Tire

Abstract

To provide a tire which can achieve improvement in operation stability performance during high-speed travel.SOLUTION: A tire comprises a tread part, and a rubber cord composite having a steel cord and a topping rubber which covers the steel cord. A sum L of cord outer peripheries per 50 mm in a tire width direction at a tire meridian cross section is 65 mm or more, the composite contains an adhesive material for bonding the steel cord and the topping rubber, the adhesive material contains an oxazine compound, and the topping rubber is constituted from a rubber composition containing rubber component, carbon black, and sulfur. When a mass of the rubber component in the composite as a relative amount is represented by A (part), a mass of carbon black is represented by B (part), a mass of sulfur is represented by C (part), and a mass of oxazine compound is represented by D (part), (B+C) / (A+D) is less than 1.0.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] In recent years, in the tire market, particularly, the handling stability performance during high-speed driving has been strongly demanded. Patent Document 1 discloses that by blending a predetermined chitin fiber and / or chitosan fiber into the base rubber constituting the tread portion, heat generation can be reduced, the rigidity of the rubber can be increased, and the handling stability can be improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a tire capable of improving the handling stability performance during high-speed driving.

Means for Solving the Problems

[0005] The present invention is a tire including a tread portion and a rubber cord composite having a steel cord and a topping rubber covering the steel cord, wherein the total L of the outer circumference of the cord per 50 mm in the tire width direction in the tire meridian cross section is 65 mm or more, the composite includes an adhesive material for adhering the steel cord and the topping rubber, the adhesive material includes an oxazine compound, the topping rubber is composed of a rubber composition containing a rubber component, carbon black, and sulfur, and when the mass of the rubber component in the composite as a relative amount is A (parts), the mass of carbon black is B (parts), the mass of sulfur is C (parts), and the mass of the oxazine compound is D (parts), (B + C) / (A + D) is less than 1.0.

Advantages of the Invention

[0006] According to the present invention, there is provided a tire capable of improving the handling stability performance during high-speed driving.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0008] A tire according to an embodiment of the present invention is a tire including a tread portion and a rubber-cord composite having a steel cord and a topping rubber covering the steel cord, wherein the total L of the outer circumference of the cord per 50 mm in the tire width direction in the tire meridian cross-section is 65 mm or more, the composite includes an adhesive material for adhering the steel cord and the topping rubber, the adhesive material includes an oxazine compound, the topping rubber is composed of a rubber composition containing a rubber component, carbon black, and sulfur, and when the mass of the rubber component in the composite as a relative amount is A (parts), the mass of carbon black is B (parts), the mass of sulfur is C (parts), and the mass of the oxazine compound is D (parts), (B + C) / (A + D) is less than 1.0.

[0009] Regarding the reason why the handling stability performance during high-speed driving can be improved in the tire according to the present embodiment, although not intended to be restricted by theory, it is considered as follows.

[0010] In a rubber - cord composite, by relatively increasing the mass of the oxazine compound which is a rubber component and an adhesive component while relatively decreasing the mass of carbon black and sulfur, it is considered that the heat generation can be reduced while ensuring the rigidity of the composite. Also, by making the outer periphery of the cord larger than a predetermined value, it is considered that the adhesiveness between the steel cord and the topping rubber can be improved and the rigidity of the composite can be further improved. Furthermore, the oxazine compound itself can enhance the heat resistance of the topping rubber. By the cooperation of these, it is considered that even when high - speed driving continues for a long time and the composite is repeatedly deformed during driving, it becomes easier to ensure the handling stability.

[0011] From the viewpoint of rolling resistance, B is preferably 70 or less.

[0012] From the viewpoint of durability performance, C is preferably 10 or less.

[0013] From the viewpoint of durability performance, D is preferably 15 or less.

[0014] From the viewpoint of rolling resistance, the total content of the filler with respect to 100 parts by mass of the rubber component in the rubber composition is preferably 70 parts by mass or less.

[0015] The rubber composition preferably contains the oxazine compound. That is, it is preferable that the rubber composition constituting the topping rubber contains the oxazine compound as an adhesive material.

[0016] From the viewpoint of handling stability performance, the distance G from the tread surface to the steel cord is preferably 15 mm or less.

[0017] When the tanδ of the tread rubber at 70 °C is 70 °C tanδ1 and the tanδ of the topping rubber at 70 °C is 70 °C tanδ2, 70 °C tanδ1 / 70 °C tanδ2 is preferably 1.5 or less.

[0018] By setting 70℃ tanδ1 / 70℃ tanδ2 within the above range, it is considered possible to suppress the deterioration of grip performance at high temperatures.

[0019] <Definition> The "tread part" is a member that includes the part forming the contact surface of the tire. In the tire radial cross-section, when the tire skeleton is formed by members such as steel or textile materials like the belt layer, belt reinforcement layer, carcass layer, etc., it is a member arranged more radially outside than those.

[0020] The "normal rim" is the rim defined for each tire in the standard system including the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it refers to the standard rim in the applicable sizes described in the "JATMA YEAR BOOK"; in the case of ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" described in the "STANDARDS MANUAL"; in the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" described in the "YEAR BOOK". Refer to JATMA, ETRTO, and TRA in this order, and follow the standard if there is an applicable size during reference. In the case of a tire not defined in the above standards, it refers to the rim with the narrowest rim width among the minimum diameter rims that can be assembled with the tire and can maintain the internal pressure (i.e., does not cause air leakage between the rim / tire).

[0021] A "filament" is a steel wire that is the smallest unit forming a steel cord.

[0022] The "total L of the outer circumference of the cords per 50 mm in the tire width direction in the tire meridian cross-section" refers to the total length of the outer circumferences of the filaments constituting the steel cords existing per 50 mm in the tire width direction in the tire meridian cross-section.

[0023] "The distance G from the tread surface to the steel cord" refers to the straight-line distance from the crown part on the tire equatorial plane to the outermost part in the tire radial direction of the rubber-cord composite in the tire meridian cross-section. "Crown part" refers to, when there is no circumferential groove on the tire equatorial plane, the outermost end in the tire radial direction of the tread part intersecting with the tire equatorial plane, and when there is a circumferential groove on the tire equatorial plane, it refers to the part where the line segment connecting the outermost tread ends at the land parts at both ends of the circumferential groove intersects with the tire equatorial plane.

[0024] "Plasticizer" is a material that imparts plasticity to the rubber component and is a component extracted from the rubber composition using acetone. Plasticizers include plasticizers that are liquid (in a liquid state) at 25°C and plasticizers that are solid at 25°C. However, waxes and stearic acid commonly used in the tire industry are not included.

[0025] "Content of plasticizer" also includes the amount of plasticizer contained in the stretched rubber component preliminarily stretched by plasticizers such as oil, resin component, and liquid rubber component. The same applies to the content of oil, the content of resin component, and the content of liquid rubber. For example, when the stretching component is oil, the stretched oil is included in the content of oil.

[0026] <Measurement method> "The distance G from the tread surface to the steel cord" is a value measured in a state where the tire is cut by a plane including the tire rotation axis and the width of the bead part is adjusted to the width of the standard rim.

[0027] "tanδ at 70°C" is the loss tangent measured under the conditions of a temperature of 70°C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±1%, and an elongation mode. The sample for measuring tanδ at 70°C is a vulcanized rubber composition with a length of 20 mm × a width of 4 mm × a thickness of 1 mm. When it is cut out from a tire, it is cut out from the topping rubber and the tread part such that the tire circumferential direction is the long side and the tire radial direction is the thickness direction.

[0028] The "nitrogen adsorption specific surface area (N2SA) of carbon black" is measured in accordance with JIS K 6217-2:2017. The "nitrogen adsorption specific surface area (N2SA) of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0029] The manufacturing procedure of the tire according to one embodiment of the present invention will be described in detail below. However, the following description is an exemplification for explaining the present invention and is not intended to limit the technical scope of the present invention only to this description range.

[0030] <Tire> Hereinafter, a tire according to one embodiment of the present invention will be described with reference to the drawings.

[0031] FIG. 1 shows a meridian cross-sectional view of a tire 11 according to the present embodiment. In FIG. 1, only the left side portion of the CL (center line) is shown, but the same structure is continuously provided on the right side of the CL with the CL as the axis of symmetry. As shown in FIG. 1, the tire 11 includes a tread portion 12, a sidewall portion 13, a bead portion 14, an inner liner 15, a carcass 16, a belt layer 17, and a bead wire 18. The belt layer 17 has two layers, but the number of layers is not particularly limited and can be arbitrarily selected.

[0032] FIG. 2 shows a cross-sectional view in a plane orthogonal to the longitudinal direction of the steel cord 21. Each belt layer 17 has a plurality of steel cords 21 and a topping rubber 22. The plurality of steel cords 21 are arranged in parallel in a row. Further, the topping rubber 22 covers the steel cord 21, and the entire circumference of each individual steel cord is covered with the topping rubber 22. The steel cord 21 is embedded in the topping rubber 22.

[0033] The steel cord 21 may be inclined with respect to the tire circumferential direction or may not be inclined. The inclination angle of the steel cord 21 with respect to the tire circumferential direction is not particularly limited, but is set, for example, in the range of 0° to 60°, preferably 5° to 45°, and more preferably 10° to 30°.

[0034] The steel cord 21 includes filaments. The steel cord may be a single-wire monofilament cord (i.e., a cord composed of one steel filament having a 1×1 structure), or may have two or more steel filaments.

[0035] When one steel cord has two or more steel filaments, the steel cord preferably has a twisted structure in which those steel filaments are twisted along its longitudinal direction. The twisted structure is not particularly limited, and for example, it can be a single-twisted steel cord having a 1×N structure or a layer-twisted steel cord having an N+M structure.

[0036] The single-twisted structure can be expressed, for example, as a 1×N structure. The 1×N structure means a structure in which N filaments are twisted to form a single layer. The single layer means a structure in which, in a cross-section perpendicular to the longitudinal direction of the steel cord, the filaments are arranged along the circumferential direction of a single circle in a single layer. Examples of the single-twisted structure in the present embodiment include a 1×2 structure, a 1×3 structure, and a 1×4 structure.

[0037] Figure 3 is a perspective view of a steel cord having a 1×2 structure. The steel cord 50 shown in Figure 3 has two filaments 51 twisted spirally along the longitudinal direction so as to form a single layer.

[0038] The layer-twisted structure has a structure in which, in a cross-section perpendicular to the longitudinal direction of the steel cord, a plurality of filaments are wound in a plurality of layers in order from the center, and can be expressed, for example, as an N+M structure. The N+M structure means a structure having a core in which N filaments are twisted spirally along its longitudinal direction and an outer sheath in which M filaments are twisted spirally along the longitudinal direction of the core so as to cover the outer periphery of the core.

[0039] FIG. 4 is a perspective view of a steel cord having a 3 + 8 structure, and FIG. 5 schematically shows a cross-sectional view in a plane perpendicular to the longitudinal direction of FIG. 4. The steel cord 30 shown in FIGS. 4 and 5 has three filaments 31 twisted together to form a core 311 as the first layer. Further, around the core 311, eight filaments 32 are spirally twisted along the longitudinal direction of the core 311 to form a single-layer outer sheath 321. Here, the term "single layer" means a structure in which, in a cross-section perpendicular to the longitudinal direction of the steel cord, the filaments are arranged in a single layer (one layer) along the circumferential direction of a single circle. Specifically, as shown in FIG. 5, the filaments 32 constituting the outer sheath 321 are arranged so as to form a single layer between the circumscribed circle C1 of the core 311 and the circumscribed circle C2 of the outer sheath 321.

[0040] The layer-twisted structure is not limited to the above-described embodiment. For example, a three-layer twisted structure in which a plurality of additional filaments are spirally twisted along the longitudinal direction of the core 311 can be formed on the outer periphery of the outer sheath 321 of the steel cord 30 shown in FIGS. 4 and 5. Further, the number of filaments constituting the core 311 and the outer sheath 321 is not particularly limited, and can be arbitrarily selected according to the filament diameter (diameter of the filament) and the like.

[0041] The material of the steel filament is not particularly limited, and HT material (High Tensile), SHT material (Super High Tensile), UHT material (Ultra High Tensile), etc. can be used. Further, recycled iron obtained by melting used iron products may also be used. When using a steel cord in which a plurality of steel filaments are twisted together, from the viewpoint of improving the durability by making it easier for the topping rubber to enter the inside of the steel cord, steel filaments pre-bent in the longitudinal direction may be used.

[0042] The filament diameter of the steel cord is not particularly limited and can be arbitrarily selected according to required characteristics and the like. However, from the viewpoint of ensuring the durability of the steel cord against impact, 0.13 mm or more is more preferable, 0.16 mm or more is further preferable, 0.19 mm or more is further preferable, 0.22 mm or more is further preferable, and 0.25 mm or more is particularly preferable. Also, from the viewpoint of sufficiently absorbing impact and improving the riding comfort performance, 0.70 mm or less is preferable, 0.60 mm or less is more preferable, 0.50 mm or less is further preferable, 0.40 mm or less is further preferable, and 0.35 mm or less is particularly preferable.

[0043] The steel cord according to this embodiment may be provided with a plating layer. Since the steel cord having a plating layer exhibits high moisture and heat resistant adhesion performance even under severe conditions of high temperature and high humidity, peeling between the topping rubber and the steel cord can be prevented, and the durability of the tire under moisture and heat conditions can be improved. When the steel cord has a plurality of filaments, a plating layer can be provided on the surface of each filament.

[0044] The plating layer can be formed by plating a copper layer, a zinc layer, a cobalt layer, etc. on the filament before wire drawing, and then heat-treating to diffuse the metals of the respective layers formed on the surface of the filament. Note that the lamination order formed on the filament for forming the plating layer is not particularly limited.

[0045] Next, the heat-treated material is wire-drawn to have a desired filament diameter, whereby a filament having a plating layer can be formed. When the steel cord is composed of one filament, it can be used as it is after wire drawing. Also, when the steel cord has a plurality of filaments, after wire drawing, the obtained filaments can be twisted, for example, to have a desired twist structure to obtain a steel cord having a plating layer.

[0046] The number of cords per 50 mm in the tire width direction in the tire meridian cross-section (also called ends) can be appropriately selected so that the total L of the outer circumferences of the cords per 50 mm in the tire width direction in the tire meridian cross-section satisfies the range described below. Preferably, it is 33 or more, more preferably 34 or more, and even more preferably 35 or more. Also, the ends are preferably 80 or less, more preferably 70 or less, even more preferably 60 or less, still more preferably 50 or less, and particularly preferably 45 or less.

[0047] The total L of the outer circumferences of the cords per 50 mm in the tire width direction in the tire meridian cross-section is 65 mm or more, and preferably 66 mm or more. By setting L within the above range, it is considered that the adhesiveness between the steel cord and the topping rubber can be improved, and the rigidity of the composite can be further improved. On the other hand, the lower limit value of L is not particularly limited, but preferably 78 mm or less, more preferably 76 mm or less, even more preferably 74 mm or less, and particularly preferably 72 mm or less.

[0048] (Rubber-cord composite) By coating the above-mentioned steel cord with a predetermined topping rubber according to a conventional method, the rubber-cord composite according to the present embodiment can be obtained.

[0049] The rubber-cord composite according to the present embodiment includes an adhesive material for adhering the steel cord and the topping rubber. The adhesive material may be compounded in the topping rubber or applied to the cord surface, but it is preferably compounded in the topping rubber. That is, it is preferable that the rubber composition constituting the topping rubber contains the adhesive material.

[0050] The adhesive material according to this embodiment contains an oxazine compound. The oxazine compound is not particularly limited as long as it is a compound containing a 6-membered heterocyclic ring including one oxygen atom, one nitrogen atom, and a double bond. From the viewpoints of crosslinkability, adhesiveness, curability, etc., a benzoxazine compound is preferable, a benzoxazine compound having two or more benzoxazine rings in one molecule is more preferable, and a benzoxazine compound having two 1,3-benzoxazine rings in one molecule is even more preferable.

[0051] Specific examples of the benzoxazine compound include, for example, a Pd-type benzoxazine compound obtained by the reaction of a diphenyldiamine compound, a phenol compound, and formaldehyde; a Fa-type benzoxazine compound obtained by the reaction of a bisphenol compound, an amine compound, and formaldehyde, etc. From the viewpoint of heat resistance, a Pd-type benzoxazine compound is preferable.

[0052] As the Pd-type benzoxazine compound, for example, the following formula (1):

Chemical formula

[0053] n and m are preferably 0. R 1 and R 2 each independently are preferably a hydrogen atom or a methyl group. X 1 is preferably a methylene group.

[0054] As the Fa-type benzoxazine compound, for example, the following formula (2): [Chemical] (In the formula, R 3 and R 4 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group (the phenyl may be substituted with 1 to 3 halogen atoms, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms); X 2 represents an alkylene group having 1 to 6 carbon atoms, a group represented by the formula "-SO2-", a group represented by the formula "-CO-", an oxygen atom, or a single bond), and examples of the compound include those represented by the formula.)

[0055] R 3 and R 4 are each independently preferably a phenyl group (the phenyl may be substituted with 1 to 3 alkyl groups having 1 to 6 carbon atoms). X 2 is preferably a methylene group.

[0056] The adhesive material according to this embodiment may further contain an adhesive material other than the oxazine compound.

[0057] From the viewpoint of durability performance during high-speed driving, the tanδ (70°C tanδ1) of the tread rubber at 70°C is preferably 0.25 or less, more preferably 0.20 or less, and even more preferably 0.18 or less. On the other hand, from the viewpoint of grip performance, it is preferably 0.08 or more, more preferably 0.10 or more, and even more preferably 0.12 or more. When the tread portion 12 is composed of two or more rubber layers, the 70°C tanδ1 refers to the tanδ at 70°C of the outermost rubber layer constituting the tread surface.

[0058] From the viewpoint of rolling resistance, the tanδ (70°C tanδ2) of the topping rubber at 70°C is preferably 0.20 or less, more preferably 0.18 or less, and even more preferably 0.16 or less. On the other hand, from the viewpoint of grip performance at high temperatures, it is preferably 0.06 or more, more preferably 0.08 or more, and even more preferably 0.10 or more.

[0059] The 70°C tanδ1 / 70°C tanδ2 is preferably 1.5 or less, more preferably 1.4 or less. By setting 70°C tanδ1 / 70°C tanδ2 within the above range, it is considered that a decrease in grip performance at high temperatures can be suppressed. On the other hand, the lower limit value of 70°C tanδ1 / 70°C tanδ2 is not particularly limited, but is preferably 0.6 or more, more preferably 0.8 or more, still more preferably 1.0 or more, still more preferably 1.1 or more, and particularly preferably 1.2 or more.

[0060] Incidentally, the 70°C tanδ of the rubber compositions constituting the topping rubber and the tread rubber can be appropriately adjusted according to the types and blending amounts of the following rubber components, fillers, plasticizers, vulcanizing agents, vulcanization accelerators, etc.

[0061] When the mass of the rubber component in the rubber - cord composite as a relative amount is A (parts), the mass of carbon black is B (parts), the mass of sulfur is C (parts), and the mass of the oxazine compound is D (parts), (B + C) / (A + D) is less than 1.0, preferably less than 0.90, more preferably less than 0.80, still more preferably less than 0.75, still more preferably less than 0.70, and particularly preferably less than 0.66. By relatively increasing the mass of the rubber component and the oxazine compound as the adhesive component while relatively decreasing the mass of carbon black and sulfur, it is considered that the heat generation can be reduced while ensuring the rigidity of the composite. On the other hand, from the viewpoint of durability performance, (B + C) / (A + D) is preferably more than 0.01, more preferably more than 0.10, and still more preferably more than 0.50.

[0062] [Rubber Composition] The rubber composition (hereinafter referred to as the rubber composition according to the present embodiment) constituting the topping rubber 22 that coats the steel cord contains a rubber component, carbon black, and sulfur, and all can be manufactured using the raw materials described below. Hereinafter, the rubber composition according to the present embodiment will be described.

[0063] [Rubber Component]< In the rubber composition according to this embodiment, a diene rubber is preferably used as the rubber component. Examples of the diene rubber include isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and the like. These diene rubbers may be modified rubbers treated with a modifying group capable of interacting with a filler such as carbon black or silica, or may be hydrogenated rubbers in which a part of the unsaturated bonds is hydrogenated. The diene rubber may be used alone or in combination of two or more. Further, as the diene rubber, an extended rubber preliminarily extended using a plasticizer described later may be used.

[0064] The content of the diene rubber in the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Further, it may be a rubber component composed only of the diene rubber.

[0065] From the viewpoints of cord adhesiveness and elongation at break, the rubber component according to this embodiment more preferably contains an isoprene rubber, and may be a rubber component composed only of the isoprene rubber.

[0066] (Isoprene rubber) The isoprene rubber is not particularly limited, and examples thereof include natural rubber (NR), isoprene rubber (IR), and modified natural rubber. Examples of NR include SIR20, RSS#3, and TSR20. Examples of IR include IR2200. Examples of the modified natural rubber include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, and grafted natural rubber. These isoprene rubbers may be used alone or in combination of two or more.

[0067] From the viewpoint of the effects of the present invention, the content in the rubber component when containing isoprene rubber is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more. Further, the upper limit value of the content is not particularly limited and may be 100% by mass.

[0068] (SBR) Although SBR is not particularly limited, for example, unmodified solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), modified SBR of these (modified S-SBR, modified E-SBR), etc. can be mentioned. Examples of modified SBR include SBR in which the terminal and / or main chain is modified, and modified SBR coupled with tin, silicon compounds, etc. (condensates, those having a branched structure, etc.). Further, hydrogenated products of these SBRs (hydrogenated SBR) etc. can also be used. These SBRs may be used alone or in combination of two or more.

[0069] From the viewpoint of the effects of the present invention, the content in the rubber component when containing SBR is preferably less than 40% by mass, more preferably less than 20% by mass, still more preferably less than 10% by mass, and particularly preferably less than 5% by mass.

[0070] (BR) Although BR is not particularly limited, 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-based butadiene rubber synthesized using a rare-earth element-based catalyst (rare-earth-based BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc., which are common in the tire industry, can be used. These BRs may be used alone or in combination of two or more.

[0071] From the viewpoint of the effects of the present invention, the content in the rubber component when containing BR is preferably less than 40% by mass, more preferably less than 20% by mass, still more preferably less than 10% by mass, and particularly preferably less than 5% by mass.

[0072] (Other rubber components) The rubber component may contain a rubber component other than a diene rubber (non-diene rubber) as long as it does not affect the effects of the present invention. As the non-diene rubber, rubber components generally used in the tire industry can be used. For example, butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), hydrin rubber, etc. can be mentioned. These other rubber components may be used alone or in combination of two or more. In addition to the above rubber components, a known thermoplastic elastomer may or may not be contained.

[0073] (Rubber components synthesized from recycled and biomass-derived raw materials) The monomers that are constituent units of synthetic rubbers such as IR, BR, and SBR may be derived from underground resources such as petroleum and natural gas, or may be recycled from rubber products such as tires and non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl compound is not particularly limited, and examples include styrene. Among them, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and recycled styrene (recycled styrene) as raw materials.

[0074] The method for producing the recycled monomer is not particularly limited. For example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Also, the method for producing recycled naphtha is not particularly limited. For example, rubber products such as tires may be decomposed under high temperature and high pressure, decomposed by microwaves, or extracted after mechanical pulverization.

[0075] Furthermore, monomers that are constituent units of synthetic rubbers such as IR, BR, and SBR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, and examples include agricultural and forestry products, sugars, wood chips, plant residues after obtaining useful components, ethanol derived from plants, biomass naphtha, and the like.

[0076] The biomass-derived monomers (biomass monomers) are not particularly limited, and examples include biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl compound is not particularly limited, and examples include styrene. Also, the method for producing biomass monomers is not particularly limited, and examples include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical as biological conversion, and examples of chemical and / or physical conversion include those by catalysts, high heat, high pressure, electromagnetic waves, supercritical fluids, and combinations thereof.

[0077] The polymers synthesized from biomass monomer components (biomass polymers) are 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.

[0078] Whether the raw material of the polymer is derived from biomass can be determined by pMC (percent Modern Carbon) measured in accordance with ASTM D6866-10.

[0079] pMC is the ratio of the 14 C concentration of the sample to that of the 14 C concentration of the modern standard reference, and is a value used as an indicator to show the biomass ratio of a compound. The significance of this value is described below.

[0080] In one mole (6.02×10 23 atoms) of carbon atoms, there are approximately 6.02×10 11 atoms of 14 C, which is about one trillionth of the normal carbon atoms. 14 The half-life of 14 C is 5730 years, and 14 C decreases regularly. It takes 226,000 years for all of them to decay. Therefore, in fossil fuels such as coal, oil, and natural gas, which are considered to have passed more than 226,000 years after carbon dioxide in the atmosphere was taken up and fixed by plants, etc., all the 14 C elements originally contained in them have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain any 14 C elements at all. Therefore, chemical substances produced from these fossil fuels also do not contain any 14 C elements.

[0081] On the other hand, 14 C is constantly generated by cosmic rays undergoing nuclear reactions in the atmosphere. From this, 14 C is in equilibrium between the decrease due to radioactive decay and the generation due to nuclear reactions, and in the earth's atmospheric environment, the amount of 14 C is a certain amount. Therefore, the 14 C concentration of substances derived from biomass resources circulating in the current environment is about 1×10 -12 mol% with respect to the entire carbon atoms as described above. Therefore, by using the difference between these values, the biomass ratio in a certain compound can be calculated.

[0082] This 14C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 the C concentration ( 13 C / 12 C), 14 the C concentration ( 14 C / 12 C) is measured. In the measurement, 14 as a modern standard reference for the concentration of 14 C, the concentration of 14 C in the circulating carbon in nature in 1950 is adopted. As a specific reference material, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific activity of carbon in this oxalic acid (the radioactivity intensity of 14 C per gram of carbon) is fractionated for each carbon isotope, 13 corrected to a constant value for 14 C, and the value obtained by applying the decay correction from 1950 AD to the measurement date is used as the value of the standard 14 C concentration (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0083] Therefore, if the rubber is made of 100% biomass-derived materials, although there are regional differences and the like, it usually does not reach 100 under normal conditions at present, so it will show a value of about 110 pMC. On the other hand, for chemical substances derived from fossil fuels such as petroleum, when the concentration of 14 C is measured, it will show a value of about 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% mentioned above.

[0084] From the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in the rubber composition is suitable from the perspective of environmental protection.

[0085] <Filler> The rubber composition according to this embodiment contains carbon black as a filler, and may further contain silica. Further, the filler may be a filler consisting only of carbon black.

[0086] (Carbon black) The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw material of the carbon black may be a biomass material such as lignin or vegetable oil, or may be a pyrolysis oil obtained by pyrolyzing waste tires. Further, the production method of the carbon black may be by combustion such as the furnace method, may be by hydrothermal carbonization (HTC), or may be by thermal decomposition of methane such as the thermal black method. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbian Carbon Co., etc. can be used. These carbon blacks may be used alone or in combination of two or more.

[0087] In addition to the above, from the viewpoint of life cycle assessment and the like, carbon black made from biomass materials such as lignin or recycled carbon black obtained by pyrolyzing and purifying products containing carbon black such as tires may be used as the carbon black.

[0088] In this specification, "recycled carbon black" refers to carbon black obtained by pulverizing used products such as tires containing carbon black and firing the pulverized product, and when oxidized and burned by heating in air by a thermogravimetric method conforming to JIS K 6226-2:2003, it refers to carbon black in which the ratio of the mass of the component that does not burn (ash content) is 13% by mass or more. That is, the ratio of the mass of the weight loss (carbon amount) due to the oxidative combustion of the recycled carbon black is 87% by mass or less. Recycled carbon black may also be represented by rCB.

[0089] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975 refers to "Rubber Chemistry and Technology", Vol. 85, No. 3, pages 408 - 449 (2012), especially pages 438, 440, 442, and describes that it can be obtained by pyrolysis of organic materials at 550 - 800 °C with oxygen excluded, or by vacuum pyrolysis at relatively low temperatures (

[0027] ). The carbon black obtained from such a pyrolysis process usually lacks functional groups on its surface, as mentioned in

[0004] of Patent No. 6856781 (Comparison of the surface morphology and chemistry of pyrolytic carbon black and commercially available carbon black, Powder Technology 160 (2005) 190 - 193).

[0090] Recycled carbon black may lack functional groups on its surface, or may be treated to contain functional groups on its surface. The treatment to make the recycled carbon black contain functional groups on its surface 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. Also, in Patent 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 such carbon black treated to contain functional groups on its surface.

[0091] Recycled carbon black commercially available from Strable Green Carbon, LDCarbon, etc. can be used.

[0092] From the perspective of reinforcement, the nitrogen adsorption specific surface area (N2SA) of carbon black is 20 m 2 / g or more is preferable, 30 m 2 / g or more is more preferable, 40 m 2 / g or more is even more preferable, 50 m 2 / g or more is particularly preferable. Further, from the viewpoint of low fuel consumption performance, the N2SA of the carbon black is 120 m 2 / g or less is preferable, 100 m 2 / g or less is more preferable, 90 m 2 / g or less is even more preferable. The N2SA of the carbon black is measured by the above measurement method.

[0093] The average primary particle diameter of the carbon black is preferably 36 nm or less, more preferably 32 nm or less, even more preferably 28 nm or less, and particularly preferably 24 nm or less. The lower limit of the average primary particle diameter is not particularly limited, but preferably 5 nm or more, more preferably 8 nm or more, and even more preferably 10 nm or more. The average primary particle diameter of the carbon black is measured by the above measurement method.

[0094] From the viewpoint of durability performance, the content of carbon black with respect to 100 parts by mass of the rubber component is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 40 parts by mass or more. Further, from the viewpoint of rolling resistance, 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, even more preferably 75 parts by mass or less, even more preferably 70 parts by mass or less, and particularly preferably 65 parts by mass or less.

[0095] (Silica) The silica is not particularly limited, and for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), etc., which are common in the tire industry, can be used. The raw material of the silica is not particularly limited, and for example, it may be a raw material derived from a mineral such as quartz, or it may be a raw material derived from a living organism such as rice husk (for example, silica using a biomass material such as rice husk as a raw material), or silica recycled from a product containing silica may be used. Among them, hydrous silica prepared by a wet method is preferred because it has many silanol groups. These silicas may be used alone or in combination of two or more.

[0096] Silica using a biomass material as a raw material can be obtained, for example, by extracting a silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to obtain a precipitate of silicon dioxide, which is then filtered, washed with water, dried, and pulverized.

[0097] As the silica recycled from a product containing silica, for example, silica recovered from products containing silica such as electronic components such as semiconductors, tires, desiccants, and filter materials such as diatomaceous earth can be used. The recovery method is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among them, silica recovered from electronic components such as semiconductors or tires is preferred.

[0098] When silica crystallizes, it does not dissolve in water and the silicic acid that is its component cannot be utilized. By controlling the combustion temperature and combustion time, crystallization of the silica in the rice husk ash can be suppressed (see, for example, JP-A-2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.).

[0099] Amorphous silica extracted from rice husks can be those commercially available from companies such as Wilmar.

[0100] The nitrogen adsorption specific surface area (N2SA) of the silica is 100 m from the viewpoints of abrasion resistance performance and elongation at break.2 Above / g is preferable, and 120m 2 Above / g is more preferable, and 140m 2 Above / g is even more preferable, and 160m 2 Above / g is particularly preferable. Also, from the viewpoints of heat generation property and processability, 350m 2 Below / g is preferable, and 300m 2 Below / g is more preferable, and 250m 2 Below / g is even more preferable. Note that the N2SA of silica is measured by the above measurement method.

[0101] 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 value of the average primary particle diameter is not particularly limited, but from the viewpoint of the dispersibility of silica, 1 nm or more is preferable, 3 nm or more is more preferable, and 5 nm or more is even more preferable. Note that the average primary particle diameter of silica is measured by the above measurement method.

[0102] The content of silica with respect to 100 parts by mass of the rubber component when contained is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 12 parts by mass or more, and particularly preferably 14 parts by mass or more from the viewpoints of low fuel consumption performance and adhesiveness. Also, from the viewpoint of tire strength, 50 parts by mass or less is preferable, 45 parts by mass or less is more preferable, 40 parts by mass or less is even more preferable, and 35 parts by mass or less is particularly preferable.

[0103] (Other fillers) The filler may contain other fillers other than silica and carbon black. The other fillers are not particularly limited, but for example, aluminum hydroxide, calcium carbonate, alumina, clay, talc, etc., which have been conventionally commonly used in the tire industry, can be compounded.

[0104] From the perspective of rolling resistance, the total filler content relative to 100 parts by mass of the rubber component is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, still more preferably 80 parts by mass or less, still more preferably 75 parts by mass or less, still more preferably 70 parts by mass or less, and particularly preferably 65 parts by mass or less. From the perspective of durability performance, it is preferably 35 parts by mass or more, more preferably 40 parts by mass or more, still more preferably 45 parts by mass or more, and particularly preferably 50 parts by mass or more.

[0105] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited. For example, sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, etc. Among them, it is preferably to contain a sulfide-based silane coupling agent and / or a mercapto-based silane coupling agent. As the silane coupling agent, for example, those commercially available from Evonik Degussa, Momentive, etc. can be used. These silane coupling agents may be used alone or in combination of two or more.

[0106] When contained, the content of the silane coupling agent relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, still more preferably 2.0 part by mass or more, and particularly preferably 4.0 part by mass or more from the viewpoint of enhancing the dispersibility of silica. Further, from the viewpoint of preventing a decrease in abrasion resistance performance, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 12 parts by mass or less.

[0107] <Oxazine compound> The rubber composition according to the present embodiment preferably contains an oxazine compound. As the oxazine compound, for example, the above-mentioned oxazine compound contained in the rubber - cord composite can be used.

[0108] When the rubber composition according to the present embodiment contains an oxazine compound, the content relative to 100 parts by mass of the rubber component is preferably 1.0 part by mass or more, more preferably 2.0 part by mass or more, still more preferably 3.0 part by mass or more from the viewpoint of adhesiveness. Further, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 12 parts by mass or less.

[0109] <Cobalt compound> The rubber composition according to the present embodiment preferably contains a cobalt compound. By containing a cobalt compound, the adhesive force between the steel cord and the topping rubber can be enhanced, and a tire excellent in durability can be obtained. Examples of the cobalt compound include cobalt alone, cobalt chloride, cobalt organic acid, cobalt inorganic acid, etc., and cobalt organic acid is preferred. These cobalt compounds may be used alone or in combination of two or more.

[0110] Cobalt organic acid is suitably used to promote the adhesion between the plating layer of the steel cord and the rubber composition and to prevent the plating components from flowing out into the rubber composition during hygrothermal deterioration. The number of carbon atoms of the organic acid constituting the cobalt organic acid is preferably 12 or more and 24 or less, more preferably 14 or more and 22 or less. Specific examples of cobalt organic acid salts include, for example, cobalt stearate, cobalt naphthenate, cobalt neodecanoate, cobalt rosinate, cobalt versatate, cobalt tallate, cobalt oleate, cobalt linoleate, cobalt linolenate, cobalt palmitate, and the like. Further, the cobalt organic acid may be a complex salt (for example, cobalt boron trineodecanoate) in which part of the organic acid is replaced with boric acid.

[0111] Examples of cobalt inorganic acid include cobalt sulfate, cobalt nitrate, cobalt phosphate, cobalt chromate, and the like.

[0112] From the viewpoint of adhesiveness, the content of the cobalt compound contained per 100 parts by mass of the rubber component is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, and still more preferably 0.5 part by mass or more. Further, the content is preferably 3.0 parts by mass or less, more preferably 2.0 parts by mass or less, and still more preferably 1.5 parts by mass or less.

[0113] <Other compounding agents> In addition to the above components, the rubber composition according to this embodiment may appropriately contain compounding agents generally used in the conventional tire industry, such as plasticizers, thermosetting resins, zinc organic acid, vulcanized rubber particles, processing aids, waxes, anti-aging agents, stearic acid, zinc oxide, vulcanizing agents, vulcanization accelerators, and the like.

[0114] A plasticizer is a material that imparts plasticity to a rubber component, and is a concept that includes both plasticizers that are liquid at 25°C and plasticizers that are solid at normal temperature (25°C). Examples of plasticizers include resin components, oils, liquid rubbers, ester-based plasticizers, etc. These plasticizers may be derived from mineral resources such as petroleum and natural gas, may be derived from biomass, or may be derived from naphtha recycled from rubber products or non-rubber products. Also, low-molecular-weight hydrocarbon components obtained by pyrolyzing and extracting used tires and products containing various components may be used as plasticizers. These plasticizers may be used alone or in combination of two or more.

[0115] The resin component is not particularly limited, but resin components commonly used in the tire industry can be used. For example, tackifying resins such as dicyclopentadiene-based resins, aromatic vinyl-based resins, C9-based resins, C5-based resins, C5C9-based resins, coumarone-based resins, indene-based resins, terpene-based resins, rosin-based resins, and phenol-based resins can be mentioned. These resin components may be used alone or in combination of two or more.

[0116] Examples of oils include mineral oils, vegetable oils, animal oils, etc. Also, from the perspective of life cycle assessment, waste oils after being used in rubber mixers or engines, or refined waste cooking oils used in restaurants may be used.

[0117] In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oil (mineral oil), naphthenic oil, aromatic oil, etc. Specific examples of mineral oil include, for example, MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. Also, oils with a low content of polycyclic aromatic (PCA) compounds can be used for environmental protection. Examples of the low-PCA-content oils include MES, TDAE, heavy naphthenic oil, etc.

[0118] In this specification, "vegetable oil" refers to, 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, grape seed oil, wood wax, etc. Furthermore, vegetable oils 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, oxidatively polymerized oils obtained by oxidizing the above oils, waste edible oils recovered from those used as edible oils, etc. Note that vegetable oil may be liquid or solid at room temperature (25°C). These vegetable oils may be used alone or in combination of two or more.

[0119] 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 the hydroxy group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited, and may be any of 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, and triacylglycerol. Further, the acylglycerol may be a monomer, a dimer, or a multimer of three or more units. Note that acylglycerols of two or more units can be obtained by thermal polymerization, oxidative polymerization, or the like. Also, the acylglycerol may be liquid or solid at normal temperature (25°C).

[0120] The method for confirming whether the acylglycerol is contained in the rubber composition is not particularly limited. For example, the following 1 can be confirmed by 1H-NMR measurement. Specifically, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at normal temperature (25°C) for 24 hours. After removing the rubber composition, 1 1H-NMR is measured. When the signal of tetramethylsilane (TMS) is set to 0.00 ppm, signals are observed around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm. These signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" means a range of ±0.10 ppm.

[0121] The fatty acid is not particularly limited, and may be an unsaturated fatty acid or a saturated fatty acid. Examples of the unsaturated fatty acid include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of the saturated fatty acid include butyric acid and lauric acid.

[0122] Among these, as the fatty acid, it is desirable to contain a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As the vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or a vegetable oil subjected to modification such as transesterification may be used. Further, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by variety improvement, genetic recombination, or the like.

[0123] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0124] Examples of the animal oil include fish oil, beef tallow, or oleyl alcohol that can be derived therefrom.

[0125] From the viewpoint of the effects of the present invention, the content with respect to 100 parts by mass of the rubber component when containing oil is preferably 1.0 part by mass or more, more preferably 1.5 part by mass or more, and still more preferably 2.0 part by mass or more. Also, the content is preferably less than 40 parts by mass, more preferably less than 30 parts by mass, still more preferably less than 20 parts by mass, and particularly preferably less than 10 parts by mass.

[0126] The liquid rubber is not particularly limited as long as it is a polymer in a liquid state at normal temperature (25°C). Examples thereof include liquid butadiene rubber (liquid BR), liquid styrene-butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene-isoprene rubber (liquid SIR), liquid farnesene rubber, and the like. These liquid rubbers may be used alone or in combination of two or more.

[0127] Examples of ester plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), bis(2-ethylhexyl) azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), and the like. These ester plasticizers may be used alone or in combination of two or more.

[0128] From the viewpoint of the effects of the present invention, the content of the plasticizer relative to 100 parts by mass of the rubber component (the total amount of all plasticizers when a plurality of plasticizers are used in combination) is preferably 1.0 part by mass or more, more preferably 1.5 parts by mass or more, and further preferably 2.0 parts by mass or more. Also, the content is preferably less than 40 parts by mass, more preferably less than 30 parts by mass, further preferably less than 20 parts by mass, and particularly preferably less than 10 parts by mass.

[0129] A thermosetting resin refers to a resin that polymerizes by heating to form a polymer with a network structure and hardens so that it cannot return to its original state. The thermosetting resin is not particularly limited, and examples include resorcinol resin, modified resorcinol resin, cresol resin, modified cresol resin, phenol resin, modified phenol resin, and the like. These thermosetting resins may be used alone or in combination of two or more. By blending these thermosetting resins, the adhesiveness to the cord, the elongation at break, and the complex elastic modulus can be improved.

[0130] The number of carbon atoms of the organic acid constituting the zinc organic acid is preferably 10 or more and 24 or less, more preferably 12 or more and 22 or less. Specific examples of the zinc organic acid include, for example, zinc laurate, zinc oleate, zinc stearate, zinc benzoate, zinc t-butylbenzoate, and the like. These zinc organic acids may be used alone or in combination of two or more.

[0131] The vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder and the like specified in JIS K 6316:2017 can be used. From the viewpoints of environmental consideration and cost, recycled rubber powder produced from crushed waste tires and the like is preferred. These may be used alone or in combination of two or more.

[0132] The vulcanized rubber particles are not particularly limited, and may be non-modified vulcanized rubber particles or modified vulcanized rubber particles. As commercially available products of vulcanized rubber, for example, products of Lehigh, Murakami Rubber Industry Co., Ltd. and the like can be used.

[0133] When containing vulcanized rubber particles, the content thereof can be appropriately adjusted within the range of, for example, more than 1 part by mass and less than 80 parts by mass with respect to 100 parts by mass of the rubber component.

[0134] Examples of the processing aid include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, mixtures of fatty acid metal salts and fatty acid amides, and the like. As the processing aid, for example, those commercially available from Schill+Seilacher, Performance Additives and the like can be used. These processing aids may be used alone or in combination of two or more.

[0135] When contained, the content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1 part by mass, and still more preferably more than 1.5 parts by mass from the viewpoint of exerting the effect of improving processability. Further, from the viewpoints of abrasion resistance and breaking strength, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and still more preferably less than 5.0 parts by mass.

[0136] The wax is not particularly limited, and any of those usually used in the tire industry can be preferably used. Examples thereof include 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 them, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, candelilla wax, etc. Examples of mineral waxes include paraffin wax, microcrystalline wax, and their selected special waxes, etc., and paraffin wax is preferred. Note that the wax according to this embodiment does not contain stearic acid. As the wax, for example, those commercially available from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., etc. can be used. These waxes may be used alone or in combination of two or more.

[0137] When contained, the content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and still more preferably 1.5 part by mass or more from the viewpoint of the weather resistance of the rubber. Further, from the viewpoint of preventing whitening of the tire due to blooming, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0138] The anti-aging agent is not particularly limited, but examples 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; p-phenylenediamine-based anti-aging agents such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditoly-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bis, tris, polyphenol-based anti-aging agents such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercial products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys Co., etc. can be used. These anti-aging agents may be used alone or in combination of two or more.

[0139] When containing an anti-aging agent, from the viewpoint of the ozone crack resistance of the rubber, the content per 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 part by mass or more. Also, from the viewpoints of abrasion resistance performance and wet grip performance, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0140] When contained, the content of stearic acid relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and still more preferably 1.5 part by mass or more from the viewpoint of processability. Further, from the viewpoint of vulcanization rate, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0141] When contained, the content of zinc oxide relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and still more preferably 1.5 part by mass or more from the viewpoint of processability. Further, from the viewpoint of abrasion resistance performance, it is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and still more preferably 10 parts by mass or less.

[0142] Sulfur is preferably used as the vulcanizing agent. As the sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, etc. can be used. Further, as the vulcanizing agent other than sulfur, known organic crosslinking agents can also be used. These vulcanizing agents may be used alone or in combination of two or more.

[0143] The content of sulfur relative to 100 parts by mass of the rubber component is preferably 4.0 parts by mass or more, more preferably 5.0 parts by mass or more, still more preferably 5.5 parts by mass or more, still more preferably 5.7 parts by mass or more, and particularly preferably 6.0 parts by mass or more from the viewpoint of the adhesion performance of the steel cord. Further, from the viewpoint of durability performance, it is preferably 10 parts by mass or less, more preferably 9.0 parts by mass or less, still more preferably 8.0 parts by mass or less, and particularly preferably 7.0 parts by mass or less. In addition, when oil-containing sulfur is used as the vulcanizing agent, the content of the vulcanizing agent is the total content of the pure sulfur component contained in the oil-containing sulfur.

[0144] Examples of the vulcanization accelerator include sulfenamide - type vulcanization accelerators, thiazole - type vulcanization accelerators, thiuram - type vulcanization accelerators, guanidine - type vulcanization accelerators, dithiocarbamate - type vulcanization accelerators, caprolactam disulfide, and the like. These vulcanization accelerators may be used alone or in combination of two or more. Among them, from the viewpoint of more suitably obtaining the desired effect, one or more vulcanization accelerators selected from the group consisting of sulfenamide - type vulcanization accelerators and thiazole - type vulcanization accelerators are preferred, and sulfenamide - type vulcanization accelerators are more preferred.

[0145] Examples of the sulfenamide - type vulcanization accelerators include N - tert - butyl - 2 - benzothiazolylsulfenamide (TBBS), N - cyclohexyl - 2 - benzothiazolylsulfenamide (CBS), N,N - dicyclohexyl - 2 - benzothiazolylsulfenamide (DCBS), and the like. Among them, TBBS and CBS are preferred.

[0146] Examples of the thiazole - type vulcanization accelerators include 2 - mercaptobenzothiazole (MBT) or its salts, di - 2 - benzothiazolyldisulfide (MBTS), 2 - (2,4 - dinitrophenyl) mercaptobenzothiazole, 2 - (2,6 - diethyl - 4 - morpholinothio) benzothiazole, and the like. Among them, MBTS and MBT are preferred, and MBTS is more preferred.

[0147] Examples of the guanidine - type vulcanization accelerators include 1,3 - diphenylguanidine (DPG), 1,3 - di - o - tolguanidine, 1 - o - tolbiguanide, di - o - tolguanidine salt of dicatecholborate, 1,3 - di - o - cumenylguanidine, 1,3 - di - o - biphenylguanidine, 1,3 - di - o - cumenyl - 2 - propionylguanidine, and the like. Among them, DPG is preferred. However, from the viewpoint of the effects of the present invention, the content of the guanidine - type vulcanization accelerator with respect to 100 parts by mass of the rubber component is preferably 0.5 part by mass or less, more preferably 0.3 part by mass or less, further preferably 0.1 part by mass or less, and particularly preferably not containing the guanidine - type vulcanization accelerator.

[0148] When containing a vulcanization accelerator, the content relative to 100 parts by mass of the rubber component is preferably 0.3 part by mass or more, preferably 0.5 part by mass or more, and more preferably 0.7 part by mass or more from the viewpoint of ensuring a sufficient vulcanization rate. Further, the content of the vulcanization accelerator is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, and even more preferably 3.0 parts by mass or less from the viewpoint of suppressing blooming.

[0149] In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the various materials from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation step of synthesizing methane from carbon dioxide may be converted.

[0150] <Manufacture> The rubber composition according to this embodiment can be manufactured by a known method. For example, it can be manufactured by kneading the above-mentioned respective components using a rubber kneading device such as an open roll, a closed kneader (Banbury mixer, kneader, etc.).

[0151] The kneading process includes, for example, a base kneading process of kneading compounding agents and additives other than the vulcanizing agent and the vulcanization accelerator, and a final kneading (F kneading) process of adding the vulcanizing agent and the vulcanization accelerator to the kneaded product obtained in the base kneading process and kneading. Further, the base kneading process can also be divided into a plurality of processes if desired.

[0152] The kneading conditions are not particularly limited. For example, in the base kneading process, a method of kneading at a discharge temperature of 150 to 170°C for 3 to 10 minutes, and in the final kneading process, kneading at 70 to 110°C for 1 to 5 minutes can be mentioned.

[0153] The tire according to this embodiment can be manufactured by a conventional method using the topping rubber composed of the above-described steel cord and the rubber composition. That is, a steel cord is coated with an unvulcanized rubber composition corresponding to the topping rubber to obtain a rubber-cord composite. This is bonded together with the tread portion and other tire members on a tire molding machine and molded by a conventional method to form an unvulcanized tire, and the tire can be manufactured by heating and pressurizing this unvulcanized tire in a vulcanizer. The vulcanization conditions are not particularly limited, and for example, a method of vulcanizing at 150 to 200°C for 10 to 30 minutes can be mentioned.

[0154] <Use> 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, or a racing tire. Note that a passenger car tire is a tire assumed to be mounted on an automobile that runs on four wheels and refers to a tire having a maximum load capacity of 1000 kg or less. Further, the tire according to this embodiment can be used for all-season tires, summer tires, winter tires such as studless tires, etc.

Examples

[0155] Hereinafter, examples (Examples) considered to be preferable in carrying out the invention will be shown, but the scope of the present invention is not limited to the examples. Using the various chemicals shown below, a tire having a steel cord coated with the topping rubber obtained according to the formulation in Table 1 was examined, and the results calculated based on the following evaluation methods are shown in Table 1.

[0156] Hereinafter, the various chemicals used in the examples and comparative examples are collectively shown. NR: TSR20 Carbon black: SHOW BLACK N330 (N2SA: 75 m 2 / g) manufactured by Cabot Japan Co., Ltd. Silica: ULTRASIL VN3 (N2SA: 175 m 2 / g) manufactured by Evonik Degussa GmbH Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide) manufactured by Evonik Degussa Oil: Diana Process NH-60 (aromatic process oil) manufactured by Idemitsu Kosan Co., Ltd. Oxazine compound: Pd-type benzoxazine compound represented by the following formula (3) manufactured by Shikoku Kasei Kogyo Co., Ltd.

[0157] [Chemical formula] Antioxidant: Nocrack 224 (2,2,4-trimethyl-1,2-dihydroquinoline polymer) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Cobalt compound: Cost-F (cobalt stearate) manufactured by DIC Corporation Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Muclon OT-20 (insoluble sulfur, oil content: 20% by mass) manufactured by Shikoku Kasei Kogyo Co., Ltd. Vulcanization accelerator: Acceler DZ-G (N,N-dicyclohexyl-2-benzothiazolylsulfenamide) manufactured by Kawaguchi Chemical Industry Co., Ltd.

[0158] (Examples and Comparative Examples) According to the formulation shown in Table 1, using a 1.7 L sealed Banbury mixer, chemicals other than sulfur and vulcanization accelerators were kneaded for 5 minutes until the discharge temperature reached 160 °C to obtain a kneaded product. Next, using a twin-screw open roll, sulfur and vulcanization accelerators were added to the obtained kneaded product and kneaded for 4 minutes until the temperature reached 105 °C to obtain an unvulcanized rubber composition. Using this unvulcanized rubber composition, a steel cord (filament diameter: 0.30 mm) having the configuration described in Table 1 was coated to obtain a rubber-cord composite. This was bonded together with the tread portion and other tire members to produce an unvulcanized tire, which was vulcanized at 170 °C to obtain each test tire (size: 195 / 65R15, distance G from the tread surface to the steel cord: 15 mm, cord inclination angle: 15°) described in Table 1. In the configuration of the steel cord in the table, "1×2 36e" means that there are 36 steel cords of 1×2 structure per 50 mm in the tire width direction in the tire meridian cross-section (36 ends), and "1×2 32e" means that there are 32 steel cords of 1×2 structure per 50 mm in the tire width direction in the tire meridian cross-section (32 ends). In the case of "1×2 32e", the total L of the cord outer circumference per 50 mm in the tire width direction in the tire meridian cross-section is less than 65 mm.

[0159] <Measurement of tanδ> For each vulcanized rubber test piece prepared by cutting out a length of 20 mm × width of 4 mm × thickness of 1 mm from the tread portion of each test tire and the topping rubber covering the steel cord, with the tire circumferential direction as the long side and the tire radial direction as the thickness direction, using a dynamic viscoelasticity measuring device (Epsilon series manufactured by GABO), tanδ was measured under the conditions of a temperature of 70 °C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±1%, and an elongation mode.

[0160] <Handling and stability performance> Each test tire is mounted on each of the four wheels of a FF passenger car with a displacement of 2000 cc, and actual vehicle running is performed on a test course of a dry asphalt road surface. The handling characteristics are evaluated based on the feelings during straight running, lane change, acceleration and deceleration at 100 km / h by a test driver. The evaluation is performed with an integer value from 1 to 5 points, and the total score of 20 test drivers is calculated based on the evaluation criteria that the higher the score, the better the handling characteristics. The total score of the control tire (Comparative Example 1) is converted into a reference value (100), and the evaluation results of each test tire are exponentiated and displayed in proportion to the total score.

[0161]

Table 1

[0162] <Embodiment> Examples of embodiments of the present invention are shown below.

[0163] 〔1〕A tire comprising a tread portion and a rubber - cord composite having a steel cord and a topping rubber covering the steel cord, wherein the total L of the outer circumference of the cord per 50 mm in the tire width direction in the tire meridian cross - section is 65 mm or more, the composite includes an adhesive material for adhering the steel cord and the topping rubber, the adhesive material contains an oxazine compound, the topping rubber is composed of a rubber composition containing a rubber component, carbon black, and sulfur, and when the mass of the rubber component in the composite as a relative amount is A (parts), the mass of carbon black is B (parts), the mass of sulfur is C (parts), and the mass of the oxazine compound is D (parts), (B + C) / (A + D) is less than 1.0. 〔2〕The tire according to [1] above, wherein (B + C) / (A + D) is less than 0.75. 〔3〕The tire according to [1] or [2] above, wherein B is 70 or less. 〔4〕The tire according to any one of [1] to [3] above, wherein C is 10 or less. 〔5〕The tire according to any one of [1] to [4] above, wherein D is 15 or less. 〔6〕The tire according to any one of 〔1〕to 〔5〕above, wherein the total content of the filler with respect to 100 parts by mass of the rubber component in the rubber composition is 70 parts by mass or less. 〔7〕The tire according to any one of 〔1〕to 〔6〕above, wherein the rubber composition contains the oxazine compound. 〔8〕The tire according to any one of 〔1〕to 〔7〕above, wherein the distance G from the tread surface to the steel cord is 15 mm or less. 〔9〕When the tanδ at 70 °C of the tread rubber is 70 °C tanδ1 and the tanδ at 70 °C of the topping rubber is 70 °C tanδ2, the tire according to any one of 〔1〕to 〔8〕above, wherein 70 °C tanδ1 / 70 °C tanδ2 is 1.5 or less.

Explanation of symbols

[0164] 11 ··· Tire 12 ··· Tread part 13 ··· Sidewall part 14 ··· Bead part 15 ··· Inner liner 16 ··· Carcass 17 ··· Belt layer 18 ··· Bead wire 21, 30, 50 ··· Steel cord 22 ··· Topping rubber 31, 32, 51 ··· Filament 311 ··· Core 321 ··· Outer sheath CL ··· Center line

Claims

1. A tire comprising a tread portion and a rubber - cord composite having a steel cord and a topping rubber covering the steel cord, wherein the total L of the outer circumference of the cord per 50 mm in the tire width direction in the tire meridian cross - section is 65 mm or more, the composite includes an adhesive material for adhering the steel cord and the topping rubber, the adhesive material contains an oxazine compound, the topping rubber is composed of a rubber composition containing a rubber component, carbon black, and sulfur, when the mass of the rubber component in the composite as a relative amount is A (parts), the mass of carbon black is B (parts), the mass of sulfur is C (parts), and the mass of the oxazine compound is D (parts), a tire in which (B + C) / (A + D) is less than 1.

0.

2. The tire according to claim 1, wherein (B + C) / (A + D) is less than 0.

75.

3. The tire according to claim 1 or 2, wherein B is 70 or less.

4. The tire according to claim 1 or 2, wherein C is 10 or less.

5. The tire according to claim 1 or 2, wherein D is 15 or less.

6. The tire according to claim 1 or 2, wherein the total content of the filler per 100 parts by mass of the rubber component in the rubber composition is 70 parts by mass or less.

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

8. The tire according to claim 1 or 2, wherein the distance G from the tread surface to the steel cord is 15 mm or less.

9. When the tanδ of the tread rubber at 70 °C is 70 °C tanδ1 and the tanδ of the topping rubber at 70 °C is 70 °C tanδ2, the tire according to claim 1 or 2, wherein 70 °C tanδ1 / 70 °C tanδ2 is 1.5 or less.

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