Rubber composition for inner liner and tire

Abstract

To provide a rubber composition for an inner liner which is excellent in overall performance of air permeation resistance and crack growth resistance, and to provide a tire.SOLUTION: The present invention relates to the rubber composition for an inner liner which contains a butyl rubber, an isoprene rubber, carbon black, a layered silicate mineral, and an aliphatic-aromatic copolymer-based resin. The content (mass%) of the butyl rubber and the content (mass%) of the isoprene rubber in 100 mass% of a rubber component, and the content (pts.mass) of the layered silicate mineral and the content (pts.mass) of the aliphatic-aromatic copolymer-based resin with respect to 100 pts.mass of the rubber component satisfy the following inequality (1): 1.5<(the content of the butyl rubber + the content of the layered silicate mineral) / (the content of the isoprene rubber + the content of the aliphatic-aromatic copolymer-based resin)<135.0.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a rubber composition for an inner liner and a tire. [Background technology]

[0002] Tires are generally provided with innerliners for the purpose of imparting air permeability resistance, but it is also desired that they also have improved crack resistance (crack growth resistance). Summary of the Invention [Problem to be solved by the invention]

[0003] An object of the present disclosure is to solve the above problems and to provide a rubber composition for an inner liner and a tire that are excellent in overall performance such as air permeation resistance and crack growth resistance. [Means for solving the problem]

[0004] The present disclosure relates to a rubber composition comprising a butyl-based rubber, an isoprene-based rubber, carbon black, a layered silicate mineral, and an aliphatic-aromatic copolymer-based resin, The rubber composition for an inner liner has a content (% by mass) of the butyl rubber and a content (% by mass) of the isoprene rubber in 100% by mass of the rubber component, a content (parts by mass) of the layered silicate mineral relative to 100 parts by mass of the rubber component, and a content (parts by mass) of the aliphatic-aromatic copolymer resin, which satisfy the following formula (1):

number

[0005] The present disclosure relates to a rubber composition for an inner liner that contains a butyl rubber, an isoprene rubber, carbon black, a layered silicate mineral, and an aliphatic aromatic copolymer resin, and satisfies the formula (1), thereby improving the overall performance of air permeation resistance and crack growth resistance. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a cross-sectional view showing a portion of a pneumatic tire. [Figure 2] FIG. 2 is an enlarged view of the vicinity of the equatorial plane CL of the tire 2 of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] The present disclosure relates to a rubber composition for an inner liner that contains a butyl rubber, an isoprene rubber, carbon black, a layered silicate mineral, and an aliphatic-aromatic copolymer resin, and satisfies formula (1).

[0008] The reason why the above-mentioned effects are obtained is not entirely clear, but it is presumed that the following mechanism is responsible. It is believed that blending layered silicate minerals inhibits air permeation within the rubber, improving air permeation resistance. Also, blending an aliphatic aromatic copolymer resin inhibits air permeation in the aromatic ring portion, and even when blending a resin with lower air permeability than butyl rubber, it is believed that it is possible to maintain air permeation resistance while increasing the strength of the rubber and improving crack growth resistance (crack resistance). Furthermore, by further using isoprene rubber so as to satisfy formula (1) "1.5 < (butyl rubber content + layered silicate mineral content) / (isoprene rubber content + aliphatic aromatic copolymer resin content) < 135", it is believed that air permeability resistance and crack growth resistance (crack resistance) can be improved in a balanced manner. Furthermore, it is believed that the molding processability can be improved by compounding an appropriate amount of isoprene-based rubber. Therefore, it is presumed that the present disclosure can improve the overall performance of air permeation resistance and crack growth resistance. Furthermore, it is believed that moldability can also be improved.

[0009] In this way, the rubber composition satisfies the formula (1) "1.5<(butyl rubber content+layer silicate mineral content) / (isoprene rubber content+aliphatic aromatic copolymer resin content)<135," thereby solving the problem (objective) of improving the overall performance of air permeation resistance and crack growth resistance. In other words, the parameter of formula (1) does not define the problem (objective), but the problem of the present application is to improve the overall performance of air permeation resistance and crack growth resistance, and a composition that satisfies the parameter is used as a means to achieve this.

[0010] <Rubber composition for inner liner> The rubber composition for an inner liner has a butyl rubber content (% by mass) and an isoprene rubber content (% by mass) in 100% by mass of the rubber component, and a layered silicate mineral content (parts by mass) and an aliphatic aromatic copolymer resin content (parts by mass) relative to 100 parts by mass of the rubber component that satisfy the following formula (1):

number

[0011] (rubber component) The rubber composition contains a butyl-based rubber and an isoprene-based rubber as rubber components.

[0012] The rubber component usable in the rubber composition is a component that contributes to crosslinking, and is generally a polymer with a weight-average molecular weight (Mw) of 10,000 or more that is not extracted with acetone. The rubber component is in a solid state at room temperature (25°C).

[0013] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, and even more preferably 200,000 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.

[0014] In this specification, the weight average molecular weight (Mw) 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).

[0015] Examples of butyl rubbers include butyl rubber and halogenated butyl rubbers such as chlorinated butyl rubber (Cl-IIR), brominated butyl rubber (Br-IIR), and fluorinated butyl rubber (F-IIR). Commercially available butyl rubbers include Exprobutyl and Chlorobutyl HT1068 manufactured by ExxonMobil Corporation. These may be used alone or in combination of two or more. Among these, halogenated butyl rubber is preferred as the butyl rubber because it provides good air permeability resistance.

[0016] The butyl rubber may be an unmodified butyl rubber or a modified butyl rubber. The modified butyl rubber may be any butyl rubber having a functional group that interacts with a filler such as silica, and examples thereof include terminally modified butyl rubber (terminally modified butyl rubber having the functional group at the terminal) in which at least one terminal of the butyl rubber has been modified with a compound (modifier) ​​having the functional group, main chain modified butyl rubber having the functional group in the main chain, main chain terminally modified butyl rubber having the functional group in the main chain and at least one terminal (for example, main chain terminally modified butyl rubber having the functional group in the main chain and at least one terminal modified with the modifier), and terminally modified butyl rubber modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or epoxy group introduced therein.

[0017] 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.

[0018] In the rubber composition, the content of the butyl rubber in 100% by mass of the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, and particularly preferably 90% by mass or more. The upper limit is preferably 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0019] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of NR include SIR20, RSS#3, and TSR20, which are commonly used in the rubber industry. Examples of IR include IR2200 and other commonly used rubber products. Examples of modified NR include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. Modified isoprene-based rubbers having functional groups similar to those of the modified butyl-based rubber can also be used. These may be used alone or in combination.

[0020] In the rubber composition, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more. The upper limit is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0021] The rubber composition may contain rubber components other than butyl rubber and isoprene rubber. Examples of other rubbers include diene rubbers such as 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). Fluorine rubbers may also be used. These may be used alone or in combination of two or more. Among these, SBR and BR are preferred from the viewpoint of obtaining the most effective effect.

[0022] 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.

[0023] The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more. The styrene content is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. Within the above range, the effect tends to be more favorable. In this specification, the styrene content of SBR is 1 It is calculated by H-NMR measurement.

[0024] The vinyl content of the SBR is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more. The vinyl content is preferably 90 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less. Within the above range, the effect tends to be more favorable. In this specification, the vinyl content (amount of 1,2-bonded butadiene units) of SBR can be measured by infrared absorption spectroscopy.

[0025] Both unmodified and modified SBR can be used. Modified SBR includes modified SBR with the same functional groups as those in the modified butyl rubber. Hydrogenated styrene-butadiene rubber can also be used as SBR.

[0026] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used.

[0027] When the rubber composition contains SBR, the content of SBR in 100% by mass of the rubber component is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more. The upper limit is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0028] 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.

[0029] The BR may be either unmodified or modified. Examples of modified BR include modified BRs into which functional groups similar to those of the modified butyl rubbers are introduced. The BR may also be hydrogenated butadiene rubber.

[0030] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0031] When the rubber composition contains BR, the BR content in 100% by mass of the rubber component is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more. The upper limit is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0032] (filler) The rubber composition contains carbon black as a filler. Usable carbon black is not particularly limited, but examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., and the like. These may be used alone or in combination of two or more.

[0033] The nitrogen adsorption specific surface area (N2SA) of carbon black is 10m 2 / g or more is preferable, and 15m 2 / g or more is more preferable, and 20m 2 / g or more is more preferable. 2 / g or less is preferable, and 70m 2 / g or less is more preferable, and 35m 2 / g or less is more preferable, and 27m 2 Within the above range, the effect tends to be better. The N2SA of carbon black is a value measured in accordance with JIS K6217-2:2001.

[0034] The compressed oil adsorption number (COAN) of the carbon black is preferably 40 ml / 100 g or more, more preferably 45 ml / 100 g or more, and even more preferably 50 ml / 100 g or more. The COAN is preferably 120 ml / 100 g or less, more preferably 90 ml / 100 g or less, even more preferably 80 ml / 100 g or less, and particularly preferably 69 ml / 100 g or less. Within the above ranges, better effects tend to be obtained. The COAN of the carbon black is a value measured in accordance with ASTM D3493, and the oil used is dibutyl phthalate (DBP).

[0035] In the rubber composition, the carbon black content is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 40 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less. Within the above range, better effects tend to be obtained.

[0036] The rubber composition contains a layered silicate mineral as a filler. Layered silicate minerals have a structural unit of composite layers consisting of stacked tetrahedral sheets containing silicon ions and oxygen ions, and octahedral sheets containing metal ions and oxygen ions and / or hydroxide ions. They are classified into 1:1 type, in which a composite layer is made up of one layer of tetrahedral sheets and one layer of octahedral sheets, and 2:1 type, in which a composite layer is made up of an octahedral sheet sandwiched between a pair of tetrahedral sheets. Examples of 1:1 type layered silicate minerals include the kaolin genus (kaolinite, dickite, halloysite, amesite) and the serpentine genus (chrysotile, lizardite). Examples of 2:1 type layered silicate minerals include the smectite genus (montmorillonite, beidellite, saponite, hectorite, sauconite), the vermiculite genus (vermiculite), the mica genus (muscovite, paragonite, phlogopite, biotite, lepidolite), the brittle mica genus (margarite, clintonite, anandite), the chlorite genus (donbassite, cookeite, sudoite, clinochlore, chamosite, nimite), the talc genus (talc, willemsite), and the pyrophyllite genus (pyrophyllite, ferripyrophyllite). These may be used alone or in combination of two or more.

[0037] Among these layered silicate minerals, 2:1 type layered silicate minerals are preferred from the viewpoint of obtaining better effects, and among the 2:1 type layered silicate minerals, those with a layer charge of 0 (talc, pyrophyllite, etc.) are preferred, and those with a layer charge of 0 and a composite layer containing magnesium ions as a constituent unit (talc, etc.) are more preferred.

[0038] The average particle size of the layered silicate mineral is preferably 0.5 μm or more, more preferably 1.5 μm or more, and even more preferably 3.5 μm or more. The upper limit is preferably 100 μm or less, more preferably 30 μm or less, and even more preferably 10 μm or less. Within the above range, the effect tends to be more favorable. The average particle size of the layered silicate mineral is a value measured by a laser diffraction particle size distribution measuring device.

[0039] The reason why the above-mentioned effects are so pronounced when the average particle size of the layered silicate mineral is within a specified range, particularly 0.5 to 100 μm, is not entirely clear, but it is thought that making it 0.5 μm or more provides the desired effect of inhibiting air permeation, while making it 100 μm or less prevents the layered silicate mineral from becoming the starting point for cracks, resulting in good crack resistance, and thus significantly improving the overall performance of air permeation resistance and crack growth resistance.

[0040] In the rubber composition, the content of the layered silicate mineral is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, and particularly preferably 30 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 80 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0041] The reason why the above-mentioned effects are significantly achieved when the content of the layered silicate mineral is within a specified range, particularly 10 to 50 parts by mass, is not entirely clear, but it is thought that by blending a specified amount of layered silicate mineral or more, the desired improvement in air permeability resistance is achieved, and by adjusting the amount to a specified amount or less, a decrease in elongation is suppressed, resulting in good crack resistance, and thereby significantly improving the overall performance of air permeability resistance and crack growth resistance.

[0042] Fillers (filling materials) that can be used other than carbon black and layered silicate minerals are not particularly limited, and materials known in the rubber field can be used, such as inorganic fillers such as silica, carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica.

[0043] (Aliphatic aromatic copolymer resin) The rubber composition contains an aliphatic-aromatic copolymer resin as a plasticizer. Examples of the aliphatic-aromatic copolymer resin include resins obtained by copolymerizing a material constituting an aliphatic resin with a material constituting an aromatic resin.

[0044] Specific examples of aliphatic aromatic copolymer resins include C5 / C9 copolymer petroleum resins, and more specifically, examples include resins obtained by copolymerizing a C5 fraction (e.g., isoprene, pentene, methylbutene, piperylene, cyclopentene, cyclopentadiene, etc.), which is a petroleum fraction having 4 to 5 carbon atoms, with a C9 fraction (e.g., styrene, vinyltoluene, alkylstyrene, indene, etc.), which is a petroleum fraction having 8 to 10 carbon atoms, and may be hydrogenated or modified. These may be used alone or in combination of two or more.

[0045] In the rubber composition, the content of the aliphatic aromatic copolymer resin is preferably 0.1 parts by mass or more, more preferably 1 part 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 of the content is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0046] The reason why the above-mentioned effects are so pronounced when the content of the aliphatic aromatic copolymer resin is within a predetermined range, particularly 0.1 to 20 parts by mass, is not entirely clear, but it is presumed that by setting the amount of the aliphatic aromatic copolymer resin, which has higher molecular mobility than butyl rubber, within an appropriate range, the formation of areas in the rubber where the molecules are not densely packed is prevented, and air permeation resistance is significantly improved, thereby significantly improving the overall performance of air permeation resistance and crack growth resistance.

[0047] The softening point of the aliphatic aromatic copolymer resin is preferably 60° C. or higher, more preferably 80° C. or higher, and even more preferably 90° C. or higher. The upper limit is preferably 140° C. or lower, more preferably 120° C. or lower, and even more preferably 110° C. or lower. Within the above range, better effects tend to be obtained. In the present disclosure, the softening point 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.

[0048] The weight average molecular weight (Mw) of the aliphatic aromatic copolymer resin is preferably 500 or more, more preferably 1000 or more, and even more preferably 1500 or more. The upper limit is preferably 7000 or less, more preferably 6500 or less, and even more preferably 6000 or less. Within the above range, better effects tend to be obtained.

[0049] Among these, from the viewpoint of obtaining better effects, the aliphatic aromatic copolymer resin is preferably an aliphatic / aromatic copolymer petroleum resin produced by mixing a C5 fraction having a boiling point range of 20 to 110°C obtained by thermal decomposition of petroleum products with a C9 fraction having a boiling point range of 140 to 280°C obtained by thermal decomposition.

[0050] Examples of components constituting the C5 fraction include monoolefinically unsaturated hydrocarbons having 4 to 6 carbon atoms, such as 2-methyl-1-butene, 2-methyl-2-butene, 1-pentene, 2-pentene, and cyclopentene; linear dienes having 4 to 6 carbon atoms, such as isoprene and piperylene; cyclopentadienes, such as cyclopentadiene and methylcyclopentadiene; and aliphatic saturated hydrocarbons, such as cyclopentane, 2-methylpentane, 3-methylpentane, and n-hexane. These may be used alone or in combination of two or more.

[0051] Examples of components constituting the C9 fraction include vinyl aromatic hydrocarbons having 8 to 10 carbon atoms, such as styrene, its alkyl derivatives α-methylstyrene and β-methylstyrene, vinyltoluene, indene and its alkyl derivatives, cyclic unsaturated hydrocarbons, such as dicyclopentadiene and its derivatives, other olefins having 10 or more carbon atoms, and saturated aromatics having 9 or more carbon atoms. These may be used alone or in combination of two or more.

[0052] The aliphatic aromatic copolymer resin preferably has a blend ratio of 30 to 90% by weight of C5 fraction and 70 to 10% by weight of C9 fraction, and more preferably 50 to 90% by weight of C5 fraction and 50 to 10% by weight of C9 fraction. The aliphatic aromatic copolymer resin can be produced by a known method.

[0053] Commercially available aliphatic aromatic copolymer resins include Petrotack (manufactured by Tosoh Corporation), Toho Hi-Resin (manufactured by Toho Chemical Industry Co., Ltd.), Quinton 100 series (manufactured by Nippon Zeon Co., Ltd.), and Escolez 2000 series (manufactured by Exxon Mobil Corporation).

[0054] (plasticizer) The rubber composition may contain a plasticizer other than the aliphatic-aromatic copolymer resin. A plasticizer refers to a material that can impart plasticity to a rubber component. Examples of plasticizers include liquid plasticizers (plasticizers that are liquid (liquid) at 25°C) and solid plasticizers (plasticizers that are solid at 25°C). Plasticizers may be used alone or in combination of two or more types.

[0055] The liquid plasticizer is not particularly limited, and examples thereof include oil, liquid resin, liquid diene polymer, etc. Among them, oil is preferred from the viewpoint of obtaining a more effective effect.

[0056] The oil is not particularly limited, and examples thereof include known oils such as process oil, vegetable oil, or a mixture thereof. Examples of process oils that can be used include paraffin-based process oil (mineral oil), aromatic process oil, naphthenic process oil, and low-PCA (polycyclic aromatic) process oils such as TDAE and MES. Examples of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil (canola oil), soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, macadamia nut oil, and tung oil. These oils may be used alone or in combination of two or more. Among these, vegetable oils and process oils are preferred, and vegetable oils and paraffin-based process oils (mineral oils) are more preferred, from the viewpoint of obtaining better effects.

[0057] In the rubber composition, the content of the liquid plasticizer 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 20 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, the effect tends to be more favorably obtained. When rubber extended with a liquid plasticizer such as oil-extended rubber is used, the amount of extending oil is also included in the content of the liquid plasticizer (oil, etc.). The oil content is also preferably in a similar range.

[0058] Examples of solid plasticizers include aromatic vinyl polymers that are solid at room temperature (25° C.), coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, acrylic resins, etc. The resins may be hydrogenated. The solid plasticizer also includes the aliphatic-aromatic copolymer resins that are solid at room temperature (25° C.) These may be used alone or in combination of two or more.

[0059] In the rubber composition, the content of the solid plasticizer (total amount of the aliphatic-aromatic copolymer resin in a solid state at room temperature (25°C) and other solid plasticizers) is preferably 0.1 parts by mass or more, more preferably 1 part 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 of the content is preferably 30 parts by mass or less, more preferably 20 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.

[0060] Examples of the plasticizer 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, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Industry Co., Ltd.

[0061] (Other ingredients) The rubber composition preferably contains an antioxidant from the viewpoint of crack resistance, ozone resistance, and the like.

[0062] The antioxidant is not particularly limited, but 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, N,N'-di-2-naphthyl-p-phenylenediamine, and the like. Examples of suitable antioxidants include p-phenylenediamine antioxidants such as amines; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine antioxidants and quinoline antioxidants are preferred, with polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline being more preferred. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis.

[0063] In the rubber composition, the content of the antioxidant is preferably 0.2 parts by mass or more, more preferably 2.0 parts by mass or more, and even more preferably 3.0 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 4.0 parts by mass or less.

[0064] The rubber composition preferably contains stearic acid. In the rubber composition, the content of stearic acid is preferably 0.5 to 10.0 parts by mass, and more preferably 1.5 to 4.0 parts by mass, per 100 parts by mass of the rubber component.

[0065] 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.

[0066] The rubber composition preferably contains zinc oxide. In the rubber composition, the content of zinc oxide is preferably 0.5 to 10.0 parts by mass, and more preferably 1.5 to 6.0 parts by mass, per 100 parts by mass of the rubber component.

[0067] 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.

[0068] The rubber composition may contain wax. In the rubber composition, the content of the wax is preferably 0.5 to 10.0 parts by mass, and more preferably 1.5 to 5.0 parts by mass, based on 100 parts by mass of the rubber component.

[0069] The wax is not particularly limited, and examples thereof include petroleum waxes, natural waxes, etc. Synthetic waxes obtained by refining or chemically treating multiple waxes can also be used. These waxes may be used alone or in combination of two or more types.

[0070] Examples of petroleum-based waxes include paraffin wax and microcrystalline wax. Natural waxes are not particularly limited as long as they are derived from non-petroleum resources, and include, for example, plant-based waxes such as candelilla wax, carnauba wax, Japan wax, rice wax, and jojoba wax; animal-based waxes such as beeswax, lanolin, and spermaceti; mineral-based waxes such as ozokerite, ceresin, and petrolactam; and refined products thereof. Commercially available products include those from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd.

[0071] It is preferable to compound sulfur into the rubber composition, in that sulfur forms an appropriate amount of crosslinked chains in the polymer chains and imparts good performance.

[0072] In the rubber composition, the sulfur content is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, and even more preferably 0.5 part 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, and even more preferably 1.5 parts by mass or less.

[0073] 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.

[0074] The rubber composition preferably contains a vulcanization accelerator. In the rubber composition, the content of the vulcanization accelerator (total amount of vulcanization accelerator) is not particularly limited and may be freely determined according to the desired vulcanization rate and crosslink density, but is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.25 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, and even more preferably 4.5 parts by mass or less. Within the above range, better effects tend to be obtained.

[0075] The type of vulcanization accelerator is not particularly limited, and commonly used ones can be used. Examples of the vulcanization accelerator include thiazole-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 and guanidine-based vulcanization accelerators are preferred.

[0076] In addition to the above components, the rubber composition may contain appropriate additives, such as release agents, pigments, and other common additives used in the rubber composition depending on the field of application. The content of the additives in the rubber composition is preferably 0.5 to 10 parts by mass, more preferably 2 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0077] From the viewpoint of obtaining better effects, it is desirable that the contents of the layered silicate mineral and the aliphatic aromatic copolymer resin contained in the rubber composition (the content (parts by mass) of the layered silicate mineral and the content (parts by mass) of the aliphatic aromatic copolymer resin per 100 parts by mass of the rubber component) satisfy the following formula: 0.5<Layered silicate mineral content / Aliphatic aromatic copolymer resin content<20.0 The ratio of the layered silicate mineral content to the aliphatic aromatic copolymer resin content is preferably 2.0 or more, more preferably 4.0 or more, even more preferably 6.0 or more, and particularly preferably 8.0 or more, and is preferably 16.0 or less, more preferably 12.0 or less, and even more preferably 10.0 or less. Within the above ranges, the effect tends to be better obtained.

[0078] The reason why the aforementioned effects are so pronounced when the "content of layered silicate mineral / content of aliphatic aromatic copolymer resin" is within a specified range is not entirely clear, but it is presumed that the effect of improving air permeability resistance due to the layered silicate mineral and the effect of improving rubber strength due to the aliphatic aromatic copolymer resin are achieved in a well-balanced manner, thereby significantly improving the overall performance of air permeability resistance and crack growth resistance.

[0079] The rubber composition can be produced by a known method. For example, the rubber composition can be produced by kneading the components using a rubber kneading device such as an open roll or a Banbury mixer, and optionally crosslinking the components. The kneading conditions are as follows: the kneading temperature is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30 seconds to 30 minutes, preferably 1 minute to 30 minutes.

[0080] <Tires> The rubber composition is used as an inner liner for a tire. Examples of the tire include pneumatic tires and non-pneumatic tires, with pneumatic tires being preferred. The rubber composition can be particularly suitably used as a summer tire or a winter tire (such as a studless tire, snow tire, or studded tire). The tire can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a heavy-duty tire for trucks, buses, or the like, a light truck tire, a motorcycle tire, or a racing tire (high-performance tire).

[0081] A tire is manufactured by a conventional method using the above rubber composition. For example, a rubber composition containing various materials is extruded in an unvulcanized state to match the shape of an inner liner, and then molded together with other tire components in a tire building machine by a conventional method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in the vulcanizer to obtain a tire.

[0082] The tire of the present disclosure is provided with an inner liner made of the rubber composition, and from the viewpoint of obtaining better effects, it is desirable that the thickness T (mm) of the inner liner satisfy the following formula: 0.5mm≦T≦3.0mm The lower limit of T is preferably 0.7 mm or more, more preferably 0.9 mm or more, and even more preferably 1.0 mm or more. The upper limit is preferably 2.5 mm or less, more preferably 2.0 mm or less, and even more preferably 1.5 mm or less. Within the above ranges, the effect tends to be preferably obtained.

[0083] The reason why the above-mentioned effects are so pronounced when the thickness T of the inner liner is within a predetermined range is not entirely clear, but it is presumed that the layered silicate mineral's effect of improving air permeability resistance and the aliphatic-aromatic copolymer resin's effect of improving rubber strength are both pronounced, resulting in a significant improvement in the overall performance of air permeability resistance and crack growth resistance.

[0084] In the present disclosure, the thickness T of the inner liner refers to the maximum dimension (maximum thickness of the inner liner) among the thicknesses of each inner liner at each point on the inner surface of the inner liner. The thickness at each point on the inner surface of the inner liner is a value measured along the normal to the inner surface of the inner liner at that point, and the thickness T of the inner liner is the maximum thickness at each point. The thickness at each point is the distance from the inner surface of the inner liner on the tire cavity side to the interface with other layers (carcass layer, belt layer, etc.) in a cross section cut along a plane including the tire axis.

[0085] In this specification, unless otherwise specified, the thickness T of the inner liner is measured when the tire is mounted on a standard rim and inflated to a standard internal pressure (also referred to as a standard state). No load is applied to the tire during measurement. For example, in the case of a passenger car tire, the dimensions and angles are measured when the internal pressure is 180 kPa.

[0086] A genuine rim is a rim specified in the standard on which the tire is based. The "standard rim" in the JATMA standard, the "design rim" in the TRA standard, and the "measuring rim" in the ETRTO standard are genuine rims. The genuine internal pressure is the internal pressure specified in the standard on which the tire 1 is based. The "maximum air pressure" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard are genuine internal pressures.

[0087] In order to obtain better effects in the tire of the present disclosure, it is desirable that the thickness T (mm) of the inner liner and the content of the layered silicate mineral contained in the rubber composition for the inner liner that constitutes the inner liner (the content (parts by mass) of the layered silicate mineral per 100 parts by mass of the rubber component) satisfy the following formula: Layered silicate mineral content / inner liner thickness ≥ 15 The ratio of the layered silicate mineral content to the thickness of the inner liner is preferably 20 or more, more preferably 30 or more, and even more preferably 40 or more, and is preferably 100 or less, more preferably 80 or less, and even more preferably 60 or less. Within the above ranges, the effect tends to be better obtained.

[0088] The reason why the above-mentioned effect is significantly achieved when the "content of layered silicate mineral / thickness of inner liner" is a specified amount or more is not entirely clear, but it is presumed that by incorporating a sufficient amount of layered silicate mineral, the effect of improving air permeability resistance due to the layered silicate mineral is significantly achieved, thereby significantly improving the overall performance of air permeability resistance and crack growth resistance.

[0089] In the tire of the present disclosure, from the viewpoint of obtaining better effects, it is desirable that the thickness T (mm) of the inner liner and the content of the aliphatic aromatic copolymer resin contained in the rubber composition for the inner liner that constitutes the inner liner (the content (parts by mass) of the aliphatic aromatic copolymer resin per 100 parts by mass of the rubber component) satisfy the following formula: Aliphatic aromatic copolymer resin content / thickness of inner liner ≧ 1.0 The ratio of the content of the aliphatic aromatic copolymer resin to the thickness of the inner liner is preferably 3.0 or more, more preferably 5.0 or more, and is preferably 20.0 or less, more preferably 10.0 or less. Within the above ranges, better effects tend to be obtained.

[0090] The reason why the above-mentioned effect is significantly achieved when the "content of aliphatic aromatic copolymer resin / thickness of inner liner" is equal to or greater than a predetermined value is not necessarily clear, but it is presumed that by compounding a sufficient amount of aliphatic aromatic copolymer resin, the effect of improving the strength of the rubber is significantly achieved, thereby significantly improving the overall performance of air permeation resistance and crack growth resistance.

[0091] An example of a tire according to the present disclosure having an inner liner made of the rubber composition will be described with reference to FIG. 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 tread 4 includes a cap layer 30 and a base layer .

[0092] Although FIG. 1 shows an example of a two-layer structure tread 4 consisting of a cap layer 30 and a base layer 28, a single-layer structure tread or a tread portion having a structure of three or more layers may also be used.

[0093] In the tire 2, each sidewall 6 extends substantially radially inward from an end of the tread 4. A radially outer portion of each sidewall 6 is joined to the tread 4. A radially inner portion of each sidewall 6 is joined to a clinch 10. The sidewall 6 can prevent damage to the carcass 14.

[0094] 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.

[0095] Each clinch 10 is located approximately radially inward of the sidewall 6. The clinches 10 are located axially outward of the beads 12 and the carcass 14.

[0096] Each bead 12 is located axially inward of the clinch 10. The bead 12 includes a core 32 and an apex 34 extending radially outward from the core 32. The core 32 is preferably ring-shaped and includes a wound non-extensible wire. The apex 34 tapers radially outward.

[0097] 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.

[0098] In the tire 2, the carcass ply 36 is laid between the beads 12 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 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.

[0099] 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 equator plane is preferably 75° to 90°. In other words, the carcass 14 preferably has a radial structure.

[0100] 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. The belt layer 16 is composed 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 (see JATMA).

[0101] Although not shown, each of the inner layer 38 and the outer layer 40 preferably comprises a large number of cords arranged in parallel and a topping rubber. In other words, the belt layer 16 includes a large number of cords arranged in parallel. Each cord is inclined with respect to the equatorial plane. The absolute value of the inclination angle is generally 10° or more and 35° or less. The inclination direction of the cords of the inner layer 38 with respect to the equatorial plane is opposite to the inclination direction of the cords of the outer layer 40 with respect to the equatorial plane.

[0102] 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.

[0103] 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.

[0104] 1 constitute a reinforcing layer. The reinforcing layer may be constituted by the belt layer 16 alone.

[0105] FIG. 2 is an enlarged view of the vicinity of the equatorial plane CL of the tire 2 in FIG. 2 indicates the thickness of the inner liner 20 at a predetermined point on the inner liner inner surface 51, and is a value measured along the normal to the inner liner inner surface 51 at that point. The thickness T of the inner liner 20 is the maximum value of the thickness at each point (maximum thickness of the inner liner).

[0106] The inner liner 20 is located inside the carcass 14. The inner liner 20 is bonded to the inner surface of the carcass 14. A typical base rubber of the inner liner 20 is butyl rubber or halogenated butyl rubber. The inner liner 20 maintains the internal pressure of the tire 2.

[0107] The tire 2 has an inner liner 20 made of the above-mentioned rubber composition for an inner liner.

[0108] In the tire 2, it is desirable that the thickness T of the inner liner 20, the content of the layered silicate mineral in the rubber composition for the inner liner, and the content of the aliphatic aromatic copolymer resin satisfy the above-mentioned formulas "0.5 mm≦T≦3.0 mm", "content of layered silicate mineral / thickness of inner liner≧15", and "content of aliphatic aromatic copolymer resin / thickness of inner liner≧1.0".

[0109] 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.

[0110] 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.

[0111] 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. [Example]

[0112] 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.

[0113] Tires obtained by varying the formulation according to Table 1 using the various chemicals shown below were examined, and the results calculated based on the evaluation method described below are shown in Table 1.

[0114] (rubber component) Butyl rubber: Chlorobutyl HT1068 (chlorinated butyl rubber (Cl-IIR)) manufactured by ExxonMobil NR:TSR20

[0115] (Chemicals other than rubber components) Carbon black: "Seast V" (N660, N2SA: 27m) manufactured by Tokai Carbon Co., Ltd. 2 / g, COAN:69ml / 100g) Layered silicate mineral 1: Imerys SB-100S (kaolin clay, average particle size: 6.0-7.0 μm) Layered silicate mineral 2: Mistron 850JS (talc, average particle size: 4.5 to 5.5 μm) manufactured by Nippon Mistron Co., Ltd. Layered silicate mineral 3: Polyfil DL (kaolin clay, average particle size: 3.5-4.5 μm) manufactured by Kamin Aliphatic aromatic copolymer resin 1: Petrotack 100V (C5C9 petroleum resin, Mw 3800, softening point 96°C) manufactured by Tosoh Corporation Aliphatic aromatic copolymer resin 2: Petrotack 90 (C5C9 petroleum resin, Mw 1600, softening point 95°C) manufactured by Tosoh Corporation Aliphatic aromatic copolymer resin 3: T-REZ PR802 manufactured by ENEOS Co., Ltd. (C5C9 petroleum resin, Mw 1370, softening point 90°C) C5 petroleum resin: Maruzen Petrochemical Co., Ltd.'s MARKARETS T-100AS (C5 petroleum resin: an aliphatic petroleum resin made primarily from olefins and diolefins in the C5 fraction obtained by naphtha cracking, softening point: 100°C) Oil: Diana Process PA32 (mineral oil) manufactured by Idemitsu Kosan Co., Ltd. Zinc oxide: Zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: NOF Corporation's "Tsubaki" stearic acid Sulfur: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd. Vulcanization accelerator: Noccela MP (2-mercaptobenzothiazole) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0116] <Production of test tires> According to the formulation shown in Table 1, chemicals other than sulfur and vulcanization accelerator are kneaded for 4 minutes at 160°C using a 16L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded mixture. Next, sulfur and a vulcanization accelerator are added to the kneaded mixture, and the mixture is kneaded using an open roll at 80° C. for 4 minutes to obtain an unvulcanized polymer composition. The unvulcanized polymer composition is molded into the shape of an inner liner, and is laminated together with other tire components on a tire building machine to form an unvulcanized tire. The unvulcanized tire is then vulcanized at 170°C for 12 minutes to produce a test tire (size: 195 / 65R15, specifications: Table 1).

[0117] <Air permeability resistance (gas permeability test)> A sample is taken from the inner liner of the test tire and the air permeability of the sample is measured according to ASTM D-1434-75M method. The air permeability of Comparative Example 1 is set to 100, and the air permeability resistance index is expressed as an index according to the following calculation formula: A larger index indicates a smaller air permeability and better air permeability resistance. (Air permeability index) = (Air permeability of Comparative Example 1) / (Air permeability of each formulation) × 100

[0118] <Crack growth resistance (fracture characteristics)> A sample was taken from the inner liner of the test tire, and a dumbbell-shaped No. 6 test piece was prepared from the sample based on JIS K6251:2010. A tensile test was carried out using the test piece in an atmosphere of 25°C to measure the breaking strength TB (MPa) and elongation at break EB (%), and the breaking energy was calculated as TB × EB (MPa·%) / 2. The fracture energy of each formulation was calculated and expressed as an index, with the fracture energy of Comparative Example 1 being set at 100. A larger index indicates better crack growth resistance (crack resistance).

[0119] <Overall performance> The overall performance of air permeability resistance and crack growth resistance is evaluated as the sum of the air permeability resistance (index) and the crack growth resistance (index). The higher the index, the better the overall performance.

[0120] <Moldability> Mooney viscosity ML of unvulcanized rubber composition at 130°C according to JIS K6300 (1+4)The Mooney viscosity value and sheet processability (burn resistance during sheet production, flatness of the sheet) are evaluated comprehensively. The moldability of Example 11 is expressed as an index, with 100 being the index. The larger the index, the more stable the gauge (thickness of the rubber) during molding and the better the moldability. Note that when the index is 100 or more, practical moldability can be ensured.

[0121] [Table 1]

[0122] The present disclosure (1) includes a butyl rubber, an isoprene rubber, carbon black, a layered silicate mineral, and an aliphatic-aromatic copolymer resin, The rubber composition for an inner liner has a content (% by mass) of the butyl rubber and a content (% by mass) of the isoprene rubber in 100% by mass of the rubber component, a content (parts by mass) of the layered silicate mineral relative to 100 parts by mass of the rubber component, and a content (parts by mass) of the aliphatic-aromatic copolymer resin relative to 100 parts by mass of the rubber component, which satisfy the following formula (1):

number

[0123] The present disclosure (2) is the rubber composition for an inner liner according to the present disclosure (1), wherein the content of the layered silicate mineral is 10 to 50 parts by mass per 100 parts by mass of the rubber component.

[0124] The present disclosure (3) is a rubber composition for an inner liner according to the present disclosure (1) or (2), wherein the content of the aliphatic aromatic copolymer resin is 0.1 to 20 parts by mass per 100 parts by mass of the rubber component.

[0125] The present disclosure (4) is the rubber composition for an inner liner according to any one of the present disclosures (1) to (3), wherein the layered silicate mineral has an average particle size of 0.5 to 100 μm.

[0126] The present disclosure (5) is a rubber composition for an inner liner according to any one of the present disclosures (1) to (4), in which the contents of the layered silicate mineral and the aliphatic aromatic copolymer resin satisfy the following formula: 6.0<Layered silicate mineral content / Aliphatic aromatic copolymer resin content<12.0

[0127] The present disclosure (6) is a tire having an inner liner made of the rubber composition according to any one of the present disclosures (1) to (5).

[0128] The present disclosure (7) is the tire according to the present disclosure (6), wherein the thickness of the inner liner is 0.5 to 3.0 mm.

[0129] The present disclosure (8) is a tire according to the present disclosure (6) or (7), in which the thickness (mm) of the inner liner and the content (parts by mass) of the layered silicate mineral per 100 parts by mass of the rubber component in the rubber composition for the inner liner satisfy the following formula: Layered silicate mineral content / inner liner thickness ≥ 30

[0130] The present disclosure (9) is a tire according to any one of the present disclosures (6) to (8), in which the thickness (mm) of the inner liner and the content (parts by mass) of the aliphatic aromatic copolymer resin relative to 100 parts by mass of the rubber component in the rubber composition for the inner liner satisfy the following formula: Aliphatic aromatic copolymer resin content / thickness of inner liner ≥ 3.0 [Explanation of symbols]

[0131] 2. Pneumatic tires 3 Side section 4 Tread 6 Sidewall 8 Wing 10 Clinch 12 beads 14 Carcass 16 Belt 18 bands 20 Inner liner 22 Chafer 26 Groove 28 base layer 30 cap layers 32 cores 34 Apex 36 Carcass ply 36a Main part 36b Folded part 38 Inner layer 40 outer layer 42 Main groove 44 Ribs 51 Inner liner inner surface CL Equatorial plane of tire 2 T1: Thickness of the inner liner at a given point on the inner liner inner surface 51

Claims

1. The rubber composition contains a butyl rubber, an isoprene rubber, carbon black, a layered silicate mineral, and an aliphatic-aromatic copolymer resin, The aliphatic aromatic copolymer resin is a C5 / C9 copolymer petroleum resin, The rubber composition for an inner liner, in which the contents (% by mass) of the butyl-based rubber and the isoprene-based rubber in 100% by mass of the rubber component, the contents (parts by mass) of the layered silicate mineral and the contents (parts by mass) of the aliphatic-aromatic copolymer-based resin relative to 100 parts by mass of the rubber component, satisfy the following formula (1): [Equation 1]

2. 2. The rubber composition for an inner liner according to claim 1, wherein the content of the layered silicate mineral is 10 to 50 parts by mass per 100 parts by mass of the rubber component.

3. 3. The rubber composition for an inner liner according to claim 1, wherein the content of the aliphatic aromatic copolymer resin is 0.1 to 20 parts by mass per 100 parts by mass of the rubber component.

4. 4. The rubber composition for an inner liner according to claim 1, wherein the layered silicate mineral has an average particle size of 0.5 to 100 μm.

5. 5. The rubber composition for an inner liner according to claim 1, wherein the contents of the layered silicate mineral and the aliphatic aromatic copolymer resin satisfy the following formula: 6.0<content of layered silicate mineral / content of aliphatic aromatic copolymer resin<12.0

6. A tire having an inner liner made of the rubber composition according to any one of claims 1 to 5.

7. 7. The tire according to claim 6, wherein the thickness of the inner liner is 0.5 to 3.0 mm.

8. The tire according to claim 6 or 7, wherein the thickness (mm) of the inner liner and the content (parts by mass) of the layered silicate mineral per 100 parts by mass of the rubber component in the rubber composition for the inner liner satisfy the following formula: Content of layered silicate mineral / thickness of inner liner≧15

9. The tire according to any one of claims 6 to 8, wherein the thickness (mm) of the inner liner and the content (parts by mass) of the aliphatic-aromatic copolymer resin per 100 parts by mass of the rubber component in the rubber composition for the inner liner satisfy the following formula: Content of aliphatic aromatic copolymer resin / thickness of inner liner≧3.0

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