Tire

Abstract

The present invention further improves later stage grip performance in a tire. This tire comprises a tread section. Formed in a land section of the surface of the tread section is a groove that has an opening section opening in the surface of the tread section, and a groove bottom section, and has a width of 2 mm or less and a depth of 20 mm or less. The opening section and the groove bottom section intersect when the surface of the tread section is viewed in plan view, and the ratio X of the area of the intersecting section of the opening section and the groove bottom section to the area of the opening section when the surface of the tread section is viewed in plan view is 95% or less. The tread section is formed from a rubber composition that includes a rubber component, silica, and carbon black, the ratio Y of the silica content (parts by mass) to the carbon black content (parts by mass) being greater than 50%. Furthermore, X / Y<1.5.

Description

tire

[0001] The present invention relates to a tire.

[0002] In recent years, there has been a demand for tires to have improved grip performance (later stage grip performance) when the tread has worn down due to driving (later stage wear). Various technologies have been proposed to achieve this (for example, Patent Document 1), but they are still not sufficient, and further improvements are required.

[0003] JP 2022-19300 A

[0004] In view of the above problems, an object of the present invention is to further improve the later grip performance of a tire.

[0005] The present invention provides a tire having a tread portion, wherein a land portion on the surface of the tread portion is formed with a groove having a width of 2 mm or less and a depth of 20 mm or less, the groove having an opening facing the surface of the tread portion and a groove bottom, the opening and the groove bottom intersect when the surface of the tread portion is viewed in a plane, a ratio X of an area of ​​an intersection of the opening and the groove bottom to an area of ​​the opening when the surface of the tread portion is viewed in a plane is 95% or less, the tread portion is formed from a rubber composition containing a rubber component, silica, and carbon black, and a ratio Y of a content (parts by mass) of the silica to a content (parts by mass) of the carbon black exceeds 50%, and further, X / Y<1.5.

[0006] According to the present invention, it is possible to further improve the later grip performance of the tire.

[0007] 1A and 1B are a schematic perspective view and a schematic plan view illustrating a groove provided in a tire according to the present invention.

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

[0009] 1. Overview A tire according to the present invention is a tire having a tread portion, and grooves (hereinafter also referred to as "sipes") having a width of 2 mm or less and a depth of 20 mm or less, each having an opening facing the surface of the tread portion and a groove bottom, are formed in land portions on the surface of the tread portion. In the sipes, the openings and the groove bottoms intersect when the surface of the tread portion is viewed in plan, and a ratio X of the area of ​​the intersection of the openings and the groove bottoms to the area of ​​the openings when the surface of the tread portion is viewed in plan is 95% or less. The tread portion is formed from a rubber composition containing a rubber component, silica, and carbon black, and a ratio Y of the silica content (parts by mass) to the carbon black content (parts by mass) is greater than 50%. Furthermore, the ratio of X to Y (X / Y) is less than 1.5.

[0010] These characteristics make it possible to improve the later grip performance of the tire, as will be described later.

[0011] 2. Mechanism of the manifestation of the effects in the tire according to the present invention The mechanism of the manifestation of the above-mentioned effects in the tire according to the present invention is thought to be as follows.

[0012] (1) Shape of the Tread Portion As described above, in the tire according to the present invention, sipes each having an opening facing the surface of the tread portion and a groove bottom are formed in the land portion on the surface of the tread portion. When the surface of the tread portion is viewed in plan, the sipes are formed in a shape in which the opening and the groove bottom intersect, i.e., in a twisted shape.

[0013] By providing such twisted sipes on the surface of the tread, tire wear can be appropriately controlled, ensuring the rigidity of the tread even in the later stages of wear, and improving later grip performance.

[0014] At this time, if a sufficient twisted shape is not formed, that is, if the area of ​​the intersection (overlapping part) between the opening and the groove bottom is not small enough, the grip performance in the latter stage cannot be sufficiently improved. Therefore, in the present invention, the area A (mm ２) the area B (mm ２ The ratio X (= B / A) of B to A is set to 95% or less. It is more preferably 90% or less, even more preferably 80% or less, even more preferably 70% or less, even more preferably 60% or less, and even more preferably 50% or less. The lower limit is, for example, preferably 1% or more, more preferably 5% or more, even more preferably 10% or more, even more preferably 20% or more, even more preferably 30% or more, and even more preferably 40% or more.

[0015] (2) Rubber Composition Forming the Tread Portion In the present invention, the tread portion is formed from a rubber composition containing a rubber component, silica, and carbon black, in which the ratio Y (=Si / CB) of the silica content (Si parts by mass) to the carbon black content (CB parts by mass) exceeds 50%.

[0016] It is believed that by including reinforcing agents such as carbon black and silica in the rubber composition, tire wear can be appropriately controlled, the rigidity of the tread portion can be ensured even in the later stages of wear, and grip performance in the later stages can be improved.

[0017] Unlike carbon black, silica's hydration water and surface functional groups capture ozone, improving the tire's ozone resistance, improving tire durability, and ensuring sufficient abrasion resistance. Therefore, in the present invention, the ratio Y (=Si / CB) of the silica content (Si parts by mass) to the carbon black content (CB parts by mass) is set to more than 50%. It is more preferably 70% or more, even more preferably 100% or more, even more preferably 130% or more, even more preferably 160% or more, and even more preferably 200% or more. The upper limit is, for example, preferably 500% or less, more preferably 460% or less, even more preferably 420% or less, even more preferably 380% or less, even more preferably 340% or less, and even more preferably 300% or less.

[0018] (3) X / Y In the present invention, the ratio of X to Y (X / Y) is further controlled to less than 1.5. This allows the effects of the twist sipe and the rubber composition to work together to more appropriately control tire wear, ensuring the rigidity of the tread even in the later stages of wear and improving late grip performance. It is more preferably 1.4 or less, even more preferably 1.2 or less, even more preferably 1.0 or less, even more preferably 0.8 or less, and even more preferably 0.7 or less. The lower limit is preferably 0.01 or more, more preferably 0.03 or more, even more preferably 0.10 or more, even more preferably 0.15 or more, even more preferably 0.20 or more, even more preferably 0.25 or more, and even more preferably 0.32 or more.

[0019] [2] More preferred aspects of the tire according to the present invention The tire according to the present invention can achieve even greater effects by adopting the following aspects.

[0020] 1. Multi-Layered Tread Portion In the tire according to the present invention, the thickness of the tread portion is preferably 10 mm or more and 20 mm or less, more preferably 12 mm or more and 18 mm or less, and even more preferably 14 mm or more and 16 mm or less.

[0021] The tread portion may be formed of only one layer of cap rubber, or may have a base rubber layer on the inside of the cap rubber layer, making it two layers, or may have three layers, or may have four or more layers.

[0022] In this case, the thickness of the cap rubber layer in the entire tread portion is preferably 10% or more, more preferably 30% or more, even more preferably 50% or more, and even more preferably 70% or more, which is thought to enable sufficient friction to be generated between the tread surface and the road surface even in the later stages of wear, further improving the later stage grip performance.

[0023] The thickness of the tread portion mentioned above refers to the thickness of the tread portion on the tire equatorial plane in the tire radial cross section. When the tread portion is formed of a single rubber composition, it refers to the thickness of that rubber composition. When the tread portion is formed of a laminated structure of multiple rubber compositions, it refers to the total thickness of these layers.

[0024] In the present invention, the tread portion refers to the region that forms the contact patch of the tire, and refers to the portion radially outward of the components that contain fiber materials such as the carcass, belt layer, belt reinforcing layer, etc. The thickness of the tread portion can be measured in a cross section cut out in the radial direction of the tire, with the bead portion aligned with the normal rim width.

[0025] Note that a "regular rim" is a rim that is determined for each tire by a standard system that includes the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Manufacturers Association), this refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," in the case of ETRTO (The European Tyre and Rim Technical Organization), this refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and in the case of TRA (The Tire and Rim Association, Inc.), this refers to the "Design Rim" listed in the "YEAR BOOK." Reference is made to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, that standard will be followed. In the case of tires not specified by the standard, it refers to the rim that can be mounted on a rim and can maintain internal pressure, i.e., the rim with the smallest rim diameter and the next narrowest rim width, among rims that do not cause air leakage between the rim and tire.

[0026] 2. Aspect Ratio Aspect ratio is the cross-sectional height of a tire relative to its cross-sectional width, and it is believed that the smaller this ratio (lower aspect ratio) the better the grip performance. On the other hand, if the aspect ratio is too low, it may lead to a deterioration in ride comfort.

[0027] Considering these points, in the tire according to the present invention, the aspect ratio is preferably 30% or more and 60% or less, and more preferably 40% or more and 50% or less.

[0028] The above aspect ratio (%) can be calculated using the tire cross-sectional height Ht (mm), cross-sectional width Wt (mm), tire outer diameter Dt (mm), and rim diameter R (mm) when the internal pressure is set to 250 kPa, using the following formula: Aspect ratio (%) = (Ht / Wt) x 100 (%) Ht = (Dt - R) / 2

[0029] 3. Amount of Styrene in SBR When styrene-butadiene rubber (SBR) with a small amount of styrene (mass ratio) is used as the rubber component in the rubber composition constituting the tread portion of the tire according to the present invention, it is believed that minute styrene domains are formed in the rubber matrix, thereby further improving the grip performance in the later period.

[0030] Specifically, the styrene content of SBR is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, while the lower limit is preferably 4% by mass or more, more preferably 5% by mass or more, and even more preferably 6% by mass or more.

[0031] The above-mentioned SBR with a styrene content of 25% by mass or less means that when a single styrene-containing polymer (SBR) is contained in the rubber component, the styrene content is 25% by mass or less. When a plurality of styrene-containing polymers (SBR) are contained in the rubber component, the styrene content calculated by the sum of the product of the styrene content (% by mass) in each polymer and the blending amount (parts by mass) of that polymer per 100 parts by mass of the rubber component is 25% by mass or less.

[0032] More specifically, when 100 parts by mass of the rubber component contains SBR1 (X1 parts by mass) having a styrene content of S1% by mass and SBR2 (X2 parts by mass) having a styrene content of S2% by mass, the styrene content calculated from the formula {(S1×X1)+(S2×X2)} / (X1+X2) is 25% by mass or less.

[0033] In addition, in the case of a rubber composition after vulcanization, the styrene content can also be calculated by determining the amount of styrene contained in the rubber component after acetone extraction using solid-state nuclear magnetic resonance (solid-state NMR) or Fourier transform infrared spectroscopy (FTIR).

[0034] 4. Silica Particle Diameter As described above, in the present invention, the rubber composition forming the tread portion contains silica, and in this case, the particle diameter (average primary particle diameter) of the silica is preferably 17 nm or less.

[0035] The average primary particle diameter can be calculated by directly observing silica particles extracted from a rubber composition cut out from a tire using a transmission electron microscope (TEM) or the like, calculating the equivalent cross-sectional area diameter from the area of ​​each silica particle obtained, and determining the average value.

[0036] 5. Inclusion of Resin Component In the present invention, the rubber composition forming the tread portion preferably contains a resin component.

[0037] It is believed that by including a resin component in the rubber composition, the adhesiveness of the resin component can maintain grip on the road surface, further improving later grip performance.

[0038] Preferred resin components include rosin-based resins, styrene-based resins, coumarone-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, which will be described later, and of these, terpene-based resins are more preferred.

[0039] [3] Embodiments The present invention will be specifically described below based on embodiments.

[0040] 1. Sipe Fig. 1 shows (a) a schematic perspective view and (b) a schematic plan view illustrating a groove provided in a tire according to the present invention. Fig. 1 shows a sipe provided in one land portion in the tread portion, with 1 representing the land portion, 2 representing an opening, and 3 representing the groove bottom. Also, S represents the intersection of the opening and the groove bottom.

[0041] As shown in FIG. 1( a), the sipe is provided with a twist from the opening 2 to the groove bottom 3, and when viewed in a plan view, an intersection S is formed where the opening 2 and the groove bottom 3 overlap, as shown in FIG. 1( b).

[0042] As described above, by setting the ratio of the area of ​​the intersection S to the area of ​​the opening 2 to 95% or less, the later grip performance can be sufficiently improved.

[0043] 2. Rubber Composition In the present embodiment, the rubber composition constituting the tread can be obtained by kneading various compounding materials such as a rubber component, a reinforcing material, an antioxidant, oil, a resin material, and an antioxidant.

[0044] (1) Compounding Materials (a) Rubber Component The rubber component is not particularly limited, and examples thereof include diene rubbers such as natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), and butyl rubber (IIR). These may be used alone or in combination of two or more, and in the present invention, a combination of SBR and isoprene rubber is preferred.

[0045] (A) SBR The weight-average molecular weight of SBR is, for example, more than 100,000 and less than 2,000,000. The styrene content of SBR is, for example, preferably more than 5% by mass, more preferably more than 10% by mass, and even more 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 even more preferably less than 30% by mass. The vinyl content (amount of 1,2-bonded butadiene units) of SBR is, for example, preferably more than 5% by mass, more preferably more than 10% by mass, and even more 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 even more preferably less than 30% by mass. The structural identification of SBR (measurement of styrene content and vinyl content) can be performed using, for example, a JNM-ECA series instrument manufactured by JEOL Ltd.

[0046] 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 may be either unmodified SBR or modified SBR. Furthermore, hydrogenated SBR, in which the butadiene portion of SBR is hydrogenated, may be used. Hydrogenated SBR may be obtained by subsequently hydrogenating the BR portion of SBR, or a similar structure may be obtained by copolymerizing styrene, ethylene, and butadiene.

[0047] The modified SBR is preferably an SBR having a functional group that interacts with a filler such as silica. Examples include terminal-modified SBR in which at least one terminal of the SBR has been modified with a compound (modifying agent) having the above functional group (terminal-modified SBR having the above functional group at the terminal), main-chain-modified SBR in which the main chain has the above functional group, main-chain-terminal-modified SBR in which the main chain and the terminals have the above functional group (for example, main-chain-terminal-modified SBR in which the main chain has the above functional group and at least one terminal has been modified with the above modifier), and terminal-modified SBR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and into which a hydroxyl group or epoxy group has been introduced.

[0048] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo 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. These functional groups may have a substituent.

[0049] Furthermore, as the modified SBR, for example, SBR modified with a compound (modifier) ​​represented by the following formula can be used.

[0050]

[0051] In the formula, R １ , R ２ and R ３are 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. ４ and R ５ are the same or different and represent a hydrogen atom or an alkyl group. ４ and R ５ may bond to form a ring structure together with the nitrogen atom, and n represents an integer.

[0052] As the modified SBR modified with the compound (modifying agent) represented by the above formula, SBR in which the polymerization terminals (active terminals) of solution-polymerized styrene-butadiene rubber (S-SBR) have been modified with the compound represented by the above formula (such as the modified SBR described in JP 2010-111753 A).

[0053] R １ , R ２ and R ３ is preferably an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). ４ and R ５ is preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. ４ and R ５ When the groups bond to form a ring structure together with the nitrogen atom, the ring is preferably a 4- to 8-membered ring. The alkoxy group also includes a cycloalkoxy group (e.g., a cyclohexyloxy group) and an aryloxy group (e.g., a phenoxy group, a benzyloxy group).

[0054] Specific examples of the modifying agent include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. These may be used alone or in combination of two or more.

[0055] Furthermore, modified SBR modified with the following compounds (modifiers) can also be used as the modified SBR. Examples of the modifier include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups such as diglycidylated bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline; Diglycidylamino compounds such as diglycidyl orthotoluidine, tetraglycidyl meta-xylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamic acid chloride, and N,N-diethylcarbamic acid chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane;(Trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(trippropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxy sulfide group-containing silane compounds such as (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, Alkoxysilanes such as thyltriethoxysilane; (thio)benzophenone compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, and N,N,N',N'-bis-(tetraethylamino)benzophenone; Benzaldehyde compounds having an amino group and / or a substituted amino group, such as dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-t-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, and N-phenyl-2-piperidone;N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurylolactam, N-vinyl-ω-laurylolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam; as well as N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), and tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-triones , N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophen, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone, etc. Modification with the above compounds (modifiers) can be carried out by known methods.

[0056] Examples of SBR that can be used include SBR manufactured and sold by Sumitomo Chemical Co., Ltd., ENEOS Materials Corporation, Asahi Kasei Corporation, and Zeon Corporation. SBR may be used alone or in combination of two or more types.

[0057] The amount of SBR per 100 parts by mass of the rubber component is preferably 35 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, and still more preferably 50 parts by mass or more. The upper limit is, for example, preferably 65 parts by mass or less, more preferably 60 parts by mass or less, and still more preferably 55 parts by mass or less.

[0058] (b) Isoprene-based rubber Examples of isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR, with NR being preferred due to its excellent strength.

[0059] Examples of NR include SVR-L, SIR20, RSS#3, and TSR20, which are commonly used in the tire industry. Examples of IR include IR2200 manufactured by Zeon Corporation, which is commonly used in the tire industry. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

[0060] The content of the isoprene-based rubber in 100 parts by mass of the rubber component is preferably 35 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, and still more preferably 50 parts by mass or more. The upper limit is, for example, preferably 65 parts by mass or less, more preferably 60 parts by mass or less, and still more preferably 55 parts by mass or less.

[0061] (C) BR The rubber composition may contain BR as needed. The weight average molecular weight of the BR is, for example, more than 100,000 and less than 2,000,000. The vinyl content of the BR is, for example, more than 1% by mass and less than 30% by mass. The cis content of the BR is, for example, more than 1% by mass and 98% by mass or less. The trans content of the BR is, for example, more than 1% by mass and less than 60% by mass. The cis content can be measured by infrared absorption spectroscopy.

[0062] The BR is not particularly limited, and can be BR with a high cis content (cis content of 90% or more), BR with a low cis content, BR containing syndiotactic polybutadiene crystals, etc. The BR can be either unmodified BR or modified BR, and the modified BR can be, for example, BR modified with a compound (modifier) ​​represented by the following formula:

[0063]

[0064] In the formula, R １ , R ２ and R ３are 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. ４ and R ５ are the same or different and represent a hydrogen atom or an alkyl group. ４ and R ５ may bond to form a ring structure together with the nitrogen atom, and n represents an integer.

[0065] The modified BR modified with the compound (modifying agent) represented by the above formula includes BR whose polymerization terminal (active terminal) has been modified with the compound represented by the above formula.

[0066] R １ , R ２ and R ３ is preferably an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). ４ and R ５ is preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. ４ and R ５ When the groups bond to form a ring structure together with the nitrogen atom, the ring is preferably a 4- to 8-membered ring. The alkoxy group also includes a cycloalkoxy group (e.g., a cyclohexyloxy group) and an aryloxy group (e.g., a phenoxy group, a benzyloxy group).

[0067] Specific examples of the modifying agent include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. These may be used alone or in combination of two or more.

[0068] The modified BR may also be modified with the following compounds (modifiers): Examples of the modifier include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups such as diglycidylated bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline; Diglycidylamino compounds such as diglycidyl orthotoluidine, tetraglycidyl meta-xylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamic acid chloride, and N,N-diethylcarbamic acid chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane;(Trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(trippropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxy sulfide group-containing silane compounds such as (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyl alkoxysilanes such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, and N,N,N',N'-bis-(tetraethylamino)benzophenone; (thio)benzophenone compounds having an amino group and / or a substituted amino group such as 4-N,N-di Benzaldehyde compounds having an amino group and / or a substituted amino group, such as methylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-t-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, and N-phenyl-2-piperidone;N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurylolactam, N-vinyl-ω-laurylolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam; as well as N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), and tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-triones , N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophen, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone, etc. Modification with the above-mentioned compounds (modifying agents) can be carried out by known methods. These modified BRs may be used alone or in combination of two or more.

[0069] As the BR, for example, products of Ube Industries, Ltd., ENEOS Materials Corporation, Asahi Kasei Corporation, Zeon Corporation, etc. can be used.

[0070] The amount of BR per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and is preferably 25 parts by mass or less, more preferably 20 parts by mass or less.

[0071] (d) Other Rubber Components The rubber composition may contain, as other rubber components, rubbers (polymers) that are generally used in the production of tires, such as nitrile rubber (NBR), as necessary.

[0072] (b) Compounding Materials Other Than Rubber Component (a) Filler The rubber composition contains reinforcing agents such as carbon black and silica as fillers. In addition to carbon black and silica, other fillers include calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc. When silica is used, it is preferable to use it in combination with a silane coupling agent.

[0073] The total amount of filler blended per 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, and still more preferably 90 parts by mass or more. On the other hand, from the viewpoint of dispersibility in the rubber composition, it is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and still more preferably 100 parts by mass or less.

[0074] (i) Carbon Black Carbon black is used for the purpose of improving the crack growth resistance, durability, resistance to ultraviolet degradation, etc. of the tire.

[0075] The nitrogen adsorption specific surface area of ​​carbon black (N ２ From the viewpoint of reinforcing the rubber, SA) is, for example, 30 m ２ / g or more, and ２ / g or more is more preferable, and 60m ２ On the other hand, from the viewpoint of heat buildup, it is more preferable that the solubility is 250 m / g or more. ２ / g or less, and ２ / g or less is more preferable, and 120m ２ The nitrogen adsorption specific surface area of ​​carbon black is measured in accordance with ASTM D4820-93.

[0076] From the viewpoint of rubber rigidity, the dibutyl phthalate (DBP) absorption of carbon black is preferably, for example, 50 ml / 100 g or more, and more preferably 100 ml / 100 g or more. On the other hand, from the viewpoint of rubber compliance with deformation, it is preferably 250 ml / 100 g or less, and more preferably 150 ml / 100 g or less. The DBP absorption of carbon black is measured in accordance with ASTM D2414-93.

[0077] The carbon black is not particularly limited, and examples thereof include furnace blacks (furnace carbon blacks) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black (acetylene carbon black); thermal blacks (thermal carbon blacks) such as FT and MT; and channel blacks (channel carbon blacks) such as EPC, MPC, and CC. These may be used alone or in combination of two or more.

[0078] In addition to carbon black made from mineral oil or the like, biomass-derived carbon black obtained by burning lignin or the like, or recycled carbon black obtained by pyrolyzing and purifying rubber products containing carbon black, such as tires, may be used as appropriate by replacing them in equal amounts.

[0079] Specific carbon blacks are not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available carbon blacks that can be used include, for example, products from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shinnikka Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These may be used alone or in combination of two or more.

[0080] The amount of carbon black per 100 parts by mass of the rubber component is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more. The upper limit is, for example, preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less.

[0081] (ii) Silica The hydration water contained in silica and the functional groups on the surface can capture ozone, improving ozone resistance and improving tire durability.

[0082] As for silica, if the average primary particle diameter is too small, the processability will be poor, so it is preferable to use silica of more than 8 nm.It is more preferable to use silica of 9 nm or more, and even more preferable to use silica of 10 nm or more.On the other hand, from the viewpoint of ensuring the reinforcement of rubber and ensuring the steering stability performance on wet roads during driving, it is preferable to use silica of 25 nm or less, more preferably 20 nm or less, and even more preferably 17 nm or less.

[0083] 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 aggregate structure as a circle and measuring the absolute maximum length of the smallest particle as the diameter of the circle; the average primary particle size of silica can be determined by observing with a transmission or scanning electron microscope, measuring 400 or more primary particles of silica observed within the field of view, and averaging the measured values.

[0084] The BET specific surface area of ​​silica is set to 100 m from the viewpoint of obtaining good durability. ２ / g, and preferably more than 130m ２ On the other hand, it is more preferable that the viscosity is more than 250 m / g. ２ / g, and preferably less than 200m ２ The BET specific surface area is preferably less than N / g as measured by the BET method in accordance with ASTM D3037-93. ２ This is the SA value.

[0085] Examples of silica include dry process silica (anhydrous silica), wet process silica (hydrated silica), and colloidal silica. Among these, wet process silica is preferred because it contains water of hydration and a large number of silanol groups, and can effectively capture ozone. Alternatively, silica made from hydrous glass or silica made from biomass materials such as rice husks may also be used.

[0086] As silica, products available from Evonik Industries, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0087] The content of silica per 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 60 parts by mass or more, more preferably 70 parts by mass or more, and even more preferably 80 parts by mass or more, and from the viewpoint of dispersibility in the rubber composition, the upper limit is preferably 120 parts by mass or less, more preferably 110 parts by mass or less, even more preferably 100 parts by mass or less, and even more preferably 90 parts by mass or less.

[0088] (iii) Silane Coupling Agent When silica is used, it is preferable to use a silane coupling agent in combination in order to increase the dispersibility of the silica and to improve the mechanical properties and moldability by reacting with the silica.

[0089] The silane coupling agent is not particularly limited, 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, and bis(4-trimethoxysilylbutyl)trisulfide. Sulfide, 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-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilyl Examples of suitable silane coupling agents include sulfide-based agents such as ethyl-N,N-dimethylthiocarbamoyl tetrasulfide and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based agents such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based agents such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Of these, preferred are silane coupling agents having a thiocarbonyl group, such as the above-mentioned NXT. These may be used alone or in combination of two or more.

[0090] As the silane coupling agent, for example, products available from Evonik Industries, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Dow Corning Toray Co., Ltd., etc. can be used.

[0091] The content of the silane coupling agent is, for example, preferably more than 2 parts by mass, more preferably more than 3 parts by mass, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more, relative to 100 parts by mass of silica.The upper limit is, for example, preferably less than 15 parts by mass, more preferably 12 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 9 parts by mass or less.

[0092] (iv) Other Fillers In addition to the above-mentioned 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. The content of these fillers is, for example, more than 0.1 part by mass and less than 150 parts by mass per 100 parts by mass of the rubber component.

[0093] (b) Plasticizer Component In consideration of proper dispersion of powder materials during kneading, it is preferable to use a plasticizer component in the rubber composition as needed. The plasticizer component here refers to a component that plasticizes the rubber composition, such as process oil, rubber component extender oil, liquid rubber, or resin component.

[0094] In this case, the content of the plasticizer component per 100 parts by mass of the rubber component is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and still more preferably 30 parts by mass or more. The upper limit is, for example, preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and still more preferably 40 parts by mass or less.

[0095] The content of the plasticizer component also includes the amount of oil contained in rubber (oil-extended rubber) and the like.

[0096] (i) Oil Examples of oil include mineral oil, synthetic oil, vegetable oil, animal oil, and mixtures thereof.

[0097] Examples of mineral oils that can be used include paraffinic, aromatic, and naphthenic oils, and examples of such products that can be used include those manufactured by Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Corporation, H&R Corporation, Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., and Fuji Kosan Co., Ltd. These may be used alone or in combination of two or more.

[0098] From the viewpoint of life cycle assessment, lubricating oils used in the mixers and engines of rubber mixers, waste cooking oils used in restaurants, etc. may be appropriately refined and used as these oils.

[0099] Examples of vegetable oils include linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and wood wax.

[0100] Further examples of vegetable oils include refined oils (such as salad oil) obtained by refining the above oils, interesterified oils, hydrogenated hardened oils, thermally polymerized oils, oxidatively polymerized oils, and waste edible oils recovered from edible oils. Vegetable oils may be liquid or solid at room temperature (25° C.). These may be used alone or in combination of two or more.

[0101] As the vegetable oil, acylglycerol is preferred, and triacylglycerol is more preferred. Acylglycerol refers to a compound in which a hydroxy group of glycerin is ester-bonded to a carboxylic acid. The acylglycerol is not particularly limited, and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, acylglycerol may be a monomer, a dimer, or a polymer of trimer or higher. Dimers or higher acylglycerols can be obtained by thermal polymerization, oxidative polymerization, or the like. Acylglycerol may be liquid or solid at room temperature (25°C).

[0102] The method for confirming whether or not acylglycerol is contained in the rubber composition is not particularly limited, but may be １ For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at room temperature (25°C) for 24 hours, and after removing the rubber composition, the rubber composition is immersed in deuterated chloroform at room temperature. １ When H-NMR was measured, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm when the signal for tetramethylsilane (TMS) was set at 0.00 ppm. These signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atoms of the ester groups, and therefore the presence of acylglycerol can be confirmed. Here, "around" refers to a range of ±0.10 ppm.

[0103] The carboxylic acid is not particularly limited and may be an unsaturated fatty acid or a saturated fatty acid. Examples of the unsaturated fatty acid include monounsaturated fatty acids such as oleic acid and polyunsaturated fatty acids such as linoleic acid and linolenic acid.

[0104] As the vegetable oil, for example, commercially available oils from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Corporation, H&R Corporation, Toyokuni Oil Mills Co., Ltd., Fuji Kosan Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0105] (ii) Liquid Rubber Liquid rubber is a polymer that is in a liquid state at room temperature (25°C) and is a rubber component that can be extracted by acetone extraction from a vulcanized tire. Examples of liquid rubber include farnesene-based polymers, liquid diene-based polymers, and hydrogenated products thereof.

[0106] Farnesene polymers are polymers obtained by polymerizing farnesene, which has structural units based on farnesene. Farnesene exists as an isomer, 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).

[0107] The farnesene-based polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

[0108] Examples of liquid diene polymers include liquid styrene butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene isoprene copolymer (liquid SIR).

[0109] The liquid diene polymer has a weight average molecular weight (Mw) of, for example, 1.0 × 10 in terms of polystyrene measured by gel permeation chromatography (GPC). ３ Super, 2.0×10 ５ Here, the Mw of the liquid diene polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0110] As the liquid rubber, for example, products of Kuraray Co., Ltd., Cray Valley Co., Ltd., etc. can be used.

[0111] (iii) Resin component The resin component also functions as a tackifier, and may be solid or liquid at room temperature. Specific examples of the resin component include rosin resins, styrene resins, coumarone resins, terpene resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, and two or more of these resins may be used in combination. If necessary, these resin components may be provided with a modifying group capable of reacting with silica or the like.

[0112] Rosin-based resins are resins whose main component is rosin acid, which is obtained by processing pine resin. These rosin-based resins (rosins) can be classified based on whether they are modified or not, and can be divided into unmodified rosin (unmodified rosin) and modified rosin (rosin derivatives). Unmodified rosins include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. Modified rosin is a modification of unmodified rosin, and examples thereof include rosin esters, unsaturated carboxylic acid-modified rosin esters, unsaturated carboxylic acid-modified rosin esters, rosin amide compounds, and rosin amine salts.

[0113] The styrene-based resin is a polymer using a styrene-based monomer as a constituent monomer, and examples thereof include polymers obtained by polymerizing a styrene-based monomer as the main component (50% by mass or more).Specific examples include homopolymers obtained by polymerizing each of 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.) alone, copolymers obtained by copolymerizing two or more styrene-based monomers, and copolymers of a styrene-based monomer and another monomer copolymerizable therewith.

[0114] Examples of the other monomer include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene and butadiene isoprene, olefins such as 1-butene and 1-pentene, α,β-unsaturated carboxylic acids or acid anhydrides thereof such as maleic anhydride, and the like.

[0115] Among the coumarone resins, coumarone-indene resins are preferred. Coumarone-indene resins are resins containing coumarone and indene as monomer components constituting the resin skeleton (main chain). Monomer components contained in the skeleton other than coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0116] 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 is the amount of potassium hydroxide, expressed in milligrams, required to neutralize acetic acid bonded to hydroxyl groups when acetylating 1 g of the resin, and is a value measured by potentiometric titration (JIS K 0070:1992).

[0117] The softening point of the coumarone-indene resin is, for example, more than 30° C. and less than 160° C. The softening point is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point tester.

[0118] 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 compounds having a molecular weight of (C ５ H ８ ) ｎ Monoterpenes (C １０ H １６ ), sesquiterpenes (C １５ H ２４ ), diterpenes (C ２０ H ３２), and examples thereof include 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, and γ-terpineol.

[0119] Examples of polyterpenes include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin, which are made from the above-mentioned terpene compounds, as well as hydrogenated terpene resins obtained by hydrogenating the terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the above-mentioned terpene compounds with phenolic compounds, and resins obtained by hydrogenating the above-mentioned resins. Specific examples include resins obtained by condensing the above-mentioned terpene compounds, phenolic compounds, and formalin. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Examples of aromatic-modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the above-mentioned resins. The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring, and examples thereof include phenolic compounds such as phenol, alkylphenol, alkoxyphenol, and unsaturated hydrocarbon group-containing phenol; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and unsaturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; coumarone, indene, and the like.

[0120] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions having 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferably used as a C5 petroleum resin.

[0121] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a hydrogenated or modified version. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples include coumarone-indene resin, coumarone resin, indene resin, and aromatic vinyl resin. Preferred aromatic vinyl resins are α-methylstyrene (AMS resin), styrene homopolymers, and copolymers of α-methylstyrene and styrene, with copolymers of α-methylstyrene and styrene being more preferred, due to their economical efficiency, ease of processing, and excellent heat generation. Examples of aromatic vinyl resins that can be used include those commercially available from Kraton, Eastman Chemical, and the like.

[0122] The term "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified resin. Examples of the C5 fraction and the C9 fraction include the petroleum fractions mentioned above. As the C5C9 resin, for example, commercially available resins from Tosoh Corporation, LUHUA Corporation, etc. can be used.

[0123] The acrylic resin is not particularly limited, but for example, a solventless acrylic resin can be used.

[0124] Examples of solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized by high-temperature continuous polymerization (high-temperature continuous bulk polymerization) (methods described in U.S. Pat. No. 4,414,370, JP-A No. 59-6207, JP-B No. 5-58005, JP-A No. 1-313522, U.S. Pat. No. 5,010,166, and Toa Gosei Kenkyusho Annual Report TREND 2000 Vol. 3, pp. 42-45, etc.), with minimal use of secondary raw materials such as polymerization initiators, chain transfer agents, and organic solvents. In the present invention, (meth)acrylic refers to both methacrylic and acrylic.

[0125] Examples of the monomer components constituting the acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (such as alkyl esters, aryl esters, and aralkyl esters), (meth)acrylamide, and (meth)acrylic acid derivatives such as (meth)acrylamide derivatives.

[0126] Furthermore, aromatic vinyls 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 as a monomer component constituting the acrylic resin.

[0127] The acrylic resin may be a resin composed solely of a (meth)acrylic component, or a resin containing components other than a (meth)acrylic component, and may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

[0128] As the resin component, for example, products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Clayton, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Co., Ltd., and the like can be used.

[0129] (c) Lubricant (Stearic Acid) The rubber composition may contain a lubricant. A lubricant based on a fatty acid derivative such as stearic acid is preferably used as the lubricant. Conventionally known stearic acids can be used, and specifically, for example, products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used. Struktol WB16 manufactured by Struktol Co., Ltd. can also be used.

[0130] The amount of stearic acid per 100 parts by mass of the rubber component is, for example, preferably more than 0.5 parts by mass and less than 10.0 parts by mass.

[0131] (D) Antiaging Agent 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 per 100 parts by mass of the rubber component.

[0132] Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine. p-phenylenediamine-based antioxidants such as quinolone; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. These antioxidants may be used alone or in combination of two or more.

[0133] Specific examples of antioxidants that can be used include products from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, and the like.

[0134] (e) Zinc Oxide The rubber composition may contain zinc oxide. The content of zinc oxide is, for example, more than 0.5 parts by mass and less than 10 parts by mass per 100 parts by mass of the rubber component. As the zinc oxide, a conventionally known product can be used, and for example, products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0135] (F) Wax The rubber composition may contain wax. The content of the wax relative to 100 parts by mass of the rubber component 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.

[0136] The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as vegetable wax and animal wax; and synthetic waxes such as polymers of ethylene, propylene, etc. These may be used alone or in combination of two or more.

[0137] As the wax, for example, products from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used.

[0138] (G) Crosslinking Agent and Vulcanization Accelerator The rubber composition preferably contains a crosslinking agent such as sulfur. The content of the crosslinking agent is, for example, more than 0.1 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component. The sulfur content is the pure sulfur content, and when insoluble sulfur is used, it is the content excluding oil content.

[0139] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. These may be used alone or in combination of two or more.

[0140] As sulfur, for example, products from Tsurumi Chemical Industry Co., Ltd., Karuizawa Iso Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0141] Crosslinking agents other than sulfur may also be used. Specifically, for example, vulcanizing agents containing sulfur atoms such as TACKIROL V200 manufactured by Taoka Chemical Co., Ltd., DURALINK HTS (1,6-hexamethylene-sodium dithiosulfate dihydrate) manufactured by Flexis, and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane: hybrid crosslinking agent) manufactured by LANXESS, and organic peroxides such as dicumyl peroxide can be used.

[0142] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator per 100 parts by mass of the rubber component is, for example, more than 0.3 parts by mass and less than 10.0 parts by mass.

[0143] Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, N-t-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenyl guanidine, di-orthotolyl guanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more.

[0144] (H) Others In addition to the above-mentioned components, the rubber composition may contain additives commonly used in the tire industry, such as organic fillers such as cellulose fibers, organic peroxides, etc. The content of these additives is, for example, more than 0.1 parts by mass and less than 50 parts by mass per 100 parts by mass of the rubber component.

[0145] (2) Preparation of Rubber Composition The rubber composition can be prepared by a general method, for example, a production method including a base kneading step of kneading a rubber component with a filler such as carbon black, and a finish kneading step of kneading the kneaded product obtained in the base kneading step with a crosslinking agent.

[0146] The kneading can be carried out using a known (internal) kneading machine such as a Banbury mixer, a kneader, or an open roll.

[0147] The kneading temperature in the base kneading step is, for example, higher than 50° C. and lower than 200° C., and the kneading time is, for example, higher than 30 seconds and lower than 30 minutes. In the base kneading step, in addition to the above components, compounding agents conventionally used in the rubber industry, for example, softeners such as oil, stearic acid, zinc oxide, antioxidants, waxes, vulcanization accelerators, etc., may be appropriately added and kneaded as needed.

[0148] In the final kneading step, the kneaded product obtained in the base kneading step is kneaded with a crosslinking agent. The kneading temperature in the final kneading step is, for example, higher than room temperature and lower than 80°C, and the kneading time is, for example, longer than 1 minute and shorter than 15 minutes. In the final kneading step, in addition to the above components, a vulcanization accelerator, zinc oxide, etc. may be appropriately added and kneaded as necessary.

[0149] The rubber composition obtained as described above can then be extruded into a predetermined shape to form a tread.

[0150] 3. Tire Manufacturing The tire according to the present embodiment can be manufactured by a conventional method. First, the rubber composition obtained as described above is molded into a predetermined shape to manufacture a tread. Next, the rubber composition is combined with other rubber components on a tire building machine to manufacture an unvulcanized tire.

[0151] Specifically, an inner liner as a component for ensuring the airtightness of the tire, a carcass as a component for withstanding the load, impact, and inflation pressure to which the tire is subjected, and a belt component as a component for tightly fastening the carcass and increasing the rigidity of the tread are wound around a forming drum, and both ends of the carcass are fixed to both side edges, and bead portions as components for fixing the tire to the rim are arranged. After forming into a toroidal shape, a tread is attached to the center of the outer periphery and sidewalls are attached to the radially outer sides to form side portions, thereby producing an unvulcanized tire.

[0152] The unvulcanized tire thus produced is then heated and pressurized in a vulcanizer to obtain a tire. The vulcanization step can be carried out by applying a known vulcanization method. The vulcanization temperature is, for example, higher than 120°C and lower than 200°C, and the vulcanization time is, for example, longer than 5 minutes and shorter than 15 minutes.

[0153] As described above, the tire obtained as described above more appropriately controls tire wear due to the combined effect of the sipes formed with an appropriate twist and the effect of the rubber composition prepared with an appropriate silica / carbon black ratio, thereby ensuring rigidity of the tread portion even in the later stages of wear and improving later grip performance.

[0154] The tire according to the present invention can be suitably used as a passenger car tire, a large passenger car tire, a large SUV tire, a truck / bus tire, a motorcycle 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.

[0155] Below, examples (embodiments) that are considered preferable for implementation will be shown, but the scope of the present invention is not limited to these examples.

[0156] Table 1 shows the results of calculations based on the grip performance evaluation method in the later stages of wear described below, assuming a tire (tire size: 175 / 60R18) made of a tread molded from the various compounded materials shown below and other rubber components.

[0157] 1. Preparation of Rubber Composition A rubber composition for tread is prepared using the various compounding materials shown below.

[0158] (1) Compounding Materials (a) Rubber Component (a) NR: TSR20 (b) SBR: HPR840 (S-SBR) manufactured by ENEOS Materials Corporation (styrene content: 10% by mass, vinyl content: 42% by mass)

[0159] (b) Compounding materials other than rubber components (a) Carbon black: Diablack N220 (N) manufactured by Mitsubishi Chemical Corporation ２ SA: 115m 2 / g) (b) Silica: Ultrasil VN3 (N) manufactured by Eponic Industries ２ SA: 175m 2 / g, average primary particle size: 17 nm) (c) Silane coupling agent: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Corporation (d) Oil: Process oil A / OMIX manufactured by Sankyo Yuka Kogyo Co., Ltd. (e) Resin: YS Resin PX850 manufactured by Yasuhara Chemical Co., Ltd. (softening point 85°C, β-pinene resin (terpene resin)) (f) Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. (g) Antioxidant-1: Nocrac 6C (N-(1,3 dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (h) Antioxidant-2: Nocrac RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (i) Stearic acid: Beaded stearic acid "Tsubaki" manufactured by NOF Corporation (j) Zinc oxide: Zinc oxide type 2 manufactured by Mitsui Mining & Smelting Co., Ltd. (k) Sulfur: Powdered sulfur manufactured by Karuizawa Iso Co., Ltd. (l) Accelerator-1: Noccela CZ-G (CBS) (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (m) Accelerator-2: Noccela D (DPG) (1,3-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0160] (2) Preparation of Rubber Composition for Tread Based on each formulation shown in Table 1, materials other than sulfur and vulcanization accelerator are kneaded for 5 minutes under the condition of 150°C using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded mixture.

[0161] Next, sulfur and a vulcanization accelerator are added to the kneaded mixture, and the mixture is kneaded for 5 minutes at 80° C. using an open roll to obtain each rubber composition for tread.

[0162] 2. Molding of Tread Next, the rubber composition obtained above is molded into a tread of a predetermined shape having a width of 2 mm or less, a depth of 20 mm or less, and twisted sipes formed therein such that the ratio X of the area of ​​the intersection of the opening and the groove bottom is 95% or less.

[0163] 3. Tire Manufacturing Next, the tread obtained above was laminated together with other tire components to form an unvulcanized tire, which was then press-vulcanized at 170°C for 10 minutes to manufacture test tires for Examples 1 to 4 and Comparative Examples 1 to 4.

[0164] 4. Performance evaluation test (evaluation of grip performance in the later stages of wear) Each test tire was fitted to all wheels of a vehicle (a domestically produced FF vehicle with an engine displacement of 2,000 cc), and the vehicle was inflated with air to an internal pressure of 230 kPa. After the vehicle was driven for 30,000 km, the actual vehicle was driven on a test course with a dry asphalt surface, and the driving time was measured.

[0165] Also, as a reference tire, a tire manufactured by replacing all of the SBR in the compounding of Comparative Example 3 with NR is used, and the running time is measured in the same manner.

[0166] Then, the running time saved by each test tire is calculated based on the running time of the reference tire.

[0167] Next, the reduced running time in Comparative Example 1 is set as 100, and the result is indexed based on the following formula to evaluate the grip performance in the later stages of wear. The larger the value, the better the grip performance in the later stages of wear. Grip performance in the later stages of wear = [(Test tire results) / (Comparative Example 1 results)] x 100

[0168]

[0169] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments. Various modifications can be made to the above-described embodiments within the scope of the same or equivalent to the present invention.

[0170] The present invention (1) is a tire having a tread portion, wherein a groove having a width of 2 mm or less and a depth of 20 mm or less is formed in a land portion on the surface of the tread portion, the groove having an opening facing the surface of the tread portion and a groove bottom, the opening and the groove bottom intersect when the surface of the tread portion is viewed in a plane, a ratio X of an area of ​​an intersection of the opening and the groove bottom to an area of ​​the opening when the surface of the tread portion is viewed in a plane is 95% or less, the tread portion is formed from a rubber composition containing a rubber component, silica, and carbon black, and a ratio Y of a content (parts by mass) of the silica to a content (parts by mass) of the carbon black exceeds 50%, and further, X / Y<1.5.

[0171] The present invention (2) is the tire according to the present invention (1), characterized in that the X is 80% or less.

[0172] The present invention (3) is the tire according to the present invention (2), characterized in that the X is 60% or less.

[0173] The present invention (4) is characterized in that the X is 1% or more, and is a tire in any combination with any of the present inventions (1) to (3).

[0174] The present invention (5) is characterized in that the Y is 100% or more, and is a tire in any combination with any of the present inventions (1) to (4).

[0175] The present invention (6) is the tire according to the present invention (5), characterized in that the Y is 200% or more.

[0176] The present invention (7) is characterized in that the Y is 380% or less, and is a tire in any combination with any of the present inventions (1) to (6).

[0177] The present invention (8) is characterized in that the X / Y is 1.2 or less, and is a tire in any combination with any of the present inventions (1) to (7).

[0178] The present invention (9) is the tire according to the present invention (8), characterized in that the X / Y is 0.8 or less.

[0179] The present invention (10) is characterized in that the X / Y is 0.03 or more, and is a tire in any combination with any of the present inventions (1) to (9).

[0180] The present invention (11) is a tire characterized in that the thickness of the tread portion is 10 mm or more and 20 mm or less, and is an arbitrary combination with any of the present inventions (1) to (10).

[0181] The present invention (12) is characterized in that the tread portion is formed of a plurality of layers with a cap rubber layer as the outermost layer, and is a tire in any combination with any of the present inventions (1) to (11).

[0182] The present invention (13) is the tire according to the present invention (12), characterized in that the thickness of the cap rubber layer in the entire tread portion is 10% or more.

[0183] The present invention (14) is the tire according to the present invention (13), characterized in that the thickness of the cap rubber layer in the entire tread portion is 70% or more.

[0184] The present invention (15) is a tire characterized by having an aspect ratio of 30% or more and 60% or less, and is an optional combination with any of the present inventions (1) to (14).

[0185] The present invention (16) is characterized in that the rubber composition contains styrene-butadiene rubber (SBR) having a styrene content of 25 mass % or less, and is a tire in any combination with any of the present inventions (1) to (15).

[0186] The present invention (17) is the tire according to the present invention (16), characterized in that the content of the styrene-butadiene rubber (SBR) in 100 parts by mass of the rubber component is 40 parts by mass or more.

[0187] The present invention (18) is characterized in that the content of the isoprene-based rubber in 100 parts by mass of the rubber component of the rubber composition is 40 parts by mass or more, and is a tire in any combination with any of the present inventions (1) to (17).

[0188] The present invention (19) is a tire characterized in that the particle diameter of the silica is 17 nm or less, and is any combination with any of the present inventions (1) to (18).

[0189] The present invention (20) is characterized in that the rubber composition contains at least one resin component selected from a rosin-based resin, a styrene-based resin, a coumarone-based resin, a terpene-based resin, a C5 resin, a C9 resin, a C5C9 resin, and an acrylic resin, and is a tire in any combination with any of the present inventions (1) to (19).

[0190] 1 Land part 2 Opening part 3 Groove bottom S Intersection part

Claims

1. A tire having a tread portion, wherein a groove having an opening facing the surface of the tread portion and a groove bottom, the opening and the groove bottom intersect when the surface of the tread portion is viewed in plan, and a ratio X of an area of ​​the intersection of the opening and the groove bottom to an area of ​​the opening when the surface of the tread portion is viewed in plan is 95% or less, the tread portion is formed from a rubber composition containing a rubber component, silica, and carbon black, and a ratio Y of the silica content (parts by mass) to the carbon black content (parts by mass) exceeds 50%, and further wherein X / Y<1.

5.

2. The tire according to claim 1, wherein said X is 80% or less.

3. The tire according to claim 2, wherein said X is 60% or less.

4. A tire according to any one of claims 1 to 3, characterized in that X is 1% or more.

5. A tire according to any one of claims 1 to 4, characterized in that Y is 100% or more.

6. The tire according to claim 5, wherein said Y is 200% or more.

7. A tire according to any one of claims 1 to 6, characterized in that the Y is 380% or less.

8. A tire according to any one of claims 1 to 7, characterized in that the X / Y ratio is 1.2 or less.

9. The tire according to claim 8, wherein said X / Y is 0.8 or less.

10. A tire according to any one of claims 1 to 9, characterized in that the X / Y ratio is 0.03 or more.

11. A tire according to any one of claims 1 to 10, characterized in that the thickness of the tread portion is not less than 10 mm and not more than 20 mm.

12. A tire according to any one of claims 1 to 11, characterized in that the tread portion is formed from a plurality of layers with a cap rubber layer being the outermost layer.

13. The tire according to claim 12, wherein the thickness of said cap rubber layer in the entire tread portion is 10% or more.

14. The tire according to claim 13, wherein the thickness of said cap rubber layer in the entire tread portion is 70% or more.

15. A tire according to any one of claims 1 to 14, characterized in that the aspect ratio is 30% or more and 60% or less.

16. A tire according to any one of claims 1 to 15, characterized in that the rubber composition contains styrene-butadiene rubber (SBR) having a styrene content of 25 mass % or less.

17. The tire according to claim 16, characterized in that the content of the styrene-butadiene rubber (SBR) in 100 parts by mass of the rubber component is 40 parts by mass or more.

18. A tire according to any one of claims 1 to 17, characterized in that the content of isoprene-based rubber in 100 parts by mass of the rubber component of the rubber composition is 40 parts by mass or more.

19. A tire according to any one of claims 1 to 18, characterized in that the particle size of the silica is 17 nm or less.

20. A tire described in any one of claims 1 to 19, characterized in that the rubber composition contains at least one resin component selected from rosin-based resins, styrene-based resins, coumarone-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins.

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