tire

Abstract

To provide a rubber composition for tires with improved overall performance in fuel efficiency, wet grip performance, and wear resistance, as well as to provide a tire.SOLUTION: A rubber composition for tires contains 0.1 pt.mass or more and 5 pts.mass or less of tetrazine compound based on 100 pts.mass of a rubber component. The rubber component contains more than 25 mass% of an isoprene rubber, more than 50 mass% of a styrene-butadiene rubber, and a butadiene rubber. When a content of the isoprene rubber in 100 pts.mass of the rubber component is defined as AIR, and a content (pts.mass) of the tetrazine compound is defined as ATET, AIR and ATET satisfy the formula (1). When a loss tangent of the rubber composition for tires at 30°C is defined as 30°Ctanδ and a loss tangent at 0°C is defined as 0°Ctanδ, 30°Ctanδ and 0°Ctanδ satisfy the formula (2) and the formula (3). ATET / AIR>0.020 (1), 30°Ctanδ≤0.15 (2) and 0°Ctanδ / 30°Ctanδ>2.0 (3).SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a rubber composition for tires and a tire. [Background technology]

[0002] Generally, tires widely used in passenger cars and the like are required to achieve a high level of both fuel efficiency and wet grip performance. For example, Patent Document 1 discloses a method for improving wet braking performance and rolling resistance performance by using a rubber composition containing a predetermined amount of styrene-butadiene rubber and butadiene rubber with a predetermined cis-1,4 bond content in a predetermined ratio. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2006-307039 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, in addition to fuel efficiency and wet grip performance, it is also necessary to improve the wear resistance of the tires so that they can be used for a long time.

[0005] The present invention aims to provide a rubber composition for tires and a tire that improves the overall performance of fuel efficiency, wet grip performance, and wear resistance. [Means for solving the problem]

[0006] This invention relates to the following rubber compositions for tires. A tire rubber composition comprising 0.1 to 5 parts by mass of silica and a tetrazine compound per 100 parts by mass of rubber component, The rubber component comprises more than 25% by mass of isoprene rubber, more than 50% by mass of styrene-butadiene rubber, and butadiene rubber. The content (parts by mass) of isoprene-based rubber in 100 parts by mass of the aforementioned rubber component is A IR The content (parts by mass) of the tetrazine compound is set to A TET In that case, A IR and A TET and satisfy equation (1) below, The tire rubber composition wherein the loss tangent at 30°C is 30°C tanδ and the loss tangent at 0°C is 0°C tanδ, and the 30°C tanδ and 0°C tanδ satisfy the following equations (2) and (3). A TET / A IR >0.020 (1) 30℃ tanδ ≤ 0.15 (2) 0°C tanδ / 30°C tanδ > 2.0 (3) [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a rubber composition for tires and tires that have improved overall performance in terms of fuel efficiency, wet grip performance, and wear resistance. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the tire cross-section width Wt, tire cross-section height Ht, and tire outer diameter Dt. [Figure 2] This figure schematically represents the tread contact surface in a tire according to one embodiment of the present invention. The enclosed area in the figure is the tread contact surface. [Figure 3] This figure shows the tread pattern of a tire according to one embodiment of the present invention. [Figure 4] This is a schematic representation of a portion of the cross-sectional view of a tire according to one embodiment of the present invention. [Modes for carrying out the invention]

[0009] The rubber composition for tires of the present invention is a rubber composition for tires containing silica and 0.1 to 5 parts by mass of a tetrazine compound with respect to 100 parts by mass of a rubber component, wherein the rubber component contains more than 25% by mass of an isoprene-based rubber, more than 50% by mass of a styrene-butadiene rubber, and a butadiene rubber, and the content (parts by mass) of the isoprene-based rubber in 100 parts by mass of the rubber component is A IR is taken, and the content (parts by mass) of the tetrazine compound is A TET When taken as, A IR and A TET satisfy the following formula (1), and when the loss tangent at 30°C of the rubber composition for tires is 30°C tanδ and the loss tangent at 0°C is 0°C tanδ, the rubber composition for tires is such that 30°C tanδ and 0°C tanδ satisfy the following formula (2) and formula (3). A TET / A IR > 0.020 (1) 30°C tanδ ≤ 0.15 (2) 0°C tanδ / 30°C tanδ > 2.0 (3)

[0010] Although not intending to be bound by theory, in the present invention, the following can be considered as a mechanism for improving the overall performance of low fuel consumption performance, wet grip performance, and wear resistance. That is, a predetermined amount of silica and a tetrazine compound are blended with a rubber component containing more than 25% by mass of an isoprene-based rubber, more than 50% by mass of a styrene-butadiene rubber, and a butadiene rubber, and by satisfying formula (1), the uneven distribution of silica is suppressed. Further, by satisfying formula (2) and formula (3) in that state, it is considered that the overall performance of low fuel consumption performance, wet grip performance, and wear resistance is improved.

[0011] The right side of the formula (1) is preferably 0.050.

[0012] It is considered that by increasing the content ratio of the tetrazine compound with respect to the isoprene-based rubber, the wear resistance of the isoprene rubber layer can be improved.

[0013] The right-hand side of equation (3) is preferably 3.0.

[0014] It is believed that wet grip performance can be improved by increasing the ratio of 0°C tanδ, which is related to the exothermic properties at low temperatures, to 30°C tanδ, which is related to the exothermic properties at room temperature.

[0015] The content (parts by mass) of styrene-butadiene rubber in 100 parts by mass of rubber component is A SBR The content of the butadiene rubber is set to A BR In that case, A SBR and A BR and A IR Preferably, the following equation (4) is satisfied. A SBR >A IR >A BR (4)

[0016] By increasing the content in order of decreasing glass transition temperature, it is possible to improve the balance between wear resistance and wet grip performance.

[0017] The silica content is preferably 90 parts by mass or less per 100 parts by mass of the rubber component.

[0018] It tends to be easier to ensure low fuel consumption.

[0019] The silica preferably contains silica with an average primary particle diameter of 17 nm or less.

[0020] It is believed that this can improve wear resistance.

[0021] The aforementioned tire rubber composition contains carbon black, The silica content (parts by mass) per 100 parts by mass of rubber component is A SIL The carbon black content (parts by mass) per 100 parts by mass of rubber component is set to A CB In that case, A SIL and A CB Preferably, the following equation (5) is satisfied. ACB / A SIL <1 (5)

[0022] A silica-rich formulation is considered preferable for achieving the effects of the present invention.

[0023] The aforementioned tire rubber composition preferably contains a mercapto-silane coupling agent.

[0024] It is believed that fuel efficiency can be improved by including a mercapto-silane coupling agent.

[0025] Another embodiment of the present invention is a tire having a tread made of the tire rubber composition described above.

[0026] When the maximum load capacity of the tire is WL (kg) and the weight of the tire is G (kg), it is preferable that WL and G satisfy the following equation (6). G / WL ≤ 0.012 (6)

[0027] Tires that satisfy equation (6) are relatively lightweight and therefore generate less heat, which is considered desirable from the standpoint of fuel efficiency.

[0028] When the land ratio (%) of the tread contact surface of the aforementioned tread is B, A SBR It is preferable that B satisfies the following equation (7). A SBR ×B>25.0 (7)

[0029] By fulfilling the above requirements, it is believed that the balance between wear resistance and wet grip performance can be improved.

[0030] Preferably, the tread surface of the tread has one or more circumferential grooves that extend continuously in the circumferential direction of the tire, and a land area partitioned by the circumferential grooves, wherein the land area has transverse grooves that extend toward the radially inward direction of the tire, and the transverse grooves have a portion in which the groove width is wider than the groove width on the tread surface in a cross section perpendicular to the extension direction.

[0031] By positioning the aforementioned lateral grooves on the land portion, it is believed that the increase in compressive stiffness can be suppressed even as wear progresses, thereby ensuring wet grip performance.

[0032] The groove bottom gauge of the tread is preferably 1 mm or more and 4 mm or less.

[0033] By keeping the groove bottom gauge within the above range, heat generation can be suppressed, which is thought to contribute to improved fuel efficiency.

[0034] The tread surface of the tread has one or more circumferential grooves that extend continuously in the circumferential direction of the tire, and when the area of ​​the tread surface that is 30% of the tread contact width with respect to the tire equator is defined as the center region, it is preferable that at least one of the circumferential grooves in the center region is zigzag-shaped.

[0035] The fact that at least one of the circumferential grooves in the central region is zigzag-shaped enhances the heat dissipation effect by the airflow through the circumferential groove, which is thought to improve durability and contribute to wear resistance.

[0036] In the tread surface, when the area 30% of the tread contact width centered on the tire equator is defined as the center region, and the areas on both sides of the center region that are within the tread contact width are defined as a pair of shoulder regions, it is preferable that the groove depth of the deepest part of the circumferential grooves in the shoulder regions is 10 mm or more.

[0037] The above configuration is expected to improve drainage and thus contribute to improved wet grip performance.

[0038] <Definition> Unless otherwise specified, the "dimensions of each part of the tire" refer to the values ​​specified in the standard unloaded condition, when the tire is mounted on a standard rim and filled with the standard internal pressure.

[0039] A "standard rim" refers to the rim specified for each tire within the standard system that includes the standard on which the tire is based. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." In the case of tires not specified in the standard, it refers to the rim with the smallest diameter and narrowest rim width among rims that can be mounted on and can maintain internal pressure, i.e., rims that do not cause air leakage between the rim and tire.

[0040] "Regular internal pressure" refers to the air pressure specified for each tire by each standard within the tire standard system, including the standard on which the tire is based. For example, it is the "maximum air pressure" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO.

[0041] "Regular load" refers to the load specified for each tire by each standard within the standards system that the tire is based on. For example, it is the maximum load capacity for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO.

[0042] "Maximum load capacity (WL) (kg)" is a value calculated by the following formulas (A) and (B), where Wt (mm) is the tire section width, Ht (mm) is the tire section height, and Dt (mm) is the tire outer diameter, as measured under normal conditions. V is the virtual volume of space occupied by the tire. The tire section width Wt is the maximum width between the outer surfaces of the sidewalls under normal conditions, excluding any patterns or letters on the tire sidewall. The tire section height Ht is the distance from the bottom of the bead to the outermost surface of the tread, and the tire outer diameter is half the difference between the nominal rim diameter and the tire outer diameter. In this disclosure, maximum load capacity refers to the "maximum load capacity (WL) (kg)" described above, unless otherwise specified. V = {(Dt / 2)} 2 -(Dt / 2-Ht) 2} × π × Wt ···(A) WL = 0.000011 × V + 100 ... (B)

[0043] "Tire weight" is expressed in G (kg). However, G is the weight of the tire alone, excluding the weight of the rim. On the other hand, if the tire contains components such as sponge or sealant, or sensor components, the weight includes these components.

[0044] "Land ratio B" is the ratio of the contact surface area to the total surface area of ​​the tread contact surface when a tire in a normal state is subjected to a normal load, with a camber angle of 0 degrees, and making contact with a flat surface, assuming that all grooves are filled. It is obtained by applying ink to the tread surface and pressing it onto cardboard. Here, "all grooves" includes the circumferential grooves and lateral grooves mentioned above.

[0045] A "horizontal groove" is a groove found on land, and its width is not particularly limited. Therefore, in addition to grooves with a width of 2 mm or more, it also includes narrow grooves with a width of less than 2 mm, which are sometimes called sipes.

[0046] The "groove bottom gauge" refers to the thickness of the rubber from the deepest part of the circumferential groove to the cords of the belt layer (or the cords of the belt protection layer if the belt protection layer has cords), and in the case of multiple grooves, it refers to the gauge that represents the maximum thickness of the rubber.

[0047] "Zigzag" refers to a design where the center of the circumferential groove in the width direction oscillates in the tire's width direction while extending circumferentially. Therefore, it includes not only designs where straight grooves repeatedly bend, but also designs where curved grooves repeatedly curve in a wave-like pattern.

[0048] A "circumferential groove in the center region" refers to a circumferential groove located within the center region, where the center region is defined as 30% of the tread contact width with the tire equator as the center of the tread surface, and the two outer regions of the center region that are within the tread contact width are defined as a pair of shoulder regions. When a circumferential groove spans both the center region and the shoulder regions, it is considered a circumferential groove in the center region if more than half of it is located in the center region.

[0049] "Circumferential grooves in the shoulder region" refers to circumferential grooves present on the tread surface that are not present in the center region.

[0050] "The groove depth of the deepest part of the circumferential groove in the shoulder region" refers to the groove depth of the circumferential groove with the deepest groove depth if there are multiple circumferential grooves in the shoulder region.

[0051] "Plasticizer content" includes the amount of plasticizer in the rubber component stretched by the plasticizer. Similarly, "oil content" includes the amount of oil contained in the oil-stretched rubber.

[0052] <Measurement method> "Styrene content" is, 1 It is calculated by 1H-NMR measurement.

[0053] The "vinyl bond amount (amount of 1,2-bonded butadiene units)" is measured by infrared absorption spectroscopy.

[0054] The "cis content (amount of cis-1,4-linked butadiene units)" is measured by infrared absorption spectroscopy.

[0055] The "weight-average molecular weight (Mw)" can be determined by converting the measured value obtained by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMALTPORE HZ-M manufactured by Tosoh Corporation) to standard polystyrene equivalent.

[0056] The "N2SA of carbon black" is a value determined according to JIS K 6217-2:2017.

[0057] "N2SA of silica" is a value measured by the BET method in accordance with ASTM D3037-93.

[0058] The "average primary particle diameter" is a value determined by observing with a transmission or scanning electron microscope, measuring 400 or more primary particles observed within the field of view, and averaging the results. This method is applied to materials such as silica and carbon black.

[0059] Unless otherwise specified, the "softening point of resins, etc." is the temperature at which the sphere descends when the softening point specified in JIS K 6220-1:2015 is measured using a ring-type softening point measuring device. If the softening point is measured by another method, this will be noted.

[0060] "30℃tanδ" is measured using a GABO iplexer series under the conditions of 30℃ temperature, 5% initial strain, 1% dynamic strain, 10Hz frequency, and extension mode. When taking samples from tires, a sample measuring 20mm in length, 4mm in width, and 1mm in thickness is taken from inside the rubber layer of the tread of each test tire, with the tire circumference being the longer side and the tire radius being the thickness.

[0061] "0°C tanδ" is measured using a GABO iplexer series instrument under the conditions of 0°C temperature, 10% initial strain, 2.5% dynamic strain, 10 Hz frequency, and extension mode. When sampling from a tire, the procedure is the same as for 30°C tanδ.

[0062] <Rubber composition for tires> The present invention describes the rubber composition for tires. The rubber composition for tires of the present invention contains 0.1 to 5 parts by mass of a tetrazine compound per 100 parts by mass of rubber component.

[0063] (Rubber component) The rubber component of the present invention comprises more than 25% by mass of isoprene rubber, more than 50% by mass of styrene-butadiene rubber, and butadiene rubber.

[0064] Isoprene-based rubber Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. For NR, for example, commonly used rubbers in the tire industry such as SIR20, RSS#3, and TSR20 can be used. For IR, there are no particular limitations, and commonly used rubbers in the tire industry such as IR2200 can be used. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used individually or in combination of two or more types.

[0065] The isoprene-based rubber content in 100% by mass of the rubber component is preferably 26% by mass or more, more preferably more than 28% by mass, and even more preferably 30% by mass or more. The upper limit is preferably less than 45% by mass, more preferably less than 40% by mass, and even more preferably less than 35% by mass. Keeping it within the above range tends to improve fuel efficiency and wet grip performance.

[0066] ≪SBR≫ The type of SBR used is not particularly limited; for example, emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR) can be used. Furthermore, the SBR may be unmodified or modified. Hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used. These may be used individually or in combination of two or more types.

[0067] The styrene content of SBR is preferably more than 5.0% by mass, more preferably more than 10.0% by mass, and even more preferably more than 20.0% by mass. The styrene content is preferably less than 40.0% by mass, more preferably less than 35.0% by mass, and even more preferably less than 30.0% by mass. Within the above range tends to improve fuel efficiency and wet grip performance. In this specification, the styrene content is defined as follows: 1 It can be measured by 1H-NMR.

[0068] The vinyl bonding amount of SBR is preferably more than 30% by mass, more preferably more than 40% by mass, and even more preferably more than 50% by mass. The vinyl bonding amount is preferably less than 80% by mass, more preferably less than 70% by mass, and even more preferably less than 65% by mass. Keeping it within the above range tends to improve fuel efficiency and wet grip performance. The vinyl bonding amount can be measured by the method described above.

[0069] SBR can be either stretched SBR (stretched SBR) or unstretched SBR. When using stretched SBR, the amount of stretching of the SBR, i.e., the amount of stretching plasticizer contained in the SBR, is preferably 10 to 50 parts by mass per 100 parts by mass of rubber solids in the SBR. As a plasticizer used for stretching, oil is preferably used, for example.

[0070] 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.

[0071] The SBR content in 100% by mass of the rubber component is preferably 52% by mass or more, more preferably more than 55% by mass, and even more preferably 60% by mass or more. The upper limit is preferably less than 90% by mass, more preferably less than 80% by mass, and even more preferably less than 70% by mass. Keeping it within the above range tends to improve fuel efficiency and wet grip performance.

[0072] ≪BR≫ BR is not particularly limited; for example, high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using rare-earth catalysts (rare-earth BR) can be used. These may be used individually or in combination of two or more.

[0073] In particular, BR is preferably high-cis BR with a cis content of more than 90% by mass. The cis content is more preferably more than 95% by mass, and more preferably 98% by mass or more. The cis content can be measured by the method described above.

[0074] Furthermore, BR may be either unmodified BR or modified BR. Modified BR can be BR in which functional groups similar to those of modified diene rubber have been introduced. In addition, hydrogenated butadiene polymer (hydrogenated BR) can also be used as BR.

[0075] For example, products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used as BRs.

[0076] The BR content in 100% by mass of the rubber component is preferably more than 1% by mass, more preferably more than 3% by mass, even more preferably more than 5% by mass, even more preferably more than 10% by mass, even more preferably more than 15% by mass, and even more preferably 18% by mass or more. The upper limit is preferably less than 30% by mass, more preferably less than 25% by mass, and even more preferably 22% by mass or less. Keeping it within the above range tends to improve fuel efficiency and wet grip performance.

[0077] ≪Formula (4)≫ The amount of isoprene-based rubber in 100 parts by mass of rubber components (parts by mass) is A IR The content (parts by mass) of styrene-butadiene rubber is A SBR , the butadiene rubber content is A BR In that case, A IR and A SBR and A BR From the viewpoint of the effects of the present invention, it is preferable that the following formula (4) is satisfied. A SBR >A IR >A BR (4)

[0078] Here, A SBR / A IR The value of is preferably greater than 1.3, more preferably greater than 1.5, and even more preferably greater than 1.7. The upper limit of this value is naturally restricted, but for example, it may be less than 2.9 or less than 2.5. Also, A IR / A BR The value of is preferably greater than 1.1, more preferably greater than 1.6, and even more preferably greater than 2.9. The upper limit of this value is naturally restricted, but for example, it may be less than 48.0, less than 9.0, less than 4.5, or less than 3.0.

[0079] <<Other rubber components>> Other rubbers can be used as the rubber component. Examples of other rubbers include diene rubbers such as styrene-isoprene butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR), as well as non-diene rubbers such as ethylene-propylene diene rubber (EPDM), butyl rubber (IIR), and halogenated butyl rubber (X-IIR). These may be used individually or in combination of two or more types.

[0080] The content of diene rubber in 100% by mass of the rubber component is preferably more than 80% by mass, more preferably more than 90% by mass, and most preferably 100% by mass.

[0081] (Tetrazine compound) Tetrazine compounds are a general term for compounds containing a tetrazine ring, and include tetrazine and its derivatives. Specifically, tetrazine compounds can be compounds represented by the following chemical formula (1) or salts thereof.

[0082] [ka] (In the formula, R 1 and R 2 Each of these independently represents a hydrogen atom, an alkyl group, an alkylthio group, an aralkyl group, an aryl group, an arylthio group, a heterocyclic group, or an amino group, and each of these groups may have one or more substituents.

[0083] The alkyl group may be linear, branched, or cyclic. Preferably, the alkyl group has 1 to 8 carbon atoms. More preferably, the alkyl group is a linear or branched alkyl group with 1 to 6 carbon atoms.

[0084] The alkylthio group may be linear, branched, or cyclic. Preferably, the alkylthio group has 1 to 8 carbon atoms. More preferably, the alkylthio group is a linear or branched alkylthio group with 1 to 6 carbon atoms.

[0085] Examples of aralkyl groups include benzyl, phenethyl, trityl, and 1-naphthylmethyl groups.

[0086] Examples of aryl groups include phenyl groups, biphenyl groups, and naphthyl groups.

[0087] Examples of arylthio groups include phenylthio groups, biphenylthio groups, and naphthylthio groups.

[0088] Examples of heterocyclic groups include nitrogen-containing heterocyclic groups such as pyridyl, pyrazinyl, pyrimidyl, pyridazyl, quinolyl, isoquinolyl, quinoxalinyl, quinazolinyl, phthalazinyl, tetrahydroquinolyl, pyrrolyl, imidazolyl, pyrazolyl, indolyl, benzimidazolyl, and indazolyl groups; oxygen-containing heterocyclic groups such as furyl, benzofuranyl, and isobenzofuranyl groups; sulfur-containing heterocyclic groups such as thienyl and benzothienyl groups; heterocyclic groups containing a nitrogen atom and an oxygen atom such as oxazolyl, isoxazolyl, and benzoxazolyl groups; and heterocyclic groups containing a nitrogen atom and a sulfur atom such as thiazolyl, isothiazolyl, and benzothiazolyl groups. Among these, heteroaromatic ring groups, which are aromatic heterocyclic groups, are preferred, and more preferably are pyridyl, pyrimidyl, pyrazinyl, pyrazolyl, furyl, or thienyl groups.

[0089] The amino group may be a primary amino group (-NH2), or a secondary or tertiary amino group having one or two hydrocarbon groups (preferably alkyl groups). In the case of a secondary or tertiary amino group, it is preferable that the total number of carbon atoms in the hydrocarbon groups is 15 or less.

[0090] Each of these alkyl groups, alkylthio groups, aralkyl groups, aryl groups, arylthio groups, heterocyclic groups, and amino groups may have one or more substituents. The substituents are not particularly limited and include, for example, halogen atoms, amino groups, aminoalkyl groups, alkoxycarbonyl groups, acyl groups, acyloxy groups, amide groups, carboxyl groups, carboxyalkyl groups, formyl groups, nitrile groups, nitro groups, alkyl groups, hydroxyalkyl groups, hydroxyl groups, alkoxy groups, aryl groups, aryloxy groups, heterocyclic groups, thiol groups, alkylthio groups, and arylthio groups. Preferably, there may be one to five substituents, and more preferably one to three substituents.

[0091] R 1 and R 2 A heterocyclic group is preferred, and among these, an aromatic heterocyclic group is more preferred.

[0092] The salts of the tetrazine compound represented by chemical formula (1) are not particularly limited and include, for example, inorganic acid salts such as hydrochloride, sulfate, and nitrate; organic acid salts such as acetate and methanesulfonate; alkali metal salts such as sodium and potassium salts; alkaline earth metal salts such as magnesium and calcium salts; and quaternary ammonium salts such as dimethylammonium and triethylammonium.

[0093] In one embodiment, the tetrazine compound is R in chemical formula (1). 1 and R 2 However, each is preferably independently an aryl group or a heterocyclic group, more preferably a heterocyclic group, even more preferably a nitrogen-containing heteroaromatic ring group, and even more preferably a pyridyl group or a thienyl group.

[0094] Specific examples of tetrazine compounds (1) include the following compounds. 3,6-Bis(2-pyridyl)-1,2,4,5-tetrazine, 3,6-Bis(3-pyridyl)-1,2,4,5-tetrazine, 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine, 3,6-Bis(2-Furanyl)-1,2,4,5-Tetradine, 3,6-bis(3,5-dimethyl-1-pyrazolyl)-1,2,4,5-tetrazine, 3,6-Bis(2-thienyl)-1,2,4,5-tetrazine, 3-methyl-6-(2-pyridyl)-1,2,4,5-tetrazine, 3,6-Bis(2-pyrimidinyl)-1,2,4,5-tetrazine, 3,6-Bis(2-pyrazyl)-1,2,4,5-tetrazine

[0095] ≪Content≫ The content of the tetrazine compound is 0.1 parts by mass or more and 5 parts by mass or less. Preferably, the content is more than 0.5 parts by mass, more preferably 0.6 parts by mass or more, even more preferably more than 1 part by mass, even more preferably more than 1.5 parts by mass, and even more preferably 2.0 parts by mass or more. On the other hand, preferably the content is less than 5.0 parts by mass, more preferably less than 4.5 parts by mass, and even more preferably 4.0 parts by mass or less.

[0096] ≪Formula (1)(A TET / A IR )≫ The content (parts by mass) of isoprene-based rubber in 100 parts by mass of the aforementioned rubber component is A IR The content (parts by mass) of the tetrazine compound is set to A TET In that case, A IR and A TET This satisfies equation (1) below. A TET / A IR >0.020 (1)

[0097] In equation (1), the value of the right-hand side is preferably 0.023, more preferably 0.030, even more preferably 0.040, even more preferably 0.050, even more preferably 0.060, and even more preferably 0.067, from the viewpoint of the effects of the present invention. TET / A IR There is no particular upper limit on the value of this parameter, but it is usually less than 1.000, or less than 0.500, or less than 0.200.

[0098] (Filler) The tire rubber composition of the present invention contains silica, and more preferably contains silica and carbon black.

[0099] Silica The aforementioned tire rubber composition contains silica as a filler. Suitable silica types include dry-process silica (anhydrous silica) and wet-process silica (hydrated silica). Among these, wet-process silica is preferred due to its higher silanol group content. Commercially available silica products from companies such as Degussa, Rhodia, Tosoh Silica, Solvay Japan, and Tokuyama Corporation can be used. These may be used individually or in combination of two or more types.

[0100] The nitrogen adsorption specific surface area (N2SA) of silica is preferably 50 m². 2 / g or more, more comfortably 150m 2 More than 175m / g, more preferably 175m 2 / g or more, more preferably 180m 2 It is greater than / g, and more preferably 210m 2 It is greater than / g. The upper limit of N2SA of silica is not particularly limited, but preferably 600m 2 Less than / g, more preferably less than 350m² / g, and even more preferably 260m 2 It is less than / g. Keeping it within the above range tends to improve wet grip performance. Note that the N2SA of silica is the value measured by the method described above.

[0101] The average primary particle diameter of silica is preferably less than 25 nm, more preferably less than 22 nm, even more preferably 17 nm or less, even more preferably less than 16 nm, and even more preferably 15 nm or less, from the viewpoint of reinforcing properties and low fuel consumption. The lower limit of the average primary particle diameter is not particularly limited, but is preferably greater than 3 nm, more preferably greater than 5 nm, and even more preferably greater than 10 nm. The average primary particle diameter of silica can be determined by the method described above.

[0102] The silica content (total amount of silica) is preferably 90 parts by mass or less per 100 parts by mass of rubber component. More preferably, the content is less than 85 parts by mass, even more preferably 83 parts by mass or less, and even more preferably 80 parts by mass or less. On the other hand, the content is preferably more than 35 parts by mass, more preferably more than 40 parts by mass, and even more preferably 50 parts by mass or more. Being within the above range tends to improve fuel efficiency and wet grip performance.

[0103] ≪Silane coupling agents≫ Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited, but examples include sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, Momentive's NXT-Z100, NXT-Z45, and NXT(3-octanoylthiopropyltriethoxysilane); vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-amino Examples of silane coupling agents include amino-based silane coupling agents such as ethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferred, and mercapto-based silane coupling agents are particularly preferred. These silane coupling agents may be used individually or in combination of two or more.

[0104] The mercapto-based silane coupling agent means a silane coupling agent having a mercapto group and a silane coupling agent in which the mercapto group is protected by a protecting group. The mercapto-based silane coupling agent is not particularly limited, and for example, it is at least one selected from the group consisting of a compound represented by the following chemical formula (2), a compound represented by the following chemical formula (3), and a compound containing a bonding unit A represented by the following chemical formula (4) and a bonding unit B represented by the following chemical formula (5). Among them, at least one of a compound represented by the following chemical formula (2) and a compound containing a bonding unit A represented by the following chemical formula (4) and a bonding unit B represented by the following chemical formula (5) is preferable, and a compound represented by the following chemical formula (2) is more preferable because the effects of the present invention can be exhibited more favorably.

[0105]

Chemical formula

[0106]

Chemical formula

[0107]

Chemical formula

Chemical formula

[0108] As the compound represented by chemical formula (2), R 1005 , R1006 , 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. 1004 Examples of R 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 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.

[0109] R in chemical formula (2) 1002 , R 1005 , R 1006 , R 1007 and R 1008Specific 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.

[0110] R in chemical formula (2) 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.

[0111] Specific examples of silane coupling agents represented by chemical formula (2) 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. Among these, 3-octanoylthiopropyltriethoxysilane is preferred.

[0112] The silane coupling agent represented by chemical formula (2) has a thioester structure (i.e., a protected mercapto group) within its molecule, exhibits low reactivity with rubber components up to high temperatures, can suppress the strong bonding between the rubber components, the silane coupling agent, and silica during mixing, and can appropriately disperse silica, thus tending to exhibit the effects of the present invention more effectively.

[0113] Examples of compounds represented by chemical formula (3) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the compound represented by the following chemical formula (6) (Si363 manufactured by Evonik Degussa). The compound represented by the following chemical formula (6) can be preferably used. These may be used individually or in combination of two or more. [ka]

[0114] Compounds containing the bonding unit A shown in chemical formula (4) and the bonding unit B shown in chemical formula (5) include, for example, those manufactured and sold by Momentive, Inc. These may be used individually or in combination of two or more types.

[0115] The content of the silane coupling agent relative to 100 parts by mass of silica (total amount when multiple silane coupling agents are used in combination) is preferably more than 1 part by mass, more preferably more than 3 parts by mass, even more preferably more than 5 parts by mass, and even more preferably more than 7 parts by mass, from the viewpoint of improving the dispersibility of silica. Furthermore, from the viewpoint of preventing a decrease in wear resistance, the content is preferably less than 20 parts by mass, more preferably less than 15 parts by mass, and even more preferably less than 12 parts by mass.

[0116] Carbon Black The carbon black used is not particularly limited; any carbon black usable in the tire industry can be used. Examples of such carbon blacks include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nippon Chemical Carbon Co., Ltd., and Columbia Carbon Corporation can be used. These can be used individually or in combination of two or more types.

[0117] The specific surface area (N2SA) of carbon black for nitrogen adsorption is 50 m². 2 Preferably more than / g, 70m 2 More preferably than / g, 90m 2 A value exceeding / g is even more preferable. Also, the above N2SA is 200m 2 Preferably less than / g, 150m 2 Less than / g is more preferable, 130m 2 A value of less than / g is even more preferable. Keeping it within the above range tends to improve fuel efficiency and wet grip performance. The specific surface area of ​​nitrogen adsorption of carbon black is determined by the method described above.

[0118] The average primary particle diameter of the carbon black is preferably less than 30 nm, more preferably less than 28 nm, and even more preferably less than 25 nm, from the viewpoint of reinforcing properties. The lower limit of the average primary particle diameter is not particularly limited, but is preferably greater than 10 nm, more preferably greater than 15 nm, and even more preferably greater than 20 nm. The average primary particle diameter of the carbon black can be determined by the method described above.

[0119] The carbon black content is preferably more than 1 part by mass, more preferably more than 3 parts by mass, and even more preferably 5 parts by mass or more, per 100 parts by mass of rubber component. The upper limit of the content is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 10 parts by mass. Keeping it within the above range tends to improve fuel efficiency and wet grip performance.

[0120] ≪Formula (5)(A CB / A SIL )≫ When a tire rubber composition contains silica and carbon black, the silica content (parts by mass) per 100 parts by mass of rubber component is A SIL The carbon black content (parts by mass) is set to A CB In that case, A SIL and A CB Preferably, the following equation (5) is satisfied. A CB / A SIL <1 (5)

[0121] The right-hand side of equation (5) above is preferably 0.5, more preferably 0.3, and even more preferably 0.1. On the other hand, A CB / A SIL There is no particular lower limit to the value of , but it may be greater than 0.01, for example.

[0122] <<Other fillers>> The tire rubber composition of the present invention may contain other fillers besides silica and carbon black. Such other fillers are not particularly limited, and materials known in the rubber field can be used, such as inorganic fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica.

[0123] ≪Filler content≫ From the viewpoint of the effects of the present invention, the content of the filler (total content of the filler) is preferably more than 30 parts by mass, more preferably more than 40 parts by mass, and even more preferably more than 50 parts by mass, per 100 parts by mass of the rubber component. The upper limit of this content is preferably less than 200 parts by mass, more preferably less than 150 parts by mass, even more preferably less than 120 parts by mass, and even more preferably less than 100 parts by mass.

[0124] (resin) The rubber composition for tires of the present invention may contain a resin. Examples of resins commonly used in the tire industry include petroleum resins, terpene resins, rosin resins, and phenolic resins. These resin components may be used individually or in combination of two or more.

[0125] ≪Petroleum resin≫ Examples of petroleum resins include C5-based petroleum resins, aromatic petroleum resins, and C5C9-based petroleum resins.

[0126] C5-based petroleum resins refer to resins obtained by polymerizing C5 fractions. Examples of C5 fractions include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferably used as a C5-based petroleum resin.

[0127] Aromatic petroleum resins refer to resins obtained by polymerizing C9 fractions, and may be hydrogenated or modified. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of aromatic petroleum resins that are suitably used include coumarone indene resin, coumarone resin, indene resin, and aromatic vinyl resins. For aromatic vinyl resins, homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene are preferred, and copolymers of α-methylstyrene and styrene are more preferred, due to their economical nature, ease of processing, and excellent heat generation properties. Aromatic vinyl resins that are commercially available from companies such as Kraton and Eastman Chemical can be used.

[0128] C5C9 petroleum resin refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified. Examples of the C5 and C9 fractions include the petroleum fractions mentioned above. As C5C9 petroleum resin, commercially available products from companies such as Tosoh Corporation and LUHUA can be used.

[0129] Terpene resins Examples of terpene resins include polyterpene resins consisting of at least one terpene compound selected from α-pinene, β-pinene, limonene, dipentene, etc.; aromatically modified terpene resins made from the terpene compound and an aromatic compound; terpene-phenol resins made from the terpene compound and a phenolic compound; and these terpene resins that have been hydrogenated (hydrogenated terpene resins). Examples of aromatic compounds used as raw materials for aromatically modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenolic compounds used as raw materials for terpene-phenol resins include phenol, bisphenol A, cresol, and xylenol.

[0130] ≪Rosin-based resin≫ Rosin-based resins are not particularly limited, but examples include natural resin rosin and rosin-modified resins obtained by hydrogenation, disproportionation, dimerization, esterification, etc.

[0131] Phenolic resins Phenolic resins are not particularly limited, but examples include phenol-formaldehyde resin, alkylphenol-formaldehyde resin, alkylphenol-acetylene resin, and oil-modified phenol-formaldehyde resin.

[0132] The content of the resin component relative to 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 3 parts by mass, even more preferably more than 4 parts by mass, and even more preferably 5 parts by mass or more. Furthermore, the content of the resin component is preferably less than 30 parts by mass, more preferably less than 25 parts by mass, and even more preferably less than 20 parts by mass.

[0133] (Plasticizer) The rubber composition for tires of the present invention may contain plasticizers other than the resin components described above. A plasticizer is a material that imparts plasticity to the rubber components, and the concept includes both liquid plasticizers at room temperature (25°C) and solid plasticizers at room temperature (25°C). Specific examples of plasticizers other than the resin components include oils, liquid polymers, ester-based plasticizers, and the like. Plasticizers other than the resin components may be used individually or in combination of two or more types.

[0134] ≪Oil≫ Examples of oils include process oils, vegetable oils, and animal fats. Examples of process oils include paraffinic process oils, naphthenic process oils, and aromatic process oils. Furthermore, for environmental reasons, process oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of low-PCA process oils include light extraction solvates (MES), processed distillate aromatic extracts (TDAEs), and heavy naphthenic oils. Additionally, from a life cycle assessment perspective, refined waste oil from rubber mixers and engines, or waste cooking oil used in restaurants, may be used. Oils may be used individually or in combination of two or more types.

[0135] Liquid polymer The liquid polymer is not particularly limited as long as it is a polymer that is in a liquid state at room temperature (25°C), but examples include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), liquid farnesene rubber, etc. The liquid polymer may be used alone or in combination of two or more types.

[0136] Ester-based plasticizers Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelaate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), and trixylenyl phosphate (TXP). Ester-based plasticizers may be used individually or in combination of two or more.

[0137] ≪Content≫ When plasticizers other than resin components are included, the content per 100 parts by mass of the rubber component (total amount if multiple plasticizers are used in combination) is preferably more than 1 part by mass, more preferably more than 2 parts by mass, and still more preferably more than 3 parts by mass. Furthermore, the content of the plasticizer is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, and still more preferably less than 30 parts by mass.

[0138] (Other compounding agents) The rubber composition for tires of the present invention may use other compounding agents such as wax, antioxidant, stearic acid, zinc oxide, vulcanizing agent, and vulcanization accelerator.

[0139] ≪Wax≫ The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used, such as petroleum-based waxes, mineral-based waxes, and synthetic waxes. Among these, petroleum-based waxes are preferred. Examples of petroleum-based waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. Waxes manufactured and sold by companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Paramelt Co., Ltd. can be used. One type of wax or a combination of two or more types can be used.

[0140] When wax is included, the content per 100 parts by mass of rubber component is preferably more than 0.3 parts by mass, more preferably more than 0.5 parts by mass, and even more preferably 1.0 part by mass or more. On the other hand, the content is preferably less than 4.0 parts by mass, more preferably less than 3.0 parts by mass, and even more preferably less than 2.0 parts by mass.

[0141] Anti-aging agent The antioxidant is not particularly limited, and any commonly used in the tire industry can be suitably used. Examples of antioxidants include quinoline-based antioxidants, quinone-based antioxidants, phenol-based antioxidants, phenylenediamine-based antioxidants, and metal carbamate salts. Among these, phenylenediamine-based antioxidants are preferred because they exhibit a better effect in improving ozone resistance.

[0142] When an anti-aging agent is included, its content per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 0.8 parts by mass, and even more preferably more than 1.0 part by mass. On the other hand, the content is preferably less than 7.0 parts by mass, more preferably less than 5.0 parts by mass, and even more preferably less than 3.0 parts by mass.

[0143] ≪Stearic Acid≫ When stearic acid is included, its content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 0.7 parts by mass, and even more preferably more than 1.0 part by mass, from the viewpoint of processability. On the other hand, from the viewpoint of vulcanization rate, the content is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, and even more preferably less than 3 parts by mass.

[0144] ≪Zinc Oxide≫ When zinc oxide is included, its content per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 0.7 parts by mass, and even more preferably more than 1 part by mass, from the viewpoint of processability. On the other hand, from the viewpoint of wear resistance, the content is preferably less than 10 parts by mass, more preferably less than 7 parts by mass, and even more preferably less than 5 parts by mass.

[0145] ≪Sulfurizing agent≫ The vulcanizing agent is not particularly limited, and known vulcanizing agents can be used, such as organic peroxides, sulfur-based vulcanizing agents, resin vulcanizing agents, and metal oxides such as magnesium oxide. Among these, sulfur-based vulcanizing agents are preferred. As sulfur-based vulcanizing agents, for example, sulfur, sulfur donors such as morpholine disulfide can be used. Among these, the use of sulfur is preferred. The vulcanizing agent can be used one or in combination of two or more types.

[0146] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur (oil-treated sulfur, special sulfur treated with dispersants, masterbatch-type sulfur, etc.), and insoluble sulfur (oil-treated insoluble sulfur, etc.), all of which can be suitably used. Among these, powdered sulfur is preferred. Sulfur can be used from, for example, products manufactured and sold by Tsurumi Chemical Industries, Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals, Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc.

[0147] When a vulcanizing agent is included, its content per 100 parts by mass of rubber component is preferably more than 0.4 parts by mass, more preferably more than 0.7 parts by mass, even more preferably 1.0 part by mass or more, and even more preferably more than 1.5 parts by mass. On the other hand, the content is preferably less than 6.0 parts by mass, more preferably less than 5.0 parts by mass, and even more preferably less than 3.0 parts by mass. When the vulcanizing agent content is within the above range, an appropriate reinforcing effect tends to be obtained, and the effects of the present invention tend to be exhibited more favorably. Note that if the vulcanizing agent contains components other than sulfur, such as oil-treated sulfur, the vulcanizing agent content refers to the content of the sulfur component itself.

[0148] <<Vulcanization accelerator>> The vulcanization accelerator is not particularly limited, and known vulcanization accelerators can be used, such as sulfenamide, thiazole, thiram, thiourea, guanidine, dithiocarbamate, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Among these, sulfenamide, thiram, and guanidine are preferred, with sulfenamide being more preferred. Vulcanization accelerators manufactured and sold by companies such as Ouchi Shinko Chemical Industry Co., Ltd. and Sanshin Chemical Industry Co., Ltd. can be used. These vulcanization accelerators can be used individually or in combination of two or more.

[0149] Examples of sulfenamide-based vulcanization accelerators include N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), and N,N'-dicyclohexyl-2-benzothiazolyl sulfenamide (DZ). Examples of thiuram-based vulcanization accelerators include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, and tetrabenzylthiuram disulfide (TBzTD). Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), diorthotolylguanidine, and orthotolylbiguanidine.

[0150] The content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 2.0 parts by mass. On the other hand, the content is preferably less than 8.0 parts by mass, more preferably less than 6.0 parts by mass, and even more preferably less than 5.0 parts by mass. When the content of the vulcanization accelerator is within the above range, fracture strength and elongation tend to be ensured, and the effects of the present invention tend to be exhibited more favorably.

[0151] (Equation (2) (30℃tanδ), Equation (3) (0℃tanδ / 30℃tanδ)) In the present invention, when the loss tangent at 30°C is 30°Ctanδ and the loss tangent at 0°C is 0°Ctanδ, the tire rubber composition satisfies the following equations (2) and (3). 30℃ tanδ ≤ 0.15 (2) 0°C tanδ / 30°C tanδ > 2.0 (3)

[0152] In equation (2) above, the value on the right-hand side is preferably 0.14. On the other hand, there are no particular restrictions on the lower limit of tanδ at 30°C from the viewpoint of the effects of the present invention, but it is usually around 0.08.

[0153] In the above formula (3), the value of the right-hand side is preferably 2.3, more preferably 2.6, even more preferably 2.9, even more preferably 3.0, and even more preferably 3.1. On the other hand, there is no particular upper limit to 0°C tanδ / 30°C tanδ from the viewpoint of the effects of the present invention, but it is usually around 4.0.

[0154] The values ​​of 0°C tanδ and 30°C tanδ can be adjusted by conventional methods in the tire industry. Specifically, they can be adjusted by changing the type and amount of chemicals (e.g., rubber components, fillers, softeners, sulfur, vulcanization accelerators, silane coupling agents, etc.) blended into the tire rubber composition. For example, the values ​​of 0°C tanδ and 30°C tanδ can be reduced by decreasing the content of silica or aromatic petroleum resins, and conversely, the values ​​of 0°C tanδ and 30°C tanδ can be increased by increasing their content. Therefore, those skilled in the art can appropriately adjust the values ​​of 0°C tanδ and 30°C tanδ according to the target value of 30°C tanδ and the 0°C tanδ / 30°C tanδ ratio.

[0155] <Tires> The tire of the present invention will be described below with reference to the drawings as appropriate. However, the drawings are for illustrative purposes only. The tire of the present invention is a tire having a tread made of the above-mentioned tire rubber composition.

[0156] (Formula (6)(G / WL)) In the present invention, when the maximum load capacity of the tire is WL (kg) and the weight of the tire is G (kg), it is preferable that WL and G satisfy the following equation (6). G / WL ≤ 0.012 (6)

[0157] The tire of the present invention that satisfies formula (6) above is a relatively lightweight tire in which the tire weight is limited based on the maximum load capacity. The right-hand side of formula (6) is more preferably 0.011, even more preferably 0.010, and even more preferably 0.009. On the other hand, there are no particular restrictions on the lower limit of G / WL from the viewpoint of the effects of the present invention, but it is usually around 0.008.

[0158] The G / WL ratio can be decreased by reducing the value of G relative to the value of WL, and conversely, it can be increased by increasing the value of G relative to the value of WL.

[0159] (Formula (7)(A SBR ×B)) In the present invention, when the land ratio (%) of the tread contact surface of the tire's tread is B, A SBR It is preferable that B and satisfy the following equation (7). A SBR ×B>25.0 (7)

[0160] The land ratio B is the ratio of the contact surface area to the total surface area of ​​the tread contact surface when a tire in a normal state is subjected to a normal load, with a camber angle of 0 degrees, and making contact with a flat surface, assuming all grooves are filled. It can be obtained by applying ink to the tread surface and pressing it onto cardboard. Figure 2 schematically represents the tread contact surface. The enclosed area in the figure is the tread contact surface.

[0161] In the above formula (7), the value of the right-hand side is preferably 28.0, more preferably 30.0, even more preferably 32.0, and even more preferably 33.0. On the other hand, A SBR Regarding the upper limit of the value of ×B, there are no particular restrictions from the viewpoint of the effects of the present invention, but it is usually around 70.0, and may also be around 60.0.

[0162] The land ratio B is preferably 0.50 or higher, more preferably greater than 0.60, and even more preferably 0.64 or higher, from the viewpoint of grip performance and wear resistance. On the other hand, the land ratio R is preferably less than 0.80, more preferably 0.75 or lower, and even more preferably less than 0.70, from the viewpoint of grip performance.

[0163] (Circumferential grooves, transverse grooves) Preferably, the tread surface has one or more circumferential grooves extending continuously in the tire circumferential direction and a land area partitioned by the circumferential grooves, the land area has transverse grooves extending toward the radially inward direction of the tire, and the transverse grooves have a portion in which the groove width is wider than the groove width on the tread surface in a cross section perpendicular to the extension direction.

[0164] The circumferential grooves may extend in a straight line or in a zigzag pattern. Furthermore, while there may be one or more circumferential grooves, having two or more divides the tread into at least one pair of shoulder tread sections and a center tread section sandwiched between them. Having three or more circumferential grooves further divides the center tread into a section that faces the inside of the vehicle and a section that faces the outside when mounted on the vehicle. This allows for different tread patterns in each section, which is preferable as it increases the design flexibility of the tread pattern. The number of circumferential grooves may be four or more, or even five or more.

[0165] Preferably, the lateral grooves extend inward in the tire radial direction, and have a portion (widened portion) in a cross section perpendicular to the extension direction where the groove width is wider than the groove width on the tread surface. It is believed that having such a configuration can suppress the increase in compressive stiffness even as wear progresses, thereby ensuring wet grip performance. The width of the lateral grooves is not particularly limited, but is usually 8 mm or less. Also, grooves with a width of less than 2 mm are sometimes distinguished from grooves as sipes, but the lateral grooves of the present invention also include grooves with a width of less than 2 mm. The direction of the lateral grooves may have a predetermined angle (θ) with respect to the tire width direction. The range of θ is, for example, 0° to ±80°. For a single lateral groove, θ may be constant at any position in the tire width direction, or θ may change according to the displacement of the position in the tire width direction. At least one end of the lateral groove may communicate with the circumferential groove, or both ends may communicate with the circumferential groove, or they may not communicate with it.

[0166] Figure 3 shows the tread pattern of a tire according to one embodiment of the present invention. In the figure, the tread surface has three circumferential grooves that extend continuously in the circumferential direction of the tire. The central circumferential groove 11 extends in a zigzag pattern. The pair of circumferential grooves 12 located on either side of it extend in a straight line. These circumferential grooves demarcate a pair of center land sections 21 and a pair of shoulder land sections 22. The center land section 21 has a lateral groove 31 that extends inward in the radial direction of the tire, and the shoulder land sections 22 have a lateral groove 32 that extends inward in the radial direction of the tire. In a cross section perpendicular to the extension direction, the lateral groove 31 has a widened section in which the groove width gradually widens compared to the groove width on the tread surface, and is widened to its maximum at the bottom of the groove. On the other hand, the lateral groove 32 has a constant groove width in a cross section perpendicular to the extension direction. Neither end of the lateral groove 31 communicates with the circumferential grooves. On the other hand, one end of the lateral groove 32 communicates with the circumferential groove, and the other end extends to the tread contact edge Te.

[0167] (Grove bottom gauge) The groove bottom gauge of the tread is preferably 1 mm or more and 4 mm or less. The groove bottom gauge is the thickness of the rubber from the deepest part of the circumferential groove to the cord of the belt layer (or the cord of the belt protection layer if the belt protection layer has cords), and in the case of multiple grooves, it is the thickness of the rubber that is the maximum. It is preferable to set the groove bottom gauge within the above range because it is thought that heat generation can be suppressed and contribute to improved fuel efficiency. The groove bottom gauge is preferably 2 mm or more, and more preferably 3 mm or more.

[0168] Figure 4 schematically shows a portion of a cross-sectional view of a tire according to one embodiment of the present invention. The tire 100 has a tread 200, a band 300 positioned radially inward of the tread, and a two-layer belt layer 400 positioned further inward. Each of the belt layers 400 has a belt cord 500. The thickness of the rubber from the deepest part of the circumferential groove to the belt cord 500 is represented as the groove bottom gauge D1.

[0169] (Shape of the circumferential grooves in the center region) The tread surface of the tread has one or more circumferential grooves that extend continuously in the circumferential direction of the tire, and when the area of ​​the tread surface with the tire equator as the center is defined as 30% of the tread contact width, it is preferable that at least one of the circumferential grooves in the center area is zigzag-shaped. It is believed that the zigzag shape of at least one of the circumferential grooves in the center area enhances the heat dissipation effect by the airflow through the circumferential groove, thereby improving durability and contributing to wear resistance. Here, zigzag shape means that the center in the width direction of the circumferential groove extends in the circumferential direction of the tire while oscillating in the width direction of the tire. Therefore, in addition to a form in which straight grooves repeatedly bend, it also includes a form in which curved grooves repeatedly curve in a wave-like manner.

[0170] A zigzag circumferential groove is said to exist in the center region if more than half of the groove is located within the center region. In other words, if the areas on both sides of the center region, within the tread contact width, are considered a pair of shoulder regions, even if a circumferential groove spans both the center region and the shoulder region simultaneously, if more than half of the groove is located within the center region, it is considered a circumferential groove located within the center region.

[0171] In Figure 3, the circumferential grooves 11 are located within the center region of the tread surface, which is 30% of the tread contact width centered on the tire equator, and their shape is a zigzag pattern in which straight grooves repeatedly bend.

[0172] (Groove depth of circumferential grooves in the shoulder region) In the aforementioned tread surface, the area 30% of the tread contact width centered on the tire equator is defined as the center area, and the areas on both outer sides of the center area and within the tread contact width are defined as a pair of shoulder areas. In such cases, it is preferable that the groove depth of the deepest part of the circumferential grooves in the shoulder areas is 10 mm or more. This configuration is thought to improve drainage and thus contribute to improved wet grip performance. Here, the circumferential grooves in the shoulder areas are the circumferential grooves on the tread surface other than the circumferential grooves in the center area described above. That is, the circumferential grooves in the shoulder areas are those where more than half of the groove is located in the shoulder area, even if the groove spans both the center area and the shoulder area simultaneously. Furthermore, the groove depth of the deepest part of the circumferential grooves in the shoulder areas refers to the groove depth of the circumferential groove with the deepest groove depth if there are multiple circumferential grooves in the shoulder area.

[0173] The groove depth at the deepest part of the circumferential groove in the shoulder region is preferably 11 mm or more, and more preferably 12 mm or more.

[0174] In Figure 4, the groove depth at the deepest part of the circumferential groove in the shoulder region is represented by D2.

[0175] <Manufacturing> The rubber composition according to the present invention can be manufactured by known methods. For example, it can be manufactured by kneading each of the above components using a rubber kneading device such as an open roll or a closed kneader (Banbury mixer, kneader, etc.).

[0176] The mixing process includes, for example, a base mixing process in which compounding agents and additives other than the vulcanizing agent and vulcanization accelerator are mixed, and a final mixing (F mixing) process in which the vulcanizing agent and vulcanization accelerator are added to the mixture obtained in the base mixing process and mixed. Furthermore, the base mixing process can be divided into multiple processes as desired.

[0177] There are no particular limitations on the mixing conditions, but for example, in the base mixing process, mixing is performed at a discharge temperature of 150-170°C for 3-10 minutes, and in the final mixing process, mixing is performed at 70-110°C for 1-5 minutes. There are no particular limitations on the vulcanization conditions, but for example, vulcanization is performed at 150-200°C for 10-30 minutes.

[0178] The tire of the present invention can be manufactured by conventional methods using the rubber composition described above. Specifically, an unvulcanized rubber composition, in which the above components are blended with the rubber component as needed, is extruded in an extruder equipped with a die of a predetermined shape to match the shape of the rubber layer constituting the tread surface of the tread portion. This unvulcanized tire is then bonded together with other tire components on a tire molding machine and molded in conventional methods to form an unvulcanized tire. This unvulcanized tire is then heated and pressurized in a vulcanizing machine to manufacture the tire. The vulcanization conditions are not particularly limited, but for example, a method of vulcanization at 150 to 200°C for 10 to 30 minutes can be used.

[0179] <Application> Tires include pneumatic tires and non-pneumatic tires. Of these, pneumatic tires are preferred. The tires can be used for passenger cars, large passenger cars, large SUVs, heavy-duty trucks and buses, light trucks, motorcycles, and racing tires (high-performance tires). Among these, they are particularly suitable for use in passenger cars. [Examples]

[0180] The following examples (case studies) are shown as preferred for implementation, but the scope of the present invention is not limited to these examples. The results of examining tires obtained using the various chemicals shown below, according to each table, and calculating them based on the evaluation method described below, are shown at the bottom of each table.

[0181] <Various chemicals> The chemicals used in the examples and comparative examples are summarized below.

[0182] IR-type rubber: Natural rubber (TSR20) SBR: HPR850 manufactured by JSR Corporation (styrene content 27.5% by mass, vinyl bond content 59.0% by mass) BR: Ubepol BR150B manufactured by Ube Industries, Ltd. (Cis content 98% by mass, vinyl bond content 1% by mass) Carbon black: Seest N220 (N2SA114m) manufactured by Mitsubishi Chemical Corporation. 2 / g, average primary particle diameter 23nm) Silica 1: Evonik Degussa's UltraSil VN3 (N2SA175m 2 / g, average primary particle diameter: 17nm) Silica 2: Evonik Degussa's UltraSil 9100GR (N2SA235m 2 / g, average primary particle diameter: 15nm) Silane coupling agent 1: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa. Silane coupling agent 2: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Oil: Diana Process NH-70S (aroma-type process oil) manufactured by Idemitsu Kosan Co., Ltd. Tetrazine compound 1: 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (manufactured by Tokyo Chemical Industry Co., Ltd.) Tetrazine compound 2: 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine (manufactured by Tokyo Chemical Industry Co., Ltd.) Tetrazine compound 3: 3,6-bis(2-thienyl)-1,2,4,5-tetrazine (manufactured by Tokyo Chemical Industry Co., Ltd.) Resin: SYLVARES SA85 manufactured by Arizona Chemical (a copolymer of α-methylstyrene and styrene, Tg 43°C, softening point 85°C) Wax: Ozo Ace wax manufactured by Nippon Seiro Co., Ltd. Anti-aging agent: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: Beads of stearic acid manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator 1: Noxellar NS (N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noxellar D (N,N'-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0183] <Manufacturing of unvulcanized rubber composition> According to the formulation shown in Table 1, the chemicals other than sulfur and vulcanization accelerator are mixed in a 1.7L Banbury mixer at 150°C for 3 minutes to obtain a mixture. Sulfur and vulcanization accelerator are added to the mixture and kneaded in an open roll at 100°C for 2 minutes to obtain an unvulcanized rubber composition.

[0184] <Manufacturing of vulcanized rubber composition> Each of the obtained unvulcanized rubber compositions is vulcanized at 170°C for 15 minutes to obtain a vulcanized rubber composition.

[0185] <Manufacturing of test tires> According to Tables 2 and 3, each of the obtained unvulcanized rubber compositions was molded into the shape of a tread, bonded together with other tire components, and vulcanized at 170°C for 15 minutes to obtain a test tire (tire size: 195 / 65R15).

[0186] <30℃ tanδ> A sample measuring 20 mm in length, 4 mm in width, and 1 mm in thickness was taken from the rubber layer of the tread of each test tire, with the tire circumference as the longer side. The loss tangent was measured using a GABO iplexer series under the conditions of a temperature of 30°C, initial strain of 5%, dynamic strain of 1%, frequency of 10 Hz, and extension mode. The thickness direction of the sample was the tire radius direction.

[0187] <0℃tanδ> Samples with a length of 20 mm, a width of 4 mm, and a thickness of 1 mm are taken from the inside of the rubber layer of the tread of each test tire, with the tire circumferential direction being the long side. Using an Iplexer series manufactured by GABO, the loss tangent is measured under the conditions of a temperature of 0 °C, an initial strain of 10%, a dynamic strain of 2.5%, a frequency of 10 Hz, and an elongation mode. The thickness direction of the sample is the tire radial direction.

[0188] <Low fuel consumption performance> Using a rolling resistance tester, the rolling resistance of each test tire when running at a rim (15×6JJ), an internal pressure (230 kPa), a load (4.82 kN), and a speed (80 km / h) is measured and expressed as an index with the reference example being 100. The larger the index, the better the low fuel consumption performance.

[0189] <Wear resistance performance> The vulcanized rubber composition obtained above is cut into a predetermined size to obtain a vulcanized rubber test piece. Using a LAT tester (Laboratory Abration and Skid Tester), the volume loss amount of each vulcanized rubber test piece is measured under the conditions of a load of 100 N, a speed of 20 km / h, and a slip angle of 6°, and is expressed as an index based on the following formula. The larger the index, the better the wear resistance performance. Wear resistance performance = (Volume loss amount of the reference example) / (Volume loss amount of each example or each comparative example) × 100

[0190] <Wet grip performance> Each test tire is mounted on all wheels of a vehicle (domestic FF2000CC), and the braking distance from an initial speed of 100 km / h is obtained on a wet asphalt road surface. The result of the reference example is represented as an index with 100. The larger the index, the better the wet skid performance (wet grip performance).

[0191] <Comprehensive performance> The sum of the low fuel consumption performance index, the wear resistance performance index, and the wet grip performance index is used as the comprehensive performance index, and the comprehensive performance of these performances is evaluated based on this comprehensive performance index.

[0192]

Table 1

[0193] [Table 2]

[0194] [Table 3]

[0195] <Embodiment> Preferred embodiments are shown below.

[0196] [1] A tire rubber composition comprising, per 100 parts by mass of rubber component, silica and tetrazine compound in an amount of 0.1 parts by mass or more and less than 5.0 parts by mass, preferably more than 0.5 parts by mass and less than 4.5 parts by mass, more preferably 0.6 parts by mass or more and 4.0 parts by mass or less, even more preferably more than 1.0 parts by mass and 4.0 parts by mass or less, even more preferably more than 1.5 parts by mass and 4.0 parts by mass or less, and even more preferably 2.0 parts by mass or more and 4.0 parts by mass or less, The rubber component comprises more than 25% by mass of isoprene rubber, preferably 26% by mass or more, more preferably more than 28% by mass, even more preferably more than 30% by mass, more than 50% by mass of styrene-butadiene rubber, preferably 52% by mass or more, more preferably more than 55% by mass, even more preferably more than 60% by mass, and butadiene rubber. The content (parts by mass) of isoprene-based rubber in 100 parts by mass of the aforementioned rubber component is A IR The content (parts by mass) of the tetrazine compound is set to A TET In that case, A IR and A TET The following equation (1) is satisfied, preferably the value of the right-hand side of equation (1) is 0.023, more preferably 0.030, and still more preferably 0.040. The tire rubber composition wherein, when the loss tangent at 30°C is 30°Ctanδ and the loss tangent at 0°C is 0°Ctanδ, 30°Ctanδ and 0°Ctanδ satisfy the following equations (2) and (3), preferably the value of the right-hand side of equation (2) is 0.14, preferably the value of the right-hand side of equation (3) is 2.3, more preferably 2.6, and even more preferably 2.9. A TET / A IR >0.020 (1) 30℃ tanδ ≤ 0.15 (2) 0°C tanδ / 30°C tanδ > 2.0 (3) [2] The tire rubber composition according to [1] above, wherein the right-hand side of formula (1) is 0.050, preferably 0.060, and more preferably 0.067. [3] The tire rubber composition according to [1] or [2] above, wherein the right-hand side of formula (3) is 3.0, preferably 3.1. [4] The amount of styrene-butadiene rubber in 100 parts by mass of rubber component (parts by mass) is A SBR The content of the butadiene rubber is set to A BR In that case, A IR and A SBR and A BR A tire rubber composition according to any one of the above items [1] to [3], wherein the following formula (4) is satisfied. A SBR >A IR >A BR (4) [5] The tire rubber composition according to any one of the above [1] to [4], wherein the silica content is 90 parts by mass or less, preferably less than 85 parts by mass, more preferably 83 parts by mass or less, and even more preferably 80 parts by mass or less, per 100 parts by mass of the rubber component. [6] The tire rubber composition according to any one of the above [1] to [5], wherein the silica has an average primary particle diameter of 17 nm or less, preferably less than 16 nm, and more preferably 15 nm or less. [7] The tire rubber composition contains carbon black, The silica content (parts by mass) per 100 parts by mass of rubber component is A SILThe carbon black content (parts by mass) per 100 parts by mass of rubber component is set to A CB In that case, A SIL and A CB A tire rubber composition according to any one of the above [1] to [6], wherein the following formula (5) is satisfied, and preferably the value of the right-hand side of formula (5) is 0.5, more preferably 0.3, and even more preferably 0.1. A CB / A SIL <1 (5) [8] The tire rubber composition according to any one of the above [1] to [7], wherein the tire rubber composition comprises a mercapto-silane coupling agent. [9] A tire having a tread made of the tire rubber composition described in any one of the above items [1] to [8].

[10] The tire according to [9] above, wherein the maximum load capacity of the tire is WL (kg) and the weight of the tire is G (kg), and WL and G satisfy the following equation (6), preferably the value of the right-hand side of equation (6) is 0.011, more preferably 0.010, and even more preferably 0.009. G / WL ≤ 0.012 (6)

[11] When the land ratio (%) of the tread contact surface of the tread is B, A SBR The tire according to [9] or

[10] above, wherein B and B satisfy the following equation (7), preferably the value of the right-hand side is 28.0, more preferably 30.0, even more preferably 32.0, and even more preferably 33.0. A SBR ×B>25.0 (7)

[12] The tread surface of the tread has one or more circumferential grooves that extend continuously in the circumferential direction of the tire, and land portions partitioned by the circumferential grooves, The aforementioned land portion has transverse grooves extending inward in the radial direction of the tire. The tire according to any one of the above [9] to

[11] , wherein the lateral groove has a portion in a cross section perpendicular to the extending direction in which the groove width is wider than the groove width on the tread surface. The tire according to any one of [9] to

[12] above, wherein the groove bottom gauge of the tread is 1 mm or more and 4 mm or less, preferably 2 mm or more and 4 mm or less, more preferably 3 mm or more and 4 mm or less.

[14] The tread surface of the tread has one or more circumferential grooves that continuously extend in the tire circumferential direction, When a region of 30% of the tread contact width is defined as the center region with the tire equator as the center on the tread surface, at least one of the circumferential grooves present in the center region is zigzag. The tire according to any one of [9] to

[13] above.

[15] When a region of 30% of the tread contact width is defined as the center region with the tire equator as the center on the tread surface, and regions on both outer sides of the center region and within the tread contact width are defined as a pair of shoulder regions, the groove depth at the deepest part of the circumferential groove present in the shoulder region is 10 mm or more, preferably 11 mm or more, more preferably 12 mm or more. The tire according to any one of [9] to

[14] above.

Explanation of Symbols

[0197] Wt Tire section width Ht Tire section height Dt Tire outer diameter EP Tire equatorial plane TW Tread contact width CR Center region SR Shoulder region Te Tread contact end 11 Circumferential groove 12 Circumferential groove 21 Center land 22 Shoulder land 31 Transverse groove 32 Transverse groove 100 Tire 200 Tread 300 Band 400 Belt layer 500 Belt cord D1 Groove bottom gauge D2 Groove depth R Rim

Claims

1. A tire having a tread made of a tire rubber composition containing 0.1 to 5 parts by mass of silica and a tetrazine compound per 100 parts by mass of rubber component, The rubber component comprises more than 25% by mass of isoprene rubber, more than 50% by mass of styrene-butadiene rubber, and butadiene rubber. The content (parts by mass) of isoprene-based rubber in 100 parts by mass of the aforementioned rubber component is A IR The content (parts by mass) of the tetrazine compound is set to A TET In that case, A IR and A TET and satisfy the following equation (1), When the loss tangent of the tire rubber composition at 30°C is 30°C tanδ and the loss tangent at 0°C is 0°C tanδ, then 30°C tanδ and 0°C tanδ satisfy the following equations (2) and (3). Let WL (kg) be the maximum load capacity of the tire and G (kg) be the weight of the tire. The tire is such that WL and G satisfy the following equation (6). A TET / A IR >0.020 (1) 30℃ tanδ ≤ 0.15 (2) 0℃tanδ / 30℃tanδ>2.0 (3) G / WL≦0.012 (6)

2. The tire according to claim 1, wherein the right-hand side of formula (1) is 0.

050.

3. The tire according to claim 1 or 2, wherein the right-hand side of formula (3) is 3.

0.

4. Let the content (parts by mass) of the styrene-butadiene rubber in 100 parts by mass of the rubber component be A SBR and let the content of the butadiene rubber be A BR When doing so, the tire according to claim 1 or 2, wherein A IR and A SBR and A BR satisfy the following formula (4). A SBR >A IR >A BR (4)

5. The tire according to claim 1 or 2, wherein the silica content is 90 parts by mass or less per 100 parts by mass of rubber component.

6. The tire according to claim 1 or 2, comprising silica with an average primary particle diameter of 17 nm or less.

7. The aforementioned tire rubber composition contains carbon black, The silica content (parts by mass) per 100 parts by mass of rubber component is A SIL The carbon black content (parts by mass) relative to 100 parts by mass of rubber component is set to A CB In that case, A SIL and A CB The tire according to claim 1 or 2, wherein the following equation (5) is satisfied. A CB / A SIL <1 (5)

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

9. The tire according to claim 1 or 2, wherein the right-hand side of formula (2) is 0.

14.

10. The tire according to claim 1 or 2, wherein the right-hand side of formula (6) is 0.

011.

11. When the land ratio (%) of the tread contact surface of the tread is B, A SBR The tire according to claim 4, wherein B and B satisfy the following equation (7). A SBR ×B>25.0 (7)

12. The tread surface of the tread has one or more circumferential grooves that extend continuously in the circumferential direction of the tire, and land areas partitioned by the circumferential grooves, The aforementioned land portion has transverse grooves extending inward in the radial direction of the tire. The tire according to claim 1 or 2, wherein the lateral groove has a portion in a cross section perpendicular to the extending direction in which the groove width is wider than the groove width on the tread surface.

13. The tire according to claim 1 or 2, wherein the groove bottom gauge of the tread is 1 mm or more and 4 mm or less.

14. The tread surface of the tread has one or more circumferential grooves that extend continuously in the circumferential direction of the tire. The tire according to claim 1 or 2, wherein, when the tread surface is defined as a center region with respect to the tire equator and a region of 30% of the tread contact width, at least one of the circumferential grooves in the center region is zigzag-shaped.

15. The tire according to claim 1 or 2, wherein, on the tread surface of the tread, a region with the tire equator as the center and 30% of the tread contact width is defined as the center region, and the regions on both outer sides of the center region and within the tread contact width are defined as a pair of shoulder regions, and the groove depth of the deepest part of the circumferential grooves in the shoulder regions is 10 mm or more.

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