Tire

Abstract

The invention provides a tire capable of improving the comprehensive performance of high-speed durability and rolling resistance. A tire is provided with: a carcass provided with carcass cords; a belt layer provided with belt layer cords and provided on the outside of the carcass in the tire radial direction; a cap ply provided with a cap ply cord and provided on the outside of the belt layer in the tire radial direction; and a tread provided on the outside of the cap ply in the radial direction of the tire, in which the cap ply cords are formed by twisting one yarn comprising PET fibers, the tread is formed using a rubber composition having an acetone extraction component of more than 15 mass% so that the thickness exceeds 6 mm and the rubber hardness (Shore hardness) Hs exceeds 60, and the product of the diameter (mm) of the cap ply cords and the thickness (mm) of the tread is less than 5.0.

Description

Technical Field

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

[0002] As described in Patent Document 1, in a passenger car tire, from the aspect of preventing tire deformation caused by centrifugal force during high-speed driving, a crown ply (also referred to as a cap ply) is usually provided between the tread and the belt layer.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-38812 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] The problem of the present invention is to improve the comprehensive performance of high-speed durability and rolling resistance.

[0008] Means for Solving the Problems

[0009] The present invention relates to a tire having:

[0010] A carcass having carcass cords;

[0011] A belt layer having belt layer cords and provided on the radially outer side of the carcass of the tire;

[0012] A crown ply having crown ply cords and provided on the radially outer side of the belt layer of the tire; and

[0013] A tread provided on the radially outer side of the crown ply of the tire,

[0014] The tire is characterized in that

[0015] The above-mentioned crown ply cords are formed by twisting one yarn containing polyethylene terephthalate fiber,

[0016] The above-mentioned tread is formed of a rubber composition having an acetone extract component of more than 15% by mass to a thickness of more than 6 mm and a rubber hardness (Shore hardness) Hs of more than 60,

[0017] The product of the diameter (mm) of the above-mentioned crown ply cords and the thickness (mm) of the above-mentioned tread is less than 5.0.

[0018] Advantages of the Invention

[0019] According to the present invention, it is possible to improve the comprehensive performance of high-speed durability and rolling resistance. Brief Description of the Drawings

[0020] Figure 1 It is a schematic cross-sectional view of a tire showing an embodiment of the present invention. Detailed Embodiment

[0021] [1] Features of the tire of the present invention

[0022] First, the features of the tire of the present invention will be described.

[0023] 1. Outline

[0024] The tire of the present invention includes: a carcass having carcass cords; a belt layer having belt layer cords and provided on the radially outer side of the carcass in the tire; a chafer layer having chafer layer cords and provided on the radially outer side of the belt layer in the tire; and a tread provided on the radially outer side of the chafer layer in the tire. And, the chafer layer cords are formed by twisting one yarn containing polyethylene terephthalate (PET) fiber. In addition, the tread is formed of a rubber composition (tread rubber composition) having an acetone extract component of more than 15% by mass to a thickness of more than 6 mm and a rubber hardness (Shore hardness) Hs of more than 60. Further, the product of the diameter (mm) of the chafer layer cords and the thickness (mm) of the tread is less than 5.0.

[0025] By having these features, as described later, it is possible to improve the comprehensive performance of high-speed durability and rolling resistance.

[0026] 2. Mechanism of effect manifestation in the tire of the present invention

[0027] Regarding the mechanism of the above-described effect manifestation in the tire of the present invention, the following can be considered.

[0028] (1) Use of the PET chafer layer

[0029] In the tire of the present invention, the chafer layer cords use a single-twist PET chafer layer formed by twisting one yarn containing PET fiber.

[0030] (a) PET chafer layer

[0031] The PET chafer layer has a higher modulus than nylon 66 (polyamide synthetic fiber) which has been mainly used heretofore. Therefore, by adopting the PET chafer layer for the chafer layer cords, it is possible to further improve high-speed durability.

[0032] (b) Single-twist chafer layer

[0033] However, the PET chafer layer is more likely to generate heat than nylon 66 (polyamide synthetic fiber), which may cause deterioration of rolling resistance.

[0034] In the present invention, by using a single-twist cap ply formed by twisting one yarn as the cap ply cord, the heat generation is reduced. That is, by using the single-twist cap ply, the volume of the cap ply cord can be reduced, so the heat generation can be reduced.

[0035] In addition, the use of the single-twist cap ply can reduce the weight of the tire and achieve the light weight of the tire, so the rolling resistance can be reduced.

[0036] It should be noted that the thickness of the cord of the cap ply is preferably 0.01 mm or more and 0.05 mm or less, more preferably 0.02 mm or more and 0.04 mm or less. In addition, the total thickness of the cap ply is preferably 0.20 mm or more and 0.60 mm or less, more preferably 0.30 mm or more and 0.50 mm or less.

[0037] (2) Tread

[0038] However, in the case of using the single-twist cap ply, the compression fatigue resistance deteriorates, which may lead to a reduction in high-speed durability.

[0039] (a) Thickness of the tread

[0040] In the present invention, the tread is thickened. Specifically, the thickness exceeds 6 mm. Thereby, the compression on the cap ply can be reduced, so the compression fatigue resistance can be improved and the high-speed durability can be improved. More preferably, it is 8 mm or more, and further preferably 10 mm or more. As the upper limit, for example, it is preferably 20 mm or less, more preferably 15 mm or less, and further preferably 12 mm or less.

[0041] It should be noted that the tread may be formed of only one layer of the crown rubber layer, or may be formed of two layers by providing a base rubber layer inside the crown rubber layer. In addition, it may be three layers or four layers or more. In this case, the above-mentioned rubber composition for the tread becomes the rubber composition for forming the crown rubber layer.

[0042] In this case, the thickness of the crown rubber layer in the whole tread is preferably 10% or more, more preferably 30% or more, further preferably 50% or more, and further preferably 70% or more.

[0043] In the present invention, the thickness of the tread refers to the thickness of the tread on the tire equator plane in the radial cross-section of the tire. In the case where the tread is formed of a single rubber composition, it is the thickness of the rubber composition. In the case where it is formed of a laminated structure of two or more rubber compositions, it refers to the total thickness of these layers. In the cross-section cut out by cutting the tire in the radial direction, it can be measured by making the bead part in a state consistent with the normal rim width.

[0044] It should be noted that a "regular rim" refers to the rim specified for each tire in a standard system including the standards on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim in the applicable sizes recorded in the "JATMA YEARBOOK"; in the case of ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" recorded in the "STANDARDS MANUAL"; in the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" recorded in the "YEAR BOOK". Refer to them in the order of JATMA, ETRTO, and TRA. When there are applicable sizes, follow the relevant standard. Additionally, in the case of a tire not specified in the standard, it refers to the rim that can assemble the tire and maintain the internal pressure, that is, the rim with the smallest rim diameter and the narrowest rim width among the rims that do not leak air between the rim and the tire.

[0045] (b) Rubber hardness (Shore hardness) Hs

[0046] If the tread is soft, the deformation amount of the tread during high-speed driving becomes larger, and the compression applied to the belt layer becomes larger. Therefore, the high-speed durability may deteriorate due to compression fatigue.

[0047] In the present invention, the rubber hardness (Shore hardness) Hs of the tread exceeds 60. Thereby, sufficient rigidity can be ensured, the deformation of the tread during high-speed driving can be suppressed, and thus the compression fatigue applied to the belt layer can be reduced, achieving an improvement in high-speed durability.

[0048] It should be noted that the above-mentioned rubber hardness (Shore hardness) Hs can be measured using a Type A durometer according to the method specified in JIS K6253-3:2012.

[0049] Moreover, the rubber hardness (Shore hardness) Hs is more preferably 65 or more, and further preferably 70 or more. As the upper limit, for example, it is preferably 85 or less, and more preferably 80 or less.

[0050] (c) Acetone extract components

[0051] Furthermore, in the present invention, the acetone extract components (AE) of the tread exceed 15% by mass.

[0052] The acetone extract component (AE) can be regarded as an index indicating the amount of materials such as softeners that impart plasticity to the rubber component in the rubber composition, and can also be regarded as an index indicating the softness of the rubber composition. Therefore, when the AE amount of the tread is increased to a certain extent, even during high-speed driving, it is possible to sufficiently ensure the contact area with the road surface, and in addition, it is possible to suppress the heat generation caused by the concentration of the contact pressure, and it is possible to achieve an improvement in high-speed durability.

[0053] It should be noted that the measurement of the acetone extract component (AE) can be carried out in accordance with JIS K 6229:2015. Specifically, a vulcanized rubber test piece cut out from the measurement part is immersed in acetone for a specified time, and the mass reduction rate (%) of the test piece is obtained, and thus AE (mass%) can be obtained.

[0054] More specifically, each vulcanized rubber test piece can be immersed in acetone for 72 hours at normal temperature and normal pressure to extract soluble components, and the mass of each test piece before and after extraction is measured, and it can be obtained by the following formula.

[0055] Acetone extraction amount (%) = { (mass of rubber test piece before extraction - mass of rubber test piece after extraction) / (mass of rubber test piece before extraction)} × 100

[0056] In addition, the above-mentioned acetone extract component can be appropriately changed by changing the blending ratio of the plasticizer in the rubber composition.

[0057] It should be noted that as the AE amount, it is more preferably 17% by mass or more. On the other hand, as the upper limit, for example, it is preferably 25% by mass or less, more preferably 20% by mass or less.

[0058] (3) The product of the diameter (mm) of the cap ply cord and the thickness (mm) of the tread

[0059] The present inventors further conducted research and found that if the product of the diameter (mm) of the cap ply cord and the thickness (mm) of the tread is less than 5.0, the above-mentioned various effects are synergistically exerted, and it is considered that an improvement in the comprehensive performance of high-speed durability and rolling resistance can be achieved. It should be noted that the product of the diameter (mm) of the cap ply cord and the thickness (mm) of the tread is more preferably 3.0 or less, further preferably 2.5 or less. As the lower limit, for example, it is preferably 1.0 or more, more preferably 1.5 or more, further preferably 2.0 or more.

[0060] It should be noted that in the above, the tread is described as having 1 layer, but it can also be composed of 2 layers or more. In this case, it is preferable that the outermost layer (tread running surface layer) on the ground contact side satisfies the above-mentioned various parameters.

[0061] [2] More preferred embodiments of the tire of the present invention

[0062] The tire of the present invention can achieve greater effects by adopting the following methods.

[0063] 1. Belt ply cord

[0064] In the present invention, as the belt ply cord constituting the belt ply, a steel cord is preferred. From the aspect of reducing the weight of the tire, a cord composed of 4 or fewer filaments is preferred. As the lower limit, for example, 1 or more is preferred. It should be noted that the belt ply cord can adopt a twisting method such as single twist (such as 1×2 structure, etc.) or ply twist (such as 2+2 structure, etc.) for 1 to 4 filaments, or can also adopt non-twisting (untwisted).

[0065] In addition, the number of cord filaments per 50 mm width (density) is preferably 20 or more, more preferably 30 or more. It should be noted that as the upper limit, for example, 60 or less is preferred, more preferably 50 or less.

[0066] 2. Particle size of silica

[0067] In the present invention, the rubber composition for the tread preferably contains silica. At this time, if the particle size (average primary particle size) of silica is too small, the processability deteriorates, so silica with a particle size exceeding 8 nm is preferably used. More preferably, it is 9 nm or more, and further preferably 10 nm or more. On the other hand, from the aspects of ensuring the reinforcement of the rubber and ensuring the handling stability performance on a wet road surface during driving, it is preferably 25 nm or less, more preferably 20 nm or less, and further preferably 17 nm or less.

[0068] It should be noted that the average primary particle size of silica refers to the average value of the values obtained by observing the smallest particle unit of silica constituting the aggregated structure as a circle and measuring the absolute maximum length of the smallest particle as the diameter of the circle. It can be observed by a transmission or scanning electron microscope, 400 or more primary particles of silica observed in the field of view are measured, and the average value is obtained through them.

[0069] Specifically, the silica taken out from the rubber composition cut out from the tire is directly observed using an electron microscope or the like, and the equivalent cross-sectional diameter is calculated from the area of each silica particle obtained, and the average value is obtained, whereby the average primary particle size can be calculated.

[0070] 3. Resin component

[0071] In addition, the rubber composition forming the tread preferably contains a resin component.

[0072] By containing a resin component in the rubber composition, the adhesion of the resin component is utilized to improve the ground contact property with the road surface, and thus it is considered that the rolling resistance during starting can be further improved.

[0073] As the preferred resin component, preferred are the rosin-based resin, styrene-based resin, benzofuran-based resin, terpene-based resin, C5 resin, C9 resin, C5C9 resin, acrylic resin, etc. described later. Among them, styrene-based resins such as α-methylstyrene are more preferred. And, as the content relative to 100 parts by mass of the rubber component, it is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, and further preferably 50 parts by mass or more.

[0074] [3] Embodiment

[0075] Hereinafter, the present invention will be specifically described based on the embodiment.

[0076] 1. Tire of the present embodiment

[0077] Figure 1 is a schematic cross-sectional view for explaining the tire of the present embodiment. Figure 1 In it, the up-down direction is the radial direction of the tire, the left-right direction is the rotational axis direction of the tire, and the direction perpendicular to the paper surface is the circumferential direction of the tire. It should be noted that Figure 1 in it, the dotted line CL represents the equatorial plane of the tire. It should be noted that the shape of this tire is symmetric with respect to the equatorial plane except for the tread pattern, and thus Figure 1 1 / 4 of the entire tire is shown in it.

[0078] As Figure 1 shown, the tire 1 includes a tread 2, a pair of sidewalls 3, a pair of chafing parts 4, a pair of beads 5, an innerliner 6, a carcass 7, a belt layer 8, a pair of fillers 9, and a cap ply 10. The carcass 7, belt layer 8, cap ply 10, and tread 2 are arranged from the inner side to the outer side in the radial direction of the tire.

[0079] With such a configuration, as described above, as the cap ply cord, a cap ply cord formed by twisting 1 yarn containing PET fiber is used, and the tread is appropriately formed. In addition, by appropriately controlling the product of the diameter (mm) of the cap ply cord and the thickness (mm) of the tread, the comprehensive performance of high-speed durability and rolling resistance can be improved.

[0080] 2. Rubber composition for tread

[0081] In the present embodiment, the rubber composition for tread can be obtained by kneading various compounding materials such as a rubber component, a reinforcing material, an anti-aging agent, an oil, a resin material, and an anti-aging agent.

[0082] (1) Compounding materials

[0083] (a) Rubber component

[0084] The rubber component is not particularly limited, and for example, diene rubbers such as natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile rubber (NBR), chloroprene rubber (CR), and butyl rubber (IIR) can be used. They can be used alone or in combination of two or more. In the present invention, the combination of NR, SBR, and BR is preferred.

[0085] (①) SBR

[0086] The weight-average molecular weight of SBR is, for example, more than 100,000 and less than 2,000,000. The styrene content of SBR is, for example, preferably more than 5% by mass, more preferably more than 10% by mass, and further preferably more than 15% by mass. On the other hand, it is preferably less than 40% by mass, more preferably less than 35% by mass, and further preferably less than 30% by mass. The vinyl content (amount of 1,2-bonded butadiene units) of SBR is, for example, preferably more than 5% by mass, more preferably more than 10% by mass, and further preferably more than 15% by mass. On the other hand, it is preferably less than 70% by mass, more preferably less than 40% by mass, and further preferably less than 30% by mass. It should be noted that the structural identification (measurement of styrene content and vinyl content) of SBR can be carried out using, for example, a device of the JNM-ECA series manufactured by JEOL Ltd.

[0087] The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. can be used. The SBR can be either unmodified SBR or modified SBR. In addition, hydrogenated SBR obtained by hydrogenating the butadiene part in SBR can be used, and the hydrogenated SBR can also be obtained by subsequently hydrogenating the BR part in SBR, or the same structure can be obtained by copolymerizing styrene, ethylene, and butadiene.

[0088] As the modified SBR, SBR having a functional group that interacts with a filler such as silica is preferred, and examples thereof include end-modified SBR obtained by modifying at least one end of SBR with a compound (modifying agent) having the above functional group (end-modified SBR having the above functional group at the end); main-chain modified SBR having the above functional group in the main chain; main-chain end-modified SBR having the above functional group in the main chain and at the end (for example, main-chain end-modified SBR having the above functional group in the main chain and modifying at least one end with the above modifying agent); end-modified SBR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and introducing a hydroxyl group, an epoxy group, etc.

[0089] Examples of the above functional groups include, for example, amino group, amide group, silyl group, alkoxysilyl group, isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, oxycarbonyl group, mercapto group, thioether group, disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazine group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxy group, oxy group, epoxy group, etc. It should be noted that these functional groups may carry substituents.

[0090] In addition, as the modified SBR, for example, SBR modified with a compound (modifier) represented by the following formula can be used.

[0091] [Chemical formula 1]

[0092]

[0093] It should be noted that in the formula, R 1 , R 2 and R 3 are the same or different and represent an alkyl group, an alkoxy group, a silanyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH) or their derivatives. R 4 and R 5 are the same or different and represent a hydrogen atom or an alkyl group. R 4 and R 5 may be bonded to form a ring structure together with the nitrogen atom. n represents an integer.

[0094] As the modified SBR modified with the compound (modifier) represented by the above formula, SBR obtained by modifying the polymerization terminal (active terminal) of solution-polymerized styrene-butadiene rubber (S-SBR) with the compound represented by the above formula (modified SBR described in Japanese Patent Laid-Open No. 2010-111753, etc.) can be used.

[0095] As R 1 , R 2 and R 3 , an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms) is suitable. As R 4 and R 5 , an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is suitable. n is preferably 1 to 5, more preferably 2 to 4, and further preferably 3. In addition, when R 4 and R 5 are bonded to form a ring structure together with the nitrogen atom, a 4- to 8-membered ring is preferred. It should be noted that the alkoxy group also includes cycloalkoxy groups (such as cyclohexyloxy group) and aryloxy groups (such as phenoxy group, benzyloxy group).

[0096] As specific examples of the above-mentioned modifiers, 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. can be cited. They can be used alone or in combination of two or more.

[0097] In addition, as the modified SBR, a modified SBR modified with the following compounds (modifying agents) can also be used. Examples of the modifying agent include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups such as diglycidylated bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylamino compounds such as diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl-o-toluidine, tetraglycidyl-m-xylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bis(aminomethyl)cyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamoyl chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamoyl chloride, and N,N-diethylcarbamoyl chloride; epoxy group-containing silane compounds such as 1,3-bis(epoxypropylpropyl)-tetramethyldisiloxane and (3-epoxypropylpropyl)-pentamethyldisiloxane; thioether group-containing silane compounds such as (trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tripropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxysilyl)propyl]sulfide, and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide; N-substituted aziridine compounds such as aziridine and propyleneimine; alkoxysilanes such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane;(Thio)benzophenone compounds having an amino group and / or a substituted amino group such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-tert-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, N,N,N',N'-bis-(tetraethylamino)benzophenone; benzaldehyde compounds having an amino group and / or a substituted amino group such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone, N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, N-phenyl-2-piperidone; N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurolactam, N-vinyl-ω-laurolactam, N-methyl-β-propiolactam, N-phenyl-β-propiolactam; and N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tri-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-trione, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylvinylurea, 1,3-divinylvinylurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-acetone, 1,7-bis(methylethylamino)-4-heptanone, etc. It should be noted that the modification by the above compounds (modifiers) can be carried out by known methods.;

[0098] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., ENEOS Materials Co., Ltd., Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used. It should be noted that the SBR can be used alone or in combination of two or more kinds.

[0099] The content of SBR in 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably 45 parts by mass or more, and further preferably 50 parts by mass or more. As the upper limit, for example, it is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and further preferably 60 parts by mass or less.

[0100] (②) Isoprene rubber

[0101] As the isoprene rubber, natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, etc. can be cited. From the aspect of excellent strength, NR is preferred.

[0102] As NR, for example, SVR-L, SIR20, RSS#3, TSR20, etc., which are commonly used in the tire industry, can be used. As IR, there is no particular limitation, and for example, IR2200 manufactured by Zeon Corporation can be used, which is commonly used in the tire industry. As the modified NR, deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. can be cited. As the modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. can be cited. As the modified IR, epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. can be cited. They can be used alone or in combination of two or more.

[0103] The content of the isoprene rubber in 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more. As the upper limit, for example, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less.

[0104] (③) BR

[0105] The weight-average molecular weight of BR is, for example, more than 100,000 and less than 2,000,000. The vinyl content of BR is, for example, more than 1% and less than 30%. The cis content of BR is, for example, more than 1% and 98% or less. The trans amount of BR is, for example, more than 1% and less than 60%. It should be noted that the cis content can be measured by infrared absorption spectrometry.

[0106] There is no particular limitation for BR, and BR with a high cis content (cis content of 90% or more), BR with a low cis content, BR containing syndiotactic polybutadiene crystals, etc. can be used. BR can be either unmodified BR or modified BR. As the modified BR, for example, BR modified with a compound (modifying agent) represented by the following formula can be used.

[0107] [Chemical formula 2]

[0108]

[0109] It should be noted that in the formula, R 1 , R 2 and R 3 are the same or different and represent an alkyl group, an alkoxy group, a silanyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or a derivative thereof. R 4 and R 5 are the same or different and represent a hydrogen atom or an alkyl group. R4 and R 5 can be bonded to form a ring structure together with the nitrogen atom. n represents an integer.

[0110] As the modified BR modified with the compound (modifier) represented by the above formula, BR obtained by modifying the polymerization terminal (active terminal) with the compound represented by the above formula can be mentioned.

[0111] As R 1 、R 2 and R 3 , it is preferably an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms). As R 4 and R 5 , it is preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and further preferably 3. In addition, when R 4 and R 5 are bonded to form a ring structure together with the nitrogen atom, it is preferably a 4- to 8-membered ring. It should be noted that the alkoxy group also includes cycloalkoxy groups (such as cyclohexyloxy) and aryloxy groups (such as phenoxy and benzyloxy).

[0112] Specific examples of the above modifier include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. They can be used alone or in combination of two or more.

[0113] In addition, as the modified BR, a modified BR obtained by modifying with the following compounds (modifying agents) can also be used. Examples of the modifying agent include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups such as diglycidylated bisphenol A; polyepoxides such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; tertiary amines containing epoxy groups such as 4,4'-diglycidyl-diphenylmethanamine and 4,4'-diglycidyl-dibenzylmethanamine; diglycidylamino compounds such as diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl-o-toluidine, tetraglycidyl-m-xylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bis(aminomethyl)cyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamoyl chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamoyl chloride, and N,N-diethylcarbamoyl chloride; silane compounds containing epoxy groups such as 1,3-bis-(glycidoxypropyl)-tetramethyldisiloxane and (3-glycidoxypropyl)-pentamethyldisiloxane; sulfur ether group-containing silane compounds such as (trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tripropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxysilyl)propyl]sulfide, and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide; N-substituted aziridine compounds such as aziridine and propyleneimine; alkoxysilanes such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane;(Thio)benzophenone compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-tert-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, N,N,N',N'-bis-(tetraethylamino)benzophenone, etc.; Benzaldehyde compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, 4-N,N-divinylaminobenzaldehyde, etc.; N-substituted pyrrolidones such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone, N-methyl-5-methyl-2-pyrrolidone, etc.; N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, N-phenyl-2-piperidone, etc.; N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurolactam, N-vinyl-ω-laurolactam, N-methyl-β-propiolactam, N-phenyl-β-propiolactam, etc.; and N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-trione, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylvinylurea, 1,3-divinylvinylurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-acetone, 1,7-bis(methylethylamino)-4-heptanone, etc. It should be noted that the modification by the above compounds (modifiers) can be carried out by known methods. It should be noted that these modified BRs can be used alone or in combination of two or more.

[0114] As the BR, products of, for example, Ube Industries, Ltd., ENEOS Materials Co., Ltd., Asahi Kasei Corporation, Zeon Corporation, etc. can be used.

[0115] The content of BR in 100 parts by mass of the rubber component is preferably 25 parts by mass or more, more preferably 30 parts by mass or more. On the other hand, it is preferably 40 parts by mass or less, more preferably 35 parts by mass or less.

[0116] (④) Other rubber components

[0117] In the rubber composition, as other rubber components, rubber (polymers) such as nitrile rubber (NBR) that are commonly used in the manufacture of tires may be included as needed.

[0118] It should be noted that the raw materials (monomers) of the above synthetic rubbers such as SBR and BR can be derived from underground resources such as petroleum and natural gas, or can be recycled from rubber products such as tires or non-rubber products such as polystyrene.

[0119] As the monomers obtained by recycling (recycled monomers), there is no particular limitation, and examples include recycled isoprene, recycled butadiene, recycled aromatic vinyl monomers, etc. As the above butadiene, 1,2-butadiene and 1,3-butadiene can be cited. As the above aromatic vinyl monomer, there is no particular limitation, and styrene etc. can be cited. Among them, recycled isoprene (recycled isoprene), butadiene (recycled butadiene) and / or recycled styrene (recycled styrene) are preferably used as raw materials.

[0120] As the method for manufacturing recycled monomers, there is no particular limitation, and examples include synthesis from recycled naphtha obtained by decomposing rubber products such as tires. In addition, as the method for manufacturing recycled naphtha, there is no particular limitation. For example, rubber products such as tires can be decomposed under high temperature and high pressure, or can be decomposed by microwave, or can be extracted after mechanical pulverization.

[0121] In addition, the raw materials (monomers) of synthetic rubbers such as IR, SBR, and BR can be derived from biomass. Here, biomass refers to substances from natural resources such as plants. As biomass, there is no particular limitation, and examples include agricultural, forestry, and fishery products, sugars, wood, plant residues after obtaining useful components, plant-derived ethanol, biomass naphtha, etc. As the monomers from biomass (biomass monomers), there is no particular limitation, and examples include butadiene from biomass, aromatic vinyl monomers from biomass, etc. As the above butadiene, 1,2-butadiene and 1,3-butadiene can be cited. As the above aromatic vinyl monomer, there is no particular limitation, and styrene etc. can be cited. In addition, the method for manufacturing biomass monomers is not particularly limited, and examples include methods based on biological and / or chemical and / or physical conversion of animals and plants. As biological conversion, fermentation using microorganisms is representative, and as chemical and physical conversion, conversion using catalysts, conversion using high heat, conversion using high pressure, conversion using electromagnetic waves, conversion using critical liquids, and combinations thereof can be cited.

[0122] As the polymer synthesized from biomass monomer components (biomass polymer), there is no particular limitation, and examples thereof include polybutadiene rubber synthesized from butadiene derived from biomass, aromatic vinyl monomer / butadiene copolymer synthesized from butadiene derived from biomass and / or aromatic vinyl monomer derived from biomass, etc. As the above-mentioned aromatic vinyl monomer / butadiene copolymer, for example, styrene-butadiene rubber synthesized from butadiene derived from biomass and / or styrene derived from biomass can be cited.

[0123] Whether the raw material of the polymer is derived from biomass can be judged by pMC (percent Modern Carbon) measured according to ASTM D 6866-10.

[0124] pMC refers to the 14 ratio of the C concentration of the sample to the 14 C concentration of the modern standard reference, and this value is used as an index representing the biomass ratio of the compound (rubber). The meaning of this value is as described below.

[0125] Among 1 mole (6.02×10 23 pieces) of carbon atoms, there are approximately one trillionth of ordinary carbon atoms, that is, about 6.02×10 11 pieces 14 of 14 C. 14 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 them to decay. Therefore, after carbon dioxide in the atmosphere, etc. is taken in and immobilized by plants, etc., it is considered that in fossil fuels such as coal, oil, and natural gas that have passed more than 226,000 years, all of the 14 C elements contained in these substances at the beginning of immobilization have decayed. Therefore, in the present of the 21st century, fossil fuels such as coal, oil, and natural gas do not contain 14 C elements at all. Therefore, chemical substances produced from these fossil fuels also do not contain

[0126] On the other hand, cosmic rays undergo nuclear reactions in the atmosphere and continuously generate 14 C, which is in balance with the decrease caused by radiation decay, and the amount of 14 C in the atmospheric environment of the earth is a certain amount. Therefore, the 14 C concentration of substances derived from biomass resources that are recycled in the current environment is about 1×10 -12Values around mol%. Therefore, by using the difference between these values, the proportion (biomass proportion) of the compound derived from natural resources (compound derived from biomass resources) in a certain compound (rubber) can be calculated.

[0127] This 14 C is usually measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ([[]] 13 C / [[[]] 12 C), [[[]] 14 C concentration ([[]] 14 C / [[[]] 12 C) are measured. In the measurement, the [[[]] 14 C concentration in the circulating carbon in nature in 1950 is used as the [[[]] 14 C concentration reference, that is, the modern standard reference. As a specific standard substance, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific radioactivity of carbon in this oxalic acid (radioactivity intensity of [[[]] 14 C per 1 g of carbon) is divided into each carbon isotope, and [[[]] 13 C is corrected to a certain value, and decay correction is performed from 1950 AD to the measurement date, and the obtained value is used as the standard [[[]] 14 C concentration value (100%). The ratio of this value to the value of the actually measured sample becomes the pMC value.

[0128] Therefore, if rubber is made from a substance that is 100% derived from biomass (natural system), although there are regional differences, etc., it usually does not reach 100 under normal conditions at present, so it shows a value of about 110 pMC. On the other hand, for chemical substances derived from fossil fuels such as petroleum, when measuring the [[[]] 14 C concentration, it shows a value of about 0 pMC (for example, 0.3 pMC). This value corresponds to the biomass proportion of 0% mentioned above.

[0129] In summary, from the aspect of environmental protection (sustainability), it is suitable to use materials such as rubber with a high pMC value, that is, rubber materials with a high biomass proportion, in the rubber composition.

[0130] (b) Blending materials other than rubber components

[0131] (①) Filler

[0132] The rubber composition preferably contains silica or carbon black as a reinforcing agent, but other fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc. can also be contained as needed. It should be noted that when using silica, it is preferably used in combination with a silane coupling agent.

[0133] As the compounding amount of the filler, relative to 100 parts by mass of the rubber component, it is preferably at least more than 75 parts by mass of silica, and the total compounding amount with other fillers is preferably 80 parts by mass or more, more preferably 90 parts by mass or more relative to 100 parts by mass of the rubber component. On the other hand, from the aspect of dispersibility in the rubber composition, it is preferably 150 parts by mass or less, more preferably 100 parts by mass or less.

[0134] (i) Silica

[0135] Silica has OH groups on its surface. Therefore, by containing a large amount of more than 75 parts by mass, hydrogen bonds are generated between the silica surfaces, and it also interacts with the rubber component. Therefore, when driving, it is easy to generate and transmit forces inside the rubber, and it is easy to transmit the forces generated during turning, ensuring excellent handling stability. In addition, the OH groups on the surface can capture ozone, so the ozone resistance is improved, and the durability of the tire can be enhanced. It should be noted that the content of silica is more preferably 80 parts by mass or more, further preferably 90 parts by mass or more relative to 100 parts by mass of the rubber component. As the upper limit, for example, it is preferably 150 parts by mass or less, more preferably 100 parts by mass or less.

[0136] From the aspect of obtaining good durability performance, the BET specific surface area of silica is preferably more than 100 m 2 / g, more preferably more than 130 m 2 / g. On the other hand, it is preferably less than 250 m 2 / g, more preferably less than 200 m 2 / g. It should be noted that the above BET specific surface area is the value of N2SA measured by the BET method according to ASTM D3037-93.

[0137] As silica, there is no particular limitation, and silica commonly used in the tire industry such as silica prepared by the dry method (anhydrous silica) and silica prepared by the wet method (hydrous silica) can be used. As commercially available products, products of Evonik Industries, Rhodia, Tosoh Silica Corporation, Solvay Japan Corporation, Tokuyama Corporation, etc. can be used.

[0138] As the raw material of silica, there is no particular limitation. For example, it can be a raw material from a mineral source such as quartz, or a raw material from a biological source such as rice husk (for example, silica based on biomass materials such as rice husk), and recycled silica from products containing silica can also be used. Among them, due to the large number of silanol groups, hydrous silica prepared by the wet method is preferred.

[0139] Silica made from biomass materials (biomass silica) can be obtained, for example, as follows: Silicate is extracted from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and the precipitate of silica produced by reacting this silicate with sulfuric acid is filtered, washed with water, dried, and pulverized in the same manner as existing wet silica, whereby it can be obtained.

[0140] Silica recycled from products containing silica (recycled silica) can use, for example, silica recovered from products containing silica such as semiconductor and other electronic components, tires, desiccants, and filter materials such as diatomaceous earth. In addition, as the recovery method, there is no particular limitation, and examples include thermal decomposition and decomposition using electromagnetic waves. Among them, silica recovered from semiconductor and other electronic components or tires is preferred.

[0141] If silica crystallizes, it is insoluble in water and the silicic acid as its component cannot be utilized. By controlling the combustion temperature and combustion time, crystallization of silica in rice husk ash can be suppressed (refer to Japanese Patent Laid-Open No. 2009-2594, Akita Prefectural University Internet Journal B / 2019, vol. 6, p. 216-222, etc.).

[0142] Amorphous silica extracted from rice husks can use commercially available amorphous silica such as that from Wilmar Corporation.

[0143] It should be noted that these silicas can be used alone or in combination of two or more. It should be noted that from the aspect of environmental protection, it is suitable to use sustainable silicas such as biomass silica and recycled silica.

[0144] As described above, the content of silica relative to 100 parts by mass of the rubber component exceeds 75 parts by mass relative to 100 parts by mass of the rubber component, more preferably 80 parts by mass or more, and still more preferably 90 parts by mass or more. As the upper limit, for example, it is preferably 150 parts by mass or less, and more preferably 100 parts by mass or less.

[0145] (ii) Silane coupling agent

[0146] When using silica, in order to improve the dispersibility of silica and achieve improvements in mechanical properties, moldability, etc. through reaction with silica, it is preferable to use a silane coupling agent in combination.

[0147] As the silane coupling agent, there is no particular limitation, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide and other sulfur-containing compounds, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, NXT, NXT-Z manufactured by Momentive and other mercapto-containing compounds, vinyltriethoxysilane, vinyltrimethoxysilane and other vinyl-containing compounds, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane and other amino-containing compounds, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and other glycidoxy-containing compounds, 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane and other nitro-containing compounds, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane and other chlorine-containing compounds, etc. Among them, a silane coupling agent having a thiocarbonyl group such as the above-mentioned NXT is preferred. They can be used alone or in combination of two or more.

[0148] As the silane coupling agent, products of Evonik Industries, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., AZmax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used.

[0149] The content of the silane coupling agent is preferably more than 3 parts by mass, more preferably 5 parts by mass or more, and still more preferably 7 parts by mass or more, relative to 100 parts by mass of silica. As the upper limit, it is preferably less than 15 parts by mass, more preferably 12 parts by mass or less, and still more preferably 9 parts by mass or less.

[0150] (iii) Carbon black

[0151] Carbon black is preferably used for the purpose of improving the crack growth resistance, durability, ultraviolet degradation resistance, etc. of the tire.

[0152] From the aspect of the reinforcing property of rubber, the nitrogen adsorption specific surface area (N2SA) of carbon black is, for example, preferably 30 m 2 / g or more, more preferably 50 m 2 / g or more, and still more preferably 60 m 2 / g or more. On the other hand, from the aspect of heat generation, it is preferably 250 m 2 / g or less, more preferably 150 m 2 / g or less, and still more preferably 120 m 2 / g or less. It should be noted that the nitrogen adsorption specific surface area of carbon black is measured according to ASTM D4820-93.

[0153] From the aspect of the rigidity of rubber, the dibutyl phthalate (DBP) absorption of carbon black is, for example, preferably 50 ml / 100 g or more, more preferably 100 ml / 100 g or more. On the other hand, from the aspect of the followability to rubber deformation, it is preferably 250 ml / 100 g or less, more preferably 150 ml / 100 g or less. It should be noted that the DBP absorption of carbon black is measured according to ASTM D2414-93.

[0154] There is no particular limitation on the carbon black, and examples thereof include furnace black such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF (Furnace carbon black); acetylene black (Acetylene carbon black); thermal carbon black such as FT and MT (Thermal carbon black); channel carbon black such as EPC, MPC, and CC (Channelcarbon black), etc. In addition, as the part number, examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. They can be used alone or in combination of two or more.

[0155] In addition to mineral oil, the raw material of carbon black can also be biomass materials such as lignin and vegetable oil, or pyrolysis oil (recycled carbon black) obtained by pyrolyzing rubber products containing carbon black such as waste tires. From the aspect of environmental protection, it is suitable to use these sustainable carbon blacks.

[0156] In addition, the carbon black can be manufactured by combustion such as the furnace method, or by hydrothermal carbonization (HTC), or by thermal decomposition of methane based on the thermal carbon black method, etc.

[0157] 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. They can be used alone or in combination of two or more.

[0158] The content of carbon black relative to 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more. As the upper limit, for example, it is preferably 25 parts by mass or less, more preferably 20 parts by mass or less.

[0159] (iv) Other fillers

[0160] In addition to the above carbon black and silica, the rubber composition may further contain fillers such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, magnesium sulfate, etc. which are commonly used in the tire industry. Their content is, for example, more than 0.1 part by mass and less than 150 parts by mass relative to 100 parts by mass of the rubber component.

[0161] (②) Softening agent component

[0162] In the rubber composition, from the aspect of imparting plasticity to the rubber component during mixing and appropriately dispersing the powder material, a softening agent component is preferably used as needed. It should be noted that the softening agent component here is a concept including both softening agents that are liquid at 25°C and softening agents that are solid at 25°C.

[0163] Examples of softening agents can include resin components, oils, liquid polymers, ester plasticizers, etc. These softening agents can be derived from mineral resources such as petroleum or natural gas, can also be derived from biomass, and can also be derived from naphtha recycled from rubber products and non-rubber products. In addition, low-molecular-weight hydrocarbon components obtained by pyrolysis and extraction of used tires or products containing various components can be used as softening agents, among which softening agents derived from biomass or from recycling are preferably used as sustainable softening agents.

[0164] It should be noted that these softening agents can be used alone or in combination of two or more. As the content of the plasticizer component relative to 100 parts by mass of the rubber component, it is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 25 parts by mass or more. As the upper limit, for example, it is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and further preferably 30 parts by mass or less. It should be noted that the content of the plasticizer component also includes the amount of oil contained in rubber (oil-extended rubber), etc.

[0165] (i) Oil

[0166] As the oil, for example, mineral oil, vegetable oil, animal oil, etc. can be cited. In addition, from the aspect of life cycle assessment, the oil refined from waste oil used in a rubber mixer or an engine, or waste cooking oil used in a cooking store can also be used.

[0167] (i-1) Mineral oil

[0168] Mineral oil refers to the oil derived from mineral resources such as petroleum and natural gas. As mineral oil, paraffinic oil (mineral oil), naphthenic oil, aromatic oil, etc. can be cited.

[0169] As specific mineral oil, 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. can be cited.

[0170] In addition, for environmental countermeasures, the oil with a low content of polycyclic aromatic compound (PCA) can also be used. As the above-mentioned oil with a low PCA content, MES, TDAE, heavy naphthenic oil, etc. can be cited.

[0171] As commercially available mineral oil, for example, paraffinic, aromatic, naphthenic, etc. oils can be cited. The products of Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., OLISOY Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kogyo Co., Ltd., etc. can be used. They can be used alone or in combination of two or more.

[0172] (i-2) Vegetable oil

[0173] As vegetable oil, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, fragrant oil, castor oil, tung oil, pine oil, pine tar, 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. can be cited.

[0174] In addition, as vegetable oils, refined oils (such as salad oil) refined from the above-mentioned various oils, transesterified oils after transesterification, solidified oils after hydrogenation, thermally polymerized oils after thermal polymerization, oxidation-polymerized oils after oxidation, waste cooking oils recovered after use as edible oils, etc. may also be cited. It should be noted that vegetable oils can be liquid or solid at normal temperature (25°C). They can be used alone or in combination of two or more.

[0175] As vegetable oils, acylglycerols are preferably contained, and triacylglycerols are more preferably contained. It should be noted that acylglycerols refer to compounds in which the hydroxyl groups of glycerol form ester bonds with fatty acids. As acylglycerols, there is no particular limitation, and they can be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. In addition, acylglycerols can be monomers, dimers, or polymers of trimer or higher. It should be noted that acylglycerols of dimer or higher can be obtained by thermal polymerization or oxidation polymerization, etc. In addition, acylglycerols can be liquid or solid at normal temperature (25°C).

[0176] As a method for confirming whether acylglycerols are contained in the rubber composition, there is no particular limitation, and it can be confirmed by 1 1H-NMR measurement. For example, a rubber composition admixed with triacylglycerol is immersed in deuterated chloroform at normal temperature (25°C) for 24 hours. After removing the rubber composition, 1H-NMR is measured at room temperature. 1 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. It is presumed that these signals are signals from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. Therefore, it can be confirmed that acylglycerols are contained. It should be noted that "around" here refers to the range of ±0.10 ppm.

[0177] It should be noted that as fatty acids, there is no particular limitation, and they can be unsaturated fatty acids or saturated fatty acids. As unsaturated fatty acids, monovalent unsaturated fatty acids such as oleic acid, and polyvalent unsaturated fatty acids such as linoleic acid and linolenic acid can be cited. In addition, as saturated fatty acids, butyric acid, lauric acid, etc. can be cited.

[0178] Among them, as the above-mentioned fatty acids, fatty acids with fewer double bonds, that is, saturated fatty acids or monovalent unsaturated fatty acids, are preferably contained, and oleic acid is preferred. As vegetable oils containing such fatty acids, for example, vegetable oils containing saturated fatty acids or monovalent unsaturated fatty acids can be used, or vegetable oils modified by transesterification or the like can be used. In addition, in order to produce vegetable oils containing such fatty acids, plants can also be improved by variety improvement, genetic recombination, genome editing, etc.

[0179] As the vegetable oil, commercially available vegetable oils such as those produced by Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, OLISOY Corporation, H&R Corporation, Toyokuni Oil Co., Ltd., Fujikosan Co., Ltd., Nisshin Oillio Group, Ltd. can be used.

[0180] (ii) Liquid rubber

[0181] Liquid rubber refers to a polymer in a liquid state at normal temperature (25 °C), which is a rubber component that can be extracted from vulcanized tires by acetone extraction. Examples of liquid rubber include farnesene-based polymers, liquid diene-based polymers, and their hydrides.

[0182] Farnesene-based polymers refer to polymers obtained by polymerizing farnesene and having structural units based on farnesene. 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) exist in farnesene.

[0183] The farnesene-based polymer can be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

[0184] 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.

[0185] The polystyrene-reduced weight-average molecular weight (Mw) of the liquid diene-based polymer measured by gel permeation chromatography (GPC) is, for example, more than 1.0×10 3 and less than 2.0×10 5 . Here, the Mw of the liquid diene-based polymer is a polystyrene-reduced value measured by gel permeation chromatography (GPC).

[0186] As the liquid rubber, products of, for example, KURARAY Co., Ltd., Cray Valley Corporation, etc. can be used.

[0187] (iii) Resin component

[0188] The resin component also functions as an adhesion - imparting component. It can be solid or liquid at room temperature. As specific resin components, for example, rosin - based resins, styrene - based resins, benzofuran - based resins, terpene - based resins, C5 resins, C9 resins, C5C9 resins, acrylic resins, etc. can be cited, and two or more of them can be used in combination. It should be noted that these resin components can also be provided with modified groups capable of reacting with silica, etc. as required.

[0189] Rosin - based resins are resins mainly composed of rosin acid obtained by processing pine resin. This rosin - based resin (rosin type) can be classified according to whether it is modified or not, and can be classified into unmodified rosin (unmodified rosin) and rosin modifiers (rosin derivatives). As unmodified rosin, tall oil rosin (also known as tall oil pitch), gum rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins can be cited. Rosin modifiers are modifiers of unmodified rosin, and examples include rosin esters, unsaturated carboxylic acid - modified rosins, unsaturated carboxylic acid - modified rosin esters, amide compounds of rosin, amine salts of rosin, etc.

[0190] Styrene - based resins are polymers using styrene - based monomers as constituent monomers, and examples include polymers obtained by polymerizing styrene - based monomers as the main component (50% by mass or more). Specifically, in addition to homopolymers obtained by homopolymerizing 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.) respectively, and copolymers obtained by copolymerizing two or more styrene - based monomers, copolymers of styrene - based monomers and other monomers capable of copolymerizing with them can also be cited.

[0191] As the above - mentioned other monomers, examples include acrylonitrile - based monomers such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylic acid and 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 or their anhydrides such as maleic anhydride; etc.

[0192] Among benzofuran - based resins, benzofuran - indene resins are preferred. Benzofuran - indene resins are resins containing benzofuran and indene as monomer components forming the resin skeleton (main chain). As monomer components contained in the skeleton in addition to benzofuran and indene, styrene, α - methylstyrene, methyl indene, vinyltoluene, etc. can be cited.

[0193] The hydroxyl value (OH value) of the benzofuran indene resin is, for example, more than 15 mgKOH / g and less than 150 mgKOH / g. It should be noted that the OH value refers to the amount of potassium hydroxide required to neutralize acetic acid bonded to hydroxyl groups when 1 g of the resin is acetylated, expressed in milligrams, and is a value measured by potentiometric titration method (JIS K 0070:1992).

[0194] The softening point of the benzofuran indene resin is, for example, more than 30 °C and less than 160 °C. It should be noted that the softening point is the softening point specified in JIS K 6220-1:2001 measured using a ring and ball softening point apparatus, which is the temperature at which the ball drops.

[0195] Examples of terpene resins include polyterpene, terpene phenol, aromatic modified terpene resin, etc. Polyterpene is a resin obtained by polymerizing terpene compounds and its hydrides. Terpene compounds are hydrocarbons and their oxygen-containing derivatives represented by the composition of (C5H8), and are compounds having a basic skeleton of terpenes classified as monoterpene (C n H 10 ), sesquiterpene (C 16 H 15 ), diterpene (C 24 H 20 ), etc. Examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, allo-ocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, etc. 32 )

[0196] As polyterpenes, in addition to terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, β-pinene / limonene resin, etc. which are made from the above-mentioned terpene compounds as raw materials, hydrogenated terpene resins obtained by hydrogenating the terpene resins can also be cited. As terpene phenols, resins obtained by copolymerizing the above-mentioned terpene compounds and phenolic compounds, and resins obtained by hydrogenating the resins can be cited. Specifically, resins obtained by condensing the above-mentioned terpene compounds, phenolic compounds and formaldehyde can be cited. It should be noted that as phenolic compounds, for example, phenol, bisphenol A, cresol, xylenol, etc. can be cited. As aromatic-modified terpene resins, resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the resins can be cited. It should be noted that as aromatic compounds, as long as they are compounds having an aromatic ring, there is no particular limitation, and for example, phenolic compounds such as phenol, alkylphenol, alkoxyphenol, phenol containing an unsaturated hydrocarbon group; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, naphthol containing an unsaturated hydrocarbon group; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, styrene containing an unsaturated hydrocarbon group; benzofuran, indene, etc. can be cited.

[0197] "C5 resin" refers to a resin obtained by polymerizing C5 fractions. As C5 fractions, for example, petroleum fractions corresponding to 4 to 5 carbon atoms such as cyclopentadiene, pentene, pentadiene, isoprene, etc. can be cited. As C5 petroleum resins, dicyclopentadiene resin (DCPD resin) is preferably used.

[0198] "C9 resin" refers to a resin obtained by polymerizing C9 fractions, and can also be a resin obtained by hydrogenating or modifying them. As C9 fractions, for example, petroleum fractions corresponding to 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, indene, methylindene, etc. can be cited. As a specific example, for example, benzofuran indene resin, benzofuran resin, indene resin and aromatic vinyl resin are preferably used. As aromatic vinyl resins, due to reasons such as economy, easy processing, and excellent heat generation properties, α-methylstyrene (AMS resin) or homopolymers of styrene or copolymers of α-methylstyrene and styrene are preferred, and copolymers of α-methylstyrene and styrene are more preferred. As aromatic vinyl resins, for example, aromatic vinyl resins commercially available from KRATON Corporation, Eastman Chemical Company, etc. can be used.

[0199] "C5C9 resin" refers to a resin obtained by copolymerizing the above-mentioned C5 fractions and the above-mentioned C9 fractions, and can also be a resin obtained by hydrogenating or modifying them. As C5 fractions and C9 fractions, the above-mentioned petroleum fractions can be cited. As C5C9 resins, for example, resins commercially available from Tosoh Corporation, LUHUA Company, etc. can be used.

[0200] The acrylic resin is not particularly limited, and for example, a solvent-free acrylic resin can be used.

[0201] Solvent-free acrylic resins include (meth) acrylic resins (polymers) synthesized by a high temperature continuous polymerization method (high temperature continuous bulk polymerization method) (methods described in U.S. Patent No. 4,414,370, Japanese Patent Publication No. 59-6207, Japanese Patent Publication No. 5-58005, Japanese Patent Publication No. 1-313522, U.S. Patent No. 5,010,166, East Asia Synthesis Research Annual Report TREND 2000 No. 3, p. 42-45, etc.) without using a polymerization initiator, a chain transfer agent, an organic solvent, etc. as secondary raw materials as much as possible. It should be noted that in the present invention, (meth) acrylic acid refers to methacrylic acid and acrylic acid.

[0202] Examples of the monomer components constituting the acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters, aryl esters, arylalkyl esters, etc.), (meth)acrylamide, and (meth)acrylic acid derivatives such as (meth)acrylamide derivatives.

[0203] As monomer components constituting the acrylic resin, aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene may be used together with (meth)acrylic acid or a (meth)acrylic acid derivative.

[0204] The acrylic resin may be a resin composed only of a (meth)acrylic acid component or a resin containing components other than the (meth)acrylic acid component as constituent elements. In addition, the acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

[0205] As the resin component, for example, products of Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, KRATON, Nippon Paint Chemicals Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Co., Ltd., Arakawa Chemical Industries, Ltd., and Taoka Chemical Industries, Ltd. can be used.

[0206] (③) Wax

[0207] The rubber composition may contain wax. The content of the wax is, for example, preferably 0.5 to 20 parts by mass, more preferably 1.0 to 15 parts by mass, and even more preferably 1.5 to 10 parts by mass, relative to 100 parts by mass of the rubber component.

[0208] As the wax, there is no particular limitation, and any wax commonly used in the tire industry can be suitably used. For example, mineral waxes, waxes of plant origin, etc. can be cited. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Waxes of plant origin refer to waxes derived from natural resources such as plants. Among them, mineral waxes are preferred.

[0209] As waxes of plant origin, for example, rice bran wax, carnauba wax, candelilla wax, etc. can be cited. As petroleum waxes, for example, paraffin wax, microcrystalline wax, their selected special waxes, etc. can be cited, and paraffin wax is preferred. It should be noted that in the present invention, the wax does not include stearic acid.

[0210] It should be noted that as the wax, for example, waxes commercially available from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., etc. can be used. These waxes can be used alone or in combination of two or more.

[0211] (④)Antioxidant

[0212] The rubber composition may contain an antioxidant. The content of the antioxidant is, for example, more than 1 part by mass and less than 10 parts by mass relative to 100 parts by mass of the rubber component.

[0213] There is no particular limitation on the antioxidant, and examples thereof 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'-dimethylxyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD), etc.; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-tert-butyl-4-methylphenol and styrenated phenol; bisphenol-based, triphenol-based, polyphenol-based antioxidants such as tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, 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. They can be used alone or in combination of two or more.

[0214] As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis Co., etc. can be used.

[0215] (⑤) Processing aids

[0216] The rubber composition may contain processing aids. Examples of processing aids include metal salts (compounds in which the hydrogen atoms of an acid are replaced by metal ions), fatty acid amides, amide esters, fatty acid esters, etc. They may be used alone or in combination of two or more. Among them, metal salts and fatty acid amides are preferred, and metal salts are more preferred.

[0217] Examples of the metal used in the metal salt include alkali metals such as potassium and sodium, alkaline earth metals such as calcium and barium, etc. In addition, magnesium, zinc, nickel, molybdenum, etc. can also be used. Among them, alkali metals are preferred.

[0218] Examples of the acid used in the metal salt include fatty acids such as lauric acid, myristic acid, and palmitic acid. In addition, boric acid, carbonic acid, hydrochloric acid, nitric acid, sulfuric acid, etc. can also be used.

[0219] As commercially available products of processing aids, products of Kishida Chemical Co., Ltd., Kenzo Pharmaceutical Co., Ltd., Struktol Company, Performance Additives Company, etc. can be used.

[0220] The content of the processing aid is preferably 1 part by mass or more, more preferably 2 parts by mass or more, relative to 100 parts by mass of the rubber component. As the upper limit, for example, it is preferably 6 parts by mass or less, more preferably 4 parts by mass or less.

[0221] (⑥) Lubricant (stearic acid)

[0222] The rubber composition may contain a lubricant. As the lubricant, a lubricant based on fatty acid derivatives such as stearic acid is preferably used. As stearic acid, commercially available stearic acid can be used. Specifically, products of NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acids Co., Ltd., etc. can be used. In addition, Struktol WB16 manufactured by Struktol Company can also be used.

[0223] The content of stearic acid is preferably more than 0.5 part by mass and less than 10.0 parts by mass relative to 100 parts by mass of the rubber component.

[0224] (⑦) Zinc oxide

[0225] The rubber composition may contain zinc oxide. The content of zinc oxide is, for example, more than 0.5 part by mass and less than 10 parts by mass relative to 100 parts by mass of the rubber component. As zinc oxide, commercially available zinc oxide can be used. Products of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., HAKUSUI TECH Co., Ltd., Sho Do Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0226] (⑧) Crosslinking agent and vulcanization accelerator

[0227] The rubber composition preferably contains a crosslinking agent such as sulfur. The content of the crosslinking agent is, for example, more than 0.1 part by mass and less than 10.0 parts by mass with respect to 100 parts by mass of the rubber component. It should be noted that the content of sulfur is the pure sulfur component, and in the case of using insoluble sulfur, it is the content after removing the oil component.

[0228] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc. that are commonly used in the rubber industry. They can be used alone or in combination of two or more.

[0229] It should be noted that as sulfur, products of, for example, Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Corporation, Flexis, Nippon Karyu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0230] Crosslinking agents other than sulfur can also be used. Specifically, for example, TACKROLV200 manufactured by Tago Chemical Industry Co., Ltd., DURALINK HTS (1,6 - hexamethylene - disodium dithiocarbamate dihydrate) manufactured by Flexis, KA9188 (1,6 - bis(N,N’ - dibenzylthiocarbamoyl disulfide): hybrid crosslinking agent) manufactured by LANXESS, etc., which are sulfur - containing vulcanizing agents, and organic peroxides such as dicumyl peroxide can be used.

[0231] Furthermore, the rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator is, for example, more than 0.3 part by mass and less than 10.0 parts by mass with respect to 100 parts by mass of the rubber component.

[0232] Examples of the vulcanization accelerator include thiazole - based vulcanization accelerators such as 2 - mercaptobenzothiazole, di - 2 - benzothiazolyl disulfide, N - cyclohexyl - 2 - benzothiazolyl sulfenamide; thiuram - based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), tetra(2 - ethylhexyl)thiuram disulfide (TOT - N); sulfenamide - based vulcanization accelerators such as N - cyclohexyl - 2 - benzothiazolyl sulfenamide, N - tert - butyl - 2 - benzothiazolyl sulfenamide, N - ethylene oxide - 2 - benzothiazolyl sulfenamide, N - ethylene oxide - 2 - benzothiazolyl sulfenamide, N,N’ - diisopropyl - 2 - benzothiazolyl sulfenamide; guanidine - based vulcanization accelerators such as diphenylguanidine, di - o - tolylguanidine, o - tolylbiguanide. They can be used alone or in combination of two or more.

[0233] (⑧) Others

[0234] In the rubber composition, in addition to the above components, additives commonly used in the tire industry, such as organic fillers like cellulose fibers, organic peroxides, etc., can be blended as needed. The content of these additives is, for example, more than 0.1 part by mass and less than 50 parts by mass relative to 100 parts by mass of the rubber component.

[0235] It should be noted that in the present invention, various materials containing carbon atoms in the above-mentioned materials (such as rubber, oil, resin, vulcanization accelerator, anti-aging agent, surfactant, etc.) can be derived from carbon dioxide in the atmosphere. As a method for obtaining the blend of the present invention from carbon dioxide, carbon dioxide can be directly converted, or methane obtained through the methanation process of synthesizing methane via carbon dioxide can be converted.

[0236] (⑨) Capping ply cord

[0237] Although not a blending material of the rubber composition, the capping ply cord will also be described. In the present invention, as described above, as the capping ply cord, a single-twist PET capping ply formed by twisting one yarn containing PET fibers is used.

[0238] It should be noted that as the total fineness of the capping ply cord, it is preferably 900 dtex or more and 2500 dtex or less, more preferably 1500 tex or more and 2300 dtex or less.

[0239] Moreover, the thickness (diameter of the cord) is preferably 0.2 mm or more and 0.8 mm or less, more preferably 0.3 mm or more and 0.6 mm or less.

[0240] In addition, the number of cords per 50 mm width, that is, the density, is preferably 40 or more and 80 or less, more preferably 50 or more and 70 or less.

[0241] It should be noted that the fineness, thickness, and density of the above capping ply cord can be measured according to the method specified in JIS L1017:2002.

[0242] After treating the capping ply cord with an adhesive and bonding it to a specified rubber composition for the capping ply, a capping ply can be formed. It should be noted that as the adhesive used in the bonding, for example, EX-313 (glycerol polyglycidyl ether, manufactured by Nagase chemteX Corporation) and RFL (resorcinol-formaldehyde-emulsion) as epoxy compounds can be used.

[0243] It should be noted that as the PET fiber, it can also be PET fiber (recycled PET fiber) obtained by recycling used plastic bottles and other plastic wastes. From the aspect of environmental protection, it is suitable to use such sustainable PET fibers.

[0244] (2) Preparation of Rubber Composition

[0245] The rubber composition can be prepared by a general method, for example, a manufacturing method including a basic kneading step of kneading rubber components and fillers such as silica, and a refining kneading step of kneading the kneaded product obtained in the above basic kneading step and a crosslinking agent.

[0246] Kneading can be carried out using a known (closed type) kneader such as a Banbury mixer, a kneader, an open mill, etc.

[0247] The kneading temperature in the basic kneading step is, for example, more than 50°C and less than 200°C, and the kneading time is, for example, more than 30 seconds and less than 30 minutes. In the basic kneading step, in addition to the above components, compounding agents used in the existing rubber industry, such as softening agents such as oil, stearic acid, zinc oxide, anti-aging agents, waxes, vulcanization accelerators, etc., can be appropriately added as needed and kneaded.

[0248] In the refining kneading step, the kneaded product obtained in the above basic kneading step and a crosslinking agent are kneaded. The kneading temperature in the refining kneading step is, for example, more than room temperature and less than 80°C, and the kneading time is, for example, more than 1 minute and less than 15 minutes. In the refining kneading step, in addition to the above components, vulcanization accelerators, zinc oxide, etc. can be appropriately added as needed and kneaded.

[0249] After that, the obtained rubber composition is extruded into a specified shape, and thus can be formed into a tread.

[0250] 3. Manufacture of Tire

[0251] The tire of this embodiment can be manufactured by a usual method. First, the obtained rubber composition is used to form a specified shape to manufacture a tread. Next, it is combined with other rubber components on a tire molding machine to produce an unvulcanized tire.

[0252] Specifically, on a molding drum, an inner liner layer as a component for ensuring the airtightness of the tire, a carcass as a component for bearing the load, impact, and filling air pressure of the tire, a belt layer component as a component for strongly clamping the carcass and improving the tread rigidity, a crown belt layer, etc. are wound. While fixing both ends of the carcass at both side edges, a bead portion as a component for fixing the tire on a rim is arranged. After forming into a ring shape, by attaching the tread to the central portion of the outer periphery and attaching the sidewall to the radial outside to form a sidewall portion, an unvulcanized tire is produced.

[0253] Then, the tire is obtained by heating and pressing the above-prepared uncured tire in a vulcanizer. The vulcanization process can be carried out by applying known vulcanization means. As the vulcanization temperature, for example, it is 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.

[0254] In the tire obtained above, as described above, by appropriately controlling the product of the diameter (mm) of the cap ply cord and the thickness (mm) of the tread, the effects brought by using the single-twist PET cap ply and the effects brought by the appropriately formed tread act synergistically, and it is possible to improve the comprehensive performance of high-speed durability and rolling resistance.

[0255] Moreover, the tire of the present invention can be suitably used as a passenger car tire, a large passenger car tire, a large SUV tire, a truck-bus tire, a two-wheeled vehicle tire, a racing tire, a studless tire (winter tire), an all-season tire, a run-flat tire, etc., and is particularly preferably used as a passenger car tire.

[0256] Examples

[0257] The following shows examples (Examples) considered to be preferable during implementation, but the scope of the present invention is not limited to these Examples.

[0258] For a tire (tire size: 195 / 65R15) composed of tire components such as a tread, a cap ply, and a belt layer formed from various compounding materials shown below, research was conducted on high-speed durability, rolling resistance, and comprehensive performance. The evaluation results are shown in Table 2.

[0259] 1. Preparation of rubber composition

[0260] Using the various compounding materials shown below, a rubber composition for the tread was prepared.

[0261] (1) Compounding materials

[0262] (a) Rubber components

[0263] (①) NR: TSR20

[0264] (②) SBR-1: Modified S-SBR (styrene content: 25% by mass, vinyl content: 60 mol%, Tg: -24 °C, non-extended oil) manufactured based on Production Example 1 described later

[0265] (③) SBR-2: Modified S-SBR (styrene content: 40% by mass, vinyl content: 35 mol%, Tg: -25 °C, 25% extended oil) manufactured based on Production Example 2 described later

[0266] (④) SBR-3: Modified S-SBR manufactured based on Production Example 3 below (styrene content: 40% by mass, vinyl content: 36 mol%, Tg: -25°C, non-oil-extended)

[0267] (⑤) SBR-4: TUFDENE 3830 manufactured by Asahi Kasei Corporation (S-SBR: styrene content: 33% by mass, vinyl bond content: 31%, 37.5% oil-extended)

[0268] (⑥) BR: UBEPOL BR150B manufactured by Ube Industries, Ltd. (high-cis BR) (cis content: 97%, trans content: 2%, vinyl content: 1%)

[0269] (Production Example 1)

[0270] The above SBR-1 was produced as follows. First, cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into a high-pressure autoclave reactor purged with nitrogen. After adjusting the temperature of the reactor contents, n-butyllithium was added to initiate polymerization. Thereafter, polymerization was carried out under adiabatic conditions. At the moment when the polymerization conversion reached 99%, 1,3-butadiene was added, and polymerization was further carried out for 5 minutes. N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane was added as a modifier for reaction. After the polymerization reaction was completed, 2,6-di-tert-butyl-p-cresol was added, the solvent was removed by stripping, and drying was carried out using a hot roll to obtain SBR-1.

[0271] (Production Example 2)

[0272] The above SBR-2 was obtained in the same manner as in Production Example 1, except that the target styrene content, vinyl content, and Tg were changed and TDAE oil was added.

[0273] (Production Example 3)

[0274] The above SBR-3 was obtained in the same manner as in Production Example 1, except that the target styrene content, vinyl content, and Tg were changed and the modifier was 3-dimethylaminopropyltriethoxysilane.

[0275] (b) Compounding materials other than the rubber component

[0276] (①) Carbon black: DIABLACK N220 manufactured by Mitsubishi Chemical Corporation

[0277] (N2SA: 115 m 2 / g)

[0278] (②) Silica-1: ULTRASIL VN3 manufactured by Evonik Degussa GmbH

[0279] (N2SA: 175 m 2 / g, average primary particle size: 17 nm)

[0280] (③) Silica-2: ULTRASIL 9100GR manufactured by Evonik Degussa

[0281] (N2SA: 235 m 2 / g, average primary particle size: 15 nm)

[0282] (④) Silane coupling agent: NXT manufactured by Momentive

[0283] (3-Octanoylthiopropyltriethoxysilane)

[0284] (⑤) Oil: Processing oil A / OMIX manufactured by Sankyo Yuka Kogyo

[0285] (⑥) Resin: YS resin PX850 manufactured by Yasuhara Chemical

[0286] (Softening point 85 °C, β-pinene resin (terpene resin))

[0287] (⑦) Wax: OZOACE 0355 manufactured by Nippon Seiro

[0288] (⑧) Antioxidant-1: NOCRAC 6C manufactured by Ouchi Shinko Chemical Industry

[0289] (N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine)

[0290] (⑨) Antioxidant-2: ANTAGE RD manufactured by Kawaguchi Chemical Industry

[0291] (Poly(2,2,4-trimethyl-1,2-dihydroquinoline)

[0292] (⑩) Stearic acid: Bead stearic acid "Tsubaki" manufactured by NOF

[0293] Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting

[0294] Sulfur: Powder sulfur manufactured by Karuizawa Sulfur

[0295] Accelerator-1: NOCCELER CZ manufactured by Ouchi Shinko Chemical Industry

[0296] (N-Cyclohexylbenzothiazole-2-sulfenamide)

[0297] Accelerator - 2: NOCCELER D manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0298] (N,N'-Diphenylguanidine)

[0299] (2) Preparation of rubber composition for tread

[0300] Based on the respective ratios of A to C shown in Table 1, using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., materials other than sulfur and vulcanization accelerators were kneaded at 150 °C for 5 minutes to obtain a kneaded product.

[0301] Next, sulfur and vulcanization accelerators were added to the kneaded product, and it was kneaded at 80 °C for 5 minutes using a two-roll mill to obtain rubber compositions for treads with ratios A to C.

[0302] 2. Molding of tire components (tread, crown ply, belt ply)

[0303] (1) Molding of tread

[0304] Next, using the rubber composition obtained above, treads were molded with the respective thicknesses shown in Table 2.

[0305] (2) Molding of crown ply

[0306] Meanwhile, a specified rubber composition for the crown ply was applied to the respective crown ply cords shown in Table 2 to mold each crown ply.

[0307] (3) Molding of belt ply

[0308] Similarly, a specified rubber composition for the belt ply was applied to the respective belt ply cords shown in Table 2 to mold each belt ply.

[0309] 3. Manufacture of tires

[0310] Next, the respective treads, crown plies, and belt plies obtained above were joined together with other tire components to form an unvulcanized tire, which was press-vulcanized at 170 °C for 10 minutes to manufacture the test tires of Examples 1 to 4 and Comparative Examples 1 to 6.

[0311] 4. Performance evaluation test

[0312] (1) High-speed durability evaluation

[0313] Assemble each test tire onto a rim (size = 16×6.0J), fill the tire with air, adjust the internal pressure to 280 kPa, then install it on a drum driving test machine, apply a longitudinal load of 4.22 kN, gradually increase the speed from 200 km / h in increments of 10 km / h, and measure the time and speed until the tire is damaged. Divide the obtained time by the time taken to increase to the next speed, multiply by 10 km / h, and add the obtained value to the obtained speed to calculate the total value.

[0314] Next, set the result in Comparative Example 2 as 100, exponentiate it based on the following formula, and use it as an index for high-speed durability evaluation. The larger the value, the better the durability.

[0315] High-speed durability evaluation = [(result of the test tire) / (result of Comparative Example 2)] × 100

[0316] (2) Evaluation of rolling resistance

[0317] Use a rolling resistance test machine to measure the rolling resistance coefficient (RRC: Rolling Resistance Coefficient) of each test tire when driving on a drum at a speed of 80 km / h under the following conditions.

[0318] Rim used: 16×6.0J

[0319] Internal pressure: 210 kPa

[0320] Load: 4.82 kN

[0321] Next, set the result in Comparative Example 3 as 100, exponentiate it based on the following formula, and use it as an evaluation of rolling resistance. The larger the value, the lower the rolling resistance.

[0322] Rolling resistance evaluation = [(result of Comparative Example 3) / (result of the test tire)] × 100

[0323] (3) Comprehensive evaluation

[0324] Furthermore, sum up the results of (1) and (2) as the comprehensive evaluation.

[0325] Show the evaluation results in Table 2.

[0326] [Table 1]

[0327] (parts by mass) Ratio A Ratio B Ratio C NR 15 - - SBR-1 55 20 - SBR-2 25 - 62.5 SBR-3 - - 40 SBR-4 - 96.25 - BR 10 10 10 Carbon black 5 5 5 Silica-1 55 52 - Silica-2 - - 50 Silane coupling agent 5.5 5.2 5 Oil 8 8 10 Wax 1.5 1.5 1.5 Antioxidant-1 2.5 2.5 2.5 Antioxidant-2 0.8 0.8 0.8 Stearic acid 2 2 2 Zinc oxide 2 2 2 Sulfur 1.5 2.5 2.5 Accelerator-1 2.1 3 3 Accelerator-2 2.1 3 3 Hs 58 58 63 AE 12.5 21.8 17

[0328] [Table 2]

[0329]

[0330] As described above, the present invention has been described based on the embodiments, but the present invention is not limited to the above-described embodiments. Various modifications can be made to the above-described embodiments within the scope identical to and equivalent to the present invention.

[0331] The present invention (1) relates to a tire, which includes:

[0332] a carcass including carcass cords;

[0333] a belt layer including belt cords and disposed radially outside the carcass of the tire;

[0334] a crown belt layer including crown belt cords and disposed radially outside the belt layer of the tire; and

[0335] a tread disposed radially outside the crown belt layer of the tire,

[0336] wherein the tire is characterized in that

[0337] the above-mentioned crown belt cords are formed by twisting one yarn containing polyethylene terephthalate fibers,

[0338] the above-mentioned tread is formed of a rubber composition having an acetone extract component of more than 15% by mass, a thickness of more than 6 mm, and a rubber hardness (Shore hardness) Hs of more than 60,

[0339] the product of the diameter (mm) of the above-mentioned crown belt cords and the thickness (mm) of the above-mentioned tread is less than 5.0.

[0340] The present invention (2) is the tire as described in the present invention (1), characterized in that the thickness of the crown belt cords of the above-mentioned crown belt layer is 0.01 mm or more and 0.05 mm or less.

[0341] The present invention (3) is the tire as described in the present invention (1), characterized in that the total thickness of the above-mentioned crown belt layer is 0.20 mm or more and 0.60 mm or less.

[0342] The present invention (4) is the tire as described in the present invention (1), characterized in that the thickness of the above-mentioned tread is 10 mm or less.

[0343] The present invention (5) is the tire as described in the present invention (1), characterized in that the product of the diameter (mm) of the above-mentioned crown belt cords and the thickness (mm) of the above-mentioned tread is 3.0 or less.

[0344] The present invention (6) is the tire as described in the present invention (1), characterized in that the above-mentioned rubber composition is a rubber composition containing more than 75 parts by mass of silica relative to 100 parts by mass of the rubber component.

[0345] The tire of the present invention (7) as described in the present invention (1) is characterized in that the total fineness of the above-mentioned cap ply cords is 900 dtex or more and 2500 dtex or less.

[0346] The tire of the present invention (8) as described in the present invention (1) is characterized in that the diameter of the above-mentioned cap ply cords is 0.2 mm or more and 0.8 mm or less.

[0347] The tire of the present invention (9) as described in the present invention (1) is characterized in that the number of cords per 50 mm width of the above-mentioned cap ply cords is 40 or more and 80 or less.

[0348] The tire of the present invention (10) as described in the present invention (1) is characterized in that the above-mentioned rubber composition contains vegetable oil.

[0349] The tire of the present invention (11) as described in the present invention (1) is characterized in that the above-mentioned rubber composition contains sustainable carbon black.

[0350] The tire of the present invention (12) as described in the present invention (1) is characterized in that the above-mentioned rubber composition contains sustainable silica.

[0351] The tire of the present invention (13) as described in the present invention (1) is characterized in that the above-mentioned polyethylene terephthalate fiber is a sustainable polyethylene terephthalate fiber.

[0352] Symbol Explanation

[0353] 1 Tire

[0354] 2 Tread

[0355] 3 Sidewall

[0356] 4 Abrasion Protection Part

[0357] 5 Bead

[0358] 6 Innerliner

[0359] 7 Carcass

[0360] 8 Belt

[0361] 9 Filler

[0362] 10 Cap Ply

[0363] CL Equatorial Plane of the Tire

Claims

1. A tire, comprising: A carcass having carcass cords; a belt layer including belt layer cords and arranged on the tire radial direction outer side of the carcass; a cap layer including cap layer cords and disposed on the outer side of the belt layer in the tire radial direction; and A tread, which is arranged on the outer side of the cap layer in the tire radial direction, The tire is characterized by: The cap layer cord is formed by twisting one yarn including polyethylene terephthalate fiber. The tread is formed by using a rubber composition containing an acetone extract component exceeding 15% by mass, having a thickness exceeding 6 mm and a rubber hardness, that is, a Shore hardness Hs exceeding 60, The product of the diameter of the cap layer cord and the thickness of the tread is less than 5.0, in, The unit of the diameter is mm, and the unit of the thickness is mm.

2. The tire according to claim 1, characterized in that The thickness of the cap ply cord of the cap ply is 0.01 mm to 0.05 mm.

3. The tire according to claim 1, characterized in that The total thickness of the cap layer is not less than 0.20 mm and not more than 0.60 mm.

4. The tire according to claim 1, characterized in that The thickness of the tread is 10 mm or less.

5. The tire according to claim 1, characterized in that A product of a diameter of the cap layer cord and a thickness of the tread is 3.0 or less, wherein the unit of the diameter is mm, and the unit of the thickness is mm.

6. The tire according to claim 1, characterized in that The rubber composition contains more than 75 parts by mass of silica per 100 parts by mass of the rubber component.

7. The tire according to claim 1, characterized in that The total fineness of the cap layer cord is 900 dtex or more and 2500 dtex or less.

8. The tire according to claim 1, characterized in that The diameter of the band cord is 0.2 mm or more and 0.8 mm or less.

9. The tire according to claim 1, characterized in that The number of cords of the band ply per 50 mm width is 40 or more and 80 or less.

10. The tire according to claim 1, wherein: The rubber composition contains vegetable oil.

11. The tire according to claim 1, characterized in that The rubber composition contains sustainable carbon black.

12. The tire according to claim 1, characterized in that The rubber composition contains sustainable silica.

13. The tire according to claim 1, characterized in that The polyethylene terephthalate fiber is a sustainable polyethylene terephthalate fiber.

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