JP2024074869A - tire - Google Patents

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

The present invention relates to a tire.

Tires are required to provide a comfortable ride, and various techniques have been proposed to improve the ride comfort (for example, Patent Documents 1 to 4).

JP 2005-263175 A JP 2010-132772 A JP 2019-065270 A JP 2021-172248 A

However, with the construction of expressways in recent years, the number of opportunities to travel long distances at high speeds has increased dramatically. However, tires manufactured based on the above-mentioned conventional technology still do not provide sufficient ride comfort when traveling at high speeds, and further improvements are strongly desired.

Therefore, the objective of the present invention is to improve ride comfort during high-speed driving.

The present invention relates to
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 tan δ) 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 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.

The present invention also provides a method for producing a semiconductor device comprising the steps of:
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 tan δ) 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,
A land ratio in the tread portion is 60% or more,
The tire is characterized in that the ratio of the content (parts by mass) of styrene butadiene rubber (SBR) having a styrene content of 25 mass% or less in 100 parts by mass of the rubber component of the cap rubber layer to the land ratio (%) in the tread portion [SBR content (parts by mass) with a styrene content of 25 mass% or less / land ratio (%)] is 0.7 or less.

The present invention also provides a method for producing a semiconductor device comprising the steps of:
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 tan δ) 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,
The 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.

The present invention can improve ride comfort during high-speed driving.

[1] Features of the Tire According to the Present Invention First, the features of the tire according to the present invention will be described.

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 a rubber component, and having a loss tangent (0°C tan δ) of 0.10 or more measured 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%, in a deformation mode: tension. The thickness of the tread portion is 10 mm or more and 20 mm or less.

The cap rubber layer referred to here is not limited to the cap rubber layer that forms the outermost layer of the tread portion. 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.

These features make it possible to improve ride comfort during high-speed driving, as described below.

2. Mechanism of manifestation of effects in the tire according to the present invention The mechanism of manifestation of the above-mentioned effects in the tire according to the present invention is believed to be as follows.

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.

SBR with a low styrene content, specifically, 25% by mass or less, has a low glass transition temperature (Tg), so by including such low styrene content SBR in the rubber component, an interface can be formed between the styrene portion of the SBR and other polymers. This interface can then absorb and mitigate the impact that the tire receives from the outside (road surface) while traveling at high speeds.

At the same time, by including 40 parts by mass or less of SBR with a low styrene content (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 and allow it to move flexibly, so that they can absorb and mitigate the impacts that the tire receives from the outside (road surface) while traveling at high speeds.

The amount of styrene is preferably 20% by mass or less, and 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.

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 entire SBR is 25% by mass or less.

In other words, if the rubber component contains only a styrene-containing polymer (SBR), the styrene content is 25% by mass or less. If the rubber component contains multiple styrene-containing polymers (SBR), the styrene content calculated by the sum of 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.

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 amount of styrene calculated from the formula {(S1 x X1) + (S2 x X2)}/(X1 + X2) is 25% by mass or less.

In addition, for vulcanized rubber compositions, the amount of styrene contained in the rubber components after acetone extraction can also be calculated using solid-state nuclear magnetic resonance (solid-state NMR) or Fourier transform infrared spectroscopy (FTIR).

In the present invention, the rubber composition forming the cap rubber layer further has a loss tangent (0°C tan δ) 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.

Loss tangent tan δ 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, 0°C tan δ is set to a large value of 0.10 or more, so that even during high-speed driving where high-frequency vibrations occur, the energy of vibrations 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.

The loss tangent tan δ is preferably 0.30 or less, and more preferably 0.25 or less, as the loss tangent (30°C tan δ) measured under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%, in a deformation mode of tension. By appropriately controlling 30°C tan δ to such a value, the tread portion that is deflected by contact with the road surface during rolling can easily restore to its original shape when it leaves the road surface, and can easily deflect again when the tire re-contacts the ground, which is believed to improve ride comfort.

In the above, the loss tangent (tan δ) can be measured using a viscoelasticity measuring device such as GABO's "IPLEXER (registered trademark)".

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 easily flexed and deformed, improving the ride comfort performance. It is more preferable that the thickness is 12 mm or more and 18 mm or less, and even more preferable that the thickness is 14 mm or more and 16 mm or less.

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.

When the tire has grooves on the equatorial plane, this refers to the thickness from the intersection of the straight 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.

The tread portion is the area that forms the tire's contact surface, but refers to the portion radially outward of the carcass, belt layer, belt reinforcing layer, and other components that contain fiber materials. The thickness of the tread portion can be measured by aligning the bead portion to the standard rim width in a cross section cut out in the radial direction of the tire.

A "genuine rim" is a rim that is determined for each tire by the standard system that includes the standards on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Manufacturers Association), this refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," in the case of ETRTO (The European Tire and Rim Technical Organization), this refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and in the case of TRA (The Tire and Rim Association, Inc.), this refers to the "Design Rim" listed in the "YEAR BOOK." Reference should be made in the order of JATMA, ETRTO, and TRA, and if an applicable size is available at the time of reference, that standard should be followed. In the case of tires not specified by the standard, it refers to the rim that can be mounted on a rim and can maintain internal pressure, i.e., the rim that does not leak air between the rim and tire, and has the smallest rim diameter and the next narrowest rim width.

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

[2] More Preferred Aspects 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.

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 considered that the ride comfort performance during high-speed driving is further improved because tan δ at around 0° C. is easily increased by making the Tg higher.

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, a 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, and the temperature corresponding to the largest tan δ value in the range of -60°C or more and 40°C or less 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 or more and 40°C or less, the point with the lowest temperature is defined as Tg. For example, in the present invention, if the maximum value of tan δ is in the range of -60°C or more and 40°C or less, the temperature showing the maximum value is 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 the range of -60°C or more and 40°C or less, and the temperature at which tan δ is maximum is -60°C, then the glass transition temperature (Tg) is -60°C according to the above definition.

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

As mentioned 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.

In this case, it is preferable to set the 0°C tan δ of the base rubber layer smaller than the 0°C tan δ of the cap rubber layer. This improves responsiveness to the grip performance generated by the cap rubber layer, thereby sufficiently improving ride comfort during high-speed driving.

The 0°C tan δ of the cap rubber layer and base rubber layer can be adjusted as appropriate by the amount and type of compounding 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, and increasing the content of resin components. 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, and decreasing the content of resin components.

In the case of a multi-layered tread portion, it is preferable that 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 smaller than the complex modulus of the cap rubber layer measured in the same manner. These complex moduli can be measured, for example, using a viscoelasticity measuring device such as GABO's "IPLEXER (registered trademark)".

The complex modulus of elasticity is a parameter that indicates the rigidity of the rubber layer. By making the complex modulus of elasticity of the base rubber layer smaller than that 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, improving ground contact and significantly improving ride comfort during high-speed driving.

3. Inclusion of silica in the cap rubber layer In the present invention, the rubber composition forming the cap rubber layer preferably contains silica. By including silica, the flexibly moving minute styrene domains and the silica tend to generate friction, and further increase heat generation and release vibration energy, so that the ride comfort during high-speed driving can be sufficiently improved.

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 taking into consideration the kneading processability and molding processability of the rubber composition, it 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.

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

The average primary particle diameter can be calculated by directly observing silica particles extracted from the 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 calculating the average value.

4. Inclusion of Resin Component in Cap Rubber Layer In the present invention, the rubber composition forming the cap rubber layer preferably contains a resin component.

By including a resin component in the rubber composition, the adhesiveness of the resin component improves the tire's ability to adhere to the road surface, and ride comfort during high-speed driving can be significantly improved.

Preferred resin components include rosin-based resins, styrene-based resins, coumarone-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, and acrylic-based resins, which will be described later, and among these, styrene-based 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.

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.

The acetone extractables (AE) can be considered as an index showing the amount of softeners and the like 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 in the cap rubber layer as described above, the area of the tire in contact with the road surface is sufficiently secured, improving ground contact and sufficiently improving ride comfort during high-speed driving.

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 specified time and determining the mass loss rate (%) of the test piece.

More specifically, each vulcanized rubber test piece is immersed in acetone for 72 hours at room temperature and normal pressure to extract the soluble components, and the mass of each test piece before and after extraction is measured, and the mass can be calculated according to 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

The amount of acetone extractables can be adjusted by changing the blending ratio of the plasticizer in the rubber composition.

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

"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. If the land ratio is large, the area in contact with the road surface will be larger, improving ground contact and significantly improving ride comfort when driving at high speeds.

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.

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

Specifically, the tire is mounted on a standard rim, the standard internal pressure is applied, and the tire is left to stand at 25°C for 24 hours. After that, ink is applied to the surface of the tire tread, and the standard load is applied and pressed against cardboard (camber angle is 0°), and the contact shape is transferred to the paper, so the tire is rotated 72° in the circumferential direction and transferred at five locations. In other words, five contact shapes are obtained. At this time, the parts of the five contact shapes that are interrupted by the grooves in the outline of the contact shape are smoothly connected, and the resulting shape is called the virtual contact surface.

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 (%).

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

The "normal load" is 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 described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". As in the case of the "normal rim" and "normal internal pressure" described above, JATMA, ETRTO, and TRA are referred to in that order and their standards are followed. In the case of a tire not determined by a standard, the normal load W _L is calculated as follows.
V = {(Dt/2) ² - (Dt/2 - Ht) ² } x π x Wt
_WL = 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)

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 in 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 due to the styrene domains works together to further improve the ride comfort performance during high-speed driving. It is more preferable that it is 0.6 or less. The lower limit is not particularly limited, but it is preferably 0.3 or more, and more preferably 0.4 or more.

7. Aspect Ratio The aspect ratio is the tire's cross-sectional height relative to its cross-sectional width. The smaller this ratio is, the better the tire's contact with the road surface and the more comfortable it is to ride at high speeds. On the other hand, if the aspect ratio is low, the amount of deflection at the side is small, which may lead to a deterioration in ride comfort.

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.

The above aspect ratio (%) can be calculated by 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 250 kPa.
Aspect ratio (%) = (Ht/Wt) x 100 (%)
Ht = (Dt - R) / 2

In this case, if the ratio of the silica content (parts by mass) to the aspect ratio (%) relative to 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 the ride comfort performance during high-speed driving. It is more preferable that it is 1.7 or more. There is no particular upper limit, but it is preferably 2.2 or less, and more preferably 2.1 or less.

[3] Embodiments Hereinafter, the present invention will be described in detail based on embodiments.

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.

(1) Compounding Materials (a) Rubber Component The rubber component is not particularly limited, and rubbers (polymers) that are generally 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).

In the present invention, among these, from the viewpoint of including styrene in the rubber component, it is preferable to include one of styrene-based polymers such as SBR, SBS, and SB, and to include SBR. In addition, 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 preferable.

(a) Special Branch Office
The weight average molecular weight of the SBR is, for example, more than 100,000 and less than 2,000,000. In the present 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 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 portion in the SBR component. The structure of the SBR (measurement of the styrene amount and vinyl content) can be identified using, for example, a JNM-ECA series device manufactured by JEOL Ltd.

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, 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.

There are no particular limitations on the SBR, 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. Hydrogenated SBR, in which the butadiene portion of SBR is hydrogenated, 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.

The modified SBR may be any SBR having a functional group that interacts with a filler such as silica. Examples of the modified SBR include terminally modified SBR (terminally modified SBR having the above-mentioned functional group at the terminal) in which at least one terminal of the SBR has been modified with a compound (modifying agent) having the above-mentioned functional group, main-chain modified SBR having the above-mentioned functional group in the main chain, main-chain terminally modified SBR having the above-mentioned functional group in the main chain and at least one terminal (for example, main-chain terminally modified SBR having the above-mentioned functional group in the main chain and at least one terminal modified with the above-mentioned modifying agent), and terminally modified SBR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or epoxy group introduced therein.

Examples of the 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, and epoxy groups. These functional groups may have a substituent.

In addition, the modified SBR may be, for example, SBR modified with a compound (modifier) represented by the following formula:

In the formula, R ¹ , 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 a derivative 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 be bonded to form a ring structure together with the nitrogen atom. n represents an integer.

As 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).

R ¹ , R ² and R ³ are preferably alkoxy groups (preferably alkoxy groups having 1 to 8 carbon atoms, more preferably alkoxy groups having 1 to 4 carbon atoms). R ⁴ and R ⁵ are preferably alkyl groups (preferably alkyl groups having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. When R ⁴ and R ⁵ are bonded to form a ring structure together with the nitrogen atom, it is preferably a 4- to 8-membered ring. The alkoxy group also includes cycloalkoxy groups (cyclohexyloxy group, etc.) and aryloxy groups (phenoxy group, benzyloxy group, etc.).

Specific examples of the above-mentioned 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.

In addition, modified SBR modified with the following compounds (modifiers) can also be used as modified SBR. Modifiers include, 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 diglycidylated bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; 4,4'-diglycidyl-diphenylmethylamine, 4,4 Epoxy group-containing tertiary amines such as N,N'-diglycidyl-dibenzylmethylamine; diglycidylamino compounds such as diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidylorthotoluidine, tetraglycidylmetaxylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; bis-(1-methylpropyl)carbamic acid chloride, 4-morpholinecarbonyl chloride, 1 -pyrrolidine carbonyl chloride, N,N-dimethylcarbamic acid chloride, N,N-diethylcarbamic acid chloride, and other amino group-containing acid chlorides; 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane, (3-glycidyloxypropyl)-pentamethyldisiloxane, and other epoxy group-containing silane compounds; (trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(trippropoxysilyl)propyl]sulfide, ( Sulfide group-containing silane compounds such as (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxysilyl)propyl]sulfide, and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)propyl ... alkoxysilanes such as N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane; 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' (thio)benzophenone compounds having an amino group and/or a substituted amino group, such as N,N-bis(diphenylamino)benzophenone and N,N,N',N'-bis-(tetraethylamino)benzophenone; benzaldehyde compounds having an amino group and/or a substituted amino group, such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde and 4-N,N-divinylaminobenzaldehyde; N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-t-butyl-2-pyrrolidone, N-methyl N-substituted pyrrolidones 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), triphenylamine, ... Examples of the compound include 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone, and the like. Modification with the above compounds (modifiers) can be carried out by known methods.

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. Note that SBR may be used alone or in combination of two or more types.

(b) BR
In the present invention, the rubber composition may contain BR. In this case, the content of BR in 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, and is preferably 30 parts by mass or less, and more preferably 25 parts by mass or less.

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 mass% and less than 30 mass%. The cis content of the BR is, for example, more than 1 mass% and less than 98 mass%. The trans content of the BR is, for example, more than 1 mass% and less than 60 mass%.

The BR is not particularly limited, and can be BR with a high cis content (cis content of 90% or more), BR with a low cis content, BR containing syndiotactic polybutadiene crystals, etc. The BR can be either unmodified BR or modified BR, and modified BR can be modified BR with the aforementioned functional groups introduced. These can be used alone or in combination of two or more types. The cis content can be measured by infrared absorption spectroscopy.

For example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, etc. can be used as BR.

(C) Isoprene-based rubber In the present invention, the rubber composition may contain an isoprene-based rubber. In this case, the content of the isoprene-based rubber in 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 50 parts by mass or more. On the other hand, it is preferably 70 parts by mass or less, more preferably less than 60 parts by mass.

Isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, etc.

As the NR, for example, SIR20, RSS#3, TSR20, SVR-L, etc., which are common in the tire industry, can be used. As the IR, there is no particular limitation, and for example, IR2200, etc., which are common in the tire industry can be used. As the modified NR, deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. can be used. As the modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. can be used. As the modified IR, epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. can be used. These may be used alone or in combination of two or more.

(d) Other Rubber Components The other rubber components may include rubbers (polymers) that are generally used in the manufacture of tires, such as nitrile rubber (NBR).

(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.

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

The BET specific surface area of the silica is preferably more than 140 m ² /g, more preferably more than 160 m ² /g, from the viewpoint of obtaining good durability performance. On the other hand, from the viewpoint of obtaining good rolling resistance during high-speed driving, it is preferably less than 250 m ² /g, more preferably less than 220 m ² /g. The above-mentioned BET specific surface area is the value of N ₂ SA measured by the BET method in accordance with ASTM D3037-93.

In the present invention, as described above, it is preferable to use silica having a particle size of 17 nm or less for 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, and the mobility of the polymer can be increased, thereby improving the ride comfort performance. There is no particular lower limit, but it is preferable that it is 10 nm or more from the viewpoint of dispersibility during mixing.

When silica is used as a reinforcing filler, 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. There is no particular upper limit, but it 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.

Examples of silica include dry process silica (anhydrous silica) and wet process silica (hydrated silica). Of these, 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.

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

(i-2) Silane Coupling Agent When silica is used as a 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, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl Examples of such silanes include sulfide-based silanes such as rubamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide, mercapto-based silanes such as 3-mercaptopropyl trimethoxysilane, 2-mercaptoethyl triethoxysilane, and Momentive's NXT and NXT-Z, vinyl-based silanes such as vinyl triethoxysilane and vinyl trimethoxysilane, amino-based silanes such as 3-aminopropyl triethoxysilane and 3-aminopropyl trimethoxysilane, glycidoxy-based silanes such as γ-glycidoxypropyl triethoxysilane and γ-glycidoxypropyl trimethoxysilane, nitro-based silanes such as 3-nitropropyl trimethoxysilane and 3-nitropropyl triethoxysilane, and chloro-based silanes such as 3-chloropropyl trimethoxysilane and 3-chloropropyl triethoxysilane. These silanes may be used alone or in combination of two or more.

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

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

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

The specific content ratio of carbon black per 100 parts by mass of the rubber component is preferably 5 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 20 parts by mass or less.

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.

The CTAB specific surface area (Cetyl Tri-methyl Ammonium Bromide) of the carbon black is preferably 130 m ² /g or more, more preferably 160 m ² /g or more, and even more preferably 170 m ² /g or more. On the other hand, it is preferably 250 m ² /g or less, and more preferably 200 m ² /g or less. The CTAB specific surface area is a value measured in accordance with ASTM D3765-92.

Specific carbon blacks are not particularly limited, and 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 Co., Ltd., Lion Co., Ltd., Shin-Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., and the like. These may be used alone or in combination of two or more types.

(iii) Other Fillers In addition to the above-mentioned silica and carbon black, 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.

(B) Plasticizer Component The rubber composition may contain oil (including extender oil), liquid rubber, and resin as plasticizer components that soften 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.

(i) Oils Examples of oils include mineral oils (generally called 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 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 alone or in combination of two or more. In addition, from the viewpoint of life cycle assessment, waste oils after being used as lubricating oils for rubber mixers and automobile engines, waste edible oils, and the like may be used appropriately.

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, Orisoy Corporation, H&R Corporation, Toyokuni Seiyu Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., etc.

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

Farnesene polymers are polymers obtained by polymerizing farnesene and contain 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).

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).

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).

The liquid diene polymer has a weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) of, for example, more than 1.0 × 10 ³ and less than 2.0 × 10 ^5. In this specification, the Mw of the liquid diene polymer is a value in terms of polystyrene measured by gel permeation chromatography (GPC).

The liquid rubber content (total content of liquid farnesene-based polymer, liquid diene-based 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.

As liquid rubber, for example, products from Kuraray Co., Ltd., Cray Valley, Inc., etc. can be used.

(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 resin, styrene resin, coumarone resin, terpene resin, C5 resin, C9 resin, C5C9 resin, and acrylic resin, and two or more of them 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, based on 100 parts by mass of the rubber component. In addition, these resin components may be provided with a modified group capable of reacting with silica or the like, as necessary.

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 they have been 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 of such modifications include rosin esters, unsaturated carboxylic acid modified rosin esters, unsaturated carboxylic acid modified rosin esters, rosin amide compounds, and rosin amine salts.

Styrene-based resins are polymers that use styrene-based monomers as constituent monomers, and examples thereof include polymers in which styrene-based monomers are polymerized as the main component (50% by mass or more). Specifically, examples include homopolymers in which styrene-based monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) are polymerized alone, copolymers in which two or more styrene-based monomers are copolymerized, and copolymers of styrene-based monomers and other monomers that can be copolymerized with them.

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 their acid anhydrides, etc.

Among the coumarone resins, coumarone-indene resins are preferred. Coumarone-indene resins are resins that contain coumarone and indene as monomer components that make up the resin skeleton (main chain). Other monomer components contained in the skeleton besides coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

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

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 the acetic acid bonded to the hydroxyl group when acetylating 1 g of resin, and is a value measured by potentiometric titration (JIS K 0070:1992).

The softening point of 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 as specified in JIS K 6220-1:2001 is measured using a ring and ball softening point tester.

Examples of terpene resins include polyterpene, terpene phenol, and aromatic modified terpene resin. Polyterpene is a resin obtained by polymerizing a terpene compound and a hydrogenated product thereof. Terpene compounds are hydrocarbons represented by the composition (C ₅ H ₈ ) _n and their oxygen-containing derivatives, and are compounds having a basic skeleton of terpenes classified as monoterpenes (C ₁₀ H ₁₆ ), sesquiterpenes (C ₁₅ H ₂₄ ), diterpenes (C ₂₀ H ₃₂ ), and examples of such compounds 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.

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, specifically 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 has an aromatic ring, but examples thereof include phenolic compounds such as phenol, alkylphenols, alkoxyphenols, and phenols containing unsaturated hydrocarbon groups; naphthol compounds such as naphthol, alkylnaphthols, alkoxynaphthols, and naphthols containing unsaturated hydrocarbon groups; styrene derivatives such as styrene, alkylstyrenes, alkoxystyrenes, and styrenes containing unsaturated hydrocarbon groups; coumarone, indene, and the like.

"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 petroleum resin.

"C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a resin obtained by hydrogenating or modifying the C9 fraction. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of suitable resins include coumarone-indene resin, coumarone resin, indene resin, and aromatic vinyl resin. 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, because they are economical, easy to process, and have excellent heat generation properties. As aromatic vinyl resins, those commercially available from Kraton, Eastman Chemical, etc. can be used.

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

There are no particular limitations on the acrylic resin, but for example, a solvent-free acrylic resin can be used.

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-59-6207, JP-B-5-58005, JP-A-1-313522, U.S. Pat. No. 5,010,166, and Toa Gosei Kenkyuu Nenpo 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 means methacryl and acrylic.

Examples of 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.

In addition, aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene may be used together with (meth)acrylic acid or (meth)acrylic acid derivatives as monomer components constituting the above acrylic resin.

The acrylic resin may be a resin composed only of (meth)acrylic components, or a resin containing components other than (meth)acrylic components. The acrylic resin may also have hydroxyl groups, carboxyl groups, silanol groups, etc.

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 Co., Ltd., Taoka Chemical Co., Ltd., etc. can be used.

(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, a conventionally known product can be used, for example, a product of NOF Corporation, NOF Corporation, Kao Corporation, FUJIFILM Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used.

(D) Antiaging Agent In the present invention, the rubber composition preferably contains an antiaging agent. The content of the antiaging 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.

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

As anti-aging agents, products from, for example, Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flexis, Inc., etc. can be used.

(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.

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 kinds.

As wax, products from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used.

(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, and for example, products of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

(G) Crosslinking Agent and Vulcanization Accelerator The rubber composition preferably contains a crosslinking agent such as sulfur. 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.

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

As sulfur, products from, for example, Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzatsu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

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.

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.

Examples of vulcanization accelerators 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, N-t-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenyl guanidine, di-orthotolyl guanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more.

(H) 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, 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.

(2) Preparation of Rubber Composition The rubber composition for forming 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 process in which a rubber component and a filler such as carbon black are kneaded together, and a finish kneading process in which the kneaded product obtained in the base kneading process is kneaded together with a crosslinking agent.

The kneading can be carried out using a known (closed) kneading machine such as a Banbury mixer, kneader, or open roll.

The kneading temperature in the base kneading step is, for example, more than 50°C and less than 200°C, and the kneading time is, for example, more than 30 seconds and less than 30 minutes. In the base kneading step, in addition to the above components, compounding agents conventionally used in the rubber industry, such as softeners such as oil, zinc oxide, antioxidants, wax, vulcanization accelerators, etc., may be added and kneaded as necessary.

In the final kneading process, the mixture obtained in the base kneading process is kneaded with a crosslinking agent. The kneading temperature in the final kneading process is, for example, above room temperature and below 80°C, and the kneading time is, for example, more than 1 minute and less than 15 minutes. In the final kneading process, in addition to the above components, vulcanization accelerators, zinc oxide, etc. may be appropriately added and kneaded as necessary.

2. Manufacturing of Tire The tire according to the present invention can be manufactured as an unvulcanized tire by molding a tread rubber of a predetermined shape using the rubber composition obtained above as a cap rubber layer, and then molding the tread rubber together with other tire components in a tire building machine by a normal method.

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 obtained by using the above-mentioned rubber components and compounding materials, changing the compounding amounts as appropriate, and kneading 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 molded together with other tire components in a tire building machine in the usual manner to produce an unvulcanized tire.

Specifically, an inner liner as a member to ensure the airtightness of the tire, a carcass as a member to withstand the load, impact, and filling air pressure that the tire receives, and a belt member as a member to tighten the carcass and increase the rigidity of the tread are wound around the forming drum, both ends of the carcass are fixed to both side edges, and beads as members to secure the tire to the rim are placed. After forming into a toroidal shape, the tread is attached to the center of the outer circumference and the sidewall is attached to the radially outer side to form the side portion, and an unvulcanized tire is produced.

The unvulcanized tire thus produced is then heated and pressurized in a vulcanizer to obtain a tire. The vulcanization process can be carried out by applying known vulcanization methods. 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.

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

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. It is also preferably used as a pneumatic tire.

Below, examples (working examples) that are considered to be 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, a pneumatic tire (tire size 205/55R16, aspect ratio: 55%, land ratio: 65%) made from a composition obtained by varying the blending according to each table using the various chemicals shown below was examined, and the results calculated based on the following evaluation method are shown in Tables 2 and 3.

1. Rubber composition for forming the cap rubber layer (1) Compounding materials (a) Rubber component (a) NR: SVR-L
(ii) SBR-1: Modified S-SBR obtained by the method shown 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 (Hisis BR) from Ube Industries, Ltd.
(cis content 97% by mass, trans content 2% by mass, vinyl content 1% by mass)

(Production of SBR-1)
The SBR-1 is prepared according to the following procedure. First, two autoclaves with an internal volume of 10 L, an inlet at the bottom and an outlet at the top, and equipped with a stirrer and a jacket are connected in series as reactors, and butadiene, styrene, and cyclohexane are mixed in a predetermined ratio. This mixed solution is passed through a dehydration column filled with activated alumina, and mixed with n-butyllithium in a static mixer to remove impurities, and then continuously fed from the bottom of the first reactor, and further 2,2-bis(2-oxolanyl)propane as a polar substance and n-butyllithium as a polymerization initiator are continuously fed from the bottom of the first reactor at a predetermined rate, respectively, and the temperature inside the reactor is maintained at 95° C. The polymer solution is continuously withdrawn from the head of the reactor and fed to the second reactor. The temperature of the second reactor is kept at 95°C, and a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane (monomer) as a modifier and an oligomer component is continuously added as a 1000-fold diluted solution of cyclohexane at a predetermined rate to carry out a modification reaction. This polymer solution is continuously withdrawn from the reactor, and an antioxidant is continuously added using a static mixer, after which the solvent is removed to obtain the desired modified diene polymer (SBR-1).

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

(b) Compounding materials other than rubber components (a) Carbon black: Diablack N220 manufactured by Mitsubishi Chemical Corporation
( _N2SA : ^115m2 /g)
(b) Silica: Ultrasil VN3 manufactured by Evonik Industries
( _N2SA : 175 ^m2 /g, average primary particle size: 17 nm)
(c) Silane coupling agent: Si266 manufactured by Evonik Industries
(Bis(3-triethoxysilylpropyl)disulfide)
(d) Resin: SYLVATRAXX4401 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: Bead 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))

(2) Rubber composition for forming cap rubber layer According to the respective compounding contents shown in Tables 2 and 3, materials other than sulfur and vulcanization accelerator are kneaded for 5 minutes under the condition of 150°C using a Banbury mixer to obtain a kneaded product. Note that each compounding amount is in parts by mass.

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

2. Rubber Composition for Forming 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.

3. Manufacture of Pneumatic Tires Using each rubber composition, a tread portion was manufactured by extruding 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.

Then, it is laminated together with other tire components to form an unvulcanized tire, and press-vulcanized for 10 minutes under conditions 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.

4. Calculation of parameters After that, the following parameters are calculated for each test tire.

(1) tan δ
A rubber test piece for viscoelasticity measurement was prepared by cutting out a piece of 20 mm length x 4 mm width x 2 mm thickness from the cap rubber layer of the tread portion of each test tire, with the long side being in the tire circumferential direction, and measuring tan δ for each rubber test piece using an Iplexer series manufactured by GABO Corporation under the conditions of a frequency of 10 Hz, initial strain of 5%, dynamic strain of 1%, deformation mode: tension, and measuring temperatures: 0°C and 30°C, respectively, to obtain 0°C tan δ and 30°C tan δ. The 0°C tan δ of the base rubber layer is set to 0.07.

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

(3) Complex modulus of elasticity The complex modulus of elasticity (MPa) of a rubber test piece for viscoelasticity measurement, which is similarly cut out from the cap rubber layer, is measured under the conditions of temperature 0°C, frequency 10 Hz, initial strain 5%, dynamic strain 1%, and deformation mode: extension, using an Iplexer series manufactured by GABO Co., Ltd. The complex modulus of elasticity of the base rubber layer is set to 12.0 MPa.

(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.

(5) (SBR content/land ratio), (silica content/aspect ratio)
Additionally, based on the specifications and compounding contents of each test tire, the ratio of the content (parts by mass) of styrene butadiene rubber (SBR) having a styrene content of 25 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 the aspect ratio (%) for 100 parts by mass of the rubber component (silica content/aspect ratio) are calculated.

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 filled with air to an internal pressure of 250 kPa (the normal internal pressure of 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 of the evaluations by the 20 drivers was then calculated.

Next, the result of Comparative Example 1 was set as 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)] x 100

The present invention has been described above based on an embodiment, but the present invention is not limited to the above embodiment. Various modifications can be made to the above embodiment within the same or equivalent scope as the present invention.

The present invention (1) is
A tire having a tread portion,
A cap rubber layer forming the tread portion is
A styrene-butadiene rubber (SBR) having a styrene content of 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 tan δ) 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 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.

The present invention (2) is
A tire having a tread portion,
A cap rubber layer forming the tread portion is
A styrene-butadiene rubber (SBR) having a styrene content of 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 tan δ) 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,
A land ratio in the tread portion is 60% or more,
The tire is characterized in that the ratio of the content (parts by mass) of styrene butadiene rubber (SBR) having a styrene content of 25 mass% or less in 100 parts by mass of the rubber component of the cap rubber layer to the land ratio (%) in the tread portion [SBR content (parts by mass) with a styrene content of 25 mass% or less / land ratio (%)] is 0.7 or less.

The present invention (3) is
A tire having a tread portion,
A cap rubber layer forming the tread portion is
A styrene-butadiene rubber (SBR) having a styrene content of 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 tan δ) 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,
The 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.

The present invention ( 4 ) is
The styrene-butadiene rubber (SBR) has a styrene content of 4% by mass or more and 15% by mass or less, and is a tire in any combination with any of the present inventions (1) to (3) .

The present invention ( 5 ) is
The tire is characterized in that the content of the styrene-butadiene rubber (SBR) is 15 parts by mass or more and 35 parts by mass or less, and is an arbitrary combination with any of the present inventions (1) to (3) .

The present invention ( 6 ) is
The tire according to the present invention ( 5 ), characterized in that the content of the styrene-butadiene rubber (SBR) is 15 parts by mass or more and 30 parts by mass or less.

The present invention ( 7 ) relates to
The tire is characterized in that the 0° C. tan δ is 0.30 or more, and is an arbitrary combination with any of the present inventions (1) to ( 3 ).

The present invention ( 8 ) relates to
The tire according to the present invention (7) , characterized in that the 0° C. tan δ is 0.40 or more.

The present invention ( 9 ) relates to
The loss tangent (30°C tan δ) of the cap rubber layer measured under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%, in a deformation mode of tension, is 0.25 or less, and the tire is an arbitrary combination with any of the present inventions (1) to (3) .

The present invention ( 10 ) relates to
The cap rubber layer has a glass transition temperature (Tg) of higher than −40° C., and is a tire in any combination with any of the present inventions (1) to ( 3 ).

The present invention ( 11 ) relates to
The tire 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, and is any combination with any of the present inventions (1) to (3) .

Claims (11)

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 tan δ) 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 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. 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 tan δ) 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,
A land ratio in the tread portion is 60% or more,
A tire characterized in that the ratio of the content (parts by mass) of styrene butadiene rubber (SBR) having a styrene content of 25 mass% or less in 100 parts by mass of the rubber component of the cap rubber layer to the land ratio (%) in the tread portion [SBR content (parts by mass) of styrene content of 25 mass% or less / land ratio (%)] is 0.7 or less. 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 tan δ) 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 a ratio of a silica content (parts by mass) to an aspect ratio (%) relative to 100 parts by mass of a rubber component [silica content (parts by mass)/aspect ratio (%)] is 1.5 or more. The tire according to any one of claims 1 to 3, characterized in that the styrene-butadiene rubber (SBR) has a styrene content of 4 mass % or more and 15 mass % or less. The tire according to any one of claims 1 to 3, characterized in that a content of the styrene-butadiene rubber (SBR) is equal to or greater than 15 parts by mass and equal to or less than 35 parts by mass. The tire according to claim 5, characterized in that the content of the styrene-butadiene rubber (SBR) is 15 parts by mass or more and 30 parts by mass or less. The tire according to any one of claims 1 to 3, characterized in that the 0°C tan δ is 0.30 or more. The tire described in claim 7, characterized in that the 0°C tan δ is 0.40 or more. The tire according to any one of claims 1 to 3, characterized in that the loss tangent (30°C tan δ) 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. The tire according to any one of claims 1 to 3, characterized in that the glass transition temperature (Tg) of the cap rubber layer is greater than -40°C. The tire according to any one of claims 1 to 3, 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.