl)lithium, (4-(octamethyleneiminyl)-2-butenyl)lithium, (4-(1,3,3-trimethyl-6-azabicyclo[3.2.1]octanyl)-2-butenyl)lithium, (4-(1,2,3,6-tetrahydropyridinyl)-2-butenyl)lithium, (4-(hexamethyleniminyl)-2-methyl-2-butenyl)lithium, (4-(hexamethyleniminyl)-3-methyl-2-butenyl)lithium, and the like. The organolithium compounds having at least one nitrogen atom in the molecule are not limited to these, and include analogs thereof as long as they satisfy the above conditions.From the viewpoint of reactivity and interactivity with inorganic fillers such as carbon and silica, and from the viewpoint of controlling chain transfer reactions, which will be described later, (3-(piperidinyl)propyl)lithium, (3-(hexamethinleniminyl)propyl)lithium, (3-(1,2,3,6-tetrahydropyridinyl)propyl)lithium, (4-(piperidinyl)-2-butenyl)lithium, and (4-(hexamethinleniminyl)-2-butenyl)lithium are preferred, and (3-(hexamethinleniminyl)propyl)lithium, (4-(piperidinyl)-2-butenyl)lithium, and (4-(hexamethinleniminyl)-2-butenyl)lithium are more preferred, and (4-(piperidinyl)-2-butenyl)lithium is more preferred.

[0157] In formula (3), R １２ and R １３ is R in formula (2). １２ and R １３ The organolithium compound having at least one nitrogen atom in the molecule represented by formula (3) may be a reaction product of an organomonolithium compound and an organic unsaturated compound having a substituted amino group. In this case, R ２０ is an organic group derived from an organomonolithium compound, and R １９ is an alkylene compound derived from an organic unsaturated compound having a substituted amino group. When the organic monolithium compound has a substituted amino group, R ２０is a hydrocarbon group having a substituted amino group. As the organic unsaturated compound having a substituted amino group, known organic unsaturated compounds having a substituted amino group that undergo addition reaction with a lithium-based initiator are used, including vinyl aromatic compounds having a substituted amino group and conjugated diene compounds having a substituted amino group. The organic lithium compound having at least one nitrogen atom in the molecule represented by formula (3) is not limited to the following, but examples thereof include 1-(4-N,N-dimethylaminophenyl)hexyllithium, 1-(4-N,N-dimethylaminophenyl)-1-phenylhexyllithium, 1-(4-N,N-dimethylaminomethylphenyl)hexyllithium, 1-(4-N,N-bistrimethylsilylaminophenyl)hexyllithium, 1-(4-N-trimethylsilyl-N-ethylaminophenyl)hexyllithium, 1-(4-N,N-bistrimethylsilylaminophenyl)-1-phenylhexyllithium, reaction product of 1 mole of butyllithium with 2 moles of 4-N,N-dimethylaminostyrene, reaction product of 1 mole of sec-butyllithium with 4 moles of 4-N,N-bistrimethylsilylaminostyrene, reaction product of 1 mole of butyllithium with 4 moles of 2-N,N-dimethylamino-1,3-butadiene, reaction product of 1 mole of piperidinolithium with 2 moles of 4-N,N-dimethylaminostyrene, reaction product of 3-N,N-bistrimethylsilylaminopropyllithium with 2 moles of 4-N,N-dimethylaminostyrene, and the like.

[0158] The organolithium compound having at least one nitrogen atom in the molecule represented by the formula (4) includes a reaction product of an N-substituted orthotoluidine compound with an alkyllithium. The organolithium compound having at least one nitrogen atom in the molecule represented by formula (4) is not limited to the following, but examples thereof include N,N-dimethyl-o-toluidino lithium, N,N-dimethyl-m-toluidino lithium, N,N-dimethyl-p-toluidino lithium, N,N-diethyl-o-toluidino lithium, N,N-diethyl-m-toluidino lithium, N,N-diethyl-p-toluidino lithium, N,N-dipropyl-o-toluidino lithium, N,N-dipropyl-m-toluidino lithium, N,N-dipropyl-p-toluidino lithium, N,N-dibutyl-o-toluidino lithium, N,N-dibutyl-m-toluidino lithium, N,N-dibutyl-p-toluidino lithium, o-piperidinotoluenolithium, Examples of organolithium compounds include lithium, p-piperidinotoluenolithium, o-pyrrolidinotoluenolithium, p-pyrrolidinotoluene, N,N,N',N'-tetramethyltoluylenediaminolithium, N,N,N',N'-tetraethyltoluylenediaminolithium, N,N,N',N'-tetrapropyltoluylenediaminolithium, N,N-dimethylxylidinolithium, N,N-diethylxylidinolithium, N,N-dipropylxylidinolithium, N,N-dimethylmesidinolithium, N,N-diethylmesidinolithium, (N,N-dimethylamino)toluylphenylmethylaminolithium, 1-(N,N-dimethylamino)-2-methylnaphthalenolithium, and 1-(N,N-dimethylamino)-2-methylanthracenolithium. Organolithium compounds having at least one nitrogen atom in the molecule are not limited to these compounds, and include analogs thereof as long as they satisfy the above conditions. From the viewpoint of polymerization activity, N,N-dimethyl-o-toluidino lithium is more preferred.

[0159] The organolithium compound having at least one nitrogen atom in the molecule represented by formula (4) is not limited to the following, but an example thereof includes 2-(2-methylpiperidinyl)-1-ethyllithium (for example, trade name "AI-250" manufactured by FMC Corporation).

[0160] The organolithium compound is not limited to these, and includes analogs thereof as long as the above conditions are met. Prior to the polymerization step, an organolithium compound having at least one nitrogen atom in the molecule or other organolithium compounds may be prepared in advance, and any known method can be used for this purpose.

[0161] In the above-mentioned polymerization step, when obtaining a nitrogen-containing conjugated diene polymer, a step of copolymerizing at least a conjugated diene compound and a copolymerizable monomer having at least one nitrogen atom in the molecule in the presence of an organolithium compound may be carried out. As the copolymerizable monomer having at least one nitrogen atom in the molecule, a known organic unsaturated compound having a substituted amino group that copolymerizes with a conjugated diene compound in the presence of a lithium initiator is used, and includes a vinyl aromatic compound having a substituted amino group and a conjugated diene compound having a substituted amino group.

[0162] The organolithium compound is preferably an organomonolithium compound, which may or may not have a substituted amino group in the molecule. From the viewpoints of industrial availability and ease of control of the polymerization reaction, an alkyllithium compound is preferred. In this case, a conjugated diene polymer having an alkyl group at the polymerization initiation terminal is obtained. Examples of the alkyllithium compound include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium. From the viewpoints of industrial availability and ease of control of the polymerization reaction, n-butyllithium and sec-butyllithium are preferred as the alkyllithium compound.

[0163] The substituted amino group is an amino group in which each hydrogen atom of the amino group is independently substituted with at least one selected from the group consisting of an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 14 carbon atoms, an aralkyl group having 6 to 20 carbon atoms, and a protecting group, and the substituents may bond to form a cyclic structure together with the adjacent nitrogen atom, in which case the substituent is an alkyl group having 5 to 12 carbon atoms, which may have an unsaturated bond or a branched structure in part. The protecting group is preferably an alkyl-substituted silyl group.

[0164] From the viewpoint of reliably and simply obtaining the conjugated diene polymer of this embodiment, 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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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 using 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.

[0169] 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.

[0170] 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.

[0171] The method for producing a modified conjugated diene polymer of this embodiment may include a step of removing impurities prior to the polymerization / branching step. In particular, when the above-described monomer, polymerization initiator, and / or inert solvent contain allenes and acetylenes as impurities, it is preferable to include a step of removing impurities prior to the polymerization / branching step. By including a step of removing impurities, a modified 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. Examples of such a step of removing impurities include, but are not limited to, a step of treating with an organometallic compound. Examples of such organometallic compounds include, but are not limited to, organolithium compounds, and examples of organolithium compounds include, but are not limited to, n-butyllithium.

[0172] In the polymerization-branching step, a branching reaction is initiated in the modified conjugated diene polymer by adding a branching agent described below. After the branching agent is added, a polymerization reaction in which the modified conjugated diene polymer grows and a branching reaction in which the modified 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 modified 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.

[0173] Furthermore, by adding a branching agent during polymerization of the modified 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 having the bound vinyl aromatic compound amount and the vinyl bond amount within the above-mentioned specified range, the coupling rate and / or modification rate of the polymerization terminal can be easily improved. However, it is not essential that the conjugated diene polymer of this embodiment be reacted with a coupling modifier.

[0174] As described above, in the method for producing a modified 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 compound and the amount of vinyl bond. The amount of polar compound typically used to set the amount of bound vinyl aromatic compound and the amount of vinyl bond 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, and in the conjugated diene polymer of this embodiment, in which the amount of bound vinyl aromatic compound and the amount of vinyl bond are within the above-mentioned ranges, the polymerization terminals tend to be vinyl aromatic compounds. Under such conditions, it tends to be difficult to obtain a conjugated diene polymer with a high coupling rate or modification rate. That is, since the method for producing a modified conjugated diene polymer of this embodiment uses a branching agent, even with an amount of polar compound that does not normally easily maintain the activity of the polymerization active terminals, the active terminals of the polymer can be sufficiently maintained, and a high coupling rate and modification rate can be achieved.

[0175] 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.

[0176] The branching agent is not particularly limited, but for example, a compound represented by the following formula (10) or formula (11) can be used.

[0177]

[0178]

[0179] (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, 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. １ ~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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] 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 tribromo(3-vinylphenyl)silane, tribromo(2-vinylphenyl)silane, dichloromethyl(4-vinylphenyl)silane, dichloromethyl(3-vinylphenyl)silane, dichloromethyl(2-vinylphenyl)silane, dibromomethyl(4-vinylphenyl)silane, dibromomethyl(3-vinylphenyl)silane, dibromomethyl(2-vinylphenyl)silane, dimethylchloro(4-vinylphenyl)silane, dimethylchloro(3-vinylphenyl)silane, dimethylchloro(2-vinylphenyl)silane, dimethylbromo(4-vinylphenyl)silane, dimethylbromo(3-vinylphenyl)silane, dimethylbromo(2-vinylphenyl)silane, and the like.

[0187] Among these, trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane, trimethoxy(3-vinylphenyl)silane, triethoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)silane, tributoxy(3-vinylphenyl)silane, triisopropoxy(3-vinylphenyl)silane, and trichloro(4-vinylphenyl)silane are preferred, and trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, and tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane are more preferred.

[0188] 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 silyl groups 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.

[0189] 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.

[0190] 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 polymer, and as the amount added increases, the overall degree of branching and the degree of branching at the extreme values ​​increase.

[0191] In the polymerization branching step, the reaction temperature may or may not be changed after the branching agent is added.

[0192] In the polymerization branching step, after adding the branching agent, a monomer 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.

[0193] 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, 10.0% or more, 15.0% or more, or 20.0% or more of the total amount of monomers used in the conjugated diene polymer. The amount of the added monomer may be 50.0% or less, 40.0% or less, or 35.0% or less. When the amount of the added monomer is within the above range, the molecular weight between the branching point generated by adding the branching agent and the branching point generated by adding the coupling modifier is increased, and therefore, 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.

[0194] (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 described above.

[0195] 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.

[0196] 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.

[0197] Preferable coupling modifiers having a nitrogen atom-containing group include amine compounds having no active hydrogen, protected amine compounds in which active hydrogen is substituted with a protecting group, imine compounds represented by 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.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] 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-pyrrolid ... dipyridyl ketone, methyl-4-pyridyl ketone, propyl-2-pyridyl ketone, di-4-pyridyl ketone, 2-benzoylpyridine, N,N,N',N'-tetramethylurea, N,N-dimethyl-N',N'-diphenylurea, N,N-methyl diethylcarbamate, N,N-diethylacetamide, N,N-dimethyl-N',N'-dimethylaminoacetamide, N,N-dimethylpicolinic acid amide, and N,N-dimethylisonicotinic acid amide.

[0202] Examples of the nitrogen atom-containing vinyl compound 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.

[0203] Examples of nitrogen-containing epoxy compounds include, but are not limited to, hydrocarbon compounds containing an epoxy group bonded to an amino group. The hydrocarbon compounds may further contain 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):

[0204]

[0205] 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.

[0206] 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.

[0207] 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 ２６ may 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.

[0208]

[0209] 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.

[0210] 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.

[0211] Examples of the nitrogen atom-containing epoxy compound include, but are not limited to, N,N-diglycidyl-4-glycidoxyaniline, 1-N,N-diglycidylaminomethyl-4-glycidoxy-cyclohexane, 4-(4-glycidoxyphenyl)-(N,N-diglycidyl)aniline, 4-(4-glycidoxyphenoxy)-(N,N-diglycidyl)aniline, 4-(4-glycidoxybenzyl)-(N,N-diglycidyl)aniline, 4-(N,N'-diglycidyl-2-piperazinyl)-glycidoxybenzene, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylenediamine 4,4-methylene-bis(N,N-diglycidylaniline), 1,4-bis(N,N-diglycidylamino)cyclohexane, N,N,N',N'-tetraglycidyl-p-phenylenediamine, 4,4'-bis(diglycidylamino)benzophenone, 4-(4-glycidylpiperazinyl)-(N,N-diglycidyl)aniline, 2-[2-(N,N-diglycidylamino)ethyl]-1-glycidylpyrrolidine, N,N-diglycidylaniline, 4,4'-diglycidyl-dibenzylmethylamine, N,N-diglycidylaniline, N,N-diglycidylorthotoluidine, and N,N-diglycidylaminomethylcyclohexane. Among these, preferred are N,N-diglycidyl-4-glycidoxyaniline and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

[0212] Examples of the imine compound 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)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).

[0213] Examples of the nitrogen atom-containing alkoxysilane compound 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)propyltrimethoxysilane, 1-[3-( 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-methyl amine, bis(3-triethoxysilylpropyl)methylamine, tris(trimethoxysilyl)amine, tris(3-trimethoxysilylpropyl)amine, N,N,N',N'-tetra(3-trimethoxysilylpropyl)ethylenediamine, 3-isocyanatopropyltrimethoxysilane, 3-cyanopropyltrimethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-dimethoxy-8-(N,N-diethylamino)methyl-1,6-dioxa-2-silacyclooctane, etc.

[0214] 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- 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.

[0215] 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.

[0216] 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.

[0217] 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 amine, N-(1-methylpropylidene)-3-methyl(diethoxysilyl)-1-propanamine, N-benzylidene-3-methyl(dimethoxysilyl)propan-1-amine, N-benzylidene-3-methyl(diethoxysilyl)propan-1-amine, N-4-methylbenzylidene-3-(triethoxysilyl)propan-1-amine, N-4-methylbenzylidene-3-(trimethoxysilyl)propan-1-amine, N-4-methylbenzylidene-3-methyl(dimethoxysilyl)propan-1-amine, N-4-methylbenzylidene-3-methyl(diethoxysilyl)propan-1-amine, N-naphthylidene-3-(triethoxysilyl)propan-1-amine, N-naphthylidene-3-(trimethoxysilyl)propan-1-amine, N-naphthylidene-3-methyl(dimethoxysilyl)propan-1-amine, 1,1-(1,4-furan)

[0033] Examples of such amines include 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.

[0218] 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.

[0219]

[0220] 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, and R １３ 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. d is an integer of 1 to 3.

[0221]

[0222] 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.

[0223]

[0224] 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.

[0225]

[0226] 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.

[0227]

[0228] 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.

[0229] 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.

[0230] 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 formula (16) is 3 are preferred. Specifically, 1-methyl-4-(3-(trimethoxysilyl)propyl)piperazine and 1-methyl-4-(3-(triethoxysilyl)propyl)piperazine are preferred.

[0231] 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.

[0232] 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.

[0233] More specifically, the amounts of the polymerization initiator and the coupling modifier represented by 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 formula (14).

[0234] 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, 2-methoxy-2-methyl-1-(methylisobutylideneaminoethyl)-1-aza-2-silacyclopentane, and the like.

[0235] 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 carry out the reaction at 0°C or higher and 120°C or lower for 30 seconds or longer.

[0236] 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.

[0237] 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).

[0238] 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-silacyclohexane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacycloheptane, 2,2-dimethoxy-1-(5-trimethoxysilylpropyl)-1-aza-2-silacyclohexane ... -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, 2-ethoxy,2-ethyl-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane, and the like.

[0239] 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 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.

[0240] 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.

[0241] 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.

[0242] 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).

[0243] 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.

[0244] Among these, from the viewpoints of reactivity and interaction between the functional group of the modifier and an inorganic filler such as silica, as well as processability, it is preferable that n, m, and l all represent 3. Preferred specific examples include tris(3-trimethoxysilylpropyl)amine and tris(3-triethoxysilylpropyl)amine.

[0245] 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.

[0246] 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.

[0247] 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.

[0248] In the formula (18), A is preferably represented by any one of the following general formulae (i) to (iv).

[0249]

[0250] In 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.

[0251]

[0252] In 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.

[0253]

[0254] In 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.

[0255]

[0256] In 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.

[0257] 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-

[0033] Examples thereof include 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, and tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-propanediamine.

[0258] 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 Examples of such aminomethylcyclohexane include 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, and tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane.

[0259] 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,Examples of such amines include 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.

[0260] In the formula (18), when A is represented by the formula (ii), examples of the coupling modifier having a nitrogen atom-containing group include, but are not limited to, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, bis(2-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3-propanediamine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, tris(3-triethoxysilylpropyl)-methyl-1,3-propanediamine, bis(2-triethoxysilylpropyl)-[3-(2,2 -diethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3-propanediamine, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-methyl-1,3-propanediamine, N1,N1'-(propane-1,3-diyl)bis(N1-methyl-N3,N3-bis(3-(trimethoxysilyl)propyl)-1,3-propanediamine), N1-(3-(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N1-methyl-N3-(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N3-(3-(trimethoxysilyl)propyl)-1,3-propanediamine, and the like.

[0261] 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-

[0034] Examples thereof include bis[3-(1-sila-2-azacyclopentane)propyl]-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-bis(3-trimethoxysilylpropyl)silane, and bis(3-trimethoxysilylpropyl)-bis[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]silane.

[0262] In the formula (18), when A is represented by formula (iv), examples of the modifying agent having a nitrogen atom-containing group include, but are not limited to, 3-tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-(2,2-dimethoxy-1-aza-2-silacyclopentane)propane and 3-tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-trimethoxysilylpropane.

[0263] In the formula (18), A is preferably represented by formula (i) or formula (ii), and s is 0.

[0264] 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-

[0033] tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trismethoxysilylpropyl)-methyl-1,3-propanediamine, and the like.

[0265] 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.

[0266] This tends to result in better abrasion resistance and low hysteresis loss performance when vulcanized.

[0267] 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, 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.

[0268] 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 conjugated diene polymer to 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.

[0269] 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.

[0270] 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.

[0271] The method for producing a conjugated diene-based polymer of the present embodiment 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.

[0272] The method for producing a conjugated diene-based polymer of the present embodiment may further include a modification step using a modifier other than the above-mentioned coupling modifier.

[0273] In the method for producing a conjugated diene polymer of this embodiment, 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, it is preferable to use a combination of coupling modifiers with different numbers of functional groups. Furthermore, when three or more types of coupling modifiers are added, it is preferable to use a combination of coupling modifiers with different numbers of functional groups.

[0274] In the step of adding the coupling modifier, it is preferable to add two types of coupling modifiers with different numbers of functional groups. Examples of a combination of two types of coupling modifiers with different numbers of functional groups include a combination of a coupling modifier with two or less functional groups and a coupling modifier with three or more functional groups. It is preferable to add multiple types of coupling modifiers simultaneously, and they may or may not be mixed in advance.

[0275] 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.

[0276] 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.

[0277] 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.

[0278] In the method for producing a conjugated diene polymer of this embodiment, after the coupling step using a coupling modifier, a deactivator and / or a neutralizer may be added to the polymer solution as needed.

[0279] Examples of the quenching agent include, but are not limited to, water and alcohols such as methanol, ethanol, and isopropanol.

[0280] 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.

[0281] The method for producing a conjugated diene polymer of this embodiment may include a step of obtaining the obtained conjugated diene polymer from a polymer solution. As such a method, a known method can be used, and for example, the following methods can be used. Specifically, examples include a method in which the solvent is separated by steam stripping or the like, the polymer is filtered, and then the polymer is dehydrated and dried to obtain a polymer; a method in which the polymer is concentrated in a flashing tank and then devolatilized using a vent extruder or the like to obtain a polymer; and a method in which the polymer is directly devolatilized using a drum dryer or the like to obtain a polymer.

[0282] [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.

[0283] The rubber softener is not particularly limited, but examples thereof include extender oil, liquid rubber, and resin.

[0284] 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.

[0285] 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.

[0286] 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.

[0287] 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.

[0288] The veil of this embodiment contains 100 parts by mass of the modified conjugated diene polymer of this embodiment and 2 parts by mass or less of a softener component. The veil of this embodiment may also contain 100 parts by mass of the modified conjugated diene 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 polymer of this embodiment or the veil of this embodiment per 100 parts by mass of the total amount of the rubber component.

[0289] 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 the vulcanizate has 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.

[0290] 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.

[0291] 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 ３Solid 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.

[0292] 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.

[0293] 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.

[0294] 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.

[0295] 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.

[0296] Examples of metal hydroxides include, but are not limited to, aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0297] 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.

[0298] 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.

[0299] 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.

[0300] 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.

[0301] 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."

[0302] 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.

[0303] 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.

[0304] 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.

[0305] Examples of natural rubber include, but are not limited to, smoked sheets RSS3 to 5, SMR, and epoxidized natural rubber.

[0306] 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.

[0307] 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.

[0308] 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.

[0309] 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.

[0310] 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.

[0311] 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.

[0312] 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).

[0313] 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.

[0314] 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.

[0315] 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.

[0316] 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.

[0317] 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.

[0318] 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.

[0319] 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.

[0320] 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.

[0321] [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.

[0322] 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.

[0323] 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.

[0324] (Property 1) Average Molecular Weight Measured by GPC Measurement Using an unmodified conjugated diene polymer and a modified conjugated diene polymer as samples, GPC measurement was performed using a GPC measurement device (manufactured by Tosoh Corporation under the trade name "HLC-8320GPC") equipped with three connected 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 5 mmol / L triethylamine-THF (tetrahydrofuran) solution was used as the eluent. Three columns, manufactured by Tosoh Corporation under the trade name "TSKgel SuperMultiporeHZ-H", were connected, and a Tosoh Corporation product name "TSKguardcolumn SuperMP(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 the GPC measurement device and measured under conditions of an oven temperature of 40 ° C. and a THF flow rate of 0.35 mL / min. The measurement results were used as the average molecular weight of each sample.

[0325] (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.

[0326] (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.

[0327] (Physical Properties 4, 8) Degree of Branching (Bn) and Absolute Molecular Weight 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 viscosity detector (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 viscosity detector. The linear polymer had an intrinsic viscosity [η ０ ]=10 －３．４９８ M ０．７１１ The 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, an absolute molecular weight distribution curve and a 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').

[0328] (Property 5) Modification Ratio The modification ratio of a modified conjugated diene polymer was measured by column adsorption GPC as follows. The column adsorption GPC method is a method for determining the modification ratio of a modified polymer by utilizing the property that the modified basic polymer component in a modified conjugated diene polymer is easily adsorbed onto a GPC column filled with silica gel. Using the modified conjugated diene polymer as a sample, a sample solution containing the sample and a low-molecular-weight internal standard polystyrene was measured using a polystyrene column. In addition, a similar sample solution was measured using a silica column. The amount of modified conjugated diene polymer adsorbed onto the silica column was measured, and the modification ratio was determined by calculating the difference between the chromatogram obtained by measurement using the polystyrene column and the chromatogram obtained by measurement using the silica column.

[0329] <Preparation of sample solution>: 10 mg of sample and 5 mg of standard polystyrene were dissolved in 10 mL of THF to prepare a sample solution. The modification rate of the modified conjugated diene polymer was measured under the following measurement conditions.

[0330] <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 5 mmol / L 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 following conditions: a column oven temperature of 40 ° C., and a THF flow rate of 0.35 mL / min. Three Tosoh Corporation product name "TSKgel SuperMultiporeHZ-H" columns were connected, and a Tosoh Corporation product name "TSKguardcolumn SuperMP(HZ)-H" was connected in front of the columns as a guard column.

[0331] <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.

[0332] 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)

[0333] (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 a measurement sample was prepared by dissolving the sample in 100 mL of chloroform. 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.

[0334] (Physical Property 7) Amount of vinyl bond in bound conjugated diene (amount of 1,2-vinyl bond in bound butadiene) A measurement sample was prepared by dissolving 50 mg of a modified conjugated diene polymer in 10 mL of carbon disulfide. The infrared spectrum of each sample was measured from 600 to 1000 cm. －１The 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)).

[0335] (Physical Property 9) Glass Transition Temperature DSC measurement was carried out on the modified conjugated diene polymer as a sample using a differential scanning calorimeter (trade name "DSC3200S" manufactured by Mac Science) in accordance with ISO 22768: 2006. A DSC curve was recorded while heating from -100°C at 20°C / min under a helium flow of 50 mL / min, and the peak top (inflection point) of the DSC differential curve was taken as the glass transition temperature.

[0336] (Property 10) Antioxidant (Stabilizer) Content (Stabilizer Content) The antioxidant content in the modified conjugated diene polymer was measured by HPLC analysis as follows. HPLC analysis is a method in which 5.0 μL of a sample solution adjusted to a concentration of 100 mg / 10 mL (using a solvent of THF:MeOH=1:1) is added to an Agilent Technologies LC1260 Infinity or equivalent, and the column temperature is 35° C., the flow rate is 2.5 mL / min, and the developing solvent composition is changed using THF (tetrahydrofuran) and methanol according to the time table described below, followed by separation and analysis based on UV detection intensity to determine the amount of modified antioxidant added in the modified conjugated diene polymer.

[0337] (Property 11) Nitrogen Atom Content (ppm by mass) Using a modified conjugated diene polymer as a sample, measurement was carried out in accordance with JIS-2609: Crude oil and petroleum products - Nitrogen content test method, chemiluminescence method. The measurement device used was a trace total nitrogen analyzer ("TN-2100H" manufactured by Mitsubishi Chemical Analytech Co., Ltd.). The measurement method involved pyrolyzing a sample in a flow of argon gas, followed by combustion and oxidation with oxygen gas to produce nitric oxide, which was then subjected to an oxidation reaction with ozone gas under dehydration conditions, and the luminescence intensity at 590 to 2500 nm detected was measured, and the nitrogen content was determined from the area value of the luminescence intensity.

[0338] (Property 12) Silicon Atom Content (ppm by mass) Using 0.5 g of a modified conjugated diene polymer as a sample, measurement was performed using an ultraviolet-visible spectrophotometer (trade name "UV-1800" manufactured by Shimadzu Corporation) in accordance with JIS K 0101 44.3.1, and the content was quantified by molybdenum blue absorptiometry. When silicon atoms were detected (detection limit 10 ppm by mass), it was determined that the polymer contained silicon atoms. This confirmed that the modified conjugated diene polymers of the examples and comparative examples contained silicon atoms.

[0339] Example 1 Modified 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 18.5 g / min, 6.2 g / min, and 117.4 g / min, respectively. During the feeding, n-butyllithium was continuously added at a rate of 0.096 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 a mixed solution of piperidinolithium (also referred to as "1-lithiopiperidine"; abbreviated as "a-1" in the table) as a pre-prepared lithium amide serving as a polymerization initiator and n-butyllithium (the molar ratio of piperidinolithium to n-butyllithium was 0.75:0.25) were supplied to the bottom of the first reactor at rates of 0.049 mmol / min and 0.221 mmol / min, respectively, while the reaction solution was vigorously stirred with a stirrer. The temperature inside the first reactor was maintained at 82°C.

[0340] 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. Once the polymerization was sufficiently stabilized, trimethoxy(4-vinylphenyl)silane (also referred to as "c-1") serving as a branching agent was supplied from the bottom of the second reactor at a rate of 0.011 mmol / min while copolymerizing 1,3-butadiene and styrene, and additional 1,3-butadiene was added at a rate of 6.2 g / min to carry out a polymerization branching step. The temperature inside the second reactor was maintained at 86°C. A small amount of the conjugated diene polymer solution was withdrawn from the outlet of the second reactor, and an antioxidant (BHT) was added so that the amount of antioxidant (BHT) was 0.2 g per 100 g of conjugated diene polymer, followed by removal of the solvent. The obtained conjugated diene polymer was subjected to measurement of various molecular weights by GPC, Mooney viscosity at 110° C., Mooney relaxation coefficient, etc. The physical properties are shown in Tables 1 to 3 (Physical Properties 1-1, 1-2, 1-3, Physical Properties 2, and Physical Properties 3).

[0341] 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 (also referred to as "b-1") was continuously added as a coupling modifier at a rate of 0.031 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 68°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.

[0342] Next, an n-hexane solution of antioxidant (BHT) was continuously added to the polymer solution flowing out of the static mixer so that the content of antioxidant (BHT) per 100 parts by mass of the conjugated diene polymer was 0.5 parts by mass, thereby completing the coupling reaction. The solvent was removed by steam stripping, and the resulting mixture was formed into a bale, thereby obtaining a modified conjugated diene polymer (A1). Various physical properties of the obtained modified conjugated diene polymer (A1) were measured. The measurement results are shown in Table 1.

[0343] (Example 2) Modified conjugated diene polymer (A2) A modified conjugated diene polymer (A2) was obtained in the same manner as in Example 1, except that the coupling modifier b-1 was supplied at 0.044 mmol / min. The physical properties of the modified conjugated diene polymer (A2) are shown in Table 1.

[0344] (Example 3) Modified conjugated diene polymer (A3) A modified conjugated diene polymer (A3) was obtained in the same manner as in Example 1, except that b-1 as a coupling modifier was supplied at 0.054 mmol / min. The physical properties of the modified conjugated diene polymer (A3) are shown in Table 1.

[0345] (Example 4) Modified conjugated diene polymer (A4) A modified conjugated diene polymer (A4) was obtained in the same manner as in Example 1, except that b-1 as a coupling modifier was supplied at 0.062 mmol / min. The physical properties of the modified conjugated diene polymer (A4) are shown in Table 1.

[0346] (Example 5) Modified conjugated diene polymer (A5) A modified conjugated diene polymer (A5) was obtained in the same manner as in Example 1, except that b-1 as a coupling modifier was supplied at 0.070 mmol / min. The physical properties of the modified conjugated diene polymer (A5) are shown in Table 1.

[0347] Example 6 Modified Conjugated Diene Polymer (A6) A modified conjugated diene polymer (A6) was obtained in the same manner as in Example 1, except that a mixed solution of lithium amide / n-butyllithium as a polymerization initiator was supplied at 0.173 mmol / min, 2,2-bis(2-oxolanyl)propane as a polar compound was supplied at 0.037 mmol / min, c-1 as a branching agent was supplied at 0.009 mmol / min, and b-1 as a coupling modifier was supplied at 0.054 mmol / min. The physical properties of the modified conjugated diene polymer (A6) are shown in Table 1.

[0348] Example 7 Modified Conjugated Diene Polymer (A7) A modified conjugated diene polymer (A7) was obtained in the same manner as in Example 1, except that a mixed solution of lithium amide / n-butyllithium as a polymerization initiator was supplied at 0.154 mmol / min, 2,2-bis(2-oxolanyl)propane as a polar compound was supplied at 0.037 mmol / min, c-1 as a branching agent was supplied at 0.009 mmol / min, and b-1 as a coupling modifier was supplied at 0.054 mmol / min. The physical properties of the modified conjugated diene polymer (A7) are shown in Table 1.

[0349] (Example 8) Modified conjugated diene polymer (A8) A modified conjugated diene polymer (A8) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 16.0 g / min, additional 1,3-butadiene was supplied at 8.6 g / min, and b-1 as a coupling modifier was supplied at 0.054 mmol / min. The physical properties of the modified conjugated diene polymer (A8) are shown in Table 1.

[0350] (Example 9) Modified conjugated diene polymer (A9) A modified conjugated diene polymer (A9) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 13.6 g / min, additional 1,3-butadiene was supplied at 11.1 g / min, and b-1 as a coupling modifier was supplied at 0.054 mmol / min. The physical properties of the modified conjugated diene polymer (A9) are shown in Table 1.

[0351] (Example 10) Modified conjugated diene polymer (A10) A modified conjugated diene polymer (A10) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 19.7 g / min, styrene at 4.6 g / min, and 2,2-bis(2-oxolanyl)propane as a polar compound at 0.080 mmol / min. The physical properties of the modified conjugated diene polymer (A10) are shown in Table 1.

[0352] (Example 11) Modified conjugated diene polymer (A11) A modified conjugated diene polymer (A11) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 19.7 g / min, styrene at 4.6 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.080 mmol / min, and b-1 as a coupling modifier at 0.044 mmol / min. The physical properties of the modified conjugated diene polymer (A11) are shown in Table 1.

[0353] (Example 12) Modified conjugated diene polymer (A12) A modified conjugated diene polymer (A12) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 19.7 g / min, styrene at 4.6 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.080 mmol / min, and b-1 as a coupling modifier at 0.054 mmol / min. The physical properties of the modified conjugated diene polymer (A12) are shown in Table 1.

[0354] (Example 13) Modified conjugated diene polymer (A13) A modified conjugated diene polymer (A13) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 19.7 g / min, styrene at 4.6 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.080 mmol / min, and b-1 as a coupling modifier at 0.062 mmol / min. The physical properties of the modified conjugated diene polymer (A13) are shown in Table 1.

[0355] (Example 14) Modified conjugated diene polymer (A14) A modified conjugated diene polymer (A14) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 19.7 g / min, styrene at 4.6 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.080 mmol / min, and b-1 as a coupling modifier at 0.070 mmol / min. The physical properties of the modified conjugated diene polymer (A14) are shown in Table 1.

[0356] Example 15 Modified Conjugated Diene Polymer (A15) A modified conjugated diene polymer (A15) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 20.8 g / min, styrene at 6.9 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.104 mmol / min, additional 1,3-butadiene at 6.9 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.031 mmol / min, the temperature of the first reactor was set to 68° C., and the temperature of the second reactor was set to 70° C. The physical properties of the modified conjugated diene polymer (A15) are shown in Table 1.

[0357] Example 16 Modified Conjugated Diene Polymer (A16) A modified conjugated diene polymer (A16) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 20.8 g / min, styrene at 6.9 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.104 mmol / min, additional 1,3-butadiene at 6.9 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.044 mmol / min, the temperature of the first reactor was set to 68° C., and the temperature of the second reactor was set to 70° C. The physical properties of the modified conjugated diene polymer (A16) are shown in Table 2.

[0358] Example 17 Modified Conjugated Diene Polymer (A17) A modified conjugated diene polymer (A17) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 20.8 g / min, styrene at 6.9 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.104 mmol / min, additional 1,3-butadiene at 6.9 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.054 mmol / min, the temperature of the first reactor was set to 68° C., and the temperature of the second reactor was set to 70° C. The physical properties of the modified conjugated diene polymer (A17) are shown in Table 2.

[0359] Example 18 Modified Conjugated Diene Polymer (A18) A modified conjugated diene polymer (A18) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 20.8 g / min, styrene at 6.9 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.104 mmol / min, additional 1,3-butadiene at 6.9 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.062 mmol / min, the temperature of the first reactor was set to 68° C., and the temperature of the second reactor was set to 70° C. The physical properties of the modified conjugated diene polymer (A18) are shown in Table 2.

[0360] Example 19 Modified Conjugated Diene Polymer (A19) A modified conjugated diene polymer (A19) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 20.8 g / min, styrene at 6.9 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.104 mmol / min, additional 1,3-butadiene at 6.9 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.070 mmol / min, the temperature of the first reactor was set to 68° C., and the temperature of the second reactor was set to 70° C. The physical properties of the modified conjugated diene polymer (A19) are shown in Table 2.

[0361] (Example 20) Modified conjugated diene polymer (A20) A modified conjugated diene polymer (A20) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 16.2 g / min, styrene at 9.2 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.045 mmol / min, additional 1,3-butadiene at 5.4 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.031 mmol / min, the temperature of the first reactor was set to 68° C., and the temperature of the second reactor was set to 74° C. The physical properties of the modified conjugated diene polymer (A20) are shown in Table 2.

[0362] Example 21 Modified Conjugated Diene Polymer (A21) A modified conjugated diene polymer (A21) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 16.2 g / min, styrene at 9.2 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.045 mmol / min, additional 1,3-butadiene at 5.4 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.044 mmol / min, the temperature of the first reactor was set to 68° C., and the temperature of the second reactor was set to 74° C. The physical properties of the modified conjugated diene polymer (A21) are shown in Table 2.

[0363] Example 22 Modified Conjugated Diene Polymer (A22) A modified conjugated diene polymer (A22) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 16.2 g / min, styrene at 9.2 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.045 mmol / min, additional 1,3-butadiene at 5.4 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.054 mmol / min, the temperature of the first reactor was set to 68° C., and the temperature of the second reactor was set to 74° C. The physical properties of the modified conjugated diene polymer (A22) are shown in Table 2.

[0364] Example 23 Modified Conjugated Diene Polymer (A23) A modified conjugated diene polymer (A23) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 16.2 g / min, styrene at 9.2 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.045 mmol / min, additional 1,3-butadiene at 5.4 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.062 mmol / min, the temperature of the first reactor was set to 68° C., and the temperature of the second reactor was set to 74° C. The physical properties of the modified conjugated diene polymer (A23) are shown in Table 2.

[0365] Example 24 Modified Conjugated Diene Polymer (A24) A modified conjugated diene polymer (A24) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 16.2 g / min, styrene at 9.2 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.045 mmol / min, additional 1,3-butadiene at 5.4 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.070 mmol / min, the temperature of the first reactor was set to 68° C., and the temperature of the second reactor was set to 74° C. The physical properties of the modified conjugated diene polymer (A24) are shown in Table 2.

[0366] Example 25 Modified Conjugated Diene Polymer (A25) A modified conjugated diene polymer (A25) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 17.2 g / min, styrene at 5.7 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.060 mmol / min, additional 1,3-butadiene at 7.9 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.031 mmol / min, the temperature of the first reactor was set to 83° C., and the temperature of the second reactor was set to 88° C. The physical properties of the modified conjugated diene polymer (A25) are shown in Table 2.

[0367] Example 26 Modified Conjugated Diene Polymer (A26) A modified conjugated diene polymer (A26) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 17.2 g / min, styrene at 5.7 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.060 mmol / min, additional 1,3-butadiene at 7.9 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.044 mmol / min, the temperature of the first reactor was set to 83° C., and the temperature of the second reactor was set to 88° C. The physical properties of the modified conjugated diene polymer (A26) are shown in Table 2.

[0368] Example 27 Modified Conjugated Diene Polymer (A27) A modified conjugated diene polymer (A27) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 17.2 g / min, styrene at 5.7 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.060 mmol / min, additional 1,3-butadiene at 7.9 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.054 mmol / min, the temperature of the first reactor was set to 83° C., and the temperature of the second reactor was set to 88° C. The physical properties of the modified conjugated diene polymer (A27) are shown in Table 2.

[0369] Example 28 Modified Conjugated Diene Polymer (A28) A modified conjugated diene polymer (A28) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 17.2 g / min, styrene at 5.7 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.060 mmol / min, additional 1,3-butadiene at 7.9 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.062 mmol / min, the temperature of the first reactor was set to 83° C., and the temperature of the second reactor was set to 88° C. The physical properties of the modified conjugated diene polymer (A28) are shown in Table 2.

[0370] Example 29 Modified Conjugated Diene Polymer (A29) A modified conjugated diene polymer (A29) was obtained in the same manner as in Example 1, except that 1,3-butadiene was supplied at 17.2 g / min, styrene at 5.7 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.060 mmol / min, additional 1,3-butadiene at 7.9 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.070 mmol / min, the temperature of the first reactor was set to 83° C., and the temperature of the second reactor was set to 88° C. The physical properties of the modified conjugated diene polymer (A29) are shown in Table 2.

[0371] (Comparative Example 1) Modified conjugated diene polymer (B1) A modified conjugated diene polymer (B1) was obtained in the same manner as in Example 1, except that n-butyllithium was used as the polymerization initiator. The physical properties of the modified conjugated diene polymer (B1) are shown in Table 3.

[0372] Comparative Example 2 Modified Conjugated Diene Polymer (B2) A modified conjugated diene polymer (B2) was obtained in the same manner as in Example 1, except that n-butyllithium as a polymerization initiator was supplied at 0.071 mmol / min, b-1 as a coupling modifier was supplied at 0.054 mmol / min, 2,2-bis(2-oxolanyl)propane as a polar compound was supplied at 0.055 mmol / min, c-1 as a branching agent was supplied at 0.0016 mmol / min, and b-1 as a coupling modifier was supplied at 0.071 mmol / min. The physical properties of the modified conjugated diene polymer (B2) are shown in Table 3.

[0373] Comparative Example 3 Modified Conjugated Diene Polymer (B3) The same procedure as in Example 1 was repeated except that n-butyllithium was used as the polymerization initiator, and the polymerization temperature in the first reactor was maintained at 92°C, and the temperature in the second reactor was maintained at 95°C. A modified conjugated diene polymer (B3) was obtained. The physical properties of the modified conjugated diene polymer (B3) are shown in Table 3.

[0374] Comparative Example 4 Modified Conjugated Diene Polymer (B4) A modified conjugated diene polymer (B4) was obtained in the same manner as in Example 1, except that n-butyllithium was used as the polymerization initiator, 1,3-butadiene was supplied at 16.2 g / min, styrene at 9.24 g / min, 2,2-bis(2-oxolanyl)propane as a polar compound at 0.104 mmol / min, additional 1,3-butadiene at 5.4 g / min, c-1 as a branching agent at 0.011 mmol / min, and b-1 as a coupling modifier at 0.054 mmol / min, the temperature of the first reactor was set to 68° C., and the temperature of the second reactor was set to 70° C. The physical properties of the modified conjugated diene polymer (B4) are shown in Table 3.

[0375]

[0376]

[0377]

[0378] [Evaluation of modified conjugated diene polymer bales] (Evaluation 1) Bale appearance (presence or absence of cracks / crumbs) The modified conjugated diene polymer bales produced by the methods shown in the Examples and Comparative Examples were visually inspected for appearance, such as the presence or absence of external cracks or crumbling, and evaluated based on the following criteria, with each panelist giving a maximum score of 4 points. The appearance of the bale is an index of the bale formability of the modified conjugated diene polymer. IV: The crumb did not come together and could not be formed into a bale. III: It could be formed into a bale, but no crumbling was observed over time. II: No cracks, crumbling, etc. of 5% or less were observed on the bale surface. I: No cracks, crumbling, etc. were observed at all on the bale surface.

[0379] [Preparation and Evaluation of Rubber Compositions] (Evaluation of Rubber Compositions) Using the modified conjugated diene polymers A1 to A29 and B1 to B4 shown in Tables 1 to 7 as raw materials, rubber compositions were obtained according to the formulations shown below. Modified conjugated diene polymer (any of A1 to A29 and B1 to B4): 70 parts by mass (oil excluded) Butadiene rubber (trade name "BR150" manufactured by Ube Industries, Ltd.): 30 parts by mass Silica (trade name "Ultrasil 7000GR" manufactured by Evonik Degussa, nitrogen adsorption specific surface area 170 m２ / 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

[0380] 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 (A1 to A29 or B1 to B4), butadiene rubber, filler (silica, carbon black), 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.

[0381] 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 to 160°C. After cooling, the compound was mixed in the third stage of mixing using an open roll set at 70°C, with sulfur and vulcanization accelerators 1 and 2 added and mixed. 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 to 7.

[0382] (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 discharge following completion of kneading by the pressure kneader in the first stage of kneading), 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 were 60% or less smooth, and the processability was very poor. III: The edge portions of the sheet were more than 60% but not more than 80% smooth, and the processability was poor. II: The edge portions of the sheet were more than 80% but not more than 90% smooth, and the processability was excellent. I: The edge portions of the sheet were more than 90% smooth, and the processability was excellent.

[0383] (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. The larger the index, the better the fuel economy, and a value exceeding 65 was evaluated as having excellent fuel economy. In addition, 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. The larger the index, the better the wet grip performance, and a value exceeding 65 was evaluated as having excellent wet grip performance.

[0384] (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 to 100. The larger the value, the better the tensile strength and tensile elongation, and the more excellent the fracture properties.

[0385] (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.

[0386]

[0387]

[0388]

[0389]

[0390] The modified conjugated diene polymer of the present invention is excellent in bale formability, processability, and fuel-saving performance, and its vulcanizate has an excellent balance of abrasion resistance, fracture properties, and low hysteresis loss.

[0391] The disclosure of Japanese Patent Application No. 2023-126215, filed on August 2, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

[0392] The modified conjugated diene polymer, the method for producing the modified conjugated diene polymer, the modified conjugated diene polymer composition, the rubber composition, and the like of the present invention have excellent moldability of the modified conjugated diene polymer, and the vulcanizates thereof have an excellent balance of performance such as abrasion resistance, fracture properties, and low hysteresis loss, and therefore have industrial applicability in applications such as tires, resin modification, interior and exterior parts of automobiles, vibration-proof rubber, and footwear.

Claims

1. A modified conjugated diene polymer which satisfies the following <Condition (i)> to <Condition (vi)>. <Condition (i)> The Mooney viscosity measured at 100°C is 100 or more and 180 or less. <Condition (ii)> The Mooney relaxation coefficient measured at 100°C is in the range of 0.10 to 0.

40. <Condition (iii)> The glass transition temperature is -95°C to -45°C. <Condition (iv)> The silicon atom content is 100 ppm by mass or more based on the total amount of the modified conjugated diene polymer. <Condition (V)> The nitrogen atom content is 50 ppm by mass or more based on the total amount of the modified conjugated diene polymer. <Condition (Vi)> The antioxidant content is 0.5 parts by mass or less based on 100 parts by mass of the modified conjugated diene polymer.

2. The modified conjugated diene polymer according to claim 1, wherein the Mooney viscosity measured at 100° C. in the condition (i) is 105 or more and 180 or less.

3. The modified conjugated diene polymer according to claim 1, wherein the Mooney relaxation coefficient measured at 100° C. under the condition (ii) is 0.10 to 0.

35.

4. The modified conjugated diene polymer according to claim 1, wherein the glass transition temperature of the condition (iii) is -95°C to -55°C.

5. The modified conjugated diene polymer according to claim 1, wherein the nitrogen atom content of the condition (V) is 80 ppm by mass or more based on the total amount of the modified conjugated diene polymer.

6. The modified conjugated diene polymer according to claim 1, having a molecular weight distribution (PDI; MWD) of 1.4 to 2.

5.

7. The modified conjugated diene polymer according to claim 1, wherein the amount of 1,2-vinyl bonds relative to the total mass of the modified conjugated diene polymer is 45.0 mol % or less.

8. The modified conjugated diene polymer according to claim 1, which has a branching degree (Bn) of 2 or more as measured by a GPC-light scattering method with a viscosity detector.

9. The modified conjugated diene polymer according to claim 1, having a nitrogen atom at at least one terminal, and having at least one branched chain having a star-shaped structure, the branched chain having a star-shaped structure having a portion derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, the portion derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group having a further main chain branch structure and having a coupling structure centered on a nitrogen-containing alkoxysilane substituent.

10. The modified conjugated diene polymer according to claim 1, wherein the coupling structure centered on the nitrogen-containing alkoxysilane substituent comprises a nitrogen-containing alkoxysilane modifier residue having at least four silicon atoms and an alkoxy group and / or a hydroxy group, a modified conjugated diene polymer chain having a main chain branched structure is bonded to the silicon atoms, and the number of the alkoxy groups and / or the hydroxy groups in the modifier residue is greater on average than the number of the silicon atoms.

11. A veil comprising 100 parts by mass of the modified conjugated diene polymer according to claim 1 and 2 parts by mass or less of a softener component.

12. A veil comprising 100 parts by mass of the modified conjugated diene polymer according to claim 1 and less than 1 part by mass of a softener component.

13. A method for producing a modified conjugated diene polymer according to claim 1, comprising: a step of polymerizing at least a conjugated diene compound in the presence of an organolithium compound having at least one nitrogen atom in the molecule; and a branching step of obtaining a branched conjugated diene polymer having a main chain branched structure using a branching agent, wherein in the step of coupling the branched conjugated diene polymer using a coupling agent and / or the step of modifying the branched conjugated diene polymer with a modifying agent having a nitrogen atom-containing group, the coupling agent and / or the modifying agent are added in excess.

14. 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 polymer described in claim 1 or the veil described in claim 11 relative to 100 parts by mass of the total amount of the rubber component.

15. A tire comprising the rubber composition according to claim 14.

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