Tire

Abstract

The invention provides a tire capable of improving the comprehensive performance of high-speed durability, steering stability 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 polyethylene terephthalate fibers, and the tread is formed so that the thickness exceeds 6 mm and the rubber hardness (Shore hardness) Hs exceeds 60 using a rubber composition comprising 75 parts by mass or more of silica with respect to 100 parts by mass of the rubber component. The product of the diameter (mm) of the cap ply cords and the thickness (mm) of the tread is less than 10.0.

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 Unexamined Patent Application Publication 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, handling stability, 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 radially outside the carcass of the tire;

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

[0013] A tread provided radially outside 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 fibers,

[0016] The above-mentioned tread is formed of a rubber composition containing 75 parts by mass or more of silica with respect to 100 parts by mass of the rubber component, and has a thickness exceeding 6 mm and a rubber hardness (Shore hardness) Hs exceeding 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 10.0.

[0018] Advantages of the Invention

[0019] According to the present invention, it is possible to improve the comprehensive performance of high-speed durability, handling stability, and rolling resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 FIG. is a schematic cross-sectional view of a tire showing an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[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 chafe layer having chafe 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 chafe layer in the tire. Further, the chafe layer cords are formed by twisting one yarn containing polyethylene terephthalate (PET) fibers. In addition, the tread uses a rubber composition (tread rubber composition) containing 75 parts by mass or more of silica with respect to 100 parts by mass of the rubber component, and is formed to have a thickness exceeding 6 mm and a rubber hardness (Shore hardness) Hs exceeding 60. Further, the product of the diameter (mm) of the chafe layer cords and the thickness (mm) of the tread is less than 10.0.

[0025] By having these features, as described later, in a tire using a chafe layer, it is possible to improve the comprehensive performance of high-speed durability, handling stability, 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 a single-twist PET chafe layer

[0029] In the tire of the present invention, the chafe layer cords use a single-twist PET chafe layer formed by twisting one yarn containing PET fibers. The filaments constituting the yarn may be only PET fibers, or may be filaments formed by mixing PET fibers and other fibers (such as polyamide fibers).

[0030] PET fibers are highly elastic compared to nylon 66 (a polyamide synthetic fiber) that has been mainly used heretofore, and can reduce the cord diameter. Therefore, it is considered that the thickness of the chafe layer (cord thickness) and the weight of the chafe layer (cord weight) can be reduced, and a reduction in rolling resistance can be achieved.

[0031] (2) Tread

[0032] However, a tire made of a chafer layer with a reduced cord diameter has poor compression fatigue resistance, so there is a possibility of reducing high-speed durability.

[0033] In order to improve the compression fatigue resistance, it is possible to thicken the tread and reduce the compression on the chafer layer.

[0034] The present inventors further conducted research and found that when a suitable rubber composition, specifically a rubber composition containing 75 parts by mass or more of silica relative to 100 parts by mass of the rubber component, is used for the tread rubber composition, and the tread is formed with a thickness exceeding 6 mm and a rubber hardness (Shore hardness) Hs exceeding 60, while reducing the rolling resistance, it is possible to prevent the compression fatigue of the chafer layer (improve durability), and furthermore, excellent handling stability can be ensured.

[0035] That is, in the tread rubber composition, a large amount of silica having OH groups on the surface is contained in an amount of 75 parts by mass or more relative to 100 parts by mass of the rubber component, whereby hydrogen bonds are generated between the silica surfaces and also interact with the rubber component. Therefore, when driving, it is possible to easily generate and transmit forces inside the rubber. As a result, it is possible to easily transmit the forces generated during turning and ensure excellent handling stability. It should be noted that the content of silica is more preferably 80 parts by mass or more, further preferably 85 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 200 parts by mass or less, more preferably 150 parts by mass or less, further preferably 120 parts by mass or less, further preferably 100 parts by mass or less.

[0036] Moreover, by making the thickness of the tread exceed 6 mm, it is possible to reduce the compression on the chafer layer, so it is possible to improve the compression fatigue resistance and high-speed durability. More preferably, it is 8 mm or more, 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, further preferably 12 mm or less.

[0037] In addition, by increasing the rubber hardness (Shore hardness) Hs of the tread to exceed 60, it is possible to reduce the deformation amount of the tread and the compression applied to the chafer layer, so it is possible to suppress the compression fatigue of the chafer layer and improve the compression fatigue resistance (high-speed durability).

[0038] Furthermore, a tread with a rubber hardness (Shore hardness) Hs exceeding 60 can ensure sufficient rigidity, suppress the deformation of the tread during turning, and easily transmit the generated forces, so it is possible to ensure excellent handling stability.

[0039] 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.

[0040] 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.

[0041] It should be noted that in the above text, the case where the tread is made into a single layer (crown rubber layer) that only forms the ground contact surface has been described. However, it may also be composed of two layers with a base rubber layer provided inside the crown rubber layer, or it may be three layers, or four or more layers. In this case, the above rubber composition for the tread becomes the rubber composition that forms the crown rubber layer, which is the outermost layer on the ground contact surface side, and preferably satisfies the above various parameters.

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

[0043] Here, the thickness of the tread refers to the thickness of the tread on the tire equatorial plane in the radial cross-section of the tire. In the case where the tread is formed of a single rubber composition, it refers to the thickness of this rubber composition. In the case where it is formed of a laminated structure of two or more rubber compositions, it refers to the thickness of the crown rubber layer, which is the outermost layer on the ground contact surface side among these layers. In the cross-section cut out from 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 the "normal rim" refers to the rim specified for each tire in the standard system including the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it refers to the standard rim in the applicable sizes described in the "JATMA YEARBOOK". In the case of ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" described in the "STANDARDS MANUAL". In the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" described in the "YEAR BOOK". Refer to them in the order of JATMA, ETRTO, TRA. When there is an applicable size in the reference, follow that standard. In addition, in the case of a tire not specified in the standard, it refers to the rim that can assemble the rim 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 / tire.

[0045] (3) The product of the diameter (mm) of the cap ply cord and the thickness (mm) of the tread

[0046] The present inventor 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 10.0, the above-mentioned various effects work synergistically, and an improvement in the comprehensive performance of high-speed durability, handling stability, 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 8.00 or less, and further preferably 6.00 or less. As the lower limit, for example, it is preferably 2.00 or more, more preferably 3.00 or more, and further preferably 4.00 or more.

[0047] It should be noted that in the above text, regarding the "diameter of the cap ply cord", it refers to the diameter in the case where the circumscribed circle of the cross-section perpendicular to the extension direction of the cord is a perfect circle, and in the case of an ellipse or the like, it refers to the equivalent circle diameter (the diameter of a circle assuming the same cross-sectional area as a perfect circle). The same applies to the "diameter of the belt ply cord" described later.

[0048] [2] More preferred embodiments of the tire of the present invention

[0049] The tire of the present invention can achieve greater effects by adopting the following methods.

[0050] 1. Belt ply cord

[0051] 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, it is preferably composed of 1 or more and 4 or less filaments. It can be an untwisted 1×1 structure, a single-twisted 1×4 structure, or a layer-twisted 2+2 structure.

[0052] In addition, the number of cords (density) per 50 mm width in the tire width direction is preferably 20 or more, and more preferably 30 or more. It should be noted that as the upper limit, for example, it is preferably 60 or less, and more preferably 50 or less.

[0053] 2. Particle size of silica

[0054] As described above, in the present invention, the tread rubber composition contains silica. At this time, if the particle size (average primary particle size) of the silica is too small, the processability deteriorates. Therefore, it is preferable to use silica with a particle size exceeding 8 nm. More preferably, it is 9 nm or more, and further preferably 10 nm or more. On the other hand, from the aspect of ensuring the reinforcement of the rubber and ensuring the handling stability 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.

[0055] 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 through a transmission or scanning electron microscope. More than 400 primary particles of silica observed in the field of view are measured, and the average value is obtained therefrom.

[0056] Specifically, silica taken out from the rubber composition cut out from a tire is directly observed using an electron microscope or the like, 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.

[0057] 3. Resin component

[0058] In addition, the rubber composition forming the tread preferably contains a resin component.

[0059] By containing a resin component in the rubber composition, the grounding property to the road surface is improved by the adhesiveness of the resin component, and therefore it is considered that the rolling resistance at the start can be further improved.

[0060] As a preferred resin component, preferably the rosin resin, styrene resin, benzofuran resin, terpene resin, C5 resin, C9 resin, C5C9 resin, acrylic resin, etc. described later are preferred. Among them, styrene 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.

[0061] [3] Embodiment

[0062] Hereinafter, the present invention will be specifically described based on the embodiment.

[0063] 1. Tire of the present embodiment

[0064] Figure 1 is a schematic cross-sectional view for explaining the tire of the present embodiment. Figure 1 In, the up-down direction is the radial direction of the tire, the left-right direction is the rotation 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, 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 therefore Figure 1 1 / 4 of the entire tire is shown in.

[0065] As Figure 1As 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 inner liner 6, a carcass 7, a belt layer 8, a pair of fillers 9, and a cap ply 10. The carcass 7, the belt layer 8, the cap ply 10, and the tread 2 are arranged from the inner side to the outer side in the tire radial direction.

[0066] With such a configuration, as described above, as the cap ply cord, a cap ply cord obtained by twisting one 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, it is considered that an improvement in the comprehensive performance of high-speed durability, handling stability, and rolling resistance can be achieved.

[0067] 2. Rubber composition for tread

[0068] 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, and a resin material.

[0069] (1) Compounding materials

[0070] (a) Rubber component

[0071] 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.

[0072] (①) SBR

[0073] 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 structure identification (measurement of styrene content and vinyl content) of SBR can be performed using, for example, a device of the JNM-ECA series manufactured by JEOL Ltd.

[0074] The SBR is not particularly limited, and for example, emulsion polymerization styrene-butadiene rubber (E-SBR), solution polymerization 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. 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.

[0075] As the modified SBR, an SBR having a functional group that interacts with a filler such as silica is preferred. Examples include a terminal-modified SBR obtained by modifying at least one terminal of SBR with a compound (modifying agent) having the above functional group (a terminal-modified SBR having the above functional group at the terminal); a main-chain modified SBR having the above functional group in the main chain; a main-chain and terminal modified SBR having the above functional group in the main chain and at the terminal (for example, a main-chain and terminal modified SBR having the above functional group in the main chain and modifying at least one terminal with the above modifying agent); a terminal-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.

[0076] Examples of the above functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a ureido group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a thioether group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazino group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, etc. It should be noted that these functional groups can have substituents.

[0077] In addition, as the modified SBR, for example, an SBR modified with a compound (modifying agent) represented by the following formula can be used.

[0078] [Chemical formula 1]

[0079]

[0080] 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 siloxy 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. R 4 and R 5 can be bonded to form a ring structure together with the nitrogen atom. n represents an integer.

[0081] As the modified SBR modified with the compound (modifying agent) 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 Application Laid-Open No. 2010-111753, etc.) can be used.

[0082] 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 bond 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) and aryloxy groups (such as phenoxy and benzyloxy).

[0083] Specific examples of the above modifying agent 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.

[0084] 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; polyepoxides such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; tertiary amines containing epoxy groups 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; acyl chlorides containing amino groups 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 amino groups and / or substituted amino groups 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 amino groups and / or substituted amino groups 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.;

[0085] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., ENEOS Materials Co., Ltd., Asahi Kasei Corporation, Zeon Corporation, etc. can be used. It should be noted that the SBR can be used alone or in combination of two or more kinds.

[0086] 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.

[0087] (②) Isoprene rubber

[0088] 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.

[0089] 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 modified NR, deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. can be cited. As modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. can be cited. As 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.

[0090] 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.

[0091] (③) BR

[0092] The weight-average molecular weight of BR is, for example, more than 100,000 and less than 2 million. 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 content 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 spectroscopy.

[0093] 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 modified BR, for example, BR modified with a compound (modifying agent) represented by the following formula can be used.

[0094] [Chemical formula 2]

[0095]

[0096] 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 a nitrogen atom. n represents an integer.

[0097] 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.

[0098] 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 a nitrogen atom, it is preferably a 4- to 8-membered ring. It should be noted that the alkoxy group also includes a cycloalkoxy group (such as cyclohexyloxy) and an aryloxy group (such as phenoxy and benzyloxy).

[0099] As specific examples of the above modifier, 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. can be mentioned. They can be used alone or in combination of two or more.

[0100] In addition, as the modified BR, 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, 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, polyepoxidized liquid polybutadiene; tertiary amines containing epoxy groups such as 4,4'-diglycidyl-diphenylmethylamine, 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl-o-toluidine, tetraglycidyl-m-xylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, tetraglycidyl-1,3-bis(aminomethyl)cyclohexane and other diglycidylamino compounds; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamoyl chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamoyl chloride, N,N-diethylcarbamoyl chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidoxypropyl)-tetramethyldisiloxane, (3-glycidoxypropyl)-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, (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide; N-substituted aziridine compounds such as aziridine, propyleneimine; alkoxysilanes such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltriethoxysilane;(Thio)benzophenone compounds having amino groups and / or substituted amino groups 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 amino groups and / or substituted amino groups 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-methylenebis-(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.

[0101] As the BR, products of, for example, Ube Industries, Ltd., ENEOS Materials Co., Ltd., Asahi Kasei Corporation, Nippon Zeon Co., Ltd. can be used.

[0102] 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.

[0103] (④) Other rubber components

[0104] In the rubber composition, as other rubber components, rubber (polymers) commonly used in the manufacture of tires such as nitrile rubber (NBR) may be included as needed.

[0105] 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.

[0106] The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples thereof 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.

[0107] The method for manufacturing recycled monomers is not particularly limited, and examples thereof include synthesis from recycled naphtha obtained by decomposing rubber products such as tires. In addition, the method for manufacturing recycled naphtha is not particularly limited. For example, rubber products such as tires can be decomposed under high temperature and high pressure, or can be decomposed by microwaves, or can be extracted after mechanical pulverization.

[0108] 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. Biomass is not particularly limited, and examples thereof include agricultural and forestry products, sugars, woods, plant residues after obtaining useful components, ethanol derived from plants, biomass naphtha, etc. The monomers derived from biomass (biomass monomers) are not particularly limited, and examples thereof include butadiene derived from biomass, aromatic vinyl monomers derived 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 thereof 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.

[0109] As a polymer synthesized from biomass monomer components (biomass polymer), there is no particular limitation, and examples include polybutadiene rubber synthesized from butadiene derived from biomass, aromatic vinyl monomer / butadiene copolymers synthesized from butadiene derived from biomass and / or aromatic vinyl monomers derived from biomass, and the like. 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 mentioned.

[0110] 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.

[0111] pMC refers to the 14 ratio of the 14 C concentration of the sample to the

[0112] 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. 23 In 1 mole (6.02×10 11 ), there are about one trillionth of ordinary carbon atoms, that is, about 6.02×10 14 14 C. 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 and the like are taken in and immobilized by plants and the like, it is considered that in fossil fuels such as coal, oil, and natural gas that have passed more than 226,000 years, all 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

[0113] 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 earth's atmospheric environment 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 -12 ​Values around mol%. Therefore, by using the difference between these values, the proportion (biomass proportion) of the compound (from biomass resources) from natural resources in a certain compound (rubber) can be calculated.

[0114] 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 (the radioactive intensity of [[[]] 14 C per 1 g of carbon) is separated into each carbon isotope, corrected to a certain value for [[[]] 13 C, 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.

[0115] Therefore, if rubber is made from a substance 100% from biomass (natural system), even with geographical differences, etc., it usually does not become 100 under normal conditions at present, so it shows a value of about 110 pMC or so. On the other hand, for chemical substances 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.

[0116] 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, for rubber compositions.

[0117] (b) Blending materials other than rubber components

[0118] (①) Filler

[0119] The rubber composition contains silica as a reinforcing agent, but other fillers such as carbon black, 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.

[0120] As the compounding amount of the filler, relative to 100 parts by mass of the rubber component, first, as described above, the silica is 75 parts by mass or more, 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.

[0121] (i) Silica

[0122] As described above, since silica has OH groups on its surface, by containing a large amount of 75 parts by mass or more, hydrogen bonds are generated between the silica surfaces and it also interacts with the rubber component. Therefore, it is possible to easily generate and transmit force inside the rubber during driving, and it is possible to easily transmit the force 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.

[0123] 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 N2SA value measured by the BET method in accordance with ASTM D3037-93.

[0124] There is no particular limitation on the silica, and for example, silica prepared by the dry method (anhydrous silica), silica prepared by the wet method (hydrous silica), etc., which are commonly used in the tire industry, can be used. As commercially available products, products of Evonik Industries, Rhodia, Tosoh Silica Corporation, Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0125] There is no particular limitation on the raw material of silica. For example, it can be a raw material from mineral sources such as quartz, or a raw material from biological sources such as rice husks (for example, silica using biomass materials such as rice husks as raw materials), and silica recycled 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.

[0126] 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 resulting silica precipitate produced by reacting with sulfuric acid is filtered, washed with water, dried, and pulverized in the same manner as existing wet silica, whereby it can be obtained.

[0127] Silica recycled from products containing silica (recycled silica) can be, 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 recycled from semiconductor and other electronic components or tires is preferred.

[0128] 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 Unexamined Patent Application Publication No. 2009-2594, Akita Prefectural University Online Journal B / 2019, vol. 6, p. 216-222, etc.).

[0129] Amorphous silica extracted from rice husks can use commercially available amorphous silica such as that from Wilmar Corporation.

[0130] 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 (sustainability), it is suitable to use sustainable silicas such as biomass silica and recycled silica.

[0131] As described above, the content of silica relative to 100 parts by mass of the rubber component is 75 parts by mass or more, more preferably 80 parts by mass or more, and 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.

[0132] (ii) Silane coupling agent

[0133] 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.

[0134] 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 compounds, vinyltriethoxysilane, vinyltrimethoxysilane and other vinyl compounds, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane and other amino compounds, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and other glycidoxy compounds, 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane and other nitro compounds, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane and other chlorine 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.

[0135] 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.

[0136] 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.

[0137] (iii) Carbon black

[0138] Carbon black is preferably used for the purpose of improving the crack growth resistance, durability, ultraviolet degradation resistance, etc. of the tire.

[0139] 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.

[0140] 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 of 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.

[0141] 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 carbonblack); acetylene black (Acetylene carbon black); thermal carbon black such as FT and MT (Thermalcarbon 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.

[0142] 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.

[0143] In addition, the carbon black can be manufactured by combustion such as the furnace method, by hydrothermal carbonization (HTC), or by pyrolysis of methane based on the thermal carbon black method, etc.

[0144] 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.

[0145] 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.

[0146] (iv) Other fillers

[0147] 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.

[0148] (②) Softener component

[0149] In the rubber composition, considering the proper dispersion of the powder materials during mixing, a softener component is preferably used as needed. It should be noted that the softener plasticizer component here refers to a material that imparts plasticity to the rubber component, and is a concept that includes both softeners that are liquid at 25°C and softeners that are solid at 25°C.

[0150] Examples of softeners include resin components, oils, liquid polymers, ester plasticizers, etc. These softeners 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 or non-rubber products. In addition, low-molecular-weight hydrocarbon components obtained by pyrolysis and extraction of used tires or products containing various components can also be used as softeners, among which softeners derived from biomass or recycled ones are preferably used as sustainable softeners.

[0151] It should be noted that these softeners 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.

[0152] (i) Oil

[0153] As the oil, for example, mineral oil, vegetable oil, animal oil, etc. can be cited. In addition, from the aspect of life cycle assessment, oil refined from waste oil used in a rubber mixer or an engine, or waste cooking oil used in a cooking shop can also be used.

[0154] (i-1) Mineral oil

[0155] Mineral oil refers to 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.

[0156] 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.

[0157] In addition, for environmental countermeasures, 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.

[0158] As commercially available mineral oil, for example, paraffinic, aromatic, naphthenic, etc. oils can be cited, and products of Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, OLISOY Company, H&R Company, Toyokuni Oil Co., Ltd., Showa Shell Sekiyu KK, Fuji Kogyo Co., Ltd., etc. can be used. They can be used alone or in combination of two or more.

[0159] (i-2) Vegetable oil

[0160] As vegetable oil, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran 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.

[0161] In addition, as vegetable oils, refined oils (such as salad oil) obtained by refining 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 being used as edible oils, etc. may also be mentioned. 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.

[0162] As vegetable oils, acylglycerols are preferably included, and triacylglycerols are more preferably included. It should be noted that acylglycerol refers to a compound in which the hydroxyl group of glycerol forms an ester bond with a fatty acid. As acylglycerol, there is no particular limitation, and it can be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. In addition, acylglycerol can be a monomer, a dimer, or a polymer 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, acylglycerol can be liquid or solid at normal temperature (25°C).

[0163] As a method for confirming whether an acylglycerol is 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 containing 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 speculated 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 acylglycerol is contained. It should be noted that "around" here refers to the range of ±0.10 ppm.

[0164] 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, polyvalent unsaturated fatty acids such as linoleic acid and linolenic acid can be mentioned. In addition, as saturated fatty acids, butyric acid, lauric acid, etc. can be mentioned.

[0165] 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 included, 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.

[0166] 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, H&R, Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group, Ltd. etc. can be used.

[0167] (ii) Liquid rubber

[0168] Liquid rubber refers to a polymer that is in a liquid state at normal temperature (25 °C), and 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.

[0169] Farnesene-based polymers refer to polymers obtained by polymerizing farnesene and having a structural unit 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.

[0170] 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).

[0171] 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.

[0172] The weight-average molecular weight (Mw) in terms of polystyrene 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 value in terms of polystyrene measured by gel permeation chromatography (GPC).

[0173] As the liquid rubber, products of KURARAY Co., Ltd., Cray Valley, etc. can be used.

[0174] (iii) Resin component

[0175] The resin component also functions as an adhesion - imparting component and 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 modifying groups capable of reacting with silica, etc. as required.

[0176] 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.

[0177] 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 each styrene - based monomer (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.

[0178] As the above - mentioned other monomers, examples include acrylonitrile - based compounds such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acid - based compounds such as acrylic acid and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, diene - based compounds such as chloroprene, butadiene, and isoprene, olefin - based compounds such as 1 - butene and 1 - pentene; α,β - unsaturated carboxylic acids or their acid anhydrides such as maleic anhydride; etc.

[0179] Among benzofuran - based resins, benzofuran - indene resins are preferred. Benzofuran - indene resins are resins containing benzofuran and indene as monomer components constituting the resin skeleton (main chain). As monomer components contained in the skeleton other than benzofuran and indene, styrene, α - methylstyrene, methyl indene, vinyltoluene, etc. can be cited.

[0180] The hydroxyl value (OH value) of the coumarone indene resin is, for example, more than 15 mgKOH / g and less than 150 mgKOH / g. The OH value refers to the amount of potassium hydroxide required to neutralize acetic acid bonded to the hydroxyl group when 1 g of the resin is acetylated, expressed in milligrams, and is a value measured by potentiometric titration (JIS K 0070: 1992).

[0181] The softening point of the coumarone indene resin is, for example, higher than 30° C. and lower than 160° C. The softening point is a softening point specified in JIS K 6220-1:2001 and measured using a ring and ball softening point measuring apparatus, and is a temperature at which a ball falls.

[0182] Examples of terpene resins include polyterpenes, terpene phenols, and aromatic modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenated products. Terpene compounds are composed of (C5H8) n The hydrocarbons and their oxygenated derivatives are classified as monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ) and the like as a basic skeleton, for example, α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, etc. can be mentioned.

[0183] 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 such 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 such 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.

[0184] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction. As the C5 fraction, 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.

[0185] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, or a resin obtained by hydrogenating or modifying them. As the C9 fraction, 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 resins 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 a homopolymer of styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred. As aromatic vinyl resins, for example, aromatic vinyl resins commercially available from companies such as KRATON and Eastman Chemical can be used.

[0186] "C5C9 resin" refers to a resin obtained by copolymerizing the above-mentioned C5 fraction and the above-mentioned C9 fraction, or a resin obtained by hydrogenating or modifying them. As the C5 fraction and the C9 fraction, 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.

[0187] The acrylic resin is not particularly limited, and for example, a solvent-free acrylic resin can be used.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] (③) Wax

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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 Corporation, etc. can be used. These waxes can be used alone or in combination of two or more.

[0198] (④)Antioxidant

[0199] 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.

[0200] There is no particular limitation on the antioxidant, and examples thereof include naphthylamine antioxidants such as phenyl-α-naphthylamine; diphenylamine antioxidants such as octylated diphenylamine, 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine 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); quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-tert-butyl-4-methylphenol, styrenated phenol; bisphenol, triphenol, polyphenol antioxidants such as tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, p-phenylenediamine antioxidants and quinoline antioxidants are preferred, and 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.

[0201] As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis Corporation, etc. can be used.

[0202] (⑤)Processing aids

[0203] The rubber composition may contain processing aids. Examples of the 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.

[0204] 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.

[0205] Examples of the acid used in the metal salt include fatty acids such as lauric acid, myristic acid, palmitic acid, etc. In addition, boric acid, carbonic acid, hydrochloric acid, nitric acid, sulfuric acid, etc. can also be used.

[0206] As commercially available products of the processing aids, products of Kishida Chemical Co., Ltd., Ken-Ei Pharmaceutical Co., Ltd., Struktol Company, Performance Additives Company, etc. can be used.

[0207] The content of the processing aids 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.

[0208] (⑥)Lubricant (stearic acid)

[0209] 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 the stearic acid, conventionally known stearic acid can be used. Specifically, products of Nippon Oil Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acid Co., Ltd., etc. can be used. In addition, Struktol WB16 manufactured by Struktol Company can also be used.

[0210] 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.

[0211] (⑦)Zinc oxide

[0212] The rubber composition may contain zinc oxide. The content of zinc oxide is, for example, more than 0.5 parts by mass and less than 10 parts by mass relative to 100 parts by mass of the rubber component. As the zinc oxide, publicly known zinc oxides can be used, and products of, for example, Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., HAKUSUI TECH Co., Ltd., Shoindo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0213] (⑧) Crosslinking agent and vulcanization accelerator

[0214] The rubber composition preferably contains a crosslinking agent such as sulfur. The content of the crosslinking agent is, for example, more than 0.1 parts by mass and less than 10.0 parts by mass relative 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.

[0215] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. They can be used alone or in combination of two or more.

[0216] It should be noted that as sulfur, products of, for example, Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis Co., Ltd., Nippon Karyu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0217] 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 Co., Ltd., KA9188 (1,6 - bis(N,N’ - dibenzylthiocarbamoyl disulfide): hybrid crosslinking agent) manufactured by LANXESS Co., Ltd., etc., sulfur - atom - containing vulcanizing agents, organic peroxides such as dicumyl peroxide, etc. can be used.

[0218] Moreover, the rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator is, for example, more than 0.3 parts by mass and less than 10.0 parts by mass relative to 100 parts by mass of the rubber component.

[0219] As vulcanization accelerators, thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, bis(2-benzothiazolyl) disulfide, and N-cyclohexyl-2-benzothiazolesulfenamide can be cited; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetra(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazolesulfenamide, N-tert-butyl-2-benzothiazolesulfenamide, N-oxydiethylene-2-benzothiazolesulfenamide, N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-o-tolylguanidine, and o-tolylbiguanide. They can be used alone or in combination of two or more.

[0220] (⑧) Others

[0221] In the rubber composition, in addition to the above components, additives commonly used in the tire industry, such as organic filler materials such as cellulose fibers and organic peroxides, 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.

[0222] 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 a methanation process for synthesizing methane from carbon dioxide can be converted.

[0223] (⑨) Cordon ply cord

[0224] Although not a blending material for the rubber composition, the cordon ply cord will also be described. In the present invention, as described above, as the cordon ply cord, a single-twist PET cordon ply formed by twisting one yarn containing PET fibers is used.

[0225] It should be noted that the total fineness of the cordon ply cord is preferably 900 dtex or more and 2500 dtex or less, more preferably 1500 tex or more and 2300 dtex or less.

[0226] 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.

[0227] In addition, the number of cords (density) per 50 mm width in the tire width direction is preferably 40 or more and 80 or less, more preferably 50 or more and 70 or less.

[0228] It should be noted that the fineness, thickness, and density of the above-mentioned cord of the breaker ply can be measured according to the methods specified in JIS L1017:2002.

[0229] After treating the cord of the breaker ply with an adhesive and bonding it to the specified rubber composition for the breaker ply, a breaker 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-latex), etc., which are epoxy compounds, can be used.

[0230] It should be noted that as the PET fiber, it can also be a PET fiber (recycled PET fiber) obtained by recycling used plastic bottles and other plastic wastes. From the aspect of environmental protection, such sustainable PET fibers are suitable for use.

[0231] (2) Preparation of the rubber composition

[0232] The rubber composition can be prepared by a general method, for example, a manufacturing method including a basic kneading process of kneading rubber components and fillers such as silica, and a refining kneading process of kneading the kneaded product obtained in the above basic kneading process and a crosslinking agent.

[0233] Kneading can be carried out using a known (closed type) kneading machine such as a Banbury mixer, a kneader, or an open mill.

[0234] The kneading temperature in the basic kneading process 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 process, in addition to the above components, compounding agents used in the existing rubber industry, such as softeners such as oil, stearic acid, zinc oxide, anti-aging agents, wax, vulcanization accelerators, etc., can be appropriately added as needed and kneaded.

[0235] In the refining kneading process, the kneaded product obtained in the above basic kneading process and the crosslinking agent are kneaded. The kneading temperature in the refining kneading process 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 process, in addition to the above components, vulcanization accelerators, zinc oxide, etc., can be appropriately added as needed and kneaded.

[0236] After that, the above-obtained rubber composition is extruded and processed into a specified shape, and thus it can be formed into a tread.

[0237] 3. Manufacture of the tire

[0238] The tire of the present embodiment can be manufactured by a conventional method. First, using the rubber composition obtained above, it is molded into a prescribed shape to manufacture a tread. Next, together with other rubber components, it is assembled on a tire molding machine to produce an unvulcanized tire.

[0239] 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 inflation pressure of the tire, a belt layer component as a component for strongly clamping the carcass and improving the tread rigidity, a crown ply, etc. are wound. While fixing both ends of the carcass at both side edges, a bead portion as a component for fixing the tire to a rim is arranged. After being molded into a ring shape, by attaching the tread to the central portion of the outer periphery and attaching the sidewall to the radially outer side to form a sidewall portion, an unvulcanized tire is produced.

[0240] Then, the tire is obtained by heating and pressurizing the unvulcanized tire manufactured above in a vulcanizer. The vulcanization process can be carried out by applying known vulcanization means. As the vulcanization temperature, for example, it exceeds 120°C and is less than 200°C, and the vulcanization time, for example, exceeds 5 minutes and is less than 15 minutes.

[0241] In the tire obtained above, as described above, by appropriately controlling the product of the diameter (mm) of the crown ply cord and the thickness (mm) of the tread, the effects brought by using a single-twist PET crown ply tape and the effects brought by an appropriately formed tread act synergistically, and an improvement in the comprehensive performance of high-speed durability, handling stability, and rolling resistance can be achieved.

[0242] 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-wheeler 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.

[0243] Examples

[0244] The following shows examples (examples) considered to be preferable during implementation, but the scope of the present invention is not limited to these examples.

[0245] Regarding a tire (tire size: 195 / 65R15) composed of a tread and tire components such as a crown ply and a belt layer formed from various compounding materials shown below, studies were conducted, and the results calculated based on the evaluation methods described later regarding high-speed durability, handling stability, rolling resistance, and comprehensive performance are shown together in the lower part of Table 2.

[0246] 1. Preparation of rubber composition

[0247] Using the various compounding materials shown below, a rubber composition for the tread was prepared.

[0248] (1) Blended material

[0249] (a) Rubber component

[0250] (①) NR: TSR20

[0251] (②) SBR-1: Modified S-SBR (styrene content: 25% by mass, vinyl content: 63 mol%, Tg: -20°C, non-oil-extended) manufactured based on Production Example 1 described below

[0252] (③) SBR-2: Modified S-SBR (styrene content: 24% by mass, vinyl content: 59 mol%, Tg: -25°C, non-oil-extended) manufactured based on Production Example 2 described below

[0253] (④) SBR-3: HPR840 (modified S-SBR, styrene content: 10% by mass, vinyl content: 42 mol%, Tg: -60°C, non-oil-extended) manufactured by ENEOS Materials Co., Ltd.

[0254] (⑤) BR-1: BR730 (cis content: 96% by mass, trans content: 3% by mass, vinyl content: 1% by mass) manufactured by ENEOS Materials Co., Ltd.

[0255] (⑥) BR-2: ASAPREN N103 (cis content: 38% by mass, Tg: -90°C) manufactured by Asahi Kasei Corporation

[0256] (⑦) BR-3: BR360B (cis content: 97% by mass, trans content: 1% by mass, vinyl content: 2% by mass) manufactured by Ube Industries, Ltd.

[0257] (Production Example 1)

[0258] 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, and the solvent was removed by stripping and dried by a hot roll to obtain SBR-1.

[0259] (Production Example 2)

[0260] The above SBR-2 was obtained in the same manner as in Production Example 1, except that the target styrene content, vinyl content, Tg were changed, and the modifier was 3-dimethylaminopropyltriethoxysilane.

[0261] (b) Compounding materials other than the rubber component

[0262] (①) Carbon black: DIABLACK N220 manufactured by Mitsubishi Chemical Corporation

[0263] (N2SA: 115 m2 / g)

[0264] (②) Silica: ULTRASIL VN3 manufactured by Evonik Industries

[0265] (N2SA: 175 m2 / g, average primary particle size: 17 nm)

[0266] (③) Silane coupling agent: NXT manufactured by Momentive

[0267] (3-octanoylthiopropyltriethoxysilane)

[0268] (④) Oil: Processing oil A / OMIX manufactured by Sankyo Yuka Kogyo Co., Ltd.

[0269] (⑤) Resin: YS resin PX850 manufactured by Yasuhara Chemical Co., Ltd.

[0270] (Softening point 85°C, β-pinene resin (terpene resin))

[0271] (⑥) Wax: OZOACE 0355 manufactured by Nippon Seiro Co., Ltd.

[0272] (⑦) Anti-aging agent - 1: NOCRAC 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0273] (N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine)

[0274] (⑧) Anti-aging agent - 2: ANTAGE RD manufactured by Kawaguchi Chemical Industry Co., Ltd.

[0275] (Poly(2,2,4-trimethyl-1,2-dihydroquinoline)

[0276] (⑨) Anti-aging agent - 3: Sirantech S-TMQ manufactured by Sennics

[0277] (Poly(2,2,4-trimethyl-1,2-dihydroquinoline)

[0278] (⑩) Processing aid - 1: NOCCELER CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0279] (N-cyclohexylbenzothiazole-2-sulfenamide)

[0280] Processing aid - 2: NOCCELER D manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0281] (1,3-diphenylguanidine (DPG))

[0282] Processing aid - 3: NOCCELER M-P manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0283] (2-mercaptobenzothiazole)

[0284] Stearic acid: Bead stearic acid "Tsubaki" manufactured by NOF Corporation

[0285] Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd.

[0286] Sulfur: Powder sulfur manufactured by Karuizawa Sulfur Co., Ltd.

[0287] Accelerator - 1: Sanceler CM-G manufactured by Sanshin Chemical Industry Co., Ltd.

[0288] (N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)

[0289] Accelerator - 2: SOXINOL DG manufactured by Sumitomo Chemical Co., Ltd.

[0290] (1,3-diphenylguanidine (DPG)

[0291] Accelerator - 3: SUNSINE MBT manufactured by Shandong Shangshun Chemical Co., Ltd.

[0292] (2-mercaptobenzothiazole)

[0293] (2) Preparation of the tread rubber composition

[0294] Based on the respective ratios of A to C shown in Table 1, using a 1.7 L 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.

[0295] Next, sulfur and vulcanization accelerators were added to the kneaded product, and it was kneaded at 80 °C for 5 minutes using an open mill to obtain the tread rubber compositions of ratios A to C.

[0296] 2. Molding of tire components (tread, cap ply, belt ply)

[0297] (1) Molding of the tread

[0298] Next, using the rubber composition obtained above, the tread (tread running surface) is molded to each thickness shown in Table 2.

[0299] (2) Molding of the cap ply

[0300] Meanwhile, the specified rubber composition for the cap ply is applied to each cap ply cord shown in Table 2, and each cap ply is molded.

[0301] (3) Molding of the belt ply

[0302] Similarly, the specified rubber composition for the belt ply is applied to each belt ply cord shown in Table 2, and each belt ply is molded.

[0303] 3. Manufacture of tires

[0304] Next, the obtained treads, cap plies, belt plies and other tire components are joined together to form an unvulcanized tire, which is then pressure-vulcanized at 170 °C for 10 minutes to manufacture the test tires of Examples 1 to 4 and Comparative Examples 1 to 3.

[0305] 4. Performance evaluation test

[0306] (1) Evaluation of rolling resistance

[0307] Using a rolling resistance testing machine, the rolling resistance coefficient (RRC: Rolling Resistance Coefficient) of each test tire is measured when it travels on a drum at a speed of 80 km / h under the following conditions.

[0308] Rim used: 15×6J

[0309] Internal pressure: 210 kPa

[0310] Load: 4.35 kN

[0311] Next, taking the result of Comparative Example 3 as 100, it is indexed based on the following formula for rolling resistance evaluation. The larger the value, the lower the rolling resistance.

[0312] Rolling resistance evaluation = [(Result of Comparative Example 3) / (Result of test tire)] × 100

[0313] (2) Evaluation of handling stability

[0314] Install each test tire on all the wheels of a vehicle (a domestic FR vehicle with a displacement of 2000 cc). Twenty test drivers respectively give a sensory evaluation of the handling stability when driving around at a speed of over 70 km / h on a test track on a scale of 1 to 10 (the larger the value, the better), and calculate the total score.

[0315] Next, set the result in Comparative Example 2 as 100, and perform indexation based on the following formula as the evaluation of handling stability. The larger the value, the more excellent the handling stability during high-speed driving.

[0316] Handling stability evaluation = [(result of the test tire) / (result of Comparative Example 2)] × 100

[0317] (3) High-speed durability evaluation

[0318] Assemble each test tire onto a wheel rim (size = 15 × 6J), fill the tire with air, adjust the internal pressure to 230 kPa, then install it on a drum driving test machine, apply a longitudinal load of 5.88 kN, and gradually increase the speed from 210 km / h in steps of 10 km / h, and measure the time until the tire is damaged.

[0319] Next, set the result in Comparative Example 3 as 100, and perform indexation based on the following formula as an index for evaluating high-speed durability. The larger the value, the longer the time until damage, indicating the more excellent durability after driving. High-speed durability evaluation = [(result of the test tire) / (result of Comparative Example 3)] × 100

[0320] (4) Comprehensive evaluation

[0321] And sum up (1) to (3) as the comprehensive evaluation.

[0322] [Table 1]

[0323] (parts by mass) Ratio A Ratio B Ratio C NR 40 40 11.15 SBR-1 - 34.3 - SBR-2 - - 46.31 SBR-3 - - 11.58 BR-1 48 - - BR-2 12 - - BR-3 - 25.7 30.96 Carbon black 5 5 15 Silica 60 80 75 Silane coupling agent 4.8 6.4 6 Oil 22 37 20 Resin 7.9 14 7 Wax 1.4 2.06 1.93 Antioxidant-1 1.7 3.22 2.42 Antioxidant-2 0.5 1.04 - Antioxidant-3 - - 0.96 Processing aid-1 1.5 2 - Processing aid-2 0.5 0.74 - Processing aid-3 - - 2 Stearic acid 4 3 2 Zinc oxide 2 2.2 2 Sulfur 1.25 1.4 1.6 Accelerator-1 1 2.2 2 Accelerator-2 1.6 1.6 1.7 Accelerator-3 0.2 - - Hs 50 55 65

[0324] [Table 2]

[0325]

[0326] The present invention has been described based on the embodiments, but the present invention is not limited to the above embodiments. Various changes can be made to the above embodiments within the same and equivalent scope as the present invention.

[0327] The present invention (1) relates to a tire, which has:

[0328] A carcass that has carcass cords;

[0329] A belt layer that has belt layer cords and is provided radially outside the tire of the above carcass;

[0330] A crown ply, which includes crown ply cords and is disposed on the radially outer side of the belt ply in the tire; and

[0331] A tread, which is disposed on the radially outer side of the crown ply in the tire,

[0332] The tire is characterized in that

[0333] the crown ply cords are formed by twisting one yarn containing polyethylene terephthalate fibers,

[0334] the tread is formed of a rubber composition containing 75 parts by mass or more of silica relative to 100 parts by mass of the rubber component, and has a thickness exceeding 6 mm and a rubber hardness (Shore hardness) Hs exceeding 60,

[0335] the product of the diameter (mm) of the crown ply cords and the thickness (mm) of the tread is less than 10.0.

[0336] The tire according to the present invention (2) as described in the present invention (1), characterized in that the diameter of the crown ply cords is 0.2 mm or more and 0.8 mm or less.

[0337] The tire according to the present invention (3) as described in the present invention (1), characterized in that, in the tire width direction of the crown ply cords, the number of cords per 50 mm width is 40 or more and 80 or less.

[0338] The tire according to the present invention (4) as described in the present invention (1), characterized in that the belt ply cords are composed of 1 or more and 4 or less filaments.

[0339] The tire according to the present invention (5) as described in the present invention (1), characterized in that, in the tire width direction, the number of belt ply cords per 50 mm width is 20 or more and 60 or less.

[0340] The tire according to the present invention (6) as described in the present invention (1), characterized in that vegetable oil is contained in the rubber composition.

[0341] The tire according to the present invention (7) as described in the present invention (1), characterized in that sustainable carbon black is contained in the rubber composition.

[0342] The tire according to the present invention (8) as described in the present invention (1), characterized in that sustainable silica is contained in the rubber composition.

[0343] The tire according to the present invention (9) as described in the present invention (1), characterized in that the polyethylene terephthalate fibers are sustainable polyethylene terephthalate fibers.

[0344] Symbol description

[0345] 1 Tire

[0346] 2 Tread

[0347] 3 Sidewall

[0348] 4 Abrasion-resistant part

[0349] 5 Bead

[0350] 6 Inner liner

[0351] 7 Carcass

[0352] 8 Belt

[0353] 9 Filler

[0354] 10 Apex

[0355] Equatorial plane of the CL 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 using a rubber composition containing 75 parts by mass or more of silica relative to 100 parts by mass of the rubber component, has a thickness exceeding 6 mm, and has a rubber hardness, i.e., 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 10.0, wherein, The units of the diameter and the thickness are mm.

2. 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.

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

4. The tire according to claim 1, characterized in that The belt cords are composed of one or more and four or less filaments.

5. The tire according to claim 1, characterized in that In the tire width direction, the number of belt cords per 50 mm width is 20 or more and 60 or less.

6. The tire according to claim 1, characterized in that The rubber composition contains vegetable oil.

7. The tire according to claim 1, characterized in that Sustainable carbon black is contained in the rubber composition.

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

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

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