Tire

Abstract

To provide a tire having improved durability during high-speed traveling.SOLUTION: A tire comprising a pair of bead portions, each of the bead portions comprising a bead filler extending from a bead core outward in a tire radial direction, and a bead support layer disposed outward of the bead filler in a tire rotational axis direction, the bead support layer being formed of a rubber composition (B), wherein Dt and 70 °C. tan δ (B) satisfy the following formula: 70 °C. tan δ (B) * Dt ≤ 110.0 (1) Dt ≤ 600 (2) SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Tires are required to have a wide range of performance characteristics. One of the major challenges is improving durability during high-speed driving. For example, Patent Document 1 describes that by adjusting the blending amount of an amine-based antioxidant between a bead reinforcing layer and a member adjacent to the layer, migration of the amine-based antioxidant from the adjacent member to the bead reinforcing layer is suppressed, thereby suppressing an increase in heat generation in the bead reinforcing layer and an accompanying decrease in rigidity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-31630 Summary of the Invention [Problem to be solved by the invention]

[0004] With the recent development of expressways, improving tire durability during high-speed driving has become an increasingly important issue.

[0005] An object of the present invention is to provide a tire having improved durability during high-speed running. [Means for solving the problem]

[0006] The present invention relates to the following tire. A tire having a pair of bead portions, The bead portion includes a bead filler extending radially outward from a bead core, and a bead support layer disposed on the outer side of the bead filler in the tire rotational axis direction, the bead support layer is composed of a rubber composition (B), A tire in which, when the outer diameter (mm) of the tire is Dt and the loss tangent of the rubber composition (B) at 70°C is 70°C tan δ(B), Dt and 70°C tan δ(B) satisfy the following formula: (1) 70℃ tanδ(B)×Dt≦110.0 (2) Dt≦600 [Effects of the Invention]

[0007] According to the present invention, a tire having improved durability during high-speed running can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross section of a tire according to one embodiment of the present invention, taken along a plane including the tire rotation axis, where Dt represents the tire outer diameter, and the bead support layer is not covered with clinches. [Figure 2] 1 is a cross section of a tire according to an embodiment of the present invention, taken along a plane including the tire rotation axis, where Dt represents the tire outer diameter. The bead support layer is covered with clinches. [Figure 3] The figure shows a cross section of a tire without a bead support layer, taken along a plane including the tire rotation axis, where Dt indicates the tire outer diameter. DETAILED DESCRIPTION OF THE INVENTION

[0009] A tire according to one embodiment of the present invention is the following tire. A tire having a pair of bead portions, The bead portion includes a bead filler extending radially outward from a bead core, and a bead support layer disposed on the outer side of the bead filler in the tire rotational axis direction, the bead support layer is composed of a rubber composition (B), A tire in which, when the outer diameter (mm) of the tire is Dt and the loss tangent of the rubber composition (B) at 70°C is 70°C tan δ(B), Dt and 70°C tan δ(B) satisfy the following formula: (1) 70℃ tanδ(B)×Dt≦110.0 (2) Dt≦600

[0010] While not intending to be bound by theory, the present invention is believed to improve tire durability during high-speed running through the following mechanism. Specifically, as the tire outer diameter increases, the amount of deformation on the tire sidewall tends to increase, and this increase in deformation is more pronounced near the bead portion than near the tire's maximum width. Therefore, by setting the tire outer diameter to 600 mm or less, the deformation area on the tire sidewall can be reduced, contributing to improved durability. Furthermore, by providing a bead support layer in the bead portion and further setting the product of a predetermined loss tangent (tanδ) of the bead support layer and the tire outer diameter to a certain value or less, the amount of deformation and heat generation in the bead portion are suppressed, contributing to improved durability. These factors are believed to work together to suppress damage near the bead portion during high-speed running, improving tire durability.

[0011] It is preferable that the 70° C. tan δ(B) satisfies the following formula: (3) 70℃ tanδ(B)≦0.15

[0012] This is because heat generation in the bead support layer can be further suppressed.

[0013] The right side of equation (1) is preferably 90.0.

[0014] This is because the effects of the present invention can be more effectively exhibited.

[0015] The right side of equation (2) is preferably 550.

[0016] This is because the effects of the present invention can be more effectively exhibited.

[0017] The right side of equation (3) is preferably 0.10.

[0018] This is because heat generation in the bead support layer can be further suppressed.

[0019] The bead support layer is preferably covered with clinches.

[0020] This is because the effects of the present invention can be more effectively achieved by suppressing distortion of the bead support layer during vehicle travel.

[0021] The clinch is composed of a rubber composition (C), and when the loss tangent of the rubber composition (C) at 70°C is 70°C tanδ(C), it is preferable that 70°C tanδ(C) and 70°C tanδ(B) satisfy the following formula: (4) 70℃tanδ(B) / 70℃tanδ(C)<1.00

[0022] This is because by suppressing heat generation in the clinch layer, the degree of heat transfer to the bead support layer can be reduced.

[0023] The right side of equation (4) is preferably 0.70.

[0024] This is because the effects of the present invention can be more effectively exhibited.

[0025] The tire is preferably a passenger tire.

[0026] This is because passenger cars are one example of vehicles to which tires with an outer diameter of 600 mm or less can be applied.

[0027] <Definition> "Normal condition" refers to a condition in which the tire is mounted on a normal rim and filled with air at normal internal pressure, with no load applied.

[0028] Unless otherwise specified, the "dimensions of each part of the tire" are values ​​that are specified when the tire appears on its outer surface in a normal state, while those that exist inside the tire or on a cut surface of the tire are values ​​that are specified when, for example, the tire is cut along a plane that includes the tire rotation axis and the cut tire piece is maintained within the rim width of a normal rim.

[0029] "Genuine rim" refers to the rim specified for each tire in the standard system that includes the standard on which the tire is based. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organization), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." JATMA, ETRTO, and TRA are referenced in that order, and if an applicable size is available at the time of reference, that standard is followed. In the case of a tire not specified in the above standards, it refers to the narrowest rim among the smallest diameter rims that can be mounted on the tire and can maintain internal pressure (i.e., no air leaks from between the rim and tire).

[0030] "Normal internal pressure" refers to the air pressure specified for each tire in the standard system that includes the standard on which the tire is based. For example, for JATMA, it is "maximum air pressure," for ETRTO, it is "INFLATION PRESSURE," and for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims, refer to JATMA, ETRTO, and TRA in that order, and follow that standard if there is an applicable size at the time of reference. In the case of tires not specified in the above standards, it refers to the normal internal pressure (250kPa or more) of another tire size (defined in the standard) that is specified using the regular rim as the standard rim, and if there are multiple normal internal pressures of 250kPa or more listed, it refers to the smallest value among them.

[0031] "Normal load" refers to the load specified for each tire in the standard system that includes the standard on which the tire is based. For example, for JATMA it is "Maximum Load Capacity", for ETRTO it is "Load Capacity", and for TRA it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". As with normal rims and normal internal pressures, JATMA, ETRTO, and TRA should be referenced in that order, and if there is an applicable size at the time of reference, that standard should be followed. For tires not specified in the above standards, the maximum load capacity W calculated separately should be used. L is the normal load.

[0032] "Maximum load capacity W L " is calculated using the following formula: "V" is the virtual volume of the tire (mm 3 ), "Dt" is the outer diameter (mm) of the tire in its normal state, "Ht" is the tire's cross-sectional height (mm) in the tire's radial direction in a cross section of the tire taken along a plane including the tire's rotation axis, and "Wt" is the tire's cross-sectional width (mm) in its normal state. Ht can be calculated by (Dt-R) / 2, where R is the tire rim diameter. Wt is the value obtained by excluding any patterns or letters on the tire sidewall. Note that maximum load capacity is synonymous with the normal load mentioned above.

[0033]

number

[0034] "Tire outer diameter Dt" refers to the outer diameter of the tire in its normal state.

[0035] The "plasticizer content" includes the amount of plasticizer in the rubber component extended by the plasticizer. Similarly, the "oil content" includes the amount of oil contained in the oil-extended rubber.

[0036] <Measurement method> "Styrene content" is measured by pyrolysis gas chromatography and NMR measurement ( 1 H-NMR and 13The amount of components such as "styrene content" is calculated by C-NMR. Unlike physical property values ​​such as complex modulus (E*), the amount of components such as "styrene content" has a true value that is independent of the measurement method, so it is preferable to use a measurement method with as high accuracy as possible. In this specification, "pyrolysis gas chromatography" refers to a method in which a sample is heated in a pyrolysis device, the individual components contained in the gas phase components generated by this heating are separated using a separation column, and each isolated component is analyzed.

[0037] "Vinyl content (amount of 1,2-bonded butadiene units)" can be measured by pyrolysis gas chromatography or NMR measurement ( 1 H-NMR and 13 It is calculated using C-NMR. As with the "styrene content," there is a true value for the "vinyl content" that is independent of the measurement method, so it is preferable to use a measurement method with as high accuracy as possible.

[0038] "Cis content (cis-1,4-bonded butadiene unit amount)" is measured by infrared absorption spectroscopy or NMR measurement ( 1 H-NMR and 13 This is a value measured by C-NMR and is applied to rubber components that have repeating units derived from butadiene, such as BR. As with the "styrene content," the "cis content" also has a true value that is independent of the measurement method, so it is preferable to use a measurement method with as high accuracy as possible.

[0039] The "weight average molecular weight (Mw)" can be determined by converting the value into standard polystyrene based on a measurement value obtained by gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKgel SuperMultipore HZ-M manufactured by Tosoh Corporation).

[0040] The "nitrogen adsorption specific surface area (N2SA) of carbon black" is measured in accordance with JIS K 6217-2:2017.

[0041] The "nitrogen adsorption specific surface area (N2SA) of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0042] The "average primary particle size" is a value obtained by photographing particles with a transmission or scanning electron microscope and arithmetically averaging the particle sizes of 400 particles. If the particle shape is spherical, the particle size is the diameter of the sphere, and if the particle shape is non-spherical, the particle size is calculated from the microscope image as the circle-equivalent diameter (positive square root of {4 × (particle area) / π}).

[0043] Unless otherwise specified, the "softening point of resin, etc." is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2015 is measured using a ring and ball softening point tester. If the softening point is measured by another method, that fact will be stated.

[0044] "70°C tan δ" is measured using a GABO Iplexer series under the following conditions: temperature 70°C, initial strain 10%, dynamic strain ±1%, frequency 10Hz, and extension mode. When taking samples from the tire, a sample measuring 20mm long x 4mm wide x 1mm thick is taken from the bead reinforcing layer or clinch of each test tire, with the long side aligned tangentially to the tire circumferential direction and the thickness aligned in the tire width direction.

[0045] <Tires> The tire of the present embodiment will be described below with reference to the drawings as appropriate, although the drawings are merely examples for the purpose of explanation.

[0046] The tire of this embodiment is a tire having a pair of bead portions, each of which has a bead filler extending radially outward from a bead core, and a bead support layer arranged axially outward of the bead filler.

[0047] FIG. 1 is a cross-sectional view of a tire 1 having a pair of bead portions according to this embodiment, taken along a plane passing through the tire rotation axis. In FIG. 1, CL represents the tire centerline, which coincides with the tire equatorial plane passing through the center in the tire width direction, and Dt represents the tire outer diameter. The bead portion 2 includes a bead core 3 and a bead filler 4 wrapped around a carcass 7, and a bead support layer 5 disposed on the tire width direction outer side of a folded-up portion of the carcass 7. A clinch 6 is disposed on the tire width direction outer side of the bead support layer 5. Here, the bead support layer 5 is not completely covered by the clinch 6. Here, "the bead support layer is completely covered by the clinch 6" means that, in a cross-sectional view of the tire taken along a plane passing through the tire rotation axis, a clinch is always present on the tire width direction outer side of the bead support layer.

[0048] 2 is a view similar to FIG. 1 of a tire 1 having a pair of bead portions according to this embodiment, but differs from FIG. 1 in that the bead support layer 5 is completely covered with clinches 6. In the tire of this embodiment, it is preferable that the bead support layer 5 is completely covered with clinches 6.

[0049] (Equation (1), Equation (2)) In the tire of this embodiment, when the outer diameter (mm) of the tire is Dt and the loss tangent at 70°C of the rubber composition (B) constituting the bead support layer is 70°C tan δ(B), Dt and 70°C tan δ(B) satisfy the following formula: (1) 70℃ tanδ(B)×Dt≦110.0 (2) Dt≦600

[0050] The value of the right side of formula (1) is preferably 100.0, more preferably 90.0, even more preferably 80.0, even more preferably 70.0, even more preferably 60.0, and even more preferably 55.0. There is no particular lower limit to the value of the left side of formula (1) from the viewpoint of the effects of the present invention, but it may be, for example, 45.0.

[0051] The value of the right side of formula (2) is preferably 599, more preferably 598, even more preferably 597, even more preferably 596, even more preferably 595, even more preferably 590, even more preferably 580, even more preferably 570, even more preferably 560, even more preferably 550, even more preferably 549, even more preferably 548, even more preferably 547, even more preferably 546, even more preferably 545, and even more preferably 540. There is no particular lower limit for the value of the left side of formula (2) from the viewpoint of the effects of the present invention, but it may be, for example, 450.

[0052] Dt is the tire outer diameter, and can be adjusted by increasing or decreasing the tire outer diameter. The 70°C tan δ(B) of rubber composition (B) can be appropriately adjusted by changing the types and amounts of components constituting the rubber composition (described below). For example, 70°C tan δ(B) tends to be increased by increasing the amount of filler, decreasing the particle size of the filler, or decreasing the amounts of vulcanizing agent and vulcanization accelerator. Therefore, 70°C tan δ(B) tends to be decreased by performing the reverse operation.

[0053] From the above, the values ​​on the right-hand sides of equations (1) and (2) can be adjusted to desired values.

[0054] (Formula (3)) In the tire according to the present embodiment, it is preferable that the 70° C. tan δ(B) satisfies the following formula. (3) 70℃ tanδ(B)≦0.15

[0055] The right side of formula (3) is preferably 0.14, more preferably 0.13, even more preferably 0.12, even more preferably 0.11, and even more preferably 0.10. On the other hand, the lower limit of the left side of formula (3) is not particularly limited from the viewpoint of the effects of the present invention, but may be, for example, 0.60.

[0056] The value of 70°C tan δ(B) can be adjusted as described above.

[0057] (Formula (4)) In the tire of this embodiment, when the loss tangent at 70°C of the rubber composition (C) constituting the clinch is 70°C tan δ(C), it is preferable that 70°C tan δ(C) and 70°C tan δ(B) satisfy the following formula: (4) 70℃tanδ(B) / 70℃tanδ(C)<1.00

[0058] The value of the right side of formula (4) is preferably 0.90, more preferably 0.80, even more preferably 0.70, and still more preferably 0.68. There is no particular lower limit to the value of the left side of formula (4) from the viewpoint of the effects of the present invention, but it may be, for example, 0.50.

[0059] The value of 70°C tan δ(B) can be adjusted as described above, and the value of 70°C tan δ(C) can be adjusted in the same way, so the value of the left side of equation (4) can be adjusted by adjusting the values ​​of each of these tan δ.

[0060] <Rubber composition> The rubber composition (B) constituting the bead support layer and the rubber composition (C) constituting the clinch according to this embodiment will be described.

[0061] 1. Rubber composition (B) constituting the bead support layer (rubber component) The rubber component preferably contains at least one rubber component selected from the group consisting of isoprene-based rubber (IR rubber), styrene-butadiene rubber (SBR), and butadiene rubber (BR). The rubber component may also contain at least two rubber components selected from the group consisting of IR rubber, SBR, and BR, or may contain IR rubber, SBR, and BR. The rubber component preferably contains IR rubber and SBR. These rubber components may also be extended rubbers extended with a plasticizer, as described below, or may be rubbers that have been modified or hydrogenated by adding hydrogen to double bonds.

[0062] <Isoprene rubber> 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 tire industry. Examples of IR include IR2200 and other commonly used rubbers. 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. These may be used alone or in combination of two or more.

[0063] The content of the isoprene-based rubber in 100% by mass of the rubber component is preferably more than 20% by mass, more preferably more than 30% by mass, even more preferably more than 40% by mass, and even more preferably 50% by mass or more, from the viewpoint of improving the elongation at break and the crack resistance of the rubber composition. On the other hand, the upper limit of the content of the isoprene-based rubber is preferably less than 90% by mass, more preferably less than 80% by mass, and even more preferably less than 75% by mass, from the viewpoint of suppressing deterioration due to heat, etc.

[0064] SBR The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR). The SBR may be unmodified or modified. Among these, E-SBR is preferred. Hydrogenated styrene-butadiene copolymers (hydrogenated SBR) may also be used as SBR. These may be used alone or in combination of two or more.

[0065] The styrene content of SBR is preferably greater than 5.0% by mass, more preferably greater than 10% by mass, and even more preferably 10.0% by mass or greater. The styrene content is preferably less than 40.0% by mass, more preferably less than 35.0% by mass, and even more preferably less than 30.0% by mass. By keeping the styrene content within the above range, it is believed that microscopic styrene domains can be formed in the rubber component, making it easier to absorb strain due to deformation within the rubber composition. The styrene content can be measured by the method described above.

[0066] The vinyl bond content of SBR is preferably more than 5 mol%, more preferably more than 10 mol%, and even more preferably more than 15 mol%. The vinyl bond content is preferably less than 65 mol%, more preferably less than 40 mol%, and even more preferably less than 20 mol%. The vinyl bond content can be measured by the above-mentioned method.

[0067] The SBR may be SBR extended with a plasticizer (extended SBR), or non-extended SBR. When extended SBR is used, the amount of extension of the SBR, i.e., the content of the extended plasticizer contained in the SBR, is preferably 10 to 50 parts by mass per 100 parts by mass of the rubber solid content of the SBR. Examples of plasticizers used for extension include resins, oils, liquid polymers, and ester-based plasticizers, which will be described later.

[0068] 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.

[0069] The content of SBR in 100% by mass of the rubber component may be 0% by mass, but when SBR is contained, it is preferably more than 5% by mass, more preferably more than 10% by mass, even more preferably more than 20% by mass, and still more preferably more than 25% by mass. The upper limit of the SBR content is preferably less than 60% by mass, more preferably less than 50% by mass, and still more preferably less than 40% by mass.

[0070] 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.

[0071] In particular, the BR preferably contains high-cis BR with a cis content of more than 90 mol %. The cis content is more preferably more than 95 mol %, and more preferably 98 mol % or more. The cis content can be measured by the method described above.

[0072] The BR may be unmodified or modified. Examples of modified BR include modified BRs into which functional groups similar to those of modified diene rubbers have been introduced. Furthermore, hydrogenated butadiene polymers (hydrogenated BRs) can also be used as the BR.

[0073] As the BR, for example, products from UBE Corporation, JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0074] The content of BR in 100% by mass of the rubber component may be 0% by mass, but when BR is contained, from the viewpoints of fuel economy and crack growth resistance, it is preferably more than 10% by mass, more preferably more than 20% by mass, even more preferably more than 30% by mass, and still more preferably more than 40% by mass. On the other hand, the upper limit of the BR content is preferably less than 70% by mass, more preferably less than 60% by mass, and still more preferably less than 50% by mass.

[0075] <Other rubber components> As the rubber component, rubbers other than those mentioned above can be used. Examples of rubbers other than those mentioned above include diene rubbers such as styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR), and non-diene rubbers such as ethylene propylene diene rubber (EPDM), butyl rubber (IIR), and halogenated butyl rubber (X-IIR). These may be used alone or in combination of two or more.

[0076] The content of the diene rubber in 100% by mass of the rubber component is preferably more than 80% by mass, more preferably more than 90% by mass, and most preferably 100% by mass.

[0077] (Rubber components synthesized from recycled and biomass-derived raw materials) Monomers, which are structural units of synthetic rubbers such as IR, SBR, and BR, may be derived from underground resources such as petroleum and natural gas, or may be recycled from rubber products such as tires or non-rubber products such as polystyrene. Monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl compounds. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds include, but are not limited to, styrene. Among these, recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) are preferably used as raw materials.

[0078] The method for producing the recycled monomer is not particularly limited, and examples thereof include synthesis from recycled naphtha obtained by decomposing rubber products such as tires. The method for producing recycled naphtha is also not particularly limited, and examples thereof include decomposing rubber products such as tires under high temperature and pressure, decomposing with microwaves, or mechanically crushing and then extracting.

[0079] Furthermore, the monomers that are the structural units of polymers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to materials derived from natural resources such as plants. Examples of biomass include, but are not limited to, agricultural, forestry, and fishery products, sugar, wood chips, plant residues after useful components have been extracted, plant-derived ethanol, and biomass naphtha.

[0080] Monomers derived from biomass (biomass monomers) are not particularly limited, and examples thereof include biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds include, but are not limited to, styrene. The method for producing biomass monomers is not particularly limited, and examples include biological and / or chemical and / or physical conversion of animals and plants. A representative example of biological conversion is fermentation by microorganisms, and examples of chemical and / or physical conversion include catalytic conversion, high heat conversion, high pressure conversion, electromagnetic wave conversion, critical fluid conversion, and combinations thereof.

[0081] Polymers synthesized from biomass monomer components (biomass polymers) are not particularly limited and include polybutadiene rubber synthesized from biomass-derived butadiene, aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compounds, etc. Examples of the aromatic vinyl / butadiene copolymers include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0082] Whether a polymer's raw material is biomass-derived can be determined by its percent modern carbon (pMC) measured in accordance with ASTM D6866-10. pMC is the modern standard reference carbon. 14 of sample against C concentration 14 This is the ratio of C concentrations and is a value used as an index of the biomass ratio of a compound. The significance of this value is explained below.

[0083] 1 mole of carbon atoms (6.02 × 10 23 ) contains approximately 6.02 × 10 atoms, which is about one trillionth of the number of ordinary carbon atoms. 11 pieces 14 C exists. 14The half-life of C is 5730 years, 14 C is decreasing regularly. Therefore, in the case of fossil fuels such as coal, oil, and natural gas, which are thought to have been absorbed and fixed by plants and other organisms more than 226,000 years ago, C was also included in these when they were first fixed. 14 All C elements have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas contain 14 Therefore, chemicals produced from these fossil fuels do not contain any C element. 14 It does not contain any C element.

[0084] on the other hand, 14 C is constantly produced by cosmic rays undergoing nuclear reactions in the atmosphere. 14 The amount of C is balanced between radioactive decay and nuclear reaction, and in the Earth's atmospheric environment, 14 Therefore, the amount of carbon derived from biomass resources currently circulating in the environment is constant. 14 As mentioned above, the C concentration is approximately 1 × 10 -12 The value is approximately mol %. Therefore, the biomass ratio in a compound can be calculated by using the difference between these values.

[0085] this 14 C is typically measured using accelerator mass spectrometry based on a tandem accelerator. 13 C concentration ( 13 C / 12 C). 14 C concentration ( 14 C / 12 C) is measured. 14 The modern standard reference for the C concentration is the carbon circulating in nature as of 1950. 14The specific standard substance used is the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific activity of carbon in this oxalic acid (per gram of carbon) is 14 The radioactivity of C is separated into carbon isotopes, 13 The standard value is the value corrected for decay from 1950 to the measurement date. 14 This is used as the C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value.

[0086] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, it will usually not reach 100 under normal conditions, so it will show a value of approximately 110 pMC. On the other hand, for chemical substances derived from petroleum and other fossil fuels, 14 When the carbon concentration is measured, it will show a value of about 0 pMC (for example, 0.3 pMC), which corresponds to the above-mentioned biomass ratio of 0%.

[0087] From the above, it is preferable in terms of environmental protection to use a material such as rubber having a high pMC value, that is, a material such as rubber having a high biomass ratio, in a rubber composition.

[0088] (filler) The rubber composition may contain a filler, and the filler preferably contains at least one of carbon black (CB) and silica. The carbon black preferably contains recovered carbon black (rCB). Alternatively, the filler may consist solely of at least one of carbon black (CB) and silica.

[0089] Carbon black Carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. The raw material for carbon black may be a biomass material such as lignin or vegetable oil, or pyrolysis oil obtained by pyrolysis of waste tires. Carbon black may be produced by combustion, such as in a furnace process, by hydrothermal carbonization (HTC), or by thermal decomposition of methane, such as in a thermal black process. Commercially available carbon black products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Columbia Carbon Co., Ltd. One type of carbon black may be used alone, or two or more types may be used in combination.

[0090] In addition to the above, from the viewpoint of life cycle assessment, carbon black may be made from a biomass material such as lignin, or recycled carbon black obtained by pyrolysis and purification of a product containing carbon black, such as a tire.

[0091] As used herein, "recycled carbon black" refers to carbon black obtained by crushing used tires or other products containing carbon black and calcining the crushed material, and refers to carbon black in which, when subjected to oxidative combustion by heating in air as measured by thermogravimetry in accordance with JIS K 6226-2:2003, the proportion of the mass of ash (ash content), which is the non-combustible component, is 13% by mass or more. In other words, the proportion of the mass (carbon content) of the recycled carbon black lost due to oxidative combustion is 87% by mass or less. Recycled carbon black is sometimes expressed as rCB.

[0092] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975, citing "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, describes the carbon black as being obtained by pyrolysis of organic materials at 550-800°C in the absence of oxygen, or by vacuum pyrolysis at relatively low temperatures (

[0027] ). Carbon black obtained from such pyrolysis processes typically lacks functional groups on its surface, as mentioned in

[0004] of Japanese Patent Publication No. 6856781 (Comparison of the Surface Morphology and Chemistry of Pyrolytic Carbon Black with Commercial Carbon Black, Powder Technology 160 (2005) pp. 190-193).

[0093] Recycled carbon black may lack functional groups on its surface, or may be treated to include functional groups on its surface. Treatment to include functional groups on the surface of recycled carbon black can be carried out by conventional methods. For example, in European Patent Application Publication No. 3,173,251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Furthermore, in Japanese Patent Publication No. 6,856,781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol or disulfide group to obtain surface-activated carbon black. The recycled carbon black of this embodiment also includes carbon blacks treated to include functional groups on their surfaces.

[0094] As the recycled carbon black, commercially available products from Strable Green Carbon, LD Carbon, etc. can be used.

[0095] The average primary particle diameter of carbon black is preferably greater than 10 nm, more preferably greater than 13 nm, and even more preferably greater than 15 nm, from the viewpoint of suppressing cracking. On the other hand, the average primary particle diameter is preferably less than 40 nm, more preferably less than 30 nm, and even more preferably less than 25 nm, from the viewpoint of obtaining reinforcing properties. The average primary particle diameter of carbon black is measured by the above-mentioned measurement method.

[0096] From the viewpoint of the effect of the present invention, the nitrogen adsorption specific surface area (N2SA) of carbon black is 250 m 2 / g is preferable, and 200m 2 / g is more preferable, and 170m 2 / g. 2 / g or more is preferable, and 100m 2 / g is more preferable, and 130m 2 The N2SA of carbon black is measured by the above-mentioned measurement method.

[0097] When carbon black is contained, the content per 100 parts by mass of the rubber component is preferably more than 30 parts by mass, more preferably more than 40 parts by mass, and even more preferably more than 50 parts by mass from the viewpoints of obtaining reinforcement and preventing deterioration due to ultraviolet rays, and the content is preferably less than 150 parts by mass, more preferably less than 120 parts by mass, and even more preferably less than 100 parts by mass from the viewpoints of obtaining flexibility and relaxing stress.

[0098] <Silica> The silica is not particularly limited, and can be, for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrated silica), or other silica commonly used in the tire industry. The raw material for silica is not particularly limited, and can be, for example, a mineral-derived raw material such as quartz, a biological raw material such as rice husk (for example, silica made from biomass materials such as rice husk), or silica recycled from a silica-containing product. Among these, hydrated silica prepared by a wet method is preferred because it contains a large number of silanol groups. Silica can be used alone or in combination of two or more types.

[0099] Silica made from biomass materials can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then reacting the silicate with sulfuric acid in the same manner as conventional wet-process silica to produce a silicon dioxide precipitate, which is then filtered, washed with water, dried, and pulverized.

[0100] Silica recycled from silica-containing products can be, for example, silica recovered from products containing silica, such as electronic components such as semiconductors, tires, desiccants, and filtering materials such as diatomaceous earth. The recovery method is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from electronic components such as semiconductors or tires is preferred.

[0101] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and duration, the crystallization of silica in rice husk ash can be suppressed (see, for example, JP 2009-2594 A, Akita Prefectural University Web Journal B / 2019, vol. 6, pp. 216-222). Amorphous silica extracted from rice husks can be commercially available from Wilmar, Inc.

[0102] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 50 m 2 / g, more preferably 80m 2 / g, more preferably 100m2 The upper limit of the N2SA of silica is not particularly limited, but is preferably 300 m 2 / g, more preferably less than 200m 2 / g, more preferably less than 150m 2 / g. By keeping it within the above range, crack propagation resistance tends to be improved. The N2SA of silica is a value measured by the above method.

[0103] From the viewpoint of reinforcing properties, fuel economy, etc., the average primary particle size of silica is preferably less than 25 nm, more preferably less than 22 nm, and even more preferably less than 20 nm. There is no particular restriction on the lower limit of the average primary particle size, but it is preferably more than 10 nm, more preferably more than 15 nm, and even more preferably more than 18 nm. The average primary particle size of silica can be determined by the above-mentioned method.

[0104] The silica content (total amount of silica) is preferably less than 70 parts by mass, more preferably less than 60 parts by mass, and even more preferably less than 55 parts by mass, per 100 parts by mass of the rubber component, while the content is preferably more than 10 parts by mass, more preferably more than 20 parts by mass, even more preferably more than 30 parts by mass, and even more preferably more than 40 parts by mass.

[0105] <Silane coupling agents> When silica is used, a silane coupling agent may be used in combination. However, in this embodiment, even when silica is used, it is preferable not to use a silane coupling agent in combination. However, a silane coupling agent may be used as long as it does not affect the effects of the present invention. The silane coupling agent is not particularly limited, but examples thereof include sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, NXT-Z100, NXT-Z45, and NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane. Examples of the silane coupling agent include amino-based silane coupling agents such as silane and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, among which sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferred. The silane coupling agents may be used alone or in combination of two or more.

[0106] When a silane coupling agent is contained, its content (when a plurality of silane coupling agents are used, the total amount) relative to 100 parts by mass of silica is preferably more than 1 part by mass, more preferably more than 3 parts by mass, and even more preferably more than 5 parts by mass, from the viewpoint of improving the dispersibility of silica.Furthermore, this content is preferably less than 20 parts by mass, more preferably less than 15 parts by mass, even more preferably less than 12 parts by mass, and even more preferably less than 9 parts by mass.

[0107] Other fillers The filler may contain fillers other than silica and carbon black. The other fillers are not particularly limited, but may include, for example, aluminum hydroxide, calcium carbonate, alumina, clay, talc, and other fillers that have been commonly used in the tire industry. The other fillers may be used alone or in combination of two or more.

[0108] <Filler content> From the viewpoint of the effects of the present invention, the content of the filler (total content of the fillers) is preferably more than 20 parts by mass, more preferably more than 30 parts by mass, and still more preferably more than 40 parts by mass per 100 parts by mass of the rubber component. The upper limit of the content is preferably less than 200 parts by mass, more preferably less than 150 parts by mass, and still more preferably less than 100 parts by mass.

[0109] (Other compounding agents) The rubber composition of the present embodiment may contain, as other compounding agents, compounding agents generally used in the tire industry, such as plasticizers, processing aids, vulcanized rubber particles, wax, stearic acid, zinc oxide, antioxidants, vulcanizing agents, and vulcanization accelerators, as appropriate.

[0110] <Plasticizer> A plasticizer is a material that imparts plasticity to rubber components and encompasses both liquid and solid plasticizers at 25°C. Examples of plasticizers include resins, oils, liquid rubbers, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, biomass-derived materials, or naphtha recycled from rubber and non-rubber products. Low-molecular-weight hydrocarbon components obtained by pyrolysis and extraction of used tires or products containing various components may also be used as plasticizers. Plasticizers may be used singly or in combination.

[0111] ·resin Of the other compounding ingredients, the rubber composition preferably contains a resin. The resin is not particularly limited, but resins commonly used in the tire industry can be used, such as aromatic vinyl resins, dicyclopentadiene resins, C9 resins, C5 resins, C5C9 resins, terpene resins, rosin resins, and phenolic resins. Of these, aromatic vinyl resins, dicyclopentadiene resins, C9 resins, and terpene resins are preferred. The resins may be used alone or in combination of two or more.

[0112] aromatic vinyl resin The term "aromatic vinyl resin" refers to a resin containing at least one aromatic vinyl compound selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc., as the monomer component with the largest content, preferably at least 50 mol %, and may be hydrogenated or modified. As the aromatic vinyl resin, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, because they are economical, easy to process, and have excellent heat generation properties. As the aromatic vinyl resin, commercially available products available from, for example, Kraton, Eastman Chemical, Mitsui Chemicals, Inc., etc., can be used. One type of resin may be used alone, or two or more types may be used in combination.

[0113] Dicyclopentadiene Resin The term "dicyclopentadiene-based resin" refers to a resin containing dicyclopentadiene (DCPD) as the monomer component with the highest content, and may be a hydrogenated or modified resin. Examples of dicyclopentadiene-based resins include DCPD / C9 resins obtained by copolymerizing dicyclopentadiene with the C9 fraction, with DCPD / C9 resins being preferred. Examples of DCPD resins that can be used include those commercially available from ExxonMobil Corporation, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., and the like. These resins may be used singly or in combination of two or more.

[0114] C9 resin The term "C9 resin" refers to a resin obtained by polymerizing a C9 fraction. It may be a C9 fraction polymerized alone or a copolymer obtained by copolymerizing a C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) with a C9 fraction is called a DCPD / C9 resin. It may also be a hydrogenated or modified version of such a resin. Examples of C9 fractions include at least one petroleum fraction having 8 to 10 carbon atoms selected from the group consisting of vinyltoluene, alkylstyrene, coumarone, indene, methylindene, dicyclopentadiene, etc. Specific examples of C9 resins include coumarone-indene resin, coumarone resin, and indene resin. These resins may be used alone or in combination.

[0115] C5 resin "C5 resin" refers to a resin obtained by polymerizing a C5 fraction other than dicyclopentadiene, and may be a hydrogenated or modified version of such a resin. Examples of C5 fractions other than dicyclopentadiene include at least one petroleum fraction having 4 to 5 carbon atoms selected from the group consisting of cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, pentadiene, etc. Such resins may be used alone or in combination of two or more.

[0116] C5C9 resin The term "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified resin. Examples of C5C9 resins that can be used include those commercially available from Tosoh Corporation, LUHUA, and the like. One type of resin may be used alone, or two or more types may be used in combination.

[0117] Terpene Resin Terpene resins refer to resins containing at least one terpene compound selected from the group consisting of α-pinene, β-pinene, limonene, dipentene, etc., as the most abundant monomer component, preferably at least 50 mol %, and may be hydrogenated or modified. Specific examples of terpene resins include polyterpene resins containing only one or more of the terpene compounds as monomer components; aromatic-modified terpene resins containing the terpene compound and an aromatic compound as monomer components; and terpene phenolic resins containing the terpene compound and a phenolic compound as monomer components. Examples of aromatic compounds that serve as monomer components for aromatic-modified terpene resins include at least one selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. Examples of phenolic compounds that serve as monomer components for terpene phenolic resins include at least one selected from the group consisting of phenol, bisphenol A, cresol, xylenol, etc. These resins may be used alone or in combination.

[0118] Rosin-based resin The rosin-based resin refers to a resin containing at least one rosin acid compound selected from the group consisting of abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc., preferably as the monomer component with the largest content, more preferably at least 50 mol %, and may be hydrogenated or modified. The rosin-based resin is not particularly limited, but examples include natural rosin resin and rosin-modified resins obtained by modifying rosin by hydrogenation, disproportionation, dimerization, esterification, etc. Such resins may be used alone or in combination of two or more.

[0119] phenolic resin The phenolic resin refers to a resin containing a phenolic compound such as phenol or cresol as the monomer component with the largest content, preferably 50 mol% or more. Examples of the phenolic resin include, but are not limited to, phenol-formaldehyde resin, alkylphenol-formaldehyde resin, alkylphenol-acetylene resin, and oil-modified phenol-formaldehyde resin. These resins may be used alone or in combination of two or more.

[0120] From the viewpoint of grip performance, the softening point of the resin is preferably above 60° C., more preferably above 70° C., and even more preferably above 80° C. Furthermore, from the viewpoint of processability and improving the dispersibility of the rubber component and the filler, the softening point is preferably 150° C. or lower, more preferably 140° C. or lower, and even more preferably 130° C. or lower. The softening point of the resin is measured by the above-mentioned measurement method.

[0121] When a resin is contained, the content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 5 parts by mass, and even more preferably more than 8 parts by mass, from the viewpoint of the effects of the invention, while the content is preferably less than 30 parts by mass, more preferably less than 25 parts by mass, and even more preferably less than 20 parts by mass, from the viewpoint of suppressing heat buildup.

[0122] ·oil Examples of oils include mineral oil, vegetable oil, and animal oil. From the viewpoint of life cycle assessment, waste oils used in rubber mixers and engines, and refined waste cooking oils used in restaurants may also be used. One type of oil may be used alone, or two or more types may be used in combination.

[0123] As used herein, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oil (mineral oil), naphthenic oil, and aromatic oil. Specific examples of mineral oil include mild extracted solvate (MES), distillate aromatic extract (DAE), treated distillate aromatic extract (TDAE), treated residual aromatic extract (TRAE), and residual aromatic extract (RAE). Furthermore, oils with a low content of polycyclic aromatic compounds (PCA) can also be used as an environmentally friendly measure. Examples of low PCA oils include MES, TDAE, and heavy naphthenic oil. Mineral oils may be used singly or in combination.

[0124] As used herein, examples of vegetable oils include linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and Japan wax. Further examples of vegetable oils include refined oils (such as salad oil) obtained by refining the above oils, interesterified oils obtained by interesterifying the above oils, hardened 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 waste edible oils recovered from edible oils and the like. Vegetable oils may be liquid or solid at 25°C. One vegetable oil may be used alone, or two or more may be used in combination.

[0125] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin is esterified with a fatty acid. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer (trimer or higher). Dimer or higher acylglycerols can be obtained by thermal polymerization, oxidative polymerization, or the like. The acylglycerol may be liquid or solid at 25°C.

[0126] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, but may be any of the following: 1 For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours, and after removing the rubber composition, the 1 When H-NMR was measured, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm when the signal of tetramethylsilane (TMS) was set at 0.00 ppm. These signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atoms of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0127] The fatty acid is not particularly limited and may be either an unsaturated fatty acid or a saturated fatty acid. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0128] Among these, it is desirable that the fatty acid contains a fatty acid with few double bonds, i.e., a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As a vegetable oil containing such a fatty acid, for example, vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or vegetable oil modified by ester exchange or the like may be used. Furthermore, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by breeding, genetic modification, or the like.

[0129] As the vegetable oil, for example, commercially available products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., Fuji Kosan Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0130] Examples of animal oils include fish oil, beef tallow, and oleyl alcohol derived from these.

[0131] When oil is contained, the content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 1.5 parts by mass, and even more preferably 2 parts by mass or more from the viewpoint of processability, and is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 10 parts by mass from the viewpoint of the effects of the invention.

[0132] Liquid rubber The liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at 25° C., and examples thereof include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), liquid farnesene rubber, etc. One type of liquid rubber may be used alone, or two or more types may be used in combination.

[0133] Ester plasticizers Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), and trixylenyl phosphate (TXP). One type of ester-based plasticizer may be used alone, or two or more types may be used in combination.

[0134] The amount of plasticizer per 100 parts by mass of the rubber component (the total amount when multiple plasticizers are used) is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, and even more preferably 12 parts by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of the effects of the invention, it is preferably less than 60 parts, more preferably less than 40 parts, and even more preferably less than 20 parts. The amount of plasticizer also includes the amount of extender plasticizers, such as extender oil, extender resin, extender liquid rubber component, and extender ester-based plasticizer, used to extend the rubber component.

[0135] <Processing aids> Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. These processing aids may be used alone or in combination of two or more. Examples of processing aids that can be used include those commercially available from Schill + Seilacher, Performance Additives, etc.

[0136] When a processing aid is contained, the content thereof per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of improving processability, and is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of abrasion resistance and breaking strength.

[0137] <Vulcanized rubber particles> The vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the standpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. The vulcanized rubber particles may be used alone or in combination of two or more types.

[0138] The vulcanized rubber particles are not particularly limited, and may be unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0139] As commercially available vulcanized rubber, for example, products from Lehigh, Muraoka Rubber Industries, Ltd., etc. can be used.

[0140] <Wax> The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used, such as mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. Waxes commercially available from, for example, Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., Ltd., etc. can be used. One type of wax may be used alone, or two or more types may be used in combination.

[0141] When wax is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and preferably 1.2 parts or more from the viewpoint of weather resistance of the rubber, and is preferably less than 10 parts by mass, more preferably less than 7.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of preventing whitening of the tire due to bloom.

[0142] <Stearic acid> When stearic acid is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and preferably 1.5 parts by mass or more from the viewpoint of processability, and is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of vulcanization rate.

[0143] <Zinc oxide> When zinc oxide is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of processability, and is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably 6.0 parts by mass or less from the viewpoint of abrasion resistance.

[0144] <Anti-aging agent> 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 (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditolyl-p-phenylenediamine. p-phenylenediamine-based antioxidants such as diphenyl ether diphenyl ether (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products that can be used include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and Flexis Co., Ltd. One type of antioxidant may be used alone, or two or more types may be used in combination.

[0145] When an antioxidant is contained, the content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 1.5 parts by mass, and even more preferably more than 2 parts by mass from the viewpoint of ozone crack resistance of the rubber, and is preferably less than 10 parts by mass, more preferably less than 7 parts by mass, and even more preferably less than 5 parts by mass from the viewpoint of abrasion resistance and wet grip performance.

[0146] <Vulcanizing agent> Sulfur is preferably used as the vulcanizing agent. Examples of sulfur that can be used include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. The vulcanizing agent may be used alone or in combination of two or more.

[0147] When sulfur is contained, the content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 1.5 parts by mass, and even more preferably more than 2 parts by mass, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, the content is preferably less than 8 parts by mass, more preferably less than 5 parts by mass, and even more preferably less than 3 parts by mass. When oil-containing sulfur is used as the vulcanizing agent, the content of the vulcanizing agent is the total content of pure sulfur contained in the oil-containing sulfur.

[0148] Known organic crosslinking agents can also be used as vulcanizing agents other than sulfur. The organic crosslinking agent is not particularly limited as long as it can form crosslinked chains other than polysulfide bonds. Examples of the organic crosslinking agent include alkylphenol-sulfur chloride condensate, sodium 1,6-hexamethylene-dithiosulfate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, and dicumyl peroxide. 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane is preferred. These organic crosslinking agents can be commercially available from Taoka Chemical Co., Ltd., Lanxess K.K., Flexis, and other companies.

[0149] <Vulcanization accelerator> The vulcanization accelerator is not particularly limited, but examples thereof include sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, guanidine vulcanization accelerators, thiuram vulcanization accelerators, thiourea vulcanization accelerators, dithiocarbamate vulcanization accelerators, aldehyde-amine vulcanization accelerators, aldehyde-ammonia vulcanization accelerators, imidazoline vulcanization accelerators, xanthate vulcanization accelerators, and caprolactam disulfide. These vulcanization accelerators may be used alone or in combination of two or more. Among them, one or more vulcanization accelerators selected from the group consisting of sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, and guanidine vulcanization accelerators are preferred, as they more suitably achieve the desired effects. The vulcanization accelerators may be used alone or in combination of two or more.

[0150] Examples of sulfenamide vulcanization accelerators include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS).

[0151] Examples of thiazole vulcanization accelerators include 2-mercaptobenzothiazole (MBT) or a salt thereof, di-2-benzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, and 2-(2,6-diethyl-4-morpholinothio)benzothiazole.

[0152] Examples of guanidine vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatechol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine.

[0153] Examples of thiuram vulcanization accelerators include tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetramethylthiuram monosulfide (TMTM), dipentamethylene thiuram disulfide, and dipentamethylene thiuram tetrasulfide.

[0154] Examples of the thiourea vulcanization accelerator include thiourea compounds such as thiacarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea and diorthotolylthiourea, N,N'-diphenylthiourea, trimethylthiourea and N,N'-diethylthiourea.

[0155] Examples of dithiocarbamate vulcanization accelerators include piperidinium pentamethylenedithiocarbamate (PPDC), zinc dimethyldithiocarbamate (ZnMDC), zinc diethyldithiocarbamate (ZnEDC), zinc dibutyldithiocarbamate (ZnBDC), zinc dibenzyldithiocarbamate (ZDBzC), zinc N-ethyl-N-phenyldithiocarbamate (ZnEPDC), zinc N-pentamethylenedithiocarbamate (ZnPDC), sodium dibutyldithiocarbamate (NaBDC), copper dimethyldithiocarbamate (CuMDC), iron dimethyldithiocarbamate (FeMDC), and tellurium diethyldithiocarbamate (TeEDC).

[0156] When a vulcanization accelerator is contained, the content (total amount when multiple vulcanization accelerators are used) per 100 parts by mass of the rubber component is preferably more than 1.5 parts by mass, more preferably more than 2 parts by mass, and even more preferably more than 2.3 parts by mass, and preferably less than 5 parts by mass, more preferably less than 4 parts by mass, and even more preferably less than 3.5 parts by mass.

[0157] In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. As a method for obtaining such various materials from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0158] 2. Rubber composition (C) constituting the clinch For the rubber composition (C), the same rubber components, fillers and other compounding ingredients as in the case of the rubber component (B) can be used, except as described below.

[0159] In the rubber composition (C), the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably more than 5% by mass, more preferably more than 10% by mass, even more preferably more than 20% by mass, and even more preferably 30% by mass or more, from the viewpoint of improving the elongation at break and crack resistance of the rubber composition. On the other hand, the upper limit of the content of the isoprene-based rubber is preferably less than 70% by mass, more preferably less than 60% by mass, and even more preferably less than 50% by mass, from the viewpoint of suppressing deterioration due to heat, etc.

[0160] In the rubber composition (C), the content of SBR in 100% by mass of the rubber component may be 0% by mass, but when SBR is contained, it is preferably more than 30% by mass, more preferably more than 40% by mass, and even more preferably more than 50% by mass. The upper limit of the SBR content is preferably less than 90% by mass, more preferably less than 80% by mass, and even more preferably less than 70% by mass.

[0161] In the rubber composition (C), the content of BR in 100% by mass of the rubber component may be 0% by mass, but when BR is contained, from the viewpoints of fuel economy and crack growth resistance, the content is preferably more than 10% by mass, more preferably more than 20% by mass, even more preferably more than 30% by mass, and still more preferably more than 40% by mass. On the other hand, the upper limit of the BR content is preferably less than 70% by mass, more preferably less than 60% by mass, and still more preferably less than 50% by mass.

[0162] <Manufacturing> The rubber composition (B) constituting the bead support layer according to the present embodiment can be produced by a known method, for example, by kneading the components of each rubber composition using a rubber kneading device such as an open roll or an internal kneader (e.g., a Banbury mixer or a kneader).

[0163] The kneading step includes, for example, a base kneading step in which compounding ingredients and additives other than the vulcanizing agent and vulcanization accelerator are kneaded, and a final kneading (F kneading) step in which the vulcanizing agent and vulcanization accelerator are added to the kneaded product obtained in the base kneading step and kneaded. Furthermore, the base kneading step can be divided into multiple steps as desired.

[0164] The kneading conditions are not particularly limited, but examples include a method in which the base kneading step involves kneading for 3 to 10 minutes at a discharge temperature of 150 to 170°C, and in the final kneading step, kneading for 1 to 5 minutes at 70 to 110°C.

[0165] The rubber composition (C) constituting the clinch according to this embodiment can be produced in the same manner as the production method for the rubber composition (B).

[0166] The tire according to the present embodiment can be manufactured by a conventional method using the rubber composition described above. Specifically, the unvulcanized rubber composition (B) manufactured as described above is extruded to conform to the shape of the bead support layer using an extruder equipped with a die having a predetermined shape. If necessary, the unvulcanized rubber composition (C) manufactured as described above is extruded to conform to the shape of the clinch using an extruder equipped with a die having a predetermined shape. The unvulcanized bead support layer thus obtained, together with the unvulcanized clinch if necessary, is laminated with other tire components on a tire building machine and molded by a conventional method to form an unvulcanized tire. A tire can be manufactured by heating and pressurizing this unvulcanized tire in a vulcanizer. The vulcanization conditions are not particularly limited, and examples include a method of vulcanizing at 150 to 200°C for 10 to 30 minutes.

[0167] <Application> In this specification, the term "tire" refers to a tire that can be used for any purpose, regardless of whether it is a pneumatic tire or a non-pneumatic tire, and can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a racing tire, a motorcycle tire, a heavy-duty tire, or a run-flat tire. Note that a passenger car tire is a tire that is intended to be mounted on a four-wheeled vehicle and has a maximum load capacity of less than 1,400 kg. [Example]

[0168] The following examples (working examples) are considered to be preferable for carrying out the present invention, but the scope of the present invention is not limited to these working examples. Tires obtained using the various chemicals shown below and according to each table were examined, and the results calculated based on the following evaluation method are shown in each table.

[0169] <Various chemicals> The chemicals used in the examples and comparative examples are summarized below.

[0170] IR rubber: Natural rubber (TSR20) SBR: Nipol 1502 (E-SBR, styrene content: 23.5% by mass, vinyl content: 18% by mole, unmodified) manufactured by ZEON Corporation CB (Carbon Black): N134 (N2SA: 148m 2 / g, average primary particle size 18nm, DBP oil absorption: 123mL / 100g, available from Cabot Japan Co., Ltd.) Resin 1: Sylvares SA85 (a copolymer of α-methylstyrene and styrene (aromatic vinyl resin), softening point: 85°C, SP value: 9.1, Tg: 43°C, available from Kraton) Resin 2: YS Resin TO-125 (aromatic modified terpene resin, softening point: 125°C) manufactured by Yasuhara Chemical Co., Ltd. Oil: Idemitsu Kosan Co., Ltd. Diana Process NH-70S (aromatic process oil) Wax: Ozoace wax manufactured by Nippon Seiro Co., Ltd. Antioxidant 1: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant 2: Nocrac RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Co., Ltd. Stearic acid: Camellia stearic acid beads manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (powdered sulfur containing 5% oil) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccelaer D (N,N'-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0171] <Production of Unvulcanized Rubber Composition (B)> According to the formulation shown in Table 1, the chemicals other than sulfur and the vulcanization accelerator are kneaded for 5 minutes using a 1.7 L closed-type Banbury mixer until the discharge temperature reaches 170°C to obtain a kneaded mixture. Next, using a two-screw open roll, sulfur and the vulcanization accelerator are added to the kneaded mixture obtained, and the mixture is kneaded for 4 minutes until the temperature reaches 105°C to obtain the unvulcanized rubber composition (B) for the bead support layer.

[0172] <Production of Unvulcanized Rubber Composition (C)> According to the formulation shown in Table 2, the chemicals other than sulfur and the vulcanization accelerator are kneaded for 5 minutes using a 1.7 L closed-type Banbury mixer until the discharge temperature reaches 170°C, to obtain a kneaded mixture. Next, using a two-screw open roll, sulfur and the vulcanization accelerator are added to the kneaded mixture, and the mixture is kneaded for 4 minutes until the temperature reaches 105°C, to obtain the unvulcanized rubber composition (C) for clinching.

[0173] <Production of test tires> The unvulcanized rubber compositions obtained above were extruded into the shapes of the bead support layer and the clinch using an extruder equipped with a predetermined die. The molded bodies thus obtained were bonded together with other tire components in a tire building machine according to Table 3 or Table 4 to form unvulcanized tires, which were then press-vulcanized at 170°C for 12 minutes to produce test tires (Tire 1: 215 / 45R16, Tire 2: 165 / 50R16). The bead filler in all test tires was composed of rubber composition (B) with B1 formulation in Table 1. In Tables 3 and 4, with regard to "the clinch covers the bead support layer," Y / N indicates that N does not cover it as in Figure 1, and Y indicates that it covers it as in Figure 2. Furthermore, the comparative tire without a bead support layer was the tire shown in Figure 3.

[0174] <70℃ tanδ> For rubber test pieces (length 20 mm x width 4 mm x thickness 1 mm) for viscoelasticity measurement cut out from the bead support layer or clinch of each test tire, the loss tangent (70°C tanδ) is measured in an extension deformation mode using an Iplexer series manufactured by GABO under the following conditions: measurement temperature: 70°C, initial strain: 10%, dynamic strain: ±1%, frequency: 10 Hz. Each test piece is cut so that the long side is the tangent direction in the tire circumferential direction and the thickness is in the tire width direction.

[0175] <Durability at high speeds> The test tire is mounted on the front wheel of a domestically produced FF vehicle (2000cc displacement) and inflated to an internal pressure of 250kPa. After that, the vehicle is overloaded and driven around a dry test course at a speed of 50km / h for 10 laps, followed by another lap at 80km / h. The speed is then gradually increased, and the speed at which the driver feels something is wrong is measured. Durability is evaluated relatively by indexing the results using the formula below, with the result of the reference example being 100. The higher the value, the better the durability. High-speed durability performance = [(measurement speed of each test tire) / (measurement speed of the reference example)] x 100

[0176] [Table 1]

[0177] [Table 2]

[0178] [Table 3]

[0179] [Table 4]

[0180] In the above table, Y indicates that the clinch covers the bead support layer, and N indicates that the clinch does not cover the bead support layer.

[0181] <Embodiment> The following describes a preferred embodiment.

[0182] [1] A tire having a pair of bead portions, The bead portion includes a bead filler extending radially outward from a bead core, and a bead support layer disposed on the outer side of the bead filler in the tire rotational axis direction, the bead support layer is composed of a rubber composition (B), A tire in which, when the outer diameter (mm) of the tire is Dt and the loss tangent of the rubber composition (B) at 70°C is 70°C tan δ(B), Dt and 70°C tan δ(B) satisfy the following formula, or the right-hand side of formula (1) is preferably 100.0, and the right-hand side of formula (2) is preferably 599, more preferably 598, even more preferably 597, even more preferably 596, even more preferably 595, even more preferably 590, even more preferably 580, even more preferably 570, and even more preferably 560. (1) 70℃ tanδ(B)×Dt≦110.0 (2) Dt≦600 [2] The tire according to the above [1], wherein the 70°C tan δ(B) satisfies the following formula, or the right-hand side of formula (3) is preferably 0.14, more preferably 0.13, even more preferably 0.12, and still more preferably 0.11. (3) 70℃ tanδ(B)≦0.15 [3] The tire according to the above [1] or [2], wherein the right side of formula (1) is 90.0, preferably 80.0, more preferably 70.0, even more preferably 60.0, and still more preferably 55.0. [4] The tire according to any one of the above [1] to [3], wherein the right side of formula (2) is 550, preferably 549, more preferably 548, even more preferably 547, even more preferably 546, even more preferably 545, and even more preferably 540. [5] The tire according to any one of the above [1] to [4], wherein the right-hand side of formula (3) is 0.10. [6] The tire according to any one of the above [1] to [5], wherein the bead support layer is covered with clinches. [7] The clinch is composed of a rubber composition (C), The tire according to any one of the above [1] to [6], wherein, when the loss tangent of the rubber composition (C) at 70°C is 70°C tan δ(C), 70°C tan δ(C) and 70°C tan δ(B) satisfy the following formula, or the right-hand side of formula (4) is preferably 0.90, more preferably 0.80: (4) 70℃tanδ(B) / 70℃tanδ(C)<1.00 [8] The tire according to the above [7], wherein the right side of formula (4) is 0.70, preferably 0.68. [9] The tire according to any one of the above items [1] to [8], which is a tire for a passenger car. [Explanation of symbols]

[0183] Dt Tire outer diameter CL Tire centerline 1 tire 2 Bead section 3 Bead Core 4 Bead filler 5 Bead support layer 6. Clinch 7. Carcass R rim

Claims

1. A tire having a pair of bead portions, The bead portion includes a bead filler extending radially outward from a bead core, and a bead support layer disposed on the outer side of the bead filler in the tire rotational axis direction, the bead support layer is composed of a rubber composition (B), A tire in which Dt and 70°C tan δ(B) satisfy the following formula, where Dt is the outer diameter (mm) of the tire and 70°C tan δ(B) is the loss tangent of the rubber composition (B) at 70°C. (1) 70°C tan δ(B)×Dt≦110.0 (2) Dt≦600

2. The tire according to claim 1, wherein the 70°C tan δ(B) satisfies the following formula: (3) 70°C tan δ(B)≦0.15

3. The tire according to claim 1 or 2, wherein the right side of formula (1) is 90.

0.

4. The tire according to claim 1 or 2, wherein the right side of formula (2) is 550.

5. The tire according to claim 2, wherein the right side of formula (3) is 0.

10.

6. 3. The tire of claim 1, wherein the bead support layer is covered with clinches.

7. The clinch is made of a rubber composition (C), The tire according to claim 1 or 2, wherein when the loss tangent of the rubber composition (C) at 70°C is 70°C tanδ(C), 70°C tanδ(C) and 70°C tanδ(B) satisfy the following formula: (4) 70°C tan δ(B) / 70°C tan δ(C)<1.00

8. The tire according to claim 7, wherein the right side of formula (4) is 0.

70.

9. 3. The tire of claim 1 or 2, which is a passenger vehicle tire.

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