tire

Abstract

To improve the riding comfort performance during high-speed traveling.SOLUTION: In a tire comprising a tread part, a cap rubber layer forming the tread part contains 15 pts.mass to 40 pts.mass of styrene-butadiene rubber (SBR) with the styrene amount of 4 mass% to 25 mass%, in 100 pts.mass of a rubber component, and is formed of a rubber composition in which the loss tangent (0°Ctanδ) is 0.10 or higher when measured at a deformation mode: tension, under the conditions of a temperature of 0°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%. In the tire, a thickness of the tread part is 10 mm to 20 mm, and silica is contained in the rubber composition forming the cap rubber layer. A content of silica in the rubber composition is 90 pts.mass or more relative to the 100 pts.mass rubber component.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Tires are required to have a good ride comfort, and various techniques have been proposed to improve the ride comfort (for example, Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-263175 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-132772 [Patent Document 3] Japanese Patent Application Publication No. 2019-065270 [Patent Document 4] Japanese Patent Publication No. 2021-172248 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the construction of expressways in recent years, opportunities for traveling long distances at high speeds have increased dramatically. In this situation, however, tires manufactured based on the above-mentioned conventional technologies still do not provide sufficient ride comfort performance when traveling at high speeds, and further improvement is strongly desired.

[0005] Therefore, an object of the present invention is to improve ride comfort during high-speed driving. [Means for solving the problem]

[0006] The present invention provides A tire having a tread portion, A cap rubber layer forming the tread portion is Styrene butadiene rubber (SBR) with a styrene content of 4% by mass or more and 25% by mass or less per 100 parts by mass of rubber components 25 Contains not less than 40 parts by mass and not more than 40 parts by mass, The loss tangent (0℃ tanδ) measured under the conditions of temperature 0℃, frequency 10Hz, initial strain 5%, dynamic strain rate 1%, deformation mode: tension is 0.30 The rubber composition is formed from the above rubber composition, The thickness of the tread portion is 10 mm or more and 20 mm or less, The tire is characterized in that the rubber composition forming the cap rubber layer contains silica, and the silica content of the rubber composition is 90 parts by mass or more per 100 parts by mass of the rubber component.

[0008] The present invention also provides A tire having a tread portion, A cap rubber layer forming the tread portion is A styrene butadiene rubber (SBR) having a styrene content of 4% by mass or more and 25% by mass or less is contained in 15 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the rubber component, The rubber composition has a loss tangent (0°C tanδ) of 0.10 or more measured in a tensile deformation mode under the conditions of a temperature of 0°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%; The thickness of the tread portion is 10 mm or more and 20 mm or less, The aspect ratio is 30% or more and 60% or less, This tire is characterized in that the ratio of the silica content (parts by mass) to the aspect ratio (%) per 100 parts by mass of the rubber component [silica content (parts by mass) / aspect ratio (%)] is 1.5 or more. [Effects of the Invention]

[0009] According to the present invention, it is possible to improve ride comfort during high-speed driving. DETAILED DESCRIPTION OF THE INVENTION

[0010] [1] Characteristics of the tire according to the present invention First, the features of the tire according to the present invention will be described.

[0011] 1. Overview The tire according to the present invention is a tire having a tread portion, in which a cap rubber layer forming the tread portion is formed from a rubber composition 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 the rubber component, and having a loss tangent (0°C tanδ) of 0.10 or more measured in a tensile deformation mode under conditions of a temperature of 0°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%, and the thickness of the tread portion is 10 mm or more and 20 mm or less.

[0012] The cap rubber layer referred to here is not limited to the cap rubber layer that forms the outermost layer of the tread portion, and if there are two or more layers within 5 mm from the tread surface toward the inside, at least one of the layers must satisfy the requirements of the rubber composition.

[0013] These features make it possible to improve ride comfort during high-speed driving, as will be described later.

[0014] 2. Mechanism of effect manifestation in the tire according to the present invention The mechanism by which the above-described effects of the tire according to the present invention are exhibited is believed to be as follows.

[0015] As described above, the cap rubber layer of the tire 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 the rubber component.

[0016] Since SBR with a low styrene content, specifically 25% by mass or less, has a low glass transition temperature (Tg), incorporating such low-styrene-content SBR into the rubber component allows an interface to be formed between the styrene portion of the SBR and other polymers. This interface can then absorb and mitigate external (road) impacts received by the tire during high-speed driving.

[0017] At the same time, by incorporating 40 parts by mass or less of SBR with a low styrene content (25% by mass or less), minute styrene domains can be appropriately formed on the rubber surface. These minute styrene domains increase the mobility of the polymer, allowing it to move flexibly, thereby absorbing and mitigating external (road) impacts received by the tire while traveling at high speeds.

[0018] The styrene content is more preferably 20% by mass or less, and even more preferably 15% by mass or less, while the lower limit is preferably 4% by mass or more, more preferably 5% by mass or more, and even more preferably 6% by mass or more.

[0019] In the present 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 the rubber component" means that the amount of SBR per 100 parts by mass of the rubber component is 40 parts by mass or less, and the amount of styrene in the total SBR is 25% by mass or less.

[0020] In other words, when the rubber component contains only one styrene-containing polymer (SBR), it indicates that the styrene content is 25% by mass or less, and when the rubber component contains multiple styrene-containing polymers (SBR), it indicates that the styrene content calculated by summing the product of the styrene content (% by mass) in each polymer and the blending amount (parts by mass) of that polymer per 100 parts by mass of the rubber component is 25% by mass or less.

[0021] More specifically, when 100 parts by mass of the rubber component contains SBR1 (X1 parts by mass) with a styrene content of S1% by mass and SBR2 (X2 parts by mass) with a styrene content of S2% by mass, the styrene content calculated from the formula {(S1×X1)+(S2×X2)} / (X1+X2) is 25% by mass or less.

[0022] In addition, for a rubber composition after vulcanization, the styrene content can also be calculated by determining the amount of styrene contained in the rubber component after acetone extraction using solid-state nuclear magnetic resonance (solid-state NMR) or a Fourier transform infrared spectrophotometer (FTIR).

[0023] In the present invention, the loss tangent (0°C tanδ) of the rubber composition forming the cap rubber layer is further measured in tension under the conditions of a temperature of 0°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%, and is 0.10 or more.

[0024] The loss tangent tanδ is a viscoelastic parameter that indicates the energy absorption performance, and the larger the value, the more energy can be absorbed and converted into heat. In the present invention, the 0°C tanδ is set to a large value of 0.10 or more, so that even during high-speed driving where high-frequency vibrations occur, vibration energy can be sufficiently absorbed, converted into heat, and released. It is more preferable that it is 0.30 or more, and even more preferable that it is 0.40 or more. There is no particular upper limit, but it is preferably 0.85 or less, more preferably 0.80 or less, and even more preferably 0.75 or less.

[0025] The loss tangent tanδ (30°C tanδ) measured in tension under conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1% is preferably 0.30 or less, and more preferably 0.25 or less. By appropriately controlling 30°C tanδ to such a value, the tread portion that deflects upon contact with the road surface during rolling can easily return to its original shape when it leaves the road surface and can easily deflect again when it re-contacts the road, which is thought to improve ride comfort.

[0026] In the above, the loss tangent (tan δ) can be measured using a viscoelasticity measuring device such as "IPLEXER (registered trademark)" manufactured by GABO.

[0027] 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. By controlling the thickness to such an appropriate value, it is believed that the entire tread portion becomes more flexible and deformable, improving ride comfort. It is more preferable that the thickness be 12 mm or more and 18 mm or less, and even more preferable that the thickness be 14 mm or more and 16 mm or less.

[0028] The thickness of the tread portion mentioned above refers to the thickness of the tread portion on the tire equatorial plane in the tire radial cross section. When the tread portion is formed of a single rubber composition, it refers to the thickness of that rubber composition. When the tread portion is formed of a laminated structure of multiple rubber compositions described below, it refers to the total thickness of these layers.

[0029] When the tire has grooves on the equatorial plane, this refers to the thickness from the intersection of the line connecting the radially outermost end points of the grooves with the equatorial plane of the tire to the radially innermost interface of the tread portion.

[0030] The tread portion is a component that forms the contact patch of the tire, and refers to the portion radially outward of components that contain fiber materials such as the carcass, belt layer, belt reinforcing layer, etc. The thickness of the tread portion can be measured by aligning the bead portion with the normal rim width in a cross section cut out in the radial direction of the tire.

[0031] "Genuine rim" refers to the rim specified for each tire in the standard system that includes the standard on which the tire is based. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA Year Book." For ETRTO (The European Tire and Rim Technical Organization), it refers to the "Measuring Rim" listed in the "Standards Manual." For TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "Year Book." JATMA, ETRTO, and TRA are referenced in that order, and if an applicable size is available at the time of reference, that standard is followed. For tires not specified in the standard, it refers to the rim that can be mounted on the rim and can maintain internal pressure, i.e., the rim with the smallest rim diameter and the next narrowest rim width, among rims that do not leak air between the rim and tire.

[0032] As described above, in the tire according to the present invention, the entire rubber in the tread portion is easily flexible, and input from the road surface can be sufficiently absorbed and dissipated as heat even when traveling at high speeds, so it is thought that ride comfort performance when traveling at high speeds can be sufficiently improved.

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

[0034] 1. Glass transition temperature (Tg) of the cap rubber layer In the present invention, the glass transition temperature (Tg) of the cap rubber layer is preferably higher than −40° C. By making the Tg higher than −40° C., it is thought that the tan δ at around 0° C. is likely to become high, further improving the ride comfort performance during high-speed driving.

[0035] The glass transition temperature (Tg) of the rubber composition can be determined from a temperature distribution curve of tan δ measured using a viscoelasticity measuring device such as the "Iplexer (registered trademark)" series manufactured by GABO. Specifically, the temperature distribution curve of tan δ is measured under conditions of a frequency of 10 Hz, an initial strain of 10%, an amplitude of ±0.5%, and a heating rate of 2°C / min. The temperature corresponding to the largest tan δ value in the range of -60°C to 40°C on the measured temperature distribution curve is defined as the glass transition temperature (Tg). If there are two or more points with the largest tan δ value in the range of -60°C to 40°C, the lowest temperature point is defined as Tg. For example, in the present invention, if the maximum value of tan δ is in the range of -60°C to 40°C, the temperature showing the maximum value is defined as the glass transition temperature (Tg) according to the above definition. Furthermore, for example, if a temperature distribution curve is obtained in which tan δ gradually decreases as the temperature increases within a range of -60°C or more and 40°C or less, and the temperature at which tan δ reaches its maximum value is -60°C, then the glass transition temperature (Tg) is -60°C according to the above definition.

[0036] 2. Multi-layered tread In the present invention, the tread portion may be formed of only one layer, a cap rubber layer, or may be formed of two layers by providing a base rubber layer inside the cap rubber layer, or may be formed of three layers, four layers, or more. In this case, the thickness of the cap rubber layer in the entire tread portion is preferably 10% or more. This makes it possible to sufficiently transmit friction generated between the surface of the tread portion and the road surface to the inside of the tire, which is thought to further improve ride comfort during high-speed driving. It is more preferable that the thickness of the cap rubber layer in the entire tread portion be 70% or more.

[0037] As described above, the thickness of the cap rubber layer and the thickness of the base rubber layer can be calculated by adding up the thickness of the cap rubber layer and the thickness of the base rubber layer in the thickness of the tread portion.

[0038] In this case, it is preferable that the 0°C tan δ of the base rubber layer is smaller than the 0°C tan δ of the cap rubber layer, which improves responsiveness to the grip performance generated by the cap rubber layer and can sufficiently improve ride comfort during high-speed driving.

[0039] The 0°C tan δ of the cap rubber layer and base rubber layer can be adjusted appropriately by the amounts and types of compounded materials described below, and can be increased, for example, by increasing the styrene content in the rubber component, increasing the SBR content in the rubber component, increasing the styrene content in the SBR component, increasing the content of fillers such as silica and carbon black, increasing the content of resin components, etc. Conversely, it can be decreased by decreasing the styrene content in the rubber component, decreasing the SBR content in the rubber component, decreasing the styrene content in the SBR component, decreasing the content of fillers such as silica and carbon black, decreasing the content of resin components, etc.

[0040] In the case of a multi-layered tread portion, the complex modulus of the base rubber layer measured at a temperature of 0°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode of extension is preferably smaller than the complex modulus of the cap rubber layer measured in the same manner. These complex moduli can be measured using a viscoelasticity measuring device such as the "IPLEXER (registered trademark)" manufactured by GABO.

[0041] The complex modulus is a parameter that indicates the rigidity of the rubber layer. By making the complex modulus of the base rubber layer smaller than the complex modulus of the cap rubber layer, the entire tread portion deforms from the inside during driving, allowing the road surface and the tread surface to make almost uniform contact with each other, thereby improving ground contact and significantly improving ride comfort during high-speed driving.

[0042] 3. Silica content in the cap rubber layer In the present invention, the rubber composition forming the cap rubber layer preferably contains silica, which facilitates friction between the flexibly moving minute styrene domains and the silica, further increasing heat buildup and allowing vibration energy to escape, thereby sufficiently improving ride comfort during high-speed driving.

[0043] The specific content is preferably 90 parts by mass or more, more preferably 100 parts by mass or more, and even more preferably 110 parts by mass or more, per 100 parts by mass of the rubber component. There is no particular upper limit, but in consideration of the kneading processability and molding processability of the rubber composition, the content is preferably 140 parts by mass or less, more preferably 130 parts by mass or less, and even more preferably 120 parts by mass or less.

[0044] In the present invention, the particle size (average primary particle size) of silica is preferably 17 nm or less, taking into consideration ease of friction with the polymer.

[0045] The average primary particle diameter can be calculated by directly observing silica particles extracted from a rubber composition cut out from a tire using a transmission electron microscope (TEM) or the like, calculating the equivalent cross-sectional area diameter from the area of ​​each silica particle obtained, and determining the average value.

[0046] 4. Resin component content in the cap rubber layer In the present invention, the rubber composition forming the cap rubber layer preferably contains a resin component.

[0047] By including a resin component in the rubber composition, the adhesion to the road surface is improved due to the adhesiveness of the resin component, and ride comfort during high-speed driving can be sufficiently improved.

[0048] Preferable 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, and among these, styrene resins such as α-methylstyrene are more preferable.The content 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.

[0049] 5. Acetone extractables (AE) of the cap rubber layer In the present invention, the acetone extractables (AE) of the cap rubber layer is preferably 11% by mass or more, more preferably 12% by mass or more, and even more preferably 13% by mass or more. On the other hand, although there is no particular upper limit, it is preferably 17% by mass or less, more preferably 14% by mass or less, and even more preferably 15% by mass or less.

[0050] The acetone extractables (AE) can be considered as an index showing the amount of softeners in a rubber composition, and can also be considered as an index showing the softness of the rubber composition. Therefore, when the amount of AE is increased to a certain extent as described above in the cap rubber layer, the area in contact with the road surface of the tire is sufficiently secured, improving ground contact and sufficiently improving ride comfort during high-speed driving.

[0051] The acetone extractables (AE) can be measured in accordance with JIS K 6229: 2015. Specifically, the AE (mass%) can be obtained by immersing a vulcanized rubber test piece cut out from the measurement site in acetone for a predetermined time and determining the mass loss rate (%) of the test piece.

[0052] More specifically, each vulcanized rubber test piece is immersed in acetone at room temperature and normal pressure for 72 hours to extract the soluble components, and the mass of each test piece is measured before and after extraction, and the mass can be calculated using the following formula. Acetone extractable amount (%) = (mass of rubber test piece before extraction - mass of rubber test piece after extraction) / (mass of rubber test piece before extraction)}×100

[0053] The acetone extractable content can be appropriately changed by changing the compounding ratio of the plasticizer in the rubber composition.

[0054] 6. Land Ratio In the tire according to the present invention, the land ratio in the tread portion of the tire mounted on a regular rim and pressurized to a regular internal pressure is preferably 55% or more, more preferably 60% or more, and even more preferably 63% or more.

[0055] The "land ratio" is the ratio of the actual contact area to the virtual contact area where all the grooves on the surface of the tread are filled. A larger land ratio increases the area in contact with the road surface, improving ground contact and significantly improving ride comfort at high speeds.

[0056] The upper limit of the land ratio is not particularly limited, but is preferably 85% or less, more preferably 80% or less, and even more preferably 75% or less.

[0057] The above-mentioned land ratio can be determined from the ground contact shape under normal rim, normal internal pressure, and normal load conditions.

[0058] Specifically, a tire is mounted on a standard rim, pressurized to the standard internal pressure, and left to stand at 25°C for 24 hours. Then, ink is applied to the tire tread surface, and the standard load is applied and pressed onto cardboard (camber angle 0°). The contact shape can be obtained by transferring the tire to paper, and the tire is rotated 72° in circumferential directions, transferring the shape to five locations. In other words, five contact shapes are obtained. At this point, the five contact shapes are smoothly connected, with the grooves in the contact shape contours being smoothly joined, and the resulting shape is called the virtual contact surface.

[0059] The land ratio can be calculated by (average area of ​​five contact shapes (black parts) transferred to cardboard / average area of ​​virtual contact surface obtained from five contact shapes) x 100 (%).

[0060] "Normal internal pressure" refers to the air pressure specified for each tire by the standard. For JATMA, it refers to the maximum air pressure, for ETRTO, it refers to the "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 "normal rims," ​​JATMA, ETRTO, and TRA are referenced in that order, and the standards are followed. For tires not specified in the standard, it refers to the normal internal pressure (250 KPa or higher) of another tire size (specified in the standard) that is specified with the normal rim as the standard rim. Note that if multiple normal internal pressures of 250 KPa or higher are listed, it refers to the smallest value among them.

[0061] Furthermore, "normal load" refers to the load determined for each tire by each standard in the standard system, including the standard on which the tire is based, and refers to the maximum mass that can be loaded on the tire. In the case of JATMA, it refers to the maximum load capacity, in the case of ETRTO, it refers to the "LOAD CAPACITY", and in the case of TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". As with the above-mentioned "normal rim" and "normal internal pressure", JATMA, ETRTO, and TRA are referenced in that order and their standards are followed. In the case of tires not specified in the standard, the normal load W is calculated as follows: L Ask for. V={(Dt / 2) 2 -(Dt / 2-Ht) 2}×π×Wt W L =0.000011×V+175 W L :Normal load (kg) V: Virtual volume of the tire (mm 3 ) Dt: Tire outer diameter Dt (mm) Ht: tire section height (mm) Wt: tire cross-sectional width (mm)

[0062] In this case, if the ratio of the content (parts by mass) of styrene butadiene rubber (SBR) with a styrene content of 25% by mass or less per 100 parts by mass of the rubber component to the land ratio (%) in the tread portion (SBR content (parts by mass) with a styrene content of 25% by mass or less / land ratio (%)) is 0.7 or less, the effect of the network of styrene domains works together to further improve ride comfort during high-speed driving. A value of 0.6 or less is more preferable. There is no particular lower limit, but a value of 0.3 or more is preferable, and a value of 0.4 or more is more preferable.

[0063] 7. Flatness The aspect ratio is the tire's cross-sectional height relative to its cross-sectional width, and the smaller this ratio is, the better the tire's contact with the road surface and the more comfortable it can be when driving at high speeds. On the other hand, a low aspect ratio reduces the amount of deflection at the side, which can lead to a deterioration in ride comfort.

[0064] Considering these points, it is preferable that the specific aspect ratio of the tire according to the present invention is 30% or more and 60% or less.

[0065] The above aspect ratio (%) can be calculated using the following formula using the tire cross-sectional height Ht (mm), cross-sectional width Wt (mm), tire outer diameter Dt (mm), and rim diameter R (mm) when the internal pressure is set to 250 kPa. Oblateness (%)=(Ht / Wt)×100(%) Ht=(Dt-R) / 2

[0066] In this case, when the ratio of the silica content (parts by mass) to the aspect ratio (%) per 100 parts by mass of the rubber component (silica content (parts by mass) / aspect ratio (%)) is 1.5 or more, the effect of the silica network works together to further improve ride comfort during high-speed driving. 1.7 or more is more preferable. There is no particular upper limit, but it is preferably 2.2 or less, and more preferably 2.1 or less.

[0067] [3] Implementation form The present invention will be specifically described below based on embodiments.

[0068] 1. Rubber composition In the tire according to the present invention, the rubber composition forming the cap rubber layer can be obtained by appropriately adjusting the types and amounts of various compounding materials such as the rubber component, filler, softener, vulcanizing agent, and vulcanization accelerator described below.

[0069] (1) Compounding materials (a) Rubber component The rubber component is not particularly limited, and rubbers (polymers) commonly used in tire production can be used, such as isoprene-based rubber, diene-based rubbers such as butadiene rubber (BR), styrene-butadiene rubber (SBR), and nitrile rubber (NBR), butyl-based rubbers such as butyl rubber, and thermoplastic elastomers such as styrene-butadiene-styrene block copolymer (SBS) and styrene-butadiene block copolymer (SB).

[0070] In the present invention, among these, from the viewpoint of including styrene in the rubber component, it is preferable to include any one of styrene-based polymers such as SBR, SBS, and SB, and to include SBR. Furthermore, these styrene-based polymers may be used in combination with other rubber components, and for example, a combination of SBR and BR, or a combination of SBR, BR, and isoprene-based rubber is preferred.

[0071] (a) SBR The weight-average molecular weight of the SBR is, for example, more than 100,000 and less than 2,000,000. As described above, in the present invention, the styrene content in the SBR component is 25% by mass or less. The vinyl content (1,2-bonded butadiene content) of the SBR is, for example, more than 5% by mass and less than 70% by mass. The vinyl content of the SBR refers to the 1,2-bonded butadiene content relative to the total butadiene moieties in the SBR component. The structure of the SBR (measurement of the styrene content and vinyl content) can be identified using, for example, a JNM-ECA series instrument manufactured by JEOL Ltd.

[0072] In the present invention, the content of SBR in 100 parts by mass of the rubber component is 40 parts by mass or less, as described above, more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less, while 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.

[0073] The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR). The SBR may be either unmodified or modified. Hydrogenated SBR, which is obtained by hydrogenating the butadiene portion of SBR, may also be used. Hydrogenated SBR may be obtained by subsequently hydrogenating the BR portion of SBR, or a similar structure may be obtained by copolymerizing styrene, ethylene, and butadiene.

[0074] The modified SBR may be any SBR having a functional group that interacts with a filler such as silica, and examples thereof include terminal-modified SBR in which at least one terminal of the SBR has been modified with a compound (modifier) ​​having the above functional group (terminal-modified SBR having the above functional group at the terminal), main-chain-modified SBR in which the main chain has the above functional group, main-chain terminal-modified SBR in which the main chain and terminals have the above functional group (for example, main-chain terminal-modified SBR in which the main chain has the above functional group and at least one terminal has been modified with the above modifier), and terminal-modified SBR in which the SBR has been modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and in which a hydroxyl group or epoxy group has been introduced.

[0075] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, etc. These functional groups may have a substituent.

[0076] Furthermore, as the modified SBR, for example, SBR modified with a compound (modifying agent) represented by the following formula can be used.

[0077] [ka]

[0078] In the formula, R 1 , R 2 and R 3 R may be the same or different and represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or a derivative thereof. 4 and R 5 are the same or different and represent a hydrogen atom or an alkyl group. 4 and R 5 may bond to form a ring structure together with the nitrogen atom, and n represents an integer.

[0079] As the modified SBR modified with a compound (modifier) ​​represented by the above formula, SBR in which the polymerization terminals (active terminals) of solution-polymerized styrene-butadiene rubber (S-SBR) have been modified with a compound represented by the above formula (such as the modified SBR described in JP 2010-111753 A).

[0080] R 1 , R 2 and R 3R is preferably an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). 4 and R 5 is preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. In addition, R 4 and R 5 When the groups bond to form a ring structure together with the nitrogen atom, the ring is preferably a 4- to 8-membered ring. The alkoxy group also includes a cycloalkoxy group (such as a cyclohexyloxy group) and an aryloxy group (such as a phenoxy group or a benzyloxy group).

[0081] Specific examples of the modifying agent include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. These may be used alone or in combination of two or more.

[0082] Modified SBR may also be modified with the following compounds (modifiers): Examples of the modifier include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups, such as diglycidylated bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline; Diglycidyl amino compounds such as diglycidyl orthotoluidine, tetraglycidyl meta-xylenediamine, tetraglycidyl aminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidyl aminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamic acid chloride, and N,N-diethylcarbamic acid chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane;(Trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(trippropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxy sulfide group-containing silane compounds such as (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, Alkoxysilanes such as thyltriethoxysilane; (thio)benzophenone compounds having an amino group and / or a substituted amino group such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, and N,N,N',N'-bis-(tetraethylamino)benzophenone; 4-N,N- Benzaldehyde compounds having an amino group and / or a substituted amino group, such as dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone; and N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, and N-phenyl-2-piperidone;N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurylolactam, N-vinyl-ω-laurylolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam; as well as N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), and tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-trione , N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophen, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone, etc. Modification with the above compounds (modifiers) can be carried out by known methods.

[0083] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used. The SBR may be used alone or in combination of two or more types.

[0084] (b)BR In the present invention, the rubber composition may contain BR. In this case, the amount of BR per 100 parts by mass of the rubber component is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and is preferably 30 parts by mass or less, more preferably 25 parts by mass or less.

[0085] The weight-average molecular weight of the BR is, for example, more than 100,000 and less than 2,000,000. The vinyl content of the BR is, for example, more than 1% by mass and less than 30% by mass. The cis content of the BR is, for example, more than 1% by mass and less than 98% by mass. The trans content of the BR is, for example, more than 1% by mass and less than 60% by mass.

[0086] The BR is not particularly limited, and can be a BR with a high cis content (cis content of 90% or more), a BR with a low cis content, or a BR containing syndiotactic polybutadiene crystals. The BR can be either unmodified or modified, and examples of modified BR include modified BRs into which the above-mentioned functional groups have been introduced. These can be used alone or in combination of two or more. The cis content can be measured by infrared absorption spectroscopy.

[0087] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0088] (c) Isoprene rubber In the present invention, the rubber composition may contain an isoprene-based rubber. In this case, the content of the isoprene-based rubber per 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and is preferably 70 parts by mass or less, more preferably less than 60 parts by mass.

[0089] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR.

[0090] Examples of NR that can be used include those commonly used in the tire industry, such as SIR20, RSS#3, TSR20, and SVR-L. Examples of IR are not particularly limited, and examples of IR that can be used include those commonly used in the tire industry, such as IR2200. Examples of modified NR include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

[0091] (d) Other rubber components Furthermore, other rubber components may include rubbers (polymers) that are generally used in the manufacture of tires, such as nitrile rubber (NBR).

[0092] (b) Compounding materials other than rubber components (a) Filler In the present embodiment, the rubber composition preferably contains a filler. Specific examples of the filler include silica, carbon black, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica.

[0093] (i-1) Silica In the present invention, the rubber composition preferably contains silica, and preferably contains a silane coupling agent together with silica.

[0094] The BET specific surface area of ​​silica is 140m from the viewpoint of obtaining good durability. 2 / g or more is preferable, and 160m 2 On the other hand, from the viewpoint of obtaining good rolling resistance during high-speed running, a value of 250m 2 / g or less is preferable, and 220m 2 / g or less. The BET specific surface area is the N2SA value measured by the BET method in accordance with ASTM D3037-93.

[0095] In the present invention, as described above, it is preferable to use silica having a particle size of 17 nm or less in the rubber composition forming 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 increasing the mobility of the polymer, thereby improving ride comfort. Although the lower limit is not particularly limited, it is preferable that it be 10 nm or more from the viewpoint of dispersibility during mixing.

[0096] When silica is used as a filler reinforcing agent, the content is, as described above, preferably 90 parts by mass or more, more preferably more than 100 parts by mass, and even more preferably 110 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is not particularly limited, but is preferably 140 parts by mass or less, more preferably 130 parts by mass or less, and even more preferably 120 parts by mass or less.

[0097] Examples of silica include dry process silica (anhydrous silica) and wet process silica (hydrated silica). Among them, wet process silica is preferred because it has a large number of silanol groups. Silica made from hydrous glass or silica made from biomass materials such as rice husks may also be used.

[0098] As silica, for example, products from Evonik Industries, Rhodia, Tosoh Silica Corporation, Solvay Japan, Tokuyama Corporation, etc. can be used.

[0099] (i-2) Silane coupling agent When silica is used as the reinforcing filler, the rubber composition preferably contains a silane coupling agent together with silica. The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocathanide, Examples of such compounds include sulfide-based compounds such as rubamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These compounds may be used alone or in combination of two or more.

[0100] As the silane coupling agent, for example, products from Evonik Industries, Momentive, Shin-Etsu Silicones Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Dow Corning Toray Co., Ltd., etc. can be used.

[0101] The content of the silane coupling agent is, for example, more than 3 parts by mass and less than 25 parts by mass relative to 100 parts by mass of silica.

[0102] (ii) Carbon black In the present invention, the rubber composition preferably contains carbon black from the viewpoint of reinforcement.

[0103] The specific content ratio of carbon black per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less.

[0104] The carbon black is not particularly limited, and examples thereof include furnace blacks (furnace carbon blacks) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black (acetylene carbon black); thermal blacks (thermal carbon blacks) such as FT and MT; and channel blacks (channel carbon blacks) such as EPC, MPC, and CC. These may be used alone or in combination of two or more.

[0105] The specific surface area of ​​carbon black CTAB (Cetyl Tri-methyl Ammonium Bromide) is 130m 2 / g or more is preferable, and 160m 2 / g or more is more preferable, and 170m 2 / g or more is more preferable. 2 / g or less is preferable, and 200m 2 / g or less is more preferable. The CTAB specific surface area is a value measured in accordance with ASTM D3765-92.

[0106] Specific carbon blacks are not particularly limited, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available carbon blacks include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These may be used alone or in combination of two or more.

[0107] (iii) Other fillers In addition to the silica and carbon black described above, the rubber composition may further contain, as necessary, fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc. The content of these fillers is, for example, more than 0.1 part by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0108] (b) Plasticizer component The rubber composition may contain plasticizer components, such as oil (including extender oil), liquid rubber, and resin, which soften the rubber. The plasticizer component is a component that can be extracted from vulcanized rubber with acetone. The total content of the plasticizer components is preferably 25 parts by mass or more, and more preferably 40 parts by mass or more, per 100 parts by mass of the rubber component. On the other hand, it is preferably 50 parts by mass or less, and more preferably 45 parts by mass or less. When oil-extended rubber is used as the rubber component, the amount of oil-extended oil is also included in the oil content.

[0109] (i) Oil Examples of oils include mineral oils (commonly referred to as process oils), vegetable oils, and mixtures thereof. Examples of mineral oils (process oils) that can be used include paraffin-based process oils, 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 bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These oils may be used alone or in combination. From the perspective of life cycle assessment, waste oils used as lubricants in rubber mixers and automobile engines, as well as waste edible oils, may also be used as appropriate.

[0110] Specific examples of process oils (mineral oils) that can be used include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Corporation, H&R Corporation, Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and the like.

[0111] (ii) Liquid rubber The liquid rubber mentioned as a plasticizer is a polymer that is in a liquid state at room temperature (25°C) and is a rubber component that can be extracted by acetone from a vulcanized tire. Examples of liquid rubber include farnesene polymers, liquid diene polymers, and hydrogenated products thereof.

[0112] Farnesene polymers are polymers obtained by polymerizing farnesene, which has structural units based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene).

[0113] The farnesene-based polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

[0114] 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).

[0115] The liquid diene polymer has a weight average molecular weight (Mw) of, for example, 1.0 × 10 in terms of polystyrene measured by gel permeation chromatography (GPC). 3 Super, 2.0×10 5 In this specification, the Mw of the liquid diene polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0116] The amount of the liquid rubber (total amount of the liquid farnesene polymer, liquid diene polymer, etc.) is, for example, more than 1 part by mass and less than 100 parts by mass per 100 parts by mass of the rubber component.

[0117] As the liquid rubber, for example, products of Kuraray Co., Ltd., Cray Valley Co., Ltd., etc. can be used.

[0118] (iii) Resin component The resin component also functions as a tackifier and may be solid or liquid at room temperature. Specific examples of the resin component include rosin-based resins, styrene-based resins, coumarone-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, and two or more types may be used in combination. The content of the resin component is preferably more than 2 parts by mass and less than 45 parts by mass, more preferably less than 30 parts by mass, per 100 parts by mass of the rubber component. These resin components may be provided with a modifying group capable of reacting with silica, etc., as needed.

[0119] Rosin-based resins are resins whose main component is rosin acid, which is obtained by processing pine resin. These rosin-based resins (rosins) can be classified based on whether they are modified or not, and can be divided into unmodified rosin (unmodified rosin) and modified rosin (rosin derivatives). Examples of unmodified rosins include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. Modified rosin is a modification of unmodified rosin, and examples include rosin esters, unsaturated carboxylic acid-modified rosin esters, unsaturated carboxylic acid-modified rosin esters, rosin amide compounds, and rosin amine salts.

[0120] Styrenic resins are polymers that use styrene monomers as constituent monomers, and examples thereof include polymers obtained by polymerizing styrene monomers as the main component (50% by mass or more).Specific examples include homopolymers obtained by polymerizing styrene monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) individually, copolymers obtained by copolymerizing two or more styrene monomers, and copolymers of styrene monomers and other monomers that can be copolymerized with them.

[0121] Examples of the other monomers include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene and butadiene isoprene, olefins such as 1-butene and 1-pentene, α,β-unsaturated carboxylic acids such as maleic anhydride or acid anhydrides thereof, and the like.

[0122] Among the coumarone resins, coumarone-indene resins are preferred. Coumarone-indene resins are resins containing coumarone and indene as monomer components that constitute the resin skeleton (main chain). Monomer components contained in the skeleton other than coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0123] The amount of the coumarone-indene resin per 100 parts by mass of the rubber component is, for example, more than 1.0 part by mass and less than 50.0 parts by mass.

[0124] The hydroxyl value (OH value) of the coumarone-indene resin is, for example, more than 15 mgKOH / g and less than 150 mgKOH / g. The OH value is the amount of potassium hydroxide, expressed in milligrams, required to neutralize acetic acid bonded to hydroxyl groups when acetylating 1 g of the resin, and is a value measured by potentiometric titration (JIS K 0070:1992).

[0125] The softening point of the coumarone-indene resin is, for example, more than 30° C. and less than 160° C. The softening point is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point tester.

[0126] Terpene resins include polyterpenes, terpene phenols, and aromatic modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenated products. Terpene compounds are (C5H8) n The hydrocarbons and their oxygen-containing derivatives are represented by the following composition: monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0127] Examples of polyterpenes include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin, which are made from the above-mentioned terpene compounds, as well as hydrogenated terpene resins obtained by hydrogenating the terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the above-mentioned terpene compounds with phenolic compounds, and resins obtained by hydrogenating the above-mentioned resins. Specific examples include resins obtained by condensing the above-mentioned terpene compounds, phenolic compounds, and formalin. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Examples of aromatic-modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the above-mentioned resins. The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring, and examples thereof include phenolic compounds such as phenol, alkylphenol, alkoxyphenol, and unsaturated hydrocarbon group-containing phenol; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and unsaturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; coumarone, indene, and the like.

[0128] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions having 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferably used as a C5 petroleum resin.

[0129] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a hydrogenated or modified version. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of suitable aromatic vinyl resins include coumarone-indene resins, coumarone resins, indene resins, and aromatic vinyl resins. Preferred aromatic vinyl resins are homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene, with copolymers of α-methylstyrene and styrene being more preferred, due to their economical efficiency, ease of processing, and excellent heat generation properties. Examples of aromatic vinyl resins that can be used include those commercially available from Kraton, Eastman Chemical Company, and the like.

[0130] "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified resin. Examples of C5 fractions and C9 fractions include the petroleum fractions mentioned above. As the C5C9 resin, for example, commercially available products from Tosoh Corporation, LUHUA, etc. can be used.

[0131] The acrylic resin is not particularly limited, but for example, a solventless acrylic resin can be used.

[0132] Examples of solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized by high-temperature continuous polymerization (high-temperature continuous bulk polymerization) (methods described in U.S. Pat. No. 4,414,370, JP-A Nos. 59-6207, JP-B Nos. 5-58005, 1-313522, U.S. Pat. No. 5,010,166, and Toa Gosei Kenkyusho Annual Report TREND 2000, Vol. 3, pp. 42-45, etc.), with minimal use of secondary raw materials such as polymerization initiators, chain transfer agents, and organic solvents. In the present invention, (meth)acrylic refers to both methacrylic and acrylic.

[0133] Examples of the monomer components constituting the acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylic acid derivatives such as (meth)acrylamide derivatives.

[0134] Furthermore, aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene may be used together with (meth)acrylic acid or a (meth)acrylic acid derivative as a monomer component constituting the acrylic resin.

[0135] The acrylic resin may be a resin composed solely of a (meth)acrylic component, or a resin containing components other than a (meth)acrylic component, and may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

[0136] As the resin component, for example, products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Co., Ltd., etc. can be used.

[0137] (c) Stearic acid In the present invention, the rubber composition preferably contains stearic acid. The content of stearic acid is, for example, more than 0.5 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component. As the stearic acid, conventionally known stearic acids can be used, such as products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc.

[0138] (d) Antiaging agents In the present invention, the rubber composition preferably contains an antioxidant. The content of the antioxidant is, for example, more than 0.5 parts by mass and less than 10 parts by mass, and more preferably 1 part by mass or more, per 100 parts by mass of the rubber component.

[0139] Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine. Examples of antioxidants include p-phenylenediamine antioxidants such as quinolone; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. These antioxidants may be used alone or in combination of two or more.

[0140] As the antioxidant, for example, products available from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, etc. can be used.

[0141] (E) Wax In the present invention, the rubber composition preferably contains wax. The content of the wax per 100 parts by mass of the rubber component is, for example, 0.5 to 20 parts by mass, preferably 1.0 to 15 parts by mass, and more preferably 1.5 to 10 parts by mass.

[0142] The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as vegetable wax and animal wax; and synthetic waxes such as polymers of ethylene, propylene, etc. These may be used alone or in combination of two or more.

[0143] As the wax, for example, products from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used.

[0144] (f) Zinc oxide The rubber composition may contain zinc oxide. The content of zinc oxide is, for example, more than 0.5 parts by mass and less than 10 parts by mass per 100 parts by mass of the rubber component. As the zinc oxide, a conventionally known product can be used, such as products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc.

[0145] (g) Crosslinking agents and vulcanization accelerators The rubber composition preferably contains a crosslinking agent such as sulfur, etc. The content of the crosslinking agent is, for example, more than 0.1 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0146] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. These may be used alone or in combination of two or more.

[0147] As sulfur, for example, products from Tsurumi Chemical Industry Co., Ltd., Karuizawa Iso Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0148] Examples of crosslinking agents other than sulfur include vulcanizing agents containing sulfur atoms, such as Tackirol V200 manufactured by Taoka Chemical Co., Ltd. and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by Lanxess, and organic peroxides, such as dicumyl peroxide.

[0149] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator is, for example, more than 0.3 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0150] Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more.

[0151] (H) Other In addition to the above components, the rubber composition may further contain, as necessary, additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, organic peroxides, reversion (reversion) inhibitors, etc. The content of these additives is, for example, more than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0152] (2) Preparation of rubber composition The rubber composition that forms the cap rubber layer is prepared by appropriately adjusting the various compounding materials described above and using a general method, for example, a manufacturing method including a base kneading step in which the rubber component is kneaded with a filler such as carbon black, and a finish kneading step in which the kneaded product obtained in the base kneading step is kneaded with a crosslinking agent.

[0153] The kneading can be carried out using a known (internal) kneading machine such as a Banbury mixer, a kneader, or an open roll.

[0154] The kneading temperature in the base kneading step is, for example, higher than 50° C. and lower than 200° C., and the kneading time is, for example, higher than 30 seconds and lower than 30 minutes. In the base kneading step, in addition to the above components, compounding agents conventionally used in the rubber industry, for example, softeners such as oil, zinc oxide, antioxidants, waxes, vulcanization accelerators, etc., may be appropriately added and kneaded as needed.

[0155] In the final kneading step, the kneaded product obtained in the base kneading step is kneaded with a crosslinking agent. The kneading temperature in the final kneading step is, for example, higher than room temperature and lower than 80°C, and the kneading time is, for example, longer than 1 minute and shorter than 15 minutes. In the final kneading step, in addition to the above components, a vulcanization accelerator, zinc oxide, etc. may be appropriately added and kneaded as necessary.

[0156] 2. Tire manufacturing The tire according to the present invention can be produced as an unvulcanized tire by molding the rubber composition obtained above into a tread rubber of a predetermined shape as a cap rubber layer, and then molding it together with other tire components in a tire building machine by a conventional method.

[0157] When the tread portion has a multi-layer structure with a base rubber layer, the rubber composition for forming the base rubber layer can be basically obtained by similarly kneading the above-mentioned rubber components and compounding materials, appropriately changing the compounding amounts thereof, and extruding the base rubber composition together with the cap rubber layer to form a tread rubber of a predetermined shape, and then molding the tread rubber together with other tire components in a tire building machine using a normal method to produce an unvulcanized tire.

[0158] Specifically, an inner liner as a component for ensuring the airtightness of the tire, a carcass as a component for withstanding the load, impact, and inflation pressure to which the tire is subjected, and a belt component as a component for tightly fastening the carcass and increasing the rigidity of the tread are wound around a forming drum, and both ends of the carcass are fixed to both side edges, and bead portions as components for fixing the tire to the rim are arranged. After forming into a toroidal shape, a tread is attached to the center of the outer periphery and sidewalls are attached to the radially outer sides to form side portions, thereby producing an unvulcanized tire.

[0159] The unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire. The vulcanization process can be carried out by using a known vulcanization method. The vulcanization temperature is, for example, greater than 120°C and less than 200°C, and the vulcanization time is, for example, greater than 5 minutes and less than 15 minutes.

[0160] As mentioned above, the resulting tire has a tread rubber that is flexible throughout, and is able to sufficiently absorb input from the road surface and release it as heat even when traveling at high speeds, thereby significantly improving ride comfort when traveling at high speeds.

[0161] The tire according to the present invention can be suitably used as a passenger car tire, a large passenger car tire, a large SUV tire, a truck / bus tire, a motorcycle tire, a racing tire, a studless tire (winter tire), an all-season tire, a run-flat tire, an aircraft tire, a mining tire, a non-pneumatic tire, etc., and is particularly preferably used as a passenger car tire. Also, it is preferably used as a pneumatic tire. [Example]

[0162] Below, examples (working examples) that are considered preferable for carrying out the present invention are shown, but the scope of the present invention is not limited to these working examples. In the working examples, pneumatic tires (tire size 205 / 55R16, aspect ratio: 55%, land ratio: 65%) manufactured from compositions obtained by varying the formulation according to each table using the various chemicals shown below were examined, and the results calculated based on the following evaluation methods are shown in Tables 2 and 3.

[0163] 1. Rubber composition for forming the cap rubber layer (1) Compounding materials (a) Rubber component (i) NR:SVR-L (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) (c) SBR-2: HPR840 (S-SBR) manufactured by JSR Corporation (styrene content: 10% by mass, vinyl content: 42% by mass) (d) SBR-3: HPR850 (modified S-SBR) manufactured by JSR Corporation (styrene content: 27.5% by mass, vinyl content: 59.0% by mass) (E) BR: Ubepol BR150B (High-Sys BR) from Ube Industries, Ltd. (cis content 97% by mass, trans content 2% by mass, vinyl content 1% by mass)

[0164] (Production of SBR-1) The SBR-1 described above is prepared according to the following procedure. First, two 10 L reactors, each consisting of a 10 L inlet at the bottom, an outlet at the top, and a jacket equipped with a stirrer, are connected in series. Butadiene, styrene, and cyclohexane are mixed in the specified ratios. This mixture is passed through a dehydration column packed with activated alumina and mixed with n-butyllithium in a static mixer to remove impurities. The mixture is then continuously fed into the bottom of the first reactor. 2,2-bis(2-oxolanyl)propane as a polar substance and n-butyllithium as a polymerization initiator are continuously fed into the bottom of the first reactor at specified rates, while the reactor temperature is maintained at 95°C. The polymer solution is continuously withdrawn from the top of the reactor and fed into the second reactor. The temperature of the second reactor is maintained at 95°C, and a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane (monomer) as a modifier and oligomer components is continuously added at a predetermined rate as a 1000-fold diluted solution of cyclohexane to carry out the modification reaction. This polymer solution is continuously withdrawn from the reactor, and after continuous addition of an antioxidant using a static mixer, the solvent is removed to obtain the desired modified diene polymer (SBR-1).

[0165] The vinyl content of the SBR (unit: mass%) was determined by infrared spectroscopy at 910 cm, which is the absorption peak of the vinyl group. -1 The amount of styrene (unit: mass %) was determined from the refractive index in accordance with JIS K6383 (1995).

[0166] (b) Compounding materials other than rubber components (a) Carbon black: Diablack 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) (c) Silane coupling agent: Si266 manufactured by Evonik Industries (Bis(3-triethoxysilylpropyl)disulfide) (d) Resin: SYLVATRAXX 4401 manufactured by Arizona Chemical Company (α-methylstyrene resin) (E) Oil: H&R Vivatec 500 (Aromatic process oil: TDAE oil) (f) Zinc oxide: Zinc oxide type 2 manufactured by Mitsui Mining & Smelting Co., Ltd. (g) Anti-aging agent: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd. (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) (H) Stearic acid: Beaded stearic acid "Tsubaki" manufactured by NOF Corporation (i) Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. (J) Sulfur: Powdered sulfur (containing 5% oil) manufactured by Tsurumi Chemical Industry Co., Ltd. (k) Vulcanization accelerator: Noccela CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-cyclohexyl-2-benzothiazylsulfenamide (CBS))

[0167] (2) Rubber composition forming the cap rubber layer According to the formulations shown in Tables 2 and 3, materials other than sulfur and vulcanization accelerator are kneaded for 5 minutes at 150°C using a Banbury mixer to obtain a kneaded mixture. The amounts of each compound are in parts by mass.

[0168] Next, sulfur and a vulcanization accelerator are added to the kneaded mixture, and the mixture is kneaded for 5 minutes at 80°C using an open roll to obtain a rubber composition for forming the cap rubber layer.

[0169] 2. Rubber composition forming the base rubber layer In parallel, a rubber composition for forming the base rubber layer is obtained based on the formulation shown in Table 1 in the same manner as the rubber composition for forming the cap rubber layer.

[0170] [Table 1]

[0171] 3. Manufacturing of pneumatic tires Each rubber composition is extruded into a predetermined shape with a total thickness shown in Tables 2 and 3, with (thickness of cap rubber layer / thickness of base rubber layer)=90 / 10, to produce a tread portion.

[0172] Thereafter, the unvulcanized tire is formed by laminating it together with other tire components, and is press-vulcanized for 10 minutes under a condition of 170°C to produce the pneumatic tires (test tires) of Examples 1 to 6 shown in Table 2 and the pneumatic tires (test tires) of Comparative Examples 1 to 6 shown in Table 3.

[0173] 4. Calculation of parameters The following parameters are then determined for each test tire:

[0174] (1) tanδ A rubber test piece for viscoelasticity measurement, 20 mm long x 4 mm wide x 2 mm thick, was cut from the cap rubber layer of the tread portion of each test tire, with the long side aligned in the tire circumferential direction. For each rubber test piece, tan δ was measured using a GABO Iplexer series under conditions of a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of 1%, a deformation mode of tension, and measurement temperatures of 0°C and 30°C, to obtain 0°C tan δ and 30°C tan δ, respectively. The 0°C tan δ of the base rubber layer was set to 0.07.

[0175] (2) Tg For a rubber test piece for viscoelasticity measurement, similarly cut out from the cap rubber layer, tan δ was measured using an "IPLEXER (registered trademark)" manufactured by GABO Corporation under conditions of a frequency of 10 Hz, an initial strain of 2%, an amplitude of ±1%, and a heating rate of 2°C / min, changing the temperature from -60°C to 40°C, and the temperature corresponding to the largest tan δ value in the obtained temperature distribution curve was determined as Tg.

[0176] (3) Complex modulus The complex modulus (MPa) of a rubber test piece for viscoelasticity measurement, similarly cut out from the cap rubber layer, is measured using an Iplexer series manufactured by GABO 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 deformation mode: extension. The complex modulus of the base rubber layer is set to 12.0 MPa.

[0177] (4) Acetone extractables (AE) of the cap rubber layer Using a vulcanized rubber test piece cut out from the cap rubber layer of the tread portion of each test tire, the AE (mass%) is determined in accordance with JIS K 6229:2015.

[0178] (5) (SBR content / land ratio), (silica content / aspect ratio) Additionally, based on the specifications and compounding details of each test tire, the ratio of the content (parts by mass) of styrene butadiene rubber (SBR) with a styrene content of 25% by mass or less in 100 parts by mass of the rubber component to the land ratio (%) in the tread portion (SBR content / land ratio) and the ratio of the content (parts by mass) of silica to 100 parts by mass of the rubber component to the aspect ratio (%) (silica content / aspect ratio) are calculated.

[0179] 5. Performance evaluation test (evaluation of ride comfort performance) Each test tire was fitted to all wheels of a vehicle (a domestically produced FF vehicle with an engine displacement of 2000cc) and inflated to an internal pressure of 250 kPa (the standard internal pressure for a passenger car). The vehicle was then driven at 180 km / h on a test course with a dry asphalt surface, and 20 drivers each performed a sensory evaluation of the ride comfort during the drive on a 5-point scale (the higher the number, the better). The total score for the evaluations by the 20 drivers was then calculated.

[0180] Next, the result of Comparative Example 1 was set to 100 and indexed according to the following formula to evaluate the ride comfort performance during high-speed driving. A larger value indicates better ride comfort performance during high-speed driving. Ride comfort performance when driving at high speeds = [(Test tire results) / (Comparative example 1 results)] × 100

[0181] [Table 2]

[0182] [Table 3]

[0183] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments. Various modifications can be made to the above-described embodiments within the scope of the same or equivalent to the present invention.

[0184] The present invention (1) is A tire having a tread portion, A cap rubber layer forming the tread portion is Styrene butadiene rubber (SBR) with a styrene content of 4% by mass or more and 25% by mass or less per 100 parts by mass of rubber components 25 Contains not less than 40 parts by mass and not more than 40 parts by mass, The loss tangent (0℃ tanδ) measured under the conditions of temperature 0℃, frequency 10Hz, initial strain 5%, dynamic strain rate 1%, deformation mode: tension is 0.30 The rubber composition is formed from the above rubber composition, The thickness of the tread portion is 10 mm or more and 20 mm or less, The tire is characterized in that the rubber composition forming the cap rubber layer contains silica, and the silica content of the rubber composition is 90 parts by mass or more per 100 parts by mass of the rubber component.

[0186] The present invention ( 2 )teeth, A tire having a tread portion, A cap rubber layer forming the tread portion is A styrene butadiene rubber (SBR) having a styrene content of 4% by mass or more and 25% by mass or less is contained in 15 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the rubber component, The rubber composition has a loss tangent (0°C tanδ) of 0.10 or more measured in a tensile deformation mode under the conditions of a temperature of 0°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%; The thickness of the tread portion is 10 mm or more and 20 mm or less, The aspect ratio is 30% or more and 60% or less, This tire is characterized in that the ratio of the silica content (parts by mass) to the aspect ratio (%) per 100 parts by mass of the rubber component [silica content (parts by mass) / aspect ratio (%)] is 1.5 or more.

[0187] The present invention ( 3 )teeth, The present invention (1) is characterized in that the amount of styrene in the styrene-butadiene rubber (SBR) is 4% by mass or more and 15% by mass or less. Or as stated in (2) It is a tire.

[0188] The present invention (4) is The content of the styrene butadiene rubber (SBR) 、3 The tire according to the present invention (1) or (2) is characterized in that the amount of the filler is 5 parts by mass or less.

[0189] The present invention (5) is The content of the styrene butadiene rubber (SBR) 、3 The tire according to the present invention (4) is characterized in that the total weight of the filler is 0 parts by mass or less.

[0190] The present invention (6) is The 0°C tan δ is 0.30 or more, This invention (2) The tire is described in the above.

[0191] The present invention (7) is The present invention is characterized in that the 0°C tan δ is 0.40 or more. (1) or (2) The tire is described in the above.

[0192] The present invention ( 8 )teeth, The loss tangent (30°C tanδ) of the cap rubber layer measured under the conditions of a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain rate of 1%, in a deformation mode of tension, is 0.25 or less, and the present invention (1) is characterized in that Or as stated in (2) It is a tire.

[0193] The present invention ( 9 )teeth, The present invention (1) is characterized in that the glass transition temperature (Tg) of the cap rubber layer is higher than -40°C. Or as stated in (2) It is a tire.

[0194] The present invention ( 10 )teeth, The present invention (1) is characterized in that the content of silica in the rubber composition forming the cap rubber layer is 100 parts by mass or more per 100 parts by mass of the rubber component. Or as stated in (2) It is a tire.

Claims

1. A tire having a tread portion, A cap rubber layer forming the tread portion is a styrene-butadiene rubber (SBR) having a styrene content of 4% by mass or more and 25% by mass or less is contained in an amount of 25 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the rubber component; the rubber composition has a loss tangent (0°C tanδ) of 0.30 or more measured under the conditions of a temperature of 0°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%, in a deformation mode of tension; The thickness of the tread portion is 10 mm or more and 20 mm or less, The tire is characterized in that the rubber composition forming the cap rubber layer contains silica, and the silica content of the rubber composition is 90 parts by mass or more per 100 parts by mass of the rubber component.

2. A tire having a tread portion, A cap rubber layer forming the tread portion is a styrene-butadiene rubber (SBR) having a styrene content of 4% by mass or more and 25% by mass or less is contained in an amount of 15 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the rubber component; the rubber composition has a loss tangent (0°C tanδ) of 0.10 or more, measured under the conditions of a temperature of 0°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%, in a deformation mode of tension; The thickness of the tread portion is 10 mm or more and 20 mm or less, The aspect ratio is 30% or more and 60% or less, A tire characterized in that the ratio of the silica content (parts by mass) to the aspect ratio (%) per 100 parts by mass of the rubber component [silica content (parts by mass) / aspect ratio (%)] is 1.5 or more.

3. 3. The tire according to claim 1, wherein the styrene-butadiene rubber (SBR) contains 4% by mass or more and 15% by mass or less of styrene.

4. 3. The tire according to claim 1, wherein the content of the styrene-butadiene rubber (SBR) is 35 parts by mass or less.

5. 5. The tire according to claim 4, wherein the content of the styrene-butadiene rubber (SBR) is 30 parts by mass or less.

6. 3. The tire according to claim 2, wherein the 0° C. tan δ is 0.30 or more.

7. 3. The tire according to claim 1, wherein the 0° C. tan δ is 0.40 or more.

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

9. The tire according to claim 1 or 2, wherein the cap rubber layer has a glass transition temperature (Tg) of higher than -40°C.

10. 3. The tire according to claim 1, wherein the content of silica in the rubber composition forming the cap rubber layer is 100 parts by mass or more per 100 parts by mass of the rubber component.

Images