tire

Abstract

To provide a tire in which the total performance of the grip performance in the time of straight travel under a high-speed travel condition and the grip performance in the time of cornering is improved.SOLUTION: A tire includes a tread part whose mounting direction to a vehicle is designated. The tread part includes an inner side tread rubber layer which constitutes a vehicle inner end side in the time of mounting to the vehicle; and an outer side tread rubber layer which constitutes a vehicle outer end side. A ratio (D / WL) of a distance D to an interface between the inner side tread rubber layer and the outer side tread rubber layer from a vehicle outer ground contact end to a distance WL between both ground contact ends is equal to or greater than 0.50. An average value tanδAin of a loss tangent tanδ at 0°C to 50°C of the inner side tread rubber layer measured under a condition of 10 Hz of a frequency, 1% of an initial strain and ±0.1% of an amplitude is equal to or less than 0.30. An average value tanδAout of the loss tangent tanδ at 0°C to 50°C of the outer side tread rubber layer measured under a condition of 10 Hz of the frequency, 1% of the initial strain and ±0.1% of the amplitude is equal to or greater than 0.40.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to tires. [Background technology]

[0002] Pneumatic tires are required to have both good grip performance when traveling straight and when cornering. Patent Document 1 discloses a rubber composition for tire treads that contains a specific carbon black and has excellent grip performance from the initial stage of driving and peak grip performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-158662 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a tire that has improved overall performance in terms of grip performance when traveling straight and grip performance when cornering under high-speed driving conditions. [Means for solving the problem]

[0005] As a result of extensive investigation, it was found that the above-mentioned problems can be solved by dividing the tread portion in the tire width direction in a tire having a tread portion whose mounting direction on a vehicle is specified, and setting the widths of an inner tread rubber layer that forms the vehicle inner end side when mounted on a vehicle and an outer tread rubber layer that forms the vehicle outer end side and the average value of each loss tangent tanδ within predetermined ranges.

[0006] That is, the present disclosure provides a tire having a tread portion whose mounting direction on a vehicle is specified, and the tread portion has an inner tread rubber layer that forms the vehicle inner end side when mounted on the vehicle, and an outer tread rubber layer that forms the vehicle outer end side, and the distance W between both ground contact ends is L The ratio of the distance D from the outer contact edge of the vehicle to the interface between the inner tread rubber layer and the outer tread rubber layer (D / W L ) is 0.50 or more, and the average value tanδA of the loss tangent tanδ of the inner tread rubber layer at 0°C to 50°C measured under the conditions of a frequency of 10Hz, an initial strain of 1%, and an amplitude of ±0.1% in is 0.30 or less, and the average value tanδA of the loss tangent tanδ of the outer tread rubber layer at 0°C to 50°C measured under the conditions of a frequency of 10Hz, an initial strain of 1%, and an amplitude of ±0.1% out The present invention relates to a tire having a tensile strength of 0.40 or more. [Effects of the Invention]

[0007] According to the present disclosure, a tire is provided that has improved overall performance in terms of grip performance when traveling straight and grip performance when cornering under high-speed driving conditions. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a tire according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] A tire according to one embodiment of the present disclosure has a tread portion whose mounting direction on a vehicle is specified, and the tread portion has an inner tread rubber layer that forms an end side on the inner side of the vehicle when mounted on the vehicle, and an outer tread rubber layer that forms an end side on the outer side of the vehicle, and the distance W between both ground contact ends is L The ratio of the distance D from the outer contact edge of the vehicle to the interface between the inner tread rubber layer and the outer tread rubber layer (D / W L) is 0.50 or more, and the average value tanδA of the loss tangent tanδ of the inner tread rubber layer at 0°C to 50°C measured under the conditions of a frequency of 10Hz, an initial strain of 1%, and an amplitude of ±0.1% in is 0.30 or less, and the average value tanδA of the loss tangent tanδ of the outer tread rubber layer at 0°C to 50°C measured under the conditions of a frequency of 10Hz, an initial strain of 1%, and an amplitude of ±0.1% out is 0.40 or more.

[0010] When the widths of the inner tread rubber layer constituting the vehicle inner end side and the outer tread rubber layer constituting the vehicle outer end side when mounted on a vehicle and the average value of the loss tangent tanδ of each satisfy the above requirements, the tire obtained has improved overall performance in terms of grip performance when traveling straight and grip performance when cornering under high-speed driving conditions. The reason for this is thought to be as follows, without intending to be bound by theory.

[0011] When driving straight at high speeds, the inside of the vehicle makes contact with the road surface widely. Therefore, when driving at high speeds where the tire surface temperature exceeds 60°C, if tan δ is high, the rubber heats up, reducing rigidity and reducing grip performance in the circumferential direction of the tire. Therefore, the tan δA of the inner tread rubber layer in It is believed that by making this smaller than a predetermined value, it is possible to improve grip performance when traveling straight.

[0012] On the other hand, when cornering at high speeds, the outer side of the vehicle mainly comes into contact with the ground. Since a lateral force of 1G or more is applied to the tire when cornering at high speeds, it is necessary to ensure grip performance in the tire width direction while cornering by increasing tanδ in the temperature range that matches the tire temperature, causing the rubber to heat up and reduce rigidity, and improving the ability to follow the road surface. Therefore, the average value of the loss tangent tanδ of the outer tread rubber layer from 0°C to 50°C, tanδA out It is believed that grip performance during cornering can be improved by making it larger than a predetermined value.

[0013] Furthermore, by having the outer tread rubber layer account for 50% or more of the tread contact width, the outer tread rubber layer partially contacts the ground during straight-line braking, providing better adhesion, which, combined with the high rigidity of the inner tread rubber layer, facilitates deceleration. Furthermore, when cornering, when the outer tread rubber layer is more likely to contact the ground, the outer tread rubber layer compound, which partially heats up during straight-line driving and has reduced rigidity, conforms to the road surface, allowing for enhanced grip performance against lateral forces from the beginning of cornering. In this way, the width of the outer tread rubber layer and the aforementioned physical properties of the inner tread rubber layer and outer tread rubber layer work together to achieve the remarkable effect of more effectively improving grip performance during straight-line driving and cornering.

[0014] The rubber composition constituting the outer tread rubber layer preferably contains 100 parts by mass or more of carbon black per 100 parts by mass of the rubber component, from the viewpoint of facilitating heat buildup during cornering and straight running.

[0015] The rubber composition constituting the outer tread rubber layer preferably contains 70 parts by mass or more of a softener per 100 parts by mass of the rubber component, from the viewpoint of road-following ability during cornering.

[0016] The rubber composition constituting the outer tread rubber layer preferably contains an aromatic petroleum resin from the viewpoint of generating adhesion to the road surface during cornering and improving grip performance.

[0017] The rubber composition constituting the inner tread rubber layer preferably contains 40 parts by mass or more of silica per 100 parts by mass of the rubber component, from the viewpoint of ensuring rigidity during straight running.

[0018] The groove area ratio of the ground contact surface of the outer tread rubber layer is preferably smaller than the groove area ratio of the ground contact surface of the inner tread rubber layer, and the difference between the groove area ratio of the ground contact surface of the outer tread rubber layer and the groove area ratio of the ground contact surface of the inner tread rubber layer is preferably 2% to 10%.

[0019] By making the groove area ratio of the contact surface of the outer tread rubber layer smaller than the groove area ratio of the contact surface of the inner tread rubber layer, the rigidity toward the outside of the vehicle becomes greater than that toward the inside of the vehicle, and the cornering force ratio (CF ratio) of the rear to the front increases, which is thought to improve linearity and further improve grip performance.

[0020] tanδA out and D / W L It is preferable that the following formula (1) is satisfied. Equation (1) tanδA out ×(D / W L ) ≥ 0.30

[0021] tanδA out and D / W L By setting the product of x and y in the above range, it is possible to ensure good rigidity and ground contact area of ​​the tread rubber, and heat generation properties are also improved, so it is thought that grip performance can be further improved.

[0022] <Definition> A "genuine rim" is a rim that is determined for each tire by the standard system that includes the standard on which the tire is based. For JATMA, it is a "standard rim," for TRA, it is a "design rim," and for ETRTO, it is a "measuring rim."

[0023] "Normal internal pressure" is the air pressure specified for each tire by each standard in the standard system, including the standard on which the tire is based. For JATMA, it is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE."

[0024] "Normal condition" refers to a state in which a tire is mounted on a normal rim, inflated to a normal internal pressure, and no load is applied. In this specification, unless otherwise specified, the dimensions of each part of the tire are measured in the normal condition.

[0025] "Normal load" is the load specified for each tire by each standard in the standard system, including the standard on which the tire is based. For JATMA, it is "maximum load capacity," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is "LOAD CAPACITY."

[0026] The "tread contact edge" is the outermost contact point in the tire width direction when a normal load is applied to a tire in a normal state and the tire contacts a flat surface with a camber angle of 0 degrees.

[0027] "Distance D from the vehicle outer contact edge to the interface between the inner tread rubber layer and the outer tread rubber layer" refers to the straight-line distance from the vehicle outer contact edge on the contact surface to the extension of the rubber interface between the inner tread rubber layer and the outer tread rubber layer on the tread surface.

[0028] The "groove area ratio" is the ratio of the total area of ​​all grooves to the total surface area of ​​each contact patch formed by the outer tread rubber layer and the inner tread rubber layer, which are divided at the interface, assuming that all grooves are filled.

[0029] "Oil content" includes the amount of oil contained in oil-extended rubber.

[0030] <Measurement method> The "groove area ratio" is calculated from the contact shape when the tread is pressed against a flat surface under a normal load under normal conditions. The contact shape can be obtained by, for example, mounting a tire on a normal rim and maintaining the normal internal pressure, applying ink to the tread, pressing the tire perpendicularly against cardboard or the like under a normal load (camber angle 0°), and transferring the ink applied to the tread. The obtained contact shape can then be divided at the dividing interface between the outer tread rubber layer and the inner tread rubber layer, thereby determining the groove area ratio of the contact surface of the outer tread rubber layer and the groove area ratio of the contact surface of the inner tread rubber layer, respectively.

[0031] "Tan δA" can be calculated as the average of 11 values ​​obtained by measuring tan δ at temperatures from 0°C to 50°C in 5°C increments under conditions of a frequency of 10 Hz, an initial strain of 1%, and an amplitude of ±0.1%. The sample for measuring tan δA is a vulcanized rubber composition measuring 20 mm in length, 4 mm in width, and 1 mm in thickness. When cutting out a sample from a tire, it is cut out from the tread portion of the tire so that the long side is in the tire circumferential direction and the thickness direction is in the tire radial direction.

[0032] "Styrene content" is 1 It is a value calculated by H-NMR measurement, and is applied to, for example, rubber components having repeating units derived from styrene, such as SBR. "Vinyl content (amount of 1,2-bonded butadiene units)" is a value calculated by infrared absorption spectroscopy in accordance with JIS K 6239-2:2017, and is applied to, for example, rubber components having repeating units derived from butadiene, such as SBR and BR. "Cis content (amount of cis-1,4-bonded butadiene units)" is a value calculated by infrared absorption spectroscopy in accordance with JIS K 6239-2:2017, and is applied to, for example, rubber components having repeating units derived from butadiene, such as BR.

[0033] The "weight average molecular weight (Mw)" can be determined by converting the measured value into a standard polystyrene equivalent value based on the value measured by gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMALTIPORE HZ-M manufactured by Tosoh Corporation). For example, this applies to SBR, BR, etc.

[0034] "N2SA of carbon black" is measured in accordance with JIS K 6217-2:2017. "Oil absorption of carbon black (DBP oil absorption (OAN))" is measured in accordance with JIS K6217-4:2017.

[0035] "N2SA of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0036] The "softening point of the resin component" is the softening point specified in JIS K 6220-1:2015 7.7 measured using a ring and ball softening point tester, and is the temperature at which the ball drops.

[0037] A procedure for manufacturing a tire according to an embodiment of the present disclosure will be described in detail below. However, the following description is merely an example for explaining the present disclosure, and is not intended to limit the technical scope of the present disclosure to the scope of the description.

[0038] <Tires> Hereinafter, a tire according to an embodiment of the present disclosure will be described with reference to the drawings.

[0039] As shown in FIG. 1, a tire T includes a pair of bead portions 1, sidewall portions 2 extending outward from each bead portion 1 in the tire radial direction RD (the vertical direction in FIG. 1; hereinafter simply referred to as the tire radial direction), a tread portion 3 continuing to the radially outer ends of both sidewall portions 2, and a toroidal carcass layer 4 extending from the tread portion 3 through the sidewall portions 2 to the bead portions 1. A bead core 1a and a bead filler 1b are disposed in the bead portions 1. The carcass layer 4 is disposed between the pair of bead portions 1 and is composed of at least one carcass ply, and its end portion is secured in a wound-up state via the bead core 1a. A sidewall rubber 6 is disposed on the outer side of the carcass layer 4 in the sidewall portions 2. A rim strip rubber 7 is disposed on the outer side of the carcass layer 4 in the bead portions 1, and comes into contact with a rim (not shown) when the tire is mounted on a rim.

[0040] The tire of the present disclosure has a specified mounting direction relative to a vehicle, and the mounting direction relative to the vehicle is indicated on the side of the tire.

[0041] The tread portion 3 has an outer tread edge To and an inner tread edge Ti. The outer tread edge To is located on the outer side of the vehicle (on the right side in FIG. 1) when mounted on the vehicle. The inner tread edge Ti is located on the inner side of the vehicle (on the left side in FIG. 1) when mounted on the vehicle. Each tread edge To, Ti is the outermost contact point in the tire width direction (left-right direction in FIG. 1) when a normal load is applied to a normal tire in a normal state and the tire contacts a flat surface with a camber angle of 0 degrees.

[0042] In FIG. 1 , the tread portion 3 has a cap portion 50 that forms the contact surface and a base portion 51 provided radially inward of the cap portion 50. The cap portion 50 has an inner tread rubber layer 52 that forms the vehicle-inner end side when mounted on a vehicle, and an outer tread rubber layer 53 that forms the vehicle-outer end side. Wing rubber may be provided on the outside of the inner tread rubber layer 52 and the outer tread rubber layer 53. Note that even if wing rubber is provided or the sidewall portion is configured to cover the radially outer side of the tread, these do not fall under the inner tread rubber and outer tread rubber of the present disclosure, even if they form the contact surface. In FIG. 1 , the interface P between the inner tread rubber layer and the outer tread rubber layer from the vehicle-outer contact edge is located below the circumferential groove 5a, but is not limited to this and may be located below the land portion 5. The "land portion" refers to an area in the tread portion 3 that is partitioned by the tread ground contact edges To, Ti and a plurality of circumferential grooves 5a that extend continuously in the tire circumferential direction.

[0043] Distance W between the ground contact edges of the outer tread edge To and the inner tread edge Ti L The ratio of the distance D from the outer contact edge of the vehicle to the interface P between the inner tread rubber layer and the outer tread rubber layer (D / W L ) is 0.50 or more, preferably 0.52 or more, more preferably 0.54 or more, even more preferably 0.56 or more, and particularly preferably 0.58 or more. LBy setting the D / W within the above range, the outer tread rubber layer will partially contact the ground when braking straight ahead, providing adhesion, and this, combined with the high rigidity of the inner tread rubber layer, will facilitate deceleration. Also, when cornering, where the outer tread rubber layer is more likely to contact the ground, the outer tread rubber layer, which has partially heated up during straight ahead and reduced rigidity, will follow the road surface, allowing for grip performance against lateral forces to be demonstrated from the beginning of cornering. L In view of the effects of the present disclosure, is preferably 0.90 or less, more preferably 0.88 or less, even more preferably 0.86 or less, and particularly preferably 0.84 or less.

[0044] The groove area ratio of the contact surface of the outer tread rubber layer is preferably smaller than the groove area ratio of the contact surface of the inner tread rubber layer. By making the groove area ratio of the contact surface of the outer tread rubber layer smaller than the groove area ratio of the contact surface of the inner tread rubber layer, the rigidity in the direction toward the outside of the vehicle becomes greater than that in the direction toward the inside of the vehicle, and the cornering force ratio (CF ratio) of the rear to the front increases, which is thought to improve linearity and further improve grip performance.

[0045] The groove area ratio of the ground contact surface of the outer tread rubber layer is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. The groove area ratio of the ground contact surface of the outer tread rubber layer is preferably 40% or less, more preferably 35% or less, and even more preferably 30% or less.

[0046] The groove area ratio of the contact surface of the inner tread rubber layer is preferably 8% or more, more preferably 12% or more, and even more preferably 18% or more. The groove area ratio of the contact surface of the inner tread rubber layer is preferably 45% or less, more preferably 40% or less, and even more preferably 35% or less.

[0047] From the viewpoint of the effects of the present disclosure, the difference between the groove area ratio of the contact surface of the outer tread rubber layer and the groove area ratio of the contact surface of the inner tread rubber layer is preferably 2% or more and 10% or less, more preferably 3% or more and 9% or less, and even more preferably 4% or more and 8% or less.

[0048] Tan δA of the inner tread rubber layer in is 0.30 or less, preferably 0.28 or less, more preferably 0.26 or less, and even more preferably 0.24 or less. in By setting tan δA in the above range, it is possible to suppress a decrease in the rigidity of the inner tread rubber layer and further improve the grip performance when traveling straight. in From the viewpoint of grip performance, is preferably 0.06 or more, more preferably 0.08 or more, even more preferably 0.10 or more, and particularly preferably 0.12 or more.

[0049] Tan δA of the outer tread rubber layer out is 0.40 or more, preferably 0.42 or more, more preferably 0.44 or more, and even more preferably 0.46 or more. out By setting tan δA in the above range, grip performance during cornering can be further improved. out From the viewpoint of fuel economy, is preferably equal to or less than 0.90, more preferably equal to or less than 0.80, and even more preferably equal to or less than 0.70.

[0050] The tan δA of the rubber composition of the present disclosure can be adjusted appropriately by the types and amounts of the rubber component, filler, softener, etc., which will be described later.

[0051] tan δA represented by the above formula (1) out and D / W L The product of tan δA is preferably 0.20 or more, more preferably 0.24 or more, even more preferably 0.27 or more, still more preferably 0.30 or more, and particularly preferably 0.33 or more. out and D / W L By setting the product of tan δA within the above range, it is believed that the tread rubber can ensure good rigidity and contact area, and heat generation properties are also improved, thereby further improving grip performance. out and D / W L The product of is preferably 0.80 or less, more preferably 0.70 or less, and even more preferably 0.65 or less.

[0052] [Rubber composition] The tire of the present disclosure can more effectively improve grip performance during straight running and cornering by combining the width of the outer tread rubber layer 53 described above with the physical properties of the rubber composition constituting the cap portion 50 including the inner tread rubber layer 52 and the outer tread rubber layer 53.

[0053] <Rubber component> The rubber compositions (hereinafter referred to as the rubber compositions of the present disclosure) constituting the inner tread rubber layer 52 and the outer tread rubber layer 53 each preferably use a diene rubber as the rubber component. From the viewpoint of the effects of the present disclosure, the content of the diene rubber in the rubber component is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The rubber component may also be composed solely of diene rubber.

[0054] Examples of diene rubbers include isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene rubber (SIR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). These diene rubbers may be used alone or in combination of two or more. Among these, it is preferable to contain at least one selected from the group consisting of isoprene rubber, BR, and SBR, and it is more preferable to contain SBR.

[0055] (SBR) The SBR is not particularly limited, and examples thereof include unmodified solution-polymerized SBR (S-SBR) and emulsion-polymerized SBR (E-SBR), as well as modified SBRs (modified S-SBR, modified E-SBR). Modified SBRs include SBRs whose ends and / or main chains are modified, and modified SBRs (condensates, those with branched structures, etc.) coupled with tin, silicon compounds, etc. Among these, S-SBR and modified SBR are preferred. Furthermore, hydrogenated products of these SBRs (hydrogenated SBR) can also be used.

[0056] The SBRs listed above may be used alone or in combination of two or more. As the SBRs listed above, for example, commercially available products from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., ZS Elastomers Co., Ltd., etc. can be used.

[0057] From the viewpoints of grip performance and abrasion resistance, the styrene content of SBR is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass or more. From the viewpoints of temperature dependency of grip performance and blow resistance, the styrene content is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. The styrene content of SBR is measured by the above-mentioned measurement method.

[0058] The vinyl content of SBR is preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more, from the viewpoints of ensuring reactivity with silica, grip performance, and abrasion resistance. Furthermore, the vinyl content of SBR is preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 60 mol% or less, from the viewpoints of preventing an increase in temperature dependency, elongation at break, and abrasion resistance. The vinyl content of SBR is measured by the above-mentioned measurement method.

[0059] From the viewpoint of grip performance, the weight average molecular weight (Mw) of SBR is preferably 200,000 or more, more preferably 250,000 or more. From the viewpoint of crosslinking uniformity, the weight average molecular weight is preferably 2,000,000 or less, more preferably 1,800,000 or less, and even more preferably 1,500,000 or less. The weight average molecular weight of SBR is measured by the above-mentioned measurement method.

[0060] When SBR is contained, the content in the rubber component is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, still more preferably 60% by mass or more, and particularly preferably 70% by mass or more, from the viewpoint of grip performance. There is no particular upper limit for the SBR content, and it may be 100% by mass.

[0061] (BR) The BR is not particularly limited, and examples thereof include BR having a cis content of less than 50 mol% (low-cis BR), BR having a cis content of 90 mol% or more (high-cis BR), rare earth butadiene rubber (rare earth BR) synthesized using a rare earth catalyst, BR containing syndiotactic polybutadiene crystals (SPB-containing BR), and modified BR (high-cis modified BR, low-cis modified BR), which are commonly used in the tire industry. These BRs may be used alone or in combination of two or more. The cis content of BR is measured by the above-mentioned measurement method.

[0062] As the high-cis BR, for example, commercially available products from Zeon Corporation, Ube Industries, Ltd., JSR Corporation, etc. can be used. The inclusion of high-cis BR can improve low-temperature properties and wear resistance. The cis content of the high-cis BR is preferably 95 mol% or more, more preferably 96 mol% or more, even more preferably 97 mol% or more, and particularly preferably 98 mol% or more. The cis content of BR is measured by the above-mentioned measurement method.

[0063] From the viewpoint of abrasion resistance, the weight-average molecular weight (Mw) of BR is preferably 300,000 or more, more preferably 350,000 or more, and even more preferably 400,000 or more. From the viewpoint of crosslink uniformity, etc., it is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less. The Mw of BR is measured by the above-mentioned measurement method.

[0064] When BR is contained, the content in the rubber component is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and particularly preferably 7% by mass or more, from the viewpoint of grip performance. The content of BR is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less.

[0065] (Isoprene rubber) Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of NR include SIR20, RSS#3, and TSR20, which are commonly used in the tire industry. Examples of IR include IR2200 and other commonly used rubbers. 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 isoprene-based rubbers may be used alone or in combination.

[0066] When an isoprene-based rubber is contained, the content in the rubber component is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, from the viewpoint of grip performance. The lower limit of the content is not particularly limited, but can be, for example, 1% by mass or more, 3% by mass or more, 5% by mass or more, or 10% by mass or more.

[0067] (Other rubber components) The rubber component may contain other rubber components besides diene rubber, as long as the effects of the present disclosure are not affected. Examples of other rubber components include crosslinkable rubber components commonly used in the tire industry, such as butyl rubber (IIR), halogenated butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. These other rubber components may be used alone or in combination of two or more. In addition to the above rubber components, known thermoplastic elastomers may or may not be included.

[0068] <Filler> The rubber composition of the present disclosure more preferably contains carbon black and / or silica as a filler. The rubber composition constituting the outer tread rubber layer preferably contains carbon black as a filler. The rubber composition constituting the inner tread rubber layer preferably contains silica as a filler, more preferably silica and carbon black.

[0069] (silica) The silica is not particularly limited, and can be, for example, silica prepared by a dry method (anhydrous silica) or silica prepared by a wet method (hydrated silica), which are commonly used in the tire industry. Among them, hydrated silica prepared by a wet method is preferred because it contains a large number of silanol groups. In addition to the above silica, silica made from biomass materials such as rice husks can also be used as appropriate. These silicas can be used alone or in combination of two or more types.

[0070] The nitrogen adsorption specific surface area (N2SA) of silica is 100m from the viewpoint of ensuring reinforcement and grip performance. 2 / g or more is preferable, and 120m 2 / g or more is more preferable, and 140m 2 / g or more is more preferable, and 160m 2 From the viewpoint of heat buildup and processability, it is particularly preferable that the tensile strength is 350 m / g or more. 2 / g or less is preferable, and 300m 2 / g or less is more preferable, and 250m 2 / g or less is more preferable. The N2SA of silica is measured by the above-mentioned measuring method.

[0071] When the rubber composition constituting the inner tread rubber layer contains silica, the content thereof per 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably 60 parts by mass or more, even more preferably 80 parts by mass or more, and particularly preferably 90 parts by mass or more, from the viewpoint of ensuring rigidity during straight running. Also, the content of silica per 100 parts by mass of the rubber component is preferably 150 parts by mass or less, more preferably 140 parts by mass or less, and even more preferably 130 parts by mass or less, from the viewpoint of reducing the specific gravity of the rubber and achieving weight reduction. Note that when the rubber composition constituting the outer tread rubber layer contains silica, the content thereof per 100 parts by mass of the rubber component is determined by tan δA out is not particularly limited as long as it is 0.40 or more.

[0072] (carbon black) The carbon black is not particularly limited, and for example, those commonly used in the tire industry, such as GPF, FEF, HAF, ISAF, and SAF, can be used. In addition to carbon black produced by burning common mineral oil, carbon black made from biomass materials such as lignin can also be used. These carbon blacks can be used alone or in combination of two or more.

[0073] The nitrogen adsorption specific surface area (N2SA) of carbon black is 50m from the viewpoint of reinforcement and grip performance. 2 / g or more is preferable, and 70m 2 / g or more is more preferable, and 100m 2 / g or more is more preferable, and 120m 2 / g or more is particularly preferable. 2 / g or less is preferable, and 220m 2 / g or less is more preferable. The N2SA of carbon black is measured by the above-mentioned measurement method.

[0074] The oil absorption (DBP oil absorption (OAN)) of carbon black is preferably 85 mL / 100 g or more, more preferably 90 mL / 100 g or more, and even more preferably 100 mL / 100 g or more, from the viewpoint of reinforcement and grip performance. Furthermore, from the viewpoint of grip performance, the OAN is preferably 250 mL / 100 g or less, more preferably 225 mL / 100 g or less, and even more preferably 200 mL / 100 g or less. The OAN of carbon black is measured by the above-mentioned measurement method.

[0075] When the rubber composition constituting the outer tread rubber layer contains carbon black, the content thereof per 100 parts by mass of the rubber component is preferably 60 parts by mass or more, more preferably 80 parts by mass or more, even more preferably 100 parts by mass or more, and particularly preferably 110 parts by mass or more, from the viewpoint of facilitating heat buildup during cornering and straight driving. When the rubber composition constituting the inner tread rubber layer contains carbon black, the content thereof per 100 parts by mass of the rubber component 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 particularly preferably 10 parts by mass or more, from the viewpoint of weather resistance and reinforcement. Furthermore, the content of carbon black per 100 parts by mass of the rubber component is preferably 160 parts by mass or less, more preferably 150 parts by mass or less, and even more preferably 140 parts by mass or less, from the viewpoint of fuel economy.

[0076] (Other fillers) Fillers other than silica and carbon black that have been commonly used in the tire industry can be blended, such as aluminum hydroxide, calcium carbonate, alumina, clay, talc, etc. In addition to these fillers, biochar (BIOCHAR) may also be used as appropriate.

[0077] The total amount of filler per 100 parts by mass of the rubber component is preferably 60 parts by mass or more, more preferably 80 parts by mass or more, even more preferably 100 parts by mass or more, and particularly preferably 110 parts by mass or more, from the viewpoint of reinforcement and grip performance, and is preferably 160 parts by mass or less, more preferably 150 parts by mass or less, and even more preferably 140 parts by mass or less, from the viewpoint of dispersibility.

[0078] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent.The silane coupling agent is not particularly limited, and any silane coupling agent that has been conventionally used in combination with silica in the tire industry can be used, for example, mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl)disulfide, bis(3-triethoxysilylpropyl)tetrasulfide; 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, 3-octanoylthio-1-propyltrimethoxysilane; Examples of suitable silane coupling agents include thioester-based silane coupling agents such as silane; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)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. Among these, sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferred. Examples of suitable silane coupling agents include those commercially available from Momentive, Inc. These silane coupling agents may be used alone or in combination.

[0079] When a silane coupling agent is contained, the content thereof per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, even more preferably 2.0 parts by mass or more, and particularly preferably 4.0 parts by mass or more, from the viewpoint of improving the dispersibility of silica, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 12 parts by mass or less, from the viewpoint of preventing a decrease in abrasion resistance.

[0080] <Softener> The rubber composition according to the present disclosure preferably contains a softener, such as a resin component, oil, liquid rubber, or ester-based plasticizer.

[0081] (resin component) The resin component is not particularly limited, and examples thereof include petroleum resins, terpene resins, rosin resins, and phenolic resins commonly used in the tire industry. These resin components may be used alone or in combination of two or more. From the viewpoint of generating adhesion to the road surface during cornering and improving grip performance, aromatic petroleum resins are preferably used in the rubber composition constituting the outer tread rubber layer.

[0082] As used herein, "C5 petroleum resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions having 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferably used as the C5 petroleum resin.

[0083] In this specification, "aromatic petroleum resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a hydrogenated or modified version of the C9 fraction. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of aromatic petroleum resins include: Coumarone-indene resin, coumarone resin, indene resin, and aromatic vinyl resin are preferably used. As the aromatic vinyl resin, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, because they are economical, easy to process, and have excellent heat generation properties. As the aromatic vinyl resin, for example, commercially available products from Kraton, Eastman Chemical, Mitsui Chemicals, Inc., etc. can be used.

[0084] As used herein, the term "C5C9 petroleum resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified resin. Examples of the C5 fraction and the C9 fraction include the petroleum fractions described above. As the C5C9 petroleum resin, for example, commercially available products from Tosoh Corporation, LUHUA, etc. can be used.

[0085] Examples of terpene resins include polyterpene resins made of at least one terpene compound selected from α-pinene, β-pinene, limonene, dipentene, and the like; aromatic modified terpene resins made from the terpene compound and an aromatic compound; terpene phenolic resins made from a terpene compound and a phenolic compound; and those obtained by subjecting these terpene resins to hydrogenation treatment (hydrogenated terpene resins). Examples of aromatic compounds used as raw materials for aromatic modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenolic compounds used as raw materials for terpene phenolic resins include phenol, bisphenol A, cresol, and xylenol.

[0086] The rosin-based resin is not particularly limited, but examples thereof include natural resin rosin and rosin-modified resins obtained by modifying rosin by hydrogenation, disproportionation, dimerization, esterification, etc.

[0087] The phenolic resin is not particularly limited, but examples thereof include phenol formaldehyde resin, alkylphenol formaldehyde resin, alkylphenol acetylene resin, and oil-modified phenol formaldehyde resin.

[0088] From the viewpoint of grip performance, the softening point of the resin component is preferably 60° C. or higher, more preferably 70° C. or higher, and even more preferably 80° C. or higher. From the viewpoint of processability and improving the dispersibility of the rubber component and the filler, the softening point is preferably 150° C. or lower, more preferably 140° C. or lower, and even more preferably 130° C. or lower. The softening point of the resin component is measured by the above-mentioned measurement method.

[0089] When a resin component is contained, the content per 100 parts by mass of the rubber component is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, and particularly preferably 30 parts by mass or more, from the viewpoint of grip performance. Also, from the viewpoint of suppressing heat buildup, the content is 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.

[0090] (oil) Examples of oils include process oil, vegetable oils, and animal fats. Examples of the process oil include paraffinic process oil, naphthenic process oil, and aromatic process oil. Furthermore, as an environmental measure, process oil with a low content of polycyclic aromatic compounds (PCA) can also be used. Examples of the low-PCA process oil include mild extract solvates (MES), treated distillate aromatic extract (TDAE), and heavy naphthenic oil. Furthermore, from the perspective of life cycle assessment, refined waste oil from rubber mixers and engines, or waste cooking oil from restaurants, can also be used.

[0091] When oil is contained, the content per 100 parts by mass of the rubber component 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, and particularly preferably 40 parts by mass or more from the viewpoint of processability, and is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 80 parts by mass or less, and particularly preferably 70 parts by mass or less from the viewpoint of abrasion resistance.

[0092] (liquid rubber) The liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at room temperature (25°C), and examples thereof 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. These liquid rubbers may be used alone or in combination of two or more.

[0093] When a liquid rubber is contained, the content thereof per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more. The content of the liquid rubber is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less.

[0094] (ester plasticizer) Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelate (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). These ester-based plasticizers may be used alone or in combination of two or more.

[0095] When an ester-based plasticizer is contained, the content thereof per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more. The content of the ester-based plasticizer is 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.

[0096] The content of the softener per 100 parts by mass of the rubber component (the total amount when multiple softeners are used in combination) is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 90 parts by mass or more, and particularly preferably 100 parts by mass or more from the viewpoint of road conformity during cornering. Also, from the viewpoint of processability, the content is preferably 180 parts by mass or less, more preferably 170 parts by mass or less, even more preferably 160 parts by mass or less, and particularly preferably 150 parts by mass or less.

[0097] <Other compounding agents> In addition to the above components, the rubber composition according to the present disclosure may appropriately contain compounding agents conventionally commonly used in the tire industry, such as wax, processing aids, antioxidants, stearic acid, zinc oxide, vulcanizing agents, and vulcanization accelerators.

[0098] When wax is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more from the viewpoint of weather resistance of the rubber, and is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less from the viewpoint of preventing whitening of the tire due to bloom.

[0099] The antioxidant is not particularly limited, but examples thereof include amine-based, quinoline-based, quinone-based, phenol-based, and imidazole-based compounds, as well as metal carbamates. Preferred are phenylenediamine-based antioxidants such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, and N-cyclohexyl-N'-phenyl-p-phenylenediamine, and quinoline-based antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymer and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline. These antioxidants may be used alone or in combination of two or more.

[0100] When an antioxidant is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of ozone crack resistance of the rubber, and is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, from the viewpoint of abrasion resistance and wet grip performance.

[0101] When stearic acid is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more from the viewpoint of processability, and is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less from the viewpoint of vulcanization rate.

[0102] When zinc oxide is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more from the viewpoint of processability, and is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less from the viewpoint of abrasion resistance.

[0103] As the vulcanizing agent, sulfur is preferably used, and examples of sulfur that can be used include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.

[0104] When sulfur is contained, the content per 100 parts by mass of the rubber component is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, the content is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, even more preferably 3.0 parts by mass or less, and particularly preferably 2.5 parts by mass or less. When oil-containing sulfur is used as the crosslinking agent, the content of the vulcanizing agent is the total content of pure sulfur contained in the oil-containing sulfur.

[0105] Known organic crosslinking agents can also be used as vulcanizing agents other than sulfur. When an organic crosslinking agent is added, the distance between crosslinking points becomes longer than in crosslinking using sulfur, making it possible to generate more energy loss and achieving excellent peak grip performance.

[0106] The organic cross-linking agent is not particularly limited as long as it can form cross-linked chains other than polysulfide bonds, but examples include alkylphenol-sulfur chloride condensation products, 1,6-hexamethylene-sodium dithiosulfate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, and dicumyl peroxide.

[0107] Examples of vulcanization accelerators include sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, thiuram vulcanization accelerators, guanidine vulcanization accelerators, dithiocarbamate vulcanization accelerators, and caprolactam disulfide. These vulcanization accelerators may be used alone or in combination of two or more. Among them, in order to more suitably obtain the desired effects, one or more vulcanization accelerators selected from the group consisting of sulfenamide vulcanization accelerators, guanidine vulcanization accelerators, and dithiocarbamate vulcanization accelerators are preferred, and it is more preferred to use a sulfenamide vulcanization accelerator and a dithiocarbamate vulcanization accelerator in combination.

[0108] Examples of sulfenamide vulcanization accelerators include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), etc. Among these, TBBS and CBS are preferred.

[0109] Examples of thiazole vulcanization accelerators include 2-mercaptobenzothiazole (MBT) or its salt, di-2-benzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio)benzothiazole, etc. Among these, MBTS and MBT are preferred, and MBTS is more preferred.

[0110] Examples of guanidine vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatechol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, etc. Among these, DPG is preferred.

[0111] Examples of dithiocarbamate vulcanization accelerators include piperidinium pentamethylenedithiocarbamate (PPDC), zinc dimethyldithiocarbamate (ZnMDC), zinc diethyldithiocarbamate (ZnEDC), zinc dibutyldithiocarbamate (ZnBDC), zinc dibenzyldithiocarbamate (ZDBzC), zinc N-ethyl-N-phenyldithiocarbamate (ZnEPDC), zinc N-pentamethylenedithiocarbamate (ZnPDC), sodium dibutyldithiocarbamate (NaBDC), copper dimethyldithiocarbamate (CuMDC), iron dimethyldithiocarbamate (FeMDC), and tellurium diethyldithiocarbamate (TeEDC). Of these, ZnBDC and ZDBzC are preferred.

[0112] When a vulcanization accelerator is contained, the content thereof per 100 parts by mass of the rubber component is preferably 1.0 part by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2.0 parts by mass or more. The content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably 8.0 parts by mass or less, more preferably 7.0 parts by mass or less, even more preferably 6.0 parts by mass or less, and particularly preferably 5.0 parts by mass or less. By setting the content of the vulcanization accelerator within the above range, breaking strength and elongation tend to be ensured.

[0113] <Manufacturing> The rubber composition according to the present disclosure can be produced by a known method, for example, by kneading the above-described components using a rubber kneading device such as an open roll or an internal kneader (such as a Banbury mixer or kneader).

[0114] The kneading step includes, for example, a base kneading step in which compounding ingredients and additives other than the vulcanizing agent and vulcanization accelerator are kneaded, and a final kneading (F kneading) step in which the vulcanizing agent and vulcanization accelerator are added to the kneaded product obtained in the base kneading step and kneaded. Furthermore, the base kneading step can be divided into multiple steps as desired.

[0115] The kneading conditions are not particularly limited, but examples include a method in which the base kneading step involves kneading for 3 to 10 minutes at a discharge temperature of 150 to 170°C, and a method in which the final kneading step involves kneading for 1 to 5 minutes at 70 to 110°C. The vulcanization conditions are not particularly limited, but examples include a method in which vulcanization is carried out for 10 to 30 minutes at 150 to 200°C.

[0116] The tire of the present disclosure having a tread made of the rubber composition can be manufactured by a conventional method. That is, an unvulcanized rubber composition obtained by blending the above-mentioned components with a rubber component as needed is extruded to match the shape of each rubber layer constituting the tread, and is then bonded together with other tire components in a tire building machine and molded by a conventional method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in a vulcanizer to manufacture the tire. The vulcanization conditions are not particularly limited, and examples include a method of vulcanizing at 150 to 200°C for 10 to 30 minutes.

[0117] <Application> The tire of the present disclosure can be a general-purpose tire such as a passenger car tire, a truck / bus tire, or a motorcycle tire, or a racing tire. Passenger car tires are tires designed to be mounted on four-wheeled vehicles and have a maximum load capacity of 1000 kg or less. The tire of the present disclosure can also be used as an all-season tire, a summer tire, or a winter tire such as a studless tire. [Example]

[0118] Hereinafter, the present disclosure will be described based on examples, but the present disclosure is not limited to these examples.

[0119] The various chemicals used in the examples and comparative examples are listed below. NR:TSR20 SBR1: HP755B manufactured by JSR Corporation (S-SBR, styrene content: 40% by mass, vinyl content: 38 mol%, contains 37.5 parts by mass of oil per 100 parts by mass of rubber solids) SBR2: Tufuden 4850 manufactured by Asahi Kasei Corporation (unmodified S-SBR, styrene content: 40% by mass, vinyl content: 46 mol%, Mw: 940,000, contains 50 parts by mass of oil per 100 parts by mass of rubber solids) BR: UBEPOL BR (registered trademark) 150B (cis content: 97 mol%, Mw: 440,000) manufactured by Ube Industries, Ltd. Carbon black: Show Black N330 (N2SA: 75 ml) manufactured by Cabot Japan Co., Ltd. 2 / g, DBP oil absorption: 102mL / 100g) Silica: ZEOSIL 1165MP (N2SA: 160m) manufactured by Rhodia 2 / g) Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide) manufactured by Evonik Degussa Resin component 1: Petrotack 100V (C5C9 petroleum resin, softening point: 96°C) manufactured by Tosoh Corporation Resin component 2: FTR8100 (C5C9 petroleum resin, softening point: 96°C) manufactured by Mitsui Chemicals, Inc. Oil: H&R VivaTec 500 (TDAE oil) Liquid rubber: Cray Valley Ricon 100 (liquid SBR) Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Camellia stearic acid beads manufactured by NOF Corporation Anti-aging agent: Antigen 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Wax: Sunnock N manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Sulfur: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd. Vulcanization accelerator 1: Sancerer CM-G (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Sanshin Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccela ZTC (zinc dibenzyldithiocarbamate (ZDBzC)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 3: Percussit DPG (1,3-diphenylguanidine) manufactured by Flexis

[0120] Examples and Comparative Examples According to the formulation shown in Table 1, using a 1.7 L sealed Banbury mixer, chemicals other than sulfur and vulcanization accelerators were kneaded for 1 to 10 minutes until the discharge temperature reached 150 to 160 °C to obtain a kneaded product. Next, using a two-roll open mill, sulfur and vulcanization accelerators were added to the obtained kneaded product and kneaded for 4 minutes until the temperature reached 105 °C to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was extruded into the shapes of an inner tread rubber layer and an outer tread rubber layer (both with a thickness of 7.5 mm) using an extruder equipped with a die of a predetermined shape to form a composite of the outer tread layer and the inner tread layer, and bonded together with a base portion (thickness: 1.5 mm) and other tire members to produce an unvulcanized tire. Each test tire was produced by press vulcanization at 170 °C for 12 minutes.

[0121] <Measurement of tanδA> After vulcanization, each rubber test piece was cut out from each rubber layer of the tread portion of each test tire to a size of 20 mm in length × 4 mm in width × 1 mm in thickness such that the tire circumferential direction was the long side and the tire radial direction was the thickness direction. For each rubber test piece, using an Iplexer series manufactured by GABO, the loss tangent tanδ was measured at each temperature in 5 °C increments from 0 °C to 50 °C under the conditions of a frequency of 10 Hz, an initial strain of 1%, and an amplitude of ±0.1%. Then, the average value of the obtained 11 numerical values was taken as tanδA. The results are shown in Table 1 and Table 2.

[0122] <Grip performance during straight driving> The test tires were mounted on all wheels of a domestic FR car (2000 cc), and 10 laps of actual vehicle running were performed on a test course of a dry asphalt road surface. When braking while driving straight at a speed of 100 km / h, the test driver evaluated the control stability. The evaluation was performed with integer values from 1 to 10. Based on the evaluation criteria that the higher the score, the better the control stability during steering, the total score of 10 test drivers was calculated. The total score of Comparative Example 1 was converted to a reference value (100), and the evaluation results of each test tire were indexed to be proportional to the total score and displayed. A larger numerical value indicates higher initial grip performance.

[0123] <Grip performance when cornering> The test tires were mounted on all wheels of a domestically produced FR vehicle (2000cc), and the vehicle was driven 10 laps on a test course with a dry asphalt surface. While driving on a straight line at 100 km / h, the test driver performed a sensory evaluation of the stability of control when braking and entering a corner. The evaluation was performed using an integer value from 1 to 10, with a higher score indicating better control stability during steering. The total score of the 10 test drivers was calculated based on this evaluation standard. The total score of Comparative Example 1 was converted to a reference value (100), and the evaluation results of each test tire were displayed as an index proportional to the total score. A higher value indicates better initial grip performance.

[0124] The target performance for the overall performance of grip performance when going straight and when cornering (the sum of the grip performance index when going straight and the grip performance index when cornering) is over 200.

[0125] [Table 1]

[0126] [Table 2]

[0127] The results in Tables 1 and 2 show that the tires of the present disclosure have improved overall performance in terms of grip performance when traveling straight and grip performance when cornering under high-speed driving conditions.

[0128] <Embodiment> Examples of embodiments of the present disclosure are provided below.

[0129] [1] A tire having a tread portion whose mounting direction on a vehicle is specified, wherein the tread portion has an inner tread rubber layer that forms the vehicle inner end side when mounted on the vehicle and an outer tread rubber layer that forms the vehicle outer end side, and the distance W between both ground contact ends LThe ratio of the distance D from the outer contact edge of the vehicle to the interface between the inner tread rubber layer and the outer tread rubber layer (D / W L ) is 0.50 or more, and the average value tanδA of the loss tangent tanδ of the inner tread rubber layer at 0°C to 50°C measured under the conditions of a frequency of 10Hz, an initial strain of 1%, and an amplitude of ±0.1% in is 0.30 or less, and the average value tanδA of the loss tangent tanδ of the outer tread rubber layer at 0°C to 50°C measured under the conditions of a frequency of 10Hz, an initial strain of 1%, and an amplitude of ±0.1% out Tires with a coefficient of friction of 0.40 or more. [2] The tire according to the above [1], wherein the rubber composition constituting the outer tread rubber layer contains 100 parts by mass or more of carbon black per 100 parts by mass of the rubber component. [3] The tire according to [1] or [2] above, wherein the rubber composition constituting the outer tread rubber layer contains 70 parts by mass or more of a softener per 100 parts by mass of the rubber component. [4] The tire according to any one of the above [1] to [3], wherein the rubber composition constituting the outer tread rubber layer contains an aromatic petroleum resin. [5] The tire according to any one of the above [1] to [4], wherein the rubber composition constituting the inner tread rubber layer contains 40 parts by mass or more of silica per 100 parts by mass of the rubber component. [6] The tire according to any one of the above [1] to [5], wherein the groove area ratio of the ground contact surface of the outer tread rubber layer is smaller than the groove area ratio of the ground contact surface of the inner tread rubber layer. [7] A tire described in any one of [1] to [6] above, wherein the difference between the groove area ratio of the contact surface of the outer tread rubber layer and the groove area ratio of the contact surface of the inner tread rubber layer is 2% or more and 10% or less. [8] tanδA out and D / W L The tire according to any one of the above [1] to [7], which satisfies the following formula (1): Equation (1) tanδA out ×(D / W L ) ≥ 0.30 [Explanation of symbols]

[0130] 1. Bead part 1a···Bead core 1b Bead filler 2. Sidewall 3. Tread section 4. Carcass layer 5... land department 5a...Circumferential groove 6. Sidewall rubber 7. Rim strip rubber 50···Cap part 51 Base 52 Inner tread rubber layer 53 Outer tread rubber layer

Claims

1. A tire having a tread portion whose mounting direction on a vehicle is specified, the tread portion has an inner tread rubber layer that forms an end portion on an inner side of a vehicle when the tire is mounted on the vehicle, and an outer tread rubber layer that forms an end portion on an outer side of the vehicle, Distance between both ground edges W L The ratio of the distance D from the outer ground contact edge of the vehicle to the interface between the inner tread rubber layer and the outer tread rubber layer (D / W L ) is 0.50 or more, The interface divides the tread portion in the tire width direction into the inner tread rubber layer and the outer tread rubber layer, The average value tanδA of the loss tangent tanδ of the inner tread rubber layer measured under the conditions of a frequency of 10 Hz, an initial strain of 1%, and an amplitude of ±0.1% at 0°C to 50°C in is 0.30 or less, The average value tanδA of the loss tangent tanδ of the outer tread rubber layer measured under the conditions of a frequency of 10 Hz, an initial strain of 1%, and an amplitude of ±0.1% at 0°C to 50°C out A tire having a coefficient of friction of 0.40 or more.

2. The tire according to claim 1, wherein the rubber composition constituting the outer tread rubber layer contains 100 parts by mass or more of carbon black per 100 parts by mass of the rubber component.

3. 3. The tire according to claim 1, wherein the rubber composition constituting the outer tread rubber layer contains 70 parts by mass or more of a softener per 100 parts by mass of the rubber component.

4. The tire according to any one of claims 1 to 3, wherein a rubber composition constituting the outer tread rubber layer contains an aromatic petroleum resin.

5. The tire according to any one of claims 1 to 4, wherein the rubber composition constituting the inner tread rubber layer contains 40 parts by mass or more of silica per 100 parts by mass of the rubber component.

6. The tire according to any one of claims 1 to 5, wherein a groove area ratio of the ground contact surface of the outer tread rubber layer is smaller than a groove area ratio of the ground contact surface of the inner tread rubber layer.

7. The tire according to any one of claims 1 to 6, wherein a difference between a groove area ratio of the contact surface of the outer tread rubber layer and a groove area ratio of the contact surface of the inner tread rubber layer is 2% or more and 10% or less.

8. The tire according to claim 1, wherein tan δA out is 0.42 or more.

9. The tire according to claim 1, wherein D / W L is 0.52 or more.

10. tan δA out and D / W L The tire according to any one of claims 1 to 9, wherein the following formula (1) is satisfied: Equation (1) tanδA out × (D / W L ) ≥ 0.30

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