tire

Abstract

To provide a tire that can improve the overall performance of fuel efficiency and durability. [Solution] A tire comprising a belt layer and a sponge member on the radially inner side of the tread portion, wherein the belt layer has a steel cord consisting of 1 to 4 filaments and a topping rubber covering the steel cord, the topping rubber is made of a rubber composition containing rubber components, and the density D of the sponge member is 20 kg / m³ 3 The cord diameter of the steel cord is less than R (mm), and the maximum load capacity of the tire is W. L (kg) M = R / W L ×10 4 If defined as such, a tire where M is greater than 2.5 and D / M is less than 7.0.

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] In order to improve the low fuel consumption performance of a tire, weight reduction of tire members is desired. Patent Document 1 describes a tire in which a steel cord having a filament diameter of 0.15 to 0.26 mm and a filament number of 5 to 7 is embedded in a belt layer, achieving both durability and weight reduction in a high dimension.

[0003] On the other hand, in order to improve the sound insulation performance of a tire, etc., a sound insulating body such as a sponge member may be attached to the tire. Such a sound insulating body is required to have a performance of deforming flexibly following the deformation of the tire in order to prevent its damage.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a tire capable of improving the overall performance of low fuel consumption performance and durability performance.

Means for Solving the Problems

[0006] The present invention is a tire provided with a belt layer and a sponge member on the inner side in the tire radial direction of a tread portion, the belt layer having a steel cord composed of 1 to 4 filaments and a topping rubber covering the steel cord, the topping rubber being composed of a rubber composition containing a rubber component, and the density D of the sponge member being 20 kg / m 3The cord diameter of the steel cord is less than R (mm), and the maximum load capacity of the tire is W. L (kg) M = R / W L ×10 4 This definition applies to tires where M is greater than 2.5 and D / M is less than 7.0. [Effects of the Invention]

[0007] According to the present invention, a tire is provided that can improve the overall performance of fuel efficiency and durability. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view of a tire relating to one embodiment of the present invention. [Figure 2] This figure schematically shows the belt layer according to this embodiment. [Figure 3] This diagram schematically shows the belt layer near the center of the tire. [Figure 4] This is a perspective view of one example of a single-strand steel cord configuration. [Modes for carrying out the invention]

[0009] One embodiment of the present invention is a tire comprising a belt layer and a sponge member on the radially inner side of the tread portion, wherein the belt layer has a steel cord consisting of 1 to 4 filaments and a topping rubber covering the steel cord, the topping rubber is made of a rubber composition containing a rubber component, and the density D of the sponge member is 20 kg / m³ 3 The cord diameter of the steel cord is less than R (mm), and the maximum load capacity of the tire is W. L (kg) M = R / W L ×10 4 If defined as such, it is a tire where M is greater than 2.5 and D / M is less than 7.0.

[0010] Although not intending to be bound by theory, the reasons for the improved durability performance of the tire of the present invention are considered as follows.

[0011] (1) By setting the number of filaments of the steel cord in the belt layer to 4 or less, the tire can be lightened, but there is a concern that the durability performance may decrease. The value of M obtained by the ratio of the cord diameter R of the steel cord to the maximum load capacity W of the tire L is set within the above-mentioned predetermined range, which is considered to contribute to suppressing the decrease in durability performance.

[0012] (2) On the other hand, when the number of filaments of the steel cord is small, the movement of the steel cord becomes large, so the sponge member also moves greatly following it, and there is a concern about the decrease in the durability performance of the sponge member. Therefore, by setting the density D of the sponge member and the value of D / M within the above-mentioned predetermined range, it is considered to contribute to suppressing the decrease in the durability performance of the sponge member.

[0013] By the cooperation of the above (1) and (2), in the tire with a sponge member, it is considered that a remarkable effect is achieved in that while maintaining the durability performance of the sponge member, the fuel efficiency performance is improved by lightening the tire.

[0014] The steel cord preferably has a 1×1 structure or a 1×4 structure.

[0015] With such an aspect, the coating amount of topping rubber can be reduced while maintaining the durability performance of the tire, so it is considered that the fuel efficiency performance is further improved by lightening the tire.

[0016] When the number of arrangements per 50 mm in the tire width direction of the steel cord is E, D / E is preferably less than 0.17.

[0017] If the number of steel cords arranged E is small, the movement of the steel cords increases, which improves the durability of the tire. However, the sponge material also moves more in response, raising concerns about a decrease in the durability of the sponge material. It is believed that setting D / E within the aforementioned range can suppress the decrease in the durability of the sponge material.

[0018] When the bending stiffness of the steel cord is expressed as Fr (g·cm), it is preferable that D / Fr is less than 1.7.

[0019] If the bending stiffness Fr of the steel cord is small, the movement of the steel cord increases, which improves the durability of the tire. However, the sponge member also moves more in response, raising concerns about a decrease in the durability of the sponge member. It is believed that setting D / E within the aforementioned range can suppress the decrease in the durability of the sponge member.

[0020] The cobalt element content in the aforementioned rubber composition per 100 parts by mass of rubber component is 2.85 × 10⁻⁶, from the viewpoint of suppressing a decrease in durability performance. -3 It is preferable that the amount is less than or equal to parts by mass.

[0021] The rubber composition preferably contains silica.

[0022] By incorporating silica into the topping rubber, the rigidity of the topping rubber in the micro-deformation region can be reduced, which is expected to improve adhesion to the steel cord topping rubber and further enhance the tire's durability.

[0023] The steel cord preferably has a ternary plating layer consisting of copper, zinc, and cobalt.

[0024] By employing a ternary plating process, cobalt, which has a higher ionization tendency than copper, is preferentially leached out. This is thought to suppress the expansion of the adhesive layer due to copper leaching after humid heat degradation, thereby maintaining high adhesive strength.

[0025] The belt layer comprises a first belt ply and a second belt ply laminated on the radially outer side of the first belt layer. When the shortest distance between the steel cords of the second belt ply and the steel cords of the first belt ply at the center of the tire is a, and the shortest distance between the steel cords at the outermost end of the second belt ply and the cords of the first belt ply is b, it is preferable that b / a is 1.5 or greater. It is believed that setting b / a within the above range contributes to improving the durability performance at the belt ends.

[0026] Preferably, the distance from the upper and lower surfaces of the first belt ply to the cord in the tire center and the distance from the upper and lower surfaces of the second belt ply to the cord in the tire center are both 0.14 mm or less. This configuration is thought to contribute to improved fuel efficiency.

[0027] The tire according to this embodiment preferably includes electronic components.

[0028] The tire according to this embodiment can be suitably used as a tire for electric vehicles, a tire for hybrid vehicles, or a tire for plug-in hybrid vehicles.

[0029] In this specification, numerical values ​​accompanied by "greater than or equal to," "greater than," "less than or equal to," or "less than" relating to the boundaries of a numerical range can be arbitrarily combined to constitute a numerical range, as long as it does not contradict the spirit of the present invention. Furthermore, these numerical values ​​can also be combined with the numerical values ​​in the examples as their upper or lower limits to constitute a numerical range. When a numerical range thus constructed is shown as including a boundary value, it can be interpreted, as long as it does not contradict the spirit of the present invention, to simultaneously show a numerical range that does not include that boundary value, in an arbitrarily selectable manner. Therefore, for example, a numerical range shown as including both boundary values ​​at both ends can be interpreted, as long as it does not contradict the spirit of the present invention, to show a numerical range that does not include either one of the boundary values, or a numerical range that does not include either boundary value. Also, a numerical range shown as including only one boundary value and not including the other boundary value can be interpreted, as long as it does not contradict the spirit of the present invention, to show a numerical range that does not include either boundary value.

[0030] <Definition> The "tread portion" is the part that forms the contact surface of the tire, and in the radial cross-section of the tire, if the tire has components that form the tire skeleton using steel or textile materials such as belt layers, belt reinforcement layers, and carcass layers, the tread portion is the component that is radially outward from these components.

[0031] The "belt layer" is one of the reinforcing layers and consists of at least one belt ply. The multiple belt cords constituting the belt ply are arranged approximately parallel to each other, and the direction of extension of the belt cords is inclined at 10° or more with respect to the tire circumferential direction. The belt has joints on the circumference of the tire. Here, "approximately parallel" means that the angle difference between the direction of extension of each belt cord and the tire circumferential direction is within ±3°.

[0032] A "band" is one of the reinforcing layers and consists of at least one band ply. The band cords that make up the band ply are arranged in a spiral winding in the circumferential direction of the tire, and the direction of extension of the band cords is kept within an inclination of 5° or less relative to the circumferential direction of the tire. The band does not have any joints on the circumference of the tire.

[0033] "Standard condition" refers to a state of no load where the tire is mounted on a standard rim and filled with air at the standard internal pressure. Unless otherwise specified, tires in the standard condition should be used.

[0034] Unless otherwise specified, the "dimensions of each part of the tire" refer to values ​​that are determined in the normal state for those visible on the outer surface of the tire, while those located inside the tire or on the cut surface of the tire refer to values ​​that are determined, for example, by cutting the tire in a plane including the tire's axis of rotation and holding the cut tire piece within the rim width of the normal rim.

[0035] A "standard rim" refers to the rim specified for each tire within the standards system that the tire is based on. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." Refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. In the case of a tire not specified in the above standards, it refers to the narrowest rim width among the smallest diameter rims that can be mounted on that tire and that can maintain internal pressure (i.e., do not cause air leakage between the rim and tire).

[0036] "Regular internal pressure" refers to the air pressure specified for each tire in the standards system, including the standard on which the tire is based. For example, for JATMA it refers to "maximum air pressure," for ETRTO it refers to "INFLATION PRESSURE," and for TRA it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims, refer to JATMA, ETRTO, and TRA in that order, and if there is an applicable size at the time of reference, follow that standard. In the case of tires not specified in the above standards, it refers to the regular internal pressure (but at least 250kPa) of another tire size (but specified in the standard) that is listed with the aforementioned regular rim as the standard rim. If multiple regular internal pressures of 250kPa or higher are listed, refer to the lowest value among them.

[0037] "Regular load (kg)" refers to the load specified for each tire in the standard system that the tire is based on. For example, for JATMA it is "Maximum Load Capacity," for ETRTO it is "LOAD CAPACITY," and for TRA it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims and regular in-tire pressure, refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. For tires not specified in the above standards, the maximum load capacity (kg) is calculated separately. L This is considered the normal load.

[0038] "Maximum load capacity W L The weight (kg) is calculated using the following formula: "V" is the virtual volume of the tire (mm²). 3), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the height of the tire's cross-section in the radial direction in a plane containing the tire's axis of rotation (mm), and "Wt" is the width of the tire's cross-section in the normal state (mm). Ht can be calculated by (Dt-R) / 2, where R is the rim diameter of the tire. Wt is the value obtained by removing any patterns or letters on the tire's sidewall. Note that the maximum load capacity is synonymous with the normal load mentioned above.

[0039]

number

[0040] The term "tire center section" refers to the portion of the tire located within a distance of 1 / 4 of the tire contact patch width from the tire's equatorial plane in the tire's width direction.

[0041] A "filament" is a strand of wire that makes up a steel cord.

[0042] "Rubber components of a rubber composition" refer to components that contribute to crosslinking within a rubber composition, and generally have a weight-average molecular weight (Mw) of 10,000 or more.

[0043] A "plasticizer" is a material that imparts plasticity to rubber components and is extracted from rubber compositions using acetone. Plasticizers include those that are liquid at 25°C and those that are solid at 25°C. However, waxes and stearic acid commonly used in the tire industry are excluded.

[0044] "Plasticizer content" includes the amount of plasticizer contained in the extensible rubber component that has been pre-stretched with plasticizers such as oil, resin components, and liquid rubber components. The same applies to the oil content, resin component content, and liquid rubber content; for example, if the extensible component is oil, the extensible oil is included in the oil content.

[0045] <Measurement method> "Sponge material density D" refers to the "apparent density" measured in accordance with JIS K 7222:2005. The unit is kg / m 3 That is the case.

[0046] The "cord diameter R of steel cord" refers to the diameter of the filament if the steel cord is a single-wire monofilament cord, or the diameter of the circumscribed circle of the filament assembly if the steel cord is composed of multiple twisted filaments. The unit is mm.

[0047] The bending stiffness Fr of a steel cord is determined using a stiffness testing machine (for example, a TABER 150-D model). A 145mm steel cord is clamped at both ends, and the bending angles of the cord are applied at +15 degrees and -15 degrees. The average of the bending moments at +15 degrees and -15 degrees is used to determine the stiffness. The unit is g·cm.

[0048] The "average thickness of the plating layer" is measured in accordance with JIS H 8501:1999.

[0049] The nitrogen adsorption specific surface area (N2SA) of carbon black is measured in accordance with JIS K 6217-2:2017.

[0050] The nitrogen adsorption specific surface area (N2SA) of silica is measured by the BET method in accordance with ASTM D3037-93.

[0051] The "average primary particle diameter" is a value obtained by photographing particles with a transmission or scanning electron microscope and taking the arithmetic mean of the particle diameters of 400 particles. If the particle shape is spherical, the diameter of the sphere is used as the particle diameter; if it is not spherical, the equivalent diameter of a circle (the positive square root of {4 × (particle area) / π}) is calculated from the microscope image and used as the particle diameter. The average primary particle diameter is applied to silica, carbon black, and other materials.

[0052] The procedure for manufacturing a tire, which is one embodiment of the present invention, will be described in detail below. However, the following description is illustrative for explaining the present invention and is not intended to limit the technical scope of the present invention to this scope only.

[0053] <Tires> The tire according to this embodiment includes a belt layer and a sponge member on the radially inner side of the tread portion. The belt layer has a steel cord consisting of 1 to 4 filaments and a topping rubber covering the steel cord. The tire according to one embodiment of the present invention will be described below with reference to the drawings, but the drawings are for illustrative purposes only. Furthermore, the embodiments shown below are merely examples.

[0054] Figure 1 shows a cross-sectional view of the tire 11 according to this embodiment, with respect to the plane passing through the tire rotation axis. Although Figure 1 only shows the portion to the right of CL (tire centerline), the same structure is continuously present to the left of CL, with CL as the axis of symmetry.

[0055] As shown in Figure 1, the tire 11 comprises a tread portion 1, a sidewall 32, a bead portion 33, a carcass 34, a belt layer 7, a band 36, and a sponge member 39. The bead portion 33 includes a bead core 31.

[0056] The belt layer 7 has a first belt ply 5 and a second belt ply 6 laminated on the radially outer side of the first belt ply 5, but the number of layers is not particularly limited and can be arbitrarily selected. The band 36 is formed by an edge band 61 that covers only the edge portion of the belt 35 and a full band 62 that covers the entire area of ​​the belt 5, but is not limited to this configuration.

[0057] The tread portion 1 may be a tread portion consisting of a single rubber layer, or it may be a tread portion having a cap rubber layer that constitutes the tread surface, and one or more rubber layers existing between the cap rubber layer and the band 36.

[0058] The tire 11 preferably includes electronic components (not shown). Examples of electronic components include a wireless tag equipped with a sensor for detecting the internal state of the tire, such as tire pressure, and a recording unit for unique tire identification information.

[0059] (Sponge material) The tire according to this embodiment includes a sponge member. The position of the sponge member in the tire is not limited as long as it is on the radial side of the tread portion 1, but it is preferable that it is fixed to the inner surface 15 of the tire along the circumferential direction of the tire. The sponge member 39 is preferably a long strip having a bottom surface fixed to the inner surface 15 of the tire. In this case, the outer ends in the circumferential direction may be butted together to form a substantially annular shape, or the outer ends may be spaced apart in the circumferential direction.

[0060] The sponge member 39 has substantially the same cross-sectional shape at each position in the circumferential direction, excluding the outer end. To prevent tilting and deformation during driving, a flat, elongated cross-sectional shape with a height smaller than the width in the tire axial direction is preferred.

[0061] The sponge member 39 preferably has grooves 37 that extend continuously in the circumferential direction on the inner surface side in the radial direction of the tire. It is believed that providing grooves 37 increases the surface area of ​​the sponge member 39, allowing it to absorb more resonance energy and improve heat dissipation, making it easier to suppress the temperature rise of the sponge member.

[0062] The aforementioned electronic components and the like can be fixed to the groove 37.

[0063] The sponge member according to this embodiment is a porous structure, and its cells (pores) may be interconnected or closed cells, but interconnected is preferable.

[0064] As the porous structure, foamed synthetic resin or synthetic rubber is preferably used, but a web-like structure in which animal fibers, plant fibers, or synthetic fibers are intertwined and linked together may also be used.

[0065] The material of the foam is not particularly limited, but examples include synthetic resins such as polyurethane, polystyrene, polyethylene, polypropylene, and ethylene-vinyl acetate copolymer (EVA); and synthetic rubbers such as ethylene-propylene-diene rubber (EPDM), silicone rubber, acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), butyl rubber, chloroprene rubber, acrylic rubber, and epichlorohydrin rubber (ECO). Among these, polyurethane is preferred from the viewpoint of sound dampening, lightness, controllability of foaming, and durability.

[0066] For example, when polyurethane foam is used as a sponge component, the polyurethane foam can be manufactured using polyurethane raw materials such as polyols, polyisocyanates, catalysts, foam stabilizers, and blowing agents by known methods.

[0067] If the sponge material is a foam, its density can be adjusted as appropriate by changing the type and amount of catalysts, foam stabilizers, blowing agents, etc., that are blended into the raw materials.

[0068] The density D of the sponge material is 20 kg / m³, from the viewpoint of the effects of the present invention. 3 It is less than 17 kg / m 3 The following is preferable: 15 kg / m 3 The following is more preferable: 13 kg / m 3 The following is even more preferable: 10 kg / m 3 The following are particularly preferred. On the other hand, there is no particular limit to the lower limit of the density D of the sponge material, but from the viewpoint of reducing running noise, 8.0 kg / m 3 The above is preferable, and 8.5 kg / m 3 The above is more preferable, 9.0 kg / m 3 The above is even more preferable.

[0069] From the viewpoint of sufficient conversion of air vibration energy, the volume of the sponge member is preferably 0.4% or more, preferably 1% or more, and more preferably 2% or more of the total volume of the tire cavity. Furthermore, the volume of the sponge member is preferably 30% or less, preferably 20% or less, and more preferably 10% or less of the total volume of the tire cavity.

[0070] Here, the volume of the sponge member refers to the apparent total volume of the sponge member, which is determined from its external shape including the internal air bubbles. In this specification, the total volume Vi of the tire cavity is to be approximately determined by the following formula (1) in an unloaded, normal state with the tire mounted on a normal rim and filled with normal internal pressure. Below, A refers to the area enclosed by the line segment connecting the inner radial endpoints of the tire and the surface of the tire cavity and the pair of bead portions. Vi=A×{(Di-Dr) / 2+Dr}×π ···(1) A: Cross-sectional area (mm) of the tire cavity obtained by CT scanning a tire-rim assembly in a normal state. Di: Maximum outer diameter of the inner surface of the tire in its normal state (mm) Dr: Rim diameter (mm)

[0071] (Belt layer and steel cord) Figure 2 is a schematic cross-sectional view of the belt layer 7. As shown, the first belt ply 5 and the second belt ply 6 each have multiple steel cords (5A, 6A) and topping rubber (5B, 6B). The multiple steel cords are arranged in a row in parallel. The topping rubber covers the steel cords, and the entire circumference of each individual steel cord is covered with topping rubber.

[0072] When the shortest distance between the steel cord 6A of the second belt ply 6 and the steel cord 5A of the first belt ply 5 in the center of the tire is denoted as a, and the shortest distance between the steel cord 6A at the outermost end of the second belt ply 6 and the steel cord 5A of the first belt ply 5 is denoted as b, then b / a is preferably 1.5 or greater, preferably 1.7 or greater, and preferably 1.9 or greater. It is believed that setting b / a within the above range contributes to improving the durability performance at the belt end. Furthermore, from the viewpoint of low fuel consumption performance, b / a is preferably 4.5 or less, more preferably 4.0 or less, even more preferably 3.5 or less, and particularly preferably 3.0 or less. In essence, b represents the shortest distance between the steel cord at the outermost end of the second belt ply and the curve formed by the outermost ends in the tire radial direction of the multiple steel cords aligned in the first belt ply (dotted line L in Figure 2).

[0073] Figure 3 is a schematic cross-sectional view of the center portion of the belt layer 7, which is the area enclosed by the dashed line in Figure 2. The distance from the interface of the first belt ply 5 to the steel cord 5A in the tire center portion (i.e., the distance c1 from the top surface to the cord 5A and the distance c2 from the bottom surface to the cord 5A) is preferably 0.18 mm or less, more preferably 0.15 mm or less, and even more preferably 0.12 mm or less. This configuration is thought to contribute to improved fuel efficiency. Furthermore, there is no particular lower limit to the distance from the interface of the first belt ply 5 to the steel cord 5A in the tire center portion, but it is preferably 0.03 mm or more, and more preferably 0.05 mm or more.

[0074] For similar reasons, the distance from the upper and lower surfaces of the second belt ply 6 to the code 6A in the tire center (i.e., the distance c3 from the top surface to the code 6A and the distance c4 from the bottom surface to the code 6A) is preferably 0.18 mm or less, more preferably 0.15 mm or less, and even more preferably 0.12 mm or less. Furthermore, there is no particular lower limit to the distance from the upper and lower surfaces of the second belt ply 6 to the code 6A in the tire center, but it is preferably 0.03 mm or more, and more preferably 0.05 mm or more.

[0075] The steel cord is inclined with respect to the circumferential direction of the tire. The angle of inclination of the steel cord with respect to the circumferential direction of the tire is not particularly limited, but is set in the range of 0° to 60°, for example.

[0076] The steel cord according to this embodiment has 1 to 4 steel strands, also called filaments. That is, the steel cord may be a single-strand monofilament cord (i.e., a cord consisting of one filament with a 1x1 structure), or it may have 2 to 4 filaments.

[0077] When a single steel cord has 2 to 4 filaments, it is preferable that the steel cord has a twisted structure in which these filaments are twisted together along its longitudinal direction. The twisted structure is not particularly limited and can be, for example, a single-strand steel cord with a 1×N structure or a layered steel cord with an N+M structure.

[0078] A single-strand structure can be expressed as, for example, a 1×N structure. A 1×N structure means a structure in which N filaments are twisted together to form a single layer. A single layer means a structure in which, in a cross-section perpendicular to the longitudinal direction of the steel cord, the filaments are arranged to form a single layer along the circumference of a circle. Examples of single-strand structures in this embodiment include 1×2 structures, 1×3 structures, and 1×4 structures.

[0079] Figure 4 is a perspective view of a steel cord having a 1x2 structure. The steel cord 50 shown in Figure 4 has two filaments 51 twisted together spirally along the longitudinal direction to form a single layer.

[0080] A layered twisted structure has a structure in which multiple filaments are wound in layers sequentially from the center outwards in a cross section perpendicular to the longitudinal direction of the steel cord, and can be represented, for example, as an N+M structure. An N+M structure means a structure having a core in which N filaments are twisted together in a spiral along their longitudinal direction, and an outer sheath in which M filaments are twisted together in a spiral along the longitudinal direction of the core to cover the outer circumference of the core. An example of a layered twisted structure in this embodiment is a 2+2 structure.

[0081] The steel cord preferably has a 1x1 or 1x4 structure. This configuration allows for a reduction in the amount of topping rubber coating while maintaining the tire's durability, which is expected to further improve fuel efficiency through tire weight reduction.

[0082] The material of the steel filament is not particularly limited, and HT (High Tensile), SHT (Super High Tensile), UHT (Ultra High Tensile), etc., can be used. Recycled iron obtained by melting down used iron products may also be used. Furthermore, when using a steel cord made by twisting multiple steel filaments together, steel filaments that have been pre-curled in the longitudinal direction may be used to improve durability by making it easier for the topping rubber to penetrate inside the steel cord.

[0083] The steel cord according to this embodiment may be coated with a plating layer. A steel cord with a plating layer exhibits high moisture-resistant heat bonding performance even under harsh conditions of high temperature and humidity, thereby preventing delamination between the topping rubber and the steel cord and improving the durability of the tire under humid and hot conditions. If the steel cord has multiple filaments, a plating layer can be applied to the surface of each filament.

[0084] The composition of the plating layer is not particularly limited, but a plating layer containing a copper layer and a zinc layer is preferred, and a plating layer containing a copper layer, a zinc layer, and a cobalt layer is more preferred. In particular, steel cords having a ternary plating layer consisting of copper (Cu), zinc (Zn), and cobalt (Co) exhibit high moisture-resistant thermal bonding performance even under harsh conditions of high temperature and humidity, thereby preventing delamination between the topping rubber and the steel cord and improving the durability performance of the tire under humid and hot conditions.

[0085] From the viewpoint of suppressing excessive copper reaction, the zinc content in the plating layer is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more. Furthermore, from the viewpoint of suppressing adhesion reduction due to the formation of excessive zinc oxide, it is preferably 44% by mass or less, more preferably 40% by mass or less, even more preferably 36% by mass or less, and particularly preferably 32% by mass or less.

[0086] From the viewpoint of adhesion, the copper content in the plating layer is preferably 55% by mass or more, more preferably 58% by mass or more, and even more preferably 61% by mass or more. Furthermore, from the viewpoint of preventing rubber deterioration due to copper leaching in a humid and hot environment, it is preferably 78% by mass or less, more preferably 75% by mass or less, and even more preferably 72% by mass or less.

[0087] From the viewpoint of thermal and humid adhesion, the cobalt content in the plating layer is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, and even more preferably 3.0% by mass or more. Furthermore, from the viewpoint of preventing crack formation during wire drawing, it is preferably 8.0% by mass or less, more preferably 7.0% by mass or less, and even more preferably 6.0% by mass or less.

[0088] The plating layer can be formed by plating copper, zinc, and cobalt layers onto the filament before wire drawing, and then diffusing the metals of each layer formed on the filament surface by heat treatment. The order in which the layers are formed on the filament to create the plating layer is not particularly limited.

[0089] Next, the heat-treated material can be drawn to a desired filament diameter to form a filament with a plating layer. If the steel cord consists of a single filament, it can be used as is after drawing. If the steel cord has multiple filaments, after drawing, the resulting filaments can be twisted together, for example, to form a desired twisted structure, thereby creating a steel cord with a plating layer.

[0090] 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 even more 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 even more preferably 0.30 μm or less.

[0091] From the viewpoint of the effects of the present invention, the cord diameter R of the steel cord is preferably 0.15 mm or more, more preferably 0.20 mm or more, even more preferably 0.25 mm or more, even more preferably 0.30 mm or more, even more preferably 0.35 mm or more, and particularly preferably 0.40 mm or more. On the other hand, from the viewpoint of reducing the weight of the tire, the cord diameter R of the steel cord is preferably 0.75 mm or less, more preferably 0.65 mm or less, even more preferably 0.55 mm or less, and particularly preferably 0.45 mm or less.

[0092] The number of steel cords E (also called ends) per 50 mm in the tire width direction is not particularly limited, but is preferably 40 or more, more preferably 45 or more, even more preferably 50 or more, even more preferably 55 or more, and particularly preferably 60 or more. Furthermore, E is preferably 100 or less, more preferably 95 or less, and even more preferably 90 or less.

[0093] From the viewpoint of the effects of the present invention, the bending stiffness Fr of the steel cord is preferably 5.0 g·cm or more, more preferably 10 g·cm or more, even more preferably 20 g·cm or more, even more preferably 30 g·cm or more, even more preferably 40 g·cm or more, and particularly preferably 50 g·cm or more. On the other hand, there is no particular upper limit to Fr, but it is preferably 80 g·cm or less, more preferably 70 g·cm or less, and even more preferably 60 g·cm or less. The bending stiffness Fr of the steel cord can be appropriately adjusted by changing the composition of the steel cord and the cord diameter D.

[0094] Tire's maximum load capacity W L (kg) is preferably 400 or more, more preferably 450 or more, and even more preferably 500 or more, from the viewpoint of better exhibiting the effects of the present invention. L (kg) is preferably 1300 or less, more preferably 1200 or less, and even more preferably 1100 or less. L This can be increased by increasing the virtual volume V of the space occupied by the tire, and conversely, it can be decreased by increasing it.

[0095] M=R / W L ×10 4 When defined in this way, from the viewpoint of durability performance, M is greater than 2.5, preferably greater than 3.0, more preferably greater than 3.5, even more preferably greater than 4.0, and particularly preferably greater than 4.5. On the other hand, there is no particular upper limit to M, but it is preferably less than 20, and more preferably less than 15.

[0096] From the viewpoint of the present invention, D / M is less than 7.0, preferably less than 6.0, more preferably less than 5.0, even more preferably less than 4.0, even more preferably less than 3.5, and particularly preferably less than 3.0. On the other hand, there is no particular limit to the lower limit of D / M, but it is preferably greater than 0.3, and more preferably greater than 0.5.

[0097] From the viewpoint of the sponge's durability, the D / E ratio is preferably less than 0.26, more preferably less than 0.23, even more preferably less than 0.20, and particularly preferably less than 0.17. On the other hand, there is no particular lower limit to the D / E ratio, but it is preferably greater than 0.08, and more preferably greater than 0.10.

[0098] From the viewpoint of the sponge's durability, D / Fr is preferably less than 3.0, more preferably less than 2.5, even more preferably less than 2.0, even more preferably less than 1.7, even more preferably less than 1.4, and particularly preferably less than 1.0. On the other hand, there is no particular lower limit for D / Fr, but it is preferably greater than 0.10, and more preferably greater than 0.15.

[0099] [Rubber composition] The rubber composition constituting the topping rubber that covers the steel cords of the belt layer 7 according to this embodiment (hereinafter referred to as the rubber composition according to this embodiment) contains rubber components and can be manufactured using the raw materials described below. The rubber composition according to this embodiment will be described below.

[0100] <Rubber components> In the rubber composition according to this embodiment, diene rubber is preferably used as the rubber component. Examples of diene rubber include isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR). These diene rubbers may be modified rubbers treated with modifying groups that can interact with fillers such as carbon black and silica, or hydrogenated rubbers in which some of the unsaturated bonds have been hydrogenated. One type of diene rubber may be used alone, or two or more types may be used in combination. In addition, as the diene rubber, stretched rubber that has been pre-stretched using a softening agent described later may be used.

[0101] The content of diene rubber in the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Alternatively, the rubber component may consist solely of diene rubber.

[0102] As the rubber component, at least one selected from the group consisting of isoprene-based rubber, SBR, and BR is preferably used. The rubber component preferably contains isoprene-based rubber, but may consist only of isoprene-based rubber.

[0103] (Isoprene rubber) As isoprene-based rubbers, for example, isoprene rubber (IR) and natural rubber, which are common in the tire industry, can be used. Natural rubber includes not only unmodified natural rubber (NR), but also 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-based rubbers may be used individually or in combination of two or more types.

[0104] NR is not particularly limited and can be any that is common in the tire industry, such as SIR20, RSS#3, TSR20, etc.

[0105] From the viewpoint of the effects of the present invention, the content of isoprene-based rubber in the rubber component is preferably 60% by mass or more, more preferably 70% by mass or more, even more 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 100% by mass.

[0106] (SBR) There are no particular limitations on SBR, and examples include unmodified solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR). Modified SBRs include SBRs with modified terminals and / or main chains, and modified SBRs coupled with tin, silicon compounds, etc. (condensates, those with branched structures, etc.). Among these, S-SBR and modified SBRs are preferred. Furthermore, hydrogenated versions of these SBRs (hydrogenated SBRs) can also be used. These SBRs may be used individually or in combination of two or more types.

[0107] The SBR content in the rubber component is not particularly limited, but is preferably less than 40% by mass, more preferably less than 20% by mass, even more preferably less than 10% by mass, and particularly preferably less than 5% by mass.

[0108] (BR) BR is not particularly limited, and for example, BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare-earth butadiene rubber synthesized using a rare-earth element catalyst (rare-earth BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc., which are common in the tire industry, can be used. These BRs may be used individually or in combination of two or more types.

[0109] The BR content in the rubber component is not particularly limited, but is preferably less than 40% by mass, more preferably less than 20% by mass, even more preferably less than 10% by mass, and particularly preferably less than 5% by mass.

[0110] (Other rubber components) The rubber component may include rubber components other than diene rubber (non-diene rubber) to the extent that it does not affect the effects of the invention. Examples of non-diene rubbers include rubber components commonly used in the tire industry, such as butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, polyethylene chloride rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. Other rubber components may be used individually or in combination of two or more. Furthermore, known thermoplastic elastomers may or may not be included in addition to the above-mentioned rubber components.

[0111] (Rubber components synthesized from recycled and biomass-derived raw materials) Monomers, which are the constituent units of synthetic rubbers such as IR, SBR, and BR, may be derived from underground resources such as petroleum and natural gas, or they may be recycled from rubber products such as tires or non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, but include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl compounds. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds are not particularly limited, but include styrene. In particular, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0112] The method for producing recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Furthermore, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and pressure, decomposed by microwaves, or extracted after mechanical grinding.

[0113] Furthermore, the monomers that make up polymers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural, forestry, and fishery products, sugars, wood chips, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha.

[0114] The biomass-derived monomer (biomass monomer) is not particularly limited and includes biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. Examples of the aromatic vinyl compound are not particularly limited but include styrene. Furthermore, the method for producing the biomass monomer is not particularly limited and includes, for example, biological and / or chemical and / or physical transformations of plants and animals. Typical biological transformations include fermentation by microorganisms, while chemical and / or physical transformations include those by catalysts, high heat, high pressure, electromagnetic waves, critical liquids, and combinations thereof.

[0115] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compounds. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0116] Whether the raw materials for a polymer are biomass-derived can be determined by measuring pMC (percent Modern Carbon) according to ASTM D6866-10. pMC refers to the percentage of modern standard reference carbon. 14 Sample relative to C concentration 14This is a ratio of C concentrations and is used as an indicator of the biomass ratio of a compound. The significance of this value is described below.

[0117] 1 mole of carbon atoms (6.02 × 10⁻¹⁰) 23 (Each) contains approximately 6.02 × 10¹⁶ atoms, which is about one trillionth of the amount of carbon atoms in a normal atom. 11 individual 14 C exists. 14 The half-life of C is 5730 years. 14 C is decreasing regularly. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been fixed after more than 226,000 years have passed since atmospheric carbon dioxide was taken in and fixed by plants, etc., C was initially included in these as well. 14 All elements of C have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas are no longer viable. 14 It contains absolutely no element C. Therefore, chemical substances produced using these fossil fuels as raw materials also contain C. 14 It contains absolutely no element C.

[0118] on the other hand, 14 C is continuously produced when cosmic rays undergo nuclear reactions in the atmosphere. Therefore, 14 In the Earth's atmospheric environment, carbon (C) is produced in a state where its decrease due to radioactive decay and its production through nuclear reactions are in equilibrium. 14 The amount of C is constant. Therefore, the amount of biomass resource-derived substances currently circulating in the environment 14 As mentioned above, the carbon concentration is approximately 1 × 10¹⁶ of the total carbon atoms. -12 These values ​​are approximately in mole percent. Therefore, the difference between these values ​​can be used to calculate the biomass ratio in a given compound.

[0119] this 14 C is typically measured as follows: Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12Perform measurement C). In the measurement, 14 As a modern standard reference for the concentration of C, the amount of cyclic carbon in nature as of 1950 14 The C concentration will be used. The specific standard material will be the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific radioactivity of carbon in this oxalic acid (per gram of carbon) will be used. 14 The radioactivity intensity of C is separated by carbon isotope, 13 The standard value is obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date. 14 This value is used as the C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0120] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal conditions it will often not reach 100, and will show a value of approximately 110 pMC. On the other hand, regarding chemical substances derived from fossil fuels such as petroleum, 14 When the C concentration is measured, it will show a value of approximately 0 pMC (for example, 0.3 pMC). This value corresponds to the aforementioned biomass ratio of 0%.

[0121] Based on the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in rubber compositions is preferable from an environmental protection standpoint.

[0122] <Filler> The rubber composition according to this embodiment preferably contains carbon black as a filler, and may further contain other fillers such as silica. Alternatively, the filler may consist only of carbon black and silica.

[0123] The carbon black used is not particularly limited and includes N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw materials for the carbon black may be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by thermal decomposition of waste tires. The manufacturing method for the carbon black may be combustion such as the furnace method, hydrothermal carbonization (HTC), or thermal decomposition of methane such as the thermal black method. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbia Carbon Corporation, etc. These carbon blacks may be used individually or in combination of two or more types.

[0124] In addition to the above, from the perspective of life cycle assessment, carbon black may also be made from biomass materials such as lignin, or recycled carbon black obtained by thermally decomposing and refining products containing carbon black, such as tires.

[0125] In this specification, "recycled carbon black" refers to carbon black obtained by crushing used tires and other products containing carbon black, and calcining the crushed material, wherein, according to the thermogravimetric method compliant with JIS K 6226-2:2003, when oxidative combustion occurs by heating in air, the proportion of the mass of ash (ash content), which is the component that does not burn, is 13% by mass or more. In other words, the proportion of the mass (carbon content) lost due to the aforementioned oxidative combustion of recycled carbon black is 87% by mass or less. Recycled carbon black may also be represented as rCB.

[0126] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975, which refers to "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, states that it can be obtained by the pyrolysis of organic materials at 550-800°C in the absence of oxygen, or by vacuum pyrolysis at relatively low temperatures (

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

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

[0127] Recycled carbon black may lack functional groups on its surface, or it may be treated to include functional groups on its surface. Treatment to include functional groups on the surface of recycled carbon black can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. In addition, in Japanese Patent Publication No. 6856781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes carbon black treated to include functional groups on its surface.

[0128] Recycled carbon black can be purchased from companies such as Strable Green Carbon and LD Carbon.

[0129] The nitrogen adsorption specific surface area (N2SA) of carbon black is 80m² from the perspective of reinforcing properties. 2 Preferably more than / g, 90m2 More preferably than / g, 100m 2 More preferably than / g, 110m 2 A value exceeding / g is particularly preferred. Furthermore, from the viewpoint of heat generation and processability, 250m 2 Preferably less than / g, 220m 2 Less than / g is more preferable, 190m 2 A value of less than / g is even more preferable. The N2SA of carbon black is measured by the measurement method described above.

[0130] From the viewpoint of reinforcing properties, the carbon black content per 100 parts by mass of rubber component is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and particularly preferably 50 parts by mass or more. Furthermore, from the viewpoint of suppressing heat generation, it is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 80 parts by mass or less, and particularly preferably 70 parts by mass or less.

[0131] (silica) The silica used is not particularly limited, and common types used in the tire industry can be used, such as silica prepared by a dry process (anhydrous silica) or silica prepared by a wet process (hydrated silica). The raw material for silica is not particularly limited, and may be a mineral-derived raw material such as quartz, or a biological-derived raw material such as rice husks (for example, silica made from biomass materials such as rice husks), or silica recycled from silica-containing products may be used. Among these, hydrated silica prepared by a wet process is preferred because it contains a large number of silanol groups. These silicas may be used individually or in combination of two or more types.

[0132] Silica derived from biomass materials can be obtained, for example, by extracting silicates from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then using these silicates to react with sulfuric acid in the same way as conventional wet silica, the precipitate of silicon dioxide is filtered, washed with water, dried, and pulverized.

[0133] The silica recycled from silica-containing products can be, for example, silica recovered from products containing silica such as semiconductors and other electronic components, tires, desiccants, and diatomaceous earth and other filter materials. The recovery method is not particularly limited and can include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from semiconductors and other electronic components or tires is preferred.

[0134] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol.6, pp.216-222, etc.).

[0135] Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0136] The nitrogen adsorption specific surface area (N2SA) of silica is 110 m², from the perspective of low fuel consumption and wear resistance. 2 Preferably 130m / g or more. 2 More preferably 150m / g or more, 2 More preferably 170m / g or more. 2 A value of 350m or more is particularly preferred. Furthermore, from the viewpoint of low fuel consumption and processability, 350m 2 Preferably less than / g, 300m 2 More preferably less than / g, 250m 2 A value of less than / g is even more preferable. The N2SA of silica is measured by the measurement method described above.

[0137] The average primary particle diameter of silica is preferably 24 nm or less, more preferably 22 nm or less, even more preferably 20 nm or less, and particularly preferably 18 nm or less. The lower limit of the average primary particle diameter is not particularly limited, but from the viewpoint of silica dispersibility, it is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 5 nm or more. The average primary particle diameter of silica is measured by the measurement method described above.

[0138] When silica is included, its content per 100 parts by mass of the rubber component is not particularly limited, but 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. Furthermore, the content is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less.

[0139] From the viewpoint of the effects of the present invention, the total content of filler per 100 parts by mass of rubber component is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and particularly preferably 50 parts by mass or more. Furthermore, from the viewpoint of low fuel consumption performance and elongation at break, it is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 80 parts by mass or less, and particularly preferably 70 parts by mass or less.

[0140] (Other fillers) Other fillers besides silica and carbon black are not particularly limited and may include those commonly used in the tire industry, such as aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, magnesium sulfate, talc, and clay. These other fillers may be used individually or in combination of two or more.

[0141] (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 conventionally been used in combination with silica in the tire industry can be used, for example: mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, and 3-octanoylthio-1-propyltrimethoxysilane. Examples include thioester silane coupling agents such as lan; vinyl silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, it is preferable to contain a sulfide silane coupling agent and / or a mercapto silane coupling agent. As silane coupling agents, for example, those commercially available from Evonik Industries, Momentive, etc., can be used. These silane coupling agents may be used individually or in combination of two or more.

[0142] From the viewpoint of improving silica dispersibility, the content of the silane coupling agent per 100 parts by mass of silica is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, and even more preferably 5.0 parts by mass or more. Furthermore, from the viewpoint of cost and processability, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 12 parts by mass or less.

[0143] <Thermosetting resin> The rubber composition according to this embodiment preferably contains a thermosetting resin. Here, a thermosetting resin refers to a resin that polymerizes upon heating to form a network structure, hardens, and does not return to its original state.

[0144] The thermosetting resin is not particularly limited and examples include resorcinol resin, modified resorcinol resin, cresol resin, modified cresol resin, phenol resin, and modified phenol resin. These thermosetting resins may be used individually or in combination of two or more. By incorporating these thermosetting resins, the adhesion to the cord, elongation at break, and complex modulus can be improved. Among these, resorcinol resin, modified resorcinol resin, and modified cresol resin are preferred, with modified resorcinol resin being more preferred.

[0145] Examples of resorcinol resins include resorcinol-formaldehyde condensates. Examples of modified resorcinol resins include those in which some of the repeating units of a resorcinol resin have been alkylated.

[0146] Examples of cresol resins include cresol-formaldehyde condensates. Examples of modified cresol resins include those in which the terminal methyl groups of cresol resin are modified to hydroxyl groups, and those in which some of the repeating units of cresol resin are alkylated.

[0147] Phenolic resins include those obtained by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, and furfural using an acid or alkali catalyst. Among these, those obtained by reaction with an acid catalyst (such as novolac-type phenolic resins) are preferred. Modified phenolic resins include those obtained by modifying phenolic resin with cashew oil, tall oil, linseed oil, various animal and vegetable oils, unsaturated fatty acids, rosin, alkylbenzene resins, aniline, melamine, and the like.

[0148] When a thermosetting resin is included, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, preferably 1.0 part by mass or more, and more preferably 1.5 parts by mass or more, from the viewpoint of adhesiveness and durability. Furthermore, from the viewpoint of suppressing the adhesive reaction during vulcanization and preventing a decrease in durability after moist heat degradation, it is preferably 6.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 4.5 parts by mass or less, and particularly preferably 4.0 parts by mass or less.

[0149] <Hardening agent> The rubber composition according to this embodiment preferably contains a curing agent for curing the thermosetting resin. The curing agent is not particularly limited and examples include hexamethoxymethyl melamine (HMMM), modified etherified methylolmelamine resin, hexamethylenetetramine (HMT), pentakis(methoxymethyl)methylolmelamine, tetrakis(methoxymethyl)dimethylolmelamine, etc., with modified etherified methylolmelamine resin being preferred. These curing agents may be used individually or in combination of two or more.

[0150] When a curing agent is included, its content per 100 parts by mass of the rubber component is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.7 parts by mass or more, from the viewpoint of the effects of the present invention. Furthermore, the content is preferably 3.0 parts by mass or less, more preferably 2.5 parts by mass or less, and even more preferably 2.0 parts by mass or less.

[0151] <Cobalt compounds> The rubber composition constituting the topping rubber preferably contains a cobalt compound. The inclusion of a cobalt compound enhances the adhesion between the steel cord and the topping rubber, resulting in a tire with superior durability. Examples of cobalt compounds include elemental cobalt, cobalt chloride, organic cobalt acid, and inorganic cobalt acid, with organic cobalt acid being preferred. These cobalt compounds may be used individually or in combination of two or more.

[0152] Organic cobalt acids are suitably used to promote adhesion between the plating layer of the steel cord and the rubber composition, and to prevent the plating components from leaching into the rubber composition during hygroscopic and heat-induced degradation. The number of carbon atoms in the organic acid constituting the organic cobalt acid is preferably 12 to 24, and more preferably 14 to 22. Specific examples of organic cobalt acid salts include, for example, cobalt stearate, cobalt naphthenate, cobalt neodecanoate, cobalt rosinate, cobalt versatate, cobalt tol oilate, cobalt oleate, cobalt linoleate, cobalt linolenate, and cobalt palmitate. In addition, the organic cobalt acid may be a composite salt in which some of the organic acid is replaced with boric acid (for example, boron-3-cobalt neodecanoate).

[0153] Examples of inorganic cobalt acids include cobalt sulfate, cobalt nitrate, cobalt phosphate, and cobalt chromate.

[0154] The cobalt element content per 100 parts by mass of rubber component is 2.85 × 10⁻⁶ -3 Preferably, it is 2.5 × 10⁻¹⁶ parts by mass or less. -3 Parts per mass or less is more preferable, 2.0 × 10 -3 A ratio of parts per mass or less is more preferable, specifically 1.0 × 10⁻⁶. -3 Parts by mass or less is even more preferable, and may even be 0 parts by mass.

[0155] <Other compounding agents> In addition to the components mentioned above, the rubber composition according to this embodiment may appropriately contain compounding agents commonly used in the tire industry, such as plasticizers, vulcanized rubber particles, waxes, antioxidants, stearic acid, zinc oxide, vulcanizing agents, and vulcanization accelerators.

[0156] A plasticizer is a material that imparts plasticity to rubber components, and the concept includes both liquid plasticizers at 25°C and solid plasticizers at 25°C. Examples of plasticizers include resin components, oils, liquid rubber, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, from biomass, or from naphtha recycled from rubber or non-rubber products. In addition, low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may be used as plasticizers. These plasticizers may be used individually or in combination of two or more types.

[0157] (Resin components) The rubber composition according to this embodiment may also contain a resin component. The resin component that can be used in this embodiment is not particularly limited, but resins commonly used in the tire industry can be used, such as C9 resins, C5 resins, C5C9 resins, dicyclopentadiene resins, aromatic vinyl resins, coumarone resins, indene resins, terpene resins, rosin resins, phenolic resins, etc. These resin components may be used individually or in combination of two or more. Each resin component may also be used individually or in combination of two or more.

[0158] ≪C9 series resin≫ A "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a polymer obtained by polymerizing the C9 fraction alone, or a copolymer obtained by copolymerizing the C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) and a C9 fraction is called a DCPD / C9 resin. Furthermore, the C9 resin may be a hydrogenated or modified version of these resins. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene. As for C9 resins, commercially available products from companies such as BASF, Zeon Corporation, and ENEOS Corporation can be used.

[0159] ≪C5 series resin≫ "C5 resins" refer to resins obtained by polymerizing C5 fractions, and may be hydrogenated or modified versions of these resins. Examples of C5 fractions other than dicyclopentadiene include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, isoprene, piperylene, 2-methyl-1-butene, 2-methyl-2-butene, and 1-pentene. As C5 resins, commercially available products from companies such as Structol, Nippon Zeon Co., Ltd., and ENEOS Corporation can be used.

[0160] ≪C5C9 resin≫ "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified. As C5C9 petroleum resin, commercially available products from companies such as Tosoh Corporation and LUHUA can be used.

[0161] <Dicyclopentadiene resins> A "dicyclopentadiene-based resin" refers to a resin in which cyclopentadiene (CPD) and / or dicyclopentadiene (DCPD) are the most abundant monomer components, and these may be hydrogenated or modified resins. Preferred dicyclopentadiene-based resins include polymers obtained by polymerizing only dicyclopentadiene as a monomer, and copolymers (DCPD / C9 resins) obtained by copolymerizing dicyclopentadiene with the C9 fraction. Commercially available dicyclopentadiene-based resins from companies such as ExxonMobil, ENEOS Corporation, Nippon Zeon Corporation, and Maruzen Petrochemical Co., Ltd. can be used.

[0162] Aromatic vinyl resin "Aromatic vinyl resin" refers to a resin in which aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-chlorostyrene are the most abundant monomer components, and these may be hydrogenated or modified. As aromatic vinyl resins, α-methylstyrene or a homopolymer of styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, for reasons of being economical, easy to process, and having excellent heat generation properties. As aromatic vinyl resins, commercially available products from companies such as Kraton, Eastman Chemical Company, and Mitsui Chemicals, Inc. can be used.

[0163] Coumaron-based resin "Coumarone-based resin" refers to a resin containing coumarone as a monomer component, and may be hydrogenated or modified. Preferred coumarone-based resins include, for example, coumarone resin, which is a polymer with coumarone as the monomer component; coumarone-indene resin, which is a copolymer with coumarone and indene as monomer components; and coumarone-indene-styrene resin, which is a copolymer with coumarone, indene, and styrene as monomer components. As coumarone-based resins, commercially available products from companies such as Rutgers, Nippon Paint Chemical Co., Ltd., and Mitsui Chemicals, Inc. can be used.

[0164] Indene resin "Indene-based resin" refers to a resin containing indene as a monomer component, and may be hydrogenated or modified resins. Preferred indene-based resins include, for example, coumarone-indene resin, which is a copolymer of coumarone and indene as monomer components, and coumarone-indene-styrene resin, which is a copolymer of coumarone, indene, and styrene as monomer components. Commercially available indene-based resins from companies such as Rutgers, Nippon Paint Chemical Co., Ltd., and Mitsui Chemicals, Inc. can be used.

[0165] Terpene resins "Terpene resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, and dipentene as monomer components, and may be hydrogenated or modified. Preferred terpene resins include, for example, polyterpene resins, which are polymers in which one or more of the aforementioned terpene compounds are used as monomer components; aromatically modified terpene resins, which are copolymers in which the aforementioned terpene compounds and aromatic compounds are used as monomer components; and terpene phenol resins, which are copolymers in which the aforementioned terpene compounds and phenol compounds are used as monomer components. Examples of aromatic compounds that serve as monomer components in aromatically modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenol compounds that serve as monomer components in terpene phenol resins include phenol, bisphenol A, cresol, and xylenol. As terpene resins, commercially available products from companies such as Yasuhara Chemical Co., Ltd., Arakawa Chemical Industries, Ltd., and Nippon Terpene Chemical Co., Ltd. can be used.

[0166] ≪Rosin-based resin≫ "Rosin-based resin" refers to a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palastic acid, and isopimal acid, and may be hydrogenated or modified. Rosin-based resins are not particularly limited, but examples include natural resin rosin and rosin-modified resins obtained by hydrogenating, disproportionating, dimerizing, esterifying, etc. As rosin-based resins, commercially available products from companies such as Harima Chemical Industries, Ltd., Arakawa Chemical Industries, Ltd., and IREC Co., Ltd. can be used.

[0167] Phenolic resins "Phenol-based resins" refer to resins containing phenol compounds such as phenol and cresol as monomer components, and may also be hydrogenated or modified resins. Phenolic resins are not particularly limited, but examples include phenol-formaldehyde resins, alkylphenol-formaldehyde resins, alkylphenol-acetylene resins, oil-modified phenol-formaldehyde resins, and terpene-phenol resins. Phenolic resins that are commercially available from companies such as Sumitomo Bakelite Co., Ltd., DIC Corporation, and Asahi Organic Materials Co., Ltd. can be used.

[0168] When a resin component is included, the content of the resin component relative to 100 parts by mass of the rubber component is not particularly limited, but is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. Furthermore, the content is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 10 parts by mass.

[0169] (oil) Examples of oils include mineral oil, vegetable oil, and animal oil. Furthermore, from a life cycle assessment perspective, waste oil from rubber mixers and engines, or refined waste cooking oil from restaurants, may also be used. Oils may be used individually or in combination of two or more types.

[0170] In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oils (mineral oil), naphthenic oils, and aromatic oils. Specific examples of mineral oil include MES (Mild Extracted Solvate), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Furthermore, for environmental reasons, oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of low-PCA oils include MES, TDAE, and heavy naphthenic oils. Mineral oil may be used alone or in combination of two or more types.

[0171] In this specification, vegetable oils include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and wood wax. Furthermore, vegetable oils may also include refined oils (such as salad oil) obtained by refining the above oils, transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidized polymerized oils obtained by oxidizing the above oils, and waste cooking oils recovered from use as edible oils. Note that vegetable oils may be liquid or solid at 25°C. Vegetable oils may be used individually or in combination of two or more types.

[0172] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer of three or more. Note that acylglycerols of two or more forms can be obtained by thermal polymerization, oxidative polymerization, etc. Also, the acylglycerol may be a liquid or a solid at 25°C.

[0173] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, 1 This can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours, and after removing the rubber composition, it is measured at room temperature. 1 When 1H-NMR was measured and the tetramethylsilane (TMS) signal was set to 0.00 ppm, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm. These signals are presumed to originate from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0174] The aforementioned fatty acids are not particularly limited and may be unsaturated or saturated fatty acids. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0175] In particular, it is desirable that the fatty acid contains fatty acids with few double bonds, i.e., saturated fatty acids or monounsaturated fatty acids, and oleic acid is preferred. As a vegetable oil containing such fatty acids, for example, a vegetable oil containing saturated fatty acids or monounsaturated fatty acids may be used, or a vegetable oil that has been modified by transesterification or other means may be used. Furthermore, in order to produce a vegetable oil containing such fatty acids, plants may be improved by breeding, genetic modification, genome editing, etc.

[0176] As for vegetable oils, commercially available products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used.

[0177] Examples of animal oils include fish oil, beef tallow, whale oil, or oleyl alcohol which can be derived from them.

[0178] When oil is included, the content of oil per 100 parts by mass of rubber component is not particularly limited, but 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. Furthermore, 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 less than 10 parts by mass.

[0179] Liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at 25°C, but examples include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), and liquid farnesene rubber. These liquid rubbers may be used individually or in combination of two or more.

[0180] Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelaate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), and trixylenyl phosphate (TXP). Ester-based plasticizers may be used individually or in combination of two or more.

[0181] From the viewpoint of the effects of the present invention, the content of plasticizer per 100 parts by mass of rubber component (total amount if multiple plasticizers 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. Furthermore, the content is preferably less than 40 parts by mass, more preferably less than 30 parts by mass, even more preferably less than 20 parts by mass, and particularly preferably less than 10 parts by mass.

[0182] Vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the viewpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. These vulcanized rubber particles may be used individually or in combination of two or more types.

[0183] The vulcanized rubber particles are not particularly limited and may be either unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0184] Commercially available vulcanized rubber products can be used, such as those from Lehigh, Muraoka Rubber Industries, and others.

[0185] When vulcanized rubber particles are included, the content per 100 parts by mass of the rubber component can be appropriately adjusted, for example, within a range of more than 1 part by mass and less than 80 parts by mass.

[0186] The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used, such as mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. The wax can be commercially available from companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Paramelt Co., Ltd. These waxes may be used individually or in combination of two or more types.

[0187] When wax is included, the amount of wax per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of weather resistance of the rubber. Furthermore, from the viewpoint of preventing whitening of the tire due to bloom, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0188] The anti-aging agents are not particularly limited, but include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditril-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as amines (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flexis, and others. The antioxidant may be used alone or in combination of two or more.

[0189] When an anti-aging agent is included, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of the rubber's resistance to ozone cracking. Furthermore, from the viewpoint of wear resistance and wet grip performance, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0190] When stearic acid is included, its content per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of vulcanization rate, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0191] When zinc oxide is included, its content per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of processability. Furthermore, 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.

[0192] Sulfur is preferably used as a vulcanizing agent. Suitable sulfur varieties include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.

[0193] When sulfur is included as a vulcanizing agent, the amount of sulfur per 100 parts by mass of rubber component is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.7 parts by mass or more, 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, even more preferably 3.0 parts by mass or less, and particularly preferably 2.5 parts by mass or less. When oil-containing sulfur is used as the vulcanizing agent, the amount of vulcanizing agent is the total amount of pure sulfur contained in the oil-containing sulfur.

[0194] As a vulcanizing agent other than sulfur, known organic crosslinking agents can also be used. The organic crosslinking agent is not particularly limited as long as it can form crosslinking chains other than polysulfide bonds, but examples include alkylphenol-sulfur chloride condensates, hexamethylene-1,6-bisthiosulfate sodium dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, and dicumyl peroxide. These organic crosslinking agents can be commercially available from companies such as Taoka Chemical Industries, Ltd., Lanxess Corporation, and Flexis.

[0195] The vulcanization accelerator is not particularly limited, but examples include sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiram-based vulcanization accelerators, thiourea-based vulcanization accelerators, dithiocarbamate-based vulcanization accelerators, aldehyde-amine-based vulcanization accelerators, aldehyde-ammonia-based vulcanization accelerators, imidazoline-based vulcanization accelerators, xanthate-based vulcanization accelerators, caprolactam disulfide, and the like. These vulcanization accelerators may be used individually or in combination of two or more. Among these, one or more vulcanization accelerators selected from the group consisting of sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, and guanidine-based vulcanization accelerators are preferred because they more favorably produce the desired effect.

[0196] Examples of sulfenamide-based vulcanization accelerators include N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide (DCBS). Among these, TBBS and CBS are preferred.

[0197] Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole (MBT) or its salts, di-2-benzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, and 2-(2,6-diethyl-4-morpholinothio)benzothiazole. Among these, MBTS and MBT are preferred.

[0198] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salts of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine. Among these, DPG is preferred.

[0199] When a vulcanization accelerator is included, its content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 0.7 parts by mass or more, and even more preferably 1.0 part by mass or more, from the viewpoint of ensuring a sufficient vulcanization rate. Furthermore, 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.

[0200] [Manufacturing of rubber compositions and tires] The rubber composition according to this embodiment can be manufactured by known methods. For example, it can be manufactured by kneading each of the above components using a rubber kneading device such as an open roll or a closed kneader (Banbury mixer, kneader, etc.).

[0201] The mixing process includes, for example, a base mixing process in which compounding agents and additives other than the vulcanizing agent and vulcanization accelerator are mixed, and a final mixing (F mixing) process in which the vulcanizing agent and vulcanization accelerator are added to the mixture obtained in the base mixing process and mixed. Furthermore, the base mixing process can be divided into multiple processes as desired.

[0202] While there are no particular limitations on the mixing conditions, one example is to mix the base mixture at a discharge temperature of 150-170°C for 3-10 minutes, and then mix the final mixture at 70-110°C for 1-5 minutes.

[0203] The tire according to this embodiment can be manufactured by conventional methods using the steel cord and sponge member described above. Specifically, the steel cord is coated with an unvulcanized rubber composition corresponding to the topping rubber obtained by the above method to obtain a steel cord-rubber composite that forms the belt layer. These are then bonded together with the tread portion and other tire members on a tire molding machine and molded in a conventional method to form an unvulcanized tire, and this unvulcanized tire can be manufactured by heating and pressurizing it in a vulcanizing machine. The vulcanization conditions are not particularly limited, but for example, a method of vulcanizing at 150 to 200°C for 10 to 30 minutes can be used. The sponge member is curved along the inner surface of the tire and attached with double-sided adhesive tape.

[0204] <Application> The tire according to this embodiment can be a general-purpose tire such as a passenger car tire, a truck / bus tire, or a motorcycle tire, but it can also be a tire for an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. A passenger car tire refers to a tire intended for use on a four-wheeled vehicle, with a maximum load capacity of 1000 kg or less. Furthermore, the tire according to this embodiment can be used as an all-season tire, a summer tire, or a winter tire such as a studless tire. [Examples]

[0205] The following describes examples (examples) that are considered preferable for implementation, but the scope of the present invention is not limited to these examples. A tire having the basic structure shown in Figure 1 and the specifications described below and in the table below was examined, and the results calculated based on the evaluation method described below are shown in Tables 2 to 5.

[0206] The various chemicals used in the examples and comparative examples are summarized below.

[0207] <Sponge material> Sponge material 1: Ether-based polyurethane foam manufactured according to manufacturing example 1 below (density D: 9 kg / m³) 3 ) Sponge material 2: Ether-based polyurethane foam manufactured by Marusuzu Co., Ltd. (Model number E-16, Density D: 15 kg / m³) 3 ) Sponge material 3: Ether-based polyurethane foam from Achilles Corporation (model number PD, density D: 25 kg / m³) 3 )

[0208] <Topping Rubber> NR:TSR20 Carbon Black: Show Black N330 (N2SA: 75m) manufactured by Cabot Japan Co., Ltd. 2 / g, average primary particle diameter: 30nm) Silica: ULTRASIL VN3 (N2SA: 175m) manufactured by Evonik Industries. 2 / g, average primary particle diameter: 18nm) Thermosetting resin: Sumilite Resin PR-12686E (cashew oil modified phenolic resin, softening point: 100°C) manufactured by Sumitomo Bakelite Co., Ltd. Hardener: Sumikanol 507AP (modified etherified methylol melamine resin) manufactured by Taoka Chemical Industry Co., Ltd. Cobalt compound: Cost-F (cobalt stearate) manufactured by DIC Corporation. Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: M95 (insoluble sulfur) manufactured by Nippon Dry Distillation Industry Co., Ltd. Vulcanization accelerator: Noxellar DZ (N,N-dicyclohexyl-2-benzothiazolyl sulfenamide (DCBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0209] Manufacturing Example 1: Manufacturing of Sponge Component 1 Polyol (GP3000 manufactured by Sanyo Chemical Industries, Ltd.), water (ion-exchanged water), catalyst (33LV manufactured by Sankyo Air Products Co., Ltd., MRH110 manufactured by Johoku Chemical Industry Co., Ltd.), and surfactant (SF2961 manufactured by Toray Dow Corning Silicone Co., Ltd.) are mixed in a predetermined ratio using a hand mixer. Then, a predetermined polyisocyanate (T-80 manufactured by Nippon Polyurethane Industries Co., Ltd., MR200 manufactured by Nippon Polyurethane Co., Ltd.) is added, and this mixture is placed in a foaming box to foam and harden to obtain sponge material 1.

[0210] (Examples and Comparative Examples) According to the formulation shown in Table 1, the chemicals other than sulfur and vulcanization accelerator were mixed in a 1.7 L closed Banbury mixer for 5 minutes until the discharge temperature reached 160°C to obtain a mixture. Next, using a twin-screw open roll mixer, the vulcanizing agent and vulcanization accelerator were added to the obtained mixture and mixed for 4 minutes until the temperature reached 105°C to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was used to coat steel cords to obtain a steel cord-rubber composite ply that forms the belt layer. These were bonded together with the tread portion and other tire components on a tire molding machine to produce an unvulcanized tire, which was then vulcanized at 170°C to obtain the test tires described in Tables 2 to 5. A sponge member was then curved along the inner surface of the tire and attached with double-sided adhesive tape. Here, the steel cords had a ternary plating layer, with an average thickness of 0.19 μm and a composition of the plating layer of Cu 68 mass%, Zn 28 mass%, and Co 4 mass%.

[0211] <Fuel efficiency> Each test tire is mounted on a standard rim, the internal pressure is adjusted to 230 kPa, and the rolling resistance is measured using a rolling resistance tester. The load is set to a load less than or equal to the standard load. The rolling resistance is measured when the tire is driven at a speed of 80 km / h, and its reciprocal is expressed as an index with Comparative Example 1 set to 100. A larger index indicates lower rolling resistance and better fuel efficiency.

[0212] <Durability performance of sponge material> Each test tire is mounted on a standard rim, the internal pressure is adjusted to 230 kPa, and the durability performance of the sponge material is evaluated using a drum testing machine. The load is set to a load equal to or greater than the standard load. The vehicle is driven at a speed of 80 km / h, and the distance until the sponge material and its vicinity are damaged is measured. The results are expressed as an index, with the value for Comparative Example 1 set to 100. A higher index indicates better durability performance.

[0213] <Overall Performance> The sum of the fuel efficiency index and the durability index is displayed as the overall performance index.

[0214] [Table 1]

[0215] [Table 2]

[0216] [Table 3]

[0217] [Table 4]

[0218] [Table 5]

[0219] <Embodiment> Examples of embodiments of the present invention are shown below.

[0220] [1] A tire having a belt layer and a sponge member on the radially inner side of the tread portion, wherein the belt layer has a steel cord consisting of 1 to 4 filaments and a topping rubber covering the steel cord, the topping rubber is made of a rubber composition containing rubber components, and the density D of the sponge member is 20 kg / m³ 3 Less than 8.0-17 kg / m 3 The cord diameter of the steel cord is R (mm), and the maximum load capacity of the tire is W. L (kg) M = R / W L ×10 4 When defined as such, a tire in which M is greater than 2.5, preferably greater than 3.0 and less than 20, more preferably greater than 4.0 and less than 15, and D / M is less than 7.0, preferably greater than 0.3 and less than 5.0, more preferably greater than 0.5 and less than 4.0. [2] The tire according to [1] above, wherein the steel cord has a 1x1 structure or a 1x4 structure. [3] The tire described in [1] or [2] above, wherein D / E is less than 0.17, when E is the number of steel cords arranged per 50 mm in the tire width direction. [4] A tire according to any of [1] to [3] above, wherein the bending rigidity of the steel cord is Fr (g·cm), and D / Fr is less than 1.7. [5] The cobalt element content in the rubber composition is 2.85 × 10⁻¹⁵ per 100 parts by mass of the rubber component. -3 A tire as described in any of the above [1] to [4], having a mass of less than or equal to the part-of-mass. [6] A tire as described in any of [1] to [5] above, wherein the D / M is less than 3.0. [7] The tire according to any one of [1] to [6] above, wherein the rubber composition contains silica. [8] The tire according to any one of [1] to [7] above, wherein the steel cord has a ternary plating layer consisting of copper, zinc, and cobalt. [9] The tire according to any one of [1] to [8] above, wherein the belt layer comprises a first belt ply and a second belt ply laminated on the radially outer side of the first belt layer, and when the shortest distance between the steel cord of the second belt ply and the steel cord of the first belt ply in the center portion of the tire is a, and the shortest distance between the steel cord at the outermost end of the second belt ply and the cord of the first belt ply is b, then b / a is 1.5 or more.

[10] A tire according to any of [1] to [9] above, wherein the distance from the upper and lower surfaces of the first belt ply to the cord in the center portion of the tire and the distance from the upper and lower surfaces of the second belt ply to the cord in the center portion are both 0.14 mm or less.

[11] The tire according to any of [1] to

[10] above, wherein the tire further comprises an electronic component.

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

[11] above, wherein the tire is an electric vehicle tire, a hybrid vehicle tire, or a plug-in hybrid vehicle tire. [Explanation of symbols]

[0221] 1. Tread section 5. First Belt Ply 6. Second Belt Ply 7 Belt layer 11 tires 15. Inner surface of the tire 31 Bead Core 32 Sidewall 33 Bead section 34 Carcass 36 bands 37. Grooves 39 Sponge material 61 Edge Band 62 Full Band CL Tire Equatorial Plane 5A, 6A, 50 steel cord 5B, 6B Topping Rubber 51 filaments

Claims

1. A tire having a belt layer and a sponge member on the radially inward side of the tread portion, The belt layer comprises a steel cord consisting of 1 to 4 filaments, and a topping rubber covering the steel cord. The topping rubber is composed of a rubber composition containing rubber components. The density D of the aforementioned sponge member is 20 kg / m³ 3 It is less than, The diameter of the steel cord is R (mm), and the maximum load capacity of the tire is W. L (kg) M=R / W L ×10 4 If defined as follows, A tire with an M value greater than 2.5 and a D / M value less than 7.

0.

2. The tire according to claim 1, wherein the steel cord has a 1x1 structure or a 1x4 structure.

3. The tire according to claim 1 or 2, wherein, when E is the number of steel cords arranged per 50 mm in the tire width direction, D / E is less than 0.

17.

4. The tire according to claim 1 or 2, wherein, when the bending rigidity of the steel cord is Fr (g・cm), D / Fr is less than 1.

7.

5. The cobalt element content in the rubber composition is 2.85 × 10⁻¹⁰ parts by mass of rubber component. -3 A tire according to claim 1 or 2, wherein the mass is less than or equal to the part-of-mass.

6. The tire according to claim 1 or 2, wherein the D / M is less than 3.

0.

7. The tire according to claim 1 or 2, wherein the rubber composition contains silica.

8. The tire according to claim 1 or 2, wherein the steel cord has a ternary plating layer made of copper, zinc, and cobalt.

9. The belt layer comprises a first belt ply and a second belt ply laminated on the radially outer side of the first belt layer. The tire according to claim 1 or 2, wherein when the shortest distance between the steel cord of the second belt ply and the steel cord of the first belt ply in the center portion of the tire is a, and the shortest distance between the steel cord at the outermost end of the second belt ply and the cord of the first belt ply is b, b / a is 1.5 or more.

10. The tire according to claim 1 or 2, wherein the distance from the upper and lower surfaces of the first belt ply to the cord in the center portion of the tire, and the distance from the upper and lower surfaces of the second belt ply to the cord in the center portion, are both 0.14 mm or less.

11. The tire according to claim 1 or 2, further comprising an electronic component.

12. The tire according to claim 1 or 2, wherein the tire is a tire for an electric vehicle, a tire for a hybrid vehicle, or a tire for a plug-in hybrid vehicle.

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