Tire

Abstract

To provide a tire, which is further improved in grip performance in a later term.SOLUTION: A tire comprises a tread part. Grooves whose widths are 2 mm or less and whose depths are 20 mm or less having opening parts and groove bottom parts facing a surface of the tread part are formed on a land part on the surface of the tread part. The opening parts cross the groove bottom parts, when the surface of the tread part is viewed from top. A ratio X of areas of crossing parts between the opening parts and the groove bottom parts to areas of the opening parts when the surface of the tread part is viewed from top is 95% or less. The tread part includes rubber ingredients, silica and carbon black and is formed of rubber compositions in which a ratio Y of contents (mass parts) of silica to contents (mass parts) of carbon black is over 50%, where X and Y satisfy a relational expression of X / Y<1.5.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] In recent years, there has been a demand for improving the grip performance (late-stage grip performance) of tires in a state where the tread is worn due to driving (late wear stage), and various techniques have been proposed for this purpose (for example, Patent Document 1), but they are not yet sufficient, and further improvement is required.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

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

Means for Solving the Problems

[0005] The present invention is a tire including a tread portion, wherein a groove having a width of 2 mm or less and a depth of 20 mm or less, which has an opening facing the surface of the tread portion and a groove bottom, is formed in a land portion on the surface of the tread portion, the opening and the groove bottom intersect when the surface of the tread portion is viewed in plan, a ratio X of an area of an intersection portion between 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 of a rubber composition containing a rubber component, silica, and carbon black, and the ratio Y of the content (parts by mass) of silica to the content (parts by mass) of carbon black is more than 50%. Furthermore, the tire is characterized in that X / Y < 1.5.

Advantages of the Invention

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

Brief Description of the Drawings

[0007]

Figure 1

Embodiments for Carrying Out the Invention

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

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

[0010] By having these features, as will be described later, it is possible to improve the late grip performance of the tire.

[0011] 2. Mechanism of Effect Expression in the Tire According to the Present Invention Regarding the mechanism of the above-described effect expression in the tire according to the present invention, it is considered as follows.

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

[0013] By providing such a twisted-shaped sipe on the surface of the tread portion, it is considered that the wear of the tire can be appropriately controlled, and even in the late stage of wear, the rigidity of the tread portion can be ensured, and the late grip performance can be improved.

[0014] At this time, if a sufficient twisted shape is not formed, that is, if the area of the intersection portion (overlap portion) of the opening portion and the groove bottom portion is not sufficiently small, the late grip performance cannot be sufficiently improved. Therefore, in the present invention, the ratio X (= B / A) of the area B (mm 2 ) of the intersection portion of the opening portion and the groove bottom portion to the area A (mm 2 ) of the opening portion when the surface of the tread portion is viewed in plan is set to 95% or less. It is more preferably 90% or less, further preferably 80% or less, further preferably 70% or less, further preferably 60% or less, and further preferably 50% or less. As the lower limit, for example, it is preferably 1% or more, more preferably 5% or more, further preferably 10% or more, further preferably 20% or more, further preferably 30% or more, and further preferably 40% or more.

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

[0016] By containing carbon black and silica, which are reinforcing agents, in the rubber composition, it is considered that the wear of the tire can be appropriately controlled, the rigidity of the tread portion can be ensured even in the later stage of wear, and the grip performance in the later stage can be improved.

[0017] At this time, different from carbon black, the contained water of hydration and surface functional groups of silica capture ozone to improve the ozone resistance of the tire, and while the durability of the tire is improved, sufficient abrasion resistance can be ensured. 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, still more preferably 100% or more, still more preferably 130% or more, still more preferably 160% or more, and still more preferably 200% or more. As the upper limit, for example, it is preferably 500% or less, more preferably 460% or less, still more preferably 420% or less, still more preferably 380% or less, still more preferably 340% or less, and still more preferably 300% or less.

[0018] (3) X / Y In the present invention, further, the ratio of X to Y (X / Y) described above is controlled to be less than 1.5. Thereby, the effect in the above-described twist cycle and the effect in the rubber composition cooperate to more appropriately control the wear of the tire, and even in the late stage of wear, the rigidity of the tread portion can be ensured, and it is considered that the late-stage grip performance can be improved. It is more preferably 1.4 or less, further preferably 1.2 or less, still further preferably 1.0 or less, and still further preferably 0.8 or less. As the lower limit, it is preferably 0.01 or more, more preferably 0.03 or more, still further preferably 0.10 or more, still further preferably 0.15 or more, still further preferably 0.20 or more, and still further preferably 0.25 or more.

[0019] [2] More preferred embodiments of the tire according to the present invention The tire according to the present invention can obtain a greater effect by adopting the following embodiments.

[0020] 1. Lamination of the tread portion In the tire according to the present invention, the preferred thickness of the tread portion is 10 mm or more and 20 mm or less, more preferably 12 mm or more and 18 mm or less, and still more preferably 14 mm or more and 16 mm or less.

[0021] Note that the tread portion may be formed of only one layer of cap rubber layer, but a base rubber layer may be provided inside the cap rubber layer to form two layers, or three layers, or 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, still further preferably 50% or more, and still further preferably 70% or more. Thereby, it is considered that sufficient friction can be generated between the tread portion surface and the road surface even in the late stage of wear, and the late-stage grip performance can be further improved.

[0023] The thickness of the tread portion described 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 is the thickness of the rubber composition, and when it is formed of a laminated structure of a plurality of rubber compositions, it refers to the total thickness of these layers.

[0024] In the present invention, the tread portion is a member in the region forming the ground contact surface of the tire, but refers to the portion outside the tire in the radial direction from members including fiber materials such as carcass, belt layer, and belt reinforcing layer. Further, the thickness of the tread portion described above can be measured by making the bead portion in a state where it is adjusted to the normal rim width in the cross-section obtained by cutting the tire in the radial direction.

[0025] The "normal rim" is the rim defined for each tire in the standard system including the standards on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it is the standard rim in the applicable sizes described in the "JATMA YEAR BOOK", in the case of ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" described in the "STANDARDS MANUAL", and in the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" described in the "YEAR BOOK". Refer to JATMA, ETRTO, and TRA in this order, and follow the standard if there is an applicable size at the time of reference. And in the case of a tire not defined by the standard, it refers to the rim that can be assembled with the tire and can hold the internal pressure, that is, among the rims that do not cause air leakage between the rim / tire, the one with the smallest rim diameter and then the narrowest rim width.

[0026] 2. Aspect ratio The aspect ratio is the cross-sectional height with respect to the tire cross-sectional width, and it is considered that the smaller this ratio (lower aspect ratio), the better the grip performance. On the other hand, if the aspect ratio becomes too low, there is a risk of deterioration in the riding comfort performance.

[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] Note that the above aspect ratio (%) can be obtained by the following formula 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 250 kPa. Aspect ratio (%) = (Ht / Wt) × 100 (%) Ht = (Dt - R) / 2

[0029] 3. Styrene content in SBR In the rubber composition constituting the tread portion of the tire according to the present invention, when styrene-butadiene rubber (SBR) with a low styrene content (mass ratio) is used as the rubber component, it is considered that minute styrene domains are formed in the rubber matrix, thereby further improving the late grip performance.

[0030] Specifically, SBR with a styrene content of 25% by mass or less is preferable, more preferably 20% by mass or less, and even more preferably 15% by mass or less. On the other hand, as the lower limit, it is preferably 4% by mass or more, more preferably 5% by mass or more, and even more preferably 6% by mass or more.

[0031] Note that the above SBR with a styrene content of 25% by mass or less means that when a styrene-containing polymer (SBR) is contained alone in the rubber component, the styrene content is 25% by mass or less, and when a plurality of styrene-containing polymers (SBR) are contained in the rubber component, the styrene content is determined by the sum of the product of the styrene content (% by mass) in each polymer and the compounding amount (parts by mass) of that polymer with respect to 100 parts by mass of the rubber component, indicating that the styrene content is 25% by mass or less.

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

[0033] Also, in the vulcanized rubber composition, it is also possible to calculate the styrene content contained in the rubber component after acetone extraction by using solid nuclear magnetic resonance (solid NMR) or Fourier transform infrared spectrophotometer (FTIR).

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

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

[0036] 5. Containment of resin component In the present invention, it is preferable that the rubber composition forming the tread portion contains a resin component.

[0037] By containing a resin component in the rubber composition, it is considered that the grip performance with respect to the road surface can be maintained by the adhesiveness of the resin component, and the late grip performance can be further improved.

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

[0039] [3] Embodiment Hereinafter, the present invention will be specifically described based on the embodiment.

[0040] 1. Sipe FIG. 1 is a (a) schematic perspective view and (b) schematic plan view for explaining a groove provided in a tire according to the present invention. In FIG. 1, a sipe provided in one land portion in the tread portion is shown, where 1 is the land portion, 2 is the opening portion, and 3 is the groove bottom portion. Also, S is the intersection portion between the opening portion and the groove bottom portion.

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

[0042] And, as described above, by setting the ratio of the area of the intersection portion S to the area of the opening portion 2 to 95% or less, the late 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, an oil, a resin material, and an antioxidant.

[0044] (1) Compounding materials (a) Rubber component The rubber component is not particularly limited. For example, 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) can be used. These may be used alone or in combination of two or more. In the present invention, the combined use of SBR and isoprene rubber is preferred.

[0045] (i) SBR 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 preferably, for example, 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 the SBR is preferably, for example, 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. Incidentally, the structure identification (measurement of styrene content and vinyl content) of the SBR can be carried out, for example, using an apparatus of the JNM-ECA series 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 non-modified SBR or modified SBR. Further, hydrogenated SBR obtained by hydrogenating the butadiene part in the SBR may be used, and the hydrogenated SBR may be obtained by subjecting the BR part in the SBR to a post-hydrogenation treatment, or styrene, ethylene, and butadiene may be copolymerized to obtain a similar structure.

[0047] The modified SBR is preferably an SBR having a functional group that interacts with a filler such as silica. For example, a terminal-modified SBR (terminal-modified SBR having the above functional group at the terminal) in which at least one terminal of the SBR is modified with a compound (modifying agent) having the above functional group, 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 at least one terminal modified with the above modifying agent), and a terminal-modified SBR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or an epoxy group introduced therein, etc. may be mentioned.

[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 substituents.

[0049] As the modified SBR, for example, SBR modified with a compound (modifying agent) represented by the following formula can be used.

[0050]

Chemical formula

[0051] 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 derivatives 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 combine to form a ring structure together with the nitrogen atom. 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 terminal (active terminal) of solution-polymerized styrene-butadiene rubber (S-SBR) is modified with the compound represented by the above formula (modified SBR described in JP-A-2010-111753, etc.) can be used.

[0053] R 1 , R 2 and R 3As the [group], an alkoxy group is preferred (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms). R 4 and R 5 As the [group], an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is preferred. n is preferably 1 to 5, more preferably 2 to 4, and still more preferably 3. Also, R 4 and R 5 When they are bonded to form a ring structure together with the nitrogen atom, a 4- to 8-membered ring is preferred. Note that the alkoxy group includes a cycloalkoxy group (such as a cyclohexyloxy group) and an aryloxy group (such as a phenoxy group and a benzyloxy group).

[0054] Specific examples of the above-mentioned modifier 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] In addition, as the modified SBR, 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, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, 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, polyepoxidized liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine, 4,4'-diglycidyl-dibenzylmethylamine; diglycidylamino compounds such as diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl orthotoluidine, tetraglycidyl metaxylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, 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, N,N-diethylcarbamic acid chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane, (3-glycidyloxypropyl)-pentamethyldisiloxane;(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 and other sulfide group-containing silane compounds; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; alkoxysilanes such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltriethoxysilane; (thio)benzophenone compounds having 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, N,N,N',N'-bis-(tetraethylamino)benzophenone; benzaldehyde compounds having an amino group and / or a substituted amino group such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-t-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; In addition, N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-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-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone and the like can be mentioned. The modification with the above compounds (modifying agents) can be carried out by known methods.;

[0056] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., ENEOS MATERIALS Co., Ltd., Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd. and the like can be used. The SBR may be used alone or in combination of two or more kinds.;

[0057] The content of SBR 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, and still more preferably 45 parts by mass or more. The upper limit is preferably, for example, 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 rubber Examples of the isoprene rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, etc. NR is preferred in terms of excellent strength.;

[0059] As the NR, for example, those commonly used in the tire industry such as SVR-L, SIR20, RSS#3, TSR20, etc. can be used. As the IR, there is no particular limitation, and for example, those commonly used in the tire industry such as IR2200 manufactured by Nippon Zeon Co., Ltd. can be used. As the modified NR, deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. can be used. As the modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. can be used. As the modified IR, epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. can be mentioned. These may be used alone or in combination of two or more.

[0060] The content of isoprene 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, and even more preferably 45 parts by mass or more. As the upper limit, for example, it is preferably 65 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less.

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

[0062] There is no particular limitation on the BR, and BR with a high cis content (cis content of 90% or more), BR with a low cis content, BR containing syndiotactic polybutadiene crystal, etc. can be used. The BR may be either unmodified BR or modified BR. As the modified BR, for example, BR modified with a compound (modifying agent) represented by the following formula can be used.

[0063]

Chemical formula

[0064] 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 combine to form a ring structure together with a nitrogen atom. n represents an integer.

[0065] Examples of the modified BR modified by the compound (modifying agent) represented by the above formula include BR in which the polymerization terminal (active terminal) is modified by 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 1 to 4 carbon atoms). R 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 still more preferably 3. Also, when R 4 and R 5 combine to form a ring structure together with a nitrogen atom, a 4- to 8-membered ring is preferable. Note that the alkoxy group includes a cycloalkoxy group (such as a cyclohexyloxy group) and an aryloxy group (such as a phenoxy group and a benzyloxy group).

[0067] Specific examples of the above-mentioned modifier include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, and the like. These may be used alone or in combination of two or more.

[0068] In addition, as the modified BR, modified BR 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, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, 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, polyepoxidized liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine, 4,4'-diglycidyl-dibenzylmethylamine; diglycidylamino compounds such as diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl orthotoluidine, tetraglycidyl metaxylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, 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, N,N-diethylcarbamic acid chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane, (3-glycidyloxypropyl)-pentamethyldisiloxane;(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 and other sulfide group-containing silane compounds; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; alkoxysilanes such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltriethoxysilane; (thio)benzophenone compounds having 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, N,N,N',N'-bis-(tetraethylamino)benzophenone; benzaldehyde compounds having an amino group and / or a substituted amino group such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-t-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; In addition, N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-triones, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethyl ethyleneurea, 1,3-divinyl ethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone and the like can be mentioned. In addition, the modification with the above compounds (modifying agents) can be carried out by known methods. These modified BRs may be used alone or in combination of two or more kinds.;

[0069] As BR, for example, products of Ube Industries, Ltd., ENEOS MATERIALS Co., Ltd., Asahi Kasei Corporation, Nippon Zeon Co., Ltd. and the like can be used.

[0070] The content of BR in 100 parts by mass of the rubber component is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more. On the other hand, it is preferably 25 parts by mass or less, and more preferably 20 parts by mass or less.

[0071] (ii) Other rubber components The rubber composition may contain, as other rubber components, rubber (polymer) generally used in the production of tires such as nitrile rubber (NBR) as required.

[0072] (b) Compound materials other than rubber components (i) Filler The rubber composition contains, as a filler, a reinforcing agent such as carbon black or silica. In addition, examples of the filler include, in addition to carbon black and silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, and the like. When silica is used, it is preferably used in combination with a silane coupling agent.

[0073] The total blending amount of the filler is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, with respect to 100 parts by mass of the rubber component. On the other hand, from the viewpoint of dispersibility in the rubber composition, it is preferably 150 parts by mass or less, 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, ultraviolet degradation resistance, etc. of tires.

[0075] The nitrogen adsorption specific surface area (N2SA) of carbon black is, from the viewpoint of reinforcement to rubber, for example, preferably 30 m 2 / g or more, more preferably 50 m 2 / g or more, and even more preferably 60 m 2 / g or more. On the other hand, from the viewpoint of heat generation, it is preferably 250 m 2 / g or less, more preferably 150 m 2 / g or less, and even more preferably 120 m 2 / g or less. The nitrogen adsorption specific surface area of carbon black is measured according to ASTM D4820-93.

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

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

[0078] In addition to carbon black made from mineral oil and the like, carbon black derived from biomass obtained by burning lignin and the like, and recycled carbon black obtained by pyrolyzing and purifying rubber products containing carbon black such as tires may be appropriately used in an equal amount substitution with these.

[0079] Specific carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. As commercially available products, for example, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nippon Chemical Carbon Co., Ltd., Columbian Carbon Company, etc. can be used. These may be used alone or in combination of two or more.

[0080] The content of carbon black with respect to 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 still more preferably 40 parts by mass or more. As the upper limit, for example, it is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and still more preferably 60 parts by mass or less.

[0081] (ii) Silica The water of hydration and surface functional groups contained in silica can capture ozone, so the ozone resistance is improved and the durability of the tire can be improved.

[0082] As for silica, if the average primary particle diameter is too small, the processability deteriorates. Therefore, it is preferable to use silica with a particle diameter exceeding 8 nm, more preferably 9 nm or more, and even more preferably 10 nm or more. On the other hand, from the viewpoints of ensuring the rubber reinforcement property and the handling stability performance on a wet road surface during driving, it is preferably 25 nm or less, more preferably 20 nm or less, and even more preferably 17 nm or less.

[0083] The average primary particle diameter of silica means the average value of the values measured by observing the minimum particle unit of silica constituting the aggregated structure as a circle and measuring the absolute maximum length of the minimum particle as the diameter of the circle. It can be observed with a transmission or scanning electron microscope, and more than 400 primary particles of silica observed in the visual field are measured, and the average value is obtained.

[0084] The BET specific surface area of silica is preferably more than 100 m 2 / g, more preferably more than 130 m 2 / g from the viewpoint of obtaining good durability performance. On the other hand, it is preferably less than 250 m 2 / g, more preferably less than 200 m 2 / g. The above-mentioned BET specific surface area is the value of N2SA measured by the BET method in accordance with ASTM D3037-93.

[0085] Examples of silica include dry-process silica (anhydrous silica), wet-process silica (hydrous silica), colloidal silica, etc. Among them, wet-process silica containing water of hydration, containing many silanol groups, and capable of effectively capturing ozone is preferable. Further, silica using hydrated glass or the like as a raw material, silica using biomass materials such as rice husks as a raw material, etc. may also be used.

[0086] As for silica, products of Evonik Industries, Rhodia, Tosoh Silica Corporation, Solvay Japan, Inc., Tokuyama Corporation, etc. can be used.

[0087] The content of silica relative to 100 parts by mass of the rubber component is 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 with respect to 100 parts by mass of the rubber component. As the upper limit, from the viewpoint of dispersibility in the rubber composition, it is preferably 120 parts by mass or less, more preferably 110 parts by mass or less, and even more preferably 100 parts by mass or less.

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

[0089] The silane coupling agent is not particularly limited. For example, 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, etc. sulfide-based, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, mercapto-based such as NXT and NXT-Z manufactured by Momentive, vinyl-based such as vinyltriethoxysilane and vinyltrimethoxysilane, amino-based such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane, glycidoxy-based such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, nitro-based such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, chloro-based such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, etc. can be mentioned. Among these, silane coupling agents having a thiocarbonyl group such as the above-mentioned NXT are preferred. These may be used alone or in combination of two or more.

[0090] As the silane coupling agent, for example, 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.

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

[0092] (iv) Other fillers In addition to the carbon black and silica described above, the rubber composition may further contain fillers generally used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, magnesium sulfate, etc. The content of these is, for example, more than 0.1 part by mass and less than 150 parts by mass with respect to 100 parts by mass of the rubber component.

[0093] (b) Plasticizer component In consideration of the proper dispersion of the powder material during kneading, it is preferable to use a plasticizer component as needed in the rubber composition. Here, the plasticizer component refers to those that plasticize the rubber composition, such as process oil, extender oil for rubber components, liquid rubber, resin components, etc.

[0094] At this time, the content of the plasticizer component with respect to 100 parts by mass of the rubber component is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more. As the upper limit, it is preferably, for example, 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0095] Note that the content of the plasticizer component includes the amount of oil contained in rubber (oil-extended rubber), etc.

[0096] (i) Oil Examples of the oil include mineral oil, synthetic oil, vegetable oil, animal oil, or a mixture thereof.

[0097] Examples of the mineral oil include paraffinic oil, aromatic oil, naphthenic oil, etc. For example, products of Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Orisoy Co., H&R Co., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kogyo Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0098] Also, from the perspective of life cycle assessment, as these oils, lubricating oil used in mixers or engines of rubber mixers, waste cooking oil after use in restaurants, etc. may be appropriately refined and used.

[0099] Examples of the vegetable oil 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, grape seed oil, wood wax, etc.

[0100] Furthermore, examples of the vegetable oil also include refined oil (such as salad oil) obtained by refining each of the above oils, transesterified oil obtained by transesterification, hydrogenated hardened oil, thermally polymerized oil obtained by thermal polymerization, oxidation polymerized oil obtained by oxidation, waste cooking oil recovered from those used as edible oil, etc. Note that the vegetable oil may be liquid or solid at normal temperature (25°C). These may be used alone or in combination of two or more.

[0101] As the vegetable oil, acylglycerol is preferable, and triacylglycerol is more preferable. Here, acylglycerol refers to a compound in which the hydroxy group of glycerin and a carboxylic acid are ester-bonded. The acylglycerol is not particularly limited, and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Further, the acylglycerol may be a monomer, a dimer, or a multimer of trimer or more. Note that acylglycerols of dimer or more can be obtained by thermal polymerization, oxidative polymerization, or the like. Also, the acylglycerol may be liquid or solid at normal temperature (25 °C).

[0102] As a method for confirming whether acylglycerol is contained in the rubber composition, although not particularly limited, 1 it can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at normal temperature (25 °C) for 24 hours. After removing the rubber composition, 1 1H-NMR is measured. When the signal of tetramethylsilane (TMS) is set to 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm are observed. Since the signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group, the content 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, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

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

[0106] A farnesene-based polymer is a polymer obtained by polymerizing farnesene and has a structural unit based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene).

[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-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), and the like.

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

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

[0111] (iii) Resin component The resin component also functions as an adhesiveness-imparting component and may be solid or liquid at room temperature. Specific resin components include, for example, rosin-based resins, styrene-based resins, coumarone-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, acrylic resins, etc. Two or more of them may be used in combination. In addition, these resin components may be provided with a modifying group capable of reacting with silica or the like as necessary.

[0112] The rosin-based resin is a resin mainly composed of rosin acid obtained by processing pine resin. This rosin-based resin (rosins) can be classified according to the presence or absence of modification, and can be classified into unmodified rosin (unmodified rosin) and rosin modified products (rosin derivatives). Examples of unmodified rosin include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. Rosin modified products are modified products of unmodified rosin, and examples include rosin esters, unsaturated carboxylic acid-modified rosins, unsaturated carboxylic acid-modified rosin esters, amide compounds of rosin, amine salts of rosin, etc.

[0113] The styrene-based resin is a polymer using a styrene-based monomer as a constituent monomer, and examples include polymers polymerized with a styrene-based monomer as a main component (50% by mass or more). Specifically, homopolymers obtained by polymerizing each styrene-based monomer (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) alone, copolymers obtained by copolymerizing two or more styrene-based monomers, and copolymers of a styrene-based monomer and other monomers copolymerizable therewith are also included.

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

[0115] Among coumarone resins, coumarone-indene resins are preferred. A coumarone-indene resin is a resin containing coumarone and indene as monomer components constituting the resin skeleton (main chain). Examples of monomer components contained in the skeleton other than coumarone and indene include styrene, α-methylstyrene, methyl indene, vinyltoluene and the like.

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

[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 measured with a ring and ball softening point measuring device according to the softening point defined in JIS K 6220-1:2001.

[0118] Examples of terpene resins include polyterpenes, terpene phenols, aromatic modified terpene resins and the like. Polyterpenes are resins obtained by polymerizing terpene compounds and hydrogenated products thereof. Terpene compounds are hydrocarbons represented by the composition of (C5H8) n and oxygen-containing derivatives thereof, and include monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H32 ) It is a compound having a terpene as a basic skeleton and classified into, for example, α-pinene, β-pinene, dipentene, limonene, myrcene, allo-ocimene, ocimene, α-farnesene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, etc.

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

[0120] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of the C5 fraction include petroleum fractions corresponding to 4 to 5 carbon atoms such as cyclopentadiene, pentene, pentadiene, isoprene, etc. As the C5-based petroleum resin, dicyclopentadiene resin (DCPD resin) is preferably used.

[0121] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, which may be hydrogenated or modified. Examples of the C9 fraction include petroleum fractions corresponding to 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, indene, and methylindene. As specific examples, for instance, coumarone-indene resin, coumarone resin, indene resin, and aromatic vinyl resins are preferably used. Among the aromatic vinyl resins, due to economic reasons, ease of processing, and excellent heat generation properties, a homopolymer of α-methylstyrene (AMS resin) or styrene, or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred. As the aromatic vinyl resin, for example, those commercially available from companies such as Kraton Corporation and Eastman Chemical Company can be used.

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

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

[0124] The solventless acrylic resin is a (meth)acrylic resin (polymer) synthesized by a high-temperature continuous polymerization method (high-temperature continuous bulk polymerization method) (the methods described in U.S. Patent No. 4,414,370, JP-A-59-6207, JP-B-5-58005, JP-A-1-313522, U.S. Patent No. 5,010,166, Annual Report of Toagosei Research TREND2000 No. 3 p42-45, etc.) without using a polymerization initiator, chain transfer agent, organic solvent, etc. as auxiliary raw materials as much as possible. In the present invention, "(meth)acrylic" means 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] In addition, as the monomer components constituting the acrylic resin, aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene may be used together with (meth)acrylic acid or (meth)acrylic acid derivatives.

[0127] The acrylic resin may be a resin composed only of the (meth)acrylic component or a resin having components other than the (meth)acrylic component as constituent elements. Further, the acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

[0128] Examples of the resin component include products of Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Clayton, Nippon Paint Co., Ltd., Nippon Catalyst Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., Tago Chemical Industry Co., Ltd., etc.

[0129] (C) Lubricant (stearic acid) The rubber composition may contain a lubricant. As the lubricant, lubricants based on fatty acid derivatives such as stearic acid can be preferably used. As stearic acid, conventionally known ones can be used. Specifically, for example, products of NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acids Co., Ltd., etc. can be used. In addition, Structol WB16 manufactured by Structol can also be used.

[0130] The content of stearic acid is preferably more than 0.5 part by mass and less than 10.0 parts by mass with respect to 100 parts by mass of the rubber component.

[0131] (B) Antioxidant 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 with respect to 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; p-phenylenediamine-based antioxidants such as N-isopropyl-N′-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, and N,N′-di-2-naphthyl-p-phenylenediamine; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bis, tris, polyphenol-based antioxidants such as tetrakis-[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane, etc. These may be used alone or in combination of two or more.

[0133] As specific antioxidants, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys Co., etc. can be used.

[0134] (E) Zinc Oxide 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 with respect to 100 parts by mass of the rubber component. As the zinc oxide, conventionally known ones can be used, for example, products of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Sho Do Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0135] (F) Wax The rubber composition may contain wax. The content of the wax is preferably, for example, 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 with respect to 100 parts by mass of the rubber component.

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

[0137] In addition, as the wax, for example, products of Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used.

[0138] (d) 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 part by mass and less than 10.0 parts by mass with respect to 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 the oil component.

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

[0140] In addition, as the sulfur, for example, products of Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexsys, Nippon Karyu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0141] Crosslinking agents other than sulfur may be used. Specifically, for example, Tackiol V200 manufactured by Tago Chemical Industry Co., Ltd., DURALINK HTS (sodium 1,6-hexamethylene-dithiolsulfate dihydrate) manufactured by Flexsys, KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane: hybrid crosslinking agent) manufactured by Lanxess, etc., vulcanizing agents containing sulfur atoms, organic peroxides such as dicumyl peroxide, etc. can be used.

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

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

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

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

[0146] Kneading can be performed using a known (sealed type) kneader such as a Banbury mixer, a kneader, or an open roll.

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

[0148] In the finishing kneading step, the kneaded product obtained in the base kneading step and the crosslinking agent are kneaded. The kneading temperature in the finishing kneading step is, for example, above room temperature and below 80°C, and the kneading time is, for example, above 1 minute and below 15 minutes. In the finishing kneading step, in addition to the above components, vulcanization accelerators, zinc oxide, etc. may be appropriately added and kneaded as required.

[0149] The rubber composition obtained as described above can then be formed into a tread by extrusion into a predetermined shape.

[0150] 3. Tire Manufacturing The tire according to this embodiment can be manufactured by a normal method. First, using the rubber composition obtained as described above, it is formed into a predetermined shape to manufacture a tread. Next, it is combined with other rubber members on a tire molding machine to produce an unvulcanized tire.

[0151] Specifically, on the forming drum, an inner liner as a member for ensuring the airtightness of the tire, a carcass as a member for withstanding the load, impact, and inflation pressure received by the tire, a belt member as a member for strongly clamping the carcass to increase the rigidity of the tread, etc. are wound, both ends of the carcass are fixed to both side edges, and a bead portion as a member for fixing the tire to the rim is arranged, and after forming into a toroidal shape, a tread is attached to the central portion of the outer periphery, and a sidewall is bonded to the radially outer side to form a side portion, thereby producing an unvulcanized tire.

[0152] Thereafter, the unvulcanized tire produced as described above is heated and pressurized in a vulcanizer to obtain a tire. The vulcanization process can be carried out by applying known vulcanization means. The vulcanization temperature is, for example, above 120°C and below 200°C, and the vulcanization time is, for example, above 5 minutes and below 15 minutes.

[0153] As described above, the tire obtained has the effects of the sipes formed with appropriate twist and the rubber composition produced with an appropriate silica / carbon black ratio working together to more appropriately control the wear of the tire. Therefore, even in the later stage of wear, the rigidity of the tread portion can be ensured, and the improvement of the grip performance in the later stage can be achieved.

[0154] And the tire according to the present invention can be preferably 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 particularly preferably as a passenger car tire.

Example

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

[0156] Assuming a tire (tire size: 175 / 60R18) consisting of a tread formed from various compounding materials shown below and other rubber members, Table 1 shows the results calculated based on the following grip performance evaluation method in the late wear stage.

[0157] 1. Preparation of rubber composition Using the various compounding materials shown below, a rubber composition for the tread is prepared.

[0158] (1) Compounding materials (a) Rubber components (i) NR: TSR20 (ii) SBR: HPR840 (S-SBR) manufactured by ENEOS Materials Co., Ltd. (Styrene content: 10% by mass, vinyl content: 42% by mass)

[0159] (b) Compounding materials other than rubber components (i) Carbon black: DIABLACK N220 manufactured by Mitsubishi Chemical Corporation (N2SA: 115 m 2 / g) (ii) Silica: ULTRASIL VN3 manufactured by Evonik Industries AG (N2SA: 175 m 2 / g, average primary particle diameter: 17 nm) (iii) Silane coupling agent: NXT manufactured by Momentive (3-Octanoylthiopropyltriethoxysilane) (iv) Oil: Process Oil A / OMIX manufactured by Sankyo Yuka Kogyo Co., Ltd. (v) Resin: YS Resin PX850 manufactured by Yasuhara Chemical Co., Ltd. (Softening point 85°C, β-pinene resin (terpene resin)) (vi) Wax: Oz Ace 0355 manufactured by Nippon Seiko Co., Ltd. (vii) Antioxidant-1: No Crack 6C manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine) (viii) Antioxidant-2: No Crack RD manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (Poly(2,2,4-trimethyl-1,2-dihydroquinoline)) (Li) Stearic acid: Bead stearic acid "Tsubaki" manufactured by NOF Corporation (Nu) Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. (Ru) Sulfur: Powder sulfur manufactured by Karuizawa Sulfur Co., Ltd. (Wo) Accelerator-1: Nocceler CZ-G (CBS) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-Cyclohexyl-2-benzothiazolylsulfenamide) (Wa) Accelerator-2: Nocceler D (DPG) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (1,3-Diphenylguanidine)

[0160] (2) Preparation of rubber composition for tread Based on each formulation shown in Table 1, using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., materials other than sulfur and vulcanization accelerator were kneaded at 150°C for 5 minutes to obtain a kneaded product.

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

[0162] 2. Molding of tread Next, using the rubber composition obtained above, it was molded into a tread having a predetermined shape in which a twist siped was formed such that the width was 2 mm or less, the depth was 20 mm or less, and the ratio X of the area of the intersection of the opening and the groove bottom was 95% or less.

[0163] 3. Manufacture of tire Next, the tread obtained above was bonded together with other tire members to form an unvulcanized tire, which was press-vulcanized at 170°C for 10 minutes to manufacture each test tire of Examples 1 to 4 and Comparative Examples 1 to 4.

[0164] 4. Performance evaluation test (evaluation of grip performance in the latter stage of wear) Each test tire was mounted on all the wheels of a vehicle (a domestic FF vehicle with a displacement of 2,000 cc), filled with air so that the internal pressure became 230 kPa, and driven for 30,000 km. Then, actual vehicle running was performed on a test course of a dry asphalt road surface, and the running time was measured.

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

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

[0167] Next, taking the shortened running time in Comparative Example 1 as 100, it is indexed based on the following formula for the grip performance evaluation in the late wear stage. The larger the numerical value, the better the grip performance in the late wear stage. Grip performance in the late wear stage =[(Result of the test tire) / (Result of Comparative Example 1)]×100

[0168]

Table 1

[0169] As described above, the present invention has been described based on the embodiments, but the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments within the same and equivalent scope as the present invention.

[0170] The present invention (1) is a tire provided with a tread portion, a groove having a width of 2 mm or less and a depth of 20 mm or less, which has an opening portion facing the surface of the tread portion and a groove bottom portion, is formed on the land portion of the surface of the tread portion, the opening portion and the groove bottom portion intersect when the surface of the tread portion is viewed in plan, The ratio X of the area of the intersection of the opening and the groove bottom to the area of the opening when the surface of the tread portion is viewed in plan view is 95% or less. The tread portion is formed of a rubber composition containing a rubber component, silica, and carbon black, and the ratio Y of the content (parts by mass) of silica to the content (parts by mass) of carbon black is more than 50%. Furthermore, it is a tire characterized in that X / Y < 1.5.

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

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

[0173] The present invention (4) is characterized in that the X is 1% or more, and it is the tire according to the present invention (2) or (3).

[0174] The present invention (5) is characterized in that the Y is 100% or more, and it is the tire according to the present invention (1).

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

[0176] The present invention (7) is characterized in that the Y is 380% or less, and it is the tire according to the present invention (5) or (6).

[0177] The present invention (8) is characterized in that the X / Y is 1.2 or less, and it is the tire according to the present invention (1).

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

[0179] The present invention (10) is The tire according to the present invention (8) or (9), wherein X / Y is 0.03 or more.

[0180] The present invention (11) is The tire according to the present invention (1), wherein the thickness of the tread portion is 10 mm or more and 20 mm or less.

[0181] The present invention (12) is The tire according to the present invention (1), wherein the tread portion is formed of a plurality of layers having a cap rubber layer as the outermost layer.

[0182] The present invention (13) is The tire according to the present invention (12), wherein 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), wherein the thickness of the cap rubber layer in the entire tread portion is 70% or more.

[0184] The present invention (15) is The tire according to the present invention (1), wherein the aspect ratio is 30% or more and 60% or less.

[0185] The present invention (16) is The tire according to the present invention (1), wherein the rubber composition contains styrene-butadiene rubber (SBR) having a styrene content of 25% by mass or less.

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

[0187] The present invention (18) is characterized in that the content of the isoprene rubber in 100 parts by mass of the rubber component of the rubber composition is 40 parts by mass or more, and it is a tire according to the present invention (1).

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

[0189] The present invention (20) is characterized in that the rubber composition contains at least one resin component selected from rosin resins, styrene resins, coumarone resins, terpene resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, and it is a tire according to the present invention (1).

Description of Reference Numerals

[0190] 1 Tread 2 Opening 3 Groove Bottom S Intersection

Claims

1. 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, which has an opening facing the surface of the tread portion and a groove bottom, is formed in the land portion on the surface of the tread portion, the opening and the groove bottom intersect when the surface of the tread portion is viewed in plan, a ratio X of the area of the intersection portion between the opening and the groove bottom to the area of the opening when the surface of the tread portion is viewed in plan is 95% or less, the tread portion is formed of a rubber composition containing a rubber component, silica, and carbon black, and a ratio Y of the content (parts by mass) of silica to the content (parts by mass) of carbon black is more than 50%, and further, X / Y < 1.

5. A tire characterized by this.

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

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

4. The tire according to claim 2 or claim 3, wherein X is 1% or more.

5. The tire according to claim 1, wherein Y is 100% or more.

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

7. The tire according to claim 5 or claim 6, wherein Y is 380% or less.

8. The tire according to claim 1, wherein X / Y is 1.2 or less.

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

10. The tire according to claim 8 or claim 9, wherein X / Y is 0.03 or more.

11. The tire according to claim 1, wherein the thickness of the tread portion is 10 mm or more and 20 mm or less.

12. The tire according to claim 1, wherein the tread portion is formed of a plurality of layers having a cap rubber layer as the outermost layer.

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

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

15. The tire according to claim 1, wherein the aspect ratio is 30% or more and 60% or less.

16. The tire according to claim 1, wherein the rubber composition contains a styrene-butadiene rubber (SBR) having a styrene content of 25% by mass or less.

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

18. The tire according to claim 1, wherein 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.

19. The tire according to claim 1, wherein the particle diameter of the silica is 17 nm or less.

20. The tire according to claim 1, wherein 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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