Tire

Abstract

To further improve durability.SOLUTION: A tire comprises: a carcass comprising a carcass cord; a belt which comprises a belt cord and is provided outside the carcass in a tire radial direction; a band which comprises a band cord comprising a polyester fiber and is provided outside the belt in the tire radial direction; and a tread provided outside the band in the tire radial direction. The belt cord is a cord comprising four filaments. A diameter (mm) of the band cord and a diameter (mm) of the belt cord satisfy the following expression: |the diameter of the band cord-the diameter of the belt cord |<0.40.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] Patent Document 1 describes a pneumatic tire including a carcass, a belt, and a band.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to further improve durability.

Means for Solving the Problems

[0005] The present invention is a carcass including carcass cords, a belt including belt cords provided on the outer side in the tire radial direction of the carcass, a band including band cords containing polyester fibers provided on the outer side in the tire radial direction of the belt, and a tread provided on the outer side in the tire radial direction of the band, and is a tire characterized in that the belt cords are cords composed of four filaments, and the diameter (mm) of the band cords and the diameter (mm) of the belt cords satisfy the following formula. |Diameter of band cord - Diameter of belt cord| < 0.40

Effects of the Invention

[0006] According to the present invention, further improvement in durability can be achieved.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0008] [1] Features of the Tire According to the Present Invention First, the features of the tire according to the present invention will be described.

[0009] 1. Overview The tire according to the present invention includes a carcass provided with carcass cords, a belt provided with belt cords and disposed on the outer side in the tire radial direction of the carcass, a band provided with band cords containing polyester fibers and disposed on the outer side in the tire radial direction of the belt, and a tread disposed on the outer side in the tire radial direction of the band. And the belt cord is a cord composed of four filaments. Also, the diameter (mm) of the band cord and the diameter (mm) of the belt cord satisfy the following formula. |Diameter of band cord - Diameter of belt cord| < 0.40

[0010] By having these features, as will be described later, further improvement in the durability of the tire can be achieved.

[0011] In the above, the "diameter of the cord" in the diameter of the band cord and the diameter of the belt cord refers to the diameter when the circumscribed circle of the cross-section perpendicular to the extending direction of the cord is a perfect circle, and in the case of an ellipse or the like, it refers to the equivalent diameter of a circle (the diameter of the circle assumed when the cross-sectional area is the same).

[0012] 2. Mechanism of Effect Manifestation in the Tire According to the Present Invention Regarding the mechanism for the above-described effects in the tire according to the present invention, it is considered as follows.

[0013] In the tire according to the present invention, the belt cord is composed of four filaments. As a result, the cord diameter can be reduced while maintaining strength, so it is considered that the thickness of the rubber (rubber gauge) topped on the belt cord can be made thinner, and further improvement in the durability of the tire can be achieved.

[0014] Further, by reducing the difference between the diameter (mm) of the band cord and the diameter (mm) of the belt cord, specifically, making |diameter of band cord - diameter of belt cord| < 0.40, the difference between the stress of the band and the stress of the belt can be reduced. Therefore, it is considered that the looseness between the band and the belt can be sufficiently suppressed, and the durability can be improved.

[0015] Note that |diameter of band cord - diameter of belt cord| is more preferably 0.30 or less, and even more preferably 0.20 or less.

[0016] [2] More preferred embodiments of the tire according to the present invention The tire according to the present invention can obtain a greater effect by adopting the following embodiments.

[0017] 1. Ends of the band cord and the belt cord In the present invention, it is preferable that the difference between the ends E BA of the band cord and the ends E BE of the belt cord is small. As a result, the difference between the stress of the band and the stress of the belt described above can be further reduced. Therefore, it is considered that the looseness between the band and the belt can be further suppressed, and further improvement in durability can be achieved. In this specification, "ends" means "the number of cords per 50 mm width in the tire width direction".

[0018] Specifically, |E BA - E BEIf <30, it is considered that further improvement in durability can be achieved. Note that |E BA -E BE | is more preferably 15 or less, and particularly preferably 0.

[0019] 2. Bending rigidity of the belt cord In the present invention, the bending rigidity of the belt cord is preferably small. Thereby, the belt cord becomes more flexible, and the stress difference from the band cord becomes smaller, so it is considered that further improvement in durability can be achieved.

[0020] Specifically, if it is less than 50 (g·cm), it is considered that further improvement in durability can be achieved. More preferably, it is 40 (g·cm) or less, and even more preferably 20 (g·cm) or less.

[0021] The bending rigidity of the belt cord described above can be measured according to the following procedure using, for example, a rigidity tester (e.g., model 150-D) manufactured by TABER Co., Ltd. (USA). First, attach both ends of a belt cord with a length of 145 mm to the clamps of the rigidity tester, and apply bending angles of +15 degrees and -15 degrees to the belt cord 10 as shown in FIG. 2. Then, the average value of the bending moment at +15 degrees and the bending moment at -15 degrees is defined as the bending rigidity value (g·cm).

[0022] 3. Intermediate elongation and thermal shrinkage rate of the band cord In the present invention, it is preferable that both the intermediate elongation and the thermal shrinkage rate of the band cord are low. Thereby, the dimensional stability is further improved, it becomes difficult to stretch, and it approaches the hardness of the belt, so it is considered that the loop between the band and the belt can be further suppressed and further improvement in durability can be achieved.

[0023] Specifically, if the sum of the intermediate elongation (%) and the thermal shrinkage rate (%) of the band cord is less than 15, it is considered that further improvement in durability can be achieved. More preferably, it is 10 or less.

[0024] The intermediate elongation percentage (%) of the band cord can be determined from the elongation percentage at a load of 44 N in the "load-elongation" curve of the band cord determined under the environment of room temperature (25°C ± 2°C) in accordance with "JIS L1017:2002 Test Methods for Chemical Fiber Tire Cords".

[0025] Also, the heat shrinkage rate (%) of the band cord can be determined from the ratio y / x (%) of the amount of shrinkage y (mm) to the length x (mm) of the band cord before standing when the band cord is left standing for 30 minutes at a temperature of 180°C in a no-load state in accordance with "JIS L1017:2002 Test Methods for Chemical Fiber Tire Cords".

[0026] The band may be one layer or two layers. Also, the band may be formed across the entire width direction of the tread, or may be formed only at both ends of the tread. The band cord can be composed of fibers. As the fibers constituting the band cord, polyester fibers can be used, and PET (polyethylene terephthalate) fibers and PEN (polyethylene naphthalate) fibers are preferred, and PET fibers are more preferred. Also, the fibers constituting the band cord may be fibers recycled from used products or waste products, or may be fibers synthesized from biomass.

[0027] 4. Use of Sustainable Materials In the tire according to the present invention, the above-mentioned belt, carcass ply, and band are produced by coating both sides of the cord assembly with a conventionally known rubber composition. However, considering the strong demand for environmental protection in recent years, it is preferable to replace the materials constituting these rubber compositions with sustainable materials.

[0028] (1) Rubber Material For example, as the raw materials (monomers) of synthetic rubbers such as SBR and BR, those recycled from rubber products such as tires and non-rubber products such as polystyrene can be used instead of those derived from petroleum.

[0029] The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples thereof include butadiene derived from recycling and aromatic vinyl derived from recycling. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples thereof include styrene. Among them, it is preferable to use butadiene derived from recycling (recycled butadiene) and / or styrene derived from recycling (recycled styrene) as raw materials.

[0030] The method for producing recycled monomers is not particularly limited. For example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. The method for producing recycled naphtha is not particularly limited. For example, rubber products such as tires may be decomposed under high temperature and high pressure, decomposed by microwaves, or extracted after mechanical pulverization.

[0031] Furthermore, the raw materials (monomers) of synthetic rubbers such as SBR and BR may be derived from biomass. The monomers derived from biomass (biomass monomers) are not particularly limited, and examples thereof include butadiene derived from biomass and aromatic vinyl derived from biomass. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples thereof include styrene. The method for producing biomass monomers is not particularly limited, and examples thereof include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical of biological conversion, and examples of chemical and / or physical conversion include those by catalysts, high heat, high pressure, electromagnetic waves, supercritical fluids, and combinations thereof. Examples of the biomass sources of these monomers include sugars, wood, plant residues after obtaining useful components, ethanol derived from plants, and biomass naphtha.

[0032] The polymers synthesized from biomass monomer components (biomass polymers) are not particularly limited, and examples thereof include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers 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.

[0033] Whether the raw material of the polymer is derived from biomass can be determined by pMC (percent Modern Carbon) measured in accordance with ASTM D6866-10.

[0034] pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the standard modern carbon (modern standard reference), and this value is used as an index indicating the biomass ratio of the compound (rubber). The significance of this value will be described below.

[0035] In one mole (6.02×10 23 pieces) of carbon atoms, there are approximately 6.02×10 11 pieces of 14 C, which is about one trillionth of ordinary carbon atoms. 14 C is called a radioactive isotope, and its half-life is 5730 years and it decreases regularly. It takes 226,000 years for all of these to decay. Therefore, after carbon dioxide in the atmosphere and the like are taken up and fixed by plants and the like, in fossil fuels such as coal, oil, and natural gas, which are considered to have passed more than 226,000 years, 14 all of the 14 C elements that were also contained in them at the time of fixation have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain 14 any

[0036] On one hand, 14 C is constantly generated as cosmic rays undergo nuclear reactions in the atmosphere. Its decrease due to radioactive decay is balanced, and in the Earth's atmospheric environment, 14 the amount of C is constant. Therefore, for substances derived from biomass resources that are cycling in the current environment, 14 the C concentration is approximately 1×10 -12 mol% with respect to the total C atoms as described above. Therefore, by utilizing the difference between these values, the ratio (biomass ratio) of the compound derived from natural resources (compound derived from biomass resources) in a certain compound (rubber) can be calculated.

[0037] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 the C concentration ( 13 C / 12 C), 14 the C concentration ( 14 C / 12 C) is measured. In the measurement, 14 as the modern standard reference for the concentration of C, the concentration of 14 C in the circulating carbon in nature in 1950 is adopted. As a specific standard substance, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific activity of carbon (radioactivity intensity of 14 C per 1 g of carbon) in this oxalic acid is separated for each carbon isotope, 13 and for 14 C, it is corrected to a certain value, and the value after applying the decay correction from 1950 AD to the measurement date is used as the value of the standard

[0038] Therefore, if the rubber is made of a 100% biomass (natural) - derived substance, although there are regional differences, it will show a value of approximately 110 pMC (currently, in the normal state, it often does not reach 100). On the other hand, for chemical substances derived from fossil fuels such as petroleum, when measuring this 14 C concentration, it will show almost 0 pMC (for example, 0.3 pMC). This value corresponds to the biomass ratio of 0% mentioned above.

[0039] From the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in the rubber composition is suitable from the perspective of environmental protection.

[0040] Also, as the rubber material, it is also preferable to use vulcanized rubber particles.

[0041] Vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder etc. specified in JIS K 6316:2017 can be used. From the perspectives of environmental consideration and cost, recycled rubber powder produced from crushed waste tires etc. is preferable. These may be used alone or in combination of two or more.

[0042] The vulcanized rubber particles are not particularly limited, and they may be non - modified vulcanized rubber particles or modified vulcanized rubber particles.

[0043] As commercially available products of vulcanized rubber particles, for example, products of Lehigh, Murakami Rubber Industry Co., Ltd. etc. can be used.

[0044] (2) Silica Generally, silica is contained as a reinforcing filler in the rubber composition. Instead of raw materials derived from minerals such as quartz, the use of sustainable silica is also preferable.

[0045] The silica is not particularly limited, and for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), etc., which are common in the tire industry, can be used. The raw material of the silica is not particularly limited, and for example, it may be a raw material derived from a mineral such as quartz, or a raw material derived from a biological source such as rice husk (for example, silica using a biomass material such as rice husk as a raw material), or silica recycled from a product containing silica may be used. Among them, hydrous silica prepared by a wet method is preferred because of its large number of silanol groups. These silicas may be used alone or in combination of two or more.

[0046] Silica using a biomass material as a raw material can be obtained, for example, by extracting a silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to filter, wash with water, dry, and pulverize the resulting silicon dioxide precipitate.

[0047] As the silica recycled from a product containing silica, for example, silica recovered from products containing silica such as electronic components such as semiconductors, tires, desiccants, and filter materials such as diatomaceous earth can be used. The recovery method is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among them, silica recovered from electronic components such as semiconductors or tires is preferred.

[0048] When silica crystallizes, it is insoluble in water and the silicic acid that is its component cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see, for example, Japanese Patent Laid-Open No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.).

[0049] Amorphous silica extracted from rice husks can be those commercially available from Wilmar Co., Ltd. and the like.

[0050] (3) Carbon black And it is also common for the rubber composition to contain carbon black as a reinforcing filler, and it is also preferable to use sustainable carbon black as such carbon black.

[0051] The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762 and the like. The raw material of the carbon black may be a biomass material such as lignin or vegetable oil, or may be a pyrolysis oil obtained by pyrolyzing waste tires. Further, the production method of the carbon black may be by combustion such as the furnace method, may be by hydrothermal carbonization (HTC), or may be by thermal decomposition of methane such as the thermal black method. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbian Carbon Company, etc. can be used. These may be used alone or in combination of two or more.

[0052] (4) Oil Examples of oils commonly used as softeners include process oils, vegetable oils, animal oils, etc. Examples of process oils include paraffinic process oils (mineral oils), naphthenic process oils, aromatic process oils, etc. Specific examples of process oils include, for example, MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. Also, process oils with a low content of polycyclic aromatic compounds (PCA) can be used for environmental protection. Examples of the low-PCA-content process oils include MES, TDAE, heavy naphthenic oils, etc. Further, from the perspective of life cycle assessment, it is also possible to use waste oils after being used in rubber mixers or engines, or refined waste cooking oils used in restaurants.

[0053] Specific examples of vegetable oils include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran 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, grape seed oil, wood rosin, etc. Furthermore, vegetable oils include refined oils (such as salad oil) obtained by refining the above oils, transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidatively polymerized oils obtained by oxidizing the above oils, and vegetable oils such as waste cooking oils recovered from those used as edible oils, etc. Note that vegetable oils may be liquid or solid at room temperature (25°C). These vegetable oils may be used alone or in combination of two or more.

[0054] The vegetable oil preferably contains acylglycerol, more preferably contains triacylglycerol. Here, acylglycerol refers to a compound in which the hydroxy group of glycerin and a fatty acid are ester-bonded. 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 multimer of trimer or higher. Note that acylglycerols of dimer or higher can be obtained by thermal polymerization, oxidative polymerization, or the like. Also, the acylglycerol may be liquid or solid at normal temperature (25 °C).

[0055] As a method for confirming whether or not the acylglycerol is contained in the rubber composition, it is not particularly limited, but 1 it can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at normal temperature (25 °C) for 24 hours. After removing the rubber composition, 1 1H-NMR is measured. When the signal of tetramethylsilane (TMS) is set to 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm are observed, and these signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" means a range of ±0.10 ppm.

[0056] The fatty acid is not particularly limited and may be an unsaturated fatty acid or a saturated fatty acid. Examples of the unsaturated fatty acid include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of the saturated fatty acid include butyric acid and lauric acid.

[0057] Among them, as the fatty acid, it is desirable to contain a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As the vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or a vegetable oil subjected to modification such as transesterification may be used. Further, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by variety improvement, genetic recombination, genome editing, etc.

[0058] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Oil Chemical Co., Ltd., ENEOS Co., Ltd., Oryz Oy, H&R, Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0059] (5) Plasticizers other than oil In the rubber composition, as a plasticizer that imparts plasticity to the rubber component, in addition to the above-mentioned oil, a plasticizer that is liquid (liquid state) at room temperature (25°C) and a plasticizer that is solid at room temperature (25°C) are also contained. Examples of such plasticizers include resin components, liquid polymers, ester-based plasticizers, etc. These plasticizers may be derived from petroleum, may be derived from biomass, or may be derived from naphtha recycled from rubber products or non-rubber products (sustainable plasticizers). Further, a low-molecular-weight hydrocarbon component obtained by pyrolyzing and extracting used tires and products containing various components may be used as a plasticizer. These plasticizers may be used alone or in combination of two or more.

[0060] (6) Wax Rubber compositions generally contain wax, and the wax is not particularly limited, and any wax commonly used in the tire industry can be preferably used. For example, petroleum waxes, mineral waxes, synthetic waxes, plant-derived waxes, etc. can be mentioned. Among them, petroleum waxes and plant-derived waxes are preferred, and petroleum waxes are more preferred. Examples of plant-derived waxes include rice wax, carnauba wax, candelilla wax, etc. Examples of petroleum waxes include paraffin wax, microcrystalline wax, and these selected special waxes, etc., and paraffin wax is preferred. As the wax, for example, those commercially available from Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., etc. can be used. These waxes may be used alone or in combination of two or more.

[0061] (7) Antioxidant Rubber compositions generally contain antioxidants, which are not particularly limited, but include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based antioxidants such as 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), N,N'-ditolyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bis, tris, polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys, etc. can be used.

[0062] In the rubber composition, various materials containing carbon atoms (such as rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the formulation of the present invention from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process for synthesizing methane from carbon dioxide may be converted.

[0063] [3] Embodiments Hereinafter, the present invention will be specifically described based on embodiments.

[0064] 1. Tire according to this embodiment FIG. 1 is a schematic cross-sectional view for explaining the structure in an example of the tire according to this embodiment, and shows a tire meridian cross-section including the rotation axis in the normal state of the tire.

[0065] Here, the "normal state" means that the tire is mounted on a normal rim, filled with a normal internal pressure, and is in a no-load state.

[0066] The "normal rim" is the rim defined for each tire in a standard system including the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it refers to the standard rim in the applicable size described in the "JATMA YEAR BOOK"; in the case of ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" described in the "STANDARDS MANUAL"; in the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" described in the "YEAR BOOK". Refer to JATMA, ETRTO, and TRA in this order, and follow the standard if there is an applicable size at the time of reference. In the case of a tire not defined by the standard, it refers to the rim that can be mounted on the tire and can hold the internal pressure, that is, among the rims that do not cause air leakage between the rim / tire, the one with the smallest rim diameter and then the narrowest rim width.

[0067] And the "normal internal pressure" refers to the air pressure determined for each tire in the standard system including the standards on which the tire is based. For JATMA, it is the "maximum air pressure"; for ETRTO, it is the "INFLATION PRESSURE"; for TRA, it refers to the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Refer to JATMA, ETRTO, and TRA in this order, and follow the relevant standard if there is an applicable size during the reference. For a tire not specified in the standard, it refers to the normal internal pressure (however, not less than 250 KPa) of another tire size (specified in the standard) with the above-mentioned normal rim described as the standard rim. In the case where there are multiple normal internal pressures not less than 250 KPa described, it refers to the minimum value among them.

[0068] As shown in FIG. 1, the tire 1 includes a tread 2, a sidewall 3, a bead 4, a carcass 6, and a belt 7. Note that C is the center line. In FIG. 1, the description of the band disposed between the carcass and the tread is omitted.

[0069] (1) Carcass The carcass 6 is composed of a single carcass ply 6A and is locked by turning from the inside to the outside around the bead core 5 of the bead 4 through the sidewall 3 from the tread 2 (1-0 structure). The carcass 6 may be composed of two carcass plies. Also, as the material of the carcass cord, conventionally known materials such as polyester fibers such as PET (polyethylene terephthalate) fibers and PEN (polyethylene naphthalate) fibers, polyamide fibers such as nylon 6 fibers and nylon 66 fibers, and aramid fibers can be used. The fibers constituting the carcass cord may be fibers recycled from used products or waste products, or fibers synthesized from biomass.

[0070] In addition, in FIG. 1, 6a is the inner body part of the carcass ply 6A, 6b is the outer folded-back part, and between the inner body part 6a and the outer folded-back part 6b, for example, a bead apex rubber 8 extending radially outward from the bead core 5 in the tire radial direction is disposed.

[0071] The carcass ply 6A is configured by topping both surfaces of a cord array body in which ply cords of a predetermined linear density are arranged at predetermined ends with a predetermined rubber composition for carcass ply (not shown).

[0072] In the present invention, as the ply cord, a polyester synthetic fiber having a high modulus is used.

[0073] (2) Belt The belt 7 is disposed on the outer side in the radial direction of the carcass 6 and inside the tread 2.

[0074] The belt 7 is composed of one or more (it may be one, two, or three or more) belt plies. In FIG. 1, it is composed of a first belt ply 7A located on the inner side in the tire radial direction and a second belt ply 7B located on the outer side of the first belt ply 7A. Note that three or more belt plies may be used.

[0075] The belt ply is made by topping both surfaces of a cord array body in which a belt cord (the material is metal, particularly iron, and particularly steel is preferable) composed of four filaments is arranged at predetermined ends with a predetermined rubber composition for belt, and is made to have a thinner gauge than the carcass ply (not shown). The filaments constituting the belt cord preferably have a metal material, more preferably iron. Also, its cross-sectional shape is preferably circular, but may be elliptical. And it may be corrugated or may be plated. Also, it may not be twisted, may be single-twisted (1×4), or may be layer-twisted (2+2), but a 1×4 structure is preferable. In the present embodiment, filaments having a circular cross-sectional shape are used in a single-twisted (1×4 structure) without being corrugated.

[0076] By adopting such a belt 7, it is considered that the durability can be improved.

[0077] 2. Tire manufacturing The tire according to this embodiment can be manufactured by a normal method.

[0078] Specifically, on a forming drum, an inner liner as a member for ensuring the airtightness of the tire, a carcass as a member for withstanding the load, impact, and inflation pressure received by the tire, a belt as a member for strongly clamping the carcass to increase the rigidity of the tread, etc. are wound, and at both side edges, both ends of the carcass ply are fixed and a bead as a member for fixing the tire to the rim is arranged, and after forming in a toroidal shape, a tread is attached to the central part of the outer periphery and a sidewall is bonded to the radially outer side to form a side part, thereby producing an unvulcanized tire.

[0079] Thereafter, the unvulcanized tire produced as described above is heated and pressurized in a vulcanizer to obtain a tire. The vulcanization process can be carried out by applying known vulcanization means. As the vulcanization temperature, for example, it is above 120°C and below 200°C, and the vulcanization time is, for example, more than 5 minutes and less than 15 minutes.

[0080] As described above, since the belt and the band of the tire obtained are appropriately formed, further improvement in the durability of the tire can be achieved.

[0081] And the tire according to the present invention can be suitably used as a passenger car tire, a large passenger car tire, a large SUV tire, a small truck tire, etc.

Example

[0082] Hereinafter, examples (examples) considered to be preferable when implementing are shown, but the scope of the present invention is not limited to the said examples.

[0083] For belts and bands other than those with the respective specifications shown in Table 1, substantially the same tires were considered with the configuration shown in Fig. 1 (tire size: 195 / 65R15), and the results calculated based on the evaluation methods for durability and low fuel consumption described below are also shown at the bottom of Table 1.

[0084] 1. Durability Evaluation Each test tire was mounted on a rim (size = 15×6J), filled with air, and the internal pressure was adjusted to 230 kPa. Then, it was mounted on a drum running tester, a vertical load of 5.88 kN was applied, and the speed was gradually increased from 210 km / h in steps of 10 km / h until the tire was damaged, and the time until damage was measured. The results are expressed as an index with Comparative Example 1 set to 100, and the larger the numerical value, the longer the time until damage, indicating excellent durability after high-speed driving.

[0085] Next, with the result in Comparative Example 1 set to 100, it was indexed based on the following formula for durability evaluation. The larger the numerical value, the better the durability. Durability Evaluation = [(Result of test tire) / (Result of Comparative Example 1)] × 100

[0086] 2. Low Fuel Consumption Evaluation Using a rolling resistance tester, for each test tire, the rolling resistance coefficient RRC (Rolling Resistance Coefficient) was measured when running on a drum at a speed of 80 km / h under the following conditions. Rim in use: 15×6J Internal pressure: 210 kPa Load: 4.35 kN

[0087] Next, with the result in Comparative Example 1 set to 100, it was indexed based on the following formula for low fuel consumption evaluation. The larger the numerical value, the better the low fuel consumption. Low Fuel Consumption Evaluation = [(Result of Comparative Example 1) / (Result of test tire)] × 100

[0088] 3. Overall Performance The overall performance is represented by the sum of the indices of durability and low fuel consumption.

[0089]

Table 1

[0090] The above is the description of the present invention based on the embodiments. However, the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments within the same and equivalent scope of the present invention.

[0091] The present invention (1) is a carcass provided with a carcass cord, a belt provided with a belt cord and provided on the outer side in the tire radial direction of the carcass, a band provided with a band cord containing polyester fibers and provided on the outer side in the tire radial direction of the belt, a tire comprising a tread provided on the outer side in the tire radial direction of the band, wherein the belt cord is a cord composed of four filaments, the diameter (mm) of the band cord and the diameter (mm) of the belt cord satisfy the following formula, and the tire is characterized by this. |Diameter of band cord - Diameter of belt cord| < 0.40

[0092] The present invention (2) is the number of cords E per 50 mm width of the band cord BA and the number of cords E per 50 mm width of the belt cord BE satisfy the following formula, and it is the tire described in the present invention (1). |E BA - E BE | < 30

[0093] The present invention (3) is characterized in that the bending stiffness of the belt cord is less than 50 (g·cm), and it is the tire described in the present invention (1).

[0094] The present invention (4) is The sum of the intermediate elongation (%) and the heat shrinkage rate (%) of the band code is less than 15, and it is the tire according to the present invention (1).

Explanation of symbols

[0095] 1 Tire 2 Tread 3 Sidewall 4 Bead 5 Bead core 6 Carcass 6A Carcass ply 6a Inner main body part 6b Outer folded-back part 7 Belt 7A First belt ply 7B Second belt ply 8 Bead apex rubber 10 Band code C Center line

Claims

1. A carcass having a carcass cord; A belt having a belt cord and provided on the outer side in the tire radial direction of the carcass; A band having a band cord containing polyester fibers and provided on the outer side in the tire radial direction of the belt; A tire comprising a tread provided on the outer side in the tire radial direction of the band, wherein The belt cord is a cord composed of four filaments; The tire is characterized in that the diameter (mm) of the band cord and the diameter (mm) of the belt cord satisfy the following formula. |Diameter of band cord - Diameter of belt cord| < 0.40

2. The number of cords E per 50 mm width of the band cord ＢＡ and the number of cords E per 50 mm width of the belt cord ＢＥ satisfy the following formula, and the tire according to claim 1 is characterized in that. |E ＢＡ -E ＢＥ | < 30

3. The tire according to claim 1, wherein the bending stiffness of the belt cord is less than 50 (g·cm).

4. The tire according to claim 1, wherein the sum of the intermediate elongation (%) and the heat shrinkage rate (%) of the band cord is less than 15.

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