Tire

Abstract

The purpose of the present invention is to improve the durability of a tire. A tire provided with a tread portion and a belt layer, characterized in that the tread portion has at least one rubber layer, and the belt layer has steel cords and topping rubber covering the steel cords. The tread rubber layer constituting the tread of the tread portion and the topping rubber are each configured from a rubber composition containing a rubber component and a filler, the topping rubber has a complex elastic modulus (70 DEG C E * 1) of 15.0 MPa or less at 70 DEG C, and when the maximum load capacity of the tire is WL (kg) and the tan [delta] of the topping rubber at 70 DEG C is 70 DEG C tan [delta] 1, the maximum load capacity of the tire is WL (kg), and the maximum load capacity of the tire is WL (kg). WL and 70 DEG C tan [delta] 1 satisfy formula (1). 9.33 * 10 <-5 > * WL-70 DEG C tan delta 1gt; 0.023... (1).

Description

Technical Field

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

[0002] People are seeking a tire with excellent durability that can be used for a longer period of time while suppressing the frequency of tire replacement. Patent Document 1 discloses a steel element for reinforcing a rubber product and a reinforced rubber product comprising the steel element and a rubber compound, wherein the steel element is a steel element covered with a covering of a ternary or quaternary alloy of copper-m-zinc. [Prior art literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Publication No. 2015-511998 Summary of the invention [Problems to be solved by the invention]

[0004] In Patent Document 1, when the rubber article is used as a tire, the specific degree of durability is not clear, and there is still room for improvement.

[0005] An object of the present invention is to improve the durability performance of a tire.

Methods to solve the problem

[0006] The present invention relates to a tire, which is a tire having a tread portion and a belt layer, characterized in that the tread portion has at least one rubber layer, the belt layer has steel cords and a topping rubber covering the steel cords, a running surface rubber layer constituting the tread of the tread portion and the topping rubber are respectively composed of a rubber composition containing a rubber component and a filler, the topping rubber has a complex elastic modulus (70°C E*1) at 70°C of 15.0 MPa or less, and the maximum load capacity of the tire is set to W L (kg), when the tanδ of the topping rubber at 70°C is set to tanδ1 at 70°C, W L and tanδ1 at 70℃ satisfies the following formula (1), 9.33×10 -5 ×W L -70℃tanδ1>0.023…(1). Effects of the Invention

[0007] According to the present invention, the durability performance of a tire can be improved.

[0008]

Figure 1

Figure 2

Figure 3

Explanation of symbols

[0009] A tire according to one embodiment of the present invention is a tire having a tread portion and a belt layer, characterized in that the tread portion has at least one rubber layer, the belt layer has steel cords and a topping rubber covering the steel cords, a running surface rubber layer constituting the tread of the tread portion and the topping rubber are respectively composed of a rubber composition containing a rubber component and a filler, the topping rubber has a complex elastic modulus (70°C E*1) at 70°C of 15.0 MPa or less, and the maximum load capacity of the tire is set to W L (kg), when the tanδ of the topping rubber at 70°C is set to tanδ1 at 70°C, W L and tanδ1 at 70℃ satisfies the following formula (1), 9.33×10 -5 ×W L -70℃tanδ1>0.023…(1).

[0010] Although not wishing to be bound by theory, the reason why the durability of the tire of the present invention is improved is considered to be as follows.

[0011] It is believed that when the virtual volume (air capacity) of the tire increases, the maximum load capacity W of the tire increases. L Increase, can suppress the deformation of tread and belt layer. Therefore, it can be considered that W L When W is smaller, the deformation at the belt layer becomes relatively larger, so by making the heat generation (70℃ tanδ1) of the topping rubber covering the belt layer smaller, the durability of the tire can be easily improved. On the other hand, it is believed that when the heat generation (70℃ tanδ1) of the topping rubber is higher, by increasing W L , suppressing the deformation of the tread and belt layers can easily improve the durability of the tire.

[0012] Furthermore, it is considered that by setting the complex elastic modulus (70°C E*1) of the topping rubber at 70°C to 15.0 MPa or less, it is possible to suppress the occurrence of strain concentration in the belt layer due to the extremely high rigidity of the belt layer.

[0013] It is considered that the above-mentioned synergistic effect can achieve a noteworthy effect of being able to more effectively improve the durability performance of the tire.

[0014] The filler contained in the rubber composition constituting the topping rubber preferably contains silica.

[0015] It is considered that by mixing silica into the topping rubber, the rigidity of the topping rubber in a micro-deformation region can be reduced, thereby improving the adhesion with the steel cord topping rubber and further improving the durability of the tire.

[0016] The filler contained in the rubber composition constituting the topping rubber preferably contains regenerated carbon black.

[0017] Regenerated carbon black has a wider particle size distribution than ordinary carbon black. Therefore, it is believed that compared with mixing ordinary carbon black, it is possible to suppress the movement of the polymer and the heating of the topping rubber even with respect to a wide range of various frequencies input from the road surface, thereby further improving the durability of the tire.

[0018] The rubber composition constituting the cap rubber layer preferably contains 20 parts by mass or less of carbon black per 100 parts by mass of the rubber component. The cap rubber layer preferably has a tan δ at 30°C (tan δ2 at 30°C) of 0.16 or less.

[0019] By reducing the heat generation of the running surface rubber layer by reducing the carbon black content in the running surface rubber layer, the temperature of the tire surface can be suppressed to a relatively low level. In addition, it is believed that by suppressing the heat generation of the surface components, it becomes easier to release the heat generated in the tire internal components such as the belt layer, and the durability of the tire is further improved.

[0020] When the tan δ of the cap rubber layer at 30°C is 30°C tan δ2 and the tan δ of the cap rubber layer at 0°C is 0°C tan δ2, 0°C tan δ2 / 30°C tan δ2 is preferably larger than 2.3.

[0021] By setting 0℃tanδ2 / 30℃tanδ2 to the above range, the running surface rubber layer can be kept in a soft state until the low temperature region, so that in a wide temperature range, the strain concentration on the tire internal parts due to the deformation caused by rotation can be suppressed. As a result, it is believed that the mechanical fatigue degradation caused by the deformation of the topping rubber is suppressed, and the durability of the tire is further improved.

[0022] The total amount of styrene in the rubber component constituting the cap rubber layer is preferably 15% by mass or less.

[0023] It is considered that by setting the total styrene amount in the rubber component constituting the cap rubber layer within the above-mentioned range, even if styrene-butadiene rubber, which generally has a higher glass transition temperature than isoprene-based rubber or butadiene rubber, is mixed, the complex elastic modulus can be reduced in a wider temperature range, particularly in a low temperature range, and thus the cap rubber layer can be kept in a soft state.

[0024] From the viewpoint of facilitating the effect of the present invention, W L Preferably, it is 400 or more.

[0025] The steel cord is preferably a monofilament cord of a single wire.

[0026] It is considered that by using the steel cord as an untwisted monofilament cord, the rigidity of the steel cord is increased, and the deformation amount of the belt layer can be suppressed.

[0027] From the viewpoint of the effect of the present invention, the cross-sectional area of ​​the steel cord is S (mm 2 ), when the number of the steel cords per 50 mm width in a direction perpendicular to the longitudinal direction of the steel cord is set to E, S×E is preferably greater than or equal to 1.0 and less than or equal to 25.

[0028] In the rubber composition constituting the topping rubber, when the content of silica per 100 parts by mass of the rubber component is represented by Y (parts by mass), Y / (S×E) is preferably 0.10 or more.

[0029] It is believed that by mixing silica into the topping rubber, the rubber becomes acidic, and the zinc oxide coating on the plated surface of the steel cord becomes easy to peel off, thereby efficiently forming an adhesive layer. Here, it is believed that by setting Y / (S×E) to the above range, the advantage of forming the adhesive layer due to acidification is greater than the enlargement of the adhesive layer due to the precipitation of copper, and good adhesive performance can be obtained.

[0030] The steel cord preferably has a 3-component plating layer consisting of copper, zinc and cobalt.

[0031] It is considered that by adopting ternary plating, cobalt, which has a higher ionization tendency than copper, is preferentially eluted, and thus enlargement of the adhesive layer due to elution of copper after wet heat degradation can be suppressed, and high adhesive strength can be maintained.

[0032] When the weight of the tire is G (kg), G / W L It is preferably 0.060 or less.

[0033] Think: By G / W LBy setting the above range, the rubber amount of the entire tire is reduced, which can suppress the total heat generation caused by deformation. At the same time, by ensuring a sufficient air volume for compliance, the total heat generation caused by deformation can be synergistically suppressed, thereby achieving a high degree of both durability performance and low fuel consumption performance.

[0034] <Definition> The "tread portion" is the portion that forms the contact surface of the tire. When the tire has components in the radial cross-section that include a belt layer or belt reinforcement layer, a carcass layer, etc. formed by steel or textile materials to form the tire skeleton, it is a component that is radially outside of these components.

[0035] The "belt layer" is a layer located radially outside the tire than the carcass layer, which is equivalent to multiple working layers of internal reinforcement materials that are inclined at about 18 to 30 degrees relative to the tire circumference and overlapped in reverse, or a circumferential belt layer in which the internal reinforcement materials are oriented at an angle of ±10 degrees relative to the tire circumference.

[0036] The “normal state” refers to an unloaded state in which the wheel is assembled to a normal rim and filled with air at a normal internal pressure.

[0037] Regarding the "dimensions of each part of the tire", unless otherwise specified, the "dimensions of each part of the tire" appearing on the outer surface of the tire are specific values ​​under the normal state. On the other hand, the "dimensions of each part of the tire" existing inside the tire or in the tire cross-section are, for example: the tire is cut along a plane including the tire rotation axis, and the cut tire piece is kept in a state of maintaining the rim width of the normal rim.

[0038] "Regular rim" means a rim specified for each tire in a specification system including the specifications based on which the tire is based, for example, in the case of JATMA (Japan Automobile Tire Association), it means a standard rim with an applicable size listed in the "JATMA Year Book", in the case of ETRTO (The European Tyre and Rim Technical Organization), it means a "Measuring Rim" listed in the "STANDARDS MANUAL", and in the case of TRA (The Tire and Rim Association, Inc.), it means a "Design Rim" listed in the "Year Book". JATMA, ETRTO, and TRA are referred to in this order, and when referring to applicable sizes, the applicable sizes are followed. In addition, in the case of a tire not specified in the aforementioned specifications, it means a rim with the narrowest rim width among the rims with the minimum diameter that can be assembled on the rim and can maintain the internal pressure (i.e., no air leakage occurs between the rim and the tire).

[0039] "Regular internal pressure" means the air pressure specified for each tire in each specification system including the specifications on which the tire is based. If it is JATMA, it is "maximum air pressure", if it is ETRTO, it is "inflation pressure (INFLATIONPRESSURE)", if it is TRA, it is the maximum value recorded in the table "Tire load limits at various cold inflation pressures (TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES)", and in the same way as regular rims, it is referenced in the order of JATMA, ETRTO, and TRA. When referencing, if there is an applicable size, the specification is followed. In addition, in the case of a tire not specified in the above-mentioned specifications, it refers to the regular internal pressure (including 250 kPa or more) of other tire sizes (including tires specified in the specifications) recorded with the above-mentioned regular rim as the standard rim. When multiple regular internal pressures of 250 kPa or more are recorded, it refers to the minimum value among them.

[0040] The "tire weight G (kg)" refers to the weight of the tire alone excluding the weight of the rim. On the other hand, when the tire inner cavity is provided with noise suppression materials, sealants, sensors, etc., G is defined as the weight including these.

[0041] Maximum load capacity (W L "(kg)" is set to: When the tire section width measured under normal conditions is set to Wt (mm), the tire section height is set to Ht (mm), and the tire outer diameter is set to Dt (mm), the value calculated by the following formula is different from the "maximum load capacity" based on the road index specified in the JATMA standard. V is the virtual volume of the space occupied by the tire.

[0042]

Mathematical formula 1

[0043] “Tire outer diameter Dt” means the outer diameter of the tire in a normal state.

[0044] The "cross-sectional width Wt of the tire" refers to the maximum width between the outer surfaces of the sidewalls in a normal state (except when there are patterns or letters on the side of the tire).

[0045] The "cross-sectional height Ht of the tire" refers to the height in the tire radial direction of a cross section including the tire rotation axis, and when the rim diameter of the tire is set to R, it can be calculated by (Dt-R) / 2.

[0046] The “cross-sectional area of ​​the steel cord” refers to the cross-sectional area of ​​the steel cord when the steel cord is cut along a plane perpendicular to the longitudinal direction of the steel cord.

[0047] "Softener" refers to a material that imparts plasticity to the rubber component and is a component extracted from the rubber composition using acetone. Softeners include softeners that are liquid (liquid) at 25°C and softeners that are solid at 25°C. However, wax and stearic acid commonly used in the tire industry are not included.

[0048] The "softener content" also includes the amount of softener contained in the extended rubber component that has been extended in advance with a softener such as oil, resin component, liquid rubber component, etc. The same applies to the oil content, resin component content, and liquid rubber content. For example, when the extended component is oil, the oil content includes the extended oil.

[0049] <Measurement method> "70°C E*" is the complex elastic modulus measured using a dynamic viscoelasticity measuring device (e.g., EPLEXOR series manufactured by GABO) at a temperature of 70°C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±1%, and a tensile mode. The sample for the 70°C E* measurement is a vulcanized rubber composition of 20 mm in length, 4 mm in width, and 1 mm in thickness. When it is cut from a tire, it is cut from the topping rubber with the tire circumferential direction being the long side and the tire radial direction being the thickness direction.

[0050] "70°C tanδ" is the loss tangent measured using a dynamic viscoelasticity measuring device (e.g., EPLEXOR series manufactured by GABO Corporation) under the conditions of temperature 70°C, frequency 10 Hz, initial strain 10%, dynamic strain ±1%, and tensile mode. The sample for this measurement is prepared in the same manner as in the case of 70°C E*.

[0051] "30℃ tanδ" is the loss tangent measured using a dynamic viscoelasticity measuring device (e.g., EPLEXOR series manufactured by GABO) under the conditions of temperature 30℃, frequency 10Hz, initial strain 5%, dynamic strain ±1%, and tensile mode. The sample for 30℃ tanδ measurement is a vulcanized rubber composition of 20mm long × 4mm wide × 1mm thick. When cutting from a tire, the sample is cut from the tread with the tire circumferential direction being the long side and the tire radial direction being the thickness direction.

[0052] "0°C tanδ" is the loss tangent measured using a dynamic viscoelasticity measuring device (e.g., EPLEXOR series manufactured by GABO Corporation) under the conditions of temperature 0°C, frequency 10 Hz, initial strain 10%, dynamic strain ±2.5%, and tensile mode. The sample for this measurement is prepared in the same manner as in the case of 30°C tanδ.

[0053] The “average thickness of the plating layer” is measured in accordance with JIS H 8501:1999.

[0054] Styrene content is 1 The value calculated by H-NMR measurement is applicable to a rubber component having a repeating unit derived from styrene, such as SBR, for example.

[0055] The “vinyl content (amount of 1,2-bonded butadiene units)” is a value calculated by infrared absorption spectrum analysis according to JIS K 6239-2:2017, and is applicable to rubber components having repeating units derived from butadiene, such as SBR and BR.

[0056] The “cis content (cis-1,4-bonded butadiene unit amount)” is a value calculated by infrared absorption spectrum analysis according to JIS K 6239-2:2017, and is applied to rubber components having repeating units derived from butadiene, such as BR.

[0057] The "total styrene content in the rubber component" refers to the total content (mass %) of styrene units contained in 100 mass % of the rubber component. For each rubber component, the styrene content (mass %) is calculated and multiplied by the mass ratio in the rubber component, and these values ​​are added together. Specifically, it is calculated by Σ(styrene content (mass %) of each rubber containing styrene unit × content (mass %) of each rubber containing styrene unit in the rubber component / 100).

[0058] The "weight average molecular weight (Mw)" can be determined by converting the measured value by gel permeation chromatography (GPC) (e.g., GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation) into standard polystyrene. For example, it is applicable to SBR, BR, etc.

[0059] The “nitrogen adsorption specific surface area (N2SA) of carbon black” is measured in accordance with JIS K 6217-2: 2017. The “nitrogen adsorption specific surface area (N2SA) of silica” is measured by the BET method in accordance with ASTM D3037-93.

[0060] The "average primary particle size" is obtained by taking a picture of the particles with a transmission or scanning electron microscope and taking the arithmetic average of the particle sizes of 400 particles. For the particle size, when the shape of the particle is roughly circular, the diameter of the circle is set as the particle size, and when it is needle-shaped or rod-shaped, the short diameter is set as the particle size. In other cases, the equivalent circle diameter calculated from the electron microscope image is used as the particle size. The equivalent circle diameter can be obtained by setting it to the positive square root of [4×(area of ​​the particle) / π]. The average primary particle size is applicable to silica, carbon black, etc.

[0061] The “softening point of the resin component” is a temperature at which a ball falls when the softening point specified in JIS K 6220-1:2015 7.7 is measured using a ring and ball softening point measuring apparatus.

[0062] The steps of manufacturing a tire according to one embodiment of the present invention will be described in detail below. However, the following description is an example for explaining the present invention, and the technical scope of the present invention is not limited to the description.

[0063] <Tires> Hereinafter, a tire according to an embodiment of the present invention will be described with reference to the drawings.

[0064] Figure 1 A cross-sectional view of a tire 11 according to the present embodiment taken along a plane passing through the tire rotation axis is shown. Figure 1 Only the left side of CL (center line) is shown in the figure. Let CL be the axis of symmetry. The same structure is continuous on the right side of CL. Figure 1 As shown, the tire 11 includes a tread portion 12, a sidewall portion 13, a bead portion 14, an inner liner 15, a carcass 16, a belt layer 17, and a bead wire 18. The belt layer 17 has two layers, but the number of layers is not particularly limited and can be arbitrarily selected.

[0065] Figure 2 A cross-sectional view of a surface perpendicular to the longitudinal direction of a steel cord 21 is shown. Each belt layer 17 has a plurality of steel cords 21 and a topping rubber 22. The plurality of steel cords 21 are arranged in a row. In addition, the topping rubber 22 covers the steel cords 21, and the entire body of each steel cord is covered by the topping rubber 22. The steel cord 21 is embedded in the topping rubber 22.

[0066] The steel cord 21 may or may not be inclined relative to the tire circumferential direction. The inclination angle of the steel cord 21 relative to the tire circumferential direction is not particularly limited, and is set, for example, in the range of 0° to 60°, preferably 5° to 45°, and more preferably 10° to 30°.

[0067] (Steel cord) The steel cord according to the present embodiment has one or more steel wires also called monofilaments. The steel cord may be a single-wire monofilament cord (i.e., a cord composed of one monofilament having a 1×1 structure) or may have a plurality of monofilaments, and a monofilament cord is a preferred embodiment.

[0068] It is considered that by using the steel cord as an untwisted monofilament cord, the rigidity of the steel cord is increased, and thus the deformation amount of the belt layer can be suppressed.

[0069] When one steel cord has a plurality of steel monofilaments, the steel cord preferably has a twist structure in which the plurality of monofilaments are twisted along the length direction thereof. When the steel cord has a plurality of monofilaments, the twist structure is not particularly limited, and may be, for example, a single-twisted steel cord of a 1×N structure or a layer-twisted steel cord of an N+M structure.

[0070] The single twist structure can be represented by a 1×N structure, for example. The 1×N structure refers to a structure in which N single filaments are twisted into a single layer (1 layer). A single layer means that in a cross section perpendicular to the longitudinal direction of the steel cord, the single filaments are arranged in a single layer (1 layer) along the circumferential direction of a circle. N in the single twist structure is preferably 6 or less, more preferably 4 or less, and particularly preferably 2.

[0071] Figure 3 It is a three-dimensional diagram of a steel cord having a 1×2 structure. Figure 3 In the steel cord 50 shown, two monofilaments 51 are twisted helically in the longitudinal direction to form a single layer.

[0072] The layer twist structure has a structure in which a plurality of monofilaments are sequentially wound in layers from the center in a cross section perpendicular to the longitudinal direction of the steel cord, and can be represented by, for example, an N+M structure. The N+M structure is a structure having a core in which N monofilaments are twisted in a spiral shape along the longitudinal direction thereof, and an outer sheath in which M monofilaments are twisted in a spiral shape along the longitudinal direction of the core so as to cover the outer circumference of the core.

[0073] The material of the steel wire is not particularly limited, and HT material (High Tensile), SHT material (Super High Tensile), UHT material (Ultra High Tensile), etc. can be used. In addition, recycled iron obtained by melting used iron products can also be used. In addition, when using a steel cord with multiple steel wires twisted together, from the perspective of improving durability by making it easier for the topping rubber to enter the steel cord, a steel wire that has been modified in the length direction in advance can also be used.

[0074] The monofilament diameter of the steel cord is not particularly limited and can be arbitrarily selected according to the required characteristics, etc. From the viewpoint of ensuring the durability of the steel cord against impact, it is preferably 0.10 mm or more, more preferably 0.13 mm or more, further preferably 0.16 mm or more, further preferably 0.19 mm or more, further preferably 0.22 mm or more, further preferably 0.25 mm or more, and particularly preferably 0.28 mm or more. In addition, from the viewpoint of fully absorbing impact and improving riding comfort performance, it is preferably 0.70 mm or less, more preferably 0.60 mm or less, further preferably 0.50 mm or less, further preferably 0.45 mm or less, further preferably 0.40 mm or less, and particularly preferably 0.35 mm or less.

[0075] The steel cord involved in this embodiment may also be coated. Since the steel cord with the coating layer can exhibit high moisture-heat resistant bonding performance even under harsh conditions of high temperature and high humidity, it can prevent the peeling between the topping rubber and the steel cord, and improve the durability of the tire under wet and hot conditions. In addition, when the steel cord has multiple monofilaments, a coating layer may be applied to the surface of each monofilament.

[0076] The composition of the coating layer is not particularly limited, and a coating layer including a copper layer and a zinc layer is preferred, and a coating layer including a copper layer, a zinc layer and a cobalt layer is more preferred. In particular, since high moisture-heat resistant adhesion can be exhibited even under harsh conditions of high temperature and high humidity, a steel cord having a ternary coating layer composed of copper (Cu), zinc (Zn) and cobalt (Co) can prevent peeling between the topping rubber and the steel cord, and can improve the durability of the tire under wet and hot conditions.

[0077] From the viewpoint of suppressing the overreaction of copper, the zinc content in the plated layer is preferably 15% by mass or more, more preferably 20% by mass or more, and further preferably 25% by mass or more. In addition, from the viewpoint of suppressing the decrease in adhesion caused by the generation of excess zinc oxide, it is preferably 44% by mass or less, more preferably 40% by mass or less, further preferably 36% by mass or less, and particularly preferably 32% by mass or less.

[0078] From the viewpoint of adhesion, the copper content in the plated layer is preferably 55% by mass or more, more preferably 58% by mass or more, and further preferably 61% by mass or more. In addition, from the viewpoint of preventing rubber degradation caused by the dissolution of copper under a hot and humid environment, it is preferably 78% by mass or less, more preferably 75% by mass or less, and further preferably 72% by mass or less.

[0079] From the viewpoint of wet heat adhesion, the cobalt content in the plated layer is preferably 1.0 mass % or more, more preferably 2.0 mass % or more, and further preferably 3.0 mass % or more. In addition, from the viewpoint of preventing cracks from occurring during wire drawing, it is preferably 8.0 mass % or less, more preferably 7.0 mass % or less, and further preferably 6.0 mass % or less.

[0080] The plating layer can be formed by forming a copper layer, a zinc layer, a cobalt layer, etc. by plating the monofilament before wire drawing, and then heat treating it to diffuse the metal layers formed on the surface of the monofilament. In addition, the stacking order formed on the monofilament to form the plating layer is not particularly limited.

[0081] Then, by subjecting the heat-treated material to wire drawing to a desired single-filament diameter, a single-filament having a coating layer can be formed. When the steel cord is composed of one single-filament, it can be used directly after wire drawing. In addition, when the steel cord has a plurality of single-filaments, after wire drawing, the obtained single-filaments can be twisted into a desired twist structure to obtain a steel cord having a coating layer.

[0082] From the viewpoint of initial adhesion, the average thickness of the plating layer is preferably 0.10 μm or more, more preferably 0.13 μm or more, and further preferably 0.16 μm or more. Furthermore, from the viewpoint of suppressing excessive adhesion reaction, it is preferably 0.40 μm or less, more preferably 0.35 μm or less, and further preferably 0.30 μm or less.

[0083] The cross-sectional area S of the steel cord is preferably 0.04 mm 2 More preferably 0.05 mm 2 More preferably, 0.06 mm 2 Above, particularly preferably 0.07 mm 2 In addition, the cross-sectional area S of the steel cord is preferably 0.80 mm 2 Below, more preferably 0.60 mm 2 Below, more preferably 0.40 mm 2 Below, more preferably 0.30 mm 2 Below, more preferably 0.25 mm 2 Below, particularly preferably 0.20 mm 2 the following.

[0084] The number of steel cords E (also referred to as ends) per 50 mm width in a direction perpendicular to the longitudinal direction of the steel cord is not particularly limited, but is preferably 20 or more, more preferably 25 or more, further preferably 30 or more, further preferably 35 or more, and particularly preferably 40 or more. In addition, E is preferably 90 or less, more preferably 80 or less, further preferably 70 or less, and particularly preferably 60 or less.

[0085] The product of S and E (S×E) is preferably 1.0 or more, more preferably 2.0 or more, further preferably 3.0 or more, further preferably 4.0 or more, further preferably 5.0 or more, and particularly preferably 5.5 or more. In addition, the product of S and E is preferably 25 or less, more preferably 20 or less, further preferably 15 or less, further preferably 12 or less, further preferably 10 or less, and particularly preferably 8.0 or less. In addition, the product of S and E is an index representing the amount of steel cord per unit cross-sectional area.

[0086] In the rubber composition constituting the topping rubber, when the content of silica relative to 100 parts by mass of the rubber component is Y (parts by mass), Y / (S×E) is preferably 0.10 or more, more preferably 0.30 or more, further preferably 0.50 or more, further preferably 0.75 or more, further preferably 1.0 or more, and particularly preferably 1.2 or more. It is believed that by mixing silica into the topping rubber, the rubber becomes acidic, and the zinc oxide film on the plated surface of the steel cord becomes easy to peel off, so that the adhesive layer can be efficiently formed. It is believed that by setting Y / (S×E) to the above range, the advantage of the adhesive layer formed by acidification is greater than the enlargement of the adhesive layer caused by the precipitation of copper, and good adhesive performance can be obtained. On the other hand, the upper limit value of Y / (S×E) is not particularly limited, but is preferably 20 or less, more preferably 10 or less, further preferably 5.0 or less, and particularly preferably 2.5 or less.

[0087] From the viewpoint of better exerting the effect of the present invention, the maximum load capacity W of the tire L (kg) is preferably 400 or more, more preferably 500 or more, further preferably 600 or more, further preferably 700 or more, and particularly preferably 800 or more. L (kg) is preferably 1300 or less, more preferably 1200 or less, and further preferably 1100 or less. L It can be increased by increasing the virtual volume V of the space occupied by the tire, or vice versa.

[0088] When the weight of the tire is G (kg), from the viewpoint of the effect of the present invention, G / W LIt is preferably 0.060 or less, more preferably 0.040 or less, further preferably 0.025 or less, and particularly preferably 0.020 or less. L The lower limit of is not particularly limited, for example, it can be set to be above 0.012, above 0.013, or above 0.014. In addition, the weight G of the tire can be changed by conventional methods, that is, it can be increased by increasing the specific gravity of the tire, or by increasing the thickness of each component of the tire, or vice versa.

[0089] From the viewpoint of the effect of the present invention, the complex elastic modulus (70°C E*1) of the topping rubber at 70°C is 15.0 MPa or less, preferably 14.0 MPa or less, more preferably 12.0 MPa or less, further preferably 10.0 MPa or less, further preferably 9.0 MPa or less, further preferably 8.0 MPa or less, and particularly preferably 7.0 MPa or less. On the other hand, the lower limit of 70°C E*1 is not particularly limited, but is preferably 2.0 MPa or more, more preferably 3.0 MPa or more, and further preferably 4.0 MPa or more.

[0090] From the viewpoint of the effect of the present invention, the tanδ of the topping rubber at 70°C (tanδ1 at 70°C) is preferably 0.079 or less, more preferably 0.065 or less, further preferably 0.052 or less, further preferably 0.046 or less, further preferably 0.040 or less, further preferably 0.036 or less, and particularly preferably 0.033 or less. On the other hand, the lower limit of tanδ1 at 70°C is not particularly limited, but is preferably 0.020 or more, more preferably 0.023 or more, and further preferably 0.026 or more.

[0091] The tire according to this embodiment is characterized in that W L And tanδ1 at 70°C satisfies the following formula (1). 9.33×10 -5 ×W L -70℃tanδ1>0.023…(1)

[0092] From the perspective of the effect of the present invention, 9.33×10 -5 ×W L -70°C tanδ1 is preferably greater than 0.024, more preferably greater than 0.030, further preferably greater than 0.035, and particularly preferably greater than 0.040. -5 ×W L The upper limit of tan δ1 at -70°C is not particularly limited, but is preferably less than 0.090, more preferably less than 0.085, further preferably less than 0.080, and particularly preferably less than 0.075.

[0093] From the viewpoint of heat generation, the tanδ of the running surface rubber layer at 30°C (tanδ2 at 30°C) is preferably 0.25 or less, more preferably 0.23 or less, further preferably 0.20 or less, further preferably 0.18 or less, further preferably 0.16 or less, further preferably 0.15 or less, and particularly preferably 0.14 or less. On the other hand, from the viewpoint of ride comfort performance, tanδ2 at 30°C is preferably 0.03 or more, more preferably 0.05 or more, further preferably 0.07 or more, and particularly preferably 0.09 or more.

[0094] From the viewpoint of low fuel consumption performance at low temperatures, the tan δ of the running surface rubber layer at 0°C (tan δ2 at 0°C) is preferably 0.42 or less, more preferably 0.40 or less, further preferably 0.38 or less, further preferably 0.36 or less, and particularly preferably 0.34 or less. On the other hand, from the viewpoint of wet grip performance, tan δ2 at 0°C is preferably 0.07 or more, more preferably 0.10 or more, further preferably 0.12 or more, further preferably 0.15 or more, and particularly preferably 0.18 or more.

[0095] 0℃tanδ2 / 30℃tanδ2 is preferably greater than 1.4, more preferably greater than 1.5, further preferably greater than 1.7, further preferably greater than 1.9, further preferably greater than 2.1, and particularly preferably greater than 2.3. By setting 0℃tanδ2 / 30℃tanδ2 to the above range, the running surface rubber layer can be kept in a soft state to the low temperature region, so that in a wider temperature range, the strain concentration on the internal parts of the tire due to rotational deformation can be suppressed. As a result, it is believed that the mechanical fatigue deterioration caused by the deformation of the topping rubber is suppressed, and the durability of the tire is further improved. On the other hand, the upper limit value of 0℃tanδ2 / 30℃tanδ2 is not particularly limited, and is preferably less than 3.0, and more preferably less than 2.8.

[0096] [Rubber composition] The rubber composition of the topping rubber of the tire and the rubber composition of the tread portion (hereinafter referred to as the rubber composition of the present embodiment) are compositions containing rubber components and fillers, and can be manufactured using the raw materials described below. The rubber composition of the present embodiment is described below, but unless otherwise specified, it is assumed to be any type of rubber composition that can be applied to the tread portion and the rubber composition that can be applied to the topping rubber.

[0097] <Rubber ingredients> The rubber composition involved in the present embodiment can preferably use a diene rubber as a rubber component. As the diene rubber, for example, isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene rubber (SIR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), etc. can be cited. These diene rubbers can be modified rubbers treated with a modifying group that can interact with fillers such as carbon black or silica, or can be hydrogenated rubbers in which a part of the unsaturated bonds is hydrogenated. One type of diene rubber can be used alone, or two or more types can be used in combination. In addition, as the diene rubber, a volume-enhanced rubber pre-increased with the following softener can also be used.

[0098] The content of the diene rubber in the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and particularly preferably 95% by mass or more. Alternatively, the rubber component may be composed only of diene rubber.

[0099] As the diene rubber component, at least one selected from the group consisting of isoprene rubber, SBR and BR can be preferably used. The diene rubber component preferably contains isoprene rubber, more preferably contains isoprene rubber and SBR and / or BR, further preferably contains isoprene rubber and SBR, and particularly preferably contains isoprene rubber, BR and SBR.

[0100] (Isoprene rubber) As the isoprene rubber, for example, common rubbers in the tire industry such as isoprene rubber (IR) and natural rubber can be used. Natural rubbers include, in addition to non-modified natural rubber (NR), modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, and grafted natural rubber. These isoprene rubbers can be used alone or in combination of two or more.

[0101] The NR is not particularly limited, and those commonly used in the tire industry can be used, and examples thereof include SIR20, RSS#3, and TSR20.

[0102] From the viewpoint of the effect of the present invention, the content of the isoprene rubber in the rubber component constituting the topping rubber is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more. On the other hand, the upper limit of the content is not particularly limited and may be set to 100% by mass.

[0103] From the viewpoint of the effect of the present invention, the content of the isoprene-based rubber in the rubber component constituting the cap rubber layer is preferably 70% by mass or less, more preferably 60% by mass or less, further preferably 50% by mass or less, and particularly preferably 45% by mass or less. On the other hand, the lower limit of the content is not particularly limited, and can be set to 1% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more.

[0104] (SBR) As SBR, there is no particular limitation, and examples include unmodified solution polymerization SBR (S-SBR), emulsion polymerization SBR (E-SBR), their modified SBR (modified S-SBR, modified E-SBR), etc. As modified SBR, examples include modified SBR (condensates, substances with branched structures, etc.) coupled with SBR, tin, silicon compounds, etc. modified at the end and / or main chain, etc. Among them, S-SBR and modified SBR are preferred. Further, hydrides of these SBRs (hydrogenated SBR), etc., can also be used. These SBRs can be used alone or in combination of two or more.

[0105] As the SBR involved in this embodiment, either extended SBR or non-extended SBR can be used. When extended SBR is used, the extended amount of SBR, that is, the content of extended softener contained in SBR is preferably 10 to 50 parts by mass relative to 100 parts by mass of the rubber solid content of SBR.

[0106] As the SBR listed above, for example, commercially available products from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., ZS ELASTOMERS Co., Ltd., etc. can be used.

[0107] The styrene content of SBR is preferably 40% by mass or less, more preferably 36% by mass or less, further preferably 32% by mass or less, and particularly preferably 28% by mass or less. In addition, the styrene content of SBR is preferably 5% by mass or more, more preferably 7% by mass or more, further preferably 10% by mass or more, and particularly preferably 12% by mass or more. In addition, the styrene content of SBR is measured by the above-mentioned determination method.

[0108] From the viewpoint of ensuring reactivity with silica and wear resistance, the vinyl content of SBR is preferably more than 5 mol%, more preferably more than 10 mol%, and more preferably more than 15 mol%. In addition, from the viewpoint of elongation at break and wear resistance, the vinyl content of SBR is preferably less than 45 mol%, more preferably less than 40 mol%, and more preferably less than 35 mol%. In addition, the vinyl content of SBR is measured by the above-mentioned determination method.

[0109] From the viewpoint of the effect of the present invention, the weight average molecular weight (Mw) of SBR is preferably 100,000 or more, more preferably 200,000 or more, and further preferably 300,000 or more. In addition, from the viewpoint of crosslinking uniformity, the weight average molecular weight is preferably 2,000,000 or less, more preferably 1,800,000 or less, and further preferably 1,500,000 or less. In addition, the weight average molecular weight of SBR is measured by the above-mentioned measuring method.

[0110] The content of SBR in the rubber component constituting the topping rubber is not particularly limited, but is preferably 40% by mass or less, more preferably 20% by mass or less, further preferably 10% by mass or less, and particularly preferably 5% by mass or less.

[0111] The content of SBR in the rubber component constituting the cap rubber layer can be appropriately selected, for example, so that the total amount of styrene in the rubber component constituting the cap rubber layer satisfies the following range, and is preferably 85% by mass or less, more preferably 80% by mass or less, further preferably 75% by mass or less, and particularly preferably 70% by mass or less. On the other hand, the lower limit of the content is not particularly limited, and can be 1% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more.

[0112] (BR) The BR is not particularly limited, and for example, BR having a cis content of less than 50 mol% (low cis BR), BR having a cis content of 90 mol% or more (high cis BR), rare earth-based butadiene rubber synthesized using a rare earth element-based catalyst (rare earth-based BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high cis-modified BR, low cis-modified BR), and the like, which are generally used in the tire industry, can be used. These BRs may be used alone or in combination of two or more.

[0113] As high cis BR, for example, commercially available materials such as Zeon Co., Ltd., Ube Industries, Ltd., and JSR Co., Ltd. can be used. By containing high cis BR, wear resistance can be improved. The cis content of high cis BR is preferably 95 mol% or more, more preferably 96 mol% or more, and further preferably 97 mol% or more. In addition, the cis content of BR is measured by the above-mentioned measurement method.

[0114] The content of BR in the rubber component constituting the topping rubber is not particularly limited, but is preferably 40% by mass or less, more preferably 20% by mass or less, further preferably 10% by mass or less, and particularly preferably 5% by mass or less.

[0115] From the viewpoint of the effects of the present invention, the content of BR in the rubber component constituting the cap rubber layer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, further preferably 20 parts by mass or more, and particularly preferably 30 parts by mass or more. In addition, the content is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, further preferably 50 parts by mass or less, and particularly preferably 45 parts by mass or less.

[0116] From the viewpoint of the effect of the present invention, the total styrene content in the rubber component constituting the cap rubber layer is preferably 25% by mass or less, more preferably 20% by mass or less, further preferably 15% by mass or less, and particularly preferably 13% by mass or less. In addition, the lower limit of the total styrene content in the rubber component is not particularly limited, but is preferably 1% by mass or more, more preferably 3% by mass or more, further preferably 5% by mass or more, and particularly preferably 7% by mass or more.

[0117] (Other rubber components) In the range that does not affect the effect of the present invention, the rubber component may also contain other rubber components other than the diene rubber. As other rubber components other than the diene rubber, crosslinkable rubber components commonly used in the tire industry can be used, for example, non-diene rubbers such as butyl rubber (IIR), halogenated butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), and epichlorohydrin rubber can be cited. In addition, in addition to the above-mentioned rubber components, it may also contain or not contain a known thermoplastic elastomer. Other rubber components may be used alone or in combination of two or more.

[0118] (Rubber components synthesized from recycled / biomass-derived raw materials) The monomers constituting the units of synthetic rubbers such as SBR and BR may be substances derived from petroleum, or substances recovered from rubber products such as tires or non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples thereof include butadiene derived from recycling, aromatic vinyl compounds derived from recycling, and the like. Examples of the above-mentioned butadiene include 1,2-butadiene and 1,3-butadiene. Examples of the above-mentioned aromatic vinyl compounds are not particularly limited, and examples thereof include styrene, and the like. Among them, it is preferred to use butadiene derived from recycling (recycled butadiene) and / or styrene derived from recycling (recycled styrene) as raw materials.

[0119] There are no particular limitations on the method for producing the recovered monomer, and for example, the monomer may be synthesized from recycled naphtha obtained by cracking rubber products such as tires. In addition, there are no particular limitations on the method for producing the recycled naphtha, and for example, rubber products such as tires may be cracked under high temperature and high pressure, or by microwave cracking, or by mechanical crushing followed by extraction.

[0120] Furthermore, monomers as constituent units of polymers such as SBR and BR may also be substances derived from biomass. As monomers derived from biomass (biomass monomers), there are no particular limitations, and examples include butadiene derived from biomass, aromatic vinyl compounds derived from biomass, and the like. As the above-mentioned butadiene, 1,2-butadiene and 1,3-butadiene can be cited. As the above-mentioned aromatic vinyl compounds, there are no particular limitations, and examples include styrene, etc. In addition, the method for producing biomass monomers is not particularly limited, and for example, substances based on biological and / or chemical and / or physical transformations of animals and plants can be cited. As biological transformations, fermentation based on microorganisms is representative, and as chemical and / or physical transformations, catalyst-based transformations, high-heat-based transformations, high-pressure-based transformations, electromagnetic wave-based transformations, critical liquid-based transformations, and combinations thereof can be cited. As biomass sources for these monomers, examples include sugar or wood, plant residues after obtaining useful components, ethanol derived from plants, biomass naphtha, and the like.

[0121] The polymer (biomass polymer) synthesized from the biomass monomer component is not particularly limited, and examples thereof include polybutadiene rubber synthesized from butadiene derived from biomass, aromatic vinyl / butadiene copolymer synthesized from butadiene derived from biomass and / or aromatic vinyl derived from biomass, etc. As the above-mentioned aromatic vinyl / butadiene copolymer, for example, styrene-butadiene rubber synthesized from butadiene derived from biomass and / or styrene derived from biomass, etc. can be mentioned.

[0122] Whether the raw material of a polymer is derived from biomass can be determined by measuring pMC (percent modern carbon) according to ASTM D6866-10. pMC refers to: 14 C concentration relative to modern carbon (modern standard reference) 14 The ratio of C concentration is used as an index to indicate the biomass ratio of the compound (rubber). The significance of this value will be described below.

[0123] 1 mol (6.02×10 23 There are about one trillionth of ordinary carbon atoms in the carbon atom, that is, about 6.02×10 11 indivual 14 C.14 The half-life of C is 5730 years. 14 Therefore, it is believed that the carbon dioxide in the atmosphere has been absorbed and fixed by plants for more than 226,000 years. In fossil fuels such as coal, oil, and natural gas, the carbon dioxide in the atmosphere has been fixed for more than 226,000 years. 14 Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain any 14 Therefore, the chemical substances produced from these fossil fuels do not contain any 14 Element C.

[0124] on the other hand, 14 C is continuously generated by cosmic rays in the atmosphere due to nuclear reactions. 14 C is balanced by the reduction of radioactive decay and the generation of nuclear reactions. In the Earth's atmosphere, 14 Therefore, in the current environment, the amount of materials derived from biomass resources in the material cycle is 14 As mentioned above, the C concentration is about 1×10 -12 Therefore, the ratio (biomass ratio) of a compound derived from a natural resource (a compound derived from a biomass resource) in a certain compound (rubber) can be calculated using the difference between these values.

[0125] Usually, the 14 C was measured as follows. Using tandem accelerator-based accelerator mass spectrometry, 13 C concentration ( 13 C / 12 C) 14 C concentration ( 14 C / 12 C) determination. When determining, as 14 The modern standard reference (standard modern carbon) is based on the concentration of carbon in the natural circulation in 1950. 14 C concentration. As a specific standard substance, an oxalic acid standard provided by NIST (National Institute of Standards and Technology) was used. The specific radioactivity of carbon in the oxalic acid (per 1g of carbon) was calculated. 14 The radioactivity intensity of C is classified according to each carbon isotope. 13 The C correction is a fixed value, and the value to which the decay correction from 1950 to the date of measurement is applied is used as the standard 14The C concentration value (100%) is used. The ratio of this value to the value of the sample actually measured is the pMC value.

[0126] Therefore, if the rubber is made of 100% biomass (natural) materials, it will show a value of about 110 pMC (most of which will not be 100 under normal conditions today) although there are regional differences. 14 When the concentration of C is about 0 pMC (for example, 0.3 pMC), this value corresponds to the above-mentioned biomass ratio of 0%.

[0127] In summary, it is preferable from the perspective of environmental protection to use rubber or other materials with a high pMC value, that is, rubber or other materials with a high biomass ratio, for the rubber composition.

[0128] <Packing> The rubber composition according to the present embodiment preferably contains silica as a filler, and more preferably contains silica and carbon black. In addition, the filler may be a filler consisting only of carbon black and silica.

[0129] (Silicon Dioxide) As silicon dioxide, there is no particular limitation, for example, general silicon dioxide in the tire industry such as silicon dioxide prepared by a dry method (anhydrous silicon dioxide) and silicon dioxide prepared by a wet method (hydrous silicon dioxide) can be used. As the raw material of silicon dioxide, there is no particular limitation, for example, it can be a raw material derived from minerals such as quartz, it can also be a raw material derived from organisms such as rice husks (for example, silicon dioxide using biomass materials such as rice husks as raw materials, etc.), and silicon dioxide recovered from products containing silicon dioxide can also be used. Among them, due to the large number of silanol groups, hydrous silicon dioxide prepared by a wet method is preferred. These silicon dioxides can be used alone or in combination of two or more.

[0130] Silica made from biomass materials can be obtained by extracting silicate from rice husk ash obtained by burning rice husks with a sodium hydroxide solution, and using the silicate to react with sulfuric acid in the same way as conventional wet silica, filtering the silica precipitate generated, washing with water, drying, and pulverizing.

[0131] Silica recovered from products containing silica may be, for example, silica recovered from electronic components such as semiconductors, tires, desiccants, diatomaceous earth and other filter materials containing silica. In addition, the recovery method is not particularly limited, and thermal cracking, electromagnetic wave cracking and the like can be cited. Among them, silica recovered from electronic components such as semiconductors or tires is preferred.

[0132] If silicon dioxide is crystallized, it will not dissolve in water, and the silicic acid as its component cannot be used. By controlling the combustion temperature and combustion time, the crystallization of silicon dioxide in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Online Journal B / 2019, vol. 6, p. 216-222, etc.).

[0133] Amorphous silica extracted from rice husks and commercially available products such as Wilmar can be used.

[0134] From the viewpoint of wear resistance and elongation at break, the nitrogen adsorption specific surface area (N2SA) of silica is preferably 100 m 2 / g or more, more preferably 120m 2 / g or more, more preferably 140m 2 / g or more, particularly preferably 160 m 2 / g or more. In addition, from the viewpoint of heat generation and processability, 350 m 2 / g or less, more preferably 300m 2 / g or less, more preferably 250m 2 / g or less. In addition, the N2SA of silica is measured by the above-mentioned measurement method.

[0135] The average primary particle size of silicon dioxide is preferably less than 20nm, more preferably less than 18nm, further preferably less than 17nm, and particularly preferably less than 16nm. The lower limit of the average primary particle size is not particularly limited, and from the viewpoint of the dispersibility of silicon dioxide, it is preferably more than 1nm, more preferably more than 3nm, and more preferably more than 5nm. In addition, the average primary particle size of silicon dioxide is measured by the above-mentioned measuring method.

[0136] From the viewpoint of the effect of the present invention, in the rubber composition constituting the topping rubber, the content Y (mass parts) of silica relative to 100 mass parts of the rubber component is preferably 1 mass part or more, more preferably 3 mass parts or more, further preferably 5 mass parts or more, and particularly preferably 7 mass parts or more. In addition, from the viewpoint of tire strength, it is preferably 50 mass parts or less, more preferably 40 mass parts or less, further preferably 30 mass parts or less, and particularly preferably 25 mass parts or less.

[0137] From the viewpoint of the effects of the present invention, in the rubber composition constituting the cap rubber layer, the content of silica relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 4 parts by mass or more, further preferably 7 parts by mass or more, and particularly preferably 10 parts by mass or more. In addition, the content is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, further preferably 40 parts by mass or less, and particularly preferably 35 parts by mass or less.

[0138] (Carbon Black) The carbon black is not particularly limited, and general materials used in the tire industry such as GPF, FEF, HAF, ISAF, and SAF can be used. Specifically, N110, N115, N120, N125, N134, N135, N219, N220, N231, N234, N293, N299, N326, N330, N339, N343, and N347 can be preferably used. , N351, N356, N358, N375, N539, N550, N582, N630, N642, N650, N660, N683, N754, N762, N765, N772, N774, N787, N907, N908, N990, N991, etc. In addition to these, synthetic products of Sumitomo Rubber Industries, Ltd. can also be preferably used. The raw material of carbon black can be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by pyrolysis of waste tires. In addition, the manufacturing method of carbon black can be a combustion-based method such as a furnace method, a method based on hydrothermal carbonization (HTC), or a method based on thermal cracking of methane derived from a thermal black method, etc. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shinjika Carbon Co., Ltd., Columbia Carbon Co., Ltd., etc. can be used. These carbon blacks may be used alone or in combination of two or more.

[0139] In this specification, "regenerated carbon black" refers to carbon black obtained by crushing used tires and other products containing carbon black and burning the crushed products, and the mass ratio of the unburned component, i.e., ash (ash content) is 13% by mass or more when heated in air to cause oxidative combustion using the thermogravimetric method based on JIS K 6226-2:2003. In other words, the mass ratio of the reduced amount (carbon content) of the regenerated carbon black based on the above-mentioned oxidative combustion is 87% by mass or less. Regenerated carbon black is sometimes also represented by rCB.

[0140] Regenerated carbon black can be obtained by the thermal cracking process of used pneumatic tires. For example, in the specification of European Patent Application Publication No. 3427975, "Rubber Chemistry and Technology", Vol. 85, No. 3, pp. 408-449 (2012), especially pp. 438, 440, 442, it is mentioned that it is obtained by thermal cracking of organic materials at 550-800°C after removing oxygen, or by vacuum thermal cracking at a relatively low temperature (

[0027] ). As mentioned in

[0004] of Japanese Patent Gazette No. 6856781, the carbon black obtained by such a thermal cracking process is generally a regenerated carbon black lacking functional groups on its surface (surface morphology and chemical comparison between thermal cracked carbon black and commercially available carbon black, Powder Technology 160 (2005) 190-193).

[0141] Regenerated carbon black may be carbon black lacking functional groups on its surface, or may be carbon black treated so that its surface contains functional groups. The treatment to make the surface of the recycled carbon black contain functional groups can be implemented by conventional methods. For example, in the specification of European Patent Application Publication No. 3173251, carbon black containing hydroxyl and / or carboxyl groups on its surface is obtained by treating the carbon black obtained by the thermal cracking process with potassium permanganate under acidic conditions. In addition, in Japanese Patent Gazette No. 6856781, the carbon black obtained by the thermal cracking process is treated with an amino acid compound containing at least one thiol or disulfide group to obtain carbon black whose surface is activated. The regenerated carbon black involved in this embodiment includes these carbon blacks treated to make the surface contain functional groups.

[0142] As the regenerated carbon black, commercially available products such as Strable Green Carbon and LD Carbon can be used.

[0143] The filler contained in the rubber composition constituting the topping rubber preferably contains regenerated carbon black. Regenerated carbon black has a wider particle size distribution than ordinary carbon black. Therefore, it is believed that: compared with the case of mixing ordinary carbon black, even with respect to input of a wide range of various frequencies from the road surface, the movement of the polymer can be suppressed, and the heat generation of the topping rubber can be suppressed, thereby further improving the durability of the tire.

[0144] From the viewpoint of the effect of the present invention, the nitrogen adsorption specific surface area (N2SA) of the carbon black contained in the rubber composition constituting the topping rubber is preferably 20 m 2 / g or more, more preferably 40m 2 / g or more, more preferably 50m 2 / g or more, particularly preferably 60 m 2 / g or more. In addition, from the viewpoint of low fuel consumption performance and processability, 200 m 2 / g or less, more preferably 150m 2 / g or less, more preferably 120m 2 / g or less. In addition, the N2SA of carbon black is measured by the above-mentioned measurement method.

[0145] The average primary particle size of the carbon black contained in the rubber composition constituting the topping rubber is preferably 45 nm or less, more preferably 40 nm or less, further preferably 35 nm or less, and particularly preferably 32 nm or less. The lower limit of the average primary particle size is not particularly limited, but is preferably 5 nm or more, more preferably 8 nm or more, and further preferably 10 nm or more. In addition, the average primary particle size of the carbon black is measured by the above-mentioned measurement method.

[0146] From the viewpoint of reinforcement, the nitrogen adsorption specific surface area (N2SA) of the carbon black contained in the rubber composition constituting the cap rubber layer is preferably 30 m 2 / g or more, more preferably 50m 2 / g or more, more preferably 70m 2 / g or more, particularly preferably 90m 2 / g or more. In addition, from the viewpoint of low fuel consumption performance and processability, 200 m 2 / g or less, more preferably 150m 2 / g or less, more preferably 120m 2 / g or less.

[0147] The average primary particle size of the carbon black contained in the rubber composition constituting the topping rubber is preferably 36 nm or less, more preferably 32 nm or less, further preferably 28 nm or less, and particularly preferably 24 nm or less. The lower limit of the average primary particle size is not particularly limited, but is preferably 5 nm or more, more preferably 8 nm or more, and further preferably 10 nm or more.

[0148] From the viewpoint of elongation at break, the content of carbon black in the rubber composition constituting the topping rubber is preferably 10 parts by mass or more, more preferably 13 parts by mass or more, further preferably 16 parts by mass or more, further preferably 19 parts by mass or more, and particularly preferably 22 parts by mass or more, relative to 100 parts by mass of the rubber component. In addition, from the viewpoint of suppressing heat generation, it is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, further preferably 40 parts by mass or less, and particularly preferably 35 parts by mass or less.

[0149] When the rubber composition constituting the topping rubber contains regenerated carbon black, from the viewpoint of the effect of the present invention, the content thereof is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more relative to 100 parts by mass of the rubber component. In addition, from the viewpoint of suppressing heat generation, it is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, further preferably 40 parts by mass or less, and particularly preferably 35 parts by mass or less.

[0150] From the viewpoint of reinforcement, the content of carbon black in the rubber composition constituting the cap rubber layer is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, further preferably 7 parts by mass or more, and particularly preferably 10 parts by mass or more, relative to 100 parts by mass of the rubber component. Furthermore, from the viewpoint of suppressing heat generation, it is preferably 35 parts by mass or less, more preferably 30 parts by mass or less, further preferably 27 parts by mass or less, further preferably 23 parts by mass or less, and particularly preferably 20 parts by mass or less.

[0151] (Other fillers) Fillers other than silica and carbon black are not particularly limited, and for example, materials commonly used in the tire industry such as aluminum hydroxide, alumina, calcium carbonate, magnesium sulfate, talc, clay, and biochar can be mixed. These other fillers can be used alone or in combination of two or more.

[0152] From the viewpoint of the effect of the present invention, the total content of the filler relative to 100 parts by mass of the rubber component is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, further preferably 30 parts by mass or more, and particularly preferably 35 parts by mass or more. In addition, from the viewpoint of suppressing heat generation, it is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, further preferably 50 parts by mass or less, and particularly preferably 45 parts by mass or less.

[0153] In the rubber composition constituting the topping rubber, the ratio of silica to the total content of silica and carbon black is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, further preferably 20% by mass or more, and particularly preferably 25% by mass or more. In addition, in the rubber composition constituting the topping rubber, the ratio of silica to the total content of silica and carbon black is selected to be 75% by mass or less, more preferably 65% ​​by mass or less, further preferably 55% by mass or less, and particularly preferably 45% by mass or less.

[0154] In the rubber composition constituting the cap rubber layer, the ratio of silica to the total content of silica and carbon black is preferably 20% by mass or more, more preferably 25% by mass or more, further preferably 30% by mass or more, and particularly preferably 33% by mass or more. In addition, in the rubber composition constituting the cap rubber layer, the ratio of silica to the total content of silica and carbon black is preferably 99% by mass or less, more preferably 90% by mass or less, further preferably 80% by mass or less, and particularly preferably 70% by mass or less.

[0155] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited, and any silane coupling agent that has been used in combination with silica in the tire industry can be used, for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane and other mercapto-based silane coupling agents; bis(3-triethoxysilylpropyl)disulfide, bis(3-triethoxysilylpropyl)tetrasulfide and other sulfide-based silane coupling agents; 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, 3-octanoylthio-1-propyltrimethoxysilane, 2-octanoylthio-1-propyltrimethoxysilane, 2-octanoylthio-1-propyltrieth ...ethoxysilane, 2-octanoylthio-1-propyltrimethoxysilane, 2-octanoylthio-1-propyltriethoxysilane, 2-octanoylthio-1-propyltriethoxysilane, 2-octanoylthio-1-propyltrimethoxysilane, 2-octanoyl Thioester silane coupling agents such as thiosilane; vinyl silane coupling agents such as vinyl triethoxysilane and vinyl trimethoxysilane; amino silane coupling agents such as 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane, and 3-(2-aminoethyl)aminopropyl triethoxysilane; glycidyl silane coupling agents such as γ-glycidoxypropyl triethoxysilane and γ-glycidoxypropyl trimethoxysilane; nitro silane coupling agents such as 3-nitropropyl trimethoxysilane and 3-nitropropyl triethoxysilane; chlorinated silane coupling agents such as 3-chloropropyl trimethoxysilane and 3-chloropropyl triethoxysilane, etc. Among them, sulfide silane coupling agents and / or mercapto silane coupling agents are preferably contained. As the silane coupling agent, for example, commercially available substances such as Momentive can be used. These silane coupling agents may be used alone or in combination of two or more.

[0156] When a silane coupling agent is contained, from the viewpoint of improving the dispersibility of silica, its content relative to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, further preferably 2.0 parts by mass or more, and particularly preferably 4.0 parts by mass or more. In addition, from the viewpoint of preventing a decrease in wear resistance, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 12 parts by mass or less.

[0157] <Thermosetting resin> The rubber composition constituting the topping rubber preferably contains a thermosetting resin. Here, the thermosetting resin refers to a resin that forms a network structure when polymerized by heating and does not return to its original state after curing.

[0158] There are no particular restrictions on the thermosetting resin, and examples thereof include resorcinol resin, modified resorcinol resin, cresol resin, modified cresol resin, phenolic resin, modified phenolic resin, etc. These thermosetting resins can be used alone or in combination of two or more. By mixing these thermosetting resins, the adhesion to the cord, the elongation at break, and the complex elastic modulus can be improved. Among them, resorcinol resin, modified resorcinol resin, and modified cresol resin are preferred, and modified resorcinol resin is more preferred.

[0159] Examples of the resorcinol resin include resorcinol-formaldehyde condensates, and examples of the modified resorcinol resin include products obtained by alkylating a portion of the repeating units of the resorcinol resin.

[0160] Examples of the cresol resin include cresol-formaldehyde condensates, and examples of the modified cresol resin include products in which the methyl groups at the terminals of the cresol resin are modified with hydroxyl groups, and products in which a part of the repeating units of the cresol resin are alkylated.

[0161] As phenolic resin, there can be mentioned resins obtained by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, furfural, etc. using an acid or alkaline catalyst. Among them, resins obtained by reacting under an acid catalyst (phenolic resins of novolac type, etc.) are preferred. In addition, as modified phenolic resin, there can be mentioned resins obtained by modifying phenolic resin with cashew nut oil, tall oil, linseed oil, various animal and vegetable oils, unsaturated fatty acids, rosin, alkylbenzene resins, aniline, melamine, etc.

[0162] When the rubber composition constituting the topping rubber contains a thermosetting resin, from the viewpoint of adhesion and durability, the content thereof relative to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and further preferably 1.5 parts by mass or more. In addition, from the viewpoint of suppressing the adhesion reaction during vulcanization and preventing the decrease in durability after wet heat degradation, it is preferably 6.0 parts by mass or less, more preferably 5.0 parts by mass or less, further preferably 4.5 parts by mass or less, and particularly preferably 4.0 parts by mass or less.

[0163] <Curing Agent> In order to cure the aforementioned thermosetting resin, the rubber composition constituting the topping rubber preferably contains a curing agent. There are no particular restrictions on the curing agent, and examples thereof include hexamethoxymethyl melamine (HMMM), modified etherified methylol melamine resin, hexamethylenetetramine (HMT), penta(methoxymethyl)methylol melamine, tetra(methoxymethyl)dimethylol melamine, etc., preferably modified etherified methylol melamine resin. These curing agents may be used alone or in combination of two or more.

[0164] When the rubber composition constituting the topping rubber contains a curing agent, from the viewpoint of the effect of the present invention, the content thereof is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, further preferably 0.5 parts by mass or more, and particularly preferably 0.7 parts by mass or more relative to 100 parts by mass of the rubber component. In addition, the content is preferably 3.0 parts by mass or less, more preferably 2.5 parts by mass or less, and further preferably 2.0 parts by mass or less.

[0165] <Cobalt compounds> The rubber composition constituting the topping rubber preferably contains a cobalt compound. By containing a cobalt compound, the adhesion between the steel cord and the topping rubber can be improved, and a tire with excellent durability can be obtained. As the cobalt compound, for example, cobalt, cobalt chloride, organic acid cobalt, inorganic acid cobalt, etc. can be listed, preferably organic acid cobalt. These cobalt compounds can be used alone or in combination of two or more.

[0166] In order to promote the adhesion between the coating layer of the steel cord and the rubber composition, and to prevent the coating component from flowing out into the rubber composition during hygroscopic thermal degradation, it is preferred to use organic acid cobalt. The number of carbon atoms of the organic acid constituting the organic acid cobalt is preferably 12 or more and 24 or less, and more preferably 14 or more and 22 or less. As specific examples of organic acid cobalt salts, for example, cobalt stearate, cobalt naphthenate, cobalt neodecanoate, cobalt rosin acid, cobalt neodecanoate (Versatic acid), cobalt tall oil acid, cobalt oleate, cobalt linoleate, cobalt linolenate, cobalt palmitate, etc. can be cited. In addition, the organic acid cobalt can also be set as a composite salt in which a part of the organic acid is replaced by boric acid (e.g., cobalt borate neodecanoate).

[0167] Examples of the inorganic cobalt acid include cobalt sulfate, cobalt nitrate, cobalt phosphate, and cobalt chromate.

[0168] When the rubber composition constituting the topping rubber contains a cobalt compound, from the viewpoint of adhesion, the content thereof is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and further preferably 0.5 parts by mass or more relative to 100 parts by mass of the rubber component. In addition, the content is preferably 3.0 parts by mass or less, more preferably 2.0 parts by mass or less, and further preferably 1.5 parts by mass or less.

[0169] <Other Mixtures> The rubber composition involved in this embodiment may appropriately contain, in addition to the above-mentioned components, admixtures commonly used in the tire industry in the past, such as softeners, vulcanized rubber particles (rubber powder), antioxidants, waxes, processing aids, stearic acid, zinc oxide, vulcanizers, vulcanization accelerators, etc.

[0170] In this specification, "softener" refers to: a material that imparts plasticity to a rubber component, and is a concept that includes both a softener that is liquid (liquid) at 25°C and a softener that is solid at room temperature (25°C). Examples of softeners include resin components, oils, liquid rubbers, ester plasticizers, and the like. These softeners may be substances derived from petroleum, substances derived from biomass, or substances derived from naphtha recovered from rubber products or non-rubber products. In addition, low molecular weight hydrocarbon components obtained by thermal cracking and extraction of used tires and products containing various components may also be used as softeners. These softeners may be used alone or in combination of two or more.

[0171] (Resin component) The resin component is not particularly limited, and the resin components commonly used in the tire industry can be used, for example, adhesive resins such as C9 resin, C5 resin, C5C9 resin, dicyclopentadiene resin, aromatic vinyl resin, terpene resin, rosin resin, phenol resin, etc. can be listed. These resin components can be used alone or in combination of two or more. The rubber composition involved in this embodiment preferably contains one or more resin components selected from the group consisting of terpene resin, dicyclopentadiene resin and aromatic vinyl resin, and more preferably contains a resin component containing dicyclopentadiene, styrene and indene as monomer components.

[0172] "C9-based resin" refers to a resin obtained by polymerizing a C9 fraction, which may be a resin obtained by polymerizing a C9 fraction alone, or a copolymer obtained by copolymerizing a C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) with a C9 fraction is called a DCPD / C9 resin. In addition, it may also be a hydrogenated product or a modified product thereof. As the C9 fraction, for example, petroleum fractions having 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene may be cited. These C9-based resins may be used alone or in combination of two or more.

[0173] "C5-based resin" refers to a resin obtained by polymerizing a C5 fraction, and may also be a hydrogenated product or a modified product thereof. Examples of the C5 fraction include petroleum fractions corresponding to 4 to 5 carbon atoms such as cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, and pentadiene. These C5-based resins may be used alone or in combination of two or more.

[0174] "C5C9-based resin" refers to a resin obtained by copolymerizing the above-mentioned C5 fraction and the above-mentioned C9 fraction, and may also be a hydrogenated product or a modified product thereof. Examples of C5C9-based petroleum resins include those commercially available from Tosoh Corporation, LUHUA Corporation, etc. These C5C9-based resins may be used alone or in combination of two or more.

[0175] "Dicyclopentadiene resin" refers to a resin containing cyclopentadiene (CPD) or dicyclopentadiene (DCPD), and may also be a hydrogenated product or a modified product thereof. Examples of dicyclopentadiene resins include DCPD / C9 resins containing dicyclopentadiene and the following C9 fraction as monomer components (the DCPD / C9 resins may also be hydrogenated products or modified products thereof), preferably DCPD / C9 resins containing dicyclopentadiene, styrene and indene as monomer components. Examples of dicyclopentadiene resins include commercially available materials from ExxonMobil Corporation, ENEOS Co., Ltd., Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., etc. These dicyclopentadiene resins may be used alone or in combination of two or more.

[0176] “Aromatic vinyl resin” refers to a resin containing aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-chlorostyrene as the monomer component with the largest content, and may also be their hydrogenated products or modified products. As aromatic vinyl resins, for reasons of economy, easy processing, and excellent heat generation, α-methylstyrene or homopolymers of styrene or copolymers of α-methylstyrene and styrene are preferred, and copolymers of α-methylstyrene and styrene are more preferred. As aromatic vinyl resins, for example, commercially available materials from Kraton, Eastman Chemical, Mitsui Chemicals, Inc., etc. can be used. These aromatic vinyl resins can be used alone or in combination of two or more.

[0177] "Terpene resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, dipentene, etc. as monomer components, and may also be hydrogenated products or modified products thereof. Specific examples of terpene resins include, for example, polyterpene resins containing only one or more of the above-mentioned terpene compounds as monomer components; aromatic modified terpene resins containing the above-mentioned terpene compounds and aromatic compounds as monomer components; terpene phenol resins containing the above-mentioned terpene compounds and phenol compounds as monomer components, etc. As aromatic compounds that become monomer components of aromatic modified terpene resins, for example, styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. can be listed. As phenolic compounds that become monomer components of terpene phenol resins, for example, phenol, bisphenol A, cresol, xylenol, etc. can be listed. These terpene resins can be used alone or in combination of two or more.

[0178] "Rosin-based resin" refers to a resin comprising abietic acid, neoabietic acid, palustric acid, isopimaric acid and other rosin acid compounds, which may be hydrogenated products or modified products thereof. Rosin-based resins are not particularly limited, and examples thereof include natural resin rosin, and rosin-modified resins modified by hydrogenation, disproportionation, dimerization, esterification, and the like. These rosin-based resins may be used alone or in combination of two or more.

[0179] "Phenolic resin" refers to a resin containing a phenol compound such as phenol or cresol as the largest monomer component, and may be a hydrogenated product or a modified product thereof. The phenolic resin is not particularly limited, and examples thereof include phenolic resin, alkylphenolic resin, alkylphenolacetylene resin, and oil-modified phenolic resin. These phenolic resins may be used alone or in combination of two or more.

[0180] The softening point of the adhesive resin is preferably 35° C. or higher, more preferably 50° C. or higher, and even more preferably 65° C. or higher. In addition, from the viewpoint of processability and improving the dispersibility of the rubber component and the filler, it is preferably 150° C. or lower, more preferably 140° C. or lower, and even more preferably 130° C. or lower. The softening point of the adhesive resin is measured by the above-mentioned measurement method.

[0181] When the rubber composition constituting the running surface rubber layer contains an adhesive resin, the content of the adhesive resin relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more. In addition, from the viewpoint of suppressing heat generation, it is preferably less than 40 parts by mass, more preferably less than 30 parts by mass, further preferably less than 20 parts by mass, and particularly preferably less than 15 parts by mass. In addition, in the rubber composition constituting the topping rubber, the content of the adhesive resin relative to 100 parts by mass of the rubber component is not particularly limited, but is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, and further preferably less than 10 parts by mass.

[0182] As oil, for example, process oil, vegetable oil, animal oil, etc. can be cited. As process oil, paraffin process oil (mineral oil), cycloparaffin process oil, aromatic process oil, etc. can be cited. As specific examples of process oil, for example, MES (mild extract solvent), DAE (distillate aromatic extract), TDAE (refined distillate aromatic extract), TRAE (treated residual aromatic extract), RAE (residual aromatic extract), etc. can be cited. Due to environmental measures, process oils with a lower content of polycyclic aromatic compounds (PCA) can also be used. As the above-mentioned low PCA content oil, MES, TDAE, heavy cycloparaffin oil, etc. can be cited. In addition, from the perspective of life cycle assessment, oils refined from waste oil used in rubber mixers or engines and waste cooking oil used in restaurants can also be used.

[0183] As vegetable oil, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, Queensland nut oil, peanut oil, grape seed oil, wood wax, etc. can be listed. Further, as vegetable oil, it can also be listed as refined oil (salad oil, etc.) after the above oil is refined, ester exchange oil after the above oil is transesterified, hydrogenated oil after the above oil is hydrogenated, thermally polymerized oil after the above oil is thermally polymerized, oxidatively polymerized oil after the above oil is oxidized, and waste edible oils such as edible oils are recovered after the used oils are recycled. In addition, vegetable oil can be liquid or solid at room temperature (25°C). Vegetable oil can be used alone or in combination of two or more.

[0184] The vegetable oil preferably contains acylglycerols, and more preferably contains triacylglycerols. In addition, in the present specification, acylglycerols refer to compounds in which the hydroxyl group of glycerol forms an ester bond with a fatty acid. There are no particular limitations on the acylglycerols, and it can be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerols can be monomers, dimers, or polymers of trimers or higher. In addition, dimers or higher acylglycerols can be obtained by thermal polymerization, oxidative polymerization, etc. In addition, the acylglycerols can be liquid or solid at room temperature (25°C).

[0185] The method for confirming whether or not the rubber composition contains acylglycerols is not particularly limited, and for example, the following method can be used. 1 Specifically, a rubber composition mixed with triacylglycerol was immersed in deuterated chloroform at room temperature (25°C) for 24 hours, and after removing the rubber composition, the rubber composition was measured at room temperature. 1 H-NMR, when the signal of tetramethylsilane (TMS) is set to 0.00ppm, signals near 5.26ppm, 4.28ppm, and 4.15ppm are observed. It is estimated that these signals are signals from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group, and it can be confirmed that acylglycerol is contained. In addition, "nearby" in this paragraph refers to the range of ±0.10ppm.

[0186] As the above-mentioned fatty acid, there is no particular limitation, and it can be an unsaturated fatty acid or a saturated fatty acid. As unsaturated fatty acids, monounsaturated fatty acids such as oleic acid, polyunsaturated fatty acids such as linoleic acid and linolenic acid can be listed. In addition, as saturated fatty acids, butyric acid, lauric acid, etc. can be listed.

[0187] Among them, as the above-mentioned fatty acid, it is desirable to contain a fatty acid with less double bonds, i.e. a saturated fatty acid or a monounsaturated fatty acid, preferably oleic acid. As the vegetable oil containing such a fatty acid, for example, the vegetable oil contained in a saturated fatty acid or a monounsaturated fatty acid can be used, and the vegetable oil modified by transesterification can also be used. In addition, in order to manufacture the vegetable oil containing such a fatty acid, plants can also be improved by variety improvement, genetic recombination, etc.

[0188] As the vegetable oil, for example, commercially available ones from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Manufacturing Co., Ltd., Fuji Kosan Co., Ltd., Nissin Oillio Group Co., Ltd., etc. can be used.

[0189] Examples of the animal oil include fish oil, beef tallow, and oleyl alcohol derived from these.

[0190] When oil is contained, from the viewpoint of the effect of the present invention, the content of the oil relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more. In addition, the content is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, even more preferably less than 15 parts by mass, and particularly preferably 10 parts by mass or less.

[0191] The liquid rubber is not particularly limited as long as it is a polymer in a liquid state at room temperature (25° C.), and examples thereof include liquid butadiene polymer (liquid BR), liquid isoprene rubber polymer (liquid IR), liquid styrene butadiene copolymer (liquid SBR), liquid styrene isoprene rubber copolymer (liquid SIR), and polymers containing myrcene or farnesene. These liquid polymers may be used alone or in combination of two or more.

[0192] When a liquid polymer is contained, its content relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 3 parts by mass or more. In addition, the content is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, and further preferably less than 10 parts by mass.

[0193] As the ester plasticizer, for example, dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), trixyl phosphate (TXP), etc. The ester plasticizer may be used alone or in combination of two or more.

[0194] From the viewpoint of the effects of the present invention, the content of the softener relative to 100 parts by mass of the rubber component (the total amount of all softeners when multiple softeners are used in combination) is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more. In addition, the content is preferably 70 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 35 parts by mass or less, and particularly preferably 25 parts by mass or less.

[0195] The antioxidant is not particularly limited, and examples thereof include naphthylamine antioxidants such as phenyl-α-naphthylamine; diphenylamine antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditolyl p-phenylenediamine antioxidants such as DTPD, N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroxyquinoline; monophenol antioxidants such as 2,6-di-tert-butyl-4-methylphenol and styrenated phenol; di-, tri-, and polyphenol antioxidants such as tetrakis-[methylene-3-(3,5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane, etc. Among them, p-phenylenediamine antioxidants and quinoline 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. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flexis Co., Ltd., etc. These antioxidants may be used alone or in combination of two or more.

[0196] When containing an antioxidant, from the viewpoint of the ozone cracking resistance of the rubber, the content of the antioxidant relative to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and further preferably 1.5 parts by mass or more. In addition, from the viewpoint of wear resistance, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0197] As wax, there is no particular limitation, and any one of the substances commonly used in the tire industry can be preferably used. For example, petroleum wax, mineral wax, synthetic wax, wax derived from plants, etc. can be listed. Among them, petroleum wax and wax derived from plants are preferred, and petroleum wax is more preferred. As wax derived from plants, for example, rice bran wax, carnauba wax, candelilla wax, etc. can be listed. As petroleum wax, for example, paraffin wax, microcrystalline wax, their selected special waxes, etc. can be listed, preferably paraffin wax. In addition, the wax involved in the present embodiment is set to be a wax that does not contain stearic acid. Regarding wax, for example, commercially available substances by Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seira Co., Ltd., Paramelt Co., Ltd., etc. can be used. These waxes can be used alone or in combination of two or more.

[0198] When wax is contained, the content of wax is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, based on 100 parts by mass of the rubber component, from the viewpoint of weather resistance of the rubber. Furthermore, from the viewpoint of preventing tire whitening due to blooming, the content of wax is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0199] As processing aids, for example, fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, mixtures of fatty acid metal salts and fatty acid amides, etc. can be cited. As processing aids, for example, commercially available substances from Schill+Seilacher, Performance-Additives, etc. can be used. These processing aids can be used alone or in combination of two or more.

[0200] When stearic acid is contained, the content of stearic acid relative to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and further preferably 1.5 parts by mass or more from the viewpoint of processability. In addition, from the viewpoint of vulcanization speed, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0201] When the rubber composition constituting the topping rubber contains zinc oxide, from the viewpoint of the effect of the present invention, the content of zinc oxide relative to 100 parts by mass of the rubber component is preferably 1.0 parts by mass or more, more preferably 2.0 parts by mass or more, further preferably 3.0 parts by mass or more, and particularly preferably 4.0 parts by mass or more. In addition, from the viewpoint of wear resistance, it is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and further preferably 9 parts by mass or less.

[0202] When the rubber composition constituting the tread rubber layer contains zinc oxide, the amount of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, relative to 100 parts by mass of the rubber component from the viewpoint of processability. In addition, from the viewpoint of wear resistance, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0203] As the vulcanizing agent, sulfur can be preferably used. As the sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, etc. can be used.

[0204] When the rubber composition constituting the topping rubber contains sulfur, from the viewpoint of the effect of the present invention, the content of sulfur relative to 100 parts by mass of the rubber component is preferably 1.0 parts by mass or more, more preferably 2.0 parts by mass or more, further preferably 3.0 parts by mass or more, further preferably 4.0 parts by mass or more, and particularly preferably 5.0 parts by mass or more. In addition, from the viewpoint of preventing deterioration, it is preferably 10.0 parts by mass or less, more preferably 9.0 parts by mass or less, and further preferably 8.0 parts by mass or less. In addition, when oil-containing sulfur is used as a crosslinking agent, the content of the vulcanizing agent is set to the total content of pure sulfur contained in the oil-containing sulfur.

[0205] When the rubber composition constituting the cap rubber layer contains sulfur, the content thereof is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more relative to 100 parts by mass of the rubber component from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less.

[0206] As a vulcanizing agent other than sulfur, a known organic crosslinking agent may also be used. As an organic crosslinking agent, as long as it is a substance that can form a crosslinked chain other than a polysulfide bond, there is no particular limitation, for example, alkylphenol / sulfur chloride condensate, hexamethylene-1,6-sodium dithiosulfate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyl dithio)hexane, diisopropylbenzene peroxide, etc., preferably hexamethylene-1,6-sodium dithiosulfate dihydrate. These organic crosslinking agents can use commercially available substances such as Tiangang Chemical Industry Co., Ltd., Lanxess Co., Ltd., and Flexis Company.

[0207] When the rubber composition constituting the topping rubber contains a vulcanizing agent other than sulfur (preferably sodium hexamethylene-1,6-dithiosulfate dihydrate), from the viewpoint of the effect of the present invention, the content of the vulcanizing agent other than sulfur relative to 100 parts by mass of the rubber component is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and further preferably 1.0 parts by mass or more. On the other hand, the content is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and further preferably 3.0 parts by mass or less.

[0208] As the vulcanization accelerator, there is no particular limitation, and for example, sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, guanidine vulcanization accelerators, thiuram vulcanization accelerators, thiourea vulcanization accelerators, dithiocarbamate vulcanization accelerators, aldehyde-amine vulcanization accelerators, aldehyde-ammonia vulcanization accelerators, imidazoline vulcanization accelerators, xanthate vulcanization accelerators, caprolactam disulfide, etc. can be listed. One of these vulcanization accelerators can be used alone, or two or more can be used in combination. Among them, from the point of view of being able to better obtain the desired effect, it is preferably a vulcanization accelerator selected from the group consisting of sulfenamide vulcanization accelerators, thiazole vulcanization accelerators and guanidine vulcanization accelerators.

[0209] Examples of the sulfenamide vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS).

[0210] Examples of the thiazole vulcanization accelerator include 2-mercaptobenzothiazole (MBT) or a salt thereof, di-2-benzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, and 2-(2,6-diethyl-4-morpholinothio)benzothiazole. Among them, MBTS and MBT are preferred, and MBTS is more preferred.

[0211] As guanidine vulcanization accelerators, for example, 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of di-orthocatechol borate, 1,3-di-o-cumylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumyl-2-propionylguanidine, etc. can be cited. Among them, DPG is preferred. Among them, when the rubber composition constituting the topping rubber contains a guanidine vulcanization accelerator, from the viewpoint of the effect of the present invention, the content of the guanidine vulcanization accelerator relative to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or less, more preferably 0.3 parts by mass or less, further preferably 0.1 parts by mass or less, and particularly preferably no guanidine vulcanization accelerator is contained.

[0212] When a vulcanization accelerator is contained, the content of the vulcanization accelerator is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and further preferably 1.5 parts by mass or more relative to 100 parts by mass of the rubber component from the viewpoint of ensuring a sufficient vulcanization rate. In addition, from the viewpoint of suppressing blooming, the content of the vulcanization accelerator is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0213] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) can also be derived from carbon dioxide in the atmosphere. As a method for obtaining these various materials from carbon dioxide, carbon dioxide can be directly converted, or methane obtained through a methanation step of synthesizing methane from carbon dioxide can be converted.

[0214] [Manufacture of rubber composition and tire] The rubber composition according to the present embodiment can be produced by a known method, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll mill or a closed mixer (Banbury mixer, kneader, etc.).

[0215] The kneading step includes, for example, a basic kneading step of kneading a compounding agent and an additive other than a vulcanizing agent and a vulcanization accelerator, and a final kneading (F kneading) step of adding a vulcanizing agent and a vulcanization accelerator to the kneaded product obtained in the basic kneading step and kneading. Furthermore, the basic kneading step may be decomposed into a plurality of steps as required.

[0216] The kneading conditions are not particularly limited, and examples thereof include a method in which kneading is performed at a discharge temperature of 150 to 170° C. for 3 to 10 minutes in the basic kneading step and kneading is performed at 70 to 110° C. for 1 to 5 minutes in the final kneading step.

[0217] The tire of the present embodiment, which has a topping rubber and a running surface rubber layer composed of the above-mentioned rubber composition, can be manufactured by a conventional method using the corresponding rubber composition. That is, the steel cord is covered with an unvulcanized rubber composition corresponding to the topping rubber to obtain a steel cord-rubber composite. Then, the unvulcanized rubber composition corresponding to the running surface rubber layer can be extruded and processed according to the shape of the running surface rubber layer using an extruder with a die of a specified shape, and is bonded together with other tire components on a tire molding machine and molded using a conventional method to form an unvulcanized tire, and the unvulcanized tire is heated and pressurized in a vulcanizer to manufacture the tire. The vulcanization conditions are not particularly limited, and for example, a method of vulcanizing at 150 to 200° C. for 10 to 30 minutes can be cited.

[0218] <Purpose> The tires involved in this embodiment can be used as general-purpose tires such as passenger car tires, truck and bus tires, and two-wheeled vehicle tires, and can also be used as racing tires. In addition, passenger car tires are tires that are installed on a four-wheeled vehicle as a prerequisite, and refer to tires whose maximum load capacity is less than 1000kg. In addition, the tires involved in this embodiment can be used for all-season tires, summer tires, winter tires such as studless tires, etc. [Example]

[0219] The following are examples (embodiments) that are considered to be preferred when implemented, but the scope of the present invention is not limited to the embodiments. Using the various chemicals shown below, a tire having a steel cord covered with a topping rubber obtained according to the formulation of Table 1 and a running surface rubber layer obtained according to the formulation of Table 2 was studied, and the results were calculated based on the following evaluation method, and the calculated results are shown in Tables 3 to 7.

[0220] The following summarizes various chemicals used in Examples and Comparative Examples. NR:TSR20 BR: UBEPOL BR (registered trademark) 150B manufactured by Ube Industries, Ltd. (unmodified BR, cis content: 97% by mass, Mw: 440,000) SBR: SBR1502 manufactured by JSR Corporation (unmodified E-SBR, styrene content: 23.5% by mass, vinyl content: 18 mol%, Mw: 420,000) Carbon black 1: SHOBLACK N330 (N2SA: 75m 2 / g, average primary particle size: 30nm) Carbon black 2: SHOBLACK N220 (N2SA: 115m 2 / g, average primary particle size: 22nm) Carbon black 3: SS550 manufactured by Streble Green Carbon (recycled carbon black obtained by thermal cracking of tires) Silicon dioxide: ULTRASIL VN3 (N2SA: 175m 2 / g) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Thermosetting resin: SUMILITERESIN PR-12686E manufactured by Sumitomo Bakelite Co., Ltd. (cashew nut oil-modified phenolic resin, softening point: 100°C) Curing agent: SUMIKANOL 507AP (modified etherified methylol melamine resin) manufactured by Taoka Chemical Industry Co., Ltd. Oil: Diana Process NH-70S (aromatic process oil) manufactured by Idemitsu Kosan Co., Ltd. Adhesive resin 1: SYLVATARAXX4150 manufactured by Kraton Corporation (polyterpene resin, softening point: 115°C) Adhesive resin 2: Oppera PR-395 manufactured by ExxonMobil Corporation (hydrogenated DCPD / C9 resin, softening point: 118°C) Zinc oxide: Zinc Hua No. 1 manufactured by Mitsui Mining and Smelting Co., Ltd. Antioxidant 1: NOCRAC 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant 2: NOCRAC FR (2,2,4-trimethyl-1,2-dihydroquinoline polymer) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Cobalt compound: Cost-F (cobalt stearate) manufactured by DIC Corporation Stearic acid: TSUBAKI stearic acid beads manufactured by NOF Corporation Wax: OZOACE 0355 manufactured by Nippon Seiro Co., Ltd. Vulcanizing agent 1: M95 (insoluble sulfur) manufactured by Japan Kanto Industry Co., Ltd. Curing agent 2: DURALINK HTS (sodium hexamethylene-1,6-dithiosulfate dihydrate) manufactured by Flexis Vulcanizing agent 3: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. (powdered sulfur containing 5% oil) Vulcanization accelerator 1: NOCCELLER DZ (N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: NOCCELLER CZ (N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 3: NOCCELLER D (1,3-diphenylguanidine (DPG) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)

[0221] (Examples and Comparative Examples) According to the formulations shown in Tables 1 and 2, a 1.7L closed Banbury mixer was used to mix chemicals other than sulfur and vulcanization accelerators for 5 minutes until the discharge temperature reached 160°C to obtain a kneaded product. Then, sulfur and vulcanization accelerators were added to the obtained kneaded product using an open roll mill, and kneaded for 4 minutes until it reached 105°C, and kneaded to obtain an unvulcanized rubber composition. The unvulcanized rubber composition obtained in Table 1 was used to cover steel cords (single wire diameter: 0.30mm) to obtain a steel cord-rubber composite. Then, the unvulcanized rubber composition in Table 2 was extruded and processed according to the shape of the running surface rubber layer using an extruder with a die of a specified shape, and was laminated together with other tire components on a tire molding machine to produce an unvulcanized tire, which was vulcanized at 170°C to obtain the test tires described in Tables 3 to 7. Here, in the two-element plated steel cord, the average thickness of the plated layer is 0.24 μm, and the composition of the plated layer is 63 mass % Cu and 37 mass % Zn, and in the three-element plated steel cord, the average thickness of the plated layer is 0.19 μm, and the composition of the plated layer is 68 mass % Cu, 28 mass % Zn, and 4 mass % Co. In addition, in the composition of the steel cord in the table, "1×2 40e" means that the steel cord of the 1×2 structure has 40 ends per 50 mm width in the direction perpendicular to the longitudinal direction of the steel cord, and "1×1 80e" means that the monofilament steel cord of the 1×1 structure has 80 ends per 50 mm width in the direction perpendicular to the longitudinal direction of the steel cord.

[0222] <Measurement of tanδ1 at 70℃ and E*1 at 70℃> For each vulcanized rubber test piece prepared by cutting a 20 mm long × 4 mm wide × 1 mm thick piece from the topping rubber covering the steel cord of each test tire with the long side in the tire circumferential direction and the thickness direction in the tire radial direction, a dynamic viscoelasticity measuring apparatus (EPLEXOR series manufactured by GABO Corporation) was used to measure the loss tangent tanδ and the complex elastic modulus E* under the conditions of temperature 70°C, frequency 10 Hz, initial strain 10%, dynamic strain ±1%, and tensile mode.

[0223] <Measurement of tanδ2 at 30℃ and tanδ2 at 0℃> For each vulcanized rubber test piece prepared by cutting a length of 20 mm × width of 4 mm × thickness of 1 mm from the inside of the running surface rubber layer of the tread portion of each test tire with the tire circumferential direction as the long side and the tire radial direction as the thickness direction, a dynamic viscoelasticity measuring device (EPLEXOR series manufactured by GABO Co., Ltd.) was used to measure the length loss tangent tanδ under the conditions of temperature 30°C, frequency 10 Hz, initial strain 5%, dynamic strain ±1%, and tensile mode. In addition, the loss tangent tanδ was measured under the conditions of temperature 0°C, frequency 10 Hz, initial strain 10%, dynamic strain ±2.5%, and tensile mode.

[0224] <Peel test> A sample piece with a width of 25 mm is cut from the belt layer including the equatorial part of the tire in the axial direction of the tire. Furthermore, the sample piece is placed in an oven at a temperature of 80°C and a relative humidity of 90% for one week to deteriorate it by moisture and heat. Using a peeling tester, the peeling resistance of the obtained sample piece when it is peeled off from one end along the belt layer at a speed of 50 mm / min is measured. In addition, the results are expressed as "durability performance" using the peeling resistance of the benchmark comparative examples (Comparative Example 4 in Table 3, Comparative Example 8 in Table 4, Comparative Example 13 in Table 5, Comparative Example 17 in Table 6, and Comparative Example 21 in Table 7) as an index of 100.

[0225]

Table 1

[0226]

Table 2

[0227]

Table 3

[0228]

Table 4

[0229]

Table 5

[0230]

Table 6

[0231]

Table 7

[0232] <Implementation Method> Examples of embodiments of the present invention are shown below.

[0233] [1] A tire comprising a tread portion and a belt layer, wherein the tread portion has at least one rubber layer, the belt layer has steel cords and a topping rubber covering the steel cords, a running surface rubber layer constituting the tread of the tread portion and the topping rubber are respectively composed of a rubber composition containing a rubber component and a filler, the topping rubber has a complex elastic modulus (70°C E*1) at 70°C of 15.0 MPa or less, preferably 12.0 MPa or less, more preferably 12.0 MPa or less, and further preferably 8.0 MPa or less, and the maximum load capacity of the tire is set to W L (kg), when the tanδ of the topping rubber at 70°C is set to tanδ1 at 70°C, W L And tanδ1 at 70°C satisfies the following formula (1). 9.33×10 -5 ×W L -70℃tanδ1>0.023…(1) [2] The tire according to [1], wherein the filler contained in the rubber composition constituting the topping rubber includes silica. [3] The tire according to [1] or [2], wherein the filler contained in the rubber composition constituting the topping rubber includes regenerated carbon black. [4] The tire according to any one of [1] to [3], wherein the content of carbon black in the rubber composition constituting the cap rubber layer is 20 parts by mass or less per 100 parts by mass of the rubber component. [5] The tire according to any one of [1] to [4], wherein the cap rubber layer has a tan δ at 30°C (tan δ2 at 30°C) of 0.16 or less. [6] A tire according to any one of [1] to [5], wherein when the tanδ of the running surface rubber layer at 30°C is set to 30°C tanδ2 and the tanδ of the running surface rubber layer at 0°C is set to 0°C tanδ2, 0°C tanδ2 / 30°C tanδ2 is greater than 2.3. [7] The tire according to any one of [1] to [6], wherein the total amount of styrene in the rubber component constituting the cap rubber layer is 15% by mass or less, preferably 13% by mass or less. [8] The tire according to any one of [1] to [7], wherein W L It is 400 or more, preferably 500 or more, more preferably 600 or more, and further preferably 700 or more. [9] The tire according to any one of [1] to [8], wherein the steel cord is a single-wire monofilament cord.

[10] The tire according to any one of [1] to [9], wherein the cross-sectional area of ​​the steel cord is S (mm 2 ), when the number of the steel cords in every 50 mm width in a direction perpendicular to the length direction of the steel cord is set to E, S×E is greater than 1.0 and less than 25, preferably greater than 2.0 and less than 20, more preferably greater than 3.0 and less than 15, and further preferably greater than 4.0 and less than 10.

[11] A tire according to any one of [1] to

[10] , wherein, in the rubber composition constituting the topping rubber, when the content of silica relative to 100 parts by mass of the rubber component is set to Y (parts by mass), Y / (S×E) is greater than 0.10, preferably greater than 0.50, and more preferably greater than 1.0.

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

[11] , wherein the steel cord has a ternary plating layer composed of copper, zinc, and cobalt.

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

[12] , wherein, when the weight of the tire is G (kg), G / W L It is 0.060 or less, preferably 0.025 or less, and more preferably 0.020 or less.

Claims

1. A tire comprising a tread portion and a belt layer, characterized in that: The tread portion has at least one rubber layer, The belt layer comprises steel cords and topping rubber covering the steel cords. The cap rubber layer constituting the tread of the tread portion and the topping rubber are respectively composed of a rubber composition containing a rubber component and a filler. The complex elastic modulus of the topping rubber at 70°C, i.e., 70°C E*1, is 15.0 MPa or less, The maximum load capacity of the tire is set as W L , when the tanδ of the topping rubber at 70℃ is set to 70℃tanδ1, W L and tanδ1 at 70℃ satisfies the following formula (1), 9.33×10 -5 ×W L -70℃tanδ1>0.023……(1), The W L The unit is kg.

2. The tire according to claim 1, wherein: The filler contained in the rubber composition constituting the topping rubber includes silica.

3. The tire according to claim 1 or 2, wherein: The filler contained in the rubber composition constituting the topping rubber includes regenerated carbon black.

4. The tire according to claim 1 or 2, wherein: In the rubber composition constituting the cap rubber layer, the content of carbon black is 20 parts by mass or less per 100 parts by mass of the rubber component.

5. The tire according to claim 1 or 2, wherein: The tread rubber layer has a tan δ at 30° C., that is, a 30° C. tan δ2 of 0.16 or less.

6. The tire according to claim 1 or 2, wherein: When the tan δ of the cap rubber layer at 30°C is set to 30°C tan δ2 and the tan δ of the cap rubber layer at 0°C is set to 0°C tan δ2, 0°C tan δ2 / 30°C tan δ2 is greater than 2.

3.

7. The tire according to claim 1 or 2, wherein: The total amount of styrene in the rubber component constituting the cap rubber layer is 15% by mass or less.

8. The tire according to claim 1 or 2, wherein: W L More than 400.

9. The tire according to claim 1 or 2, wherein: The steel cord is a single-wire monofilament cord.

10. The tire according to claim 1 or 2, wherein: When the cross-sectional area of ​​the steel cord is S and the number of the steel cords per 50 mm width in a direction perpendicular to the longitudinal direction of the steel cord is E, S×E is 1.0 or more and 25 or less, and the unit of S is mm 2 .

11. The tire according to claim 10, wherein: In the rubber composition constituting the topping rubber, when the content of silica per 100 parts by mass of the rubber component is represented by Y, Y / (S×E) is 0.10 or more, and the unit of Y is parts by mass.

12. The tire according to claim 1 or 2, wherein: The steel cord has a ternary plating layer consisting of copper, zinc and cobalt.

13. The tire according to claim 1 or 2, wherein: When the weight of the tire is G, G / W L It is less than 0.060, and the unit of G is kg.

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