tire

Abstract

To improve steering stability during high-speed traveling, especially responsiveness at the time of entering a corner.SOLUTION: A tire includes a tread part. A cap rubber layer forming the tread part is formed from a rubber composition which contains 80 pts.mass or more and 100 pts.mass or less of styrene-butadiene rubber (SBR) with a styrene content of 25 mass% or less, in 100 pts.mass of a rubber component, and which contains 100 pts.mass or less of silica with respect to 100 pts.mass of the rubber component. The rubber composition has a complex elastic modulus (30°C E*) of greater than 8.0 MPa as measured in a deformation mode of extension under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%. The tread part has a thickness of 8.5 mm or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Tires are required to have excellent handling stability from the standpoint of safety.

[0003] Therefore, various techniques have been proposed to improve the driving stability by improving the grip performance (for example, Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-93386 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-79017 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-133845 [Patent Document 4] JP 2016-37100 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the recent development of expressways, it is not uncommon to travel long distances on expressways, and it is therefore believed that there is a strong demand for the above-mentioned conventional technology to further improve handling stability during high-speed driving, particularly responsiveness when entering corners.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to improve the handling stability during high speed driving, and in particular the responsiveness when entering a corner. [Means for solving the problem]

[0007] The present invention provides A tire having a tread portion, A cap rubber layer forming the tread portion is A styrene-butadiene rubber (SBR) having a styrene content of 25% by mass or less is contained in an amount of 80 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the rubber component, The rubber composition contains 100 parts by mass or less of silica per 100 parts by mass of the rubber component, The complex modulus of elasticity (30℃E) measured under the conditions of temperature 30℃, frequency 10Hz, initial strain 5%, dynamic strain rate 1%, deformation mode: extension * ) is formed from a rubber composition having a modulus of elasticity of more than 8.0 MPa, The tire is characterized in that the thickness of the tread portion is 8.5 mm or less. [Effects of the Invention]

[0008] According to the present invention, it is possible to improve the handling stability during high-speed driving, and in particular the responsiveness when entering a corner. DETAILED DESCRIPTION OF THE INVENTION

[0009] [1] Characteristics of the tire according to the present invention First, the features of the tire according to the present invention will be described.

[0010] 1. Overview The tire according to the present invention is a tire having a tread portion, and the cap rubber layer forming the tread portion is formed from a rubber composition containing 80 parts by mass or more and 100 parts by mass or less of styrene butadiene rubber (SBR) with a styrene content of 25% by mass or less per 100 parts by mass of the rubber component, and 100 parts by mass or less of silica per 100 parts by mass of the rubber component. The complex modulus (30°C E) of this rubber composition measured in a deformation mode: elongation under conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1% is * ) exceeds 8.0 MPa. The thickness of the tread portion is 8.5 mm or less.

[0011] The cap rubber layer referred to here is not limited to the cap rubber layer that forms the outermost layer of the tread portion, and if there are two or more layers within 5 mm from the tread surface toward the inside, at least one of the layers must satisfy the requirements of the rubber composition.

[0012] These features make it possible to improve the handling stability during high-speed driving, and in particular the responsiveness when entering a corner, as will be described later.

[0013] 2. Mechanism of effect manifestation in the tire according to the present invention The mechanism by which the above-described effects of the tire according to the present invention are exhibited is believed to be as follows.

[0014] (1) Contains low-styrene SBR As described above, the cap rubber layer of the tire according to the present invention is formed from a rubber composition containing 80 parts by mass or more and 100 parts by mass or less of SBR with a styrene content of 25% by mass or less per 100 parts by mass of the rubber component.

[0015] SBR with a low styrene content, specifically, 25% by mass or less, has a low glass transition temperature (Tg). Therefore, by including 80 parts by mass or more and 100 parts by mass or less in 100 parts by mass of the rubber component and forming the majority of the cap rubber layer, the Tg of the entire rubber composition can be lowered, the mobility of the polymer can be increased, and the ability to follow the road surface can be improved. It is believed that this improves handling stability during high-speed driving, particularly responsiveness when entering corners.

[0016] Furthermore, SBR with a low styrene content forms tiny styrene domains within the rubber matrix, which make it easier for heat to be generated through friction in the domains when input is applied from the road surface. This improves the tire's ability to follow the road surface and improves handling stability at high speeds, particularly responsiveness when entering corners.

[0017] In the present invention, the styrene content is more preferably 20% by mass or less, and even more preferably 15% by mass or less, while the lower limit is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 8% by mass or more.

[0018] The phrase "containing 80 parts by mass or more of SBR with a styrene content of 25% by mass or less per 100 parts by mass of the rubber component" means that the amount of SBR per 100 parts by mass of the rubber component is 80 parts by mass or more, and the amount of styrene in the total SBR is 25% by mass or less.

[0019] In other words, when the rubber component contains only one styrene-containing polymer (SBR), it indicates that the styrene content is 25% by mass or less, and when the rubber component contains multiple styrene-containing polymers (SBR), it indicates that the styrene content calculated by summing the product of the styrene content (% by mass) in each polymer and the blending amount (parts by mass) of that polymer per 100 parts by mass of the rubber component is 25% by mass or less.

[0020] More specifically, when 100 parts by mass of the rubber component contains SBR1 (X1 parts by mass) with a styrene content of S1% by mass and SBR2 (X2 parts by mass) with a styrene content of S2% by mass, the styrene content calculated from the formula {(S1×X1)+(S2×X2)} / (X1+X2) is 25% by mass or less.

[0021] In addition, in the rubber composition after vulcanization, the amount of styrene can also be calculated by determining the amount of styrene contained in the rubber component after acetone extraction using solid-state nuclear magnetic resonance (solid-state NMR) or Fourier transform infrared spectrophotometer (FTIR).

[0022] In the present invention, the amount of SBR in 100 parts by mass of the rubber component is more preferably 85 parts by mass or more, and further preferably 90 parts by mass or more.

[0023] (2) Silica content In the cap rubber layer of the tire according to the present invention, the silica content is 100 parts by mass or less per 100 parts by mass of the rubber component, an amount that does not exceed the rubber component. This facilitates uniform dispersion of silica in the rubber matrix, resulting in a homogenized rubber composition and improved road conformity. Furthermore, a silica network is easily formed in the rubber matrix, providing sufficient rubber reinforcement and improving force transmission within the tire. This is believed to result in improved handling stability during high-speed driving, particularly responsiveness when entering corners.

[0024] In the present invention, the content of silica is more preferably 98 parts by mass or less per 100 parts by mass of the rubber component, while the lower limit is preferably 75 parts by mass or more, more preferably 80 parts by mass or more, and even more preferably 90 parts by mass or more, in consideration of reinforcing properties of the rubber.

[0025] (3) Complex modulus (30℃E * ) In the present invention, the complex modulus of elasticity (30°C E) of the rubber composition forming the cap rubber layer is measured at a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode of elongation. * ) is set to be over 8.0 MPa.

[0026] The complex modulus is a parameter that indicates the rigidity of the rubber layer. * By making the modulus of elasticity exceed 8.0 MPa, the rigidity of the entire rubber can be improved, which is thought to produce a large reaction force from a macroscopic perspective, improving the handling stability during high-speed driving, and in particular the responsiveness when entering corners.

[0027] In the present invention, the above-mentioned 30°C * is more preferably greater than 8.5 MPa, and even more preferably greater than 9.0 MPa. On the other hand, in consideration of exhibiting appropriate conformability, the upper limit is preferably 11.0 MPa or less, more preferably 10.0 MPa or less, and even more preferably 9.5 MPa or less.

[0028] Here, the "complex modulus" can be measured using a viscoelasticity measuring device such as "IPLEXER (registered trademark)" manufactured by GABO.

[0029] Complex modulus of elasticity of rubber layer (30℃E * ) can be adjusted appropriately by mixing the ingredients described below. Specifically, it can be adjusted by increasing the ratio of fillers such as silica and carbon black, reducing the amount of plasticizer components such as oil, increasing the amount of resin components, or increasing the amount of vulcanizing agents such as sulfur and accelerators.

[0030] (4) Tread thickness Furthermore, in the tire according to the present invention, the thickness of the tread portion is made thin, at 8.5 mm or less, which is believed to further improve the rigidity of the tread portion, increase the force transmission inside the tire, and increase the rigidity in the shear direction, thereby improving the handling stability during high-speed driving, especially the responsiveness when entering corners.

[0031] In the present invention, the thickness of the tread portion is more preferably 8.0 mm or less, while the lower limit is preferably 7.0 mm or more, and more preferably 7.5 mm or more.

[0032] In the present invention, the tread portion is a region that forms the contact surface of the tire, and refers to the portion radially outward of components containing fiber materials such as the carcass, belt layer, and belt reinforcing layer.

[0033] The "tread thickness" refers to the thickness of the tread at the tire equatorial plane in a radial cross section of the tire. When the tread is formed from a single rubber composition, it refers to the thickness of that rubber composition. When the tread is formed from a laminated structure of multiple rubber compositions (described below), it refers to the total thickness of those layers. When the tire has grooves on the equatorial plane, it refers to the thickness from the intersection of a line connecting the radially outermost endpoints of the grooves with the tire equatorial plane to the radially innermost interface of the tread. The tread thickness can be measured by aligning the bead portion with the normal rim width in a radial cross section of the tire.

[0034] "Genuine rim" refers to the rim specified for each tire in 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 Tire and Rim Technical Organization), it refers to the "Measuring Rim" listed in the "Standards Manual." For TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "Year Book." JATMA, ETRTO, and TRA are referenced in that order, and if an applicable size is available at the time of reference, that standard is followed. For tires not specified in the standard, it refers to the rim that can be mounted on the rim and can maintain internal pressure, i.e., the rim with the smallest rim diameter and the next narrowest rim width, among rims that do not leak air between the rim and tire.

[0035] As described above, in the tire according to the present invention, the effects (1) to (4) work together to suppress slippage with the road surface due to the microscopic mobility, high heat generation, and tracking ability of the rubber matrix itself, and at the same time, from a macroscopic perspective, appropriate rigidity and ease of force transmission can be obtained, making it easy to generate a reaction force, so that the tire has excellent responsiveness when turning the steering angle and entering a corner while traveling at high speed, and it is thought that this improves handling stability during high-speed traveling.

[0036] [2] More preferred embodiments of the tire according to the present invention The tire according to the present invention can achieve even greater effects by adopting the following aspects.

[0037] 1. Loss tangent of the cap rubber layer at 30°C (30°C tanδ) In the present invention, the rubber composition forming the cap rubber layer preferably has a loss tangent (30°C tanδ) measured in tension under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%, of 0.25 or less, and more preferably 0.20 or less.

[0038] The loss tangent (tanδ) can be considered a parameter that represents the phase difference between the input and response of rubber, and by reducing the loss tangent at the frequency / temperature corresponding to rolling, i.e., 30°C tanδ, to 0.25 or less, the phase difference between input and response is reduced, improving responsiveness and therefore further improving handling stability during high-speed driving. Note that the lower limit is not particularly limited, but is preferably 0.15 or more, more preferably 0.16 or more, and even more preferably 0.18 or more.

[0039] Here, the "loss tangent (tan δ)" can be measured using a viscoelasticity measuring device such as "IPLEXER (registered trademark)" manufactured by GABO, in the same manner as in the measurement of the "complex modulus" described above.

[0040] Furthermore, the 30°C tan δ can be adjusted appropriately by mixing the ingredients described below, and can be lowered by reducing the styrene content in the SBR component, reducing the resin component, reducing the amount of fillers such as silica and carbon black, or increasing the amount of sulfur or vulcanization accelerator.

[0041] 2. Multi-layered tread In the present invention, the tread portion may be formed of only one layer, a cap rubber layer, or may be formed of two layers, such as a cap rubber layer, with a base rubber layer provided inside the cap rubber layer, or may be formed of three layers, four layers, or more. In this case, the thickness of the cap rubber layer in the entire tread portion is preferably 10% or more. This is thought to further improve steering stability during high-speed driving, as it enables sufficient friction to be generated between the tread surface and the road surface and sufficient frictional force to be transmitted to the inside of the tire during high-speed driving. A thickness of 70% or more is more preferable.

[0042] As described above, when the tire is formed with a laminated structure of multiple rubber compositions, the "thickness of the tread portion" refers to the total thickness of the laminated layers. When the tire has grooves on the equatorial plane, the "thickness of the tread portion" refers to the thickness from the intersection of the tire equatorial plane with a line connecting the outermost end points of the grooves in the radial direction of the tire to the innermost interface of the tread portion in the radial direction of the tire.

[0043] In this case, it is preferable that the 30°C tan δ of the base rubber layer is smaller than the 30°C tan δ of the cap rubber layer, which is believed to improve responsiveness by reducing the phase difference between the grip performance generated by the cap rubber layer and the response inside the tire, thereby further improving steering stability during high-speed driving.

[0044] In addition, the base rubber layer is 30°C * is the temperature of the cap rubber layer at 30℃E *This makes it easier for the tire to deform inside the tread portion and makes it easier for the entire tread surface to contact the road surface, which is thought to make it easier to further improve steering stability during high-speed driving.

[0045] In addition, the base rubber layer is * and 30° C. tan δ can be adjusted in the same manner as in the cap rubber layer described above.

[0046] 3. Particle size of silica contained in the cap rubber layer In the present invention, the particle size (average primary particle size) of silica contained in the cap rubber layer is preferably 17 nm or less from the viewpoint of improving reinforcing properties.

[0047] The average primary particle diameter can be calculated by directly observing silica particles extracted from a rubber composition cut out from a tire using a transmission electron microscope (TEM) or the like, calculating the equivalent cross-sectional area diameter from the area of ​​each silica particle obtained, and determining the average value.

[0048] 4. Resin component content in the cap rubber layer In the present invention, the rubber composition forming the cap rubber layer preferably contains a resin component.

[0049] It is believed that by including a resin component in the rubber composition, the adhesiveness of the resin component ensures grip on the road surface even during high-speed driving, thereby further improving steering stability during high-speed driving.

[0050] Preferred resin components include rosin resins, styrene resins, coumarone resins, terpene resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, which will be described later. Among these, styrene resins such as α-methylstyrene are more preferred. The content per 100 parts by mass of the rubber component is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 35 parts by mass or more. In consideration of softening of the rubber, the upper limit is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0051] 5. Acetone extractables (AE) of the cap rubber layer In the present invention, from the viewpoint of exhibiting excellent handling stability through stable grip performance during high-speed driving, the acetone extractables (AE) of the cap rubber layer is preferably 12% by mass or more, more preferably 14% by mass or more, and even more preferably 16% by mass or more, while the upper limit is preferably 23% by mass or less, more preferably 20% by mass or less, even more preferably 19% by mass or less, and even more preferably 18% by mass or less.

[0052] Acetone extractables (AE) can be considered an index showing the amount of softeners in a rubber composition, and can also be considered an index showing the mobility of the molecular chains of the rubber composition. Therefore, by appropriately controlling the amount of AE in the cap rubber layer, it is possible to ensure a sufficient contact area between the tire and the road surface during high-speed driving, thereby achieving stable grip performance and excellent handling stability during high-speed driving.

[0053] The acetone extractables (AE) can be measured in accordance with JIS K 6229: 2015. Specifically, the AE (mass%) can be obtained by immersing a vulcanized rubber test piece cut out from the measurement site in acetone at room temperature and normal pressure for 72 hours and determining the mass loss rate (%) of the test piece.

[0054] More specifically, each vulcanized rubber test piece is immersed in acetone at room temperature and normal pressure for 72 hours to extract the soluble components, and the mass of each test piece is measured before and after extraction, and the mass can be calculated using the following formula. Acetone extractable amount (%) = (mass of rubber test piece before extraction - mass of rubber test piece after extraction) / (mass of rubber test piece before extraction)}×100

[0055] The acetone extractable content can be appropriately changed by changing the compounding ratio of the plasticizer in the rubber composition.

[0056] 6. Land Ratio In the tire according to the present invention, the land ratio in the tread portion of the tire mounted on a regular rim and pressurized to a regular internal pressure is preferably 55% or more, more preferably 60% or more, and even more preferably 63% or more.

[0057] The "land ratio" is the ratio of the actual contact area to the hypothetical contact area that would result from filling all of the grooves on the surface of the tread. A larger land ratio means a larger area in contact with the road, resulting in stable, sufficient grip performance and excellent handling stability.

[0058] The upper limit of the land ratio is not particularly limited, but is preferably 85% or less, more preferably 80% or less, and even more preferably 75% or less.

[0059] The land ratio can be determined from the ground contact shape under normal rim, normal internal pressure, and normal load conditions.

[0060] Specifically, a tire is mounted on a standard rim, pressurized to the standard internal pressure, and left to stand at 25°C for 24 hours. Then, ink is applied to the tire tread surface, and the standard load is applied and pressed onto cardboard (camber angle 0°). The contact shape can be obtained by transferring the tire to paper, and the tire is rotated 72° in circumferential directions, transferring the shape to five locations. In other words, five contact shapes are obtained. At this point, the five contact shapes are smoothly connected, with the grooves in the contact shape contours being smoothly joined, and the resulting shape is called the virtual contact surface.

[0061] The land ratio can be calculated by (average area of ​​five contact shapes (black parts) transferred to cardboard / average area of ​​virtual contact surface obtained from five contact shapes) x 100 (%).

[0062] "Regular internal pressure" refers to the air pressure specified for each tire by the standard. For JATMA, it refers to the maximum air pressure, for ETRTO, it refers to "INFLATION PRESSURE," and for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with "regular rims," ​​JATMA, ETRTO, and TRA are referenced in that order, and the standards are followed. For tires not specified in the standard, it refers to the regular internal pressure (250 KPa or higher) of another tire size (specified in the standard) that is specified with the regular rim as the standard rim. If multiple regular internal pressures of 250 KPa or higher are listed, it refers to the smallest value among them.

[0063] Furthermore, "normal load" refers to the load determined for each tire by each standard in the standard system, including the standard on which the tire is based, and refers to the maximum mass that can be loaded on the tire. In the case of JATMA, it refers to the maximum load capacity, in the case of ETRTO, it refers to the "LOAD CAPACITY", and in the case of TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". As with the above-mentioned "normal rim" and "normal internal pressure", JATMA, ETRTO, and TRA are referenced in that order and their standards are followed. In the case of tires not specified in the standard, the normal load W is calculated as follows: L Ask for. V={(Dt / 2) 2 -(Dt / 2-Ht) 2}×π×Wt W L =0.000011×V+175 W L :Normal load (kg) V: Virtual volume of the tire (mm 3 ) Dt: Tire outer diameter Dt (mm) Ht: tire section height (mm) Wt: tire cross-sectional width (mm)

[0064] 7. Land ratio of tread area and 30°C E of cap rubber layer * Relationship with In the tire according to the present invention, the land ratio R (%) in the tread portion and the complex modulus E at 30°C of the cap rubber layer are * As mentioned above, the land ratio is the contact area ratio of the tread portion, and the product of the 30°C E of the cap rubber layer is preferably 560 or more. * By making the product of x and y equal to or greater than 560, it is believed that the rigidity of the tread portion is improved, making it easier to improve the steering stability during high-speed driving.

[0065] The land ratio R and the cap rubber layer 30°C E *The product of is more preferably 580 or more, and even more preferably 600 or more. On the other hand, although there is no particular upper limit, it is preferably 800 or less, more preferably 750 or less, and even more preferably 700 or less.

[0066] 8. Tread thickness and 30°C E of the cap rubber layer * Relationship with In the tire according to the present invention, the 30°C E of the cap rubber layer relative to the thickness G (mm) of the tread portion is * (MPa) ratio (30℃E * / G) is preferably 1.00 or more. It is believed that the thicker the tread thickness G, the greater the deformation that occurs in the tread during cornering, and the lower the responsiveness. Therefore, it is preferable that the 30°C E of the cap rubber layer is set to 1.00 or more relative to the tread thickness G. * It is believed that by making the value of the tread width sufficiently high, the rigidity of the tread portion can be ensured and good responsiveness can be achieved.

[0067] In addition, the above-mentioned 30°C * / G is more preferably 1.05 or more, and even more preferably 1.10 or more. There is no particular upper limit, but it is preferably 3.00 or less, preferably 2.50 or less, and even more preferably 2.00 or less.

[0068] 9. Flatness The aspect ratio is the ratio of the tire's cross-sectional height to its cross-sectional width, and the smaller this ratio is, the smaller the proportion of the portion that deforms in the tire width direction relative to the friction generated in the tread, making it easier to transmit force, which increases stability and responsiveness at high speeds, improves steering sharpness, and improves handling stability at high speeds.On the other hand, a low aspect ratio reduces the amount of deflection at the side, which may lead to a deterioration in ride comfort.

[0069] Considering these points, it is preferable that the specific aspect ratio of the tire according to the present invention is 30% or more and 60% or less.

[0070] The aspect ratio (%) can be calculated using the following formula, using the tire cross-sectional height Ht (mm), cross-sectional width Wt (mm), tire outer diameter Dt (mm), and rim diameter R (mm) when the internal pressure is set to 250 kPa. Oblateness (%)=(Ht / Wt)×100(%) Ht=(Dt-R) / 2

[0071] [3] Implementation form The present invention will be specifically described below based on embodiments.

[0072] 1. Rubber composition for forming the cap rubber layer In the tire according to the present invention, the rubber composition forming the cap rubber layer can be obtained by appropriately adjusting the types and amounts of various compounding materials such as the rubber component, filler, plasticizer, vulcanizing agent, and vulcanization accelerator described below.

[0073] (1) Compounding materials (a) Rubber component In the present invention, styrene-butadiene rubber (SBR) is contained as the rubber component from the viewpoint of containing styrene in the rubber component, but styrene-based polymers other than SBR, such as styrene-butadiene-styrene block copolymer (SBS) and styrene-butadiene block copolymer (SB), may also be contained.

[0074] Furthermore, rubbers (polymers) commonly used in tire production, such as diene rubbers such as isoprene rubber, butadiene rubber (BR), and nitrile rubber (NBR), and butyl rubbers such as butyl rubber, may be used in combination with the styrene polymers described above. For example, a combination of SBR and BR, or a combination of SBR, BR, and isoprene rubber is preferred. These rubber components may be extended in advance with a plasticizer component such as oil, resin, or liquid rubber, as described below.

[0075] (a) SBR The weight-average molecular weight of the SBR is, for example, more than 100,000 and less than 2,000,000. As described above, in the present invention, the styrene content in the SBR component is 25% by mass or less. The vinyl content (1,2-bonded butadiene content) of the SBR is, for example, more than 5% by mass and less than 70% by mass. The vinyl content of the SBR refers to the 1,2-bonded butadiene content relative to the total butadiene moieties in the SBR component. The structure of the SBR (measurement of the styrene content and vinyl content) can be identified using, for example, a JNM-ECA series instrument manufactured by JEOL Ltd.

[0076] In the present invention, the content of SBR in 100 parts by mass of the rubber component is, as described above, 80 parts by mass or more and 100 parts by mass or less, more preferably 85 parts by mass or more, and even more preferably 90 parts by mass or more.

[0077] The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR). The SBR may be either unmodified or modified. Hydrogenated SBR, which is obtained by hydrogenating the butadiene portion of SBR, may also be used. Hydrogenated SBR may be obtained by subsequently hydrogenating the BR portion of SBR, or a similar structure may be obtained by copolymerizing styrene, ethylene, and butadiene.

[0078] The modified SBR may be any SBR having a functional group that interacts with a filler such as silica, and examples thereof include terminal-modified SBR in which at least one terminal of SBR has been modified with a compound (modifier) ​​having the functional group (terminal-modified SBR having the functional group at the terminal), main-chain-modified SBR in which the functional group is present in the main chain, main-chain terminal-modified SBR in which the functional group is present in the main chain and at least one terminal (for example, SBR having the functional group in the main chain and at least one terminal modified with the modifier), and terminal-modified SBR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or epoxy group introduced therein.

[0079] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, etc. These functional groups may have a substituent.

[0080] Furthermore, as the modified SBR, for example, SBR modified with a compound (modifying agent) represented by the following formula can be used.

[0081] [ka]

[0082] In the formula, R 1 , R 2 and R 3 R may be the same or different and represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or a derivative thereof. 4 and R 5 are the same or different and represent a hydrogen atom or an alkyl group. 4 and R 5 may bond to form a ring structure together with the nitrogen atom, and n represents an integer.

[0083] As the modified SBR modified with a compound (modifier) ​​represented by the above formula, SBR in which the polymerization terminals (active terminals) of solution-polymerized styrene-butadiene rubber (S-SBR) have been modified with a compound represented by the above formula (such as the modified SBR described in JP 2010-111753 A).

[0084] R 1 , R 2 and R 3R is preferably an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). 4 and R 5 is preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. In addition, R 4 and R 5 When the groups bond to form a ring structure together with the nitrogen atom, the ring is preferably a 4- to 8-membered ring. The alkoxy group also includes a cycloalkoxy group (such as a cyclohexyloxy group) and an aryloxy group (such as a phenoxy group or a benzyloxy group).

[0085] Specific examples of the modifying agent include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. These may be used alone or in combination of two or more.

[0086] Modified SBR may also be modified with the following compounds (modifiers): Examples of the modifier include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups, such as diglycidylated bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline; Diglycidyl amino compounds such as diglycidyl orthotoluidine, tetraglycidyl meta-xylenediamine, tetraglycidyl aminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidyl aminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamic acid chloride, and N,N-diethylcarbamic acid chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane;(Trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(trippropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxy sulfide group-containing silane compounds such as (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, Alkoxysilanes such as thyltriethoxysilane; (thio)benzophenone compounds having an amino group and / or a substituted amino group such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, and N,N,N',N'-bis-(tetraethylamino)benzophenone; 4-N,N- Benzaldehyde compounds having an amino group and / or a substituted amino group, such as dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones, such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidones, such as N-methyl-2-piperidone, N-vinyl-2-piperidone, and N-phenyl-2-piperidone;N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurylolactam, N-vinyl-ω-laurylolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam; as well as N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), and tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-trione , N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophen, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone, etc. Modification with the above compounds (modifiers) can be carried out by known methods.

[0087] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used. The SBR may be used alone or in combination of two or more types.

[0088] (b)BR In the present invention, the rubber composition may contain BR as needed. In this case, the amount of BR per 100 parts by mass of the rubber component is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less.

[0089] The weight-average molecular weight of the BR is, for example, more than 100,000 and less than 2,000,000. The vinyl content of the BR is, for example, more than 1% by mass and less than 30% by mass. The cis content of the BR is, for example, more than 1% by mass and less than 98% by mass. The trans content of the BR is, for example, more than 1% by mass and less than 60% by mass.

[0090] The BR is not particularly limited, and can be a BR with a high cis content (cis content of 90% or more), a BR with a low cis content, or a BR containing syndiotactic polybutadiene crystals. The BR can be either unmodified or modified, and examples of modified BR include modified BRs into which the above-mentioned functional groups have been introduced. These can be used alone or in combination of two or more. The cis content can be measured by infrared absorption spectroscopy.

[0091] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0092] (c) Isoprene rubber In the present invention, the rubber composition may contain an isoprene-based rubber as needed. In this case, the content of the isoprene-based rubber per 100 parts by mass of the rubber component is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less.

[0093] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR.

[0094] Examples of NR that can be used include those commonly used in the tire industry, such as SIR20, RSS#3, TSR20, and SVR-L. Examples of IR are not particularly limited, and examples of IR that can be used include those commonly used in the tire industry, such as IR2200. Examples of modified NR include deproteinized natural rubber (DPNR) and highly purified 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 alone or in combination of two or more.

[0095] (d) Other rubber components Furthermore, rubber (polymer) generally used in the manufacture of tires, such as nitrile rubber (NBR), may be included as a rubber component other than those mentioned above.

[0096] (b) Compounding materials other than rubber components (a) Filler In the present invention, the rubber composition contains silica as a filler as described above, but may contain other fillers. Specific examples of fillers other than silica include carbon black, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, and biochar.

[0097] (i-1) Silica In the present invention, the content of silica is, as described above, 100 parts by mass or less, and more preferably 98 parts by mass or less, per 100 parts by mass of the rubber component.

[0098] In the present invention, the BET specific surface area of ​​the silica contained in the rubber composition is 140 m from the viewpoint of obtaining good durability. 2 / g, and preferably more than 160m 2 / g or more is more preferable, and 180m 2 On the other hand, from the viewpoint of obtaining good rolling resistance during high-speed running, it is more preferable that the fine particle silica has a density of more than 300m 2 / g or less. The BET specific surface area is the N2SA value measured by the BET method in accordance with ASTM D3037-93.

[0099] In the present invention, as described above, it is preferable to use silica having a particle size of 17 nm or less in the rubber composition. By using silica having a small particle size, the frequency of contact with the polymer (styrene domain) can be increased, thereby improving reinforcement. Although the lower limit is not particularly limited, it is preferable that it be 10 nm or more from the viewpoint of dispersibility during mixing.

[0100] Examples of silica include dry process silica (anhydrous silica) and wet process silica (hydrated silica). Among them, wet process silica is preferred because it has a large number of silanol groups. Silica made from hydrous glass or silica made from biomass materials such as rice husks may also be used.

[0101] As silica, for example, products from Evonik Industries, Rhodia, Tosoh Silica Corporation, Solvay Japan, Tokuyama Corporation, etc. can be used.

[0102] (i-2) Silane coupling agent The rubber composition of the present invention preferably contains a silane coupling agent together with silica.

[0103] The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocathanide, Examples of such compounds include sulfide-based compounds such as rubamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These compounds may be used alone or in combination of two or more.

[0104] As the silane coupling agent, for example, products from Evonik Industries, Momentive, Shin-Etsu Silicones Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Dow Corning Toray Co., Ltd., etc. can be used.

[0105] The content of the silane coupling agent is, for example, more than 3 parts by mass and less than 25 parts by mass relative to 100 parts by mass of silica.

[0106] (ii) Carbon black In the present invention, the rubber composition preferably contains carbon black from the viewpoint of reinforcement.

[0107] The specific content ratio of carbon black per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, and is preferably 35 parts by mass or less, more preferably 30 parts by mass or less.

[0108] The carbon black is not particularly limited, and examples thereof include furnace blacks (furnace carbon blacks) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black (acetylene carbon black); thermal blacks (thermal carbon blacks) such as FT and MT; and channel blacks (channel carbon blacks) such as EPC, MPC, and CC. These may be used alone or in combination of two or more.

[0109] The specific surface area of ​​carbon black CTAB (Cetyl Tri-methyl Ammonium Bromide) is 130m 2 / g or more is preferable, and 160m 2 / g or more is more preferable, and 170m 2 / g or more is more preferable. 2 / g or less is preferable, and 200m 2 / g or less is more preferable. The CTAB specific surface area is a value measured in accordance with ASTM D3765-92.

[0110] Specific carbon blacks are not particularly limited, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available carbon blacks include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These may be used alone or in combination of two or more.

[0111] (iii) Other fillers In addition to the silica and carbon black described above, the rubber composition may further contain, as necessary, fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc. The content of these fillers is, for example, more than 0.1 part by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0112] (b) Plasticizer component The rubber composition may contain oil, liquid rubber, and resin as plasticizer components to soften the rubber. The plasticizer components are components that can be extracted from vulcanized rubber with acetone. When the rubber composition contains the above-mentioned extensible rubber components, the extensible components contained therein are included in the plasticizer components. The total content of the plasticizer components is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, per 100 parts by mass of the rubber component. On the other hand, it is preferably 55 parts by mass or less, more preferably 50 parts by mass or less.

[0113] (i) Oil Examples of oils include mineral oils (commonly referred to as process oils), vegetable oils, and mixtures thereof. Examples of mineral oils (process oils) that can be used include paraffinic process oils, aromatic process oils, and naphthenic process oils, such as MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Examples of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These oils may be used alone or in combination. From the viewpoint of life cycle assessment, waste oils used as lubricating oils in rubber mixers or automobile engines, waste cooking oils, etc. may also be used as appropriate.

[0114] Specific examples of process oils (mineral oils) that can be used include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Corporation, H&R Corporation, Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and the like.

[0115] (ii) Liquid rubber The liquid rubber mentioned as a plasticizer is a polymer that is in a liquid state at room temperature (25°C) and is a rubber component that can be extracted by acetone from a vulcanized tire. Examples of liquid rubber include farnesene polymers, liquid diene polymers, and hydrogenated products thereof.

[0116] Farnesene polymers are polymers obtained by polymerizing farnesene, which has structural units based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene).

[0117] The farnesene-based polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

[0118] Examples of liquid diene polymers include liquid styrene butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene isoprene copolymer (liquid SIR).

[0119] The liquid diene polymer has a weight average molecular weight (Mw) of, for example, 1.0 × 10 in terms of polystyrene measured by gel permeation chromatography (GPC). 3 Super, 2.0×10 5 In this specification, the Mw of the liquid diene polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0120] The amount of the liquid rubber (total amount of the liquid farnesene polymer, liquid diene polymer, etc.) is, for example, more than 1 part by mass and less than 100 parts by mass per 100 parts by mass of the rubber component.

[0121] As the liquid rubber, for example, products of Kuraray Co., Ltd., Cray Valley Co., Ltd., etc. can be used.

[0122] (iii) Resin component The resin component also functions as a tackifier and may be solid or liquid at room temperature. Specific examples of the resin component include rosin-based resins, styrene-based resins, coumarone-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, and two or more of these may be used in combination. The content of the resin component is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 35 parts by mass or more, per 100 parts by mass of the rubber component. Considering the softening of the rubber, the upper limit is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0123] Rosin-based resins are resins whose main component is rosin acid, which is obtained by processing pine resin. These rosin-based resins (rosins) can be classified based on whether they are modified or not, and can be divided into unmodified rosin (unmodified rosin) and modified rosin (rosin derivatives). Examples of unmodified rosins include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. Modified rosin is a modification of unmodified rosin, and examples include rosin esters, unsaturated carboxylic acid-modified rosin esters, unsaturated carboxylic acid-modified rosin esters, rosin amide compounds, and rosin amine salts.

[0124] Styrenic resins are polymers that use styrene monomers as constituent monomers, and examples thereof include polymers obtained by polymerizing styrene monomers as the main component (50% by mass or more).Specific examples include homopolymers obtained by polymerizing styrene monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) individually, copolymers obtained by copolymerizing two or more styrene monomers, and copolymers of styrene monomers and other monomers that can be copolymerized with them.

[0125] Examples of the other monomers include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene and butadiene isoprene, olefins such as 1-butene and 1-pentene, α,β-unsaturated carboxylic acids such as maleic anhydride or acid anhydrides thereof, and the like.

[0126] Among the coumarone resins, coumarone-indene resins are preferred. Coumarone-indene resins are resins containing coumarone and indene as monomer components that constitute the resin skeleton (main chain). Monomer components contained in the skeleton other than coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0127] The amount of the coumarone-indene resin per 100 parts by mass of the rubber component is, for example, more than 1.0 part by mass and less than 50.0 parts by mass.

[0128] The hydroxyl value (OH value) of the coumarone-indene resin is, for example, more than 15 mgKOH / g and less than 150 mgKOH / g. The OH value is the amount of potassium hydroxide, expressed in milligrams, required to neutralize acetic acid bonded to hydroxyl groups when acetylating 1 g of the resin, and is a value measured by potentiometric titration (JIS K 0070:1992).

[0129] The softening point of the coumarone-indene resin is, for example, more than 30° C. and less than 160° C. The softening point is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point tester.

[0130] Terpene resins include polyterpenes, terpene phenols, and aromatic modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenated products. Terpene compounds are (C5H8) n The hydrocarbons and their oxygen-containing derivatives are represented by the following composition: monoterpenes (C10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0131] Examples of polyterpenes include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin, which are made from the above-mentioned terpene compounds, as well as hydrogenated terpene resins obtained by hydrogenating the terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the above-mentioned terpene compounds with phenolic compounds, and resins obtained by hydrogenating the above-mentioned resins. Specific examples include resins obtained by condensing the above-mentioned terpene compounds, phenolic compounds, and formalin. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Examples of aromatic-modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the above-mentioned resins. The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring, and examples thereof include phenolic compounds such as phenol, alkylphenol, alkoxyphenol, and unsaturated hydrocarbon group-containing phenol; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and unsaturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; coumarone, indene, and the like.

[0132] "C5 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 a C5 petroleum resin.

[0133] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a hydrogenated or modified version. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of suitable aromatic vinyl resins include coumarone-indene resins, coumarone resins, indene resins, and aromatic vinyl resins. Preferred aromatic vinyl resins are homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene, with copolymers of α-methylstyrene and styrene being more preferred, due to their economical efficiency, ease of processing, and excellent heat generation properties. Examples of aromatic vinyl resins that can be used include those commercially available from Kraton, Eastman Chemical Company, and the like.

[0134] "C5C9 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 C5 fractions and C9 fractions include the petroleum fractions mentioned above. As the C5C9 resin, for example, commercially available products from Tosoh Corporation, LUHUA, etc. can be used.

[0135] The acrylic resin is not particularly limited, but for example, a solventless acrylic resin can be used.

[0136] Examples of solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized by high-temperature continuous polymerization (high-temperature continuous bulk polymerization) (methods described in U.S. Pat. No. 4,414,370, JP-A Nos. 59-6207, JP-B Nos. 5-58005, 1-313522, U.S. Pat. No. 5,010,166, and Toa Gosei Kenkyusho Annual Report TREND 2000, Vol. 3, pp. 42-45, etc.), with minimal use of secondary raw materials such as polymerization initiators, chain transfer agents, and organic solvents. In the present invention, (meth)acrylic refers to both methacrylic and acrylic.

[0137] Examples of the monomer components constituting the acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylic acid derivatives such as (meth)acrylamide derivatives.

[0138] Furthermore, aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene may be used together with (meth)acrylic acid or a (meth)acrylic acid derivative as a monomer component constituting the acrylic resin.

[0139] The acrylic resin may be a resin composed solely of a (meth)acrylic component, or a resin containing components other than a (meth)acrylic component, and may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

[0140] As the resin component, for example, products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Co., Ltd., etc. can be used.

[0141] (c) Stearic acid In the present invention, the rubber composition preferably contains stearic acid. The content of stearic acid is, for example, more than 0.5 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component. As the stearic acid, conventionally known stearic acids can be used, such as products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc.

[0142] (d) Antiaging agents In the present invention, the rubber composition preferably contains an antioxidant. The content of the antioxidant is, for example, more than 0.5 parts by mass and less than 10 parts by mass, and more preferably 1 part by mass or more, per 100 parts by mass of the rubber component.

[0143] Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine. Examples of antioxidants include p-phenylenediamine antioxidants such as quinolone; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. These antioxidants may be used alone or in combination of two or more.

[0144] As the antioxidant, for example, products available from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, etc. can be used.

[0145] (E) Wax In the present invention, the rubber composition preferably contains wax. The content of the wax per 100 parts by mass of the rubber component is, for example, 0.5 to 20 parts by mass, preferably 1.0 to 15 parts by mass, and more preferably 1.5 to 10 parts by mass.

[0146] The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as vegetable wax and animal wax; and synthetic waxes such as polymers of ethylene, propylene, etc. These may be used alone or in combination of two or more.

[0147] As the wax, for example, products from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used.

[0148] (f) Zinc oxide The rubber composition may contain zinc oxide. The content of zinc oxide is, for example, more than 0.5 parts by mass and less than 10 parts by mass per 100 parts by mass of the rubber component. As the zinc oxide, a conventionally known product can be used, such as products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc.

[0149] (g) Crosslinking agents and vulcanization accelerators The rubber composition preferably contains a crosslinking agent such as sulfur, etc. The content of the crosslinking agent is, for example, more than 0.1 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0150] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. These may be used alone or in combination of two or more.

[0151] As sulfur, for example, products from Tsurumi Chemical Industry Co., Ltd., Karuizawa Iso Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0152] Examples of crosslinking agents other than sulfur include vulcanizing agents containing sulfur atoms, such as Tackirol V200 manufactured by Taoka Chemical Co., Ltd. and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by Lanxess, and organic peroxides, such as dicumyl peroxide.

[0153] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator is, for example, more than 0.3 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0154] Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more.

[0155] (H) Other In addition to the above components, the rubber composition may further contain, as necessary, additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, organic peroxides, reversion (reversion) inhibitors, etc. The content of these additives is, for example, more than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0156] (2) Preparation of rubber composition The rubber composition that forms the cap rubber layer is prepared by appropriately adjusting the various compounding materials described above and using a general method, for example, a manufacturing method including a base kneading step in which the rubber component is kneaded with a filler such as silica, and a finish kneading step in which the kneaded product obtained in the base kneading step is kneaded with a crosslinking agent.

[0157] The kneading can be carried out using a known (internal) kneading machine such as a Banbury mixer, a kneader, or an open roll.

[0158] The kneading temperature in the base kneading step is, for example, higher than 50° C. and lower than 200° C., and the kneading time is, for example, higher than 30 seconds and lower than 30 minutes. In the base kneading step, in addition to the above components, compounding agents conventionally used in the rubber industry, for example, plasticizer components such as oil, zinc oxide, antioxidants, waxes, vulcanization accelerators, etc., may be appropriately added and kneaded as needed.

[0159] In the final kneading step, the kneaded product obtained in the base kneading step is kneaded with a crosslinking agent. The kneading temperature in the final kneading step is, for example, higher than room temperature and lower than 80°C, and the kneading time is, for example, longer than 1 minute and shorter than 15 minutes. In the final kneading step, in addition to the above components, a vulcanization accelerator, zinc oxide, etc. may be appropriately added and kneaded as necessary.

[0160] 2. Tire manufacturing The tire according to the present invention can be produced as an unvulcanized tire by molding the rubber composition obtained above into a tread rubber of a predetermined shape as a cap rubber layer, and then molding it together with other tire components in a tire building machine by a conventional method.

[0161] When the tread portion has a multi-layer structure with a base rubber layer, the rubber composition for forming the base rubber layer can be basically obtained by similarly kneading the above-mentioned rubber components and compounding materials, appropriately changing the compounding amounts thereof, and extruding the base rubber composition together with the cap rubber layer to form a tread rubber of a predetermined shape, and then molding the tread rubber together with other tire components in a tire building machine by a normal method to produce an unvulcanized tire.

[0162] Specifically, an inner liner as a component for ensuring the airtightness of the tire, a carcass as a component for withstanding the load, impact, and inflation pressure to which the tire is subjected, and a belt component as a component for tightly fastening the carcass and increasing the rigidity of the tread are wound around a forming drum, and both ends of the carcass are fixed to both side edges, and bead portions as components for fixing the tire to the rim are arranged. After forming into a toroidal shape, a tread is attached to the center of the outer periphery and sidewalls are attached to the radially outer sides to form side portions, thereby producing an unvulcanized tire.

[0163] The unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire. The vulcanization process can be carried out by using a known vulcanization method. The vulcanization temperature is, for example, greater than 120°C and less than 200°C, and the vulcanization time is, for example, greater than 5 minutes and less than 15 minutes.

[0164] The resulting tire has the cooperation of the effects (1) to (4) described in "2. Mechanism of Effect Expression in Tire According to the Present Invention" above, which allows the rubber matrix itself to have high microscopic mobility and heat generation properties and to easily transmit force, while from a macroscopic perspective, it has the ability to follow the road surface due to appropriate rigidity and to easily generate reaction forces due to the ease of force transmission, resulting in excellent responsiveness when turning at a steering angle while driving at high speed and allowing for sufficient improvement in handling stability during high-speed driving.

[0165] The tire according to the present invention is not particularly limited to a particular category and can be used as a passenger car tire, a tire for heavy load vehicles such as trucks and buses, a two-wheeled vehicle tire, a run-flat tire, a non-pneumatic tire, etc., but is preferably used as a passenger car tire. Also, it is preferably used as a pneumatic tire. [Example]

[0166] Below, examples (working examples) that are considered preferable for carrying out the present invention are shown, but the scope of the present invention is not limited to these working examples. In the working examples, pneumatic tires (tire size 225 / 45R17, aspect ratio: 45%) manufactured from compositions obtained by varying the formulation according to each table using the various chemicals shown below were examined, and the results calculated based on the following evaluation methods are shown in Tables 2 to 4.

[0167] 1. Rubber composition for forming the cap rubber layer (1) Compounding materials (a) Rubber component (A) SBR-1: Modified S-SBR obtained by the method shown below (Production Example 1) (styrene content: 45% by mass, vinyl content: 35% by mass) (ii) SBR-2: Modified S-SBR obtained by the method shown in the following (Production Example 2) (styrene content: 25% by mass, vinyl content: 25% by mass) (c) SBR-3: HPR840 (S-SBR) manufactured by JSR Corporation (styrene content: 10% by mass, vinyl content: 42% by mass) (d) BR: Ubepol BR150B (High Sys BR) manufactured by Ube Industries, Ltd. (cis content 97% by mass, trans content 2% by mass, vinyl content 1% by mass)

[0168] (Production Example 1) The SBR-1 is prepared according to the following procedure. First, cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium is added to initiate polymerization. Polymerization is carried out under adiabatic conditions, with a maximum temperature of 85°C. When the polymerization conversion rate reaches 99%, butadiene is added and polymerization is continued for an additional 5 minutes. After that, methyltrimethoxysilane is added as a modifier and the reaction is continued for 15 minutes. After the polymerization reaction is complete, 2,6-di-tert-butyl-p-cresol is added. Next, the solvent is removed by steam stripping, and the mixture is dried on a heated roll heated to 110°C to obtain SBR-1.

[0169] (Production Example 2) The SBR-2 is prepared according to the following procedure. First, two 10 L reactors, each equipped with a jacket and an inlet at the bottom and an outlet at the top, are connected in series. Butadiene, styrene, and cyclohexane are mixed in the specified ratios. This mixture is passed through a dehydration column packed with activated alumina and mixed with n-butyllithium in a static mixer to remove impurities. The mixture is then continuously fed into the bottom of the first reactor. 2,2-bis(2-oxolanyl)propane as a polar substance and n-butyllithium as a polymerization initiator are continuously fed into the bottom of the first reactor at specified rates, while the reactor temperature is maintained at 95°C. The polymer solution is continuously withdrawn from the top of the reactor and fed into the second reactor. The temperature of the second reactor is maintained at 95°C, and a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane (monomer) as a modifier and oligomer components is continuously added at a predetermined rate as a 1000-fold diluted solution of cyclohexane to carry out the modification reaction. This polymer solution is continuously withdrawn from the reactor, and after continuous addition of an antioxidant using a static mixer, the solvent is removed to obtain SBR-2.

[0170] The vinyl content (unit: mass%) of SBR-1 and SBR-2 obtained above was determined by infrared spectroscopy at the absorption peak of the vinyl group at 910 cm -1The amount of styrene (unit: mass%) is determined from the refractive index in accordance with JIS K6383 (1995).

[0171] (b) Compounding materials other than rubber components (a) Silica: Ultrasil VN3 manufactured by Evonik Industries (N2SA:175m 2 / g, average primary particle diameter: 15nm) (b) Carbon black: Diablack N220 manufactured by Mitsubishi Chemical Corporation (N2SA:115m 2 / g) (c) Silane coupling agent: Si69 manufactured by Evonik Industries (Bis(3-triethoxysilylpropyl)tetrasulfide) (d) Resin: T-REZ PR801 manufactured by ENEOS Corporation (Hydrogenated aromatic modified alicyclic hydrocarbon resin) (E) Oil: H&R VIVATEC 500 (TDAE oil) (f) Zinc oxide: Zinc oxide type 2 manufactured by Mitsui Mining & Smelting Co., Ltd. (G) Anti-aging agent-1: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd. (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) (H) Anti-aging agent-2: Antigen RD manufactured by Sumitomo Chemical Co., Ltd. (polymer of 2,2,4-trimethyl-1,2-dihydroquinoline) (i) Wax: Sunnock N (selected special wax) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (J) Stearic acid: Beaded stearic acid "Tsubaki" manufactured by NOF Corporation (k) Vulcanization accelerator 1: Noccela CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-cyclohexyl-2-benzothiazylsulfenamide (CBS)) (L) Vulcanization accelerator 2: Noxeler D manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N,N'-diphenylguanidine (DPG)) (W) Sulfur: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd.

[0172] (2) Rubber composition forming the cap rubber layer According to the formulations shown in Tables 2 to 4, materials other than sulfur and vulcanization accelerator are kneaded for 5 minutes at 150°C using a Banbury mixer to obtain a kneaded mixture. Each blend amount is in parts by mass.

[0173] Next, sulfur and a vulcanization accelerator are added to the kneaded mixture, and the mixture is kneaded for 5 minutes at 80°C using an open roll to obtain a rubber composition for forming the cap rubber layer.

[0174] 2. Rubber composition forming the base rubber layer In parallel, a rubber composition for forming the base rubber layer is obtained based on the formulation shown in Table 1 in the same manner as the rubber composition for forming the cap rubber layer.

[0175] [Table 1]

[0176] 3. Manufacturing of pneumatic tires Each rubber composition is extruded into a predetermined shape so that the (cap rubber layer / base rubber layer) ratio becomes 70 / 30, and a tread portion having a thickness shown in Tables 2 to 4 is manufactured.

[0177] Thereafter, the tire is laminated together with other tire components to form an unvulcanized tire, which is then press-vulcanized for 10 minutes under a condition of 170°C to produce pneumatic tires (test tires) of Examples 1 to 11 shown in Tables 2 and 3, and pneumatic tires (test tires) of Comparative Examples 1 to 5 shown in Table 4.

[0178] 4. Calculation of parameters (1) 30°C * A rubber test piece for viscoelasticity measurement was prepared by cutting out a piece of rubber from the cap rubber layer of the tread portion of each test tire, measuring 20 mm in length, 4 mm in width, and 2 mm in thickness, with the long side in the tire circumferential direction. Each rubber test piece was measured using an Iplexer series manufactured by GABO under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain of 1%, with a deformation mode of elongation at 30°C E * (MPa). * is set to 4.0 MPa.

[0179] (2) 30℃ tanδ A rubber test piece for viscoelasticity measurement was prepared by cutting a piece 20 mm long x 4 mm wide x 2 mm thick from the cap rubber layer of the tread portion of each test tire, with the long side in the tire circumferential direction. For each rubber test piece, the 30°C tan δ was measured using a GABO Iplexer series under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of 1%, and a deformation mode of tension. The 30°C tan δ of the base rubber layer was set to 0.07.

[0180] (3)AE Using a vulcanized rubber test piece cut out from the cap rubber layer of the tread portion of each test tire, the AE (mass%) is determined in accordance with JIS K 6229:2015.

[0181] (4) Land Ratio The land ratio R (%) is determined using the method described above.

[0182] (5) 30°C E * × Land ratio Cap rubber layer 30℃E * (MPa) and the land ratio R (%) at 30°C * (MPa) x land ratio (%).

[0183] (6) 30°C E * × Tread thickness G (mm) Cap rubber layer 30℃E * (MPa) and tread thickness G (mm) at 30°C E * / Calculate the tread thickness G (mm).

[0184] 5. Performance evaluation test (evaluation of handling stability at high speeds) Each test tire was fitted to all wheels of a vehicle (a domestically produced FF vehicle with an engine displacement of 2000cc), and the internal pressure was inflated to the standard level. After a break-in run on a dry test course, the vehicle was driven at approximately 120km / h, and 20 drivers each performed a sensory evaluation on a 5-point scale (the higher the number, the better) of the stability of steering control when entering a corner. The total score of the 20 drivers' evaluations was then calculated.

[0185] Next, the result of Comparative Example 2 was set to 100 and indexed according to the following formula to evaluate the handling stability when running at high speeds on dry roads. A larger value indicates better handling stability when running at high speeds on dry roads. Steering stability when driving at high speeds on dry roads = [(Test tire results) / (Comparative example 2 results)] × 100

[0186] [Table 2]

[0187] [Table 3]

[0188] [Table 4]

[0189] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments. Various modifications can be made to the above-described embodiments within the scope of the same or equivalent to the present invention.

[0190] The present invention (1) is A tire having a tread portion, A cap rubber layer forming the tread portion is A styrene-butadiene rubber (SBR) having a styrene content of 25% by mass or less is contained in an amount of 80 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the rubber component, The rubber composition contains 100 parts by mass or less of silica per 100 parts by mass of the rubber component, The complex modulus of elasticity (30℃E) measured under the conditions of temperature 30℃, frequency 10Hz, initial strain 5%, dynamic strain rate 1%, deformation mode: extension * ) is formed from a rubber composition having a modulus of elasticity of more than 8.0 MPa, The tire is characterized in that the thickness of the tread portion is 8.5 mm or less.

[0191] The present invention (2) is 30°C * is more than 8.5 MPa, and is the tire according to the present invention (1).

[0192] The present invention (3) is 30°C * is more than 9.0 MPa, and is a tire according to the present invention (2).

[0193] The present invention (4) is The tire is characterized in that the thickness of the tread portion is 8.0 mm or less, and is an optional combination with any of the present inventions (1) to (3).

[0194] The present invention (5) is The cap rubber layer has a loss tangent (30°C tanδ) of 0.25 or less, measured in a tensile deformation mode under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%, and is a tire in any combination with any of present inventions (1) to (4).

[0195] The present invention (6) is The tire according to the present invention (5) is characterized in that the 30° C. tan δ is 0.20 or less.

[0196] The present invention (7) is The tread portion is multi-layered with a base rubber layer provided inside the cap rubber layer, and the thickness of the cap rubber layer accounts for 70% or more of the entire tread portion, and this tire is an optional combination with any of present inventions (1) to (6).

[0197] The present invention (8) is The tire is characterized in that the particle size (average primary particle size) of the silica is 17 nm or less, and is any combination with any of the present inventions (1) to (7).

[0198] The present invention (9) is The tire is characterized in that the acetone extractables (AE) of the cap rubber layer is 20% by mass or less, and is an optional combination with any of the present inventions (1) to (8).

[0199] The present invention (10) is The tire according to the present invention (9) is characterized in that the acetone extractables (AE) of the cap rubber layer is 18% by mass or more.

[0200] The present invention (11) is The tire is characterized in that the land ratio in the tread portion is 60% or more, and is an optional combination with any of the present inventions (1) to (10).

[0201] The present invention (12) is The land ratio R (%) in the tread portion and the 30°C E * (MPa) product is 560 or more, and is a tire in any combination with any of the present inventions (1) to (11).

[0202] The present invention (13) is When the thickness of the tread portion is G (mm), the 30°C E * The tire is characterized in that the tensile strength (MPa) and the G satisfy the following relationship, and is an arbitrary combination with any of the present inventions (1) to (12). 30°C / 104°F * / G≧1.0

[0203] The present invention (14) is The tire is characterized by having an aspect ratio of 30% or more and 60% or less, and is an optional combination with any of the present inventions (1) to (13).

Claims

1. A tire having a tread portion, A cap rubber layer forming the tread portion is A styrene-butadiene rubber (SBR) having a styrene content of 25% by mass or less is contained in an amount of 80 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the rubber component, The rubber composition contains 100 parts by mass or less of silica per 100 parts by mass of the rubber component, The complex modulus of elasticity (30°C E) measured under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%, in a deformation mode of extension. ＊ ) is formed from a rubber composition having a modulus of elasticity of more than 8.0 MPa, The tire is characterized in that the thickness of the tread portion is 8.5 mm or less.

2. The 30°C ＊ 2. The tire of claim 1, wherein the tensile strength is greater than 8.5 MPa.

3. The 30°C ＊ 3. The tire according to claim 2, wherein the tensile strength is greater than 9.0 MPa.

4. 4. The tire according to claim 1, wherein the thickness of the tread portion is 8.0 mm or less.

5. 4. The tire according to claim 1, wherein the cap rubber layer has a loss tangent (30°C tanδ) of 0.25 or less, measured in a deformation mode of tension under conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%.

6. 6. The tire according to claim 5, wherein the 30° C. tan δ is 0.20 or less.

7. 4. The tire according to claim 1, wherein the tread portion is multi-layered with a base rubber layer provided inside the cap rubber layer, and the thickness of the cap rubber layer accounts for 70% or more of the entire tread portion.

8. 4. The tire according to claim 1, wherein the particle diameter (average primary particle diameter) of the silica is 17 nm or less.

9. 4. The tire according to claim 1, wherein the cap rubber layer has an acetone extractable content (AE) of 20% by mass or less.

10. The tire according to claim 9, wherein the cap rubber layer has an acetone extractable content (AE) of 18% by mass or less.

11. 4. The tire according to claim 1, wherein a land ratio in the tread portion is 60% or more.

12. the land ratio R (%) in the tread portion and the 30°C E ＊ 4. The tire according to claim 1, wherein the product of (MPa) is 560 or more.

13. When the thickness of the tread portion is G (mm), the 30°C E ＊ The tire according to any one of claims 1 to 3, wherein the tension (MPa) and the G satisfy the following relationship: 30°E ＊ / G≧1.0

14. 4. The tire according to claim 1, wherein an aspect ratio is 30% or more and 60% or less.

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