tire

Abstract

To improve grip performance on icy and snowy road surfaces.SOLUTION: A tire includes a tread part. A cap rubber layer forming the tread part is formed from a rubber composition which contains 40 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. The rubber composition has a loss tangent (-30°C tanδ) of 0.10 or greater 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 10 mm or greater and 20 mm or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Tires are required to have high braking performance (grip performance) for safety reasons, and various technologies have been proposed to improve grip performance (for example, Patent Documents 1 to 3). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2011-93386 [Patent Document 2] Japanese Patent Publication No. 2013-79017 [Patent Document 3] Japanese Patent Publication No. 2016-37100 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, tires manufactured based on the conventional technology described above still do not offer sufficient grip performance on icy and snowy surfaces, and further improvements are strongly desired.

[0005] Therefore, the objective of this invention is to improve grip performance on icy and snowy road surfaces. [Means for solving the problem]

[0006] The present invention A tire having a tread section, The cap rubber layer that forms the tread portion Styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less is contained in 40 parts by mass or less per 100 parts by mass of the rubber component. 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 loss tangent (-30°C tanδ) measured in the deformation mode: tension is 0.10 or more, the law of nature, Under conditions of temperature 0°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1%, the loss loss tangent (0°C tanδ) measured in the deformation mode: tensile is 0.30 or greater. and it is formed from a rubber composition, the thickness T of the tread portion is 10 mm or more and 20 mm or less, furthermore, the department tread thickness T (mm) and The aforementioned the -30 ℃t tanδ of the cap rubber layer satisfy the following formula, and it is a tire characterized by this. -30°C tanδ / T ≥ 0.022

Effects of the Invention

[0007] According to the present invention, it is possible to improve the grip performance on icy and snowy road surfaces.

Modes for Carrying Out the Invention

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

[0009] The tire according to the present invention is a tire provided with a tread portion, and the cap rubber layer forming the tread portion contains 40 parts by mass or less of SBR having a styrene content of 25% by mass or less in 100 parts by mass of the rubber component. 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 loss tangent (-30°C tanδ) measured in the deformation mode: tension is 0.10 or more, Furthermore, under conditions of temperature 0°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1%, the loss loss tangent (0°C tanδ) measured in the deformation mode: tensile is 0.30 or greater. and it is formed from a rubber composition. And the thickness of the tread portion is 10 mm or more and 20 mm or less. And the ratio of -30 ℃t tanδ of the cap rubber layer to the department tread thickness T (mm) (-30°C tanδ / T )but is 0.022 or more.

[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 grip performance on icy and snowy roads.

[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 tire cap rubber layer according to the present invention contains 40 parts by mass or less of SBR with a styrene content of 25% by mass or less per 100 parts by mass of rubber component.

[0014] SBR with a low styrene content, specifically 25% by mass or less, has a low glass transition temperature (Tg). By incorporating such low-styrene SBR into the rubber component, the rubber can maintain its softness even at low temperatures, improving its ability to conform to icy and snowy road surfaces.

[0015] At the same time, by including 40 parts by mass or less of SBR with a low styrene content (styrene content of 25% by mass or less), minute styrene domains can be appropriately formed on the rubber surface, making it easier to grip the road surface.

[0016] Furthermore, the presence of minute styrene domains generates friction with other polymer molecular chains, allowing for moderate heat generation even at low temperatures, thus facilitating friction on icy and snowy road surfaces. These minute styrene domains also provide a scratching effect on icy and snowy surfaces.

[0017] 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.

[0018] In this invention, "containing 40 parts by mass or less of SBR with a styrene content of 25% by mass or less per 100 parts by mass of rubber component" means that the amount of SBR in 100 parts by mass of rubber component is 40 parts by mass or less, and the amount of styrene in the total SBR is 25% by mass or less.

[0019] 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.

[0020] 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.

[0021] 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).

[0022] In the present invention, the loss loss tangent (-30°C tanδ) of the rubber composition forming the cap rubber layer, measured under the conditions of temperature -30°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1%, with deformation mode: tensile, is 0.10 or higher.

[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℃, a temperature lower than that of an icy or snowy road surface, is set to 0.10 or higher. Therefore, even in a low-temperature atmosphere, sufficient energy during rolling can be absorbed and converted into heat, ensuring heat generation and improving grip performance. A value of 0.50 or higher is more preferable, and 0.65 or higher is even more preferable. There is no particular upper limit, but a value of 0.85 or lower is preferable, 0.80 or lower is more preferable, and 0.75 or lower is even more preferable.

[0024] Furthermore, considering that the ambient temperature of the icy and snowy road surface is around 0°C, 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 preferably 0.30 or higher, more preferably 0.35 or higher, and even more preferably 0.45 or higher. The higher the 0°C tanδ, the greater the energy loss on the icy and snowy road surface, which improves heat generation and thus improves grip performance.

[0025] On the other hand, if the tread area becomes excessively heated, the ice may melt and cause slippage. Therefore, it is preferable to keep tanδ low when the area is heated to a certain extent. For example, under conditions of a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain rate of 1%, the loss loss tangent (30°C tanδ) measured in the deformation mode: tensile is preferably 0.20 or less, and more preferably 0.13 or less.

[0026] In the above, the loss tangent (tanδ) can be measured using a viscoelasticity measuring device such as the "Iplexer®" manufactured by GABO.

[0027] The -30°C tanδ, 0°C tanδ, and 30°C tanδ values ​​mentioned above can be adjusted by appropriately changing the content of each compounding material, as described later. For example, the -30°C tanδ can be increased by increasing the styrene content in the SBR, increasing the styrene content in the rubber component, or increasing the amount of resin component. Conversely, it can be decreased by decreasing the styrene content in the SBR, decreasing the styrene content in the rubber component, or decreasing the amount of resin component. The 0°C tanδ and 30°C tanδ can also be increased by increasing the styrene content in the SBR, increasing the styrene content in the rubber component, increasing the amount of resin component, or increasing the amount of fillers such as silica and carbon black. Conversely, they can be decreased by decreasing the styrene content in the SBR, decreasing the styrene content in the rubber component, decreasing the amount of resin component, or decreasing the amount of silica and carbon black.

[0028] Furthermore, in the tire according to the present invention, as described above, the thickness of the tread portion is set to 10 mm or more and 20 mm or less. This makes the entire tread portion more flexible and deformable, improving contact with the ground and thus improving grip performance. It is more preferable that the thickness be 12 mm or more and 18 mm or less, and even more preferable that it be 14 mm or more and 16 mm or less.

[0029] The aforementioned 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] As described above, the tire according to the present invention can improve grip performance on icy and snowy roads because it is possible to obtain grip and friction on ice and snow by the styrene domain while increasing contact with the ground.

[0034] [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.

[0035] 1. Glass transition temperature (Tg) of the cap rubber layer When a rubber composition with a high glass transition temperature (Tg) is used to form the cap rubber layer, the tread portion hardens at temperatures near the driving temperature, which may worsen the ability to follow the road surface. Therefore, in order to improve grip performance on icy and snowy roads, it is preferable to lower the glass transition temperature (Tg) of the rubber composition to reduce the hardness of the rubber in the low-temperature range, and specifically, it is preferable that it be -40°C or lower.

[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 -70°C to 30°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 -70°C to 30°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 -70°C to 30°C, then according to the above definition, the temperature at which that maximum value is shown is Tg. Also, for example, if a temperature distribution curve is obtained in which tanδ gradually decreases with increasing temperature within the range of -70°C to 30°C, and the temperature at which tanδ is shown to be the maximum value is -70°C, then according to the above definition, the glass transition temperature (Tg) is -70°C.

[0037] Furthermore, the glass transition temperature (Tg) of the rubber composition can be adjusted, similar to tanδ as described above, by appropriately changing the content of each compounding material, as will be described later. For example, it can be increased by increasing the amount of SBR in the rubber component, increasing the styrene content within the SBR component, increasing the amount of resin component, or using a resin component with a high softening point. Conversely, it can be decreased by decreasing the amount of SBR in the rubber component, decreasing the styrene content within the SBR component, decreasing the amount of resin component, or using a resin component with a low softening point.

[0038] 2. Relationship between tanδ of the cap rubber layer at -30°C and tread thickness As mentioned above, in this invention, the tread thickness is set to 10 mm or more to facilitate contact with the ground on the tread surface. Among these, the tanδ of the cap rubber at -30°C (-30℃ tanδ) The tread thickness T (mm) and -30℃ tanδ / T ≧0.022 By increasing the tanδ of the cap rubber layer at low temperatures relative to the tread thickness in order to satisfy this relationship, it becomes easier to improve contact with the ground while also achieving even greater surface grip performance.

[0039] 3. Multi-layering of the tread area In the present invention, the tread portion may be formed by only one cap rubber layer, or by providing a base rubber layer inside the cap rubber layer to form two layers, or three layers, or even four or more layers. In this case, it is preferable that the thickness of the cap rubber layer in the entire tread portion is 10% or more. This makes it possible to generate sufficient friction between the tread surface and the road surface and transmit sufficient frictional force to the inside of the tire, thereby significantly improving grip performance on icy and snowy roads. Furthermore, considering the generation of friction between the tread surface and the road surface, it is more preferable that the thickness of the cap rubber layer in the entire tread portion is 70% or more.

[0040] 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.

[0041] In this case, it is preferable to make the 30°C tanδ of the base rubber layer greater than that of the cap rubber layer. As mentioned above, it is desirable that the 30°C tanδ of the cap rubber layer be low from the viewpoint of suppressing the tread surface temperature from rising, which would melt ice on the road surface and cause slippage. This increases the heat generation of the base rubber layer inside, making it easier for energy loss to occur inside the tire, and thus making it easier for energy loss to occur throughout the tread, which is thought to result in excellent grip performance.

[0042] Furthermore, in the case of a multi-layered tread section, it is preferable that the complex modulus of elasticity measured at a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode of elongation of the base rubber layer is greater than the complex modulus of elasticity measured at -30°C for the cap rubber layer. These complex moduli can be measured using a viscoelasticity measuring device such as the "Iplexer®" manufactured by GABO.

[0043] The complex modulus of elasticity is a parameter that indicates the stiffness of the rubber layer. The temperature inside the tire, such as the base rubber layer, is thought to be higher than the surface temperature during driving. Therefore, by making the complex modulus of elasticity of the base rubber layer at 30°C greater than that of the cap rubber layer at -30°C, it is possible to suppress excessive deformation of the tread rubber in the base rubber layer after the tread surface follows the road surface during driving, making it easier to generate reaction force, and thus obtaining excellent grip performance.

[0044] 4. Silica content in the cap rubber layer In the present invention, it is preferable that the rubber composition forming the cap rubber layer contains silica. By including silica, friction is more easily generated between the flexibly moving minute styrene domains and the silica, further increasing heat generation and improving grip performance on icy and snowy road surfaces.

[0045] Specifically, the content is preferably more than 50 parts by mass, more preferably more than 75 parts by mass, and even more preferably 85 parts by mass or more, per 100 parts by mass of rubber component. There is no particular upper limit, but considering the kneading and molding properties of the rubber composition, it is preferably 150 parts by mass or less, more preferably 130 parts by mass or less, and even more preferably 110 parts by mass or less.

[0046] In this invention, the particle size (average primary particle size) of the silica is preferably 17 nm or less, taking into consideration factors such as the ease of friction with the polymer.

[0047] 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.

[0048] 5. 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.

[0049] It is believed that by including a resin component in the rubber composition, grip on the road surface can be ensured due to the adhesive properties of the resin component.

[0050] Preferred resin components include rosin resins, styrene resins, coumarone resins, terpene resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, which will be described later. Among these, styrene resins such as α-methylstyrene are more preferred. The content of the resin per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 25 parts by mass or more.

[0051] 6. Acetone extract (AE) from the cap rubber layer In the present invention, the acetone extract (AE) in the cap rubber layer is preferably 5% by mass or more, more preferably 8% by mass or more, and even more preferably 11% by mass or more. On the other hand, there is no particular upper limit, but it is preferably 17% by mass or less, more preferably 14% by mass or less, and even more preferably 15% by mass or less.

[0052] Acetone extract (AE) can be considered an indicator of the amount of softeners and other components in a rubber composition. The higher the amount of AE, the more flexibly the rubber molecules can move, resulting in better road surface conformity. Therefore, as described above, when the amount of AE in the cap rubber layer is increased to a certain extent, a sufficient contact area between the tire and the road surface can be secured, allowing for stable and excellent grip performance.

[0053] 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.

[0054] Furthermore, the aforementioned acetone extract can be appropriately modified by changing the blending ratio of plasticizers in the rubber composition.

[0055] 7. Styrene content in rubber components and land ratio (1) Rand ratio In the tire according to the present invention, the land ratio in the tread portion of the tire, when mounted on a regular rim and subjected to regular internal pressure, is preferably 55% or more, more preferably 60% or more, and even more preferably 63% or more.

[0056] The "land ratio" is the ratio of the actual contact area to the hypothetical contact area created by filling all the grooves on the surface of the tread. A larger land ratio means a larger contact area with the road surface, resulting in stable and sufficient grip performance.

[0057] The land ratio is not particularly limited to an upper limit, but is preferably 85% or less, more preferably 80% or less, and even more preferably 75% or less.

[0058] The above-mentioned land ratio can be determined from the contact patch shape under normal rim, normal internal pressure, and normal load conditions.

[0059] 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.

[0060] 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 (%).

[0061] The "standard internal pressure" mentioned above refers to the air pressure specified for each tire by each standard in the standards system, including the standard on which the aforementioned tire is based. For JATMA, it refers to the maximum air pressure; for ETRTO, it refers to "INFLATION PRESSURE"; and for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with the "standard rim," refer to JATMA, ETRTO, and TRA in that order and follow their respective standards. In the case of tires not specified in the standards, it refers to the standard internal pressure (but 250 kPa or higher) of another tire size (specified in the standards) that lists the aforementioned standard rim as the standard rim. If multiple standard internal pressures of 250 kPa or higher are listed, refer to the lowest value among them.

[0062] Furthermore, "regular 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". Similar to the cases of "regular rim" and "regular internal pressure" mentioned above, refer to JATMA, ETRTO, and TRA in that order and follow their respective standards. In the case of tires not specified in the standards, the regular 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)

[0063] (2) Amount of styrene in the rubber component Furthermore, in the present invention, the amount of styrene contained in 100 parts by mass of the rubber component is preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less. There is no particular lower limit, but it is preferably 2% by mass or more, more preferably 3% by mass or more, and even more preferably 4% by mass or more.

[0064] The "amount of styrene in the rubber component" mentioned above refers to the amount of styrene derived from the rubber component contained in 100 parts by mass of the rubber component, excluding the amount of styrene from acetone-soluble components such as resin components. If the rubber component contains multiple styrene-containing polymers, it can be calculated from the product of the styrene content of each polymer and the polymer content. For example, if 100 parts by mass of the rubber component contains X1 parts by mass of SBR with styrene content A1 and X2 parts by mass of SBR with styrene content A2, it can be calculated as (A1 × X1 + A2 × X2) / 100.

[0065] (3) Relationship between the amount of styrene in the rubber component and the land ratio

[0066] Furthermore, in the present invention, the ratio of the amount of styrene (mass%) in the rubber component to the land ratio (%) is preferably 0.10 or less, and more preferably 0.08 or less.

[0067] The styrene portion in the rubber component forms styrene-derived domains, and it is believed that these domains can bite into the road surface, thereby improving grip performance on icy and snowy surfaces. However, if an excessive amount of styrene domains are formed on the tread surface, it is thought that this can actually make it more difficult for the styrene domains to bite into the road surface. Therefore, by keeping the amount of styrene in the rubber component below a certain level relative to the land ratio, which is the actual contact area ratio, it is thought that the styrene domains will bite into the icy and snowy surface more easily, thereby improving grip performance.

[0068] 8. Styrene content in rubber components and tread thickness In the tire according to the present invention, the product of the amount of styrene (mass%) in the rubber component and the thickness of the tread (mm) is preferably 100 or less, more preferably 80 or less, and even more preferably 60 or less. On the other hand, there is no particular lower limit, but it is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more.

[0069] Styrene domains formed within the rubber component can generate heat through friction with other rubber molecular chains. However, if this occurs excessively, it can lead to excessive heat generation during rolling, potentially raising the tread surface temperature. Therefore, by keeping the product of the tread thickness below a certain level, heat can be more easily dissipated from the tread and heat accumulation can be suppressed, which is thought to improve grip performance on icy and snowy surfaces.

[0070] 9. Flatness The aspect ratio is the ratio of the tire's cross-sectional height to its cross-sectional width. A smaller aspect ratio reduces the proportion of the tire that deforms in the width direction relative to the friction generated by the tread, making it easier to transmit force and thus improving grip performance. On the other hand, a lower aspect ratio reduces the amount of deflection in the sidewall, which may lead to a deterioration in ride comfort.

[0071] Considering these points, in the tire according to the present invention, the specific aspect ratio is preferably 30% or more and 60% or less.

[0072] 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

[0073] [3] Embodiment The present invention will be described in detail 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 type and amount 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 be modified as described below. In addition, stretched rubber, which has been pre-stretched with plasticizer components such as oil, resin, or liquid rubber, may be used with these rubber components.

[0076] In the present invention, among these, the rubber component contains styrene, and it is preferable that it contains one of the styrene-based polymers such as SBR, SBS, and SB. Furthermore, these styrene-based polymers may be used in combination with other rubber components, for example, a combination of SBR and BR, or a combination of SBR, 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 40 parts by mass or less, as described above, but is more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less. On the other hand, the lower limit is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more.

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

[0085] As the modified SBR modified with the compound (modifying agent) represented by the above formula, SBR in which the polymerization terminal (active terminal) of solution-polymerized styrene-butadiene rubber (S-SBR) is modified with the compound represented by the above formula (modified SBR described in JP-A-2010-111753, etc.) can be used.

[0086] R 1 and R 2 and R 3 An alkoxy group is preferable as (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). R 4 and R 5 An alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is preferable as. n is preferably 1 to 5, more preferably 2 to 4, and still more preferably 3. Also, when R 4 and R 5 combine to form a ring structure together with the nitrogen atom, a 4- to 8-membered ring is preferable. Note that the alkoxy group includes a cycloalkoxy group (such as a cyclohexyloxy group) and an aryloxy group (such as a phenoxy group and a 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 per 100 parts by mass of the rubber component is preferably 10 parts by mass or more, and more preferably 15 parts by mass or more. On the other hand, it is preferably 30 parts by mass or less, and more preferably 25 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 contain isoprene-based rubber. In this case, the content of isoprene-based rubber in 100 parts by mass of the rubber component is preferably 30 parts by mass or more, and more preferably 50 parts by mass or more. On the other hand, it is preferably 70 parts by mass or less, and more preferably less than 60 parts by mass.

[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 this embodiment, the rubber composition preferably contains a filler. Specific fillers include, for example, silica, carbon black, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica.

[0099] (i-1) Silica In the present invention, the rubber composition preferably contains silica, and more preferably contains a silane coupling agent together with the silica.

[0100] The BET specific surface area of ​​silica is 140 m² from the perspective 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.

[0101] In the present invention, as described above, it is preferable to use silica with a particle size of 17 nm or less in the rubber composition that forms the outer cap rubber layer. By using silica with a small particle size, the frequency of contact with the polymer (styrene domain) can be increased, thereby improving grip performance. The lower limit is not particularly limited, but it is preferable to be 10 nm or more from the viewpoint of dispersibility during mixing.

[0102] When silica is used as a filler and reinforcing agent, it is preferably more than 50 parts by mass, more preferably more than 75 parts by mass, and even more preferably 85 parts by mass or more, per 100 parts by mass of the rubber component. However, as mentioned above, considering the kneading and molding properties of the rubber composition, it is preferably 150 parts by mass or less, more preferably 130 parts by mass or less, and even more preferably 110 parts by mass or less.

[0103] 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.

[0104] For example, silica products from companies such as Evonik Industries, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Ltd., and Tokuyama Corporation can be used.

[0105] (i-2) Silane coupling agent When silica is used as a filler and reinforcing agent, it is preferable that the rubber composition contains a silane coupling agent along with the 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.

[0106] 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.

[0107] 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.

[0108] (ii) Carbon Black In the present invention, the rubber composition preferably contains carbon black from the viewpoint of reinforcing properties.

[0109] The specific content ratio of carbon black per 100 parts by mass of rubber component is preferably 2 parts by mass or more, and more preferably 4 parts by mass or more. On the other hand, it is preferably 10 parts by mass or less, and more preferably 6 parts by mass or less.

[0110] 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.

[0111] 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 preferable that it is 170m or more / g. 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.

[0112] 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. In addition to the mineral oil-based carbon blacks mentioned above, carbon derived from lignin and other materials may also be used as appropriate.

[0113] (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, mica, and biochar, 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.

[0114] (b) Plasticizer components The rubber composition may contain 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 2 parts by mass or more, and more preferably 20 parts by mass or more, per 100 parts by mass of the rubber component. On the other hand, it is preferably 40 parts by mass or less, and more preferably 30 parts by mass or less. If extensible rubber is used as the rubber component, the amount of extensible component is also included in the plasticizer content. For example, if oil extensibility is used, the extensible oil is also included in the amount of oil described later.

[0115] (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 oils such as MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Dstillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract), as well as aromatic process oils and naphthenic process oils. 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 in rubber mixing mixers or as lubricants in automobile engines, or waste cooking oil, may be used as appropriate.

[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 more than 2 parts by mass and less than 45 parts by mass, and more preferably less than 30 parts by mass, 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 mixing machines such as Banbury mixers, kneaders, and open roll mixers.

[0160] The mixing temperature in the base mixing process is, for example, above 50°C and below 200°C, and the mixing time is, for example, above 30 seconds and below 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. There are no particular restrictions on the order in which the materials are added during mixing; the rubber components may be crushed in the mixer and then the fillers and softeners may be added, or the fillers and softeners may be mixed in the mixer beforehand and then the rubber components may be added.

[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 earlier, the resulting tire can improve contact with the ground while also allowing the styrene domains to grip ice and snow, thus significantly improving grip performance on icy and snowy surfaces.

[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 to 4.

[0169] 1. Rubber composition for forming the cap rubber layer (1) Compounding materials (a) Rubber component (i) NR: TSR20 (b) SBR-1: Modified S-SBR obtained by the method described in the next paragraph. (Styrene content: 25% by mass, vinyl content: 25% by mass) (H) SBR-2: HPR840 manufactured by JSR Corporation (Styrene content: 10% by mass, vinyl content: 42% by mass) (ii) BR: Ube Pole BR150B (High-Sys BR) manufactured by 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: H&R Vivatec 500 (Aromatic process oil: TDAE oil) (H) Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. (T) Anti-aging agent: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd. (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) (Chi) Stearic acid: Beads stearic acid "Tsubaki" manufactured by NOF Corporation (Re) Wax: Sunnock N manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (Nu) Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industries Co., Ltd. (containing 5% oil) (L) Vulcanization accelerator: Noxellar CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-cyclohexyl-2-benzothiadylsulfenamide (CBS))

[0173] (2) Rubber composition for forming the cap rubber layer According to the formulations shown in Tables 2 to 4, the materials other than sulfur and vulcanization accelerator are mixed in a Banbury mixer for 5 minutes at 150°C to obtain a mixture.

[0174] Next, sulfur and a vulcanization accelerator are added to the resulting 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 Using each of the obtained rubber compositions, extrude them into a predetermined shape such that the ratio of (thickness of the cap rubber layer / thickness of the base rubber layer) is 6 / 4, forming a tread section with a thickness T (mm) as shown in Tables 2 to 4.

[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) for Examples 1 to 12 shown in Tables 2 and 3, and the pneumatic tires (test tires) for Comparative Examples 1 to 6 shown in Table 4.

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

[0180] (1) tanδ From the cap rubber layer of the tread of each test tire, a rubber test piece measuring 20 mm in length, 4 mm in width, and 2 mm in thickness was cut out so that the longer side was in the circumferential direction of the tire. For each rubber test piece, 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 -30°C, 0°C, and 30°C, respectively. The tanδ values ​​for -30°C, 0°C, and 30°C were then determined. The 30°C tanδ of the base rubber layer was assumed to be 0.22.

[0181] Next, the -30°C tanδ / T (mm) is determined from the -30°C tanδ of the cap rubber layer and the thickness T (mm) of the tread portion.

[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 conditions of frequency 10 Hz, initial strain 2%, amplitude ±1%, and heating rate 2°C / min, while the temperature is varied from -70°C to 30°C. The temperature corresponding to the largest tanδ value in the resulting temperature distribution curve is determined as Tg.

[0183] (3) Complex modulus of elasticity The complex modulus (MPa) of rubber test specimens for viscoelasticity measurement, similarly cut from the cap rubber layer, was measured using a GABO Iplexer series under the conditions of -30°C, 10Hz frequency, 5% initial strain, and 1% dynamic strain, with the deformation mode being elongation. The complex modulus of the base rubber layer at 30°C was assumed to be 12.0 MPa.

[0184] (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.

[0185] (5) Other parameters Next, the amount of styrene (mass%) in the rubber component is determined, and further, the amount of styrene (mass%) in the rubber component multiplied by the tread thickness T (mm), and the amount of styrene (mass%) in the rubber component / land ratio (%) are calculated.

[0186] 5. Performance evaluation test (evaluation of grip performance on icy and snowy road surfaces) Each test tire is mounted on all wheels of a vehicle (a domestically produced front-wheel-drive car with a 2000cc engine), and after being inflated to an internal pressure of 250kPa (the standard internal pressure for passenger cars), the vehicle is driven at 60km / h on an icy and snowy test course. Twenty drivers then provide a subjective evaluation of the grip performance during the drive on a 5-point scale (higher numbers indicate better performance). The total score from the evaluations of the 20 drivers is then calculated.

[0187] Next, the results in Comparative Example 4 are set to 100 and indexed based on the following formula to evaluate the grip performance on icy and snowy roads (icy and snowy grip performance). A higher numerical value indicates better ice and snowy grip performance. Ice and snow grip performance = [(Results of test tire) / (Results of comparative example 4)] × 100

[0188] [Table 2]

[0189] [Table 3]

[0190] [Table 4]

[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 Styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less is contained in 40 parts by mass or less 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 or equal to 0.10. the law of nature, Under conditions of temperature 0°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1%, the loss loss tangent (0°C tanδ) measured in the deformation mode: tensile is 0.30 or greater. It is formed from a rubber composition, The thickness T of the tread portion is 10 mm or more and 20 mm or less. the law of nature, Furthermore, the thickness T (mm) of the tread portion and the -30°C tanδ of the cap rubber layer satisfy the following equation. This tire has the following characteristics: -30℃ tanδ / T ≥ 0.022 The present invention (2) is, A tire having a tread section, The cap rubber layer that forms the tread portion Styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less is contained in 40 parts by mass or less per 100 parts by mass of the rubber component. It is formed from a rubber composition in which the loss loss tangent (-30°C tanδ), measured under the conditions of temperature -30°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1%, with deformation mode: tensile, is 0.10 or greater. The thickness T of the tread portion is 10 mm or more and 20 mm or less. Furthermore, the thickness T (mm) of the tread portion and the -30°C tanδ of the cap rubber layer satisfy the following formula: The tread portion is formed from the cap rubber layer and the base rubber layer provided inside the cap rubber layer. The tire is characterized in that the loss tangent (30°C tanδ) of the base rubber layer, measured at a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, a dynamic strain of 1%, and a deformation mode of tension, is greater than the loss tangent (30°C tanδ) of the cap rubber layer, measured in the same manner. -30℃ tanδ / T ≥ 0.022 The present invention (3) is, A tire having a tread section, The cap rubber layer that forms the tread portion Styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less is contained in 40 parts by mass or less per 100 parts by mass of the rubber component. It is formed from a rubber composition in which the loss loss tangent (-30°C tanδ), measured under the conditions of temperature -30°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1%, with deformation mode: tensile, is 0.10 or greater. The thickness T of the tread portion is 10 mm or more and 20 mm or less. Furthermore, the thickness T (mm) of the tread portion and the -30°C tanδ of the cap rubber layer satisfy the following formula: The tread portion is formed from the cap rubber layer and the base rubber layer provided inside the cap rubber layer. The tire is characterized in that the complex modulus of elasticity of the base rubber layer, measured at a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode of elongation, is greater than the complex modulus of elasticity of the cap rubber layer, measured similarly at -30°C. -30℃ tanδ / T ≥ 0.022 The present invention (4) is, A tire having a tread section, The cap rubber layer that forms the tread portion Styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less is contained in 40 parts by mass or less per 100 parts by mass of the rubber component. It is formed from a rubber composition in which the loss loss tangent (-30°C tanδ), measured under the conditions of temperature -30°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1%, with deformation mode: tensile, is 0.50 or greater. The thickness T of the tread portion is 10 mm or more and 20 mm or less. Furthermore, the tire is characterized in that the thickness T (mm) of the tread portion and the -30°C tanδ of the cap rubber layer satisfy the following formula. -30℃ tanδ / T > 0.04

[0193] This invention ( 5 )teeth, The present invention is characterized in that the content of styrene-butadiene rubber (SBR) is 35 parts by mass or less, and (1) Any combination of (4) It is a tire.

[0194] This invention ( 6 )teeth, The aforementioned Cap rubber layer The present invention (1) is characterized in that the tanδ at -30℃ is 0.50 or higher. Any combination of (5)It is a tire.

[0195] This invention ( 7 )teeth, The aforementioned Cap rubber layer The present invention is characterized in that the tanδ at -30℃ is 0.65 or higher. Any combination of (1) through (6) It is a tire.

[0196] This invention ( 8 )teeth, The loss loss tangent (0°C tanδ) measured under the conditions of a temperature of 0°C, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain rate of 1% in the cap rubber layer, with the deformation mode being tensile, is 0.30 or greater, and the present invention (1) to ( 7 This is a tire in any combination of any of the following:

[0197] This invention ( 9 )teeth, Under the conditions of a temperature of 0°C, frequency of 10Hz, initial strain of 5%, and dynamic strain of 1% for the aforementioned cap rubber layer, the loss loss tangent (0°C tanδ) measured in the deformation mode: tensile was, The present invention is characterized by being 0.35 or higher. Any combination of (1) through (8) It is a tire.

[0198] This invention ( 10 )teeth, The aforementioned Cap rubber layer The present invention is characterized in that tanδ at 0℃ is 0.45 or higher. 9 These are the tires listed in the image.

[0199] This invention ( 11 )teeth, The loss loss tangent (30°C tanδ) measured under the conditions of a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain rate of 1% in the cap rubber layer, with the deformation mode being tensile, is 0.20 or less, and is characterized by the present invention (1) to ( 10 This is a tire in any combination of any of the following:

[0200] This invention ( 12 )teeth, The aforementioned Cap rubber layer The present invention is characterized in that the tanδ at 30℃ is 0.13 or less. 11 These are the tires listed in the image.

[0201] This invention (13 ) is characterized in that the thickness T of the tread portion is 12 mm or more and 18 mm or less, and is a tire in any combination with any one of the present invention (1) to ( 12 ).

[0202] The present invention ( 14 ) is the tread department thickness T (mm) and The aforementioned the -30 ℃t tanδ of the cap rubber layer satisfies the following formula, and is a tire in any combination with any one of the present invention (1) to ( 13 ). -30°C tanδ / T > 0.04

[0203] The present invention ( 15 ) is characterized in that the glass transition temperature (Tg) of the cap rubber layer is -40°C or less, and is a tire in any combination with any one of the present invention (1) to ( 14 ).

[0204] The present invention ( 16 ) is characterized in that the tread portion is formed from the cap rubber layer and a base rubber layer provided inside the cap rubber layer, and is a tire in any combination with any one of the present invention (1) to ( 15 ).

[0205] The present invention ( 17 ) is The tread portion is formed from the cap rubber layer and the base rubber layer provided inside the cap rubber layer. characterized in that the thickness of the cap rubber layer is 50% or more with respect to the thickness of the entire tread portion, and is a tire of the present invention Any combination of (1) through (16) . <00​​​​​​The present invention is characterized in that the 30°C tanδ in the base rubber layer is greater than the 30°C tanδ in the cap rubber layer. Any combination of (1) through (17) It is a tire.

[0207] This invention ( 19 )teeth, The tread portion is formed from the cap rubber layer and the base rubber layer provided inside the cap rubber layer. The present invention is characterized in that the complex modulus of elasticity of the base rubber layer, measured at a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, a dynamic strain of 1%, and a deformation mode of elongation, is greater than the complex modulus of elasticity of the cap rubber layer, similarly measured at -30°C. 1 )from( 18 This is a tire in any combination of any of the following:

[0208] This invention ( 20 )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 ( 19 This is a tire in any combination of any of the following:

[0209] This invention ( 21 )teeth, The present invention is characterized in that the acetone extract (AE) in the cap rubber layer is 8% by mass or more, and (1) 20 This is a tire in any combination of any of the following:

[0210] This invention ( 22 )teeth, The present invention is characterized in that the ratio of the amount of styrene in the rubber component (mass%) to the land ratio (%) in the tread portion (amount of styrene in the rubber component / land ratio) is 0.10 or less, and from (1) of the present invention ( 21 This is a tire in any combination of any of the following:

[0211] This invention ( 23 )teeth, The product of the amount of styrene (mass %) in the rubber component and the thickness T (mm) of the tread portion is 120 or less, and the tire is any combination of the inventions (1) to ( 22 ).

Claims

1. A tire having a tread section, The cap rubber layer that forms the tread portion The rubber component contains 40 parts by mass or less of styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less per 100 parts by mass. 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 0.10 or greater. It is formed from a rubber composition in which the loss tangent (0°C tanδ), measured under the conditions of temperature 0°C, frequency 10 Hz, initial strain 5%, and dynamic strain rate 1%, in the deformation mode: tensile, is 0.30 or greater. The thickness T of the tread portion is 10 mm or more and 20 mm or less. Furthermore, the tire is characterized in that the thickness T (mm) of the tread portion and the -30°C tanδ of the cap rubber layer satisfy the following formula. -30℃tanδ / T≧0.022

2. A tire having a tread section, The cap rubber layer that forms the tread portion The rubber component contains 40 parts by mass or less of styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less per 100 parts by mass. It is formed from a rubber composition in which the loss loss tangent (-30°C tanδ), measured under the conditions of temperature -30°C, frequency 10 Hz, initial strain 5%, and dynamic strain rate 1%, in the deformation mode: tensile, is 0.10 or greater. The thickness T of the tread portion is 10 mm or more and 20 mm or less. Furthermore, the thickness T (mm) of the tread portion and the -30°C tanδ of the cap rubber layer satisfy the following formula: The tread portion is formed from the cap rubber layer and the base rubber layer provided inside the cap rubber layer. A tire characterized in that the loss tangent (30°C tanδ) of the base rubber layer, measured at a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, a dynamic strain of 1%, and a deformation mode of tensile, is greater than the loss tangent (30°C tanδ) of the cap rubber layer, measured in the same manner. -30℃tanδ / T≧0.022

3. A tire having a tread section, The cap rubber layer that forms the tread portion The rubber component contains 40 parts by mass or less of styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less per 100 parts by mass. It is formed from a rubber composition in which the loss loss tangent (-30°C tanδ), measured under the conditions of temperature -30°C, frequency 10 Hz, initial strain 5%, and dynamic strain rate 1%, in tensile deformation mode, is 0.10 or greater. The thickness T of the tread portion is 10 mm or more and 20 mm or less. Furthermore, the thickness T (mm) of the tread portion and the -30°C tanδ of the cap rubber layer satisfy the following formula: The tread portion is formed from the cap rubber layer and the base rubber layer provided inside the cap rubber layer. A tire characterized in that the complex modulus of elasticity of the base rubber layer, measured at a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, a dynamic strain of 1%, and a deformation mode of elongation, is greater than the complex modulus of elasticity of the cap rubber layer, similarly measured at -30°C. -30℃tanδ / T≧0.022

4. A tire having a tread section, The cap rubber layer that forms the tread portion The rubber component contains 40 parts by mass or less of styrene-butadiene rubber (SBR) with a styrene content of 25% by mass or less per 100 parts by mass. It is formed from a rubber composition in which the loss loss tangent (-30°C tanδ), measured under the conditions of temperature -30°C, frequency 10 Hz, initial strain 5%, and dynamic strain rate 1%, in tensile deformation mode, is 0.50 or greater. The thickness T of the tread portion is 10 mm or more and 20 mm or less. Furthermore, the tire is characterized in that the thickness T (mm) of the tread portion and the -30°C tanδ of the cap rubber layer satisfy the following formula. -30℃tanδ / T>0.04

5. The tire according to any one of claims 1 to 4, characterized in that the content of styrene-butadiene rubber (SBR) is 35 parts by mass or less.

6. The tire according to any one of claims 1 to 3, characterized in that the -30°C tanδ of the cap rubber layer is 0.50 or more.

7. The tire according to any one of claims 1 to 4, characterized in that the -30°C tanδ of the cap rubber layer is 0.65 or more.

8. The tire according to any one of claims 2 to 4, characterized in that the loss tangent (0°C tanδ) measured in the deformation mode: tensile under the conditions of a temperature of 0°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain of 1% in the cap rubber layer is 0.30 or more.

9. The tire according to any one of claims 1 to 4, characterized in that the loss tangent (0°C tanδ) measured in the deformation mode: tensile under the conditions of a temperature of 0°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain of 1% of the cap rubber layer is 0.35 or more.

10. The tire according to claim 9, characterized in that the tanδ of the cap rubber layer at 0°C is 0.45 or more.

11. The tire according to any one of claims 1 to 4, characterized in that the loss tangent (30°C tanδ) measured in the deformation mode: tensile under the conditions of a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain of 1% in the cap rubber layer is 0.20 or less.

12. The tire according to claim 11, characterized in that the 30°C tanδ of the cap rubber layer is 0.13 or less.

13. The tire according to any one of claims 1 to 4, characterized in that the thickness T of the tread portion is 12 mm or more and 18 mm or less.

14. The tire according to any one of claims 1 to 3, characterized in that the thickness T (mm) of the tread portion and the -30°C tanδ of the cap rubber layer satisfy the following formula. -30℃tan / T>0.04

15. The tire according to any one of claims 1 to 4, characterized in that the glass transition temperature (Tg) of the cap rubber layer is -40°C or lower.

16. The tire according to claim 1 or 4, characterized in that the tread portion is formed from the cap rubber layer and a base rubber layer provided inside the cap rubber layer.

17. The tread portion is formed from the cap rubber layer and the base rubber layer provided inside the cap rubber layer, The tire according to any one of claims 1 to 4, characterized in that the thickness of the cap rubber layer is 50% or more of the total thickness of the tread portion.

18. The tread portion is formed from the cap rubber layer and the base rubber layer provided inside the cap rubber layer, The tire according to any one of claims 1, 3, or 4, characterized in that the 30°C tanδ in the base rubber layer is greater than the 30°C tanδ in the cap rubber layer.

19. The tread portion is formed from the cap rubber layer and the base rubber layer provided inside the cap rubber layer, The tire according to any one of claims 1, 2, or 4, characterized in that the complex modulus of elasticity of the base rubber layer, measured at a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, a dynamic strain of 1%, and a deformation mode of extension, is greater than the complex modulus of elasticity of the cap rubber layer, similarly measured at -30°C.

20. The tire according to any one of claims 1 to 4, 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.

21. The tire according to any one of claims 1 to 4, characterized in that the acetone extract (AE) in the cap rubber layer is 8% by mass or more.

22. The tire according to any one of claims 1 to 4, characterized in that the ratio of the amount of styrene in the rubber component (mass%) to the land ratio (%) in the tread portion (amount of styrene in the rubber component / land ratio) is 0.10 or less.

23. The tire according to any one of claims 1 to 4, characterized in that the product of the amount of styrene (mass%) in the rubber component and the thickness T (mm) of the tread portion is 120 or less.

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