Tire

Abstract

The invention provides a tire with improved durability. The present invention pertains to a tire provided with a tread surface and a tread base, the tire being characterized in that the tread surface contains a polymer having an ethylene unit, an isoprene rubber, and a compound represented by formula (1), the content of the isoprene rubber being 20 mass% or more per 100 mass% of the rubber component, and the content of the isoprene rubber being 20 mass% or more per 100 mass% of the rubber component. The content of the isoprene-based rubber in 100% by mass of the rubber component of the tread base is greater than the content of the isoprene-based rubber in 100% by mass of the rubber component of the tread tread (1) R1R2N-(C = S)-Sz (C = S)-NR3R4 (In the formula, z represents an integer of 1-8; r1-R4 may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1-15 carbon atoms.

Description

Technical Field

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

[0002] Conventionally, tires are required to have various performances, and from the viewpoint of recent environmental considerations, etc., improvement in durability and the like is desired. Summary of the invention Problems to be solved by the invention

[0003] An object of the present invention is to solve the above-mentioned problems and provide a tire having improved durability. Means for solving problems

[0004] The present invention relates to a tire comprising a cap tread and a base tread, wherein: The cap tread contains a polymer having ethylene units, an isoprene-based rubber, and a compound represented by the following formula (1), wherein the content of the isoprene-based rubber in 100% by mass of the rubber component is 20% by mass or more, The content of the isoprene-based rubber in 100% by mass of the rubber component of the base tread is larger than the content of the isoprene-based rubber in 100% by mass of the rubber component of the cap tread. (1)R 1 R 2 N-(C=S)-Sz(C=S)-NR 3 R 4 (wherein z represents an integer of 1 to 8. 1 ~R 4 are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms. Effects of the Invention

[0005] The present invention is a tire having a tread surface and a tread base, characterized in that the tread surface contains a polymer having ethylene units, an isoprene-based rubber and a compound represented by the above formula (1), and the content of the isoprene-based rubber in 100% by mass of the rubber component is 20% by mass or more, and the content of the isoprene-based rubber in 100% by mass of the rubber component of the tread base is greater than the content of the isoprene-based rubber in 100% by mass of the rubber component of the tread surface, thereby improving durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a cross-sectional view showing a part of a pneumatic tire. Figure 2 Yes means Figure 1 An enlarged cross-sectional view of the tire near the tread. Reference numerals 2: tire; 4: tread; 6: sidewall; 8: tread wing; 10: overlap; 12: bead; 14: carcass; 16: belt layer; 18: belt layer; 20: inner liner; 22: bead cover; 24: tread surface; 26: groove; 28: base layer; 30: running surface layer; 32: core; 34: apex rubber; 36: carcass cord layer; 36a: main body; 36b: turnback; 38: inner layer; 40: outer layer; 42: main groove; 44: pattern (rib); CL: equatorial plane of the tire; Tc: thickness of the running surface of the tread; Tb: thickness of the base of the tread. DETAILED DESCRIPTION

[0007] The tire comprises a tread surface and a base tread, wherein the tread surface contains a polymer having ethylene units, an isoprene-based rubber and a compound represented by the above formula (1), and the content of the isoprene-based rubber in 100% by mass of the rubber component is 20% by mass or more, and the content of the isoprene-based rubber in the base tread is greater than the content of the isoprene-based rubber in the tread surface.

[0008] The reason why the above tire achieves the above effects is not necessarily clear, but is presumed as follows. A formulation containing a polymer having ethylene units generally has problems of delayed vulcanization and low compatibility with other rubbers, and thus there is a concern of interfacial peeling between the cap tread / base tread. In the above tire, a predetermined amount of isoprene-based rubber having high compatibility with the base tread is compounded in the cap tread, and the compound represented by (1) is compounded to accelerate vulcanization, thereby improving the co-crosslinking property between the cap tread and the base tread, and suppressing interface peeling. Therefore, the durability of the tire is improved.

[0009] As described above, the tire is configured to have a cap tread and a base tread that satisfy the following conditions: "the content of isoprene rubber in 100% by mass of the rubber component is 20% by mass or more" and "the content of isoprene rubber in 100% by mass of the rubber component of the base tread is greater than the content of isoprene rubber in 100% by mass of the rubber component of the cap tread", thereby solving the problem (purpose) of improving durability. That is, the parameters of "the content of isoprene rubber in 100% by mass of the rubber component is 20% by mass or more" and "the content of isoprene rubber in 100% by mass of the rubber component of the base tread is greater than the content of isoprene rubber in 100% by mass of the rubber component of the cap tread" are not the subject (purpose) of the present invention. The subject of the present application is to improve durability, and as a means for solving the problem, the tire is configured to satisfy the above parameters.

[0010] The tire has a cap tread and a base tread. The cap tread is composed of a rubber composition for a cap tread, and the base tread is composed of a rubber composition for a base tread.

[0011] Chemical substances that can be used in combination with the rubber composition for cap treads and the rubber composition for base treads are described below.

[0012] The rubber composition for cap treads and the rubber composition for base treads contain a rubber component. Here, the rubber component is a component that contributes to crosslinking, and generally refers to a polymer having a weight average molecular weight (Mw) of 10,000 or more and a polymer component that is not extracted by acetone. The rubber component is in a solid state at room temperature (25° C.).

[0013] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, further preferably 200,000 or more, particularly preferably 270,000 or more, and preferably 2,000,000 or less, more preferably 1,500,000 or less, further preferably 1,000,000 or less. When it is within the above range, there is a tendency that the effect can be better obtained.

[0014] In addition, in this specification, the weight average molecular weight (Mw) can be calculated|required by standard polystyrene conversion based on the measurement value obtained by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0015] The rubber component that can be used in the rubber composition for cap treads and the rubber composition for base treads may be an unmodified rubber or a modified rubber. Examples of modified rubbers include rubbers having functional groups that interact with fillers such as silica, etc. For example, examples include: terminal-modified rubbers in which at least one terminal of the rubber is modified with a compound (modifier) ​​having the above functional group (terminal-modified rubbers having the above functional group at the terminal), main chain-modified rubbers having the above functional group on the main chain, main chain-terminal-modified rubbers having the above functional group on the main chain and the terminal (for example, main chain-terminal-modified rubbers having the above functional group on the main chain and at least one terminal modified with the above modifier), terminal-modified rubbers modified (coupled) with a multifunctional compound having two or more epoxy groups in the molecule, and having hydroxyl groups or epoxy groups introduced therein, etc.

[0016] As the functional group, for example, amino, amide, silyl, alkoxysilyl, isocyanate, imino, imidazole, urea, ether, carbonyl, oxycarbonyl, mercapto, sulfide group, disulfide group, sulfonyl, sulfinyl, thiocarbonyl, ammonium, imido, 1,2-hydrazo, azo, diazo, carboxyl, nitrile, pyridyl, alkoxy, hydroxyl, oxy, epoxy, etc. can be cited. It should be noted that these functional groups may have a substituent. Among them, amino (preferably, an amino group in which the hydrogen atom possessed by the amino group is substituted by an alkyl group having 1 to 6 carbon atoms), alkoxy (preferably, an alkoxy group having 1 to 6 carbon atoms), and alkoxysilyl (preferably, an alkoxysilyl group having 1 to 6 carbon atoms) are preferred.

[0017] Examples of the rubber component include diene rubber.

[0018] As diene rubber, isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR) etc. can be cited. In addition, as rubber component, butyl rubber, fluororubber etc. can also be cited. They can be used alone, or two or more can be used in combination. In addition, these rubber components can be modified, hydrogenated, and filled rubber (extended rubber) filled with oil, resin, liquid rubber component etc. can also be used. Among diene rubber, isoprene rubber, BR, SBR are preferred.

[0019] As isoprene-based rubber, natural rubber (NR), polyisoprene rubber (IR), modified NR, modified NR, modified IR, etc. can be cited. As NR, for example, conventional products in the rubber industry such as SIR 20, RSS#3, TSR20, etc. can be used. As IR, there is no particular limitation, for example, conventional products in the rubber industry such as IR2200 can be used. As modified NR, deproteinized natural rubber (DPNR), high-purity natural rubber, etc. can be cited; as modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. can be cited; as modified IR, epoxidized polyisoprene rubber, hydrogenated polyisoprene rubber, grafted polyisoprene rubber, etc. can be cited. They can be used alone, or two or more kinds can be used in combination.

[0020] BR is not particularly limited, for example, high cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, BR synthesized using a rare earth catalyst (rare earth BR), etc. can be used. They can be used alone, or two or more can be used in combination. Among them, BR preferably contains a high cis BR with a cis content of 90% by mass or more. The cis content is more preferably 95% by mass or more. It should be noted that the cis content can be measured by infrared absorption spectroscopy.

[0021] The cis-amount of BR refers to the cis-amount of the BR when there is one type of BR, and refers to the average cis-amount when there are multiple types of BR. The average cis content of BR can be calculated by {∑(content of each BR×cis content of each BR)} / total content of all BRs. For example, in the case where BR with a cis content of 90% by mass is 20% by mass and BR with a cis content of 40% by mass is 10% by mass in the rubber component of 100% by mass, the average cis content of BR is 73.3% by mass (=(20×90+10×40) / (20+10)).

[0022] In addition, BR may be either unmodified BR or modified BR. As the modified BR, there may be mentioned a modified BR into which the same functional group as the modified rubber is introduced. In addition, a hydrogenated butadiene polymer (hydrogenated BR) may be used as BR.

[0023] 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. These can be used alone or in combination of two or more.

[0024] The styrene content of SBR is preferably 5% by mass or more, more preferably 20% by mass or more, and further preferably 25% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, and further preferably 35% by mass or less. Within the above range, there is a tendency to obtain better effects. It should be noted that, in this specification, the styrene content can be 1 The results were determined by H-NMR measurement.

[0025] The styrene amount of SBR refers to the styrene amount of the SBR when there is one type of SBR, and refers to the average styrene amount when there are multiple types of SBR. The average styrene content of SBR can be calculated by {∑(content of each SBR×styrene content of each SBR)} / total content of all SBRs. For example, in the case where SBR with a styrene content of 40 mass% is 85 mass% and SBR with a styrene content of 25 mass% is 5 mass% in 100 mass% of the rubber component, the average styrene content of SBR is 39.2 mass% (=(85×40+5×25) / (85+5)).

[0026] The vinyl bond amount of SBR is preferably 3% by mass or more, more preferably 5% by mass or more, and further preferably 7% by mass or more. The vinyl bond amount is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less. When within the above range, there is a tendency to obtain a better effect. In addition, in this specification, the vinyl bond amount (1,2-bonded butadiene unit amount) can be measured by infrared absorption spectroscopic analysis.

[0027] The vinyl amount (1,2-bonded butadiene unit amount) of SBR is the ratio of vinyl bonds (unit: mass%) when the total mass of the butadiene part in SBR is 100, vinyl amount [mass%] + cis amount [mass%] + trans amount [mass%] = 100 [mass%]. When there is one type of SBR, it refers to the vinyl amount of the SBR, and when there are multiple types of SBR, it refers to the average vinyl amount. The average vinyl content of SBR can be calculated by ∑{content of each SBR×(100[mass%]-styrene content of each SBR[mass%])×vinyl content of each SBR[mass%]} / ∑{content of each SBR×(100[mass%]-styrene content of each SBR[mass%])}. For example, in 100 parts by mass of the rubber component, 75 parts by mass of SBR having a styrene content of 40% and a vinyl content of 30% is used, and 75 parts by mass of SBR having a styrene content of 25% and a vinyl content of 30% is used. When the amount of SBR containing 20 mass% is 15 mass parts and the balance 10 mass parts is rubber components other than SBR, the average vinyl amount of SBR is 28 mass% (={75×(100[mass%]-40[mass%])×30[mass%]+15×(100[mass%]-25[mass%])×20[mass%]} / {75×(100[mass%]-40[mass%])+15×(100[mass%]-25[mass%])}.

[0028] SBR can use any one of non-modified SBR and modified SBR. As modified SBR, modified SBR introduced with the same functional group as modified rubber can be cited. In addition, as SBR, hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used.

[0029] The raw materials (monomers) of synthetic rubbers such as SBR and BR can be derived from petroleum, or can be recovered and reused from rubber products such as tires or non-rubber products such as polystyrene. The monomers obtained by recycling and reuse (recycled monomers) are not particularly limited, and examples include butadiene from recycling and reuse, aromatic vinyl compounds from recycling and reuse, etc. As the butadiene, 1,2-butadiene and 1,3-butadiene can be mentioned. As the aromatic vinyl compound, there are no particular limitations, and styrene can be mentioned. Among them, it is preferred to use butadiene from recycling and reuse (recycled butadiene) and / or styrene from recycling and reuse (recycled styrene) as raw materials.

[0030] There are no particular limitations on the method for producing the recycled monomer, and for example, the monomer may be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. In addition, there are no particular limitations on the method for producing the recycled naphtha, and for example, rubber products such as tires may be decomposed under high temperature and high pressure, or may be decomposed under microwaves, or may be extracted after mechanical pulverization.

[0031] In addition, the raw materials (monomers) of synthetic rubbers such as SBR and BR can be derived from biomass. As monomers from biomass (biomass monomers), there are no particular limitations, and examples include butadiene from biomass, aromatic vinyl compounds from biomass, and the like. As the butadiene, 1,2-butadiene and 1,3-butadiene can be cited. As the aromatic vinyl compound, there are no particular limitations, and examples include styrene, etc. In addition, the method for producing biomass monomers is not particularly limited, and for example, methods of biological and / or chemical and / or physical transformation of plants and animals can be cited. As a biological transformation, a representative method is fermentation by microorganisms, and as a chemical and / or physical transformation, chemical and / or physical transformation by catalysts (agents), high heat, high pressure, electromagnetic waves, critical liquids, and combinations thereof can be cited. As biomass sources of these monomers, sugar or wood, plant residues after obtaining useful components, ethanol from plants, biomass naphtha, and the like can be cited.

[0032] The polymer synthesized from the biomass monomer component (biomass polymer) is not particularly limited, and examples thereof include: polybutadiene rubber synthesized from butadiene from biomass, aromatic vinyl / butadiene copolymers synthesized from butadiene from biomass and / or aromatic vinyl compounds from biomass, etc. As the aromatic vinyl / butadiene copolymer, for example, styrene-butadiene rubber synthesized from butadiene from biomass and / or styrene from biomass, etc. can be mentioned.

[0033] Whether the raw material of a polymer is derived from biomass can be determined by pMC (percent Modern Carbon) measured according to ASTM D6866-10.

[0034] pMC refers to the 14 C concentration relative to modern standard reference 14 The ratio of C concentration is used as an index to indicate the biomass ratio of the compound (rubber). The meaning of this value is as follows.

[0035] 1 mole of carbon atoms (6.02×10 23 There are about one trillionth of the usual carbon atoms, or about 6.02×10 11 individual 14 C. 14 C is called a radioactive isotope, and its half-life is 5730 years and decreases regularly. It takes 226,000 years for all of these to decay. Therefore, in fossil fuels such as coal, oil, and natural gas (it is believed that carbon dioxide in the atmosphere is taken in and fixed in plants, etc., after more than 226,000 years), the carbon dioxide that is just contained in these fossil fuels is fixed. 14 Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain any 14 Therefore, the chemical products produced from these fossil fuels do not contain any 14 Element C.

[0036] On the other hand, cosmic rays are continuously generated by nuclear reactions in the atmosphere. 14 C, due to radioactive decay 14 The reduction phase equilibrium of C, in the Earth's atmosphere, 14 The amount of C is constant. Therefore, the amount of biomass resources in the current environment that carry out material circulation is 14 The C concentration is about 1×10 -12 Therefore, the ratio (biomass ratio) of a compound derived from a natural resource (a compound derived from a biomass resource) in a certain compound (rubber) can be calculated using the difference between these values.

[0037] Should 14 C is usually determined as follows. Using tandem accelerator-based accelerator mass spectrometry, 13 C concentration ( 13 C / 12 C) 14 C concentration ( 14 C / 12C) determination. In the determination, as 14 The modern standard reference material (Modern Standard Reference) based on the C concentration standard uses the C concentration in the natural circulating carbon in 1950. 14 C concentration. As a specific standard substance, an oxalic acid standard provided by NIST (National Institute of Standards and Technology) was used. The specific radioactivity of carbon in the oxalic acid (per 1g of carbon) was calculated. 14 The radioactivity intensity of C) is distinguished by each carbon isotope. 13 C is corrected to a fixed value, and the decay-corrected value from 1950 to the date of measurement is used as the standard 14 The ratio of this value to the value of the sample actually measured is the pMC value.

[0038] Therefore, if rubber is made from 100% biomass (natural), it will show a value of about 110 pMC, although there are regional differences (currently, under normal conditions, it is often not 100). On the other hand, for chemical substances derived from fossil fuels such as petroleum, when measuring this 14 When the concentration of C is about 0 pMC (for example, 0.3 pMC), this value corresponds to the above-mentioned biomass ratio of 0%.

[0039] In summary, it is preferable to use rubber or other materials having a high pMC value, that is, rubber or other materials having a high biomass ratio, in the rubber composition in terms of environmental protection.

[0040] Examples of the rubber component include a rubber having an ethylene unit (vinyl unit; a structural unit composed of ethylene: -CH 2 -CH 2 -) polymers. In the above tire, the polymer having ethylene units used in the tread surface is a high molecular weight polymer having ethylene units, which is a component that cannot be extracted from the rubber composition after vulcanization by organic solvents such as acetone, and is a substance used as a rubber component. It should be noted that the high molecular weight polymer having ethylene units preferably has a weight average molecular weight of the above rubber component.

[0041] The polymer having an ethylene unit is not particularly limited as long as it is a polymer having an ethylene unit, but a multi-component copolymer containing an ethylene unit, a conjugated diene unit, and an aromatic vinyl unit is preferred from the viewpoint of obtaining a good effect.

[0042] In the above multi-component copolymer, the conjugated diene unit is a structural unit derived from a conjugated diene compound. Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene. These may be used alone or in combination of two or more, preferably 1,3-butadiene and isoprene, and more preferably 1,3-butadiene.

[0043] In the above multi-component copolymer, the aromatic vinyl unit is a structural unit derived from an aromatic vinyl compound. Examples of the aromatic vinyl compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, 2,4,6-trimethylstyrene, etc. These may be used alone or in combination of two or more, preferably styrene and α-methylstyrene, and more preferably styrene.

[0044] The above-mentioned multi-polymer can be modulated by, for example, the following method: a method of copolymerizing ethylene, a conjugated diene compound and an aromatic vinyl compound; a method of converting a portion of the conjugated diene units into non-conjugated olefin units by hydrogenation after copolymerizing the conjugated diene compound and the aromatic vinyl compound, or the ethylene, the conjugated diene compound and the aromatic vinyl compound. That is, the above-mentioned multi-polymer can be a copolymer of ethylene, a conjugated diene compound and an aromatic vinyl compound, or a hydrogenated product (hydrogenated copolymer) of a copolymer of a conjugated diene compound and an aromatic vinyl compound, or the ethylene, the conjugated diene compound and the aromatic vinyl compound. They can be used alone or in combination of two or more. Among them, from the perspective of better obtaining the effect, the hydrogenated product of the copolymer of the conjugated diene compound and the aromatic vinyl compound is preferred, and the hydrogenated styrene-butadiene copolymer is more preferred.

[0045] When preparing the above multi-component copolymer, the polymerization method is not particularly limited, and may be random polymerization or block polymerization, with random polymerization being preferred.

[0046] When the multi-polymer is a hydrogenated copolymer, there is no particular limitation on the method and reaction conditions of hydrogenation, as long as the hydrogenation is carried out under known methods and known conditions. Usually, it is carried out at 20 to 150°C and 0.1 to 10 MPa of hydrogen pressure in the presence of a hydrogenation catalyst. There are no particular limitations on other methods and conditions related to manufacturing, for example, the contents described in International Publication No. 2016 / 039005 can be used.

[0047] In the rubber composition for tread, the content of the polymer having ethylene units in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 65% ​​by mass or more, and particularly preferably 70% by mass or more. The upper limit is not particularly limited, and may be 100% by mass, preferably 95% by mass or less, more preferably 85% by mass or less, and further preferably 80% by mass or less. Within the above range, there is a tendency to appropriately obtain the effect.

[0048] In the rubber composition for cap tread, the content of isoprene-based rubber in 100% by mass of the rubber component is 20% by mass or more, preferably 25% by mass or more, and more preferably 30% by mass or more. The upper limit is preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 40% by mass or less. Within the above range, there is a tendency that the effect can be appropriately obtained.

[0049] In the rubber composition for a base tread, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 60% by mass or more, more preferably 65% ​​by mass or more, and further preferably 75% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, and more preferably 85% by mass or less. Within the above range, there is a tendency that the effect can be appropriately obtained.

[0050] In the rubber composition for a base tread, the content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 25% by mass or less. When it is within the above range, there is a tendency that the effect can be appropriately obtained.

[0051] In the above tire, the content Ib of the isoprene-based rubber in 100% by mass of the rubber component of the base tread is greater than the content Ic of the isoprene-based rubber in 100% by mass of the rubber component of the cap tread (Ib>Ic). Ib / Ic is preferably 2.0 or more, more preferably 2.3 or more, and further preferably 2.5 or more. The upper limit is preferably 3.8 or less, more preferably 3.3 or less, and further preferably 3.0 or less. Within the above range, there is a tendency that the effect can be appropriately obtained.

[0052] Although the mechanism by which the effect can be better obtained when Ib / Ic is adjusted to a predetermined value or above, especially to a value of 2.3 or above, is not clear, it is speculated as follows: by making the amount of isoprene-based rubber in the base tread greater than that in the cap tread, the compatibility between the cap tread and the base tread is improved, and interface peeling is suppressed. Therefore, the durability of the tire is improved.

[0053] The rubber composition for a cap tread contains a compound represented by the following formula (1). (1)R 1 R 2 N-(C=S)-Sz(C=S)-NR 3 R 4 (wherein z represents an integer of 1 to 8. 1 ~R 4 are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms.

[0054] In the above formula (1), z is preferably 1 or more, and is preferably 6 or less, and more preferably 3 or less.

[0055] R in the above formula (1) 1 ~R 4 The number of carbon atoms in the hydrocarbon group is preferably 2 or more, more preferably 4 or more, and is preferably 12 or less, more preferably 10 or less. As R 1 ~R 4 Examples of the hydrocarbon group include monovalent aliphatic hydrocarbon groups such as alkyl groups and monovalent aromatic hydrocarbon groups such as aryl groups. An alkyl group is preferred, an alkyl group having a branched structure is more preferred, and a 2-ethylhexyl group is further preferred.

[0056] Examples of the compound represented by the formula (1) include Nocceler TBzTD (tetrabenzylthiuram disulfide) and Nocceler TOT-N (tetrakis(2-ethylhexyl)thiuram disulfide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Among them, tetrabenzylthiuram disulfide is preferred from the viewpoint of obtaining a better effect.

[0057] The rubber composition for a base tread may also contain a compound represented by the above formula (1).

[0058] The rubber composition for cap treads and the rubber composition for base treads may contain a vulcanization accelerator other than the compound represented by the above formula (1).

[0059] The type of vulcanization accelerator is not particularly limited, and commonly used vulcanization accelerators can be used. As vulcanization accelerators, benzothiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazole disulfide, and N-cyclohexyl-2-benzothiazole sulfenamide can be cited; sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; guanidine-based vulcanization accelerators such as diphenylguanidine, di-o-tolylguanidine, and o-tolylbiguanide. They can be used alone, or two or more can be used in combination. Among them, sulfenamide-based, guanidine-based, and benzothiazole-based vulcanization accelerators are preferred.

[0060] In the rubber composition for a tread, the content of the compound represented by the above formula (1) is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and further preferably 0.5 parts by mass or more, relative to 100 parts by mass of the rubber component. The upper limit is preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less, and further preferably 1.0 parts by mass or less. Within the above range, there is a tendency to appropriately obtain the effect.

[0061] Although the mechanism by which the effect can be better obtained when the content of the compound represented by the above formula (1) is adjusted to a specified range, particularly 0.1 to 2.0 parts by mass, is not clear, it is presumed as follows: by adding a specified amount of the compound represented by the above formula (1), the vulcanization rate is accelerated, thereby improving the co-crosslinking of the cap tread and the base tread, and suppressing interface peeling. Therefore, the durability of the tire is improved.

[0062] In the rubber composition for tread, relative to 100 parts by mass of the rubber component, the content of the vulcanization accelerator (the total amount of the vulcanization accelerator) is preferably 3.0 parts by mass or more, more preferably 5.0 parts by mass or more, further preferably 5.3 parts by mass or more, and particularly preferably 5.5 parts by mass or more. The upper limit is preferably 8.0 parts by mass or less, more preferably 7.0 parts by mass or less, and further preferably 6.0 parts by mass or less. When within the above range, there is a tendency to appropriately obtain the effect.

[0063] In the rubber composition for base tread, the content of the vulcanization accelerator (the total amount of the vulcanization accelerator) is preferably 1.0 parts by mass or more, more preferably 1.5 parts by mass or more, and further preferably 2.0 parts by mass or more, relative to 100 parts by mass of the rubber component. The upper limit is preferably 5.0 parts by mass or less, more preferably 4.5 parts by mass or less, and further preferably 4.0 parts by mass or less. Within the above range, there is a tendency to appropriately obtain the effect.

[0064] The rubber composition for cap treads and the rubber composition for base treads preferably contain a plasticizer.

[0065] In this specification, a plasticizer is a material that imparts plasticity to a rubber component, and is a concept that includes both a plasticizer that is liquid (liquid) at room temperature (25°C) and a plasticizer that is solid at room temperature (25°C). Examples of plasticizers include resin components, oils, liquid polymers, ester plasticizers, and the like. These plasticizers may come from petroleum, or may come from biomass, or may come from naphtha recovered and reused from rubber products or non-rubber products. In addition, a low molecular weight hydrocarbon component obtained by thermally decomposing and extracting a used tire or a product containing various components may be used as a plasticizer. One of these plasticizers may be used alone, or two or more may be used in combination.

[0066] Specific examples of the plasticizer include oils, liquid polymers, resins, etc. These may be used alone or in combination of two or more.

[0067] As oil, for example, process oil, vegetable oil, animal oil, etc. can be cited. As process oil, paraffinic process oil (mineral oil), cycloparaffinic process oil, aromatic process oil, etc. can be cited. As specific examples of process oil, for example, mild extract solvate (MES: Mild Extract Solvated), distillate aromatic extract (DAE: Distillate Aromatic Extract), treated distillate aromatic extract (TDAE: Treated Distillate Aromatic Extract), treated residual aromatic extract (TRAE: Treated Residual Aromatic Extract), residual aromatic extract (RAE: Residual Aromatic Extract), etc. can be cited. In addition, for environmental measures, process oil with low content of polycyclic aromatic compounds (PCA) can also be used. As the above-mentioned low PCA content process oil, MES, TDAE, heavy cycloparaffinic oil, etc. can be cited. In addition, from the perspective of life cycle assessment, oil obtained by refining waste oil used in rubber mixers and engines, and waste cooking oil used in restaurants can be used.

[0068] In this specification, as vegetable oil, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia oil, peanut oil, grape seed oil, wood wax, etc. can be cited. In addition, as vegetable oil, refined oil (salad oil, etc.) obtained by refining the above oil, ester exchange oil obtained by transesterifying the above oil, hydrogenated oil obtained by hydrogenating the above oil, thermally polymerized oil obtained by thermally polymerizing the above oil, oxidatively polymerized oil obtained by oxidizing the above oil, and waste edible oil recovered as edible oil, etc. It should be noted that the vegetable oil can be liquid or solid at room temperature (25°C). These vegetable oils can be used alone or in combination of two or more.

[0069] The vegetable oil involved in the present embodiment preferably contains acylglycerols, and more preferably contains triacylglycerols. It should be noted that, in the present specification, acylglycerols refer to compounds in which the hydroxyl group possessed by glycerol forms an ester bond with a fatty acid. There are no particular limitations on the acylglycerols, and they may be 1-monoacylglycerol, or 2-monoacylglycerol, or 1,2-diacylglycerol, or 1,3-diacylglycerol, or triacylglycerol. In addition, the acylglycerols may be monomers, or dimers, or polymers of trimers or higher. It should be noted that acylglycerols of dimers or higher can be obtained by thermal polymerization, oxidative polymerization, etc. In addition, the acylglycerols may be liquid or solid at room temperature (25°C).

[0070] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, and the method can be performed by 1 For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at room temperature (25°C) for 24 hours to remove the rubber composition, and then measured at room temperature. 1 H-NMR, when the signal of tetramethylsilane (TMS) was set to 0.00 ppm, signals were observed near 5.26 ppm, near 4.28 ppm, and near 4.15 ppm, which are presumed to be signals from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. It should be noted that "nearby" in this paragraph refers to the range of ±0.10 ppm.

[0071] The fatty acid is not particularly limited and may be an unsaturated fatty acid or a saturated fatty acid. As unsaturated fatty acids, monounsaturated fatty acids such as oleic acid, polyunsaturated fatty acids such as linoleic acid and linolenic acid may be mentioned. In addition, saturated fatty acids may include butyric acid (butyric acid), lauric acid, etc.

[0072] Among them, as the fatty acid, it is preferred to contain a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, preferably oleic acid. As a vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid can be used, or a vegetable oil modified by transesterification can be used. In addition, in order to produce a vegetable oil containing such a fatty acid, plants can be improved by variety improvement, genetic recombination, genome editing, etc.

[0073] As the oil, for example, commercially available products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEO S Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Manufacturing Co., Ltd., Fuji Kosan Co., Ltd., Nissin Oillio Group Co., Ltd., etc. can be used.

[0074] As the above-mentioned liquid polymer, for example, liquid diene polymers (liquid rubber) or liquid farnesene polymers at 25° C. can be cited. As liquid rubber, liquid styrene-butadiene copolymers (liquid SBR), liquid butadiene polymers (liquid BR), liquid isoprene polymers (liquid IR), liquid styrene-isoprene copolymers (liquid SIR), liquid styrene-butadiene-styrene block copolymers (liquid SBS block polymers), liquid styrene-isoprene-styrene block copolymers (liquid SIS block polymers) etc. can be cited. These ends or main chains can be modified by polar groups. In addition, these hydrides can also be used.

[0075] The weight average molecular weight (Mw) of the liquid diene polymer measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 1.0×10 3 ~5.0×10 4 , more preferably 3.0×10 3 ~1.5×10 4 In addition, the lower limit or upper limit of Mw of the liquid diene polymer may be 4,500 or 8,500. In addition, in this specification, Mw of a liquid diene polymer is a polystyrene conversion value measured by gel permeation chromatography (GPC).

[0076] As the liquid diene polymer, for example, products produced by Sartomer Co., Ltd., Kuraray Co., Ltd., etc. can be used.

[0077] As the above-mentioned resin, commonly used resins can be used as tire compounds, which can be liquid or solid at room temperature (25°C). For example, aromatic vinyl polymers, coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, acrylic resins, etc. can be cited. In addition, the resin can be a hydrogenated resin (hydrogenated resin). They can be used alone or in combination of two or more. In addition, the resin itself can be a copolymer from a variety of monomer components. Among them, hydrogenated resins are preferred from the perspective of better effects. In addition, aromatic vinyl polymers, petroleum resins, terpene resins, and hydrogenated resins of these are preferred.

[0078] Although the mechanism by which the effect can be better obtained when using a hydrogenated resin is not clear, it is presumed that the compatibility with the polymer having ethylene units is increased, oil bleeding is suppressed, and the change in hardness Hs after heat aging is suppressed. As a result, the comprehensive performance of durability and the sustainability of wet grip performance after aging is improved.

[0079] When a resin that is solid at room temperature is used, the softening point of the resin is preferably 50° C. or higher, more preferably 55° C. or higher, further preferably 60° C. or higher, and particularly preferably 85° C. or higher. In addition, it is preferably 160° C. or lower, more preferably 150° C. or lower, further preferably 140° C. or lower, and particularly preferably 100° C. or lower. When it is within the above range, there is a tendency that the effect can be better obtained. When the resin is liquid at room temperature, the softening point is preferably 20° C. or lower, preferably 10° C. or lower, and preferably 0° C. or lower. In the case of hydrogenated resins, the softening point is preferably the same as above. The softening point of the resin is the softening point specified in JIS K6220-1:2001 measured using a ring and ball softening point measuring device, and is the temperature at which the ball falls.

[0080] The aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a structural unit. For example, a resin obtained by polymerizing α-methylstyrene and / or styrene can be cited, and specifically, a homopolymer of styrene (styrene resin), a homopolymer of α-methylstyrene (α-methylstyrene resin), a copolymer of α-methylstyrene and styrene, a copolymer of styrene and other monomers, etc. can be cited.

[0081] The coumarone-indene resin is a resin containing coumarone and indene as main 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, methylindene, vinyltoluene, and the like.

[0082] The coumarone resin is a resin containing coumarone as a main monomer component constituting the resin skeleton (main chain).

[0083] The indene resin is a resin containing indene as a main monomer component constituting the resin skeleton (main chain).

[0084] As the phenolic resin, for example, a known resin such as a polymer obtained by reacting phenols with aldehydes such as formaldehyde, acetaldehyde, and furfural using an acid or alkaline catalyst can be used. Among them, a phenolic resin obtained by reacting them using an acid catalyst (such as a novolac type phenolic resin) is preferred.

[0085] Examples of the rosin resin include rosin-based resins represented by natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

[0086] Examples of the petroleum resin include C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, C9 / DCPD resins, and hydrogenates thereof, among which DCPD resins, hydrogenated DCPD resins, C9 / DCPD resins, and C9 / hydrogenated DCPD resins are preferred.

[0087] The above-mentioned terpene resin is a polymer containing terpene as a structural unit. For example, polyterpene resins obtained by polymerizing terpene compounds, aromatic modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds, etc. can be cited. As aromatic modified terpene resins, terpene phenol resins using terpene compounds and phenolic compounds as raw materials, terpene styrene resins using terpene compounds and styrene compounds as raw materials, and terpene phenol styrene resins using terpene compounds, phenolic compounds and styrene compounds as raw materials can also be used. It should be noted that as terpene compounds, α-pinene, β-pinene, etc. can be cited, as phenolic compounds, phenol, bisphenol A, etc. can be cited, and as aromatic compounds, styrene compounds (styrene, α-methylstyrene, etc.) can be cited. Among them, aromatic modified terpene resins are preferred.

[0088] The acrylic resin is a polymer containing an acrylic monomer as a structural unit. For example, styrene acrylic resins such as styrene acrylic resins obtained by copolymerizing an aromatic vinyl monomer component and an acrylic monomer component having a carboxyl group can be cited. Among them, solvent-free styrene acrylic resins containing a carboxyl group can be preferably used.

[0089] As the above resin, for example, products of Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Co., Ltd., Exxon Mobil Corporation, Kraton, Nippon Paint Chemicals Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Co., Ltd., Arakawa Chemical Industries, Ltd., and Taoka Chemical Industries, Ltd. can be used.

[0090] As the plasticizer, from the viewpoint of sustainability, it is preferred to use a plant-derived plasticizer such as the plant-derived oil or farnesene polymer.

[0091] Farnesene polymers are polymers obtained by polymerizing farnesene, and have structural units based on farnesene. Farnesene includes isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodetetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene), and (E)-β-farnesene having the following structure is preferred. [Chemistry 1]

[0092] The farnesene polymer may be a homopolymer of farnesene (farnesene homopolymer), or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer). They may be used alone, or two or more may be used in combination. Among them, a copolymer of farnesene and a vinyl monomer is preferred.

[0093] As the vinyl monomer, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-tert-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl) dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-tert-butylstyrene, 3-tert-butylstyrene, 4-tert-butylstyrene, vinylxylene, vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene, aromatic vinyl compounds such as diphenylethylene containing tertiary amino groups, or conjugated diene compounds such as butadiene and isoprene, etc., can be mentioned. They can be used alone or in combination of two or more. Among them, butadiene is preferred. That is, as the farnesene-vinyl monomer copolymer, a copolymer of farnesene and butadiene (farnesene-butadiene copolymer) is preferred.

[0094] In the farnesene-vinyl monomer copolymer, the copolymerization ratio of farnesene to vinyl monomer (farnesene / vinyl monomer) is preferably 40 / 60 to 90 / 10 on a mass basis.

[0095] Farnesene polymers can preferably use farnesene polymers having a weight average molecular weight (Mw) of more than 3000 and less than 300,000. The Mw of the farnesene polymer is preferably more than 8000, more preferably more than 10000, and in addition, preferably less than 100,000, more preferably less than 60,000, and further preferably less than 50,000. Within the above range, there is a tendency to better obtain the effect.

[0096] The farnesene polymer may be in a liquid state or a solid state at room temperature (25° C.), and among them, a liquid farnesene polymer that is in a liquid state at room temperature (25° C.) is preferred.

[0097] In the rubber composition for cap tread, the content of the plasticizer (total amount of the plasticizer) is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, and further preferably 50 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and further preferably 75 parts by mass or less. The lower limit is not particularly limited, but within the above range, there is a tendency to obtain better effects. It should be noted that the content of the plasticizer also includes the amount of oil and resin contained in the oil-extended rubber and the resin-filled rubber.

[0098] In the rubber composition for cap tread, the content of the solid plasticizer in a solid state at room temperature (25° C.) is preferably 15 parts by mass or more, more preferably 25 parts by mass or more, and further preferably 30 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and further preferably 50 parts by mass or less. Within the above range, there is a tendency that the effect can be better obtained.

[0099] In the rubber composition for cap tread, the content of the liquid plasticizer in a liquid state at room temperature (25° C.) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and further preferably 20 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 35 parts by mass or less. Within the above range, there is a tendency that the effect can be better obtained. It should be noted that the content of the liquid plasticizer also includes the amount of oil contained in the oil-extended rubber and the amount of liquid resin in the resin-filled rubber filled with the liquid resin.

[0100] In the rubber composition for tread, the content of the above resin (total amount of the resin) is preferably 15 parts by mass or more, more preferably 25 parts by mass or more, and further preferably 30 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and further preferably 50 parts by mass or less. When within the above range, there is a tendency to obtain better effects.

[0101] In the rubber composition for tread, the content of oil (the total amount of oil) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and further preferably 20 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 35 parts by mass or less, relative to 100 parts by mass of the rubber component. When it is within the above range, there is a tendency to obtain better effects. It should be noted that the oil content also includes the amount of oil contained in the oil-extended rubber.

[0102] In the rubber composition for base tread, the content of the plasticizer (total amount of the plasticizer) is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and further preferably 7 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 20 parts by mass or less. When it is within the above range, there is a tendency that the effect can be better obtained. It should be noted that the content of the plasticizer also includes the amount of oil and resin contained in the oil-extended rubber and the resin-filled rubber.

[0103] In the rubber composition for base tread, the content of the solid plasticizer in a solid state at room temperature (25° C.) is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, further preferably 5 parts by mass or less, and may be 0 parts by mass, relative to 100 parts by mass of the rubber component. When within the above range, there is a tendency that the effect can be better obtained.

[0104] In the rubber composition for base tread, the content of the liquid plasticizer in a liquid state at room temperature (25° C.) is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and further preferably 7 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 20 parts by mass or less. When within the above range, there is a tendency that the effect can be better obtained. It should be noted that the content of the liquid plasticizer also includes the amount of oil contained in the oil-extended rubber and the amount of liquid resin in the resin-filled rubber filled with the liquid resin.

[0105] In the rubber composition for base tread, the content of oil (total amount of oil) is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and further preferably 7 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 20 parts by mass or less. When it is within the above range, there is a tendency that the effect can be better obtained. It should be noted that the oil content also includes the amount of oil contained in the oil-extended rubber.

[0106] In the above-mentioned tire, from the perspective of obtaining better effects, preferably, the content Rc (parts by mass) of resin in the rubber composition for the tread surface relative to 100 parts by mass of the rubber component is greater than the content Ob (parts by mass) of oil in the rubber composition for the base tread relative to 100 parts by mass of the rubber component.

[0107] The ratio of Rc to Ob (Rc / Ob) is preferably 2.0 or more, more preferably 4.0 or more, and further preferably 4.3 or more, and is preferably 10.0 or less, more preferably 6.0 or less, and further preferably 5.5 or less. Within the above range, there is a tendency that the effect can be better obtained.

[0108] Although the mechanism by which the effect can be better obtained when Rc / Ob is adjusted to a predetermined range is not clear, it is presumed as follows: by compounding a larger content (Rc) of the resin in the cap tread than the content (Ob) of the oil in the base tread, the change in hardness Hs over time due to oil seepage can be further suppressed, thereby improving the durability of the tire.

[0109] The rubber composition for cap treads and the rubber composition for base treads preferably contain a filler. The filler is not particularly limited, and materials known in the rubber field can be used, for example, inorganic fillers such as carbon black, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica, biochar (BIOCHAR); poorly dispersible fillers, etc. Among them, carbon-derived fillers such as carbon black (carbon-containing fillers) and silica are preferred from the perspective of obtaining better effects.

[0110] In the rubber composition for the tread surface and the rubber composition for the base tread, there is no particular limitation on the carbon black that can be used, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. As commercial products, products of Asahi Carbon Co., Ltd., Cabot Japan KK, Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nichia Carbon Co., Ltd., and Columbia Carbon Inc. can be used. They can be used alone, or two or more can be used in combination. In addition, in addition to the conventional carbon black made from mineral oil or the like, carbon black made from biomass materials such as lignin can also be used. Furthermore, recycled carbon black obtained by decomposing rubber products such as tires and plastic products containing carbon black may be appropriately used in place of the above-mentioned carbon black in an equal amount.

[0111] Nitrogen adsorption specific surface area of ​​carbon black (N 2 SA) is preferably 5m 2 / g or more, more preferably 10m 2 / g or more, more preferably 15m 2 / g or more. In addition, the above N 2 SA is preferably 150m 2 / g or less, more preferably 130m 2 / g or less, more preferably 120m 2 When it is within the above range, there is a tendency that the effect can be better obtained. In addition, the nitrogen adsorption specific surface area of ​​carbon black is calculated|required according to JIS K6217-2:2001.

[0112] The dibutyl phthalate oil absorption (DBP) of carbon black is preferably 40 ml / 100 g or more, more preferably 60 ml / 100 g or more, and further preferably 70 ml / 100 g or more. In addition, the DBP is preferably 200 ml / 100 g or less, more preferably 150 ml / 100 g or less, and further preferably 100 ml / 100 g or less. When it is within the above range, there is a tendency that the effect can be better obtained. In addition, the DBP of carbon black is calculated|required by the measurement method of JIS K6217-4:2001.

[0113] In the rubber composition for the tread surface and the rubber composition for the base tread, there is no particular limitation on the silica that can be used. For example, silica commonly used in the tire industry such as silica modulated by a dry method (anhydrous silica) and silica modulated by a wet method (hydrous silica) can be used. The raw material of silica is not particularly limited. For example, it can be a raw material from minerals such as quartz, or a raw material from organisms such as rice husks (for example, silica made from biomass materials such as rice husks), or silica recycled from products containing silica can be used. Among them, hydrous silica modulated by a wet method is preferred because of the large number of silanol groups. These silicas can be used alone or in combination of two or more.

[0114] Silica made from biomass materials can be obtained, for example, by the following method: silicate is extracted from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, the silicate is reacted with sulfuric acid in the same manner as conventional wet silica to produce a silica precipitate, and the obtained silica precipitate is filtered, washed with water, dried, and crushed.

[0115] The silicon dioxide recovered and reused from the products containing silicon dioxide can be, for example, silicon dioxide recovered from electronic components such as semiconductors, tires, desiccants, diatomaceous earth and other products containing silicon dioxide. In addition, the recovery method is not particularly limited, and thermal decomposition, decomposition by electromagnetic waves, etc. can be cited. Among them, silicon dioxide recovered from electronic components such as semiconductors or tires is preferred.

[0116] When silicon dioxide crystallizes, it is insoluble in water, so its component silicic acid cannot be used. By controlling the combustion temperature and combustion time, the crystallization of silicon dioxide in rice husk ash can be suppressed (see: JP-2009-2594; Akita Prefectural University Online Journal B / 2019, Vol. 6, pp. 216-222, etc.).

[0117] Amorphous silica extracted from rice husks may be commercially available products such as those produced by Wilmar.

[0118] The nitrogen adsorption specific surface area of ​​silicon dioxide (N 2 SA) is preferably 50m 2 / g or more, more preferably 100m 2 / g or more, more preferably 150m 2 / g or more. In addition, N 2 The upper limit of SA is not particularly limited, but is preferably 350 m 2 / g or less, more preferably 300m 2 / g or less, more preferably 250m 2 When it is within the above range, there is a tendency that the effect can be better obtained. It should be noted that the N 2 SA is a value measured by the BET method according to ASTM D3037-93.

[0119] Examples of the poorly dispersible filler include microfibrillated plant fibers, short-fiber cellulose, and gel-like compounds. Among them, microfibrillated plant fibers are preferred.

[0120] As the above-mentioned microfibrillated plant fiber, cellulose microfibrils are preferred from the perspective of obtaining good reinforcement. As cellulose microfibrils, as long as they are cellulose microfibrils from natural objects, there is no particular limitation, for example, can be cited: cellulose microfibrils from resource biomass such as fruits, grains, root vegetables, wood, bamboo, hemp, jute, kenaf, and waste biomass such as pulp or paper, cloth, crop waste, food waste or sewage sludge obtained from them as raw materials, unused biomass such as straw, wheat straw, thinning materials, and cellulose microfibrils produced by sea squirts, acetic acid bacteria, etc. These microfibrillated plant fibers can be used in one kind, or two or more kinds can be used in combination.

[0121] It should be noted that, in this specification, cellulose microfibrils typically refer to cellulose fibers having an average fiber diameter of 10 μm or less, and more typically refer to cellulose fibers having a microstructure with an average fiber diameter of 500 nm or less formed by the aggregation of cellulose molecules. Typical cellulose microfibrils are formed, for example, as aggregates of cellulose fibers having the above-mentioned average fiber diameter.

[0122] In the rubber composition for a tread, the content of the filler (the total amount of fillers such as silica and carbon black) is preferably 50 parts by mass or more, more preferably 80 parts by mass or more, and further preferably 83 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and further preferably 100 parts by mass or less. Within the above range, there is a tendency for the comprehensive performance of durability and the sustainability of wet grip performance after time to be improved.

[0123] Although the mechanism by which the effect can be better obtained when the filler content is adjusted to a predetermined level or more, especially 50 parts by mass or more, is not clear, it is speculated as follows: by increasing the filler content, the polymer ratio is reduced, thereby suppressing the change in physical properties after heat aging. Therefore, the comprehensive performance of durability and the sustainability of wet grip performance after aging is improved.

[0124] In the rubber composition for tread, the content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 10 parts by mass or less. When within the above range, there is a tendency to obtain better effects.

[0125] In the rubber composition for cap tread, the content of silica is preferably 60 parts by mass or more, more preferably 70 parts by mass or more, and further preferably 75 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 150 parts by mass or less, more preferably 130 parts by mass or less, and further preferably 120 parts by mass or less. When it is within the above range, there is a tendency that the effect can be better obtained.

[0126] When the rubber composition for tread contains a poorly dispersible filler, the content of the poorly dispersible filler is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more, relative to 100 parts by mass of the rubber component. The upper limit of the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, further preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less. Within the above range, there is a tendency to obtain better effects.

[0127] In the rubber composition for base tread, the content of filler (the total amount of fillers such as silica and carbon black) is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, and further preferably 50 parts by mass or less. When it is within the above range, there is a tendency that the effect can be better obtained.

[0128] In the rubber composition for base tread, the content of carbon black is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, and further preferably 50 parts by mass or less. When it is within the above range, there is a tendency that the effect can be better obtained.

[0129] In the rubber composition for base tread, the content of silica is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, further preferably 5 parts by mass or less, and may be 0 parts by mass, relative to 100 parts by mass of the rubber component. When it is within the above range, there is a tendency that the effect can be better obtained.

[0130] When the rubber composition for the base tread contains a poorly dispersible filler, the content of the poorly dispersible filler is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more, relative to 100 parts by mass of the rubber component. The upper limit of the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, further preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less. Within the above range, there is a tendency to obtain better effects.

[0131] The ratio (Fc / Fb) of the content Fc of the filler relative to 100 parts by mass of the rubber component in the rubber composition for the tread cap to the content Fb of the filler relative to 100 parts by mass of the rubber component in the rubber composition for the base tread is preferably 1.6 or more, more preferably 2.2 or more, further preferably 2.5 or more, and particularly preferably 2.7 or more. The upper limit of Fc / Fb is not particularly limited, but is preferably 5.0 or less, more preferably 4.5 or less, and further preferably 4.0 or less. Within the above range, there is a tendency to obtain better effects.

[0132] Although the mechanism by which the effect can be better obtained when Fc / Fb is adjusted to a predetermined value or more, especially to a value of 2.2 or more, is not clear, it is presumed as follows: by compounding the filler content (Fc) of the cap tread more than the predetermined value compared to the filler content (Fb) of the base tread, the polymer ratio in the cap tread is reduced, thereby suppressing the change in physical properties after heat aging. Therefore, durability is improved.

[0133] The ratio of the carbon black content Cc in the rubber composition for the cap tread relative to 100 parts by mass of the rubber component to the carbon black content Cb in the rubber composition for the base tread relative to 100 parts by mass of the rubber component (Cc / Cb) is preferably 0.10 or more, more preferably 0.15 or more, and further preferably 0.17 or more. The upper limit of Cc / Cb is not particularly limited, but is preferably 0.30 or less, more preferably 0.23 or less, and further preferably 0.20 or less. Within the above range, there is a tendency to obtain better effects.

[0134] Although the mechanism by which the effect can be better obtained when Cc / Cb is adjusted to a predetermined value or more, especially to a value of 0.15 or more, is not clear, it is speculated as follows: by compounding the carbon black content (Cc) of the cap tread to a predetermined value or more than the carbon black content (Cb) of the base tread, the polymer ratio in the cap tread is reduced, thereby suppressing the change in physical properties after heat aging. Therefore, the comprehensive performance of durability and the sustainability of wet grip performance after aging is improved.

[0135] When the rubber composition for a cap tread or the rubber composition for a base tread contains silica, it is further preferred that a silane coupling agent is contained. The silane coupling agent is not particularly limited, and any silane coupling agent known in the rubber field can be used. 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)tetrasulfide, and bis(4-triethoxysilylbutyl)tetrasulfide. 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-disulfide Sulfide-based silane coupling agents such as methylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z manufactured by Momentive; vinyltriethoxysilane, vinyltrimethoxysilane Vinyl silane coupling agents such as silane; amino silane coupling agents such as 3-aminopropyl triethoxysilane and 3-aminopropyl trimethoxysilane; glycidoxy silane coupling agents such as γ-glycidoxy propyl triethoxysilane and γ-glycidoxy propyl trimethoxysilane; nitro silane coupling agents such as 3-nitropropyl trimethoxysilane and 3-nitropropyl triethoxysilane; chlorine silane coupling agents such as 3-chloropropyl trimethoxysilane and 3-chloropropyl triethoxysilane. As commercially available products, products of Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., AZmax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used. They can be used alone or in combination of two or more.

[0136] In the rubber composition for the tread cap and the rubber composition for the base tread, the content of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, relative to 100 parts by mass of silicon dioxide. The upper limit of the content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, further preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. Within the above range, there is a tendency to better obtain the effect.

[0137] The rubber composition for cap treads and the rubber composition for base treads preferably contain an antioxidant from the viewpoint of crack resistance, ozone resistance, and the like.

[0138] The antioxidant is not particularly limited, and examples thereof include naphthylamine antioxidants such as phenyl-α-naphthylamine; diphenylamine 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 (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditolyl- p-phenylenediamine antioxidants such as p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-tert-butyl-4-methylphenol and styrenated phenol; bisphenol, trisphenol, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane, etc. Among them, p-phenylenediamine antioxidants and quinoline antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flexsys Corporation, etc. can be used.

[0139] In the rubber composition for cap treads and the rubber composition for base treads, the content of the antioxidant is preferably 0.2 parts by mass or more, more preferably 2.0 parts by mass or more, and further preferably 2.5 parts by mass or more, relative to 100 parts by mass of the rubber component. The content is preferably 7.0 parts by mass or less, and more preferably 3.5 parts by mass or less.

[0140] The rubber composition for cap treads and the rubber composition for base treads preferably contain stearic acid. In the rubber composition for cap treads and the rubber composition for base treads, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 2.0 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, relative to 100 parts by mass of the rubber component.

[0141] As stearic acid, conventionally known stearic acid can be used. For example, products of NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used.

[0142] The rubber composition for cap treads and the rubber composition for base treads preferably contain zinc oxide. In the rubber composition for cap treads and the rubber composition for base treads, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 2.0 parts by mass or more, and is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, per 100 parts by mass of the rubber component.

[0143] As zinc oxide, conventionally known zinc oxide can be used, for example, products of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., HakusuiTech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0144] The rubber composition for cap treads and the rubber composition for base treads may contain wax. In the rubber composition for cap treads and the rubber composition for base treads, the wax content is preferably 1.0 parts by mass or more, more preferably 1.5 parts by mass or more, and is preferably 10.0 parts by mass or less, more preferably 2.0 parts by mass or less, per 100 parts by mass of the rubber component.

[0145] As wax, there is no particular limitation, and any of the waxes commonly used in the tire industry can be appropriately used. For example, petroleum wax, mineral wax, synthetic wax, wax from plant, etc. can be cited. Among them, petroleum wax and wax from plant are preferred, and petroleum wax is more preferred. As wax from plant, for example, rice bran wax, carnauba wax (carnaubawax), candelilla wax, etc. can be cited. As petroleum wax, for example, paraffin wax, microcrystalline wax, these selected special waxes, etc. can be cited, preferably paraffin wax. It should be noted that the wax of the present embodiment does not contain stearic acid. Regarding wax, for example, commercial products of Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seira Co., Ltd., Paramelt Co., Ltd., etc. can be used. These waxes can be used alone, or two or more can be used in combination.

[0146] It is preferred to blend sulfur into the rubber composition for cap treads and the rubber composition for base treads from the viewpoint of forming appropriate crosslinking chains on polymer chains and imparting good performance.

[0147] In the rubber composition for cap treads, the sulfur content is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and further preferably 1.5 parts by mass or more, relative to 100 parts by mass of the rubber component. The sulfur content is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, and further preferably 2.0 parts by mass or less.

[0148] In the rubber composition for a base tread, the sulfur content is preferably 1.0 parts by mass or more, more preferably 2.0 parts by mass or more, and further preferably 2.5 parts by mass or more, relative to 100 parts by mass of the rubber component. The sulfur content is preferably 7.0 parts by mass or less, more preferably 5.0 parts by mass or less, and further preferably 4.0 parts by mass or less.

[0149] Sulfur includes powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. As commercially available products, products of Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexsys Co., Ltd., Nippon Innolux Co., Ltd., Hosoi Chemical Co., Ltd., etc. can be used. These can be used alone or in combination of two or more.

[0150] The rubber composition for cap treads and the rubber composition for base treads may contain, in addition to the above-mentioned components, a compounding agent commonly used in the tire industry, for example, a release agent or the like.

[0151] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) can be derived from carbon dioxide in the atmosphere. As a method for obtaining the above-mentioned compound from carbon dioxide, carbon dioxide can be directly converted, or methane obtained by a methanogenic process of synthesizing methane from carbon dioxide can be converted.

[0152] In the rubber composition for a tread, from the perspective of comprehensive performance of durability and sustainability of wet grip performance over time, preferably, the content of the polymer having ethylene units in 100% by mass of the rubber component is 50% by mass or more, and the content of the resin relative to 100 parts by mass of the rubber component is 20 parts by mass or more.

[0153] Although the mechanism by which the effect can be better obtained when the content of the polymer having ethylene units and the content of the resin are adjusted to a predetermined level or above is not clear, it is believed that the following is true: by combining the compound represented by formula (1) with a formulation containing a polymer having ethylene units with few double bonds and good physical properties after heat aging, the single crosslinking ratio is increased, and further, the hardness change and tensile property change after heat aging are reduced. In addition, by adding more resins, the change in hardness over time is reduced. Therefore, the comprehensive performance of durability and the continuity of wet grip performance over time is improved.

[0154] The rubber composition for cap treads and the rubber composition for base treads can be produced by, for example, kneading the above-mentioned components using a rubber kneading device such as an open roll or a Banbury mixer, followed by vulcanization.

[0155] As the mixing conditions, in the basic mixing step of mixing additives other than the crosslinking agent (vulcanizing agent) and the vulcanization accelerator, the mixing temperature is preferably 100°C or more, more preferably 120°C or more, and preferably 180°C or less, and more preferably 170°C or less. In the final mixing step of mixing the vulcanizing agent and the vulcanization accelerator, the mixing temperature is preferably 80°C or more, and preferably 120°C or less, and more preferably 110°C or less. In addition, the composition mixed with the vulcanizing agent and the vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. As the vulcanization temperature, it is preferably 140°C or more, more preferably 150°C or more, and preferably 190°C or less, and more preferably 185°C or less.

[0156] The rubber composition for a cap tread and the rubber composition for a base tread are used for a cap tread and a base tread of tire components, respectively.

[0157] It should be noted that, in the present specification, the tread running surface refers to the rubber layer that forms the outermost layer in the radial direction of the tire among the rubber layers constituting the tread. In the case where the tread is a single-layer structure tread, the single-layer structure tread itself, in the case where the tread is a two-layer structure of a tread running surface and a tread base, the rubber layer that forms the surface layer, and in the case of a tread having a structure with more than three layers, the rubber layer that forms the outermost layer respectively correspond to the tread running surface.

[0158] In the present specification, the tread base refers to a rubber layer that is arranged on the radially inner side of the tread running surface that forms the outermost layer in the radial direction of the tire among the rubber layers constituting the tread of the multi-layer structure. In the case of a tread with a two-layer structure of the tread running surface and the tread base, the rubber layer that forms the radially inner side of the tire and in the case of a tread with a structure having three or more layers, one layer or two or more layers of the rubber layer that are arranged on the radially inner side of the tread running surface correspond to the tread base.

[0159] The tire is manufactured by a conventional method using the rubber composition for cap tread and the rubber composition for base tread. That is, in the unvulcanized stage, the composition mixed with various additives as needed is extruded into the shape of cap tread and base tread, formed in a conventional manner on a tire molding machine, and bonded together with other tire components to form an unvulcanized tire, and then heated and pressurized in a vulcanizer to manufacture the tire.

[0160] The tire is not particularly limited, and examples thereof include pneumatic tires, solid tires, and non-pneumatic tires (airless tires), etc. Among them, pneumatic tires are preferred.

[0161] The above tires can be suitably used as passenger car tires, large passenger car tires, large SUV tires, truck / bus tires, two-wheeled vehicle tires, racing tires, winter tires (studless tires, snow tires, studded tires), all-season tires, run-flat tires, aircraft tires, mining tires, etc.

[0162] In the above tire, the thickness Tc (mm) of the tread running surface is preferably 12 mm or less, more preferably 10 mm or less, and further preferably 9 mm or less. The lower limit is preferably 5 mm or more, more preferably 6 mm or more, and further preferably 7 mm or more. Within the above range, there is a tendency to appropriately obtain the effect.

[0163] In the above tire, the thickness Tb (mm) of the tread base is preferably 4 mm or less, more preferably 3 mm or less. The lower limit is preferably 0.5 mm or more, more preferably 1 mm or more. Within the above range, there is a tendency that the effect can be appropriately obtained.

[0164] Tc / Tb is preferably 1.5 or more, more preferably 2.1 or more, further preferably 3.0 or more, and particularly preferably 3.5 or more. The upper limit is preferably 9.2 or less, more preferably 7.0 or less, and further preferably 5.0 or less. Within the above range, there is a tendency that the effect can be appropriately obtained.

[0165] Although the mechanism by which the effect can be better obtained when Tc / Tb is adjusted to a predetermined range is not clear, it is presumed that the change in hardness Hs over time due to plasticizer bleeding can be further suppressed, thereby improving the durability of the tire.

[0166] In the above tire, the ratio (Dc / Tc) of the content Dc (parts by mass) of the compound represented by the above formula (1) in the rubber composition for the tread surface relative to 100 parts by mass of the rubber component to the thickness Tc (mm) of the tread surface is preferably 0.01 or more, more preferably 0.02 or more, further preferably 0.04 or more, and particularly preferably 0.06 or more. The upper limit is preferably 0.15 or less, more preferably 0.12 or less, and further preferably 0.10 or less. Within the above range, there is a tendency to appropriately obtain the effect.

[0167] Although the mechanism by which the effect can be better obtained when Dc / Tc is adjusted to a value above the prescribed value is not clear, it is presumed that by adding a larger amount of the compound of formula (1) per unit thickness, the co-crosslinking property of the cap tread and the base tread is improved, and the change in hardness Hs over time caused by oil seepage can be further suppressed. Therefore, the durability of the tire is improved.

[0168] It should be noted that in this specification, the thickness Tc of the tread running surface (running surface layer) refers to the thickness of the tread running surface on the equatorial plane of the tire in the radial section of the tire. In the radial section of the tire, it is the straight-line distance from the tread surface (the surface of the tread running surface) to the radial inner side of the tread running surface of the tire.

[0169] The thickness Tb of the base tread (base layer) refers to the thickness of the base tread on the tire equatorial plane in the radial cross section of the tire. In the radial cross section of the tire, it is the straight-line distance from the radial outer surface of the base tread to the radial inner surface of the base tread.

[0170] The thickness of the cap tread and the base tread on the tire equatorial plane are respective values ​​measured along the tire equatorial plane from the outermost surfaces of the cap tread and the outermost surfaces of the base tread on the tire equatorial plane. When there is a conducting member or the like on the tire equatorial plane, this is a value measured along the tire equatorial plane from a straight line connecting the ends of the interface blocked by the conducting member. When there are grooves on the equatorial plane of the tire, the thickness is measured at the center of the tire width direction of the land portion closest to the equatorial plane of the tire, and is the thickness measured in the normal direction of the radial outer surface of the tire on the tread running surface and the radial outer surface of the tire on the tread base.

[0171] In this specification, the dimensions such as thickness are values ​​measured under normal conditions. "Normal condition" refers to a state in which the tire rim is assembled on a normal rim and filled with a normal internal pressure and is unloaded. Here, the "normal rim" is a rim specified for each tire in a specification system including the specifications on which the tire is based, for example, in the case of JATMA (Japan Automobile Tire Association), it refers to the standard rim in the applicable size recorded in the "JATMA Yearbook (JATMA YEAR BOOK)", in the case of ETRTO (The European Tyre and Rim Technical Organisation) it refers to the "Measuring Rim" recorded in the "Standards Manual (STANDARDS MANUAL)", and in the case of TRA (The Tire and Rim Association, Inc.) it refers to the "Design Rim" recorded in the "Yearbook (YEAR BOOK)", and refer to JATMA, ETRTO, TRA in this order, and if there is an applicable size when referring, it is in accordance with the specification. In addition, in the case of tires not specified in the specifications, it refers to the rim with the smallest rim diameter and the narrowest rim width in the rim that can be assembled on the rim and can maintain the internal pressure, that is, the rim that does not leak air from the rim / tire. In addition, "regular internal pressure" refers to the air pressure specified for each tire in each specification in the specification system including the specifications based on the tire, and in the case of JATMA, it refers to the "maximum air pressure", in the case of ETRTO, it refers to the "inflation pressure (INFLATIONPRESSURE)", and in the case of TRA, it refers to the maximum value recorded in the table "Tire load limits at various cold inflation pressures (TIRE LOAD LIMITS AT VARIOUS COLD INFLATIONPRESSURES)", and is referred to in the order of JATMA, ETRTO, and TRA. When referring to the applicable size, if there is one, it is in accordance with the specification. In the case of tires not specified in the specifications, it refers to the regular internal pressure (of which 250 kPa or more) of other tire sizes (tire sizes specified in the specifications) recorded with the above-mentioned regular rim as the standard rim. In addition, when a plurality of normal internal pressures of 250 kPa or more are described, it refers to the minimum value among them.

[0172] Hereinafter, an example of the above-mentioned tire will be described using drawings, but the tire is not limited to this form.

[0173] Figure 1In the figure, the up-down direction is the radial direction of the tire 2, the left-right direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. The tire 2 is bilaterally symmetrical. The tread 4 includes a cap layer 30 (cap tread) and a base layer 28 (base tread).

[0174] It should be noted that although Figure 1 , an example of a two-layer structure tread 4 composed of a cap layer 30 and a base layer 28 is shown, but a single-layer structure tread or a tread having a structure of three or more layers may also be used.

[0175] Figure 1 In the tire 2, the cap layer 30 is composed of the rubber composition for cap tread, the base layer 28 is composed of the rubber composition for base tread, the cap layer 30 contains a polymer having ethylene units, an isoprene rubber and a compound represented by the above formula (1), and the content of the isoprene rubber in 100% by mass of the rubber component is 20% by mass or more. In addition, the content of the isoprene rubber in 100% by mass of the rubber component of the base layer 28 is greater than the content of the isoprene rubber in 100% by mass of the rubber component of the cap layer 30.

[0176] In the tire 2, each sidewall 6 extends radially inward from the end of the tread 4. The radially outer portion of the sidewall 6 is joined to the tread 4. The radially inner portion of the sidewall 6 is joined to the lap portion 10. The sidewall 6 can prevent damage to the carcass 14.

[0177] Figure 1 Each tread wing 8 is located between the tread 4 and the sidewall 6. The tread wing 8 is joined to the tread 4 and the sidewall 6, respectively.

[0178] Each clinch portion 10 is located substantially radially inward of the sidewall 6 and has at least one portion that contacts the rim.

[0179] The carcass 14 includes a carcass ply 36. In the tire 2, the carcass 14 is composed of a single carcass ply 36, but may be composed of two or more layers.

[0180] In the tire 2, the carcass ply 36 is laid between the bead cores 32 on both sides and along the tread 4 and the sidewall 6. The carcass ply 36 is folded from the axial inside to the outside around each bead core 32. By the folding, a main body 36a and a pair of folded parts 36b are formed in the carcass ply 36. That is, the carcass ply 36 includes a main body 36a and a pair of folded parts 36b.

[0181] Each bead core 32 includes a bead apex 34 extending radially outward from the bead core 32. The bead core 32 is annular and preferably includes a wound inelastic wire. The bead apex 34 tapers radially outward.

[0182] Although not shown, the carcass ply 36 is preferably formed of a plurality of parallel cords and a topping rubber. The absolute value of the angle formed by each cord with respect to the equatorial plane CL is preferably 75° to 90°. In other words, the carcass 14 preferably has a radial structure.

[0183] Figure 1 The belt layer 16 is located radially inward of the tread 4. The belt layer 16 is stacked with the carcass 14. The belt layer 16 reinforces the carcass 14. Figure 1 In the tire 2, the belt layer 16 is composed of an inner layer 38 and an outer layer 40. Figure 1 As can be clearly seen in the figure, preferably, in the axial direction, the width of the inner layer 38 is slightly larger than the width of the outer layer 40. In the tire 2, the axial width of the belt layer 16 is preferably greater than 0.6 times the cross-sectional width of the tire 2, and preferably less than 0.9 times.

[0184] Preferably, the inner layer 38 and the outer layer 40 are each formed of a plurality of steel cords (steel monofilaments) and a topping rubber (covering rubber) arranged in parallel. In other words, the belt layer 16 includes a plurality of steel monofilaments arranged in parallel.

[0185] Figure 1 The band layer 18 is located radially outside the belt layer 16. In the axial direction, the band layer 18 has a width equal to that of the belt layer 16. The width of the band layer 18 may be greater than that of the belt layer 16.

[0186] Although not shown in the figure, the belt layer 18 is preferably formed of a cord and a topping rubber. The cord is wound in a spiral shape. The belt layer 18 has a so-called annular structure. The cord substantially extends in the circumferential direction. The angle of the cord relative to the circumferential direction is preferably 5° or less, and more preferably 2° or less. Since the belt layer 16 is constrained by the cord, the lifting of the belt layer 16 is suppressed.

[0187] Figure 1 The belt layer 16 and the band layer 18 constitute a reinforcing layer. The reinforcing layer may be constituted by the belt layer 16 alone.

[0188] Figure 2 yes Figure 1 An enlarged view of the vicinity of tread 4. Figure 2 The tire is a tire 2 having grooves 26 on the tire equatorial plane (on CL). In this case, the thickness of the tread running surface (Tc) is the thickness measured at the center of the tire width direction of the land portion of the groove 26 on the equatorial plane closest to the tire in the radial cross-section of the tire, and is the thickness measured in the normal direction of the surface of the running surface layer 30 (tread running surface). Specifically, it refers to the straight-line distance in the normal direction between the interface between the radial outer surface of the running surface layer 30 and the outermost side of the base layer 28. In addition, the thickness of the tread base (Tb) is the thickness measured at the center of the tire width direction of the land portion of the groove 26 on the equatorial plane closest to the tire in the radial cross-section of the tire. It is the thickness measured in the normal direction of the radial outer surface of the base layer 28 (tread base). Specifically, it refers to the straight-line distance in the normal direction between the outer surface of the base layer 28 and the interface on the outermost side of the tire of the belt layer 18.

[0189] The inner liner 20 is located inside the carcass 14. The inner liner 20 is bonded to the inner surface of the carcass 14. A typical base rubber of the inner liner 20 is butyl rubber or halogenated butyl rubber. The inner liner 20 maintains the internal pressure of the tire 2.

[0190] Each chafer 22 is located near the bead 12. In this embodiment, preferably, the chafer 22 is formed of cloth and rubber impregnated in the cloth. The chafer 22 may be formed integrally with the clinch 10.

[0191] In the tire 2, the tread 4 has a main groove 42 as the groove 26. Figure 1 As shown, a plurality of (specifically, three) main grooves 42 are engraved on the tread 4. These main grooves 42 are arranged at intervals in the axial direction. On the tread 4, four patterns 44 (ribs; rib-type patterns) extending in the circumferential direction are formed by engraving three main grooves 42. In other words, the main grooves 42 are between the patterns 44 and the patterns 44.

[0192] Each main groove 42 extends in the circumferential direction. The main groove 42 is continuous in the circumferential direction without interruption. The main groove 42 promotes drainage of water between the road surface and the tire 2, for example, on rainy days. Therefore, even if the road surface is wet, the tire 2 can fully contact the road surface.

[0193] In the tire 2, the content Rc (parts by mass) of the resin and the content Oc (parts by mass) of the oil in the cap layer 30 relative to 100 parts by mass of the rubber component, the content Ob (parts by mass) of the oil in the base layer relative to 100 parts by mass of the rubber component, the content Pc (parts by mass) of the plasticizer in the cap layer 30 relative to 100 parts by mass of the rubber component, the content Pb (parts by mass) of the plasticizer in the base layer 28 relative to 100 parts by mass of the rubber component, the filler content in the cap layer 30 relative to 100 parts by mass of the rubber component The content Fc of the filler, the content Fb of the filler in the base layer relative to 100 parts by mass of the rubber component, the content Cc of the carbon black in the driving surface layer 30 relative to 100 parts by mass of the rubber component, the content Cb of the carbon black in the base layer 28 relative to 100 parts by mass of the rubber component, the thickness Tc (mm) of the driving surface layer 30, the thickness Tb (mm) of the base layer 28, Rc / Oc, Oc / Ob, Rc / Ob, Pc / Pb, Fc / Fb, Cc / Cb, Tc / Tb, Rc / Tc are preferably within the above-mentioned ranges. Example

[0194] Hereinafter, examples (embodiments) considered to be preferable when implemented are shown, but the scope of the present disclosure is not limited to the embodiments.

[0195] The following is a summary of various chemicals used in synthesis and polymerization. It should be noted that the chemicals are purified according to conventional methods as needed. n-Hexane: Made by Kanto Chemical Co., Ltd. Styrene: Made by Kanto Chemical Co., Ltd. Butadiene: 1,3-Butadiene manufactured by Tokyo Chemical Industry Co., Ltd. TMEDA: N,N,N',N'-Tetramethylethylenediamine manufactured by Kanto Chemical Co., Ltd. n-Butyl lithium solution: 1.6 M n-Butyl lithium hexane solution manufactured by Kanto Chemical Co., Ltd.

[0196] In addition, the evaluation methods of the copolymers are summarized and described below.

[0197] (Measurement of Hydrogenation Rate of Conjugated Diene Moiety of Copolymer) Carbon tetrachloride was used as a solvent to prepare a 15 mass % solution, and the 1 The spectrum reduction rate of the unsaturated bond portion of H-NMR was calculated.

[0198] (Determination of Styrene Content) The concentration of NMR was measured at 25°C using a JEOL JNM-A 400 NMR instrument. 1The styrene content was determined from the ratio of 6.5 to 7.2 ppm of phenyl protons based on styrene units to 4.9 to 5.4 ppm of vinyl protons based on butadiene units determined from the H-NMR spectrum.

[0199] (Measurement of weight average molecular weight (Mw)) The weight average molecular weight (Mw) of the copolymer was determined by conversion to standard polystyrene based on the value measured by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0200] (Production Example 1: Synthesis of hydrogenated styrene-butadiene copolymer 1: hydrogenation rate 95 mol%) In a heat-resistant reaction vessel fully purged with nitrogen, 2000 ml of n-hexane, 60 g of styrene, 140 g of butadiene, 0.93 g of TMEDA, and 0.45 mmol of n-butyl lithium were added, and the mixture was stirred at 50°C for 5 hours to carry out a polymerization reaction. Next, hydrogen was supplied at a pressure of 0.4 MPa-Gauge while stirring for 20 minutes to allow the hydrogen to react with the unreacted polymer terminal lithium to generate lithium hydride. The hydrogen supply pressure was set to 0.7 MPa-Gauge, the reaction temperature was set to 90°C, and hydrogenation was carried out using a catalyst based on dichlorodipentadienyl titanocene. When the absorption of hydrogen reaches the cumulative amount that becomes the target hydrogenation rate, the reaction temperature is adjusted to room temperature, the hydrogen pressure is restored to normal pressure, the copolymer is taken out from the reaction vessel, the reaction solution is stirred and poured into water, and the solvent is removed by steam stripping to obtain a hydrogenated styrene-butadiene copolymer 1 (hydrogenation rate: 95 mol%, weight average molecular weight (Mw): 450,000, styrene content: 30% by mass, butadiene content: 70% by mass).

[0201] (Production Example 2: Synthesis of hydrogenated styrene-butadiene copolymer 2: hydrogenation rate 80 mol %) Hydrogenated styrene-butadiene copolymer 2 (hydrogenation rate: 80 mol %, weight average molecular weight (Mw): 480,000, styrene content: 30 mass %, butadiene content: 70 mass %) was obtained according to the same formulation as hydrogenated styrene-butadiene copolymer 1, except that the cumulative amount of hydrogen absorption was adjusted to achieve the target hydrogenation rate.

[0202] The following is a summary of various chemicals used in the production of cap treads and base treads. It should be noted that the chemicals are purified according to conventional methods as necessary. (Tread surface) Hydrogenated styrene-butadiene copolymers 1 and 2: the above-mentioned Production Examples 1 and 2 (polymers having ethylene units) NR:TSR20 Carbon black: Shoblack N220 (N 2 SA: 111m 2 / g) Silicon dioxide: Ultrasil VN3 (N 2 SA: 175m 2 / g) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. Antioxidant: Antigene 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Oil: Vivatec 500 (TDAE, aromatic processing oil) manufactured by H&R Resin 1: Sylvatraxx 4401 (styrene-α-methylstyrene resin (copolymer of styrene and α-methylstyrene) manufactured by Arizona Chemical Company) Resin 2: PR120 manufactured by Exxon Mobil Corporation (hydrogenated dicyclopentadiene resin, softening point 120°C) Stearic acid: Tsubaki manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 2 manufactured by Mitsui Metal Industries, Ltd. Sulfur: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd. Vulcanization accelerator CZ: Nocceler CZ-G (N-cyclohexyl-2-benzothiazole sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator DPG: Nocceler D (N,N'-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator TBzTD: Sanshin Chemical Industry Co., Ltd. (tetrabenzylthiuram disulfide)

[0203] (Tread base) NR:SIR20 BR: BR150B manufactured by Ube Industries, Ltd. Carbon black: Shoblack N220 (N 2 SA: 111m 2 / g) Oil: Aroma oil manufactured by JX Nippon Oil & Energy Corporation Stearic acid: Tsubaki manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 2 manufactured by Mitsui Metal Industries, Ltd. Antioxidant: Antigene 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. Sulfur: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd. Vulcanization accelerator TBBS: Nocceler NS (N-tert-butyl-2-benzothiazole sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0204] (Production of rubber composition for cap tread) According to the formulation shown in Table 1, materials other than sulfur and the vulcanization accelerator were kneaded at 150° C. for 5 minutes using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded product. Sulfur and a vulcanization accelerator were added to the kneaded product, and the mixture was kneaded at 80° C. for 5 minutes using an open roll mill to obtain an unvulcanized rubber composition.

[0205] (Preparation of rubber composition for base tread) According to the formulation shown in Table 2, materials other than sulfur and the vulcanization accelerator were kneaded at 150° C. for 5 minutes using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded product. Sulfur and a vulcanization accelerator were added to the kneaded product, and the mixture was kneaded at 80° C. for 5 minutes using an open roll mill to obtain an unvulcanized rubber composition.

[0206] <Method for preparing test tire> According to the specifications of Table 3, the above-mentioned unvulcanized rubber composition for tread was formed into the shape of a tread, and the above-mentioned unvulcanized rubber composition for base tread was formed into the shape of a base tread, respectively, and laminated together with other tire components on a tire molding machine to form an unvulcanized tire, which was vulcanized at 170°C for 10 minutes to manufacture a test tire (size 205 / 70R15, passenger car tire).

[0207] According to Table 3, test tires were obtained by changing the composition of the formulation and specification, and the results calculated based on the following evaluation method are shown in each table. It should be noted that the benchmark comparison examples are as follows. Table 3: Comparative Example 1 (durability), Example 1 (sustainability of wet grip performance after time)

[0208] <Durability> The above-mentioned test tire rim was assembled on a rim (17×7.00JJ), filled with an internal pressure of 300kPa, and carried out using a drum tester in a step speed method according to the load / speed performance test specified in ECE30. During the test, the running speed was gradually increased, and the speed and time when the tire was broken were measured. The results are indicated by an index with Comparative Example 1 being 100. A larger index indicates better durability (high-speed durability).

[0209] <Sustainability of wet grip performance over time> (new product) Each test tire was mounted on a domestically produced 2000cc FF vehicle and the vehicle was driven on a wet road surface at 25°C. The brakes were applied at a speed of 150 km / h and the stopping distance (initial) required to stop was measured. (Wet grip performance after time) After the actual vehicle had traveled 20,000 km, the stopping distance (after time) required to stop was measured using the same method. Based on the stopping distances of each test tire when new and after aging, the maintenance rate (%) of the wet grip performance was calculated. The results were expressed as an index with the maintenance rate of Example 1 being 100. A larger index indicates more excellent sustainability of the wet-grip performance.

[0210] [Table 1]

[0211] [Table 2] Tread base

[0212] [Table 3]

[0213] The present invention <1> A tire having a cap tread and a base tread, characterized in that: The cap tread contains a polymer having ethylene units, an isoprene-based rubber, and a compound represented by the following formula (1), wherein the content of the isoprene-based rubber in 100% by mass of the rubber component is 20% by mass or more, The content of the isoprene-based rubber in 100% by mass of the rubber component of the base tread is larger than the content of the isoprene-based rubber in 100% by mass of the rubber component of the cap tread. (1)R 1 R 2 N-(C=S)-Sz(C=S)-NR 3 R 4 (wherein z represents an integer of 1 to 8. 1 ~R 4 are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms.

[0214] The present invention <2> According to the present invention <1> The tire described above, wherein the content of the compound represented by formula (1) is 0.1 parts by mass or more and 2.0 parts by mass or less relative to 100 parts by mass of the rubber component.

[0215] The present invention <3> According to the present invention <1> or <2> The tire, wherein the tread running surface, The content of the polymer having ethylene units in 100% by mass of the rubber component is 50% by mass or more, The content of the resin is 20 parts by mass or more relative to 100 parts by mass of the rubber component.

[0216] The present invention <4> According to the present invention <3> In the tire, the resin includes a hydrogenated resin.

[0217] The present invention <5> The present invention <1> ~ <4> The tire according to any combination of any one of the above, wherein the content of the filler in the cap tread is 80 parts by mass or more per 100 parts by mass of the rubber component.

[0218] The present invention <6> The present invention <1> ~ <5> A tire according to any combination of any one of the above, wherein: The ratio (Ib / Ic) of the isoprene rubber content Ib in 100 mass % of the rubber component of the base tread to the isoprene rubber content Ic in 100 mass % of the rubber component of the cap tread is 2.3 or more.

[0219] The present invention <7> The present invention <1> ~ <6> A tire according to any combination of any one of the above, wherein: The ratio (Rc / Ob) of the content Rc (parts by mass) of the resin in the cap tread relative to 100 parts by mass of the rubber component to the content Ob (parts by mass) of the oil in the base tread relative to 100 parts by mass of the rubber component is 2.0 or more and 10.0 or less.

[0220] The present invention <8> The present invention <1> ~ <7> A tire according to any combination of any one of the above, wherein: The ratio (Fc / Fb) of the filler content Fc in the cap tread relative to 100 parts by mass of the rubber component to the filler content Fb in the base tread relative to 100 parts by mass of the rubber component is 2.2 or more.

[0221] The present invention <9> The present invention <1> ~ <8> A tire according to any combination of any one of the above, wherein: The ratio (Cc / Cb) of the carbon black content Cc in the cap tread relative to 100 parts by mass of the rubber component to the carbon black content Cb in the base tread relative to 100 parts by mass of the rubber component is 0.15 or more.

[0222] The present invention <10> The present invention <1> ~ <9> A tire according to any combination of any one of the above, wherein: The ratio (Tc / Tb) of the thickness Tc (mm) of the cap tread to the thickness Tb (mm) of the base tread is 2.1 or more and 9.2 or less.

[0223] The present invention <11> The present invention <1> ~ <10> A tire according to any combination of any one of the above, wherein: The ratio (Dc / Tc) of the content Dc (parts by mass) of the compound represented by the formula (1) per 100 parts by mass of the rubber component in the cap tread to the thickness Tc (mm) of the cap tread is 0.02 or more.

Claims

1. A tire comprising a cap tread and a base tread, characterized in that: The cap tread contains a polymer having ethylene units, an isoprene-based rubber, and a compound represented by the following formula (1), wherein the content of the isoprene-based rubber in 100% by mass of the rubber component is 20% by mass or more, The content of the isoprene-based rubber in 100% by mass of the rubber component of the base tread is greater than the content of the isoprene-based rubber in 100% by mass of the rubber component of the cap tread. (1)R 1 R 2 N-(C=S)-Sz(C=S)-NR 3 R 4 , In the formula, z represents an integer from 1 to 8; R 1 ~R 4 The same or different radicals represent a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms.

2. The tire according to claim 1, wherein: The content of the compound represented by formula (1) is 0.1 parts by mass or more and 2.0 parts by mass or less relative to 100 parts by mass of the rubber component.

3. The tire according to claim 1, wherein: In the running surface of the tread, The content of the polymer having ethylene units in 100% by mass of the rubber component is 50% by mass or more, The content of the resin is 20 parts by mass or more relative to 100 parts by mass of the rubber component.

4. The tire according to claim 3, wherein: The resin includes a hydrogenated resin.

5. The tire according to claim 1, wherein: In the cap tread, the content of the filler is 80 parts by mass or more relative to 100 parts by mass of the rubber component.

6. The tire according to claim 1, wherein: The ratio Ib / Ic of the isoprene rubber content Ib in 100 mass % of the rubber component of the base tread to the isoprene rubber content Ic in 100 mass % of the rubber component of the cap tread is 2.3 or more.

7. The tire according to claim 1, wherein: The ratio Rc / Ob of the content Rc of the resin per 100 parts by mass of the rubber component in the cap tread to the content Ob of the oil per 100 parts by mass of the rubber component in the base tread is 2.0 or more and 10.0 or less, where the unit of Rc is part by mass and the unit of Ob is part by mass.

8. The tire according to claim 1, wherein: The ratio Fc / Fb of the filler content Fc in the cap tread relative to 100 parts by mass of the rubber component to the filler content Fb in the base tread relative to 100 parts by mass of the rubber component is 2.2 or more.

9. The tire according to claim 1, wherein: The ratio Cc / Cb of the carbon black content Cc in the cap tread relative to 100 parts by mass of the rubber component to the carbon black content Cb in the base tread relative to 100 parts by mass of the rubber component is 0.15 or more.

10. The tire according to claim 1, wherein: A ratio Tc / Tb of a thickness Tc of the cap tread to a thickness Tb of the base tread is 2.1 or more and 9.2 or less, where the unit of Tc is mm and the unit of Tb is mm.

11. The tire according to claim 1, wherein: The ratio Dc / Tc of the content Dc of the compound represented by formula (1) per 100 parts by mass of the rubber component in the cap tread to the thickness Tc of the cap tread is 0.02 or more, where Dc is expressed in parts by mass and Tc is expressed in mm.

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