Conjugated diene-based polymer and rubber composition

Abstract

To provide a conjugated diene-based polymer which gives a rubber composition having an excellent balance between gripping properties and abrasion resistance and excellent silica dispersibility and has a low water content.SOLUTION: Wherein a content of an aromatic vinyl monomer unit is 30 mass% or more and 45 mass% or less, an amount of 1, 2-vinyl bonds is 30mol% or more and 60mol or less, a mooney viscosity is 30 or more and 90 or less, a molecular weight distribution obtained by GPC (gel permeation chromatography) is 1.7 or more and less than 3.0, a content of a conjugated diene-based polymer having a molecular weight of 100,000 or less is 5 mass% or more, a content of a conjugated diene-based polymer having a molecular weight of 1,000,000 or more is 5 mass% or more, and a content of Mg is 10ppm or more.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In recent years, with the aging of society accelerating, fatal accidents due to falls are increasing, and there is an increasing demand for shoes that are safe and can be used for a long period of time. To this end, rubber compositions for shoe soles are required to have grip properties for safety and abrasion resistance for long-term use. However, conventional rubber compositions have the problem that it is difficult to simultaneously satisfy both gripping properties and abrasion resistance.

[0003] In order to solve such problems, Patent Document 1 proposes a rubber composition of solution-polymerized styrene-butadiene rubber and hydrous silica, which has a loss modulus (tan δ) peak in the temperature range of −10°C to −30°C under specific conditions.

[0004] On the other hand, inorganic fillers such as silica have poorer affinity with rubber components than carbon, and therefore the rubber composition disclosed in Patent Document 1 has a problem in that the dispersibility of silica in the rubber composition is poor and sufficient abrasion resistance cannot be obtained. In response to this, Patent Document 2 proposes a rubber composition in which the dispersibility of silica is improved and the abrasion resistance is improved by introducing a specific functional group into a conjugated diene polymer.

[0005] However, none of the above documents is yet satisfactory in terms of achieving both gripping properties and wear resistance, and further improvements are required. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 10-17717 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-162777 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, high grip performance and abrasion resistance are required particularly for rubber compositions for shoes, but the techniques disclosed so far have the problem that it is difficult to satisfy both of these requirements simultaneously.

[0008] Therefore, in order to solve the above-mentioned problems of the prior art, an object of the present invention is to provide a conjugated diene polymer from which a rubber composition can be obtained which has excellent gripping properties and abrasion resistance and which has an excellent balance of these properties. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems of the conventional art, and as a result have found that the above-mentioned problems of the conventional art can be solved by a conjugated diene polymer having specified 1,2-vinyl bond content, aromatic vinyl monomer unit content, Mooney viscosity, molecular weight distribution, content of conjugated diene polymer having a molecular weight within a specific range, and Mg content, and have thus completed the present invention. That is, the present invention is as follows.

[0010] [1] The content of aromatic vinyl monomer units is 30% by mass or more and 45% by mass or less, The amount of 1,2-vinyl bonds is 30 mol% or more and 60 mol or less, Mooney viscosity is 30 or more and 90 or less, The molecular weight distribution obtained by GPC (gel permeation chromatography) is 1.7 or more and less than 3.0, The content of conjugated diene polymers having a molecular weight of 100,000 or less is 5% by mass or more, The content of conjugated diene polymers having a molecular weight of 1 million or more is 5% by mass or more, The Mg content is 10 ppm or more. Conjugated diene polymer. [2] The modification rate is 30% by mass or more. The conjugated diene polymer according to [1] above. [3] The glass transition temperature is between -40°C and 5°C. The conjugated diene polymer according to [1] or [2] above. [4] The Ti content is 2 ppm or more, The conjugated diene polymer according to any one of [1] to [3] above. [5] The amount of 1,2-vinyl bonds is 45 mol or more and 60 mol or less. The conjugated diene polymer according to any one of [1] to [4] above. [6] The water content is 0.6% by mass or less. The conjugated diene polymer according to any one of [1] to [5] above. [7] Does not contain extender oil The conjugated diene polymer according to any one of [1] to [6] above. [8] A molded article of a conjugated diene polymer, The conjugated diene polymer according to any one of [1] to [7] above. [9] A rubber composition containing the conjugated diene polymer according to any one of [1] to [8] above as a rubber component.

[10] The rubber composition 100 parts by mass of a rubber component containing the conjugated diene polymer according to any one of [1] to [8]; 20 parts by mass or more of an inorganic filler; containing The rubber composition according to [9].

[11] The rubber composition according to [9] above, which is a rubber composition for shoes. [Effects of the Invention]

[0011] According to the present invention, a rubber composition having an excellent balance of gripping properties and abrasion resistance and excellent silica dispersibility can be obtained, and a conjugated diene polymer with a low water content can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The following embodiments are merely examples for explaining the present invention, and the present invention is not limited to the following embodiments. The present invention can be practiced with appropriate modifications within the scope of its gist.

[0013] [Conjugated diene polymer] The conjugated diene polymer of the present embodiment is The content of aromatic vinyl monomer units is 30% by mass or more and 45% by mass or less, the amount of 1,2-vinyl bonds is 30 mol% or more and 60 mol% or less, the Mooney viscosity is 30 or more and 90 or less, the molecular weight distribution obtained by GPC (gel permeation chromatography) is 1.7 or more and less than 3.0, the content of conjugated diene polymers having a molecular weight of 100,000 or less is 5% by mass or more, the content of conjugated diene polymers having a molecular weight of 1,000,000 or more is 5% by mass or more, and the content of Mg is 10 ppm or more. The conjugated diene polymer of the present embodiment has a low water content, and a rubber composition obtained by using the polymer has an excellent balance of gripping properties and abrasion resistance, and excellent silica dispersibility.

[0014] (Aromatic vinyl monomer unit content) The conjugated diene polymer of the present embodiment has an aromatic vinyl monomer unit content of 30% by mass or more and 45% by mass or less. The content of aromatic vinyl monomer units in the conjugated diene polymer of the present embodiment is preferably 30% by mass or more and 45% by mass or less, more preferably 32% by mass or more and 45% by mass or less, and even more preferably 35% by mass or more and 45% by mass or less. When the content of the aromatic vinyl monomer unit is within the above range, a rubber composition that exhibits excellent gripping properties and high abrasion resistance tends to be obtained. When the content of aromatic vinyl monomer units is 30% by mass or more, excellent tensile strength tends to be obtained. When the content of aromatic vinyl monomer units is 45% by mass or less, the solubility in the polymerization solvent tends to be good, and the productivity tends to be excellent. The content of aromatic vinyl monomer units in the conjugated diene polymer can be measured by the method described in the examples below. The content of the aromatic vinyl monomer unit in the conjugated diene polymer can be controlled within the above-mentioned range by adjusting the amount of monomer added in the polymerization step, the polymerization temperature and the polymerization time.

[0015] (1,2-vinyl bond content) The conjugated diene polymer of this embodiment has a 1,2-vinyl bond content of 30 mol % or more and 60 mol % or less. The 1,2-vinyl bond content of the conjugated diene polymer of this embodiment is preferably 40 mol% or more and 60 mol% or less, and more preferably 45 mol% or more and 60 mol% or less. When the 1,2-vinyl bond content is within the above range, a rubber composition with a good balance of gripping properties and abrasion resistance tends to be obtained. When the 1,2-vinyl bond content is 30 mol% or more, a rubber composition with excellent gripping properties tends to be obtained. When the 1,2-vinyl bond content is 60 mol% or less, a rubber composition with excellent abrasion resistance tends to be obtained. When high-cis-butadiene having a high cis-bond content is used as a rubbery polymer other than the conjugated diene-based polymer of this embodiment as a constituent component of the rubber composition for shoes, the compatibility with high-cis-butadiene can be adjusted by changing the 1,2-vinyl bond content of the conjugated diene-based polymer of this embodiment, and increasing the 1,2-vinyl bond content tends to improve the compatibility with high-cis-butadiene. The amount of 1,2-vinyl bonds in the conjugated diene polymer can be measured by the method described in the Examples below. The 1,2-vinyl bond content of the conjugated diene polymer of the present embodiment can be controlled within the above-mentioned numerical range by adjusting the amount of polar substance added to the polymerization initiator in the polymerization step, and the 1,2-vinyl bond content tends to increase by increasing the amount of polar substance added.

[0016] (Mooney viscosity) The conjugated diene polymer of the present embodiment has a Mooney viscosity of 30 or more and 90 or less, preferably 50 or more and 90 or less, and more preferably 55 or more and 80 or less. When the Mooney viscosity is within the above range, a conjugated diene polymer can be obtained that can be used to produce a rubber composition that exhibits excellent gripping properties and high abrasion resistance. If the Mooney viscosity is 30 or more, sufficient tensile strength tends to be obtained, and if it is 90 or less, excellent processability tends to be obtained. The Mooney viscosity can be measured using, for example, a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) with an L-shaped rotor in accordance with JIS K6300 (ISO 289-1). Specifically, the sample is first preheated at 100°C for 1 minute, and then the rotor is rotated at 2 rpm. The torque after 4 minutes is measured to determine the Mooney viscosity at 100°C. The Mooney viscosity tends to increase when the conjugated diene polymer has a high molecular weight, a high modification rate, and a multi-branched structure, and can be controlled within the above-mentioned range by adjusting the amounts of the polymerization initiator and the coupling agent added to the active terminals of the conjugated diene polymer. The Mooney viscosity can also be controlled by the method described later in the production method.

[0017] (Molecular weight distribution (MWD)) The conjugated diene polymer of this embodiment has a molecular weight distribution (MWD) of 1.7 or more and less than 3.0, preferably 1.8 or more and 2.8 or less, and more preferably 1.9 or more and 2.6 or less. When the molecular weight distribution (MWD) is within the above range, a conjugated diene polymer tends to be obtained that can be used to produce a rubber composition that exhibits excellent processability when vulcanized and excellent abrasion resistance. In particular, from the viewpoint of processability, when the molecular weight distribution is less than 3.0, the rubber tends to be less likely to shrink when passed through a roll or the like during the preparation of the rubber composition, compared to a rubber sheet immediately after being rolled to a desired thickness. In particular, when producing a rubber composition for shoes, it is preferable that the rubber sheet shrinks less. The molecular weight distribution of the conjugated diene polymer can be measured by the method described in the examples below. The molecular weight distribution can be controlled within the above numerical range by adjusting the residence time distribution during polymerization and the type and amount of coupling agent added.

[0018] (Content of conjugated diene polymers with a molecular weight of 100,000 or less) The conjugated diene polymer of this embodiment has a content of molecular weights of 100,000 or less of 5% by mass or more, preferably 5.5% by mass or more, and more preferably 6.0% by mass or more. The content is defined as the area ratio of molecular weights of 100,000 or less when the total area of ​​a molecular weight distribution curve obtained by gel permeation chromatography is taken as 100%. When the content of the conjugated diene polymer having a molecular weight of 100,000 or less is within the above range, a conjugated diene polymer that can be used to produce a rubber composition exhibiting excellent gripping properties can be obtained. The content of the conjugated diene polymer having a molecular weight of 100,000 or less in the conjugated diene polymer of this embodiment can be measured by the method described in the examples below. The content of the conjugated diene polymer having a molecular weight of 100,000 or less can be controlled, for example, by adjusting the amount of polymerization initiator added. If the amount of polymerization initiator is small, the molecular weight distribution curve obtained by gel permeation chromatography of the resulting conjugated diene polymer will be shifted overall to the high molecular weight side, and the area ratio of molecular weights of 100,000 or less will be small. If the amount of polymerization initiator is large, the molecular weight distribution curve obtained by gel permeation chromatography of the resulting conjugated diene polymer will be shifted overall to the low molecular weight side, and the area ratio of molecular weights of 100,000 or less will be large.

[0019] (Content of conjugated diene polymers with a molecular weight of 1 million or more) The conjugated diene polymer of this embodiment has a content of conjugated diene polymers having a molecular weight of 1 million or more of 5% by mass or more, preferably 6.0% by mass or more, and more preferably 7.0% by mass or more. The content is defined as the area ratio of conjugated diene polymers having a molecular weight of 1 million or more, when the total area of ​​a molecular weight distribution curve obtained by gel permeation chromatography is taken as 100%. The content of conjugated diene polymers having a molecular weight of 1 million or more in the conjugated diene polymer of this embodiment can be measured by the method described in the Examples below. When the content of the conjugated diene polymer having a molecular weight of 1,000,000 or more is within the above range, a conjugated diene polymer that can be used to produce a rubber composition exhibiting excellent abrasion resistance can be obtained. The content of the conjugated diene polymer having a molecular weight of 1,000,000 or more can be controlled by adjusting the amount of polymerization initiator added, in the same manner as the content of the conjugated diene polymer having a molecular weight of 100,000 or less.

[0020] (Mg content) The conjugated diene polymer of this embodiment has a Mg content of 10 ppm or more, preferably 15 ppm or more, and more preferably 20 ppm or more. Mg in the conjugated diene polymer can be contained in the form of a metal salt or metal ion, such as a metal carbonate, metal sulfate, metal hydroxide, or metal chloride. These can be contained alone or in the form of a mixture or an aqueous solution. The Mg content in the conjugated diene polymer of the present embodiment can be measured by the method described in the examples below. As a method for controlling the Mg content of the conjugated diene polymer within the above range, a method of increasing the Mg concentration contained in water used in the solvent removal step after the completion of polymerization can be mentioned. The conjugated diene polymer of this embodiment is characterized by a high content of aromatic vinyl monomer units and a high content of 1,2-vinyl bonds. Therefore, the amount of polar substance added during the polymerization step described below tends to be large. If a large amount of polar substance is added, for example, when finishing is performed by steam stripping during the finishing step, the resulting conjugated diene polymer tends to have a high residual moisture content. Similarly, when the content of conjugated diene polymers having a molecular weight of 100,000 or less is 5% by mass or more and the modification rate is 30% by mass or more, the residual moisture content also tends to be large. If the residual moisture content is large, the temperature does not rise during kneading of the rubber compound, preventing the reaction between silica and silane coupling or the conjugated diene polymer from proceeding, which tends to result in poor silica dispersibility. Furthermore, the bale-molded conjugated diene polymer is packaged in film. However, a high residual moisture content can cause condensation, so a low residual moisture content is preferable from the perspective of quality. When the Mg content is within the above-mentioned range, a conjugated diene copolymer with a low water content tends to be obtained, thereby obtaining a rubber composition with excellent silica dispersibility. As the Mg content in the water used in the solvent removal step increases, the amount of water remaining in the conjugated diene polymer decreases, while the Mg content in the conjugated diene polymer tends to increase.

[0021] (Ti content) The conjugated diene polymer of the present embodiment preferably has a Ti content of 2 ppm or more, more preferably 3 ppm or more, and even more preferably 4 ppm or more. Ti can be contained in the form of a metal salt or metal ion, such as a metal carbonate, metal sulfate, metal hydroxide, or metal chloride. These may be contained alone or in the form of a mixture or an aqueous solution. The Ti content in the conjugated diene polymer of the present embodiment can be measured by the method described in the examples below. As a method for controlling the Ti content of the conjugated diene polymer within the above range, a method of increasing the Ti concentration in water used in the solvent removal step after the completion of polymerization can be mentioned. When the content of Ti is within the above range, a rubber composition having even better silica dispersibility tends to be obtained due to a synergistic effect with Mg, and the reaction between silica and a coupling agent or a modified conjugated diene polymer tends to be promoted when the rubber compound is kneaded.

[0022] (denaturation rate) The conjugated diene polymer of the present embodiment preferably has a modification rate of 30% by mass or more, more preferably 50% by mass or more, and even more preferably 65% ​​by mass or more. When the modification rate is within the above range, the interaction with the silica-based inorganic filler, which is a reinforcing material for the outsole, is strengthened, and a conjugated diene-based polymer is obtained that can be used to produce a rubber composition that exhibits excellent gripping properties and high abrasion resistance while increasing dispersibility and improving processability. The upper limit of the modification rate is not particularly limited, but is, for example, 100% by mass. The modification rate of the conjugated diene polymer of the present embodiment can be measured by a column adsorption GPC method, more specifically, by the method described in the examples. The modification rate can be controlled within the above range by adjusting the type and amount of the polymerization initiator and the amount of the modifying agent. In this specification, the term "modification rate" refers to the mass ratio of a polymer having a nitrogen-atom-containing functional group to the total amount of the conjugated diene polymer. The position at which the nitrogen atom is introduced into the conjugated diene polymer of this embodiment may be the polymerization initiation terminal of the conjugated diene polymer, in the molecular chain (including grafting), or at the polymerization terminal. An example of a method for introducing a nitrogen atom into the polymerization initiation terminal is a method described in International Publication No. 2016 / 133202, which uses an organolithium compound containing a nitrogen atom as a polymerization initiator.

[0023] (glass transition temperature) The conjugated diene polymer of the present embodiment preferably has a glass transition temperature (Tg) of -40°C or more and 5°C or less, more preferably -30°C or more and 5°C or less, and even more preferably -25°C or more and 0°C or less. By having a glass transition temperature within the above range, a modified conjugated diene polymer that can be used to produce a rubber composition having a good balance between gripping properties and abrasion resistance tends to be obtained. When the conjugated diene polymer of the present embodiment has a glass transition temperature (Tg) of -40°C or higher, the rubber composition tends to have excellent gripping properties, and when the glass transition temperature (Tg) is 5°C or lower, the rubber composition tends to have excellent wear resistance. The glass transition temperature of the conjugated diene polymer can be measured by the method described in the examples below. The glass transition temperature (Tg) of the conjugated diene polymer of this embodiment tends to decrease as the aromatic vinyl content decreases, and the amount of 1,2-vinyl bonds decreases as the amount of polar substance added relative to the amount of polymerization initiator added decreases. The glass transition temperature (Tg) tends to decrease by about 1°C when the content of aromatic vinyl monomer units is reduced by 1 mass%, and the glass transition temperature (Tg) tends to decrease by about 1°C when the amount of 1,2-vinyl bonds is reduced by 2 mol%. The amount of 1,2-vinyl bonds in the conjugated diene polymer of this embodiment can be controlled by adjusting the amount of polar substance added to the polymerization initiator, and the amount of 1,2-vinyl bonds tends to increase by increasing the amount of polar substance added, thereby controlling the glass transition temperature (Tg).

[0024] [Method for producing conjugated diene polymer] The method for producing a conjugated diene polymer of this embodiment includes, for example, a polymerization step of polymerizing a conjugated diene compound and an aromatic vinyl compound using an organolithium compound as a polymerization initiator to obtain a conjugated diene polymer, and, if necessary, a modification step of reacting an active terminal of the conjugated diene polymer with a coupling agent (hereinafter referred to as "modifier") containing a modifying group to obtain a modified conjugated diene polymer. The method for producing a conjugated diene polymer of this embodiment includes a finishing step of removing the solvent from the polymer solution. From the viewpoint of processability of the conjugated diene polymer, a modifier capable of reacting with the active terminal of the conjugated diene polymer to produce a modified conjugated diene polymer having four or more branches is preferred. From the viewpoint of polymerization productivity and obtaining a stable modification rate, preferred modifiers include, for example, isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, nitrogen-containing carbonyl compounds, nitrogen-containing vinyl compounds, nitrogen-containing epoxy compounds, and nitrogen-containing alkoxysilane compounds.

[0025] In this specification, the term "compound" refers to a compound before polymerization, and the term "monomer unit" refers to a structural unit that constitutes a polymer.

[0026] Examples of organolithium compounds as polymerization initiators include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium. In particular, n-butyllithium and sec-butyllithium are preferred from the viewpoints of industrial availability and ease of control of the polymerization reaction.

[0027] As the polymerization initiator, an organolithium compound having no active hydrogen or a substituted amino group with a structure in which the active hydrogen is protected may be used. Examples of organolithium compounds having a substituted amino group with a structure that does not have active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium. Examples of alkyllithium compounds having an amino group with a structure in which an active hydrogen is protected include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0028] The organolithium compound having a substituted amino group can also be used as a solubilized oligomeric organolithium compound by reacting it with a small amount of a polymerizable monomer, such as 1,3-butadiene, isoprene, or styrene.

[0029] These organolithium compounds may be used alone or in combination of two or more, or may be used in combination with other organometallic compounds.

[0030] The Mooney viscosity of the conjugated diene polymer can be controlled by adjusting the amount of organolithium added in the polymerization step. That is, the Mooney viscosity decreases when the amount of organolithium added increases, and increases when the amount of organolithium added decreases. By utilizing this, the Mooney viscosity can be controlled to a desired value.

[0031] Conjugated diene compounds that are polymerization monomers used in the polymerization step 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, from the viewpoint of ease of industrial availability, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. These may be used alone or in combination of two or more.

[0032] Examples of aromatic vinyl compounds that are polymerization monomers used in the polymerization step include, but are not limited to, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred from the viewpoint of industrial availability. These may be used alone or in combination of two or more. By including such a structural unit based on an aromatic vinyl compound, the hardness of the modified conjugated diene polymer of this embodiment can be controlled when used as a material for the outsole of a shoe.

[0033] In the polymerization step, in addition to the above-mentioned polymerizable monomers, other monomers may also be used. Examples of other monomers include, but are not limited to, non-conjugated polyene compound monomers such as ethylidene norbornene, dicyclopentadiene, vinyl norbornene, and divinylbenzene; and cyclic non-conjugated polyene compound monomers such as dicyclopentadiene, vinyl norbornene, and ethylidene norbornene. By using such other monomers, when the conjugated diene polymer of the present embodiment is used as a material for the outsole of a shoe, the balance between breaking strength, gripping properties, and abrasion resistance tends to be further improved. These may be used alone or in combination of two or more.

[0034] The polymerization reaction of the conjugated diene polymer is preferably carried out in a solvent. Examples of the solvent include, but are not limited to, hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific examples of the hydrocarbon solvent 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.

[0035] In the polymerization step, a polar compound may be added. This allows the aromatic vinyl compound and the conjugated diene compound to be randomly copolymerized. Polar compounds tend to be usable as vinylating agents for controlling the microstructure of the conjugated diene moiety. They also tend to be effective in accelerating the polymerization reaction.

[0036] 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. Among these, 2,2-bis(2-oxolanyl)propane is preferred from the viewpoint of obtaining a high modification rate when the conjugated diene polymer of this embodiment is used as a modified conjugated diene polymer. These polar compounds may be used alone or in combination of two or more.

[0037] The amount of polar compound used is not particularly limited and can be selected depending on the purpose, but is preferably 0.01 mol or more and 100 mol or less per mol of the polymerization initiator. Such polar compounds (vinylating agents) can be used as modifiers for the microstructure of the conjugated diene portion of the polymer in an appropriate amount depending on the desired vinyl bond amount. Many polar compounds also have an effective randomizing effect in the copolymerization of a conjugated diene compound and an aromatic vinyl compound, and tend to be used as agents for adjusting the distribution of the aromatic vinyl compound or the amount of styrene blocks. As a method for randomizing a conjugated diene compound and an aromatic vinyl compound, for example, as described in JP-A-59-140211, a method may be used in which a copolymerization reaction is initiated with the entire amount of styrene and a portion of 1,3-butadiene, and the remaining 1,3-butadiene is intermittently added during the copolymerization reaction.

[0038] In the polymerization step, polymerization may be carried out by either a batch or continuous polymerization method. However, from the viewpoint of stably producing a conjugated diene polymer containing high and low molecular weight components and controlled branching, continuous polymerization is preferred, and polymerization in a single reactor or a reactor in which two or more reactors are connected is more preferred. Since a longer residence time tends to broaden the molecular weight distribution, the molecular weight distribution can be adjusted by adjusting the residence time. Furthermore, to achieve a modification rate of 30% by mass or more, the polymerization temperature is preferably 50°C or higher and 100°C or lower, and the conjugated diene polymer is preferably polymerized at a solid content of 16.0% by mass or lower. Furthermore, the molecular weight distribution can also be adjusted by the polymerization temperature; increasing the polymerization temperature tends to broaden the molecular weight fraction.

[0039] The modification step is not particularly limited, and can be carried out using a reactor equipped with a stirrer and capable of temperature control with a jacket, and an in-line mixer, static mixer, or the like may also be used.

[0040] As the modifying agent used in the modification step, from the viewpoints of polymerization productivity and a high modification rate, a nitrogen-containing modifying agent is preferred, and examples thereof include isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, nitrogen-group-containing carbonyl compounds, nitrogen-group-containing vinyl compounds, nitrogen-group-containing epoxy compounds, and nitrogen-group-containing alkoxysilane compounds.

[0041] Furthermore, from the viewpoint of processability when the rubber composition using the conjugated diene polymer of this embodiment is used as a material for an outsole, the number of branches due to the modifier is preferably high. The number of branches is not particularly limited, but from the viewpoint of processability, 3 branches or more is preferred, and 4 branches or more is more preferred. The upper limit of the number of branches is not particularly limited, but from the viewpoint of processability, 30 branches or less is preferred.

[0042] The nitrogen-containing modifier may be a nitrogen-containing epoxy compound. Examples of the nitrogen-containing epoxy compound include, but are not limited to, N,N-diglycidyl-4-glycidoxyaniline, 1-N,N-diglycidylaminomethyl-4-glycidoxycyclohexane, 4-(4-glycidoxyphenyl)-(N,N-diglycidyl)aniline, 4-(4-glycidoxyphenoxy)-(N,N-diglycidyl)aniline, 4-(4-glycidoxybenzyl)-(N,N-diglycidyl)aniline, 4-(N,N'-diglycidyl-2-piperazinyl)-glycidoxybenzene, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-m-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. Of these, N,N-diglycidyl-4-glycidoxyaniline and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane are more preferred.

[0043] As these nitrogen-containing modifiers, nitrogen group-containing alkoxysilane compounds are more preferred from the viewpoints of polymerization productivity and a high modification rate of the conjugated diene polymer of the present embodiment, and tensile strength when the conjugated diene polymer of the present embodiment is used as a material for an outsole.

[0044] Examples of the nitrogen group-containing alkoxysilane compound include, but are not limited to, 3-(4-methylpiperazin-1-yl)propyltriethoxysilane, 3-(4-methylpiperazin-1-yl)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-trimethoxy ... 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-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, tris(3-trimethoxysilylpropyl)amine, tris(3-methyldimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine tris(trimethoxysilylpropyl)amine, tris(3-methyldiethoxysilylpropyl)amine, tris(trimethoxysilylmethyl)amine, tris(2-trimethoxysilylethyl)amine, tris(4-trimethoxysilylbutyl)amine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, and 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.

[0045] In the method for producing a conjugated diene polymer of this embodiment, a deactivator, a neutralizer, or the like may be added at the end of the polymerization step, if necessary. Examples of the deactivator include, but are not limited to, water; alcohols such as methanol, ethanol, and isopropanol; etc. The term "final stage of the polymerization process" used herein refers to a state in which 95% or more of the added monomers have been consumed in the polymerization. Examples of neutralizing agents include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture having 9 to 11 carbon atoms, mainly 10 carbon atoms); aqueous solutions of inorganic acids; and carbon dioxide gas.

[0046] In the method for producing a conjugated diene polymer of this embodiment, it is preferable to add a rubber stabilizer at the end of the polymerization step from the viewpoint of preventing gel formation and improving processing stability. The rubber stabilizer is not limited to the following and known stabilizers can be used, but preferred are antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (hereinafter also referred to as "BHT"), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol) propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol.

[0047] In the method for producing a conjugated diene-based polymer of the present embodiment, a rubber softener may be added as needed, for example, at the end of the polymerization step, from the viewpoint of improving polymer productivity and processability when a filler or the like is blended in the rubber composition when an outsole is produced using the rubber composition. Examples of rubber softeners include, but are not limited to, extender oils, liquid rubbers, resins, etc. From the viewpoints of processability, productivity, and economy, extender oils are preferred. The method for adding a rubber softener to a conjugated diene polymer is not limited to the following, but a preferred method is to add the rubber softener to a polymer solution, mix, and then remove the solvent from the resulting polymer solution containing the rubber softener.

[0048] Examples of extender oils include naphthenic oil and paraffin oil. The content of extender oil in the rubber composition using the modified conjugated diene polymer of this embodiment is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less, from the viewpoint of suppressing deterioration over time when used as an outsole material.

[0049] 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. When hydrogenating, all of the unsaturated groups may be hydrogenated, or some may remain.

[0050] The effect of adding the resin is to improve the processability of a rubber composition containing the conjugated diene polymer and a filler, etc., and also tends to improve the breaking strength of a vulcanized product.

[0051] The finishing step is to remove the solvent from the polymer solution to obtain the conjugated diene-based polymer of the present embodiment. As the obtaining method, a known method can be used, and examples thereof include a method of separating the solvent by steam stripping or the like, filtering the polymer, and then dehydrating and drying it to obtain the polymer, a method of concentrating the polymer in a flashing tank and further devolatilizing it with a vent extruder or the like, and a method of directly degassing it with a drum dryer or the like.

[0052] (water content) The conjugated diene polymer of the present embodiment preferably has a water content of 0.6% by mass or less, more preferably 0.55% by mass or less, and even more preferably 0.40% by mass or less. By keeping the moisture content at 0.6% by mass or less, for example, condensation does not form on the packaging material for the molded article, and the effect of improving quality can be obtained. The water content of the conjugated diene polymer of the present embodiment can be measured by the method described in the examples below. The water content of the conjugated diene polymer can be controlled within the above range by adjusting the Mg content.

[0053] (extension oil) The conjugated diene-based polymer of the present embodiment preferably does not contain an extender oil, from the viewpoint of suppressing coloring when used as a material for an outsole.

[0054] (Molded article of conjugated diene polymer) From the viewpoint of transportation and storage, the conjugated diene polymer of this embodiment is preferably formed into a block-shaped (rectangular) bale from an industrial perspective. There are no particular limitations on the production method, but for example, a block-shaped bale can be obtained by applying a predetermined pressure to crumb-shaped rubber obtained by removing the solvent by steam stripping or the like and then drying. There are no limitations on the pressure, temperature, or pressure holding time during molding, but it is preferred that the pressure be 5 MPa or more and 25 MPa or less, the temperature be 10°C or more and 125°C or less, and the pressure holding time be 1 second or more and 5 minutes or less.

[0055] [Rubber composition] The rubber composition of the present embodiment contains the conjugated diene polymer of the present embodiment as a rubber component. The rubber composition of the present embodiment preferably contains 100 parts by mass of a rubber component containing the conjugated diene polymer of the present embodiment and 20 parts by mass or more of an inorganic filler. The rubber composition of the present embodiment contains the conjugated diene polymer of the present embodiment described above, and thus has excellent gripping properties and abrasion resistance.

[0056] In the rubber composition of the present embodiment, the content of the conjugated diene-based polymer of the present embodiment in the rubber component may be 100% by mass, but from the viewpoint of improving abrasion resistance and breaking strength when used as an outsole material, it is preferably 90% by mass or less, preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. In the rubber composition of the present embodiment, the content of the conjugated diene polymer of the present embodiment in the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and even more preferably 30% by mass or more, based on the total amount of the rubber component, from the viewpoint of improving gripping properties when used as a material for an outsole.

[0057] (Rubber polymer other than modified conjugated diene polymer in rubber component) The rubber composition of the present embodiment may contain, as a rubber component, a rubbery polymer other than the conjugated diene-based polymer of the present embodiment. Examples of the rubber-like polymer include diene rubbers such as natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), butyl rubber (IIR), acrylonitrile-chloroprene rubber, acrylonitrile-isoprene rubber, styrene-chloroprene rubber, and styrene-isoprene rubber. These may be used alone or in combination. Preferred are rubber-like polymers selected from natural rubber, isoprene rubber, butadiene rubber, butyl rubber, acrylonitrile-butadiene rubber, and styrene-butadiene rubber, and more preferred are butadiene rubber (BR) and isoprene rubber (IR).

[0058] The conjugated diene polymer of the present embodiment can be used alone as the rubber component constituting the rubber composition of the present embodiment, but when a rubbery polymer other than the conjugated diene polymer of the present embodiment is contained, the content of the rubbery polymer is preferably 10 mass % or more, more preferably 30 mass % or more, even more preferably 50 mass % or more, and still more preferably 60 mass % or more, based on the total amount of the rubber component. When the rubber composition of the present embodiment is used as an outsole material, the rubber polymer content within the above range tends to further improve abrasion resistance and breaking strength. Also, from the viewpoint of improving gripping properties when the rubber composition of the present embodiment is used as an outsole material, the rubber polymer content is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0059] (filler) The rubber composition of the present embodiment contains a filler. From the viewpoint of improving gripping properties and abrasion resistance when the rubber composition of the present embodiment is used as a material for an outsole, the content of the filler is 20 parts by mass or more, preferably 30 parts by mass or more, and more preferably 35 parts by mass or more, per 100 parts by mass of the total amount of the rubber components. Furthermore, from the viewpoint of reducing weight when the rubber composition of the present embodiment is used as a material for an outsole, the content of the filler is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less, per 100 parts by mass of the total amount of the rubber component.

[0060] The filler used in the rubber composition of the present embodiment is preferably an inorganic filler. As the inorganic filler, known inorganic fillers can be used, and examples thereof include, but are not limited to, silica-based inorganic fillers such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber; light calcium carbonate, heavy calcium carbonate, various surface-treated calcium carbonates; magnesium carbonate, magnesium hydroxide, aluminum hydroxide, barium sulfate, magnesium sulfate, calcium sulfate, titanium oxide, magnesium oxide, alumina, and carbon.

[0061] The inorganic filler is preferably silica. Examples include dry silica, wet silica, and synthetic silicate silica. When the inorganic filler is silica, the modifying group of the modifier is preferably an amino group, from the viewpoint of improving the interaction between the rubber component and the silica.

[0062] (Silane coupling agent) The rubber composition of the present embodiment may contain a silane coupling agent. The silane coupling agent has a group that has affinity or bonding properties for both the rubber component and the silica-based inorganic filler, and functions to strengthen the interaction between them. Generally, a compound having a sulfur bond, an alkoxysilyl group, and a silanol group in one molecule is preferably used.

[0063] Examples of silane coupling agents include, but are not limited to, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, ethoxy(3-mercaptopropyl)bis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silane [Si363 manufactured by Evonik Degussa], and NXT-Z30, NXT-Z45, NXT-Z60, and NXT silane manufactured by Momentive. Silane coupling agents containing mercapto groups, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide silane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide tetrasulfide, 3-triethoxysilylpropyl benzoyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, dimethoxymethylsilylpropyl benzothiazolyl tetrasulfide, and the like.

[0064] Among the silane coupling agents, mercapto group-containing silane coupling agents such as bis-[3-(triethoxysilyl)-propyl]-disulfide, ethoxy(3-mercaptopropyl)bis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silane [Si363 manufactured by Evonik Degussa], and NXT-Z30, NXT-Z45, NXT-Z60, and NXT silane manufactured by Momentive, and bis-[3-(triethoxysilyl)-propyl]-tetrasulfide are preferred from the viewpoint of high reinforcing effect. These silane coupling agents may be used alone or in combination of two or more.

[0065] The amount of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the rubber component, from the viewpoint of enhancing the effect of intensifying the interaction between the rubber component and the silica-based inorganic filler. Also, from the viewpoint of improving processability, the amount of the silane coupling agent is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the rubber component.

[0066] (rubber softener) The rubber composition of the present embodiment may contain a rubber softener in order to improve processability. Suitable rubber softeners include, for example, mineral oil-based rubber softeners and liquid or low-molecular weight synthetic softeners. The mineral oil-based rubber softeners are also called process oils or extender oils and are used to soften rubber, increase its volume, and improve its processability. Furthermore, the mineral oil-based rubber softeners are mixtures of aromatic rings, naphthenic rings, and paraffin chains. Softeners in which the carbon number of the paraffin chains accounts for 50% or more of the total carbons are called paraffinic, those in which the carbon number of the naphthenic rings is 30 to 45% are naphthenic, and those in which the aromatic carbon number is more than 30% are called aromatic. As the rubber softener to be used together with the conjugated diene polymer of this embodiment, one having an appropriate aromatic content is preferred because it tends to have good affinity with the conjugated diene polymer.

[0067] (Method of manufacturing rubber composition) The rubber composition of the present embodiment can be produced by mixing a rubber component containing the conjugated diene-based polymer of the present embodiment and other rubbery polymers, a filler, and, if necessary, additives such as a silane coupling agent and a rubber softener. The mixing method is not limited to the following, but examples thereof include a melt-kneading method using a general mixer such as an open roll, a Banbury mixer, a kneader, a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, and a method in which the components are dissolved and mixed and then the solvent is removed by heating.

[0068] 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. In addition, either a method of kneading the constituent materials of the rubber composition of the present embodiment all at once or a method of mixing them in several batches can be applied.

[0069] The rubber composition of the present embodiment may be vulcanized using a vulcanizing agent to form a vulcanized composition. Examples of the vulcanizing agent include, but are not limited to, radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds.

[0070] The sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, polymeric polysulfur compounds, and the like.

[0071] From the viewpoint of improving breaking strength through a reinforcing effect, the content of the vulcanizing agent is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of the total amount of the rubber component consisting of the conjugated diene polymer and the rubbery polymer. From the viewpoint of improving flexibility and elongation at break, the content of the vulcanizing agent is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less.

[0072] As the vulcanization method, a conventionally known method can be applied, and the vulcanization temperature is not particularly limited, but from the viewpoint of shortening the vulcanization time and increasing production efficiency, it is preferably 120°C or higher, more preferably 140°C or higher, and even more preferably 150°C or higher. Also, from the viewpoint of suppressing thermal degradation during vulcanization, it is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower.

[0073] In vulcanization, a vulcanization accelerator may be used as needed. As the vulcanization accelerator, a conventionally known material can be used, and examples thereof include, but are not limited to, sulfenamide compounds, guanidine compounds, thiuram compounds, aldehyde-amine compounds, aldehyde-ammonia compounds, thiazole compounds, thiourea compounds, and dithiocarbamate compounds.

[0074] Furthermore, examples of the vulcanization aid include, but are not limited to, zinc oxide and stearic acid.

[0075] The content of the vulcanization accelerator is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the total amount of the rubber components.

[0076] To the rubber composition of the present embodiment, various additives other than those described above, such as softeners, fillers, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants, may be added within a range that does not impair the object of the present embodiment. Known materials can be used for the heat stabilizer, antistatic agent, weather stabilizer, antioxidant, colorant, and lubricant.

[0077] [Rubber composition for shoes] The rubber composition of this embodiment is suitable as a rubber composition for shoes. The rubber composition for shoes of this embodiment is particularly suitable for use as a rubber composition for shoe soles. That is, by using the rubber composition for shoe soles of this embodiment, an outsole having excellent abrasion resistance and gripping properties can be obtained. The rubber composition for shoes of this embodiment can be used as a sole material for all types of footwear, including, but not limited to, sports shoes, running shoes, trekking shoes, and casual shoes. [Example]

[0078] Hereinafter, the present embodiment will be described in detail with reference to specific examples and comparative examples, but the present invention is not limited to the following examples and comparative examples in any way. Hereinafter, "parts" means "parts by mass" unless otherwise specified. Various physical properties in the examples and comparative examples were measured by the methods shown below. In the following description, the modified conjugated diene polymer and the unmodified conjugated diene polymer may be collectively referred to as the conjugated diene polymer.

[0079] (Molecular weight distribution (MWD), content of conjugated diene polymers with a molecular weight of 100,000 or less, content of conjugated diene polymers with a molecular weight of 1,000,000 or more) A gel permeation chromatography (hereinafter also referred to as "GPC") measuring device equipped with three connected columns packed with polystyrene gel was used to measure chromatograms, and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the conjugated diene polymers of the Examples and Comparative Examples described below were determined based on a calibration curve using standard polystyrene, and the molecular weight distribution (MWD) was calculated from Mw / Mn. The contents of conjugated diene polymers of 100,000 or less and 1,000,000 or more were calculated from the area ratios of molecular weights of 100,000 or less and 100 or more, respectively, in the obtained GPC chart. The specific measurement conditions are shown below. 20 μL of the following measurement solution was injected into the GPC measurement device and the measurement was carried out. <Measurement conditions> Device: Tosoh Corporation, product name "HLC-8320GPC" Eluent: 5mmol / L triethylamine in tetrahydrofuran (THF) Guard column: Tosoh Corporation's product name "TSKguardcolumn SuperH-H" Separation column: Tosoh Corporation product names "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000" connected in this order. Oven temperature: 40°C Flow rate: 0.6mL / min Detector: RI detector (Tosoh Corporation, product name "HLC8020") Measurement solution: 10 mg of sample dissolved in 20 mL of THF

[0080] (Mooney viscosity) The Mooney viscosity of the conjugated diene polymers of the examples and comparative examples described below was measured using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) in accordance with JIS K6300 (ISO 289-1) using an L-shaped rotor. First, the sample was preheated at 100°C for 1 minute, and then the rotor was rotated at 2 rpm. The torque was measured after 4 minutes to determine the Mooney viscosity at 100°C.

[0081] (denaturation rate) The modification rate is calculated by utilizing the adsorption characteristics of a modified conjugated diene polymer in a specific column. Furthermore, a column with this characteristic adsorbs nitrogen. In other words, the modification rate is the proportion of nitrogen-containing conjugated diene polymers. The modification rate of the modified conjugated diene polymer was measured by a column adsorption GPC method as follows, utilizing the property of the modified conjugated diene polymer to be adsorbed onto a column. The amount of adsorption onto the silica-based column was measured by subtracting the chromatogram of a sample solution containing the sample and low-molecular-weight internal standard polystyrene measured using a column packed with polystyrene-based gel from the chromatogram measured using a column packed with silica-based gel, and the modification rate was calculated. The GPC measurement conditions using a polystyrene column are as follows: 20 μL of the measurement solution below was injected into the GPC measurement device and the measurement was carried out. <GPC measurement conditions using a polystyrene column> Device: Tosoh Corporation, product name "HLC-8320GPC" Eluent: THF containing 5mmol / L triethylamine Guard column: Tosoh Corporation's product name "TSKguardcolumn SuperH-H" Column: Tosoh Corporation product names "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000" connected in this order Oven temperature: 40°C Flow rate: 0.6mL / min Detector: RI detector (Tosoh HLC8020) Measurement solution: 10 mg of sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF to prepare a sample solution. The conditions for GPC measurement using a silica column are as follows: 50 μL of the measurement solution below was injected into the GPC measurement device and measurement was carried out. <GPC measurement conditions using a silica column> Device: Tosoh Corporation, product name "HLC-8320GPC" Eluent:THF Guard column: GL Sciences product name "DIOL 4.6 x 12.5 mm 5 micron" Separation column: Agilent Technologies' Zorbax PSM-1000S, PSM-300S, and PSM-60S columns connected in this order Oven temperature: 40°C Flow rate: 0.5mL / min Detector: RI detector (Tosoh HLC8020) <Calculation method of denaturation rate>: The total peak area of ​​the chromatogram using the polystyrene-based column was set to 100, the peak area of ​​the sample was set to P1, the peak area of ​​the standard polystyrene was set to P2, and the total peak area of ​​the chromatogram using the silica-based column was set to 100, the peak area of ​​the sample was set to P3, and the peak area of ​​the standard polystyrene was set to P4. The modification rate (% by mass) was calculated using the following formula. Modification rate (mass%) = [1-(P2 x P3) / (P1 x P4)] x 100 (However, P1+P2=P3+P4=100)

[0082] (Aromatic vinyl monomer unit content) 100 mg of the sample was dissolved in 100 mL of chloroform to prepare a measurement sample. The content (mass%) of the aromatic vinyl monomer unit relative to 100 mass% of the conjugated diene polymer of the sample Examples and Comparative Examples was measured based on the amount of absorption at the ultraviolet absorption wavelength (around 254 nm in the case of styrene) by the aromatic group of the aromatic vinyl monomer unit. The measurement device used was a spectrophotometer "UV-2450" manufactured by Shimadzu Corporation.

[0083] (1,2-vinyl bond content) Conjugated diene polymers of the examples and comparative examples described below were used as samples, and 50 mg of the sample was dissolved in 10 mL of carbon disulfide to prepare a measurement sample. -1The absorbance at a predetermined wave number was measured in the range of 100 Hz to 100 Hz, and the microstructure of the butadiene moiety, i.e., the 1,2-vinyl bond content (mol%) was determined according to the calculation formula of Hampton's method (method described in R.R. Hampton, Analytical Chemistry 21, 923 (1949)). The measuring device used was a Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation.

[0084] (metal content) The amount of metal contained in the conjugated diene polymers of the examples and comparative examples described below was measured using an inductively coupled plasma (ICP, Inductively Coupled Plasma, manufactured by Shimadzu Corporation, device name: ICPS-7510). First, the conjugated diene polymer was completely dissolved in sulfuric acid and nitric acid, and the aqueous solution containing the metal components was sprayed into argon plasma. The intensity of the wavelengths of light emitted from the solution, which were specific to the various metal elements, was measured, and the amount (ppm by mass) of metals (Mg, Ti) contained in 100 parts by mass of the conjugated diene polymer was determined by the calibration curve method.

[0085] (water content) The water content of the conjugated diene polymers in the examples and comparative examples described below was measured in accordance with ISO 248-2. A moisture content of 1.0% by mass or less was judged to be good, and a moisture content exceeding 1.0% by mass was judged to be high. Conjugated diene polymer 11 of Comparative Example 4 was not measured because it was a commercially available product.

[0086] (glass transition temperature (Tg)) In accordance with ISO 22768:2006, a differential scanning calorimeter "DSC3200S" manufactured by Mac Science was used to record a DSC curve while raising the temperature 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.

[0087] [Production of Conjugated Diene Polymer] (Example 1) Sample No. 1 One autoclave was used, with an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom, an outlet at the top, and a stirrer and a jacket for temperature control. A static mixer was also connected just before the raw material inlet of the reactor. 1,3-butadiene, from which impurities such as water had been removed, was mixed at 17.0 g / min, styrene at 9.2 g / min, and n-hexane at 137.6 g / min to obtain a mixed solution. Just before this mixed solution entered the first reactor, n-butyllithium for impurity inactivation treatment was fed at 0.020 phm, mixed in the static mixer, and then continuously fed to the bottom of the first reactor. Furthermore, 0.34 phm of 2,2-bis(2-oxolanyl)propane as a polar substance and 0.078 phm of NBL (normal butyl lithium) as a polymerization initiator were continuously fed to the bottom of the reactor, and the temperature inside the reactor was maintained at 78°C to obtain a rubber solution. The rubber solution produced in the reactor was fed from the top of the reactor to a static mixer, and a modification reaction was carried out before the static mixer by continuously feeding M1 (1,3-bis(N,N-diglycidylaminomethyl)cyclohexane) as a modifier in a ratio of 1.0 equivalent (however, the amount added was calculated assuming that 4 moles of NBL react with 1 mole of M1) to the lithium of NBL fed as a polymerization initiator. To the modified polymerization solution, an antioxidant (BHT) was continuously added so that the amount was 0.2 g per 100 g of the modified conjugated diene polymer, and the modification reaction was completed. The resulting modified conjugated diene polymer solution was subjected to steam stripping using water containing Mg (20 ppm) and Ti (0.02 ppm), and the water temperature was controlled to 98°C by blowing in steam to remove the solvent. The resulting solution was then dried in a Geer oven at 80°C for 3 hours to obtain Sample No. 1. The physical properties of Sample No. 1 are shown in Table 1.

[0088] (Examples 2 to 7) Samples Nos. 2 to 7 (Comparative Examples 2 and 3) Samples Nos. 9 and 10 Modified conjugated diene polymers of Samples Nos. 2 to 7 and Comparative Examples 2 and 3 were obtained in the same manner as Sample No. 1 under the conditions shown in Table 1 below. However, in Example 6, the modifying agent M2 ((2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane) was used, and the amount added was calculated assuming that 4 mol of NBL reacts with 1 mol of this modifying agent M2. In Example 7, water containing Mg (20 ppm) and no Ti (0 ppm) was used during solvent removal. In Comparative Examples 2 and 3, water containing neither Mg nor Ti was used.

[0089] (Comparative Example 1) Sample No. 8 A 10 L autoclave equipped with a stirrer and a jacket and capable of temperature control was used as a reactor. 4,607 g of normal hexane, 263 g of styrene, 487 g of 1,3-butadiene, and 1.61 mmol of 2,2-bis(2-oxolanyl)propane as a polar substance, from which impurities had been removed, were placed in the reactor, and when the temperature inside the reactor reached 45°C, 2.44 mmol of a polymerization initiator, n-butyllithium, was added to initiate polymerization. Immediately after the start of polymerization, the temperature inside the reactor began to rise, reaching a peak of 83°C, and when a decrease in temperature was confirmed, 0.61 mmol of modifier M1 was added, followed by stirring for a further 30 minutes. To the modified polymerization solution, an antioxidant (BHT) was added in an amount of 0.2 g per 100 g of the modified conjugated diene polymer to terminate the modification reaction. The resulting modified conjugated diene polymer solution was subjected to steam stripping using water containing neither Mg nor Ti, and the water temperature was controlled to 98°C by blowing in steam to remove the solvent. The resulting solution was then dried in a gear oven at 80°C for 3 hours to obtain sample No. 8.

[0090] (Comparative Example 4) Sample No. 11 In Comparative Example 4, ESBR 1502 manufactured by ENEOS Materials was used.

[0091] [Table 1]

[0092] [Production of Rubber Composition] (Examples A1 to A7), (Comparative Examples A1 to A4) (Examples B1 to B7), (Comparative Examples B1 to B4) (Examples C1 to C7), (Comparative Examples C1 to C4) (Examples D1 to D7), (Comparative Examples D1 to D4) (Examples E1 to E7), (Comparative Examples E1 to E4) Table 2 below shows compoundings A to E as compounding examples of rubber compositions using the conjugated diene polymers (samples No. 1 to 11) prepared as described above. A rubber composition was obtained by compounding 100 parts by mass of a rubber component containing a conjugated diene polymer with a predetermined amount of an inorganic filler and the like. More specifically, the materials in Table 2 below were kneaded by the following method to obtain rubber compositions. In the first stage of mixing, raw rubber (modified conjugated diene polymer and specified rubber), inorganic filler (silica), silane coupling agent, zinc oxide, stearic acid, and antioxidant were mixed at a filling rate of 65% and a rotor rotation speed of 30 rpm using an internal mixer (capacity 0.6 L) equipped with a temperature control device. At this time, the temperature of the internal mixer was controlled, and each rubber composition (compound) was obtained at a discharge temperature of 125 to 135°C. Thereafter, in the second stage of kneading, the rubber composition discharged in the first stage was passed through an open roll set at 73°C seven times. After cooling, as the third stage of kneading, sulfur and vulcanization accelerators 1 and 2 were added to the second stage compound in the amounts shown in Table 3 below and kneaded using an open roll set at 73°C. This was common to all compoundings A to E. Thereafter, the rubber composition was molded and vulcanized at 160°C in a vulcanizing press, and the properties of the vulcanized rubber composition were evaluated. Specifically, the evaluation was carried out by the method described below. The vulcanization time and evaluation results are shown in Tables 4 to 8. In addition, when a rubber composition was prepared using the conjugated diene polymer of Example 1 and Compounding A, it was designated as Example A1, and similarly, the examples and comparative examples of rubber compositions were designated by their numbers and compounding symbols, such as (Examples A1 to E7), (Comparative Examples A1 to E4), etc. That is, when a rubber composition is obtained by compounding B using the conjugated diene polymer of Example 2, it is designated as Example B2 in the following rubber composition.

[0093] [Table 2]

[0094] [Table 3]

[0095] The materials used for each component in Tables 2 and 3 are as follows: Conjugated diene polymers: Examples 1 to 7 and Comparative Examples 1 to 4 in Table 1 BR (Ube Industries' "UBEPOL U150") IR (Nipol IR2200, manufactured by Nippon Zeon Co., Ltd.) NBR (manufactured by Nippon Zeon Co., Ltd., product name "Nipol DN4050") BIIR (manufactured by JSR Corporation, product name "BROMOBUTYL2244") ·NR(RSS#1) Silica (trade name "Ultrasil VN3" manufactured by Evonik Degussa) Silane coupling agent (Evonik Degussa brand name "Si69", bis(triethoxysilylpropyl)tetrasulfide) Zinc oxide (zinc oxide) Antioxidant (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) Vulcanization accelerator 1 (2-mercaptobenzothiazole: MBT) Vulcanization accelerator 2 (N-(tert-butyl)-2-benzothiazole sulfenamide: TBBS)

[0096] [Evaluation of Rubber Composition] (Evaluation 1) Formability The degree of shrinkage of the rubber composition sheet obtained after passing through the open rolls seven times in the second stage kneading was evaluated on a 4-point scale. 4: Almost no shrinkage 3:Shrinks a little 2: The surface of the sheet is slightly wavy and shrinks. 1: The surface of the sheet also becomes significantly wavy and shrinks.

[0097] (Evaluation 2) Grip: Coefficient of dynamic friction The dynamic friction coefficient was measured using a dynamic friction tester (Heidon Tribogear Type 40) manufactured by Shinto Scientific Co., Ltd. The sliding surface was a ceramic tile, lubricated with water, and a vulcanized sheet 3 mm thick, 30 mm wide, and 30 mm deep was attached to a blade holder-type jig. The grip was evaluated as the average value of the dynamic friction coefficient under a load of 500 gf, a sliding speed of 10 mm / min, and a sliding distance of 80 mm. In Tables 4 to 8, the evaluation results of Comparative Examples A2, B2, C2, D2, and E2 were indexed with an index value of 100, and the evaluation results of Blends A to E were indexed. The larger the value, the better the gripping ability.

[0098] (Rating 3) Abrasion resistance The specific wear volume (unit: mm) was measured using a DIN abrasion tester (manufactured by Ueshima Seisakusho) in accordance with JIS K6264. 3 ) was measured. In Tables 4 to 8, the evaluation results of Comparative Examples A2, B2, C2, D2, and E2 were indexed with an index value of 100, and the evaluation results of Blends A to E were indexed. The larger the value, the more excellent the abrasion resistance.

[0099] (Rating 4) Silica dispersibility The viscoelastic parameters of the vulcanized specimens were measured in torsion mode using a Rheometrics Scientific viscoelastic testing machine (ARES). The difference in storage modulus (G') at 50°C, frequency 10 Hz, strain 0.1% and strain 10% was defined as ΔG' and used as an index of silica dispersibility. In Tables 4 to 8, the evaluation results of Comparative Examples A2, B2, C2, D2, and E2 were indexed based on an evaluation score of 100, and the evaluation results of Blends A to E were indexed. The smaller the value, the better the silica dispersibility.

[0100] [Table 4]

[0101] [Table 5]

[0102] [Table 6]

[0103] [Table 7]

[0104] [Table 8]

[0105] As shown in Table 1, Comparative Examples 1 and 2 did not contain Mg and contained a large amount of water. Furthermore, as in Comparative Example 3, when the content of aromatic vinyl monomer units and the vinyl bond amount were outside the ranges of the present invention, the water content was less than 1% by mass even without containing Mg. As shown in Tables 4 to 8, the same tendency was observed in all the formulations. That is, in the case of conjugated diene polymer 10, in which the content of aromatic vinyl monomer units and the amount of vinyl bonds are outside the ranges of the present invention, the sum of gripping property and abrasion resistance did not exceed 200 in any of the formulations, whereas the sum of gripping property and abrasion resistance exceeded 200 in the case of conjugated diene polymers 1 to 7, indicating an excellent balance between gripping property and abrasion resistance. Furthermore, silica dispersibility was evaluated by ΔG', an index affected by glass transition temperature, so it is best to compare polymers with the same glass transition temperature. Therefore, it is best to compare conjugated diene polymer 1 containing both Mg and Ti with conjugated diene polymer 7 containing Mg but no Ti and conjugated diene polymer 9 containing neither Mg nor Ti. The silica dispersibility was best when both Mg and Ti were contained, followed by when Mg was contained. The moldability was better as the molecular weight distribution decreased. [Industrial Applicability]

[0106] The modified conjugated diene-based polymer and rubber composition of the present invention are useful in the field of shoe soles, particularly as sole materials for all types of footwear such as sports shoes, running shoes, trekking shoes, and casual shoes, and further have industrial applicability as materials for various components such as tires, rubber compositions for housing, and industrial products including vibration-proof rubber.

Claims

1. The content of aromatic vinyl monomer units is 30% by mass or more and 45% by mass or less, the amount of 1,2-vinyl bonds is 30 mol % or more and 60 mol or less, Mooney viscosity is 30 or more and 90 or less, The molecular weight distribution obtained by GPC (gel permeation chromatography) is 1.7 or more and less than 3.0, The content of the conjugated diene polymer having a molecular weight of 100,000 or less is 5% by mass or more, The content of the conjugated diene polymer having a molecular weight of 1,000,000 or more is 5% by mass or more, The Mg content is 10 ppm or more. Conjugated diene polymer.

2. The modification rate is 30% by mass or more. The conjugated diene polymer according to claim 1 .

3. The glass transition temperature is -40°C or higher and 5°C or lower. The conjugated diene polymer according to claim 1 .

4. The Ti content is 2 ppm or more. The conjugated diene polymer according to claim 1 .

5. the 1,2-vinyl bond content is 45 mol or more and 60 mol or less; The conjugated diene polymer according to claim 1 .

6. The water content is 0.6% by mass or less. The conjugated diene polymer according to claim 1 .

7. Does not contain extender oil The conjugated diene polymer according to claim 1 .

8. A molded article of a conjugated diene polymer, The conjugated diene polymer according to claim 1 .

9. A rubber composition comprising the conjugated diene polymer according to any one of claims 1 to 8 as a rubber component. Rubber composition.

10. The rubber composition 100 parts by mass of a rubber component containing the conjugated diene-based polymer according to any one of claims 1 to 8; 20 parts by mass or more of an inorganic filler; containing The rubber composition of claim 9.

11. The rubber composition according to claim 9, which is a rubber composition for shoes.

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