Rubber composition for outsole and outsole

Abstract

A rubber composition for an outsole, comprising a rubber, a filler and a tackifier.

Description

Rubber composition for outsole and outsole

[0001] The present invention relates to a rubber composition for an outsole and an outsole.

[0002] Conventionally, gripping ability has been cited as one of the important properties of shoe outsoles, and there has been a demand for further improvement. To date, various technologies relating to outsoles that attempt to improve gripping ability have been disclosed.

[0003] For example, Patent Document 1 discloses a technology relating to a rubber composition and an outsole in which the viscoelastic property tan δ is improved by specifying the composition ratio of the compound and using a predetermined silane coupling agent, thereby improving grip. Also, Patent Document 2 discloses a technology relating to a rubber composition and an outsole in which the grip property is improved by using a terminal-modified group-containing cyclic olefin ring-opening polymer and specifying the glass transition temperature.

[0004] Patent Application No. 2017-549835 Patent Application No. 2015-72532

[0005] However, the rubber compositions described in Patent Documents 1 and 2 have a problem in that there is room for improvement before they can be applied to outsoles of sports shoes and the like, which require better grip. According to the inventors' investigation into the properties of materials that contribute to the grip of shoes, the adhesive strength of the surface that comes into contact with the ground is important. On the other hand, if the amount of plasticizer such as oil added to the rubber composition is increased in order to improve adhesiveness, the abrasion resistance and strength of the rubber composition are significantly reduced, resulting in a problem of worsening the durability of the outsole.

[0006] In view of the above-mentioned problems of the conventional art, an object of the present invention is to provide a rubber composition for outsoles that has practically good strength and abrasion resistance and that can provide outsoles with excellent gripping properties.

[0007] The present inventors have conducted extensive research to solve the problems of the prior art described above and have found that by blending a tackifier into a rubber composition containing rubber and a filler, it is possible to provide a rubber composition for outsoles that can provide outsoles with improved adhesion without reducing abrasion resistance or strength, and have thus completed the present invention.

[0008] [1] A rubber composition for an outsole containing a rubber, a filler, and a tackifier. [2] The rubber composition for an outsole according to [1], wherein the rubber is a conjugated diene polymer. [3] The rubber composition for an outsole according to [2], wherein the conjugated diene polymer contains aromatic vinyl monomer units and conjugated diene monomer units. [4] The rubber composition for an outsole according to [3], wherein the conjugated diene polymer has an aromatic vinyl monomer unit content of 10% by mass or more and 60% by mass or less and a vinyl bond content of 20% by mass or more and 70% or less. [5] The rubber composition for an outsole according to [3] or [4], wherein the conjugated diene polymer has an aromatic vinyl monomer block content of 5% by mass or less. [6] The rubber composition for an outsole according to any one of [1] to [5], wherein the content of the filler is 15 to 60 parts by mass per 100 parts by mass of the rubber. [7] The rubber composition for an outsole according to any one of [1] to [6], wherein the content of silica is 80% by mass or more relative to the total mass of the filler. [8] The rubber composition for an outsole according to any one of [1] to [7], wherein the softening point of the tackifier is 40 to 170°C. [9] The rubber composition for an outsole according to any one of [1] to [8], wherein the glass transition temperature of the tackifier is -20°C or higher.

[10] The rubber composition for an outsole according to any one of [1] to [9], wherein the tackifier is a terpene compound and / or a petroleum hydrocarbon compound.

[11] The rubber composition for an outsole according to any one of [1] to

[10] , wherein the b* value of the tackifier is 50 or less.

[12] The rubber composition for an outsole according to

[10] or

[11] , wherein the petroleum hydrocarbon compound is an aromatic petroleum hydrocarbon resin or an alkylphenol.

[13] The rubber composition for an outsole according to any one of [1] to

[12] , wherein a mixture of the rubber and the tackifier has one Tg in differential scanning calorimetry (DSC).

[14] The rubber composition for an outsole according to any one of [2] to

[13] above, wherein the tackifier is a terpene compound, the content of aromatic vinyl monomer units in the conjugated diene polymer is from 10 to 50% by mass, and the vinyl bond content is from 24 to 60%.

[15] The rubber composition for an outsole according to any one of [2] to

[14] above, wherein the tackifier is a petroleum hydrocarbon compound, the content of aromatic vinyl monomer units in the conjugated diene polymer is from 20 to 60% by mass, and the vinyl bond content is from 20 to 55%.

[16] The rubber composition for an outsole according to any one of [1] to

[15] above, wherein the difference in glass transition temperature between the rubber and the tackifier is from 10 to 180°C.

[17] The rubber composition for an outsole according to any one of [1] to

[16] , wherein the content of the tackifier in the rubber composition for an outsole is 1 part by mass or more and 30 parts by mass or less per 100 parts by mass of the rubber.

[18] The rubber composition for an outsole according to any one of [1] to

[17] , wherein the haze is 50% or less.

[19] The rubber composition for an outsole according to any one of [1] to

[18] , wherein the rubber is a nitrile rubber in an amount of 10% by mass or more and less than 60% by mass in the rubber.

[20] The rubber composition for an outsole according to any one of [1] to

[19] , wherein the rubber is an epichlorohydrin rubber in an amount of 10% by mass or more and 90% by mass or less in the rubber.

[21] The rubber composition for an outsole according to any one of [1] to

[20] , wherein the rubber is a urethane rubber in an amount of 10% by mass or more and 90% by mass or less in the rubber.

[22] The rubber composition for an outsole according to any one of [1] to

[21] above, wherein the rubber contains chlorosulfonated ethylene rubber in an amount of 10% by mass or more and 90% by mass or less in the rubber.

[23] The rubber composition for an outsole according to any one of [1] to

[22] above, wherein the rubber contains acrylic rubber in an amount of 10% by mass or more and 90% by mass or less in the rubber.

[24] The rubber composition for an outsole according to any one of [1] to

[23] above, wherein the rubber contains silicone rubber in an amount of 10% by mass or more and 90% by mass or less in the rubber.

[25] The rubber composition for an outsole according to any one of [1] to

[24] above, wherein the rubber contains 10% by mass or more and 90% by mass or less of a fluororubber.

[26] The rubber composition for an outsole according to any one of [2] to

[25] above, wherein the conjugated diene-based polymer contains polybutadiene and a styrene-butadiene copolymer.

[27] An outsole which is a molded article of the rubber composition for an outsole according to any one of [1] to

[26] above.

[0009] According to the present invention, it is possible to provide a rubber composition for an outsole and an outsole which are practically good in strength and abrasion resistance and have excellent gripping properties.

[0010] Hereinafter, an embodiment for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that the present embodiment is an example for explaining the present invention, and the present invention is not limited to the following embodiment. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0011] [Rubber Composition for Outsole] The rubber composition for the outsole of the present embodiment contains rubber, a filler, and a tackifier.

[0012] In this specification, an outsole refers to a component used in the part of a shoe that comes into contact with the ground. When the outsole comes into contact with a floor surface, the outsole is designed to exert adhesive force, i.e., the force that allows the outsole to adhere to the floor surface and not separate from it, thereby making the outsole less slippery and providing excellent grip. By using the rubber composition for outsoles of this embodiment, adhesive force can be improved when used as an outsole without adding a plasticizer, resulting in practically satisfactory strength, abrasion resistance, and excellent grip. Even if a method for improving tire grip is applied to an outsole in order to obtain excellent grip in the outsole, sufficient grip may not be obtained in the outsole. This is thought to be because the mechanisms by which grip is exerted differ between tires and outsoles. For tires, energy loss due to tire deformation is thought to have a significant impact on the exertion of grip, and therefore, improving tan δ (0°C, 106 Hz) in viscoelasticity measurement is important. In contrast, improving adhesive force is important for an outsole.

[0013] (Rubber) The rubber composition for an outsole of this embodiment contains rubber from the viewpoint of balancing abrasion resistance and grip performance. Both natural and synthetic rubbers can be used as the rubber. Examples of synthetic rubbers include, but are not limited to, polybutadiene rubber (BR), polyisoprene rubber (IR), styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber (HSBR), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), chloroprene rubber, butyl rubber (IIR), and their brominated and chlorinated derivatives, ethylene-propylene-diene rubber (EPDM), epichlorohydrin rubber (ECO), urethane rubber (U), chlorosulfonated polyethylene (CSM), acrylic rubber (ACM), silicone rubber (Q), and fluororubber (FKM). Thermoplastic elastomers and thermosetting elastomers are also included. The rubber contained in the rubber composition for an outsole of this embodiment may be used alone, or two or more types of rubber may be used in combination. The rubber content in the rubber composition for an outsole of 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, from the viewpoints of elasticity and flexibility. On the other hand, from the viewpoints of cost and processability, the content is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. The rubber contained in the rubber composition for an outsole of this embodiment preferably contains at least one selected from the group consisting of polybutadiene rubber (BR), polyisoprene rubber (IR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber, butyl rubber (IIR), its brominated derivatives (BIIR) and chlorinated derivatives (CIIR), and ethylene-propylene-diene rubber (EPDM), from the viewpoints of the balance between abrasion resistance and gripping performance, cost, and supply stability. In particular, from the viewpoint of ease of crosslinking, it is preferable to contain a conjugated diene-based polymer containing a conjugated diene monomer unit, which will be described later.

[0014] (Conjugated Diene Polymer) The rubber composition for an outsole of this embodiment preferably contains a conjugated diene polymer as the rubber. The content of the conjugated diene polymer relative to the total rubber is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, from the viewpoint of the abrasion resistance of the outsole. On the other hand, from the viewpoint of the oil resistance of the outsole of this embodiment, it is preferably 100% by mass or less, more preferably 70% by mass or more, and even more preferably 60% by mass or less.

[0015] The conjugated diene polymer contains at least a structural unit derived from a conjugated diene compound (hereinafter also referred to as a "conjugated diene monomer unit"). Examples of the conjugated diene compound 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.

[0016] Furthermore, from the viewpoint of good winding properties around a roll used in, for example, kneading a crosslinking agent into an outsole composition, the conjugated diene polymer is preferably a copolymer of an aromatic vinyl compound and a conjugated diene compound. That is, the conjugated diene polymer preferably contains a structural unit derived from an aromatic vinyl compound (hereinafter also referred to as an "aromatic vinyl monomer unit"). Examples of aromatic vinyl compounds include, but are not limited to, styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred from the viewpoint of ease of industrial availability.

[0017] The conjugated diene polymer may be a polymer containing only conjugated diene monomer units, or may be a copolymer having conjugated diene monomer units and aromatic vinyl monomer units, but in order to improve processability and reproducibility of the physical properties of the rubber composition, it is preferable that the amount of other constituent components than the conjugated diene monomer units and aromatic vinyl monomer units is small. From the viewpoint of elasticity of the rubber composition for an outsole of this embodiment, the total content of the conjugated diene monomer units and aromatic vinyl monomer units in the conjugated diene polymer is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass.

[0018] When the conjugated diene polymer is a copolymer of a conjugated diene compound and an aromatic vinyl compound, it is preferable to control the microstructure, for example, the content of aromatic vinyl monomer units and the amount of 1,2-vinyl bonds. From the viewpoint of the strength and hardness of the rubber composition for outsoles of this embodiment, the content of aromatic vinyl monomer units in the conjugated diene polymer is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. When used for highly transparent outsoles, the content is preferably 40% by mass or more, more preferably 41% by mass or more, and even more preferably 42% by mass or more. From the viewpoint of the moldability and crushability of the conjugated diene polymer veil, the content is preferably 63% by mass or less, preferably 60% by mass or less, more preferably 58% by mass or less, even more preferably 55% by mass or less, and even more preferably 50% by mass or less. The content of aromatic vinyl monomer units can be controlled within the above-mentioned numerical range by adjusting the amount of aromatic vinyl compound added during polymerization.

[0019] The 1,2-vinyl bond content is the molar ratio of the 1,2-vinyl bond content based on the content of conjugated diene monomer units. From the viewpoints of the processability, crosslinkability, and flexibility of the rubber composition for an outsole of this embodiment, it is preferably 18% or more, more preferably 20% or more, even more preferably 22% or more, and even more preferably 24% or more. On the other hand, from the viewpoints of ease of polymerization of the conjugated diene polymer and resistance to gelation, it is preferably 70% or less, more preferably 65% ​​or less, even more preferably 63% or less, and even more preferably 60% or less. The 1,2-vinyl bond content can be controlled within the above-mentioned numerical range by adjusting the reaction initiation temperature and reaction termination temperature during polymerization of the conjugated diene polymer, as well as the type and amount of polar substance added. The content of aromatic vinyl monomer units and the 1,2-vinyl bond content of the conjugated diene polymer can be measured by the method described in the Examples below.

[0020] The conjugated diene polymer may also contain an aromatic vinyl monomer block. When the conjugated diene polymer contains an aromatic vinyl monomer block, the content of the aromatic vinyl monomer block relative to the conjugated diene polymer is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less, from the viewpoint of the abrasion resistance of the rubber composition for an outsole of this embodiment. On the other hand, from the viewpoint of the polymerization stability of the conjugated diene polymer, it is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and even more preferably 1.15% by mass or more. The content of the aromatic vinyl monomer block in the conjugated diene polymer can be measured by a known method in which the copolymer is decomposed by the Kolthoff method (the osmium tetroxide decomposition method described in I.M. Kolthoff, et al., J. Polym. Sci. 1, 429 (1946)) and the amount of styrene block insoluble in methanol is analyzed. The content of the aromatic vinyl monomer block can be controlled within the above-mentioned range by adjusting the amount of the aromatic vinyl compound added during polymerization and the timing of the addition.

[0021] The conjugated diene polymer contained in the rubber composition for an outsole of the present embodiment may be hydrogenated. The method for hydrogenating the conjugated diene polymer is not particularly limited, but the method described in WO 2021 / 206068 can be used, for example.

[0022] <Content of Copolymer of Conjugated Diene Compound and Aromatic Vinyl Compound> As the rubber constituting the rubber composition for an outsole of this embodiment, one type of conjugated diene polymer may be used alone, or two or more types may be used in combination. When at least one of the conjugated diene polymers is a copolymer of a conjugated diene compound and an aromatic vinyl compound, from the viewpoint of the gripping properties of the rubber composition for an outsole of this embodiment, the content of the copolymer of a conjugated diene compound and an aromatic vinyl compound is preferably 20% by mass or more, more preferably 40% by mass or more, and even more preferably 60% by mass or more, based on the total rubber. Furthermore, from the viewpoint of transparency of the rubber composition for an outsole of this embodiment, the content of the copolymer of a conjugated diene compound and an aromatic vinyl compound is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, based on the total rubber. Furthermore, from the viewpoint of transparency, the content of the copolymer of a conjugated diene compound and an aromatic vinyl compound is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less, based on the total rubber.

[0023] <Molecular Weight of Conjugated Diene Polymer> From the viewpoints of the shape stability of the rubber composition for an outsole of this embodiment and the tensile strength and abrasion resistance of a crosslinked product using the rubber composition for an outsole, the weight-average molecular weight of the conjugated diene polymer is preferably 150,000 or more, and more preferably 200,000 or more. On the other hand, from the viewpoint of the processability of the rubber composition for an outsole of this embodiment, the weight-average molecular weight is preferably 1,000,000 or less, more preferably 500,000 or less, and even more preferably 400,000 or less. From the viewpoint of the tensile strength of the rubber composition for an outsole of this embodiment, the molecular weight distribution (= weight-average molecular weight / number-average molecular weight) of the conjugated diene polymer is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.6 or less. On the other hand, from the viewpoint of the processability of the rubber composition for an outsole of this embodiment, the molecular weight distribution of the conjugated diene polymer is preferably 1.05 or more, more preferably 1.10 or more, and even more preferably 1.20 or more. The weight-average molecular weight and molecular weight distribution can be calculated from the polystyrene-equivalent molecular weight measured by GPC (gel permeation chromatography).

[0024] <Mooney Viscosity of Conjugated Diene Polymer> From the viewpoint of processability of the rubber composition for an outsole of this embodiment, the Mooney viscosity of the conjugated diene polymer is preferably 120 or less, more preferably 90 or less, and even more preferably 60 or less. On the other hand, from the viewpoint of abrasion resistance of the rubber composition for an outsole of this embodiment, the Mooney viscosity is preferably 30 or more, more preferably 40 or more, and even more preferably 45 or more.

[0025] <Coupling-Type Conjugated Diene Polymer> The conjugated diene polymer used as the rubber in the rubber composition for an outsole of this embodiment may be a coupling-type conjugated diene polymer obtained by subjecting the active terminal of the conjugated diene polymer obtained through a polymerization step to a coupling reaction using a bifunctional or higher functional compound (hereinafter also referred to as a "coupling agent"). The coupling agent is not limited to the following, but examples include coupling agents having one or more functional groups selected from functional groups such as an epoxy group, a carbonyl group, a carboxylic acid ester group, a carboxylic acid amide group, an acid anhydride group, a phosphate ester group, a phosphite ester group, an epithio group, a thiocarbonyl group, a thiocarboxylic acid ester group, a dithiocarboxylic acid ester group, a thiocarboxylic acid amide group, an imino group, an ethyleneimino group, a halogen group, an alkoxysilyl group, an isocyanate group, a thioisocyanate group, a conjugated diene group, and an arylvinyl group.

[0026] Examples of the coupling agent include, but are not limited to, halogenated silane compounds such as silicon tetrachloride, silicon tetrabromide, silicon tetraiodide, monomethyltrichlorosilicon, monoethyltrichlorosilicon, monobutyltrichlorosilicon, monohexyltrichlorosilicon, monomethyltribromosilicon, and bistrichlorosilylethane; and halogenated alkoxysilane compounds such as monochlorotrimethoxysilane, monobromotrimethoxysilane, dichlorodimethoxysilane, dibromodimethoxysilane, trichloromethoxysilane, and tribromomethoxysilane.

[0027] The coupling agent is not limited to the following, but examples thereof include alkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, and alkyltriphenoxysilane.

[0028] Furthermore, the coupling agent may be a nitrogen-containing compound, and examples thereof include, but are not limited to, isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, nitrogen-containing carbonyl compounds, nitrogen-containing vinyl compounds, and nitrogen-containing epoxy compounds (such nitrogen-containing compounds as coupling agents may be referred to hereinafter as coupling nitrogen-containing compounds).

[0029] The coupling nitrogen-containing compound is preferably a compound having a nitrogen atom-containing functional group, and the compound having a nitrogen atom-containing functional group is preferably an amine compound having no active hydrogen, and examples thereof include tertiary amine compounds, protected amine compounds in which the active hydrogen is substituted with a protecting group, imine compounds represented by the general formula -N=C, and alkoxysilane compounds bonded to the nitrogen atom-containing group.

[0030] Examples of the coupling nitrogen-containing compound include, but are not limited to, compounds having an imino group and an alkoxysilyl group, such as tristrimethoxysilylpropylamine, triethoxysilylpropylamine, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-(tributoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-ethylidene-3-(triethoxysilyl)-1-propanamine, and N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole, tetraglycidyl meta-xylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane.

[0031] The coupling nitrogen-containing compound is not limited to the following, but examples thereof include isocyanate compounds such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, diphenylethane diisocyanate, and 1,3,5-benzene triisocyanate.

[0032] Furthermore, the coupling nitrogen-containing compound is not limited to the following, but examples thereof include 3-(4-methylpiperazin-1-yl)propyltriethoxysilane, 1-[3-(diethoxyethylsilyl)propyl]-4-methylpiperazine, 1-[3-(trimethoxysilyl)propyl]-3-methylimidazolidine, 1-[3-(diethoxysilyl)propyl]-3-ethylimidazolidine, and 1-[3-(triethoxysilyl)propyl]-3-methylhexahydride. 1-[3-(dimethoxymethylsilyl)propyl]-3-methylhexahydropyrimidine, 3-[3-(tributoxysilyl)propyl]-1-methyl-1,2,3,4-tetrahydropyrimidine, 3-[3-(dimethoxymethylsilyl)propyl]-1-ethyl-1,2,3,4-tetrahydropyrimidine, 1-(2-ethoxyethyl)-3-[3-(trimethoxysilyl)propyl]imidazolidine, (2-{3-[3-(trimethylsilyl)propyl]imidazolidine )propyl]tetrahydropyrimidin-yl}ethyl)dimethylamine, 1-[3-(triethoxysilyl)propyl]-4-(trimethylsilyl)piperazine, 1-[3-(dimethoxymethylsilyl)propyl]-4-(trimethylsilyl)piperazine, 1-[3-(tributoxysilyl)propyl]-4-(trimethylsilyl)piperazine, 1-[3-(diethoxyethylsilyl)propyl]-3-(triethylsilyl)imidazolidine, 2-(trimethoxysilyl)propyl

[0033] Examples of such silyl groups include 1-[3-(triethoxysilanyl)propyl]-1,3-dimethylimidazolidine, 1-[3-(triethoxysilyl)propyl]-3-(trimethylsilyl)imidazolidine, 1-[3-(dimethoxymethylsilyl)propyl]-3-(trimethylsilyl)hexahydropyrimidine, 1-[3-(triethoxysilyl)propyl]-3-(trimethylsilyl)hexahydropyrimidine, and 1-[4-(triethoxysilyl)propyl]-4-(trimethylsilyl)piperazine.

[0033] Furthermore, the coupling nitrogen-containing compound is not limited to the following, but examples thereof include 2-[3-(trimethoxysilyl)propyl]-1,3-dimethylimidazolidine, 2-[3-(trimethoxysilyl)propyl]-1,3-(bistrimethylsilyl)imidazolidine, 2-(diethoxydiethylsilyl)-1,3-diethylimidazolidine, 2-(triethoxysilyl)-1,4-diethylpiperazine, 2-(dimethoxymethylsilyl)-1,4-dimethylpiperazine, 5-(triethoxysilyl)-1,3-dipropylhexahydropiperazine, and the like. imidazolidine, 5-(diethoxyethylsilyl)-1,3-diethylhexahydropyrimidine, {2-[3-(2-dimethylaminoethyl)-2-(ethyldimethoxysilyl)-imidazolidin-1-yl]-ethyl}-dimethylamine, 5-(trimethoxysilyl)-1,3-bis-(2-methoxyethyl)-hexahydropyrimidine, 5-(ethyldimethoxysilyl)-1,3-bis-(2-trimethylsilylethyl)-hexahydropyrimidine-1,3-dimethylimidazolidine, 2-(3-diethoxyethylsilyl-propyl)-1,3- Diethylimidazolidine, 2-(3-triethoxysilyl-propyl)-1,4-diethylpiperazine, 2-(3-dimethoxymethylsilyl-propyl)-1,4-dimethylpiperazine, 5-(3-triethoxysilyl-propyl)-1,3-dipropylhexahydropyrimidine, 5-(3-diethoxyethylsilyl-propyl)-1,3-diethylhexahydropyrimidine, {2-[3-(2-dimethylaminoethyl)-2-(3-ethyldimethoxysilyl-propyl)-imidazolidin-1-yl]-ethyl}-dimethylamine, 5-(3- trimethoxysilyl-propyl)-1,3-bis-(2-methoxyethyl)-hexahydropyrimidine, 5-(3-ethyldimethoxysilyl-propyl)-1,3-bis-(2-trimethylsilylethyl)-hexahydropyrimidine, 2-[3-(trimethoxysilyl)propyl]-1,3-bis(trimethylsilyl)imidazolidine, 2-(diethoxyethylsilyl)-1,3-bis(triethylsilyl)imidazolidine, 2-(triethoxysilyl)-1,4-bis(trimethylsilyl)piperazine, 2-(dimethoxymethylsilyl)-1,Examples include 4-bis(trimethylsilyl)piperazine and 5-(triethoxysilyl)-1,3-bis(tripropylsilyl)hexahydropyrimidine.

[0034] Furthermore, examples of the coupling nitrogen-containing compound include, but are not limited to, [3-(1-hexamethyleneimino)propyl]triethoxysilane, [3-(1-hexamethyleneimino)propyl]trimethoxysilane, [2-(1-hexamethyleneimino)ethyl]triethoxysilane, [2-(1-hexamethyleneimino)ethyl]trimethoxysilane, [3-(1-pyrrolidinyl)propyl]triethoxysilane, [3-(1-pyrrolidinyl)propyl]trimethoxysilane, [3-(1-heptamethyleneimino)propyl]triethoxysilane silane, [3-(1-dodecamethyleneimino)propyl]triethoxysilane, [3-(1-hexamethyleneimino)propyl]diethoxymethylsilane, [3-(1-hexamethyleneimino)propyl]diethoxyethylsilane, N-[3-(triethoxysilyl)propyl]-N,N'-diethyl-N'-trimethylsilyl-ethane-1,2-diamine, N-[2-(trimethoxysilanyl)ethyl]-N,N',N'-trimethylethane-1,2-diamine, and N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane.

[0035] Furthermore, the coupling nitrogen-containing compound is not limited to the following, but examples thereof include 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacycloheptane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacycloheptane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(5-trimethoxysilylpropyl ... Examples thereof include cyclopentane, 2,2-diethoxy-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-ethoxy-2-ethyl-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, and 2-ethoxy-2-ethyl-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane.

[0036] From the viewpoint of the reactivity and interaction between the functional group of the coupling nitrogen-containing compound and an inorganic filler such as silica, which will be described later, and from the viewpoint of the processability of the rubber composition for an outsole of the present embodiment, the coupling nitrogen-containing compound is preferably 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane or 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane.

[0037] <Modified Conjugated Diene Polymer> The conjugated diene polymer used as the rubber in the rubber composition for an outsole of this embodiment may be modified. Modification refers to modifying the conjugated diene polymer with a nitrogen-containing compound. Modification methods include, but are not limited to, a method using a polymerization initiator containing a nitrogen-containing compound, a method using a nitrogen-containing compound as a polymerization monomer, a method reacting the aforementioned coupling nitrogen-containing compound or non-coupling nitrogen-containing compound with the reaction terminal, and a method of modifying the double bond of the conjugated diene polymer after polymerization by reacting the nitrogen-containing compound with the double bond.

[0038] Examples of the polymerization initiator containing a nitrogen-containing compound include, but are not limited to, reaction products of nitrogen-containing compounds such as dimethylamine, diethylamine, dibutylamine, dipropylamine, diheptylamine, dihexylamine, dioctylamine, di(2-ethylhexyl)amine, didecylamine, ethylpropylamine, ethylbutylamine, ethylbenzylamine, methylphenethylamine, piperidine, hexamethyleneimine, azacyclooctane, 1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, 1,2,3,6-tetrahydropyridine, and 3,5-dimethylpiperidine with organolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, n-propyllithium, and i-propyllithium. Furthermore, examples of the non-coupling nitrogen-containing compound include, but are not limited to, 1,3-diethyl-2-imidazolinone, 1,3-dimethyl-2-imidazolinone, 1,3-dipropyl-2-imidazolinone, 1-methyl-3-ethyl-2-imidazolinone, 1-methyl-3-propyl-2-imidazolinone, 1-methyl-3-butyl-2-imidazolinone, and 1,3-dihydro-1,3-dimethyl-2H-imidazol-2-one.

[0039] <Modification Rate> In this specification, unless otherwise specified, the term "modification rate" refers to the mass ratio of a polymer having a nitrogen-atom-containing functional group to the total amount of polymers. For example, when a modifying agent that is a nitrogen-atom-containing compound is reacted with the terminal end of a polymer, the mass ratio of the polymer having a nitrogen-atom-containing functional group due to the modifying agent to the total amount of polymer is expressed as the modification rate. In addition, when a polymer is branched using a nitrogen-atom-containing branching agent, the resulting branched polymer will have a nitrogen-atom-containing functional group, and this branched polymer will also be counted when calculating the modification rate. Furthermore, when a polymer is formed into a nitrogen-atom-containing functional group by the above-mentioned coupling nitrogen-containing compound, this will also be counted when calculating the modification rate. In other words, in this specification, a polymer having a nitrogen-atom-containing functional group refers to a polymer having a nitrogen-atom-containing functional group due to a nitrogen-atom-containing modifier, a branched polymer produced by a branching agent having a nitrogen-atom-containing functional group, and a polymer having a nitrogen-atom-containing functional group produced by a coupling nitrogen-containing compound, and the total mass ratio of these is the "modification rate."

[0040] From the viewpoints of processability and improving filler dispersibility to improve performance and quality stability, the conjugated diene polymer used as the rubber for the outsole rubber composition of this embodiment preferably has a modification rate (hereinafter also simply referred to as "modification rate") measured by column adsorption GPC relative to the total amount of the conjugated diene polymer of 30% or more, more preferably 40% or more, and even more preferably 60% or more. On the other hand, from the viewpoints of processability and polymerization stability, the modification rate is preferably 90% or less, more preferably 80% or less, and the conjugated diene polymer may be unmodified. The modification rate can be measured, for example, by chromatography, which can separate functional group-containing modified components from unmodified components. Examples of this chromatography method include a method (column adsorption GPC method) in which a gel permeation chromatography column filled with a polar substance such as silica that adsorbs specific functional groups is used to quantify the unadsorbed components using an internal standard for comparison. More specifically, the modification rate can be determined by measuring the amount of adsorption to the silica column from the difference between a chromatogram obtained by measuring a sample solution containing the sample and a low-molecular-weight internal standard polystyrene on a polystyrene gel column and a chromatogram obtained by measuring the amount of adsorption to the silica column. More specifically, the modification rate can be measured by the method described in the Examples. In the conjugated diene polymer used in the rubber composition for an outsole of this embodiment, the modification rate can be controlled, for example, by adjusting the amount of the modifier added and the reaction method.

[0041] <Nitrogen Content> From the viewpoint of tear properties, the nitrogen content of the conjugated diene polymer as the rubber used in the rubber composition for an outsole of this embodiment is preferably 0 ppm or more and 5000 ppm or less, more preferably 0 ppm or more and 2000 ppm or less, even more preferably 0 ppm or more and 1500 ppm or less, and even more preferably 0 ppm or more and 1000 ppm or less. The nitrogen content can be controlled within the above-mentioned range by adjusting the type of monomer used in polymerizing the polymer and the amount of the above-mentioned modifier used.

[0042] When the rubber composition for an outsole of this embodiment contains nitrile rubber as the rubber, from the viewpoint of gripping property, the content of the nitrile rubber relative to the entire rubber is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. On the other hand, from the viewpoint of abrasion resistance of the rubber composition for an outsole of this embodiment, it is preferably less than 60% by mass, more preferably 55% by mass or less, and even more preferably 50% by mass or less. Furthermore, from the viewpoint of oil resistance, the ratio of acrylonitrile in the entire nitrile rubber is preferably 17% by mass or more, more preferably 23% by mass or more, and even more preferably 28% by mass or more. On the other hand, from the viewpoint of cold resistance, it is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less.

[0043] From the viewpoint of processability of the rubber composition for an outsole of the present embodiment, the Mooney viscosity of the rubber composition for an outsole of the present embodiment is preferably 120 or less, more preferably 90 or less, and even more preferably 60 or less. On the other hand, from the viewpoint of tensile strength of the rubber composition for an outsole of the present embodiment, the Mooney viscosity is preferably 25 or more, more preferably 35 or more, and even more preferably 45 or more.

[0044] When the rubber composition for an outsole of this embodiment contains butyl rubber or its bromide or chloride as the rubber, the content of these relative to the total rubber is preferably 20% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, from the viewpoint of weather resistance. On the other hand, from the viewpoint of oil resistance, the content is preferably 85% by mass or less, more preferably 75% by mass or less, and even more preferably 65% ​​by mass or less. The butyl rubber is preferably a copolymer of isobutylene and isoprene, and from the viewpoint of vulcanizability, the content of isoprene in the copolymer is preferably 1 mol% or more, more preferably 1.5 mol% or more, and even more preferably 2 mol% or more.

[0045] When the rubber composition for an outsole of this embodiment contains epichlorohydrin rubber (ECO) as the rubber, the content of the epichlorohydrin rubber (ECO) relative to the total rubber is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more from the viewpoint of oil resistance, while being preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less from the viewpoint of processability.

[0046] When the rubber composition for an outsole of this embodiment contains urethane rubber (U) as the rubber, the content of the urethane rubber (U) relative to the total rubber is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more from the viewpoint of tear strength, while being preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less from the viewpoint of heat resistance.

[0047] When the rubber composition for an outsole of this embodiment contains chlorosulfonated polyethylene (CSM) as the rubber, the content of CSM relative to the total rubber is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more from the viewpoint of abrasion resistance, while the content is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less from the viewpoint of cold resistance.

[0048] When the rubber composition for an outsole of this embodiment contains acrylic rubber (ACM) as the rubber, the content of ACM relative to the total rubber is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more from the viewpoint of heat resistance, while being preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less from the viewpoint of tensile strength.

[0049] When the rubber composition for an outsole of this embodiment contains silicone rubber (Q) as the rubber, the content of silicone rubber (Q) relative to the total rubber is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more from the viewpoint of weather resistance, while being preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less from the viewpoint of tear strength.

[0050] When the rubber composition for an outsole of this embodiment contains fluororubber (FKM) as the rubber, the content of the fluororubber relative to the total rubber is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more from the viewpoint of weather resistance, while being preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less from the viewpoint of cold resistance.

[0051] (Liquid Rubber) The rubber composition for an outsole of this embodiment may contain a liquid rubber to improve processability and flexibility. Liquid rubber is a low-molecular-weight rubbery polymer, and examples thereof include liquid diene rubbers such as liquid styrene butadiene rubber (liquid SBR), liquid butadiene rubber (liquid BR), and liquid isoprene rubber (liquid IR). The term "liquid rubber" refers to any component that can be distinguished from the rubber that constitutes the rubber composition for an outsole of this embodiment by its form (solid or liquid). That is, the liquid rubber is liquid under an environment of 23°C and 1 atmosphere, while the rubber that constitutes the rubber composition for an outsole of this embodiment is solid under the same environment. The cis content of the liquid BR is not particularly limited, and any of high-cis, medium-cis, and low-cis liquid BR may be contained. The liquid rubber is not particularly limited as long as it is liquid, but it is preferable that the peak top molecular weight measured by GPC be in the range of 1,000 to 50,000. The peak top molecular weight of the liquid rubber measured by GPC measurement is preferably 4,000 to 35,000, and more preferably 7,000 to 30,000. When the peak top molecular weight of the liquid rubber is within the above range, the processability and flexibility of the rubber composition for an outsole are further improved. Note that when a liquid rubber with a low molecular weight is used, processability is improved but strength tends to decrease. The amount of liquid rubber blended is not particularly limited and can be, for example, 0 to 15 parts by mass per 100 parts by mass of the total rubber used in the rubber composition for an outsole of this embodiment. The amount of liquid rubber blended is preferably 0.10 to 10.0 parts by mass, more preferably 0.20 to 7.0 parts by mass, and even more preferably 0.30 to 4.0 parts by mass. When the amount of liquid rubber blended is within the above range, the processability and flexibility of the rubber composition for an outsole of this embodiment tend to be further improved.

[0052] (Filler) The rubber composition for an outsole of this embodiment contains a filler. From the viewpoint of hardness and strength of the rubber composition for an outsole of this embodiment, the content of the filler is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and even more preferably 18 parts by mass or more, per 100 parts by mass of the above-mentioned rubber. On the other hand, from the viewpoint of processability, the content is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 55 parts by mass or less, and even more preferably 50 parts by mass or less.

[0053] The type of filler is not particularly limited as long as it is one commonly used as a material for rubber compositions for outsoles, and examples thereof include silica (dry silica, wet silica, colloidal silica), synthetic silicate white carbon, calcium carbonate, titanium oxide, talc, carbon black, etc. The fillers may be used alone or in combination of two or more. Silica is particularly preferred as the filler. When using silica as the filler, it is preferable to add a substance, such as a silane coupling agent, that improves the affinity between the inorganic filler and the rubber component in order to improve the dispersibility of the silica and enhance performance stability and reproducibility. Details of the silane coupling agent will be described later. The filler may be obtained by purchasing a commercially available product or may be produced by a conventionally known method.

[0054] From the viewpoint of rigidity of the rubber composition for an outsole of this embodiment, the content of silica relative to the total mass of the filler is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. Furthermore, when a highly transparent outsole is to be obtained or when the outsole is to be colored, it is preferable that carbon black is not included as a filler.

[0055] (Tackifier) ​​The rubber composition for outsoles of this embodiment contains a tackifier. A tackifier is generally an amorphous oligomer with a molecular weight of several hundred to several thousand, and when added to an elastomer, it imparts fluidity and tackiness, thereby improving adhesive performance. By containing a tackifier in the rubber composition for outsoles of this embodiment, an outsole using the rubber composition for outsoles of this embodiment exhibits softness that allows it to deform to conform to the unevenness of the floor surface, increasing the true contact area with the floor surface and generating friction, which tends to improve grip. Furthermore, the inclusion of a tackifier increases stickiness, which tends to improve grip.

[0056] From the viewpoint of improving gripping properties, the content of the tackifier in the rubber composition for an outsole of this embodiment is preferably 1 part by mass or more, more preferably 2 parts by mass or more, more preferably 4 parts by mass or more, even more preferably 5 parts by mass or more, even more preferably 7 parts by mass or more, even more preferably 8 parts by mass or more, and particularly preferably 10 parts by mass or more, per 100 parts by mass of the above-mentioned rubber. On the other hand, from the viewpoint of suppressing excessive stickiness and dust adhesion, the content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, even 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 above-mentioned rubber.

[0057] Moreover, from the viewpoint of suppressing dust adhesion to the rubber composition for an outsole of this embodiment, the softening point of the tackifier is preferably 40° C. or higher, more preferably 50° C. or higher, and even more preferably 55° C. or higher. On the other hand, from the viewpoint of processability, the softening point is preferably 180° C. or lower, more preferably 170° C. or lower, even more preferably 160° C. or lower, and even more preferably 150° C. or lower. The softening point of the tackifier can be measured by the ring and ball method of JIS K5601-2-2, and can be controlled within the above temperature range by selecting the materials.

[0058] From the viewpoint of flexibility of the rubber composition for an outsole of this embodiment, the glass transition temperature of the tackifier is preferably −20° C. or higher, more preferably 0° C. or higher, and even more preferably 10° C. or higher. On the other hand, because it is necessary for the tackifier to melt and be mixed into the rubber during kneading, the glass transition temperature is preferably 130° C. or lower, more preferably 120° C. or lower, and even more preferably 100° C. or lower. The glass transition temperature of the tackifier can be measured by differential scanning calorimetry (DSC), and can be controlled within the above temperature range by selecting the materials.

[0059] A wide variety of tackifiers can be selected depending on the intended use of the rubber composition for outsoles, the required performance, and the rubber components used. For example, since terpene compounds such as those described below have good compatibility with natural rubber, using a terpene compound as a tackifier and natural rubber as the rubber can suppress bleeding of the terpene compound. Examples of tackifiers include, but are not limited to, rosin compounds such as natural rosin, modified rosin, glycerol esters of natural rosin, glycerol esters of modified rosin, pentaerythritol esters of natural rosin, pentaerythritol esters of modified rosin, hydrogenated rosin, and pentaerythritol esters of hydrogenated rosin; copolymers of natural terpenes, three-dimensional polymers of natural terpenes, aromatic modified terpene resins, hydrogenated derivatives of aromatic modified terpene resins, terpene phenolic resins, hydrogenated derivatives of terpene phenolic resins, terpene resins (monoterpenes, diterpenes, triterpenes, polyterpenes), and the like. Examples of tackifiers include terpene-based compounds such as aliphatic petroleum hydrocarbon resins (C5 resins) and hydrogenated derivatives of aliphatic petroleum hydrocarbon resins; aromatic petroleum hydrocarbon resins (C9 resins) and hydrogenated derivatives of aromatic petroleum hydrocarbon resins; dicyclopentadiene-based resins, hydrogenated derivatives of dicyclopentadiene-based resins; C5 / C9 copolymer-based resins, hydrogenated derivatives of C5 / C9 copolymer-based resins; cycloaliphatic petroleum hydrocarbon resins, hydrogenated derivatives of cycloaliphatic petroleum hydrocarbon resins; and aromatic group-containing resins. These tackifiers may be used alone or in combination of two or more. A C5 / C9 copolymer is a copolymerized petroleum resin polymerized using a mixture of C5 and C9 fractions as raw materials. Liquid tackifiers that are colorless to pale yellow, substantially odorless, and have good thermal stability can also be used. Preferred tackifiers depending on the application and performance will be described in more detail below.

[0060] <Hydrogenated Derivative Tackifier> From the viewpoints of low odor and quality stability, it is preferable to use a hydrogenated derivative as the tackifier. Examples of hydrogenated derivatives include, but are not limited to, hydrogenated derivatives of aromatic modified terpene resins, hydrogenated derivatives of terpene phenol resins, hydrogenated derivatives of hydrogenated terpene resins, hydrogenated derivatives of aliphatic petroleum hydrocarbon resins (C5 resins), hydrogenated derivatives of aromatic petroleum hydrocarbon resins (C9 resins), hydrogenated derivatives of dicyclopentadiene resins, hydrogenated derivatives of C5 / C9 copolymer resins, and hydrogenated derivatives of cyclic aliphatic petroleum hydrocarbon resins. Among these, hydrogenated derivatives of aromatic petroleum hydrocarbon resins (C9 resins), hydrogenated derivatives of dicyclopentadiene resins, and hydrogenated derivatives of hydrogenated terpene resins are particularly preferred. Commercially available hydrogenated derivatives of this kind include, but are not limited to, the Arkon P and M series (trade names) manufactured by Arakawa Chemical Industry Co., Ltd., the Imave S and P series manufactured by Idemitsu Kosan Co., Ltd., the ESCOREZ 5000 series (trade name) manufactured by ExxonMobil, and the Clearon P series manufactured by Yasuhara Chemical Co., Ltd. Furthermore, examples of the ESCOREZ 5000 series include ESCOREZ 5600, which is a hydrogenated derivative of a copolymer of dicyclopentadiene and an aromatic compound, and ESCOREZ 5300 and ESCOREZ 5400, which are hydrogenated derivatives of dicyclopentadiene.

[0061] <Tackifiers Other Than Hydrogenated Derivatives> Examples of tackifiers other than hydrogenated derivatives include, but are not limited to, natural rosin, modified rosin, glycerol esters of natural rosin, glycerol esters of modified rosin, pentaerythritol esters of natural rosin, pentaerythritol esters of modified rosin, hydrogenated rosin, pentaerythritol esters of hydrogenated rosin; copolymers of natural terpene, three-dimensional polymers of natural terpene, aromatic modified terpene resins, terpene phenol resins, terpene resins, hydrogenated terpene resins; aliphatic petroleum hydrocarbon resins (C5 resins), aromatic petroleum hydrocarbon resins (C9 resins), dicyclopentadiene resins, C5 / C9 copolymer resins, cycloaliphatic petroleum hydrocarbon resins, and alkylphenols. Among these, aliphatic petroleum hydrocarbon resins (C5 resins), aromatic petroleum hydrocarbon resins (C9 resins), C5 / C9 copolymer resins, cycloaliphatic petroleum hydrocarbon resins, terpene resins, natural and modified rosin esters, and mixtures thereof are preferred. Commercially available products include, but are not limited to, the following: aliphatic petroleum hydrocarbon resins (C5 resins) include the Quinton 100 series (trade name) manufactured by Zeon Corporation, the ESCOREZ 1000 series (trade name) manufactured by ExxonMobil, and the WINGTACK series (trade name) manufactured by Cray Valley; aromatic petroleum hydrocarbon resins (C9 resins); C5 / C9 copolymer resins include the PICCOTAC series (trade name) manufactured by Eastman Chemical Company, the ESCOREZ 2000 series (trade name) manufactured by ExxonMobil Chemical Company, and the FTR series (trade name) manufactured by Mitsui Chemicals, Inc.; terpene resins; and natural and modified rosin esters include the SYLVALITE series and SYLVARES series (trade name) manufactured by Arizona Chemical Company and the PICCOLYTE series (trade name) manufactured by PINOVA.

[0062] <Aliphatic Tackifier> From the viewpoint of obtaining a rubber composition for an outsole having high grip strength and from the viewpoint of economy, it is preferable to use an aliphatic tackifier as the tackifier. Examples of aliphatic tackifiers include, but are not limited to, aliphatic petroleum hydrocarbon resins (C5 resins), hydrogenated derivatives of aliphatic petroleum hydrocarbon resins (C5 resins), C5 / C9 copolymer resins, and hydrogenated derivatives of C5 / C9 copolymer resins. The aliphatic tackifier refers to a tackifier having an aliphatic hydrocarbon group content of preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 88% by mass or more, and even more preferably 95% by mass or more. Having the aliphatic hydrocarbon group content within the above range tends to further improve adhesion, holding power, and economy. The aliphatic tackifier can be produced by homopolymerizing or copolymerizing a monomer having an aliphatic group and a polymerizable unsaturated group. Monomers having an aliphatic group and a polymerizable unsaturated group include, but are not limited to, natural and synthetic terpenes containing C5 or C6 cyclopentyl or cyclohexyl groups. Other monomers that can be used in the copolymerization include, but are not limited to, 1,3-butadiene, cis-1,3-pentadiene, trans-1,3-pentadiene, 2-methyl-1,3-butadiene, 2-methyl-2-butene, cyclopentadiene, dicyclopentadiene, terpenes, terpene-phenolic resins, and the like.

[0063] <Aromatic Tackifier> From the viewpoint of obtaining a rubber composition for an outsole that is processable and suppresses bleeding due to high compatibility with the above-mentioned rubber, it is preferable to use an aromatic tackifier as the tackifier. Examples of aromatic tackifiers include, but are not limited to, aromatic petroleum hydrocarbon resins (C9 resins) and C5 / C9 copolymer resins. The aromatic tackifier refers to a tackifier having an aromatic hydrocarbon group content of preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 88% by mass or more, and even more preferably 95% by mass or more. Having the aromatic hydrocarbon group content within the above range tends to further improve adhesion and coatability. The aromatic tackifier can be produced by homopolymerizing or copolymerizing monomers each having an aromatic group and a polymerizable unsaturated group. Monomers having an aromatic group and a polymerizable unsaturated group include, but are not limited to, styrene, α-methylstyrene, vinyltoluene, methoxystyrene, tert-butylstyrene, chlorostyrene, and indene monomers (including methylindene). Other monomers that can be used in copolymerization include, but are not limited to, 1,3-butadiene, cis-1,3-pentadiene, trans-1,3-pentadiene, 2-methyl-1,3-butadiene, 2-methyl-2-butene, cyclopentadiene, dicyclopentadiene, terpene, and terpene-phenol resins.

[0064] As the tackifier used in the rubber composition for an outsole of this embodiment, it is preferable to use the above-mentioned tackifiers having high affinity with rubber.

[0065] The tackifier used in the rubber composition for outsoles of this embodiment is preferably a tackifier that, when a mixture with the conjugated diene polymer described above is measured by differential scanning calorimetry (DSC), a single inflection point derived from the glass transition is observed when the temperature is raised from -120°C to 0°C at a rate of 10°C / min. The rubber composition for outsoles of this embodiment preferably uses a conjugated diene polymer as the rubber, and polybutadiene or a styrene-butadiene copolymer is preferably used as the conjugated diene polymer. When such polybutadiene or styrene-butadiene copolymer and a tackifier are contained, an inflection point derived from the glass transition temperature appears between -120°C and 0°C. To achieve a single inflection point derived from the glass transition, it is preferable to use a tackifier that has good compatibility with the conjugated diene polymer. Good compatibility is indicated by a small difference in the SP values ​​between the rubber and the tackifier. Satisfying the above conditions means that the compatibility between the conjugated diene polymer and the tackifier is relatively high. This reduces bleeding onto the surface, allowing a high level of balance between gripping ability and abrasion resistance to be stably achieved. On the other hand, if the compatibility between the conjugated diene polymer and the tackifier is poor, bleeding of the tackifier tends to be somewhat more, resulting in stickiness. In this case, it is preferable to add the tackifier in an amount of 10 parts by mass or less per 100 parts by mass of the conjugated diene polymer.

[0066] From the viewpoint of transparency, the tackifier used in the rubber composition for an outsole of the present embodiment has an SP value difference from the rubber of the present invention of preferably 0.8 (cal / cm ３ ) ２ or less, more preferably 0.55 (cal / cm ３ ) ２ More preferably, 0.3 (cal / cm ３ ) ２ The following is the result.

[0067] Furthermore, when the tackifier used in the rubber composition for an outsole of this embodiment is the terpene resin, from the viewpoint of compatibility between the rubber and the tackifier, the conjugated diene polymer as the rubber preferably has an aromatic vinyl monomer unit content of 10% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less, and the vinyl bond amount is preferably 24% by mass or more and 60% or less, more preferably 28% by mass or more and 58% or less, and even more preferably 29% by mass or more and 57% or less.

[0068] When the tackifier used in the rubber composition for an outsole of the present embodiment is the petroleum hydrocarbon-based compound, from the viewpoint of compatibility between the rubber and the tackifier, the conjugated diene polymer as the rubber preferably has an aromatic vinyl monomer unit content of 20% by mass or more and 60% by mass or less, more preferably 24% by mass or more and 60% by mass or less, and even more preferably 30% by mass or more and 58% by mass or less, and the vinyl bond amount is preferably 20% by mass or more and 55% by mol or less, more preferably 22% by mass or more and 55% by mass or less, and even more preferably 23% by mass or more and 54% or less.

[0069] From the viewpoint of suppressing hardening of the outsole at low temperatures, the difference in glass transition temperature between the tackifier used in the rubber composition for an outsole of this embodiment and the rubber is preferably 10° C. or more, more preferably 20° C. or more, and even more preferably 30° C. or more. On the other hand, from the viewpoint of suppressing adhesion of dust, the difference in glass transition temperature is preferably 180° C. or less, more preferably 170° C. or less, and even more preferably 160° C. or less.

[0070] The tackifier used in the rubber composition for an outsole of the present embodiment preferably has a b* value of 50 or less, more preferably 35 or less, and even more preferably 20 or less, from the viewpoint of design.

[0071] From the viewpoint of processability, the mixture of the rubber and the tackifier that constitutes the rubber composition for an outsole of the present embodiment preferably has one Tg in differential scanning calorimetry (DSC).

[0072] (Crosslinking Agent) The rubber composition for an outsole of the present embodiment is preferably a crosslinked product of a composition containing a predetermined crosslinking agent in addition to rubber, a filler, and a tackifier.

[0073] The crosslinking agent is not particularly limited, and any known crosslinking agent used for crosslinking rubber compositions can be used. Suitable examples of the crosslinking agent include sulfur, sulfur compounds, organic peroxides, and radical crosslinking agents.

[0074] Examples of organic peroxides include, but are not limited to, dicumyl peroxide, benzoyl peroxide, di-t-hexyl peroxide, t-butylcumyl peroxide, diisobutyryl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, di(2-t-butylperoxyisopropyl)benzene, cumyl peroxy neodecanoate, and di-n-propyl peroxydicarbonate. , diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, di(4-t-butylcyclohexyl)peroxydicarbonate, di(2-ethylhexyl)peroxydicarbonate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxyneoheptanoate, t-hexylperoxypivalate, t-butylperoxypivalate, di(3,5,5-trimethylbutyl)peroxyneodecanoate, Di(methylhexanoyl) peroxide, dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, disuccinic acid peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, di(4-methylbenzoyl) peroxide, t-butylperoxy-2-ethylhexanoate, di(3-methylbenzoyl) peroxide, benzoyl(3-methylbenzoyl) peroxide amide, dibenzoyl peroxide, 1,1-di(t-butylperoxy)-2-methylcyclohexane, 1,1-di(t-hexylperoxy)-3,5,5-trimethylcyclohexane, 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)cyclohexane, 2,2-di(4,4-di-(t-butylperoxy)cyclohexyl)propane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxyacetate, 2,2-di-(t-butylperoxy)butane, t-butylperoxybenzoate, n-butyl-4,4-di-(t-butylperoxy)valerate, di(2-t-butylperoxyisopropyl)benzene, di-t-butyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, and t-butyl hydroperoxide.

[0075] Examples of radical crosslinkers include, but are not limited to, ethylene glycol methacrylate (EGDMA), trimethylolpropane trimethacrylate, triallyl isocyanurate, triallyl cyanurate, diethylene glycol diacrylate, and neophenylene glycol diacrylate.

[0076] When emphasis is placed on the minimal contamination of the product, transparency, colorability, and heat resistance, it is preferable to select a peroxide as the crosslinking agent. From the viewpoint of minimal odor and residue, the crosslinking agent is more preferably dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, di(2-t-butylperoxyisopropyl)benzene, or 1,1-di(t-butylperoxy)cyclohexane. Furthermore, when a rubber with few double bonds, such as butyl rubber, silicone rubber, or fluororubber, is used as the rubber, it is preferable to select an organic peroxide as the crosslinking agent.

[0077] On the other hand, when cost, tensile properties, and ease of processing are important, crosslinking is preferably performed using sulfur or a sulfur compound and a vulcanization accelerator. Examples of sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, and polymeric polysulfur compounds.

[0078] The above crosslinking agents may be used alone or in combination of two or more.

[0079] In the outsole manufacturing process, the content of the crosslinking agent contained in the rubber composition for an outsole before molding is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the rubber. As the vulcanization method, a conventionally known method can be applied, and the vulcanization temperature is preferably 120°C or more and 200°C or less, and more preferably 140°C or more and 180°C or less.

[0080] When vulcanization is performed using sulfur or a sulfur compound, a vulcanization accelerator may be used as necessary. Conventionally known vulcanization accelerators can be used, and examples thereof include, but are not limited to, sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators. Furthermore, examples of vulcanization aids include, but are not limited to, zinc oxide, stearic acid, and triallyl isocyanurate. The content of the vulcanization accelerator is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the rubber component.

[0081] (Other Components) When silica is used as the filler, the rubber composition for an outsole of this embodiment preferably contains a silane coupling agent. According to this embodiment, the dispersibility of the inorganic filler and adhesion to the rubber are improved, and transparency and strength tend to be further improved. Examples of silane coupling agents include, but are not limited to, alkoxysilane compounds such as tetraethoxysilane, vinyltrimethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-aminopropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, bis-[3-(triethoxysilyl)propyl]tetrasulfide, bis-[3-(triethoxysilyl)propyl]disulfide, and triethoxysilylpropyl methacrylate monosulfide. The silane coupling agent is preferably a polysiloxane containing a vinyl group and an alkoxy group, more preferably a polysiloxane containing a vinyl group and an ethoxy group or a methoxy group, and even more preferably vinyltrimethoxysilane or vinyltris(2-methoxyethoxy)silane. The above silane coupling agents may be used alone or in combination of two or more. The content of the silane coupling agent is not particularly limited and may be, for example, 0 to 20 parts by mass per 100 parts by mass of the rubber. The content of the silane coupling agent is more preferably 0.50 to 10 parts by mass.

[0082] The rubber composition for an outsole of this embodiment may further contain other components. Examples of the other components include antioxidants, colorants, modifiers, processing agents (such as fatty acids), reducing agents, oxygen scavengers, light stabilizers, pH stabilizers, surface treatment agents, heat stabilizers, colorants, fillers (such as talc and calcium carbonate), surfactants, gelling agents, UV absorbers (such as salicylic acid, benzophenone, benzotriazole, cyanoacrylate, and hindered amine), dusting agents (such as polyolefins such as polyethylene, talc, and calcium carbonate powder), and polyphosphoric acid. These components may be used alone or in combination of two or more. Examples of antioxidants include, but are not limited to, monophenolic, bisphenolic, polyphenolic, sulfur-based, and phosphorus-based compounds, and specific examples include Nocrac SP (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), Irganox 1076 (manufactured by BASF), Irgafos 168 (manufactured by BASF), and Irganox 1520 (manufactured by BASF). A colorant may be used when it is desired to color the outsole. Such colorants may include any known colorant, such as color pigments, extender pigments, anti-rust pigments, and functional pigments (e.g., phthalocyanine green, titanium dioxide, iron blue, iron oxide, lead suboxide, and zinc sulfide).

[0083] The rubber composition for an outsole of the present embodiment may contain one or more components, such as antioxidants, colorants, modifiers, processing agents, reducing agents, oxygen scavengers, light stabilizers, pH stabilizers, surface treatment agents, heat stabilizers, colorants, fillers, surfactants, gelling agents, UV absorbers, dusting agents, and polyphosphoric acids, in a total amount, for example, of 0.1 to 15 parts by mass per 100 parts by mass of the rubber component. When these components are contained, the total content of these components is preferably 0.2 to 10 parts by mass, more preferably 0.20 to 5.0 parts by mass, and even more preferably 0.25 to 2.0 parts by mass.

[0084] (Transparency) The rubber composition for outsoles of this embodiment may be used for transparent outsoles with high transparency. The transparency of an outsole is evaluated by haze. The lower the haze, the higher the transparency. Generally, an outsole with a haze of more than 50% is "opaque" or "semi-transparent," while an outsole with a haze of 50% or less is "transparent." From the perspective of achieving excellent transparency, the rubber composition for outsoles of this embodiment preferably has a haze of 50% or less. "Haze" refers to the degree of cloudiness of a transparent material measured in accordance with Japanese Industrial Standard JIS K7136 (or ISO 14782). In this specification, haze can be measured using a 3.00 mm thick sheet as a measurement sample using a testing device conforming to the above standard. Specifically, it can be measured by the method described in the Examples below. The haze of the rubber composition for outsoles of this embodiment can be controlled within the above numerical range by selecting the constituent materials. For example, it is preferable to use silica as a filler.

[0085] [Outsole] The outsole of this embodiment is a molded article made from the rubber composition for an outsole of this embodiment. The outsole of this embodiment can be produced by crosslinking the rubber composition for an outsole of this embodiment, which contains the above-described rubber, filler, and tackifier, using a crosslinking agent, and then optionally adding and kneading other components in an appropriate blending ratio. More specifically, for example, the following method may be used. One example of a method for producing an outsole of this embodiment includes the steps of kneading a conjugated diene polymer and other diene rubber as rubber, silica as a filler, an optional tackifier, a silane coupling agent, a crosslinking agent, a crosslinking aid, and an antioxidant, and molding the resulting kneaded mixture. The kneading step can be performed using, for example, an open roll, a Banbury mixer, a kneader, a twin-screw extruder, and / or a Labo Plastomill. In the kneading step, the above components may be kneaded all at once, or the rubber, filler, and silane coupling agent may be kneaded first, followed by kneading other additives. The kneading with the rubber may be carried out at a temperature of, for example, 120 to 160°C from the viewpoint of uniformly mixing the components. The kneading after the addition of the crosslinking agent may be carried out at a temperature of, for example, 120°C or lower from the viewpoint of suppressing side reactions. The temperature during the kneading after the addition of the crosslinking agent is preferably 100°C or lower, more preferably 80°C or lower, and even more preferably 0 to 50°C. In the above kneading step, other components may be added as appropriate. A crosslinked rubber composition having a desired shape can be obtained by a molding step in which the kneaded mixture is molded. The molding step may be, for example, a step in which the kneaded mixture obtained in the kneading step is placed in a press mold of an appropriate shape and heated. The molding temperature during the molding step is not particularly limited, but is preferably 140 to 180°C, more preferably 150 to 170°C. The outsole of this embodiment is used as an outsole for shoes.

[0086] [Uses of Outsoles] The rubber composition for outsoles of this embodiment can be used for a variety of shoe applications, but the required performance and physical properties considered acceptable for practical use vary depending on the application. For example, sports shoes require strength, abrasion resistance, and grip to withstand intense exercise, and therefore require a better balance of strength, abrasion resistance, and grip than general shoes. Grip is particularly important for sports such as basketball, which involve repeated sudden acceleration and sudden stops. Wet grip is also important for sports, for example, to prevent slipping when used on wet surfaces outdoors or on floors wet with sweat. Furthermore, trekking shoes are used in the mountains for walking on wet boardwalks or rocks near slippery streams, etc., and because slipping poses greater danger than usual, they require high grip as well as abrasion resistance and strength to withstand wear even when climbing rocky terrain. These applications are merely examples of applications of the outsoles of this embodiment, and the physical properties considered acceptable for practical use vary depending on the application and can be adjusted as appropriate.

[0087] The present embodiment will be described in more detail below with reference to specific Production Examples, Examples, and Comparative Examples, but the present invention is not limited to the following Polymerization Examples, Examples, and Comparative Examples. Various physical properties in the Production Examples, Examples, and Comparative Examples were measured by the methods shown below.

[0088] [Physical Property Measurement Methods] [Peak-Top Molecular Weight, Weight-Average Molecular Weight] Chromatograms were measured using a GPC measurement device equipped with three connected columns packed with polystyrene gel, and the weight-average molecular weight and peak-top molecular weight were determined based on a calibration curve using standard polystyrene. Table 1 shows the peak-top molecular weights of the uncoupled and coupled products. Specific measurement conditions are shown below. Measurements were performed by injecting 20 μL of the following measurement solution into the GPC measurement device. (Measurement Conditions) Device: Tosoh Corporation, product name "HLC-8320GPC" Eluent: Tetrahydrofuran (THF) containing 5 mmol / L triethylamine Guard column: Tosoh Corporation, 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: 0.6 mL / min Detector: RI detector (trade name "HLC8020" manufactured by Tosoh Corporation) Measurement solution: Measurement solution prepared by dissolving 10 mg of a measurement sample in 20 mL of THF

[0089] [Modification Ratio] The modification ratio was measured by the column adsorption GPC method, taking advantage of the property of the modified polymer to adsorb to a column, as follows. A sample solution containing a sample and a low-molecular-weight internal standard polystyrene was measured using a column packed with polystyrene-based gel, and the amount of adsorption to the silica-based column was measured from the difference between the chromatogram measured using a column packed with silica-based gel, and the modification ratio was determined. (GPC Measurement Conditions Using a Polystyrene-Based Column) The GPC measurement conditions using a polystyrene-based column are shown below. Measurement was performed by injecting 20 μL of the following measurement solution into the GPC measurement device. Apparatus: Tosoh Corporation, product name "HLC-8320GPC" Eluent: THF containing 5 mmol / L triethylamine Guard column: Tosoh Corporation, 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: 0.6 mL / min Detector: RI detector (Tosoh Corporation, 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. (GPC measurement conditions using a silica-based column) The GPC measurement conditions using a silica-based column are shown below. 50 μL of the following measurement solution was injected into the GPC measurement device and the measurement was performed.Apparatus: Tosoh Corporation, trade name "HLC-8320GPC" Eluent: THF Guard column: GL Sciences, trade name "DIOL 4.6 x 12.5 mm 5 micron" Separation column: Agilent Technologies, trade names "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S" connected in this order Oven temperature: 40°C, Flow rate: 0.5 mL / min Detector: RI detector (Tosoh Corporation, HLC8020) (Method of calculating modification rate): The total peak area of ​​the chromatogram using the polystyrene 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 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, and the modification rate (%) was calculated using the following formula. Denaturation rate (%) = [1 - (P2 x P3) / (P1 x P4)] x 100 (where P1 + P2 = P3 + P4 = 100).

[0090] [Coupling Rate] A chromatogram was measured in the same manner as in the measurement method for the weight average molecular weight and peak top molecular weight described above. When there were two or more peaks, the coupling rate was calculated from the ratio of the area of ​​the uncoupled peak (peak on the low molecular weight side) to the area of ​​the coupled peak (peak on the high molecular weight side). When there was one peak, the coupling rate was set to 0%. When there were three or more peaks, the peak with the lowest molecular weight was considered to be the peak of the uncoupled component, and the peak of the component present on the higher molecular weight side than that peak was considered to be the coupled peak. In this example, a peak refers to a portion that has a maximum value when measured by GPC and is sandwiched between the baseline or minimum value, and has a peak molecular weight of 10,000 or more at the maximum value and a peak area of ​​5% or more.

[0091] [Mooney Viscosity] Using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.), the Mooney viscosity of each polymer was measured in accordance with JIS K6300 (ISO289-1) and ISO289-4. The measurement temperature was 100°C. Here, the sample was preheated for 1 minute, and then the rotor was rotated at 2 rpm. The torque was measured after 4 minutes to determine the Mooney viscosity (ML （１＋４） )

[0092] [Bound styrene content, 1,2-vinyl bond amount in butadiene moiety] A conjugated diene polymer was used as a sample. １ The content of aromatic vinyl monomer units (content of bound styrene) and the amount of 1,2-vinyl bonds were measured by H-NMR measurement. <Measurement conditions> Measurement equipment: JNM-LA400 (manufactured by JEOL) Solvent: deuterated chloroform Measurement sample: conjugated diene polymer Sample concentration: 50 mg / mL Observation frequency: 400 MHz Chemical shift reference: 5 wt % TMS (tetramethylsilane) added to deuterated chloroform Pulse delay: 2.904 seconds Number of scans: 64 times Pulse width: 45° Measurement temperature: 26°C

[0093] [Styrene Block Content] The content of the aromatic vinyl monomer block (styrene block) was measured according to the osmium tetroxide decomposition method described in I. M. Kolthoff, et al., J. Polym. Sci. 1,429 (1946). More specifically, 0.050 g of styrene-butadiene copolymer rubber was dissolved in 10 ml of chloroform, to which 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 mixture was refluxed in a 90°C bath for 12 minutes to carry out an oxidative decomposition reaction. After completion of the reaction, the reaction solution was cooled, and 200 mL of methanol was added to the reaction solution with stirring to precipitate the styrene block component, which was then filtered off using a 5 μm glass filter. The styrene block content was determined by dividing the mass of the resulting product by the total mass of the styrene-butadiene copolymer rubber.

[0094] [Production of Conjugated Diene Polymer] (Production Example 1: Conjugated Diene Polymer 1) A 10 L internal volume, temperature-controllable autoclave equipped with a stirrer and a jacket was used as a reactor. 648 g of 1,3-butadiene, 552 g of styrene, and 5,600 g of cyclohexane, from which impurities had been removed in advance, and 7.81 mmol of tetrahydrofuran (THF), 0.772 mmol of 2,2-bis(2-oxolanyl)propane, and 0.458 mmol of potassium t-amylalkoxide as polar substances were placed in the reactor, and the internal temperature of the reactor was maintained at 51°C. 5.72 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the initiation of the polymerization reaction, the temperature inside the reactor rose due to heat generated by the polymerization, and the reaction peak temperature was 81°C. 5.72 mmol of ethanol was added to this polymer solution as a reaction terminator. To the obtained polymer solution were added 4.4 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 1.4 g of 4,6-bis(octylthiomethyl)-o-cresol as antioxidants, and then the conjugated diene polymer solution was added dropwise to warm water to remove the solvent, followed by drying treatment in a dryer to obtain conjugated diene polymer 1. The obtained conjugated diene polymer 1 was analyzed by the above-mentioned methods, and the analytical results are shown in Table 1.

[0095] (Production Example 2 - Conjugated Diene Polymer 2) A 10 L internal volume, temperature-controllable autoclave equipped with a stirrer and a jacket was used as a reactor. 454 g of 1,3-butadiene, 468 g of styrene, 5,600 g of cyclohexane, and 7.81 mmol of tetrahydrofuran (THF) and 0.858 mmol of 2,2-bis(2-oxolanyl)propane as polar substances, which had been previously removed from impurities, were placed in the reactor, and the internal temperature of the reactor was maintained at 52°C. 6.20 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the initiation of the polymerization reaction, the temperature inside the reactor rose due to heat generated by the polymerization, and a reaction peak was observed at 76°C. Thereafter, 194 g of 1,3-butadiene was added to the reactor, and a reaction peak was observed at 79°C. Further thereafter, 80 g of styrene was added to the reactor, and a reaction peak was observed at 81°C. To this polymer solution, 6.20 mmol of ethanol was added as a reaction terminator. To the obtained polymer solution, 4.4 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 1.4 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then the conjugated diene polymer solution was added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain conjugated diene polymer 2. The obtained conjugated diene polymer 2 was analyzed by the above-mentioned method, and the results are shown in Table 1.

[0096] (Production Example 3 - Conjugated Diene Polymer 3) A 10 L internal volume, temperature-controllable autoclave equipped with a stirrer and a jacket was used as a reactor. 454 g of 1,3-butadiene, 552 g of styrene, 5,600 g of cyclohexane, and 7.81 mmol of tetrahydrofuran (THF) and 0.824 mmol of 2,2-bis(2-oxolanyl)propane as polar substances, which had been previously removed from impurities, were placed in the reactor, and the internal temperature of the reactor was maintained at 52°C. 5.77 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the initiation of the polymerization reaction, the temperature inside the reactor rose due to heat generated by the polymerization, and a reaction peak was confirmed at 76°C. Thereafter, 194 g of 1,3-butadiene was added to the reactor, and a reaction peak was confirmed at 84°C. 5.77 mmol of ethanol was added to this polymer solution as a reaction terminator. To the obtained polymer solution were added 4.4 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 1.4 g of 4,6-bis(octylthiomethyl)-o-cresol as antioxidants, and then the conjugated diene polymer solution was added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain conjugated diene polymer 3. The obtained conjugated diene polymer 3 was analyzed by the above-mentioned method, and the results are shown in Table 1.

[0097] (Production Example 4 - Conjugated Diene Polymer 4) A 10 L internal volume, temperature-controllable autoclave equipped with a stirrer and a jacket was used as a reactor. 454 g of 1,3-butadiene, 552 g of styrene, 5,600 g of cyclohexane, and 7.81 mmol of tetrahydrofuran (THF) and 0.824 mmol of 2,2-bis(2-oxolanyl)propane as polar substances, which had been previously removed from impurities, were placed in the reactor, and the internal temperature of the reactor was maintained at 48°C. 5.77 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the initiation of the polymerization reaction, the temperature inside the reactor rose due to heat generated by the polymerization, and a reaction peak was confirmed at 73°C. Thereafter, 194 g of 1,3-butadiene was added to the reactor, and a reaction peak was confirmed at 78°C. 5.77 mmol of ethanol was added to this polymer solution as a reaction terminator. To the obtained polymer solution were added 4.4 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 1.4 g of 4,6-bis(octylthiomethyl)-o-cresol as antioxidants, and then the conjugated diene polymer solution was added dropwise to warm water to remove the solvent, followed by drying treatment in a dryer to obtain conjugated diene polymer 4. The obtained conjugated diene polymer 4 was analyzed by the above-mentioned method, and the results of the analysis are shown in Table 1.

[0098] (Production Example 5 - Conjugated Diene Polymer 5) A 10 L autoclave equipped with a stirrer and a jacket and capable of temperature control was used as a reactor. 444 g of 1,3-butadiene, 756 g of styrene, 5,600 g of cyclohexane, and 7.81 mmol of tetrahydrofuran (THF), 5.17 mmol of 2,2-bis(2-oxolanyl)propane, and 0.245 mmol of potassium t-amylalkoxide were placed in the reactor, from which impurities had been removed, as well as polar substances such as 7.81 mmol of tetrahydrofuran (THF), 5.17 mmol of 2,2-bis(2-oxolanyl)propane, and 0.245 mmol of potassium t-amylalkoxide. The internal temperature of the reactor was maintained at 43°C. 6.86 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the initiation of the polymerization reaction, the temperature inside the reactor rose due to heat generation caused by the polymerization. After the reaction temperature peaked at 87°C, 1.37 mmol of 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane was added as a coupling agent, and the mixture was stirred for 5 minutes. The coupling rate was 79.6%. To this polymer solution, 1.37 mmol of ethanol was added as a reaction terminator. To the obtained polymer solution, 4.4 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 1.4 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then the conjugated diene polymer solution was added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain conjugated diene polymer 5. The obtained conjugated diene polymer 5 was analyzed by the above-mentioned method, and the results are shown in Table 1.

[0099] (Production Example 6 - Conjugated Diene Polymer 6) A 10 L internal volume, temperature-controllable autoclave equipped with a stirrer and a jacket was used as a reactor. 444 g of 1,3-butadiene, 756 g of styrene, 5,600 g of cyclohexane, and 7.81 mmol of tetrahydrofuran (THF), 4.043 mmol of 2,2-bis(2-oxolanyl)propane, and 0.656 mmol of potassium t-amylalkoxide, which had been previously removed of impurities, were placed in the reactor, and the internal temperature of the reactor was maintained at 44°C. 8.20 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the initiation of the polymerization reaction, the temperature inside the reactor rose due to heat generated by the polymerization, and the reaction peak temperature was 85°C. 8.20 mmol of ethanol was added to this polymer solution as a reaction terminator. To the obtained polymer solution were added 4.4 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 1.4 g of 4,6-bis(octylthiomethyl)-o-cresol as antioxidants, and then the conjugated diene polymer solution was added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain conjugated diene polymer 6. The obtained conjugated diene polymer 6 was analyzed by the above-mentioned method, and the results are shown in Table 1.

[0100] (Production Example 7 - Conjugated Diene Polymer 7) A 10 L internal volume, temperature-controllable autoclave equipped with a stirrer and a jacket was used as a reactor. 690 g of 1,3-butadiene, 510 g of styrene, 5,600 g of cyclohexane, and 7.81 mmol of tetrahydrofuran (THF) and 1.045 mmol of potassium t-amyl alkoxide as polar substances, which had been previously removed from impurities, were placed in the reactor, and the internal temperature of the reactor was maintained at 56°C. 5.23 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the initiation of the polymerization reaction, the temperature inside the reactor rose due to heat generated by the polymerization, and the reaction peak temperature was 77°C. 5.23 mmol of ethanol was added to this polymer solution as a reaction terminator. To the obtained polymer solution were added 4.4 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 1.4 g of 4,6-bis(octylthiomethyl)-o-cresol as antioxidants, and then the conjugated diene polymer solution was added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain conjugated diene polymer 7. The obtained conjugated diene polymer 7 was analyzed by the above-mentioned methods, and the results are shown in Table 1.

[0101] (Production Example 8 - Conjugated Diene Polymer 8) A 10 L autoclave equipped with a stirrer and a jacket and capable of temperature control was used as a reactor. 1,140 g of 1,3-butadiene, 60 g of styrene, 5,600 g of cyclohexane, and 7.81 mmol of tetrahydrofuran (THF) and 5.465 mmol of 2,2-bis(2-oxolanyl)propane as polar substances, which had been previously removed from impurities, were placed in the reactor, and the internal temperature of the reactor was maintained at 48°C. 13.27 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the initiation of the polymerization reaction, the temperature inside the reactor rose due to heat generated by the polymerization. After the reaction temperature peaked at 88°C, 2.99 mmol of 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane was added as a coupling agent, and the mixture was stirred for 5 minutes. The coupling rate was 87.2%. To this polymer solution, 13.27 mmol of ethanol was added as a reaction terminator. To the obtained polymer solution, 4.4 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 1.4 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then the conjugated diene polymer solution was added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain conjugated diene polymer 8. The obtained conjugated diene polymer 8 was analyzed by the above-mentioned method, and the results are shown in Table 1.

[0102] (Production Example 9) Conjugated Diene Polymer 9 A 10 L autoclave equipped with a stirrer and a jacket and capable of temperature control was used as a reactor. 1,128 g of 1,3-butadiene, 72 g of styrene, 5,600 g of cyclohexane, and 7.81 mmol of tetrahydrofuran (THF) as a polar substance, all of which had been previously purified, were placed in the reactor, and the internal temperature of the reactor was maintained at 56°C. 21.35 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the initiation of the polymerization reaction, the temperature inside the reactor rose due to heat generated by the polymerization. After the reaction temperature peaked at 91°C, 4.80 mmol of 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane was added as a coupling agent, and the mixture was stirred for 5 minutes. The coupling rate was 89.6%. 21.35 mmol of ethanol was added to this polymer solution as a reaction terminator. To the obtained polymer solution, 4.4 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 1.4 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then the conjugated diene polymer solution was added dropwise to warm water to remove the solvent, followed by drying treatment in a dryer to obtain conjugated diene polymer 9. The obtained conjugated diene polymer 9 was analyzed by the above-mentioned method, and the analytical results are shown in Table 1.

[0103] (Production Example 10) Conjugated Diene Polymer 10 A 10 L autoclave equipped with a stirrer and a jacket and capable of temperature control was used as a reactor. 732 g of 1,3-butadiene, 468 g of styrene, and 5,600 g of cyclohexane, from which impurities had been removed in advance, and 7.81 mmol of tetrahydrofuran (THF), 0.742 mmol of 2,2-bis(2-oxolanyl)propane, and 0.440 mmol of potassium t-amylalkoxide as polar substances were placed in the reactor, and the internal temperature of the reactor was maintained at 50°C. 5.50 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the initiation of the polymerization reaction, the temperature inside the reactor rose due to heat generated by the polymerization, and the reaction peak temperature was 82°C. 5.50 mmol of ethanol was added to this polymer solution as a reaction terminator. To the obtained polymer solution were added 4.4 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 1.4 g of 4,6-bis(octylthiomethyl)-o-cresol as antioxidants, and then the conjugated diene polymer solution was added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain conjugated diene polymer 10. The obtained conjugated diene polymer 10 was analyzed by the above-mentioned methods, and the results are shown in Table 1.

[0104] (Production Example 11) Conjugated Diene Polymer 11 A 10 L autoclave equipped with a stirrer and a jacket and capable of temperature control was used as a reactor. 574 g of 1,3-butadiene, 626 g of styrene, and 5,600 g of cyclohexane, from which impurities had been removed in advance, and 7.81 mmol of tetrahydrofuran (THF), 1.086 mmol of 2,2-bis(2-oxolanyl)propane, and 0.646 mmol of potassium t-amylalkoxide as polar substances were placed in the reactor, and the internal temperature of the reactor was maintained at 53°C. 6.21 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the initiation of the polymerization reaction, the temperature inside the reactor rose due to heat generated by the polymerization, and the peak reaction temperature was 84°C. 6.21 mmol of ethanol was added to this polymer solution as a reaction terminator. To the obtained polymer solution, 4.4 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 1.4 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then the conjugated diene polymer solution was added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain conjugated diene polymer 11. The obtained conjugated diene polymer 11 was analyzed by the above-mentioned methods, and the analytical results are shown in Table 1.

[0105]

[0106] [Production of rubber composition for outsole and outsole] (Example 1) A rubber composition for outsole and an outsole were obtained according to the formulation shown below. <Composition of rubber composition for outsole> Rubber component 1 (ASAPRENE 303 [manufactured by Asahi Kasei Corporation]): 30.0 parts by mass Rubber component 2 (BR1208 [manufactured by LG Chem]): 70.0 parts by mass Filler (REOLOSIL QS20 [manufactured by Tokuyama Corporation]): 30.0 parts by mass Silane coupling agent (Dynasylan 6498 [manufactured by Evonik]): 2.0 parts by mass Tackifier (Arcon M-100 [manufactured by Arakawa Chemical Industries, Ltd.]): 2.0 parts by mass Antioxidant (Nocrac SP [manufactured by Ouchi Shinko Chemical Industry Co., Ltd.]): 0.5 parts by mass Crosslinking agent (Perkmyl D [manufactured by NOF Corporation]) Total: 134.5 parts by mass

[0107] The above materials were kneaded by the following method to obtain a rubber composition for an outsole and an outsole. Using a 0.6 L Banbury mixer (manufactured by Toyo Seiki Seisakusho, Labo Plastomill 10C100, B600), in the first stage of kneading, rubber component 1 (ASAPRENE 303), filler (REOLOSIL QS20), silane coupling agent (Dynasylan 6498), tackifier (Alcon M-100), and antioxidant (Nocrac SP) were kneaded for 7 minutes under conditions of a filling rate of 65%, a rotor rotation speed of 35 rpm, and an initial temperature of 95°C, to obtain a first-stage compound (a rubber composition for an outsole at a stage not containing a crosslinking agent). Next, after cooling, a crosslinking agent was added and kneaded using an open roll set at 35°C to obtain a compound (a rubber composition for an outsole at a stage containing a crosslinking agent). Finally, the mixture was crosslinked using a heated press at 160°C and a pressure of about 15 MPa for about 13 minutes and molded to obtain a crosslinked outsole composition, i.e., a molded article corresponding to an outsole. After crosslinking, the physical properties of the molded article corresponding to the outsole were measured. The results of the physical property measurements are shown in Table 2 below. The ML viscosity of the second-stage compound and the physical properties of the molded article corresponding to the outsole after crosslinking and molding as described above were measured using the following methods.

[0108] (Examples 2 to 23, Examples 54 to 57, Comparative Examples 1 to 4) The compounding materials and composition ratios of the rubber composition for outsoles were changed as shown in Tables 2 to 4 below, and Examples 2 to 23, Examples 54 to 57, and Comparative Examples 1 to 4 were obtained in the same manner as in Example 1. The compounding materials, composition ratios, and physical property results are shown in Tables 2 to 4. The rubbers, tackifiers, thermoplastic resins, and liquid rubbers used in Examples 2 to 23, Examples 54 to 57, and Comparative Examples 1 to 4 are shown below. <Rubber> ・ASAPRENE 303 [manufactured by Asahi Kasei Corporation] ・Conjugated diene polymer 1 ・Conjugated diene polymer 2 ・Conjugated diene polymer 3 ・Conjugated diene polymer 4 ・Conjugated diene polymer 10 ・Conjugated diene polymer 11 ・BR1208 [manufactured by LG Chem] <Tackifier> ・Arcon M-100 [manufactured by Arakawa Chemical Industries, Ltd.] ・ESCOREZ 5600 [manufactured by ExxonMobil Corporation] ・YS Resin TO115 [manufactured by Yasuhara Chemical Co., Ltd.] ・Pine Crystal KE100 [manufactured by Arakawa Chemical Industries, Ltd.] <Thermoplastic resin> ・Novatec LL [manufactured by Japan Polyethylene Corporation] <Liquid rubber> ・LBR-302 [manufactured by Kuraray Co., Ltd.]

[0109] [Evaluation of Physical Properties of Outsoles] ((1) Compound ML) The rubber composition for outsoles (containing a crosslinking agent) after the second mixing step was used as a measurement sample, and measurements were made in the same manner as in the Mooney viscosity measurement method described above.

[0110] (2) Type A Durometer Hardness (Hardness) Type A durometer hardness was measured in accordance with Japanese Industrial Standard JIS K6253-3 using two 3.00 mm thick sheets of outsole stacked together (total thickness of 6.00 mm) as a measurement sample. The plunger was pressed against the sheet with a constant force, and the depth of penetration 3 seconds later was measured as the Type A durometer hardness.

[0111] (3) Haze Value: The haze value was measured in accordance with Japanese Industrial Standards JIS K7136 (or ISO 14782). The outsole was molded into a sheet having a thickness of 3.00 mm, and the haze value was measured using a haze meter (NDH 2000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0112] (4) Abrasion Resistance (Amount of Wear) Measurement was performed by a DIN abrasion test in accordance with JIS K 6264, and the abrasion resistance was evaluated using an index value. Specifically, the abrasion volumes of the outsoles of the examples and comparative examples were measured in the DIN abrasion test, and the abrasion resistance was determined from the amount of wear.

[0113] (5) Tensile Strength and Elongation The tensile strength and elongation of the outsoles of the Examples and Comparative Examples were measured in accordance with Japanese Industrial Standard JIS K6251. They were evaluated using index values.

[0114] (6) Grip Property (Dynamic Friction Coefficient) The dynamic friction coefficient was measured using a friction and wear tester (Heidon Tribogear Type 40) manufactured by Shinto Scientific Co., Ltd., and the grip property was evaluated using an index value. The sliding surface was a ceramic tile, lubricated with water, and an outsole sheet having a thickness of 3 mm, a width of 30 mm, and a depth of 30 mm was brought into contact with the sliding surface. The sample was then moved back and forth 10 times under a load of 500 gf, a sliding speed of 10 mm / min, and a sliding distance of 80 mm. The dynamic friction coefficients for the outward path from the 6th to 10th sliding strokes were averaged to determine the grip property. The evaluation was performed using an index value.

[0115]

[0116]

[0117]

[0118] The evaluation of each Example in Tables 2 to 4 was based on a composition assumed for sports shoes. The standard evaluation of practically sufficient performance was defined as grip (dynamic friction coefficient) of 85 or more, abrasion resistance (amount of abrasion) of 140 or less, tensile strength of 60 or more, and elongation of 70 or more. It was found that the outsoles of Examples 1 to 23 and Examples 54 to 57 had practically sufficient processability and were superior in strength, abrasion resistance, and grip compared to the outsoles of Comparative Examples 1 to 4.

[0119] [Production of rubber composition for outsole and outsole] (Example 24) A rubber composition for outsole and an outsole were obtained according to the formulation shown below. <Composition of Rubber Composition for Outsole> Rubber component 1 (Conjugated Diene Polymer 5): 30.0 parts by mass Rubber component 2 (UBEPOL BR150 [manufactured by UBE Elastomers]): 60.0 parts by mass Rubber component 3 (Nipol IR2200 [manufactured by Zeon Corporation]): 10.0 parts by mass Filler (Ultrasil VN3 [manufactured by Evonik Corporation]): 40.0 parts by mass Silane coupling agent (Si69 [manufactured by Evonik Corporation]): 2.0 parts by mass Tackifier (Arcon M-100 [manufactured by Arakawa Chemical Industries, Ltd.]): 2.0 parts by mass Antioxidant (Nocrac 6C [manufactured by Ouchi Shinko Chemical Industry Co., Ltd.]): 1.0 part by mass Vulcanization aid (zinc oxide): 3.0 parts by mass Vulcanization aid (stearic acid): 2.0 parts by mass Sulfur: 1.4 parts by mass Vulcanization accelerator (MBT): 1.0 part by mass Vulcanization accelerator (TBBS): 1.0 part by mass Total: 153.0 parts by mass

[0120] The above materials were kneaded by the following method to obtain a rubber composition for an outsole and an outsole. Using a 0.6 L Banbury mixer (manufactured by Toyo Seiki Seisakusho, Labo Plastomill 10C100, B600), rubber component 1 (conjugated diene polymer 5), rubber component 2 (UBEPOL BR150), rubber component 3 (Nipol IR2200), filler (Ultrasil VN3), silane coupling agent (Si69), tackifier (Arcon M-100), and antioxidant (Nocrac 6C) were kneaded for 7 minutes under conditions of a filling rate of 65%, a rotor rotation speed of 35 rpm, and an initial temperature of 75°C to obtain a first-stage compound (a rubber composition for an outsole not containing a crosslinking agent). Next, after cooling, a crosslinking agent was added and kneaded in an open roll set at 80°C as the second stage of kneading, to obtain a compound (a rubber composition for outsoles at the stage where a crosslinking agent is included). Finally, crosslinking was performed for approximately 13 minutes using a heated press at 160°C and a pressure of approximately 15 MPa, followed by molding, to obtain a crosslinked rubber composition for outsoles. The ML viscosity of the compound in the second stage and the physical properties of the rubber composition for outsoles after crosslinking and molding as described above were measured. The results of the physical property measurements are shown in Table 5.

[0121] (Examples 25 to 45, Comparative Examples 5 to 6) The compounding materials and composition ratios of the rubber composition for outsoles were changed as shown in Tables 5 to 7 below, and Examples 25 to 45 and Comparative Examples 5 to 6 were obtained in the same manner as in Example 24. The compounding materials, composition ratios, and physical property results are shown in Tables 5 to 7. The rubbers, tackifiers, and plasticizers used in Examples 25 to 45 and Comparative Examples 5 and 6 are shown below. <Rubber> ASAPRENE Y031 [manufactured by Asahi Kasei Corporation] Conjugated diene polymer 5 Conjugated diene polymer 6 Conjugated diene polymer 7 Conjugated diene polymer 8 Conjugated diene polymer 9 UBEPOL BR150 [manufactured by UBE Elastomers] Nipol IR2200 [manufactured by Zeon Corporation] <Tackifier> Alcon M-100 [manufactured by Arakawa Chemical Industries, Ltd.] ESCOREZ 5600 [manufactured by ExxonMobil Corporation] YS Resin TO115 [manufactured by Yasuhara Chemical Co., Ltd.] Tamanol 440 [manufactured by Arakawa Chemical Industries, Ltd.] YS Resin PX300N [manufactured by Yasuhara Chemical Co., Ltd.] Aradigm R-95 [manufactured by Arakawa Chemical Industries, Ltd.] <Plasticizer>・P-200 [ENEOS Corporation]

[0122] The rubber compositions for outsoles and the outsoles of Examples 24 to 45 and Comparative Examples 5 and 6 were evaluated for physical properties in the same manner as in Example 1. The evaluation results are shown in Tables 5 to 7 below. The Tg numbers of the mixtures of the conjugated diene polymer and the tackifier were measured and evaluated as follows.

[0123] [Tg Number of Mixture of Conjugated Diene Polymer and Tackifier] The Tg number of the mixture of the conjugated diene polymer and the tackifier can be determined by subjecting the mixture to DSC measurement in accordance with Japanese Industrial Standard JIS K6240.

[0124]

[0125]

[0126]

[0127] The evaluation of each Example in Tables 5 to 7 was based on a composition intended for walking use. The standard evaluation of practically sufficient performance was defined as grip (dynamic friction coefficient) of 80 or more, abrasion resistance (amount of wear) of 135 or less, tensile strength of 63 or more, and elongation of 80 or more. It was found that the rubber compositions for outsoles of Examples 24 to 45 had practically sufficient processability and were superior in strength, abrasion resistance, and grip compared to the rubber compositions for outsoles of Comparative Examples 5 and 6.

[0128] [Production of rubber composition for outsole and outsole] (Example 46) A rubber composition for outsole and an outsole were obtained according to the formulation shown below. <Composition of rubber composition for outsole> Rubber component 1 (conjugated diene polymer 5): 100.0 parts by mass Filler (Ultrasil VN3 [manufactured by Evonik]): 40.0 parts by mass Silane coupling agent (Si69 [manufactured by Evonik]): 2.0 parts by mass Tackifier (Arcon M-100 [manufactured by Arakawa Chemical Industries, Ltd.]): 2.0 parts by mass Antioxidant (Nocrac 6C [manufactured by Ouchi Shinko Chemical Industry Co., Ltd.]): 1.0 part by mass Vulcanization aid (zinc oxide): 3.0 parts by mass Vulcanization aid (stearic acid): 2.0 parts by mass Sulfur: 1.4 parts by mass Vulcanization accelerator (MBT): 1.0 part by mass Vulcanization accelerator (TBBS): 1.0 part by mass Total: 153.0 parts by mass

[0129] The above materials were kneaded by the following method to obtain a rubber composition for an outsole and an outsole. Using a 0.6 L Banbury mixer (manufactured by Toyo Seiki Seisakusho, Labo Plastomill 10C100, B600), in the first stage of kneading, rubber component 1 (conjugated diene polymer 5), filler (Ultrasil VN3), silane coupling agent (Si69), tackifier (Alcon M-100), and antioxidant (Nocrac 6C) were kneaded for 7 minutes under conditions of a filling rate of 65%, a rotor rotation speed of 35 rpm, and an initial temperature of 75°C, to obtain a first-stage compound (a rubber composition for an outsole at a stage not containing a crosslinking agent). Next, after cooling, a crosslinking agent was added and kneaded using an open roll set at 80°C to obtain a compound (a rubber composition for an outsole at a stage containing a crosslinking agent). Finally, the mixture was crosslinked using a heated press at 160°C and a pressure of about 15 MPa for about 13 minutes and molded to obtain a rubber composition for an outsole. The ML viscosity of the second-stage compound and the physical properties of the rubber composition for an outsole after crosslinking and molding as described above were measured. The results of the physical property measurements are shown in Table 8.

[0130] (Examples 47 to 50, Comparative Examples 7 to 8) The compounding materials and composition ratios of the rubber composition for outsoles were changed as shown in Table 8 below, and Examples 47 to 50 and Comparative Examples 7 to 8 were obtained in the same manner as in Example 46. The compounding materials, composition ratios, and physical property results are shown in Table 8. The rubbers, tackifiers, and plasticizers used in Examples 47 to 50 and Comparative Examples 7 to 8 are as follows: <Rubber> Conjugated diene polymer 5 ASAPRENE Y031 [manufactured by Asahi Kasei Corporation] <Tackifier> Alcon M-100 [manufactured by Arakawa Chemical Industries, Ltd.] <Plasticizer> P-200 [manufactured by ENEOS Corporation]

[0131] The rubber compositions for outsoles and the outsoles of Examples 46 to 50 and Comparative Examples 7 and 8 were evaluated for physical properties in the same manner as in Example 1. The evaluation results are shown in Table 8 below.

[0132]

[0133] The evaluation of each Example in Table 8 was based on a composition intended for use in trekking shoes. The standard evaluation of practically sufficient performance was defined as grip (dynamic friction coefficient) of 90 or more, abrasion resistance (amount of wear) of 140 or less, tensile strength of 75 or more, and elongation of 80 or more. It was found that the rubber compositions for outsoles obtained in Examples 46 to 50 had practically sufficient processability and were excellent in strength, abrasion resistance, and grip compared to the rubber compositions for outsoles of Comparative Examples 7 and 8.

[0134] [Production of rubber composition for outsole and outsole] (Example 51) A rubber composition for outsole and an outsole were obtained according to the formulation shown below. <Composition of Rubber Composition for Outsole> Rubber component 1 (UBEPOL BR150 [manufactured by UBE Elastomers]): 70.0 parts by mass Rubber component 2 (Nipol DN4050 [manufactured by Zeon Corporation]): 30.0 parts by mass Filler (Ultrasil VN3 [manufactured by Evonik Corporation]): 40.0 parts by mass Silane coupling agent (Si69 [manufactured by Evonik Corporation]): 2.0 parts by mass Tackifier (ESCOREZ5600 [manufactured by ExxonMobil Corporation]): 10.0 parts by mass Antioxidant (Nocrac 6C [manufactured by Ouchi Shinko Chemical Industry Co., Ltd.]): 1.0 part by mass Vulcanization aid (zinc oxide): 3.0 parts by mass Vulcanization aid (stearic acid): 2.0 parts by mass Sulfur: 1.4 parts by mass Vulcanization accelerator (MBT): 1.0 part by mass Vulcanization accelerator (TBBS): 1.0 part by mass Total: 153.0 parts by mass

[0135] The above materials were kneaded by the following method to obtain a rubber composition for an outsole and an outsole. Using a 0.6 L Banbury mixer (Toyo Seiki, Labo Plastomill 10C100, B600), rubber component 1 (UBEPOL BR150), rubber component 2 (Nipol DN4050), filler (Ultrasil VN3), silane coupling agent (Si69), tackifier (ESCOREZ5600), and antioxidant (Nocrac 6C) were kneaded for 7 minutes under the following conditions: a filling rate of 65%, a rotor rotation speed of 35 rpm, and an initial temperature of 75°C. This resulted in a first-stage compound (a rubber composition for an outsole that does not contain a crosslinking agent). After cooling, the mixture was kneaded in a second stage using an open roll set at 80°C, where a crosslinking agent was added and kneaded to obtain a compound (a rubber composition for an outsole that contains a crosslinking agent). Finally, the mixture was crosslinked at 160°C and a pressure of about 15 MPa for about 13 minutes using a heated press, and then molded to obtain a rubber composition for an outsole. The ML viscosity of the second-stage compound and the physical properties of the rubber composition for an outsole after crosslinking and molding as described above were measured. The results of the physical property measurements are shown in Table 9.

[0136] (Examples 52-53, Comparative Example 9) The compounding materials and composition ratios of the rubber composition for outsoles were changed as shown in Table 9 below, and Examples 52-53 and Comparative Example 9 were obtained in the same manner as in Example 51. The compounding materials, composition ratios, and physical property results are shown in Table 9. The rubbers and tackifiers used in Examples 52-53 and Comparative Example 9 are as follows. <Rubber> - UBEPOL BR150 [manufactured by UBE Elastomers] - ASAPRENE Y031 [manufactured by Asahi Kasei Corporation] - Nipol DN4050 [manufactured by Nippon Zeon Co., Ltd.] - Bromobutyl 2244 [manufactured by ExxonMobil] <Tackifier> - ESCOREZ 5600 [manufactured by ExxonMobil]

[0137] The rubber compositions for outsoles and the outsoles of Examples 51 to 53 and Comparative Example 9 were evaluated for physical properties in the same manner as in Example 1. The evaluation results are shown in Table 9 below.

[0138]

[0139] The evaluation of each Example in Table 9 was based on a composition intended for use in running shoes. The standard evaluation of practically sufficient performance was defined as grip (dynamic friction coefficient) of 90 or more, abrasion resistance (amount of wear) of 210 or less, tensile strength of 78 or more, and elongation of 76 or more. It was found that the rubber compositions for outsoles obtained in Examples 51 to 53 had practically sufficient processability and were superior in strength, abrasion resistance, and grip compared to the rubber composition for outsoles of Comparative Example 9.

[0140] This application is based on a Japanese patent application (Patent Application No. 2023-116818) filed with the Japan Patent Office on July 18, 2023, the contents of which are incorporated herein by reference.

[0141] The rubber composition for an outsole of this embodiment has industrial applicability as a material for sports shoes, walking shoes, and trekking shoes.

Claims

1. A rubber composition for an outsole, comprising: rubber; a filler; and a tackifier.

2. The rubber composition for an outsole according to claim 1, wherein the rubber comprises a conjugated diene polymer.

3. The rubber composition for outsoles according to claim 2, wherein the conjugated diene polymer contains aromatic vinyl monomer units and conjugated diene monomer units.

4. The rubber composition for outsoles according to claim 3, wherein the conjugated diene polymer has an aromatic vinyl monomer unit content of 10% by mass or more and 60% by mass or less, and a vinyl bond amount of 20% by mass or more and 70% by mass or less.

5. The rubber composition for outsoles according to claim 3, wherein the conjugated diene polymer has an aromatic vinyl monomer block content of 5 mass% or less.

6. The rubber composition for outsoles according to claim 1, wherein the content of the filler is 15 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the rubber.

7. The rubber composition for an outsole according to claim 1, comprising 80 mass % or more of silica based on the total mass of the filler.

8. The rubber composition for an outsole according to claim 1, wherein the softening point of the tackifier is 40 to 170°C.

9. The composition for outsoles according to claim 1, wherein the tackifier has a glass transition temperature of -20°C or higher.

10. The rubber composition for an outsole according to claim 1, wherein the tackifier is a terpene compound and / or a petroleum hydrocarbon compound.

11. The outsole composition according to claim 1, wherein the tackifier has a b* value of 50 or less.

12. The rubber composition for an outsole according to claim 10, wherein the petroleum hydrocarbon compound is an aromatic petroleum hydrocarbon resin or an alkylphenol.

13. The rubber composition for an outsole according to claim 1, wherein the mixture of the rubber and the tackifier has one Tg in differential scanning calorimetry (DSC).

14. The rubber composition for outsoles according to claim 2, wherein the tackifier is a terpene compound, the content of aromatic vinyl monomer units in the conjugated diene polymer is from 10% by mass to 50% by mass, and the vinyl bond amount is from 24% to 60%.

15. The rubber composition for outsoles according to claim 2, wherein the tackifier is a petroleum hydrocarbon compound, the content of aromatic vinyl monomer units in the conjugated diene polymer is from 20% by mass to 60% by mass, and the vinyl bond amount is from 20% to 55%.

16. The rubber composition for outsoles according to claim 1, wherein the difference in glass transition temperature between said rubber and said tackifier is 10°C or more and 180°C or less.

17. The rubber composition for outsoles according to claim 1, wherein the content of the tackifier in the rubber composition for outsoles is 1 part by mass or more and 30 parts by mass or less per 100 parts by mass of the rubber.

18. The rubber composition for an outsole according to claim 1, wherein the haze is 50% or less.

19. The rubber composition for an outsole according to claim 1, wherein the rubber contains nitrile rubber in an amount of 10% by mass or more and less than 60% by mass.

20. The rubber composition for an outsole according to claim 1, wherein the rubber contains epichlorohydrin rubber in an amount of 10% by mass or more and 90% by mass or less.

21. The rubber composition for an outsole according to claim 1, wherein the rubber contains urethane rubber in an amount of 10% by mass or more and 90% by mass or less.

22. The rubber composition for an outsole according to claim 1, wherein the rubber contains chlorosulfonated ethylene rubber in an amount of 10% by mass or more and 90% by mass or less.

23. The rubber composition for an outsole according to claim 1, wherein the rubber contains 10% by mass or more and 90% by mass or less of acrylic rubber.

24. The rubber composition for outsoles according to claim 1, wherein the rubber contains silicone rubber in an amount of 10% by mass or more and 90% by mass or less.

25. The rubber composition for an outsole according to claim 1, wherein the rubber contains 10% by mass or more and 90% by mass or less of fluororubber.

26. The rubber composition for an outsole according to claim 2, wherein the conjugated diene-based polymer comprises polybutadiene and a styrene-butadiene copolymer.

27. An outsole which is a molded product of the rubber composition for outsoles according to any one of claims 1 to 26.

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