Rubber composition and tire

Abstract

To provide a rubber composition and a tire having improved overall performance of abrasion resistant performance and chipping resistant performance.SOLUTION: A rubber composition contains a rubber component containing isoprene rubber and styrene-butadiene, carbon black, silica, and at least one compound selected from the group consisting of a compound represented by formula (1) below and a compound represented by formula (2) below. (In the formula (1), A11 is a monovalent cyclic hydrocarbon group having at least one polar group, and R11 and R12 are each independently at least one selected from the group consisting of a hydrogen atom, an acyl group, an amide group, an alkyl group, a cycloalkyl group, and an aryl group). (In the formula (2), A21 is a monovalent cyclic hydrocarbon group having at least one polar group, and R21 is a divalent hydrocarbon group).SELECTED DRAWING: None

Description

[Technical field]

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

[0002] 2. Description of the Related Art Tires are required to have various performance characteristics. For example, heavy duty tires used for trucks, buses, etc. are required to have performance characteristics such as wear resistance and chipping resistance, and improvements in these characteristics are desired. Summary of the Invention [Problem to be solved by the invention]

[0003] An object of the present invention is to solve the above problems and to provide a rubber composition and a tire having improved overall performance in terms of abrasion resistance and chipping resistance. [Means for solving the problem]

[0004] The present invention relates to a rubber composition comprising a rubber component including an isoprene-based rubber and a styrene-butadiene rubber, carbon black, silica, and at least one selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2): [ka] (In the formula, A 11 R is a monovalent cyclic hydrocarbon group having at least one polar group. 11 and R 12 are each independently at least one selected from the group consisting of a hydrogen atom, an acyl group, an amido group, an alkyl group, a cycloalkyl group, and an aryl group. [ka] (In the formula, A 21 R is a monovalent cyclic hydrocarbon group having at least one polar group. 21 is a divalent hydrocarbon group.

[0005] 2. The rubber composition according to claim 1, wherein the content of the silica is less than 50% by mass based on 100% by mass of the total of the silica and the carbon black.

[0006] The amount of the carbon black is preferably 30 to 80 parts by mass based on 100 parts by mass of the rubber component.

[0007] The total amount of the compounds represented by the formulas (1) and (2) is preferably 30.0 parts by mass or less based on 100 parts by mass of the rubber component.

[0008] It is preferable that the content of the isoprene-based rubber is 50 to 90 mass % and the content of the styrene-butadiene rubber is 5 to 40 mass % in 100 mass % of the rubber component.

[0009] The content of the butadiene rubber in 100% by mass of the rubber component is preferably 5 to 30% by mass.

[0010] The carbon black has a nitrogen adsorption specific surface area of ​​135 m 2 It is preferable that the carbon black contains at least 100% by mass of carbon black.

[0011] The polar group preferably contains at least one type selected from the group consisting of a hydroxy group, an amino group, and a nitro group.

[0012] R 11 and the above R 12 is preferably at least one selected from the group consisting of a hydrogen atom and an alkyl group.

[0013] It is preferable that the content of the carbon black relative to 100 parts by mass of the rubber component and the total amount of styrene in 100% by mass of the rubber component satisfy the following formula: Carbon black content / total styrene content > 4.0

[0014] It is preferable that the content of the silica relative to 100 parts by mass of the rubber component and the total amount of styrene in 100% by mass of the rubber component satisfy the following formula: Silica content / total styrene content <7.0

[0015] The present invention relates to a tire having a tread constructed from the above rubber composition.

[0016] The tire is preferably a heavy duty tire. Effect of the Invention

[0017] According to the present invention, the rubber composition contains a rubber component including an isoprene-based rubber and a styrene-butadiene rubber (SBR), carbon black, silica, and at least one of the compounds represented by the formulas (1) and (2), and therefore the overall performance of the abrasion resistance and chipping resistance is improved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The rubber composition of the present invention contains a rubber component including an isoprene-based rubber and a styrene-butadiene rubber (SBR), carbon black, silica, and at least one of the compounds represented by the formulas (1) and (2), thereby improving the overall performance of the abrasion resistance and chipping resistance.

[0019] The reason why such an effect is obtained is not entirely clear, but is presumed to be as follows. For the purpose of improving chipping resistance, the use of carbon black and silica in combination or blending isoprene rubber with SBR in components such as the tread of heavy-duty tires has been studied. However, it is generally known that when silica is blended into such a blend rubber, the silica tends to be unevenly distributed in the isoprene rubber. Therefore, by blending the compounds represented by the above formulas (1) to (2) into a blend containing isoprene rubber, SBR, carbon black, and silica, the substituents (A 11 , A 21) interacts with carbon black, while -NH-NR 11 R 12 , -NH=NR 21 It is believed that the structure shown in the formula (1) enhances the affinity with rubber. As a result, carbon black is dispersed in the rubber preferentially over silica, and when silica is dispersed in the rubber by a subsequent coupling reaction, it is believed that the omnipresence of silica in the isoprene-based rubber is inhibited, and carbon black and silica are uniformly dispersed in each rubber phase and bonded to the polymer. Therefore, it is presumed that the rubber composition has improved filler dispersion in this way, and thus improves chipping resistance as well as abrasion resistance, improving the overall performance of these properties. In addition, by using a rubber component containing isoprene rubber and SBR in combination with carbon black, silica, and the compound represented by the formulas (1) and (2), these components act synergistically to synergistically improve the overall performance of the wear resistance and chipping resistance. In particular, by using carbon black in combination with the compound represented by the formulas (1) and (2), the overall performance of the wear resistance and chipping resistance is synergistically improved.

[0020] The rubber composition includes a rubber component containing an isoprene-based rubber and an SBR. Examples of isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of NR include SIR20, RSS♯3, TSR20, and other rubbers that are common in the tire industry. Examples of IR include IR2200 and other rubbers that are common in the tire industry. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), and other rubbers. Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more. Among these, NR is preferred.

[0021] The content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, particularly preferably 70% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0022] The SBR is not particularly limited, and for example, emulsion polymerized styrene butadiene rubber (E-SBR), solution polymerized styrene butadiene rubber (S-SBR), etc. can be used. These may be used alone or in combination of two or more kinds.

[0023] The styrene content of SBR is preferably 5.0% by mass or more, more preferably 10.0% by mass or more, even more preferably 15.0% by mass or more, particularly preferably 20.0% by mass or more, and is preferably 60.0% by mass or less, more preferably 40.0% by mass or less, even more preferably 35.0% by mass or less, particularly preferably 30.0% by mass or less. Within the above ranges, the effect tends to be better obtained. In this specification, the styrene content of the rubber component is 1 It is calculated by H-NMR measurement.

[0024] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., and the like can be used.

[0025] The SBR may be unmodified SBR or modified SBR. The modified SBR may be any SBR having a functional group that interacts with fillers such as silica and carbon black, and examples thereof include terminal-modified SBR (terminal-modified SBR having the above-mentioned functional group at the terminal) in which at least one terminal of SBR has been modified with a compound (modifier) ​​having the above-mentioned functional group, main-chain-modified SBR having the above-mentioned functional group in the main chain, main-chain-terminal-modified SBR having the above-mentioned functional group in the main chain and at least one terminal (for example, main-chain-terminal-modified SBR having the above-mentioned functional group in the main chain and at least one terminal modified with the above-mentioned modifier), and terminal-modified SBR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or epoxy group introduced therein. These may be used alone or in combination of two or more kinds.

[0026] Examples of the functional group include functional groups containing at least one atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a silicon atom. These may be used alone or in combination of two or more kinds.

[0027] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, and an epoxy group. These functional groups may have a substituent. Among them, an amino group (preferably an amino group in which a hydrogen atom of an amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferred because they provide a more suitable effect.

[0028] The content of SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, particularly preferably 20% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, particularly preferably 30% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0029] The rubber composition may contain other rubber components in addition to the isoprene-based rubber and SBR. Examples of other rubber components include diene rubbers other than the above. Examples of other diene rubbers include butadiene rubber (BR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Examples of rubber components other than the above include butyl rubber and fluororubber. These may be used alone or in combination of two or more. Among these, BR is preferred. This allows the effect to be obtained more favorably.

[0030] The BR is not particularly limited, and examples of the BR that can be used include high cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, BR synthesized using a rare earth catalyst (rare earth BR), etc. These may be used alone or in combination of two or more.

[0031] The cis content of BR is preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more, with no particular upper limit. When it is within the above range, the effect tends to be better. In this specification, the cis content of the rubber component can be measured by infrared absorption spectroscopy.

[0032] The BR may be either unmodified or modified. The modified BR may be a modified BR having a functional group similar to that of the modified SBR introduced therein.

[0033] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, etc. can be used.

[0034] The amount of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 10% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0035] The rubber composition contains carbon black. Examples of carbon black include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. These may be used alone or in combination of two or more kinds.

[0036] The nitrogen adsorption specific surface area (N2SA) of carbon black is 50m 2 / g or more is preferable, and 100m 2 / g or more is more preferable, and 120m 2 / g or more is more preferable, and 135m 2 / g or more is particularly preferable. 2 / g or less is preferable, and 200m 2 / g or less is more preferable, and 160m 2 / g or less is more preferable, and 150m 2 Within the above range, there is a tendency that the effect is more favorable. The nitrogen adsorption specific surface area of ​​carbon black can be determined in accordance with JIS K6217-2:2001.

[0037] The reason why such an effect is obtained is not entirely clear, but is presumed to be as follows. As described above, the dispersibility of carbon black in rubber is improved by compounding the compounds of the formulas (1) and (2). Therefore, the N2SA of carbon black is adjusted to a predetermined range, particularly N2SA135m. 2 It is believed that even when carbon black with a relatively high specific surface area, such as 1.0 μm / g or more, is blended, the carbon black and silica can be uniformly dispersed in each rubber phase and bonded to the polymer. Therefore, for example, even when carbon black with a relatively high specific surface area is blended, it is presumed that the abrasion resistance is improved without significant concerns about heat buildup, and the overall performance of chipping resistance and abrasion resistance is improved.

[0038] As carbon black, for example, products manufactured by Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shinnikka Carbon Co., Ltd., Columbia Carbon Company, etc. can be used.

[0039] The amount of carbon black per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 30 parts by mass or more, particularly preferably 40 parts by mass or more, and particularly preferably 50 parts by mass or more, and is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 90 parts by mass or less, and particularly preferably 80 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0040] The reason why such an effect is obtained is not entirely clear, but is presumed to be as follows. As described above, by compounding according to the formulas (1) and (2), the dispersibility of carbon black in rubber is improved, so that even when the amount of carbon black is adjusted to a predetermined range, particularly when a relatively large amount of 30 to 80 parts by mass is compounded, it is considered that carbon black and silica can be uniformly dispersed in each rubber phase and bonded to the polymer. Therefore, for example, even when the amount of carbon black is 30 to 80 parts by mass, it is presumed that the wear resistance is improved without significant concerns about heat generation, and the overall performance of chipping resistance and wear resistance is improved.

[0041] The rubber composition contains silica. The silica is not particularly limited, and examples thereof include dry process silica (anhydrous silicic acid) and wet process silica (hydrated silicic acid). These may be used alone or in combination of two or more. Among them, wet process silica is preferred because it has a large number of silanol groups.

[0042] As the silica, for example, products manufactured by Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0043] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 50 m 2 / g or more, more preferably 100m 2 / g or more, more preferably 150m 2 / g or more, particularly preferably 170m 2 / g or more. In addition, the N2SA is preferably 300m 2 / g or less, more preferably 250m 2 Within the above range, there is a tendency for the effect to be better obtained. The N2SA of silica can be measured in accordance with ASTM D3037-81.

[0044] The amount of silica per 100 parts by mass of the rubber component is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0045] The silica content in the total of 100% by mass of silica and carbon black is preferably less than 85% by mass, more preferably less than 50% by mass, even more preferably less than 35% by mass, and particularly preferably 20% by mass or less. The lower limit is not particularly limited, but is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 10% by mass or more. In addition, within the above range, the effect tends to be better obtained.

[0046] The reason why such an effect is obtained is not entirely clear, but is presumed to be as follows. By adjusting the silica content to less than a certain amount, particularly to less than 50% by mass, the silica content is low, so that when silica is dispersed in rubber by coupling reaction, the omnipresence of silica in isoprene-based rubber is inhibited, and carbon black and silica are uniformly dispersed in each rubber phase and can be bonded to polymer.Therefore, for example, when the silica content is adjusted to less than 50% by mass, it is presumed that even if the amount of carbon black is greater than the amount of silica, the wear resistance is improved without significant concerns about heat generation, and the overall performance of chipping resistance and wear resistance is improved.

[0047] When the rubber composition contains silica, it is preferable that the rubber composition contains a silane coupling agent together with the silica. The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamate, Examples of the silyl silane include sulfide-based silanes such as bamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based silanes such as 3-mercaptopropyl trimethoxysilane, 2-mercaptoethyl triethoxysilane, and NXT and NXT-Z manufactured by Momentive; vinyl-based silanes such as vinyl triethoxysilane and vinyl trimethoxysilane; amino-based silanes such as 3-aminopropyl triethoxysilane and 3-aminopropyl trimethoxysilane; glycidoxy-based silanes such as γ-glycidoxypropyl triethoxysilane and γ-glycidoxypropyl trimethoxysilane; nitro-based silanes such as 3-nitropropyl trimethoxysilane and 3-nitropropyl triethoxysilane; and chloro-based silanes such as 3-chloropropyl trimethoxysilane and 3-chloropropyl triethoxysilane. These may be used alone or in combination of two or more. Among these, sulfide-based and mercapto-based compounds are preferred because they provide better effects.

[0048] As the silane coupling agent, for example, products available from Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry, Azumax, Dow Corning Toray, etc. can be used.

[0049] The content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, based on 100 parts by mass of silica. When the content is within the above range, the effect tends to be better.

[0050] The rubber composition may contain fillers other than carbon black and silica. As the other fillers, materials known in the rubber field can be used, and examples of such fillers include inorganic fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica; and poorly dispersible fillers.

[0051] The total amount of the filler per 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, particularly preferably 60 parts by mass or more, and is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, even more preferably 100 parts by mass or less, particularly preferably 90 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0052] The rubber composition includes at least one compound selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2).

[0053] [ka] (In the formula, A 11 R is a monovalent cyclic hydrocarbon group having at least one polar group. 11 and R 12 are each independently at least one selected from the group consisting of a hydrogen atom, an acyl group, an amido group, an alkyl group, a cycloalkyl group, and an aryl group.

[0054] [ka] (In the formula, A 21 R is a monovalent cyclic hydrocarbon group having at least one polar group. 21 is a divalent hydrocarbon group.

[0055] A in the above formula (1) 11 is a monovalent cyclic hydrocarbon group, and the monovalent cyclic hydrocarbon group has at least one polar group.

[0056] Here, in this specification, "cyclic hydrocarbon group" refers to a hydrocarbon group containing a cyclic structure, including both alicyclic hydrocarbon groups and aromatic hydrocarbon groups. "Alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure as a cyclic structure and does not contain an aromatic ring structure, including both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups. However, it is not necessary to be composed of only an alicyclic structure, and it may contain a chain structure as a part. "Aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a cyclic structure, including both monocyclic aromatic hydrocarbon groups and polycyclic aromatic hydrocarbon groups. However, it is not necessary to be composed of only an aromatic ring structure, and it may contain a chain structure or an alicyclic structure as a part. "Number of ring members" means the number of atoms that constitute the cyclic structure, and in the case of a polycycle, it means the number of atoms that constitute the polycycle.

[0057] A 11 The monovalent cyclic hydrocarbon group in the formula (A) may be an aliphatic ring group or an aromatic ring group. 11 In the formula, the number of rings in the aliphatic ring group is not particularly limited, but is usually 1 or more, preferably 2 or more, and usually 6 or less, preferably 4 or less, and more preferably 3 or less. The number of carbon atoms in the aliphatic ring group is usually 4 or more, preferably 6 or more, more preferably 8 or more, and preferably 40 or less, more preferably 30 or less, even more preferably 20 or less, and particularly preferably 15 or less. Within the above ranges, the effect tends to be better.

[0058] Specific examples of the aliphatic ring in the aliphatic ring group include a cyclohexane ring, a cycloheptane ring, a cyclodecane ring, a cyclododecane ring, a norbornane ring, an isobornane ring, an adamantane ring, a cyclododecane ring, etc. These may be used alone or in combination of two or more kinds.

[0059] A 11 In the above, the number of rings in the aromatic ring group is not particularly limited, but is usually 1 or more, preferably 2 or more, and usually 10 or less, preferably 5 or less. Examples of the aromatic ring group include aromatic hydrocarbon ring groups and aromatic heterocyclic groups. The number of carbon atoms in the aromatic ring group is usually 4 or more, preferably 5 or more, more preferably 6 or more, and preferably 30 or less, more preferably 20 or less, and even more preferably 15 or less. Within the above range, the effect tends to be better.

[0060] Specific examples of the aromatic ring in the aromatic ring group include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, a fluorene ring, etc. In addition, the aromatic ring also includes an aromatic heterocycle in an aromatic heterocyclic group, which may be a single ring or a condensed ring. Examples of aromatic heterocyclic groups include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, cinnoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, and azulene ring. These may be used alone or in combination of two or more.

[0061] A11 has at least one polar group, but the type of polar group is not particularly limited, and examples thereof include amino group, nitrile group, ammonium group, amide group (-CONH2), hydrazo group (-NH-NH-R; R is an alkyl group or aryl group), azo group (-N=NR; R is an alkyl group or aryl group), hydroxy group, carboxy group, acyl group (-CO-R; R is an alkyl group or aryl group), epoxy group, oxycarbonyl group (-CO-OR; R is an alkyl group or aryl group), alkoxysilyl group, alkylamino group, and nitro group. Here, the alkyl group of the hydrazo group, azo group, carbonyl group, oxycarbonyl group, alkoxysilyl group, and alkylamino group is preferably a linear or branched alkyl group having 1 to 6 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, and an n-hexyl group. The aryl group in the hydrazo group, azo group, carbonyl group, and oxycarbonyl group preferably has a carbon number of 6 to 10. Specific examples include a phenyl group, a naphthyl group, etc. Among these polar groups, from the viewpoint of obtaining a better effect, a hydroxy group, an amino group, and a nitro group are preferred, and a hydroxy group is more preferred.

[0062] The reason why such an effect is obtained is not entirely clear, but is presumed to be as follows. The substituent (A) having a cyclic structure having a polar group in the compound represented by the formulas (1) to (2) 11 , A 21 It is believed that by selecting a hydroxyl group, an amino group, a nitro group, or the like as the polar group of the filler, the interaction with the carbon black is improved, and as a result, the carbon black is dispersed in the rubber preferentially over the silica, the omnipresence of the silica in the isoprene-based rubber is further inhibited, and the carbon black and silica are uniformly dispersed in each rubber phase and bonded to the polymer. Therefore, it is presumed that in the rubber composition, since the filler dispersion is improved in this way, the abrasion resistance as well as the chipping resistance are improved, and the overall performance of these performances is further improved.

[0063] R in the above formula (1) 11 and R 12 are each independently a hydrogen atom, an acyl group (-CO-R; R is an alkyl or aryl group), an amide group (-CONH2), an alkyl group, a cycloalkyl group, or an aryl group, but R 11 and R 12 The alkyl group of the alkyl group and the acyl group represented by the formula (I) preferably has 1 to 6 carbon atoms and may be linear or branched. Specific examples include methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, and n-hexyl groups. The cycloalkyl group preferably has 5 to 10 carbon atoms and specific examples include cycloheptyl, cyclohexyl, cyclooctyl, and cyclodecanyl groups. R 11 and R 12 The aryl group represented by the formula (I) and the aryl group of the acyl group preferably have 6 to 10 carbon atoms, and specific examples thereof include a phenyl group and a naphthyl group. Among these, from the viewpoint of obtaining a better effect, R 11 and R 12 is preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.

[0064] The reason why such an effect is obtained is not entirely clear, but is presumed to be as follows. R of the compounds represented by the formulas (1) to (2) 11 , R 12 , N.R. 21 By selecting a hydrogen atom, an alkyl group, etc., -NH-NR 11 R 12 , -NH=NR 21It is considered that the structure shown in the following formula enhances the affinity with rubber, and as a result, carbon black is preferentially dispersed in rubber rather than silica, and the omnipresence of silica in isoprene-based rubber is further inhibited, and carbon black and silica are uniformly dispersed in each rubber phase and can be bonded to polymer. Therefore, it is presumed that the rubber composition has improved filler dispersion in this way, and therefore has improved chipping resistance as well as wear resistance, and the overall performance of these properties is further improved.

[0065] A in the above formula (2) 21 is a monovalent cyclic hydrocarbon group, and the monovalent cyclic hydrocarbon group has at least one polar group.

[0066] A 21 Examples of the monovalent cyclic hydrocarbon group in A include 11 The monovalent cyclic hydrocarbon group in the above formula is preferably the same as the monovalent cyclic hydrocarbon group in the above formula.

[0067] A 21 has at least one polar group, but the type of the polar group is not particularly limited. 11 The polar groups in the above formula are preferably the same as those in the above formula.

[0068] R in the above formula (2) 21 R is a divalent hydrocarbon group, and the divalent hydrocarbon group may contain at least one heteroatom. Examples of the heteroatom include an oxygen atom, a sulfur atom, and a nitrogen atom. 21 Examples of the divalent hydrocarbon group include a divalent saturated or unsaturated aliphatic group, a cycloalkylene group, and an arylene group.

[0069] R 21 The divalent saturated or unsaturated aliphatic group may be linear or branched. The divalent saturated or unsaturated aliphatic group preferably has 1 to 30 carbon atoms, more preferably has 1 to 12 carbon atoms, further preferably has 1 to 8 carbon atoms, and particularly preferably has 1 to 5 carbon atoms.

[0070] R21 The cycloalkylene group preferably has a carbon number of 5 to 10. Specific examples include a cycloheptylene group, a cyclohexylene group, a cyclooctylene group, a cyclooctylene group, and a cyclodecanylene group.

[0071] R 21 The arylene group preferably has a carbon number of 5 to 10. For example, there is a cyclopentadienyl group.

[0072] Among the compounds represented by the formulas (1) and (2), from the viewpoint of obtaining a better effect, the compound represented by the formula (1) is preferred, and the compound represented by the following formula (1-1) is more preferred.

[0073] [ka] (In the formula, R 111 ~R 116 are each independently at least one selected from the group consisting of a hydrogen atom, a hydroxyl group, an amino group, and a nitro group.

[0074] R in the above formula (1-1) 111 ~R 116 From the viewpoint of obtaining a better effect, R is preferably a hydrogen atom or a hydroxyl group. 111 ~R 114 At least one of R is preferably a hydroxy group, an amino group, or a nitro group, and more preferably a hydroxy group. 115 ~R 116 At least one of the groups is preferably a hydroxy group, an amino group or a nitro group, and more preferably a hydroxy group.

[0075] Specific examples of suitable compounds represented by the formulas (1) and (2) include, for example, (1S,2S)-2,3-dihydro-1,5-dihydroxy-1H-indene-2-carboxylic acid hydrazide, (1S,2R)-2,3-dihydro-1-hydroxy-1H-indene-2-carboxylic acid hydrazide, (1S,2S)-2,3-dihydro-1-hydroxy-1H-indene-2-carboxylic acid hydrazide, (1S,2R)-2,3-dihydro-2-hydroxy-1H-indene-1-carboxylic acid hydrazide, 1,2,3,4-tetrahydro-1-oxo-2-naphthalenecarboxylic acid hydrazide, (1S,2R)-1,2,3,4-tetrahydro-1,6-dihydroxy-2-naphthalenecarboxylic acid hydrazide, 1H-pyrazole-1-carboxylic acid, Examples include 2,2-dimethylhydrazide.

[0076] Examples of the compounds represented by the formulas (1) and (2) include 2,4-dihydroxybenzohydrazide, 3,5-dihydroxybenzohydrazide, 2,3-dihydroxybenzohydrazide, 2,5-dihydroxybenzohydrazide, 2,6-dihydroxybenzohydrazide, 3,4-dihydroxybenzohydrazide, 3,6-dihydroxybenzohydrazide, 4,5-dihydroxybenzohydrazide, 4,6-dihydroxybenzohydrazide, 5,6-dihydroxybenzohydrazide, 2,3,4-trihydroxybenzohydrazide, 2,3,5-trihydroxybenzohydrazide, 2,3,6-trihydroxybenzohydrazide, 2,4,5-trihydroxybenzohydrazide, 2,4,6-trihydroxybenzohydrazide, and 2,5,6-trihydroxybenzohydrazide. The compounds represented by the formulas (1) and (2) may be used alone or in combination of two or more kinds.

[0077] The compounds represented by the formulas (1) and (2) can be synthesized by known methods, for example, by the method described in JP-A-2019-508407.

[0078] The compounds represented by the formulas (1) and (2) may be commercially available products, for example, products available from Tokyo Chemical Industry Co., Ltd., Fujifilm Wako Pure Chemical Industries, Ltd., etc.

[0079] The total amount (total content) of the compounds represented by the formulas (1) and (2) is preferably 0.2 parts by mass or more, more preferably 0.4 parts by mass or more, and even more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 30.0 parts by mass or less, more preferably 10.0 parts by mass or less, even more preferably 5.0 parts by mass or less, particularly preferably 2.0 parts by mass or less, and most preferably 1.0 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0080] The reason why such an effect is obtained is not entirely clear, but is presumed to be as follows. It is believed that by adjusting the total amount of the compounds represented by the formulas (1) and (2) to a predetermined range, particularly to 30.0 parts by mass or less, slippage during mixing of materials can be prevented, and carbon black and silica can be uniformly dispersed in each rubber phase and bonded to the polymer. Therefore, for example, when the total amount of the compounds represented by the formulas (1) and (2) is adjusted to 30.0 parts by mass or less, it is believed that the overall performance of chipping resistance and wear resistance will be improved.

[0081] The rubber composition may contain a plasticizer. In this specification, the plasticizer is a material that imparts plasticity to a rubber component, and is a concept that includes liquid plasticizers (plasticizers that are liquid (liquid) at 25° C.) and solid plasticizers (plasticizers that are solid at 25° C.). Specifically, it is a component that can be extracted from a rubber composition using acetone. These may be used alone or in combination of two or more kinds.

[0082] The total content of the plasticizers (the total content of the liquid plasticizer and the solid plasticizer) is preferably 30 parts by mass or less, more preferably 5 parts by mass or less, and further preferably 2 parts by mass or less, per 100 parts by mass of the rubber component, and may be 0 parts by mass. When it is within the above range, the effect tends to be better obtained. The plasticizer content includes the amount of oil contained in rubber (oil-extended rubber) and sulfur (oil-containing sulfur).

[0083] Examples of liquid plasticizers include oils, liquid polymers (diene-based, olefin-based, ester-based, etc.), liquid resins, essential oils derived from natural products such as turpentine oil, and ester-based plasticizers. Examples of solid plasticizers include solid resins that are solid at 25°C and are generally used in the tire industry. These may be used alone or in combination of two or more. Among these, the liquid plasticizer is preferably at least one selected from the group consisting of oils, liquid polymers, and liquid resins, more preferably oils, and even more preferably process oils.

[0084] The oil is not particularly limited, and may be a conventionally known oil, such as paraffin-based process oil, aromatic process oil, naphthene-based process oil, low PCA (polycyclic aromatic) process oil such as TDAE and MES, vegetable oil, and mixtures thereof. These may be used alone or in combination of two or more. Among them, paraffin-based process oil is preferred.

[0085] As the oil, for example, products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., etc. can be used.

[0086] Examples of liquid resins include terpene-based resins (including terpene phenol resins and aromatic modified terpene resins) that are liquid at 25°C, rosin resins, styrene-based resins, C5-based resins, C5C9-based resins, coumarone-indene-based resins (including simple coumarone and indene resins), olefin-based resins, polyurethane resins, and acrylic resins.

[0087] Examples of the liquid resin that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0088] Examples of liquid diene polymers include liquid styrene butadiene copolymers (liquid SBR), liquid butadiene polymers (liquid BR), liquid isoprene polymers (liquid IR), liquid styrene isoprene copolymers (liquid SIR), liquid styrene butadiene styrene block copolymers (liquid SBS block polymers), liquid styrene isoprene styrene block copolymers (liquid SIS block polymers), etc. that are liquid at 25° C. The ends or main chains of these may be modified with polar groups.

[0089] As the liquid diene polymer, for example, products available from Sartomer Co., Ltd., Kuraray Co., Ltd., etc. can be used.

[0090] The content of the liquid plasticizer (preferably oil) is preferably 30 parts by mass or less, more preferably 5 parts by mass or less, and further preferably 2 parts by mass or less, per 100 parts by mass of the rubber component, and may be 0 part by mass. When the content is within the above range, the effect tends to be better. The plasticizer content includes the amount of oil contained in rubber (oil-extended rubber) and sulfur (oil-containing sulfur).

[0091] As the solid plasticizer, solid resins that are usually used as tire compounds can be used. Specific examples include terpene resins, rosin resins, styrene resins, olefin resins, C5 resins, C9 resins, C5 / C9 resins, coumarone resins, indene resins, coumarone-indene resins, acrylic resins, and urethane resins. These may be used alone or in a mixture of two or more kinds, and the resin itself may be a copolymer of monomer components of multiple origins.

[0092] Examples of resins that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0093] The softening point of the resin is preferably 30° C. or higher, more preferably 50° C. or higher, even more preferably 80° C. or higher, and is preferably 200° C. or lower, more preferably 160° C. or lower, even more preferably 140° C. or lower, and particularly preferably 120° C. or lower. By keeping it within the above range, the above-mentioned effects tend to be more suitably obtained. In this specification, the softening point of a resin is the temperature at which the ball drops when the softening point as specified in JIS K 6220-1:2001 is measured using a ring and ball softening point tester.

[0094] The content of the solid plasticizer (preferably a resin) is preferably 30 parts by mass or less, more preferably 5 parts by mass or less, and further preferably 2 parts by mass or less, per 100 parts by mass of the rubber component, and may be 0 part by mass. When the content is within the above range, the effect tends to be better.

[0095] The rubber composition preferably contains sulfur. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. These may be used alone or in combination of two or more kinds.

[0096] As sulfur, for example, products from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanritsu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0097] The amount of sulfur is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.8 parts by mass or more, based on 100 parts by mass of the rubber component. The amount is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, even more preferably 5 parts by mass or less, particularly preferably 3 parts by mass or less, and most preferably 2 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0098] The rubber composition preferably contains a vulcanization accelerator. Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazolylsulfenamide, Nt-butyl-2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more. Among these, sulfenamide-based vulcanization accelerators are preferred.

[0099] As the vulcanization accelerator, for example, products manufactured by Kawaguchi Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Rhein Chemie AG, etc. can be used.

[0100] The content of the vulcanization accelerator is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better.

[0101] The rubber composition preferably contains stearic acid. As the stearic acid, any known stearic acid can be used, for example, products available from NOF Corp., Kao Corp., Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., and the like.

[0102] The content of stearic acid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0103] The rubber composition may contain zinc oxide. As the zinc oxide, any known zinc oxide can be used, for example, products available from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., and the like.

[0104] The amount of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component. Within the above range, the effect tends to be better obtained.

[0105] The rubber composition may contain an antioxidant. Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine. Examples of the antioxidant include p-phenylenediamine antioxidants such as quinolinone; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis, tris, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. These antioxidants may be used alone or in combination of two or more. Among them, p-phenylenediamine antioxidants and quinoline antioxidants are preferred, and p-phenylenediamine antioxidants are more preferred.

[0106] As the antioxidant, for example, products available from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, etc. can be used.

[0107] The content of the antioxidant is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component. Within the above range, the effect tends to be better.

[0108] The rubber composition may contain a wax. The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax, natural waxes such as vegetable wax and animal wax, synthetic waxes such as polymers of ethylene, propylene, etc. These may be used alone or in combination of two or more kinds.

[0109] As the wax, for example, products available from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used.

[0110] The amount of the wax is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, based on 100 parts by mass of the rubber component. The amount is preferably 10 parts by mass or less, more preferably 7 parts by mass or less. Within the above range, the effect tends to be better.

[0111] In addition to the above components, the rubber composition may contain additives commonly used in the tire industry, such as vulcanizing agents other than sulfur (e.g., organic crosslinking agents, organic peroxides), etc. The content of each of these components is preferably 0.1 parts by mass or more and preferably 200 parts by mass or less per 100 parts by mass of the rubber component.

[0112] In order to obtain a greater effect, it is desirable for the rubber composition to have the carbon black content (parts by mass) per 100 parts by mass of the rubber component and the total styrene amount (% by mass) in the rubber component satisfy the following formula: Carbon black content / total styrene content > 4.0 The carbon black content / total styrene content is preferably 6.0 or more, more preferably 8.0 or more, even more preferably 9.0 or more, and particularly preferably 10.0 or more. The upper limit is preferably 20.0 or less, more preferably 17.0 or less, even more preferably 15.0 or less, and particularly preferably 13.0 or less. By keeping it within the above range, it is considered that the proportion of carbon black that can be dispersed without being affected by steric hindrance due to the styrene part in the rubber increases, making it possible to easily distribute the carbon black into the isoprene-based rubber phase.

[0113] In order to obtain a greater effect, it is desirable for the rubber composition to have the silica content (parts by mass) per 100 parts by mass of the rubber component and the total styrene amount (% by mass) in the rubber component satisfy the following formula: Silica content / total styrene content <7.0 The silica content / total styrene content is preferably 6.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, and particularly preferably 2.5 or less. The lower limit is preferably 0.5 or more, more preferably 1.0 or more, even more preferably 1.2 or more, and particularly preferably 1.4 or more. By keeping it within the above range, it is believed that silica can easily reach double bonds other than styrene parts in the rubber component, and the reinforcing effect of silica can be easily obtained.

[0114] The total styrene content in the rubber component is preferably 2.0% by mass or more, more preferably 3.0% by mass or more, even more preferably 4.0% by mass or more, particularly preferably 4.5% by mass or more, and is preferably 15.0% by mass or less, more preferably 10.0% by mass or less, even more preferably 8.0% by mass or less, particularly preferably 6.0% by mass or less. If it is within the above range, it is considered that it is easy to distribute carbon to the isoprene-based rubber layer and at the same time, reinforcement by silica is easily obtained.

[0115] Here, the total amount of styrene in the rubber component is the total content of styrene parts contained in the total amount of rubber component (unit: mass%), and can be calculated by Σ(content of each rubber component × amount of styrene in each rubber component / 100). For example, in a case where 100% by mass of rubber component contains 85% by mass of SBR with styrene content: 40% by mass, 5% by mass of SBR with styrene content: 25% by mass, and 10% by mass of BR with styrene content: 0% by mass, the total amount of styrene in the rubber component is 35.25% by mass (=85×40 / 100+5×25 / 100+10×0 / 100).

[0116] The amount of styrene in each rubber component can be measured by a nuclear magnetic resonance (NMR) method. In addition, the total styrene amount in the rubber component is calculated according to the above-mentioned formula in the examples of this specification, but it may be analyzed from the tire using, for example, a pyrolysis gas chromatograph mass spectrometer (Py-GC / MS) or the like.

[0117] The rubber composition can be produced, for example, by kneading the components using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanizing the mixture.

[0118] As for the kneading conditions, in the base kneading step in which additives other than the crosslinking agent (vulcanizing agent) and the vulcanization accelerator are kneaded, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C. In the finish kneading step in which the vulcanizing agent and the vulcanization accelerator are kneaded, the kneading temperature is usually 120°C or lower, preferably 80 to 110°C. Furthermore, the composition kneaded with the vulcanizing agent and the vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190°C, preferably 150 to 185°C.

[0119] The rubber composition can be used, for example, in tire components (as a rubber composition for tires), and is particularly suitable for use in treads (cap treads).

[0120] The tire of the present invention is manufactured by a conventional method using the above rubber composition. That is, the rubber composition, which contains various additives as necessary, is extruded in an unvulcanized state to match the shapes of the tire components such as the tread, molded in a conventional method on a tire building machine, laminated together with other tire components to form an unvulcanized tire, and then heated and pressurized in a vulcanizer to manufacture the tire.

[0121] The tire is not particularly limited, and examples thereof include pneumatic tires, solid tires, airless tires, etc. Among these, pneumatic tires are preferred.

[0122] The above-mentioned tire can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a heavy load tire (such as a truck or bus tire), a motorcycle tire, a racing tire, a winter tire (a studless tire, a snow tire, a stud tire), an all-season tire, a run-flat tire, an aircraft tire, a mining tire, etc. Among them, it can be preferably used as a heavy load tire. Note that a heavy load tire refers to a tire with a maximum load capacity of 1400 kg or more. Here, the maximum load capacity is the maximum load capacity determined for each tire by the standard system including the standard on which the tire is based, for example, the maximum load capacity based on the load index (LI) in the case of the JATMA standard (Japan Automobile Tire Manufacturers Association standard), the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of the TRA, and "LOAD CAPACITY" in the case of the ETRTO. EXAMPLES

[0123] The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0124] Various chemicals used in the examples and comparative examples will be collectively described below. NR:TSR20 SBR: SBR1502 (styrene content 23.5% by mass) manufactured by Sumitomo Chemical Co., Ltd. BR: BR360L (cis 1,4 bond content 98%) manufactured by Ube Industries, Ltd. Carbon black 1: Seast 6 (N220, N2SA119m) manufactured by Tokai Carbon Co., Ltd. 2 / g) Carbon black 2: VULCAN10H (N134, N2SA144m) manufactured by Cabot Japan Co., Ltd. 2 / g) Silica: Uratosil VN3 (N2SA175m) manufactured by Evonik Degussa 2 / g) Silane coupling agent: Evonik Degussa Si-266 Wax: Ozoace wax made by Nippon Seiro Co., Ltd. Antioxidant 6C: Nocrac 6C (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Anti-aging agent RD: Nocrac RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: Paulownia wood produced by NOF Corporation Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Compound A: (1S,2S)-2,3-Dihydro-1,5-dihydroxy-1H-indene-2-carboxylic acid hydrazide (manufacturing example below) Compound B: 3,5-dihydroxybenzohydrazide manufactured by Tokyo Chemical Industry Co., Ltd. 5% oil sulfur: 5% oil-treated powder sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. (soluble sulfur containing 5% oil by mass) Vulcanization accelerator: Sansera NS-G manufactured by Sanshin Chemical Industry Co., Ltd.

[0125] (Production example) By following the method described in JP-A-2019-508407, it is possible to synthesize (1S,2S)-2,3-Dihydro-1,5-dihydroxy-1H-indene-2-carboxylic acid hydrazide.

[0126] A simulation was performed based on Tables 1 and 2. The results are shown in Tables 1 and 2. The manufacturing conditions and test conditions are as follows.

[0127] (Manufacturing conditions) Using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd., chemicals other than sulfur and the vulcanization accelerator were kneaded at 150°C for 4 minutes, then sulfur and the vulcanization accelerator were added, and the mixture was kneaded at 80°C for 5 minutes using an open roll. Thereafter, the unvulcanized rubber composition was molded into a tread shape in a simulation, and laminated together with other tire components to form an unvulcanized tire. The tire was press-vulcanized at 150°C for 12 minutes to produce a tire with a size of 11R22.5.

[0128] (Wear resistance test conditions) The tires obtained through the simulation were evaluated on an actual vehicle under the following conditions. The amount of wear when the tires were mounted on a truck and driven 50,000 km at a speed of 80 km / h was calculated and expressed as an index (wear resistance performance index) with the standard comparative example taken as 100. The higher the index, the more excellent the wear resistance. The reference example in Table 1 is Comparative Example 1-4, and the reference example in Table 2 is Comparative Example 2-4.

[0129] (Test conditions for chipping resistance) The tires obtained through the simulation were evaluated on an actual vehicle under the following conditions. The chipping resistance performance was determined when the tire was mounted on a truck and driven 50,000 km at 60 km / h on rough road surfaces, and expressed as an index (chipping resistance performance index) with the standard comparative example taken as 100. The higher the index, the more excellent the chipping resistance performance. The reference example in Table 1 is Comparative Example 1-4, and the reference example in Table 2 is Comparative Example 2-4.

[0130] [Table 1]

[0131] [Table 2]

[0132] In each table, in the examples including a rubber component including isoprene-based rubber and SBR, carbon black, silica, and at least one of the compounds represented by the formulas (1) and (2), the overall performance of the abrasion resistance and chipping resistance (represented by the sum of the two indices of abrasion resistance and chipping resistance) is improved. In addition, Comparative Examples 1-6, 1-1, 1-5, and Example 1-2 show that the combined use of carbon black and the compound represented by the formulas (1) and (2) synergistically improves the overall performance of the abrasion resistance and chipping resistance.

Claims

1. A rubber composition comprising a rubber component including an isoprene-based rubber and a styrene-butadiene rubber, carbon black, silica, and at least one selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2), 【Chemistry 1】 (In the formula, A １１ R is a monovalent cyclic hydrocarbon group having at least one polar group. １１ and R １２ are each independently at least one selected from the group consisting of a hydrogen atom, an acyl group, an amide group, an alkyl group, a cycloalkyl group, and an aryl group. 【Chemistry 2】 (In the formula, A ２１ R is a monovalent cyclic hydrocarbon group having at least one polar group. ２１ is a divalent hydrocarbon group. A rubber composition in which the content (parts by mass) of the carbon black relative to 100 parts by mass of the rubber component and the total amount of styrene in 100% by mass of the rubber component satisfy the following formula: 6.0≦Carbon black content / total styrene content≦20.0

2. The rubber composition according to claim 1, wherein the silica content is less than 50% by mass based on 100% by mass of the total of the silica and the carbon black.

3. 3. The rubber composition according to claim 1, wherein the amount of the carbon black is 30 to 80 parts by mass based on 100 parts by mass of the rubber component.

4. The rubber composition according to any one of claims 1 to 3, wherein a total amount of the compounds represented by the formulas (1) and (2) is 30.0 parts by mass or less based on 100 parts by mass of the rubber component.

5. The rubber composition according to any one of claims 1 to 4, wherein the content of the isoprene-based rubber is 50 to 90 mass% and the content of the styrene-butadiene rubber is 5 to 40 mass% in 100 mass% of the rubber component.

6. The rubber composition according to any one of claims 1 to 5, wherein the content of the butadiene rubber in 100% by mass of the rubber component is 5 to 30% by mass.

7. The carbon black has a nitrogen adsorption specific surface area of ​​135 m ２ 7. The rubber composition according to claim 1, further comprising carbon black having a specific surface area of ​​250 m 2 / g or more and 250 m 2 / g or less.

8. The rubber composition according to any one of claims 1 to 7, wherein the polar group includes at least one group selected from the group consisting of a hydroxy group, an amino group, and a nitro group.

9. The R １１ and the R １２ The rubber composition according to any one of claims 1 to 8, wherein is at least one selected from the group consisting of a hydrogen atom and an alkyl group.

10. The rubber composition according to any one of claims 1 to 9, wherein the content of the silica relative to 100 parts by mass of the rubber component and the total amount of styrene in 100% by mass of the rubber component satisfy the following formula: Silica content / total styrene content < 7.0

11. A tire having a tread made of the rubber composition according to any one of claims 1 to 10.

12. 12. The tire of claim 11 which is a heavy duty tire.

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