Tire

Abstract

Provided is a tire in which a cap ply is used, the tire being capable of improving the overall performance of high-speed durability, riding comfort performance, 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, the cap ply cord being formed by twisting a single yarn comprising polyethylene terephthalate fibers. The tread is formed using a rubber composition containing more than 30 parts by mass of an isoprene-based rubber per 100 parts by mass of a rubber component so as to have a thickness of more than 6 mm and a rubber hardness (Shore hardness) Hs of more than 60, and the product of the diameter (mm) of the cap ply cord and the thickness (mm) of the tread is less than 10.2.

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, riding comfort performance, and rolling resistance.

[0008] Means for Solving the Problems

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

[0010] A carcass having carcass cords;

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

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

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

[0014] The tire is characterized in that

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

[0016] The above-mentioned tread is formed of a rubber composition containing more than 30 parts by mass of isoprene rubber in 100 parts by mass of the rubber component to a thickness of more than 6 mm and a rubber hardness (Shore hardness) Hs of more than 60,

[0017] The product of the diameter (mm) of the above-mentioned crown ply cords and the thickness (mm) of the above-mentioned tread is less than 10.2.

[0018] Advantages of the Invention

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

[0020] Figure 1 It is a schematic cross-sectional view of a tire showing an embodiment of the present invention. Detailed 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 disposed radially outside the carcass of the tire; a chafer layer having chafer layer cords and disposed radially outside the belt layer of the tire; and a tread disposed radially outside the chafer layer of the tire. Further, the chafer layer cords are formed by twisting one yarn containing polyethylene terephthalate (PET) fibers. In addition, the tread is formed of a rubber composition containing more than 30 parts by mass of isoprene rubber (IR) in 100 parts by mass of the rubber component to have a thickness of more than 6 mm and a rubber hardness (Shore hardness) Hs of more than 60. Further, the product of the diameter (mm) of the chafer layer cords and the thickness (mm) of the tread is less than 10.2.

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

[0026] 2. Mechanism of Effect Manifestation in the Tire of the Present Invention

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

[0028] (1) Use of a single-twist PET chafer layer

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

[0030] (a) PET chafer layer

[0031] PET fibers are highly elastic compared to nylon 66 (a polyamide synthetic fiber) that has been mainly used, and can reduce the cord diameter. Therefore, it is considered that the thickness (cord thickness) of the chafer layer and the weight (cord weight) of the chafer layer can be reduced, and a reduction in rolling resistance can be achieved.

[0032] (b) Single-twist chafer layer

[0033] However, compared with nylon 66 (synthetic polyamide fiber), the PET crown ply is prone to heat generation, which may lead to deterioration of rolling resistance.

[0034] In the present invention, by using a single-twist crown ply formed by twisting one yarn as the crown ply cord, heat generation is reduced. That is, by using a single-twist crown ply, a reduction in the volume of the crown ply cord can be achieved, and thus heat generation can be reduced.

[0035] In addition, the use of a single-twist crown ply can reduce the weight of the tire, achieving weight reduction of the tire, and thus a reduction in rolling resistance can be achieved.

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

[0037] (2) Tread

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

[0039] (a) Thickness of the tread

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

[0041] It should be noted that the tread may be formed of only one layer of the layer (crown rubber layer) as the ground contact surface, or may be composed of two layers with a base rubber layer provided inside the crown rubber layer. In addition, it may be three layers or four layers or more. In this case, the rubber composition for the tread becomes the rubber composition for forming the outermost crown rubber layer on the ground contact surface side, and preferably satisfies the above respective 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 equator plane in the radial cross-section of the tire. In the case where the tread is formed of a single rubber composition, it is the thickness of 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 outermost crown rubber layer on the ground contact 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 "JATMA YEARBOOK". In the case of ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" described in "STANDARDS MANUAL". In the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" described in "YEAR BOOK". Refer to them in the order of JATMA, ETRTO, and TRA. When there are applicable sizes in the reference, follow that standard. Additionally, 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] (b) Rubber hardness (Shore hardness) Hs

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

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

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

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

[0050] (3) Isoprene rubber (IR)

[0051] The isoprene rubber has low heat generation. Therefore, by including more than 30 parts by mass of the isoprene rubber in 100 parts by mass of the rubber component of the tread rubber composition, it is possible to suppress the reduction in the modulus of the PET associated with tire heat generation during high-speed driving, and it is possible to achieve an improvement in high-speed durability.

[0052] (3) The product of the diameter (mm) of the cap ply cord and the thickness (mm) of the tread

[0053] The present inventors further conducted research and found that if the product of the diameter (mm) of the cap ply cord and the thickness (mm) of the tread is less than 10.2, the above-described various effects are synergistically exerted, and it is possible to achieve an improvement in the comprehensive performance of high-speed durability, riding comfort performance, and rolling resistance. 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 6.00 or less, and further preferably 4.00 or less. As the lower limit, for example, it is preferably 1.50 or more, and more preferably 2.50 or more.

[0054] It should be noted that in the above text, regarding the "diameter of the cap ply cord", in the case where the circumscribed circle of the cross-section perpendicular to the extending direction of the cord is a perfect circle, it refers to the diameter, and in the case of an ellipse or the like, it refers to the equivalent circle diameter (the diameter of the perfect circle assuming the same cross-sectional area). The same applies to the diameters of the belt ply cord and the carcass cord.

[0055] [2] More preferred embodiments of the tire of the present invention

[0056] The tire of the present invention can achieve greater effects by adopting the following methods.

[0057] 1. Belt ply cord

[0058] In the present invention, as the belt ply cord constituting the belt ply, a steel cord is preferred. From the aspect of tire weight reduction, 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.

[0059] 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.

[0060] 2. Particle size of silica

[0061] In the present invention, the rubber composition for a tread preferably contains silica. At this time, if the particle size (average primary particle size) of the silica is too small, the processability deteriorates. Therefore, silica having a particle size exceeding 8 nm is preferably used. More preferably, it is 9 nm or more, and further preferably 10 nm or more. On the other hand, from the viewpoints 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.

[0062] 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, and can be observed by a transmission type or scanning type electron microscope. More than 400 primary particles of silica observed in the field of view are measured, and the average value is obtained therefrom.

[0063] Specifically, the silica taken out from the rubber composition cut out from the tire is directly observed using an electron microscope or the like, and the equivalent cross-sectional diameter is calculated from the area of each silica particle obtained, and the average value is obtained, whereby the average primary particle size can be calculated.

[0064] 3. Resin component

[0065] In addition, the rubber composition forming the tread preferably contains a resin component.

[0066] By containing a resin component in the rubber composition, the ground contact property with the road surface is improved by the adhesiveness of the resin component, and therefore it is considered that the rolling resistance during starting can be further improved.

[0067] As the preferred resin component, preferably 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.

[0068] [3] Embodiment

[0069] Hereinafter, the present invention will be specifically described based on the embodiment.

[0070] 1. Tire of the present embodiment

[0071] Figure 1 is a schematic cross-sectional view for explaining the tire of the present embodiment. Figure 1In the following description, the up-down direction is the radial direction of the tire, the left-right direction is the rotational axis direction of the tire, and the direction perpendicular to the paper surface is the circumferential direction of the tire. It should be noted that Figure 1 In Figure 1 , the dotted line CL represents the equatorial plane of the tire. It should be noted that the shape of the tire is symmetric with respect to the equatorial plane except for the tread pattern. Therefore Figure 1 One quarter of the entire tire is shown in Figure 1 .

[0072] As Figure 1 As shown in Figure 1 , 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 radial direction of the tire.

[0073] With such a configuration, as described above, as the cap ply cord, a cap ply cord formed by twisting one yarn containing PET fibers is used, and the tread is appropriately formed. Further, 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, riding comfort performance, and rolling resistance can be achieved.

[0074] 2. Rubber composition for tread

[0075] 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 antioxidant, an oil, a resin material, and an antioxidant.

[0076] (1) Compounding materials

[0077] (a) Rubber component

[0078] The rubber component other than the isoprene rubber (IR) is not particularly limited, and for example, diene rubbers such as styrene-butadiene rubber (SBR), butadiene rubber (BR), nitrile rubber (NBR), chloroprene rubber (CR), and butyl rubber (IIR) can be used. In the present invention, the combined use of IR, SBR, and BR is preferred.

[0079] (①) SBR

[0080] The weight-average molecular weight of the SBR is, for example, more than 100,000 and less than 2,000,000. The styrene content of the 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 the SBR is, for example, preferably more than 5% by mass, more preferably more than 10% by mass, and further preferably more than 15% by mass. On the other hand, it is preferably less than 70% by mass, more preferably less than 40% by mass, and further preferably less than 30% by mass. It should be noted that the structural identification (measurement of styrene content and vinyl content) of the SBR can be carried out using, for example, a device of the JNM-ECA series manufactured by JEOL Ltd.

[0081] The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. can be used. The SBR can be either unmodified SBR or modified SBR. In addition, hydrogenated SBR obtained by hydrogenating the butadiene part in the SBR can be used. The hydrogenated SBR can also be obtained by subsequently hydrogenating the BR part in the SBR, or the same structure can be obtained by copolymerizing styrene, ethylene, and butadiene.

[0082] As the modified SBR, preferably an SBR having a functional group that interacts with a filler such as silica can be mentioned. For example, a terminal-modified SBR obtained by modifying at least one terminal of the SBR with a compound (modifier) 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 terminal-modified SBR having the above functional group in the main chain and at the terminal (for example, a main-chain terminal-modified SBR having the above functional group in the main chain and modifying at least one terminal with the above modifier); 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.

[0083] As the above functional group, for example, an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea 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 hydrazine 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. can be mentioned. It should be noted that these functional groups can have substituents.

[0084] In addition, as the modified SBR, for example, an SBR modified with a compound (modifier) represented by the following formula can be used.

[0085] [Chemical formula 1]

[0086]

[0087] 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 silyloxy 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 may be bonded to form a ring structure together with the nitrogen atom. n represents an integer.

[0088] As the modified SBR modified with the compound (modifier) represented by the above formula, SBR obtained by modifying the polymerization terminal (active terminal) of solution-polymerized styrene-butadiene rubber (S-SBR) with the compound represented by the above formula (modified SBR described in Japanese Patent Application Laid-Open No. 2010-111753, etc.) can be used.

[0089] As R 1 , R 2 and R 3 , an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms) is suitable. As R 4 and R 5 , an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is suitable. n is preferably 1 to 5, more preferably 2 to 4, and further preferably 3. In addition, when R 4 and R 5 are bonded to form a ring structure together with the nitrogen atom, a 4- to 8-membered ring is preferred. It should be noted that the alkoxy group also includes a cycloalkoxy group (such as cyclohexyloxy) and an aryloxy group (such as phenoxy and benzyloxy).

[0090] Specific examples of the above modifier include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. They can be used alone or in combination of two or more.

[0091] 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; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylamino compounds such as diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl-o-toluidine, tetraglycidyl-m-xylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bis(aminomethyl)cyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamoyl chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamoyl chloride, and N,N-diethylcarbamoyl chloride; epoxy group-containing silane compounds such as 1,3-bis(epoxypropylpropyl)-tetramethyldisiloxane and (3-epoxypropylpropyl)-pentamethyldisiloxane; thioether group-containing silane compounds such as (trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tripropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxysilyl)propyl]sulfide, and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide; N-substituted aziridine compounds such as aziridine and propyleneimine; alkoxysilanes such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane;(Thio)benzophenone compounds having 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.;

[0092] 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.

[0093] 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.

[0094] (②) Isoprene rubber

[0095] As the isoprene rubber, natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, etc. can be cited. From the viewpoint of excellent strength, NR is preferred.

[0096] As NR, for example, SVR-L, SIR20, RSS#3, TSR20, etc., which are commonly used in the tire industry, can be used. As IR, there is no particular limitation, and for example, IR2200 manufactured by Zeon Corporation can be used, which is commonly used in the tire industry. As the modified NR, deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. can be cited. As the modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. can be cited. As the modified IR, epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. can be cited. They can be used alone or in combination of two or more.

[0097] As described above, the content of the isoprene rubber in 100 parts by mass of the rubber component exceeds 30 parts by mass, and more preferably 35 parts by mass or more. As the upper limit, for example, it is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, further preferably 80 parts by mass or less, further preferably 70 parts by mass or less, and further preferably 60 parts by mass or less.

[0098] (③) BR

[0099] The weight-average molecular weight of BR, for example, exceeds 100,000 and is less than 2,000,000. The vinyl content of BR, for example, exceeds 1% by mass and is less than 30% by mass. The cis content of BR, for example, exceeds 1% by mass and is 98% by mass or less. The trans content of BR, for example, exceeds 1% by mass and is less than 60% by mass. It should be noted that the cis content can be measured by infrared absorption spectroscopy.

[0100] There is no particular limitation for BR, and BR with a high cis content (cis content of 90% or more), BR with a low cis content, BR containing syndiotactic polybutadiene crystals, etc. can be used. BR can be either unmodified BR or modified BR. As the modified BR, for example, BR modified with the compound (modifying agent) represented by the following formula can be used.

[0101] [Chemical formula 2]

[0102]

[0103] It should be noted that in the formula, R 1 , R 2 and R 3Same or different, representing an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or a derivative thereof. R 4 and R 5 Same or different, representing a hydrogen atom or an alkyl group. R 4 and R 5 may be bonded to form a ring structure together with the nitrogen atom. n represents an integer.

[0104] As the modified BR modified with the compound (modifier) represented by the above formula, there can be mentioned BR obtained by modifying the polymerization terminal (active terminal) with the compound represented by the above formula.

[0105] As R 1 、R 2 and R 3 , an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms) is suitable. As R 4 and R 5 , an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is suitable. n is preferably 1 to 5, more preferably 2 to 4, and further preferably 3. In addition, when R 4 and R 5 are bonded to form a ring structure together with the nitrogen atom, a 4- to 8-membered ring is preferred. It should be noted that the alkoxy group also includes a cycloalkoxy group (such as cyclohexyloxy) and an aryloxy group (such as phenoxy and benzyloxy).

[0106] As specific examples of the above modifier, there can be mentioned 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.

[0107] 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, 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; 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, and N,N-diethylcarbamoyl chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidoxypropyl)-tetramethyldisiloxane and (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 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. It should be noted that these modified BRs can be used alone or in combination of two or more.

[0108] As the BR, products of, for example, Ube Industries, Ltd., ENEOS Materials Co., Ltd., Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used.

[0109] 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.

[0110] (④) Other rubber components

[0111] In the rubber composition, as other rubber components, rubber (polymers) such as nitrile rubber (NBR) that are commonly used in the manufacture of tires may be included as needed.

[0112] 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.

[0113] As the monomers obtained by recycling (recycled monomers), there is no particular limitation, 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), recycled butadiene (recycled butadiene) and / or recycled styrene (recycled styrene) are preferably used as raw materials.

[0114] As the method for manufacturing recycled monomers, there is no particular limitation, and examples thereof include synthesis from recycled naphtha obtained by decomposing rubber products such as tires. In addition, as the method for manufacturing recycled naphtha, there is no particular limitation, and for example, rubber products such as tires can be decomposed under high temperature and high pressure, can be decomposed by microwaves, or can be extracted after mechanical pulverization.

[0115] In addition, the raw materials (monomers) of synthetic rubbers such as IR, SBR, and BR can be derived from biomass. Here, biomass refers to substances from natural resources such as plants. As biomass, there is no particular limitation, and examples thereof include agricultural and forestry products, sugars, wood, plant residues after obtaining useful components, plant-derived ethanol, biomass naphtha, etc. As the monomers derived from biomass (biomass monomers), there is no particular limitation, 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 a catalyst, conversion using high heat, conversion using high pressure, conversion using electromagnetic waves, conversion using a critical liquid, and combinations thereof can be cited.

[0116] As a polymer synthesized from biomass monomer components (biomass polymer), there is no particular limitation, and examples thereof include polybutadiene rubber synthesized from butadiene derived from biomass, and aromatic vinyl monomer / butadiene copolymers synthesized from butadiene derived from biomass and / or aromatic vinyl monomers derived from biomass. 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.

[0117] 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.

[0118] pMC refers to the 14 ratio of the C concentration of the sample to the 14 C concentration of the modern standard reference, and this value is used as an index representing the biomass ratio of the compound (rubber). The meaning of this value is as described below.

[0119] In 1 mole (6.02×10 23 ), there is about one trillionth of ordinary carbon atoms, that is, about 6.02×10 11 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 of the 14 C elements contained in these substances at the beginning of immobilization have decayed. Therefore, in 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 14 C elements at all.

[0120] 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, it is possible to calculate the proportion (biomass proportion) of the compound (from natural resources) in a certain compound (rubber), that is, the compound from biomass resources.

[0121] 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 benchmark of the 14 C concentration, that is, the modern standard reference. As a specific reference material, 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 radioactivity intensity of 13 C per 1 g of carbon) is divided into each carbon isotope, corrected to a certain value for 14 C, and decay correction is carried out from 1950 AD to the measurement date, and the obtained value is used as the standard

[0122] Therefore, if rubber is made from a substance that is 100% from biomass (natural system), although there are regional differences, etc., it usually does not reach 100 under normal conditions at present, so it shows a value of about 110 pMC. On the other hand, for chemical substances 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.

[0123] In summary, from the aspect of environmental protection (sustainability), it is suitable to use materials such as rubber with a high pMC value, that is, rubber materials with a high biomass proportion, in the rubber composition.

[0124] (b) Blending materials other than rubber components

[0125] (①) Filler

[0126] As described above, the rubber composition preferably contains silica as a reinforcing agent, and if necessary, other fillers such as carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc. may also be contained. It should be noted that when using silica, it is preferably used in combination with a silane coupling agent.

[0127] As the compounding amount of the filler, relative to 100 parts by mass of the rubber component, first, it is preferable that the silica exceeds 75 parts by mass, 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.

[0128] (i) Silica

[0129] Silica has OH groups on its surface, so hydrogen bonds are generated between the silica surfaces and it also interacts with the rubber component. Therefore, when driving, forces can be easily generated and transmitted inside the rubber, and the forces generated during turning can be easily transmitted, ensuring excellent ride comfort performance. 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.

[0130] 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.

[0131] As the silica, there is no particular limitation, 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.

[0132] As the raw material of silica, there is no particular limitation. For example, it can be a raw material of mineral origin such as quartz, or a raw material of biological origin such as rice husk (for example, silica based on biomass materials such as rice husk), 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.

[0133] Silica (biomass silica) made from biomass materials 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 from the reaction with sulfuric acid is filtered, washed with water, dried, and pulverized in the same manner as existing wet silica, whereby it can be obtained.

[0134] 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, the recovery method is not particularly limited, and examples include thermal decomposition and decomposition using electromagnetic waves. Among them, silica recovered from semiconductor and other electronic components or tires is preferred.

[0135] If silica crystallizes, it becomes 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 (see Japanese Patent Laid-Open No. 2009-2594, Akita Prefectural University Online Journal B / 2019, vol. 6, p. 216-222, etc.).

[0136] Amorphous silica extracted from rice husks can use commercially available amorphous silica such as that from Wilmar Corporation.

[0137] 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.

[0138] The content of silica relative to 100 parts by mass of the rubber component is preferably more than 75 parts by mass, 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.

[0139] (ii) Silane coupling agent

[0140] When using silica, in order to improve the dispersibility of silica and at the same time improve mechanical properties, moldability, etc. through reaction with silica, it is preferable to use a silane coupling agent in combination.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] (iii) Carbon black

[0145] Carbon black is preferably used for the purpose of improving the crack growth resistance, durability, ultraviolet degradation resistance, etc. of the tire.

[0146] 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 further 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 further 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.

[0147] From the aspect of the rigidity of rubber, the dibutyl phthalate (DBP) absorption of carbon black is, for example, preferably 50 ml / 100 g or more, more preferably 100 ml / 100 g or more. On the other hand, from the aspect of the followability to rubber deformation, it is preferably 250 ml / 100 g or less, more preferably 150 ml / 100 g or less. It should be noted that the DBP absorption of carbon black is measured according to ASTM D2414-93.

[0148] 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.

[0149] 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.

[0150] In addition, the carbon black can be manufactured by combustion such as the furnace method, or by hydrothermal carbonization (HTC), or by pyrolysis of methane based on the thermal carbon black method, etc.

[0151] 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.

[0152] 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.

[0153] (iv) Other fillers

[0154] In addition to the above carbon black and silica, the rubber composition may further contain fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, magnesium sulfate, etc. 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.

[0155] (②) Softening agent component

[0156] In the rubber composition, considering the proper dispersion of the powder materials during mixing, a softening agent component is preferably used as needed. It should be noted that the softening agent and plasticizer component here refers to the material that imparts plasticity to the rubber component, and it is a concept that includes both softening agents that are liquid at 25°C and softening agents that are solid at 25°C.

[0157] Examples of softening agents include resin components, oils, liquid polymers, ester plasticizers, etc. These softening agents can be derived from mineral resources such as petroleum or natural gas, can also be derived from biomass, and can also be derived from naphtha recycled from rubber products 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 softening agents. Among them, softening agents derived from biomass or from recycling are preferably used as sustainable softening agents.

[0158] It should be noted that these softening agents can be used alone or in combination of two or more. As the content of the plasticizer component relative to 100 parts by mass of the rubber component, it is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 25 parts by mass or more. As the upper limit, for example, it is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and further preferably 30 parts by mass or less. It should be noted that the content of the plasticizer component also includes the amount of oil contained in rubber (oil-extended rubber), etc.

[0159] (i) Oil

[0160] 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.

[0161] (i-1) Mineral oil

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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 Co., H&R Co., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kogyo Co., Ltd., etc. can be used. They can be used alone or in combination of two or more.

[0166] (i-2) Vegetable oil

[0167] 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.

[0168] 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, oxidatively polymerized oils after oxidation, waste cooking oils recovered after use 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.

[0169] As vegetable oils, acylglycerols are preferably included, and triacylglycerols are more preferably included. It should be noted that acylglycerols refer to compounds in which the hydroxyl groups of glycerol form ester bonds with fatty acids. As acylglycerols, there is no particular limitation, and they can be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. In addition, acylglycerols can be monomers, dimers, or polymers of trimer or higher. It should be noted that acylglycerols of dimer or higher can be obtained by thermal polymerization or oxidative polymerization, etc. In addition, acylglycerols can be liquid or solid at normal temperature (25°C).

[0170] As a method for confirming whether an acylglycerol is included 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, and 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 acylglycerols are contained. It should be noted that "around" here refers to the range of ±0.10 ppm.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] (ii) Liquid rubber

[0175] Liquid rubber refers to a polymer in a liquid state at room temperature (25 °C), which is a rubber component that can be extracted from vulcanized tires by acetone extraction. Examples of liquid rubber include farnesene-based polymers, liquid diene-based polymers, and their hydrides.

[0176] Farnesene-based polymers refer to polymers obtained by polymerizing farnesene and having structural units based on farnesene. Isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene) exist in farnesene.

[0177] 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).

[0178] 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.

[0179] The polystyrene-reduced weight average molecular weight (Mw) of the liquid diene-based polymer measured by gel permeation chromatography (GPC) is, for example, more than 1.0×10 3 and less than 2.0×10 5 . Here, the Mw of the liquid diene-based polymer is the polystyrene-reduced value measured by gel permeation chromatography (GPC).

[0180] As the liquid rubber, products of, for example, KURARAY Co., Ltd., Cray Valley, etc. can be used.

[0181] (iii) Resin component

[0182] The resin component also functions as an adhesion - imparting component. It can be solid or liquid at room temperature. As specific resin components, for example, rosin - based resins, styrene - based resins, benzofuran - based resins, terpene - based resins, C5 resins, C9 resins, C5C9 resins, acrylic resins, etc. can be cited, and two or more of them can be used in combination. It should be noted that these resin components can also be provided with modified groups capable of reacting with silica, etc. as required.

[0183] Rosin - based resins are resins mainly composed of rosin acid obtained by processing pine resin. These rosin - based resins (rosins) can be classified according to whether they are 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.

[0184] Styrene - based resins are polymers using styrene - based monomers as constituent monomers, and examples include polymers obtained by polymerizing styrene - based monomers as the main component (50% by mass or more). Specifically, in addition to homopolymers obtained by homopolymerizing styrene - based monomers (styrene, o - methylstyrene, m - methylstyrene, p - methylstyrene, α - methylstyrene, p - methoxystyrene, p - tert - butylstyrene, p - phenylstyrene, o - chlorostyrene, m - chlorostyrene, p - chlorostyrene, etc.) respectively, and copolymers obtained by copolymerizing two or more styrene - based monomers, copolymers of styrene - based monomers and other monomers capable of copolymerizing with them can also be cited.

[0185] As the above - mentioned other monomers, examples include acrylonitrile - based monomers such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylic acid and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene, butadiene, and isoprene, olefins such as 1 - butene and 1 - pentene; α,β - unsaturated carboxylic acids or their acid anhydrides such as maleic anhydride; etc.

[0186] 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, examples include styrene, α - methylstyrene, methyl indene, vinyltoluene, etc.

[0187] 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).

[0188] 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.

[0189] 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.

[0190] 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 copolymerized from the above-mentioned terpene compounds and phenolic compounds, and resins obtained by hydrogenating such resins can be cited. Specifically, resins formed by condensing the above-mentioned terpene compounds, phenolic compounds, and formaldehyde can be cited. It should be noted that as phenolic compounds, phenol, bisphenol A, cresol, xylenol, etc. can be cited for example. 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 phenol compounds such as phenol, alkylphenol, alkoxyphenol, phenol containing an unsaturated hydrocarbon group, etc. can be cited; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, naphthol containing an unsaturated hydrocarbon group, etc.; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, styrene containing an unsaturated hydrocarbon group, etc.; benzofuran, indene, etc.

[0191] "C5 resin" refers to a resin obtained by polymerizing C5 fractions. As C5 fractions, petroleum fractions corresponding to 4 to 5 carbon atoms such as cyclopentadiene, pentene, pentadiene, isoprene, etc. can be cited for example. As C5-based petroleum resins, dicyclopentadiene resin (DCPD resin) is preferably used.

[0192] "C9 resin" refers to a resin obtained by polymerizing C9 fractions, or a resin obtained by hydrogenating or modifying them. As C9 fractions, petroleum fractions corresponding to 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, indene, methylindene, etc. can be cited for example. As a specific example, benzofuran indene resin, benzofuran resin, indene resin, and aromatic vinyl-based resins are preferably used. As aromatic vinyl-based 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 more preferably used, and a copolymer of α-methylstyrene and styrene is even more preferably used. As aromatic vinyl-based resins, aromatic vinyl-based resins commercially available from companies such as KRATON and Eastman Chemical can be used for example.

[0193] "C5C9 resin" refers to a resin obtained by copolymerizing the above-mentioned C5 fractions and the above-mentioned C9 fractions, or a resin obtained by hydrogenating or modifying them. As C5 fractions and C9 fractions, the above-mentioned petroleum fractions can be cited. As C5C9 resins, resins commercially available from companies such as Tosoh Corporation and LUHUA can be used for example.

[0194] The acrylic resin is not particularly limited, and for example, a solvent-free acrylic resin can be used.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] 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.

[0200] (③) Wax

[0201] 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.

[0202] 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.

[0203] 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.

[0204] 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.

[0205] (④)Antioxidant

[0206] 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.

[0207] There is no particular limitation on the antioxidant, and examples thereof include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based antioxidants such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-dimethylxyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD), etc.; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-tert-butyl-4-methylphenol and styrenated phenol; bisphenol-based, triphenol-based, polyphenol-based antioxidants such as tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. They can be used alone or in combination of two or more.

[0208] 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.

[0209] (⑤) Processing aids

[0210] The rubber composition may contain processing aids. Examples of processing aids include metal salts (compounds in which the hydrogen atoms of an acid are replaced by metal ions), fatty acid amides, amide esters, fatty acid esters, etc. They can 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.

[0211] 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.

[0212] 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.

[0213] As commercially available products of processing aids, products of Kishida Chemical Co., Ltd., Kenzo Pharmaceutical Co., Ltd., Struktol Company, Performance Additives Company, etc. can be used.

[0214] The content of the processing aid is preferably 1 part by mass or more, more preferably 2 parts by mass or more, relative to 100 parts by mass of the rubber component. As the upper limit, for example, it is preferably 6 parts by mass or less, more preferably 4 parts by mass or less.

[0215] (⑥) Lubricant (stearic acid)

[0216] The rubber composition may contain a lubricant. As the lubricant, a lubricant based on fatty acid derivatives such as stearic acid is preferably used. As stearic acid, conventionally known stearic acid can be used. Specifically, products of Nippon Oil Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acids Co., Ltd., etc. can be used. In addition, Struktol WB16 manufactured by Struktol Company can also be used.

[0217] 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.

[0218] (⑦) Zinc oxide

[0219] The rubber composition may contain zinc oxide. The content of zinc oxide is, for example, more than 0.5 part by mass and less than 10 parts by mass relative to 100 parts by mass of the rubber component. As 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.

[0220] (⑧) Crosslinking agent and vulcanization accelerator

[0221] The rubber composition preferably contains a crosslinking agent such as sulfur. The content of the crosslinking agent is, for example, more than 0.1 part by mass and less than 10.0 parts by mass 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.

[0222] 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.

[0223] 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 Kankyo Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0224] 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., which are sulfur - containing vulcanizing agents, and organic peroxides such as dicumyl peroxide can be used.

[0225] Moreover, the rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator is, for example, more than 0.3 part by mass and less than 10.0 parts by mass relative to 100 parts by mass of the rubber component.

[0226] As vulcanization accelerators, thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, bis(2-benzothiazolyl) disulfide, and N-cyclohexyl-2-benzothiazolyl sulfenamide 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-benzothiazolyl sulfenamide, N-tert-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazolyl sulfenamide, and N,N'-diisopropyl-2-benzothiazolyl sulfenamide; 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.

[0227] (⑧) Others

[0228] In the rubber composition, in addition to the above components, additives commonly used in the tire industry, such as organic filler materials like 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.

[0229] It should be noted that in the present invention, various materials containing carbon atoms in the above materials (such as rubber, oil, resin, vulcanization accelerator, anti-aging agent, surfactant, etc.) can be derived from carbon dioxide in the atmosphere. As a method for obtaining the blend of the present invention from carbon dioxide, carbon dioxide can be directly converted, or methane obtained through the methanation process of synthesizing methane via carbon dioxide can be converted.

[0230] (⑨) Capping ply cord

[0231] Although not a blending material of the rubber composition, the capping ply cord will also be described. In the present invention, as described above, as the capping ply cord, a single-twist PET capping ply formed by twisting one yarn containing PET fibers is used.

[0232] It should be noted that the total fineness of the capping ply cord is preferably 900 dtex or more and 2500 dtex or less, more preferably 1500 tex or more and 2300 dtex or less.

[0233] 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.

[0234] 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.

[0235] It should be noted that the fineness, coarseness, and density of the above-mentioned cap ply cords can be measured according to the methods specified in JIS L1017:2002.

[0236] After treating the cap ply cords with an adhesive and bonding them to the specified rubber composition for the cap ply, a cap 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), which is an epoxy compound, and RFL (resorcinol-formaldehyde-emulsion) can be used.

[0237] 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, it is suitable to use such sustainable PET fibers.

[0238] (2) Preparation of the rubber composition

[0239] The rubber composition can be prepared by a general method, for example, a manufacturing method including a basic kneading step of kneading rubber components and fillers such as silica, and a refining kneading step of kneading the kneaded product obtained in the above basic kneading step and a crosslinking agent.

[0240] Kneading can be carried out using a known (closed-type) kneader such as a Banbury mixer, a kneader, or an open mill.

[0241] The kneading temperature in the basic kneading step is, for example, more than 50°C and less than 200°C, and the kneading time is, for example, more than 30 seconds and less than 30 minutes. In the basic kneading step, in addition to the above components, compounding agents used in the existing rubber industry, such as softeners such as oil, stearic acid, zinc oxide, anti-aging agents, waxes, vulcanization accelerators, etc., can be appropriately added as needed and kneaded.

[0242] In the refining kneading step, the kneaded product obtained in the above basic kneading step and the crosslinking agent are kneaded. The kneading temperature in the refining kneading step is, for example, more than room temperature and less than 80°C, and the kneading time is, for example, more than 1 minute and less than 15 minutes. In the refining kneading step, in addition to the above components, vulcanization accelerators, zinc oxide, etc. can be appropriately added as needed and kneaded.

[0243] After that, the above-obtained rubber composition is extruded into a specified shape, and thus a tread can be formed.

[0244] 3. Manufacture of the tire

[0245] 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 specified shape to manufacture a tread. Next, it is combined with other rubber components on a tire molding machine to produce an unvulcanized tire.

[0246] 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 circumference and attaching the sidewall to the radially outer side to form a sidewall portion, an unvulcanized tire is produced.

[0247] Then, the tire is obtained by heating and pressurizing the unvulcanized tire produced above in a vulcanizer. The vulcanization process can be carried out by applying known vulcanization means. As the vulcanization temperature, for example, it is more than 120 °C and less than 200 °C, and the vulcanization time is, for example, more than 5 minutes and less than 15 minutes.

[0248] 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, riding comfort performance, and rolling resistance can be achieved.

[0249] 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.

[0250] Examples

[0251] The following shows examples (examples) considered to be preferable during implementation, but the scope of the present invention is not limited to these examples.

[0252] Regarding tires (tire size: 195 / 65R15) composed of treads molded from various compounding materials shown below, and tire components such as a crown ply and a belt layer, research was conducted, and the results calculated based on the evaluation methods described later regarding high-speed durability, riding comfort performance, rolling resistance, and comprehensive performance are shown together at the lower part of Table 2.

[0253] 1. Production of rubber composition

[0254] Using the various compounding materials shown below, a rubber composition for the tread was produced.

[0255] (1) Blended material

[0256] (a) Rubber component

[0257] (①) NR: TSR20

[0258] (②) SBR-1: Modified S-SBR (styrene content: 25% by mass, vinyl content: 60 mol%, Tg: -24°C, non-oil-extended) manufactured based on Production Example 1 described below

[0259] (③) SBR-2: Modified S-SBR (styrene content: 40% by mass, vinyl content: 36 mol%, Tg: -25°C, non-oil-extended) manufactured based on Production Example 2 described below

[0260] (④) BR: UBEPOL BR (registered trademark) 150B manufactured by Ube Industries, Ltd. (unmodified, cis content: 96% by mass, Tg: -107°C)

[0261] (Production Example 1)

[0262] 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. Then, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane was added as a modifier for reaction. After the polymerization reaction ended, 2,6-di-tert-butyl-p-cresol was added, the solvent was removed by stripping, and drying was carried out using a hot roll to obtain SBR-1.

[0263] (Production Example 2)

[0264] The above SBR-2 was obtained in the same manner as in Production Example 1 except that the target styrene content, vinyl content, and Tg were changed and the modifier was 3-dimethylaminopropyltriethoxysilane.

[0265] (b) Blended materials other than rubber components

[0266] (①) Carbon black: DIABLACK N220 manufactured by Mitsubishi Chemical Corporation

[0267] (N2SA: 115 m 2 / g)

[0268] (②) Silica: ULTRASIL VN3 manufactured by Evonik Industries AG

[0269] (N2SA: 175 m2 / g, average primary particle size: 17 nm)

[0270] (③) Silane coupling agent: NXT manufactured by Momentive

[0271] (3 - Octanoylthiopropyltriethoxysilane)

[0272] (④) Oil: Processing oil A / OMIX manufactured by Sankyo Yuka Kogyo Co., Ltd.

[0273] (⑤) Resin: YS resin PX850 manufactured by Yasuhara Chemical Co., Ltd.

[0274] (Softening point 85°C, β - pinene resin (terpene resin))

[0275] (⑥) Wax: OZOACE 0355 manufactured by Nippon Seiro Co., Ltd.

[0276] (⑦) Anti - aging agent - 1: NOCRAC 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0277] (N - (1,3 - dimethylbutyl) - N’ - phenyl - p - phenylenediamine)

[0278] (⑧) Anti - aging agent - 2: ANTAGE RD manufactured by Kawaguchi Chemical Industry Co., Ltd.

[0279] (Poly(2,2,4 - trimethyl - 1,2 - dihydroquinoline)

[0280] (⑨) Stearic acid: Bead - shaped stearic acid "Tsubaki" manufactured by NOF Corporation

[0281] (⑩) Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd.

[0282] Sulfur: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd.

[0283] Accelerator - 1: NOCCELERCZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0284] (N - cyclohexylbenzothiazole - 2 - sulfenamide)

[0285] Accelerator - 2: NOCCELER D manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0286] (N,N’ - diphenylguanidine)

[0287] (2) Preparation of the tread rubber composition

[0288] Based on the respective ratios of A to C shown in Table 1, using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., materials other than sulfur and vulcanization accelerators were kneaded at 150 °C for 5 minutes to obtain a kneaded product.

[0289] Next, sulfur and vulcanization accelerators were added to the kneaded product, and it was kneaded at 80 °C for 5 minutes using a two-roll mill to obtain rubber compositions for treads of ratios A to C.

[0290] 2. Molding of tire components (tread, crown ply, belt ply)

[0291] (1) Molding of the tread

[0292] Next, using the rubber composition obtained above, a tread (tread running surface) was molded with the respective thicknesses shown in Table 2.

[0293] (2) Molding of the crown ply

[0294] Meanwhile, a prescribed rubber composition for the crown ply was applied to each crown ply cord shown in Table 2 to mold each crown ply.

[0295] (3) Molding of the belt ply

[0296] Similarly, a prescribed rubber composition for the belt ply was applied to each belt ply cord shown in Table 2 to mold each belt ply.

[0297] 3. Manufacture of tires

[0298] Next, the respective treads, crown plies, and belt plies obtained above were bonded together with other tire components to form an unvulcanized tire, which was then pressure-vulcanized at 170 °C for 10 minutes to manufacture test tires for Examples 1 to 4 and Comparative Examples 1 to 5.

[0299] 4. Performance evaluation test

[0300] (1) High-speed durability evaluation

[0301] Each test tire was assembled onto a rim (size = 16 × 6.0J), air was filled into the tire, and after adjusting the internal pressure to 280 kPa, it was installed on a drum driving test machine. A longitudinal load of 4.22 kN was applied, and starting from 200 km / h, the speed was gradually increased in stages by 10 km / h, and the time and speed until tire damage were measured. The time obtained was divided by the time taken to increase to the next speed, multiplied by 10 km / h, and the value obtained was added to the speed obtained to be used as an index of high-speed durability.

[0302] Next, taking the result in Comparative Example 2 as 100, it was indexed based on the following formula for high-speed durability evaluation. The larger the value, the more excellent the high-speed durability.

[0303] High-speed durability evaluation = [(Result of the test tire) / (Result of Comparative Example 2)] × 100

[0304] (2) Ride comfort performance evaluation

[0305] Each test tire was assembled onto all the wheels of a vehicle (a domestic FR car with a displacement of 2000 cc). Twenty test drivers respectively gave a sensory evaluation of the ride comfort performance when driving around on a test track at a speed of over 100 km / h on a scale of 1 - 10 (the larger the value, the better), and the total score was calculated.

[0306] Next, taking the result in Comparative Example 5 as 100, it was indexed based on the following formula as the ride comfort performance evaluation. The larger the value, the more excellent the ride comfort performance.

[0307] Ride comfort performance evaluation = [(Result of the test tire) / (Result of Comparative Example 5)] × 100

[0308] (3) Rolling resistance evaluation

[0309] Using a rolling resistance testing machine, the rolling resistance coefficient (RRC: Rolling Resistance Coefficient) of each test tire when driving on a drum at a speed of 80 km / h under the following conditions was measured.

[0310] Rim used: 16 × 6.0J

[0311] Inner pressure: 210 kPa

[0312] Load: 4.82 kN

[0313] Next, taking the result in Comparative Example 4 as 100, it was indexed based on the following formula as the rolling resistance evaluation. The larger the value, the more the rolling resistance is reduced.

[0314] Rolling resistance evaluation = [(Result of Comparative Example 4) / (Result of the test tire)] × 100

[0315] (4) Comprehensive evaluation

[0316] Moreover, the results of (1) - (3) were totaled as the comprehensive evaluation.

[0317] [Table 1]

[0318] (parts by mass) Ratio A Ratio B Ratio C NR 15 40 35 SBR-1 30 35 45 SBR-2 45 15 10 BR-1 10 10 10 Carbon black 8 8 10 Silica 55 55 55 Silane coupling agent 5.5 5.5 5.5 Oil 17.5 17.5 5.5 Wax 1.5 1.5 1.5 Antioxidant-1 2.5 2.5 2.5 Antioxidant-2 0.8 0.8 0.8 Stearic acid 2 2 2 Zinc oxide 2 2 2 Sulfur 1.5 1.5 1.5 Accelerator-1 2.1 2.1 2.1 Accelerator-2 2.1 2.1 2.1 Hs 58 58 65

[0319] [Table 2]

[0320]

[0321] As described above, the present invention has been described based on the embodiments, but the present invention is not limited to the above-described embodiments. Various modifications can be made to the above-described embodiments within the scope identical to and equivalent to the present invention.

[0322] The present invention (1) relates to a tire, which includes:

[0323] a carcass including carcass cords;

[0324] a belt layer including belt cords and disposed on the radially outer side of the carcass in the tire;

[0325] a crown belt layer including crown belt cords and disposed on the radially outer side of the belt layer in the tire; and

[0326] a tread disposed on the radially outer side of the crown belt layer in the tire,

[0327] wherein the tire is characterized in that

[0328] the above-mentioned crown belt cords are formed by twisting one yarn containing polyethylene terephthalate fibers,

[0329] the above-mentioned tread is formed of a rubber composition containing more than 30 parts by mass of isoprene rubber in 100 parts by mass of the rubber component, with a thickness exceeding 6 mm and a rubber hardness (Shore hardness) Hs exceeding 60,

[0330] the product of the diameter (mm) of the above-mentioned crown belt cords and the thickness (mm) of the above-mentioned tread is less than 10.2.

[0331] The present invention (2) is the tire according to the present invention (1), characterized in that the thickness of the crown belt cords of the crown belt layer is 0.01 mm or more and 0.05 mm or less.

[0332] The present invention (3) is the tire according to the present invention (1), characterized in that the total thickness of the crown belt layer is 0.20 mm or more and 0.60 mm or less.

[0333] The present invention (4) is the tire according to the present invention (1), characterized in that the belt cords are composed of one or more and four or less filaments.

[0334] The present invention (5) is the tire according to the present invention (1), characterized in that in the tire width direction of the belt cords, the number of cords per 50 mm width is 20 or more and 60 or less.

[0335] The present invention (6) is the tire according to the present invention (1), characterized in that the rubber composition contains vegetable oil.

[0336] The tire of the present invention (7) as described in the present invention (1), characterized in that the rubber composition contains sustainable carbon black.

[0337] The tire of the present invention (8) as described in the present invention (1), characterized in that the rubber composition contains sustainable silica.

[0338] The tire of the present invention (9) as described in the present invention (1), characterized in that the polyethylene terephthalate fiber is a sustainable polyethylene terephthalate fiber.

[0339] Symbol Explanation

[0340] 1 Tire

[0341] 2 Tread

[0342] 3 Sidewall

[0343] 4 Abrasion Protection Part

[0344] 5 Bead

[0345] 6 Innerliner

[0346] 7 Carcass

[0347] 8 Belt

[0348] 9 Filler

[0349] 10 Crown Band

[0350] CL Equatorial Plane of the Tire

Claims

1. A tire, comprising: A carcass having carcass cords; a belt layer including belt layer cords and arranged on the tire radial direction outer side of the carcass; a cap layer including cap layer cords and disposed on the outer side of the belt layer in the tire radial direction; and A tread, which is arranged on the outer side of the cap layer in the tire radial direction, The tire is characterized by: The cap layer cord is formed by twisting one yarn including polyethylene terephthalate fiber. The tread is formed by using a rubber composition containing more than 30 parts by mass of isoprene-based rubber in 100 parts by mass of the rubber component, and has a thickness of more than 6 mm and a rubber hardness, that is, a Shore hardness Hs, of more than 60. The product of the diameter of the cap layer cord and the thickness of the tread is less than 10.2, in, The unit of the diameter is mm, and the unit of the thickness is mm.

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

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

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

5. The tire according to claim 1, characterized in that The number of belt cords per 50 mm width in the tire width direction 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 The rubber composition contains sustainable carbon black.

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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