Rubber composition, vulcanized rubber, and tire

Abstract

Disclosed is a rubber composition comprising a diene-based rubber and a compound represented by formula (I). The diene-based rubber comprises at least one rubber selected from the group consisting of natural rubber (NR), styrene / butadiene copolymer rubbers (SBR), and butadiene rubbers (BR).　[Chemical formula 1] (In formula (I), R1 represents an optionally substituted, C4 or higher alkyl group or an optionally substituted aryl group and R2 and R3 each independently represent an optionally substituted alkyl group.)

Description

Rubber compositions, vulcanized rubber, and tires

[0001] The present invention relates to rubber compositions, vulcanized rubber, and tires.

[0002] Conventionally, rubber compositions containing N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD) as an anti-aging agent are known (for example, Patent Document 1).

[0003] Japanese Patent Publication No. 2021-046554

[0004] In recent years, the environmental impact of 6PPD ozone oxidized forms has been reported to be significant, and research into new anti-aging agents to replace 6PPD is underway. On the other hand, anti-aging agents that replace 6PPD tend to have a slow bleed rate (migration rate) in rubber compositions, and their anti-aging effect in a short time is insufficient, so there is a need to improve the bleed rate.

[0005] The main objective of this invention is to provide a rubber composition that can achieve a sufficient anti-aging effect in a short time.

[0006] In view of the above-mentioned problems, the inventors conducted diligent studies and discovered that a rubber composition containing a predetermined diene rubber and a predetermined compound as an anti-aging agent to replace 6PPD exhibits a sufficient anti-aging effect in a short time, thus completing the present invention.

[0007] The present invention provides the rubber compositions described in [1] to [5] below, the vulcanized rubber described in [6], and the tire described in [7]. [1] A rubber composition comprising a diene rubber, a compound represented by formula (I), wherein the diene rubber comprises at least one selected from the group consisting of natural rubber (NR), styrene-butadiene copolymer rubber (SBR), and butadiene rubber (BR). [In formula (I), R １ R represents an alkyl group having four or more carbon atoms, which may have substituents, or an aryl group, which may have substituents. ２ and R ３Each independently represents an alkyl group which may have substituents. ] [2] The rubber composition according to [1], further comprising a filler, wherein the filler comprises at least one selected from the group consisting of carbon black and silica. [3] The rubber composition according to [2], wherein the filler comprises silica. [4] The R １ The rubber composition according to any one of [1] to [3], wherein the branched or cyclic alkyl group having 4 to 8 carbon atoms may have substituents. [5] The rubber composition according to any one of [1] to [4], further comprising a vulcanizing agent. [6] A vulcanized rubber obtained by vulcanizing the rubber composition according to [5]. [7] A tire comprising a rubber member containing the vulcanized rubber according to [6].

[0008] The present invention provides a rubber composition that can obtain a sufficient anti-aging effect in a short time. Furthermore, the present invention provides vulcanized rubber using such a rubber composition. Moreover, the present invention provides a tire using such vulcanized rubber.

[0009] The embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below.

[0010] In this specification, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages within this specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in numerical ranges described within this specification, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples.

[0011] In this specification, unless otherwise specified, the materials exemplified below may be used individually or in combination of two or more, to the extent that the conditions are met. The content of each component refers to the total amount of multiple substances corresponding to each component, unless otherwise specified.

[0012] [Rubber Composition] The rubber composition of one embodiment contains a diene rubber and a compound represented by formula (I), wherein the diene rubber contains a predetermined rubber. The rubber composition may further contain fillers, vulcanizing agents, etc. Since the rubber composition of this embodiment contains a predetermined rubber and a compound represented by formula (I), it is possible to obtain a sufficient anti-aging effect in a short time.

[0013] (Diene-based rubber) The rubber composition contains diene-based rubber. Here, diene-based rubber means rubber made from diene monomers having conjugated double bonds. The diene-based rubber includes at least one selected from the group consisting of natural rubber (NR), styrene-butadiene copolymer rubber (SBR), and butadiene rubber (BR) (hereinafter, these three types of diene-based rubber may be referred to as "rubber A"). Preferably, the diene-based rubber includes at least one selected from the group consisting of natural rubber (NR) and styrene-butadiene copolymer rubber (SBR), and more preferably natural rubber (NR).

[0014] Examples of natural rubber (NR) include grades such as RSS#1, RSS#3, TSR20, and SIR20. Other examples of natural rubber (NR) include epoxidized natural rubber, deproteinized natural rubber, and modified natural rubber.

[0015] The diene rubber may, in addition to rubber A, include other diene rubbers that do not fall under rubber A (hereinafter, these diene rubbers may be referred to as "rubber B"), to the extent that they do not impair the effects of the present invention.

[0016] Examples of rubber B include isoprene rubber (IR), nitrile rubber (NBR), chloroprene rubber (CR), isoprene-isobutylene copolymer rubber (IIR), ethylene-propylene-diene copolymer rubber (EPDM), and halogenated butyl rubber (HR).

[0017] The diene rubbers (rubber A and rubber B) may be modified diene rubbers having units based on various modifying agents in their molecular chains or terminals. Modified diene rubbers can be produced by reacting a modifying agent during solution polymerization of monomers containing conjugated diene compounds.

[0018] As the modifier, there is no particular limitation as long as it is a compound that can be used when producing a modified diene rubber by solution polymerization. By using a diene rubber modified with a compound having a heteroatom, the filler tends to be easily dispersed in the rubber composition. Examples of the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom. Examples of the compound having a heteroatom include an amine compound, an acrylamide compound, a vinylsilane compound, an alkoxysilane compound, a polysiloxane compound, a silane sulfide compound, a sulfanyl silane compound, a cyanate compound, and a polyimine compound.

[0019] Rubber A can be the main component of the diene rubber. The content of Rubber A (the total of natural rubber (NR), styrene-butadiene copolymer rubber (SBR), and butadiene rubber (BR)) is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, still more preferably 80 to 100% by mass, particularly preferably 90 to 100% by mass, and most preferably 95 to 100% by mass based on the total amount of the diene rubber, from the viewpoint of obtaining a more sufficient anti-aging effect in a short time. The content of Rubber A can be, for example, 100% by mass based on the total amount of the diene rubber. That is, the diene rubber may be composed only of Rubber A and may not contain Rubber B.

[0020] The content of the diene rubber (the total of Rubber A and Rubber B) may be 30 to 90% by mass based on the total amount of the rubber composition. The content of the diene rubber is preferably 35% by mass or more, more preferably 40% by mass or more, still more preferably 45% by mass or more, particularly preferably 50% by mass or more, and preferably 85% by mass or less, more preferably 80% by mass or less, still more preferably 75% by mass or less, and particularly preferably 70% by mass or less based on the total amount of the rubber composition.

[0021] (Compound represented by formula (I)) The rubber composition contains a compound represented by formula (I). The compound represented by formula (I) is a component that acts as an anti-aging agent.

[0022]

[0023] In formula (I), R １ represents an alkyl group having 4 or more carbon atoms which may have a substituent, or an aryl group which may have a substituent. R ２ and R ３ each independently represent an alkyl group which may have a substituent.

[0024] R １ Examples of the alkyl group having 4 or more carbon atoms represented by R

[0025] include linear or branched alkyl groups such as linear or branched butyl group, linear or branched pentyl group, linear or branched hexyl group, linear or branched heptyl group, linear or branched octyl group, linear or branched nonyl group, linear or branched decyl group, linear or branched undecyl group, linear or branched dodecyl group, linear or branched tridecyl group, linear or branched tetradecyl group, linear or branched pentadecyl group, linear or branched hexadecyl group, linear or branched heptadecyl group, linear or branched octadecyl group, etc.; cyclic alkyl groups such as cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, bicyclo[1.1.0]butyl group, tricyclo[2.2.1.0]heptyl group, bicyclo[3.2.1]octyl group, bicyclo[2.2.2]octyl group, adamantyl group, bicyclo[4.3.2]undecyl group, tricyclo[5.3.1.1]dodecyl group, etc.

[0025] The number of carbon atoms of the linear or branched alkyl group as R １ is 4 or more, preferably 4 to 18, more preferably 4 to 12, and even more preferably 4 to 8, not including the carbon atoms contained in the substituent.

[0026] Examples of the substituent which the linear or branched alkyl group may have include halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom; hydroxy group; amino group; acetyl group; cyano group, etc.

[0027] R １The number of carbon atoms in the cyclic alkyl group, excluding the carbon atoms in the substituent, is 4 or more, preferably 4 to 18, more preferably 4 to 12, and even more preferably 4 to 8.

[0028] Examples of substituents that a cyclic alkyl group may have include alkyl groups having 1 to 10 carbon atoms (preferably 1 to 4 carbon atoms), such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups; halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; hydroxyl groups; amino groups; acetyl groups; and cyano groups.

[0029] R １ Examples of aryl groups represented by this formula include phenyl, naphthyl, anthracenyl, and fluorenyl groups.

[0030] The number of carbon atoms in the aryl group, excluding the carbon atoms in the substituent, is, for example, 6 or more, preferably 6 to 10.

[0031] Examples of substituents that the aryl group may have include alkyl groups having 1 to 10 carbon atoms (preferably 1 to 4 carbon atoms), such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups; halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; hydroxyl groups; amino groups; acetyl groups; and cyano groups.

[0032] R １ From the viewpoint of anti-aging properties, it is preferably a branched alkyl group having 4 to 8 carbon atoms, which may have substituents, or a cyclic alkyl group having 4 to 8 carbon atoms, which may have substituents, and more preferably a branched alkyl group having 4 to 8 carbon atoms, which may have substituents.

[0033] R ２ and R ３ The alkyl group represented by R is １Examples of alkyl groups include those with four or more carbon atoms represented by , and further examples include alkyl groups with one to three carbon atoms such as methyl groups, ethyl groups, linear or branched propyl groups, and cyclopropyl groups. Alkyl groups with one to three carbon atoms may have substituents, and examples of substituents are the same as those described above.

[0034] R ２ and R ３ The number of carbon atoms in the alkyl group, excluding the carbon atoms included in the substituent, is, for example, 1 to 18, preferably 1 to 12, more preferably 1 to 8, even more preferably 1 to 4, particularly preferably 1 to 3, and most preferably 1.

[0035] Specific examples of compounds represented by formula (I) include, for example, the compounds represented by formula (I-1) and formula (I-2).

[0036]

[0037] The compound represented by formula (I) can be obtained, for example, by a method comprising: a first step (reaction formula I-A) in which a compound represented by formula (Ia) (an aromatic halogen compound) and a compound represented by formula (Ib) (aniline) are reacted in the presence of a palladium catalyst ([Pd]) and a base to obtain an intermediate compound represented by formula (Ic); and a second step (reaction formula I-B) in which a compound represented by formula (Ic) and a compound represented by formula (Id) (an amine) are reacted in the presence of a palladium catalyst ([Pd]) and a base to obtain a compound represented by formula (I). The methods for linking the compound represented by formula (Ia) and the compound represented by formula (Ib), and the methods for linking the compound represented by formula (Ic) and the compound represented by formula (Id) can be known methods (for example, the Butchwald-Hartwig amination reaction).

[0038]

[0039] In reaction equation (I-A), R ２ and R ３ This is synonymous with the above. X １ and X ２Each of these independently represents a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

[0040]

[0041] In the reaction equation (I-B), R １ , R ２ , R ３ , and X ２ This is synonymous with the above.

[0042] The content of the compound represented by formula (I) may be 0.1 to 5 parts by mass per 100 parts by mass of the total amount of diene rubber, from the viewpoint of anti-aging properties. The content of the compound represented by formula (I) is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 0.8 parts by mass or more, particularly preferably 1 part by mass or more, preferably 4 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 2 parts by mass or less, and particularly preferably 1.5 parts by mass or less, per 100 parts by mass of the total amount of diene rubber.

[0043] (Filler) The rubber composition may further contain a filler. The filler includes at least one selected from the group consisting of carbon black and silica. The filler may contain silica, or it may contain both carbon black and silica.

[0044] Examples of carbon black include furnace carbon black, acetylene black, thermal black, channel black, and graphite. Examples of channel black include EPC, MPC, and CC. Examples of furnace carbon black include SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF. Examples of thermal black include FT and MT. The BET specific surface area of ​​the carbon black is preferably 10 to 130 m². ２ / g, more preferably 20 to 130m ２ / g, more preferably 40 to 130m ２ The value is / g. Here, the BET specific surface area refers to the value measured by the BET method in accordance with ASTM D3037-93.

[0045] The carbon black content may be 1 to 60 parts by mass per 100 parts by mass of the total diene rubber, from the viewpoint of low fuel consumption and wear resistance. The carbon black content is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and most preferably 10 parts by mass or less, per 100 parts by mass of the total diene rubber.

[0046] Examples of silica include dry silica (anhydrous silicic acid), wet silica (hydrated silicic acid), colloidal silica, and precipitated silica. The BET specific surface area of ​​the silica is preferably 20 to 400 m². ２ / g, more preferably 50 to 350m ２ / g, more preferably 100 to 300m ２ This is given by / g. Here, the BET specific surface area refers to the value measured by the BET method in accordance with ASTM D1993-03.

[0047] The silica content may be 5 to 100 parts by mass per 100 parts by mass of the total diene rubber, from the viewpoint of low fuel consumption and wear resistance. The silica content is preferably 8 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, particularly preferably 30 parts by mass or more, preferably 95 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 85 parts by mass or less, and particularly preferably 80 parts by mass or less, per 100 parts by mass of the total diene rubber.

[0048] The filler may contain other fillers besides silica and carbon black. Examples of other fillers include calcium silicate, aluminum silicate, aluminum hydroxide, bituminous coal pulverized material, talc, clay (especially calcined clay), titanium dioxide, and the like.

[0049] The total content of carbon black and silica may be 10 to 100 parts by mass per 100 parts by mass of the total diene rubber, from the viewpoint of low fuel consumption and wear resistance. The content of filler is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, preferably 95 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 85 parts by mass or less, per 100 parts by mass of the total diene rubber.

[0050] The filler content may be 10 to 120 parts by mass per 100 parts by mass of the total diene rubber, from the viewpoint of low fuel consumption and wear resistance. The filler content is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, preferably 100 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 85 parts by mass or less, per 100 parts by mass of the total diene rubber.

[0051] (Vulcanizing agent) Examples of vulcanizing agents include sulfur and sulfur compounds. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and surface-treated sulfur.

[0052] The amount of vulcanizing agent may be 0.1 to 5 parts by mass per 100 parts by mass of the total amount of diene rubber. Preferably, the amount of vulcanizing agent is 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, preferably 4 parts by mass or less, and more preferably 3 parts by mass or less, per 100 parts by mass of the total amount of diene rubber.

[0053] (Other components) The rubber composition may further contain other components. Examples of other components include vulcanization accelerators, vulcanization aids, processing aids, antioxidants other than amine-based antioxidants such as compounds represented by formula (I), curing agents, drawstring oils, silane coupling agents, resins, etc.

[0054] Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and dibenzothiadyl disulfide; thiuram-based vulcanization accelerators such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazolyl sulfenamide, N-t-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazolyl sulfenamide, and N,N'-diisopropyl-2-benzothiazolyl sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diorthototrilguanidine, and orthototrilbiguanidine. The vulcanization accelerator preferably includes a sulfenamide-based vulcanization accelerator and / or a guanidine-based vulcanization accelerator.

[0055] The amount of vulcanization accelerator may be 0.1 to 10 parts by mass, 0.3 to 8 parts by mass, or 0.5 to 5 parts by mass per 100 parts by mass of the total amount of diene rubber.

[0056] Examples of vulcanization aids include triallyl isocyanurate, N,N'-m-phenylenebismaleimide, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, 2-ethoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate. Examples include acrylate, methacryloxyethyl phosphate, 1,4-butanediol diacrylate, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, allyl glycidyl ether, N-methylol methacrylamide, 2,2-bis(4-methacryloxypolyethoxyphenyl)propane, aluminum methacrylate, zinc methacrylate, calcium methacrylate, magnesium methacrylate, 3-chloro-2-hydroxypropyl methacrylate, zinc oxide, and magnesium oxide.

[0057] The amount of vulcanization aid may be 0.1 to 15 parts by mass, 0.5 to 10 parts by mass, or 1 to 7 parts by mass per 100 parts by mass of the total amount of diene rubber.

[0058] Examples of processing aids include fatty acids such as oleic acid, palmitic acid, and stearic acid; fatty acid metal salts such as zinc laurate, zinc stearate, barium stearate, and calcium stearate; fatty acid esters; and glycols such as ethylene glycol and polyethylene glycol.

[0059] The amount of processing aid may be 0.1 to 10 parts by mass, 0.5 to 7 parts by mass, or 1 to 5 parts by mass per 100 parts by mass of the total amount of diene rubber.

[0060] Examples of antioxidants other than amine-based antioxidants include sulfur-based antioxidants.

[0061] Examples of sulfur-based anti-aging agents include imidazole-based anti-aging agents such as 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc salt of 2-mercaptomethylbenzimidazole, and zinc salt of 2-mercaptomethylimidazole; and aliphatic thioether-based anti-aging agents such as dimyristylthiodipropionate, dilaurylthiodipropionate, distearylthiodipropionate, ditridecylthiodipropionate, and pentaerythritol-tetrakis(β-lauryl-thiopropionate).

[0062] The total content of the compound represented by formula (I) and the sulfur-based antioxidant may be 0.1 to 5 parts by mass, preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 0.8 parts by mass or more, particularly preferably 1 part by mass or more, preferably 4 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 2 parts by mass or less, particularly preferably 1.5 parts by mass or less, based on 100 parts by mass of the total amount of diene rubber.

[0063] Examples of curing agents include hexamethylenetetramine, hexamethoxymethylolmelamine, pentamethoxymethylolmelamine, hexamethoxymethylmelamine, pentamethoxymethylmelamine, hexaethoxymethylmelamine, hexakis-(methoxymethyl)melamine, N,N',N''-trimethyl-N,N',N''-trimethylolmelamine, N,N',N''-trimethylolmelamine, N-methylolmelamine, N,N'-(methoxymethyl)melamine, N,N',N''-tributyl-N,N',N''-trimethylolmelamine, paraformaldehyde, and the like.

[0064] The curing agent content may be 0.1 to 10 parts by mass, 0.3 to 5 parts by mass, or 0.5 to 3 parts by mass per 100 parts by mass of the total amount of diene rubber.

[0065] Examples of spreading oils include aromatic mineral oils (viscosity-specific gravity constant (VGC value): 0.900 to 1.049), naphthenic mineral oils (VGC value: 0.850 to 0.899), and paraffinic mineral oils (VGC value: 0.790 to 0.849).

[0066] The amount of stretching oil may be 0.1 to 60 parts by mass, 1 to 50 parts by mass, or 5 to 40 parts by mass per 100 parts by mass of the total amount of diene rubber.

[0067] Examples of silane coupling agents include vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, bis[γ-(triethoxysilyl)propyl]tetrasulfide, bis[γ-(triethoxysilyl)propyl]disulfide, and γ-octanoylthio-α-propyltriethoxysilane (NXT® silane).

[0068] The silane coupling agent may be present in an amount of 0.1 to 15 parts by mass, 0.3 to 10 parts by mass, or 0.5 to 8 parts by mass per 100 parts by mass of the total amount of diene rubber.

[0069] Examples of resins include C5 petroleum resins, C5 / C9 petroleum resins, C9 petroleum resins, dicyclopentadiene resins, terpene resins, terpene phenol resins, aromatically modified terpene resins, alkylphenol-acetylene resins, rosin resins, rosin ester resins, indene resins, C9 resins containing indene, α-methylstyrene-indene copolymer resins, coumaron-indene resins, farnesene resins, and polylimonene resins.

[0070] Rubber compositions can be prepared by kneading (mixing) each component using a known kneading machine (mixer) such as a roll or mixer.

[0071] The rubber composition may be prepared, for example, by kneading in the following order: first kneading and second kneading. In the first kneading, components other than the vulcanizing agent and vulcanization accelerator are kneaded using a kneader to obtain a mixture. The kneading temperature for the first kneading is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30 seconds to 30 minutes, preferably 1 to 30 minutes. Next, in the second kneading, the mixture obtained in the first kneading is kneaded with the vulcanizing agent and vulcanization accelerator to obtain a rubber composition. The kneading temperature for the second kneading is usually 100°C or lower, preferably room temperature (25°C) to 80°C.

[0072] [Vulcanized Rubber] The vulcanized rubber of one embodiment is obtained by vulcanizing the above rubber composition.

[0073] Vulcanized rubber can be obtained, for example, by vulcanizing a rubber composition (the rubber composition obtained in the second kneading) through a vulcanization process such as press vulcanization. The vulcanization temperature is usually 120 to 200°C, preferably 140 to 180°C. The vulcanization time is usually 1 to 60 minutes, preferably 10 to 50 minutes.

[0074] Vulcanized rubber is useful for manufacturing tires and rubber components for tires.

[0075] In addition to tire applications, vulcanized rubber can be used in vibration-damping rubber, rubber belt applications, vibration damping agents, and seismic isolation rubber applications. Examples of vibration-damping rubber applications include automotive vibration-damping rubber for engine mounts, strut mounts, bushings, and exhaust hangers. Examples of rubber belt applications include power transmission belts, conveyor belts, and V-belts.

[0076] [Tire] A tire according to one embodiment comprises a rubber member including the above-mentioned vulcanized rubber.

[0077] The rubber component may be covered with steel cords or carcass fiber cords, or it may be a tread. Examples of rubber components include tire belt components containing vulcanized rubber and steel cords, tire carcass components containing vulcanized rubber and carcass fiber cords, tire sidewall components, tire inner liner components, tire cap tread components, tire undertread components, and the like.

[0078] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by the following examples, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit of the above and below, and all such modifications are included within the technical scope of the present invention.

[0079] In the following manufacturing examples, the structure of the compound was confirmed by nuclear magnetic resonance spectroscopy (VARIAN 400-MR).

[0080] Manufacturing Example 1 <Synthesis of the compound represented by formula (I-1) (compound (I-1))> (Synthesis of the compound represented by formula (I-1c) (compound (I-1c))

[0081] Under a nitrogen atmosphere, 2,5-dibromo-p-xylene (225 g, 852 mmol, 1.0 eq.) was dissolved in toluene (2.25 L), and aniline (79.3 g, 851 mmol, 1.0 eq.), Pd ２ (dba) ３ (23.4 g, 25.6 mmol, 0.03 eq.), and BINAP (2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, 31.8 g, 51.1 mmol, 0.06 eq.) were added and heated to 90°C. NaOtBu (245 g, 2.55 mol, 3.0 eq.) was added and stirred at 90°C for 2 hours. H was added to the reaction mixture. ２ O was added and toluene extraction was performed. The organic layer was Na ２ SO ４ The dried organic layer was filtered, and the filtered organic layer was concentrated. The concentrated residue was purified by column (hexane / CH₂). ２ Cl ２By performing the following steps (100 / 0 to 5 / 1), compound (I-1c) (104 g, 44%) was obtained as a pale yellow liquid.

[0082] (Identification of compound (I-1c)) １ H-NMR (400MHz, CDCl ３ ) δ: 2.18 (s, 3H), 2.29 (s, 3H), 5.28 (s, 1H), 6.90 (m, 3H), 7.09 (s, 1H), 7.26 (t, 2H), 7.33 (s, 1H).

[0083] (Synthesis of compound (I-1))

[0084] Under a nitrogen atmosphere, compound (I-1c) (104 g, 366 mmol, 1.0 eq.) was dissolved in toluene (1.04 L), 1,3-dimethylbutylamine (76.2 g, 753 mmol, 2.0 eq.) was added, and the mixture was heated to 80°C. Pd ２ (dba) ３ (10.4 g, 11.4 mmol, 0.03 eq.), BINAP (14.1 g, 22.6 mmol, 0.06 eq.), and NaOtBu (109 g, 1.13 mol, 3.0 eq.) were added and the mixture was stirred at 80°C for 3 hours. H was added to the reaction mixture. ２ O was added and toluene extraction was performed. The organic layer was Na ２ SO ４ The dried organic layer was filtered, and the filtered organic layer was concentrated. The concentrated residue was purified by column (hexane / CH₂). ２ Cl ２ The mixture was diluted to 1 / 1 to 1 / 1. The resulting solid was suspended and washed three times with hexane to obtain compound (I-1) (62.2 g, 56%) as a pale yellow solid.

[0085] (Identification of compound (I-1)) １ H-NMR (400MHz, CDCl ３) δ: 0.93 (d, 3H), 0.97 (d, 3H), 1.20 (d, 3H), 1.26-1.35 (m, 1H), 1.51 (t, 2H), 1.74-1.83 (m, 1H), 2.06 (s, 3H) , 2.18 (s, 3H), 3.56 (s, 1H), 5.12 (s, 1H), 6.50 (s, 1H), 6.40 (d, 2H), 7.12 (t, 1H), 6.91 (s, 1H), 7.15 (t, 2H).

[0086] Example 1-1 <Preparation of Rubber Composition and Production of Vulcanized Rubber> (First Mixing: Mixing with Laboplast Mill) Using a Laboplast Mill (manufactured by Toyo Seiki Co., Ltd., capacity: 600 mL), 100 parts by mass of natural rubber (NR) (pre-mixed TSR20) as a diene rubber, 45 parts by mass of HAF carbon black (manufactured by Cabot, Show Black N330) as a filler, 10 parts by mass of silica (manufactured by Tosoh Silica Co., Ltd., Nipsil AQ) as a filler, 3 parts by mass of stearic acid (manufactured by NOF Corporation, Camellia Stearic Acid) as a processing aid, 5 parts by mass of zinc oxide (manufactured by Seido Chemical Co., Ltd., Zinc Oxide No. 1) as a vulcanization aid, and 1 part by mass of compound (I-1) as an antioxidant were mixed to obtain a mixture. The mixing time was 5 minutes after adding each component, and the mixer rotation speed was 30 to 80 rpm. The temperature of the mixture inside the laboplast mill was 150-160°C.

[0087] (Second kneading: kneading using an open roll machine) The kneaded mixture obtained in the first kneading, containing 100 parts by mass of natural rubber, 2 parts by mass of powdered sulfur (manufactured by Tsurumi Chemical Co., Ltd., Kinka brand 5% oil sulfur) as a vulcanizing agent, and 1 part by mass of CBS (N-cyclohexyl-2-benzothiazolyl sulfenamide, manufactured by Sanshin Chemical Industry Co., Ltd., Sunceller CM-G) as a vulcanization accelerator were kneaded in an open roll machine with the roll temperature set to 60°C to obtain the sheet-like rubber composition of Example 1-1.

[0088] (Vulcanization treatment) The rubber composition obtained in the second kneading was heat-treated at 145°C for 20 minutes to obtain the vulcanized rubber of Example 1-1.

[0089] <Evaluation of Rubber Composition and Vulcanized Rubber> (Calculation of Antioxidant Elution Rate) As an indicator of the bleed rate of the antioxidant, the amount of antioxidant eluted when immersed in a solvent for a certain period of time under acceleration conditions was measured. Specifically, the sheet-like rubber composition of Example 1-1 obtained in the second kneading was punched out into a 2 cm square and immersed in methanol for 24 hours. After that, the amount of antioxidant eluted into methanol was analyzed and the value obtained by dividing it by the amount of antioxidant blended in the rubber composition (see formula below) was calculated and defined as the antioxidant elution rate. The results are shown in Table 1. Antioxidant elution rate (%) = [(Amount of antioxidant eluted into methanol) / (Amount of antioxidant blended in the rubber composition)] × 100

[0090] (Evaluation of tensile properties) The tensile strength (TS) and elongation at break (EB) of the vulcanized rubber of Example 1-1 were determined in accordance with JIS K6251:2017. The results are shown in Table 1.

[0091] Examples 1-2 and 1-3 were obtained in the same manner as in Example 1-1, except that the formulation was changed as shown in Table 1, to obtain the rubber compositions and vulcanized rubbers of Examples 1-2 and 1-3. The rubber compositions and vulcanized rubbers of Examples 1-2 and 1-3 were evaluated in the same manner as in Example 1-1. The results are shown in Table 1.

[0092] The components not used in Example 1-1 are as follows: The diene rubber, filler, spreading oil, and silane coupling agent were mixed in the first compounding step, and the vulcanization accelerator was mixed in the second compounding step. (Diene rubber) Styrene-butadiene copolymer rubber (SBR): HPR355, manufactured by ENEOS Material Co., Ltd. Butadiene rubber (BR): BR01, manufactured by ENEOS Material Co., Ltd. (Filler) Carbon black N220: Seest 6, manufactured by Tokai Carbon Co., Ltd. (Spreading oil) Aromatic process oil: Aromax 3, manufactured by ENEOS Corporation (Silane coupling agent) Si75: Si75, manufactured by Evonic Co., Ltd. (Vulcanization accelerator) DPG: Diphenylguanidine, Suncellar D, manufactured by Sanshin Chemical Industry Co., Ltd.

[0093] Comparative Example 1-1 was obtained in the same manner as in Example 1-1, except that the formulation was changed as shown in Table 1, such as changing natural rubber (NR) as the diene rubber to isoprene rubber (IR) (manufactured by ENEOS Material, IR2200). The rubber composition and vulcanized rubber of Comparative Example 1-1 were evaluated in the same manner as in Example 1-1. The results are shown in Table 1.

[0094]

[0095] As shown in Table 1, the anti-aging agent elution rates of Examples 1-1 to 1-3 were higher than those of Comparative Example 1-1. This means that the bleed rate (migration rate) of the anti-aging agent in the rubber compositions of Examples 1-1 to 1-3 was higher than that of the rubber composition of Comparative Example 1-1. These results confirm that the rubber composition of the present invention can obtain a sufficient anti-aging effect in a short time.

[0096] Example 2-1 <Preparation of Rubber Composition and Production of Vulcanized Rubber> The rubber composition and vulcanized rubber of Example 2-1 were obtained in the same manner as in Example 1-1, except that the formulation was changed as shown in Table 2. The components were the same as described above.

[0097] <Evaluation of Rubber Composition and Vulcanized Rubber> (Calculation of Anti-aging Agent Elution Rate) The sheet-like rubber composition of Example 2-1 obtained in the second kneading was punched out into a 2 cm square to obtain a sample. Next, Sample 1 after thermal degradation was prepared by exposing the sample to 100°C for 72 hours. Sample 2 after thermal degradation was prepared by exposing the sample to 100°C for 168 hours. The anti-aging agent elution rate was calculated for Sample 1 and Sample 2 after thermal degradation in the same manner as in Example 1-1. The results are shown in Table 2.

[0098] (Evaluation of tensile properties) The tensile strength (TS) and elongation at break (EB) of the vulcanized rubber of Example 2-1 were determined in accordance with JIS K6251:2017. The results are shown in Table 2.

[0099] Example 2-2 The rubber composition and vulcanized rubber of Example 2-2 were obtained in the same manner as in Example 2-1, except that the formulation was changed as shown in Table 2. The rubber composition and vulcanized rubber of Example 2-2 were evaluated in the same manner as in Example 2-1. The results are shown in Table 2.

[0100] Reference Examples 2-1 and 2-2 were obtained in the same manner as in Example 2-1, except that the formulation was changed as shown in Table 2, such as changing compound (I-1) as an antioxidant to 6PPD (Ozonon 6C, manufactured by Seiko Chemical Co., Ltd.). The rubber compositions and vulcanized rubbers of Reference Examples 2-1 and 2-2 were evaluated in the same manner as in Example 2-1. The results are shown in Table 2.

[0101]

[0102] As shown in Table 2, the elution rate of the antioxidant after thermal degradation in Examples 2-1 and 2-2 was higher than that of Reference Examples 2-1 and 2-2. Thus, it was found that the rubber compositions of Examples 2-1 and 2-2 exhibited a high bleed rate (migration rate) of the antioxidant in a short period of time, even after thermal degradation. Furthermore, these results revealed that compound (I-1) had a higher bleed rate (migration rate) than 6PPD.

Claims

1. A rubber composition comprising a diene rubber, a compound represented by formula (I), wherein the diene rubber comprises at least one selected from the group consisting of natural rubber (NR), styrene-butadiene copolymer rubber (SBR), and butadiene rubber (BR). [In formula (I), R １ R represents an alkyl group having four or more carbon atoms, which may have substituents, or an aryl group, which may have substituents. ２ and R ３ Each of these independently represents an alkyl group which may have substituents.

2. The rubber composition according to claim 1, further comprising a filler, wherein the filler comprises at least one selected from the group consisting of carbon black and silica.

3. The rubber composition according to claim 2, wherein the filler contains silica.

4. The aforementioned R １ The rubber composition according to any one of claims 1 to 3, wherein the alkyl group is a branched alkyl group having 4 to 8 carbon atoms, which may have substituents, or a cyclic alkyl group having 4 to 8 carbon atoms, which may have substituents.

5. The rubber composition according to any one of claims 1 to 3, further comprising a vulcanizing agent.

6. A vulcanized rubber obtained by vulcanizing the rubber composition described in claim 5.

7. A tire comprising a rubber member containing the vulcanized rubber described in claim 6.

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