Modified conjugated diene polymers, shoe rubber compositions containing the same, and outsoles

Abstract

To provide a modified conjugated diene polymer that excels in tensile strength and strikes a balance between grip performance and wear resistance, a rubber composition for shoes, and an outsole.SOLUTION: A modified conjugated diene polymer satisfies the following I)-V) conditions. I) The glass transition temperature is -80°C to -30°C. II) The 1,2-vinyl bond content is 13 mol% to 30 mol%. III) The Mooney viscosity is 30-70 as measured in accordance with JIS K6300 (ISO 289-1). IV) The modification rate is 30 mass% or more. V) The content of bonded aromatic vinyl is 40 mass% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a modified conjugated diene polymer, a rubber composition for shoes containing the same, and an outsole.

Background Art

[0002] Rubber compositions for shoes (for example, rubber compositions for shoe soles such as materials for manufacturing outsoles) are required to have grip performance for enhancing safety, strength and abrasion resistance to withstand the load and impact force accompanying the wearer's movement. Also, from the viewpoint of reducing the weight of shoes, it has been proposed to use a foam for the shoe sole material. However, the foam has a problem that its abrasion resistance is inferior to that of the non-foam. (See, for example, Patent Document 1).

[0003] As a general method for improving abrasion resistance, inorganic fillers such as carbon black, calcium carbonate, and silica are blended. From the viewpoint of enabling the coloring of the shoe sole and enhancing the design property, white inorganic fillers such as silica and calcium carbonate are generally used. However, inorganic fillers such as silica are inferior in affinity with rubber compared to carbon black, so the dispersibility of silica in rubber is not always good, and this poor dispersibility causes problems such as deterioration of processability, abrasion resistance, and mechanical strength.

[0004] In response to such problems, Patent Document 2 proposes a rubber composition for a shoe sole mainly composed of a conjugated diene rubber having a structure in which a specific functional group is bonded to a conjugated diene polymer chain. However, according to the technique of Patent Document 2, although the processability is improved, the improvement effects of the grip property and abrasion resistance as a shoe sole material are not yet sufficient.

[0005] Also, Patent Document 3 discloses a composition for a foam containing 1,2-polybutadiene, vinyl-cis butadiene rubber, a thermoplastic polymer, a foaming agent, and a crosslinking agent, and describes that it is useful as a composition for a shoe sole. However, the strength, abrasion resistance, etc. of these foaming materials are not at a satisfactory level, and further improvement is required.

Prior Art Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2000-236905 [Patent Document 2] Japanese Patent Publication No. 2005-162777 [Patent Document 3] Japanese Patent Publication No. 2006-16518 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In the field of shoe rubber compositions used in outsoles and other parts, achieving both grip and abrasion resistance simultaneously is technically challenging, and there is a demand for compositions that achieve a high level of both properties. Furthermore, while possessing these properties, tensile strength is also required when used as a shoe rubber composition.

[0008] This invention was made in view of the above-mentioned problems, and aims to provide a modified conjugated diene polymer, a shoe rubber composition, and an outsole that have excellent tensile strength and an excellent balance of grip and abrasion resistance. [Means for solving the problem]

[0009] As a result of diligent research to solve the problems of the prior art described above, the present inventors have discovered that by controlling the glass transition temperature, the amount of 1,2-vinyl bonds, Mooney viscosity, modification rate, and the amount of bonded aromatic vinyl of the modified conjugated diene polymer, a modified conjugated diene polymer can be obtained that provides excellent tensile strength and a good balance of grip and abrasion resistance for shoe rubber compositions, thus completing the present invention.

[0010] In other words, the present invention is as follows: <1> A modified conjugated diene polymer that satisfies the following conditions I) to V). I) Glass transition temperature is -80°C to -30°C II) 1,2-vinyl bond content: 13 mol% to 30 mol% III) Mooney viscosity measured under JIS K6300 (ISO 289-1) conditions is 30-70 IV) Degeneration rate of 30% by mass or more V) The amount of bonded aromatic vinyl is 40% by mass or less. <2> When the total area of ​​the molecular weight distribution curve obtained by gel permeation chromatography of the modified conjugated diene polymer is set to 100%, the area ratio of molecules with a molecular weight of 100,000 or less is 8% or more. <1> Modified conjugated diene polymers as described above. <3> When the total area of ​​the molecular weight distribution curve obtained by gel permeation chromatography of the modified conjugated diene polymer is set to 100%, the area ratio of molecules with a molecular weight of 1,000,000 or more is 5% or more. <1> or <2> Modified conjugated diene polymers as described above. <4> The ratio of the amount of blocked aromatic vinyl to the amount of bonded aromatic vinyl is 0.23 or less. <1> ~ <3> A modified conjugated diene polymer as described in any of the following. <5> The modified conjugated diene polymer contains a polymer having conjugated diene monomer units and aromatic vinyl monomer units, and having a nitrogen atom-containing functional group. <1> ~ <4> A modified conjugated diene polymer as described in any of the following. <6> <1> ~ <5> 100 parts by mass of a rubber component containing a modified conjugated diene polymer (A) as described in any of the above, The inorganic filler component (B) is present in an amount of 20 parts by mass or more per 100 parts by mass of the rubber component. A rubber composition for shoes containing the following: <7> The rubber component includes a rubbery polymer (C) other than the modified conjugated diene polymer (A), The content of the modified conjugated diene polymer (A) is 90% by mass or less relative to the total amount of the rubber components. The rubber-like polymer (C) content is 10% by mass or more based on the total amount of the rubber components, and the rubber composition for shoes according to <6>. <8> An outsole containing the rubber composition for shoes according to <6> or <7>.

Advantages of the Invention

[0011] According to the present invention, it is possible to provide a modified conjugated diene polymer, a rubber composition for shoes, and an outsole that are excellent in tensile strength and have an excellent balance between grip and wear resistance.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that the following present embodiment is an exemplification for explaining the present invention, and the present invention is not limited to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of its gist. In this specification, for example, the notation of a numerical range such as "1 to 100" includes both the lower limit value "1" and the upper limit value "100". The same applies to the notation of other numerical ranges.

[0013] The modified conjugated diene polymer of the present embodiment has a glass transition temperature of the modified conjugated diene polymer of -80°C to -30°C, a 1,2-vinyl bond content of 10 mol% to 30 mol%, a Mooney viscosity measured under the conditions of JIS K6300 (ISO 289-1) of 30 to 70, a modification rate of 30% by mass or more, and an amount of bonded aromatic vinyl of 40% by mass or less. With the above configuration, it is possible to provide a modified conjugated diene polymer that results in a rubber composition for shoes that is excellent in tensile strength and has an excellent balance between grip and wear resistance.

[0014] The modified conjugated diene polymer of the present embodiment is suitably used as a vulcanizate. The vulcanizate can be obtained, for example, by mixing the modified conjugated diene polymer of the present embodiment with an inorganic filler such as silica or carbon black, a rubbery polymer (C) component other than the modified conjugated diene polymer of the present embodiment, a silane coupling agent, a vulcanizing agent, a vulcanization accelerator, and a vulcanization aid to form a rubber composition, and then heating and vulcanizing it. Hereinafter, each component will be described in detail.

[0015] 〔Modified conjugated diene polymer〕 The modified conjugated diene polymer of the present embodiment satisfies the following conditions I) to V) from the viewpoint of obtaining a modified conjugated diene polymer that has excellent tensile strength and an excellent balance between grip properties and abrasion resistance and is used as a rubber composition for shoes.

[0016] I) Glass transition temperature The glass transition temperature (Tg) of the modified conjugated diene polymer of the present embodiment is -80°C to -30°C. By having a glass transition temperature within this range, the processability tends to improve. In particular, it is suitable for improving the balance of physical properties such as grip properties and abrasion resistance. In the modified conjugated diene polymer of the present embodiment, when the glass transition temperature (Tg) becomes lower, the grip properties tend to improve while maintaining the abrasion resistance. The glass transition temperature (Tg) is preferably -80°C to -35°C, more preferably -80°C to -45°C, and still more preferably -80°C to -55°C. The glass transition temperature (Tg) of the modified conjugated diene polymer of the present embodiment tends to decrease by reducing the aromatic vinyl / conjugated diene ratio, and by reducing the addition amount of the polar substance with respect to the addition amount of the polymerization initiator, the amount of 1,2-vinyl bonds becomes lower, and the glass transition temperature (Tg) tends to decrease. The glass transition temperature decreases by approximately 1°C when the amount of aromatic vinyl is reduced by 1% by mass, and the glass transition temperature (Tg) tends to decrease by approximately 1.5°C when the amount of 1,2-vinyl bonds is reduced by 2 mol%.

[0017] II) Amount of 1,2-vinyl bonds The amount of 1,2-vinyl bonds in the modified conjugated diene polymer of this embodiment is 13 mol% to 30 mol%. An amount of 1,2-vinyl bonds of 13 mol% or more is suitable for a balance between grip and abrasion resistance. An amount of 1,2-vinyl bonds of 30 mol% or less tends to improve abrasion resistance and tensile strength. When 1,3-butadiene is polymerized as the conjugated diene monomer, a mixture of 1,2-butadiene (vinyl bonds) and 1,4-butadiene (a mixture of cis and trans bonds) is produced as the polymer, and the amount of 1,2-butadiene in the butadiene of the conjugated diene copolymer (mol%) is defined as the "amount of 1,2-vinyl bonds". The glass transition temperature of the 1,2-vinyl bond (approximately -10°C) is higher than that of the cis-trans bond (approximately -100°C), and the glass transition temperature (Tg) can be adjusted by changing the ratio of 1,2-butadiene to 1,4-butadiene. The amount of 1,2-vinyl bond is more preferably 15 mol% or more. Preferably, the amount of 1,2-vinyl bond is 26 mol% or less, and more preferably 25.2 mol% or less. When high-cis-butadiene with a high amount of cis bonds is used as the rubbery polymer (C) of the shoe rubber composition, the compatibility with high-cis-butadiene can be adjusted by changing the amount of 1,2-vinyl bond in the modified conjugated diene polymer of this embodiment, and increasing the amount of 1,2-vinyl bond tends to improve compatibility with high-cis-butadiene.

[0018] The amount of 1,2-vinyl bonds in the modified conjugated diene polymer of this embodiment can be controlled by adjusting the amount of polar substance added to the polymerization initiator, and increasing the amount of polar substance tends to increase the amount of vinyl bonds.

[0019] III) Mooney Viscosity The Mooney viscosity of the modified conjugated diene polymer in this embodiment is 30 to 70. By setting the Mooney viscosity within this range, a modified conjugated diene polymer exhibiting high wear resistance while having excellent grip properties can be obtained. The Mooney viscosity is preferably 40 to 70, more preferably 50 to 70, and even more preferably 60 to 70. The Mooney viscosity was measured using a Mooney viscometer (product name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) in accordance with JIS K6300 (ISO 289-1) and an L-shaped rotor. Specifically, the sample was first preheated at 100°C for 1 minute, then the rotor was rotated at 2 rpm, and the torque after 4 minutes was measured to determine the Mooney viscosity at 100°C. The Mooney viscosity tends to increase when the modified conjugated diene polymer has a high molecular weight, a high modification rate, and a highly branched structure, and can be controlled by adjusting the amount of polymerization initiator and coupling agent added to the active ends of the conjugated diene polymer. Mooney viscosity can also be controlled by the method described in the manufacturing method section below.

[0020] IV) Degeneration rate The modification rate of the modified conjugated diene polymer in this embodiment is 30% by mass or more. A modification rate of 30% by mass or more enhances the dispersibility of the silica-based inorganic filler, which is a reinforcing material for the outsole, improving processability while yielding a modified conjugated diene polymer exhibiting excellent grip and high abrasion resistance. The modification rate is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 68% by mass or more. The upper limit of the modification rate is not particularly limited, but for example, it is 100% by mass. The modification rate of the modified conjugated diene polymer can be measured by column adsorption GPC. The modification rate is measured more specifically by the method described in the examples. The modification rate can be appropriately adjusted by the amount of modifying agent used.

[0021] In this specification, "modification rate" refers to the mass ratio of the polymer having a nitrogen atom-containing functional group to the total amount of the modified conjugated diene polymer. The nitrogen atom in the rubbery polymer in this embodiment may be introduced anywhere in the polymerization initiation end, within the molecular chain (including grafts), or at the polymerization end. As a method for introducing the nitrogen atom to the polymerization initiation end, an organolithium compound containing a nitrogen atom as described in WO2016 / 133202 may be used as a polymerization initiator.

[0022] V) Amount of bonded aromatic vinyl The bonded aromatic vinyl in the modified conjugated diene polymer of this embodiment is 40% by mass or less. Having 40% by mass or less of bonded aromatic vinyl yields a modified conjugated diene polymer that exhibits high abrasion resistance while possessing excellent grip. The bonded aromatic vinyl is preferably 11% to 37% by mass, more preferably 16% to 37% by mass, and even more preferably 16% to 35% by mass. The bonded aromatic vinyl in the modified conjugated diene polymer can be adjusted by the proportion of aromatic vinyl monomers.

[0023] In this embodiment, the modified conjugated diene polymer is preferable to satisfy the following conditions, from the viewpoint of obtaining a modified conjugated diene polymer that improves tensile strength and provides a shoe rubber composition with a superior balance of grip and abrasion resistance.

[0024] (Area ratio of molecules with a molecular weight of 100,000 or less) In this embodiment, when the total area of ​​the molecular weight distribution curve obtained by gel permeation chromatography of the modified conjugated diene polymer is set to 100%, it is preferable that the area ratio of molecules with a molecular weight of 100,000 or less is 8% or more. By setting the area ratio of molecules with a molecular weight of 100,000 or less to 8% or more, the gripping properties can be further improved. The area ratio of molecules with a molecular weight of 100,000 or less is preferably 9% or more, more preferably 10% or more, and even more preferably 11% or more. The upper limit of the area ratio of molecules with a molecular weight of 100,000 or less is not particularly limited, but for example, it may be 30% or less. The area ratio of molecules with a molecular weight of 100,000 or less can be adjusted by the method described later. The area ratio of molecules with a molecular weight of 100,000 or less can be adjusted, for example, by 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 modified conjugated diene polymer will be shifted overall towards the higher molecular weight side, resulting in a smaller area ratio of molecules with a molecular weight of 100,000 or less. If the amount of polymerization initiator is large, the molecular weight distribution curve obtained by gel permeation chromatography of the resulting modified conjugated diene polymer will be shifted overall towards the lower molecular weight side, resulting in a larger area ratio of molecules with a molecular weight of 100,000 or less.

[0025] (Area ratio of molecules with a molecular weight of 1,000,000 or more) When the total area of ​​the molecular weight distribution curve obtained by gel permeation chromatography of the modified conjugated diene polymer of this embodiment is set to 100%, it is preferable that the area ratio of molecules with a molecular weight of 1,000,000 or more is 5% or more. By setting the area ratio of molecules with a molecular weight of 1,000,000 or more to 5% or more, durability can be further improved. The area ratio of molecules with a molecular weight of 1,000,000 or more is preferably 6% or more, more preferably 6.5% or more, and even more preferably 7.5% or more. The upper limit of the area ratio of molecules with a molecular weight of 1,000,000 or more is not particularly limited, but for example, it may be 30% or less. The area ratio of molecules with a molecular weight of 1,000,000 or less can be adjusted by the amount of polymerization initiator added, similar to the area ratio of molecules with a molecular weight of 100,000 or less.

[0026] (Ratio of amount of block aromatic vinyl to amount of bonded aromatic vinyl) In this embodiment, the ratio of the amount of block aromatic vinyl (the amount of block styrene when the aromatic vinyl monomer is styrene) to the amount of bonded aromatic vinyl (the amount of bonded styrene when the aromatic vinyl monomer is styrene) of the modified conjugated diene polymer (hereinafter also referred to as the "block aromatic vinyl / bonded aromatic vinyl ratio") is preferably 0.23 or less, which tends to improve the modification rate and enhance the interaction with carbon black and silica. The block aromatic vinyl / bonded aromatic vinyl ratio is more preferably 0.20 or less, and even more preferably 0.15 or less. The lower limit of the block aromatic vinyl / bonded aromatic vinyl ratio is not particularly limited, but it may be 0.03 or more, or 0.05 or more. The ratio of block aromatic vinyl to bonded aromatic vinyl can be reduced by adjusting the ratio of aromatic vinyl monomer to conjugated diene monomer in this embodiment, increasing the amount of polar substance added, or increasing the polymerization temperature.

[0027] In this embodiment, the amount of block aromatic vinyl refers to the content (mass%) of the portion in the modified conjugated diene polymer in which eight or more aromatic vinyl monomer units are continuously bonded, that is, the value measured by the method described in the examples below. Therefore, the ratio of the amount of block aromatic vinyl to the amount of bonded aromatic vinyl in a modified conjugated diene polymer having conjugated diene monomer units and aromatic vinyl monomer units represents the proportion of aromatic vinyl monomer units that exist as block aromatic vinyl to the total aromatic vinyl monomer units. More specifically, the block styrene / bonded styrene ratio represents the proportion of styrene portions that exist as block styrene to the total styrene portions in a styrene-butadiene copolymer rubber.

[0028] The amount of blocked aromatic vinyl can be measured by a known method in which the copolymer is decomposed by Kolthoff's method (osmium tetroxide decomposition method described in IMKolthoff, et al., J. Polym. Sci. 1, 429 (1946)) and the amount of blocked aromatic vinyl insoluble in methanol is analyzed. More specifically, the method described in the examples may be used. The amount of blocked aromatic vinyl can be controlled by adjusting the amount of polar substance added when polymerizing the aromatic vinyl-conjugated diene copolymer. Increasing the amount of polar substance tends to decrease the amount of blocked aromatic vinyl.

[0029] (Mooney easing rate) The Mooney relaxation rate of the modified conjugated diene polymer of this embodiment at 100°C is preferably 0.7 or less. Modified conjugated diene polymers with a Mooney relaxation rate within this range tend to have good productivity when vulcanized and good safety and durability when used as outsoles. The Mooney relaxation rate is more preferably 0.55 or less, and even more preferably 0.5 or less. The lower limit of the Mooney relaxation rate is not particularly limited, but for example, it may be 0.3 or more. The Mooney relaxation rate is measured using a Mooney viscometer as follows. In this embodiment, the measurement temperature for the Mooney relaxation rate is set to 100°C. After preheating the sample for 1 minute, the rotor is rotated at 2 rpm, and the torque after 4 minutes is measured. This measured value is taken as the Mooney viscosity. Immediately afterward, the rotor rotation is stopped, and the torque is recorded at 0.1-second intervals from 1.6 to 5 seconds after stopping using a Mooney viscometer. The slope of the line when torque and time (seconds) are plotted on a log-log scale is determined, and its absolute value is taken as the Mooney relaxation rate. The Mooney relaxation rate is an indicator of molecular entanglement in modified conjugated diene copolymers. A lower rate indicates greater molecular entanglement. The Mooney relaxation rate tends to decrease with highly branched structures and high molecular weights, and thus serves as an indicator of branched structure.

[0030] The Mooney relaxation rate of the modified conjugated diene polymer in this embodiment tends to decrease as it becomes high molecular weight, highly branched, and highly modified. This can be controlled by adjusting the amount of polymerization initiator added and the amount of coupling agent and / or modifying agent added to the active end of the conjugated diene polymer. Reducing the amount of polymerization initiator results in a high molecular weight and a low Mooney relaxation rate. If the amount of coupling agent added is large relative to the active end of the conjugated diene polymer, for example, if the molecular structure of the coupling agent contains four functional groups that react with the active end, then bibranched and tribranched structures will also be formed, and the Mooney relaxation rate will increase. If the amount of coupling agent added is small relative to the active end of the conjugated diene polymer, the branching will decrease and a linear conjugated diene polymer will remain, which tends to increase the Mooney relaxation rate.

[0031] For example, by polymerizing a conjugated diene polymer so that its weight-average molecular weight is preferably 200,000 or more and 400,000 or less, more preferably 200,000 or more and 300,000 or less, before coupling, and then reacting the active ends of the conjugated diene polymer with a coupling agent containing functional groups that are preferably 3-branched or more, more preferably 4-branched or more, to adjust the modification rate of the modified conjugated diene polymer to 30% by mass or more, the Mooney relaxation rate can be controlled to 0.7 or less. The amount of coupling agent added to the active ends of the conjugated diene polymer is preferably 0.4 equivalents or more and 2.0 equivalents or less, more preferably 0.4 equivalents or more and 1.5 equivalents or less, and more preferably 0.4 equivalents or more and 1.0 equivalent or less. By adjusting the amount of coupling agent added within the above range, the coupling rate (modification rate) can be controlled to 30% by mass or more, and the grip and wear resistance of the vulcanized product tend to be excellent. When a coupling agent is added in excess of more than 1.0 equivalent to the active end of a conjugated diene polymer, unreacted coupling agent tends to remain, which is undesirable from an environmental perspective.

[0032] When a coupling agent contains functional groups and also acts as a modifier, the amount of coupling agent added controls the modification rate and also affects the molecular weight distribution. In particular, to improve processability with silica in non-oil-expandable systems, it is preferable to adjust the molecular weight before coupling, the number of branches by the coupling agent, and the coupling rate in order to ensure that the content of high molecular weight components for improving the abrasion resistance of shoe soles exceeds a certain amount while securing low molecular weight components.

[0033] Specifically, the weight-average molecular weight before coupling is preferably 400,000 or less, more preferably 350,000 or less, and even more preferably 300,000 or less. The lower limit is preferably 200,000 or more. A weight-average molecular weight of 400,000 or less before coupling tends to improve productivity, while a value of 200,000 or more tends to improve tensile strength and tear strength. The number of branches after coupling is preferably 3 or more, and more preferably 4 or more.

[0034] (Molecular weight distribution (MWD)) The molecular weight distribution (MWD) of the modified conjugated diene polymer in this embodiment is 1.5 to 3.5. Having a molecular weight distribution (MWD) within this range allows for the production of a modified conjugated diene polymer that exhibits excellent processability when vulcanized, while also possessing excellent wear resistance. The molecular weight distribution (MWD) is preferably 1.6 to 3.0, more preferably 1.7 to 2.7, and even more preferably 1.8 to 2.7. The molecular weight distribution (MWD) can be controlled by adjusting the residence time distribution during polymerization and the amount of coupling agent added.

[0035] (Weight average molecular weight (Mw)) The weight-average molecular weight (Mw) of the modified conjugated diene polymer in this embodiment is preferably 200,000 or more, more preferably 300,000 or more, in terms of the shape stability of the molded rubber composition and the tensile strength and abrasion resistance of the crosslinked material using the rubber composition. On the other hand, in terms of processability when the rubber composition is used as a crosslinking composition, it is preferably 1,500,000 or less, more preferably 1,000,000 or less, and even more preferably 500,000 or less. The weight-average molecular weight can be controlled by adjusting the amount of polymerization initiator and coupling agent added. The weight-average molecular weight can be increased by reducing the amount of polymerization initiator added. The weight-average molecular weight increases when the amount of modifying agent added is increased relative to the lithium, which is the active end of the conjugated diene polymer. It is maximized when 1 equivalent is added relative to the lithium at the active end, and the weight-average molecular weight tends to decrease when more than 1 equivalent of the modifying agent is added.

[0036] The weight-average molecular weight and molecular weight distribution can be calculated from the molecular weight in polystyrene equivalent, which is measured by GPC (gel permeation chromatography).

[0037] The modified conjugated diene polymer of this embodiment is preferably a polymer obtained by copolymerizing at least a conjugated diene monomer and an aromatic vinyl monomer, followed by a reaction with a nitrogen-containing modifying agent. In other words, the modified conjugated diene polymer of this embodiment preferably contains a polymer having conjugated diene monomer units and aromatic vinyl monomer units, and also having a nitrogen atom-containing functional group. When a modifying agent having multiple functional groups is used, coupling proceeds simultaneously with modification, resulting in a branched modified polymer. A branched polymer is preferable to a linear polymer of the same molecular weight because it tends to mix more easily with fillers and the like. For example, by reacting a low-molecular-weight compound having four or more nitrogen atom-containing modifying groups with the active end of a conjugated diene polymer, a modified conjugated diene polymer containing a multi-branched structure with four or more branches can be obtained.

[0038] By modifying the active ends of conjugated diene polymers with low-molecular-weight compounds containing nitrogen atoms, the interaction with inorganic fillers such as silica and carbon black is improved, the dispersibility of the inorganic fillers in the compound is improved, the processability when vulcanized is improved, and the grip and wear resistance are enhanced.

[0039] In this embodiment, "monomer" refers to the compound before polymerization, and "monomer unit" refers to the constituent unit that makes up the polymer.

[0040] The conjugated diene monomer is not particularly limited, but examples 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 ease of industrial availability, with 1,3-butadiene being the most preferred. These may be used individually or in combination of two or more.

[0041] Furthermore, the aromatic vinyl monomer is not particularly limited, but examples include 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 ease of industrial availability. These may be used individually or in combination of two or more. By including such aromatic vinyl monomer-based structural units, the hardness of the outsole can be adjusted.

[0042] Other monomers are not particularly limited, but examples include non-conjugated polyene monomers such as ethylidene norbornene, dicyclopentadiene, vinyl norbornene, and divinylbenzene; and cyclic non-conjugated polyene monomers such as dicyclopentadiene, vinyl norbornene, and ethylidene norbornene. Using such other monomers tends to improve the balance of fracture strength, grip, and abrasion resistance when used in outsoles. These may be used individually or in combination of two or more.

[0043] In this embodiment, the modified conjugated diene polymer preferably contains 40% by mass or more of conjugated diene monomer units, more preferably 50% by mass or more, and even more preferably 60% by mass or more, based on the total amount of the modified conjugated diene polymer. When the aromatic vinyl monomer unit content is 40% by mass or more, the grip and abrasion resistance when used as an outsole tend to be improved in a well-balanced manner. The conjugated diene monomer unit content is preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 91% by mass or less, based on the total amount of the modified conjugated diene polymer.

[0044] The modified conjugated diene polymer of this embodiment preferably contains aromatic vinyl monomer units. The content of aromatic vinyl monomer units is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 9% by mass or more, based on the total amount of the modified conjugated diene polymer. When the content of aromatic vinyl monomer units is 5% by mass or more, the grip when used as an outsole tends to be excellent. Furthermore, the content of aromatic vinyl monomer units is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less, based on the total amount of the modified conjugated diene polymer. When the content of aromatic vinyl monomer units is 40% by mass or less, the grip and abrasion resistance when used as an outsole tend to be improved in a well-balanced manner.

[0045] [Method for producing modified conjugated diene polymers] The method for producing the modified conjugated diene polymer of this embodiment includes, for example, the steps of polymerizing a conjugated diene monomer and an aromatic vinyl monomer using an organolithium compound as a polymerization initiator to obtain a conjugated diene polymer, and the steps of reacting the active end of the conjugated diene polymer with a coupling agent containing a modifying group to obtain a modified conjugated diene polymer. From the viewpoint of processability, a modified conjugated diene polymer containing a modified conjugated diene polymer with four or more branches that reacts with the active end of the conjugated diene polymer is preferred as the coupling agent. From the viewpoint of obtaining polymerization productivity and a stable modification rate, isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, nitrogen group-containing carbonyl compounds, nitrogen group-containing vinyl compounds, nitrogen group-containing epoxy compounds, nitrogen group-containing alkoxysilane compounds, etc., are preferred.

[0046] Polymerization may be carried out using either batch or continuous polymerization methods, but from the viewpoint of stably producing conjugated diene polymers with controlled high molecular weight and low molecular weight components, and branching, continuous polymerization is preferred, and polymerization in a single reactor or a reactor consisting of two or more connected reactors is more preferred. In order to achieve a modification rate of 30% by mass or more and an MSR of 0.7 or less, the polymerization temperature is preferably 50°C to 100°C, the solid content is preferably 16.0% by mass or less, and the conjugated diene polymer is preferably polymerized.

[0047] The denaturation method is not particularly limited, and a reactor equipped with a stirrer and temperature control via a jacket, an in-line mixer, a static mixer, etc., may be used.

[0048] Polymerization reactions of conjugated diene polymers are preferably carried out in a solvent. Examples of solvents include 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; and hydrocarbons consisting of aromatic hydrocarbons such as benzene, toluene, and xylene, and mixtures thereof.

[0049] With regard to achieving a Mooney viscosity of 30-70, when adding a four-branched coupling agent, the weight-average molecular weight of the conjugated diene polymer before coupling is preferably 400,000 or less, more preferably 350,000 or less, and even more preferably 300,000 or less. The lower limit is preferably 200,000 or more. When adding a three-branched coupling agent, the weight-average molecular weight of the conjugated diene polymer before coupling is preferably 250,000 or more and 350,000 or less.

[0050] When reacting a coupling agent that results in 3-branched or 4-branched or more branches with the active end of a conjugated diene polymer with a molecular weight of 200,000 to 300,000 before coupling, the preferred amount of coupling agent to be added is preferably 0.4 equivalents or more and 1.0 equivalent or less relative to the active end. The modification rate of the modified conjugated diene polymer is adjusted to 30% by mass or more, the weight-average molecular weight is preferably 250,000 or more, more preferably 300,000 or more, and the upper limit of the weight-average molecular weight is preferably 500,000 or less, more preferably 450,000 or less, and even more preferably 400,000 or less.

[0051] By adjusting the weight-average molecular weight of the conjugated diene polymer before coupling, and the modification rate and weight-average molecular weight of the modified conjugated diene polymer after coupling, within the above range, the Mooney viscosity can be controlled to 30-70.

[0052] The modification rate of the modified conjugated diene polymer in this embodiment is preferably within the range described above, but this modification rate can be controlled by adjusting the amount of modifying agent added to the active ends of the conjugated diene polymer before modification. The modification rate can be increased by increasing the amount of modifying agent added to the active ends of the conjugated diene polymer. In the molecular weight distribution of the modified conjugated diene polymer of this embodiment, the area where the molecular weight is 100,000 or less can be increased by increasing the amount of polymerization initiator added to reduce the molecular weight, or by reducing the modification rate to increase the amount of unmodified conjugated diene polymer that does not react with the coupling agent.

[0053] One way to control the area of ​​molecular weights below 100,000 in the molecular weight distribution to be 8% or more is to adjust the weight-average molecular weight of the conjugated diene polymer to 300,000 or less and the coupling rate to 70% or less. However, the adjustment method differs depending on the weight-average molecular weight and coupling rate, so this is not the only control method.

[0054] For example, to adjust the weight-average molecular weight of a modified conjugated diene polymer to 500,000, the weight-average molecular weight of the conjugated diene polymer before coupling is adjusted to 320,000, and a four-branched coupling agent is added to the active end of the conjugated diene polymer to obtain a modified conjugated diene polymer with a modification rate of 45%.

[0055] Increasing the area of ​​molecular weights below 100,000 in the molecular weight distribution to 8% or more tends to improve productivity. In this embodiment, by ensuring that the area with a molecular weight of 1,000,000 or more in the molecular weight distribution of the modified conjugated diene polymer accounts for 5% or more, the durability when used as an outsole improves, making it more economically viable.

[0056] The modified conjugated diene polymer of this embodiment is preferably modified to have a molecular weight distribution (Mw / Mn) of 1.5 to 3.5, more preferably 1.7 to 3.0, and even more preferably 1.8 to 2.6, as this improves productivity when used as a vulcanized product and safety and durability when used as an outsole.

[0057] The molecular weight distribution can be controlled by batch polymerization or continuous polymerization. Continuous polymerization tends to yield modified conjugated diene polymers with a broad molecular weight distribution. Adding an excessive or insufficient amount of modifying agent to the active end of the conjugated diene polymer also tends to broaden the molecular weight distribution.

[0058] As a modifying agent containing nitrogen atoms to adjust the rate of modification, isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, nitrogen group-containing carbonyl compounds, nitrogen group-containing vinyl compounds, nitrogen group-containing epoxy compounds, nitrogen group-containing alkoxysilane compounds, etc. are preferred in terms of polymerization productivity and high rate of modification.

[0059] Furthermore, from the perspective of improving productivity when manufacturing outsoles, a higher number of branches in the modifying agent is preferable. While there is no particular limit to the number of branches, from the perspective of improving productivity, 3 or more branches are preferable, and 4 or more branches are even preferable. While there is no particular upper limit to the number of branches, from the perspective of productivity, 30 branches or less is preferable.

[0060] Among these nitrogen atom-containing modifiers, nitrogen group-containing alkoxysilane compounds are more preferred in terms of polymerization productivity of rubbery polymers, high modification rate, and tensile strength when used as an outsole.

[0061] The nitrogen-containing alkoxysilane compound is not particularly limited, but examples include 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacycloheptane, and 2,2-dimethoxy-1-(3-di (Methoxymethylsilylpropyl)-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 Xy,2-ethyl-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane, tris(3-trimethoxysilylpropyl)amine, tris(3-methyldimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-methyldiethoxysilylpropyl)amine, tris(trimethoxysilylmethyl)amine, tris(2-trimethoxysilylethyl)amine, tris(4-trimethoxysilylbutyl)amine, tetrakis[3-(2,2-dimethoxy-1-aza Examples include -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.

[0062] Towards the end of the polymerization process of the modified conjugated diene polymer, deactivators, neutralizing agents, etc., may be added as needed. Examples of deactivators include, but are not limited to, water; and alcohols such as methanol, ethanol, and isopropanol. Here, "towards the end of the polymerization process" refers to the state in which 95% or more of the added monomer has been consumed by polymerization.

[0063] Examples of neutralizing agents include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched mixture of carboxylic acids with 9 to 11 carbon atoms, mainly around 10); aqueous solutions of inorganic acids; and carbon dioxide.

[0064] To prevent gel formation and improve processing stability, it is preferable to add a rubber stabilizer towards the end of the polymerization process of the modified conjugated diene polymer.

[0065] The rubber stabilizers are not limited to those listed below, but any known ones can be used. For example, antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (hereinafter also referred to as "BHT"), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol)propinate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol are preferred.

[0066] To improve the productivity of the polymer and the processability when adding fillers for outsoles during manufacturing, a rubber softener may be added as needed, particularly towards the end of the polymerization process of the rubber-like polymer.

[0067] Rubber softeners are not particularly limited, but examples include stretching oils, liquid rubber, and resins. Stretching oils are preferred in terms of processability, productivity, and cost-effectiveness.

[0068] While the method for adding a rubber softener to a conjugated diene polymer is not limited to the following, a preferred method involves adding the rubber softener to the polymer solution, mixing it, and then desolvating the resulting polymer solution containing the rubber softener.

[0069] Examples of preferred extensible oils include naphthenic oil and paraffin oil. The content of the extensible oil in the rubber composition 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 most preferably 5% by mass or less, in terms of preventing deterioration over time when used as an outsole.

[0070] Preferred resins include, but are not limited to, aromatic petroleum resins, coumarone-indene resins, terpene resins, rosin derivatives (including tung oil resins), tall oil, tall oil derivatives, rosin ester resins, natural and synthetic terpene resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, mixed aliphatic-aromatic hydrocarbon resins, coumarin-indene resins, phenol resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, monoolefin oligomers, diolefin oligomers, aromatic hydrocarbon resins, aromatic petroleum resins, hydrogenated aromatic hydrocarbon resins, 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.

[0071] These resins may be used individually or in combination of two or more. When hydrogenating, all unsaturated groups may be hydrogenated, or some may be left intact.

[0072] The effects of adding resin include improving the processability of rubber compositions that combine conjugated diene polymers and fillers, as well as tending to improve the fracture strength of vulcanized products.

[0073] As a method for obtaining the rubbery polymer of this embodiment by removing the solvent from the polymer solution, known methods can be used. Examples of such methods include separating the solvent by steam stripping, filtering off the polymer, and then dehydrating and drying it to obtain the polymer; concentrating it in a flushing tank and then deflorating it with a vent extruder or the like; and directly degassing it with a drum dryer or the like.

[0074] [Shoe rubber composition] The shoe rubber composition of this embodiment contains 100 parts by mass of a rubber component including the modified conjugated diene polymer (A) of this embodiment, and 20 parts by mass or more of an inorganic filler component (B) per 100 parts by mass of the rubber component. With this configuration, a shoe rubber composition can be provided that has excellent processability when made into a vulcanized product, and the vulcanized product containing the inorganic filler has excellent abrasion resistance and grip.

[0075] The content of the modified conjugated diene polymer (A) in the shoe rubber composition of this embodiment may be 100% by mass relative to the total amount of rubber components, but from the viewpoint of improving abrasion resistance and fracture strength when used as an outsole, 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. From the viewpoint of improving grip when used as an outsole, the content of the modified conjugated diene polymer (A) in this embodiment is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, relative to the total amount of rubber components.

[0076] [Rubber-like polymers other than modified conjugated diene polymers (A) (C)] The shoe rubber composition of this embodiment preferably contains a rubber-like polymer (C) as a rubber component. Examples of rubber-like polymer (C) 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 individually or in combination. Preferably, the rubber component is selected from natural rubber, isoprene rubber, butadiene rubber, butyl rubber, acrylonitrile-butadiene rubber, and styrene-butadiene rubber, and particularly preferably, butadiene rubber (BR) and isoprene rubber (IR).

[0077] While the modified conjugated diene polymer of this embodiment can be used alone as the rubber component, the amount of the rubbery polymer added is preferably 10% by mass or more, more preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, relative to the total amount of the rubber component including the modified conjugated diene polymer and the rubbery polymer. By having a rubbery polymer content within the above range, the abrasion resistance and fracture strength of the outsole are further improved. Furthermore, from the viewpoint of improving the grip of the outsole, the rubbery 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.

[0078] [Inorganic fillers] The shoe rubber composition of this embodiment contains an inorganic filler. From the viewpoint of improving grip performance and abrasion resistance when used as an outsole, the inorganic filler content is preferably 20 parts by mass or more, and more preferably 30 parts by mass or more, per 100 parts by mass of the total amount of rubber components. Furthermore, from the viewpoint of reducing weight when used as an outsole, the inorganic filler content 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 rubber components.

[0079] The inorganic filler used in the shoe rubber composition of this embodiment is at least one component of known inorganic fillers, such as silica-based inorganic fillers like silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber, as well as light calcium carbonate, heavy calcium carbonate, various surface-treated calcium carbonates, magnesium carbonate, magnesium hydroxide, aluminum hydroxide, barium sulfate, magnesium sulfate, calcium sulfate, titanium dioxide, magnesium oxide, alumina, and carbon.

[0080] A particularly preferred inorganic filler is silica, such as 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 and the silica.

[0081] [Silane coupling agent] The shoe rubber composition of this embodiment may contain a silane coupling agent. The silane coupling agent has groups that have affinity or binding properties to the rubber component and the silica-based inorganic filler, respectively, and has the function of tightening the interaction between them. Generally, compounds having a sulfur bond portion and an alkoxysilyl group or silanol group portion in a single molecule are used.

[0082] Silane coupling agents are not limited to the following, but include, for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, ethoxy(3-mercaptopropyl)bis(3,6,9,12,15-pentaoxacosan-1-yloxy)silane [manufactured by Evonik Degussa: Si363], and NXT-Z30, NXT-Z45, NXT-Z60, and NXT-silane from Momentive. Which silane coupling agents contain a mercapto group? 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)tetrasulf 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl Examples include tetrasulfide, 3-triethoxysilylpropylbenzoyltetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, dimethoxymethylsilylpropylbenzothiazolyltetrasulfide, and the like.

[0083] Among these, bis-[3-(triethoxysilyl)-propyl]-disulfide, ethoxy(3-mercaptopropyl)bis(3,6,9,12,15-pentaoxacosan-1-yloxy)silane [manufactured by Evonik Degussa: Si363], silane coupling agents containing mercapto groups such as 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 can be used individually or in combination of two or more.

[0084] From the viewpoint of further enhancing the effect of tightening the interaction between the rubber component and the silica-based inorganic filler, the amount of silane coupling agent added 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 total amount of rubber component. Furthermore, from the viewpoint of improving processability, the amount of silane coupling agent added 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 total amount of rubber component.

[0085] [Rubber softener] The shoe rubber composition of this embodiment may contain a rubber softener to improve processability. Suitable rubber softeners include, for example, mineral oil-based rubber softeners and liquid or low molecular weight synthetic softeners. The above mineral oil-based rubber softener is also called process oil or extender oil and is used to soften, increase the volume of, and improve the processability of rubber. The above mineral oil-based rubber softener is a mixture of aromatic rings, naphthenic rings, and paraffinic chains. Those in which the number of carbon atoms in the paraffinic chain accounts for 50% or more of the total carbon atoms are called paraffinic, those in which the number of carbon atoms in the naphthenic ring is 30-45% are called naphthenic, and those in which the number of aromatic carbon atoms exceeds 30% are called aromatic. As a rubber softener used with a modified conjugated diene polymer, one having an appropriate aromatic content is preferred because it tends to have good affinity with the copolymer.

[0086] [Method for producing shoe rubber composition] The method for mixing the constituent materials of the rubber composition of this embodiment, including the rubber component containing the above-mentioned modified conjugated diene polymer and rubbery polymer, inorganic fillers, silane coupling agents, rubber softeners, and other additives, is not limited to the following, but examples include a melt-kneading method using a general mixer such as an open roll, Banbury mixer, kneader, single-screw extruder, twin-screw extruder, or multi-screw extruder, and a method in which the solvent is removed by heating after each component has been dissolved and mixed.

[0087] Of these, melt-kneading methods using rolls, Banbury mixers, kneaders, and extruders are preferred from the viewpoint of productivity and good kneading performance. Furthermore, both methods of kneading the constituent materials of the rubber composition of this embodiment all at once and methods of mixing in multiple stages are applicable.

[0088] The rubber composition of this embodiment may be a vulcanized composition that has been vulcanized with a vulcanizing agent. The vulcanizing agent is not limited to the following, but examples include radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds.

[0089] Sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, and high molecular weight polysulfur compounds.

[0090] From the viewpoint of improving tensile strength through a reinforcing effect, the content of the vulcanizing agent is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the total amount of the modified conjugated diene polymer and the rubbery polymer. Furthermore, from the viewpoint of having flexibility and improving 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.

[0091] Conventional vulcanization methods can be applied, and the vulcanization temperature is not particularly limited. However, from the viewpoint of shortening the vulcanization time and improving production efficiency, a temperature of 120°C or higher is preferred, 140°C or higher is more preferred, and 150°C or higher is even more preferred. Furthermore, from the viewpoint of suppressing thermal degradation during vulcanization, a temperature of 200°C or lower is preferred, 180°C or lower is more preferred, and 160°C or lower is even more preferred.

[0092] During vulcanization, a vulcanization accelerator may be used as needed. Conventional known materials can be used as vulcanization accelerators, and are not limited to the following, but examples include sulfenamide compounds, guanidine compounds, thiuram compounds, aldehyde-amine compounds, aldehyde-ammonia compounds, thiazole compounds, thiourea compounds, and dithiocarbamate compounds.

[0093] Furthermore, while not limited to the following, examples of vulcanization aids include zinc oxide and stearic acid.

[0094] 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 rubber components.

[0095] The modified conjugated diene polymer composition of this embodiment may also contain various additives other than those mentioned above, such as softeners, fillers, heat stabilizers, antistatic agents, weather stabilizers, anti-aging agents, colorants, and lubricants, as long as the objective of this embodiment is not impaired. For the heat-resistant stabilizer, antistatic agent, weather-resistant stabilizer, anti-aging agent, colorant, and lubricant mentioned above, known materials can be used.

[0096] [Outsole] The shoe rubber composition of this embodiment is suitably used as a shoe sole rubber composition. That is, the outsole of this embodiment is made using the rubber composition of this embodiment. The rubber composition for the outsole of this embodiment is not limited to the following, but can be used as a sole material for all types of footwear, such as sports shoes, running shoes, trekking shoes, and casual shoes. [Examples]

[0097] The embodiment will be described in more detail below with reference to specific examples and comparative examples, but this embodiment is not limited in any way to the following examples and comparative examples. Hereinafter, "parts" means "parts by mass" unless otherwise specified. The various physical properties in the examples and comparative examples were measured by the methods described below.

[0098] (Weight-average molecular weight (Mw), number-average molecular weight (Mn), area ratio of molecules with a molecular weight of 100,000 or less, and area ratio of molecules with a molecular weight of 1,000,000 or more) Using a gel permeation chromatography (GPC) analyzer with three columns packed with polystyrene gel, chromatograms were measured, and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were determined based on a calibration curve using standard polystyrene. Furthermore, the area ratios for molecular weights below 100,000 and above 1,000,000 were calculated from the obtained molecular weight distribution curves. The specific measurement conditions are shown below. 20 μL of the measurement solution listed below was injected into the GPC measuring device and the measurement was performed. (Measurement conditions) Device: Tosoh Corporation product name "HLC-8320GPC" Eluent: 5 mmol / L tetrahydrofuran (THF) containing triethylamine Guard column: Product name "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation. Separation column: A combination of TSKgel SuperH5000, TSKgel SuperH6000, and TSKgel SuperH7000, manufactured by Tosoh Corporation, linked together in that order. Oven temperature: 40℃ Flow rate: 0.6mL / min Detector: RI detector (product name "HLC8020" manufactured by Tosoh Corporation) Measurement solution: A measurement solution prepared by dissolving 10 mg of the sample in 20 mL of THF.

[0099] (Moony viscosity) A Mooney viscometer (product name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) was used to measure Mooney viscosity in accordance with JIS K6300 (ISO 289-1) using an L-shaped rotor. Specifically, the sample was first preheated to 100°C for 1 minute, then the rotor was rotated at 2 rpm, and the torque after 4 minutes was measured to determine the Mooney viscosity at 100°C.

[0100] (Mooney easing rate) Using a Mooney viscometer (product name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.), Mooney viscosity was measured using an L-shaped rotor in accordance with JIS K6300 (ISO 289-1). Immediately after measuring, the rotor rotation was stopped, and the torque was recorded in Mooney units at 0.1-second intervals from 1.6 seconds to 5 seconds after stopping. The slope of the line when torque and time (seconds) were plotted on a log-log scale was determined, and its absolute value was defined as the Mooney relaxation rate (MSR).

[0101] (Degeneration rate) The modification rate of the modified conjugated diene polymer was measured using the column adsorption GPC method, taking advantage of the property that the modified conjugated diene polymer adsorbs onto a column, as follows. The amount of adsorption onto the silica-based column was determined by the difference between the chromatogram obtained by measuring the sample and a sample solution containing low molecular weight internal standard polystyrene using a polystyrene-based gel column and the chromatogram obtained by measuring it using a silica-based gel column, and the denaturation rate was calculated. The GPC measurement conditions using a polystyrene column are shown below. 20 μL of the measurement solution listed below was injected into the GPC measuring device and the measurement was performed. (GPC measurement conditions using polystyrene columns) Device: Tosoh Corporation product name "HLC-8320GPC" Eluent: THF containing 5 mmol / L triethylamine Guard column: Product name "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation. Column: A combination of the product names "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000" manufactured by Tosoh Corporation, in that order. Oven temperature: 40℃ Flow rate: 0.6mL / min Detector: RI detector (Tosoh Corporation HLC8020) Measurement solution: 10 mg of the sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF to prepare the sample solution. The GPC measurement conditions using a silica-based column are shown below. 50 μL of the measurement solution listed below was injected into the GPC measuring device and the measurement was performed. (GPC measurement conditions using silica-based columns) Device: Tosoh Corporation product name "HLC-8320GPC" Eluent:THF Guard column: DIOL 4.6×12.5mm 5micron, manufactured by GL Sciences Co., Ltd. Separation column: Agilent Technologies' Zorbax PSM-1000S, PSM-300S, and PSM-60S columns linked together in that order. Oven temperature: 40℃ Flow rate: 0.5mL / min Detector: RI detector (Tosoh Corporation HLC8020) Method for calculating the denaturation rate: The total peak area of ​​the chromatogram using a polystyrene column was set to 100, with the peak area of ​​the sample as P1 and the peak area of ​​standard polystyrene as P2. The total peak area of ​​the chromatogram using a silica column was also set to 100, with the peak area of ​​the sample as P3 and the peak area of ​​standard polystyrene as P4. The denaturation rate (mass%) was then calculated using the following formula. Degeneration rate (mass%) = [1 - (P2 × P3) / (P1 × P4)] × 100 (However, P1+P2=P3+P4=100)

[0102] (Amount of bonded aromatic vinyl) 100 mg of the sample was dissolved in 100 mL of chloroform to prepare the measurement sample. The amount of bound aromatic vinyl (mass%) relative to 100% by mass of the modified conjugated diene polymer was measured by the amount of UV absorption at the aromatic group of the aromatic vinyl (around 254 nm in the case of styrene). A Shimadzu UV-2450 spectrophotometer was used as the measuring instrument.

[0103] (Amount of 1,2-vinyl bond) 50 mg of the sample was dissolved in 10 mL of carbon disulfide to prepare the measurement sample. The infrared spectrum was measured using a solution cell at 600-1000 cm⁻¹. -1 Measurements were taken within a specified range, and the microstructure of the butadiene moiety, i.e., the amount of 1,2-vinyl bonds (mol%), was determined by the absorbance at a predetermined wavenumber according to the calculation formula of Hampton's method (as described in RRHampton, Analytical Chemistry 21,923 (1949)). A Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation was used as the measuring instrument.

[0104] (Amount of block aromatic vinyl) The amount of block aromatic vinyl was measured according to the osmium tetroxide decomposition method described in IMKolthoff, et al., J. Polym. Sci. 1, 429 (1946). More specifically, 0.050 g of a modified conjugated diene polymer was dissolved in 10 ml of chloroform, and 16 ml of a 69% by mass aqueous solution of tert-butyl hydroperoxide and 4.0 ml of a 0.050% by mass chloroform solution of osmium tetroxide were added. The reaction was carried out under reflux in a 90°C bath for 12 minutes. After the reaction was complete, the reaction solution was cooled, and 200 ml of methanol was added to the reaction solution while stirring to precipitate the aromatic vinyl block component, which was then filtered off through a 5 μm glass filter. The amount of block aromatic vinyl was determined by dividing the mass of the obtained product by the total mass of the modified conjugated diene polymer.

[0105] (Glass transition temperature (Tg)) In accordance with ISO 22768:2006, a differential scanning calorimeter "DSC3200S" manufactured by MacScience was used to record the DSC curve while increasing the temperature from -100°C to 20°C / min under a helium flow of 50 mL / min. The peak top (inflection point) of the DSC differential curve was defined as the glass transition temperature.

[0106] [Production of Modified Conjugated Dienes] (Example A1) Sample No. A One autoclave with an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom and an outlet at the top, and equipped with a stirrer and a jacket for temperature control, was used. In addition, a static mixer was connected just before the raw material inlet of the reactor. Pre-mixed 1,3-butadiene, from which water and other impurities had been removed, was added at 19.5 g / min, styrene at 6.7 g / min, and n-hexane at 137.6 g / min. Just before this mixture entered the first reactor, n-butyllithium for impurity deactivation treatment was supplied at 0.020 phm and mixed with the static mixer, and then continuously supplied to the bottom of the first reactor. Furthermore, 2,2-bis(2-oxolanil)propane was continuously supplied to the bottom of the reactor at a concentration of 0.065 phm as a polar substance, and NBL (n-butyllithium) was supplied at a concentration of 0.097 phm as a polymerization initiator, maintaining the reactor temperature at 98°C. The rubber solution produced in the reactor was supplied to a static mixer from the top of the reactor. Before reaching the static mixer, AS-2 (1,3-bis-(N,N'-diglycidylaminomethyl)cyclohexane) was continuously supplied in a ratio of 1.0 equivalent to the lithium NBL supplied as a polymerization initiator to carry out the reaction and obtain sample No. A.

[0107] (Example A2) Sample No. B Sample No. B was obtained in the same manner as in Example A1, except that the denaturant was changed to AS-1(2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silaccyclopentane).

[0108] (Example A3) Sample No. C Sample No. C was obtained in the same manner as in Example A1, except that the amount of polymerization initiator added was changed to 0.107 phm and the amount of polar substance added was changed to 0.021 phm.

[0109] (Example A4) Sample No. D Sample No. D was obtained in the same manner as in Example A3, except that the amount of denaturant added was changed to 0.6 equivalents.

[0110] (Example A5) Sample No. E Sample No. E was obtained in the same manner as in Example A1, except that the amount of denaturant added was changed to 0.4 equivalents.

[0111] ( Reference example A6) Sample No. F Sample No. F was obtained in the same manner as in Example A3, except that the amount of 1,3-butadiene added was changed to 22.1 g / min, the amount of styrene added to 4.1 g / min, the amount of polar substance added to 0.018 phm, and the polymerization temperature to 95°C.

[0112] ( Reference example A7) Sample No. G Except for changing the amount of 1,3-butadiene added to 23.5 g / min and the amount of styrene added to 2.7 g / min, Reference example Sample No. G was obtained using the same method as for A6.

[0113] (Example A8) Sample No. H Sample No. H was obtained in the same manner as in Example A1, except that the amount of 1,3-butadiene added was changed to 16.8 g / min, the amount of styrene added to 9.4 g / min, the amount of polar substance added to 0.084 phm, and the amount of polymerization initiator added to 0.116 phm.

[0114] ( Reference example A9) Sample No. I Sample No. I was obtained in the same manner as in Example A8, except that the amount of polymerization initiator added was changed to 0.082 phm, the amount of polar substance added to 0.025 phm, and the amount of modifier added to 0.6 equivalents.

[0115] (Example A10) Sample No. J Sample No. J was obtained in the same manner as in Example A1, except that the polymerization temperature was changed to 95°C.

[0116] (Example A11) Sample No. K Sample No. K was obtained in the same manner as in Example A10, except that the amount of denaturing agent added was changed to 0.6 equivalents.

[0117] (Comparative Example A1) Sample No. L Sample No. L was obtained in the same manner as in Example A1, except that the amount of polar substance added was changed to 0.18 pF and the polymerization temperature to 87°C.

[0118] (Comparative Example A2) Sample No.M Sample No. M was obtained in the same manner as in Example A3, except that the amount of polymerization initiator added was changed to 0.075 pHm, the amount of polar substance added was changed to 0.018 pHm, and the polymerization temperature was changed to 95°C.

[0119] (Comparative Example A3) Sample No. N Sample No. N was obtained in the same manner as in Example A3, except that the amount of polymerization initiator added was changed to 0.082 phm, the amount of polar substance added to 0.018 phm, and the amount of modifier added to 0.3 equivalents.

[0120] (Comparative Example A4) Sample No. O Sample No. O was obtained in the same manner as in Example A1, except that the amount of 1,3-butadiene added was changed to 15.2 g / min, the amount of styrene added to 11.0 g / min, the amount of polymerization catalyst added to 0.103 g / min, and the amount of polar substance added to 0.078 phm.

[0121] [Table 1]

[0122] That's all. Examples A1-A5, A8, A10 and A11, Reference Examples A6, A7 and A9, and In comparative examples A1 to A4, modified conjugated diene polymers (samples No. A to O) were obtained as shown in Table 1.

[0123] (Example B1~ B5, B8, B10 and B11 See also the reference examples B6, B7, and B9, andComparative examples B1~B4) As shown in Table 2, rubber compositions containing each raw rubber were obtained by blending 100 parts of a modified conjugated diene polymer as the rubber component with inorganic fillers, etc. More specifically, the materials in Table 2 were kneaded by the following method to obtain the rubber compositions. Using a sealed kneader (capacity 0.6 L) equipped with a temperature control device, the raw rubber (modified conjugated diene polymer), filler (silica), silane coupling agent, zinc oxide, stearic acid, and antioxidant were kneaded in the first stage under conditions of a filling rate of 65% and a rotor rotation speed of 30 rpm. At this time, the temperature of the sealed mixer was controlled, and each rubber composition (compound) was obtained at a discharge temperature of 125-135°C. Subsequently, as the second stage of mixing, the rubber composition discharged in the first stage was passed through the rolls seven times in an open roll machine set to 73°C. After cooling, the third stage of mixing involved adding sulfur and vulcanization accelerators 1 and 2 in an open roll oven set to 73°C. The mixture was then molded and vulcanized in a vulcanization press at 160°C for 25 minutes. The properties of the vulcanized rubber composition were then evaluated. Specifically, the evaluation was performed using the method described below. The results are shown in Table 3.

[0124] [Table 2]

[0125] [Table 3]

[0126] ( Examples C1-C5, C8, C10 and C11, Reference Examples C6, C7 and C9, and Comparative examples C1~C4) Table 4 shows that rubber compositions containing each raw rubber were obtained by blending 60 parts of polybutadiene rubber, 10 parts of polyisoprene rubber, and 30 parts of modified conjugated diene polymer as raw rubber components, along with inorganic fillers, etc. More specifically, the materials in Table 4 were kneaded by the following method to obtain the rubber compositions. Using a sealed kneader (capacity 0.6 L) equipped with a temperature control device, the raw rubbers (polybutadiene rubber, polyisoprene rubber, modified conjugated diene polymer), fillers (silica), silane coupling agent, zinc oxide, stearic acid, and antioxidant were kneaded in the first stage under conditions of a filling rate of 65% and a rotor rotation speed of 30 rpm. At this time, the temperature of the sealed mixer was controlled, and each rubber composition (blended product) was obtained at a discharge temperature of 125-135°C. Subsequently, as the second stage of mixing, the rubber composition discharged in the first stage was passed through the rolls seven times in an open roll machine set to 73°C. After cooling, the third stage of mixing involved adding sulfur and vulcanization accelerators 1 and 2 in an open roll kneading machine set to 73°C. The mixture was then molded and vulcanized in a vulcanization press at 160°C for 25 minutes. The properties of the vulcanized rubber composition were then evaluated. Specifically, the evaluation was performed using the method described below. The results are shown in Table 5.

[0127] [Table 4]

[0128] [Table 5]

[0129] The product names used for each component in Tables 2 and 4 are as follows: • Polybutadiene rubber (UBEPOL U150 manufactured by Ube Industries, Ltd.) • Polyisoprene rubber (manufactured by Zeon Corporation, product name "Nipol IR2200") • Silica (product name "Ultrasil VN3" manufactured by Evonik Degussa) • Silane coupling agent (Evonik Degussa brand name "Si69", bis(triethoxysilylpropyl)tetrasulfide) • Anti-aging agent (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) • Vulcanization accelerator 1 (2-mercaptobenzothiazole: MBT) • Vulcanization accelerator 2 (N-(tert-butyl)-2-benzothiazole sulfenamide: TBBS)

[0130] The materials listed in Table 2 were kneaded using the following method to obtain rubber compositions. A sealed kneader (capacity 0.6 L) equipped with a temperature control device was used. In the first stage of kneading, the raw rubber (modified conjugated diene polymer), filler (silica), silane coupling agent, zinc oxide, stearic acid, and antioxidant were kneaded under the conditions of a filling rate of 65% and a rotor rotation speed of 30 rpm. At this time, the temperature of the sealed mixer was controlled, and each rubber composition (compound) was obtained at a discharge temperature of 125-135°C. Subsequently, as the second stage of mixing, the rubber composition discharged in the first stage was passed through the rolls seven times in an open roll machine set to 73°C. After cooling, the third stage of mixing involved adding sulfur and vulcanization accelerators 1 and 2 in an open roll kneading machine set to 73°C. The mixture was then molded and vulcanized in a vulcanization press at 160°C for 25 minutes. The properties of the vulcanized rubber composition were then evaluated. Specifically, the evaluation was performed using the method described below. The results are shown in Table 3.

[0131] The materials listed in Table 4 were kneaded using the following method to obtain rubber compositions. A sealed kneader (capacity 0.6 L) equipped with a temperature control device was used. In the first stage of kneading, the raw rubber (polybutadiene rubber, polyisoprene rubber, modified conjugated diene polymer), filler (silica), silane coupling agent, zinc oxide, stearic acid, and antioxidant were kneaded under the conditions of a filling rate of 65% and a rotor rotation speed of 30 rpm. At this time, the temperature of the sealed mixer was controlled, and each rubber composition (compound) was obtained at a discharge temperature of 125-135°C. Subsequently, as the second stage of mixing, the rubber composition discharged in the first stage was passed through the rolls seven times in an open roll machine set to 73°C. After cooling, the third stage of mixing involved adding sulfur and vulcanization accelerators 1 and 2 in an open roll kneading machine set to 73°C. The mixture was then molded and vulcanized in a vulcanization press at 160°C for 25 minutes. The properties of the vulcanized rubber composition were then evaluated. Specifically, the evaluation was performed using the method described below. The results are shown in Table 5.

[0132] [Evaluation of characteristics] (Evaluation 1) Tear strength Trouser-shaped test specimens were prepared, and a tear test was conducted in accordance with JIS K-6252, measuring the maximum tear force (unit: NK / m) until the test specimen broke. In Table 3, the evaluation of Comparative Example B4 is indexed with a value of 100. Examples B1-B5, B8, B10 and B11, Reference Examples B6, B7 and B9, and Comparative Examples B1 to B3 were indexed. In Table 5, the evaluation of Comparative Example C4 is indexed with a value of 100. Examples C1-C5, C8, C10 and C11, Reference Examples C6, C7 and C9, and Comparative examples C1 to C3 were indexed. A higher index indicates superior tear strength.

[0133] (Evaluation 2) Tensile strength The breaking strength (in MPa) and breaking elongation (in %) were measured in accordance with the tensile testing method of JIS K6251. In Table 3, the evaluation of Comparative Example B4 is indexed with a value of 100. Examples B1-B5, B8, B10 and B11, Reference Examples B6, B7 and B9, and Comparative examples B1 to B3 were indexed. In Table 5, the evaluation of Comparative Example C4 is indexed with a value of 100. Examples C1-C5, C8, C10 and C11, Reference Examples C6, C7 and C9, and Comparative examples C1 to C3 were indexed. A higher index indicates superior tear strength.

[0134] (Rating 3) Grip performance: Dynamic friction coefficient The coefficient of dynamic friction was measured using a dynamic friction testing machine (Heidon Tribogear Type 40) manufactured by Shinto Kagaku Co., Ltd. The sliding surface was made of ceramic tile, lubricated with water, and a vulcanized sheet measuring 3 mm thick, 30 mm wide, and 30 mm deep was placed on the sliding surface. The average value of the dynamic friction coefficient was used to evaluate the grip performance under a load of 500 gf, a sliding speed of 25 mm / min, and a sliding distance of 80 mm. In Table 3, the evaluation of Comparative Example B4 is indexed with a value of 100. Examples B1-B5, B8, B10 and B11, Reference Examples B6, B7 and B9, and Comparative examples B1 to B3 were indexed. In Table 5, the evaluation of Comparative Example C4 is indexed with a value of 100. Examples C1-C5, C8, C10 and C11, Reference Examples C6, C7 and C9, and Comparative examples C1 to C3 were indexed. A higher index indicates superior tear strength.

[0135] (Evaluation 4) Abrasion resistance The specific wear volume (unit: mm²) is measured using a DIN wear tester (manufactured by Ueshima Seisakusho) in accordance with JIS K6264. 3 ) was measured. In Table 3, the evaluation of Comparative Example B4 is indexed with a value of 100. Examples B1-B5, B8, B10 and B11, Reference Examples B6, B7 and B9, and Comparative examples B1 to B3 were indexed. In Table 5, the evaluation of Comparative Example C4 is indexed with a value of 100. Examples C1-C5, C8, C10 and C11, Reference Examples C6, C7 and C9, and Comparative examples C1 to C3 were indexed. A higher index indicates superior wear resistance.

[0136] (Rating 5) Machinability: As the third stage of mixing, the surface roughness of the sheet and the roughness of the sheet edges were visually observed after mixing using an open roll. In Table 3, Comparative Example B4 is rated as E. Examples B1-B5, B8, B10 and B11, Reference Examples B6, B7 and B9, and Comparative examples B1 to B4 were evaluated. In Table 5, the evaluation of Comparative Example C4 is set to E. Examples C1-C5, C8, C10 and C11, Reference Examples C6, C7 and C9, and Comparative examples C1 to C4 were evaluated. The criteria for each evaluation in the table are as follows: A: The surface and edges of the sheet are smooth. B: The surface or edge of the sheet is slightly wavy, but otherwise smooth. C: The surface and edges of the sheet are slightly wavy but otherwise smooth. D: The surface or edge of the sheet is rough. E: The surface and edges of the sheet are rough.

[0137] As shown in Table 3, Examples B1-B5, B8, B10 and B11 are Compared to comparative examples B1 to B3, it was confirmed that the shoe rubber composition exhibited an excellent balance of tensile strength and abrasion resistance, and that even better tensile strength and tear strength could be obtained. Similarly, as shown in Table 5, Examples C1-C5, C8, C10 and C11 are, Compared to comparative examples C1 to C3, the shoe rubber composition exhibited a superior balance of tensile strength and abrasion resistance, and it was confirmed that even better tensile strength and tear strength could be obtained. [Industrial applicability]

[0138] The modified conjugated diene polymer and shoe rubber composition according to 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.

Claims

1. The following conditions I) to V) must be met, When the total area of ​​the molecular weight distribution curve obtained by gel permeation chromatography is taken as 100%, the area ratio of molecules with a molecular weight of 100,000 or less is 8% or more, and the area ratio of molecules with a molecular weight of 1,000,000 or more is 5% or more. The ratio of the amount of blocked aromatic vinyl to the amount of bonded aromatic vinyl is 0.23 or less. Modified conjugated diene polymers modified by nitrogen atom-containing functional groups. I) Glass transition temperature is between -80°C and -30°C II) 1,2-vinyl bond content: 13 mol% to 30 mol% III) Mooney viscosity measured under JIS K6300 (ISO 289-1) conditions is 30-70 IV) Degeneration rate of 30% by mass or more V) The amount of bonded aromatic vinyl is 25.1% by mass or more and 40% by mass or less.

2. The modified conjugated diene polymer contains a polymer having conjugated diene monomer units and aromatic vinyl monomer units, and having a nitrogen atom-containing functional group. The modified conjugated diene polymer according to claim 1.

3. 100 parts by mass of a rubber component containing the modified conjugated diene polymer (A) described in either claim 1 or 2, The inorganic filler component (B) is present in an amount of 20 parts by mass or more per 100 parts by mass of the rubber component. A rubber composition for shoes containing the following:

4. The rubber component includes a rubbery polymer (C) other than the modified conjugated diene polymer (A), The content of the modified conjugated diene polymer (A) is 90% by mass or less relative to the total amount of the rubber components. The shoe rubber composition according to claim 3, wherein the content of the rubbery polymer (C) is 10% by mass or more relative to the total amount of the rubber components.

5. An outsole comprising the shoe rubber composition according to claim 3 or 4.

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