tire

Abstract

Provide a tire with excellent low fuel consumption performance. 【Solution means】A tire provided with breaker topping rubber, wherein the rubber composition constituting the breaker topping rubber contains a bismaleimide compound, the weight (kg) of the tire is G, and the maximum load capacity (kg) is W EB , BRK , EB , , the thickness (mm) of the breaker topping rubber is D BRK , the ratio (%) of the elongation at break after heat deterioration by leaving the rubber composition in an environment at 80 ° C for 7 days to the elongation at break before the heat deterioration is R EB When it is set as L G / W BRK is 0.0250 or less, D EB and R satisfy the following formula. EB / D BRK > 40.0

Description

[Technical Field]

[0001] This invention relates to tires. [Background technology]

[0002] In recent years, there has been a growing demand for improved fuel efficiency in automobiles, and tires, which are components of automobiles, are also required to have improved fuel efficiency by reducing rolling resistance. Patent Document 1 describes how to improve fuel efficiency by using a predetermined thermoplastic elastomer. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2024-14499 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, in response to environmental issues, further improvements in fuel efficiency are required.

[0005] The present invention aims to provide a tire with excellent fuel efficiency. [Means for solving the problem]

[0006] This invention relates to the following tires. It is a tire equipped with breaker topping rubber. The rubber composition constituting the aforementioned breaker topping rubber contains a bismaleimide compound. Let G be the weight (kg) of the aforementioned tire, and W be its maximum load capacity (kg). L The thickness (mm) of the breaker topping rubber is D BRK The ratio (%) of the elongation at break of the rubber composition after being left to thermally degrade at 80°C for 7 days to the elongation at break before thermal degradation is R EB In that case, G / WL is 0.0250 or less, and D BRK and R EB is a tire that satisfies the following formula. (1) R EB / D BRK > 40.0

Advantages of the Invention

[0007] <00002​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​While not intended to be constrained by theory, the following mechanisms are considered to improve the fuel efficiency of tires in this invention. Specifically, (a) tires with a relatively small G / WL value are tires with a small weight relative to their maximum load capacity, and are therefore considered to contribute to improved fuel efficiency. Also, (b) bismaleimide compounds act as crosslinking agents in rubber compositions, increasing the rigidity of the rubber, and their crosslinking chains are less likely to crack due to heat, resulting in less change in elongation at break due to thermal degradation. For this reason, tires in which the breaker topping rubber, composed of a rubber composition containing bismaleimide compounds, satisfies formula (1) are resistant to thermal degradation, and the thickness of the breaker topping rubber can be reduced, thus contributing to improved fuel efficiency. And it is thought that the cooperation of (a) and (b) above dramatically improves the fuel efficiency of tires.

[0011] The aforementioned G / W L It is preferably 0.0210 or less, more preferably 0.0170 or less, even more preferably 0.0150 or less, even more preferably 0.0130 or less, and even more preferably 0.0128 or less.

[0012] Golden Week L This is because tires with a smaller value and a lighter weight relative to their maximum load capacity contribute to improved fuel efficiency.

[0013] The rubber composition preferably contains recycled carbon black.

[0014] Since recycled carbon black does not significantly restrict the polymer chains of rubber, the reaction between the bismaleimide compound and the polymer proceeds more easily, which is thought to contribute to the manifestation of the effects of the present invention.

[0015] The rubber composition preferably contains a thermosetting resin.

[0016] This is because it allows the rubber's hardness to be maintained.

[0017] G, W L , DBRK and R EB It is preferable that the following equation is satisfied. (2) R EB / (D BRK ×(G / W L ))>2700

[0018] Further collaboration between (a) and (b) above is expected to improve fuel efficiency.

[0019] The rubber composition has an elongation at break before thermal degradation of EB BF If that is the case, EB BF , D BRK and R EB It is preferable that the following equation is satisfied. (3) R EB / D BRK ×EB BF >14000

[0020] In addition to the collaboration between (a) and (b) above, the large elongation at fracture before thermal degradation is considered to contribute to the realization of the invention's effects.

[0021] The cobalt element content in the rubber composition is preferably 0.0010 parts by mass or less per 100 parts by mass of the rubber component.

[0022] This is because it allows for a reduction in the amount of cobalt used.

[0023] D BRK It is preferable that it be less than 1.5 mm.

[0024] This is because the thinner the breaker topping rubber, the better the fuel efficiency.

[0025] <Definition> "Standard condition" refers to a state of no load where the tire is mounted on a standard rim and filled with air at the standard internal pressure. Unless otherwise specified, tires in the standard condition should be used.

[0026] Unless otherwise specified, the "dimensions of each part of the tire" refer to values ​​that are determined in the normal state for those visible on the outer surface of the tire, while those located inside the tire or on the cut surface of the tire refer to values ​​that are determined, for example, by cutting the tire in a plane including the tire's axis of rotation and holding the cut tire piece within the rim width of the normal rim.

[0027] A "standard rim" refers to the rim specified for each tire within the standards system that the tire is based on. 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 Organisation), 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." Refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. In the case of a tire not specified in the above standards, it refers to the narrowest rim width among the smallest diameter rims that can be mounted on that tire and that can maintain internal pressure (i.e., do not cause air leakage between the rim and tire).

[0028] "Regular internal pressure" refers to the air pressure specified for each tire in the standards system, including the standard on which the tire is based. For example, for JATMA it refers to "maximum air pressure," for ETRTO it refers to "INFLATION PRESSURE," and for TRA it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims, refer to JATMA, ETRTO, and TRA in that order, and if there is an applicable size at the time of reference, follow that standard. In the case of tires not specified in the above standards, it refers to the regular internal pressure (but at least 250kPa) of another tire size (but specified in the standard) that is listed with the aforementioned regular rim as the standard rim. If multiple regular internal pressures of 250kPa or higher are listed, refer to the lowest value among them.

[0029] "Regular load (kg)" refers to the load specified for each tire in the standard system that the tire is based on. 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 regular rims and regular in-tire pressure, refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. For tires not specified in the above standards, the maximum load capacity (kg) is calculated separately. L This is considered the normal load.

[0030] "Maximum load capacity W L The weight (kg) is calculated using the following formula: "V" is the virtual volume of the tire (mm²). 3), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the height of the tire's cross-section in the radial direction in a plane containing the tire's axis of rotation (mm), and "Wt" is the width of the tire's cross-section in the normal state (mm). Ht can be calculated by (Dt-R) / 2, where R is the rim diameter of the tire. Wt is the value obtained by removing any patterns or letters on the tire's sidewall. Note that the maximum load capacity is synonymous with the normal load mentioned above.

[0031]

number

[0032] "Tire weight G" refers to the weight (kg) of the tire alone, excluding the weight of the rim. However, if the tire's internal cavity contains components such as sponge, sealant, or sensor components, the weight includes these components.

[0033] "Recycled carbon black" refers to carbon black obtained by crushing used tires and other products containing carbon black, and then calcining the crushed material. According to the thermogravimetric method compliant with JIS K 6226-2:2003, when oxidative combustion occurs in air, the proportion of ash (non-combustible components) is 13% by mass or more. In other words, the proportion of carbon loss due to oxidative combustion in recycled carbon black is 87% by mass or less. Recycled carbon black is sometimes denoted as rCB.

[0034] "Breaker topping rubber thickness D" BRK"Breaker topping rubber thickness" refers to the thickness (mm) of the breaker topping rubber measured along the tire centerline CL in a cross-section of the tire along a plane containing the tire rotation axis. This thickness is measured with the tire, cut along a plane containing the tire rotation axis, held at the normal rim width. This thickness is the average of the thicknesses obtained at five locations by rotating the tire circumferentially by 72° increments. If the breaker consists of one breaker ply, the thickness of that breaker ply is the thickness of the breaker topping rubber; if the breaker consists of multiple breaker plies, the total thickness of those multiple breaker plies is the thickness of the breaker topping rubber. For example, in Figure 1, breaker 2 consists of two plies, the first breaker ply 2a and the second breaker ply 2b, and the thickness of the breaker topping rubber D BRK This is shown as the total thickness of the breaker, which consists of these two breaker plies.

[0035] <Measurement method> "Elongation at break (EB) of rubber composition" is the elongation at break (%) obtained by preparing a 1 mm thick, No. 7 dumbbell-shaped test specimen and conducting a tensile test in accordance with JIS K 6251:2017 at a 23°C atmosphere and a tensile speed of 3.3 mm / second. The measurement sample is prepared by taking a sample measuring 20 mm in length, 4 mm in width, and 1 mm in thickness from the rubber layer, with the tire circumference being the longer side and the tire diameter being the thickness. If it is difficult to take a measurement sample with a thickness of 1 mm, it is acceptable to take a sample as close to 1 mm as possible. This is because the elongation at break is measured as a standardized value, and therefore is not affected by thickness.

[0036] The elongation at break of the rubber composition after thermal degradation shall be measured by taking a sample after thermally degrading the tire in an oven at 80°C for 7 days.

[0037] Elongation at break of rubber composition after thermal degradation (EB) AF (%) Elongation at break before thermal degradation EB BF Ratio to (%) EB The percentage (%) is calculated using the following formula. REB =EB AF / EB BF ×100

[0038] "Styrene content" can be determined by pyrolysis gas chromatography or NMR measurement. 1 H-NMR and 13 It is calculated by 13C-NMR. Unlike physical properties such as the complex modulus (E*), the amounts of components such as "styrene content" have true values ​​that do not depend on the measurement method, so it is preferable to use a measurement method that is as accurate as possible. In this specification, "pyrolysis gas chromatography" refers to a method in which a sample is heated by a pyrolysis apparatus, the individual components contained in the gas phase components produced by this heating are separated by a separation column, and each isolated component is analyzed.

[0039] "Vinyl content (amount of 1,2-bonded butadiene units)" can be determined by pyrolysis gas chromatography or NMR measurement. 1 H-NMR and 13 It is calculated using 1C-NMR. Similar to "styrene content," a true value exists for "vinyl content" that is independent of the measurement method, so it is preferable to use the most accurate measurement method possible.

[0040] "Cis content (amount of cis-1,4-bonded butadiene units)" is determined by infrared absorption spectroscopy or NMR measurement in accordance with JIS K 6239-2:2017. 1 H-NMR and 13 This value is measured by 13C-NMR and is applied, for example, to rubber components having repeating units derived from butadiene, such as BR. Similar to "styrene content," a true value exists for "cis content" that is independent of the measurement method, so it is preferable to use the most accurate measurement method possible.

[0041] The "weight-average molecular weight (Mw)" can be determined by converting the measured value using gel permeation chromatography (GPC) (for example, the GPC-8000 series from Tosoh Corporation, with a differential refractometer as the detector and TSKgel SuperMultipore HZ-M column from Tosoh Corporation) to a standard polystyrene equivalent. This method is applicable, for example, to SBR, BR, plasticizers, etc.

[0042] The nitrogen adsorption specific surface area (N2SA) of carbon black is measured in accordance with JIS K 6217-2:2017.

[0043] The nitrogen adsorption specific surface area (N2SA) of silica is measured by the BET method in accordance with ASTM D3037-93.

[0044] The "average primary particle diameter" is a value obtained by photographing particles with a transmission or scanning electron microscope and calculating the arithmetic mean of the particle diameters of 400 particles. If the particle is spherical, the diameter of the sphere is used as the particle diameter; if it is not spherical, the equivalent diameter of a circle (the positive square root of {4 × (particle area) / π}) is calculated from the microscope image and used as the particle diameter.

[0045] A "plasticizer" is a material that imparts plasticity to rubber components and is extracted from rubber compositions using acetone. Plasticizers include both liquid or liquid plasticizers at 25°C and solid plasticizers at 25°C. However, waxes and stearic acid commonly used in the tire industry are excluded.

[0046] "Plasticizer content" includes the amount of plasticizer in the rubber component that has been stretched by the plasticizer.

[0047] The "softening point of resin components, etc." is, unless otherwise specified, the temperature at which the softening point specified in JIS K 6220-1:2015 is measured using a ring-type softening point measuring device. If the softening point is measured by another method, this will be noted.

[0048] <Tires> The tire of the present invention will be described below, with reference to the drawings as appropriate. However, the drawings are for illustrative purposes only.

[0049] Figure 1 is a schematic diagram showing a portion of the cross-section (upper right portion of the cross-section) of a tire according to one embodiment of the present invention, along the tire meridian. In Figure 1, the tire 1 is equipped with a breaker 2 on the radially inward side of the tread portion. In the tire 1, the breaker 2 is composed of breaker plies 2a and 2b, but the breaker may be composed of one breaker ply or three or more breaker plies.

[0050] In Figure 1, the thickness D of the breaker topping rubber. BRK This is expressed as the total thickness of the two breaker plies 2a and 2b. When the breaker is made up of one breaker ply, D BRK This is the thickness of one breaker ply, and if the breaker is composed of three or more breaker plies, D BRK This is the total thickness of the three or more breaker plies.

[0051] (D BRK ) D BRK This value can vary depending on the tire size, but is generally preferable to be in the range of 1.0 mm to 2.0 mm. For example, the relatively large tires used in Table 1 below are in the range of 1.4 mm to 1.9 mm, while the relatively small tires used in Table 2 below are in the range of 1.1 mm to 1.6 mm. However, D BRK A thinner material is lighter and therefore preferable from the viewpoint of fuel efficiency. Therefore, in this embodiment, D BRK The diameter is preferably less than 1.5 mm, more preferably 1.4 mm or less, even more preferably less than 1.3 mm, even more preferably less than 1.2 mm, and even more preferably 1.1 mm or less.

[0052] (R EB ) Regarding breaker topping rubber, the elongation at break after thermal degradation is EB AF Elongation at break before thermal degradation EB BF Ratio (%) EB Preferably, it is more than 50%, more preferably more than 55%, even more preferably 55% or more, even more preferably 58% or more, even more preferably 59% or more, even more preferably more than 60%, even more preferably 62% or more, and even more preferably 65% ​​or more.

[0053] EB BF This can be increased, for example, by increasing the amount of plasticizer or decreasing the crosslink density, and conversely, it can be decreased by decreasing the amount of plasticizer or increasing the crosslink density, so a person skilled in the art can adjust it as appropriate.

[0054] R EB This can be increased, for example, by increasing the amount of bismaleimide compound, and conversely, it can be decreased by decreasing the amount of bismaleimide compound, so those skilled in the art can adjust it as appropriate.

[0055] (G / W L ) Golden Week L The ratio is 0.0250 or less. Such tires are lightweight tires in which the tire weight is relatively light relative to the tire's maximum load capacity. In this embodiment, G / W L The value is preferably 0.0240 or less, more preferably 0.0230 or less, even more preferably 0.0220 or less, even more preferably 0.0210 or less, even more preferably 0.0200 or less, even more preferably 0.0190 or less, even more preferably 0.0180 or less, even more preferably 0.0170 or less, even more preferably 0.0160 or less, even more preferably 0.0150 or less, even more preferably 0.0140 or less, even more preferably 0.0130 or less, and even more preferably 0.0128 or less.

[0056] Golden Week LThis can be adjusted by changing the tire weight and tire size.

[0057] (Formula (1)) In the tire of this embodiment, D BRK and R EB The following equation is satisfied. (1) R EB / D BRK >40.0

[0058] Here, the right-hand side of equation (1) is preferably 45.0, more preferably 50.0, and even more preferably 55.0. On the other hand, there is no particular upper limit on the value of the left-hand side of equation (1), but it is usually around 100, or it may be around 80 or 70.

[0059] (Formula (2)) In the tire of this embodiment, G, W L , D BRK and R EB The following equation is satisfied. (2) R EB / (D BRK ×(G / W L ))>2700

[0060] Here, the right-hand side of equation (2) is preferably 3000, more preferably 3500, even more preferably 4000, and even more preferably 4300. On the other hand, there is no particular upper limit on the value of the left-hand side of equation (2), but it is usually around 6000, or it may be around 5000.

[0061] (Formula (3)) In the tire of this embodiment, EB BF , D BRK and R EB The following equation is satisfied. (3) R EB / D BRK ×EB BF >14000

[0062] Here, the right-hand side of equation (3) is preferably 15,000, more preferably 16,000, even more preferably 17,000, even more preferably 18,000, and even more preferably 19,000. On the other hand, there is no particular upper limit on the value of the left-hand side of equation (3), but it is usually around 25,000, or it may be around 23,000.

[0063] <Rubber composition constituting the breaker topping rubber> The rubber composition that makes up the breaker topping rubber will be described below.

[0064] (Rubber component) The rubber component preferably includes isoprene-based rubber (IR-based rubber). In this case, the rubber component may also include rubber components other than IR-based rubber. Alternatively, the rubber component may consist solely of IR-based rubber.

[0065] Other than IR-based rubbers, any rubber components commonly used in the tire industry can be suitably used. Specifically, examples include diene-based rubbers such as isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR), as well as non-diene rubbers such as butyl rubber, ethylene-propylene rubber, polynorbornene rubber, silicone rubber, polyethylene chloride rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. Diene-based rubbers and non-diene rubbers may be used individually or in combination of two or more. In addition to the above rubber components, known thermoplastic elastomers may or may not be included.

[0066] ≪IR-type rubber≫ Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. For NR, examples include SIR20, RSS#3, TSR20, etc., which are commonly used in the tire industry. For IR, there are no particular limitations; examples include IR2200, etc., which are commonly used in the tire industry. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity 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. Isoprene-based rubbers may be used individually or in combination of two or more types.

[0067] ≪BR≫ There are no particular limitations on the type of butadiene rubber (BR), and examples include BR with high cis content, BR containing 1,2-syndiotactic polybutadiene crystals (SPB-containing BR), butadiene rubber synthesized using rare earth element catalysts (rare earth BR), tin-modified butadiene rubber modified with tin compounds (tin-modified BR), and other modified butadiene rubbers (modified BR), which are common in the tire industry. Commercially available BR products include those from UBE Corporation, JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation. Modified BRs can be any BRs having functional groups that interact with fillers such as silica. Examples include terminally modified BRs (terminally modified BRs having the functional group at the end) in which at least one end of the BR is modified with a compound having the functional group (modifying agent), main-chain modified BRs having the functional group in the main chain, main-chain terminally modified BRs having the functional group in both the main chain and the end (for example, main-chain terminally modified BRs having the functional group in the main chain and at least one end modified with the modifying agent), and terminally modified BRs that are modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule, and in which hydroxyl groups or epoxy groups are introduced. Examples of the above functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, and the like. These functional groups may have substituents. Among these, amino groups (preferably amino groups in which the hydrogen atoms of the amino group are substituted with C1-C6 alkyl groups), alkoxy groups (preferably alkoxy groups having C1-C6), and alkoxysilyl groups (preferably alkoxysilyl groups having C1-C6) are preferred.

[0068] The cis content of BR is preferably greater than 90 mol%, more preferably greater than 93 mol%, even more preferably greater than 95 mol%, and even more preferably 97 mol% or more. The cis content of BR can be measured by infrared absorption spectroscopy.

[0069] For example, BRs from companies such as UBE Corporation, JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used. BRs may be used individually or in combination of two or more types.

[0070] ≪SBR≫ Styrene-butadiene rubber (SBR) is not particularly limited and can include, for example, unmodified emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR), as well as modified SBRs such as modified emulsion-polymerized styrene-butadiene rubber (modified E-SBR) and modified solution-polymerized styrene-butadiene rubber (modified S-SBR). Modified SBRs include modified SBRs in which the terminals and / or main chain are modified, and modified SBRs coupled with tin, silicon compounds, etc. (such as those having condensates or branched structures). Furthermore, SBRs can be of the oil-expandable type, in which flexibility is adjusted by adding an expanding oil, or of the non-oil-expandable type, in which no expanding oil is added, and both types can be used. Examples of such SBRs can be those manufactured by JSR Corporation, Asahi Kasei Chemicals Corporation, Nippon Zeon Co., Ltd., and ZS Elastomer Co., Ltd. SBRs can be used individually or in combination of two or more types.

[0071] From the viewpoint of rubber strength and grip performance, the styrene content of SBR is preferably more than 15.0% by mass, more preferably more than 20.0% by mass, and even more preferably more than 23.0% by mass. Furthermore, from the viewpoint of low fuel consumption, the styrene content is preferably less than 40.0% by mass, more preferably less than 30.0% by mass, and even more preferably less than 25.0% by mass. Note that the styrene content of SBR is 1 This value is calculated by 1H-NMR measurement.

[0072] The vinyl content (amount of 1,2-bonded butadiene units) of SBR is preferably greater than 10.0 mol%, more preferably greater than 15.0 mol%, and even more preferably 18.0 mol% or higher, from the viewpoint of rubber strength and grip performance. Furthermore, from the viewpoint of low fuel consumption, the vinyl content is preferably less than 80.0 mol%, more preferably less than 50.0 mol%, and even more preferably less than 30.0 mol%. The vinyl content of SBR is measured by infrared absorption spectroscopy.

[0073] ≪Content≫ The content of IR-type rubber in 100% by mass of the rubber component is preferably more than 80% by mass, more preferably more than 90% by mass, and even more preferably more than 95% by mass, and may be 100% by mass.

[0074] The BR content in 100% by mass of the rubber component is preferably less than 20% by mass, more preferably less than 10% by mass, and even more preferably less than 5% by mass. There is no particular limit to the lower limit of this content; it may be 0% by mass, but for example, it may be 1% by mass.

[0075] The SBR content in 100% by mass of the rubber component is preferably less than 20% by mass, more preferably less than 10% by mass, and even more preferably less than 5% by mass. There is no particular limit to the lower limit of this content; it may be 0% by mass, but for example, it may be 1% by mass.

[0076] (Rubber components synthesized from recycled and biomass-derived raw materials) Monomers, which are the constituent units of synthetic rubbers such as IR, SBR, and BR, may be derived from underground resources such as petroleum and natural gas, or they may be recycled from rubber products such as tires or non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, but include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl compounds. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds are not particularly limited, but include styrene. In particular, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0077] The method for producing recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Furthermore, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and pressure, decomposed by microwaves, or extracted after mechanical grinding.

[0078] Furthermore, the monomers that make up polymers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural, forestry, and fishery products, sugars, wood chips, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha.

[0079] The biomass-derived monomer (biomass monomer) is not particularly limited and includes biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. Examples of the aromatic vinyl compound are not particularly limited but include styrene. Furthermore, the method for producing the biomass monomer is not particularly limited and includes, for example, biological and / or chemical and / or physical transformations of plants and animals. Typical biological transformations include fermentation by microorganisms, while chemical and / or physical transformations include those by catalysts, high heat, high pressure, electromagnetic waves, critical liquids, and combinations thereof.

[0080] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compounds. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0081] Whether the raw materials for a polymer are biomass-derived can be determined by measuring pMC (percent Modern Carbon) according to ASTM D6866-10. pMC refers to the percentage of modern standard reference carbon. 14 Sample relative to C concentration 14 This is a ratio of C concentrations and is used as an indicator of the biomass ratio of a compound. The significance of this value is described below.

[0082] 1 mole of carbon atoms (6.02 × 10⁻¹⁰) 23 (Each) contains approximately 6.02 × 10¹⁶ atoms, which is about one trillionth of the amount of carbon atoms in a normal atom. 11 individual 14 C exists. 14The half-life of C is 5730 years, 14 C decreases regularly. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been formed more than 226,000 years after carbon dioxide in the atmosphere was taken up and fixed by plants, etc., at the beginning of fixation, 14 all of the C element had decayed. Therefore, in the 21st century, present-day fossil fuels such as coal, oil, and natural gas 14 contain no C element at all. Therefore, chemical substances produced from these fossil fuels 14 also contain no C element at all.

[0083] On the other hand, 14 C is constantly generated by cosmic rays undergoing nuclear reactions in the atmosphere. Therefore, 14 C is in equilibrium between decreasing due to radioactive decay and being generated by nuclear reactions, and in the Earth's atmospheric environment, 14 the amount of C is constant. Therefore, in the current environment, for substances derived from biomass resources that are involved in the material cycle, 14 the C concentration is about 1×10 -12 mol% with respect to the total number of C atoms, as described above. Therefore, by utilizing the difference between these values, the biomass ratio in a certain compound can be calculated.

[0084] 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 a modern standard reference for the concentration of C, the 14The C concentration will be used. The specific standard material will be the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific radioactivity of carbon in this oxalic acid (per gram of carbon) will be used. 14 The radioactivity intensity of C is separated by carbon isotope, 13 The standard value is obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date. 14 This value is used as the C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0085] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal conditions it will often not reach 100, and will show a value of approximately 110 pMC. On the other hand, regarding chemical substances derived from fossil fuels such as petroleum, 14 When the C concentration is measured, it will show a value of approximately 0 pMC (for example, 0.3 pMC). This value corresponds to the aforementioned biomass ratio of 0%.

[0086] For the reasons stated above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in rubber compositions is preferable from an environmental protection standpoint.

[0087] (Filler) The filler preferably contains carbon black. Furthermore, the carbon black preferably contains recycled carbon black (rCB). The filler may also contain fillers other than carbon black. Such fillers include silica, aluminum hydroxide, calcium carbonate, alumina, clay, talc, and other fillers commonly used in the tire industry. Silica is preferred as a filler other than carbon black. The filler can be used individually or in combination of two or more types.

[0088] Carbon Black The carbon black is not particularly limited, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Of these, N220 and N330 are preferred. The raw material for the carbon black may be biomass material such as lignin or vegetable oil, or it may be pyrolysis oil obtained by thermal decomposition of waste tires. The method for producing the carbon black may be combustion such as the furnace method, hydrothermal carbonization (HTC), or thermal decomposition of methane such as the thermal black method. Commercial products that can be used 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 Corporation. The carbon black may be used alone or in combination of two or more types.

[0089] In addition to the above, from the perspective of life cycle assessment, carbon black made from biomass materials such as lignin, or recycled carbon black refined by thermal decomposition of carbon black-containing products such as tires, may also be used as carbon black.

[0090] In this specification, "recycled carbon black" refers to carbon black obtained by crushing used tires and other products containing carbon black, and calcining the crushed material, wherein, according to the thermogravimetric method compliant with JIS K 6226-2:2003, when oxidative combustion occurs by heating in air, the proportion of the mass of ash (ash content), which is the component that does not burn, is 13% by mass or more. In other words, the proportion of the mass (carbon content) lost due to the aforementioned oxidative combustion of recycled carbon black is 87% by mass or less. Recycled carbon black may also be represented as rCB.

[0091] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975, which refers to "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, states that it can be obtained by the 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 usually lacks functional groups on its surface, as referred to in

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

[0092] Recycled carbon black may lack functional groups on its surface, or it 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. 3173251, 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. In addition, in Japanese Patent Publication No. 6856781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes carbon black treated to include functional groups on its surface.

[0093] Recycled carbon black can be purchased from companies such as Strable Green Carbon and LD Carbon.

[0094] The nitrogen adsorption specific surface area (N2SA) of carbon black is 50m² from the perspective of reinforcing properties. 2 Preferably more than / g, 60m2 More preferably than / g, 70m 2 A value greater than / g is even more preferable. Also, from the viewpoint of heat generation and processability, 140m 2 Less than / g is preferable, 130m 2 Less than / g is more preferable, 120m 2 A value of less than / g is even more preferable. The N2SA of carbon black is measured by the measurement method described above.

[0095] From the viewpoint of reinforcing properties, the average primary particle diameter of carbon black is preferably greater than 16 nm, more preferably greater than 18 nm, and even more preferably greater than 20 nm. Furthermore, from the viewpoint of heat generation and processability, the average primary particle diameter is preferably less than 40 nm, more preferably less than 35 nm, and even more preferably less than 32 nm. The average primary particle diameter of carbon black is measured by the measurement method described above.

[0096] The carbon black content per 100 parts by mass of 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. On the other hand, the content is preferably less than 150 parts by mass, more preferably less than 110 parts by mass, and even more preferably less than 80 parts by mass. When the carbon black content is within the above range, sufficient reinforcing properties, good dispersion in the rubber, sufficient rubber strength, and crack growth resistance tend to be obtained.

[0097] From the viewpoint of reinforcing properties, the content of recycled carbon black in the total carbon black content is preferably less than 60% by mass, more preferably less than 50% by mass, even more preferably less than 45% by mass, even more preferably less than 35% by mass, and even more preferably less than 25% by mass. Furthermore, this content may be even lower, less than 20% by mass, less than 10% by mass, or even 0% by mass. On the other hand, from the viewpoint of the effects of the present invention, this content is preferably more than 1% by mass, more preferably more than 10% by mass, even more preferably more than 20% by mass, even more preferably more than 30% by mass, and even more preferably more than 40% by mass.

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

[0099] Silica derived from biomass materials can be obtained, for example, by extracting silicates from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then using these silicates to react with sulfuric acid in the same way as conventional wet silica, the precipitate of silicon dioxide is filtered, washed with water, dried, and pulverized.

[0100] The silica recycled from silica-containing products can be, for example, silica recovered from products containing silica such as semiconductors and other electronic components, tires, desiccants, and diatomaceous earth and other filter materials. The recovery method is not particularly limited and can include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from semiconductors and other electronic components 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 combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol.6, pp.216-222, etc.). Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0102] The nitrogen adsorption specific surface area (N2SA) of silica is 150 m² from the perspective of reinforcing properties. 2 Preferably more than / g, 160m2 More preferably than / g, 170m 2 A value exceeding / g is even more preferable. Also, from the viewpoint of heat generation and processability, 250m 2 Less than / g is preferable, 230m 2 Less than / g is more preferable, 210m 2 A value of less than / g is even more preferable. The N2SA of silica is measured by the measurement method described above.

[0103] From the viewpoint of reinforcing properties, the average primary particle diameter of silica is preferably greater than 14 nm, more preferably greater than 15 nm, and even more preferably greater than 16 nm. Furthermore, from the viewpoint of heat generation and processability, the average primary particle diameter is preferably less than 22 nm, more preferably less than 20 nm, and even more preferably less than 18 nm. The average primary particle diameter of silica is measured by the measurement method described above.

[0104] When silica is included, the amount of silica per 100 parts by mass of rubber component is not particularly limited, but from the viewpoint of ensuring low fuel consumption, wet grip performance, and sufficient reinforcement, it is preferably more than 1 part by mass, more preferably more than 5 parts by mass, more preferably 10 parts by mass or more, and even more preferably more than 20 parts by mass. Furthermore, from the viewpoint of silica dispersibility, processability, and wet grip performance, the amount of silica is preferably less than 150 parts by mass, more preferably less than 100 parts by mass, even more preferably less than 50 parts by mass, and even more preferably less than 30 parts by mass.

[0105] ≪Silane coupling agents≫ Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited, but examples 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, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; and 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane. Examples of silane coupling agents include amino-based silane coupling agents such as 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 these, it is preferable to contain a sulfide-based silane coupling agent and / or a mercapto-based silane coupling agent. As silane coupling agents, for example, those commercially available from Evonik Industries, Momentive, etc., can be used. Silane coupling agents may be used alone or in combination of two or more.

[0106] When a silane coupling agent is included, the content of the silane coupling agent is preferably more than 1 part by mass, more preferably more than 3 parts by mass, even more preferably more than 5 parts by mass, and even more preferably more than 7 parts by mass, per 100 parts by mass of silica. On the other hand, the content is preferably less than 20 parts by mass, more preferably less than 18 parts by mass, even more preferably less than 16 parts by mass, and even more preferably less than 14 parts by mass. Keeping it within the above range tends to improve cut resistance.

[0107] (Bismaleimide compound) This rubber composition contains a bismaleimide compound. The bismaleimide compound performs the same function as the vulcanizing agent described below. In addition to the bismaleimide compound, the vulcanizing agent described below may be added to this rubber composition.

[0108] As the bismaleimide compound, one or more compounds selected from the group consisting of compounds represented by the following chemical formulas can be used.

[0109] [ka] (Here, X represents an alkylene group, a phenylene group, or a divalent hydrocarbon group with 6 to 29 carbon atoms having 1 to 4 aromatic rings, and R 4 ~R 7 Each of these independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a -NH2 group or -NO2 group.

[0110] In the above chemical formula, examples of alkylene groups having 2 to 6 carbon atoms, which are X, include ethylene, propane-1,3-diyl, propane-2,2-diyl, tetramethylene, pentamethylene, and hexamethylene. Examples of divalent hydrocarbon groups having 6 to 29 carbon atoms and 1 to 4 aromatic rings include methylenebis(phenylene) group, phenylenebis(methylene) group, and phenoxyphenyl group. These aromatic rings may also be bonded by -O-, -S-, -SS-, -SO2-, etc. Among the above X, hydrocarbon groups having 8 to 17 carbon atoms and 1 or 2 phenylene or aromatic rings are preferred, and hydrocarbon groups having 8 to 13 carbon atoms and 1 or 2 phenylene or aromatic rings are more preferred. In the above chemical formula, X may have substituents. Examples of these substituents include alkyl groups having 1 to 3 carbon atoms, -NH2, -NO2, -F, -Cl, -Br, etc. Also, in the above chemical formula, R 4 ~R 7 Examples of alkyl groups having 1 to 5 carbon atoms, as shown, include methyl, ethyl, and propyl groups.

[0111] Suitable examples of bismaleimide compounds include, for example, N,N'-1,2-ethylenebismaleimide, N,N'-1,2-propylenebismaleimide, 4,4'-bismaleimidediphenylmethane, N,N'-m-phenylenebismaleimide, N,N'-(4,4-diphenyl-methane)bismaleimide, bis(3-ethyl-5-methyl-4-maleimoidphenyl)methane, 2,2'-bis[4-(4-maleimoidphenoxy)phenyl]propane, m-phenylenebis(methylene)bismaleimide, m-phenylenebis(methylene)biscitraconimide, and 1,1'-(methylenedi-4,1-phenylene)bismaleimide. Of these, 4,4'-bismaleimidediphenylmethane is preferred. Bismaleimide compounds may be used individually or in combination of two or more.

[0112] In this rubber composition, the content of the bismaleimide compound per 100 parts by mass of the rubber component is preferably more than 0.1 parts by mass, more preferably more than 0.5 parts by mass, and even more preferably 1.0 part by mass or more. Furthermore, the content is preferably less than 5.5 parts by mass, more preferably less than 5.0 parts by mass, and even more preferably 4.0 parts by mass or less. When the content of the bismaleimide compound is within the above range, it tends to be possible to increase the elastic modulus and improve adhesion.

[0113] (Organic cobalt) This rubber composition may contain cobalt organic acids. Cobalt organic acids act as crosslinkers between the cord and the rubber, and by incorporating this component, the adhesion between the cord and the rubber can be improved. Examples of cobalt organic acids include cobalt stearate, cobalt naphthenate, cobalt neodecanoate, and cobalt boron-3-neodecanate. Among these, cobalt stearate is preferred because it functions as a processing aid (by reducing viscosity).

[0114] From the viewpoint of adhesiveness, the content of organic cobalt acid is preferably more than 0.05 parts by mass, more preferably more than 0.10 parts by mass, and even more preferably more than 0.50 parts by mass, when converted to cobalt, per 100 parts by mass of rubber component. On the other hand, from the viewpoint of the rubber's fracture characteristics, the content is preferably less than 2.00 parts by mass, more preferably less than 1.50 parts by mass, and even more preferably less than 1.00 part by mass.

[0115] From the viewpoint of procurement concerns, the content of cobalt as an element per 100 parts by mass of rubber component is preferably small, for example, less than 0.0010 parts by mass, more preferably less than 0.0009 parts by mass, even more preferably less than 0.0008 parts by mass, even more preferably less than 0.0007 parts by mass, even more preferably 0.0006 parts by mass or less, and even more preferably 0.0005 parts by mass or less.

[0116] (thermosetting resin) This rubber composition may contain a thermosetting resin. This can enhance the adhesion between the cord and the rubber. Examples of thermosetting resins include cashew oil-modified phenolic resin, resorcinol resin, and modified resorcinol resin. Including at least one of these compounds can improve the elongation at break and the complex modulus of elasticity. The thermosetting resin may be used alone or in combination of two or more types.

[0117] Cashew oil-modified phenolic resin is a resin obtained by modifying a phenolic resin, which is produced by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, and furfural using an acid or alkali catalyst, with cashew oil. Examples include those manufactured by Sumitomo Bakelite Co., Ltd. Resorcinol resin is an example of a resorcinol-formaldehyde condensate, and examples include those manufactured by Sumitomo Chemical Co., Ltd. Modified resorcinol resin is an example of a resorcinol resin in which some of the repeating units have been alkylated. Examples include those manufactured by Indospeck, Taoka Chemical Industries, Uniroyal, Schenectady Chemicals, and Ashland Chemicals.

[0118] When a thermosetting resin is included, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 0.7 parts by mass, and even more preferably more than 1.2 parts by mass, from the viewpoint of complex modulus of elasticity and durability. On the other hand, the content is preferably less than 10 parts by mass, more preferably less than 7 parts by mass, and even more preferably less than 3 parts by mass, from the viewpoint of low fuel consumption, elongation at break, processability (sheet rolling ability), and durability.

[0119] (Hardening agent) Thermoplastic resins can be used in combination with a curing agent, which can enhance the adhesion between the cord and the rubber. While not particularly limited, examples of curing agents include hexamethylenetetramine (HMT), hexamethoxymethylolmelamine (HMMM), and partial condensates of hexamethylenemelamine pentamethyl ether (HMMPME). Of these, hexamethylenetetramine (HMT) is preferred. The curing agent may be used alone or in combination of two or more.

[0120] When a curing agent is included, its 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 complex modulus of elasticity (E*). On the other hand, from the viewpoint of elongation at break, the content is preferably less than 5 parts by mass, more preferably less than 3 parts by mass, and even more preferably less than 2 parts by mass.

[0121] <Other compounding agents> In addition to rubber components and fillers, the rubber composition may appropriately contain compounding agents commonly used in the tire industry, such as plasticizers, vulcanized rubber particles, processing aids, waxes, stearic acid, zinc oxide, antioxidants, vulcanizing agents, and vulcanization accelerators.

[0122] (Plasticizer) A plasticizer is a material that imparts plasticity to rubber components, and the concept includes both liquid and solid plasticizers at 25°C. Examples of plasticizers include oils, resin components, liquid rubber, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, from biomass, or from naphtha recycled from rubber or non-rubber products. Low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may also be used as plasticizers. Plasticizers may be used individually or in combination of two or more types.

[0123] ≪Oil≫ Examples of oils include mineral oil, vegetable oil, and animal oil. Furthermore, from a life cycle assessment perspective, waste oil from rubber mixers and engines, or refined waste cooking oil from restaurants, may also be used. Oils may be used individually or in combination of two or more types.

[0124] In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oils (mineral oil), naphthenic oils, and aromatic oils. Specific examples of mineral oil include MES (Mild Extracted Solvate), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Furthermore, for environmental reasons, oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of low-PCA oils include MES, TDAE, and heavy naphthenic oils. Mineral oil may be used alone or in combination of two or more types.

[0125] In this specification, vegetable oils include, for example, 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 wood wax. Furthermore, vegetable oils may also 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, oxidized polymerized oils obtained by oxidizing the above oils, and waste cooking oils recovered from use as edible oils. Note that vegetable oils may be liquid or solid at 25°C. Vegetable oils may be used individually or in combination of two or more types.

[0126] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl 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 polymer of three or more. Note that acylglycerols of two or more forms can be obtained by thermal polymerization, oxidative polymerization, etc. Also, the acylglycerol may be a liquid or a solid at 25°C.

[0127] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, 1 This can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours, and after removing the rubber composition, it is measured at room temperature. 1When 1H-NMR was measured and the tetramethylsilane (TMS) signal was set to 0.00 ppm, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm. These signals are presumed to originate from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0128] The aforementioned fatty acids are not particularly limited and may be unsaturated or saturated fatty acids. 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.

[0129] In particular, it is desirable that the fatty acid contains fatty acids with few double bonds, i.e., saturated fatty acids or monounsaturated fatty acids, and oleic acid is preferred. As a vegetable oil containing such fatty acids, for example, a vegetable oil containing saturated fatty acids or monounsaturated fatty acids may be used, or a vegetable oil that has been modified by transesterification or other means may be used. Furthermore, in order to produce a vegetable oil containing such fatty acids, plants may be improved by breeding, genetic modification, genome editing, etc.

[0130] As for vegetable oils, commercially available products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used.

[0131] Examples of animal oils include fish oil, beef tallow, whale oil, or oleyl alcohol which can be derived from them.

[0132] When oil is included, the content of oil per 100 parts by mass of rubber component is preferably more than 1 part by mass, more preferably more than 2 parts by mass, and even more preferably 3 parts by mass or more, from the viewpoint of processability. Furthermore, the content is preferably less than 40 parts by mass, more preferably less than 20 parts by mass, even more preferably less than 10 parts by mass, and even more preferably less than 5 parts by mass.

[0133] ≪Resin components≫ The rubber composition according to this embodiment may also contain a resin component. The resin component that can be used in this embodiment is not particularly limited, but resins commonly used in the tire industry can be used, such as C9 resins, C5 resins, C5C9 resins, dicyclopentadiene resins, aromatic vinyl resins, coumarone resins, indene resins, terpene resins, rosin resins, phenolic resins, etc. These resin components may be used individually or in combination of two or more. Each resin component may also be used individually or in combination of two or more.

[0134] C9 resin A "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a polymer obtained by polymerizing the C9 fraction alone, or a copolymer obtained by copolymerizing the C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) and a C9 fraction is called a DCPD / C9 resin. Furthermore, the C9 resin may be a hydrogenated or modified version of these resins. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene. As for C9 resins, commercially available products from companies such as BASF, Zeon Corporation, and ENEOS Corporation can be used.

[0135] C5 resin "C5 resins" refer to resins obtained by polymerizing C5 fractions, and may be hydrogenated or modified versions of these resins. Examples of C5 fractions other than dicyclopentadiene include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, isoprene, piperylene, 2-methyl-1-butene, 2-methyl-2-butene, and 1-pentene. As C5 resins, commercially available products from companies such as Structol, Nippon Zeon Co., Ltd., and ENEOS Corporation can be used.

[0136] C5C9 resin "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified. As C5C9 petroleum resin, commercially available products from companies such as Tosoh Corporation and LUHUA can be used.

[0137] Dicyclopentadiene resin A "dicyclopentadiene-based resin" refers to a resin in which cyclopentadiene (CPD) and / or dicyclopentadiene (DCPD) are the most abundant monomer components, and these may be hydrogenated or modified resins. Preferred dicyclopentadiene-based resins include polymers obtained by polymerizing only dicyclopentadiene as a monomer, and copolymers (DCPD / C9 resins) obtained by copolymerizing dicyclopentadiene with the C9 fraction. Commercially available dicyclopentadiene-based resins from companies such as ExxonMobil, ENEOS Corporation, Nippon Zeon Corporation, and Maruzen Petrochemical Co., Ltd. can be used.

[0138] Aromatic vinyl resin "Aromatic vinyl resin" refers to a resin in which aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-chlorostyrene are the most abundant monomer components, and these may be hydrogenated or modified. As aromatic vinyl resins, α-methylstyrene or a homopolymer of styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, for reasons of being economical, easy to process, and having excellent heat generation properties. As aromatic vinyl resins, commercially available products from companies such as Kraton, Eastman Chemical Company, and Mitsui Chemicals, Inc. can be used.

[0139] Coumaron resin "Coumarone-based resin" refers to a resin containing coumarone as a monomer component, and may be hydrogenated or modified. Preferred coumarone-based resins include, for example, coumarone resin, which is a polymer with coumarone as the monomer component; coumarone-indene resin, which is a copolymer with coumarone and indene as monomer components; and coumarone-indene-styrene resin, which is a copolymer with coumarone, indene, and styrene as monomer components. As coumarone-based resins, commercially available products from companies such as Rutgers, Nippon Paint Chemical Co., Ltd., and Mitsui Chemicals, Inc. can be used.

[0140] Indene resin "Indene-based resin" refers to a resin containing indene as a monomer component, and may be hydrogenated or modified resins. Preferred indene-based resins include, for example, coumarone-indene resin, which is a copolymer of coumarone and indene as monomer components, and coumarone-indene-styrene resin, which is a copolymer of coumarone, indene, and styrene as monomer components. Commercially available indene-based resins from companies such as Rutgers, Nippon Paint Chemical Co., Ltd., and Mitsui Chemicals, Inc. can be used.

[0141] Terpene resins "Terpene resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, and dipentene as monomer components, and may be hydrogenated or modified. Preferred terpene resins include, for example, polyterpene resins, which are polymers in which one or more of the aforementioned terpene compounds are used as monomer components; aromatically modified terpene resins, which are copolymers in which the aforementioned terpene compounds and aromatic compounds are used as monomer components; and terpene phenol resins, which are copolymers in which the aforementioned terpene compounds and phenol compounds are used as monomer components. Examples of aromatic compounds that serve as monomer components in aromatically modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenol compounds that serve as monomer components in terpene phenol resins include phenol, bisphenol A, cresol, and xylenol. As terpene resins, commercially available products from companies such as Yasuhara Chemical Co., Ltd., Arakawa Chemical Industries, Ltd., and Nippon Terpene Chemical Co., Ltd. can be used.

[0142] Rosin-based resin "Rosin-based resin" refers to a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palastic acid, and isopimal acid, and may be hydrogenated or modified. Rosin-based resins are not particularly limited, but examples include natural resin rosin and rosin-modified resins obtained by hydrogenating, disproportionating, dimerizing, esterifying, etc. As rosin-based resins, commercially available products from companies such as Harima Chemical Industries, Ltd., Arakawa Chemical Industries, Ltd., and IREC Co., Ltd. can be used.

[0143] Phenolic resins "Phenol-based resins" refer to resins containing phenol compounds such as phenol and cresol as monomer components, and may also be hydrogenated or modified resins. Phenolic resins are not particularly limited, but examples include phenol-formaldehyde resins, alkylphenol-formaldehyde resins, alkylphenol-acetylene resins, oil-modified phenol-formaldehyde resins, and terpene-phenol resins. Phenolic resins that are commercially available from companies such as Sumitomo Bakelite Co., Ltd., DIC Corporation, and Asahi Organic Materials Co., Ltd. can be used.

[0144] From the viewpoint of grip performance, the softening point of the resin component is preferably 60°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher. Furthermore, from the viewpoint of processability and improved dispersibility between the rubber component and filler, it 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 component is measured by the measurement method described above.

[0145] When a resin component is included, the content of the resin component 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 10 parts by mass or more, from the viewpoint of grip strength. On the other hand, from the viewpoint of suppressing heat generation, the content is preferably less than 40 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 15 parts by mass.

[0146] 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, but examples 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. The liquid rubber may be used alone or in combination of two or more types.

[0147] Ester-based plasticizers Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelaate (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). Ester-based plasticizers may be used individually or in combination of two or more.

[0148] The content of plasticizers per 100 parts by mass of rubber component (total amount if multiple plasticizers are used in combination) is preferably more than 1 part by mass, more preferably more than 5 parts by mass, and even more preferably 10 parts by mass or more. Furthermore, the content is preferably less than 40 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 15 parts by mass. Note that the plasticizer content also includes the amount of extensible plasticizers used to stretch the rubber component, such as stretching oil, stretching resin component, stretching liquid rubber component, and stretching ester-based plasticizer.

[0149] (Vulcanized rubber particles) 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 viewpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. One type of vulcanized rubber particle may be used alone, or two or more types may be used in combination.

[0150] The vulcanized rubber particles are not particularly limited and may be either unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0151] Commercially available vulcanized rubber products can be used, such as those from Lehigh, Muraoka Rubber Industries, and others.

[0152] (Processing aid) 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 individually or in combination of two or more. Examples of processing aids that can be used are those commercially available from companies such as Schill+Seilacher and Performance Additives.

[0153] When processing aids are included, the content per 100 parts by mass of rubber components 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 exhibiting an effect of improving processability. Furthermore, from the viewpoint of abrasion resistance and fracture strength, it 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.

[0154] (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. The wax can be commercially available from companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Paramelt Co., Ltd. The wax may be used alone or in combination of two or more types.

[0155] When wax is included, the content per 100 parts by mass of rubber component is preferably more than 0.3 parts by mass, more preferably more than 0.7 parts by mass, and still more preferably more than 1.0 part by mass. On the other hand, the content is preferably less than 4.0 parts by mass, more preferably less than 3.0 parts by mass, and still more preferably less than 2.5 parts by mass.

[0156] (Stearic acid) When stearic acid is included, its content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 0.7 parts by mass, and even more preferably 1.0 part by mass or more, from the viewpoint of processability. On the other hand, from the viewpoint of vulcanization rate, the content is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, and even more preferably less than 3 parts by mass.

[0157] (Zinc oxide) When zinc oxide is included, its content per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 1 part by mass, even more preferably more than 3 parts by mass, and still more preferably more than 5 parts by mass, from the viewpoint of processability. On the other hand, from the viewpoint of wear resistance, the content is preferably less than 10 parts by mass, more preferably less than 9 parts by mass, and even more preferably 8 parts by mass or less.

[0158] (Anti-aging agent) The anti-aging agents are not particularly limited, but include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents 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'-ditril-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as amines (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and 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; 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 or 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products include those from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis. The antioxidant may be used alone or in combination of two or more types.

[0159] When an anti-aging agent is included, the content per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 0.7 parts by mass, and even more preferably 1 part by mass or more, from the viewpoint of the rubber's resistance to ozone cracking. Furthermore, from the viewpoint of wear resistance and wet grip performance, it is preferably less than 5 parts by mass, more preferably less than 3 parts by mass, and even more preferably less than 1.5 parts by mass.

[0160] The rubber composition of this embodiment is resistant to thermal degradation and therefore may not contain substantially any antioxidant. Here, "substantially contained" means that the amount of antioxidant is less than 0.1 parts by mass per 100 parts by mass of the rubber component, preferably less than 0.01 parts by mass, and more preferably less than 0.001 parts by mass.

[0161] (Vulcanizing agent) The vulcanizing agent is not particularly limited, and known vulcanizing agents can be used, such as organic peroxides, sulfur-based vulcanizing agents, resin vulcanizing agents, and metal oxides such as magnesium oxide. Among these, sulfur-based vulcanizing agents can be suitably used. As sulfur-based vulcanizing agents, for example, sulfur, sulfur donors such as morpholine disulfide can be used. Among these, the use of sulfur is preferred. The vulcanizing agent can be used one or in combination of two or more types.

[0162] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur (oil-treated sulfur, special sulfur treated with dispersants, masterbatch-type sulfur, etc.), and insoluble sulfur (oil-treated insoluble sulfur, etc.), all of which can be suitably used. Among these, powdered sulfur is preferred. Sulfur can be used from, for example, products manufactured and sold by Tsurumi Chemical Industries, Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals, Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc.

[0163] As a vulcanizing agent, an organic thiosulfate compound can be used in combination with sulfur. The organic thiosulfate compound is not particularly limited, but compounds represented by the following chemical formula and / or their hydrates are preferred. MO3S-S-(CH2)qS-SO3M (In the formula, q represents an integer between 3 and 10. M represents lithium, potassium, sodium, magnesium, calcium, barium, zinc, nickel, or cobalt, either identical or different.)

[0164] In the above chemical formula, q is preferably an integer between 3 and 6, and M is more preferably potassium or sodium. Preferred hydrates of the compound represented by the above chemical formula include, for example, sodium salt monohydrate and sodium salt dihydrate. Preferred compounds and their hydrates are derivatives derived from sodium thiosulfate, such as 1,6-hexamethylene-dithiosulfate sodium dihydrate.

[0165] When a vulcanizing agent is included, its content per 100 parts by mass of the rubber component is preferably more than 1.0 part by mass, more preferably more than 3.0 parts by mass, and even more preferably more than 5.0 parts by mass. On the other hand, the content is preferably less than 10.0 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably 7.0 parts by mass or less. When the vulcanizing agent content is within the above range, an appropriate reinforcing effect tends to be obtained. Note that the vulcanizing agent content refers to the content of the vulcanizing agent that does not contain the maleimide compound. Furthermore, if the vulcanizing agent contains components other than the vulcanizing agent, such as oil-treated sulfur, the vulcanizing agent content refers to the content of the vulcanizing agent itself.

[0166] (Vulcanization accelerator) The vulcanization accelerator is not particularly limited, and known vulcanization accelerators can be used, such as sulfenamide, thiazole, thiram, thiourea, guanidine, dithiocarbamate, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Among these, sulfenamide, thiram, and guanidine are preferred, with sulfenamide being more preferred. Vulcanization accelerators manufactured and sold by companies such as Ouchi Shinko Chemical Industry Co., Ltd. and Sanshin Chemical Industry Co., Ltd. can be used. These vulcanization accelerators can be used individually or in combination of two or more.

[0167] Examples of sulfenamide-based vulcanization accelerators include N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide (DZ). Examples of thiuram-based vulcanization accelerators include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, and tetrabenzylthiuram disulfide (TBzTD). Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), diortotolylguanidine, and orthotolylbiguanidine.

[0168] The content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably more than 0.3 parts by mass, more preferably more than 0.5 parts by mass, and even more preferably 1.0 part by mass or more. On the other hand, the content is preferably less than 4.0 parts by mass, more preferably less than 3.0 parts by mass, and even more preferably less than 2.0 parts by mass. When the content of the vulcanization accelerator is within the above range, fracture strength and elongation tend to be ensured, and the effects of the present invention tend to be exhibited more favorably.

[0169] <Manufacturing Method> The tire of this embodiment can be manufactured by known methods.

[0170] (Manufacturing of the rubber composition that makes up the breaker topping rubber) This rubber composition can be manufactured by known methods. For example, it can be manufactured by kneading each of the above components using a rubber kneading device such as an open roll or a closed kneader (Banbury mixer, kneader, etc.). The kneading process includes, for example, a base kneading process in which compounding agents and additives other than the vulcanizing agent and vulcanization accelerator are kneaded, and a final kneading (F kneading) process in which the vulcanizing agent and vulcanization accelerator are added to the kneaded product obtained in the base kneading process and kneaded. Furthermore, the base kneading process can be divided into multiple processes as desired. The kneading conditions are not particularly limited, but for example, in the base kneading process, kneading is performed at a discharge temperature of 150 to 170°C for 3 to 10 minutes, and in the final kneading process, kneading is performed at a temperature of 50 to 110°C for 1 to 5 minutes.

[0171] (Circuit breaker manufacturing) The breaker consists of one or more breaker plies. The breaker plies can be manufactured by covering the breaker cord with the breaker topping rubber described above. The material of the breaker cord is not particularly limited and includes, for example, metal cords (such as steel cords), organic fiber cords, inorganic fiber cords (excluding metal cords), etc. The breaker plies thus obtained can be used as breakers positioned on the radially inner side of the tread and on the radially outer side of the carcass.

[0172] The metal cord may be a single-wire monofilament cord (i.e., a cord consisting of one filament having a 1x1 structure), or it may have multiple filaments. If a single metal cord has multiple filaments, it is preferable that the metal cord has a twisted structure in which the filaments are twisted together along its longitudinal direction. The twisted structure is not particularly limited and can be, for example, a single-twist metal cord with a 1xN structure or a layered twist metal cord with a K+M structure. Here, for example, N is an integer from 1 to 27, K is an integer from 1 to 10, M is an integer from 1 to 3, etc.

[0173] The filaments constituting the organic fiber cord are not particularly limited, but examples include polyester fibers, nylon fibers, aramid fibers, polyketone fibers, poly(p-phenylenenium) acrylate fibers, polyacrylate fibers, rayon fibers, cellulose fibers, carbon fibers, etc., with polyester fibers being preferred. These organic fibers may be made from synthetic fibers, biomass-derived fibers, recycled / regenerated fibers, etc. These organic fibers may be used individually or in combination of two or more types. The organic fiber cord can be made by twisting together multiple yarns, each made by twisting together multiple filaments.

[0174] Examples of inorganic fiber cords other than metal cords include carbon fiber cords and glass fiber cords.

[0175] (Tire manufacturing) The breaker ply obtained as described above can be molded together with other tire components on a tire molding machine in a conventional manner at the pre-vulcanization stage to produce an unvulcanized tire. By heating and pressurizing (vulcanizing) this unvulcanized tire in a vulcanizing machine, the tire of the present invention can be obtained. The vulcanization conditions are not particularly limited, and for example, a method of vulcanization at 150 to 200°C for 5 to 30 minutes can be used.

[0176] <Application> In this specification, tires, whether pneumatic or non-pneumatic, can be used for any purpose, including passenger car tires, large passenger car tires, large SUV tires, racing tires, motorcycle tires, heavy-duty tires, and run-flat tires. Passenger car tires are defined as tires intended for use on four-wheeled vehicles with a maximum load capacity of less than 1400 kg. Heavy-duty tires are defined as tires with a maximum load capacity of 1400 kg or more. In this specification, tires can be used as all-season tires, summer tires, and winter tires such as studless tires. [Examples]

[0177] The following examples (case studies) are shown as preferred for implementation, but the scope of the present invention is not limited to these examples. Tires obtained using the various chemicals shown below, according to each table, were examined, and the results calculated based on the evaluation method below are shown as fuel efficiency indices at the bottom of each table.

[0178] <Various chemicals> The materials used in the examples and comparative examples are described below. IR-type rubber: NR (TSR20) Carbon Black 1: Show Black N220 (N2SA: 115m) manufactured by Cabot Japan Co., Ltd. 2 ( / g, average primary particle size: 22nm, ash content: less than 1.0% by mass) Carbon Black 2: Show Black N330 (N2SA: 75m) manufactured by Cabot Japan Co., Ltd. 2 ( / g, average primary particle size: 30 nm, ash content: less than 1.0% by mass) Recycled carbon black (rCB): Carbon black obtained from the thermal decomposition process of tires (ash content: 17% by mass) Oil: VivaTec400 (manufactured by H&R Co., Ltd., TDAE oil, Tg: -58℃) Zinc oxide: Two types of zinc oxide (manufactured by Mitsui Mining & Smelting Co., Ltd.) Stearic acid: Beads-derived stearic acid (manufactured by NOF Corporation) Organic cobalt acid: Co-STEARATE (manufactured by DIC Corporation, cobalt stearate, cobalt content: 9.5% by mass, stearic acid content: 90.5% by mass) Thermosetting resin: PR12686 (manufactured by Sumitomo Bakelite Co., Ltd., cashew oil modified phenolic resin) Hardener: Sunceller HT (manufactured by Sanshin Chemical Industry Co., Ltd., hexamethylenetetramine) Anti-aging agent: Antigen 6C (manufactured by Sumitomo Chemical Co., Ltd., N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) Sulfur: HK-200-5 (manufactured by Hosoi Chemical Industry Co., Ltd., powdered sulfur, oil content: 5% by mass) Vulcanization accelerator: Noxellar DZ (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., N,N-dicyclohexyl-2-benzothiazolyl sulfenamide) Bismaleimide compound: 4,4'-bismaleimidediphenylmethane

[0179] <Examples and Comparative Examples> According to the formulations shown in each table, the chemicals other than sulfur and vulcanization accelerator are mixed in a 1.7 L closed Banbury mixer for 5 minutes until the discharge temperature reaches 160°C to obtain a mixture. Next, using a twin-screw open roll mixer, the vulcanizing agent and vulcanization accelerator are added to the obtained mixture and mixed for 4 minutes until the temperature reaches 105°C to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is used to coat steel cord (filament diameter: 0.30 mm) to obtain a steel cord-rubber composite.

[0180] The two resulting steel cord-rubber composites were used as breaker plies as shown in Figure 1, and bonded together with other tire components to produce an unvulcanized tire. These were then press-vulcanized for 12 minutes under conditions of 170°C to obtain each test tire (Tire 1: 275 / 80R22.5, Tire 2: 195 / 65R15).

[0181] The tire weight of tire 1 (275 / 80R22.5) is 37.0 kg, W L It is 1830 kg, G / W L It is 0.0202. On the other hand, the tire weight of tire 2 (195 / 65R15) is 7.8 kg, W L It is 609 kg, G / W L It is 0.0128.

[0182] <Rating> (Measurement of fracture elongation before thermal degradation and fracture elongation after thermal degradation) A new test tire will be subjected to heat degradation in an 80°C oven for 7 days to create a heat-degraded tire. A new sample taken from the breaker topping rubber of a new tire, and a heat-degraded sample taken from the breaker topping rubber of a heat-degraded tire, will each be subjected to a tensile test in accordance with JIS K 6251:2017, under conditions of a 23°C atmosphere and a tensile speed of 3.3 mm / sec, and the elongation at break (%) will be measured. The sample will be 20 mm long × 4 mm wide × 1 mm thick, with the tire circumference being the longer side and the tire diameter being the thickness.

[0183] The resulting fracture elongation EB before thermal degradation is obtained in this way. BF (%), elongation after thermal degradation EB AF From (%), the ratio (%) of the elongation at break after thermal degradation to the elongation at break before thermal degradation is given by the following formula: R EB We seek. R EB =EB AF / EB BF ×100

[0184] (Fuel efficiency) For each test tire, the rolling resistance was measured using a rolling resistance tester at a speed of 80 km / h, and the reciprocal of this value was expressed as an exponential value with the reference comparison example set to 100. The comparison reference examples are Comparative Examples 1-3 in Table 1 and Comparative Examples 2-3 in Table 2. A higher value indicates lower rolling resistance and superior fuel efficiency.

[0185] [Table 1]

[0186] [Table 2]

[0187] <Embodiment> The following describes preferred embodiments.

[0188] <1> It is a tire equipped with breaker topping rubber. The rubber composition constituting the aforementioned breaker topping rubber contains a bismaleimide compound. Let G be the weight (kg) of the aforementioned tire, and W be its maximum load capacity (kg). L The thickness (mm) of the breaker topping rubber is D BRK The ratio (%) of the elongation at break of the rubber composition after being left to thermally degrade at 80°C for 7 days to the elongation at break before thermal degradation is R EB In that case, G / W L is 0.0250 or less, preferably 0.240 or less, more preferably 0.0230 or less, and even more preferably 0.0220, D BRK and R EB A tire that satisfies the following equation, preferably with the right-hand side of equation (1) being 45.0, more preferably 50.0, and even more preferably 55.0. (1) R EB / D BRK >40.0 <2> The aforementioned G / W L The above is 0.0210 or less, preferably 0.0200 or less, more preferably 0.0190 or less, and even more preferably 0.0180 or less. <1> The tires as listed. <3> The aforementioned G / W L The above is 0.0170 or less, preferably 0.0160 or less. <1> The tires as listed. <4> The aforementioned G / W L The above is 0.0150 or less, preferably 0.0140 or less. <1> The tires as listed. <5> The aforementioned G / W L The above is less than or equal to 0.0130. <1> The tires as listed. <6> The aforementioned G / W L The above is 0.0128 or less. <1> The tires as listed. <7> The rubber composition contains recycled carbon black, <1> ~ Above <6> The tires listed in any one of the items. <8> The rubber composition includes a thermosetting resin, <1> ~ Above <7> The tires listed in any one of the items. <9> G, W L , D BRKand R EB The above satisfies the following equation, preferably the right-hand side of equation (2) is 3000, more preferably 3500, even more preferably 4000, and even more preferably 4300. <1> ~ Above <8> The tires listed in any one of the items. (2) R EB / (D BRK ×(G / W L ))>2700 <10> The rubber composition has an elongation at break before thermal degradation of EB BF If that is the case, EB BF , D BRK and R EB The above satisfies the following equation, preferably the right-hand side of equation (3) is 15000, more preferably 16000, even more preferably 17000, even more preferably 18000, and even more preferably 19000. <1> ~ Above <9> The tires listed in any one of the items. (3) R EB / D BRK ×EB BF >14000 <11> The cobalt element content in the rubber composition is 0.0010 parts by mass or less, preferably less than 0.0010 parts by mass, more preferably less than 0.0009 parts by mass, even more preferably less than 0.0008 parts by mass, even more preferably less than 0.0007 parts by mass, even more preferably 0.0006 parts by mass or less, and even more preferably 0.0005 parts by mass or less, per 100 parts by mass of rubber component. <1> ~ Above <10> The tires listed in any one of the items. <12> D BRK However, the above is less than 1.5 mm, preferably 1.4 mm or less, more preferably less than 1.3 mm, even more preferably less than 1.2 mm, and even more preferably less than 1.1 mm. <1> ~ Above <11> The tires listed in any one of the items. [Explanation of symbols]

[0189] 1 tire 2 Circuit breakers 2a First breaker ply 2b Second breaker ply D BRKBreaker topping rubber thickness CL tire centerline

Claims

1. It is a tire equipped with breaker topping rubber. The rubber composition constituting the aforementioned breaker topping rubber contains a bismaleimide compound. Let G be the weight (kg) of the aforementioned tire, and W be its maximum load capacity (kg). L The thickness (mm) of the aforementioned breaker topping rubber is D BRK The ratio (%) of the elongation at break of the rubber composition after being left to thermally degrade at 80°C for 7 days to the elongation at break before thermal degradation is R EB In that case, G / W L If it is 0.0250 or less, D BRK and R EB A tire that satisfies the following equation. (1) R EB / D BRK >40.0

2. The G / W L is 0.0210 or less, the tire according to claim 1.

3. The aforementioned G / W L The tire according to claim 1, wherein the coefficient is 0.0170 or less.

4. The aforementioned G / W L The tire according to claim 1, wherein the coefficient is 0.0150 or less.

5. The aforementioned G / W L The tire according to claim 1, wherein the coefficient is 0.0130 or less.

6. The aforementioned G / W L The tire according to claim 1, wherein the coefficient is 0.0128 or less.

7. The tire according to any one of claims 1 to 6, wherein the rubber composition contains recycled carbon black.

8. The tire according to any one of claims 1 to 6, wherein the rubber composition comprises a thermosetting resin.

9. G, W L , D BRK and R EB A tire according to any one of claims 1 to 6, wherein the following formula is satisfied. (2) R EB / (D BRK ×(G / W L ))>2700

10. The elongation at break of the rubber composition before thermal degradation is EB BF If that is the case, EB BF , D BRK and R EB A tire according to any one of claims 1 to 6, wherein the following formula is satisfied. (3) R EB / D BRK ×EB BF >14000

11. The tire according to any one of claims 1 to 6, wherein the content of cobalt element in the rubber composition is 0.0010 parts by mass or less per 100 parts by mass of rubber component.

12. D BRK A tire according to any one of claims 1 to 6, wherein the thickness is less than 1.5 mm.

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