Rubber composition, tire, and cross-linking agent

Abstract

To provide a rubber composition that ensures compatibility of fuel efficiency and resistance to crack propagation.SOLUTION: A rubber composition includes a rubber component, a compound expressed by formula (1) and / or a salt thereof, and a metal salt, wherein in formula (1), X denotes a functional group containing a nitrile oxide group, A denotes a spacer portion, and Y denotes triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, optionally substituted at a substitutable position.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber composition, a tire, and a crosslinking agent. [Background technology]

[0002] BACKGROUND ART In order to improve the durability of rubber products such as tires, rubber crawlers, and seismic isolation rubber, rubber compositions having excellent durability properties such as crack growth resistance have been required.

[0003] On the other hand, in connection with the recent trend toward global carbon dioxide emission regulations accompanying growing interest in environmental issues, there is an increasing demand for improved fuel efficiency in automobiles. In order to meet such demands, reduction in rolling resistance is also required in terms of tire performance, and generally, by applying a low heat buildup rubber composition to tires, the rolling resistance of the tires can be reduced, thereby realizing improved fuel efficiency in automobiles.

[0004] For example, Patent Document 1 discloses a rubber composition based on a diene elastomer, a reinforcing filler, a chemical crosslinking agent, and a modifier.

[0005] Patent Document 2 discloses a heavy vehicle tire comprising a tread made of a crosslinked rubber composition, said composition being based on an elastomeric matrix, a reinforcing filler, a reinforcing inorganic filler / functionalized diene elastomer binder, a chemical crosslinker, and a modifier.

[0006] Patent Document 3 discloses a process for producing a diene elastomer modified with a 1,3-dipolar compound.

[0007] Patent Document 4 discloses a nitrile oxide compound having a nitrile oxide group and an ionic functional group.

[0008] Patent Document 5 discloses a rubber composition based on a diene elastomer, a 1,3-dipolar compound, and a reinforcing filler.

[0009] Patent Documents 6 and 7 disclose rubber compositions containing a diene rubber, a filler such as carbon black or silica, and a tetrazine compound. The tetrazine compound is introduced into the main chain of the diene rubber to improve the dispersibility of the filler, thereby improving the fuel economy of the rubber composition. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Special Publication No. 2013-531726 [Patent Document 2] Special Publication No. 2016-506429 [Patent Document 3] US Patent Application Publication No. 2019 / 0315888 [Patent Document 4] International Publication No. 2022 / 244317 [Patent Document 5] US Patent Application Publication No. 2018 / 0346691 [Patent Document 6] Patent Publication No. 2021-107506 [Patent Document 7] Japanese Patent Application Publication No. 2020-176229 Summary of the Invention [Problem to be solved by the invention]

[0011] However, generally, fuel economy and crack propagation resistance of a rubber composition are in a trade-off relationship, and it is required to achieve both fuel economy and crack propagation resistance.

[0012] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a rubber composition that achieves both fuel economy and crack propagation resistance. Another object of the present invention is to provide a tire that achieves both low fuel consumption and high crack growth resistance. A further object of the present invention is to provide a crosslinking agent that, when applied to a rubber composition, can provide a rubber composition that achieves both fuel economy and crack propagation resistance. [Means for solving the problem]

[0013] The rubber composition, tire, and crosslinking agent of the present invention that solve the above problems are summarized as follows.

[0014] [1] A rubber component; A compound represented by the following formula (1) and / or a salt thereof, A rubber composition comprising: [ka] [In formula (1), X represents a functional group having a nitrile oxide group, A represents a spacer moiety, Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position. The rubber composition described in the above [1] can achieve both fuel economy and crack propagation resistance.

[0015] [2] In the formula (1), The rubber composition according to [1], wherein Y represents at least one functional group selected from the group consisting of the following formulae (4a), (4b), (4c), and (4d): [ka] [In formulas (4a), (4b), (4c), and (4d), y1 and y2 are the same or different and each represents a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S). The rubber composition described in [2] above can achieve both fuel economy and crack propagation resistance.

[0016] [3] In the formula (1), X represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b): [ka] [In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; l represents an integer of 1 to 4, and when l is 2 or more, x1 may be the same or different. In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; m represents an integer of 1 to 4, and when m is 2 or more, x2 may be the same or different; x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; n represents an integer of 1 to 2, and when n is 2, x3 may be the same or different. The rubber composition according to [1] or [2], wherein A represents a spacer moiety represented by the following formula (3): [ka] [In formula (3), a1 and a2 are the same or different and each represents at least one selected from the group consisting of CH2, NH, oxygen (O), and sulfur (S); n represents an integer of 0 to 10. The rubber composition described in [3] above can achieve both fuel economy and crack propagation resistance.

[0017] [4] The rubber composition according to any one of [1] to [3], wherein the compound represented by formula (1) and / or the salt thereof is at least one compound selected from the group consisting of the following formulae (1a) to (1n) and / or the salt thereof: [ka] [ka] [ka] The rubber composition described in [4] above can achieve both high fuel economy and high resistance to crack propagation.

[0018] [5] The rubber composition according to any one of [1] to [4], wherein the rubber component is a polymer containing a conjugated diene unit and / or an olefin unit. The rubber composition described in [5] above can achieve both fuel economy and crack propagation resistance.

[0019] [6] The rubber composition according to [5], wherein the rubber component is at least one rubber component selected from the group consisting of natural rubber, isoprene rubber, styrene-butadiene copolymer rubber, butadiene rubber, and ethylene-propylene-diene rubber (EPDM). The rubber composition described in [6] above can achieve both fuel economy and crack propagation resistance.

[0020] [7] The rubber composition according to any one of [1] to [6], further comprising carbon black and / or an inorganic filler. In this case, the reinforcing properties of the rubber composition are improved, and the crack propagation resistance is further improved.

[0021] [8] The rubber composition according to [7], wherein the carbon black and / or inorganic filler is contained in an amount of 30 to 150 parts by mass per 100 parts by mass of the rubber component. In this case, the reinforcing properties of the rubber composition are improved, and the crack propagation resistance is further improved.

[0022] [9] The rubber composition according to any one of [1] to [8], which contains 0.3 to 10 parts by mass of the compound represented by formula (1) and / or a salt thereof per 100 parts by mass of the rubber component. In this case, the fuel economy and crack propagation resistance of the rubber composition are further improved.

[0023]

[10] The rubber composition according to any one of [1] to [9], wherein the metal salt contains at least one metal selected from the group consisting of transition metals and zinc. A metal salt containing at least one metal selected from the group consisting of transition metals and zinc is likely to form a complex with the compound represented by the above formula (1).

[0024]

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

[10] , wherein the metal salt is at least one metal salt selected from the group consisting of metal halide salts, metal acrylate salts, metal methacrylate salts, and metal acetate salts. Metal halide salts, metal acrylate salts, metal methacrylate salts, and metal acetate salts are easy to handle and also easily form bonds with the compound represented by the above formula (1).

[0025]

[12] The metal salt is a metal salt other than zinc oxide, The rubber composition according to any one of [1] to

[11] , further comprising zinc oxide. In this case, the fuel economy and crack propagation resistance of the rubber composition are further improved.

[0026]

[13] A tire using the rubber composition according to any one of [1] to

[12] . The tire described in

[13] above can achieve both low fuel consumption and crack growth resistance.

[0027]

[14] A crosslinking agent comprising a compound represented by the following formula (1) and / or a salt thereof: [ka] [In formula (1), X represents a functional group having a nitrile oxide group, A represents a spacer moiety, Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position. When the crosslinking agent described in

[14] above is applied to a rubber composition, both fuel economy and crack propagation resistance can be achieved.

[0028]

[15] In the formula (1), The crosslinking agent according to

[14] , wherein Y represents at least one functional group selected from the group consisting of the following formulae (4a), (4b), (4c), and (4d): [ka] [In formulas (4a), (4b), (4c), and (4d), y1 and y2 are the same or different and each represents a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S). When the crosslinking agent described in

[15] above is applied to a rubber composition, both fuel economy and crack propagation resistance can be achieved.

[0029]

[16] In the formula (1), X represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b): [ka] [In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; l represents an integer of 1 to 4, and when l is 2 or more, x1 may be the same or different. In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; m represents an integer of 1 to 4, and when m is 2 or more, x2 may be the same or different; x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; n represents an integer of 1 to 2, and when n is 2, x3 may be the same or different. The crosslinking agent according to

[14] or

[15] , wherein A represents a spacer moiety represented by the following formula (3): [ka] [In formula (3), a1 and a2 are the same or different and each represents at least one selected from the group consisting of CH2, NH, oxygen (O), and sulfur (S); n represents an integer of 0 to 10. When the crosslinking agent described in

[16] above is applied to a rubber composition, both fuel economy and crack propagation resistance can be achieved.

[0030]

[17] The crosslinking agent according to any one of

[14] to

[16] , wherein the compound represented by formula (1) and / or the salt thereof is at least one compound selected from the group consisting of the following formulae (1a) to (1n) and / or the salt thereof: [ka] [ka] [ka] When the crosslinking agent described in

[17] above is applied to a rubber composition, both fuel economy and crack propagation resistance can be achieved. [Effects of the Invention]

[0031] According to the present invention, it is possible to provide a rubber composition that achieves both fuel economy and crack growth resistance. According to the present invention, it is possible to provide a tire that achieves both low fuel consumption and high crack growth resistance. According to the present invention, it is possible to provide a crosslinking agent that, when applied to a rubber composition, can give a rubber composition that achieves both fuel economy and crack propagation resistance. DETAILED DESCRIPTION OF THE INVENTION

[0032] The rubber composition, tire, and crosslinking agent of the present invention will be described in detail below by way of example based on embodiments thereof.

[0033] The compounds described herein may be derived in part or in whole from fossil sources, biological sources such as plant sources, recycled sources such as used tires, or a mixture of two or more of fossil, biological, and recycled sources. In this specification, the expression "a to b" in the description of a range of values means that the range is from a to b, unless otherwise specified.

[0034] <Rubber composition> The rubber composition of the present embodiment is A rubber component, A compound represented by the following formula (1) and / or a salt thereof, and a metal salt. [ka] [In formula (1), X represents a functional group having a nitrile oxide group, A represents a spacer moiety, Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position. In the above formula (1), Y preferably represents at least one functional group selected from the group consisting of the following formulae (4a), (4b), (4c), and (4d). [ka] [In formulas (4a), (4b), (4c), and (4d), y1 and y2 are the same or different and each represents a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S).

[0035] As described above, fuel economy and crack propagation resistance are usually in a trade-off relationship in rubber compositions. For example, if sulfur is compounded into a rubber composition to crosslink it and the network density of the sulfur crosslinks is reduced, the crack propagation resistance improves but the fuel economy decreases. Therefore, we have found that by compounding a specific compound (a compound represented by the above formula (1)) into the rubber composition to impart fuel economy, and by forming bonds other than sulfur crosslinks using the rubber composition, the compound represented by formula (1), and a metal salt, and utilizing the properties of those bonds, it is possible to achieve both fuel economy and crack propagation resistance. In the rubber composition of the present embodiment, the compound (crosslinking agent) having a triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl group having a functional group having a specific nitrile oxide group, a specific spacer moiety, and a specific functional group (preferably a specific heterocyclic group) imparts superior low heat buildup to the vulcanized rubber. In the rubber composition of this embodiment, the compound represented by formula (1) is added to the main chain of the rubber component. A metal salt forms a coordinate bond with the compound represented by formula (1) added to the main chain of the rubber component to form a complex. The metal salt then forms multiple coordinate bonds, resulting in crosslinking of multiple rubber components. The crosslinking by the coordinate bond is a reversible crosslink in which bonding (crosslinking) and dissociation (cleavage) are reversible. Although the bond is weak, it is estimated that the rubber composition will have sufficient strength in a low strain range even when strain is applied. The rubber composition of this embodiment can reduce hysteresis loss and improve fuel economy in a low strain region by maintaining a high network density of crosslinks due to coordination bonds. On the other hand, in a high strain region, the rubber composition of this embodiment is presumed to be able to improve crack propagation resistance by energy dissipation due to the cleavage of crosslinks due to coordination bonds, resulting in high hysteresis loss, and by energy dissipation caused by the cleavage of crosslinks (i.e., sacrificial fracture of crosslinks due to coordination bonds). Therefore, it is believed that the rubber composition of this embodiment can achieve both fuel economy and crack propagation resistance.

[0036] [Rubber component] The rubber composition of the present embodiment contains a rubber component, which allows the rubber composition to form a crosslinked structure together with the compound represented by formula (1) and the metal salt.

[0037] The rubber component is not particularly limited, but is preferably a polymer containing conjugated diene units and / or olefin units, and more preferably natural rubber (NR), synthetic diene rubber, a mixture of natural rubber and synthetic diene rubber, or a non-diene rubber other than these.

[0038] The natural rubber (NR) is preferably natural rubber latex, technically graded rubber (TSR), smoked sheet rubber (RSS), gutta percha, eucommia-derived natural rubber, guayule-derived natural rubber, Russian dandelion-derived natural rubber, or the like.

[0039] The natural rubber (NR) may include modified natural rubber obtained by modifying the natural rubber described above. The modified natural rubber is preferably an epoxidized natural rubber, a methacrylic acid-modified natural rubber, a styrene-modified natural rubber, or the like.

[0040] The synthetic diene rubber is preferably a styrene-butadiene copolymer rubber (SBR), a butadiene rubber (BR), an isoprene rubber (IR), a nitrile rubber (NBR), a chloroprene rubber (CR), an ethylene-propylene-diene terpolymer rubber (EPDM), a styrene-isoprene-styrene triblock copolymer (SIS), a styrene-butadiene-styrene triblock copolymer (SBS), or the like.

[0041] The synthetic diene rubber may contain a modified synthetic diene rubber obtained by modifying the synthetic diene rubber. The modified synthetic diene rubber preferably contains a diene rubber modified by a method such as main chain modification, single-end modification, or both-end modification. The modified functional group of the modified synthetic diene rubber is preferably an epoxy group, an amino group, an alkoxysilyl group, a hydroxyl group, or other functional group, and one or more of these functional groups may be contained in the modified synthetic diene rubber.

[0042] There are no particular limitations on the method for producing the synthetic diene rubber, and the synthetic diene rubber can be produced by emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, cationic polymerization, etc. There are also no particular limitations on the glass transition point of the synthetic diene rubber.

[0043] The cis / trans / vinyl ratio of the double bonds of the natural rubber and synthetic diene rubber is not particularly limited, and any ratio can be suitably used.

[0044] Examples of non-diene rubbers include silicone rubber, fluororubber, urethane rubber, ethylene propylene diene rubber (EPDM), and bromobutyl rubber.

[0045] The rubber component may be used alone or in combination (blended) of two or more kinds.

[0046] The rubber component is preferably at least one rubber component selected from the group consisting of natural rubber, isoprene rubber, styrene-butadiene copolymer rubber, butadiene rubber, and ethylene-propylene-diene rubber (EPDM), and more preferably at least one rubber component selected from the group consisting of natural rubber and isoprene rubber.

[0047] In the rubber composition of this embodiment, the rubber component preferably has a weight average molecular weight (Mw) of 10,000 to 3,000,000. When the weight average molecular weight (Mw) of the rubber component is 10,000 or more, the fuel economy of the rubber composition is improved, and when it is 3,000,000 or less, the workability of the rubber composition during kneading is improved. From the viewpoint of the fuel economy of the rubber composition, the weight average molecular weight (Mw) of the rubber component is more preferably 100,000 or more, and even more preferably 120,000 or more. Furthermore, from the viewpoint of the workability of the rubber composition during kneading, it is more preferably 2,000,000 or less, and even more preferably 1,800,000 or less.

[0048] The number average molecular weight (Mn) of the rubber component is preferably 500 to 3,000,000. The weight average molecular weight (Mw) and number average molecular weight (Mn) of the rubber component can be determined by gel permeation chromatography (GPC) using polystyrene as a standard substance.

[0049] There are no particular limitations on the blend ratio of the rubber components in the rubber composition, but the blend ratio of the rubber components is preferably 50 to 100 parts by mass, more preferably 75 to 100 parts by mass, of at least one rubber component selected from the group consisting of natural rubber, isoprene rubber, styrene-butadiene copolymer rubber, and butadiene rubber per 100 parts by mass of the rubber components.

[0050] [Compound represented by formula (1) and / or salt thereof] The rubber composition of the present embodiment contains a compound represented by the following formula (1) and / or a salt thereof. [ka] [In formula (1), X represents a functional group having a nitrile oxide group, A represents a spacer moiety, Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position. The compound represented by the formula (1) has a triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl group and can form a coordinate bond with a metal salt. The compound represented by the formula (1) can crosslink multiple rubber components together with the metal salt. In the present invention, the compound represented by the above formula (1) is used as a coordination field for a metal salt to form a crosslink through a coordinate bond. As a result, in the low strain region, the network density is maintained high by the crosslink through the coordinate bond, thereby improving fuel efficiency. On the other hand, in the high strain region, energy dissipation due to the cleavage of the crosslink through the coordinate bond improves crack propagation resistance.

[0051] In the above formula (1), X preferably represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b): [ka] [In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; l represents an integer of 1 to 4, and when l is 2 or more, x1 may be the same or different. In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; m represents an integer of 1 to 4, and when m is 2 or more, x2 may be the same or different; x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; n represents an integer of 1 to 2, and when n is 2, x3 may be the same or different.

[0052] The alkyl group is not particularly limited and may be linear, branched, or cyclic, and examples thereof include alkyl groups having 1 to 18 carbon atoms, preferably alkyl groups having 1 to 8 carbon atoms. Examples of the alkyl group include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, and 1-ethylpropyl groups; linear or branched alkyl groups having 5 to 18 carbon atoms, such as n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, 3-methylpentyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, 5-propylnonyl, n-tridecyl, n-tetradecyl, n-pentadecyl, hexadecyl, heptadecyl, and octadecyl groups; and cyclic alkyl groups having 3 to 8 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups.

[0053] The alkoxy group is not particularly limited and may be a linear, branched, or cyclic alkoxy group. Specific examples of the alkoxy group include linear or branched alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy, n-pentyloxy, neopentyloxy, and n-hexyloxy groups, and cyclic alkoxy groups such as cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, cycloheptyloxy, and cyclooctyloxy groups.

[0054] The aryl group is a monovalent aromatic hydrocarbon group, which may be either monocyclic or polycyclic, and may have 6 to 20 carbon atoms, such as a phenyl group, a 1-naphthyl group, a 2-naphthyl group, an anthryl group, a phenanthryl group, a pyrenyl group, an indenyl group, and an indanyl group.

[0055] Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and preferred are a chlorine atom, a bromine atom, and an iodine atom.

[0056] In the above formula (1), A represents a spacer moiety, and A is preferably a spacer moiety represented by the following formula (3). [ka] [In formula (3), a1 and a2 are the same or different and each represents at least one selected from the group consisting of CH2, NH, oxygen (O), and sulfur (S); n represents an integer of 0 to 10.

[0057] In the above formula (3), a1 and a2 are the same or different and each represents at least one selected from the group consisting of CH2, NH, oxygen element (O), and sulfur element (S), preferably at least one selected from the group consisting of CH2 and oxygen element (O).

[0058] In the above formula (3), n preferably represents an integer of 0 to 10, and more preferably represents an integer of 0 to 7.

[0059] The spacer moiety is preferably an alkylene group containing a nitrogen atom (N), an oxygen atom (O), and / or a sulfur atom (S), such as an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, or a heptamethylene group. Specific examples of the spacer moiety include -O-CH2CH2-, -O-CH2CH2CH2- (propyl ether group), -O-CH2CH2CH2CH2-, -O-CH2CH2CH2CH2-, -O-CH2CH2CH2CH2-O-, -O-CH2CH2CH2CH2-O- (butyl diether group), -O-CH2CH2CH2CH2CH2-O-, and the like.

[0060] In the above formula (1), Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position.

[0061] In formula (1), Y preferably represents at least one functional group selected from the group consisting of the following formulae (4a), (4b), (4c), and (4d). [ka] In formulae (4a), (4b), (4c), and (4d), y1 and y2 may be the same or different and each represent a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S). In the compound represented by the above formula (1), Y may have a substituent at a substitutable position, and by having at least one functional group selected from the group consisting of triazyl, pyridyl, pyridazyl, pyrazyl, and pyrimidyl, the rubber component can be crosslinked together with the metal salt.

[0062] The aryl group is a monovalent aromatic hydrocarbon group, which may be either monocyclic or polycyclic, and may have 6 to 20 carbon atoms, such as a phenyl group, a 1-naphthyl group, a 2-naphthyl group, an anthryl group, a phenanthryl group, a pyrenyl group, an indenyl group, and an indanyl group.

[0063] The alkyl group is not particularly limited and may be linear, branched, or cyclic, and examples thereof include alkyl groups having 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms. Examples of the alkyl group include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, and 1-ethylpropyl groups; linear or branched alkyl groups having 5 to 18 carbon atoms, such as n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, 3-methylpentyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, 5-propylnonyl, n-tridecyl, n-tetradecyl, n-pentadecyl, hexadecyl, heptadecyl, and octadecyl groups; and cyclic alkyl groups having 3 to 8 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups.

[0064] The alkoxy group is not particularly limited and may be a linear, branched, or cyclic alkoxy group. Specific examples of the alkoxy group include linear or branched alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy, n-pentyloxy, neopentyloxy, and n-hexyloxy groups, and cyclic alkoxy groups such as cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, cycloheptyloxy, and cyclooctyloxy groups.

[0065] The alkylthio group is not particularly limited and may be a linear, branched, or cyclic alkylthio group. Specific examples of the alkylthio group include linear or branched alkylthio groups such as methylthio, ethylthio, n-propylthio, isopropylthio, n-butylthio, tert-butylthio, n-pentylthio, neopentylthio, and n-hexylthio, and cyclic alkylthio groups such as cyclopropylthio, cyclobutylthio, cyclopentylthio, cyclohexylthio, cycloheptylthio, and cyclooctylthio.

[0066] The heterocyclic group is not particularly limited as long as it is a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S). Specific examples of heterocyclic groups containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S) include 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrazinyl, 2-pyrimidyl, 4-pyrimidyl, 5-pyrimidyl, 3-pyridazyl, 4-pyridazyl, 4-(1,2,3-triazyl), 5-(1,2,3-triazyl), 2-(1,3,5-triazyl), 3-(1,2,4-triazyl), 5-(1,2,4-triazyl), and 6-(1,2,4-triazyl). , 2-quinolyl, 3-quinolyl, 4-quinolyl, 5-quinolyl, 6-quinolyl, 7-quinolyl, 8-quinolyl, 1-isoquinolyl, 3-isoquinolyl, 4-isoquinolyl, 5-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl, 8-isoquinolyl, 2-quinoxalyl, 3-quinoxalyl, 5-quinoxalyl, 6-quinoxalyl, 7-quinoxalyl, 8-quinoxalyl, 3-cinnolyl, 4-cinnolyl, 5-cinnolyl, 6-cinnolyl, 7-cinnolyl, 8-cinnolyl, 2-quinazolyl, 4-quinazolyl quinazolyl, 5-quinazolyl, 6-quinazolyl, 7-quinazolyl, 8-quinazolyl, 1-phthalazyl, 4-phthalazyl, 5-phthalazyl, 6-phthalazyl, 7-phthalazyl, 8-phthalazyl, 1-tetrahydroquinolyl, 2-tetrahydroquinolyl, 3-tetrahydroquinolyl, 4-tetrahydroquinolyl, 5-tetrahydroquinolyl, 6-tetrahydroquinolyl, 7-tetrahydroquinolyl, 8-tetrahydroquinolyl, 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, 2-furyl, 3-furyl, 2-thienyl, 3-thiphenyl Enyl, 1-imidazolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl, 1-pyrazolyl, 3-pyrazolyl, 4-pyrazolyl, 5-pyrazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl, 3-isothiazolyl, 4-isothiazolyl, 5-isothiazolyl, 4-(1,2,3-thiadiazolyl), 5-(1,2,3-thiadiazolyl), 3-(1,2,5-thiadiazolyl), 2-(1,3,4-thiadiazolyl), 4-(1,2,3-oxadiazolyl), 5-(1,2,3-oxadiazolyl), 3-(1,2,4-oxadiazolyl), 5-(1,2,4-oxadiazolyl), 3-(1,2,5-oxadiazolyl), 2-(1,3,4-oxadiazolyl), 1-(1,2,3-triazolyl), 4-(1,2,3-triazolyl), 5-(1,2,3-triazolyl), 1-(1,2,4-triazolyl), 3-(1,2,4-triazolyl), 5-(1,2,4-triazolyl), 1-tetrazolyl, 5-tetrazolyl, 1-indolyl, 2-indolyl, 3-indolyl, 4-indolyl, 5-indolyl, 6-indolyl, 7-indolyl, 1-isoindolyl, 2-isoindolyl, 3-isoindolyl, 4-isoindolyl, 5-isoindolyl, 6-isoindolyl, 7-isoindolyl, 1-benzimidazolyl, 2-benzimidazolyl, 4-benzimidazolyl, 5-benzimidazolyl, 6-benzimidazolyl, 7- Benzimidazolyl, 2-benzofuranyl, 3-benzofuranyl, 4-benzofuranyl, 5-benzofuranyl, 6-benzofuranyl, 7-benzofuranyl, 1-isobenzofuranyl, 3-isobenzofuranyl, 4-isobenzofuranyl, 5-isobenzofuranyl, 6-isobenzofuranyl, 7-isobenzofuranyl, 2-benzothienyl, 3-benzothienyl, 4-benzothienyl, 5-benzothienyl, 6-benzothienyl, 7-benzothienyl, 2-benzoxazolyl, 4-benzo benzoxazolyl, 5-benzoxazolyl, 6-benzoxazolyl, 7-benzoxazolyl, 2-benzothiazolyl, 4-benzothiazolyl, 5-benzothiazolyl, 6-benzothiazolyl, 7-benzothiazolyl, 1-indazolyl, 3-indazolyl, 4-indazolyl, 5-indazolyl, 6-indazolyl, 7-indazolyl, 2-morpholyl, 3-morpholyl, 4-morpholyl, 1-piperazyl, 2-piperazyl, 1-piperidyl, 2-piperidyl, 3-piperidyl , 4-piperidyl, 2-tetrahydropyranyl, 3-tetrahydropyranyl, 4-tetrahydropyranyl, 2-tetrahydrothiopyranyl, 3-tetrahydrothiopyranyl, 4-tetrahydrothiopyranyl, 1-pyrrolidyl, 2-pyrrolidyl, 3-pyrrolidyl, furanyl, 2-tetrahydrofuranyl, 3-tetrahydrofuranyl, 2-tetrahydrothienyl, 3-tetrahydrothienyl, 5-methyl-3-oxo-2,3-dihydro-1H-pyrazol-4-yl group, and the like.

[0067] The compound represented by the above formula (1) and / or a salt thereof is preferably at least one compound selected from the group consisting of the following formulae (1a) to (1n) and / or a salt thereof. [ka] [ka] [ka]

[0068] The compound represented by the formula (1) above may be in the form of a salt, and the salt of the compound represented by the formula (1) above is not particularly limited and includes all kinds of salts. Examples of such salts include, but are not limited to, inorganic acid salts such as hydrochloride, sulfate, and nitrate; organic acid salts such as acetate and methanesulfonate; alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as magnesium salt and calcium salt; and ammonium salts such as dimethylammonium and triethylammonium.

[0069] The rubber composition of this embodiment preferably contains 0.01 to 50 parts by mass of the compound represented by formula (1) and / or its salt relative to 100 parts by mass of the rubber component. When the content of the compound represented by formula (1) and / or its salt is 0.01 part by mass or more relative to 100 parts by mass of the rubber component, the network density of the coordinate bond crosslinks increases, the hysteresis loss in the low strain region further decreases, and the fuel economy of the rubber composition improves. When the content is 50 parts by mass or less, a crosslinked rubber having sufficient elastomeric properties is easily obtained. The rubber composition preferably contains 0.1 part by mass or more of the compound represented by formula (1) and / or its salt relative to 100 parts by mass of the rubber component, more preferably 0.2 part by mass or more, even more preferably 0.25 part by mass or more, and most preferably 0.3 part by mass or more. The compound represented by formula (1) and / or its salt is contained in an amount of more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, and most preferably 5 parts by mass or less, per 100 parts by mass of the rubber component.

[0070] [Metal salts] The rubber composition of this embodiment contains a metal salt. The metal salt forms coordinate bonds with multiple compounds represented by the above formula (1), thereby crosslinking multiple rubber components. Here, the crosslinking by coordinate bonds is a reversible crosslink in which bonding (crosslinking) and dissociation (cleavage) are reversible, and the bond dissociation energy is relatively low. Therefore, even if the crosslinking is broken by an external stimulus, it can be reversibly restored. In the present invention, the above metal salt does not include a metal salt of the compound represented by formula (1).

[0071] The metal salt preferably contains at least one metal selected from the group consisting of transition metals and zinc, because metal salts containing transition metals and / or zinc are easily complexed with the compound represented by formula (1).

[0072] Examples of transition metals include elements in groups 7 to 11 of the periodic table. Specifically, examples of elements in Group 7 of the periodic table include manganese and rhenium. Examples of elements in Group 8 of the periodic table include iron, ruthenium, and osmium. Furthermore, examples of elements in Group 9 of the periodic table include cobalt, rhodium, and iridium. Examples of elements in Group 10 of the periodic table include nickel, palladium, and platinum. Furthermore, examples of elements in Group 11 of the periodic table include copper. Elements of Groups 7 to 11 of the periodic table tend to bond strongly with the compound represented by formula (1). Furthermore, when the metal salt contains an element of Group 8 of the periodic table, the bond with the compound represented by formula (1) tends to be even stronger. Regarding the metal ions in the metal salt, the valence of the ions is not particularly limited and can have any valence that each element can have, but is preferably divalent or greater.

[0073] The metal salt particularly preferably contains iron, zinc, copper, or nickel. Iron ions, zinc ions, copper ions, and nickel ions are likely to form particularly strong bonds with the compound represented by the above formula (1), and can form a stronger crosslinked structure. The valence of the iron ions is divalent (Fe 2+ ) or trivalent (Fe 3+ ) is preferred.

[0074] Examples of the metal salt include metal halides, metal sulfates, metal nitrates, metal acrylates, metal methacrylates, and metal acetates. Among these, at least one metal salt selected from the group consisting of metal halides, metal acrylates, metal methacrylates, and metal acetates is preferred. This is because metal halides, metal acrylates, metal methacrylates, and metal acetates are easy to handle and easily form bonds with the compound represented by formula (1) above. The form of the metal salt is not particularly limited, and may be, for example, a hydrate.

[0075] Examples of the metal halide salt include metal fluorides, metal chlorides, metal bromides, and metal iodides, and among these, metal chlorides are preferred because they are easy to handle and can easily form a bond with the compound represented by formula (1).

[0076] Specific examples of the metal salt include FeCl2, FeCl2·4H2O, FeCl3, FeCl3·6H2O, ZnCl2, CuCl, CuCl2, CuBr, zinc diacrylate, zinc dimethacrylate, Ni(CH3COO)2·4H2O, etc. The metal salt may be used alone or in combination of two or more.

[0077] The metal salt is preferably a metal salt other than a metal oxide, a metal carbonate, or a metal salt of a fatty acid having 10 or more carbon atoms. Metal salts other than a metal oxide, a metal carbonate, or a metal salt of a fatty acid having 10 or more carbon atoms are more likely to form a coordinate bond (more likely to form a complex) with the compound portion represented by formula (1) added to the main chain of the rubber component. Therefore, using metal salts other than these makes it easier to form crosslinks through coordinate bonds.

[0078] The content of the metal salt is preferably in the range of 0.1 to 30 parts by mass, more preferably 0.1 to 15 parts by mass, even more preferably 0.1 to 10 parts by mass, and particularly preferably 0.1 to 5 parts by mass, per 100 parts by mass of the rubber component. When the content of the metal salt (C) is 0.1 part by mass or more per 100 parts by mass of the rubber component, the network density of the coordinate bond crosslinks increases, the hysteresis loss in the low strain region further decreases, and the fuel economy of the rubber composition improves. Furthermore, when the content of the metal salt is 30 parts by mass or less per 100 parts by mass of the rubber component, a crosslinked rubber having sufficient elastomeric properties is easily obtained.

[0079] For example, crosslinking by coordinate bonds can be formed by mixing (kneading) the compound represented by the formula (1) with the metal salt. Here, it is preferable that the conditions for kneading, such as temperature and time, are appropriately selected depending on the rubber component, the compound represented by the formula (1), and the type and reactivity of the metal salt used.

[0080] As an example, the reaction scheme of coordinate bond crosslinking (complexation) when the compound represented by the formula (1a) above is used as the compound represented by the formula (1) above and iron chloride (FeCl2) is used as the metal salt is shown below. Note that the scheme shown here is one possible example and is not limited to this. [ka] [ka]

[0081] As shown in the above reaction scheme, in one embodiment of the present invention, a coordinate bond is formed by complexing a compound represented by formula (1) with a metal salt. Note that, although the above reaction scheme shows a mode in which a nitrogen atom of a pyridazine ring, a nitrogen atom of a pyridine ring, and an iron ion are complexed, various crosslinking modes can be used.

[0082] [Carbon black and / or inorganic filler] The rubber composition of the present embodiment preferably further contains carbon black and / or an inorganic filler, although in this specification, the inorganic filler does not include carbon black.

[0083] The rubber composition of this embodiment preferably contains 20 to 200 parts by mass of carbon black and / or inorganic filler per 100 parts by mass of the rubber component, more preferably 30 to 150 parts by mass, and even more preferably 35 to 110 parts by mass. When both carbon black and inorganic filler are compounded, the total amount of both components may be appropriately adjusted so that it falls within the above-mentioned range. From the viewpoint of improving the reinforcement of the rubber composition, it is preferably 20 parts by mass or more, and from the viewpoint of improving the tear strength, it is preferably 200 parts by mass or less.

[0084] (carbon black) Carbon black is used to improve the reinforcing properties of rubber. By including carbon black in the rubber component, it is possible to lower the electrical resistance of the rubber, thereby suppressing static electricity and improving the strength of the rubber.

[0085] There are no particular limitations on the carbon black, and various types of carbon black can be used, including, for example, commercially available carbon black and Carbon-Silica Dual Phase Filler.

[0086] The carbon black is preferably a high, medium or low structure SAF, ISAF, IISAF, N110, N134, N220, N234, N330, N339, N375, N550, HAF, FEF, GPF, SRF grade carbon black, etc. The carbon black is more preferably a SAF, ISAF, IISAF, N134, N234, N330, N339, N375, HAF, FEF grade carbon black.

[0087] The DBP (dibutyl phthalate) absorption range of the carbon black is preferably 60 cm 3 / 100g~200cm 3 / 100g, more preferably 70cm 3 / 100g~180cm 3 / 100g, particularly preferably 80cm 3 / 100g~160cm 3 / 100g. The DBP absorption amount of carbon black is the amount of DBP (dibutyl phthalate) absorbed by 100 g of carbon black, and can be measured in accordance with JIS K6217-4.

[0088] The nitrogen adsorption specific surface area (N2SA) of the carbon black is preferably 30 m 2 / g~200m 2 / g, more preferably 40m 2 / g~180m 2 / g, and particularly preferably 50m 2 / g~160m 2 / g. The nitrogen adsorption specific surface area of carbon black is measured in accordance with JIS K6217-2:2001.

[0089] In the rubber composition of this embodiment, the amount of carbon black blended is preferably 2 parts by mass to 200 parts by mass, more preferably 30 parts by mass to 130 parts by mass, and even more preferably 35 parts by mass to 100 parts by mass, per 100 parts by mass of the rubber component. The amount of carbon black blended is preferably 2 parts by mass or more from the viewpoint of ensuring antistatic performance and rubber strength performance, and is preferably 200 parts by mass or less from the viewpoint of improving tear strength.

[0090] The carbon black may be used alone or in combination of two or more kinds.

[0091] (Inorganic filler) The inorganic filler is not particularly limited, and any inorganic compound commonly used in the rubber industry can be used.

[0092] Examples of the inorganic compounds include silica; alumina (Al2O3) such as γ-alumina and α-alumina; alumina monohydrate (Al2O3·H2O) such as boehmite and diaspore; aluminum hydroxide [Al(OH)3] such as gibbsite and bayerite; and crystalline aluminosilicates containing hydrogen, alkali metals, or alkaline earth metals to compensate for the charge, such as various zeolites.

[0093] Inorganic compounds include aluminum carbonate [Al2(CO3)3], magnesium hydroxide [Mg(OH)2], magnesium oxide (MgO), magnesium carbonate (MgCO3), talc (3MgO·4SiO2·H2O), attapulgite (5MgO·8SiO2·9H2O), titanium dioxide (TiO2), and titanium dioxide (TiO 2n-1), calcium oxide (CaO), calcium hydroxide [Ca(OH)2], magnesium aluminum oxide (MgO·Al2O3), clay (Al2O3·2SiO2), kaolin (Al2O3·2SiO2·2H2O), pyrophyllite (Al2O3·4SiO2·H2O), bentonite (Al2O3·4SiO2·2H2O), aluminum silicate (Al2SiO5, Al4·3SiO4·5H2O, etc.), magnesium silicate (Mg2SiO4, MgSiO3, etc.), calcium silicate (Ca2·SiO4, etc.), aluminum calcium silicate (Al2O3·CaO·2SiO2, etc.), magnesium calcium silicate (CaMgSiO4), calcium carbonate (CaCO3), zirconium oxide (ZrO2), zirconium hydroxide [ZrO(OH)2·nH2O], zirconium carbonate [Zr(CO3)2], zinc acrylate, zinc methacrylate, etc.

[0094] The inorganic filler may be an inorganic compound whose surface is organically treated in order to improve its affinity with the rubber component.

[0095] The inorganic filler is preferably silica from the viewpoint of imparting rubber strength. The silica is preferably wet silica, dry silica, or colloidal silica, and more preferably wet silica. The silica may have its surface organically treated to improve its affinity with the rubber component.

[0096] The BET specific surface area of the silica is preferably in the range of 40 m 2 / g~350m 2 / g. Silica with a BET specific surface area in this range has the advantage of being able to achieve both rubber reinforcement and dispersibility in the rubber component. The BET specific surface area of the silica is more preferably 80 m 2 / g~300m 2 / g, more preferably 100m 2 / g~270m 2 / g, and particularly preferably 110m 2 / g~270m 2 / g. The BET specific surface area of silica is measured in accordance with ISO 5794 / 1.

[0097] Commercially available silica products include, for example, "HD165MP" (BET specific surface area = 165 m) manufactured by Quechen Silicon Chemical Co., Ltd. 2 / g), "HD115MP" (BET specific surface area = 115m 2 / g), "HD200MP" (BET specific surface area = 200m 2 / g), "HD250MP" (BET specific surface area = 250m 2 / g), and the product name "Nipsil AQ" manufactured by Tosoh Silica Corporation (BET specific surface area = 205 m 2 / g), "Nipsil KQ" (BET specific surface area = 240 m 2 / g), and the product name "Ultrasil VN3" manufactured by Degussa (BET specific surface area = 175 m 2 / g) etc.

[0098] The content of the inorganic filler is preferably 2 parts by mass to 200 parts by mass, more preferably 30 parts by mass to 130 parts by mass, and even more preferably 35 parts by mass to 100 parts by mass, per 100 parts by mass of the rubber component. When silica is used as the inorganic filler, the compounding amount of silica is preferably 2 parts by mass to 200 parts by mass, more preferably 30 parts by mass to 130 parts by mass, and even more preferably 35 parts by mass to 100 parts by mass, per 100 parts by mass of the rubber component.

[0099] The inorganic filler may be used alone or in a mixture (blend) of two or more kinds.

[0100] When the rubber composition of the present embodiment contains an inorganic filler such as carbon black and / or silica, a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a zirconate coupling agent, or the like may be compounded into the rubber composition for the purpose of further increasing the reinforcing properties of the rubber composition by the carbon black, silica, or the like, and for the purpose of further increasing the tear strength and abrasion resistance of the rubber composition.

[0101] The silane coupling agent is preferably a sulfide-based, polysulfide-based, thioester-based, thiol-based, olefin-based, epoxy-based, amino-based, alkyl-based or other silane coupling agent.

[0102] The titanate coupling agent is preferably an alkoxide-based, chelate-based, or acylate-based titanate coupling agent.

[0103] The zirconate coupling agent is preferably an alkoxide-based, chelate-based, or acylate-based zirconate coupling agent.

[0104] The silane coupling agent, titanate coupling agent, aluminate coupling agent, or zirconate coupling agent may be used alone or in a mixture (blend) of two or more kinds.

[0105] In the rubber composition of this embodiment, the amount of the silane coupling agent, titanate coupling agent, aluminate coupling agent, or zirconate coupling agent blended is preferably 0.1 to 20 parts by mass, and more preferably 3 to 15 parts by mass, per 100 parts by mass of carbon black and / or inorganic filler. By setting the amount of the silane coupling agent, titanate coupling agent, aluminate coupling agent, or zirconate coupling agent blended to 0.1 part by mass or more per 100 parts by mass of carbon black and / or inorganic filler, the effect of improving the tear strength of the rubber composition can be more suitably exhibited, and by setting the amount to 20 parts by mass or less, the cost of the rubber composition can be reduced, improving economy.

[0106] [Zinc oxide] In the rubber composition of this embodiment, when the metal salt is a metal salt other than zinc oxide, the rubber composition preferably further contains zinc oxide. When the rubber composition contains zinc oxide together with the metal salt other than zinc oxide, the fuel economy and crack propagation resistance of the rubber composition are further improved.

[0107] The content of the zinc oxide in the rubber composition is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, per 100 parts by mass of the rubber component. When the content of zinc oxide is in the range of 0.1 part by mass or more and 30 parts by mass or less, per 100 parts by mass of the rubber component, the fuel economy and crack propagation resistance of the rubber composition are further improved. The mass ratio of zinc oxide to metal salt other than zinc oxide (zinc oxide / metal salt other than zinc oxide) is preferably in the range of 0.1-50, more preferably 1-20.

[0108] [sulfur] The rubber composition of this embodiment preferably further contains sulfur. When the rubber composition contains sulfur, the rubber composition contains sulfur together with the metal salt, and thus, after crosslinking, both crosslinks formed by coordinate bonds with the metal salt and sulfur crosslinks are present in the rubber composition (Dual Cross Link: DCL). In the low strain region, the network density is maintained at a high level by both the crosslinks formed by coordinate bonds and the sulfur crosslinks, thereby further reducing hysteresis loss and further improving fuel economy. On the other hand, in the high strain region, the strength of the rubber composition (also referred to as a "crosslinked rubber composition" or "crosslinked rubber") is improved and crack propagation resistance is further improved by the presence of sulfur crosslinks in addition to energy dissipation due to the cleavage of crosslinks formed by coordinate bonds.

[0109] The amount of sulfur in the rubber composition is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, and preferably 30 parts by mass or less, more preferably 10 parts by mass or less, per 100 parts by mass of the rubber component. When the amount of sulfur is 0.1 part by mass or more, per 100 parts by mass of the rubber component, the network density due to sulfur is improved, and fuel economy is further improved. When the amount of sulfur (D) is 30 parts by mass or less, per 100 parts by mass of the rubber component, a crosslinked rubber with sufficient elastomeric properties is easily obtained.

[0110] In the rubber composition of the present embodiment, the mass ratio of the sulfur to the metal salt (sulfur / metal salt) is preferably 0.1 to 10. When the mass ratio of the sulfur to the metal salt (sulfur / metal salt) is 0.1 to 10, the balance between fuel economy and crack propagation resistance of the rubber composition becomes better. From the viewpoint of the balance between fuel economy and crack propagation resistance of the rubber composition, the mass ratio of the sulfur to the metal salt (sulfur / metal salt) is more preferably in the range of 0.1 to 8, and even more preferably in the range of 0.1 to 6.

[0111] In the rubber composition of the present embodiment, the mass ratio of the sulfur to the metal salt other than zinc oxide (sulfur / metal salt other than zinc oxide) is preferably 0.1 to 10. Therefore, the rubber composition of one preferred embodiment of the present invention comprises a rubber component, a compound represented by the above formula (1), a metal salt other than zinc oxide, and sulfur, and the mass ratio of the sulfur to the metal salt other than zinc oxide (sulfur / metal salt other than zinc oxide) is 0.1 to 10.

[0112] [Organic peroxide] The rubber composition of this embodiment preferably further contains an organic peroxide. By including an organic peroxide in the rubber composition together with the metal salt, the rubber composition after crosslinking contains crosslinks due to coordinate bonds of the metal salt and crosslinked structures (e.g., C-C bonds) resulting from the organic peroxide. In the low strain region, the crosslinks due to coordinate bonds and the crosslinked structures resulting from the organic peroxide maintain a high network density, thereby further reducing hysteresis loss and improving fuel economy. Meanwhile, in the high strain region, the crack propagation resistance is further improved due to the energy dissipation caused by the cleavage of crosslinks due to coordinate bonds and the presence of crosslinked structures resulting from the organic peroxide.

[0113] The organic peroxide is not particularly limited, but examples thereof include tert-butyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, dicumyl peroxide, di-tert-butyl peroxide, di-tert-hexyl peroxide, diisopropylbenzene hydroperoxide, tert-butylcumyl peroxide, di(2-tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, perbenzoic acid, benzoyl peroxide, 1,1-bis(1,1-dimethylethylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethyl ... ,1-bis(tert-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-hexylperoxy)cyclohexane, 2,2-bis(4,4-di-(tert-butylperoxy)cyclohexyl)propane, n-butyl-4,4-di-(tert-butylperoxy)valerate, tert-butyl peroxylaurate, tert-butylperoxy-2-ethylhexanate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, tert-hexylperoxy-2-ethylhexanoate, tert-butylperoxy-2-ethylhexanoate, tert-butyl peroxyacetate, cyclohexanone peroxide, acetylacetone peroxide, diisopropyl peroxydicarbonate, di(4-tert-butylcyclohexyl)peroxydicarbonate, and the like. These organic peroxides may be used alone or in combination of two or more.

[0114] The content of the organic peroxide in the rubber composition is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and preferably 30 parts by mass or less, more preferably 20 parts by mass or less, per 100 parts by mass of the rubber component. When the content of the organic peroxide is 0.1 part by mass or more, per 100 parts by mass of the rubber component, the network density of the crosslinked structure resulting from the organic peroxide is improved, further improving fuel economy. Furthermore, when the content of the organic peroxide is 30 parts by mass or less, per 100 parts by mass of the rubber component, a crosslinked rubber with sufficient elastomeric properties is easily obtained.

[0115] The mass ratio of the organic peroxide to sulfur (sulfur / organic peroxide) is preferably in the range of 0.003 to 300, and more preferably in the range of 0.01 to 100.

[0116] [Other ingredients] The rubber composition of this embodiment may contain the above-mentioned rubber component, the compound represented by the above formula (1) and / or its salt, metal salt, carbon black and / or inorganic filler, zinc oxide, sulfur, organic peroxide, etc., as well as compounding agents commonly used in the rubber industry, such as softeners, stearic acid, wax, antioxidants, adhesion inhibitors (fatty acid metal salts), vulcanization accelerators, etc., which may be appropriately selected and compounded within a range that does not impair the object of the present invention. Commercially available products can be suitably used as these compounding agents.

[0117] Examples of the vulcanization accelerator include sulfenamide vulcanization accelerators, guanidine vulcanization accelerators, thiazole vulcanization accelerators, thiuram vulcanization accelerators, and dithiocarbamate vulcanization accelerators. Among these, sulfenamide vulcanization accelerators are preferred. These vulcanization accelerators may be used alone or in combination of two or more. The content of the vulcanization accelerator is not particularly limited, and is preferably in the range of 0.1 to 5 parts by mass, more preferably 0.3 to 3 parts by mass, per 100 parts by mass of the rubber component.

[0118] [Method of manufacturing rubber composition] The rubber composition of the present embodiment is not particularly limited, but can be produced, for example, by blending various components appropriately selected as necessary with a rubber component, a compound represented by the above formula (1) and / or a salt thereof, and a metal salt, and then kneading, heating, extruding, etc.

[0119] The conditions for the kneading are not particularly limited, and various conditions such as the input volume of the kneading device, the rotation speed of the rotor, the ram pressure, the kneading temperature, the kneading time, the type of kneading device, etc. can be appropriately selected depending on the purpose. Examples of the kneading device include a Banbury mixer, an intermix, a kneader, a roll, etc. that are usually used for kneading rubber compositions.

[0120] The conditions for the heat-in are not particularly limited, and various conditions such as the heat-in temperature, heat-in time, and heat-in device can be appropriately selected depending on the purpose. Examples of the heat-in device include a heat-in roll mill typically used for heat-in of rubber compositions.

[0121] The extrusion conditions are not particularly limited, and various conditions such as extrusion time, extrusion speed, extrusion device, and extrusion temperature can be appropriately selected depending on the purpose. Examples of the extrusion device include an extruder typically used for extruding rubber compositions. The extrusion temperature can be appropriately determined.

[0122] The method for producing the rubber composition preferably includes the steps of: a step (1) of mixing a rubber component and a compound represented by formula (1) and / or a salt thereof to prepare a masterbatch (MB); a step (2) of mixing components such as carbon black and / or an inorganic filler with the MB obtained in the step (step (1)) of preparing the master batch, and then kneading the mixture to prepare an unvulcanized rubber composition; The method includes a step (step (3)) of mixing a vulcanizing agent (such as sulfur) and a metal salt with the unvulcanized rubber composition obtained in the step (step (2)) of preparing the unvulcanized rubber composition, followed by kneading. The rubber composition of this embodiment can be obtained by the above-described method for producing a rubber composition.

[0123] The contents explained in the section on the rubber composition can be applied to the rubber component, the compound represented by formula (1), and / or its salt, metal salt, etc. used in the method for producing the rubber composition.

[0124] The rubber composition can also be produced by simultaneously carrying out the steps (1) and (2). That is, the method for producing the rubber composition includes the steps of mixing and kneading a rubber component, a compound represented by formula (1) and / or a salt thereof, and components such as carbon black and / or an inorganic filler to prepare an unvulcanized rubber composition; The manufacturing method may include a step (step (3)) of mixing a vulcanizing agent (such as sulfur) and a metal salt with the unvulcanized rubber composition obtained in the step of preparing the unvulcanized rubber composition, and then kneading the mixture.

[0125] (Step (1) (Preparation of MB)) In step (1), a rubber component and a compound represented by formula (1) and / or a salt thereof are mixed to prepare a masterbatch (MB).

[0126] In step (1), the compounding amount of the compound represented by formula (1) and / or its salt is 0.01 to 50 parts by mass, preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass, even more preferably 0.25 to 5 parts by mass, and particularly preferably 0.3 to 3 parts by mass, relative to 100 parts by mass of the rubber component.

[0127] The kneading temperature in step (1) is preferably 60° C. to 190° C., more preferably 70° C. to 160° C., and even more preferably 80° C. to 150° C. By adjusting the kneading temperature to 60° C. to 190° C., the reaction proceeds smoothly and deterioration of the rubber can be suppressed.

[0128] The kneading time in step (1) is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 60 seconds to 7 minutes. By adjusting the kneading time to 10 seconds to 20 minutes, the reaction proceeds smoothly and productivity can be improved.

[0129] (Process (2)) In step (2), raw material components including carbon black and / or inorganic filler are added to the MB obtained in step (1), and if necessary, antioxidants, wax, stearic acid, etc. are added, followed by kneading to prepare an unvulcanized rubber composition.

[0130] In the kneading method, all of the components may be kneaded at once, or the components may be added in portions and kneaded depending on the purpose of viscosity adjustment, etc. In the kneading method, the kneading operation may be repeated to uniformly disperse the components.

[0131] Regarding the kneading temperature in step (2), the upper limit of the temperature of the mixture is preferably 100 to 190°C, more preferably 130 to 175°C, and even more preferably 110 to 170°C.

[0132] The kneading time in step (2) is preferably from 10 seconds to 20 minutes, more preferably from 30 seconds to 10 minutes, and even more preferably from 1 minute to 8 minutes. When proceeding from step (2) to step (3), the mixture is preferably cured so that the maximum temperature of the mixture is 60°C or less.

[0133] (Step (3)) In step (3), a vulcanizing agent (such as sulfur) and a metal salt are added to the mixture (unvulcanized rubber composition) obtained in step (2), and zinc oxide, a vulcanization accelerator, etc. are added as needed, and mixed to prepare an unvulcanized rubber composition. Step (3) is the final stage of kneading.

[0134] Step (3) is preferably carried out under heating conditions, and the heating temperature is preferably 60°C to 120°C, more preferably 65°C to 100°C.

[0135] The mixing (or kneading) time in step (2) is preferably from 10 seconds to 20 minutes, more preferably from 30 seconds to 10 minutes, and even more preferably from 60 seconds to 5 minutes. When proceeding from step (3) to the vulcanization step, the mixture is preferably kneaded so that the maximum temperature of the mixture is 70°C or less.

[0136] (Vulcanization process) The production of the rubber composition may include a vulcanization step. In the vulcanization process, it is preferable to mix a vulcanizing agent (sulfur, etc.) with the rubber composition (unvulcanized rubber composition), and then vulcanize the mixture by heating (150°C x 25 minutes) using a vulcanization press to obtain a vulcanized rubber composition.

[0137] (Addition of other compounding agents) In the method for producing a rubber composition according to the present embodiment, various compounding ingredients such as antioxidants, waxes, stearic acid, zinc oxide, vulcanization accelerators, etc. may be added as needed in step (2) and / or step (3). The other compounding ingredients may be added in either step (2) and / or step (3), or may be added separately in steps (2) and (3).

[0138] [Uses of rubber compositions] The rubber composition of the present embodiment can be used for various rubber members, including, but not limited to, tires, vibration-proof rubber, vibration-isolating rubber, and belts such as conveyor belts.

[0139] <Tires> The tire of the present embodiment is preferably a tire using the rubber composition of the present embodiment. The tire uses the rubber composition that achieves both fuel economy and crack growth resistance, and therefore achieves both fuel economy and crack growth resistance.

[0140] The application site of the rubber composition of the present invention in the tire of this embodiment is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include the tread, base tread, sidewall, side reinforcing rubber, and bead filler.

[0141] The tire can be manufactured by a conventional method. For example, components typically used in tire manufacturing, such as a carcass layer, a belt layer, and a tread layer, each composed of an unvulcanized rubber composition and / or cords, are laminated on a tire-building drum in this order, and the drum is removed to form a green tire. The green tire is then heated and vulcanized in a conventional manner to manufacture a desired tire (e.g., a pneumatic tire). Examples of the gas to be filled into the tire include normal air or air with an adjusted oxygen partial pressure, and inert gases such as nitrogen, argon, and helium.

[0142] <Crosslinking agent> The crosslinking agent of the present embodiment contains a compound represented by the following formula (1) and / or a salt thereof. [ka] [In formula (1), X represents a functional group having a nitrile oxide group, A represents a spacer moiety, Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position.

[0143] In the above formula (1), Y preferably represents at least one functional group selected from the group consisting of the following formulae (4a), (4b), (4c), and (4d). [ka] [In formulas (4a), (4b), (4c), and (4d), y1 and y2 are the same or different and each represents a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S).

[0144] In formula (1), X preferably represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b): [ka] [In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; l represents an integer of 1 to 4, and when l is 2 or more, x1 may be the same or different. In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; m represents an integer of 1 to 4, and when m is 2 or more, x2 may be the same or different; x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; n represents an integer of 1 to 2, and when n is 2, x3 may be the same or different.

[0145] In the above formula (1), A preferably represents a spacer moiety represented by the following formula (3). [ka] [In formula (3), a1 and a2 are the same or different and each represents at least one selected from the group consisting of CH2, NH, oxygen (O), and sulfur (S); n represents an integer of 0 to 10. The compound represented by formula (1) and / or a salt thereof is preferably at least one compound selected from the group consisting of the following formulae (1a) to (1n) and / or a salt thereof. [ka] [ka] [ka]

[0146] The compound represented by formula (1) and / or a salt thereof contained in the crosslinking agent of the present embodiment is the same as that described above in the section [Compound represented by formula (1) and / or a salt thereof].

[0147] The crosslinking agent of this embodiment is a compound having a triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl group, which may have a functional group having a nitrile oxide group, a specific spacer moiety, and a substituent at a substitutable position, in a rubber component. This allows vulcanized rubber containing the crosslinking agent to exhibit superior low heat buildup. Tires manufactured using this crosslinking agent in a rubber component can improve fuel economy. Furthermore, in a rubber composition containing the crosslinking agent of this embodiment, the crosslinking agent of this embodiment is added to the main chain of the rubber component, and a metal salt forms a coordinate bond with the crosslinking agent portion of this embodiment added to the main chain of the rubber component to form a complex. The metal salt then forms multiple coordinate bonds, thereby crosslinking multiple rubber components. Here, the crosslinking by the coordinate bond is a reversible crosslink in which bonding (crosslinking) and dissociation (cleavage) are reversible. Furthermore, although the bond is weak, it is estimated that the rubber composition has sufficient strength in a low strain range even when subjected to strain. In a tire manufactured using this crosslinking agent, the network density of the crosslinks due to coordination bonds is maintained high in the low strain region, thereby reducing hysteresis loss and improving fuel economy. On the other hand, in a tire manufactured using this crosslinking agent, the crosslinks due to coordination bonds are cleaved in the high strain region, resulting in high hysteresis loss, and it is presumed that the energy dissipation caused by the cleavage of the crosslinks (i.e., sacrificial fracture of the crosslinks due to coordination bonds) can improve crack propagation resistance. Therefore, it is believed that a tire manufactured by applying the crosslinking agent of this embodiment to the rubber component can achieve both low fuel consumption and crack propagation resistance.

[0148] Among the triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl groups which may have a substituent at the substitutable position, preferred are triazyl, pyridyl, pyridazyl, or pyrimidyl groups having a specific substituent, and more preferred are pyridazyl or pyridyl groups having a specific heterocyclic group. [Example]

[0149] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0150] <Production of Compounds A and B> The structures of the intermediates and compounds produced in this production example were determined using a nuclear magnetic resonance (NMR) measurement device (manufactured by Bruker, model: AVANCE500 (frequency 500 MHz)). 1 The 1H-NMR was measured (solvent: deuterated dimethyl sulfoxide (DMSO-d6) or deuterated chloroform (CDCl3)) and determined. (Production Example 1: Production of Compound A) [ka] -Process 1- To a solution of 113.6 g of 2-hydroxy-1-naphthaldehyde and 81.2 g of 5-chloro-1-pentyne in 300 mL of DMF (N,N-dimethylformamide), 109.5 g of potassium carbonate was added and the mixture was reacted at 100° C. for 24 hours. After cooling the reaction solution, 1500 mL of water was added to stop the reaction, and the precipitated solid was filtered, washed with hexane, and dried to obtain 157.2 g of intermediate 1 (yield 99%). 1H-NMR (500MHz, DMSO-d6, δppm): 10.81(1H, s), 9.11(1H, m), 8.28(1H, m), 7.95(1H, s), 7.65(1H, m), 7.63(1H, m), 7.46(1H, m), 4.38(2H, t), 2.85(1H, t), 2.42(2H, m), 2.02(2H, m) -Process 2- To a solution of 157.2 g of intermediate 1 in 450 mL of toluene, 141.7 g of 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine was added and refluxed for 24 hours. After cooling the reaction solution, the precipitated solid was filtered, washed with toluene, and dried to obtain 224.2 g of intermediate 2 (yield 91%). 1 H-NMR(500MHz, DMSO-d6,δppm): 10.63(1H, s), 9.11(1H, m), 8.74(1H, m), 8.65(1H, s), 8.61(2H, m), 8.23(1H, m), 8.05(1H, m), 7.97(2H, m), 7.92(1H, m), 7.65(1H, m), 7.60(1H, m), 7.55(3H, m), 4.32(2H, t), 3.26(2H, m), 2.14(2H, m) -Process 3- 244.2 g of Intermediate 2 was added to 800 mL of methanol, and 114.0 g of hydroxylamine hydrochloride was added to the solution, followed by a reaction for 24 hours at 60° C. After cooling the reaction solution, 1600 mL of water was added to terminate the reaction, and the precipitated solid was filtered, washed with water, and dried to obtain 248.5 g of Intermediate 3 (yield 99%). 1 H-NMR (500MHz, DMSO-d6, δppm): 11.29(1H, s), 8.85(1H, m), 8.70(1H, m), 8.60(1H, m), 8.59(3H, m), 8.00(5H, m), 7.57(2H, m), 7.40(3H, m), 4.21(2H, m), 3.23(2H, m), 2.10(2H, m) -Process 4- To a solution of 22.4 g of Intermediate 3 in 100 mL of methylene chloride, 7.26 g of N-chlorosuccinimide was added while cooling in an ice bath. The mixture was warmed to room temperature and allowed to react for 24 hours. 500 mL of saturated aqueous sodium bicarbonate solution was added to the reaction mixture to terminate the reaction, and the methylene chloride layer was separated, washed with water, and then concentrated. The resulting solid was washed with acetone and dried to obtain 20.1 g of the desired compound A (yield 90%). 1 H-NMR(500MHz, CDCl3,δppm): 8.73(1H, m), 8.66(2H, m), 8.57(1H, s), 8.14(1H, m), 7.96(1H, m), 7.85(4H, m), 7.61(1H, m), 7.45(1H, m), 7.38(1H, m), 7.32(1H, m), 7.17(1H, m), 4.24(2H, t), 3.68(2H, m), 2.33(2H, m)

[0151] (Production Example 2: Production of Compound B) [ka] -Process 1- To a solution of 51.7 g of 2-hydroxy-1-naphthaldehyde and 194.3 g of 1,4-dibromobutane in 450 mL of acetone, 82.9 g of potassium carbonate was added and refluxed for 24 hours. After cooling the reaction solution, 500 mL of water was added to stop the reaction, and the precipitated solid was filtered. The filtrate was extracted with methylene chloride, the solvent was distilled off, and the residue was purified by silica gel chromatography to obtain 69.5 g of Intermediate 4 (yield 75%). 1 H-NMR(500MHz, CDCl3,δppm): 10.92(1H, s), 9.27(1H, m), 8.05(1H, m), 7.77(1H, m), 7.63(1H, m), 7.43(1H, m), 7.26(1H, m), 4.28(2H, t), 3.52(2H, t), 2.11(4H, m) -Process 2- To a solution of 40.6 g of intermediate 4 and 31.4 g of 2,6-bis(2-pyridyl)-4(1H)-pyridone in 132 mL of DMF, 20.9 g of potassium carbonate was added and the mixture was reacted for 24 hours at 90° C. After cooling the reaction solution, 1000 mL of water was added to stop the reaction, and the precipitated solid was filtered, washed with diethyl ether, and dried to obtain 53.8 g of intermediate 5 (yield 90%). 1 H-NMR(500MHz, CDCl3,δppm): 10.94(1H, s), 9.27(1H, m), 8.67(2H, m), 8.61(2H, m), 8.00(3H, m), 7.84(2H, m), 7.76(1H, m), 7.62(1H, m), 7.33(1H, m), 7.26(3H, m), 4.34(4H, m), 2.14(4H, m) -Process 3- 8.8 g of hydroxylamine hydrochloride was added to a solution of 30.2 g of intermediate 5 in 127 mL of methanol, and the mixture was allowed to react at room temperature for 24 hours. 1000 mL of water was added to the reaction solution to stop the reaction, and the precipitated solid was filtered, washed with methanol, and dried to obtain 29.6 g of intermediate 6 (yield 95%). 1 H-NMR(500MHz, CDCl3,δppm): 10.77(1H, s), 8.84(1H, m), 8.71(2H, m), 8.61(2H, m), 8.52(1H, m), 8.03(2H, s), 7.86(3H, m), 7.70(1H, m), 7.50(1H, m), 7.35(3H, m), 7.26(1H, m), 4.38(2H, m), 4.22(2H, m), 2.12(4H, m) -Process 4- To a solution of 16.4 g of Intermediate 6 in 400 mL of methylene chloride, 241.6 g of a 1% aqueous solution of sodium hypochlorite was added dropwise while cooling in an ice bath. The mixture was warmed to room temperature and reacted for 24 hours. The methylene chloride layer was separated, washed with water, and then concentrated. The resulting solid was washed with diethyl ether and dried to obtain 14.7 g of the target compound B (yield 90%). 1H-NMR(500MHz, CDCl3,δppm): 8.67(2H, m), 8.60(2H, m), 8.02(2H, s), 7.95(2H, m), 7.82(3H, m), 7.60(1H, m), 7.42(1H, m), 7.33(2H, m), 7.26(1H, m), 4.34(4H, m), 2.15(4H, m)

[0152] <Production of Rubber Composition> [Process (1) (Masterbatch (MB) production process)] A rubber component (isoprene rubber), a compound represented by formula (1) (compound A or compound B), and an antioxidant were mixed in the ratios (parts by mass) shown in Tables 1 and 2 below under the conditions (mixing temperature, mixing speed, etc.) described below to prepare a masterbatch (MB).

[0153] (Comparative Examples 1 to 4, Examples 1 to 3, and Examples 6 to 8) Mixing temperature: 140℃ Mixing speed: 30rpm Mixing time: 6 minutes Discharge temperature: 144℃

[0154] (Examples 4, 5, 9 and 10) Mixing temperature: 140℃ Mixing speed: 30rpm Mixing time: 8 minutes Discharge temperature: 144℃

[0155] [Process (2)] Each MB obtained in step (1) was mixed with each of the components shown in step (2) in Tables 1 and 2 in the proportions (parts by mass) shown in Tables 1 and 2 below, and kneaded in a Banbury mixer. The mixture was then cured until the temperature of the mixture reached 60°C or less, to produce an unvulcanized rubber composition.

[0156] [Process (3)] Each component shown in step (3) of Tables 1 and 2 was added to the unvulcanized rubber composition obtained in step (2) in the proportions (parts by mass) shown in Tables 1 and 2 below, and the mixture was kneaded while adjusting the maximum temperature of the mixture to 70°C or less.

[0157] The unvulcanized rubber composition obtained through steps (1) to (3) was vulcanized by heating at 145°C for 25 minutes using a vulcanization press to obtain a vulcanized rubber composition (rubber composition after vulcanization).

[0158] <Evaluation of Rubber Composition> The rubber compositions obtained were measured by the methods described below.

[0159] (1) Evaluation of fuel efficiency Test specimens were prepared from the obtained rubber compositions, and a viscoelasticity test was conducted using an "ARES-G2" manufactured by TA Instruments under conditions of a frequency of 15 Hz, a shear strain of 3%, and a temperature of 50°C to measure the loss tangent (tanδ) of the rubber compositions. In Table 1, the evaluation results are normalized by the reciprocal of the formulation data of each example, with the formulation data of Comparative Example 1 set as the control (index value 100), and in Table 2, the formulation data of Comparative Example 3 set as the control (index value 100) and normalized by the reciprocal of the formulation data of each example. A larger index value indicates a smaller tanδ and better fuel economy.

[0160] (2) Evaluation of crack propagation resistance Ring test pieces with an inner diameter of 8 mm and an outer diameter of 12 mm were prepared from the obtained rubber composition. Using an Instron tensile tester, they were stretched to 100% at a rate of 100 mm / min and then returned to their initial length at the same rate. The area of the loop drawn in the strain-stress curve at this time was taken as the hysteresis loss at 200% elongation. The larger this value, the more energy can be dissipated and the more difficult crack propagation becomes, so it was used as an index of crack propagation resistance. Comparative Example 1 in Table 1 and Comparative Example 3 in Table 2 were used as controls (index value 100), and the values were normalized by the compounding data of each example. The larger the index value, the larger the loop area drawn in the strain-stress curve and the better the crack resistance.

[0161] The formulations and evaluation results of the rubber compositions of Examples 1 to 10 and Comparative Examples 1 to 4 are shown in Tables 1 and 2 below. In Tables 1 and 2, if neither the fuel economy nor the crack growth resistance index is less than 90, and the sum of the fuel economy and crack growth resistance indexes is greater than that of the control, it is considered that performance has improved and that both fuel economy and crack growth resistance have been achieved.

[0162] [Table 1]

[0163] [Table 2]

[0164] *1 Isoprene rubber (rubber component): Manufactured by ENEOS Materials, product name "IR2200" *2 Compound A represented by formula (1): Compound represented by the following formula (1a) (Production Example 1) [ka] *3 Antioxidant: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine *4 Carbon black: N234 grade *5 Wax: Rhin Chemie Rheinau, product name "Antilux 111" *6 Vulcanization accelerator: N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) *7 Iron chloride: FeCl2·4H2O, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. *8 ZDMA: Zinc dimethacrylate, manufactured by Cray Valley, product name "DYMALINK 708" *9 Compound B represented by formula (1): Compound represented by the following formula (1b) (Production Example 2) [ka]

[0165] It can be seen from Tables 1 and 2 that the rubber composition has both fuel economy and crack growth resistance. At the same time, it can also be seen that when the compound represented by the above formula (1) is applied to the rubber composition, both fuel economy and crack growth resistance can be achieved. [Industrial Applicability]

[0166] According to the present invention, it is possible to provide a rubber composition that achieves both fuel economy and crack growth resistance.

Claims

1. A rubber component, A compound represented by the following formula (1) and / or a salt thereof, A rubber composition comprising: 【Chemical 1】 [In formula (1), X represents a functional group having a nitrile oxide group, A represents a spacer moiety, Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position.

2. In the formula (1), 2. The rubber composition according to claim 1, wherein Y represents at least one functional group selected from the group consisting of the following formulae (4a), (4b), (4c), and (4d): 【Chemistry 2】 [In formulas (4a), (4b), (4c), and (4d), y1 and y2 are the same or different and each represents a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S).

3. In the formula (1), X represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b): 【Chemistry 3】 [In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; l represents an integer of 1 to 4, and when l is 2 or more, x1 may be the same or different. In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; m represents an integer of 1 to 4, and when m is 2 or more, x2 may be the same or different; x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; n represents an integer of 1 or 2, and when n is 2, x3 may be the same or different. The rubber composition according to claim 1, wherein A represents a spacer moiety represented by the following formula (3): 【Chemistry 4】 [In formula (3), a1 and a2 are the same or different and each represents CH 2 , NH, oxygen element (O), and sulfur element (S), n represents an integer of 0 to 10.

4. The compound represented by formula (1) and / or the salt thereof is at least one compound selected from the group consisting of the following formulas (1a) to (1n) and / or the salt thereof. The rubber composition according to claim 1. 【Chemistry 5】 【Chemistry 6】 【Chemistry 7】

5. The rubber composition according to claim 1, wherein the rubber component is a polymer containing conjugated diene units and / or olefin units.

6. The rubber composition according to claim 5, wherein the rubber component is at least one rubber component selected from the group consisting of natural rubber, isoprene rubber, styrene-butadiene copolymer rubber, butadiene rubber, and ethylene-propylene-diene rubber (EPDM).

7. The rubber composition according to claim 1, further comprising carbon black and / or an inorganic filler.

8. The rubber composition according to claim 7, wherein the carbon black and / or inorganic filler is contained in an amount of 30 to 150 parts by mass per 100 parts by mass of the rubber component.

9. The rubber composition according to claim 1, comprising 0.3 to 10 parts by mass of the compound represented by formula (1) and / or the salt thereof per 100 parts by mass of the rubber component.

10. The rubber composition according to claim 1 , wherein the metal salt contains at least one metal selected from the group consisting of transition metals and zinc.

11. 2. The rubber composition according to claim 1, wherein the metal salt is at least one metal salt selected from the group consisting of metal halide salts, metal acrylate salts, metal methacrylate salts, and metal acetate salts.

12. the metal salt is a metal salt other than zinc oxide, The rubber composition according to claim 1 , further comprising zinc oxide.

13. A tire using the rubber composition according to any one of claims 1 to 12.

14. A crosslinking agent comprising a compound represented by the following formula (1) and / or a salt thereof: 【Chemistry 8】 [In formula (1), X represents a functional group having a nitrile oxide group, A represents a spacer moiety, Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position.

15. In the formula (1), The crosslinking agent according to claim 14, wherein Y represents at least one functional group selected from the group consisting of the following formulae (4a), (4b), (4c), and (4d): 【Chemistry 9】 [In formulas (4a), (4b), (4c), and (4d), y1 and y2 are the same or different and each represents a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S).

16. In the formula (1), X represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b): 【Chemistry 10】 [In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; l represents an integer of 1 to 4, and when l is 2 or more, x1 may be the same or different. In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; m represents an integer of 1 to 4, and when m is 2 or more, x2 may be the same or different; x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom; n represents an integer of 1 or 2, and when n is 2, x3 may be the same or different. The crosslinking agent according to claim 14 , wherein A represents a spacer moiety represented by the following formula (3): 【Chemistry 11】 [In formula (3), a1 and a2 are the same or different and each represents CH 2 , NH, oxygen element (O), and sulfur element (S), n represents an integer of 0 to 10.

17. The crosslinking agent according to claim 14, wherein the compound represented by formula (1) and / or the salt thereof is at least one compound selected from the group consisting of the following formulae (1a) to (1n) and / or a salt thereof: 【Chemistry 12】 【Chemistry 13】 【Chemistry 14】

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