tire

Abstract

To enhance overall performance of low fuel consumption and durability characteristics.SOLUTION: There is provided a tire which comprises a belt layer constituted with a belt cord coated with a rubber composition, where the belt cord is composed of four filaments; the rubber composition has a cobalt amount of less than 0.15 parts by mass with respect to 100 parts by mass of the rubber component; and a diameter D (mm) of the belt cord, a complex elastic modulus E*(MPa) of the rubber composition measured under conditions of a temperature of 70°C, an initial elongation of 5%, a dynamic elongation of ±1%, a frequency of 10 Hz, and a deformation mode of elongation, and the cobalt amount C (parts by mass) of the rubber component in the rubber composition with respect to 100 parts by mass of the rubber constituent satisfy the following expression: D / E*<0.1×C+0.170.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] Patent Document 1 describes a pneumatic tire including a carcass, a belt, and a band.

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 improve the overall performance of low fuel consumption and durability.

Means for Solving the Problems

[0005] The present invention is a tire including a belt layer formed by coating a belt cord with a rubber composition, wherein the belt cord is composed of four filaments, the rubber composition has a cobalt amount of less than 0.15 parts by mass with respect to 100 parts by mass of the rubber component, the diameter D (mm) of the belt cord, the complex elastic modulus E * (MPa) of the rubber composition measured under the conditions of temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: extension, and the cobalt amount C (parts by mass) with respect to 100 parts by mass of the rubber component in the rubber composition satisfy the following formula. D / E * <0.1 × C + 0.170

Effects of the Invention

[0006] According to the present invention, it is possible to improve the overall performance of low fuel consumption and durability.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0008] [1] Features of the Tire According to the Present Invention First, the features of the tire according to the present invention will be described.

[0009] 1. Overview The tire according to the present invention is a tire provided with a belt layer formed by covering a belt cord (hereinafter, also simply referred to as "cord") with a rubber composition. The belt cord is composed of four filaments, and the rubber composition has a cobalt amount of less than 0.15 parts by mass with respect to 100 parts by mass of the rubber component. Further, the diameter D (mm) of the belt cord, the complex elastic modulus E * (MPa) of the rubber composition measured under the conditions of temperature: 70 °C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: extension, and the cobalt amount C (parts by mass) with respect to 100 parts by mass of the rubber component in the rubber composition satisfy the following formula. D / E * <0.1 × C + 0.170

[0010] By having these features, as described later, it is possible to improve the overall performance of low fuel consumption and durability.

[0011] Note that the above complex elastic modulus E * can be measured using a viscoelasticity measuring device such as "Implexor (registered trademark)" manufactured by GABO, for example.

[0012] 2. Mechanism of Effect Manifestation in the Tire According to the Present Invention Regarding the above-mentioned mechanism of effect manifestation in the tire according to the present invention, it can be considered as follows.

[0013] Conventionally, in the rubber composition of the belt ply constituting the belt layer, cobalt has been contained as an impurity in order to improve the adhesion to the belt cord. In recent years, however, cobalt-free has been strongly demanded from the perspective of SDGs.

[0014] However, when the cobalt content in the rubber composition is decreased, the adhesion between the cord and the rubber decreases, and BEL (BELT EDGE LOOSENESS) or loosening where the cord and the rubber peel off may occur at the edge, which may deteriorate the durability of the tire.

[0015] Therefore, as a countermeasure against the deterioration of durability, it is conceivable to increase the gauge (thickness) of the belt layer (belt ply). However, increasing the gauge may lead to a decrease in low fuel consumption performance.

[0016] In the present invention, the belt cord is composed of four filaments. By configuring the belt cord from four filaments, the cord diameter can be reduced. Therefore, even without increasing the gauge, a sufficient rubber thickness (gauge on the cord) can be ensured, and the occurrence of BEL and loosening can be suppressed.

[0017] And the belt cord with a small cord diameter can reduce the contact area with the rubber. Therefore, even if the cobalt content in the rubber composition is reduced to less than 0.15 parts by mass with respect to 100 parts by mass of the rubber component, sufficient adhesion between the cord and the rubber can be ensured. Further, the reduction of the cobalt content can reduce the loss tangent (tanδ) and improve the low fuel consumption performance.

[0018] Here, the filaments constituting the belt cord preferably have a circular cross-sectional shape, but may also have an elliptical shape. They may be corrugated or plated. Further, they may be un-twisted, single-twisted (1×4), or layer-twisted (2+2), but a 1×4 structure is preferred. In the embodiments described later, filaments with a circular cross-sectional shape are used in a single-twisted manner (1×4 structure) without being corrugated. As the belt cord, a metal cord is preferred, an iron cord is more preferred, and a steel cord is particularly preferred.

[0019] And in the above, the "cord diameter" of the belt cord refers to the diameter when the circumscribed circle of the cross-section perpendicular to the extending direction of the cord is a perfect circle, and in the case of an ellipse or the like, it refers to the equivalent circle diameter (the diameter of the perfect circle assumed when the cross-sectional area is the same).

[0020] Furthermore, in the present invention, the diameter D (mm) of the belt cord, the rubber composition, the complex elastic modulus E * (MPa), and the cobalt amount C (parts by mass) per 100 parts by mass of the rubber component in the rubber composition satisfy the following formula. D / E * <0.1×C + 0.170

[0021] The above formula indicates that in the present invention, the complex elastic modulus E * of the rubber composition is sufficiently large with respect to the cord diameter. Thus, by increasing the complex elastic modulus E * of the rubber composition, the movement of the cord end is sufficiently suppressed, so that the occurrence of BEL and loosening can be suppressed.

[0022] Note that the belt layer is not limited to one layer and may be two or more layers. In that case, for the above D / E * <0.1×C + 0.170, it is sufficient if at least one belt layer satisfies it, and it is more preferable if all belt layers satisfy it.

[0023] In the present invention, while appropriately controlling the configuration, diameter of the belt cord, and the amount of cobalt in the rubber composition, by satisfying D / E * <0.1×C + 0.170, it is considered that each of the above-described effects cooperate synergistically, so that it is possible to improve the overall performance of low fuel consumption and durability.

[0024] The amount of cobalt in the rubber composition is more preferably less than 0.10 parts by mass, even more preferably less than 0.05 parts by mass, even more preferably less than 0.05 parts by mass, even more preferably less than 0.01 parts by mass, and even more preferably less than 0.005 parts by mass, based on 100 parts by mass of the rubber component. The lower limit is not particularly limited and may be 0 parts by mass (non-containing). In this case, cobalt-free as described above is achieved.

[0025] [2] More preferred embodiments of the tire according to the present invention The tire according to the present invention can obtain a greater effect by adopting the following embodiments.

[0026] 1. Cord ends and surface area In the present invention, the product (E×S) of the number of cord ends E (number of cords per 50 mm width in the tire width direction) and the surface area S (mm 2 / mm) per unit length (1 mm) in the belt layer (belt ply) is preferably greater than 60 (E×S > 60). By making (E×S) greater than 60, in the belt layer (belt ply), the portion constrained by the rubber becomes larger, so that the adhesive force between the rubber and the cord can be more sufficiently exerted, and the movement of the cord can be sufficiently suppressed. Therefore, it is considered that the occurrence of BEL and dispersion can be further suppressed, and the durability can be further improved.

[0027] 2. Cord ends and bending rigidity In the present invention, the product (E×B) of the ends of the cords in the belt layer (belt ply) and the flexural rigidity B (g·cm) is preferably greater than 1600 (E×B>1600). By making (E×B) greater than 1600, the movement of the cords can be sufficiently suppressed, so it is considered that the occurrence of BEL, looseness, etc. can be further suppressed, and further improvement in durability can be achieved.

[0028] Incidentally, (E×B) is more preferably greater than 2000, still more preferably greater than 2400, and even more preferably greater than 10000. The upper limit is not particularly limited, but for example, it is preferably less than 15000.

[0029] The flexural rigidity of the above-mentioned belt cord can be measured, for example, using a rigidity tester (for example, model 150-D) manufactured by TABER Co., Ltd. (USA) according to the following procedure. First, both ends of a belt cord with a length of 145 mm are attached to the clamps of the rigidity tester, and as shown in FIG. 2, bending angles of +15 degrees and -15 degrees are applied to the belt cord 10. Then, the average value of the bending moment at +15 degrees and the bending moment at -15 degrees is defined as the flexural rigidity value (g·cm).

[0030] 3. Carbon black contained in the rubber composition In the present invention, the rubber composition preferably contains carbon black having a BET specific surface area of 45 m 2 / g or more in an amount of 5 parts by mass or more and 70 parts by mass or less based on 100 parts by mass of the rubber component.

[0031] Thereby, the complex elastic modulus E * of the rubber composition can be made larger, so it is considered that the occurrence of BEL, looseness, etc. can be further suppressed, and further improvement in durability can be achieved.

[0032] Incidentally, the content of carbon black is more preferably 30 parts by mass or more and 60 parts by mass or less based on 100 parts by mass of the rubber component.

[0033] The above-mentioned BET specific surface area is the value of the nitrogen adsorption specific surface area (N2SA) measured by the BET method in accordance with ASTM D3037-93.

[0034] [3] Embodiments Hereinafter, the present invention will be specifically described based on embodiments.

[0035] 1. Tire according to this embodiment FIG. 1 is a schematic cross-sectional view for explaining the structure of a tire according to this embodiment, showing a tire meridian cross-section including the rotation axis in the normal state of the tire.

[0036] Here, the "normal state" means that the tire is mounted on a normal rim, filled with a normal internal pressure, and in an unloaded state.

[0037] Note that the "normal rim" is the rim defined for each tire in a standard system including the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it is the standard rim in the applicable size described in the "JATMA YEAR BOOK"; in the case of ETRTO (The European Tyre and Rim Technical Organisation), it is the "Measuring Rim" described in the "STANDARDS MANUAL"; in the case of TRA (The Tire and Rim Association, Inc.), it is 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 at the time of reference. In the case of a tire not defined by the standard, it refers to the rim that can be mounted on the tire and can hold the internal pressure, that is, among the rims that do not cause air leakage between the rim / tire, the one with the smallest rim diameter and then the narrowest rim width.

[0038] The "normal internal pressure" refers to the air pressure determined for each tire in the standard system including the standards on which the tire is based. For JATMA, it is the "maximum air pressure"; for ETRTO, it is the "INFLATION PRESSURE"; for TRA, it refers to the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Refer to JATMA, ETRTO, and TRA in this order. If there is an applicable size during the reference, follow the relevant standard. For a tire not specified in the standard, it refers to the normal internal pressure (however, 250 KPa or more) of another tire size (specified in the standard) with the above-mentioned normal rim described as the standard rim. In the case where multiple normal internal pressures of 250 KPa or more are described, it refers to the minimum value among them.

[0039] As shown in FIG. 1, the tire 1 includes a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a belt layer 7 disposed on the outer side of the carcass 6 in the tire radial direction and inside the tread portion 2. Note that C is the center line.

[0040] The carcass 6 is composed of at least one (one in FIG. 1) carcass ply 6A, and is locked by turning from the inside to the outside around the bead core 5 of the bead portion 4 through the tread portion 2 and the sidewall portion 3. In FIG. 1, 6a is the inner main body portion of the carcass ply 6A, and 6b is the outer turned-back portion. Between the inner main body portion 6a and the outer turned-back portion 6b, for example, a bead apex rubber 8 extending radially outward from the bead core 5 in the tire radial direction is disposed.

[0041] The belt layer 7 is configured by disposing at least one belt ply in which a coating rubber is coated on an array body in which steel cords having a 1×4 configuration composed of four filaments are aligned with predetermined ends. In FIG. 1, the belt layer 7 is composed of two belt plies, i.e., a first belt ply 7A located on the inner side in the tire radial direction and a second belt ply 7B located outside the first belt ply 7A. Note that three or more belt plies may be used.

[0042] By adopting such a belt layer 7, as described above, it is possible to improve the overall performance of low fuel consumption and durability.

[0043] 2. Rubber composition constituting the belt layer In the present embodiment, the rubber composition constituting the belt layer can be obtained from the rubber components and other compounding materials described below.

[0044] (1) Compounding materials (a) Rubber components In the present embodiment, the rubber component is not particularly limited, and diene rubbers such as isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), and nitrile rubber (NBR), and butyl rubbers such as butyl rubber, which are generally used in the manufacture of tires, can be used. Among these, isoprene rubber is preferable, and it is preferable to use NR in that the cis structure of polyisoprene is nearly 100% and the tensile strength is superior to other rubber components. If necessary, BR and SBR may be used in combination.

[0045] (i) Isoprene rubber The content (total content) of isoprene rubber in 100 parts by mass of the rubber component is preferably 80 parts by mass or more, and more preferably 90 parts by mass or more.

[0046] Examples of the isoprene rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, etc., and NR is preferable in terms of excellent strength.

[0047] As the NR, for example, those commonly used in the tire industry such as SIR20, RSS#3, TSR20, etc. can be used. The IR is not particularly limited, and for example, those commonly used in the tire industry such as IR2200, etc. can be used. As the modified NR, deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., as the modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc., and as the modified IR, epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. can be mentioned. These may be used alone or in combination of two or more.

[0048] (B) Other rubber components Also, as other rubber components, rubber (polymers) generally used in the production of tires such as butadiene rubber (BR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), etc. may be included as necessary. The content (total content) of these rubber components in 100 parts by mass of the rubber components is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less.

[0049] (b) Compounding materials other than rubber components (A) Filler In the present embodiment, the rubber composition preferably contains a filler. Specific fillers include, for example, carbon black, silica, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc. Among these, carbon black can be preferably used as a reinforcing agent.

[0050] (i) Carbon black The carbon black is not particularly limited, and examples thereof include furnace black (furnace carbon black) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black (acetylene carbon black); thermal black (thermal carbon black) such as FT and MT; channel black (channel carbon black) such as EPC, MPC, and CC. These may be used alone or in combination of two or more.

[0051] As described above, the BET specific surface area of the carbon black is preferably 45 m 2 / g or more. Further, the content of the carbon black is preferably 5 parts by mass or more and 70 parts by mass or less, more preferably 30 parts by mass or more and 60 parts by mass or less, based on 100 parts by mass of the rubber component.

[0052] Specific carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. As commercially available products, for example, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nippon Carbon Co., Ltd., Columbian Carbon Co., etc. can be used. These may be used alone or in combination of two or more.

[0053] (ii) Other fillers The rubber composition may further contain fillers generally used in the tire industry, such as silica, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc., in addition to the above-described carbon black, if necessary. The content of these is, for example, more than 0.1 part by mass and less than 200 parts by mass based on 100 parts by mass of the rubber component. When using silica, it is preferably used in combination with a silane coupling agent.

[0054] (b) Thermosetting resin component The rubber composition preferably contains a phenolic resin and / or a melamine resin as a curable resin component. Thereby, without significantly deteriorating the heat generation property and the elongation at break, the adhesiveness to the steel cord can be improved, and it is possible to easily generate a large reaction force with the rubber and the steel cord.

[0055] Specific examples of the phenolic resin include PR12686 (cashew oil-modified phenolic resin) manufactured by Sumitomo Bakelite Co., Ltd., and specific examples of the melamine resin include Sumicanol 507AP (modified etherified methylol melamine resin) manufactured by Taoka Chemical Co., Ltd.

[0056] The content of the curable resin component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, from the viewpoint of sufficiently improving the complex elastic modulus and obtaining a large reaction force during deformation, with respect to 100 parts by mass of the rubber component. On the other hand, from the viewpoint of maintaining the breaking strength, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less.

[0057] When using the melamine resin, it is preferably contained together with a methylene donor as a curing agent. Examples of the methylene donor include hexamethylenetetramine (HMT), hexamethoxymethylol melamine (HMMM), and hexamethylol melamine pentamethyl ether (HMMPME). With respect to 100 parts by mass of the curable resin component, it is preferably contained in an amount of, for example, 5 parts by mass or more and about 15 parts by mass. If it is too little, there is a risk that a sufficient complex elastic modulus cannot be obtained. On the other hand, if it is too much, the viscosity of the rubber may increase and the processability may deteriorate.

[0058] As a specific methylene donor, for example, Sumicanol 507 manufactured by Taoka Chemical Co., Ltd. can be used.

[0059] (C) Plasticizer component The rubber composition may contain an oil (including extender oil), a liquid rubber, and a resin as components (softeners) for softening the rubber. The plasticizer component is a component that can be extracted from the vulcanized rubber with acetone. The total content of the plasticizer component is preferably more than 1 part by mass, more preferably 2 parts by mass or more, based on 100 parts by mass of the rubber component. On the other hand, it is preferably less than 20 parts by mass, more preferably less than 10 parts by mass. The content of the oil also includes the amount of oil contained in the rubber (oil-extended rubber).

[0060] (i) Oil Examples of the oil include process oil, vegetable oil, animal oil, or a mixture thereof. As the process oil, for example, paraffinic process oil, aromatic process oil, naphthenic process oil, etc. can be used. Specific examples of the process 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. These may be used alone or in combination of two or more.

[0061] As specific process oils, for example, products of Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Orisoy Co., H&R Co., Toyokuni Seiyu Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kogyo Co., Ltd., etc. can be used.

[0062] Examples of the vegetable oil include 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 rosin, etc. These may be used alone or in combination of two or more.

[0063] As specific vegetable oils, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Oil Chemical Co., Ltd., ENEOS Co., Ltd., Oleoso, H&R, Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0064] (ii) Liquid rubber The liquid rubber mentioned as a plasticizer is a polymer in a liquid state at normal temperature (25°C) and is a rubber component that can be extracted from the vulcanized tire by acetone extraction. Examples of liquid rubber include farnesene-based polymers, liquid diene-based polymers, and hydrogenated products thereof.

[0065] A farnesene-based polymer is a polymer obtained by polymerizing farnesene and has a structural unit based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene).

[0066] The farnesene-based polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

[0067] Examples of liquid diene-based polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), etc.

[0068] The liquid diene-based polymer has a weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) of, for example, more than 1.0×10 3 super, 2.0×10 5 less than. In this specification, the Mw of the liquid diene-based polymer is a value in terms of polystyrene measured by gel permeation chromatography (GPC).

[0069] As specific liquid rubbers, for example, products of Kuraray Co., Ltd., Kray Valley Co., etc. can be used.

[0070] (iii) Resin component The resin component also functions as an adhesiveness-imparting component and may be solid or liquid at normal temperature. Specific resin components include, for example, resins such as rosin-based resins, styrene-based resins, coumarone-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, and two or more of them may be used in combination.

[0071] Rosin-based resins are resins mainly composed of rosin acid obtained by processing pine resin. These rosin-based resins (rosins) can be classified according to the presence or absence of modification, and can be classified into unmodified rosin (non-modified rosin) and rosin modified products (rosin derivatives). Examples of unmodified rosin include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. Rosin modified products are modified products of unmodified rosin, and examples include rosin esters, unsaturated carboxylic acid-modified rosins, unsaturated carboxylic acid-modified rosin esters, amide compounds of rosin, and amine salts of rosin.

[0072] Styrene-based resins are polymers using styrene-based monomers as constituent monomers, and examples include polymers polymerized with styrene-based monomers as the main component (50% by mass or more). Specifically, styrene-based monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) are each homopolymers polymerized alone, copolymers copolymerized with two or more styrene-based monomers, and copolymers of styrene-based monomers and other monomers copolymerizable therewith.

[0073] Examples of the other monomer include acrylonitriles such as acrylonitrile and methacrylonitrile, acrylates, unsaturated carboxylic acids such as methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene, butadiene and isoprene, olefins such as 1-butene and 1-pentene; α,β-unsaturated carboxylic acids such as maleic anhydride or acid anhydrides thereof.

[0074] Among coumarone resins, coumarone-indene resins are preferred. A coumarone-indene resin is a resin containing coumarone and indene as monomer components constituting the resin skeleton (main chain). Examples of monomer components other than coumarone and indene contained in the skeleton include styrene, α-methylstyrene, methyl indene, vinyltoluene and the like.

[0075] The content of the coumarone-indene resin is, for example, more than 1.0 part by mass and less than 50.0 parts by mass with respect to 100 parts by mass of the rubber component.

[0076] The hydroxyl value (OH value) of the coumarone-indene resin is, for example, more than 15 mgKOH / g and less than 150 mgKOH / g. The OH value represents the amount of potassium hydroxide in milligrams required to neutralize acetic acid bonded to hydroxyl groups when 1 g of the resin is acetylated, and is a value measured by the potentiometric titration method (JIS K 0070:1992).

[0077] The softening point of the coumarone-indene resin is, for example, more than 30°C and less than 160°C. The softening point is the temperature at which the ball drops when measured with a ring and ball softening point measuring device according to the softening point defined in JIS K 6220-1:2001.

[0078] Examples of terpene resins include polyterpenes, terpene phenols, aromatic-modified terpene resins and the like. Polyterpenes are resins obtained by polymerizing terpene compounds and hydrogenated products thereof. Terpene compounds are hydrocarbons represented by the composition of (C5H8) n and oxygen-containing derivatives thereof, and monoterpenes (C10 H 16 ) sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ) and other compounds having a terpene as a basic skeleton, for example, α-pinene, β-pinene, dipentene, limonene, myrcene, allo-ocimene, ocimene, α-farnesene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, etc.

[0079] Examples of polyterpenes include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, β-pinene / limonene resin, etc. using the above-mentioned terpene compounds as raw materials, and hydrogenated terpene resins obtained by hydrogenating the terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the above-mentioned terpene compounds and phenolic compounds, and resins obtained by hydrogenating the resins. Specifically, resins obtained by condensing the above-mentioned terpene compounds, phenolic compounds and formalin are included. Examples of phenolic compounds include phenol, bisphenol A, cresol, xylenol, etc. Examples of aromatic-modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the resins. The aromatic compound is not particularly limited as long as it has an aromatic ring, and examples include phenolic compounds such as phenol, alkylphenol, alkoxyphenol, and unsaturated hydrocarbon group-containing phenol; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and unsaturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; coumarone, indene, etc.

[0080] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of the C5 fraction include petroleum fractions equivalent to 4 to 5 carbon atoms such as cyclopentadiene, pentene, pentadiene, and isoprene. As the C5-based petroleum resin, dicyclopentadiene resin (DCPD resin) is preferably used.

[0081] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, which may be hydrogenated or modified. Examples of the C9 fraction include petroleum fractions equivalent to 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, indene, and methylindene. As specific examples, for instance, coumarone-indene resin, coumarone resin, indene resin, and aromatic vinyl-based resins are preferably used. As the aromatic vinyl-based resin, due to economic reasons, ease of processing, and excellent heat-generating properties, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred. As the aromatic vinyl-based resin, for example, those commercially available from companies such as Kraton Corporation and Eastman Chemical Company can be used.

[0082] "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, which may be hydrogenated or modified. Examples of the C5 fraction and the C9 fraction include the aforementioned petroleum fractions. As the C5C9 resin, for example, those commercially available from Tosoh Corporation, LUHUA, etc. can be used.

[0083] The acrylic resin is not particularly limited, and for example, a solventless acrylic resin can be used.

[0084] The solventless acrylic resin is a (meth)acrylic resin (polymer) synthesized by a high-temperature continuous polymerization method (high-temperature continuous bulk polymerization method) (the method described in U.S. Patent No. 4,414,370, JP-A-59-6207, JP-B-5-58005, JP-A-1-313522, U.S. Patent No. 5,010,166, Annual Report of Toagosei Research TREND2000 No. 3 p42-45, etc.) without using a polymerization initiator, a chain transfer agent, an organic solvent, etc. as auxiliary raw materials as much as possible. In the present invention, (meth)acrylic means methacrylic and acrylic.

[0085] Examples of the monomer components constituting the acrylic resin include (meth)acrylic acid derivatives such as (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylamide derivatives.

[0086] Also, as the monomer components constituting the acrylic resin, aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinylnaphthalene, etc. may be used together with (meth)acrylic acid or (meth)acrylic acid derivatives.

[0087] The above acrylic resin may be a resin composed only of a (meth)acrylic component or a resin having components other than the (meth)acrylic component as constituent elements. Further, the above acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, etc.

[0088] As specific resin components, for example, products of Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical, Nippon Paint Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., Tago Chemical Industry Co., Ltd., etc. can be used.

[0089] (Ni)cobalt In the present invention, as described above, the rubber composition contains cobalt. Thereby, the adhesiveness between the cord and the rubber can be improved.

[0090] Examples of the cobalt-containing compound include cobalt organic acid. Specific cobalt organic acids include, for example, cobalt stearate, cobalt naphthenate, cobalt neodecanoate, cobalt boron 3 neodecanoate, cobalt abietic acid, and the like. As commercially available products, products of Dainippon Ink and Chemicals, Inc. and the like can be used. These may be used alone or in combination of two or more. Among them, cobalt stearate is preferable.

[0091] In addition, as a chemical other than the above-mentioned cobalt organic acid, a product in which the cobalt element is appropriately replaced with an element having an ionization tendency between zinc and copper may be used. Examples of such metal elements include iron, nickel, tin, antimony, bismuth, and the like.

[0092] In the present invention, these cobalt-containing compounds are appropriately selected and blended so that the cobalt content is less than 0.15 parts by mass with respect to 100 parts by mass of the rubber component. As described above, the cobalt content is more preferably less than 0.10 parts by mass, further preferably less than 0.05 parts by mass, further preferably less than 0.05 parts by mass, further preferably less than 0.01 parts by mass, and further preferably less than 0.005 parts by mass.

[0093] In addition, if necessary, an aliphatic (thiosulfuric acid) sodium salt derivative such as sodium hexamethylene-1,6-bis(thiosulfate) dihydrate may be contained together with the cobalt organic acid.

[0094] Since the aliphatic (thiosulfuric acid) sodium salt derivative contains a sulfur atom, it also functions as a crosslinking agent, can balance the initial adhesiveness / heat-resistant adhesiveness / water-resistant adhesiveness with the steel monofilament cord of the rubber composition, and can improve the adhesiveness with the steel monofilament cord.

[0095] Specific aliphatic sodium (thiosulfate) salt derivatives include, for example, Duralink HTS (hexamethylene-1,6-bis(sodium thiosulfate) dihydrate) manufactured by Flexsys, etc.

[0096] (Ph) Antioxidant The rubber composition preferably contains an antioxidant. The content of the antioxidant is, for example, more than 0.5 parts by mass and less than 10 parts by mass, and more preferably 1 part by mass or more, based on 100 parts by mass of the rubber component.

[0097] Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine, 4,4′-bis(α,α′-dimethylbenzyl) diphenylamine; p-phenylenediamine-based antioxidants such as N-isopropyl-N′-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, N,N′-di-2-naphthyl-p-phenylenediamine; 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, styrenated phenol; bis, tris, polyphenol-based antioxidants such as tetrakis-[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, etc. These may be used alone or in combination of two or more.

[0098] Note that as the antioxidant, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys, etc. can be used.

[0099] (He) Zinc Oxide The rubber composition may contain zinc oxide. The content of zinc oxide is preferably 15 parts by mass or less based on 100 parts by mass of the rubber component.

[0100] As the zinc oxide, those conventionally known can be used. For example, products of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shoindo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0101] (Tokyo) Crosslinking agent and vulcanization accelerator The rubber composition preferably contains a crosslinking agent such as sulfur. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc., which are generally used in the rubber industry. These may be used alone or in combination of two or more.

[0102] The content of sulfur is preferably 8 parts by mass or less with respect to 100 parts by mass of the rubber component.

[0103] As the sulfur, for example, products of Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Corporation, Flexsys, Nippon Kankyu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0104] Examples of crosslinking agents other than sulfur include vulcanizing agents containing sulfur atoms such as Tackiol V200 manufactured by Takeoka Chemical Industry Co., Ltd., KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by Rancess, and organic peroxides such as dicumyl peroxide.

[0105] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator is, for example, more than 0.3 parts by mass and less than 10.0 parts by mass with respect to 100 parts by mass of the rubber component.

[0106] As vulcanization accelerators, there can be mentioned thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyldisulfide, N-cyclohexyl-2-benzothiazylsulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, N-t-butyl-2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diorthotolylguanidine, orthotolylbiguanidine. These may be used alone or in combination of two or more.

[0107] (Th) Others In addition to the above components, the rubber composition may further contain additives generally used in the tire industry, for example, fatty acid metal salts, carboxylic acid metal salts, organic peroxides, reversion (vulcanization reversion) inhibitors, etc., as required.

[0108] (c) Use of sustainable materials in each rubber composition In the tire according to the present invention, when producing other tire members of the above-described belt layer, respective predetermined rubber compositions are used. However, in consideration of the strong demand for environmental protection in recent years, it is preferable to use sustainable materials as the materials constituting these rubber compositions.

[0109] (C-1) Rubber material For example, as raw materials (monomers) of synthetic rubbers such as SBR and BR, those recycled from rubber products such as tires and non-rubber products such as polystyrene can be used instead of those derived from petroleum.

[0110] The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples thereof include butadiene derived from recycling and aromatic vinyl derived from recycling. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples thereof include styrene. Among them, it is preferable to use butadiene derived from recycling (recycled butadiene) and / or styrene derived from recycling (recycled styrene) as raw materials.

[0111] The method for producing recycled monomers is not particularly limited. For example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. 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.

[0112] Furthermore, the raw materials (monomers) of synthetic rubbers such as SBR and BR may be derived from biomass. The monomers derived from biomass (biomass monomers) are not particularly limited, and examples thereof include butadiene derived from biomass and aromatic vinyl derived from biomass. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples thereof include styrene. The method for producing biomass monomers is not particularly limited. For example, it includes those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical of 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. Examples of the biomass sources of these monomers include sugars, wood, plant residues after obtaining useful components, plant-derived ethanol, biomass naphtha, and the like.

[0113] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples thereof include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0114] 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.

[0115] pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the standard modern carbon (modern standard reference), and this value is used as an index indicating the biomass ratio of the compound (rubber). The significance of this value will be described below.

[0116] In one mole (6.02×10 23 pieces) of carbon atoms, there are about 6.02×10 11 pieces of 14 C, which is about one trillionth of the normal carbon atoms. 14 C is called a radioactive isotope, and its half-life is 5730 years and it decreases regularly. It takes 226,000 years for all of these 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., the 14 C element contained in them at the time of fixation has all decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain 14 C element at all. Therefore, chemical substances produced using these fossil fuels as raw materials also do not contain 14 C element at all.

[0117] On one hand, 14 C undergoes nuclear reactions in the atmosphere by cosmic rays, is constantly generated, and is balanced with the decrease due to radioactive decay. In the Earth's atmospheric environment, 14 the amount of C is a certain amount. Therefore, for substances derived from biomass resources that are cycling in the current environment, 14 the C concentration is about 1×10 -12 mol% with respect to the entire C atoms as described above. Therefore, by utilizing the difference between these values, the ratio (biomass ratio) of the compound (biomass resource-derived compound) derived from natural resources in a certain compound (rubber) can be calculated.

[0118] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 the C concentration ( 13 C / 12 C), 14 the C concentration ( 14 C / 12 C) is measured. In the measurement, 14 as the modern standard reference for the concentration of 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 1 g of carbon) is separated for each carbon isotope, 13 the value corrected to a certain value for 14 C and subjected to 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.

[0119] Therefore, if the rubber is made of a 100% biomass (natural) - derived material, although there are regional differences, it will show a value of approximately 110 pMC (currently, in the normal state, it often does not reach 100). On the other hand, for chemical substances derived from fossil fuels such as petroleum, when measuring this 14 C concentration, it will show almost 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% mentioned above.

[0120] 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.

[0121] Also, as the rubber material, it is also preferable to use vulcanized rubber particles.

[0122] Vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder etc. defined in JIS K 6316:2017 can be used. From the perspectives of environmental consideration and cost, recycled rubber powder produced from crushed waste tires etc. is preferable. These can be used alone or in combination of two or more.

[0123] The vulcanized rubber particles are not particularly limited, and can be either non - modified vulcanized rubber particles or modified vulcanized rubber particles.

[0124] As commercially available products of vulcanized rubber particles, for example, products of Lehigh, Murakami Rubber Industry Co., Ltd. etc. can be used.

[0125] (C - 2) Silica Generally, silica is contained as a reinforcing filler in the rubber composition. Instead of raw materials derived from minerals such as quartz, the use of sustainable silica is also preferable.

[0126] 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 made from 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 of its large number of silanol groups. These silicas may be used alone or in combination of two or more.

[0127] Silica made from a biomass material can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husk using a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to precipitate silicon dioxide, followed by filtration, washing with water, drying, and pulverization.

[0128] 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 media 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.

[0129] When silica crystallizes, it is insoluble in water and the silicic acid that is its component cannot be utilized. By controlling the combustion temperature and combustion time, crystallization of silica in rice husk ash can be suppressed (see, for example, Japanese Patent Laid-Open No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.).

[0130] Amorphous silica extracted from rice husk can be a commercially available product from Wilmar Co., Ltd. or the like.

[0131] (C-3) Carbon black And it is also common for the rubber composition to contain carbon black as a reinforcing filler, and the use of sustainable carbon black as such carbon black is also preferable.

[0132] The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762 and the like. 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 thermally decomposing 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 Company, etc. can be used. These may be used alone or in combination of two or more.

[0133] (C-4) Oil Examples of oils commonly used as softeners include process oils, vegetable oils, animal oils, etc. Examples of process oils include paraffinic process oils (mineral oils), naphthenic process oils, aromatic process oils, etc. Specific examples of process oils 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, process oils with a low content of polycyclic aromatic compounds (PCA) can be used for environmental protection. Examples of the low-PCA-content process oils include MES, TDAE, heavy naphthenic 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.

[0134] Specific examples of vegetable oils include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar 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 rosin, 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, oxidation-polymerized oils obtained by oxidizing the above oils, and vegetable oils such as waste cooking oils recovered from those used as edible oils, etc. Note that vegetable oils may be liquid or solid at room temperature (25°C).

[0135] The vegetable oil preferably contains acylglycerol, and more preferably contains triacylglycerol. Here, 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 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Further, the acylglycerol may be a monomer, a dimer, or a multimer of trimer or higher. Note that acylglycerols of dimer or higher can be obtained by thermal polymerization, oxidative polymerization, or the like. Also, the acylglycerol may be liquid or solid at normal temperature (25°C).

[0136] As a method for confirming whether or not the acylglycerol is contained in the rubber composition, it is not particularly limited, but 1 it can be confirmed by 1H-NMR measurement. For example, 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 around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm are observed, and 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.

[0137] 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.

[0138] 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, genome editing, etc.

[0139] 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.

[0140] (C-5) Plasticizers other than oil In the rubber composition, as a plasticizer for imparting plasticity to the rubber component, in addition to the above-mentioned oil, a plasticizer that is liquid (liquid state) at room temperature (25°C) and a plasticizer that is solid at room temperature (25°C) are also contained. Examples of such plasticizers include resin components, liquid polymers, ester-based plasticizers, etc. These plasticizers may be derived from petroleum, may be derived from biomass, or may be derived from naphtha recycled from rubber products or non-rubber products (sustainable plasticizers). Further, a low-molecular-weight hydrocarbon component obtained by pyrolyzing and extracting used tires or products containing various components may be used as a plasticizer. These plasticizers may be used alone or in combination of two or more.

[0141] (C-6) Wax Rubber compositions generally contain wax. The wax is not particularly limited, and any wax commonly used in the tire industry can be preferably used. For example, petroleum waxes, mineral waxes, synthetic waxes, plant-derived waxes, etc. can be mentioned. Among them, petroleum waxes and plant-derived waxes are preferred, and petroleum waxes are more preferred. Examples of plant-derived waxes include rice wax, carnauba wax, candelilla wax, etc. Examples of petroleum waxes include paraffin wax, microcrystalline wax, these selected special waxes, etc., and paraffin wax is preferred. As the wax, those commercially available from, for example, Ouchi Shinsei 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.

[0142] (C-7) Antioxidant Rubber compositions generally contain antioxidants, although the antioxidants are not particularly limited. Examples of antioxidants include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based antioxidants 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 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; 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 N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys, etc. can be used.

[0143] In the rubber composition, various materials containing carbon atoms (such as rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the formulation of the present invention 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.

[0144] (2) Preparation of Rubber Composition The rubber composition is produced by a production method including a base kneading step of kneading a rubber component and a filler such as carbon black by a general method, and a finishing kneading step of kneading the kneaded product obtained in the base kneading step and a crosslinking agent.

[0145] Kneading can be performed using a known (sealed type) kneader such as a Banbury mixer, a kneader, an open roll, etc.

[0146] The kneading temperature in the base kneading step is, for example, over 50°C and less than 200°C, and the kneading time is, for example, over 30 seconds and less than 30 minutes. In the base kneading step, in addition to the above components, compounding agents conventionally used in the rubber industry, such as softening agents such as oil, zinc oxide, anti-aging agents, waxes, vulcanization accelerators, etc. may be appropriately added and kneaded as necessary.

[0147] In the finishing kneading step, the kneaded product obtained in the base kneading step and the crosslinking agent are kneaded. The kneading temperature in the finishing kneading step is, for example, over room temperature and less than 80°C, and the kneading time is, for example, over 1 minute and less than 15 minutes. In the finishing kneading step, in addition to the above components, vulcanization accelerators, zinc oxide, etc. may be appropriately added and kneaded as necessary.

[0148] At this time, by adjusting the compounding amounts of the above-described respective compounding materials, the complex elastic modulus E * can be appropriately adjusted. For example, by increasing the content of a filler such as carbon black, reducing the particle size of the filler, reducing the content of a softening agent component such as oil or resin, increasing the content of sulfur or accelerator, etc., the complex elastic modulus E * can be increased. Conversely, by reducing the content of a filler such as carbon black, increasing the content of a plasticizer component such as oil or resin, reducing the content of sulfur or accelerator, etc., the complex elastic modulus E * can be decreased.

[0149] 3. Manufacture of the belt ply The belt layer (belt ply) can be manufactured by topping both sides of cords (steel cords) arranged in parallel at a predetermined interval (ends) with the rubber composition obtained above.

[0150] Prior to topping the rubber composition, it is preferable to apply an adhesive composition to the surface of the cords to form a coating layer. By making this coating layer function as an adhesive layer, the rubber composition and the cords can be sufficiently adhered to each other.

[0151] As the adhesive composition, an adhesive composition containing a polybenzoxazine compound containing units represented by the following (Chemical Formula 1) to (Chemical Formula 4) is preferable because it exhibits excellent adhesiveness to both the rubber composition and the cords.

[0152]

Chemical Formula

[0153]

Chemical Formula

[0154]

Chemical Formula

[0155]

Chemical Formula

[0156] In the above (Chemical Formula 1) and (Chemical Formula 2), X1 is a hydrocarbon selected from aliphatic, alicyclic, and aromatic hydrocarbons and combinations thereof, and may have any one of the heteroatoms S, O, N, P and a structure in which these heteroatoms are continuously connected. And X2 has an (S)n structure in which n (1 to 8) S atoms are connected, and may have a hydrocarbon selected from aliphatic, alicyclic, and aromatic hydrocarbons and any one or a combination of S, O, N, P. Further, in (Chemical Formula 3) and (Chemical Formula 4), X1 is a hydrocarbon selected from aliphatic, alicyclic, and aromatic hydrocarbons and combinations thereof, and has an (S)n structure in which n (1 to 8) S atoms are connected.

[0157] The above-described adhesive composition can be produced, for example, by using a known method described in US2020 / 0290402 A (JP-T-2019-507805). After applying and drying the coating liquid of the obtained adhesive composition on the surface of the cord, a heat crosslinking is performed to form an adhesive layer on the surface of the cord.

[0158] 4. Tire Manufacturing The tire according to the present embodiment can be produced as an unvulcanized tire by molding the belt layer (belt ply) obtained above together with other tire members on a tire molding machine by a normal method.

[0159] Specifically, an inner liner as a member for ensuring the airtightness of the tire, a carcass as a member for withstanding the load, impact, and inflation air pressure received by the tire, and a belt layer as a member for strongly tightening the carcass and increasing the rigidity of the tread are wound around a molding drum. After fixing both ends of the carcass to both side edges and arranging a bead portion as a member for fixing the tire to a rim and molding it into a toroidal shape, a tread is provided at the central portion of the outer periphery and a sidewall is bonded to the radially outer side to form a side portion, thereby producing an unvulcanized tire.

[0160] In the present embodiment, the belt layer may be composed of a plurality of belt plies from the viewpoint of increasing the restraining force on the tread during running and making it easier to suppress the growth of the outer diameter as described above. At this time, it is preferable that the average distance D (mm) between the cords of the belt plies in the tread portion of the tire after vulcanization is 0.6 mm or less. Further, the angle formed by the cords in the tread portion with a straight line parallel to the tire circumferential direction is 10° or more and 35° or less, and it is preferable that the cords of the adjacent belt plies are arranged so as to cross each other.

[0161] Note that the angle of the cord is the angle of the cord with respect to the tire circumferential direction in a state where the tire is not filled with air, and it can be confirmed by peeling the tread portion from the outside in the radial direction of the tire.

[0162] Thereafter, the unvulcanized tire produced as described above is heated and pressurized in a vulcanizer to obtain a tire. The vulcanization process can be carried out by applying known vulcanization means. The vulcanization temperature is, for example, more than 120°C and less than 200°C, and the vulcanization time is, for example, more than 5 minutes and less than 15 minutes.

[0163] As described above, the tire obtained as above appropriately controls the belt cord diameter and the cobalt content in the rubber composition, and satisfies D / E * <0.1×C + 0.05, so that each effect cooperates and is synergistically exerted, and thus the comprehensive performance of low fuel consumption and durability can be improved.

[0164] And the tire according to the present invention can be suitably used as a passenger car tire, a large passenger car tire, a large SUV tire, a small truck tire, etc.

Examples

[0165] Hereinafter, examples (Examples) considered preferable when carrying out the invention are shown, but the scope of the present invention is not limited to the said examples.

[0166] Except for the belt layers of each specification shown in Table 1, they are substantially the same. Regarding the tire (tire size: 195 / 65R15) having the configuration shown in FIG. 1, the results calculated based on the evaluation method described later for low fuel consumption and durability are also shown at the bottom of Table 1.

[0167] 1. Manufacture of Rubber Composition First, the rubber composition constituting the belt layer is manufactured.

[0168] (1) Compound Materials (a) Rubber Component NR: RSS3

[0169] (b) Compound Materials Other than Rubber Component (i) Carbon Black - 1: SHOW BLACK N660 manufactured by Cabot Japan (BET Specific Surface Area: 35 m 2 / g, Average Particle Diameter: 40 nm) (ii) Carbon Black - 2: SHOW BLACK N326 manufactured by Cabot Japan (BET Specific Surface Area: 78 m 2 / g, Average Particle Diameter: 30 nm) (iii) Oil: Diana Process AH - 24 (Aroma Oil) manufactured by Idemitsu Kosan Co., Ltd. (iv) Cobalt Organic Acid: COST - F manufactured by DIC (Stearic Acid Cobalt, Cobalt Content: 9.5 mass%) (v) Antioxidant: Antage RD manufactured by Kawaguchi Chemical Industry Co., Ltd. (2,2,4 - Trimethyl - 1,2 - dihydroquinoline) (vi) Zinc Oxide: Zinc White No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. (vii) Sulfur: Powder Sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. (viii) Vulcanization Accelerator: Nocceler DZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N,N - Dicyclohexyl - 2 - benzothiazolylsulfenamide)

[0170] (2) Manufacture of Rubber Composition According to each compounding content shown in Table 1, using a Banbury mixer, materials other than sulfur and vulcanization accelerators are kneaded at 150 °C for 5 minutes to obtain a kneaded product. Each compounding amount is in parts by mass.

[0171] Next, sulfur and a vulcanization accelerator are added to the kneaded product obtained above, and using an open roll, it is kneaded at 80 °C for 5 minutes to obtain a rubber composition.

[0172] 2. Tire Manufacture First, the rubber composition obtained above is coated in the same amount on both sides of a steel cord with the specifications shown in Table 1 to produce a belt ply, and two sheets are laminated to form a belt layer.

[0173] Thereafter, it is bonded together with other tire members to form an unvulcanized tire, and press-vulcanized at 170 °C for 10 minutes to manufacture each test tire (Examples 1 to 8 and Comparative Examples 1 to 4) shown in Table 1.

[0174] 3. Parameter Calculation Regarding the rubber composition, a rubber test piece for viscoelasticity measurement with a length of 40 mm, a width of 4 mm, and a thickness of 1 mm is produced, and using an Implex series manufactured by GABO, under the conditions of temperature: 70 °C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: extension, the complex elastic modulus E * is measured.

[0175] And each parameter (D / E * -0.1×C, E×S, E×B) shown in Table 1 is calculated.

[0176] 4. Performance Evaluation (1) Evaluation of Low Fuel Consumption Using a rolling resistance tester, for each test tire, the rolling resistance coefficient RRC (Rolling Resistance Coefficient) is measured when running on a drum at a speed of 80 km / h under the following conditions. Service Rim: 15×6J Internal Pressure: 210 kPa Load: 4.35 kN

[0177] Next, taking the result in Comparative Example 1 as 100, it is indexed based on the following formula for low fuel consumption evaluation. The larger the numerical value, the better the low fuel consumption performance is indicated. Low fuel consumption evaluation = [(Result of Comparative Example 1) / (Result of the test tire)] × 100

[0178] (2) Evaluation of durability Each test tire is incorporated into a rim (size = 15 × 6J), the tire is filled with air, and after adjusting the internal pressure to 230 kPa, it is mounted on a drum running tester, a vertical load of 5.88 kN is applied, and the speed is gradually increased from 210 km / h in steps of 10 km / h to measure the time until the tire is damaged.

[0179] Next, taking the result in Comparative Example 1 as 100, it is indexed based on the following formula as an index of durability for evaluation. The larger the numerical value, the longer the time until damage, indicating better durability. Durability evaluation = [(Result of the test tire) / (Result of Comparative Example 1)] × 100

[0180] (3) Comprehensive performance evaluation The above low fuel consumption evaluation and durability evaluation are added together for comprehensive performance evaluation.

[0181]

Table 1

[0182] As described above, the present invention has been described based on the embodiments, but the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments within the same and equivalent scope as the present invention.

[0183] The present invention (1) is a tire provided with a belt layer formed by covering a belt cord with a rubber composition, the belt cord is composed of four filaments, The rubber composition has a cobalt content of less than 0.15 parts by mass with respect to 100 parts by mass of the rubber component. The diameter D (mm) of the belt cord and the complex elastic modulus E * (MPa) of the rubber composition measured under the conditions of temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: tension, and the cobalt content C (parts by mass) with respect to 100 parts by mass of the rubber component in the rubber composition satisfy the following formula. The tire is characterized by this. D / E * <0.1 × C + 0.170

[0184] The present invention (2) is The cobalt content in the rubber composition is less than 0.10 parts by mass with respect to 100 parts by mass of the rubber component, and it is the tire described in the present invention (1).

[0185] The present invention (3) is The cobalt content in the rubber composition is less than 0.05 parts by mass with respect to 100 parts by mass of the rubber component, and it is the tire described in the present invention (2).

[0186] The present invention (4) is The cobalt content in the rubber composition is less than 0.01 parts by mass with respect to 100 parts by mass of the rubber component, and it is the tire described in the present invention (3).

[0187] The present invention (5) is The cobalt content in the rubber composition is less than 0.005 parts by mass with respect to 100 parts by mass of the rubber component, and it is the tire described in the present invention (4).

[0188] The present invention (6) is In the tire width direction of the belt cord, the number of cords E (pieces) per 50 mm width and the surface area S (mm) per unit length (1 mm) satisfy the following formula, and it is a tire in any combination of the present inventions (1) to (5). E × S > 60

[0189] The present invention (7) is characterized in that in the tire width direction of the belt cord, the number of cords E (pieces) per 50 mm width and the bending stiffness B (g·cm) satisfy the following formula, and it is a tire in any combination with any one of the present inventions (1) to (5). E×B>1600

[0190] The present invention (8) is in the rubber composition, carbon black having a BET specific surface area of 45 m 2 / g or more is contained in an amount of 5 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the rubber component, and it is a tire in any combination with any one of the present inventions (1) to (5).

Explanation of Signs

[0191] 1 Tire 2 Tread portion 3 Sidewall portion 4 Bead portion 5 Bead core 6 Carcass 6A Carcass ply 6a Inner main body portion 6b Outer folded-back portion 7 Belt layer 7A First belt ply 7B Second belt ply 8 Bead apex rubber 10 Belt cord C Center line

Claims

1. A tire comprising a belt layer formed by coating a belt cord with a rubber composition, wherein the belt cord is composed of four filaments, and the rubber composition has a cobalt content of less than 0.15 parts by mass per 100 parts by mass of the rubber component. The diameter D (mm) of the belt cord and the complex elastic modulus E ＊ (MPa), and the amount C (parts by mass) of cobalt with respect to 100 parts by mass of the rubber component in the rubber composition satisfy the following formula, and a tire is characterized thereby. D / E ＊ <0.1 × C + 0.170

2. The tire according to claim 1, wherein the cobalt content in the rubber composition is less than 0.10 parts by mass per 100 parts by mass of the rubber component.

3. The tire according to claim 2, wherein the cobalt content in the rubber composition is less than 0.05 parts by mass per 100 parts by mass of the rubber component.

4. The tire according to claim 3, wherein the cobalt content in the rubber composition is less than 0.01 parts by mass per 100 parts by mass of the rubber component.

5. The tire according to claim 4, wherein the cobalt content in the rubber composition is less than 0.005 parts by mass per 100 parts by mass of the rubber component.

6. The tire according to any one of claims 1 to 5, wherein in the tire width direction of the belt cord, the number of cords E (pieces) per 50 mm width and the surface area S (mm) per unit length (1 mm) satisfy the following formula: E × S > 60

7. The tire according to any one of claims 1 to 5, wherein in the tire width direction of the belt cord, the number of cords E (pieces) per 50 mm width and the bending stiffness B (g·cm) satisfy the following formula: E × B > 1600

8. In the rubber composition, carbon black having a BET specific surface area of 45 m ２ / g or more is contained in an amount of 5 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the rubber component, and the tire according to any one of claims 1 to 5 is characterized thereby.

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