tire

Abstract

This tire offers excellent overall performance, including fuel efficiency during city driving and lane change performance during high-speed driving. [Solution] The present invention relates to a tire having a tread, wherein the tread is composed of a tire rubber composition containing a rubber component including styrene-butadiene rubber and an ionic coupling agent, and has a first land portion closest to the equator and a second land portion located outside the first land portion on the vehicle side of the tire's equator, and satisfies the following (1) to (3). (1) The amount of styrene in the styrene-butadiene rubber is 20% by mass or less. (2) When the width of the first land area is W1 and the width of the second land area is W2, W1 / W2 > 0.3 (3) Total amount of styrene in the rubber component / (W1 - W2 × 0.3) ≤ 1.5

Description

[Technical Field]

[0001] This invention relates to tires. [Background technology]

[0002] Tires used in automobiles are required to have low fuel consumption and handling stability, and various rubber compositions have been proposed, but further improvements are desired (Patent Documents 1 and 2, etc.). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2000-344955 [Patent Document 2] Japanese Patent Publication No. 2007-186567 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] This invention has been made in view of the above-mentioned circumstances, and aims to provide a tire that excels in overall performance, including low fuel consumption during city driving and lane change performance during high-speed driving. [Means for solving the problem]

[0005] The present invention relates to a tire having a tread, wherein the tread is composed of a tire rubber composition containing a rubber component including styrene-butadiene rubber and an ionic coupling agent, and has a first land portion closest to the equator and a second land portion located outside the first land portion on the vehicle side of the tire's equator, and satisfies the following (1) to (3). (1) The amount of styrene in the styrene-butadiene rubber is 20% by mass or less. (2) When the width of the first land area is W1 and the width of the second land area is W2, W1 / W2 > 0.3 (3) Total amount of styrene in the rubber component / (W1 - W2 × 0.3) ≤ 1.5 [Effects of the Invention]

[0006] The present invention provides a tire having a tread, wherein the tread is composed of a rubber composition for tires containing a rubber component including styrene-butadiene rubber and an ionic coupling agent, and has a first land portion closest to the equator and a second land portion located outside the first land portion on the vehicle side of the tire's equator, and satisfies the above (1) to (3), thus providing a tire with excellent overall performance in low fuel consumption during city driving and lane change performance during high-speed driving. [Brief explanation of the drawing]

[0007] [Figure 1] This is an exploded view of the tread portion of one embodiment of the present invention. [Modes for carrying out the invention]

[0008] The above-mentioned tire is a tire having a tread, the tread being composed of a tire rubber composition containing a rubber component including styrene-butadiene rubber and an ionic coupling agent, and having a first land portion closest to the equator and a second land portion located outside the first land portion on the vehicle side of the tire's equator, thus satisfying the above conditions (1) to (3).

[0009] The mechanism by which the aforementioned effects are obtained is not clear, but it is presumed to be as follows. In a tire having a tread made of a tire rubber composition containing an ionic coupling agent, setting W1 and W2 to the above relationship increases the rigidity of the tread, and in particular suppresses deformation of the rubber blocks during cornering. Furthermore, reducing the amount of styrene in the styrene-butadiene rubber component reduces energy loss caused by the movement of polymer chains. These effects reduce energy loss during driving that involves repeated turns, such as in urban areas, and also improve responsiveness by allowing the tread to make better contact with the road surface even at high speeds. Based on the above, it is presumed that the overall performance, including fuel efficiency during city driving and lane change performance during high-speed driving, will be significantly improved. The above-mentioned tires offer excellent fuel efficiency during city driving, making them particularly effective for situations where vehicles frequently travel in urban areas and make many turns, such as taxis and route buses.

[0010] In this specification, "rubber component" refers to a component that contributes to crosslinking, and is a solid rubber under the conditions of 1 atmosphere and 25°C. In other words, a liquid rubber under the conditions of 1 atmosphere and 25°C is not considered a "rubber component." Here, the rubber component is preferably a polymer with a weight-average molecular weight (Mw) of 100,000 or more.

[0011] The weight-average molecular weight of the rubber component is preferably 100,000 or more, more preferably 150,000 or more, even more preferably 200,000 or more, particularly preferably 270,000 or more, and also preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less. Within this range, a better effect tends to be obtained.

[0012] In this specification, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) can be determined by converting the measured values ​​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) to standard polystyrene equivalents.

[0013] The total styrene content in the rubber component is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, even more preferably 2.5% by mass or more, and also preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. Within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of improving dry grip performance, the amount is preferably 2.5% by mass or more, more preferably 3% by mass or more, and even more preferably 10% by mass or more. Furthermore, from the viewpoint of improving processability, the amount is preferably 10% by mass or less, more preferably 3% by mass or less, and even more preferably 2.5% by mass or less.

[0014] Here, the total amount of styrene in the rubber component is the total amount of styrene contained in the entire rubber component (unit: mass%), and can be calculated using the formula Σ(content of each rubber component × amount of styrene in each rubber component / 100). For example, if 100% by mass of rubber component consists of 85% by mass of styrene-butadiene rubber with a styrene content of 40% by mass, 5% by mass of styrene-butadiene rubber with a styrene content of 25% by mass, and 10% by mass of butadiene rubber with a styrene content of 0% by mass, then the total amount of styrene in the rubber component is 35.25% by mass (= 85 × 40 / 100 + 5 × 25 / 100 + 10 × 0 / 100).

[0015] In this specification, the amount of styrene in each rubber component is determined by pyrolysis gas chromatography or NMR measurement. 1 H-NMR and 13 It is calculated by 13C-NMR. The same applies to the styrene content and vinyl content of SBR described later. The amounts of these components are calculated using the complex modulus (E). * Unlike physical properties such as those mentioned above, there exists a true value that is independent of the measurement method, so it is preferable to use a measurement method that is as high-precision as possible. Furthermore, while the total amount of styrene in the rubber component is calculated in accordance with the formulas described herein in the examples, it may also be analyzed from the tire using, for example, Py-GC / MS.

[0016] The above rubber components include styrene-butadiene rubber (SBR). The above-mentioned 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 may be used individually or in combination of two or more types.

[0017] The glass transition temperature (Tg) of the above-mentioned SBR is preferably -40°C or lower, more preferably -60°C or lower, and even more preferably -70°C or lower. The lower limit of the Tg of SBR is not particularly limited, but it may be -100°C or higher. When it is within the above range, the effect tends to be better obtained.

[0018] In this specification, the glass transition temperature is the value measured by differential scanning calorimetry (DSC) at a heating rate of 10°C / min in accordance with JIS K7121. Furthermore, when multiple SBRs are used, the weight average value obtained from the individual glass transition temperatures and their respective mixing ratios is treated as the glass transition temperature of the SBR. For example, if 40% by mass of SBR with a Tg of -80°C is included in 100 parts by mass of the rubber component, and 40% by mass of SBR with a Tg of -40°C is included in 100 parts by mass of the rubber component, the glass transition temperature of the SBR in the rubber composition will be -60°C (=(-80×40-40×40) / (40+40)).

[0019] In the above rubber composition, the amount of styrene in SBR is 20% by mass or less. The styrene content of SBR is preferably 15% by mass or less, more preferably 10% by mass or less, and also preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. Within the above range, a better effect tends to be obtained. From the viewpoint of fuel efficiency, the amount is preferably 5% by mass or more, and more preferably 20% by mass or more. Furthermore, from the viewpoint of handling stability during high-speed driving, the amount is preferably 20% by mass or less, and more preferably 5% by mass or less.

[0020] The styrene content of SBR refers to the styrene content of a single type of SBR if it is one type, and to the average styrene content if it is one of multiple types. The average styrene content of SBR can be calculated using the formula {Σ(content of each SBR × styrene content of each SBR)} / total content of all SBR. For example, if 85% of the rubber component is SBR with 40% styrene content and 5% is SBR with 25% styrene content, the average styrene content of the SBR is 39.2% (=(85 × 40 + 5 × 25) / (85 + 5)).

[0021] The vinyl content of SBR is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and also preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. When the content is within the above range, a better effect tends to be obtained. From the viewpoint of fuel efficiency, the amount is preferably 11% by mass or more, and more preferably 20% by mass or more. Furthermore, from the viewpoint of handling stability during high-speed driving, the amount is preferably 20% by mass or less, and more preferably 11% by mass or less.

[0022] The vinyl content of SBR (amount of 1,2-bonded butadiene units) is the ratio of vinyl bonds to the total mass of the butadiene portion in the SBR, with the total mass being 100 (unit: mass%). The formula is: vinyl content [mass%] + cis content [mass%] + trans content [mass%] = 100 [mass%]. If there is only one type of SBR, it refers to the vinyl content of that SBR; if there are multiple types, it refers to the average vinyl content. The average vinyl content of SBR can be calculated using the formula: Σ{Content of each SBR × (100 [mass%] - Styrene content of each SBR [mass%]) × Vinyl content of each SBR [mass%]} / Σ{Content of each SBR × (100 [mass%] - Styrene content of each SBR [mass%])}. For example, if 100 parts by mass of rubber component, 75 parts by mass of SBR contain 40% by mass of styrene and 30% by mass of vinyl, and 25% by mass of vinyl, If 15 parts by mass of SBR have a 20% vinyl content and the remaining 10 parts by mass are other than SBR, the average vinyl content of the SBR is 28% by 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%])}.

[0023] As mentioned above, hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used as SBR.

[0024] For example, SBR manufactured and sold by companies such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Co., Ltd. can be used as the above-mentioned SBR. Alternatively, SBR synthesized by known methods can also be used.

[0025] The above rubber components may include isoprene-based rubber. Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. For NR, common types used in the rubber industry, such as SIR20, RSS#3, and TSR20, can be used. For IR, there are no particular limitations; common types used in the rubber industry, such as IR2200, can be used. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber. Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used individually or in combination of two or more types.

[0026] The above rubber component may include butadiene rubber (BR). The above-mentioned BR is not particularly limited, and for example, high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using a rare-earth catalyst (rare-earth BR) can be used. These may be used individually or in combination of two or more. In particular, it is preferable that the BR contains high-cis BR with a cis content of 90% by mass or more. A cis content of 95% by mass or more is more preferable. The cis content can be measured by infrared absorption spectroscopy.

[0027] The cis amount of the above BR refers to the cis amount of that BR if there is only one type of BR, and the average cis amount if there are multiple types. The average cis content of BR can be calculated as {Σ(content of each BR × cis content of each BR)} / total BR content. For example, if 20% of BR has a cis content of 90% and 10% has a cis content of 40% out of 100% of rubber components, the average cis content of BR is 73.3% (=(20 × 90 + 10 × 40) / (20 + 10)).

[0028] Hydrogenated butadiene polymer (hydrogenated BR) can also be used as the above-mentioned BR.

[0029] For example, products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used as BRs.

[0030] The raw materials (monomers) for synthetic rubbers such as IR, SBR, and BR may be derived from underground resources such as petroleum and natural gas, or they may be recycled from rubber products such as tires or non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, but examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl include styrene, but are not particularly limited. In particular, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0031] The method for producing recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Furthermore, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and pressure, decomposed by microwaves, or extracted after mechanical grinding.

[0032] Furthermore, the raw materials (monomers) of synthetic rubbers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural, forestry, and fishery products, sugars, wood chips, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha.

[0033] The biomass-derived monomer (biomass monomer) is not particularly limited and includes biomass-derived butadiene and biomass-derived aromatic vinyl. The butadiene is 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited but includes styrene. Furthermore, the method for producing the biomass monomer is not particularly limited and includes, for example, biological and / or chemical and / or physical transformations of plants and animals. A typical biological transformation is fermentation by microorganisms, while chemical and / or physical transformations include those by catalysts, high heat, high pressure, electromagnetic waves, critical liquids, and combinations thereof.

[0034] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0035] Whether the raw materials for a polymer are biomass-derived can be determined by measuring pMC (percent Modern Carbon) in accordance with ASTMD6866-10.

[0036] pMC stands for Modern Standard Reference Carbon. 14 Sample relative to C concentration14 It is the ratio of C concentration and is a value used as an index indicating the biomass ratio of a compound. The significance of this value is described below.

[0037] In one mole (6.02×10 23 atoms) of carbon atoms, there are approximately 6.02×10 11 atoms, which is about one trillionth of ordinary carbon atoms. 14 of 14 C exists. 14 C is called a radioactive isotope, and its half-life is 5730 years and it decreases regularly. It takes 226,000 years for all of these to decay. Therefore, after carbon dioxide in the atmosphere and the like are taken up and fixed by plants and the like, in fossil fuels such as coal, oil, and natural gas for which it is considered that more than 226,000 years have passed, all of the 14 C element has decayed. Therefore, at present in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain 14 the C element at all. Therefore, chemical substances produced from these fossil fuels also do not contain

[0038] On the other hand, 14 C is constantly generated by nuclear reactions of cosmic rays in the atmosphere, and there is a balance between the decrease due to radioactive decay. In the earth's atmospheric environment, 14 the amount of 14 C is constant. Therefore, the -12 C concentration of substances derived from biomass resources that are circulating in the current environment is about 1×10

[0039] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 the 13 C concentration ( 12 C / 14 C), 14 the 12 C concentration (14 As a modern standard reference for the concentration of C, the amount of cyclic carbon in nature as of 1950 14 The C concentration will be used. The specific standard material will be the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific radioactivity of carbon in this oxalic acid (per gram of carbon) will be used. 14 The radioactivity intensity of C is separated by carbon isotope, 13 The standard value is obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date. 14 This value is used as the C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0040] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal conditions it will often not reach 100, and will show a value of approximately 110 pMC. On the other hand, regarding chemical substances derived from fossil fuels such as petroleum, 14 When the C concentration is measured, it will show a value of approximately 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% as mentioned above.

[0041] Based on the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in rubber compositions is preferable from an environmental protection standpoint.

[0042] The SBR content in 100% by mass of the rubber component is preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and also preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. When the content is within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of improving grip performance, it is preferably 50% by mass or more, more preferably 60% by mass or more. Furthermore, from the viewpoint of improving wear resistance, it is preferably 60% by mass or less, more preferably 50% by mass or less.

[0043] When the above rubber component includes isoprene-based rubber, the isoprene-based rubber content in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and also preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. Within the above range, a better effect tends to be obtained. From the viewpoint of fuel efficiency, the amount is preferably 30% by mass or more, and more preferably 40% by mass or more. Furthermore, from the viewpoint of handling stability during high-speed driving, the amount is preferably 40% by mass or less, and more preferably 30% by mass or less.

[0044] When the above rubber component contains BR, the BR content in 100% by mass of the rubber component is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and also preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. When it is within the above range, the effect tends to be better obtained. From the viewpoint of handling stability during high-speed driving, the amount is preferably 10% by mass or more, more preferably 20% by mass or more. From the viewpoint of low fuel consumption, the amount is preferably 20% by mass or less, more preferably 10% by mass or less.

[0045] The above tire rubber composition may contain other rubber components in addition to isoprene-based rubber, BR, and SBR. Other usable rubber components include, for example, diene-based rubbers other than those mentioned above. Examples of diene-based rubbers other than isoprene-based rubber, BR, and SBR include styrene-isoprene butadiene rubber (SIBR), ethylene-propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Other rubber components include butyl-based rubber and fluororubber. The rubber components may be used individually or in combination of two or more. Furthermore, these rubber components may be subjected to modification treatment or hydrogenation treatment, and stretched rubber, which has been stretched with oil, resin, liquid rubber components, etc., may also be used.

[0046] The above rubber composition preferably contains a filler. The filler is not particularly limited, and materials known in the rubber field can be used. Examples include inorganic fillers such as silica, carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica, as well as water-soluble fillers, biochar, and poorly dispersible fillers. These may be used individually or in combination of two or more. Among these, silica and water-soluble fillers are preferred.

[0047] In the above-mentioned tire rubber composition, the silica that can be used is not particularly limited, and common silica used in the tire industry can be used, such as silica prepared by a dry process (anhydrous silica) or silica prepared by a wet process (hydrated silica). The raw material for silica is not particularly limited, and may be a mineral-derived raw material such as quartz, or a biological-derived raw material such as rice husks (for example, silica made from biomass materials such as rice husks), or silica recycled from products containing silica may be used. Among these, hydrated silica prepared by a wet process is preferred because it has a high silanol group content. These silicas may be used individually or in combination of two or more types.

[0048] Silica derived from biomass materials can be obtained, for example, by extracting silicates from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then using these silicates to react with sulfuric acid in the same way as conventional wet silica, the precipitate of silicon dioxide is filtered, washed with water, dried, and pulverized.

[0049] The silica recycled from silica-containing products can be, for example, silica recovered from products containing silica such as semiconductors and other electronic components, tires, desiccants, and diatomaceous earth and other filter materials. The recovery method is not particularly limited and can include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from semiconductors and other electronic components or tires is preferred.

[0050] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol.6, pp.216-222, etc.).

[0051] Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0052] The CTAB specific surface area of ​​silica (cetyltrimethylammonium bromide adsorption specific surface area, CTAB) is preferably 100 m². 2 / g or more, more preferably 160m 2 / g or more, more preferably 200m 2 / g or more, more preferably 230m 2 It is 1 / g or more. Furthermore, the upper limit of the CTAB of silica is not particularly limited, but preferably 350m 2 / g or less, more preferably 300m 2 / g or less, more preferably 260m 2 It is less than or equal to / g. Within the above range, there is a tendency for better results to be obtained. In this specification, the CTAB specific surface area of ​​silica is the value measured in accordance with JIS K6217-3.

[0053] It is presumed that when the above rubber composition contains silica, it tends to improve overall performance, including fuel efficiency during city driving and lane change performance during high-speed driving.

[0054] The average particle size of silica is preferably 24 nm or less, more preferably 22 nm or less, even more preferably 20 nm or less, and even more preferably 17 nm or less, and also preferably 6 nm or more, more preferably 9 nm or more, and even more preferably 12 nm or more. Within the above range, a better effect tends to be obtained.

[0055] In this specification, the method for measuring the average particle size of silica is transmission electron microscopy (TEM) observation. Specifically, silica particles are photographed with a transmission electron microscope, and if the particle shape is spherical, the diameter of the sphere is defined as the particle size; if it is needle-shaped or rod-shaped, the shorter axis is defined as the particle size; if it is irregularly shaped, the average particle size from the center is defined as the particle size; and the average particle size of 100 fine particles is defined as the average particle size.

[0056] The carbon blacks mentioned above are not particularly limited and include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw materials for carbon black may be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by thermal decomposition of waste tires. The manufacturing method for carbon black may be combustion such as the furnace method, hydrothermal carbonization (HTC), or thermal decomposition of methane such as the thermal black method. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbia Carbon Corporation, etc. Carbon black may be used alone or in combination of two or more types.

[0057] The specific surface area of ​​carbon black (CTAB) is 50 m². 2 Preferably 80m / g or more.2 More preferably 110m / g or more, 2 A value of 1 / g or more is even more preferable. Furthermore, the above CTAB is 200m 2 Preferably less than / g, 180m 2 More preferably less than / g, 160m 2 A value of less than / g is even more preferable. Within the above range, there is a tendency to obtain better effects. The CTAB specific surface area of ​​carbon black is a value measured in accordance with JIS K6217-3.

[0058] The median particle size (median diameter, D50) of the water-soluble filler is preferably 0.4 μm or larger, more preferably 0.6 μm or larger, and even more preferably 1.0 μm or larger. The upper limit is preferably 200 μm or smaller, more preferably 150 μm or smaller, even more preferably 50 μm or smaller, and particularly preferably 20 μm or smaller. Within the above range, better effects tend to be obtained. In this specification, the median particle size of a water-soluble filler can be measured by laser diffraction, and refers to the particle size of the 50% integrated value in the mass-based particle size distribution curve obtained by laser diffraction scattering. The median particle size of water-soluble fillers is measured by the following method. [Measurement of median particle size (median diameter) of water-soluble fillers] The measurement will be performed using the SALD-2000J model manufactured by Shimadzu Corporation, employing the laser diffraction method. The operating procedure is as follows: <Measurement Procedure> A water-soluble filler is dispersed at room temperature in a mixed solution of a dispersion solvent (toluene) and a dispersant (10% by mass of di-2-ethylhexyl sodium sulfosuccinate / toluene solution). The resulting dispersion is stirred for 5 minutes while being irradiated with ultrasound to obtain a test solution. The test solution is transferred to a batch cell and measured after 1 minute. (Refractive index: 1.70-0.20i)

[0059] Examples of water-soluble fillers include water-soluble inorganic salts and water-soluble organic substances. These may be used individually or in combination of two or more.

[0060] Examples of water-soluble inorganic salts include metal sulfates such as magnesium sulfate, sodium sulfate, and potassium sulfate; metal chlorides such as potassium chloride, sodium chloride, calcium chloride, and magnesium chloride; metal hydroxides such as potassium hydroxide and sodium hydroxide; carbonates such as potassium carbonate, sodium carbonate, and calcium bicarbonate; and phosphates such as sodium hydrogen phosphate and sodium dihydrogen phosphate.

[0061] Examples of water-soluble organic substances include lignin derivatives and sugars. Suitable lignin derivatives include lignin sulfonic acid and lignin sulfonate salts. The lignin derivative may be obtained by either the sulfite pulp method or the kraft pulp method.

[0062] Examples of ligninsulfonates include alkali metal salts, alkaline earth metal salts, ammonium salts, and alcoholamine salts of ligninsulfonic acid. Among these, alkali metal salts (potassium salts, sodium salts, etc.) and alkaline earth metal salts (calcium salts, magnesium salts, lithium salts, barium salts, etc.) of ligninsulfonic acid are preferred.

[0063] The lignin derivative preferably has a sulfonation degree of 1.5 to 8.0 / OCH3. In this case, the lignin derivative includes ligninsulfonic acid and / or ligninsulfonate salts in which at least a portion of lignin and / or its decomposition products are substituted with sulfon groups (sulfonated groups), and the sulfon groups of the ligninsulfonic acid may be in an unionized state, or the hydrogen of the sulfon group may be substituted with an ion such as a metal ion. The sulfonation degree is more preferably 3.0 to 6.0 / OCH3. The effect tends to be more favorably obtained by keeping it within the above range.

[0064] The degree of sulfonation of lignin derivative particles (the lignin derivatives that constitute the particles) is the rate of introduction of sulfo groups and can be calculated using the following formula. Sulfonation degree ( / OCH3) = S (moles) in the sulfone group in the lignin derivative / methoxyl group (moles) in the lignin derivative

[0065] Sugars have no particular restrictions on the number of carbon atoms they consist of and can be monosaccharides, oligosaccharides, or polysaccharides. Examples of monosaccharides include trisaccharides such as aldotrioose and ketotriose; tetrasaccharides such as erythrose and threose; pentoses such as xylose and ribose; hexoses such as mannose, allose, altrose, and glucose; and heptasaccharides such as sedoheptulose. Examples of oligosaccharides include disaccharides such as sucrose and lactose; trisaccharides such as raffinose and melegitose; tetrasaccharides such as acarbose and stachyose; and oligosaccharides such as xylooligosaccharides and cellooligosaccharides. Examples of polysaccharides include glycogen, starch (amylose, amylopectin), cellulose, hemicellulose, dextrin, and glucan.

[0066] Among water-soluble fillers, water-soluble inorganic salts are preferred, metal sulfates are more preferred, and magnesium sulfate is even more preferred. Among magnesium sulfates, anhydrous magnesium sulfate, magnesium sulfate dihydrate, and magnesium sulfate trihydrate are preferred, and anhydrous magnesium sulfate is more preferred.

[0067] It is presumed that when the above rubber composition contains a water-soluble filler, the overall performance, including fuel efficiency during city driving and lane change performance during high-speed driving, tends to improve.

[0068] Examples of the poorly dispersible fillers mentioned above include short fibers and gel-like compounds. Among these, short fibers are preferred.

[0069] Examples of short fibers that can be used include organic short fibers and inorganic short fibers. Specific examples of organic short fibers include nanocellulose such as cellulose nanofibers (CNF) and cellulose nanocrystals (CNC); biomass nanomaterials such as chitin nanofibers and chitosan nanofibers; and specific examples of inorganic short fibers include metal fibers and glass fiber systems. Commercially available products include those from Nippon Paper Industries Co., Ltd. and Sugino Machine Co., Ltd. These may be used individually or in mixtures of two or more. Among these, organic short fibers are preferred, and nanocellulose is more preferred.

[0070] The particle size of the nanocellulose is preferably 10 nm or larger, more preferably 20 nm or larger, even more preferably 25 nm or larger, and particularly preferably 28 nm or larger. It is also preferably 50 nm or smaller, more preferably 40 nm or smaller, even more preferably 35 nm or smaller, and particularly preferably 32 nm or smaller. When the particle size is within the above range, a better effect tends to be obtained.

[0071] The particle size of nanocellulose is the average fiber diameter measured by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray scattering data analysis, and pore electrical resistance method (Culter principle method). In this specification, the average fiber diameter of nanocellulose (cellulose fiber) is typically the average fiber diameter of an aggregate of cellulose fibers formed by the aggregation of cellulose molecules.

[0072] In the above-mentioned rubber composition for tires, the content of fillers (total amount of fillers such as silica and carbon black) is preferably 80 parts by mass or more, more preferably 100 parts by mass or more, even more preferably 120 parts by mass or more, and even more preferably 140 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 200 parts by mass or less, more preferably 180 parts by mass or less, and even more preferably 160 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of improving wear resistance, the amount is preferably 85 parts by mass or more, more preferably 95 parts by mass or more, even more preferably 125 parts by mass or more, even more preferably 130 parts by mass or more, and even more preferably 145 parts by mass or more. Furthermore, from the viewpoint of improving processability, the amount is preferably 145 parts by mass or less, more preferably 130 parts by mass or less, even more preferably 125 parts by mass or less, even more preferably 95 parts by mass or less, and even more preferably 85 parts by mass or less.

[0073] In the above-mentioned rubber composition for tires, the silica content is preferably 80 parts by mass or more, more preferably 110 parts by mass or more, even more preferably 130 parts by mass or more, and also preferably 180 parts by mass or less, more preferably 160 parts by mass or less, and even more preferably 140 parts by mass or less. When the silica content is within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of improving wet grip performance, the amount is preferably 80 parts by mass or more, more preferably 110 parts by mass or more, even more preferably 120 parts by mass or more, and even more preferably 130 parts by mass or more. Furthermore, from the viewpoint of improving processability, the amount is preferably 130 parts by mass or less, more preferably 120 parts by mass or less, even more preferably 110 parts by mass or less, and even more preferably 80 parts by mass or less.

[0074] When the above tire rubber composition contains carbon black, the carbon black content is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and also preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, a better effect tends to be obtained.

[0075] When the above tire rubber composition contains a water-soluble filler, the content of the water-soluble filler is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and also preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of improving wear resistance, the amount is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0076] When the above tire rubber composition contains a poorly dispersible filler, the content of the poorly dispersible filler is preferably 1 part by mass or more, more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0077] The above-mentioned rubber composition for tires contains an ionic coupling agent. Any material that reacts with silica and is modified to form ionic bonds can be used as an ionic coupling agent. More specifically, any material having a site that can react with silica and a site that can form ionic bonds can be used as an ionic coupling agent, for example, a site that reacts with silanol groups on the silica surface, such as OCR. 1 (R 1 A compound having a moiety represented by (where represents a monovalent organic group) and an ionic functional group is preferred. The above ionic functional group is not particularly limited as long as it is a functional group containing anionic species or cationic species. For example, sulfate ester base (-OSO3 - X + ), sulfonic acid base (-SO3 - X + ), phosphate ester base (-OPO(O - X + )2) Phosphosphate base (-PO(O - X + )2) Carboxylic acid base (-COO - X + ), boronic acid base (-B(O - X + )2) anionic groups such as (X + represents a cation. ), quaternary ammonium group (-(NR 35 R 36 R 37 ) + Y -Cationic groups such as (Y) (wherein R35 to R37 will be described later.) - represents an anion. ) are examples. The above ionic coupling agent may have one of these ionic functional groups, or two or more. The above X + The cation represented by may be an organic ion or an inorganic ion, and is not particularly limited, but examples include metal ions such as lithium ions, sodium ions, and potassium ions, and ammonium groups. - The anion represented by may be an organic ion or an inorganic ion, and is not particularly limited, but examples include chloride ions, as described later.

[0078] In particular, the ionic coupling agent is preferably at least one selected from the group consisting of a compound represented by the following formula (1), a hydrolysate of the compound represented by the following formula (1), and a hydrolyzed condensate of the compound represented by the following formula (1).

[0079] [ka]

[0080] In formula (1), R 31 and R 32 Each of these independently represents a monovalent organic group. 33 and R 34 Each of these independently represents an organic group having a group selected from the group consisting of alkyl groups, vinyl groups, epoxy groups, styryl groups, (meth)acrylic groups, amino groups, isocyanurate groups, ureido groups, mercapto groups, sulfide groups, polyalkylene oxyalkyl groups, carboxyl groups, sulfate ester bases, sulfonic acid bases, phosphate ester bases, phosphonic acid bases, carboxylic acid bases, boronic acid salts, and quaternary ammonium groups, and the above R 34At least one of the groups is an organic group having a group selected from the group consisting of sulfate ester bases, sulfonic acid bases, phosphate ester bases, phosphonic acid bases, carboxylic acid bases, boronic acid bases, and quaternary ammonium groups. m independently represents an integer from 0 to 2. n represents an integer. In this specification, an organic group means a group having one or more carbon atoms.

[0081] The hydrolysate of the compound represented by formula (1) is a compound in which at least some of the substituents on the silicon atom of the compound represented by formula (1) have been hydrolyzed to form a silanol group. Furthermore, the hydrolysis condensate of the compound represented by formula (1) is a compound obtained by the condensation of two or more compounds selected from the group consisting of the compound represented by formula (1) and the hydrolysis product of the compound represented by formula (1).

[0082] In formula (1), m is preferably 1 or 2, and more preferably 2. In equation (1), n ​​is preferably an integer between 2 and 20.

[0083] R in equation (1) 31 and R 32 The monovalent organic group preferably has 1 to 6 carbon atoms. R 31 and R 32 The C1-C6 organic group in the formula may be linear, branched, or have a cyclic structure. Examples of C1-C6 organic groups include alkyl groups and alkenyl groups, with alkyl groups being preferred. Examples of C1-C6 alkyl groups include methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, n-hexyl, and cyclohexyl groups.

[0084] R in equation (1) 31 and R 32Each of these groups is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, even more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

[0085] R in equation (1) 33 Each of these groups is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, even more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

[0086] R in equation (1) 34 Preferably, at least one of the organic groups has a quaternary ammonium group. Examples of groups having a quaternary ammonium group include the group represented by the following formula. [ka]

[0087] In the formula, R 35 ~R 37 Each of these independently represents a monovalent organic group. 38 Each of these independently represents a divalent organic group. - k represents an anion. k represents an integer.

[0088] R 35 ~R 37 Examples of monovalent organic groups include monovalent hydrocarbon groups, such as alkyl groups having 1 to 18 carbon atoms and alkenyl groups having 2 to 12 carbon atoms. R 35 ~R 37 The number of carbon atoms is preferably 1 to 12, more preferably 1 to 7, even more preferably 1 to 5, and particularly preferably 1 to 3. R 35 ~R 37 The monovalent organic group is particularly preferably a methyl group or an ethyl group.

[0089] R 38Examples of the divalent organic group include divalent hydrocarbon groups, and examples of the divalent hydrocarbon groups include alkylene groups having 1 to 12 carbon atoms, alkenylene groups having 2 to 12 carbon atoms, and the like. R 38 The number of carbon atoms of 38 is preferably 1 to 12, more preferably 1 to 7, still more preferably 1 to 5, and particularly preferably 1 to 3. R 38 As the divalent organic group of 38 , a methylene group and an ethylene group are particularly preferable.

[0090] k is preferably 0 to 5, more preferably 0 to 3, still more preferably 0 to 1, and particularly preferably 0.

[0091] Y - is not particularly limited, and examples thereof include halide ions (chloride ions, bromide ions, iodide ions, etc.); carboxylic acid ions (formate ions, acetate ions, trifluoroacetate ions, lactate ions, propionate ions, benzoate ions, oxalate ions, succinate ions, stearate ions, etc.); methyl sulfate ions (alkyl sulfate ions, etc.); sulfonate ions (methanesulfonate ions, benzenesulfonate ions, trifluoromethanesulfonate ions, toluenesulfonate ions, naphthalenesulfonate ions, nitrobenzenesulfonate ions, dodecylbenzenesulfonate ions, ethanesulfonate ions, etc.); sulfonimide ions (bis(trifluoromethanesulfonate)imide ions, etc.); borate ions (tetrafluoroborate ions, tetraphenylborate ions, butyltriphenylborate ions, etc.); phosphate ions (hexafluorophosphate ions, etc.); antimonate ions (hexafluoroantimonate ions, etc.); arsenate ions (hexafluoroarsenate ions, etc.); perhalate ions (perchlorate ions, periodate ions, etc.); thiocyanate ions, nitrate ions, and the like.

[0092] Among the compounds represented by the above formula (1), the hydrolyzates of the compounds represented by the above formula (1), and the hydrolysis condensates of the compounds represented by the above formula (1), from the viewpoint of obtaining better effects, the compounds represented by the following formula (1-1) are desirable.

[0093]

Chem.

[0094] In formula (1-1), R 35 ~R 37 each independently represents the same group as the aforementioned R 35 ~R 37 . R 38 each independently represents the same group as the aforementioned R 38 . Y - each independently represents the same anion as the aforementioned Y - . k each independently represents the same integer as the aforementioned k.

[0095] In formula (1-1), the preferred examples of R 35 ~R 37 , R 38 , Y - , and k are also the same as those described above.

[0096] When the ionic coupling agent has a salt structure such as a quaternary ammonium salt, such as the compound represented by the formula (1-1), better effects can be obtained. The compound represented by the formula (1) preferably has a quaternary ammonium salt structure. The ionic coupling agent is more preferably a quaternary ammonium salt.

[0097] For the above ionic coupling agent, commercially available products such as X-12-1126 and KBM-9418-40 manufactured by Shin-Etsu Chemical Co., Ltd. can be used.

[0098] In the above rubber composition for tires, the total content of the above ionic coupling agent is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 7 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, there is a tendency to obtain better effects. On the other hand, from the viewpoint of improving wet grip performance, the amount is preferably 6 parts by mass or more, more preferably 7 parts by mass or more. Furthermore, from the viewpoint of improving processability, the amount is preferably 7 parts by mass or less, more preferably 6 parts by mass or less.

[0099] If the above tire rubber composition contains silica, it is preferable that it further contains a silane coupling agent. The silane coupling agent is not particularly limited and any known in the rubber field can be used, for example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl) trisulfide, bis(4-trimethoxysilylbutyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, Examples include sulfide compounds such as N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z from Momentive; vinyl compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, mercapto compounds are preferred. Commercially available products from companies such as Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Toray Dow Corning Co., Ltd. can be used. These can be used individually or in combination of two or more types.

[0100] When the above rubber composition contains a mercapto-silane coupling agent, it is presumed that the overall performance, including fuel efficiency during city driving and lane change performance during high-speed driving, tends to improve.

[0101] In addition to compounds containing a mercapto group, compounds in which the mercapto group is protected by a protecting group (for example, compounds represented by the following formula (S1)) can also be used as mercapto-silane coupling agents.

[0102] Particularly suitable mercapto-silane coupling agents include silane coupling agents represented by the following formula (S1), and silane coupling agents containing a bonding unit A shown in the following formula (I) and a bonding unit B shown in the following formula (II). [ka] (In the formula, R 1001 -Cl, -Br, -OR 1006 -O(O=)CR 1006 , -ON=CR 1006 R 1007 , -NR 1006 R 1007 and -(OSiR 1006 R 1007 ) h (OSiR 1006 R 1007 R 1008 A monovalent group (R) selected from ) 1006 , R 1007 and R 1008 They may be the same or different, and each is a hydrogen atom or a monovalent hydrocarbon group with 1 to 18 carbon atoms, and the average value of h is 1 to 4. 1002 is R 1001 , hydrogen atom or monovalent hydrocarbon group having 1 to 18 carbon atoms, R 1003 is -[O(R 1009 O) j ]-group(R 1009 is an alkylene group with 1 to 18 carbon atoms, and j is an integer from 1 to 4. ), R 1004 R is a divalent hydrocarbon group having 1 to 18 carbon atoms. 1005(where represents a monovalent hydrocarbon group with 1 to 18 carbon atoms, and x, y, and z are numbers that satisfy the relationships x + y + 2z = 3, 0 ≤ x ≤ 3, 0 ≤ y ≤ 2, and 0 ≤ z ≤ 1.) [ka] [ka] (In the formula, v is a non-negative integer and w is a non-negative integer. 11 R represents hydrogen, halogen, branched or unbranched C1-C30 alkyl group, branched or unbranched C2-C30 alkenyl group, branched or unbranched C2-C30 alkynyl group, or an alkyl group in which the terminal hydrogen is substituted with a hydroxyl group or a carboxyl group. 12 R represents a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, or a branched or unbranched alkynylene group having 2 to 30 carbon atoms. 11 and R 12 (They may form a ring structure.)

[0103] In equation (S1), R 1005 , R 1006 , R 1007 and R 1008 Each of these is preferably independently selected from the group consisting of linear, cyclic, or branched alkyl groups, alkenyl groups, aryl groups, and aralkyl groups having 1 to 18 carbon atoms. 1002 If is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is preferably a group selected from the group consisting of linear, cyclic, or branched alkyl groups, alkenyl groups, aryl groups, and aralkyl groups. 1009 The alkylene group is preferably linear, cyclic, or branched, and is particularly preferred to be linear. 1004Examples of these include alkylene groups having 1 to 18 carbon atoms, alkenylene groups having 2 to 18 carbon atoms, cycloalkylene groups having 5 to 18 carbon atoms, cycloalkylalkylene groups having 6 to 18 carbon atoms, arylene groups having 6 to 18 carbon atoms, and aralkylene groups having 7 to 18 carbon atoms. The alkylene groups and alkenylene groups may be linear or branched, and the cycloalkylene groups, cycloalkylalkylene groups, arylene groups, and aralkylene groups may have functional groups such as lower alkyl groups on their rings. 1004 Preferably, the alkylene group has 1 to 6 carbon atoms, and in particular, linear alkylene groups such as methylene, ethylene, trimethylene, tetramethylene, pentamethylene, and hexamethylene groups are preferred.

[0104] R in equation (S1) 1002 , R 1005 , R 1006 , R 1007 and R 1008 Specific examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, vinyl group, propenyl group, allyl group, hexenyl group, octenyl group, cyclopentenyl group, cyclohexenyl group, phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenethyl group, naphthylmethyl group, and the like. R in equation (S1) 1009 Examples of linear alkylene groups include methylene, ethylene, n-propylene, n-butylene, and hexylene groups, while examples of branched alkylene groups include isopropylene, isobutylene, and 2-methylpropylene groups.

[0105] Specific examples of silane coupling agents represented by formula (S1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, and 2-lauroylthioethyltrimethoxysilane. These may be used individually or in combination of two or more. Among them, 3-octanoylthiopropyltriethoxysilane is particularly preferred.

[0106] In a silane coupling agent containing a bonding unit A represented by formula (I) and a bonding unit B represented by formula (II), the content of bonding unit A is preferably 30 mol% or more, more preferably 50 mol% or more, preferably 99 mol% or less, and more preferably 90 mol% or less. The content of bonding unit B is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 55 mol% or less. The total content of bonding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%. The content of bonding units A and B includes the amount when bonding units A and B are located at the ends of the silane coupling agent. The form of bonding units A and B when they are located at the ends of the silane coupling agent is not particularly limited, as long as they form units corresponding to formulas (I) and (II) that represent bonding units A and B.

[0107] R in equations (I) and (II)11 Examples of halogens include chlorine, bromine, and fluorine. Examples of branched or unbranched alkyl groups with 1 to 30 carbon atoms include methyl and ethyl groups. Examples of branched or unbranched alkenyl groups with 2 to 30 carbon atoms include vinyl and 1-propenyl groups. Examples of branched or unbranched alkynyl groups with 2 to 30 carbon atoms include ethynyl and propynyl groups.

[0108] R in equations (I) and (II) 12 Regarding branched or unbranched alkylene groups with 1 to 30 carbon atoms, examples include ethylene and propylene groups. Regarding branched or unbranched alkenylene groups with 2 to 30 carbon atoms, examples include vinylene and 1-propenylene groups. Regarding branched or unbranched alkylene groups with 2 to 30 carbon atoms, examples include ethynylene and propynylene groups.

[0109] In a silane coupling agent containing a bonding unit A represented by formula (I) and a bonding unit B represented by formula (II), the sum of the number of repeats of bonding unit A (v) and the number of repeats of bonding unit B (w), (v+w), is preferably in the range of 3 to 300.

[0110] In the above-mentioned rubber composition for tires, the content of the silane coupling agent is preferably 1 part by mass or more, more preferably 4 parts by mass or more, and even more preferably 6 parts by mass or more, per 100 parts by mass of silica, and also preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0111] The above rubber composition preferably contains a plasticizer. In this specification, "plasticizer" refers to a material that imparts plasticity to rubber components, and is a concept that includes both liquid plasticizers under conditions of 1 atmosphere and 25°C, and solid plasticizers under conditions of 1 atmosphere and 25°C. Examples of plasticizers include resins, oils, liquid rubber, and ester-based plasticizers. Among these, resins, oils, and liquid rubber are preferred. These plasticizers may be derived from mineral resources such as petroleum and natural gas, from biomass, or from naphtha recycled from rubber or non-rubber products. Alternatively, low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may be used as plasticizers. These plasticizers may be used individually or in combination of two or more.

[0112] Although the mechanism by which the above rubber composition becomes more effective when it contains a plasticizer is not clear, it is presumed that this improves road surface tracking and enhances overall performance, including fuel efficiency during city driving and lane change performance during high-speed driving.

[0113] Resin is a material that imparts plasticity to rubber components, and the concept includes both liquid resins and solid resins under the same conditions of 1 atmosphere and 25°C. The resin may be used alone, or two or more types may be used in combination. In this specification, resin and rubber (rubber component or liquid rubber) are considered different materials.

[0114] The resin is not particularly limited, but resins commonly used in the tire industry can be used. Examples include adhesive resins such as C5 resins, C9 resins, C5C9 resins, aromatic vinyl resins, dicyclopentadiene resins, coumarone resins, indene resins, terpene resins, rosin resins, and phenolic resins. These resins may be used individually or in combination of two or more.

[0115] Among the above resins, at least one selected from the group consisting of dicyclopentadiene resins, aromatic vinyl resins, and terpene resins is preferred, from the viewpoint of obtaining better effects.

[0116] It is presumed that when the vehicle contains at least one resin selected from the group consisting of dicyclopentadiene resins, aromatic vinyl resins, and terpene resins, the overall performance of fuel efficiency during city driving and lane change performance during high-speed driving tends to improve.

[0117] C5 resins refer to resins obtained by polymerizing C5 fractions, and may be hydrogenated or modified versions of these resins. Examples of C5 fractions include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, and pentadiene. These C5 resins may be used individually or in combination of two or more types.

[0118] C9 resins refer to resins obtained by polymerizing a C9 fraction, and may be obtained by polymerizing the C9 fraction alone, or as copolymers obtained by copolymerizing the C9 fraction with other components. They may also be hydrogenated or modified. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, coumarone, indene, and methylindene. These C9 resins may be used individually or in combination of two or more types.

[0119] C5C9 resins refer to resins obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified versions of these resins. As C5C9 petroleum resins, for example, those commercially available from Tosoh Corporation, LUHUA, etc., can be used. These C5C9 resins may be used individually or in combination of two or more types.

[0120] Aromatic vinyl resins refer to resins containing aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-chlorostyrene as the most abundant monomer component, and may also be hydrogenated or modified versions of these compounds. For aromatic vinyl resins, α-methylstyrene or a homopolymer of styrene, or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, due to their economical nature, ease of processing, and excellent heat generation properties. Aromatic vinyl resins that can be used are commercially available from companies such as Kraton, Eastman Chemical Company, and Mitsui Chemicals, Inc. These aromatic vinyl resins may be used individually or in combination of two or more types.

[0121] Dicyclopentadiene resins refer to resins containing cyclopentadiene (CPD) or dicyclopentadiene (DCPD) as monomer components, and may be hydrogenated or modified. Examples of dicyclopentadiene resins include DCPD / C9 resins containing dicyclopentadiene and C9 fraction as monomer components (these DCPD / C9 resins may be hydrogenated or modified), with DCPD / C9 resins containing dicyclopentadiene and styrene as monomer components being preferred, and DCPD / C9 resins containing dicyclopentadiene, styrene, and indene as monomer components being particularly preferred. Dicyclopentadiene resins that are commercially available from companies such as ExxonMobil, ENEOS Corporation, Nippon Zeon Corporation, and Maruzen Petrochemical Co., Ltd. can be used. These dicyclopentadiene resins may be used individually or in combination of two or more types.

[0122] Coumarone-based resins refer to resins containing coumarone as a monomer component, and may be hydrogenated or modified resins. Examples of coumarone resins include coumarone-indene resins containing coumarone and indene as monomer components, and coumarone-indene-styrene resins containing coumarone, indene, and styrene as monomer components. These coumarone-based resins may be used individually or in combination of two or more types.

[0123] Indene resins refer to resins containing indene as a monomer component, and may be hydrogenated or modified resins. Examples of indene resins include coumarone-indene resins containing coumarone and indene as monomer components, and coumarone-indene-styrene resins containing coumarone, indene, and styrene as monomer components. These indene resins may be used individually or in combination of two or more types.

[0124] Terpene resins are resins that contain terpene compounds such as α-pinene, β-pinene, limonene, and dipentene as the most abundant monomer component, and may be hydrogenated or modified versions of these compounds. Specific examples of terpene resins include, for example, polyterpene resins containing only one or more of the aforementioned terpene compounds as monomer components; aromatically modified terpene resins containing the aforementioned terpene compounds and aromatic compounds as monomer components; and terpene-phenol resins containing the aforementioned terpene compounds and phenolic compounds as monomer components. Examples of aromatic compounds that serve as monomer components in aromatically modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenolic compounds that serve as monomer components in terpene-phenol resins include phenol, bisphenol A, cresol, and xylenol. These terpene resins may be used individually or in combination of two or more types.

[0125] Rosin-based resins refer to resins containing rosin acid compounds such as abietic acid, neoabietic acid, palastic acid, and isopimal acid, and may be hydrogenated or modified versions of these compounds. Rosin-based resins are not particularly limited, but examples include natural resin rosin and rosin-modified resins obtained by hydrogenation, disproportionation, dimerization, esterification, etc. These rosin-based resins may be used individually or in combination of two or more types.

[0126] Phenolic resins are resins that contain phenol compounds such as phenol and cresol as the most abundant monomer component. Phenolic resins are not particularly limited, but examples include phenol-formaldehyde resins, alkylphenol-formaldehyde resins, alkylphenol-acetylene resins, and oil-modified phenol-formaldehyde resins. These phenolic resins may be used individually or in combination of two or more types.

[0127] The resin may be a modified resin (functionalized resin) into which functional groups have been introduced. Modified resins can be produced by known methods, such as slurry methods and metathesis methods. Specifically, they can be produced, for example, by reacting a polymer that forms the polymer backbone of the modified resin with a functional compound that allows for the introduction of functional groups, using known methods.

[0128] The polymer forming the polymer backbone is not particularly limited and may be, for example, the C5 resin, aromatic resin, or terpene resin mentioned above, or other resins. These may be used alone or in combination of two or more. Among these, aromatic resins are preferred, α-methylstyrene resins are more preferred, and styrene-α-methylstyrene resin (a copolymer of styrene and α-methylstyrene) is even more preferred.

[0129] The functional group is preferably one containing at least one element selected from the group consisting of oxygen, silicon, and nitrogen, and more preferably one containing silicon.

[0130] Commercially available resins from companies such as Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Industries, Ltd. can be used.

[0131] Examples of oils include mineral oil, vegetable oil, and animal oil. Furthermore, from a life cycle assessment perspective, refined waste oil from rubber mixers and engines, or waste cooking oil from restaurants, may also be used. Vegetable oil is particularly preferred.

[0132] In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oils (mineral oil), naphthenic oils, and aromatic oils. Specific examples of mineral oil include MES (Mild Extract Sollvates), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Furthermore, for environmental reasons, oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of such low-PCA oils include MES, TDAE, and heavy naphthenic oils.

[0133] In this specification, vegetable oils include, 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 oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and wood wax. Furthermore, vegetable oils may also include refined oils obtained by refining the above oils (such as salad oil), transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidized polymerized oils obtained by oxidizing the above oils, and waste cooking oils recovered from use as edible oils. Note that vegetable oils may be liquid or solid at 25°C. These vegetable oils may be used individually or in combination of two or more types.

[0134] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer of three or more. Note that acylglycerols of two or more forms can be obtained by thermal polymerization, oxidative polymerization, etc. Also, the acylglycerol may be a liquid or a solid at 25°C.

[0135] The method for confirming whether the acylglycerol is contained in the tire rubber composition is not particularly limited, 1 This can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours, and after removing the rubber composition, it is measured at room temperature. 1When 1H-NMR was measured and the tetramethylsilane (TMS) signal was set to 0.00 ppm, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm. These signals are presumed to originate from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0136] The aforementioned fatty acids are not particularly limited and may be either unsaturated or saturated fatty acids. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0137] In particular, it is desirable that the fatty acid contains fatty acids with few double bonds, i.e., saturated fatty acids or monounsaturated fatty acids, and oleic acid is preferred. As a vegetable oil containing such fatty acids, for example, a vegetable oil containing saturated fatty acids or monounsaturated fatty acids may be used, or a vegetable oil that has been modified by transesterification or other means may be used. Furthermore, in order to produce a vegetable oil containing such fatty acids, plants may be improved by breeding, genetic modification, genome editing, etc.

[0138] As for the oil, commercially available products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used.

[0139] As the liquid rubber, at least one diene-based (co)polymer selected from the group consisting of butadiene, isoprene, styrene, farnesene, and their derivatives can be used. Specific examples include liquid diene-based polymers such as liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), liquid farnesene polymer, and liquid farnesene-butadiene copolymer. Among these, liquid IR is preferred.

[0140] When the above rubber composition contains liquid rubber, although the mechanism by which it is more effective is not clear, it is presumed that the overall performance, including fuel efficiency during city driving and lane change performance during high-speed driving, tends to improve.

[0141] The liquid rubber may be modified with functional groups that interact with silica, or its terminals and / or main chain may be modified with functional groups containing at least one element selected from the group consisting of oxygen, nitrogen, silicon, and phosphorus. The liquid rubber may also be unhydrogenated or hydrogenated.

[0142] In the above rubber composition, the plasticizer content (total amount of plasticizer such as resin and liquid rubber) is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 70 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 100 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 80 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of improving processability, the amount is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, and even more preferably 70 parts by mass or more. Furthermore, from the viewpoint of improving wear resistance, the amount is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less.

[0143] When the above rubber composition contains a solid plasticizer in a solid state under conditions of 1 atmosphere and 25°C, the content of the solid resin is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 50 parts by mass or more, and also preferably 90 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0144] When the above rubber composition contains a liquid plasticizer in a liquid state under conditions of 1 atmosphere and 25°C, the content of the liquid plasticizer is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and also preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, a better effect tends to be obtained. Furthermore, the liquid plasticizer content includes the amount of oil contained in the oil-stretched rubber and the amount of liquid resin in the resin-stretched rubber that has been stretched with liquid resin.

[0145] When the above rubber composition contains resin, the resin content (total amount of resin in a solid state and resin in a liquid state under 1 atmosphere and 25°C conditions) is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 50 parts by mass or more, and also preferably 90 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less. Within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of improving processability, the amount is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and even more preferably 50 parts by mass or more. Furthermore, from the viewpoint of improving wear resistance, the amount is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less.

[0146] When the above rubber composition contains a resin in a solid state under conditions of 1 atmosphere and 25°C, the content of the solid resin is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 50 parts by mass or more, and also preferably 90 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0147] When the above rubber composition contains a resin in a liquid state under conditions of 1 atmosphere and 25°C, the content of the resin in a liquid state is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 50 parts by mass or more, and also preferably 90 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. Furthermore, the amount of resin contained in the liquid state includes the amount of resin contained in the resin-stretched rubber.

[0148] When the above rubber composition contains oil in a liquid state under conditions of 1 atmosphere and 25°C, the oil content is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and also preferably 35 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. When the oil content is within the above range, a better effect tends to be obtained. Note that the oil content also includes the amount of oil contained in the oil-applied rubber.

[0149] When the above rubber composition contains liquid rubber in a liquid state under conditions of 1 atmosphere and 25°C, the content of the liquid rubber is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0150] The above-mentioned tire rubber composition may contain a fatty acid derivative. Examples of the above-mentioned fatty acid derivatives include fatty acid metal salts, amide esters, fatty acid esters, fatty acid amides, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. These may be used individually or in combination of two or more. In particular, it is preferable that at least one is selected from the group consisting of fatty acid metal salts, amide esters, and mixtures of fatty acid metal salts and amide esters or fatty acid amides, more preferably fatty acid metal salts, mixtures of fatty acid metal salts and fatty acid amides, and even more preferably a mixture of fatty acid metal salts and fatty acid amides.

[0151] The fatty acids that make up the fatty acid metal salt are not particularly limited, but include saturated or unsaturated fatty acids (preferably saturated or unsaturated fatty acids having 6 to 28 carbon atoms (more preferably 10 to 25 carbon atoms, and even more preferably 14 to 20 carbon atoms)). Examples include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, behenic acid, and nervonic acid. These can be used individually or in combination of two or more. Among these, saturated fatty acids are preferred, and saturated fatty acids having 14 to 20 carbon atoms are more preferred.

[0152] Examples of metals that make up fatty acid metal salts include alkali metals such as potassium and sodium, alkaline earth metals such as magnesium, calcium and barium, zinc, nickel, and molybdenum. These may be used individually or in combination of two or more. Among these, zinc and calcium are preferred.

[0153] Examples of amide esters include fatty acid amide esters, which are composed of the saturated or unsaturated fatty acids mentioned above. These may be used individually or in combination of two or more types.

[0154] Examples of fatty acid esters include fatty acid esters comprising the saturated or unsaturated fatty acids mentioned above. These may be used individually or in combination of two or more types.

[0155] The fatty acid amide can be either saturated or unsaturated. These may be used individually or in combination of two or more. Examples of saturated fatty acid amides include N-(1-oxooctadecyl)sarcosinamide, stearic acid amide, and behenic acid amide. Examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide.

[0156] Specific examples of mixtures of fatty acid metal salts and amide esters include Aflux16, manufactured by Rhein Chemie, which is a mixture of fatty acid calcium salt and amide ester.

[0157] Specific examples of mixtures of fatty acid metal salts and fatty acid amides include WB16, manufactured by Structol, which is a mixture of fatty acid calcium and fatty acid amide.

[0158] Examples of the above-mentioned fatty acid derivatives include products from companies such as Rhein Chemie and Structol.

[0159] The content of the above fatty acid derivative is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, and even more preferably 6 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0160] The above-mentioned rubber composition for tires may contain vulcanized rubber particles. Vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the viewpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. These may be used individually or in combination of two or more types.

[0161] The vulcanized rubber particles are not particularly limited and may be either unmodified or modified vulcanized rubber particles.

[0162] Commercially available vulcanized rubber particles can be used, for example, products from Lehigh, Muraoka Rubber Industries, Ltd., and others.

[0163] In the above tire rubber composition, the content of vulcanized rubber particles is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of rubber component, and also preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0164] The above-mentioned rubber composition for tires preferably contains an anti-aging agent from the viewpoint of crack resistance, ozone resistance, etc.

[0165] While not particularly limited, examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents 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), and N,N'-ditril-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as methyl amine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, with polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline being more preferred. Commercially available products include those from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis.

[0166] In the above-mentioned rubber composition for tires, the content of the anti-aging agent is preferably 2.0 parts by mass or more, more preferably 4.5 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 10 parts by mass or less, more preferably 6 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0167] The above tire rubber composition may contain stearic acid. In the above-described rubber composition for tires, the stearic acid content is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, and preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. Within this range, a better effect tends to be obtained.

[0168] In addition, conventionally known stearic acid can be used, such as products from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acid Co., Ltd.

[0169] The above rubber composition may contain zinc oxide. In the above rubber composition, the zinc oxide content is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, and preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. Within this range, a better effect tends to be obtained.

[0170] In addition, conventionally known zinc oxides can be used, such as products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd.

[0171] The above-mentioned rubber composition for tires may contain sulfur. In the above-mentioned rubber composition for tires, the sulfur content is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, even more preferably 1.2 parts by mass or more, and preferably 3.5 parts by mass or less, more preferably 3.0 parts by mass or less, and even more preferably 2.5 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, a better effect tends to be obtained.

[0172] Examples of sulfur commonly used in the rubber industry include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur. Commercially available products include those from Tsurumi Chemical Industries, Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Co., Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., and Hosoi Chemical Industry Co., Ltd. These can be used individually or in combination of two or more types.

[0173] The above-mentioned rubber composition for tires may contain a vulcanization accelerator. In the above-mentioned rubber composition for tires, there are no particular restrictions on the content of the vulcanization accelerator, and it can be freely determined according to the desired vulcanization rate and crosslinking density. However, it is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 15 parts by mass or less, and more preferably 10 parts by mass or less.

[0174] There are no particular restrictions on the type of vulcanization accelerator; commonly used ones can be used. Examples of vulcanization accelerators include benzothiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; thiram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl-2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diortotrilguanidine, and orthotrilbiguanidine. Commercially available products from companies such as Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Co., Ltd. can be used. These may be used individually or in combination of two or more. Among these, sulfenamide, guanidine, and benzothiazole vulcanization accelerators are preferred.

[0175] In addition to the above-mentioned components, the above-mentioned rubber composition for tires may also appropriately contain compounding agents commonly used in the tire industry, such as mold release agents.

[0176] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. As a method for obtaining the above formulations from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0177] The above-mentioned rubber composition for tires can be manufactured, for example, by kneading each of the above components using a rubber mixing device such as an open roll or Banbury mixer, and then vulcanizing them.

[0178] Regarding the mixing conditions, in the base mixing step in which additives other than the crosslinking agent (vulcanizing agent) and vulcanization accelerator are mixed, the mixing temperature is preferably 100°C or higher, more preferably 120°C or higher, and also preferably 180°C or lower, more preferably 170°C or lower. In the finish mixing step in which the vulcanizing agent and vulcanization accelerator are mixed, the mixing temperature is preferably 80°C or higher, also preferably 120°C or lower, more preferably 110°C or lower. Furthermore, the composition mixed with the vulcanizing agent and vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is preferably 140°C or higher, more preferably 150°C or higher, also preferably 190°C or lower, more preferably 185°C or lower.

[0179] A tire having a tread made of the above-mentioned tire rubber composition is manufactured by conventional methods using the above-mentioned tire rubber composition. That is, a rubber composition, which may contain various additives as needed, can be extruded to match the shape of the tread at the unvulcanized stage, molded in conventional methods on a tire molding machine, bonded together with other tire components to form an unvulcanized tire, and then heated and pressurized in a vulcanizing machine to manufacture the tire.

[0180] The above-mentioned tires are not particularly limited and include, for example, pneumatic tires, solid tires, and airless tires. Among these, pneumatic tires are preferred.

[0181] The above tires can be used for passenger cars, large passenger cars, large SUVs, heavy-duty trucks and buses, light trucks, motorcycles, racing tires, winter tires (studless tires, snow tires, studded tires), all-season tires, run-flat tires, aircraft tires, mining tires, and more.

[0182] The tread of the above-described tire has a first land portion that is closest to the tire's equator and located on the outside of the vehicle relative to the tire's equator, and a second land portion located further out than the first land portion. In this specification, "outside of the vehicle" refers to the side that is further away from the center of the vehicle when the tire is mounted on the vehicle.

[0183] "The first land area closest to the equator on the outside of the vehicle, beyond the tire's equator" refers to a land area with a contact surface at least outside the vehicle's equator, in cases where there is no main groove on the equator. Examples of such land areas include land areas that straddle the equator or land areas that extend outside the vehicle with the equator as the groove edge. In cases where there is a main groove on the equator, it refers to the land area closest to the tire's equator on the outside of the vehicle, beyond the tire's equator.

[0184] "The second land area located outside the first land area" refers to the land area that is located outside the tire axis direction (outside the vehicle) of the first land area and has the largest width. If there are multiple such land areas, it refers to the land area closest to the outer contact edge of the vehicle.

[0185] "The width W1 of the first land section closest to the equator outside the vehicle, beyond the tire equator" and "the width W2 of the second land section located outside the first land section" refer to the widths of the "first land section closest to the equator outside the vehicle, beyond the tire equator" and "the second land section located outside the first land section," respectively, as defined above.

[0186] In this specification, "land area" refers to the portion of the area between two main grooves, or between one main groove and the tire's widthwise contact edge, that is intended to be in contact with the road surface.

[0187] In this specification, the main groove is defined as a groove that is continuous in the circumferential direction of the tire and has a cross-sectional area perpendicular to the circumferential direction of the tire of 10 mm². 2 This refers to the grooves described above. The shape of the grooves may be a straight line parallel to the circumferential direction of the tire, a wavy line, or a straight line that bends multiple times (zigzag).

[0188] The tire of the present invention has two land sections on the outside of the vehicle beyond the tire's equator, so at least one main groove is located outside the tire's equator.

[0189] Furthermore, the overall performance of the present invention, which includes low fuel consumption during city driving and lane change performance during high-speed driving, is largely due to the contribution of the land portion on the outside of the vehicle rather than the tire's equator. Therefore, any pattern may be formed on the inside of the tire's equator. It is preferable that the same relationship is satisfied for the land portion on the inside of the vehicle rather than the tire's equator in the tire tread. In other words, it is preferable that equation (1) is satisfied even when the inside and outside of the tire are swapped and mounted on the vehicle.

[0190] Figure 1 is an exploded view of the tread portion of one embodiment of the above tire. In Figure 1, the right side is the outer side in the tire axial direction (outside the vehicle), and the left side is the inner side in the tire axial direction (inside the vehicle).

[0191] The tread section is provided with at least two main grooves, and in this embodiment, as shown in Figure 1, three main grooves 2 are provided. The main grooves 2 include a main groove 2B that extends along the tire equator C, and main grooves 2A and 2C that extend on both outer sides of the main groove 2B. Each main groove 2 extends continuously in a straight line in the circumferential direction of the tire.

[0192] Each main groove 2 divides the tread's land portion 1 into four sections, 1A to 1D. In Figure 1, the land portion 1C located on the outer side of the vehicle in the main groove 2B extending along the tire equator C corresponds to the "first land portion that is closest to the equator while being on the outer side of the vehicle than the tire's equator," and the land portion 1D located on the outer side of the main groove 2C in the tire axial direction corresponds to the "second land portion that is located further out than the first land portion."

[0193] In the above-described tire, the width W1 of the first land portion closest to the equator on the outside of the vehicle, relative to the tire's equator, is preferably 10 mm or more, more preferably 15 mm or more, even more preferably 20 mm or more, and also preferably 35 mm or less, more preferably 30 mm or less, and even more preferably 25 mm or less. Within this range, a better effect tends to be obtained.

[0194] In the above-described tire, the width W2 of the second land portion, which is positioned outside the first land portion, is preferably 10 mm or more, more preferably 15 mm or more, even more preferably 20 mm or more, and also preferably 40 mm or less, more preferably 35 mm or less, and even more preferably 30 mm or less. When the width is within the above range, a better effect tends to be obtained.

[0195] For the above tires, W1 / W2 > 0.3. The value of (left side) is preferably 0.5 or higher, more preferably 0.6 or higher, even more preferably 0.7 or higher, and also preferably 2.0 or lower, more preferably 1.5 or lower, and even more preferably 1.0 or lower. When the value is within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of improving wear resistance, the value is preferably 0.71 or higher, and more preferably 1.0 or higher. Furthermore, from the viewpoint of improving grip performance during turning, the value is preferably 1.0 or lower, and more preferably 0.72 or lower. In this relationship, W1 is the width (in mm) of the first land portion closest to the equator, located outside the tire's equator on the vehicle's exterior, and W2 is the width (in mm) of the second land portion located outside the first land portion.

[0196] In the above tire, the total amount of styrene in the rubber component / (W1 - W2 × 0.3) ≤ 1.5. The value of (left side) is preferably 1.0 or less, more preferably 0.5 or less, even more preferably 0.3 or less, and also preferably 0.01 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. When it is within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of improving durability, it is preferably 0.87 or less, more preferably 0.22 or less. Also, from the viewpoint of improving dry grip performance, it is preferably 0.21 or more, more preferably 0.86 or more. In this relationship, the total styrene content is the content per 100g of rubber component (unit: mass%), W1 is the width of the first land portion closest to the equator on the outside of the vehicle, and W2 is the width of the second land portion located outside the first land portion (unit: mm). [Examples]

[0197] The following examples (implementations) are considered preferable for implementation, but the scope of the present invention is not limited to these examples.

[0198] The various chemicals used in the examples and comparative examples are described below. NR:TSR20 SBR1: SBR synthesized in the following manufacturing example 1 (Tg -60℃, styrene content 20% by mass, vinyl content 20% by mass, Mw 700,000) SBR2: SBR synthesized in the following manufacturing example 2 (Tg -85℃, styrene content 5% by mass, vinyl content 11% by mass, Mw 900,000) SBR3: HPR850 manufactured by JSR Corporation (Tg -24℃, styrene content 27.5% by mass, vinyl content 59% by mass) BR: BR150B manufactured by Ube Industries, Ltd. (cis content 95% by mass or more) Carbon Black: N220 (CTAB specific surface area: 111 m²) 2 / g) Silica 1: Evonik ULTRASIL VN3 (CTAB specific surface area 170 m²) 2 / g) Silica 2: Zeosil Premium SW manufactured by Solvay (CTAB specific surface area 245 m 2 / g) Silica 3: ULTRASIL 9100GR manufactured by Evonik (CTAB specific surface area 200 m 2 / g) Magnesium sulfate: MN-00 manufactured by Biki Kasei Kogyo Co., Ltd. (anhydrous magnesium sulfate, median particle size 75 μm) Silane coupling agent 1: Si266 manufactured by Evonik (bis(3-triethoxysilylpropyl) disulfide) Silane coupling agent 2: NXT manufactured by Momentive (3-octanoylthiopropyltriethoxysilane) Ionic bonding coupling agent 1: X-12-1126 of Shin-Etsu Chemical Co., Ltd. (quaternary ammonium salt, hydrolyzate of the compound represented by formula (1), compound represented by formula (1-1)) Ionic bonding coupling agent 2: KBM-9418-40 of Shin-Etsu Chemical Co., Ltd. (quaternary ammonium salt, compound represented by formula (1)) Liquid rubber: LIR-410 manufactured by Kuraray Co., Ltd. (maleic acid-modified liquid polyisoprene, Mw 30000) Oil 1: VIVATEC500 manufactured by H&R Oil 2: Nisshin Soybean Refined Oil manufactured by Nisshin Oillio Group Co., Ltd. Resin 1: Oppera PR-383 manufactured by Exxon Mobil (hydrogenated DCPD-C9 resin) Resin 2: Sylvatraxx4401 manufactured by Arizona Chemical (copolymer of α-methylstyrene and styrene) Resin 3: YS Resin TO125 manufactured by Yasuhara Chemical Co., Ltd. (terpene styrene resin (copolymer of terpene compound and styrene)) Wax: Oz Ace 0355 manufactured by Nippon Seiro Co., Ltd. Fatty acid derivative 1: WB16 manufactured by Struktol (mixture of fatty acid metal salt (calcium fatty acid, constituent fatty acid: saturated fatty acid with 14 to 20 carbon atoms) and fatty acid amide) Fatty acid derivative 2: Activator 73A manufactured by Struktol (mixture of zinc salts of aliphatic carboxylic acids and zinc salts of aromatic carboxylic acids) Antioxidant 1: Nocrack 6C manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) (6PPD) Antioxidant 2: Antage RD manufactured by Kawaguchi Chemical Industry Co., Ltd. (polymer of 2,2,4-trimethyl-1,2-dihydroquinoline) Stearic acid: Stearic acid "Tsubaki" manufactured by NOF Corporation Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (powder sulfur containing 5% by mass of oil) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Nocceler CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Vulcanization accelerator 2: Nocceler D (diphenylguanidine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

[0199] (Production Example 1) Charge cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene into a nitrogen-substituted autoclave reactor. Adjust the temperature of the contents of the reactor, add n-butyllithium to initiate polymerization. Polymerize under adiabatic conditions. When the polymerization conversion rate reaches 99%, add 1,3-butadiene and further polymerize, and carry out the reaction with 3-dimethylaminopropyltriethoxysilane as a modifier. After the polymerization reaction is completed, add 2,6-di-tert-butyl-p-cresol. Then, remove the solvent by steam stripping and dry by a hot roll to obtain SBR1.

[0200] (Production Example 2) Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. The temperature of the reactor contents is adjusted, and n-butyllithium is added to initiate polymerization. Polymerization is carried out under adiabatic conditions, and when the polymerization conversion rate reaches 99%, 1,3-butadiene is added and polymerization is continued, and N-(3-dimethylaminopropyl)acrylamide is added as a modifier to carry out the reaction. After the polymerization reaction is complete, 2,6-di-tert-butyl-p-cresol is added. Then, the solvent is removed by steam stripping, and the mixture is dried with a hot roll to obtain SBR2.

[0201] <Examples and Comparative Examples> (Base mixing process) According to the formulations shown in Tables 1 and 2, the materials are placed in a Banbury mixer and kneaded. After kneading at a rubber temperature of 160°C for 2 minutes, the mixture is discharged. Only the mixture (sheet rubber) obtained from the discharge is put into a Banbury mixer and kneaded further (discharge temperature 160°C). (Final mixing process) The above mixture, sulfur, and vulcanization accelerator are placed in a Banbury mixer and kneaded to obtain an unvulcanized rubber composition. Kneading is stopped when the rubber temperature reaches 100°C. (Vulcanization process) An unvulcanized rubber composition is molded into the shape of a cap tread, bonded together with other tire components to form an unvulcanized tire, and then press-vulcanized at 150°C for 12 minutes to obtain a test tire.

[0202] The above test tires were evaluated as follows. The results are shown in Tables 1 and 2. In the evaluation method described below, the evaluation criteria for calculating the index are as follows: Table 1: Comparative Example 1 Table 2: Comparative Example 4

[0203] Furthermore, the tire sizes in Tables 1 and 2 are as follows: Table 1:245 / 45R18 Table 2:215 / 55R17

[0204] Also, W1 and W2 in Tables 1 and 2 are as follows. Table 1: W1: 20 mm, W2: 28 mm, W1 / W2: 0.714 Table 2: W1: 20 mm, W2: 20 mm, W1 / W2: 1.0

[0205] (Low fuel consumption performance during urban driving) Each test tire is assembled onto a standard rim and filled with the standard internal pressure. Each test tire is mounted on all wheels of a vehicle, and the vehicle is driven on a dry road surface of a test course simulating a driving condition close to urban driving. After driving a predetermined distance, the fuel reduction is measured and displayed as an index with a reference value of 100. The larger the index, the better the low fuel consumption performance during urban driving.

[0206] (Lane change performance during high-speed driving) Each test tire is assembled onto a standard rim and filled with the standard internal pressure. Each test tire is mounted on all wheels of a vehicle, and the vehicle is driven on a test course on a dry road surface for familiarization driving. Then, the vehicle is driven on the test course on a dry road surface at about 120 km / h, a lane change is performed, and each driver evaluates the vehicle's wobbling on a 5-point scale from 1 (1 point: feeling significant wobbling) to 5 points (5 points: feeling no wobbling). The larger the index, the better the lane change performance during high-speed driving. The total score when this test is conducted by 10 drivers is calculated. The score is indexed with a reference value of 100 to obtain the evaluation results of each tire. (Lane change performance during high-speed driving) = (Total score of each test tire) / (Total score of the reference value) × 100

[0207] [Table 1] [Table 2]

[0208] The present invention (1) is a tire having a tread, The tread is composed of a tire rubber composition containing a rubber component including styrene-butadiene rubber and an ionic coupling agent, and has a first land portion closest to the equator on the outside of the vehicle relative to the equator of the tire, and a second land portion located further out than the first land portion. The tire must satisfy the following conditions (1) to (3). (1) The amount of styrene in the styrene-butadiene rubber is 20% by mass or less. (2) When the width of the first land area is W1 and the width of the second land area is W2, W1 / W2 > 0.3 (3) Total amount of styrene in the rubber component / (W1 - W2 × 0.3) ≤ 1.5

[0209] The present invention (2) is the tire according to the present invention (1), wherein the glass transition temperature of the styrene-butadiene rubber is -60°C or lower.

[0210] The present invention (3) is the tire according to the present invention (2), wherein the glass transition temperature of the styrene-butadiene rubber is -70°C or lower.

[0211] The present invention (4) is a tire in any combination of the rubber composition containing silica with any of the present inventions (1) to (3).

[0212] The present invention (5) relates to the silica having a CTAB specific surface area of ​​200 m². 2 The tire is described in (4) of the present invention, which is 1 / g or more.

[0213] The present invention (6) is a tire according to the present invention (4) or (5), wherein the silica content per 100 parts by mass of the rubber component is 110 parts by mass or more.

[0214] The present invention (7) is a tire in any combination of the present invention (1) to (6), wherein the rubber composition contains a resin, and the resin content is 40 parts by mass or more per 100 parts by mass of the rubber component.

[0215] The present invention (8) is a tire in any combination of the present invention (1) to (7), wherein the rubber composition contains a resin, and the resin is at least one selected from the group consisting of dicyclopentadiene resins, aromatic vinyl resins, and terpene resins.

[0216] The present invention (9) is a tire in any combination of the rubber composition containing a mercapto-silane coupling agent with any of the present inventions (1) to (8).

[0217] The present invention (10) is a tire in any combination of the rubber composition containing liquid rubber with any of the present inventions (1) to (9).

[0218] The present invention (11) is a tire in any combination of the rubber composition containing a water-soluble filler with any of the present inventions (1) to (10).

[0219] The present invention (12) is a tire in any combination of the present invention (1) to (11), wherein the rubber composition contains a plasticizer, and the content of the plasticizer is 50 parts by mass or more per 100 parts by mass of the rubber component.

[0220] The present invention (13) is a tire in any combination of the rubber composition containing vegetable oil with any of the present inventions (1) to (12).

[0221] The present invention (14) is a tire in any combination of the present invention (1) to (13), wherein the styrene content of the styrene-butadiene rubber is 10% by mass or less.

[0222] The present invention (15) is a tire in any combination of the present invention (1) to (14) wherein the total amount of styrene in the rubber component / (W1 - W2 × 0.3) ≤ 0.5. [Explanation of symbols]

[0223] 1 land area 2 Main groove C Tire Equator

Claims

1. A tire having a tread, The tread is composed of a tire rubber composition containing a rubber component including styrene-butadiene rubber and an ionic coupling agent, and has a first land portion closest to the equator on the outside of the vehicle relative to the equator of the tire, and a second land portion located further out than the first land portion. A tire that satisfies the following conditions (1) to (3). (1) The amount of styrene in the styrene-butadiene rubber is 20% by mass or less. (2) When the width of the first land area is W1 and the width of the second land area is W2, W1 / W2 > 0.3 (3) Total amount of styrene in the rubber component / (W1 - W2 × 0.3) ≤ 1.5

2. The tire according to claim 1, wherein the glass transition temperature of the styrene-butadiene rubber is -60°C or lower.

3. The tire according to claim 2, wherein the glass transition temperature of the styrene-butadiene rubber is -70°C or lower.

4. The tire according to claim 1 or 2, wherein the rubber composition contains silica.

5. The CTAB specific surface area of ​​the aforementioned silica is 200 m². ２ The tire according to claim 4, which is 1 / g or more.

6. The tire according to claim 4, wherein the silica content relative to 100 parts by mass of the rubber component is 110 parts by mass or more.

7. The tire according to claim 1 or 2, wherein the rubber composition contains a resin, and the resin content is 40 parts by mass or more per 100 parts by mass of the rubber component.

8. The tire according to claim 1 or 2, wherein the rubber composition contains a resin, and the resin is at least one selected from the group consisting of dicyclopentadiene resins, aromatic vinyl resins, and terpene resins.

9. The tire according to claim 1 or 2, wherein the rubber composition contains a mercapto-silane coupling agent.

10. The tire according to claim 1 or 2, wherein the rubber composition contains liquid rubber.

11. The tire according to claim 1 or 2, wherein the rubber composition contains a water-soluble filler.

12. The tire according to claim 1 or 2, wherein the rubber composition contains a plasticizer, and the content of the plasticizer is 50 parts by mass or more per 100 parts by mass of the rubber component.

13. The tire according to claim 1 or 2, wherein the rubber composition contains vegetable oil.

14. The tire according to claim 1 or 2, wherein the amount of styrene in the styrene-butadiene rubber is 10% by mass or less.

15. The tire according to claim 1 or 2, wherein the total amount of styrene in the rubber component / (W1 - W2 × 0.3) ≤ 0.5.

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