tire

Abstract

The present invention provides a tire in which belt delamination due to moisture infiltration from inside the tire is suppressed. [Solution] A tire comprising a belt and an internal member disposed radially inward of the belt, wherein the belt includes at least one belt ply having a metal cord and a topping rubber covering the metal cord, and when A is the cobalt content (parts by mass) per 100 parts by mass of rubber component in the rubber composition constituting the topping rubber, A is 0.03 parts by mass or less, and the internal member is composed of a rubber composition containing a moisture permeability inhibiting filler, and when B is the content (parts by mass) of the moisture permeability inhibiting filler per 100 parts by mass of rubber component in the rubber composition constituting the internal member, A and B satisfy the following formula (1). (1) B / (A+5)>1

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] One of the damages to the reinforcing layer such as the belt in a tire is the peeling of the reinforcing layer due to the breakage of the adhesive layer between the cords and the topping rubber in the reinforcing layer. As the destruction mechanism of the adhesive layer, hydrolysis of the adhesive layer due to intrusion of moisture into the adhesive layer, promotion of generation of substances causing destruction of the adhesive layer such as zinc sulfide and copper sulfide, etc. are known. In order to improve the adhesion performance of the adhesive layer, it is generally used to contain a cobalt compound in the topping rubber. However, cobalt has a high degree of production location dependence and has potential geopolitical risks. Also, cobalt is tending to be subject to stricter environmental regulations. For this reason, studies are being conducted to improve the adhesion performance of the reinforcing layer while suppressing the use of cobalt compounds (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the present invention, there is provided a tire in which peeling of the belt due to penetration of moisture from inside the tire is suppressed.

Means for Solving the Problems

[0005] That is, the present invention relates to the following tire. A tire including a belt and an inner member disposed radially inside the belt of the tire, The belt includes at least one belt ply having a metal cord and topping rubber covering the metal cord. When the cobalt content (parts by mass) per 100 parts by mass of the rubber component in the rubber composition constituting the topping rubber is A, A is 0.03 parts by mass or less. The inner member is made of a rubber composition containing a moisture permeation suppressing filler. When the content (parts by mass) of the moisture permeation suppressing filler per 100 parts by mass of the rubber component in the rubber composition constituting the inner member is B, the tire in which A and B satisfy the following formula (1). (1) B / (A + 5)> 1

Effect of the Invention

[0006] According to the present invention, peeling of the belt due to penetration of moisture from the inside of the tire can be suppressed.

Brief Description of the Drawings

[0007] [Figure 1] It is a cross-sectional view passing through the tire rotation axis of the tire according to one embodiment of the present invention.

Mode for Carrying Out the Invention

[0008] Hereinafter, a tire which is one embodiment of the present invention will be described. The tire of the present embodiment is a tire including a belt and an inner member disposed on the inner side in the tire radial direction of the belt. The belt includes at least one belt ply having a metal cord and topping rubber covering the metal cord. When the cobalt content (parts by mass) per 100 parts by mass of the rubber component in the rubber composition constituting the topping rubber is A, A is 0.03 parts by mass or less. The inner member is made of a rubber composition containing a moisture permeation suppressing filler. When the content (parts by mass) of the moisture permeation suppressing filler per 100 parts by mass of the rubber component in the rubber composition constituting the inner member is B, the tire in which A and B satisfy the following formula (1). (1) B / (A + 5)> 1

[0009] While not intended to be constrained by theory, the following mechanisms are considered to be the mechanisms by which belt delamination is suppressed in this invention. Specifically, since moisture is believed to enter mainly from the inside of the tire, it is thought that incorporating a moisture permeability-inhibiting filler into the internal components of the tire suppresses moisture penetration from the inner surface of the tire into the belt. Furthermore, since a decrease in the amount of cobalt in the rubber composition constituting the topping rubber reduces the adhesive performance between the metal cord and the topping rubber, the content of the moisture permeability-inhibiting filler and the amount of cobalt are adjusted to satisfy a predetermined relationship in order to maintain and improve adhesive performance. It is thought that belt delamination is suppressed by the cooperation of these factors.

[0010] The right-hand side of equation (1) is preferably 3, and more preferably 5.

[0011] This is because it satisfies equation (1) under stricter conditions.

[0012] When the thickness of the belt (mm) is T and the thickness of the internal member (mm) is L, it is preferable that T, L, and B satisfy the following formula (2). (2) T×L×B>10

[0013] Increasing the belt thickness increases the distance from the inside of the tire to the metal cords and topping rubber, making it more difficult for moisture to reach the adhesive layer between the metal cords and topping rubber. Similarly, increasing the thickness of the internal components also increases the distance from the inside of the tire to the metal cords and topping rubber, making it more difficult for moisture to reach the adhesive layer. Furthermore, increasing the content of the moisture permeability-inhibiting filler suppresses the intrusion of moisture from the inside of the tire into the belt. Therefore, it is believed that the adhesive performance is maintained or improved by adjusting T, L, and B to satisfy equation (2).

[0014] The right-hand side of equation (2) is preferably 20.

[0015] This is because it satisfies equation (2) under stricter conditions.

[0016] The rubber composition constituting the internal member preferably contains a rubber component including butyl rubber.

[0017] Butyl rubber has high moisture permeability suppression properties, and it is thought that incorporating butyl rubber into the internal components of the tire will suppress moisture penetration from the inner surface of the tire into the belt.

[0018] The rubber composition constituting the topping rubber preferably contains a rubber component including isoprene-based rubber.

[0019] Since isoprene-based rubber has high tear strength and mechanical strength, it is believed that using isoprene-based rubber will increase the strength of the belt topping rubber, thereby improving the strength and flexibility of the belt itself.

[0020] Preferably, the rubber composition constituting the internal member contains 70% to 100% by mass of butyl rubber in 100% by mass of the rubber component, and contains 10 to 70 parts by mass of a moisture permeability inhibiting filler per 100 parts by mass of the rubber component.

[0021] It is believed that by having the content of butyl rubber and moisture permeability-inhibiting filler in the rubber composition constituting the internal components within the above range, moisture penetration into the belt can be effectively suppressed.

[0022] Preferably, the rubber composition constituting the topping rubber contains 80% to 100% by mass of isoprene-based rubber in 100% by mass of the rubber components, and A is 0.02 parts by mass or less.

[0023] In the rubber composition constituting the topping rubber, it is believed that maintaining or improving the adhesive performance between the metal cord and the topping rubber is achieved by having the isoprene-based rubber and cobalt content within the above range.

[0024] In the rubber composition constituting the internal member, when the carbon black content (parts by mass) per 100 parts by mass of rubber component is C, it is preferable that B, C, and L satisfy the following formula (3). (3) B / (B+C) × L < 1

[0025] An internal component made of a rubber composition satisfying formula (3) is considered to have appropriately adjusted moisture permeability-inhibiting filler content, butyl rubber content, and thickness of the internal component from the viewpoint of suppressing moisture permeability.

[0026] It is preferable that the rubber composition constituting the topping rubber contains a bismaleimide compound, and when the content (parts by mass) of the bismaleimide compound per 100 parts by mass of the rubber component is E, then A, E, and T satisfy the following formula (4). (4)(A+E) / T>1

[0027] Topping rubber composed of a rubber composition satisfying formula (4) is considered to have enhanced adhesive performance between the metal cord and the topping rubber.

[0028] The moisture permeation-inhibiting filler preferably contains at least one selected from the group consisting of kaolinite, dickite, nacrite, halloysite, chrysotile, lizardite, antigorite, pyrophyllite, talc, kerolite, willemsite, vimelite, minnesotaite, mica, chlorite, smectite, vermiculite, saponite, hectorite, stevensite, montmorillonite, beiderite, nontronite, boehmite, hydrotalcite, recycled carbon black, and rubber powder.

[0029] It is believed that the moisture permeability inhibiting properties of the rubber composition constituting the internal components will be further improved by including a moisture permeability inhibiting filler selected from these options.

[0030] The metal cord preferably includes a steel cord having a plating layer of binary plating of copper and zinc, ternary plating of copper, zinc and cobalt, or ternary plating of copper, zinc and iron.

[0031] Belt plies containing steel cords with such a plating layer are expected to improve the adhesion between the cords and the topping rubber, thereby suppressing belt delamination.

[0032] <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.

[0033] 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.

[0034] 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).

[0035] "Regular internal pressure" refers to the air pressure specified for each tire in the standard system, including the standard on which the tire is based. For example, in the case of JATMA, it refers to "Maximum Air Pressure," in the case of ETRTO, it refers to "INFLATION PRESSURE," and in the case of 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 (however, only those 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.

[0036] "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.

[0037] "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.

[0038]

number

[0039] A "belt" is a layer located radially outward from the carcass, and consists of at least one belt ply comprising multiple metal cords and a topping rubber covering the metal cords. The multiple metal cords constituting the belt ply are arranged substantially parallel to each other. The belt can also consist of multiple working layers in which the internal metal cords are tilted at approximately 18-30° with respect to the tire's circumferential direction and overlap in opposite directions, or a circumferential belt layer in which the internal metal cords are oriented at an angle of ±10° with respect to the tire's circumferential direction.

[0040] "Internal components" refer to tire components located radially inward from the belt. Specifically, these include the inner liner that forms the inner surface of the tire, and the insulation (also called tigum) located radially outward from the inner liner, between the carcass and the inner liner.

[0041] "Belt thickness," "internal component thickness," "inner liner thickness," and "insulation thickness" are the radial thickness of each component layer on the equator in the cross-section of the tire, based on a plane containing the tire rotation axis. If the component is not located on the equatorial plane, the radial thickness of each component layer at the center of the component in the tire width direction is used.

[0042] A "filament" refers to the smallest unit that forms a steel cord. A yarn is made by twisting together multiple such filaments.

[0043] "Rubber components of a rubber composition" refer to components that contribute to crosslinking within a rubber composition, and generally have a weight-average molecular weight (Mw) of 10,000 or more, but are excluded if they are liquid at 25°C.

[0044] A "plasticizer" is a material that imparts plasticity to rubber components and is extracted from rubber compositions using acetone. This definition includes both liquid plasticizers at 25°C and solid plasticizers at 25°C. However, it excludes waxes and stearic acid commonly used in the tire industry.

[0045] "Plasticizer content" includes the amount of plasticizer in the rubber component that has been stretched by the plasticizer.

[0046] <Measurement method> The "thickness of the inner liner," "thickness of the insulation," "thickness of the belt," and "thickness of the internal components" are calculated using the average of the values ​​measured at five points in the tire's cross-section, including the tire's axis of rotation, at a rate of 72 degrees each. The measurement can be performed by creating a cross-sectional piece of the tire including the tire's axis of rotation and holding it in a position where the distance between the beads matches the standard rim width.

[0047] "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.

[0048] The "vinyl content (amount of 1,2 - bonded butadiene units)" is calculated by pyrolysis gas chromatography or NMR measurement ( 1 1H - NMR and 13 13C - NMR). Similar to the "styrene content", since there is a true value that does not depend on the measurement method for the "vinyl content", it is preferable to use a measurement method with as high precision as possible.

[0049] The "cis content (amount of cis - 1,4 - bonded butadiene units)" is a value measured by infrared absorption spectroscopy or NMR measurement ( 1 1H - NMR and 13 13C - NMR) in accordance with JIS K 6239 - 2:2017, and is applied to, for example, rubber components having repeating units derived from butadiene such as BR. Similar to the "styrene content", since there is a true value that does not depend on the measurement method for the "cis content", it is preferable to use a measurement method with as high precision as possible.

[0050] The "weight - average molecular weight (Mw)" can be determined by standard polystyrene conversion based on the measurement value by gel permeation chromatography (GPC) (for example, GPC - 8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKgel (registered trademark) SuperMultipore HZ - M manufactured by Tosoh Corporation). For example, it is applied to SBR, BR, plasticizers, etc.

[0051] The "nitrogen adsorption specific surface area of carbon black (N2SA)" is measured in accordance with JIS K 6217 - 2:2017.

[0052] The "nitrogen adsorption specific surface area of silica (N2SA)" is measured by the BET method in accordance with ASTM D3037 - 93.

[0053] The "average primary particle diameter" is a value obtained by photographing the particles with a transmission or scanning electron microscope and calculating the arithmetic mean of the particle diameters of 400 particles. When the shape of the particles is spherical, the diameter of the sphere is taken as the particle diameter, and when the shape is other than spherical, the equivalent circle diameter ({the positive square root of 4×(the area of the particle) / π}) is calculated from the microscope image and taken as the particle diameter.

[0054] The "softening point of the resin component" is the temperature at which the sphere descends when the softening point specified in JIS K 6220-1:2015 7.7 is measured using a ring-type softening point measuring device.

[0055] The embodiments will be described in further detail below. However, the following description is illustrative for explaining the present invention, and the present invention is not limited to these. Drawings will be used as appropriate, but the drawings are for illustrative purposes only.

[0056] <Tires> 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. The tire 1 in Figure 1 comprises a cap tread 2 including the tread surface, a base tread 3, a band 4, a belt 5, a carcass 6, insulation 7, and an inner liner 8. The inner liner 8 constitutes the inner surface of the tire and maintains the internal pressure of the tire. The insulation 7 is adjacent to the radially outer side of the inner liner 8, and the inner liner 8 is joined to other members such as the carcass 6 via the insulation 7. The thickness of the inner liner 8 along the tire centerline is indicated by L1. The thickness of the belt 5 along the tire centerline is indicated by T.

[0057] In Figure 1, the belt 5 is composed of a single belt ply comprising multiple metal cords and a topping rubber covering the metal cords. The belt 5 may be composed of multiple belt plies, but from the viewpoint of reducing tire weight, it is preferable to be composed of fewer belt plies.

[0058] 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. The metal cord may be straight, or it may be shaped in a wavy or zigzag pattern.

[0059] The metal cord is not particularly limited, but examples include wires made of steel, stainless steel, lead, aluminum, copper, brass, bronze, nickel, zinc, etc. Steel cord is preferred. Furthermore, it is preferable that the metal cord has a plating layer on its surface, which is produced by a conventional method. The plating is not particularly limited, but examples include zinc plating, copper plating, brass plating, copper-cobalt-zinc plating, and other ternary platings. Furthermore, it is preferable that the metal cord, such as steel cord, has a plating layer on its surface, which is a binary copper and zinc plating, a ternary copper, zinc and cobalt plating, or a ternary copper, zinc and iron plating. It is believed that having a plating layer on the surface of the metal cord improves its adhesion performance to the topping rubber.

[0060] The plating layer can be formed, for example, by plating a metal cord such as a steel cord with a copper layer, a zinc layer, and optionally a cobalt layer or nickel layer, and then diffusing the metals of each layer formed on the surface of the metal cord by heat treatment. The stacking order of the plating layers formed on the surface of the metal cord is not particularly limited, but for example, the layers can be stacked in the order of copper layer followed by zinc layer from the metal cord side. Furthermore, it is preferable to form the cobalt layer between the copper layer and the zinc layer, or on top of the zinc layer. It is preferable to form the iron layer between the copper layer and the zinc layer.

[0061] There are no particular restrictions on the diameter of the metal cord, but it is preferably 0.15 mm or larger, more preferably 0.18 mm or larger, even more preferably 0.20 mm or larger, and even more preferably 0.30 mm or larger. Furthermore, from the viewpoint of reducing tire weight, the diameter of the metal cord is preferably 0.60 mm or smaller, more preferably 0.55 mm or smaller, even more preferably 0.50 mm or smaller, and even more preferably 0.40 mm or smaller.

[0062] Furthermore, in this embodiment, the internal component is preferably an inner liner and / or insulation, and more preferably an inner liner. It is believed that by having an inner liner and / or insulation as the internal component, moisture intrusion from the inner surface of the tire into the belt is suppressed, and the adhesive performance between the topping rubber and the metal cord is maintained and improved.

[0063] (Formula (1)) In the tire of this embodiment, A and B satisfy the relationship given by equation (1). (1) B / (A+5)>1

[0064] In equation (1), as B increases, the value on the left side of equation (1) increases, and conversely, as B decreases, the value decreases. A takes a value of 0.03 or less.

[0065] The right-hand side of equation (1) is preferably 1.5, more preferably 2, even more preferably 3, even more preferably 4, and even more preferably 5. On the other hand, there is no particular upper limit on the left-hand side of equation (1), but it is usually around 15, or it may be around 12 or 10.

[0066] (Formula (2)) In the tire of this embodiment, it is preferable that T, L, and B satisfy the relationship given by equation (2). (2) T×L×B>10

[0067] In equation (2), as T, L, and B increase, the value on the left side of equation (2) increases, and conversely, as they decrease, the value decreases.

[0068] Here, the right-hand side of equation (2) is preferably 20, more preferably 30, and even more preferably 50. On the other hand, there is no particular upper limit on the left-hand side of equation (2), but it is usually around 100, or it may be around 80 or 60.

[0069] The value of L is, for example, 0.1 mm or more, preferably 0.5 mm or more, more preferably 0.7 mm or more, and even more preferably 1.0 mm or more. On the other hand, the value is preferably 5.0 mm or less, more preferably 4.5 mm or less, and even more preferably 4.0 mm or less.

[0070] The value of L (mm) may vary depending on the type of internal material. In the case of insulation, for example, the thickness of the insulation is preferably 0.1 mm or more, more preferably 0.5 mm or more, and even more preferably 0.7 mm or more. There is no particular upper limit, but it is preferably 2 mm or less, more preferably 1.5 mm or less, and even more preferably 1.0 mm or less.

[0071] In the case of an inner liner, for example, the thickness of the inner liner is preferably 0.5 mm or more, more preferably 0.7 mm or more, and even more preferably 1.0 mm or more. There is no particular upper limit, but it is preferably 2.5 mm or less, more preferably 2.0 mm or less, and even more preferably 1.5 mm or less.

[0072] The belt thickness T (mm) is preferably 0.5 mm or more, more preferably 0.8 mm or more, even more preferably 1.0 mm or more, even more preferably 1.5 mm or more, and even more preferably 2.0 mm or more. There is no particular upper limit, but it is preferably 4.5 mm or less, more preferably 4.0 mm or less, even more preferably 3.5 mm or less, and even more preferably 3.0 mm or less.

[0073] (Formula (3)) In the tire of this embodiment, it is preferable that B, C, and L satisfy the relationship given by equation (3). (3) B / (B+C) × L < 1

[0074] In equation (3), as B and L increase, the value on the left side of equation (3) increases, and conversely, as B and L decrease, the value decreases. Also, increasing the value of C decreases the value on the left side of equation (3), and decreasing the value of C increases the value on the left side of equation (3).

[0075] Here, the right-hand side of equation (3) is preferably 0.8, more preferably 0.6, and even more preferably 0.5. On the other hand, the lower limit of the left-hand side of equation (3) is not particularly limited, but may be around 0.1, more preferably around 0.2, and even more preferably around 0.3.

[0076] (Formula (4)) In the tire of this embodiment, it is preferable that A, E, and T satisfy the relationship given by equation (4). (4)(A+E) / T>1

[0077] In equation (4), as the values ​​of A and E increase, the value on the left side of equation (4) increases, and conversely, as their values ​​decrease, the value on the left side decreases. Also, as T increases, the value on the left side of equation (4) decreases, and conversely, as T decreases, the value on the left side of equation (4) increases.

[0078] Here, the right-hand side of equation (4) is preferably 1.2, more preferably 1.5, even more preferably 1.7, and even more preferably 1.9. On the other hand, there is no particular upper limit on the left-hand side of equation (4), but it is usually around 6, or it may be around 5 or 4.

[0079] The following describes the rubber compositions that make up the belt topping rubber and the rubber compositions that make up the internal components, specifically the rubber compositions that make up the inner liner and the rubber compositions that make up the insulation.

[0080] <Rubber composition constituting belt topping rubber> The rubber composition constituting the belt topping rubber will be described below. In this specification, the rubber composition constituting the belt topping rubber may also be referred to as the rubber composition for belt topping rubber.

[0081] (Rubber component) The rubber component may include at least one rubber selected from isoprene rubber (IR rubber), butadiene rubber (BR), and styrene-butadiene rubber (SBR). It is preferable that the rubber component includes isoprene rubber (IR rubber).

[0082] ≪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 alone or in combination of two or more types.

[0083] ≪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.

[0084] 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 the method described above.

[0085] 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.

[0086] ≪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. (those with condensates, branched structures, etc.). 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, and both are usable. Examples of such SBRs that can be used include products from JSR Corporation, Asahi Kasei Chemicals Corporation, Nippon Zeon Corporation, ZS Elastomer Co., Ltd., etc. SBRs can be used individually or in combination of two or more types.

[0087] 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 the value calculated by the method described above.

[0088] 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 more preferably less than 30.0 mol%. Note that the vinyl content of SBR is the value measured by the method described above.

[0089] ≪Content≫ The content of IR-type rubber in 100% by mass of the rubber component is, for example, 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, and may be 100% by mass.

[0090] When the rubber component contains BR, the BR content in 100% by mass of the rubber component is, for example, less than 30% by mass, 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 the content; it may be 0% by mass, but for example, it may be 1% by mass.

[0091] When the rubber component contains SBR, the SBR content in 100% by mass of the rubber component is, for example, less than 30% by mass, 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 the content, and it may be 0% by mass, but for example it may be 1% by mass.

[0092] (Other rubber components) Other rubber components besides butyl rubber include, for example, diene rubbers such as isoprene rubber (IR rubber), butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and polynorbornene rubber, as well as non-diene rubbers such as hydrogenated nitrile rubber (HNBR), ethylene propylene rubber, silicone rubber, polyethylene chloride rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. Of these, diene rubbers are preferred, and among them, isoprene rubber is preferred from the viewpoint of improving adhesion and bonding with adjacent tire components. Other rubber components may be used individually or in combination of two or more.

[0093] When other rubber components are included, their content in 100% by mass of the rubber components may be, for example, more than 1% by mass, preferably more than 3% by mass, more preferably more than 5% by mass, and even more preferably 8% by mass or more, from the viewpoint of exhibiting performance such as oil resistance and cold resistance. On the other hand, the content of the other component is preferably less than 30% by mass, more preferably less than 20% by mass, and even more preferably less than 15% by mass.

[0094] (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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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. 14 The half-life of C is 5730 years. 14 C is decreasing regularly. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been fixed after more than 226,000 years have passed since atmospheric carbon dioxide was taken in and fixed by plants, etc., C was initially included in these as well. 14 All elements of C have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas are no longer viable. 14 It contains absolutely no element C. Therefore, chemical substances produced using these fossil fuels as raw materials also contain C. 14 It contains absolutely no element C.

[0101] on the other hand, 14C is continuously produced when cosmic rays undergo nuclear reactions in the atmosphere. Therefore, 14 In the Earth's atmospheric environment, carbon (C) is produced in a state where its decrease due to radioactive decay and its production through nuclear reactions are in equilibrium. 14 The amount of C is constant. Therefore, the amount of biomass resource-derived substances currently circulating in the environment 14 As mentioned above, the carbon concentration is approximately 1 × 10¹⁶ of the total carbon atoms. -12 These values ​​are approximately in mole percent. Therefore, the difference between these values ​​can be used to calculate the biomass ratio in a given compound.

[0102] this 14 C is typically measured as follows: Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 Perform measurement C). In the measurement, 14 As a modern standard reference for the concentration of C, the amount of cyclic carbon in nature as of 1950 14 The 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.

[0103] 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%.

[0104] Based on the 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.

[0105] (Filler) The rubber composition preferably contains a filler. The filler may include carbon black (CB) or silica. It is preferable that it contains carbon black. If the filler contains silica, it may further contain a silane coupling agent. The filler may further contain other fillers other than carbon black and silica. Examples of such fillers include aluminum hydroxide, calcium carbonate, alumina, clay, talc, etc., which have been commonly used in the tire industry. The filler may consist only of carbon black and silica, or only of carbon black.

[0106] Carbon Black The carbon black used is not particularly limited and includes N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw materials for carbon black may be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by thermal decomposition of waste tires. The manufacturing method for carbon black may be combustion such as the furnace method, hydrothermal carbonization (HTC), or thermal decomposition of methane such as the thermal black method. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbia Carbon Corporation, etc. Carbon black may be used alone or in combination of two or more types.

[0107] 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.

[0108] 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.

[0109] 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).

[0110] 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.

[0111] Recycled carbon black can be purchased from companies such as Strable Green Carbon and LD Carbon.

[0112] The nitrogen adsorption specific surface area (N2SA) of carbon black is not particularly limited, but from the viewpoint of obtaining sufficient reinforcement and good abrasion resistance, 20m 2 Preferably more than / g, 30m 2 More preferably than / g, 40m 2 More preferably than / g, 50m 2 More preferably than / g, 60m 2 A value exceeding / g is even more preferable. Furthermore, regarding the upper limit of N2SA, from the viewpoint of excellent dispersibility and low heat generation, 300m is preferred. 2 Less than / g is preferred. Note that the N2SA of recycled carbon black in this specification is the value measured by the method described above.

[0113] Carbon black content From the viewpoint of reinforcing properties, the carbon black content is preferably more than 20 parts by mass, more preferably more than 30 parts by mass, even more preferably more than 40 parts by mass, and even more preferably 50 parts by mass or more, per 100 parts by mass of rubber component. On the other hand, from the viewpoint of reinforcing properties, the carbon black content is preferably less than 100 parts by mass, more preferably less than 90 parts by mass, even more preferably less than 80 parts by mass, and even more preferably 70 parts by mass or less.

[0114] Silica The rubber composition may contain silica as a filler. The silica is not particularly limited, and common types 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 products containing silica may be used. Among these, hydrated silica prepared by a wet process is preferred because it has a high silanol group content. Silica may be used alone or in combination of two or more types.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] The nitrogen adsorption specific surface area (N2SA) of silica is preferably 50 m². 2 / g or more, more 100m 2 More than 150m / g 2 More than 170m / g 2 It is greater than / g. Also, the upper limit of N2SA in silica is not particularly limited, but preferably 350m 2 Less than 250ml / g, more preferably 250ml 2 Less than 200mg / g, more preferably 200mg 2 It is less than / g. Bringing it within the above range tends to improve cut resistance. Note that the N2SA of silica is the value measured by the method described above.

[0119] 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 fuel efficiency and ride comfort, it is preferably more than 1 part by mass, more preferably more than 5 parts by mass, more preferably more than 10 parts by mass, and even more preferably more than 20 parts by mass. Furthermore, from the viewpoint of silica dispersibility and processability, the amount of silica is preferably less than 60 parts by mass, more preferably less than 50 parts by mass, and even more preferably less than 40 parts by mass.

[0120] ≪Silane coupling agents≫ When silica is used, it is preferable to further include a silane coupling agent. The silane coupling agent is not particularly limited and includes, for example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl) trisulfide, bis(4-trimethoxysilylbutyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, and 3-trimethoxysilylpropyl-N,N-dimethylthio Examples include sulfide-based compounds such as carbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products from companies such as Evonik Industries, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Toray Dow Corning Co., Ltd. can be used. The silane coupling agent may be used alone or in combination of two or more types.

[0121] 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 the content within the above range tends to improve the dispersibility of silica.

[0122] (Bismaleimide compounds) This rubber composition may contain a bismaleimide compound. The inclusion of a bismaleimide compound improves the adhesion to metal cords. Furthermore, the bismaleimide compound can perform the same function as a vulcanizing agent. In addition to the bismaleimide compound, this rubber composition may also contain the vulcanizing agents described below.

[0123] As the bismaleimide compound, one or more compounds selected from the group consisting of compounds represented by the following chemical formulas can be used.

[0124] [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 11 ~R 14 Each of these independently represents a hydrogen atom, an alkyl group with 1 to 5 carbon atoms, or a -NH2 group or -NO2 group.

[0125] 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 11 ~R 14 Examples of alkyl groups having 1 to 5 carbon atoms, as shown, include methyl, ethyl, and propyl groups.

[0126] Suitable examples of bismaleimide compounds include, for example, N,N'-1,2-ethylenebismaleimide, N,N'-1,2-propylenebismaleimide, 4,4'-diphenylmethanebismaleimide, N,N'-m-phenylenebismaleimide, N,N'-(4,4-diphenyl-methane)bismaleimide, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, 2,2'-bis[4-(4-maleimidophenoxy)phenyl]propane, m-phenylenebis(methylene)bismaleimide, m-phenylenebis(methylene)biscitraconimide, and 1,1'-(methylenedi-4,1-phenylene)bismaleimide. Of these, 4,4'-diphenylmethanebismaleimide is preferred. Bismaleimide compounds may be used individually or in combination of two or more.

[0127] ≪Bismareimide compound content E≫ 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.

[0128] (cobalt) In this rubber composition, the cobalt content A is 0.03 parts by mass or less per 100 parts by mass of the rubber component. When this rubber composition contains cobalt, it is preferable that the cobalt is included in the rubber composition as a cobalt organic acid salt. Cobalt suppresses the formation of substances that cause adhesion layer failure, such as zinc sulfide and copper sulfide, and can improve the adhesion between the metal cord and the topping rubber. In addition, the cobalt organic acid salt also plays a role in crosslinking the metal cord and the topping rubber. Examples of cobalt organic acid salts include cobalt stearate, cobalt naphthenate, cobalt neodecanoate, and cobalt borate neodecanoate.

[0129] If the rubber composition contains a cobalt organic salt, its content is preferably 0.03 parts by mass or less, more preferably 0.02 parts by mass or less, and even more preferably 0.01 parts by mass or less, per 100 parts by mass of the rubber component, in terms of cobalt. The rubber composition does not need to contain cobalt.

[0130] (Other combination drugs) In addition to rubber components and fillers, the rubber composition may appropriately contain compounding agents commonly used in the tire industry, such as plasticizers, compatibilizers, processing aids, vulcanized rubber particles, waxes, stearic acid, zinc oxide, antioxidants, vulcanizing agents, and vulcanization accelerators.

[0131] Plasticizers 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 resin components, oils, 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.

[0132] ≪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.

[0133] ·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.

[0134] ·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.

[0135] 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.

[0136] • Dicyclopentadiene resins 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.

[0137] 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.

[0138] • 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.

[0139] • 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.

[0140] • 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.

[0141] • 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.

[0142] • 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.

[0143] From the viewpoint of processability and improved dispersibility between the rubber component and the filler, the softening point of the resin component is preferably 60°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, while 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.

[0144] When a resin component 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 part by mass, and even more preferably 1.5 parts by mass or more. On the other hand, the content is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 15 parts by mass.

[0145] Compatibilizer Compatibilizers are included to reduce the separation energy at the interface between rubber components and fillers, or between different rubber components, and to facilitate mutual mixing. There are no particular limitations on the compatibilizer, and those conventionally used in the tire industry can be used. Specific examples of compatibilizers include, for example, non-reactive compatibilizers such as ethylene-propylene-styrene copolymer, styrene-ethylene-butadiene block copolymer, styrene-methyl methacrylate block copolymer, ethylene-styrene graft copolymer, chlorinated polyethylene, mixtures of aromatic hydrocarbon resins and aliphatic hydrocarbon resins, and metal soaps of unsaturated fatty acids, as well as reactive compatibilizers such as maleic anhydride grafted polypropylene, styrene-maleic anhydride copolymer, ethylene-glycidyl methacrylate copolymer, and styrene graft copolymer onto ethylene-glycidyl methacrylate copolymer. Of these, ethylene-propylene-styrene copolymer is preferred. Compatibilizers may be used individually or in combination of two or more types.

[0146] ≪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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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. 1 When 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] Examples of animal oils include fish oil, beef tallow, or oleyl alcohol which can be derived from them.

[0155] The oil content per 100 parts by mass of rubber component is preferably more than 1 part by mass, more preferably more than 2 parts by mass, even more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. Furthermore, the content is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 10 parts by mass. Note that the oil content includes the amount of oil contained in the rubber component as an oil spreading oil, as well as the amount of oil contained in other components such as sulfur.

[0156] 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.

[0157] 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.

[0158] Processing aids Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. For example, commercially available processing aids from companies such as Schill+Seilacher and Performance Additives can be used. Processing aids may be used individually or in combination of two or more.

[0159] 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.

[0160] 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.

[0161] ≪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.

[0162] When wax is included, its 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 even 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 even more preferably less than 2.5 parts by mass.

[0163] ≪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.

[0164] ≪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 0.7 parts by mass, and even more preferably 1 part by mass or more, 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 5 parts by mass, and even more preferably less than 3 parts by mass.

[0165] Anti-aging agent While not particularly limited, the following are examples of anti-aging agents: 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-phenyl Examples include p-phenylenediamine-based antioxidants such as diamine (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 and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flexis, and others. The antioxidant may be used alone or in combination of two or more.

[0166] When an anti-aging agent 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 0.8 parts by mass, and even more preferably more than 1.0 part by mass. On the other hand, the content is preferably less than 7.0 parts by mass, more preferably less than 5.0 parts by mass, and even more preferably 3.0 parts by mass or less.

[0167] ≪Sulfurizing 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 are preferred. 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.

[0168] 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.

[0169] Known organic crosslinking agents can also be used as vulcanizing agents. The organic crosslinking agents are not particularly limited as long as they can form crosslinking chains other than polysulfide bonds, but examples include alkylphenol-sulfur chloride condensates, 1,6-hexamethylene-dithiosulfate sodium dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, and dicumyl peroxide, with 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane being preferred. These organic crosslinking agents can be commercially available from companies such as Taoka Chemical Industries, Ltd., Lanxess Corporation, and Flexis.

[0170] When a vulcanizing agent is included, its content per 100 parts by mass of rubber component is preferably more than 0.4 parts by mass, more preferably 0.5 parts by mass or more, and even more preferably 1.0 part by mass or more. On the other hand, the content is preferably less than 6.0 parts by mass, more preferably less than 4.0 parts by mass, and even more preferably less than 2.0 parts by mass. When the vulcanizing agent content is within the above range, an appropriate reinforcing effect tends to be obtained. Note that if the vulcanizing agent contains components other than sulfur, such as oil-treated sulfur, the vulcanizing agent content refers to the content of the sulfur component itself.

[0171] <<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, thiazole, sulfenamide, thiram, and guanidine are preferred, thiazole and sulfenamide are more preferred, and thiazole is even more preferred. For example, vulcanization accelerators manufactured and sold by Ouchi Shinko Chemical Industry Co., Ltd., Sanshin Chemical Industry Co., Ltd., etc., can be used. One or more vulcanization accelerators can be used in combination.

[0172] 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 (DCBS). Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole (MBT) or its salts, di-2-benzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, and 2-(2,6-diethyl-4-morpholinothio)benzothiazole. Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salts of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine. Examples of thiuram-based vulcanization accelerators include tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetramethylthiuram monosulfide (TMTM), dipentamethylenethiuram disulfide, and dipentamethylenethiuram tetrasulfide.

[0173] Examples of thiourea-based vulcanization accelerators include thiourea compounds such as thiocarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea, and dioltotrilthiourea, as well as N,N'-diphenylthiourea, trimethylthiourea, and N,N'-diethylthiourea. Examples of dithiocarbamate-based vulcanization accelerators include piperidinium pentamethylenedithiocarbamate (PPDC), zinc dimethyldithiocarbamate (ZnMDC), zinc diethyldithiocarbamate (ZnEDC), zinc dibutyldithiocarbamate (ZnBDC), zinc dibenzyldithiocarbamate (ZDBzC), zinc N-ethyl-N-phenyldithiocarbamate (ZnEPDC), zinc N-pentamethylenedithiocarbamate (ZnPDC), sodium dibutyldithiocarbamate (NaBDC), copper dimethyldithiocarbamate (CuMDC), iron dimethyldithiocarbamate (FeMDC), and tellurium diethyldithiocarbamate (TeEDC).

[0174] 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 8.0 parts by mass, more preferably less than 7.0 parts by mass, and even more preferably less than 6.0 parts by mass. When the content of the vulcanization accelerator is within the above range, fracture strength and elongation tend to be ensured.

[0175] <Rubber composition constituting the internal components> The rubber compositions constituting the internal components can be manufactured by conventional methods. That is, the rubber compositions can be obtained by kneading rubber components with compounding agents. The descriptions of the rubber components and compounding agents are similar to those given for the rubber compositions constituting the belt topping rubber. Regarding the rubber compositions constituting the inner liner and insulation among the internal components, the following descriptions apply.

[0176] <Rubber composition that makes up the inner liner> The rubber composition constituting the inner liner will be described below. In this specification, the rubber composition constituting the inner liner may also be referred to as the rubber composition for the inner liner.

[0177] (Rubber component) The rubber component preferably includes butyl rubber.

[0178] ≪Butyl rubber≫ Examples of butyl rubbers include non-halogenated butyl rubber (regular butyl rubber, IIR); halogenated butyl rubbers such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR) (X-IIR); and copolymers of isobutylene and p-alkylstyrene. Among these, halogenated butyl rubber is preferred, and brominated butyl rubber and chlorinated butyl rubber are more preferred, as they offer a good balance of improved sheet processability and air barrier properties, as well as the effects of the present invention. One or more types of butyl rubber can be used.

[0179] Examples of p-alkylstyrene constituting the copolymer of isobutylene and p-alkylstyrene include p-methylstyrene. The copolymer of isobutylene and p-alkylstyrene may be halogenated. The halogenated site may be an isobutylene unit or a p-alkylstyrene unit, but it is preferably a p-alkylstyrene unit, and more preferably an alkyl group of a p-alkylstyrene unit.

[0180] In addition to regular butyl rubber (butyl rubber other than recycled butyl rubber), recycled butyl rubber can also be used in combination. Since recycled butyl rubber usually has a high content of unhalogenated butyl rubber (regular butyl rubber), using it in combination with halogenated butyl rubber ensures good air barrier properties and vulcanization speed. Recycled butyl rubber may be used alone or in combination of two or more types.

[0181] Examples of butyl rubbers that can be used include products from ExxonMobil, ENEOS Material Corporation, Arlanxeo, JSR Corporation, and Nippon Butyl Co., Ltd.

[0182] ≪Butyl rubber content≫ The butyl rubber content in 100% by mass of the rubber component is preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, and even more preferably 90% by mass or more, from the viewpoint of sufficient air barrier properties. The butyl rubber content may be 100% by mass. On the other hand, the content is not particularly limited, but from the viewpoint of compatibility with moldability, it can be, for example, 100% by mass or less, less than 100% by mass, less than 97% by mass, less than 95% by mass, less than 93% by mass, or 91% by mass or less.

[0183] <<Other rubber components>> Other rubber components besides butyl rubber include, for example, diene rubbers such as isoprene rubber (IR rubber), butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and polynorbornene rubber, as well as non-diene rubbers such as hydrogenated nitrile rubber (HNBR), ethylene propylene rubber, silicone rubber, polyethylene chloride rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. Of these, diene rubbers are preferred, and among them, isoprene rubber is preferred from the viewpoint of improving adhesion and bonding with adjacent tire components. Other rubber components may be used individually or in combination of two or more.

[0184] Examples of isoprene-based rubbers include isoprene rubber (IR), natural rubber (NR), and modified natural rubber, with NR being the preferred choice. Examples of modified natural rubbers include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. As for NR, common types used in the tire industry, such as SIR20, RSS#3, and TSR20, can be used.

[0185] When other rubber components are included, their content in 100% by mass of the rubber components can be, for example, more than 1% by mass, preferably more than 3% by mass, more preferably more than 5% by mass, even more preferably more than 8% by mass, and even more preferably 10% by mass or more, from the viewpoint of moldability. On the other hand, from the viewpoint of air permeability resistance, the content can be 30% by mass or less, preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0186] (Water permeability inhibiting filler) Examples of water permeability-inhibiting fillers include plate-like clay minerals, recycled carbon black, and rubber powder. Plate-like clay minerals do not have to be perfectly plate-like; for example, they may be partially or entirely bent or twisted.

[0187] Examples of platy clay minerals include kaolin, serpentine, pyrophyllite, talc, mica, chlorite, smectite, and vermiculite. More specifically, examples include kaolinite, dickite, nacrite, halloysite, chrysotile, lizardite, antigorite, pyrophyllite, talc, kerolite, willemsite, vimelite, minnesotaite, mica, clinochlore (Mg chlorite), FeMg chlorite, chamosite (Fe chlorite), nimite, benanthite, donbasite, sudoite, cuquerite, montmorillonite, beidelite, nontronite, savonite, hectorite, and stevensite. These can be used individually or in combination of two or more.

[0188] The moisture permeability-inhibiting filler preferably has a particle size ratio (hereinafter also referred to as "aspect ratio") within a predetermined range. For example, from the viewpoint of the effects of the present invention, the average aspect ratio of the moisture permeability-inhibiting filler is preferably 3 or more, more preferably 6 or more, and even more preferably 10 or more. On the other hand, there is no particular upper limit to the average aspect ratio, but for example, it is 1000 or less.

[0189] From the viewpoint of improving moisture permeability inhibition, the average particle size of the moisture permeability inhibiting filler is preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 5 μm or more. On the other hand, the average particle size is preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 100 μm or less.

[0190] The average thickness of the moisture permeability-inhibiting filler is preferably 100 μm or less, and more preferably 50 μm or less, from the viewpoint of not lowering the aspect ratio too much.

[0191] The average thickness, average particle size, and average aspect ratio of the moisture permeability-inhibiting filler can be determined by microscopic observation. Specifically, these can be calculated as the average value of any 100 objects within the field of view.

[0192] Furthermore, in this embodiment, recycled carbon black or rubber powder can be used as a moisture permeation-inhibiting filler.

[0193] The same explanation given for rubber compositions for belt topping rubber can be applied to recycled carbon black.

[0194] The description of vulcanized rubber particles in rubber compositions for belt topping rubber can be similarly applied to rubber powder.

[0195] As the moisture permeation inhibiting filler, at least one selected from kaolin, talc, mica, recycled carbon black, and rubber powder is preferred.

[0196] ≪Content of water permeability-inhibiting filler B≫ From the viewpoint of improving moisture permeability inhibition, the content B of the moisture permeability inhibiting filler is preferably more than 5 parts by mass, more preferably more than 8 parts by mass, even more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, per 100 parts by mass of resin. On the other hand, the content is more preferably 90 parts by mass or less, even more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less.

[0197] (Filler) This rubber composition preferably contains a filler. The filler may include carbon black and silica. It is preferable that it contains carbon black. If the filler contains silica, it may further contain a silane coupling agent. The filler may further contain other fillers other than carbon black and silica. A description of each component that may constitute the filler is as follows, and the description of the rubber composition constituting the belt topping rubber is also applicable.

[0198] ≪Carbon Black Content C≫ The carbon black content C is, for example, more than 20 parts by mass, preferably 30 parts by mass or more, more preferably 35 parts by mass or more, and even more preferably 40 parts by mass or more, per 100 parts by mass of the rubber component. On the other hand, the total content is preferably less than 80 parts by mass, more preferably less than 60 parts by mass, even more preferably less than 50 parts by mass, and even more preferably 45 parts by mass or less. When the carbon black content is within the above range, sufficient reinforcing properties tend to be obtained.

[0199] Furthermore, the same explanation given for the rubber composition constituting the belt topping rubber can be applied to carbon black.

[0200] (Other compounding agents) The rubber composition for the inner liner preferably contains a compatibilizer. It is also preferable that it contains a phenolic resin.

[0201] Compatibilizer The description of the compatibilizer is the same as the description given for the belt topping rubber composition. Suitable compatibilizers used in this rubber composition include, for example, ethylene-propylene-styrene copolymer, styrene-ethylene-butadiene block copolymer, styrene-methyl methacrylate block copolymer, ethylene-styrene graft copolymer, styrene-maleic anhydride copolymer, ethylene-glycidyl methacrylate copolymer, and styrene graft copolymer onto ethylene-glycidyl methacrylate copolymer. Of these, ethylene-propylene-styrene copolymer is preferred. By containing a compatibilizer, this rubber composition can suppress water permeability and also suppress the formation of large voids.

[0202] The compatibilizer content is not particularly limited, but considering the ability to suppress moisture permeation, for example, more than 2 parts by mass, more than 3 parts by mass, and even more than 4 parts by weight per 100 parts by mass of rubber component is preferred. On the other hand, less than 15 parts by mass is preferred, less than 12 parts by mass is preferred, and less than 10 parts by weight is even more preferred.

[0203] Phenolic resins The rubber composition for the inner liner preferably contains a phenolic resin. The description of the rubber composition constituting the belt topping rubber can be applied similarly to that of the phenolic resin. It is believed that the inclusion of a phenolic resin improves adhesion to other tire components.

[0204] The phenolic resin content is preferably 0.5 parts by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of the rubber component. On the other hand, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less.

[0205] For compounding agents other than those mentioned above, the same explanation given for the rubber composition constituting the belt topping rubber can be applied.

[0206] <Rubber composition constituting the insulation> The components of the rubber composition constituting the insulation will be described below. In this specification, the rubber composition constituting the insulation may also be referred to as the rubber composition for insulation.

[0207] (Rubber component) The following is a description of the rubber components, and the same description as given for the rubber composition constituting the belt topping rubber can also be applied. The rubber composition constituting the insulation contains a rubber component comprising at least one selected from isoprene rubber (IR rubber), styrene-butadiene rubber (SBR), and butadiene rubber (BR). In this case, the rubber component may include rubber components other than IR rubber, SBR, and BR. Alternatively, the rubber component may consist only of IR rubber, SBR, and BR.

[0208] The content of IR-type rubber in 100% by mass of rubber components is, for example, more than 20% by mass, preferably more than 30% by mass, more preferably more than 40% by mass, and even more preferably 50% by mass or more. On the other hand, the content is, for example, 100% by mass or less, preferably less than 90% by mass, and more preferably less than 80% by mass.

[0209] When the rubber component contains BR, the BR content in 100% by mass of the rubber component is, for example, more than 5% by mass, preferably more than 10% by mass, more preferably more than 20% by mass, and even more preferably more than 25% by mass. On the other hand, the content is, for example, 100% by mass or less, preferably less than 90% by mass, and more preferably less than 80% by mass.

[0210] When the rubber component contains SBR, the SBR content in 100% by mass of the rubber component is, for example, more than 5% by mass, preferably more than 10% by mass, more preferably more than 20% by mass, and even more preferably more than 25% by mass. On the other hand, the content is, for example, 100% by mass or less, preferably less than 90% by mass, and more preferably less than 80% by mass.

[0211] <Moisture permeability inhibiting filler> This rubber composition contains a water permeability-inhibiting filler. The description of the water permeability-inhibiting filler is similar to the description of the rubber composition constituting the inner liner.

[0212] <Filler> The filler may contain carbon black (CB) and silica. It is preferable that it contains carbon black. The carbon black may also contain recycled carbon black. If the filler contains silica, it may further contain a silane coupling agent. The filler may further contain other fillers besides carbon black and silica. The descriptions of each component that may constitute the filler are similar to the descriptions given for the rubber composition constituting the belt topping rubber.

[0213] <Compatibilizer> The rubber composition for insulation preferably contains a compatibilizer. The description of the compatibilizer is similar to the description given for the rubber composition constituting the inner liner.

[0214] <Phenolic resin> The rubber composition for insulation preferably contains a phenolic resin. The description of the phenolic resin is similar to the description of the rubber composition constituting the inner liner.

[0215] For compounding agents other than those mentioned above, the same explanation given for the rubber composition constituting the belt topping rubber can be applied.

[0216] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. As a method for obtaining the formulations according to this embodiment from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0217] <Manufacturing> The rubber compositions according to this embodiment can all be manufactured by known methods. For example, they can be manufactured by kneading each of the above components using a rubber kneading device such as an open roll or closed kneader (Banbury mixer, kneader, etc.).

[0218] (Manufacturing of rubber compositions for belt topping rubber and rubber compositions for internal components) Rubber compositions can be manufactured by known methods. For example, they can be manufactured by kneading each of the above components using rubber kneading equipment such as an open roll kneader 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 mixture 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.

[0219] (Manufacturing of belt plies and belts) A belt ply can be manufactured by covering metal cords, arranged at predetermined intervals using a calender roll or the like, with the rubber composition for belt topping rubber obtained above. The material of the metal cord is not particularly limited, but steel cord is preferred. A belt is constructed using one or more of these belt plies.

[0220] 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.

[0221] (Tire manufacturing) Each of the rubber compositions obtained above can be extruded in the unvulcanized stage to conform to the desired shape of a tire component, thereby forming unvulcanized internal components such as inner liners and insulation. The unvulcanized internal components such as inner liners and insulation obtained in this way, along with the belt obtained above, are bonded together with other tire components on a tire molding machine using a conventional method to form an unvulcanized tire. At this time, the belt is made to have a predetermined structure as necessary. The tire according to this embodiment can be manufactured by heating and pressurizing the thus obtained unvulcanized tire in a vulcanizing machine. The vulcanization conditions are not particularly limited, and for example, a method of vulcanization at 150 to 200°C for 10 to 40 minutes can be used.

[0222] <Application> The tire according to this embodiment can be used for any application, including passenger car tires, large passenger car tires, large SUV tires, racing tires, motorcycle tires, heavy-duty tires, and run-flat tires. A passenger car tire refers to a tire intended for use on a four-wheeled vehicle with a maximum load capacity of less than 1400 kg. A heavy-duty tire refers to a tire with a maximum load capacity of 1400 kg or more. Furthermore, in this specification, the tire can be used as an all-season tire, a summer tire, or a winter tire such as a studless tire. [Examples]

[0223] The following examples (case studies) are shown as preferred for implementation, but the scope of the present invention is not limited to these examples. In accordance with each table, inner liners, belts, and tires having tire structures obtained using the various chemicals shown below were examined, and the results calculated based on the evaluation method described below are shown at the bottom of each table.

[0224] <Various chemicals> The various chemicals used in the examples and comparative examples are summarized below. NR:TSR20 (Natural Rubber) Butyl rubber: Bromobutyl 2222 (brominated butyl rubber) manufactured by ExxonMobil Carbon Black 1 (CB1): Manufactured by Tokai Carbon Co., Ltd. (N2SA: 27m 2 / g, primary particle diameter 62nm, ash content: 1.0% by mass or less) Carbon Black 2 (CB2): Dia Black H (N330, N2SA) manufactured by Mitsubishi Chemical Corporation: 42m 2 / g, ash content: 1.0% by mass or less) Moisture permeation inhibiting filler: Polyfil DL (Kaolin) manufactured by KaMin, median particle size 3.2 μm, BET specific surface area 15 m². 2 / g) Cobalt stearate: Cost-F (cobalt content 9.5% by mass) manufactured by Dainippon Ink and Chemicals, Inc. Bismaleimide: BMI-1000 (4,4'-diphenylmethanebismaleimide) manufactured by Yamato Chemical Industries, Ltd. Anti-aging agent: Nocrack RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: Beads of stearic acid manufactured by NOF Corporation Resin: Durez 19900 (solid phenol novolac resin, softening point: 90°C) manufactured by Sumitomo Bakelite Co., Ltd. Compatibilizer: Promix 400 (ethylene-propylene-styrene copolymer) manufactured by Flow Polymers. Zinc oxide: Zinc oxide No. 1 manufactured by Ouchi Shinko Chemical Co., Ltd. Oil: Diana Process NH-70S (aroma-type process oil) manufactured by Idemitsu Kosan Co., Ltd. Sulfur 1: HK-200-5 manufactured by Hosoi Chemical Industry Co., Ltd. (Oil content: 5% by mass) Sulfur 2: M95 manufactured by Nippon Dry Distillation Industry Co., Ltd. (Oil content: 20% by mass) Vulcanization accelerator 1: Noxellar DM-P (benzothiazole disulfide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noxellar NS (Nt-butyl-2-benzothiazolyl disulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0225] <Examples and Comparative Examples> According to the formulation shown in Table 1, all chemicals except sulfur and vulcanization accelerator are mixed in a 1.7 L Banbury mixer for 5 minutes until the discharge temperature reaches 160°C to obtain a mixture. Next, sulfur and vulcanization accelerator are added to the mixture and mixed in a twin-screw open roll for 4 minutes until the temperature reaches 105°C to obtain an unvulcanized rubber composition for belt topping rubber. The obtained unvulcanized rubber composition is used to coat steel cord (filament diameter: 0.30 mm) to obtain a steel cord-rubber composite.

[0226] According to the formulation shown in Table 1, all chemicals except sulfur and vulcanization accelerator are mixed in a 1.7 L Banbury mixer for 5 minutes until the discharge temperature reaches 130°C to obtain a mixture. Next, sulfur and vulcanization accelerator are added to the mixture and mixed in a twin-screw open roll for 4 minutes until the temperature reaches 105°C to obtain an unvulcanized rubber composition for the inner liner. The mixture is then extruded into the shape of the base tread or sidewall using an extruder equipped with a die of a predetermined shape to obtain an unvulcanized inner liner component.

[0227] One of the resulting steel cord-rubber composites is used as a belt ply and bonded together with an unvulcanized inner liner and other tire components to produce an unvulcanized tire. Each test tire (tire size: 195 / 65R15) is then manufactured by press vulcanization at 160°C for 20 minutes.

[0228] <Spray resistance> Each test tire is immersed in room temperature water for 300 hours to allow it to deteriorate. From the deteriorated tire, a belt is cut out from the tire, along with the steel cord and topping rubber, to a width of 25 mm and a length of 200 mm. The prepared sample is subjected to a 90-degree peel test at a tensile speed of 100 mm / min according to JIS K 6854, and the peel resistance force (N) is measured. The measured peel resistance force is expressed as an index, with the peel resistance force of Comparative Example 4 set to 100. A higher value indicates better peel suppression.

[0229] [Table 1]

[0230] <Embodiment> Examples of embodiments of the present invention are shown below.

[0231] [1] A tire comprising a belt and an internal member disposed radially inward of the belt, The belt includes at least one belt ply having a metal cord and topping rubber covering the metal cord. When the cobalt content (parts by mass) with respect to 100 parts by mass of the rubber component in the rubber composition constituting the topping rubber is A, A is 0.03 parts by mass or less. The inner member is made of a rubber composition containing a moisture permeation suppressing filler. When the content (parts by mass) of the moisture permeation suppressing filler with respect to 100 parts by mass of the rubber component in the rubber composition constituting the inner member is B, a tire in which A and B satisfy the following formula (1). (1) B / (A + 5)>1 Here, the right side of formula (1) is preferably 1.5, more preferably 2. [2] The tire according to [1] above, wherein the right side of formula (1) is 3, preferably 4. [3] The tire according to [1] above, wherein the right side of formula (1) is 5. [4] When the thickness (mm) of the belt is T and the thickness (mm) of the inner member is L, a tire according to any one of [1] to [3] above, wherein T, L, and B satisfy the following formula (2). (2) T×L×B>10 [5] The tire according to [4] above, wherein the right side of formula (2) is 20, preferably 30, more preferably 50. [6] The tire according to any one of [1] to [5] above, wherein the rubber composition constituting the inner member contains a rubber component containing butyl rubber. [7] The tire according to any one of [1] to [6] above, wherein the rubber composition constituting the topping rubber contains a rubber component containing isoprene rubber. [8] The tire according to any one of the above [1] to [7], wherein the rubber composition constituting the internal member contains 70% by mass or more, preferably 75% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, even more preferably 90% by mass or more of butyl rubber in 100% by mass of the rubber component, and also contains 100% by mass or less, preferably less than 100% by mass, more preferably less than 97% by mass, even more preferably less than 95% by mass, even more preferably less than 93% by mass, even more preferably 91% by mass or less of a moisture permeability inhibiting filler per 100 parts by mass of the rubber component, and also contains 70 parts by mass or less, preferably 60 parts by mass or less. [9] The tire according to any one of the above [1] to [8], wherein the rubber composition constituting the topping rubber contains 80% by mass or more, preferably 90% by mass or more, and 100% by mass or less of isoprene-based rubber, and A is 0.02 parts by mass or less, preferably 0.01 parts by mass or less.

[10] The tire according to any one of the above items [1] to [9], wherein the rubber composition constituting the internal member has a carbon black content (parts by mass) of C relative to 100 parts by mass of rubber component, and B, C, and L satisfy the following formula (3). (3) B / (B+C) × L < 1 Here, the right-hand side of equation (3) is preferably 0.8, more preferably 0.6, and even more preferably 0.5.

[11] The tire according to any one of the above [1] to

[10] , wherein the rubber composition constituting the topping rubber contains a bismaleimide compound, and when the content (parts by mass) of the bismaleimide compound per 100 parts by mass of the rubber component is E, A, E, and T satisfy the following formula (4). (4)(A+E) / T>1 Here, the right-hand side of equation (4) is preferably 1.2, more preferably 1.5, even more preferably 1.7, and even more preferably 1.9.

[12] The tire according to any one of the above [1] to

[11] , wherein the moisture permeability-inhibiting filler comprises at least one selected from the group consisting of kaolinite, dickite, naclite, halloysite, chrysotile, lizardite, antigolite, pyrophyllite, talc, kerolite, willemsite, vimelite, minnesotaite, mica, chlorite, smectite, vermiculite, saponite, hectorite, stevensite, montmorillonite, byderite, nontronite, boehmite, hydrotalcite, recycled carbon black, and rubber powder.

[13] The tire according to any one of the above [1] to

[12] , wherein the metal cord includes a steel cord having a plating layer of binary copper and zinc, ternary copper, zinc and cobalt, or ternary copper, zinc and iron. [Explanation of Symbols]

[0232] 1 tire 2 Cap Tread 3 Base Tread 4 bands 5 belts 6 Carcass 7 Insulation 8 Inner Liner CL tire centerline Thickness of L1 inner liner T-belt thickness

Claims

1. A tire comprising a belt and an internal member positioned radially inward of the belt, The belt comprises at least one belt ply having a metal cord and a topping rubber covering the metal cord, and when A is the cobalt content (parts by mass) per 100 parts by mass of rubber component in the rubber composition constituting the topping rubber, A is 0.03 parts by mass or less. The internal component is made of a rubber composition containing a moisture permeability-inhibiting filler. A tire in which A and B satisfy the following formula (1), where B is the content (parts by mass) of the moisture permeability-inhibiting filler in the rubber composition constituting the internal member relative to 100 parts by mass of the rubber component. (1) B / (A+5)>1

2. The tire according to claim 1, wherein the right-hand side of equation (1) is 3.

3. The tire according to claim 1, wherein the right-hand side of equation (1) is 5.

4. The tire according to any one of claims 1 to 3, wherein T is the thickness of the belt (mm) and L is the thickness of the internal member (mm), and T, L, and B satisfy the following formula (2). (2) T × L × B > 10

5. The tire according to claim 4, wherein the right-hand side of equation (2) is 20.

6. The tire according to any one of claims 1 to 3, wherein the rubber composition constituting the internal member contains a rubber component including butyl rubber.

7. The tire according to any one of claims 1 to 3, wherein the rubber composition constituting the topping rubber includes a rubber component containing isoprene-based rubber.

8. The tire according to any one of claims 1 to 3, wherein the rubber composition constituting the internal member contains 70% to 100% by mass of butyl rubber in 100% by mass of the rubber component, and contains 10 to 70 parts by mass of a moisture permeability inhibiting filler per 100 parts by mass of the rubber component.

9. The tire according to any one of claims 1 to 3, wherein the rubber composition constituting the topping rubber contains 80% to 100% by mass of isoprene-based rubber in 100% by mass of the rubber component, and A is 0.02 parts by mass or less.

10. The tire according to any one of claims 1 to 3, wherein the rubber composition constituting the internal member, when the content (parts by mass) of carbon black relative to 100 parts by mass of rubber component is C, B, C, and L satisfy the following formula (3). (3) B / (B+C)×L<1

11. The tire according to any one of claims 1 to 3, wherein the rubber composition constituting the topping rubber contains a bismaleimide compound, and when the content (parts by mass) of the bismaleimide compound per 100 parts by mass of the rubber component is E, A, E, and T satisfy the following formula (4). (4) (A+E) / T>1

12. The tire according to any one of claims 1 to 3, wherein the moisture permeability-inhibiting filler includes at least one selected from the group consisting of kaolinite, dickite, nacrite, halloysite, chrysotile, lizardite, antigorite, pyrophyllite, talc, kerolite, willemsite, vimelite, minnesotaite, mica, chlorite, smectite, vermiculite, saponite, hectorite, stevensite, montmorillonite, byderite, nontronite, boehmite, hydrotalcite, recycled carbon black, and rubber powder.

13. The tire according to any one of claims 1 to 3, wherein the metal cord includes a steel cord having a plating layer of binary plating of copper and zinc, ternary plating of copper, zinc and cobalt, or ternary plating of copper, zinc and iron.

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