tire

Abstract

To improve wear resistance during high-speed traveling.SOLUTION: A tire includes a tread part. A cap rubber layer forming the tread part is formed from a rubber composition which contains 60 pts.mass or more and 80 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 loss tangent (30°C tanδ) of greater than 0.25 as measured in a deformation mode of 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%. The tread part has a thickness of 6 mm or greater and 15 mm or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] Since tires are worn out by running, various techniques have been proposed for improving wear resistance (for example, Patent Documents 1 to 4).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, with the recent improvement of highways, the opportunities for moving at high speed over long distances have increased dramatically. Under such circumstances, the wear resistance of tires manufactured based on the above-mentioned conventional technologies is still not sufficient, and further improvement is strongly desired.

[0005] Therefore, an object of the present invention is to improve wear resistance during high-speed running.

Means for Solving the Problems

[0006] The present invention is a tire provided with a tread portion, wherein a cap rubber layer forming the tread portion contains 60 parts by mass or more and 80 parts by mass or less of styrene-butadiene rubber (SBR) in 100 parts by mass of the rubber component with the amount of styrene in the whole SBR being 25% by mass or less, The rubber component contains less than 100 parts by mass of silica per 100 parts by mass of the rubber component, Under conditions of temperature 30°C, frequency 10Hz, initial strain 5%, and dynamic strain 1%, the loss loss tangent (30°C tanδ) measured in the deformation mode: tensile is greater than 0.25. Furthermore, under conditions of temperature 0°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1%, the loss tangent (0°C tanδ) measured in the deformation mode: tensile is 0.60 or greater. It is formed from a rubber composition, The tire is characterized in that the thickness of the tread portion is 15 mm or less. [Effects of the Invention]

[0007] According to the present invention, wear resistance during high-speed driving can be improved. [Modes for carrying out the invention]

[0008] [1] Features of the tire according to the present invention First, the features of the tire according to the present invention will be described.

[0009] The tire according to the present invention is a tire having a tread portion, wherein the cap rubber layer forming the tread portion contains styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less in the total SBR, containing 60 parts by mass or more and 80 parts by mass or less per 100 parts by mass of rubber component, and contains less than 100 parts by mass of silica per 100 parts by mass of rubber component, and the loss loss tangent (30°C tanδ) measured in the deformation mode: tensile under conditions of temperature 30°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1%, is greater than 0.25. In both cases, the loss tangent (0°C tanδ), measured under the conditions of temperature 0°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1%, with deformation mode: tensile, is 0.60 or greater. It is formed from a rubber composition, and the tread thickness is 15 mm or less.

[0010] Furthermore, the term "cap rubber layer" as used herein is not limited to the cap rubber layer forming the outermost layer of the tread portion. If there are two or more layers within 5 mm from the tread surface inward, it is sufficient that at least one of the layers satisfies the requirements of the rubber composition.

[0011] These features, as will be described later, make it possible to improve wear resistance during high-speed driving.

[0012] 2. Mechanism of effect in the tire according to the present invention The mechanism by which the above-mentioned effects are manifested in the tire according to the present invention is thought to be as follows.

[0013] As described above, the rubber composition forming the tire cap rubber layer according to the present invention is Styrene-butadiene rubber (SBR) is prepared so that the amount of styrene in the total SBR is 25% by mass or less. The rubber component contains 60 parts by mass or more and 80 parts by mass or less per 100 parts by mass, and silica contains 100 parts by mass or less per 100 parts by mass of the rubber component.

[0014] By setting the SBR component to 60 parts by mass or more and 80 parts by mass or less per 100 parts by mass of rubber component, a phase-separated structure in which the SBR phase is a continuous phase can be formed in the rubber matrix. Furthermore, by setting the styrene content in the SBR to 25% by mass or less, the silica contained in the rubber composition as a reinforcing agent can more easily interact within the SBR phase in the rubber matrix, making it easier to obtain a reinforcing effect from silica.

[0015] Furthermore, by incorporating an appropriate amount of SBR with a low styrene content (styrene content of 25% by mass or less), minute styrene domains derived from the styrene portion can be appropriately formed within the rubber matrix system. Since these formed minute styrene domains readily relieve force at the interface with other polymer molecular chains, it is thought that this can help mitigate deformation caused by friction with the road surface during high-speed tire operation.

[0016] Furthermore, the amount of styrene is more preferably 20% by mass or less, and even more preferably 15% by mass or less. On the other hand, the lower limit is preferably 4% by mass or more, more preferably 5% by mass or more, and even more preferably 6% by mass or more.

[0017] Furthermore, in the present invention, Styrene-butadiene rubber (SBR) is defined as having a styrene content of 25% by mass or less in the total SBR."Containing 60 parts by mass or more and 80 parts by mass or less per 100 parts by mass of rubber component" means that the amount of SBR in 100 parts by mass is 60 parts by mass or more and 80 parts by mass or less, and the amount of styrene in the total SBR is 25% by mass or less.

[0018] In other words, when styrene-containing polymer (SBR) is contained alone in the rubber component, it indicates that the amount of styrene is 25% by mass or less. When multiple styrene-containing polymers (SBR) are contained in the rubber component, it indicates that the amount of styrene, calculated by the sum of the products of the amount of styrene (by mass) in each polymer and the amount of that polymer blended per 100 parts by mass of the rubber component (parts by mass), is 25% by mass or less.

[0019] More specifically, if 100 parts by mass of rubber component contain 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, then the amount of styrene calculated from the formula {(S1 × X1) + (S2 × X2)} / (X1 + X2) is 25% by mass or less.

[0020] Furthermore, in the rubber composition after vulcanization, the amount of styrene contained in the rubber component after acetone extraction can also be calculated by determining it using solid-state nuclear magnetic resonance (solid-state NMR) or Fourier transform infrared spectrophotometer (FTIR).

[0021] In the present invention, the rubber composition forming the cap rubber layer contains silica in an amount less than 100 parts by mass per 100 parts by mass of rubber component, and not exceeding the amount of silica in the rubber component. As a result, in addition to the reinforcing effect due to the interaction of silica as described above, friction between minute styrene domains and silica generates heat, which allows deformation energy to be dissipated, and thus it is believed that wear resistance during high-speed driving can be sufficiently improved.

[0022] Furthermore, in this invention, the loss tangent (30°C tanδ) of the rubber composition forming the cap rubber layer, measured under the conditions of a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain of 1%, with the deformation mode being tensile, is set to be greater than 0.25.

[0023] The loss tangent tanδ is a viscoelastic parameter that indicates energy absorption performance; the larger the value, the more energy can be absorbed and converted into heat. In this invention, the tanδ at 30°C, which is close to the running temperature, is set to over 0.25. Therefore, even during high-speed driving where high-frequency vibrations occur, the vibration energy is sufficiently absorbed, converted into heat, and released, resulting in sufficient energy loss within the rubber composition and improving grip performance. Furthermore, as grip performance improves, the occurrence of slippage on the tread surface can be suppressed, which is thought to significantly improve wear resistance during high-speed driving.

[0024] Furthermore, the tanδ at 30°C is more preferably 0.30 or higher, and even more preferably 0.35 or higher. There is no particular upper limit, but it is preferably 0.50 or lower, more preferably 0.45 or lower, and even more preferably 0.40 or lower.

[0025] In the above, the loss tangent (tanδ) can be measured using a viscoelasticity measuring device such as the "Iplexer®" manufactured by GABO.

[0026] The method for adjusting tanδ is not particularly limited, but it can be increased by methods such as increasing the amount of styrene in the polymer, increasing the resin component content, or increasing the carbon black content, and decreased by decreasing the amount of styrene in the polymer, decreasing the resin component content, or decreasing the carbon black content.

[0027] Furthermore, in the tire according to the present invention, as described above, the thickness of the tread portion is set to 15 mm or less. By controlling the thickness to such an appropriate level, it is possible to suppress the accumulation of heat in the tread portion due to friction with the road surface, and to suppress the decrease in wear resistance due to the temperature rise of the tread portion caused by heat accumulation. The thickness of the tread portion is more preferably 13 mm or less, and even more preferably 9 mm or less. There is no particular lower limit, but it is preferably 4 mm or more, more preferably 5 mm or more, and even more preferably 6 mm or more.

[0028] In this invention, the tread thickness refers to the thickness of the tread on the tire's equatorial plane in the tire's radial cross-section. When the tread is formed from a single rubber composition, it refers to the thickness of that rubber composition. When it is formed from a laminated structure of multiple rubber compositions, as described later, it refers to the total thickness of these layers.

[0029] In the case of a tire with grooves on its equatorial plane, this refers to the thickness from the intersection of the straight line connecting the outermost endpoints of the grooves in the tire's radial direction with the tire's equatorial plane, to the innermost interface of the tread portion in the tire's radial direction.

[0030] The tread portion refers to the area that forms the contact surface of the tire, specifically the part radially outside the carcass, belt layer, belt reinforcement layer, and other components containing fibrous materials. The thickness of the tread portion can be measured by cutting a section of the tire radially and aligning the bead portion with the standard rim width.

[0031] In the above, "standard rim" refers to the rim specified for each tire in the standards system that includes the standards on which the tire is based. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." Refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. In the case of tires not specified in the standards, it refers to the rim with the smallest diameter and the narrowest rim width among rims that can be mounted on and can maintain internal pressure, i.e., rims that do not cause air leakage from between the rim and tire.

[0032] As described above, the tire according to the present invention is considered to have significantly improved wear resistance during high-speed driving due to the reinforcing effect of silica in the rubber composition, the deformation mitigation effect due to an appropriate amount of styrene, the slip suppression effect on the tread surface due to an appropriate 30°C tanδ, and the heat accumulation suppression effect due to appropriate thickness control.

[0033] [2] More preferred embodiment of the tire according to the present invention The tire according to the present invention can achieve even greater effects by adopting the following embodiments.

[0034] 1. Relationship between the tanδ of the cap rubber layer at 30°C and the thickness of the tread. The inventors of this invention hypothesized that there is a favorable relationship between 30°C tanδ and the tread thickness G (mm) for improving wear resistance during high-speed driving, and conducted experiments and studies. As a result, it was found that if 30°C tanδ / G > 0.03, the cooperation between the effect of suppressing slippage on the tread surface due to appropriate 30°C tanδ and the effect of suppressing heat accumulation due to appropriate thickness control is further fully realized, resulting in further improvement of wear resistance during high-speed driving. It is preferable that the upper limit of α is 0.045 or less.

[0035] 2. Glass transition temperature (Tg) of the cap rubber layer In the present invention, the glass transition temperature (Tg) of the cap rubber layer is preferably -15°C or lower, and more preferably -40°C or lower. When a rubber composition with a high glass transition temperature (Tg) is used to form the cap rubber layer, the tread portion hardens near the running temperature, which may lead to a decrease in wear resistance due to friction with the road surface. By setting the Tg to -15°C or lower, it is possible to suppress the hardening of the tread portion and further improve wear resistance during high-speed driving. The lower limit of Tg is not particularly limited, but it is preferably -60°C or higher, and more preferably -50°C or higher.

[0036] The glass transition temperature (Tg) of the rubber composition described above can be determined based on the temperature distribution curve of tanδ measured using a viscoelasticity measuring device such as the Iplexer series manufactured by GABO, under conditions of frequency 10 Hz, initial strain 10%, amplitude ±0.5%, and heating rate 2°C / min. In the case of the present invention, the temperature corresponding to the largest tanδ value in the range of -60°C to 40°C of the measured temperature distribution curve is defined as the glass transition temperature (Tg). If there are two or more points with the largest tanδ value within the range of -60°C to 40°C, the point with the lowest temperature is defined as Tg. For example, in the present invention, if the maximum value of tanδ is within the range of -60°C to 40°C, then according to the above definition, the temperature showing that maximum value is Tg. Furthermore, for example, if a temperature distribution curve is obtained in which tanδ gradually decreases with increasing temperature within the range of -60°C to 40°C, and the temperature at which tanδ is maximum is -60°C, then according to the above definition, the glass transition temperature (Tg) is -60°C.

[0037] Furthermore, the method for adjusting the glass transition temperature (Tg) is not particularly limited, but it can be increased by methods such as increasing the proportion of polymer components with a high Tg in the rubber component, increasing the amount of styrene in the rubber component, or increasing the content of resin components. Conversely, it can be lowered by methods such as decreasing the proportion of polymer components with a high Tg in the rubber component, decreasing the amount of styrene in the rubber component, or decreasing the content of resin components.

[0038] 3. Complex modulus of elasticity of the cap rubber layer (E * ) In this invention, the complex modulus of elasticity of the cap rubber layer (30°CE) was measured at a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, a dynamic strain rate of 1%, and the deformation mode was elongation. * The pressure is preferably 6.0 MPa or less, and more preferably 5.5 MPa or less. Complex modulus of elasticity E * This parameter indicates the rigidity of the rubber layer, and is 30℃E *When it is 6.0 MPa or less, it is considered that it is possible to suppress the excessive increase in rigidity, suppress slipping with the road surface during high-speed driving, and further improve the abrasion resistance. The lower limit is not particularly limited, but it is preferably 4.00 MPa or more, more preferably 5.00 MPa or more, and even more preferably 5.30 MPa or more.

[0039] And the above-mentioned 30°C E * (MPa) preferably satisfies (30°C E * / G)≧0.50 with the thickness G (mm) of the tread part described above, and more preferably 0.55 or more. On the other hand, as the upper limit, it is preferably 1.00 or less, and more preferably 0.65 or less. It is considered that the thicker the tread part, the easier it is for the heat during rolling to accumulate heat, the strength of the rubber decreases, the deformation amount during rolling increases, and it becomes easier to wear. Therefore, by appropriately controlling the relationship between 30°C E * and the thickness of the tread part, it is considered that the deformation of the tread part can be optimized during high-speed driving, and the abrasion resistance can be further improved.

[0040] The above-mentioned complex elastic modulus can be measured using a viscoelasticity measuring device such as "E-Plexor (registered trademark)" manufactured by GABO.

[0041] Also, the adjustment method of the above-mentioned 30°C E * is not particularly limited. For example, it can be increased by methods such as increasing the styrene amount of the polymer, increasing the amount of fillers such as silica and carbon black, reducing the content of the plasticizer component, and increasing the content of the resin component, and can be decreased by methods such as reducing the styrene amount of the polymer, reducing the amount of fillers such as silica and carbon black, increasing the content of the plasticizer component, and reducing the content of the resin component.

[0042] The loss tangent (0°C tanδ) and complex elastic modulus (0°C E * ) The above assumes driving conditions and uses 30°C tanδ and 30°C E * Although the specifications state that the tires are cold at the start of driving, considering driving at low temperatures, the loss tangent (0°C tanδ) of the rubber composition forming the cap rubber layer, measured in deformation mode: tensile under the conditions of temperature 0°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1%, is preferably 0.60 or higher, more preferably 0.70 or higher, and even more preferably 0.80 or higher. The upper limit is not particularly limited, but is preferably 1.00 or lower, more preferably 0.95 or lower, and even more preferably 0.90 or lower.

[0043] Similarly, the complex modulus of elasticity of the cap rubber layer was measured at a temperature of 0°C, a frequency of 10Hz, an initial strain of 5%, a dynamic strain of 1%, and the deformation mode was elongation (0°C E). * The pressure is preferably 25.0 MPa or less, and more preferably 23.5 MPa or less. The lower limit is not particularly limited, but is preferably 20.0 MPa or more, and more preferably 23.0 MPa or more.

[0044] Note that the above-mentioned 0°C tanδ and 0°C E * The method of adjustment is not particularly limited, but for example, if tanδ is 0℃, it can be increased by increasing the amount of styrene in the rubber component or increasing the content of the resin component, and decreased by decreasing the amount of styrene in the rubber component or decreasing the content of the resin component. * Therefore, the rubber content can be increased by methods such as increasing the amount of styrene in the rubber component, increasing the amount of fillers such as silica and carbon black, decreasing the amount of plasticizer components, or increasing the amount of resin components. Conversely, the rubber content can be decreased by methods such as decreasing the amount of styrene in the rubber component, decreasing the amount of fillers such as silica and carbon black, increasing the amount of plasticizer components, or decreasing the amount of resin components.

[0045] 5. Multi-layered tread In the present invention, the tread portion is preferably formed by only one cap rubber layer, but a multi-layered tread portion may be formed by providing a base rubber layer inside the cap rubber layer. In this case, the thickness of the cap rubber layer in the entire tread portion is preferably 10% or more. This makes it easier to absorb the energy generated between the tread surface and the road surface at the interface between the cap rubber layer and the base rubber layer, and is thought to further improve wear resistance during high-speed driving. It is even more preferable that the thickness of the cap rubber layer in the entire tread portion is 70% or more.

[0046] As described above, the thickness of the cap rubber layer and the base rubber layer can be calculated by adding the thickness of the cap rubber layer and the base rubber layer in the tread area.

[0047] In this case, it is preferable to make the 30°C tanδ of the base rubber layer smaller than that of the cap rubber layer. This is thought to suppress heat generation on the inside of the tread, making it easier to prevent the tread from softening due to heat accumulation, and further improving wear resistance during high-speed driving.

[0048] Furthermore, in the case of the multi-layered tread section, the complex modulus of elasticity (30℃E) was measured at a base rubber layer temperature of 30℃, frequency of 10Hz, initial strain of 5%, dynamic strain rate of 1%, and deformation mode: extension. * ) However, the same measurement was taken for the cap rubber layer at 30°C E * It is preferable that it be smaller than this.

[0049] 6. Silica particle size

[0050] In the present invention, the particle size (average primary particle size) of silica is preferably 17 nm or less, taking into consideration factors such as ease of friction with the polymer.

[0051] The average primary particle diameter can be calculated by directly observing silica extracted from the rubber composition cut from the tire using an electron microscope (TEM), calculating the equicross-sectional area diameter from the area of ​​each silica particle obtained, and then determining the average value.

[0052] 7. Content of resin components in the cap rubber layer In the present invention, it is preferable that the rubber composition forming the cap rubber layer contains a resin component.

[0053] It is believed that by including a resin component in the rubber composition, the adhesive properties of the resin component improve contact with the road surface, thereby significantly improving wear resistance during high-speed driving.

[0054] 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 of the resin component per 100 parts by mass of the rubber component is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 65 parts by mass or more.

[0055] 8. Acetone extract (AE) from the cap rubber layer In the present invention, the acetone extract (AE) in the cap rubber layer is preferably 28% by mass or more, and more preferably 30% by mass or more. On the other hand, there is no particular upper limit, but it is preferably 35% by mass or less, and more preferably 34% by mass or less.

[0056] Acetone extract (AE) can be considered an indicator of the amount of softeners and other substances in a rubber composition, and can also be considered an indicator of the ease of movement of the molecular chains of the rubber components. Therefore, as described above, if the amount of AE is increased to a certain extent in the cap rubber layer, a sufficient contact area between the tire and the road surface can be secured, improving contact performance and significantly improving wear resistance at high speeds.

[0057] Furthermore, the acetone extract (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 from the measurement site in acetone for a predetermined time and determining the mass loss rate (%) of the test piece.

[0058] More specifically, the soluble components can be extracted by immersing each vulcanized rubber test piece in acetone for 72 hours at room temperature and atmospheric pressure, measuring the mass of each test piece before and after extraction, and then determining the result using the following formula. Acetone extraction amount (%) = {(Mass of rubber test piece before extraction - Mass of rubber test piece after extraction)} / (mass of rubber test piece before extraction)} × 100

[0059] Furthermore, the aforementioned acetone extract can be appropriately modified by changing the blending ratio of plasticizers in the rubber composition.

[0060] 9. Rand ratio In the tire according to the present invention, the land ratio in the tread portion of the tire, when assembled on a regular rim and subjected to regular internal pressure, is 40% or more, and the ratio of the content (parts by mass) of styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less per 100 parts by mass of rubber component to the land ratio (%) in the tread portion (SBR content (parts by mass) with a styrene content of 25% by mass or less / land ratio (%)) is preferably 1.2 or less, and more preferably 1.0 or less.

[0061] The "land ratio" is the ratio of the actual contact area to a hypothetical contact area where all the grooves on the surface of the tread are filled. A larger land ratio means a larger contact area with the road surface, making it easier to reduce the force generated per unit area when contacting the road. Furthermore, by keeping the ratio of the amount of SBR (styrene) at 25% by mass or less to the land ratio below a certain level, it becomes easier to suppress excessive force concentration in the styrene domains formed in the rubber composition, which can become the starting point of wear, thus improving wear resistance at high speeds.

[0062] The lower limit of the ratio between the styrene content of SBR (25% by mass or less) and the land ratio is not particularly limited, but it is preferably 0.2 or higher, and more preferably 0.5 or higher.

[0063] The aforementioned land ratio can be determined from the contact shape under normal rim, normal internal pressure, and normal load conditions.

[0064] Specifically, the tire is mounted on a standard rim, the standard internal pressure is applied, and it is left to stand at 25°C for 24 hours. Then, ink is applied to the surface of the tire tread, and the standard load is applied and it is pressed onto cardboard (camber angle is 0°). By transferring the image to the paper, the contact shape can be obtained. The tire is rotated 72° in the circumferential direction, and the image is transferred at 5 locations. In other words, the contact shape is obtained 5 times. At this time, for the 5 contact shapes, the parts that are interrupted by grooves in the contour of the contact shape are smoothly connected, and the resulting shape is considered the virtual contact surface.

[0065] The land ratio can then be calculated using the formula: (average area of ​​the five contact shapes (inked areas) transferred to the cardboard / average area of ​​the virtual contact surface obtained from the five contact shapes) × 100 (%).

[0066] "Regular internal pressure" refers to the air pressure specified for each tire by the aforementioned standards. 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." Similar to "regular rim," refer to JATMA, ETRTO, and TRA in that order and follow the respective standards. For tires not specified in the standards, it refers to the regular internal pressure (but 250 kPa or higher) of another tire size (specified in the standards) that uses the aforementioned regular rim as the standard rim. If multiple regular internal pressures of 250 kPa or higher are listed, refer to the lowest value among them.

[0067] Here, "normal load" refers to the load specified for each tire in the standards system, including the standard on which the tire is based, and represents the maximum mass that the tire is allowed to be loaded with. For JATMA, it refers to the maximum load capacity; for ETRTO, it refers to "LOAD CAPACITY"; and for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". As with the "normal rim" and "normal internal pressure" mentioned above, refer to JATMA, ETRTO, and TRA in that order and follow their respective standards. For tires not specified in the standards, the normal load W is calculated as follows: L We seek. 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 section width (mm)

[0068] Furthermore, the amount of styrene in 100 parts by mass of rubber component can be calculated, for example, if 100 parts by mass of 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, using the formula {(S1 × X1) + (S2 × X2)} / 100.

[0069] 10. Flatness In the tire according to the present invention, it is preferable that the aspect ratio is 80% or less, and the ratio of silica content (parts by mass) to aspect ratio (%) per 100 parts by mass of rubber component (silica content (parts by mass) / aspect ratio (%)) is 1.7 or more.

[0070] The aspect ratio is the ratio of the tire's cross-sectional height to its cross-sectional width. A smaller aspect ratio allows the force from the rim during rolling to be more easily transmitted to the tread, thus accelerating tread wear. Therefore, by incorporating a sufficient amount of silica relative to the aspect ratio, it is possible to ensure reinforcement through a silica network, thereby improving wear resistance at high speeds.

[0071] The aspect ratio (%) mentioned above can be calculated using the following formula, with the tire's cross-sectional height Ht (mm), cross-sectional width Wt (mm), tire outer diameter Dt (mm), and rim diameter R (mm) assuming an internal pressure of 250 kPa. Oblateness (%)=(Ht / Wt)×100(%) Ht = (Dt - R) / 2

[0072] Furthermore, the upper limit of the silica content ratio to the flatness ratio, as described above, is not particularly limited, but is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less.

[0073] [3] Embodiment The present invention will be specifically described below based on embodiments.

[0074] 1. Rubber composition 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 rubber components, fillers, softeners, vulcanizing agents, and vulcanization accelerators described below.

[0075] (1) Compounding materials (a) Rubber component The rubber component is not particularly limited, and any rubber (polymer) commonly used in tire manufacturing can be used, such as isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), butyl rubber, and thermoplastic elastomers such as styrene-butadiene-styrene block copolymer (SBS) and styrene-butadiene block copolymer (SB). These rubber components may also be pre-stretched rubber using oils, resins, or liquid rubber components as described later.

[0076] In this invention, among these, the rubber component includes SBR and other rubber components. The other rubber components are not particularly limited, but combination with BR, or combination with BR and isoprene-based rubber is preferred.

[0077] (i) SBR The weight-average molecular weight of SBR is, for example, more than 100,000 and less than 2,000,000. In this invention, as described above, the amount of styrene in the SBR component is 25% by mass or less. The vinyl content (1,2-bonded butadiene content) of SBR is, for example, more than 5% by mass and less than 70% by mass. Note that the vinyl content of SBR refers to the amount of 1,2-bonded butadiene relative to the total butadiene portion in the SBR component. Furthermore, structural identification of SBR (measurement of styrene content and vinyl content) can be performed, for example, using an instrument from JEOL Ltd.'s JNM-ECA series.

[0078] In the present invention, the SBR content in 100 parts by mass of rubber component is, as described above, 60 parts by mass or more and 80 parts by mass or less, but more preferably 65 parts by mass or more and 75 parts by mass or less. In the case of stretchable SBR, the amount of pure rubber excluding the amount of stretchable component is the SBR content.

[0079] The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc., can be used. The SBR may be either unmodified SBR or modified SBR. Furthermore, hydrogenated SBR, in which the butadiene portion of the SBR is hydrogenated, may be used. Hydrogenated SBR may be obtained by subsequently hydrogenating the BR portion of the SBR, or a similar structure may be obtained by copolymerizing styrene, ethylene, and butadiene.

[0080] Modified SBRs can be any SBR having a functional group that interacts with a packing material such as silica. Examples include terminally modified SBRs (terminally modified SBRs having the functional group at the terminal) in which at least one end of the SBR is modified with a compound having the functional group (modifying agent), main-chain modified SBRs having the functional group in the main chain, main-chain terminally modified SBRs having the functional group in both the main chain and the terminal (for example, main-chain terminally modified SBRs having the functional group in the main chain and at least one end modified with the modifying agent), and terminally modified SBRs that are modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule, and in which hydroxyl groups or epoxy groups are introduced.

[0081] Examples of the above-mentioned functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, and the like. These functional groups may also have substituents.

[0082] Furthermore, as modified SBR, for example, SBR modified with a compound (modifying agent) represented by the following formula can be used.

[0083] [ka]

[0084] Note that in the formula, R 1 , R 2 and R 3 R represents, either identical or distinct, 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 R represents a hydrogen atom or an alkyl group, either identical or different. 4 and R 5 These atoms may bond to form a ring structure with the nitrogen atom. n represents an integer.

[0085] As a modified SBR modified with the compound (modifying agent) represented by the above formula, SBR obtained by modifying the polymerization ends (active ends) of solution-polymerized styrene-butadiene rubber (S-SBR) with the compound represented by the above formula (such as the modified SBR described in Japanese Patent Publication No. 2010-111753) can be used.

[0086] R 1 , R 2 and R 3 A suitable alkoxy group is used (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 A suitable alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is used. n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. Also, R 4 and R 5 When the alkoxy group is bonded to form a ring structure with the nitrogen atom, it is preferably a 4- to 8-membered ring. Note that the alkoxy group also includes cycloalkoxy groups (such as cyclohexyloxy group) and aryloxy groups (such as phenoxy group and benzyloxy group).

[0087] Specific examples of the above-mentioned denaturing agents include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. These may be used individually or in combination of two or more.

[0088] Furthermore, modified SBR can also be modified using the following compounds (modifying agents): For example, 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 diglycidyl bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxylated liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, Diglycidylamino compounds such as diglycidyl orthotoluidine, tetraglycidylmetoxylendiamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamate chloride, 4-morpholine carbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamate chloride, and N,N-diethylcarbamate 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-(tributoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldipropoxysilyl)propyl]sulfide Sulfide group-containing silane compounds such as [sisilyl)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)aminoethyl Alkoxysilanes such as tiltriethoxysilane; (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-triones. Examples include 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-dimethylaminoacetophene, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, and 1,7-bis(methylethylamino)-4-heptanone. Modification using the above compounds (modifiers) can be carried out by known methods.

[0089] For example, SBR manufactured and sold by companies such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Co., Ltd. can be used. SBR may be used alone or in combination of two or more types.

[0090] (b)BR In the present invention, the rubber composition may contain BR. In this case, the BR content in 100 parts by mass of the rubber component is preferably 20 parts by mass or more and 40 parts by mass or less, and more preferably 25 parts by mass or more and 35 parts by mass or less.

[0091] The weight-average molecular weight of BR is, for example, greater than 100,000 and less than 2,000,000. The vinyl content of BR is, for example, greater than 1% by mass and less than 30% by mass. The cis content of BR is, for example, greater than 1% by mass and less than 98% by mass. The trans content of BR is, for example, greater than 1% by mass and less than 60% by mass.

[0092] The BR is not particularly limited, and can be high-cis content BR (cis content of 90% or more), low-cis content BR, or BR containing syndiotactic polybutadiene crystals. The BR can be either unmodified or modified, and modified BR can be modified BR into which the aforementioned functional groups have been introduced. These can be used individually or in combination of two or more. The cis content can be measured by infrared absorption spectroscopy.

[0093] For example, products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used as BRs.

[0094] (h) Isoprene rubber In the present invention, the rubber composition may optionally contain isoprene-based rubber. In this case, the content of isoprene-based rubber in 100 parts by mass of the rubber component is preferably 20 parts by mass or more and 40 parts by mass or less, and more preferably 25 parts by mass or more and 35 parts by mass or less.

[0095] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR.

[0096] For NR, common types used in the tire industry can be used, such as SIR20, RSS#3, TSR20, and SVR-L. For IR, there are no particular limitations, and common types used in the tire industry can be used, such as IR2200. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used individually or in combination of two or more types.

[0097] (ii) Other rubber components Furthermore, other rubber components may include rubbers (polymers) commonly used in tire manufacturing, such as nitrile rubber (NBR).

[0098] (b) Compounding materials other than rubber components (i) Filling agent In the present invention, the rubber composition contains silica as a filler, as described above, but it may also contain other fillers. Specific fillers other than silica include, for example, carbon black, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica.

[0099] (i-1) Silica In the present invention, the BET specific surface area of ​​silica contained in the rubber composition is 140 m² from the viewpoint of obtaining good durability performance. 2 Preferably more than / g, 160m 2 A value greater than / g is preferable. On the other hand, from the viewpoint of obtaining good rolling resistance at high speeds, 250m 2 Preferably less than / g, 220m 2 It is more preferable that the value be less than / g. The BET specific surface area mentioned above is the N2SA value measured by the BET method in accordance with ASTM D3037-93.

[0100] In the present invention, as described above, silica with a particle size of 17 nm or less is preferably used. By using silica with a small particle size, the frequency of contact with the polymer (styrene domain) is increased, thereby enhancing the mobility of the polymer and causing energy loss, which can improve wear resistance during high-speed driving. The lower limit is not particularly limited, but from the viewpoint of dispersibility during mixing, it is preferably 10 nm or more.

[0101] As mentioned above, the silica content should be 100 parts by mass or less per 100 parts by mass of rubber component, and should not exceed the amount of rubber component, but preferably 95 parts by mass or less, and more preferably 90 parts by mass or less. The lower limit is not particularly limited, but considering the reinforcing properties of silica, it is preferably 70 parts by mass or more, and more preferably 80 parts by mass or more.

[0102] Examples of silica include dry-process silica (anhydrous silica) and wet-process silica (hydrated silica). Among these, wet-process silica is preferred because it contains a large number of silanol groups. Silica made from hydrated glass or silica made from biomass materials such as rice husks may also be used.

[0103] For example, silica products from companies such as Evonik Industries, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Ltd., and Tokuyama Corporation can be used.

[0104] (i-2) Silane coupling agent The rubber composition forming the cap rubber layer of the present invention preferably contains a silane coupling agent together with silica. The silane coupling agent is not particularly limited and includes, for example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl) trisulfide, bis(4-trimethoxysilylbutyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthioca Examples include sulfide compounds such as rubamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z from Momentive; vinyl compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These may be used individually or in combination of two or more.

[0105] Examples of silane coupling agents that can be used include products from Evonik Industries, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Toray Dow Corning Co., Ltd.

[0106] The silane coupling agent content is, for example, more than 3 parts by mass and less than 25 parts by mass per 100 parts by mass of silica.

[0107] (ii) Carbon Black In the present invention, the rubber composition preferably contains carbon black from the viewpoint of reinforcing properties.

[0108] The carbon black content per 100 parts by mass of rubber component is preferably 10 parts by mass or more, and more preferably 20 parts by mass or more. On the other hand, it is preferably 60 parts by mass or less, and more preferably 50 parts by mass or less.

[0109] Carbon black is not particularly limited and can 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 individually or in combination of two or more types.

[0110] The specific surface area (CTAB) of carbon black (Cetyl Tri-methyl Ammonium Bromide) is 130 m². 2 Preferably 160m / g or more. 2 It is more preferably 170m / g or more. 2 It is even more preferable if it is 1 / g or more. On the other hand, 250m 2 Preferably less than / g, 200m 2It is more preferable that the value is less than or equal to / g. Note that the CTAB specific surface area is a value measured in accordance with ASTM D3765-92.

[0111] There are no specific limitations on the carbon black used, but examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nippon Chemical Carbon Co., Ltd., and Columbia Carbon Corporation. These can be used individually or in combination of two or more types.

[0112] (iii) Other fillers The rubber composition may, if necessary, further contain fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica, in addition to the silica and carbon black mentioned above. The amount of these fillers 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.

[0113] (b) Plasticizer components The rubber composition may contain oil (including stretching oil), liquid rubber, and resin as plasticizer components to soften the rubber. The plasticizer components are those that can be extracted from vulcanized rubber using acetone. The total content of the plasticizer components is preferably 85 parts by mass or more, and more preferably 100 parts by mass or more, per 100 parts by mass of the rubber component. On the other hand, it is preferably 120 parts by mass or less, and more preferably 110 parts by mass or less. If stretchable rubber is used as the rubber component, the amount of stretchable component is included in the amount of these plasticizer components.

[0114] (i) oil Examples of oils include mineral oil (generally called process oil), vegetable oils, or mixtures thereof. Examples of mineral oils (process oils) include paraffinic process oil, aromatic process oil, and naphthenic process oil. 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 oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These may be used individually or in combination of two or more. Furthermore, from a life cycle assessment perspective, waste oil used as lubricant in rubber mixers or automobile engines, or waste cooking oil may be used as appropriate.

[0115] Furthermore, process oils with a low content of polycyclic aromatic compounds (PCA) can be used as an environmental measure. Examples of such low-PCA process oils include light extract solvates (MES), processed distillate aromatic extracts (TDAEs), and heavy naphthenic oils.

[0116] Specific process oils (mineral oils) that can be used include products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., and Fuji Kosan Co., Ltd.

[0117] (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 from vulcanized tires by acetone extraction. Examples of liquid rubber include farnesene polymers, liquid diene polymers, and their hydrogenated derivatives.

[0118] Farnesene polymers are polymers obtained by polymerizing farnesene and have constituent 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).

[0119] The farnesene polymer may be a farnesene homopolymer (farnesene homopolymer) or a farnesene-vinyl monomer copolymer (farnesene-vinyl monomer copolymer).

[0120] 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).

[0121] The liquid diene polymer has a weight-average molecular weight (Mw) on a polystyrene basis, measured by gel permeation chromatography (GPC), for example, 1.0 × 10⁻⁶. 3 Super, 2.0×10 5 It is less than. In this specification, the Mw of the liquid diene polymer is the polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0122] The liquid rubber content (total content of liquid farnesene polymers, liquid diene polymers, etc.) is, for example, more than 1 part by mass and less than 100 parts by mass per 100 parts by mass of rubber components.

[0123] As for liquid rubber, products from companies such as Kuraray Co., Ltd. and Clay Valley Corporation can be used.

[0124] (iii) Resin components The resin component also functions as a tackifying agent and may be solid or liquid at room temperature. Specific resin components include, for example, rosin resins, styrene resins, coumarone resins, terpene resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, and two or more may be used in combination. The resin component content is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 65 parts by mass or more, per 100 parts by mass of the rubber component. These resin components may be given modified groups that can react with silica or the like, as needed.

[0125] Rosin resins are resins whose main component is rosin acid, obtained by processing pine resin. These rosin resins (rosins) can be classified according to whether or not they are modified, and can be classified into unmodified rosin and rosin derivatives. Examples of unmodified rosin include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionate rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. Rosin derivatives are modified forms of unmodified rosin and include rosin esters, unsaturated carboxylic acid-modified rosins, unsaturated carboxylic acid-modified rosin esters, rosin amide compounds, and rosin amine salts.

[0126] Styrene resins are polymers that use styrene monomers as constituent monomers, and include polymers polymerized with styrene monomers as the main component (50% by mass or more). Specifically, 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 copolymerize with them.

[0127] Examples of the aforementioned 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; and α,β-unsaturated carboxylic acids such as maleic anhydride or their acid anhydrides.

[0128] Among coumarone-based resins, coumarone-indene resin is preferred. Coumarone-indene resin is a resin that contains coumarone and indene as monomer components that constitute the resin's backbone (main chain). Other monomer components that can be included in the backbone besides coumarone and indene include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0129] The coumaron indene resin content is, for example, more than 1.0 part by mass and less than 50.0 parts by mass per 100 parts by mass of rubber component.

[0130] The hydroxyl value (OH value) of coumarone indene resin is, for example, greater than 15 mg KOH / g and less than 150 mg KOH / g. The OH value is expressed in milligrams as the amount of potassium hydroxide required to neutralize the acetic acid bonded to the hydroxyl groups when acetylating 1 g of resin, and is measured by potentiometric titration (JIS K 0070:1992).

[0131] The softening point of coumaron indene resin is, for example, above 30°C and below 160°C. The softening point is determined by measuring the softening point as specified in JIS K 6220-1:2001 using a ring-type softening point measuring device, and it is the temperature at which the sphere descends.

[0132] Examples of terpene resins include polyterpenes, terpene phenols, and aromatically modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenated products. Terpene compounds are (C5H8) n A hydrocarbon represented by the following composition and its oxygen-containing derivative, a monoterpene (C10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpene (C 20 H 32 These are compounds with a terpene as their basic skeleton, classified as such, and examples include α-pinene, β-pinene, dipentene, limonene, myrcene, allocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0133] 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 terpene compounds mentioned above, as well as hydrogenated terpene resins obtained by hydrogenating these terpene resins. Terpene phenols include resins obtained by copolymerizing the above terpene compounds with phenolic compounds, and resins obtained by hydrogenating these resins. Specifically, resins obtained by condensing the above terpene compounds, phenolic compounds, and formalin are included. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Aromatically modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating these resins. The aromatic compounds are not particularly limited as long as they are compounds having an aromatic ring, but examples include phenol compounds such as phenol, alkylphenol, alkoxyphenol, and phenol containing an unsaturated hydrocarbon group; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and naphthol containing an unsaturated hydrocarbon group; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and styrene containing an unsaturated hydrocarbon group; coumarone, indene, and others.

[0134] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferably used as a C5-based petroleum resin.

[0135] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be hydrogenated or modified. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples include coumarone indene resin, coumarone resin, indene resin, and aromatic vinyl resins, which are suitably used. As aromatic vinyl resins, homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene are preferred, and copolymers of α-methylstyrene and styrene are more preferred, due to their economical nature, ease of processing, and excellent heat generation properties. Aromatic vinyl resins that are commercially available from companies such as Kraton and Eastman Chemical can be used.

[0136] "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified. Examples of the C5 and C9 fractions include the petroleum fractions mentioned above. As for the C5C9 resin, commercially available products from companies such as Tosoh Corporation and LUHUA can be used.

[0137] While there are no particular limitations on the acrylic resin used, for example, a solvent-free acrylic resin can be used.

[0138] Solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized by high-temperature continuous polymerization (high-temperature continuous mass polymerization) (methods described in U.S. Patent No. 4,414,370, Japanese Patent Publication No. 59-6207, Japanese Patent Publication No. 5-58005, Japanese Patent Publication No. 1-313522, U.S. Patent No. 5,010,166, Toa Gosei Research Annual Report TREND2000 No. 3 pp. 42-45, etc.) with minimal use of polymerization initiators, chain transfer agents, organic solvents, etc. as auxiliary raw materials. In this invention, (meth)acrylic means methacrylic and acrylic.

[0139] Examples of monomer components constituting the above-mentioned 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.

[0140] Furthermore, as monomer components constituting the above-mentioned acrylic resin, aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene may be used along with (meth)acrylic acid and (meth)acrylic acid derivatives.

[0141] The above-mentioned acrylic resin may be a resin composed solely of (meth)acrylic components, or a resin that also contains components other than (meth)acrylic components. Furthermore, the above-mentioned acrylic resin may have hydroxyl groups, carboxyl groups, silanol groups, etc.

[0142] As resin components, products from companies such as Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Industries, Ltd. can be used.

[0143] (H) Stearic acid In the present invention, the rubber composition preferably contains stearic acid. The stearic acid content 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. Conventional known stearic acid can be used, for example, products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acid Co., Ltd., etc.

[0144] (ii) Anti-aging agents In the present invention, it is preferable that the rubber composition contains an anti-aging agent. The amount of the anti-aging agent 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.

[0145] Examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4′-bis(α,α′-dimethylbenzyl)diphenylamine; N-isopropyl-N′-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, and N,N′-di-2-naphthyl-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers and other quinoline-based antioxidants; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane. These may be used individually or in combination of two or more types.

[0146] Furthermore, as an anti-aging agent, products from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis Co., Ltd. can be used.

[0147] (Ho) Wax In the present invention, the rubber composition preferably contains wax. The wax content 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, per 100 parts by mass of the rubber component.

[0148] The waxes are not particularly limited and include petroleum-based waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant-based waxes and animal-based waxes; and synthetic waxes such as polymers of ethylene and propylene. These may be used individually or in combination of two or more types.

[0149] For example, waxes from companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd. can be used.

[0150] (f) Zinc oxide The rubber composition may contain zinc oxide. The zinc oxide content 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. Conventionally known zinc oxides can be used, such as products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc.

[0151] (t) Crosslinking agents and vulcanization accelerators The rubber composition preferably contains a crosslinking agent such as sulfur. The crosslinking agent content 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.

[0152] Examples of sulfur commonly used in the rubber industry include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur. These may be used individually or in combination of two or more types.

[0153] For sulfur, products from companies such as Tsurumi Chemical Industries, Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Co., Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., and Hosoi Chemical Industries Co., Ltd. can be used.

[0154] Other crosslinking agents besides sulfur include, for example, sulfur-containing vulcanizing agents such as Tackyrol V200 manufactured by Taoka Chemical Industries, Ltd. and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by Lanxess, as well as organic peroxides such as dicumyl peroxide.

[0155] The rubber composition preferably contains a vulcanization accelerator. The amount of 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.

[0156] Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; 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-benzothiazolesulfenamide, Nt-butyl-2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diortotrilguanidine, and orthotrilbiguanidine. These may be used individually or in combination of two or more.

[0157] (Chi) Others In addition to the above-mentioned components, the rubber composition may further contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylate metal salts, organic peroxides, and reversion (vulcanization reversal) inhibitors, as needed. 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.

[0158] (2) Preparation of rubber composition The rubber composition that forms the cap rubber layer is produced by appropriately adjusting the various compounding materials described above, using a general method that includes a base mixing step of mixing rubber components with a filler such as carbon black, and a finish mixing step of mixing the mixture obtained in the base mixing step with a crosslinking agent.

[0159] Mixing can be carried out using known (closed) mixers such as Banbury mixers, kneaders, and open roll mixers.

[0160] The mixing temperature in the base mixing process is, for example, more than 50°C and less than 200°C, and the mixing time is, for example, more than 30 seconds and less than 30 minutes. In the base mixing process, in addition to the above components, compounding agents conventionally used in the rubber industry, such as softeners such as oils, zinc oxide, antioxidants, waxes, and vulcanization accelerators, may be added and mixed as needed.

[0161] In the final mixing step, the mixture obtained in the base mixing step and the crosslinking agent are mixed together. The mixing temperature in the final mixing step is, for example, above room temperature but below 80°C, and the mixing time is, for example, more than 1 minute but less than 15 minutes. In the final mixing step, in addition to the above components, vulcanization accelerators, zinc oxide, etc., may be added and mixed as needed.

[0162] 2. Tire manufacturing The tire according to the present invention can be manufactured as an unvulcanized tire by first forming the rubber composition obtained above as a cap rubber layer into a tread rubber of a predetermined shape, and then molding it together with other tire components on a tire molding machine in a conventional manner.

[0163] Furthermore, when the tread section is to have a multi-layer structure with the base rubber layer, a rubber composition for forming the base rubber layer can be obtained by using the above-mentioned rubber components and compounding materials, appropriately changing their proportions, and kneading them in the same manner. Then, after extruding it together with the cap rubber layer to form a tread rubber of a predetermined shape, it can be manufactured as an unvulcanized tire by molding it together with other tire components on a tire molding machine in a normal manner.

[0164] Specifically, an inner liner (a component to ensure the airtightness of the tire), a carcass (a component to withstand the load, impact, and air pressure of the tire), and a belt (a component to tightly fasten the carcass and increase the rigidity of the tread) are wound onto a molding drum. The ends of the carcass are fixed to both side edges, and a bead (a component to fix the tire to the rim) is placed to form a toroid shape. After forming the toroid, the tread is attached to the center of the outer circumference, and the sidewall is attached to the radially outward side to form the side section, thereby creating an unvulcanized tire.

[0165] Subsequently, the prepared unvulcanized tire is heated and pressurized in a vulcanizing machine to obtain a tire. The vulcanization process can be carried out by applying known vulcanization methods. The vulcanization temperature is, for example, above 120°C and below 200°C, and the vulcanization time is, for example, above 5 minutes and below 15 minutes.

[0166] As mentioned above, the resulting tire can significantly improve wear resistance at high speeds due to the reinforcing effect of silica in the rubber composition, the deformation mitigation effect due to the appropriate amount of styrene, the slip suppression effect on the tread surface due to the appropriate 30°C tanδ, and the heat accumulation suppression effect due to appropriate thickness control.

[0167] The tire according to the present invention is not particularly limited to any category and can be used as a passenger car tire, a heavy-duty vehicle tire such as a truck or bus, a motorcycle tire, a run-flat tire, a non-pneumatic tire, etc., but it is preferable to use it as a passenger car tire. Furthermore, it is preferable to use it as a pneumatic tire. [Examples]

[0168] The following examples (case studies) are shown as preferred for implementation, but the scope of the present invention is not limited to these examples. In the examples, pneumatic tires (tire size 205 / 55R16, aspect ratio: 55%, land ratio: 65%) made from compositions obtained by changing the formulation according to each table using the various chemicals shown below were examined, and the results calculated based on the evaluation method below are shown in Tables 2 and 3.

[0169] 1. Rubber composition for forming the cap rubber layer (1) Compounding materials (a) Rubber component (i) SBR-1: Modified S-SBR obtained by the method described in the next paragraph. (Styrene content: 25% by mass, Vinyl content: 25% by mass) (b) SBR-2: HPR850 (modified S-SBR) manufactured by JSR Corporation (Styrene content: 27.5% by mass, Vinyl content: 59.0% by mass) (h) SBR-3: HPR840 (S-SBR) manufactured by JSR Corporation (Styrene content: 10% by mass, vinyl content: 42% by mass) (ii) BR: Ube Pole BR150B (High-Sys BR) from Ube Industries, Ltd. (Cis content 97% by mass, trans content 2% by mass, vinyl content 1% by mass)

[0170] (Manufacturing of SBR-1) The above SBR-1 is prepared according to the following procedure. First, two autoclaves with a total volume of 10 L, an inlet at the bottom and an outlet at the top, equipped with a stirrer and a jacket, are connected in series as reactors, and butadiene, styrene, and cyclohexane are mixed in predetermined ratios. This mixed solution is passed through a dehydration column packed with activated alumina, and after mixing with n-butyllithium in a static mixer to remove impurities, it is continuously supplied from the bottom of the first reactor. Furthermore, 2,2-bis(2-oxolanil)propane as a polar substance and n-butyllithium as a polymerization initiator are continuously supplied from the bottom of the first reactor at predetermined rates, and the reactor temperature is maintained at 95°C. The polymer solution is continuously withdrawn from the top of the reactor and supplied to the second reactor. The temperature of the second reactor is maintained at 95°C, and a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane (monomer) and the oligomer component is continuously added at a predetermined rate as a 1000-fold dilution of cyclohexane to carry out the modification reaction. This polymer solution is continuously withdrawn from the reactor, and an antioxidant is continuously added using a static mixer. After removing the solvent, the target modified diene polymer (SBR-1) is obtained.

[0171] The vinyl content (in mass%) of SBR-1 was determined by infrared spectroscopy to be at the absorption peak of the vinyl group, 910 cm⁻¹. -1 The absorption intensity in the vicinity is used to determine the amount of styrene (unit: mass%), which is determined from the refractive index according to JIS K6383 (1995).

[0172] (b) Compounding materials other than rubber components (i) Carbon black: Dia Black N220 manufactured by Mitsubishi Chemical Corporation (N2SA:115m 2 / g) (b) Silica: UltraSil VN3 manufactured by Evonik Industries (N2SA:175m 2 / g, average primary particle diameter: 17nm) (h) Silane coupling agent: Si266 manufactured by Evonik Industries (Bis(3-triethoxysilylpropyl) disulfide) (ii) Resin: SYLVATRAXX4401 manufactured by Kraton (α-methylstyrene resin) (H) Oil: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd. (Aromatic process oils) (H) Stearic acid: Beads stearic acid "Tsubaki" manufactured by NOF Corporation (T) Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. (C) Anti-aging agent-1: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd. (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) (R) Anti-aging agent-2: Antigen RD manufactured by Sumitomo Chemical Co., Ltd. (polymer of 2,2,4-trimethyl-1,2-dihydroquinoline) (Nu) Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. (L) Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industries Co., Ltd. (containing 5% oil) (Wo) Vulcanization accelerator-1: Noxellar CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-cyclohexyl-2-benzothiadylsulfenamide (CBS)) (W) Vulcanization accelerator-2: Soxyl D (DPG) manufactured by Sumitomo Chemical Co., Ltd. (N,N'-diphenylguanidine)

[0173] (2) Rubber composition for forming the cap rubber layer According to the formulations shown in Tables 2 and 3, the materials other than sulfur and vulcanization accelerator were mixed in a Banbury mixer for 5 minutes at 150°C to obtain the mixture. The amounts of each ingredient are in parts by mass.

[0174] Next, sulfur and a vulcanization accelerator are added to the mixture, and the mixture is kneaded using an open roll at 80°C for 5 minutes to obtain a rubber composition that forms the cap rubber layer.

[0175] 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 in the production of the rubber composition for forming the cap rubber layer.

[0176] [Table 1]

[0177] 3. Manufacturing of pneumatic tires Each rubber composition is extruded into a predetermined shape such that the ratio of (thickness of the cap rubber layer / thickness of the base rubber layer) is 80 / 20, forming a tread section with a thickness G (mm) as shown in Tables 2 and 3.

[0178] Subsequently, the tire components are bonded together to form an unvulcanized tire, which is then press-vulcanized for 10 minutes under conditions of 170°C to produce the pneumatic tires (test tires) shown in Examples 1 to 7 and Comparative Examples 1 to 11 in Tables 2 and 3.

[0179] 4. Calculation of parameters Subsequently, the following parameters are determined for each test tire.

[0180] (1) Loss tangent (tanδ) A rubber test specimen for viscoelasticity measurement was prepared by cutting a piece measuring 20 mm in length, 4 mm in width, and 2 mm in thickness from the cap rubber layer of the tread of each test tire, with the tire circumference being the longer side. For each rubber test specimen, the tanδ was measured using a GABO Iplexer series at a frequency of 10 Hz, initial strain of 5%, dynamic strain of 1%, deformation mode: tensile, and measurement temperatures of 0°C and 30°C, respectively. The tanδ at 0°C and 30°C were then determined. The tanδ at 30°C for the base rubber layer was assumed to be 0.07.

[0181] Then, (30°C tanδ / G) is calculated based on the 30°C tanδ of the cap rubber layer and the tread thickness G (mm).

[0182] (2) Tg For rubber test pieces for viscoelasticity measurement, similarly cut from the cap rubber layer, tanδ is measured using GABO's "Iplexer®" under the conditions of frequency 10 Hz, initial strain 2%, amplitude ±1%, and heating rate 2°C / min, while the temperature is varied from -60°C to 40°C. Tg is then determined by the method described above.

[0183] (3) Complex modulus of elasticity (E * ) For rubber test pieces for viscoelasticity measurement, similarly cut from the cap rubber layer, the following conditions were met using a GABO iplexer series under the following conditions: frequency 10 Hz, initial strain 5%, dynamic strain 1%, deformation mode: elongation, measurement temperature: 0°C, 30°C, E * (MPa) was measured, and each was measured at 0℃E * , 30℃E * We will determine the value of the base rubber layer at 30°E. * The pressure will be set to 4.0 MPa.

[0184] And then, 30℃E * Based on (MPa) and the tread thickness G (mm), (30℃E * Calculate / G).

[0185] (4) Acetone extract (AE) from the cap rubber layer Using vulcanized rubber test pieces cut from the cap rubber layer of the tread section of each test tire, the AE (mass%) is determined in accordance with JIS K 6229:2015.

[0186] (5) (SBR content / land ratio), (silica content / flatness ratio) In addition, based on the specifications and compound composition of each test tire, the ratio of the styrene-butadiene rubber (SBR) content (parts by mass) with a styrene content of 25% by mass or less per 100 parts by mass of rubber component to the land ratio (%) in the tread section (SBR content / land ratio), and the ratio of the silica content (parts by mass) to the aspect ratio (%) per 100 parts by mass of rubber component (silica content / aspect ratio) will be calculated.

[0187] 5. Performance evaluation test (evaluation of wear resistance performance during high-speed driving) Each test tire was mounted on all wheels of a vehicle (a domestically produced front-wheel-drive car with a 2000cc engine), inflated to an internal pressure of 250kPa (the standard internal pressure for passenger cars), and driven 8000km at 100km / h on a test course. After that, the groove depth of the tread was measured, and the degree of reduction was determined. The distance traveled corresponding to a 1mm reduction in groove depth was then calculated.

[0188] Next, the results in Comparative Example 8 are set to 100 and indexed based on the following formula to evaluate the wear resistance performance during high-speed driving. A higher numerical value indicates better wear resistance performance during high-speed driving. Wear resistance during high-speed driving =[(Results of the test tire) / (Results of Comparative Example 8)]×100

[0189] [Table 2]

[0190] [Table 3]

[0191] Although the present invention has been described above based on embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments within the same and equivalent scope as the present invention.

[0192] The present invention (1) is, A tire having a tread section, The cap rubber layer that forms the tread portion The styrene-butadiene rubber (SBR) is contained in a form where the amount of styrene in the total SBR is 25% by mass or less, and the rubber component contains 60 parts by mass or more and 80 parts by mass or less per 100 parts by mass. The rubber component contains less than 100 parts by mass of silica per 100 parts by mass of the rubber component, Under conditions of temperature 30°C, frequency 10Hz, initial strain 5%, and dynamic strain 1%, the loss loss tangent (30°C tanδ) measured in the deformation mode: tensile is greater than 0.25. Furthermore, under conditions of temperature 0°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1%, the loss tangent (0°C tanδ) measured in the deformation mode: tensile is 0.60 or greater. It is formed from a rubber composition, The tire is characterized in that the thickness of the tread portion is 15 mm or less.

[0193] The present invention (2) is, The tire is characterized in that the tanδ at 30°C is 0.30 or greater, as described in (1) of the present invention.

[0195] This invention ( 3 )teeth, The present invention is characterized in that the tanδ at 0°C is 0.70 or higher. 1) or (2) These are the tires listed.

[0196] This invention ( 4 )teeth, The glass transition temperature (Tg) of the aforementioned cap rubber layer is -15°C or lower, and the present invention (1) to ( 3 This is a tire in any combination of any of the following:

[0197] This invention ( 5 )teeth, The complex modulus of elasticity (30°CE) of the aforementioned cap rubber layer was measured at a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, a dynamic strain of 1%, and the deformation mode was elongation. * ) is characterized by being 6.0 MPa or less, and the present invention (1) to ( 4 This is a tire in any combination of any of the following:

[0198] This invention ( 6 )teeth, The aforementioned 30℃E * (MPa) and the thickness of the tread portion (mm) are equal to (30℃E * The present invention is characterized by satisfying the condition (thickness of the tread portion) ≥ 0.50, and from (1) 5 This is a tire in any combination of any of the following:

[0199] This invention (7 )teeth, The complex modulus of elasticity (0°CE) of the aforementioned cap rubber layer was measured at a temperature of 0°C, a frequency of 10Hz, an initial strain of 5%, a dynamic strain of 1%, and the deformation mode was elongation. * ) is characterized by being 25.0 MPa or less, and the present invention (1) to ( 6 This is a tire in any combination of any of the following:

[0200] This invention ( 8 )teeth, The tread portion is characterized by having a thickness of 4 mm or more and 11 mm or less, and the present invention (1) to ( 7 This is a tire in any combination of any of the following:

[0201] This invention ( 9 )teeth, The present invention is characterized in that the thickness of the cap rubber layer is 10% or more and less than 100% of the total thickness of the tread portion, and (1) to ( 8 This is a tire in any combination of any of the following:

[0202] This invention ( 10 )teeth, The cap rubber layer is characterized by containing a resin component selected from the group consisting of rosin resin, styrene resin, coumarone resin, terpene resin, C5 resin, C9 resin, C5C9 resin, and acrylic resin, and the present invention (1) to ( 9 This is a tire in any combination of any of the following:

[0203] This invention ( 11 )teeth, The present invention is characterized in that the 30°C tanδ of the cap rubber layer and the thickness of the tread portion (mm) satisfy (30°C tanδ / thickness of tread portion) > 0.03, and from (1) of the present invention ( 10 This is a tire in any combination of any of the following:

[0204] This invention ( 12 )teeth, The land ratio in the tread portion is 40% or more. The present invention is characterized in that the ratio of the content (parts by mass) of styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less in 100 parts by mass of rubber component to the land ratio (%) in the tread portion (SBR content with a styrene content of 25% by mass or less (parts by mass) / land ratio (%)) is 1.2 or less, and from (1) to ( 11 This is a tire in any combination of any of the following:

[0205] This invention ( 13 )teeth, The aspect ratio is 80% or less. The present invention is characterized in that the ratio of the silica content (parts by mass) to the flattening ratio (%) per 100 parts by mass of rubber component (silica content (parts by mass) / flattening ratio (%)) is 1.7 or more, and (1) to ( 12 This is a tire in any combination of any of the following:

Claims

1. A tire having a tread section, The cap rubber layer that forms the tread portion Styrene-butadiene rubber (SBR) is contained in a form where the amount of styrene in the total SBR is 25% by mass or less, and 60 parts by mass or more and 80 parts by mass or less per 100 parts by mass of rubber component, The rubber component contains less than 100 parts by mass of silica per 100 parts by mass of the rubber component, The rubber composition is formed such that the loss tangent (30°C tanδ) measured under the conditions of temperature 30°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1% in tensile deformation mode is greater than 0.25, and the loss tangent (0°C tanδ) measured under the conditions of temperature 0°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1% in tensile deformation mode is 0.60 or greater. A tire characterized in that the thickness of the tread portion is 15 mm or less.

2. The tire according to claim 1, characterized in that the 30°C tanδ is 0.30 or more.

3. The tire according to claim 1 or 2, characterized in that the tanδ at 0°C is 0.70 or greater.

4. The tire according to claim 1 or 2, characterized in that the glass transition temperature (Tg) of the cap rubber layer is -15°C or lower.

5. The complex modulus of elasticity (30°C E) of the aforementioned cap rubber layer was measured at a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of 1%, and the deformation mode was elongation. ＊ The tire according to claim 1 or 2, characterized in that the pressure is 6.0 MPa or less.

6. The aforementioned 30°C E ＊ (MPa) and the thickness of the tread portion (mm) are equal to (30℃E ＊ The tire according to claim 1 or 2, characterized in that it satisfies the condition (thickness of the tread portion) ≥ 0.

50.

7. The complex modulus of elasticity (0°C E) of the aforementioned cap rubber layer was measured at a temperature of 0°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of 1%, and the deformation mode was elongation. ＊ The tire according to claim 1 or 2, characterized in that the pressure is 25.0 MPa or less.

8. The tire according to claim 1 or 2, characterized in that the thickness of the tread portion is 4 mm or more and 11 mm or less.

9. The tire according to claim 1 or 2, characterized in that the thickness of the cap rubber layer is 10% or more and less than 100% of the total thickness of the tread portion.

10. The tire according to claim 1 or 2, characterized in that the cap rubber layer contains a resin component selected from the group consisting of rosin resin, styrene resin, coumarone resin, terpene resin, C5 resin, C9 resin, C5C9 resin, and acrylic resin.

11. The tire according to claim 1 or 2, characterized in that the 30°C tanδ of the cap rubber layer and the thickness of the tread portion (mm) satisfy the condition (30°C tanδ / tread portion thickness) > 0.

03.

12. The land ratio in the tread portion is 40% or more. The tire according to claim 1 or 2, characterized in that the ratio of the content (parts by mass) of styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less in 100 parts by mass of rubber component to the land ratio (%) in the tread portion (content of SBR with a styrene content of 25% by mass or less (parts by mass) / land ratio (%)) is 1.2 or less.

13. The aspect ratio is 80% or less. The tire according to claim 1 or 2, characterized in that the ratio of the silica content (parts by mass) per 100 parts by mass of rubber component to the aspect ratio (%) (silica content (parts by mass) / aspect ratio (%)) is 1.7 or more.

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