Tire

Abstract

To provide a tire that is excellent in integrated performance of low-fuel economy, steering stability and noise reduction performance at the time of running.SOLUTION: The tire comprises an inner liner constituted of a rubber composition for the inner liner including butyl-based rubber and micro-fibrillated plant fiber. The product (A×T) of an average fiber diameter A (nm) of the micro-fibrillated plant fiber and a side thickness T (mm) at a tire maximum width position is 5000 or less and the side thickness T (mm) at the tire maximum width position is 10 mm or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Tires are required to have various performance characteristics, such as low fuel consumption, steering stability, and noise reduction during driving (see Patent Document 1). [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 tire that is excellent in overall performance in terms of fuel economy, steering stability, and noise reduction during driving. [Means for solving the problem]

[0005] The present invention provides a tire having an inner liner made of a rubber composition for an inner liner containing a butyl rubber and microfibrillated plant fibers, the product (A × T) of the average fiber diameter A (nm) of the microfibrillated plant fibers and the side thickness T (mm) at the maximum width position of the tire is 5000 or less, The tire has a side thickness T (mm) at the tire's maximum width position of 10 mm or less. [Effects of the Invention]

[0006] The present invention provides a tire having an inner liner made of a rubber composition for an inner liner that contains butyl rubber and microfibrillated plant fibers, in which the product (A x T) of the average fiber diameter A (nm) of the microfibrillated plant fibers and the side thickness T (mm) at the tire's maximum width position is 5000 or less, and the side thickness T (mm) at the tire's maximum width position is 10 mm or less, thereby providing a tire that has excellent overall performance in terms of fuel efficiency, handling stability, and noise reduction during driving. [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] The tire has an inner liner made of a rubber composition containing butyl rubber and microfibrillated plant fibers, and satisfies the relationship that the product (A × T) of the average fiber diameter A (nm) of the microfibrillated plant fibers and the side thickness T (mm) at the maximum width position of the tire is 5000 or less, and the side thickness T (mm) at the maximum width position of the tire is 10 mm or less.

[0009] The reason why the above-mentioned effects are obtained by the above tire is not entirely clear, but is presumed to be as follows. Generally, reducing the thickness of the side portion at the widest point of the tire is advantageous for fuel economy because it makes it harder for heat to accumulate, but it tends to be disadvantageous in terms of handling stability and noise reduction. In the above tire, by reducing the thickness of the side portion and the average fiber diameter of the microfibrillated plant fibers, heat accumulation in the side portion can be suppressed. Furthermore, the smaller the average fiber diameter of the microfibrillated plant fibers, the larger the specific surface area, which increases the number of constraint points with the rubber component and increases the rigidity of the inner liner. Furthermore, the microfibrillated plant fibers blended into the inner liner can reduce noise generated by the tire. As a result, steering stability and noise reduction can be improved. Therefore, it is presumed that the overall performance of handling stability, fuel economy, and noise reduction will be improved by providing an inner liner made of a rubber composition containing microfibrillated plant fibers and satisfying the relationship of A (nm) × T (mm) being 5000 or less and T being 10 mm or less.

[0010] In this way, the tire solves the problem (objective) of improving the overall performance of fuel economy, handling stability, and noise reduction during driving by satisfying the relationships "A×T≦5000" and "T≦10." In other words, the parameters "A×T≦5000" and "T≦10" do not define the problem (objective); the object of the present application is to improve the overall performance of fuel economy, handling stability, and noise reduction during driving, and the tire is configured to satisfy these parameters as a means to achieve this.

[0011] The tire includes an inner liner.

[0012] In this specification, an inner liner is a member formed to form the inner cavity surface of a tire, and this member reduces the amount of air permeation and can maintain the tire internal pressure. Specifically, this is the member shown in Figure 1 of JP 2008-291091 A, Figures 1 and 2 of JP 2007-160980 A, etc.

[0013] In the tire, the inner liner is made of a rubber composition for an inner liner. The tire also usually includes a sidewall, and the sidewall is made of a rubber composition for a sidewall.

[0014] Materials that can be used in common for the rubber composition for the inner liner and the rubber composition for the sidewall will be described below.

[0015] (rubber component) The rubber composition for the inner liner and the rubber composition for the sidewall each contain 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 25°C.

[0016] 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 favorably obtained.

[0017] 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).

[0018] The rubber component usable in the rubber composition for the inner liner and the rubber composition for the sidewall 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.

[0019] 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.

[0020] Examples of rubber components that can be used in the rubber composition for the inner liner and the rubber composition for the sidewall include diene rubbers. Examples of diene rubbers 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 butyl rubber and fluororubber. These may be used alone or in combination of two or more. 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] pMC is the modern standard reference 14 of sample against C concentration14 This 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.

[0028] 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.

[0029] 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.

[0030] 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.14 The 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.

[0031] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal circumstances, it will usually not reach 100, and will show a value of approximately 110 pMC. 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 about 0 pMC (for example, 0.3 pMC), which corresponds to the biomass ratio of 0% mentioned above.

[0032] 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.

[0033] In particular, from the viewpoint of obtaining a greater effect, the rubber composition for an inner liner contains a butyl-based rubber, but may further contain an isoprene-based rubber. From the viewpoint of obtaining better effects, the rubber composition for a sidewall preferably contains at least one of an isoprene-based rubber and a BR, and more preferably contains both an isoprene-based rubber and a BR.

[0034] Specific examples of the butyl-based 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-based rubbers include ExxonMobil's Exprobutyl and Chlorobutyl HT1068. The butyl-based 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.

[0035] The rubber composition for an inner liner contains a butyl rubber as a rubber component, and either an unmodified butyl rubber or a modified butyl rubber can be used as the 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.

[0036] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. NRs such as SIR20, RSS#3, and TSR20 are commonly used in the rubber industry. IRs are not particularly limited, and examples of IRs such as IR2200 are commonly used in the rubber industry. Modified NRs include deproteinized natural rubber (DPNR) and high-purity natural rubber. Modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

[0037] The 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.

[0038] 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)).

[0039] 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.

[0040] The 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.

[0041] The styrene content of the SBR is preferably 5% by mass or more, more preferably 20% by mass or more, and even more preferably 23.5% 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 styrene content is 1 It can be measured by H-NMR measurement.

[0042] 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)).

[0043] The vinyl bond content of SBR is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. When the vinyl bond content is within the above range, that is, preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less, better effects tend to be obtained. In this specification, the vinyl bond amount (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectroscopy.

[0044] 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])}.

[0045] 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.

[0046] In the rubber composition for an inner liner, the content of the butyl rubber in 100% by mass of the rubber component is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, and may be 100% by mass. When it is within the above range, the effects tend to be favorably obtained.

[0047] Although the mechanism by which a butyl rubber content of a certain amount or more, particularly 90% by mass or more, is more effective is unclear, it is believed that the microfibrillated plant fibers effectively bind and harden the butyl rubber, improving handling stability, and therefore significantly improving the overall performance of fuel economy, handling stability, and noise reduction during driving.

[0048] In the rubber composition for an inner liner, the content of the halogenated butyl rubber in 100% by mass of the rubber component is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, and may be 100% by mass. Within the above range, the effects tend to be favorably obtained.

[0049] In the rubber composition for an inner liner, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, and may be 0% by mass. When the content is within the above range, better effects tend to be obtained.

[0050] In the rubber composition for an inner liner, the content of BR in 100% by mass of the rubber component is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, and may be 0% by mass. When it is within the above range, better effects tend to be obtained.

[0051] In the rubber composition for an inner liner, the content of SBR in 100% by mass of the rubber component is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, and may be 0% by mass. When the content is within the above range, better effects tend to be obtained.

[0052] In the rubber composition for sidewalls, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. Within the above ranges, better effects tend to be obtained.

[0053] In the rubber composition for sidewalls, the BR content in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. Within the above ranges, better effects tend to be obtained.

[0054] In the rubber composition for sidewalls, the content of SBR in 100% by mass of the rubber component is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, and may be 0% by mass. When it is within the above range, better effects tend to be obtained.

[0055] In the rubber composition for a sidewall, from the viewpoint of obtaining better effects, the total content of the isoprene-based rubber and the BR in 100% by mass of the rubber component is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, and may be 100% by mass.

[0056] (filler) In the rubber composition for an inner liner and the rubber composition for a sidewall, usable fillers are not particularly limited, and materials known in the rubber field can be used. Examples include inorganic fillers such as carbon black, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica, and poorly dispersible fillers such as biochar, microfibrillated plant fiber, short fiber cellulose, and gel-like compounds. In particular, from the viewpoint of obtaining better effects, the rubber composition for the inner liner contains microfibrillated plant fibers, but it is preferable that it further contains at least one of carbon black, silica, and clay, more preferably at least one of carbon black and clay, and even more preferably carbon black. From the viewpoint of obtaining a better effect, the rubber composition for a sidewall preferably contains at least one of carbon black and silica, and more preferably contains carbon black. The above fillers may be used alone or in combination of two or more kinds.

[0057] 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 and acetic acid bacteria. The microfibrillated plant fibers may be used singly or in combination of two or more.

[0058] 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.

[0059] The method for producing the microfibrillated plant fibers is not particularly limited, but examples include a method in which a raw material for cellulose microfibrils is chemically treated, if necessary, with an alkali such as sodium hydroxide, and then mechanically ground or beaten using a refiner, twin-screw kneader (twin-screw extruder), twin-screw kneader / extruder, high-pressure homogenizer, media-agitating mill, millstone, grinder, vibrating mill, sand grinder, or the like. These methods separate lignin from the raw material by chemical treatment, thereby obtaining microfibrillated plant fibers that are substantially free of lignin. Another example is a method in which the raw material for cellulose microfibrils is subjected to ultra-high pressure treatment.

[0060] As the microfibrillated plant fibers, for example, products available from Sugino Machine Ltd., Daicel FineChem Ltd., etc. can be used.

[0061] The microfibrillated plant fibers may be unmodified microfibrillated plant fibers obtained by the above-mentioned production methods, or may be microfibrillated plant fibers that have been subjected to oxidation treatment or various chemical modification treatments, or microfibrillated plant fibers that have been subjected to oxidation treatment or various chemical modification treatments using natural materials from which cellulose microfibrils can be derived (e.g., wood, pulp, bamboo, hemp, jute, kenaf, agricultural waste, cloth, paper, sea squirt cellulose, etc.) as cellulose raw materials, followed by defibration treatment as needed. For example, microfibrillated compounds that have been subjected to oxidation treatment can be preferably used.

[0062] Examples of chemical modification of the microfibrillated plant fibers include esterification, etherification, and acetalization. Specific examples include acylation such as acetylation, cyanoethylation, amination, sulfone esterification, phosphate esterification, alkyl esterification, alkyl etherification, complex esterification, β-keto esterification, alkylation such as butylation, and chlorination. Further examples include alkyl carbamate and aryl carbamate. All chemical modification treatments are treatments that render microfibrillated plant fibers hydrophobic, and the use of microfibrillated plant fibers that have been subjected to such chemical modification treatments tends to improve the dispersibility of the microfibrillated plant fibers.

[0063] Such chemically modified microfibrillated plant fibers (hereinafter also referred to as chemically modified microfibrillated plant fibers) preferably have a degree of substitution of 0.3 or more, more preferably 0.4 or more, even more preferably 0.5 or more, and preferably 2.5 or less, more preferably 2.3 or less, even more preferably 2.0 or less. Here, the degree of substitution refers to the average number of hydroxyl groups per glucose ring unit of cellulose that have been substituted with other functional groups by chemical modification, and the theoretical maximum value is 3. When the above chemically modified microfibrillated plant fibers are a combination of two or more types, the degree of substitution is calculated as the average for all of the chemically modified microfibrillated plant fibers.

[0064] The degree of substitution in the chemically modified microfibrillated plant fibers can be confirmed, for example, by titration using 0.5N-NaOH and 0.2N-HCl, or by measurement such as NMR or infrared absorption spectroscopy.

[0065] When the chemically modified microfibrillated plant fiber is an acetylated microfibrillated plant fiber, the degree of substitution is preferably 0.3 or more and preferably 2.5 or less. When the aminated microfibrillated plant fiber is an aminated microfibrillated plant fiber, the degree of substitution is preferably 0.3 or more and preferably 2.5 or less. When the sulfone esterified microfibrillated plant fiber is an aminated microfibrillated plant fiber, the degree of substitution is preferably 0.3 or more and preferably 1.8 or less. When the alkyl esterified microfibril cellulose is an aminated microfibril cellulose, the degree of substitution is preferably 0.3 or more and preferably 1.8 or less. When the complex esterified microfibril cellulose is an aminated microfibril cellulose, the degree of substitution is preferably 0.4 or more and preferably 1.8 or less. When the β-keto esterified microfibril cellulose is an aminated microfibril cellulose, the degree of substitution is preferably 0.3 or more and preferably 1.8 or less. When the alkyl carbamate microfibril cellulose is an aminated microfibril cellulose, the degree of substitution is preferably 0.3 or more and preferably 1.8 or less. When the aryl carbamate microfibril cellulose is an aminated microfibril cellulose, the degree of substitution is preferably 0.3 or more and preferably 1.8 or less.

[0066] The acetylation can be carried out, for example, by adding acetic acid, concentrated sulfuric acid, or acetic anhydride to the microfibrillated plant fiber to cause a reaction. Specifically, the acetylation can be carried out by a conventionally known method, such as by reacting the microfibrillated plant fiber with acetic anhydride in a mixed solvent of acetic acid and toluene in the presence of a sulfuric acid catalyst to cause the acetylation reaction to proceed, and then replacing the solvent with water.

[0067] The above amination can be carried out by a known method, for example, a method in which the tosyl ester is converted into a tosyl ester, followed by reaction with an alkylamine in an alcohol to cause a nucleophilic substitution reaction.

[0068] The sulfonation can be carried out by a simple procedure, for example, by dissolving the microfibrillated plant fibers in sulfuric acid and then adding the resulting solution to water. Alternatively, the sulfonation can be carried out by treatment with anhydrous sulfuric acid gas or treatment with chlorosulfonic acid and pyridine.

[0069] The phosphate esterification can be carried out, for example, by treating microfibrillated plant fibers that have been treated with dimethylamine or the like with phosphoric acid and urea.

[0070] The alkyl esterification can be carried out, for example, by the Schotten-Baumann method, in which microfibrillated plant fibers are reacted with a carboxylic acid chloride under basic conditions, and the alkyl etherification can be carried out by the Williamson method, in which microfibrillated plant fibers are reacted with an alkyl halide under basic conditions.

[0071] The chlorination can be carried out, for example, by adding thionyl chloride in DMF (dimethylformamide) and heating.

[0072] The complex esterification can be carried out, for example, by reacting the microfibrillated plant fiber with two or more types of carboxylic acid anhydrides or carboxylic acid chlorides under basic conditions.

[0073] The β-ketoesterification can be carried out, for example, by reacting the microfibrillated plant fiber with diketene or alkylketene dimer, or by transesterification of the microfibrillated plant fiber with a β-ketoester compound such as alkylacetoacetate.

[0074] The alkyl carbamate formation can be carried out, for example, by reacting the microfibrillated plant fiber with an alkyl isocyanate in the presence of a basic catalyst or a tin catalyst.

[0075] The aryl carbamate formation can be carried out, for example, by reacting the microfibrillated plant fiber with an aryl isocyanate in the presence of a basic catalyst or a tin catalyst.

[0076] Examples of the oxidation treatment of the microfibrillated plant fibers include oxidation treatment using an N-oxyl compound, etc. From the viewpoint of obtaining better effects, microfibrillated plant fibers that have been subjected to oxidation treatment using an N-oxyl compound can also be preferably used.

[0077] As the microfibrillated plant fiber oxidized using the above-mentioned N-oxyl compound, one having a cellulose type I crystal structure and in which the primary hydroxyl group at carbon 6 of the pyranose ring of cellulose is surface-oxidized to a carboxyl group, an aldehyde group, or a salt thereof is preferably used. Such specific microfibrillated plant fibers are disclosed in, for example, JP 2008-001728 A. Here, the pyranose ring is a six-membered carbohydrate consisting of five carbons and one oxygen atom. During the oxidation reaction of cellulose using an N-oxyl compound, the primary hydroxyl group at carbon 6 of the pyranose ring of cellulose is selectively oxidized. That is, natural cellulose is in the form of nanofibers at the time of biosynthesis, but these nanofibers converge through hydrogen bonding to form fiber bundles. When cellulose fibers are oxidized using an N-oxyl compound, the primary hydroxyl group at carbon 6 of the pyranose ring is selectively oxidized, and this oxidation reaction is limited to the surface of the microfibrils, resulting in the introduction of carboxyl groups at a high density only on the surface of the microfibrils. Carboxyl groups are negatively charged and repel each other, preventing aggregation of microfibrils when dispersed in water, resulting in the fiber bundles being broken down into microfibril units, forming cellulose nanofibers. In terms of achieving better results, cellulose in which the primary hydroxyl group at carbon 6 in the pyranose ring has been surface-oxidized to a carboxyl group is preferred.

[0078] The sum of the amounts of carboxyl groups and aldehyde groups present in the microfibrillated plant fibers oxidized with the N-oxyl compound is preferably 0.1 mmol / g or more, more preferably 0.2 mmol / g or more, and preferably 2.5 mmol / g or less, more preferably 2.2 mmol / g or less, based on the weight (bone dry) of the cellulose fibers. Within the above ranges, the nanofibers can be dispersed more uniformly. In this specification, the above sum is expressed as the amount of charge in the microfibrillated plant fiber. "Bone-dry" refers to a state in which cellulose fibers account for 100% of the total weight.

[0079] In particular, the amount of carboxyl groups is preferably 0.1 mmol / g or more, more preferably 0.2 mmol / g or more, and preferably 2.4 mmol / g or less, more preferably 2.1 mmol / g or less, based on the weight (bone dry) of the cellulose fiber. Introducing carboxyl groups within the above range generates an electrical repulsive force, which defibrates the microfibrils, resulting in more uniform dispersion of the nanofibers.

[0080] In addition, known methods can be used to identify whether the microfibrillated plant fibers oxidized using the above-mentioned N-oxyl compound have a type I crystal structure and to quantify the amount of aldehyde groups and carboxyl groups (mmol / g). For example, analysis can be performed using the method described in JP 2008-001728 A.

[0081] Microfibrillated plant fibers that have been oxidized using the above-mentioned N-oxyl compound can be prepared, for example, by a process that includes an oxidation reaction step in which natural cellulose is used as a raw material and the natural cellulose is oxidized in water using an N-oxyl compound as an oxidation catalyst and a co-oxidant to obtain reaction product fibers; a purification step in which impurities are removed to obtain reaction product fibers impregnated with water; and a dispersion step in which the water-impregnated reaction product fibers are dispersed in a solvent.

[0082] First, in the oxidation reaction step, a dispersion of natural cellulose in water is prepared. Examples of natural cellulose include purified cellulose isolated from cellulose biosynthesis systems such as plants, animals, and bacteria-produced gels. Natural cellulose can also be subjected to treatments such as beating to increase its surface area. It is also possible to use natural cellulose that has been stored in Never Dry after isolation and purification. The dispersion medium for natural cellulose in the reaction is water, and the concentration of natural cellulose in the reaction aqueous solution is usually about 5% or less.

[0083] An N-oxyl compound that can be used as a cellulose oxidation catalyst refers to a compound that can generate a nitroxy radical, and includes, for example, a heterocyclic compound that generates a nitroxy radical and has an alkyl group having 1 to 4 carbon atoms at the α-position of the amino group, as represented by the following formula (1):

[0084] [ka]

[0085] In the above formula (1), R 1 ~R 4 represents the same or different alkyl groups having 1 to 4 carbon atoms.

[0086] Among the compounds that generate the nitroxy radical represented by the above formula (1), 2,2,6,6-tetraalkylpiperidine-1-oxyl and its derivatives, such as 4-hydroxy-2,2,6,6-tetraalkylpiperidine-1-oxyl, 4-alkoxy-2,2,6,6-tetraalkylpiperidine-1-oxyl, 4-benzoyloxy-2,2,6,6-tetraalkylpiperidine-1-oxyl, and 4-amino-2,2,6,6-tetraalkylpiperidine-1-oxyl, are more preferred, and among these, 2,2,6,6-tetramethylpiperidine-1-oxyl (hereinafter also referred to as TEMPO) is particularly preferred. TEMPO) and its derivatives, such as 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (hereinafter also referred to as 4-hydroxyTEMPO), 4-alkoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (hereinafter also referred to as 4-alkoxyTEMPO), 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (hereinafter also referred to as 4-benzoyloxyTEMPO), and 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (hereinafter also referred to as 4-aminoTEMPO), are more preferred, and derivatives of these can also be used. Of these, TEMPO is more preferred from the viewpoint of activity.

[0087] Examples of derivatives of 4-hydroxyTEMPO include derivatives obtained by etherifying the hydroxyl group of 4-hydroxyTEMPO with an alcohol having a linear or branched carbon chain with 4 or less carbon atoms, such as the compounds of the following formulas (2) to (4), and derivatives obtained by esterifying the hydroxyl group of 4-hydroxyTEMPO with a carboxylic acid or sulfonic acid.

[0088] [ka]

[0089] In the above formula (2), R 5 represents a straight or branched carbon chain having 4 or less carbon atoms.

[0090] [ka]

[0091] In the above formula (3), R 6 represents a straight or branched carbon chain having 4 or less carbon atoms.

[0092] [ka]

[0093] In the above formula (4), R 7 represents a straight or branched carbon chain having 4 or less carbon atoms.

[0094] As a derivative of 4-amino TEMPO, 4-acetamido TEMPO, represented by the following formula (5), in which the amino group of 4-amino TEMPO is acetylated to impart appropriate hydrophobicity, is preferred because it is inexpensive and can give uniformly oxidized cellulose.

[0095] [ka]

[0096] Furthermore, the radical of an N-oxyl compound represented by the following formula (6), that is, an azaadamantane-type nitroxy radical, is also preferred because it can oxidize cellulose efficiently in a short period of time.

[0097] [ka]

[0098] In the above formula (6), R 8 , R 9 are the same or different and represent a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms.

[0099] The amount of the N-oxyl compound added is not particularly limited as long as it is a catalytic amount sufficient to sufficiently convert the resulting oxidized cellulose into nanofibers. However, the amount is preferably 0.01 mmol / g or more, more preferably 0.015 mmol / g or more, and even more preferably 0.025 mmol / g or more, relative to 1 g (bone dry) of cellulose fiber, and is preferably 10 mmol / g or less, more preferably 1 mmol / g or less, and even more preferably 0.5 mmol / g or less.

[0100] The co-oxidizing agent may be a hypohalous acid, a perhalogen acid, or a salt thereof; hydrogen peroxide, or a perorganic acid, but is preferably an alkali metal hypohalite. For example, when using sodium hypochlorite, the reaction is preferably carried out in the presence of an alkali metal bromide. The amount of the alkali metal bromide added per gram of cellulose fiber (bone dry) is preferably 0.1 mmol / g or more, more preferably 0.2 mmol / g or more, even more preferably 0.5 mmol / g or more, and preferably 100 mmol / g or less, more preferably 10 mmol / g or less, even more preferably 5 mmol / g or less. The amount of sodium hypochlorite added is preferably 0.1 mmol / g or more, more preferably 0.5 mmol / g or more, even more preferably 2.5 mmol / g or more, and preferably 500 mmol / g or less, more preferably 50 mmol / g or less, even more preferably 25 mmol / g or less.

[0101] The pH of the aqueous reaction solution is preferably maintained in the range of about 8 to 11. The temperature of the aqueous solution can be about 4 to 40°C, for example, room temperature, and no particular temperature control is required.

[0102] The amount of the co-oxidant added is preferably 3.0 mmol / g or more and 8.2 mmol / g or less per 1 g (bone dry) of cellulose fibers.

[0103] The purification step removes compounds other than the reactant fiber and water contained in the reaction slurry, such as unreacted hypochlorous acid and various by-products, from the system. Conventional purification methods can be used, for example, by repeatedly washing with water and filtering to prepare a highly pure (99% by mass or more) dispersion of the reactant fiber and water.

[0104] Following the purification step, the water-impregnated reaction product fibers (aqueous dispersion) obtained in the purification step are subjected to a dispersion treatment (dispersion step) in which they are dispersed in a solvent, thereby preparing the microfibrillated plant fiber dispersion. Water is typically the preferred dispersion medium. In addition to water, water-soluble alcohols, ethers, ketones, and the like may also be used. The dispersing machine used in the dispersion step may be a general-purpose dispersing machine, a high-speed homomixer, a high-pressure homogenizer, or another device with powerful beating capabilities. The microfibrillated plant fiber dispersion thus obtained is preferably further hydrophobicized by a counterion exchange method or the like. The counterion exchange method may be a commonly used, conventionally known method, such as adding a dilute acid, such as dilute hydrochloric acid or dilute nitric acid, adjusted to a pH of 2 or less, to the microfibrillated plant fiber dispersion, followed by washing with water and neutralization by adding a quaternary ammonium salt, such as tetramethylammonium hydroxide or tetrabutylammonium hydroxide. The dispersion of microfibrillated plant fibers thus obtained can be dried as needed to obtain microfibrillated plant fibers that have been oxidized using an N-oxyl compound. For this drying, freeze-drying or the like can be used. Here, by mixing a compound with an extremely high boiling point and affinity for cellulose, such as a water-soluble polymer or a sugar, as a binder into the dispersion of microfibrillated plant fibers, it is possible to obtain microfibrillated plant fibers that can be redispersed in a solvent as nanofibers even by a conventional drying method. In this case, the amount of binder added to the dispersion is preferably in the range of 10 to 80% by mass relative to the reactant fibers.

[0105] The average fiber diameter of the microfibrillated plant fibers is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, and is preferably 1200 nm or less, more preferably 1000 nm or less, even more preferably 500 nm or less, and particularly preferably 100 nm or less. When the diameter is within the above range, better effects tend to be obtained.

[0106] The average fiber length of the microfibrillated plant fibers is preferably 50 nm or more, more preferably 150 nm or more, even more preferably 300 nm or more, and particularly preferably 470 nm or more. There are no particular limitations on the upper limit of the average fiber length, but it is preferably 5 mm or less, more preferably 1 mm or less, even more preferably 50 μm or less, and particularly preferably 5 μm or less. When the average fiber length is less than the lower limit or exceeds the upper limit, the same tendency as the above-mentioned average fiber diameter occurs.

[0107] In this specification, the average fiber diameter and average fiber length of microfibrillated plant fibers can be measured by image analysis using scanning electron microscope photographs, image analysis using transmission electron microscope photographs, image analysis using atomic force microscope photographs, analysis of X-ray scattering data, pore electrical resistance method (Coulter principle method), etc.

[0108] When the microfibrillated plant fibers are a combination of two or more types, the average fiber diameter and average fiber length are calculated as averages for the entire microfibrillated plant fibers.

[0109] The carbon black that can be used in the rubber composition for the inner liner and the rubber composition for the sidewall is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. The raw material for the carbon black may be a biomass material such as lignin or vegetable oil, or pyrolysis oil obtained by pyrolyzing waste tires. Furthermore, the carbon black may be produced by combustion, such as in a furnace process, by hydrothermal carbonization (HTC), or by pyrolysis of methane, such as in a thermal black process. Commercially available products 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. These may be used alone or in combination of two or more.

[0110] The nitrogen adsorption specific surface area (N2SA) of carbon black is 20m 2 / g or more is preferable, and 30m 2 / g or more is more preferable, and 40m 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.

[0111] The silica that can be used in the rubber composition for the inner liner and the rubber composition for the sidewall 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 also 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.

[0112] 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.

[0113] 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.

[0114] 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).

[0115] Amorphous silica extracted from rice husks may be commercially available from Wilmar Co., Ltd., etc.

[0116] 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.

[0117] Examples of clays that can be used in the rubber composition for the inner liner and the rubber composition for the sidewall include hard clays containing kaolinite as the main component (such as Crown Clay manufactured by Southeastern Clay Co., Ltd., Union Clay RC1 and Glomax LL manufactured by Takehara Chemical Co., Ltd.), fired clays fired at 600°C (such as IceCap K manufactured by Burgess Co., Ltd.), and silane-modified clays fired at 600°C and then treated with a silane coupling agent (such as Burgess KE manufactured by Burgess Co., Ltd.). These may be used alone or in combination of two or more.

[0118] In the rubber composition for an inner liner, the content Mc of the microfibrillated plant fibers (total amount of microfibrillated plant fibers) 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, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0119] Although the mechanism by which a greater effect is obtained when Mc is a specified value or less, particularly 20 parts by mass or less, is not clear, it is thought that a small amount of microfibrillated plant fiber improves fuel economy, while even a small amount effectively binds the butyl rubber to harden it, thereby improving steering stability. Therefore, it is presumed that the overall performance of fuel economy, steering stability, and driving noise reduction is significantly improved.

[0120] In the rubber composition for an inner liner, the content of the chemically modified microfibrillated plant fibers (total amount of the chemically modified microfibrillated plant fibers) is preferably at least 1 part by mass, more preferably at least 3 parts by mass, and even more preferably at least 5 parts by mass, per 100 parts by mass of the rubber component, and is preferably at most 20 parts by mass, more preferably at most 15 parts by mass, and even more preferably at most 10 parts by mass. Within the above ranges, better effects tend to be obtained.

[0121] In the rubber composition for an inner liner, the content of carbon black is preferably 30 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 100 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 60 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0122] In the rubber composition for an inner liner, the content of silica per 100 parts by mass of the rubber component is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, and may be 0 part by mass. When the content is within the above range, better effects tend to be obtained.

[0123] In the rubber composition for an inner liner, the content of the plant-derived silica per 100 parts by mass of the rubber component is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, and may be 0 part by mass. When the content is within the above range, better effects tend to be obtained.

[0124] In the rubber composition for an inner liner, the content of the rice husk silica per 100 parts by mass of the rubber component is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, and may be 0 part by mass. When the content is within the above range, better effects tend to be obtained.

[0125] In the rubber composition for an inner liner, the content of the clay 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, and is preferably 25 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0126] In the rubber composition for an inner liner, the content of the filler (total amount of fillers such as microfibrillated plant fibers, carbon black, clay, and silica) is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 60 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 100 parts by mass or less, even more preferably 80 parts by mass or less, and particularly preferably 70 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0127] In the rubber composition for sidewalls, the content of carbon black is preferably 30 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 100 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0128] Although the mechanism by which a tire containing isoprene-based rubber, BR, and carbon black exhibits a particularly favorable effect when the amount of carbon black per 100 parts by mass of the rubber component is 30 parts by mass or more is unclear, it is believed that sufficient hardness of the sidewall is ensured, minimizing deformation and deflection, thereby improving handling stability, and therefore significantly improving the overall performance of fuel economy, handling stability, and noise reduction during driving.

[0129] In the rubber composition for sidewalls, the content of silica per 100 parts by mass of the rubber component is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, and may be 0 part by mass. When the content is within the above range, better effects tend to be obtained.

[0130] In the rubber composition for sidewalls, the content of the plant-derived silica per 100 parts by mass of the rubber component is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, and may be 0 part by mass. When the content is within the above range, better effects tend to be obtained.

[0131] In the rubber composition for sidewalls, the content of the rice husk silica per 100 parts by mass of the rubber component is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, and may be 0 part by mass. When the content is within the above range, better effects tend to be obtained.

[0132] In the rubber composition for sidewalls, the content of filler (total amount of fillers such as microfibrillated plant fiber, carbon black, clay, silica, etc.) is preferably 30 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 100 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0133] (Silane coupling agent) The rubber composition for an inner liner and the rubber composition for a sidewall may contain 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.

[0134] In the rubber composition for innerliner and the rubber composition for sidewall, 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, per 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.

[0135] (plasticizer) The rubber composition for the inner liner and the rubber composition for the sidewall may contain a plasticizer (softener). In this specification, the term "plasticizer" refers to a material that imparts plasticity to a rubber component, and includes both plasticizers that are liquid at 25°C and plasticizers that are solid at 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.

[0136] In the rubber composition for an inner liner and the rubber composition for a sidewall, examples of usable plasticizers include polymers having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof. The polymer may be liquid or solid at 25°C. From the viewpoint of obtaining better effects, a polymer that is liquid at 25°C is desirable. The polymer may be used alone or in combination of two or more types. In particular, from the viewpoint of obtaining a greater effect, it is desirable that the rubber composition for the inner liner contains a polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof.

[0137] Although the mechanism by which the rubber composition for an inner liner contains a polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and their derivatives provides a greater effect is not clear, it is believed that the polymer improves the dispersibility of the microfibrillated plant fibers, effectively restrains the butyl rubber, hardens it, and minimizes deformation and deflection, thereby improving handling stability. Therefore, it is presumed that the overall performance of fuel economy, handling stability, and noise reduction during driving is significantly improved.

[0138] In the polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof, the derivative of maleic acid and maleic anhydride can be, for example, a compound having a moiety derived from maleic acid and / or maleic anhydride and having an ester group and / or an anionic group. Specific examples include esters of maleic acid or maleic anhydride, and salts of maleic acid or maleic anhydride. These may be used alone or in combination of two or more.

[0139] Examples of the maleic acid ester include monoalkyl maleates such as monomethyl maleate and monoethyl maleate; monoalkenyl maleates; monoaryl maleates; and dialkyl maleates. Examples of the maleic anhydride ester include compounds corresponding to these maleic acid esters.

[0140] Examples of the maleate salt include ammonium salts and metal salts of maleic acid (alkali metal salts such as sodium salt and potassium salt, alkaline earth metal salts such as calcium salt, and salts of other metals such as zinc salt), and examples of the maleic anhydride salt include compounds corresponding to these maleates. In addition, when the polymer is a compound having a moiety derived from a maleate salt or maleic anhydride, it is sufficient that the compound has at least one salt structure.

[0141] Examples of the polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof include copolymers of aromatic vinyl compounds with maleic acid and / or maleic anhydride, and derivatives thereof, which may be used alone or in combination of two or more.

[0142] Examples of the copolymer of the aromatic vinyl compound and maleic acid and / or maleic anhydride, and its derivatives include copolymers consisting of an aromatic vinyl compound unit (a structural unit derived from an aromatic vinyl compound) and at least one compound unit selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof (a structural unit derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof).Specific examples include copolymers of aromatic vinyl compounds and maleic acid, copolymers of aromatic vinyl compounds and maleic anhydride, copolymers of aromatic vinyl compounds and maleic esters, copolymers of aromatic vinyl compounds and maleic anhydride esters, copolymers of aromatic vinyl compounds and maleates, and copolymers of aromatic vinyl compounds and maleic anhydrides.

[0143] Examples of compounds constituting the aromatic vinyl compound units include styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,6-dimethylstyrene, 2,4-dimethylstyrene, α-methyl-o-methylstyrene, α-methyl-m-methylstyrene, α-methyl-p-methylstyrene, β-methyl-o-methylstyrene, β-methyl-m-methylstyrene, β-methyl-p-methylstyrene, 2,4,6-trimethylstyrene, α-methyl-2,6-dimethylstyrene, α-methyl-2,4-dimethylstyrene, β-methyl-2,6-dimethylstyrene, β-methyl-2,4-dimethylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,6-dichlorostyrene, 2,4-dichlorostyrene, α-chloro- ...α-chloro-m-methylstyrene, β-methyl-m-methylstyrene, β-methyl-p-methylstyrene, 2,4,6-trimethylstyrene, α-methyl-2,6-dimethylstyrene, α-methyl-2,4-dimethylstyrene, β-methyl-2,6-dimethylstyrene, β-methyl-2,4-dimethylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,6-dichlorostyrene, 2,4-dichlorostyrene, α-chloro-o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,6-dichlorostyrene, α-chloro-m-methylstyrene, α-chloro-m-methylstyrene, β-methyl-m-methylstyrene, β-methyl-p-methylstyrene, 2,4,6-trimethylstyrene, α-methyl-2,6-dimethylstyrene, α-methyl-2,4-dimethylstyrene, β-methyl- Examples of the aromatic vinyl compound include styrene, α-chloro-m-chlorostyrene, α-chloro-p-chlorostyrene, β-chloro-o-chlorostyrene, β-chloro-m-chlorostyrene, β-chloro-p-chlorostyrene, 2,4,6-trichlorostyrene, α-chloro-2,6-dichlorostyrene, α-chloro-2,4-dichlorostyrene, β-chloro-2,6-dichlorostyrene, β-chloro-2,4-dichlorostyrene, ot-butylstyrene, mt-butylstyrene, pt-butylstyrene, o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, o-chloromethylstyrene, m-chloromethylstyrene, p-chloromethylstyrene, o-bromomethylstyrene, m-bromomethylstyrene, p-bromomethylstyrene, styrene derivatives substituted with silyl groups, indene, vinylnaphthalene, etc. The compounds constituting the aromatic vinyl compound unit may be used alone or in combination of two or more. Among these, from the viewpoint of obtaining better effects, styrene, α-methylstyrene, and mixtures thereof are preferred, and styrene is more preferred.

[0144] The copolymer of the aromatic vinyl compound with maleic acid and / or maleic anhydride, and its derivatives, preferably has a total content of aromatic vinyl compound units (structural units derived from aromatic vinyl compounds) and aromatic vinyl compound derivative units (structural units derived from derivatives of aromatic vinyl compounds) of 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, and preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less. Within the above ranges, the effect tends to be better. The content of aromatic vinyl compound units such as styrene content and aromatic vinyl compound derivative units is 1 The styrene content can be measured using a H-NMR method, for example, using a JEOL JNM-A 400 NMR instrument at 25°C. 1 The styrene content can be determined by measuring H-NMR and determining the ratio of phenyl protons based on styrene units at 6.5 to 7.2 ppm to vinyl protons based on butadiene units at 4.9 to 5.4 ppm from the spectrum.

[0145] The copolymer of the aromatic vinyl compound with maleic acid and / or maleic anhydride, and its derivatives, preferably has a total content of at least one compound unit selected from the group consisting of maleic acid, maleic anhydride, and their derivatives, and said compound derivative unit (structural unit derived from said compound derivative) of 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, and also preferably less than 50% by mass, more preferably 40% by mass or less, and even more preferably 30% by mass or less. When the content is within the above range, better effects tend to be obtained. The content of at least one compound unit selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof, and the content of the compound derivative unit is as follows: 1 It can be measured using H-NMR.

[0146] As the polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof, a modified polymer modified with the compound can also be preferably used. In particular, from the viewpoint of obtaining a better effect, a modified liquid polymer modified with the compound can be preferably used. These may be used alone or in combination of two or more.

[0147] The liquid polymer (a polymer in a liquid state at 25°C) constituting the skeleton of the modified liquid polymer is preferably a conjugated diene polymer, etc. As the conjugated diene polymer, a liquid diene polymer obtained by polymerizing a monomer containing a conjugated diene such as 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 2-methyl-1,3-pentadiene, 4,5-diethyl-1,3-octadiene, or 3-butyl-1,3-octadiene is preferred.

[0148] Examples of the liquid diene polymer include liquid polybutadiene, liquid polyisoprene, liquid styrene-butadiene random copolymer, liquid styrene-butadiene block copolymer, liquid butadiene-isoprene random copolymer, liquid butadiene-isoprene block copolymer, liquid styrene-butadiene-isoprene random copolymer, and liquid styrene-butadiene-isoprene block copolymer. These may be used alone or in combination of two or more. Among these, liquid polyisoprene (i.e., a polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof, and modified liquid polyisoprene modified with the compound) is preferred from the viewpoint of obtaining better effects.

[0149] The liquid polymer (polymer in a liquid state at 25° C.) constituting the skeleton of the modified liquid polymer may also be a polyolefin such as polyethylene, polypropylene, or polybutene. Of these, polybutene is preferred.

[0150] The number average molecular weight (Mn) of the liquid polymer constituting the skeleton of the modified liquid polymer is preferably 1000 or more, more preferably 5000 or more, and more preferably 10000 or more, and is preferably 70000 or less, more preferably 50000 or less. Within the above range, better effects tend to be obtained.

[0151] The modified liquid polymer modified with at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof can be produced by modifying a raw material unmodified liquid polymer with the compound. The modification method is not particularly limited, and the polymer can be produced by a known method, for example, by adding the compound to the raw material unmodified liquid polymer.

[0152] As the liquid polymer, for example, products of Kuraray Co., Ltd., Cray Valley Co., Ltd., etc. can be used.

[0153] Examples of plasticizers that can be used other than the polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof include oils, liquid polymers, resins, etc. These may be used alone or in combination of two or more.

[0154] The plasticizer may also be oil, other liquid polymers, resins, etc. These may be used alone or in combination of two or more.

[0155] 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.

[0156] 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.

[0157] 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 25°C. These vegetable oils may be used alone or in combination of two or more.

[0158] 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 esterified with 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. The acylglycerol may be liquid or solid at 25°C.

[0159] 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 25°C for 24 hours, and after removing the rubber composition, the 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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).

[0165] As the liquid diene polymer, for example, products available from Sartomer Co., Ltd., Kuraray Co., Ltd., etc. can be used.

[0166] The resin may be a resin commonly used in tire compounds, and may be liquid or solid at 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.

[0167] When a resin that is solid at 25° C. 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 25°C, the softening point is preferably 20°C or lower, more preferably 10°C or lower, and even more preferably 0°C or lower. 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.

[0168] 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.

[0169] 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.

[0170] The coumarone resin is a resin containing coumarone as a main monomer component constituting the skeleton (main chain) of the resin.

[0171] The indene resin is a resin containing indene as a main monomer component constituting the skeleton (main chain) of the resin.

[0172] 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.

[0173] Examples of the rosin resin include rosin-based resins such as natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

[0174] 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.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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]

[0180] 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.

[0181] 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).

[0182] 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.

[0183] 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.

[0184] The farnesene-based polymer may be either a liquid or solid at 25° C. Among these, a liquid farnesene-based polymer that is a liquid at 25° C. is preferred.

[0185] In the rubber composition for an inner liner, the content Pc of the polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof 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, and is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0186] In the rubber composition for an inner liner, the content of the copolymer of the aromatic vinyl compound and maleic acid and / or maleic anhydride 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, and is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0187] In the rubber composition for an inner liner, the content of the derivative of the copolymer of the aromatic vinyl compound and maleic acid and / or maleic anhydride 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, and is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0188] In the rubber composition for an inner liner, the content of the modified polymer modified with at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof 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, and is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0189] In the rubber composition for an inner liner, the content of the liquid polymer modified with at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof 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, and is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0190] In the rubber composition for an inner liner, the content of the plasticizer (total amount of plasticizer) per 100 parts by mass of the rubber component is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, and even more preferably 8 parts by mass or more, and is preferably 50 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, 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.

[0191] In the rubber composition for an inner liner, the content of the solid plasticizer in a solid state at 25°C is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less. Within the above range, better effects tend to be obtained. The content of the solid plasticizer also includes the amount of resin contained in the resin-extended rubber.

[0192] In the rubber composition for an inner liner, the content of the resin in a solid state at 25°C is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less. Within the above range, better effects tend to be obtained. The resin content includes the amount of resin contained in the resin-extended rubber.

[0193] In the rubber composition for an inner liner, the content of the aromatic vinyl polymer in a solid state at 25°C is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less. Within the above range, better effects tend to be obtained. The content of the aromatic vinyl polymer includes the amount of the aromatic vinyl polymer contained in the resin-extended rubber.

[0194] In the rubber composition for an inner liner, the content of the liquid plasticizer in a liquid state at 25°C 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 is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 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.

[0195] In the rubber composition for an inner liner, the content of the oil in a liquid state at 25°C 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 is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, better effects tend to be obtained. The oil content includes the amount of oil contained in the oil-extended rubber.

[0196] In the rubber composition for sidewalls, the content of the plasticizer (total amount of plasticizer) is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, and even more preferably 9 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 50 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, 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.

[0197] In the rubber composition for sidewalls, the content of the solid plasticizer in a solid state at 25°C is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less. Within the above range, better effects tend to be obtained. The content of the solid plasticizer also includes the amount of resin contained in the resin-extended rubber.

[0198] In the rubber composition for sidewalls, the content of the resin in a solid state at 25°C is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less. Within the above range, better effects tend to be obtained. The resin content includes the amount of resin contained in the resin-extended rubber.

[0199] In the rubber composition for sidewalls, the content of the aromatic vinyl polymer in a solid state at 25°C is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less. Within the above range, better effects tend to be obtained. The content of the aromatic vinyl polymer includes the amount of the aromatic vinyl polymer contained in the resin-extended rubber.

[0200] In the rubber composition for sidewalls, the content of the liquid plasticizer in a liquid state at 25°C 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 is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 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.

[0201] In the rubber composition for sidewalls, the content of oil in a liquid state at 25°C 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 is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, better effects tend to be obtained. The oil content includes the amount of oil contained in the oil-extended rubber.

[0202] 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.

[0203] The vulcanized rubber particles are not particularly limited, and may be unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0204] As commercially available vulcanized rubber particles, for example, products from Lehigh Corporation, Muraoka Rubber Industries Co., Ltd., etc. can be used.

[0205] In the rubber composition for an inner liner and the rubber composition for a sidewall, 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, better effects tend to be obtained.

[0206] The rubber composition for the inner liner and the rubber composition for the sidewall preferably contain an antioxidant from the viewpoints of crack resistance, ozone resistance, and the like.

[0207] 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.

[0208] In the rubber composition for an inner liner and the rubber composition for a sidewall, the content of the antioxidant is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 7.0 parts by mass or less, more preferably 5.0 parts by mass or less.

[0209] The rubber composition for the inner liner and the rubber composition for the sidewall preferably contain stearic acid. In the rubber composition for the inner liner and the rubber composition for the sidewall, the content of stearic acid is preferably 1.0 part by mass or more, more preferably 2.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0210] 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.

[0211] The rubber composition for the inner liner and the rubber composition for the sidewall preferably contain zinc oxide. In the rubber composition for the inner liner and the rubber composition for the sidewall, the content of zinc oxide is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less.

[0212] 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.

[0213] The rubber composition for the inner liner and the rubber composition for the sidewall may contain wax. In the rubber composition for the inner liner and the rubber composition for the sidewall, the wax content is preferably 0.5 parts by mass or more, more preferably 2.0 parts by mass or more, and preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, per 100 parts by mass of the rubber component.

[0214] 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.

[0215] The rubber composition for the inner liner and the rubber composition for the sidewall preferably contain sulfur. In the rubber composition for an inner liner and the rubber composition for a sidewall, the sulfur content is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 1.8 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 3.5 parts by mass or less, more preferably 3.0 parts by mass or less, and even more preferably 2.5 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0216] 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.

[0217] The rubber composition for the inner liner and the rubber composition for the sidewall preferably contain a vulcanization accelerator. In the rubber composition for the inner liner and the rubber composition for the sidewall, 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 part 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.

[0218] 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.

[0219] In addition to the above components, the rubber composition for an inner liner and the rubber composition for a sidewall may contain compounding agents generally used in the tire industry, such as materials such as a mold release agent, as appropriate.

[0220] 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. As a method for obtaining the above-mentioned compound from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0221] The rubber composition for the inner liner and the rubber composition for the sidewall can be produced, for example, by kneading the components using a rubber kneading device such as an open roll or a Banbury mixer, followed by vulcanization.

[0222] As for kneading conditions, in the base kneading step in which additives other than the crosslinking agent (vulcanizing agent) and vulcanization accelerator are kneaded, the kneading temperature is preferably 100°C or higher, more preferably 120°C or higher, and preferably 180°C or lower, more preferably 170°C. In the finish kneading step in which the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is preferably 80°C or higher, and preferably 120°C or lower, more preferably 110°C or lower. 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 preferably 140°C or higher, more preferably 150°C or higher, and preferably 190°C or lower, more preferably 185°C or lower.

[0223] The acetone extractable amount AE (mass%) of the rubber composition for innerliner (rubber composition after vulcanization) is preferably 10.0 mass% or less, more preferably 5.0 mass% or less, even more preferably 4.0 mass% or less, and particularly preferably 3.0 mass% or less. The lower limit of AE is not particularly limited, but is preferably 0.5 mass% or more, more preferably 1.0 mass% or more, and even more preferably 1.5 mass% or more. Within the above range, the effect tends to be preferably obtained.

[0224] Although the mechanism by which a greater effect is obtained when the acetone extractables are below a certain level, particularly 10.0 mass% or less, is unclear, it is believed that the lower the acetone extractables, the more sufficient hardness is ensured in the tire sidewalls and the better the handling stability. Therefore, it is presumed that the overall performance of fuel economy, handling stability, and noise reduction during driving will be significantly improved.

[0225] In this specification, the acetone extractables (AE) are values ​​measured by the method for measuring acetone extractables in accordance with JIS K 6229:2015.

[0226] The AE can be adjusted by any method known to those skilled in the art. For example, the AE tends to increase as the content of plasticizer in the rubber composition increases.

[0227] The tire is manufactured by a conventional method using the rubber composition for the inner liner and the rubber composition for the sidewall. That is, a composition containing various additives as necessary is extruded in an unvulcanized state to match the shapes of various tire components such as the rubber composition for the inner liner and the sidewall, molded in a conventional method on a tire building machine, 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.

[0228] The tire is not particularly limited, and examples thereof include pneumatic tires, solid tires, airless tires, etc. Among these, pneumatic tires are preferred.

[0229] 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.

[0230] The tire has a product (A×T) of an average fiber diameter A (nm) of the microfibrillated plant fibers contained in the rubber composition for an inner liner and a side thickness T (mm) at the maximum width position of the tire, of 5000 or less. A×T is preferably 4000 or less, more preferably 2000 or less, even more preferably 1000 or less, and particularly preferably 800 or less. The lower limit of A×T is preferably 100 or more, more preferably 300 or more, and even more preferably 500 or more. Within the above range, the effect tends to be favorably obtained.

[0231] The tire has a side thickness T (mm) of 10 mm or less at the tire maximum width position. T is preferably 9 mm or less, more preferably 8 mm or less. The lower limit of T is preferably 3 mm or more, more preferably 4 mm or more, and even more preferably 5 mm or more. Within the above range, the effect tends to be preferably obtained.

[0232] In this specification, the term "maximum tire width positions" refers to a pair of positions where the tire has the maximum width in the axial direction. "Side thickness (T) at the tire's maximum width position" refers to the overall thickness of the tire's side portion in the tire's axial direction at the tire's maximum width position in a radial cross section, and means the linear distance from the tire's outer surface to the tire's inner cavity surface. Specifically, T is the linear distance in the tire's axial direction from the tire's outermost surface of the surface rubber layer, such as the sidewall or clinch apex, at the tire's maximum width position to the tire's innermost surface, such as the inner liner, in the radial cross section. The "side thickness (T) at the tire's maximum width position" is a value measured from the surface of the surface rubber layer at the tire's maximum width position along the tire axial direction.

[0233] It is desirable that the tire has a ratio (Mc / Ti) of the content Mc (parts by mass) of the microfibrillated plant fibers per 100 parts by mass of the rubber component of the rubber composition for the inner liner to the thickness Ti (mm) of the inner liner at the maximum width position of the tire, of 20 or less. Mc / Ti is preferably 17 or less, more preferably 15 or less, and even more preferably 10 or less. The lower limit of Mc / Ti is preferably 2 or more, more preferably 3 or more, and even more preferably 5 or more. Within the above range, the effect tends to be favorably obtained.

[0234] Although the mechanism by which a greater effect is obtained when Mc / Ti is adjusted within a predetermined range is unclear, it is believed that adding a certain amount of microfibrillated plant fiber relative to the thickness of the inner liner effectively restrains the butyl rubber, making it harder and improving handling stability, thereby significantly improving the overall performance of fuel economy, handling stability, and noise reduction during driving.

[0235] In the tire, the thickness Ti (mm) of the inner liner at the tire maximum width position is preferably 0.5 mm or more, more preferably 1.0 mm or more. The upper limit of Ti is preferably 3.0 mm or less, more preferably 2.0 mm or less. Within the above range, the effect tends to be preferably obtained.

[0236] It is desirable that the tire has a ratio (Pc / Ti) of the content Pc (parts by mass) of the polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof per 100 parts by mass of the rubber component of the rubber composition for the inner liner, to the thickness Ti (mm) of the inner liner at the maximum width position of the tire, of 20 or less. Pc / Ti is preferably 17 or less, more preferably 15 or less, and even more preferably 10 or less. The lower limit of Pc / Ti is preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more. Within the above range, the effect tends to be favorably obtained.

[0237] Although the mechanism by which the Pc / Ti ratio is adjusted to a specific range provides a more effective result is unclear, it is believed that adding a certain amount of the above polymer relative to the thickness of the inner liner improves the dispersibility of the filler and increases rigidity, thereby significantly improving the overall performance of fuel economy, handling stability, and noise reduction during driving.

[0238] In this specification, "thickness of inner liner (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 of the tire, and means the linear distance in the axial direction of the tire from the tire's axially outer surface to the tire's axially inner surface at the tire's maximum width position. The "thickness (Ti) of the inner liner at the maximum width position of the tire" is a value measured along the tire axial direction from the axially inner surface of the inner liner at the maximum width position of the tire.

[0239] In the tire, the groove depth D (mm) of the circumferential grooves formed in the tread is preferably 1.0 mm or more, more preferably 2.0 mm or more, and even more preferably 5.0 mm or more, and is preferably 10.0 mm or less, more preferably 9.5 mm or less, and even more preferably 9.0 mm or less. Within the above ranges, the effect tends to be better obtained.

[0240] Although the mechanism by which the effect of adjusting the groove depth D of the circumferential grooves formed in the tread to a predetermined range is unclear, it is believed that adjusting the groove depth ensures good rigidity, and therefore it is presumed that the overall performance of fuel economy, handling stability, and noise reduction during driving will be significantly improved.

[0241] In this specification, the groove depth D of the circumferential groove is measured along the normal to the surface extending from the surface forming the contact patch on the outermost surface of the tread, and means the distance from the surface extending from the surface forming the contact patch to the deepest groove bottom, and refers to the maximum distance among the groove depths of the circumferential grooves provided.

[0242] In the tire, it is desirable that the ratio (Mc / D) of the content Mc (parts by mass) of the microfibrillated plant fibers per 100 parts by mass of the rubber component of the rubber composition for the inner liner to the groove depth D (mm) of the circumferential grooves formed in the tread is 0.5 or more and 5.0 or less. Mc / D is preferably 0.8 or more, more preferably 1.0 or more, and is preferably 4.5 or less, more preferably 4.0 or less. Within the above ranges, the effect tends to be favorably obtained.

[0243] Although the mechanism by which adjusting Mc / D to a specific range provides better results is unclear, it is believed that a good balance between groove depth and the content of microfibrillated plant fiber ensures good rigidity, which is likely to result in significant improvements in overall performance in terms of fuel economy, handling stability, and noise reduction during driving.

[0244] In the tire, it is desirable that the ratio (Pc / D) of the content Pc (parts by mass) of the polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof per 100 parts by mass of the rubber component of the rubber composition for the inner liner to the groove depth D (mm) of the circumferential grooves formed in the tread is 0.5 or more and 5.0 or less. Pc / D is preferably 0.8 or more, more preferably 1.0 or more, and is preferably 4.5 or less, more preferably 4.0 or less. Within the above ranges, the effect tends to be favorably obtained.

[0245] Although the mechanism by which adjusting Pc / D to a specific range provides better results is unclear, it is believed that a good balance between groove depth and the polymer content ensures good rigidity, resulting in significant improvements in overall performance in terms of fuel economy, handling stability, and noise reduction during driving.

[0246] 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 200 mm or more, and even more preferably 220 mm or more. Within the above range, the effect tends to be preferably obtained. In this specification, the cross-sectional width Wt (mm) of a tire is the maximum width between the outer surfaces of the sidewalls in a normal state, excluding any patterns or letters on the sidewalls.

[0247] Although the mechanism by which a tire's cross-sectional width Wt is more effective when adjusted to a predetermined value or less, particularly 250 mm or less, is unclear, it is believed that adjusting Wt to ​​a predetermined value or less ensures good rigidity, which is presumed to significantly improve the overall performance of the tire in terms of fuel economy, handling stability, and noise reduction during driving.

[0248] In this specification, dimensions such as thickness are measured under normal conditions. "Normal conditions" refers to a tire mounted on a normal rim, inflated to the normal internal pressure, and unloaded. Here, "normal rim" refers to a rim specified for each tire by the standard system, including the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Manufacturers Association), this refers to the standard rim for the applicable size listed in the "JATMA Year Book." In the case of ETRTO (The European Tire and Rim Technical Organization), this refers to the "Measuring Rim" listed in the "Standards Manual." In the case of TRA (The Tire and Rim Association, Inc.), this refers to the "Design Rim" listed in the "Year Book." JATMA, ETRTO, and TRA are referenced in this order, and if an applicable size is available at the time of reference, these standards are followed. For tires not specified by a standard, this refers to a rim that can be mounted on a rim and can maintain internal pressure, i.e., the rim with the smallest rim diameter and the next narrowest rim width, among rims that can prevent air leakage between the rim and tire. Additionally, "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 "maximum air pressure," for ETRTO, it refers to "INFLATION PRESSURE," and for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." Refer to JATMA, ETRTO, and TRA in that order, and follow the standard if there is an applicable size at the time of reference. In the case of a tire not specified in the 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.

[0249] An example of the tire will be described below with reference to the drawings, but the tire is not limited to this configuration.

[0250] 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.

[0251] 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.

[0252] In the tire 2, each sidewall 6 extends substantially radially inward from an end of the tread 4. The sidewall 6 is made of the above-mentioned rubber composition for sidewalls.

[0253] 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.

[0254] 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.

[0255] 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.

[0256] 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.

[0257] 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.

[0258] 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.

[0259] 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.

[0260] 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.

[0261] 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.

[0262] 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.

[0263] 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.

[0264] 1 constitute a reinforcing layer. The reinforcing layer may be constituted by the belt layer 16 alone.

[0265] 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).

[0266] The inner liner 20 is located inside the carcass 14. The inner liner 20 is joined to the inner surface of the carcass 14.

[0267] The inner liner 20 is made of the rubber composition for an inner liner containing butyl rubber and microfibrillated plant fibers. The inner liner 20 maintains the internal pressure of the tire 2.

[0268] 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.

[0269] 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.

[0270] 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. 2D shows the groove depth of the main groove 42 formed in the tread 4 in the circumferential direction.

[0271] The tire 2 in FIG. 1 has a tire maximum width position M on the surface of the sidewall 6, and satisfies the relationship that the product (A×T) of the average fiber diameter A (nm) of the microfibrillated plant fibers contained in the inner liner 20 and the side thickness T (mm) at the tire maximum width position M is 5000 or less, and the side thickness T (mm) at the tire maximum width position M is 10 mm or less.

[0272] In the tire 2 of Figure 1, it is desirable that the ratio (Mc / Ti) of the content Mc (parts by mass) of microfibrillated plant fibers in the inner liner 20 to the thickness Ti (mm) of the inner liner at the tire's maximum width position M is 10.0 or less.

[0273] In the tire 2, with respect to the average fiber diameter A of the microfibrillated plant fibers contained in the inner liner 20, the side thickness T at the maximum width position M of the tire, the content Mc of the microfibrillated plant fibers per 100 parts by mass of the rubber component of the inner liner 20, the cross-sectional width Wt of the tire, the acetone extractable amount AE of the inner liner 20, the content Mc of the microfibrillated plant fibers per 100 parts by mass of the rubber component of the inner liner 20, the thickness Ti of the inner liner 20 at the maximum width position M of the tire, the content Pc of the polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof per 100 parts by mass of the rubber component of the inner liner 20, the thickness Ti of the inner liner 20 at the maximum width position M of the tire, and the groove depth D of the circumferential grooves formed in the tread 4, it is desirable that Mc, A, Wt, AE, Mc / Ti, Pc / Ti, D, Mc / D, and Pc / D be within the above-mentioned ranges. [Example]

[0274] Below, examples (embodiments) that are considered preferable for implementation will be shown, but the scope of the present disclosure is not limited to the embodiments.

[0275] Below, we will explain the various chemicals used in the preparation of the microfibrillated plant fiber dispersion (CNF aqueous dispersion) and the preparation of the CNF-containing mixture. Microfibrillated plant fiber 1: Recycled pulp (solid content 90% by mass, moisture 10% by mass, average fiber diameter 30 μm, crystallinity 60%) TEMPO: 2,2,6,6-tetramethylpiperidine-1-oxyl Sodium bromide: Fujifilm Wako Pure Chemical Industries, Ltd. Sodium hypochlorite: manufactured by Tokyo Chemical Industry Co., Ltd. NaOH: NaOH manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Maleic anhydride-modified polyisoprene: LIR403 manufactured by Kuraray Co., Ltd. (a polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof)

[0276] <Preparation of microfibrillated plant fiber dispersion (CNF aqueous dispersion 1)> (Production Example 1: CNF aqueous dispersion with an average fiber diameter of 100 nm) 10 g of microfibrillated plant fiber 1, 150 mg of TEMPO, and 1000 mg of sodium bromide were dispersed in 1000 ml of water. A 15% by mass aqueous solution of sodium hypochlorite was then added to 1 g of microfibrillated plant fiber (bone-dry) to achieve a sodium hypochlorite concentration of 5 mmol per 1 g of microfibrillated plant fiber to initiate the reaction. During the reaction, a 3 M aqueous solution of NaOH was added dropwise to maintain the pH at 10.0. The reaction was considered complete when no further change in pH was observed. The reaction product was then filtered through a glass filter. This was then washed with sufficient amounts of water and filtered five times to obtain a water-impregnated reaction product fiber with a solids content of 15% by mass. This was then diluted and mechanically defibrated to an average fiber diameter of 100 nm, yielding a 1% by mass aqueous CNF dispersion 1.

[0277] (Production Example 2: CNF aqueous dispersion 2 with an average fiber diameter of 500 nm) The same procedure as in Production Example 1 is carried out, except that instead of mechanically defibrating to an average fiber diameter of 100 nm, mechanically defibrating to an average fiber diameter of 500 nm is carried out, thereby obtaining a 1% by mass CNF aqueous dispersion 2.

[0278] (Production Example 3: CNF aqueous dispersion 3 with an average fiber diameter of 1200 nm) The same procedure as in Production Example 1 is carried out, except that instead of mechanically defibrating to an average fiber diameter of 100 nm, mechanically defibrating to an average fiber diameter of 1200 nm is carried out, thereby obtaining a 1% by mass CNF aqueous dispersion 3.

[0279] (Preparation of CNF-containing mixture) A predetermined amount of maleic anhydride-modified polyisoprene is added to the 1% by mass CNF aqueous dispersions 1 to 3 prepared in the above Manufacturing Examples 1 to 3 according to the formulation in Table 1, and the mixture is stirred for 5 minutes at room temperature (20 to 30°C) using a high-speed homogenizer to obtain CNF-containing mixtures (mixtures) 1 to 3.

[0280] The various chemicals used in the production of inner liners and sidewalls are described below. If necessary, the chemicals may be purified according to standard methods. (inner liner) Halogenated butyl rubber: Bromobutyl rubber 2255 (brominated butyl rubber) manufactured by Exxon Chemical Co., Ltd. NR:TSR20 CNF-containing mixtures 1 to 3: Preparation of the above CNF-containing mixtures Carbon black: N660 (N2SA: 35m) manufactured by Jiangxi Black Cat Co., Ltd. 2 / g) Clay: Crown Clay (hard clay, average particle size 0.6 μm) manufactured by Southeastern Clay Co. Resin: Durez 19900 (phenolic resin, SP value: 10.1, Mw: 2000) manufactured by Sumitomo Bakelite Co., Ltd. Stearic acid: NOF Corporation's "Tsubaki" stearic acid Zinc oxide: Zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator DM: Noccela DM (di-2-benzothiazyl disulfide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (Sidewall) NR:RSS#3 BR: Ube Pole BR150B manufactured by Ube Industries, Ltd. Carbon black: Diablack N550 (N2SA: 42 m2 / g) manufactured by Mitsubishi Chemical Corporation Stearic acid: Camellia stearic acid beads manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Antioxidant: Ozonone 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Seiko Chemical Co., Ltd. Oil: X-140 manufactured by Japan Energy Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator CZ: Noccela CZ-G (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0281] (Preparation of rubber composition for inner liner) 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 for an unvulcanized inner liner.

[0282] (Preparation of rubber composition for sidewall) According to the formulation shown in Table 2, 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 for unvulcanized sidewalls.

[0283] <Test tire manufacturing method> According to the specifications in Table 1, the unvulcanized rubber composition for the inner liner is molded into the shape of an inner liner, and the unvulcanized rubber composition for the sidewall is molded into the shape of a sidewall, and these are laminated together with other tire components in a tire building machine to form an unvulcanized tire, which is then vulcanized at 170°C for 10 minutes to produce a test tire (size 215 / 45R17, passenger car tire, Figures 1 to 2).

[0284] The results of calculations based on the following evaluation methods, assuming test tires obtained from compositions whose formulations and specifications were changed according to Table 1, are shown in each table. The reference comparative example is as follows. Table 1: Comparative Example 1

[0285] <Acetone extractables (AE)> A rubber test piece is taken from inside the inner liner of the test tire. The amount of material extracted by acetone contained in the rubber test piece is measured according to the acetone extractable amount measurement method in accordance with JIS K 6229. Acetone extractable amount AE (mass%) = (mass of sample before extraction - mass of sample after extraction) / mass of sample before extraction × 100

[0286] <Fuel efficiency> Using a rolling resistance tester, the test tire is mounted on a standard rim (15x6JJ), pressurized to a standard internal pressure (230kPa), and a load of 3.43kN is applied. The rolling resistance is then measured while driving at a speed of 80km / h, and is expressed as an index, with the reference comparative example being set at 100. The higher the index, the better the fuel economy.

[0287] <Handling stability> Test tires are fitted to all wheels of a vehicle, and the vehicle is driven around a test course with one driver on board, zigzagging along the way. The driver then evaluates the handling stability using a sensory rating of 1 to 5. The same test is carried out with other drivers, for a total of 20 drivers. The results are evaluated using an index with the total score of the reference comparison example being 100. The higher the number, the better the handling stability.

[0288] <Noise reduction while driving> The test tires are fitted to all wheels of a vehicle, and the noise generated when the vehicle is driven on a designated course is evaluated by the driver using a sensory evaluation scale of 1 to 5. Similar tests are conducted with other drivers, for a total of 20 drivers. Evaluation is based on an index where the total score of the reference comparative example is 100. The higher the number, the better the noise reduction.

[0289] <Overall performance> The overall performance of fuel economy, driving stability, and driving noise reduction is evaluated by adding up the three indices obtained from the evaluations of fuel economy, driving stability, and driving noise reduction. The higher the value, the better the overall performance.

[0290] [Table 1]

[0291] [Table 2]

[0292] The present invention (1) is a tire having an inner liner made of a rubber composition for an inner liner containing a butyl rubber and microfibrillated plant fibers, the product (A × T) of the average fiber diameter A (nm) of the microfibrillated plant fibers and the side thickness T (mm) at the maximum width position of the tire is 5000 or less, The tire has a side thickness T (mm) at the tire's maximum width position of 10 mm or less.

[0293] The present invention (2) is the tire according to the present invention (1), wherein the rubber composition for the inner liner has a content Mc of the microfibrillated plant fibers of 20 parts by mass or less per 100 parts by mass of the rubber component.

[0294] The present invention (3) is the tire according to the present invention (1) or (2), wherein the average fiber diameter A of the microfibrillated plant fibers is 10 to 1000 nm.

[0295] The present invention (4) is a tire in any combination with any of the present inventions (1) to (3), wherein the tire has a cross-sectional width Wt of 250 mm or less.

[0296] The present invention (5) is a tire in any combination with any of the present inventions (1) to (4), wherein the acetone extractable amount AE (mass %) of the rubber composition for an inner liner is 10.0 mass % or less.

[0297] The present invention (6) is a tire in any combination with any of the present inventions (1) to (5), wherein the rubber composition for the inner liner has a content of the butyl rubber of 90% by mass or more in 100% by mass of the rubber component.

[0298] The present invention (7) is a tire in any combination with any of the present inventions (1) to (6), wherein the rubber composition for the inner liner contains a polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof.

[0299] The present invention (8) is a tire in any combination with any of the present inventions (1) to (7), in which the ratio (Mc / Ti) of the content Mc (parts by mass) of the microfibrillated plant fibers per 100 parts by mass of the rubber component of the rubber composition for the inner liner to the thickness Ti (mm) of the inner liner at the maximum width position of the tire is 10 or less.

[0300] The present invention (9) comprises an isoprene-based rubber, a butadiene rubber, and carbon black, The tire is any combination of any of the present inventions (1) to (8) and has a sidewall made of a rubber composition for sidewalls in which the content of carbon black per 100 parts by mass of the rubber component is 30 parts by mass or more.

[0301] The present invention (10) is a tire in any combination with any of the present inventions (1) to (9), in which the ratio (Pc / Ti) of the content Pc (parts by mass) of a polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof per 100 parts by mass of the rubber component of the rubber composition for the inner liner to the thickness Ti (mm) of the inner liner at the maximum width position of the tire is 10 or less.

[0302] The present invention (11) is a tire in any combination with any of the present inventions (1) to (10), in which the groove depth D (mm) of the circumferential grooves formed in the tread is 1.0 mm or more and 10.0 mm or less.

[0303] The present invention (12) is a tire in any combination with any of the present inventions (1) to (11), wherein the ratio (Mc / D) of the content Mc (parts by mass) of the microfibrillated plant fibers per 100 parts by mass of the rubber component of the rubber composition for the inner liner to the groove depth D (mm) of the circumferential grooves formed in the tread is 0.5 or more and 4.0 or less.

[0304] The present invention (13) is a tire in any combination with any of the present inventions (1) to (12), wherein the ratio (Pc / D) of the content Pc (parts by mass) of the polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof, per 100 parts by mass of the rubber component of the rubber composition for the inner liner, to the groove depth D (mm) of the circumferential grooves formed in the tread, is 0.5 or more and 4.0 or less. [Explanation of symbols]

[0305] 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 D Depth of the circumferential main groove formed in the tread M Maximum tire width position T: Side thickness at maximum tire width Ti Thickness of the inner liner at the widest point of the tire

Claims

1. A tire having an inner liner made of a rubber composition for an inner liner containing butyl rubber and microfibrillated plant fibers, the product (A × T) of the average fiber diameter A (nm) of the microfibrillated plant fibers and the side thickness T (mm) at the maximum width position of the tire is 5,000 or less, The tire has a side thickness T (mm) at the tire's maximum width position of 10 mm or less.

2. The tire according to claim 1, wherein the rubber composition for the inner liner has a content Mc of the microfibrillated plant fibers of 20 parts by mass or less per 100 parts by mass of the rubber component.

3. The tire according to claim 1 or 2, wherein the microfibrillated plant fibers have an average fiber diameter A of 10 to 1000 nm.

4. The tire according to claim 1 or 2, wherein the tire has a cross-sectional width Wt of 250 mm or less.

5. The tire according to claim 1 or 2, wherein the rubber composition for the inner liner has an acetone extractable amount AE (mass %) of 10.0 mass % or less.

6. The tire according to claim 1 or 2, wherein the rubber composition for the inner liner has a content of the butyl rubber of 90% by mass or more based on 100% by mass of a rubber component.

7. 3. The tire according to claim 1, wherein the rubber composition for the inner liner contains a polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof.

8. 3. The tire according to claim 1, wherein a ratio (Mc / Ti) of a content Mc (parts by mass) of the microfibrillated plant fibers per 100 parts by mass of the rubber component of the rubber composition for the inner liner to a thickness Ti (mm) of the inner liner at the maximum width position of the tire is 10 or less.

9. Contains isoprene rubber, butadiene rubber and carbon black, 3. The tire according to claim 1, further comprising a sidewall made of a rubber composition for a sidewall, the rubber composition containing the carbon black in an amount of 30 parts by mass or more per 100 parts by mass of the rubber component.

10. 3. The tire according to claim 1, wherein the ratio (Pc / Ti) of the content Pc (parts by mass) of the polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof per 100 parts by mass of the rubber component of the rubber composition for the inner liner to the thickness Ti (mm) of the inner liner at the maximum width position of the tire is 10 or less.

11. The tire according to claim 1 or 2, wherein a groove depth D (mm) of the circumferential groove formed in the tread is 1.0 mm or more and 10.0 mm or less.

12. 3. The tire according to claim 1, wherein a ratio (Mc / D) of a content Mc (parts by mass) of the microfibrillated plant fibers per 100 parts by mass of the rubber component of the rubber composition for the inner liner to a groove depth D (mm) of the circumferential grooves formed in the tread is 0.5 or more and 4.0 or less.

13. 3. The tire according to claim 1, wherein the ratio (Pc / D) of the content Pc (parts by mass) of the polymer having a moiety derived from at least one compound selected from the group consisting of maleic acid, maleic anhydride, and derivatives thereof per 100 parts by mass of the rubber component of the rubber composition for the inner liner to the groove depth D (mm) of the circumferential groove formed in the tread is 0.5 or more and 4.0 or less.

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