Rubber composition and tire

Abstract

To provide a rubber composition and a tire excellent in overall performance of hardness and crack growth resistance.SOLUTION: The rubber composition comprises a rubber ingredient containing a butyl-based rubber, a cyclic amine having double bonds in the ring, and carbon black having a 24M4DBP oil absorption of 170ml / 100g or more.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Tires are required to have various performance characteristics, such as low fuel consumption (see Patent Document 1). In addition, improvements in hardness and crack growth resistance are also required. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-65240 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to solve the above problems and to provide a rubber composition and a tire that are excellent in overall performance in terms of hardness and crack growth resistance. [Means for solving the problem]

[0005] The present invention relates to a rubber composition containing a rubber component containing a butyl rubber, a cyclic amine having a double bond in the ring, and carbon black having a 24M4DBP oil absorption of 170 ml / 100 g or more. [Effects of the Invention]

[0006] The present invention relates to a rubber composition containing a rubber component including a butyl rubber, a cyclic amine having a double bond in the ring, and carbon black having a 24M4DBP oil absorption of 170 ml / 100 g or more, thereby improving the overall performance of hardness and crack growth resistance. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing a portion of a pneumatic tire. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing the vicinity of the tread of the tire of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0008] This embodiment is a rubber composition containing a rubber component containing a butyl rubber, a cyclic amine having a double bond in the ring, and carbon black having a 24M4DBP oil absorption of 170 ml / 100 g or more.

[0009] The mechanism by which the rubber composition provides the above-mentioned effects is not entirely clear, but is presumed to be as follows. By combining a cyclic amine containing a double bond within the ring with a highly structured carbon black with a 24M4DBP oil absorption of 170 ml / 100 g or more, an interaction occurs between the cation of the cyclic amine and the π electrons on the surface of the carbon black, forming a strong, reversible bond. As a result, the tensile properties and hardness are improved compared to conventional formulations, which is thought to improve crack growth resistance. Therefore, it is presumed that the rubber composition improves the overall performance of hardness and crack growth resistance.

[0010] The rubber composition includes a rubber component. The rubber component is a component that contributes to crosslinking and is generally a polymer with a weight-average molecular weight (Mw) of 10,000 or more that is not extracted with acetone. The rubber component is in a solid state at room temperature (25°C).

[0011] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, even more preferably 200,000 or more, and particularly preferably 270,000 or more, and is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less. Within the above ranges, the effect tends to be more favorable.

[0012] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) can be determined in terms of standard polystyrene based on measurements obtained using a gel permeation chromatograph (GPC) (GPC-8000 series, manufactured by Tosoh Corporation; detector: differential refractometer; column: TSKGEL SUPERMULTIPORE HZ-M, manufactured by Tosoh Corporation).

[0013] The rubber component may be either an unmodified rubber or a modified rubber. Examples of modified rubbers include rubbers having functional groups that interact with fillers such as silica. Examples include terminal-modified rubbers (terminal-modified rubbers having the functional groups at the terminals) in which at least one terminal of the rubber has been modified with a compound (modifier) ​​having the functional group, main-chain-modified rubbers having the functional groups in the main chain, main-chain-terminal-modified rubbers having the functional groups in the main chain and at the terminals (for example, main-chain-terminal-modified rubbers having the functional groups in the main chain and at least one terminal modified with the modifier), and terminal-modified rubbers modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having hydroxyl groups or epoxy groups introduced therein.

[0014] 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 imido 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 these, an amino group (preferably an amino group in which a hydrogen atom of the 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.

[0015] The rubber composition contains a butyl rubber as a rubber component. Examples of the butyl rubber include butyl rubber; halogenated butyl rubbers such as chlorinated butyl rubber (Cl-IIR), brominated butyl rubber (Br-IIR), and fluorinated butyl rubber (F-IIR). Commercially available butyl rubbers include ExxonMobil's Exprobutyl, Chlorobutyl HT1068, and Bromobutyl 2255. The butyl rubbers may be used alone or in combination of two or more. Among these, from the viewpoint of obtaining better effects, it is preferable to include halogenated butyl rubber, and it is more preferable to include brominated butyl rubber.

[0016] The butyl rubber may be either an unmodified butyl rubber or a modified butyl rubber. The modified butyl rubber may be a modified butyl rubber into which the same functional groups as those of the above modified rubber have been introduced.

[0017] In the rubber composition, the content of the butyl rubber in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, still more preferably 50% by mass or more, still more preferably 60% by mass or more, still more preferably 70% by mass or more, or even 100% by mass. Within the above range, the effect tends to be better obtained.

[0018] In the rubber composition, the content of the halogenated butyl rubber in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, still more preferably 50% by mass or more, still more preferably 60% by mass or more, still more preferably 70% by mass or more, or even 100% by mass. When it is within the above range, the effect tends to be better obtained.

[0019] The rubber composition may contain a rubber component other than the butyl-based rubber. Examples of rubber components other than the butyl rubber include diene rubber. Examples of diene rubber include isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Other examples of rubber components include fluororubbers. These rubber components may be modified or hydrogenated, and extended rubbers extended with oil, resin, liquid rubber components, or the like may also be used. Among these, it is preferable to include at least one of isoprene rubber, BR, and SBR.

[0020] The raw materials (monomers) for synthetic rubbers such as IR, SBR, and BR may be derived from underground resources such as petroleum and natural gas, or may be recycled from rubber products such as tires or non-rubber products such as polystyrene. Monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyls. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyls include, but are not limited to, styrene. Among these, recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) are preferably used as raw materials.

[0021] The method for producing the recycled monomer is not particularly limited, and examples thereof include synthesis from recycled naphtha obtained by decomposing rubber products such as tires. The method for producing recycled naphtha is also not particularly limited, and examples thereof include decomposing rubber products such as tires under high temperature and pressure, decomposing with microwaves, or mechanically crushing and then extracting.

[0022] Furthermore, the raw materials (monomers) of synthetic rubbers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to materials derived from natural resources such as plants. Examples of biomass include, but are not limited to, agricultural, forestry, and fishery products, sugar, wood chips, plant residues after useful components have been extracted, plant-derived ethanol, and biomass naphtha.

[0023] Monomers derived from biomass (biomass monomers) are not particularly limited and include biomass-derived butadiene and biomass-derived aromatic vinyl. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyls include, but are not limited to, styrene. The method for producing biomass monomers is not particularly limited and includes, for example, biological and / or chemical and / or physical conversion of animals and plants. A representative example of biological conversion is fermentation by microorganisms, and examples of chemical and / or physical conversion include catalytic conversion, high heat conversion, high pressure conversion, electromagnetic wave conversion, critical fluid conversion, and combinations thereof. The polymer synthesized from a biomass monomer component (biomass polymer) is not particularly limited, and examples thereof include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymer synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0024] Whether the raw material for a polymer is derived from biomass can be determined by the pMC (percent modern carbon) measured in accordance with ASTM D6866-10.

[0025] pMC is the modern standard reference 14 of sample against C concentration 14This is the ratio of C concentrations and is a value used as an index of the biomass ratio of a compound. The significance of this value is explained below.

[0026] 1 mole of carbon atoms (6.02 × 10 23 ) contains approximately 6.02 × 10 atoms, which is about one trillionth of the number of ordinary carbon atoms. 11 pieces 14 C exists. 14 C is called a radioactive isotope, and its half-life is 5,730 years, and it decreases regularly. It takes 226,000 years for all of it to decay. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been absorbed and fixed by plants and other organisms more than 226,000 years ago, C was also included in these when it was first fixed. 14 All C elements have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas contain 14 Therefore, chemicals produced from these fossil fuels do not contain any C element. 14 It does not contain any C element.

[0027] on the other hand, 14 C is produced continuously by nuclear reactions in the atmosphere caused by cosmic rays, and this balances with the decrease due to radioactive decay. In the Earth's atmospheric environment, 14 Therefore, the amount of carbon derived from biomass resources currently circulating in the environment is constant. 14 As mentioned above, the C concentration is approximately 1 × 10 -12 The value is approximately mol %. Therefore, the biomass ratio of a certain compound can be calculated by using the difference between these values.

[0028] this 14 C is typically measured using accelerator mass spectrometry based on a tandem accelerator. 13 C concentration ( 13 C / 12 C). 14 C concentration ( 14 C / 12 C) is measured. 14The modern standard reference for the C concentration is the carbon circulating in nature as of 1950. 14 The specific standard substance used is the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific activity of carbon in this oxalic acid (per gram of carbon) is 14 The radioactivity of C is separated into carbon isotopes, 13 The standard value is the value corrected for decay from 1950 to the measurement date. 14 This is used as the C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value.

[0029] Therefore, if rubber is made from 100% biomass-derived materials, it will show a value of approximately 110 pMC, although there may be regional differences (currently, under normal conditions, it is often not 100). On the other hand, for chemical substances derived from petroleum and other fossil fuels, 14 When the carbon concentration is measured, it will show a value of approximately 0 pMC (for example, 0.3 pMC), which corresponds to the biomass ratio of 0% mentioned above.

[0030] From the above, it is preferable in terms of environmental protection to use a material such as rubber having a high pMC value, that is, a material such as rubber having a high biomass ratio, in a rubber composition.

[0031] Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. As the NR, for example, SIR20, RSS#3, TSR20, and other rubber industry-standard rubbers can be used. As the IR, there are no particular limitations, and for example, IR2200 and other rubber industry-standard rubbers can be used. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber. 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.

[0032] The butadiene rubber (BR) is not particularly limited, and examples thereof include high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using a rare earth catalyst (rare earth BR). These may be used alone or in combination of two or more. Of these, the BR preferably contains high-cis BR with a cis content of 90% by mass or more. The cis content is more preferably 95% by mass or more. The cis content can be measured by infrared absorption spectroscopy.

[0033] In this specification, the cis content of BR means the cis content of the BR when there is one type of BR, and means the average cis content when there are multiple types of BR. The average cis content of BR can be calculated by {Σ(content of each BR × cis content of each BR)} / total content of all BRs. For example, when 100% by mass of the rubber component contains 20% by mass of BR with a cis content of 90% by mass and 10% by mass of BR with a cis content of 40% by mass, the average cis content of BR is 73.3% by mass (=(20×90+10×40) / (20+10)).

[0034] Both unmodified and modified BR can be used. Modified BR includes modified BR with the same functional groups as modified rubber. Hydrogenated butadiene polymer (hydrogenated BR) can also be used.

[0035] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0036] The styrene-butadiene rubber (SBR) is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. These may be used alone or in combination of two or more.

[0037] The styrene content of the SBR is preferably 5% by mass or more, more preferably 20% by mass or more, and even more preferably 24% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. Within the above range, the effect tends to be more favorable. In this specification, the amount of styrene is 1 It can be measured by H-NMR measurement.

[0038] The styrene content of SBR means the styrene content of the SBR when there is one type of SBR, and means the average styrene content when there are multiple types of SBR. The average styrene amount of SBR can be calculated by {Σ(content of each SBR × styrene amount of each SBR)} / total content of all SBRs. For example, when 100% by mass of the rubber component contains 85% by mass of SBR with a styrene amount of 40% by mass and 5% by mass of SBR with a styrene amount of 25% by mass, the average styrene amount of the SBR is 39.2% by mass (=(85×40+5×25) / (85+5)).

[0039] The vinyl content of the SBR is preferably 3% by mass or more, more preferably 10% by mass or more, and even more preferably 17% by mass or more. The vinyl content is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. When the vinyl content is within the above range, better effects tend to be obtained. In this specification, the vinyl content (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectroscopy.

[0040] The vinyl content of SBR (amount of 1,2-bonded butadiene units) is the proportion of vinyl bonds (unit: mass%) when the total mass of the butadiene parts in the SBR is taken as 100, and is calculated as vinyl content [mass%] + cis content [mass%] + trans content [mass%] = 100 [mass%]. When there is one type of SBR, it means the vinyl content of that SBR, and when there are multiple types, it means the average vinyl content. The average vinyl content of SBR can be calculated by Σ{content of each SBR × (100 [mass%] - styrene content of each SBR [mass%]) × vinyl content of each SBR [mass%]} / Σ{content of each SBR × (100 [mass%] - styrene content of each SBR [mass%])}. For example, in 100 parts by mass of the rubber component, 75 parts by mass of SBR with a styrene content of 40% by mass and a vinyl content of 30% by mass, 25 parts by mass of styrene and 10 parts by mass of vinyl are used. In the case where 15 parts by mass of SBR with a vinyl content of 20% by mass is used and the remaining 10 parts by mass are other than SBR, the average vinyl content of the SBR is 28% by mass (= {75 × (100 [% by mass] - 40 [% by mass]) × 30 [% by mass] + 15 × (100 [% by mass] - 25 [% by mass]) × 20 [% by mass])} / {75 × (100 [% by mass] - 40 [% by mass]) + 15 × (100 [% by mass] - 25 [% by mass])}.

[0041] Both unmodified and modified SBR can be used. Modified SBR includes modified SBR with the same functional groups as modified rubber. Hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used as SBR.

[0042] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used. SBR synthesized by a known method can also be used.

[0043] When the rubber composition contains an isoprene-based rubber, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. When the content is within the above range, better effects tend to be obtained.

[0044] When the rubber composition contains BR, the content of the BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. When the content is within the above range, better effects tend to be obtained.

[0045] When the rubber composition contains SBR, the content of the SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. When the content is within the above range, better effects tend to be obtained.

[0046] The rubber composition for a tire contains a cyclic amine having a double bond in the ring. As used herein, a cyclic amine having a double bond in the ring refers to a compound having at least one double bond in the ring structure of the cyclic amine.

[0047] In the rubber composition, the content of the cyclic amine having a double bond in the ring (total amount of cyclic amines having a double bond in the ring) is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, even more preferably 0.5 part by mass or more, still more preferably 1.0 part by mass or more, still more preferably 2.0 parts by mass or more, still more preferably 4.0 parts by mass or more, and is preferably 15.0 parts by mass or less, more preferably 10.0 parts by mass or less, and still more preferably 6.0 parts by mass or less, per 100 parts by mass of the rubber component. Within the above ranges, the effects tend to be better obtained.

[0048] The cyclic amine having a double bond in the ring is not particularly limited as long as it exhibits the above-mentioned effects, and examples of the ring form include a 3-membered ring, a 4-membered ring, a 5-membered ring, and a 6-membered ring. Among these, from the viewpoint of obtaining the effects more effectively, a 5-membered ring or a 6-membered ring is preferable, and a 5-membered ring is more preferable. Furthermore, it may have a heteroatom other than a nitrogen atom.

[0049] As the cyclic amine having a double bond in the ring, imidazole compounds and pyridine compounds can be suitably used, with imidazole compounds being particularly preferred.

[0050] The imidazole compound is a compound having an imidazole ring, and among these, a compound represented by the following formula (I) is preferred.

[0051] [ka]

[0052] In the above formula (I), R 1 , R 2 , R 3 , R 4 are the same or different and represent a hydrogen atom or a hydrocarbon group. 3 , R 4 may be bonded to each other to form a ring structure.

[0053] R 1 , R2 , R 3 , R 4 Examples of the hydrocarbon group include an alkyl group having 1 to 20 carbon atoms (preferably 2 to 12 carbon atoms, more preferably 4 to 9 carbon atoms), a cycloalkyl group having 5 to 24 carbon atoms (preferably 5 to 8 carbon atoms), an aryl group having 6 to 30 carbon atoms (preferably 6 to 24 carbon atoms), and an aralkyl group having 7 to 25 carbon atoms (preferably 7 to 13 carbon atoms).

[0054] Also, R 3 , R 4 When they are bonded to form a ring structure, R 3 , R 4 and the carbon atom of the imidazole ring, may be, for example, an aromatic ring, a heterocyclic ring, or an aliphatic ring having 5 to 12 carbon atoms.

[0055] From the viewpoint of obtaining better effects, R 1 , R 2 , R 3 , R 4 Preferably, at least one of R is an alkyl group. 1 , R 2 , R 3 , R 4 It is more preferable that one of R is an alkyl group and the other three are hydrogen atoms. 1 is an alkyl group, R 2 , R 3 , R 4 It is more preferable that is a hydrogen atom. In addition, R 1 If the alkyl group has a small number of carbon atoms, the ionic bond between the imidazole compound and the high-structure carbon black becomes stronger, and hardness tends to increase; if the alkyl group has a large number of carbon atoms, the ionic bond between the imidazole compound and the high-structure carbon black becomes weaker and more likely to come off, and therefore force tends to be more easily released when flexed.

[0056] Specific examples of the imidazole compound include imidazole, 1-nonylimidazole, 1-butylimidazole, 1-propylimidazole, 1-ethylimidazole, 1-methylimidazole, 1,2-dimethylimidazole, 1-decyl-2-methylimidazole, and 1-benzyl-2-methylimidazole. These may be used alone or in combination of two or more. Among these, 1-nonylimidazole, 1-butylimidazole, 1-propylimidazole, 1-ethylimidazole, and 1-methylimidazole are preferred, 1-nonylimidazole and 1-butylimidazole are more preferred, and 1-nonylimidazole is even more preferred.

[0057] The pyridine compound is a compound having a pyridine ring, and among these, a compound represented by the following formula (II) is preferred.

[0058] [ka]

[0059] In the above formula (II), R bonded to the pyridine ring 11 ~R 15 are the same or different and represent a hydrogen atom or a monovalent organic group. 11 ~R 15 may be bonded to each other or may form a ring structure.

[0060] In the above formula (II), R 11 ~R 15is a monovalent organic group, examples of the monovalent organic group include an aryl group, a heterocyclic group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an arylalkoxy group, a silyl group, a hydroxy group, an amino group, a halogen atom, a carboxyl group, a thiol group, an epoxy group, an acyl group, an oligoaryl group, a monovalent oligoheterocyclic group, an alkylthio group, an arylthio group, an arylalkyl group, an arylalkoxy group, an arylalkylthio group, an azo group, a stannyl group, a phosphino group, a silyloxy group, an aryloxycarbo Examples of the alkyl group include an aryl group, an alkoxycarbonyl group, a carbamoyl group, an arylcarbonyl group, an alkylcarbonyl group, an arylsulfonyl group, an alkylsulfonyl group, an arylsulfinyl group, an alkylsulfinyl group, a formyl group, a cyano group, a nitro group, an arylsulfonyloxy group, an alkylsulfonyloxy group, an alkylsulfonate group, an arylsulfonate group, an arylalkylsulfonate group, a boryl group, a sulfoniummethyl group, a phosphoniummethyl group, a phosphonatemethyl group, an arylsulfonate group, an aldehyde group, and an acetonitrile group. 11 ~R 15 When the monovalent organic group has a substituent, it may have one or more substituents.

[0061] Above R 11 ~R 15In the case where the monovalent organic group has a substituent, examples of the substituent include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom; a haloalkyl group such as a methyl chloride group, a methyl bromide group, a methyl iodide group, a fluoromethyl group, a difluoromethyl group, or a trifluoromethyl group; a linear or branched alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, or a tert-butyl group; a cyclic alkyl group having 5 to 7 carbon atoms such as a cyclopentyl group, a cyclohexyl group, or a cycloheptyl group; a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a tert-butoxy group, a pentylomethyl group, or a methyl group; Examples of such groups include linear or branched alkoxy groups having 1 to 20 carbon atoms, such as oxy, hexyloxy, heptyloxy, and octyloxy; hydroxy groups; thiol groups; nitro groups; cyano groups; amino groups; azo groups; acyl groups; alkenyl groups having 2 to 20 carbon atoms, such as vinyl groups, 1-propenyl groups, allyl groups, butenyl groups, and styryl groups; alkynyl groups having 2 to 20 carbon atoms, such as ethynyl groups, 1-propynyl groups, propargyl groups, and phenylacetynyl groups; alkenyloxy groups, such as vinyloxy and allyloxy groups; alkynyloxy groups, such as ethynyloxy and phenylacetyloxy groups; and aryloxy groups, such as phenoxy, naphthoxy, biphenyloxy, and pyrenyloxy groups. These groups may be bonded to each other at any position to form a ring.

[0062] Specific examples of the pyridine compound include pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, and 4-dimethylaminopyridine. These may be used alone or in combination of two or more. Among these, from the viewpoint of basicity, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, and 4-dimethylaminopyridine are preferred, and 4-dimethylaminopyridine is more preferred. By using a pyridine compound with strong basicity, the ionic bond between the pyridine compound and the highly structured carbon black becomes stronger, which tends to increase hardness.

[0063] The rubber composition contains, as a filler, carbon black having a 24M4DBP oil absorption of 170 ml / 100 g or more. The 24M4DBP oil absorption (compressed dibutyl phthalate oil absorption) of the carbon black is preferably 200 ml / 100 g or more, more preferably 250 ml / 100 g or more, even more preferably 300 ml / 100 g or more, even more preferably 350 ml / 100 g or more, even more preferably 400 ml / 100 g or more, and even more preferably 420 ml / 100 g or more. The upper limit of the 24M4DBP oil absorption is not particularly limited, but is preferably 1000 ml / 100 g or less, more preferably 800 ml / 100 g or less, even more preferably 600 ml / 100 g or less, and even more preferably 500 ml / 100 g or less. The 24M4DBP oil absorption of carbon black is a value measured based on ASTM D3493-91 (Standard Test Method for Carbon Black-n-Dibuty 1 Phthalate Absorption Number of Compressed Sample).

[0064] The carbon black having a 24M4DBP oil absorption of 170 ml / 100 g or more is not particularly limited as long as it has a 24M4DBP oil absorption of 170 ml / 100 g or more, and GPF, FEF, HAF, ISAF, SAF, etc. can be used alone or in combination of two or more. Commercially available products include those from Orion Engineered Carbons, etc.

[0065] The content of the carbon black having a 24M4DBP oil absorption of 170 ml / 100 g or more is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 7 parts by mass or more, even more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably less than 40 parts by mass, more preferably less than 30 parts by mass, even more preferably less than 25 parts by mass, and even more preferably less than 20 parts by mass. Within the above range, better effects tend to be obtained.

[0066] The rubber composition may contain a filler other than the carbon black having a 24M4DBP oil absorption of 170 ml / 100 g or more. Fillers other than the carbon black having a 24M4DBP oil absorption of 170 ml / 100 g or more are not particularly limited, and materials known in the rubber field can be used, such as carbon black having a 24M4DBP oil absorption of less than 170 ml / 100 g; inorganic fillers such as silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica; biochar; and poorly dispersible fillers. Among these, carbon black and silica having a 24M4DBP oil absorption of less than 170 ml / 100 g are preferred from the viewpoint of obtaining the best results.

[0067] In the rubber composition, the filler content (total amount of fillers such as carbon black and silica) is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 7 parts by mass or more, even more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the rubber component. Also, it is preferably less than 40 parts by mass, more preferably less than 30 parts by mass, even more preferably less than 25 parts by mass, and even more preferably less than 20 parts by mass. Within the above range, better effects tend to be obtained.

[0068] Although the mechanism by which a filler content less than the predetermined amount, particularly less than 40 parts by mass, provides a greater effect is unclear, it is believed that a low filler content makes it less likely to inhibit the self-repairing properties of the rubber composition after vulcanization, thereby enhancing the self-repairing properties of the rubber composition after vulcanization, and therefore further improving the overall performance of hardness and crack growth resistance.

[0069] Examples of carbon black having a 24M4DBP oil absorption of less than 170 ml / 100 g include, but are not limited to, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. The raw material for carbon black may be a biomass material such as lignin or vegetable oil, or pyrolysis oil obtained by pyrolysis of waste tires. Carbon black may be produced by combustion, such as in a furnace process, by hydrothermal carbonization (HTC), or by thermal decomposition of methane, such as in a thermal black process. Commercially available carbon blacks include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Columbia Carbon Co., Ltd. Carbon black may be used alone or in combination.

[0070] The nitrogen adsorption specific surface area (N2SA) of carbon black with an oil absorption of less than 170 ml / 100 g is 5 m 2 / g or more is preferable, and 50m 2 / g or more is more preferable, and 90m 2 / g or more is more preferable. 2 / g or less is preferable, and 130m 2 / g or less is more preferable, and 120m 2 Within the above range, the effect tends to be better. The nitrogen adsorption specific surface area of ​​carbon black can be determined according to JIS K6217-2:2001.

[0071] When the rubber composition contains carbon black having a 24M4DBP oil absorption of less than 170 ml / 100 g, the amount of the carbon black having a 24M4DBP oil absorption of less than 170 ml / 100 g is preferably at least 0.5 parts by mass, more preferably at least 1.0 part by mass, and even more preferably at least 3.0 parts by mass, per 100 parts by mass of the rubber component, and is preferably at most 150 parts by mass, more preferably at most 120 parts by mass, and even more preferably at most 100 parts by mass. Within the above ranges, better effects tend to be obtained.

[0072] The silica that can be used in the rubber composition is not particularly limited, and can be, for example, silica prepared by a dry process (anhydrous silica) or silica prepared by a wet process (hydrated silica), which are commonly used in the tire industry. The raw material for the silica is not particularly limited, and can be, for example, a mineral-derived raw material such as quartz, a biological raw material such as rice husk (for example, silica made from a biomass material such as rice husk), or silica recycled from a silica-containing product. Among these, hydrated silica prepared by a wet process is preferred because it contains a large number of silanol groups. These silicas can be used alone or in combination of two or more types.

[0073] Silica made from biomass materials can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then reacting the silicate with sulfuric acid in the same manner as conventional wet-process silica to produce a silicon dioxide precipitate, which is then filtered, washed with water, dried, and pulverized.

[0074] Silica recycled from silica-containing products can be, for example, silica recovered from products containing silica, such as electronic components such as semiconductors, tires, desiccants, and filtering materials such as diatomaceous earth. The recovery method is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from electronic components such as semiconductors or tires is preferred.

[0075] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and duration, it is possible to suppress the crystallization of silica in rice husk ash (see, for example, JP 2009-2594 A and Akita Prefectural University Web Journal B / 2019, vol. 6, pp. 216-222).

[0076] Amorphous silica extracted from rice husks may be commercially available from Wilmar Co., Ltd., etc.

[0077] When the rubber composition contains silica, the content of silica is preferably 5 parts by mass or more, more preferably 40 parts by mass or more, and even more preferably 50 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 100 parts by mass or less. When the content is within the above range, better effects tend to be obtained.

[0078] 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 The upper limit of the N2SA of silica is not particularly limited, but is preferably 350 m 2 / g or less, more 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 is a value measured by the BET method in accordance with ASTM D3037-93.

[0079] Examples of the hardly dispersible filler include microfibrillated plant fibers, short fiber cellulose, gel compounds, etc. Among these, microfibrillated plant fibers are preferred.

[0080] The microfibrillated plant fiber is preferably cellulose microfibrils, as they provide good reinforcing properties. The cellulose microfibrils are not particularly limited as long as they are derived from natural products, and examples include those derived from resource biomass such as fruits, grains, and root vegetables; wood, bamboo, hemp, jute, and kenaf; pulp, paper, and cloth obtained from these raw materials; waste biomass such as agricultural waste, food waste, and sewage sludge; unused biomass such as rice straw, wheat straw, and thinned wood; and cellulose produced by sea squirts, acetic acid bacteria, and the like. These microfibrillated plant fibers may be used alone or in combination of two or more.

[0081] In this specification, cellulose microfibrils typically refer to cellulose fibers having an average fiber diameter of 10 μm or less, more typically cellulose fibers having a microstructure formed by the aggregation of cellulose molecules and an average fiber diameter of 500 nm or less. Typical cellulose microfibrils are formed, for example, as an aggregate of cellulose fibers having the above-mentioned average fiber diameter.

[0082] When the rubber composition contains a hardly-dispersible filler, the content of the hardly-dispersible filler is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 50 parts by mass or less, more preferably 30 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 range, the effect tends to be more favorably obtained.

[0083] When the rubber composition contains silica, it is preferable that the rubber composition further contains a silane coupling agent. The silane coupling agent is not particularly limited, and those known in the rubber field can be used, for example, 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, Examples include sulfide-based compounds such as N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z manufactured by Momentive; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products include those from Degussa, Momentive, Shin-Etsu Silicones Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Dow Corning Toray Co., Ltd. These may be used alone or in combination of two or more.

[0084] In the rubber composition, the content of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, relative to 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0085] The rubber composition may contain a plasticizer. In this specification, the term "plasticizer" refers to a material that imparts plasticity to rubber components, and includes both plasticizers that are liquid (fluid-like) at room temperature (25°C) and plasticizers that are solid at room temperature (25°C). Examples of plasticizers include resin components, oils, liquid polymers, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, biomass-derived plasticizers, or naphtha recycled from rubber and non-rubber products. Low-molecular-weight hydrocarbon components obtained by pyrolysis and extraction of used tires or products containing various components may also be used as plasticizers. These plasticizers may be used alone or in combination.

[0086] Specific examples of the plasticizer include oils, liquid polymers, resins, etc. These may be used alone or in combination of two or more.

[0087] Examples of oils include mineral oil, vegetable oil, animal oil, etc. From the viewpoint of life cycle assessment, waste oils used in rubber mixers or engines, or refined waste cooking oils used in restaurants may also be used. As used herein, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oil (mineral oil), naphthenic oil, and aromatic oil. Specific examples of mineral oil include mild extract solvated (MES), distillate aromatic extract (DAE), treated distillate aromatic extract (TDAE), treated residual aromatic extract (TRAE), and residual aromatic extract (RAE). Furthermore, as an environmental measure, oils with a low content of polycyclic aromatic compounds (PCA) can also be used. Examples of low PCA oils include MES, TDAE, and heavy naphthenic oil.

[0088] As used herein, examples of vegetable oils include linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and Japan wax. Further examples of vegetable oils include refined oils (such as salad oil) obtained by refining the above-mentioned oils, interesterified oils obtained by interesterifying the above-mentioned oils, hardened oils obtained by hydrogenating the above-mentioned oils, thermally polymerized oils obtained by thermally polymerizing the above-mentioned oils, oxidatively polymerized oils obtained by oxidizing the above-mentioned oils, and waste edible oils recovered from edible oils and the like. Vegetable oils may be liquid or solid at room temperature (25°C). These vegetable oils may be used alone or in combination of two or more.

[0089] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin is ester-bonded to a fatty acid. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer (trimer or higher). Dimer or higher acylglycerols can be obtained by thermal polymerization, oxidative polymerization, or the like. Furthermore, the acylglycerol may be liquid or solid at room temperature (25°C).

[0090] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, but may be any of the following: 1 For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at room temperature (25°C) for 24 hours, and after removing the rubber composition, the rubber composition is immersed in deuterated chloroform at room temperature. 1 When H-NMR was measured, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm when the signal of tetramethylsilane (TMS) was set at 0.00 ppm. These signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atoms of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0091] The fatty acid is not particularly limited and may be either an unsaturated fatty acid or a saturated fatty acid. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0092] Among these, it is desirable that the fatty acid contains a fatty acid with few double bonds, i.e., a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As a vegetable oil containing such a fatty acid, for example, vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or vegetable oil modified by ester exchange or the like may be used. Furthermore, in order to produce vegetable oil containing such a fatty acid, plants may be improved by breeding, genetic modification, genome editing, or the like.

[0093] As the oil, for example, commercially available oils from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., Fuji Kosan Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0094] Examples of the liquid polymer include liquid diene polymers (liquid rubbers) and liquid farnesene polymers at 25°C. Examples of liquid rubber include liquid styrene butadiene copolymers (liquid SBRs), liquid butadiene polymers (liquid BRs), liquid isoprene polymers (liquid IRs), liquid styrene isoprene copolymers (liquid SIRs), liquid styrene butadiene styrene block copolymers (liquid SBS block polymers), and liquid styrene isoprene styrene block copolymers (liquid SIS block polymers). The terminals or main chains of these may be modified with polar groups. Hydrogenated versions of these compounds can also be used.

[0095] The liquid diene polymer has a weight average molecular weight (Mw) of 1.0×10 in terms of polystyrene as measured by gel permeation chromatography (GPC). 3 ~5.0×10 4 Preferably, it is 3.0 × 10 3 ~1.5×10 4 The lower or upper limit of Mw of the liquid diene polymer may be 4,500 or 8,500. In this specification, the Mw of the liquid diene polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0096] As the liquid diene polymer, for example, products available from Sartomer Co., Ltd., Kuraray Co., Ltd., etc. can be used.

[0097] The resin may be a resin commonly used in tire compounds, and may be liquid or solid at room temperature (25°C). Examples include aromatic vinyl polymers, coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, and acrylic resins. The resin may also be a hydrogenated resin (hydrogenated resin). These may be used alone or in combination of two or more. The resin itself may also be a copolymer of monomer components derived from multiple sources. Among these, aromatic vinyl polymers, petroleum resins, terpene resins, and hydrogenated resins thereof are preferred.

[0098] When a resin that is solid at room temperature is used, the softening point of the resin is preferably 50° C. or higher, more preferably 55° C. or higher, even more preferably 60° C. or higher, and particularly preferably 85° C. or higher. Also, the softening point is preferably 160° C. or lower, more preferably 150° C. or lower, even more preferably 140° C. or lower, and particularly preferably 100° C. or lower. Within the above range, better effects tend to be obtained. When the resin is liquid at room temperature, the softening point is preferably 20°C or lower, more preferably 10°C or lower, and even more preferably 0°C or lower. In the case of hydrogenated resins, it is desirable that the softening point is the same as above. The softening point of the resin is the temperature at which the ball drops when the softening point specified in JIS K6220-1:2001 is measured using a ring and ball softening point tester.

[0099] The aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a constituent unit. For example, it may be a resin obtained by polymerizing α-methylstyrene and / or styrene, and specifically may be a homopolymer of styrene (styrene resin), a homopolymer of α-methylstyrene (α-methylstyrene resin), a copolymer of α-methylstyrene and styrene, or a copolymer of styrene and another monomer.

[0100] The coumarone-indene resin is a resin containing coumarone and indene as the main monomer components constituting the resin skeleton (main chain). Other monomer components contained in the skeleton besides coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0101] The coumarone resin is a resin containing coumarone as a main monomer component constituting the skeleton (main chain) of the resin.

[0102] The indene resin is a resin containing indene as a main monomer component that constitutes the skeleton (main chain) of the resin.

[0103] The phenolic resin may be a known polymer obtained by reacting phenol with an aldehyde such as formaldehyde, acetaldehyde, or furfural in the presence of an acid or alkali catalyst. Of these, those obtained by reacting with an acid catalyst (such as novolac phenolic resin) are preferred.

[0104] Examples of the rosin resin include rosin-based resins such as natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

[0105] Examples of the petroleum resin include C5 resin, C9 resin, C5 / C9 resin, dicyclopentadiene (DCPD) resin, C9 / DCPD resin, and hydrogenated versions of these. Of these, DCPD resin, hydrogenated DCPD resin, C9 / DCPD resin, and C9 / hydrogenated DCPD resin are preferred.

[0106] The terpene resin is a polymer containing terpene as a structural unit. Examples include polyterpene resins obtained by polymerizing terpene compounds and aromatic-modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds. Examples of aromatic-modified terpene resins include terpene phenol resins made from terpene compounds and phenolic compounds, terpene styrene resins made from terpene compounds and styrene compounds, and terpene phenol styrene resins made from terpene compounds, phenolic compounds, and styrene compounds. Examples of terpene compounds include α-pinene and β-pinene, phenolic compounds include phenol and bisphenol A, and aromatic compounds include styrene compounds (styrene, α-methylstyrene, etc.). Among these, aromatic-modified terpene resins are preferred.

[0107] The acrylic resin is a polymer containing an acrylic monomer as a constituent unit. For example, a styrene-acrylic resin having a carboxyl group and obtained by copolymerizing an aromatic vinyl monomer component with an acrylic monomer component can be used. Among them, a solvent-free carboxyl-containing styrene-acrylic resin can be preferably used.

[0108] Examples of the 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, ExxonMobil, KRATON, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0109] From the viewpoint of sustainability, it is desirable to use the above-mentioned plant-derived plasticizers such as plant-derived oils and farnesene-based polymers as the plasticizer.

[0110] Farnesene polymers are polymers obtained by polymerizing farnesene and contain structural units based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene), but (E)-β-farnesene, which has the following structure, is preferred. [ka]

[0111] The farnesene polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer). These may be used alone or in combination of two or more. Among these, a copolymer of farnesene and a vinyl monomer is preferred.

[0112] Examples of vinyl monomers include aromatic vinyl compounds such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-tert-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-tert-butylstyrene, 3-tert-butylstyrene, 4-tert-butylstyrene, vinylxylene, vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene, and tertiary amino group-containing diphenylethylene, as well as conjugated diene compounds such as butadiene and isoprene. These may be used alone or in combination of two or more. Among these, butadiene is preferred. That is, the farnesene-vinyl monomer copolymer is preferably a copolymer of farnesene and butadiene (farnesene-butadiene copolymer).

[0113] In the farnesene-vinyl monomer copolymer, the copolymerization ratio by mass of farnesene to vinyl monomer (farnesene / vinyl monomer) is preferably 40 / 60 to 90 / 10.

[0114] The farnesene polymer preferably has a weight average molecular weight (Mw) of 3,000 or more and 300,000 or less. The Mw of the farnesene polymer is preferably 8,000 or more, more preferably 10,000 or more, and is preferably 100,000 or less, more preferably 60,000 or less, and even more preferably 50,000 or less. Within the above ranges, the effects tend to be more favorably obtained.

[0115] The farnesene polymer may be either a liquid or solid at room temperature (25° C.), with liquid farnesene polymers being preferred.

[0116] In the rubber composition, the content of the plasticizer (total amount of plasticizer) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less. Within the above range, better effects tend to be obtained. The plasticizer content includes the amount of oil and resin contained in the oil-extended rubber and resin-extended rubber.

[0117] In the rubber composition, the content of the solid plasticizer in a solid state at room temperature (25°C) is preferably 20 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 1 part 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, better effects tend to be obtained.

[0118] In the rubber composition, the content of the resin in a solid state at room temperature (25°C) is preferably 20 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 1 part 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, better effects tend to be obtained.

[0119] In the rubber composition, the content of the liquid plasticizer that is in a liquid state at room temperature (25°C) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less. Within the above range, better effects tend to be obtained. The content of the liquid plasticizer includes the amount of oil contained in the oil-extended rubber and the amount of liquid resin in the resin-extended rubber extended with the liquid resin.

[0120] In the rubber composition, the oil content is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less. Within the above range, the effect tends to be more favorably obtained. The oil content includes the amount of oil contained in the oil-extended rubber.

[0121] The rubber composition may further contain vulcanized rubber particles. The vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the standpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. These may be used alone or in combination of two or more types.

[0122] The vulcanized rubber particles are not particularly limited, and may be unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0123] As commercially available vulcanized rubber particles, for example, products from Lehigh Corporation, Muraoka Rubber Industries Co., Ltd., etc. can be used.

[0124] In the rubber composition, the content of the vulcanized rubber particles is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0125] The rubber composition preferably contains an antioxidant from the viewpoints of crack resistance, ozone resistance, and the like.

[0126] The antioxidant is not particularly limited, and examples thereof 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 (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditolyl-p-phenylenediamine. p-phenylenediamine antioxidants such as N-isopropyl-N'-phenyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; 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. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products that can be used include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, etc.

[0127] In the rubber composition, the content of the antioxidant is preferably 0.2 parts by mass or more, more preferably 2.0 parts by mass or more, and even more preferably 3.4 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10.0 parts by mass or less, more preferably 6.0 parts by mass or less.

[0128] The rubber composition preferably contains stearic acid. In the rubber composition, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2.0 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0129] As the stearic acid, conventionally known products can be used, for example, products available from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc.

[0130] The rubber composition preferably contains zinc oxide. In the rubber composition, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2.0 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 6.0 parts by mass or less, and more preferably 4.0 parts by mass or less.

[0131] As the zinc oxide, conventionally known products can be used, for example, products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0132] The rubber composition may contain wax. In the rubber composition, the wax content is preferably 0.5 parts by mass or more, more preferably 1.6 parts by mass or more, and preferably 8.0 parts by mass or less, more preferably 5.0 parts by mass or less, per 100 parts by mass of the rubber component.

[0133] The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used. Examples include mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. Waxes that can be used include those commercially available from, for example, Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., Ltd., etc. These waxes may be used alone or in combination of two or more.

[0134] It is preferable to compound sulfur as a crosslinking agent in the rubber composition, in order to form appropriate crosslinked chains in polymer chains and impart good performance.

[0135] In the rubber composition, the sulfur content is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of the rubber component. The sulfur content is preferably 7.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 4.0 parts by mass or less, and even more preferably 2.0 parts by mass or less. Within the above ranges, the effects tend to be more favorable.

[0136] 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. Commercially available products include those from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more.

[0137] The rubber composition preferably contains a vulcanization accelerator. In the rubber composition, the content of the vulcanization accelerator is not particularly limited and may be freely determined according to the desired vulcanization rate and crosslink density, but is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.3 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, and even more preferably 5.0 parts by mass or less.

[0138] The type of vulcanization accelerator is not particularly limited, and commonly used ones can be used. Examples of the vulcanization accelerator include benzothiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; 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-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; 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, guanidine-based and benzothiazole-based vulcanization accelerators are preferred.

[0139] In addition to the above components, the rubber composition may also contain compounding agents generally used in the tire industry, such as a mold release agent, as appropriate.

[0140] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. The compound of the present invention can be obtained from carbon dioxide by directly converting carbon dioxide or by converting methane obtained through a methanation process in which methane is synthesized from carbon dioxide.

[0141] The above rubber composition is obtained by kneading the above components using a rubber kneading device such as an open roll or a Banbury mixer, and then crosslinking the components, thereby obtaining a crosslinked rubber composition.

[0142] As for kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30 seconds to 30 minutes, preferably 1 minute to 30 minutes. In the finish kneading step in which the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 100°C or lower, preferably room temperature to 80°C. Furthermore, the composition kneaded with the vulcanizing agent and vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200°C, preferably 140 to 180°C.

[0143] The rubber composition (after vulcanization) has a tan δ (70°C tan δ) at 70°C of preferably 0.50 or less, more preferably 0.45 or less, and even more preferably 0.30 or less. Also, it is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.10 or more, even more preferably 0.20 or more, even more preferably 0.23 or more, even more preferably 0.25 or more, and even more preferably 0.27 or more. Within the above ranges, the effect tends to be better.

[0144] In this specification, the tan δ of the above-mentioned rubber composition (rubber composition after vulcanization) at 70°C is measured in accordance with JIS K6394 using a viscoelasticity spectrometer (GABO's "Iplexer Series") under conditions of an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, a temperature of 70°C, and tensile mode. In this measurement, a test piece (length: 20 mm, width: 4 mm, thickness: 1 mm) is sampled from the inner liner. However, if only a test piece less than 1 mm thick can be sampled from the inner liner, the measurement can be performed using this test piece less than 1 mm thick. In this sampling, the length direction of the test piece is aligned with the circumferential direction of the tire, and the thickness direction of the test piece is aligned with the radial direction of the tire. In addition, if sampling from the inner liner is not possible, the test piece can be sampled from a sheet-shaped crosslinked rubber (rubber sheet) obtained by heating the rubber composition at 170°C for 12 minutes.

[0145] Methods known to those skilled in the art can be used to adjust the tan δ of the rubber composition (rubber composition after vulcanization) at 70° C. For example, the adjustment can be made by changing the type and compounding ratio of the rubber components, or by changing the type and compounding amount of the plasticizer and filler.

[0146] The hardness Hs of the rubber composition (rubber composition after vulcanization) is preferably greater than 45, more preferably greater than 47, and even more preferably greater than 50. It is also preferably less than 70, more preferably less than 65, even more preferably less than 60, and even more preferably less than 55. When it is within the above range, the effect tends to be better obtained. In this specification, Hs is a value measured in accordance with JIS K6253-3 (2012), and specifically, is measured by the method described in the examples below.

[0147] The mechanism by which greater effects are obtained when Hs exceeds a certain value, particularly when Hs exceeds 45, is not clear, but it is thought that the greater hardness increases the rigidity of the tire itself.

[0148] The Hs of the rubber composition (rubber composition after vulcanization) can be adjusted by any method known to those skilled in the art, for example, by changing the type and compounding ratio of the rubber components, or by changing the type and compounding amount of the plasticizer and filler.

[0149] It is preferable that the product of the 70°C tan δ (tan δ at 70°C) and the filler content (filler content [parts by mass] per 100 parts by mass of the rubber component) of the above rubber composition (rubber composition after vulcanization) (70°C tan δ × filler content) exceeds 3.0. (70°C tan δ × filler content) is more preferably greater than 3.5, and even more preferably greater than 4.0. The upper limit of (70°C tan δ × filler content) is preferably less than 10.0, more preferably less than 9.5, and even more preferably less than 9.0. Within the above range, better effects tend to be obtained.

[0150] The rubber composition (rubber composition after vulcanization) preferably has a ratio (Hs / 70°C tan δ) of hardness Hs to 70°C tan δ (tan δ at 70°C) of less than 200. (Hs / 70°C tan δ) is more preferably less than 199, even more preferably less than 198, and even more preferably less than 197. The lower limit of (Hs / 70°C tan δ) is preferably more than 100, more preferably more than 130, even more preferably more than 150, and still more preferably more than 170. Within the above range, better effects tend to be obtained.

[0151] The rubber composition (rubber composition after vulcanization) preferably has a product (Hs×24M4DBP) of hardness Hs and 24M4DBP (24M4DBP oil absorption [ml / 100g] of carbon black having a 24M4DBP oil absorption of 170 ml / 100g or more) of more than 7,600. (Hs × 24M4DBP) is more preferably greater than 8000, even more preferably greater than 10000, still more preferably greater than 12000, still more preferably greater than 15000, still more preferably greater than 20000, and still more preferably greater than 21000. The upper limit of (Hs × 24M4DBP) is preferably less than 50000, more preferably less than 40000, still more preferably less than 30000, still more preferably less than 25000, and still more preferably less than 22000. Within the above range, better effects tend to be obtained.

[0152] Although the mechanism by which (Hs × 24M4DBP) exceeds a certain value, particularly when it exceeds 7600, is unclear, it is believed that increasing hardness increases rigidity, and using high-structure carbon black with a high 24M4DBP oil absorption of 170 ml / 100 g or more facilitates interaction between the carbon black and the rubber component, making cracks less likely to occur, and even if they do occur, improving the self-repairing properties of the rubber composition after vulcanization. This is thought to result in further improved crack growth resistance.

[0153] The rubber member (tire member) to which the rubber composition is applied is not particularly limited, and examples thereof include a tread, a sidewall, a wing, a base tread, an undertread, a bead apex, a clinch, and an inner liner. Thus, a tire having a rubber member made of the above rubber composition also constitutes one aspect of this embodiment.

[0154] Among the tire components, it is desirable to apply the rubber composition to an inner liner from the viewpoint of obtaining a greater effect. In this case, the rubber composition for a tire is used as a rubber composition for an inner liner.

[0155] The tire is manufactured by a conventional method using the rubber composition. That is, the composition, to which various additives are optionally blended, is extruded in an uncrosslinked or unvulcanized state to match the shapes of various tire components such as tire surface layer components, molded in a tire building machine by a conventional method, and laminated together with other tire components to form an unvulcanized tire, which is then heated and pressurized in a vulcanizer to manufacture the tire.

[0156] The tire is not particularly limited, and examples thereof include pneumatic tires, solid tires, airless tires, etc. Among these, pneumatic tires are preferred.

[0157] The above-mentioned tires are suitable for use as passenger car tires, large passenger car tires, large SUV tires, truck and bus tires, motorcycle tires, racing tires, winter tires (studless tires, snow tires, studded tires), all-season tires, run-flat tires, aircraft tires, mining tires, etc.

[0158] In the above tire, it is preferable that the ratio (24M4DBP / Tc) of 24M4DBP (the 24M4DBP oil absorption [ml / 100g] of carbon black contained in the above rubber composition having a 24M4DBP oil absorption of 170 ml / 100g or more) to the thickness Tc [mm] of the above rubber member exceeds 68. (24M4DBP / Tc) is more preferably greater than 100, even more preferably greater than 150, and even more preferably greater than 190. The upper limit of (24M4DBP / Tc) is preferably less than 500, more preferably less than 400, even more preferably less than 300, and even more preferably less than 250. Within the above ranges, better effects tend to be obtained.

[0159] Although the mechanism by which a (24M4DBP / Tc) ratio greater than a certain value, especially greater than 68, is not clear, it is believed that the use of high-structure carbon black with a high 24M4DBP oil absorption of 170 ml / 100 g or more enhances the interaction between the carbon black and the rubber component, and by reducing the thickness of the rubber component, the rubber component and the carbon black come into easier contact, enhancing self-repairing properties. This is believed to further improve crack growth resistance.

[0160] In the above tire, it is preferable that the ratio (24M4DBP / Ti) of 24M4DBP (the 24M4DBP oil absorption [ml / 100g] of carbon black contained in the rubber composition for the inner liner and having a 24M4DBP oil absorption of 170 ml / 100g or more) to the thickness Ti [mm] of the inner liner exceeds 68. (24M4DBP / Ti) more preferably exceeds 100, even more preferably exceeds 150, and even more preferably exceeds 190. The upper limit of (24M4DBP / Ti) is preferably less than 500, more preferably less than 400, even more preferably less than 300, and even more preferably less than 250. Within the above range, better effects tend to be obtained.

[0161] Although the mechanism by which a (24M4DBP / Ti) ratio greater than a certain value, especially greater than 68, is more effective is unclear, it is believed that using a high-structure carbon black with a 24M4DBP oil absorption of 170 ml / 100 g or more enhances the interaction between the carbon black and the rubber component, and by reducing the thickness of the inner liner, the rubber component and the carbon black come into easier contact with each other, enhancing self-repairing properties. This is believed to further improve the crack growth resistance of the inner liner.

[0162] In the tire, the thickness Tc [mm] of the rubber member is preferably 0.5 mm or more, more preferably 0.8 mm or more, even more preferably 1.0 mm or more, and still more preferably 2.0 mm or more, and is preferably 10.0 mm or less, more preferably 7.0 mm or less, even more preferably 6.0 mm or less, and particularly preferably 5.0 mm or less. When the thickness is within the above range, better effects tend to be obtained.

[0163] Although the mechanism by which adjusting the thickness Tc of the rubber member within a predetermined range provides a better effect is not clear, keeping the thickness of the rubber member within the predetermined range ensures the rubber strength and crack growth resistance, which is thought to further improve the crack growth resistance.

[0164] In the tire, the thickness Ti [mm] of the inner liner is preferably 0.5 mm or more, more preferably 0.8 mm or more, even more preferably 1.0 mm or more, still more preferably 1.5 mm or more, still more preferably 2.0 mm or more, and is preferably 10.0 mm or less, more preferably 7.0 mm or less, still more preferably 6.0 mm or less, still more preferably 5.0 mm or less, still more preferably 3.5 mm or less, still more preferably 2.5 mm or less. Within the above ranges, the effect tends to be better obtained.

[0165] Although the mechanism by which adjusting the inner liner thickness Ti to a predetermined range provides a better effect is unclear, it is believed that keeping the inner liner thickness within the predetermined range ensures the rubber strength and crack growth resistance, thereby further improving the crack growth resistance.

[0166] In this specification, the thickness Tc of a rubber member means the maximum thickness of each rubber member. The thickness at each point on the surface of each rubber member is the linear distance measured along the normal to the surface of each rubber member at that point, and the thickness Tc of each rubber member is the maximum thickness at that point. "Inner liner thickness Ti" refers to the thickness of the inner liner in the axial direction of the tire at the tire's maximum width position in a radial cross section, and means the linear distance in the axial direction of the tire from the axially outer surface of the inner liner to the axially inner surface of the inner liner at the tire's maximum width position. Here, "inner liner thickness Ti at the tire's maximum width position" is a value measured along the tire axial direction from the axially inner surface of the inner liner at the tire's maximum width position. The term "maximum tire width positions" refers to a pair of positions where the tire has the maximum width in the axial direction.

[0167] In this specification, dimensions such as thickness are measured with the bead portion of the tire aligned to the standard rim width. During measurement, the tire is cut out in the tire radial direction, and both bead ends of the sample are fixed in place with the width of the standard rim.

[0168] In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured under normal conditions. In this specification, the term "normal condition" refers to a state in which the tire is mounted on a normal rim (not shown), inflated to a normal internal pressure, and no load is applied.

[0169] If it is not possible to measure with the tire mounted on a regular rim, the dimensions and angles of each part in the meridian cross section of the tire are measured by cutting the tire along a plane including the axis of rotation, and then matching the distance between the left and right beads in the cross section to the distance between the beads of the tire mounted on a regular rim.

[0170] "Genuine rim" refers to the rim specified for each tire in the standard system that includes the standard on which the tire is based. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the "standard rim" for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organization), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." JATMA, ETRTO, and TRA are referenced in that order, and if an applicable size is available at the time of reference, that standard is followed. For tires not specified in the standard, it refers to the rim that can be mounted on the rim and can maintain internal pressure, i.e., the rim with the smallest rim diameter and the next narrowest rim width, among rims that do not leak air between the rim and tire.

[0171] "Normal internal pressure" refers to the air pressure specified for each tire by each standard in the standard system, including the standard on which the tire is based. For JATMA, it refers to the "Maximum Air Pressure," for ETRTO, it refers to the "INFLATION PRESSURE," and for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with "normal rim," JATMA, ETRTO, and TRA are referenced in that order, and those standards are followed. For tires not specified in a standard, it refers to the normal internal pressure (250 kPa or more) of another tire size (specified in the standard) that is specified using the normal rim as the standard rim. Note that if multiple normal internal pressures of 250 kPa or more are listed, it refers to the smallest value among them.

[0172] In the tire, it is preferable that the ratio (WT / WL) of the tire weight WT [kg] to the tire maximum load capacity WL [kg] is less than 0.0170. (WT / WL) is more preferably less than 0.0160, and even more preferably less than 0.0150. When the lower limit of (WT / WL) is within the above range, preferably more than 0.0010, more preferably more than 0.0050, and even more preferably more than 0.0100, better effects tend to be obtained.

[0173] In this specification, the tire weight WT refers to the weight of the tire itself, excluding the weight of the rim, but includes any components such as sponge or sealant, or sensor components, that may be provided in the tire cavity. The maximum load capacity (normal load) of a tire, WL, is the load specified for each tire by each standard, including the standard on which the tire is based. For JATMA, it is the maximum load capacity, for ETRTO, it is the "LOAD CAPACITY," and for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with the "normal rim" and "normal internal pressure" mentioned above, JATMA, ETRTO, and TRA are referenced in that order and their standards are followed. For tires not specified in a standard, the normal load WL is calculated using the following formula: V={(Dt / 2) 2 -(Dt / 2-Ht) 2}×π×Wt WL=0.000011×V+175 WL: Regular load (kg) V: Virtual volume of the tire (mm 3 ) Dt: Tire outer diameter (mm) Ht: tire section height (mm) Wt: tire cross-sectional width (mm)

[0174] The "section width Wt (mm)" of a tire is the maximum width between the outer surfaces of the sidewalls in the normal state, excluding any patterns or lettering on the sidewalls.

[0175] The "outer diameter Dt (mm)" of a tire refers to the outer diameter of the tire in its normal state.

[0176] The "section height Ht (mm)" of a tire refers to the height in the radial direction of the tire in its radial cross section, and is equivalent to half the difference between the tire's outer diameter Dt and the rim diameter R, where R (mm) is the tire's rim diameter. In other words, the section height Ht can be calculated by (Dt-R) / 2.

[0177] In the above tire, the tire cross-sectional width Wt [mm] is preferably 260 mm or less, more preferably 255 mm or less, and even more preferably 250 mm or less. The lower limit is preferably 150 mm or more, more preferably 180 mm or more, and even more preferably 200 mm or more. Within the above range, the effect tends to be more favorable.

[0178] An example of a tire according to the present invention will be described below with reference to the drawings, but the present invention is not limited to this example.

[0179] 1, the up-down direction is the radial direction of the tire 2, the left-right direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. The tire 2 is bilaterally symmetrical. The tread 4 includes a cap layer 30 and a base layer 28.

[0180] Although FIG. 1 shows an example of a two-layer tread structure consisting of a cap layer 30 and a base layer 28, a single-layer tread or a tread having a structure of three or more layers may also be used.

[0181] In the tire 2, each sidewall 6 extends from an end of the tread 4 substantially radially inward.

[0182] A radially outer portion of the sidewall 6 is joined to the tread 4. A radially inner portion of the sidewall 6 is joined to the clinch 10. The sidewall 6 can prevent damage to the carcass 14.

[0183] 1 is located between the tread 4 and the sidewall 6. The wing 8 is joined to each of the tread 4 and the sidewall 6.

[0184] Each clinch 10 is located approximately radially inward of the sidewall 6 and has at least one or more portions that come into contact with the rim.

[0185] The carcass 14 includes a carcass ply 36. In the tire 2, the carcass 14 is made up of one carcass ply 36, but may be made up of two or more carcass plies.

[0186] In the tire 2, the carcass ply 36 is laid between the bead cores 32 on both sides and extends along the tread 4 and the sidewall 6. The carcass ply 36 is folded back from the inside to the outside in the axial direction around each bead core 32. This folding back forms a main portion 36a and a pair of folded-back portions 36b in the carcass ply 36. That is, the carcass ply 36 includes the main portion 36a and the pair of folded-back portions 36b.

[0187] Each bead core 32 includes a bead apex 34 extending radially outward from the bead core 32. The bead core 32 is preferably ring-shaped and includes a wound, non-stretchable wire. The bead apex 34 tapers radially outward.

[0188] Although not shown, the carcass ply 36 preferably comprises a large number of parallel cords and a topping rubber. The absolute value of the angle that each cord forms with respect to the equatorial plane CL is preferably 75° to 90°. In other words, the carcass 14 preferably has a radial structure.

[0189] The belt layer 16 in FIG. 1 is located radially inward of the tread 4. The belt layer 16 is laminated with the carcass 14. The belt layer 16 reinforces the carcass 14. In the tire 2 in FIG. 1, the belt layer 16 is made up of an inner layer 38 and an outer layer 40. As is clear from FIG. 1, it is desirable that the width of the inner layer 38 is slightly larger than the width of the outer layer 40 in the axial direction. In this tire 2, the axial width of the belt layer 16 is preferably 0.6 times or more and 0.9 times or less the cross-sectional width of the tire 2.

[0190] Each of the inner layer 38 and the outer layer 40 preferably comprises a number of parallel-arranged single steel cords (steel monofilaments) and a topping rubber (coating rubber). In other words, the belt layer 16 includes a number of parallel-arranged steel monofilaments.

[0191] 1 is located radially outside the belt layer 16. In the axial direction, the band 18 has a width equal to the width of the belt layer 16. The band 18 may also have a width greater than the width of the belt layer 16.

[0192] Although not shown, the band 18 is preferably made of a cord and a topping rubber. The cord is wound spirally. This band 18 has a so-called jointless structure. The cord extends substantially in the circumferential direction. The angle of the cord with respect to the circumferential direction is preferably 5° or less, and more preferably 2° or less. The cord restrains the belt layer 16, thereby suppressing lifting of the belt layer 16.

[0193] 1 constitute a reinforcing layer. The reinforcing layer may be constituted by the belt layer 16 alone.

[0194] FIG. 2 is an enlarged view of the vicinity of the tread 4 in FIG. The tire in FIG. 2 is a tire 2 having a groove 26 on the tire equatorial plane (CL).

[0195] The inner liner 20 is located inside the carcass 14. The inner liner 20 is joined to the inner surface of the carcass 14. The inner liner 20 maintains the internal pressure of the tire 2.

[0196] The tire 2 has an inner liner 20 made of a rubber composition containing a rubber component including a butyl rubber, a cyclic amine having a double bond in the ring, and carbon black having a 24M4DBP oil absorption of 170 ml / 100 g or more.

[0197] Each chafer 22 is located near a bead 12. In this embodiment, the chafer 22 is preferably made of a cloth with rubber impregnated into the cloth. The chafer 22 may be integral with the clinch 10.

[0198] In this tire 2, the tread 4 has main grooves 42 as the grooves 26. As shown in FIG. 1 , a plurality of main grooves 42, specifically three main grooves 42, are formed in the tread 4. These main grooves 42 are spaced apart in the axial direction. The three main grooves 42 formed in the tread 4 form four ribs 44 extending in the circumferential direction. In other words, the spaces between the ribs 44 constitute the main grooves 42.

[0199] Each main groove 42 extends in the circumferential direction. The main grooves 42 are continuous and uninterrupted in the circumferential direction. The main grooves 42 facilitate the drainage of water present between the road surface and the tire 2, for example, in rainy weather. This allows the tire 2 to maintain sufficient contact with the road surface even when the road surface is wet.

[0200] The tire 2 in FIG. 1 has a maximum tire width position M on the surface of the sidewall 6 . With regard to the 24M4DBP oil absorption (24M4DBP) of the carbon black contained in the inner liner 20 having a 24M4DBP oil absorption of 170 ml / 100 g or more, the thickness Ti of the inner liner in the axial direction of the tire at the tire's maximum width position M, the tire weight WT, and the tire's maximum load capacity WL, it is desirable that 24M4DBP / Ti, 24M4DBP, Ti, WT / WL, WT, and WL be within the aforementioned ranges. [Example]

[0201] Below, examples (embodiments) that are considered preferable for implementation will be shown, but the scope of the present invention is not limited to the examples.

[0202] The various chemicals used in tire manufacturing are summarized below. If necessary, the chemicals may be refined according to standard methods. Halogenated butyl rubber: Bromobutyl rubber 2255 (brominated butyl rubber) manufactured by ExxonMobil Corporation Carbon black 1: Cabot Japan Co., Ltd.'s Show Black N220 (24M4DBP: 98ml / 100g, N2SA: 115ml) 2 / g) Carbon Black 2: Orion Engineered Carbons Printex XE2B (24M4DBP: 420ml / 100g) Stearic acid: NOF Corporation's "Tsubaki" stearic acid 1-Butylimidazole: Tokyo Chemical Industry Co., Ltd. 1-Methylimidazole: Tokyo Chemical Industry Co., Ltd. 1-nonylimidazole: Tokyo Chemical Industry Co., Ltd. 4-Dimethylaminopyridine: Tokyo Chemical Industry Co., Ltd. Zinc oxide: Zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (powdered sulfur containing 5% oil) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noccela M (2-mercaptobenzothiazole) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccela DM (di-2-benzothiazolyl disulfide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0203] <Preparation of rubber composition and rubber sheet> According to the formulation shown in Table 1, materials other than sulfur and vulcanization accelerator are kneaded for 5 minutes at 150°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded mixture. Sulfur and a vulcanization accelerator are added to the kneaded mixture, and the mixture is kneaded for 5 minutes at 80°C using an open roll to obtain an unvulcanized rubber composition. The unvulcanized rubber composition is press-vulcanized at 170°C for 12 minutes to obtain a vulcanized rubber sheet.

[0204] <Preparation of test tires> According to the specifications in Table 1, the unvulcanized rubber composition was molded into the shape of an inner liner, and the unvulcanized rubber composition was laminated together with other tire components in a tire building machine to form an unvulcanized tire. The unvulcanized tire was then vulcanized at 170°C for 10 minutes to produce a test tire (size 215 / 45R17 (outer diameter Dt: 624 mm, inner diameter r: 430 mm, section width Wt: 215 mm, maximum load capacity WL: 480 kg), tire weight WT: 6.2 kg, inner liner thickness Ti: 2.0 mm, passenger car tire, FIGS. 1 and 2).

[0205] Table 1 shows the results of calculations based on the following evaluation methods, assuming vulcanized rubber sheets and test tires obtained from compositions whose formulations and specifications were changed according to Table 1.

[0206] <hs> A test specimen is cut out from the inner liner of the test tire. Then, Hs of the test specimen is measured using a Type A durometer in accordance with JIS K6253-3 (2012) "Vulcanized rubber and thermoplastic rubber - Determination of hardness - Part 3: Durometer hardness." The measurement is performed at 25°C.

[0207] <Hardness index> The Hs value measured by the above-mentioned method is expressed as an index (hardness index) with the reference comparative example (Comparative Example 3) set at 100. A larger index indicates better hardness.

[0208] <Viscoelasticity measurement> In accordance with the provisions of JIS K6394, a viscoelasticity spectrometer (GABO's "Iplexer Series") is used to measure the loss tangent (tanδ) under the conditions of an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, a temperature of 70°C, and tension mode. Test specimens (length: 20 mm, width: 4 mm, thickness: 1 mm) are sampled from the inner liner of the test tire. When sampling, the length direction of the test specimen is aligned with the circumferential direction of the tire, and the thickness direction of the test specimen is aligned with the radial direction of the tire.

[0209] <Crack growth test> A test piece (length: 100 mm, width: 50 mm, thickness: 2.0 mm) was sampled from a vulcanized rubber sheet, and an initial scratch of 5.0 mm was made on both sides of the center in the lengthwise direction. The sample with the initial scratch was bent at 40% strain using a De Mattia testing machine, and the number of times it was bent until it broke was measured. The number of times it was bent until it broke in the reference comparative example (Comparative Example 3) was set to 100, and the result was expressed as an index (crack growth index A). A higher index A indicates better crack growth resistance.

[0210] <Overall performance> The overall performance of hardness and crack growth resistance is evaluated by the sum of the hardness index and the crack growth resistance index A. The larger the value, the better the overall performance.

[0211] [Table 1]

[0212] The present invention (1) is a rubber composition comprising a rubber component containing a butyl rubber, a cyclic amine having a double bond in the ring, and carbon black having a 24M4DBP oil absorption of 170 ml / 100 g or more.

[0213] The present invention (2) is the rubber composition according to the present invention (1), wherein the hardness Hs of the rubber composition exceeds 45.

[0214] The present invention (3) is the rubber composition according to the present invention (1) or (2), wherein the content of the filler in the rubber composition is less than 40 parts by mass per 100 parts by mass of the rubber component.

[0215] The present invention (4) is a rubber composition of any combination with any of the present inventions (1) to (3), in which the product of tan δ at 70°C (70°C tan δ) and the filler content [parts by mass] (filler content) per 100 parts by mass of the rubber component (70°C tan δ × filler content) exceeds 3.0.

[0216] The present invention (5) is a rubber composition in any combination with any of the present inventions (1) to (4), wherein the ratio (Hs / 70°C tanδ) of hardness Hs to tanδ at 70°C (70°C tanδ) in the rubber composition is less than 200.

[0217] The present invention (6) is a rubber composition in any combination with any of the present inventions (1) to (5), in which the product (Hs × 24M4DBP) of hardness Hs and 24M4DBP oil absorption [ml / 100g] (24M4DBP) of carbon black having a 24M4DBP oil absorption of 170 ml / 100g or more exceeds 7,600.

[0218] The present invention (7) is a tire having a rubber member made of a rubber composition in any combination with any of the present inventions (1) to (6).

[0219] The present invention (8) is a tire according to the present invention (7), in which the ratio (24M4DBP / Tc) of the 24M4DBP oil absorption [ml / 100g] (24M4DBP) of carbon black having a 24M4DBP oil absorption of 170 ml / 100g or more contained in the rubber composition constituting the rubber member to the thickness Tc [mm] of the rubber member exceeds 68.

[0220] The present invention (9) is the tire according to the present invention (7) or (8), in which the ratio (WT / WL) of the tire weight WT [kg] to the tire maximum load capacity WL [kg] is less than 0.0170.

[0221] The present invention (10) is a tire in any combination with any of the present inventions (7) to (9), in which the ratio (WT / WL) of the tire weight WT [kg] to the tire's maximum load capacity WL [kg] is less than 0.0150.

[0222] The present invention (11) is a tire in any combination with any of the present inventions (7) to (10), in which the ratio (WT / WL) of the tire weight WT [kg] to the tire maximum load capacity WL [kg] is less than 0.0130.

[0223] The present invention (12) is a tire in any combination with any of the present inventions (7) to (11), in which the rubber member is an inner liner.

[0224] The present invention (13) is directed to a rubber member comprising an inner liner, The tire is any combination with any of the present inventions (7) to (12), wherein the thickness Ti [mm] of the inner liner is 1.5 to 2.5 mm.

[0225] The present invention (14) is a tire in any combination with any of the present inventions (7) to (13), wherein the tire has a section width Wt [mm] of 250 mm or less. [Explanation of symbols]

[0226] 2 tires 4 Tread 6 Sidewall 8 Wing 10 Clinch 12 beads 14 Carcass 16 Belt Layer 18 bands 20 Inner liner 22 Chafer 24 Tread surface 26 Groove 28 base layer 30 cap layers 32 bead core 34 Bead Apex 36 Carcass ply 36a Main part 36b Folded part 38 Inner layer 40 outer layer 42 Main groove 44 Ribs CL Tire equatorial plane M Maximum tire width position Ti Thickness of the inner liner at the widest point of the tire< / hs>

Claims

1. A rubber composition comprising a rubber component containing a butyl rubber, a cyclic amine having a double bond in the ring, and carbon black having a 24M4DBP oil absorption of 170 ml / 100 g or more.

2. The rubber composition according to claim 1, having a hardness Hs of more than 45.

3. 2. The rubber composition according to claim 1, wherein the content of the filler is less than 40 parts by mass per 100 parts by mass of the rubber component.

4. The rubber composition according to claim 1, wherein the product (70°C tanδ x filler content) of tanδ at 70°C (70°C tanδ) and the filler content [parts by mass] (filler content) per 100 parts by mass of the rubber component exceeds 3.

0.

5. 2. The rubber composition according to claim 1, wherein the ratio (Hs / 70°C tan δ) of hardness Hs to tan δ at 70°C (70°C tan δ) is less than 200.

6. 2. The rubber composition according to claim 1, wherein the product (Hs x 24M4DBP) of hardness Hs and 24M4DBP oil absorption [ml / 100g] (24M4DBP) of carbon black having a 24M4DBP oil absorption of 170 ml / 100g or more exceeds 7,600.

7. A tire having a rubber component made of the rubber composition according to claim 1.

8. 8. The tire according to claim 7, wherein the ratio (24M4DBP / Tc) of the 24M4DBP oil absorption [ml / 100g] (24M4DBP) of carbon black having a 24M4DBP oil absorption of 170 ml / 100g or more contained in the rubber composition constituting the rubber member to the thickness Tc [mm] of the rubber member exceeds 68.

9. 8. The tire according to claim 7, wherein a ratio (WT / WL) of a weight WT [kg] of the tire to a maximum load capacity WL [kg] of the tire is less than 0.0170.

10. 8. The tire according to claim 7, wherein a ratio (WT / WL) of a weight WT [kg] of the tire to a maximum load capacity WL [kg] of the tire is less than 0.0150.

11. 8. The tire according to claim 7, wherein a ratio (WT / WL) of a weight WT [kg] of the tire to a maximum load capacity WL [kg] of the tire is less than 0.0130.

12. 8. The tire according to claim 7, wherein the rubber member is an inner liner.

13. The rubber member is an inner liner, The tire according to claim 7, wherein the thickness Ti [mm] of the inner liner is 1.5 to 2.5 mm.

14. 8. The tire according to claim 7, wherein the tire has a cross-sectional width Wt [mm] of 250 mm or less.

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