JP2024002375A - tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve wet grip performance during high-speed traveling.

SOLUTION: A tire includes a tread part. A cap rubber layer forming the tread part is formed from a rubber composition which contains 80 pts.mass or more and 100 pts.mass or less of styrene-butadiene rubber (SBR) with a styrene content of 25 mass% or less, in 100 pts.mass of a rubber component, and which contains 100 pts.mass or more of silica with respect to 100 pts.mass of the rubber component. The rubber composition has a loss tangent (30°C tanδ) of greater than 0.20 as measured in a deformation mode of tension under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%. The tread part has a thickness of 10 mm or greater and 20 mm or less.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to tires.

Tires are required to have high braking performance (grip performance) from the viewpoint of safety, and various techniques have been proposed for improving grip performance (for example, Patent Documents 1 to 3).

In particular, with the development of expressways in recent years, there is an increasing demand for improved grip performance (wet grip performance) when driving at high speeds on wet roads, as it is not uncommon to travel long distances on expressways. It's getting expensive.

JP2011-93386A Japanese Patent Application Publication No. 2013-79017 Unexamined Japanese Patent Publication No. 2016-37100

In view of the above-mentioned actual situation, it is an object of the present invention to improve wet grip performance during high-speed driving.

The present invention
A tire including a tread portion,
The cap rubber layer forming the tread portion is
Containing styrene butadiene rubber (SBR) having a styrene content of 25% by mass or less in 100 parts by mass of the rubber component, and containing 80 parts by mass or more and 100 parts by mass or less,
Containing 100 parts by mass or more of silica with respect to 100 parts by mass of the rubber component,
Formed from a rubber composition whose loss tangent (30°C tan δ) measured under the conditions of temperature 30°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1% in tensile mode is more than 0.20. and
The tire is characterized in that the thickness of the tread portion is 10 mm or more and 20 mm or less.

According to the present invention, it is possible to improve wet grip performance 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. Summary The tire according to the present invention is a tire having a tread portion, in which the cap rubber layer forming the tread portion contains SBR containing 25% by mass or less of styrene, 80 parts by mass or more in 100 parts by mass of the rubber component, It is formed from a rubber composition containing 100 parts by mass or less of silica and 100 parts by mass or more of silica based on 100 parts by mass of the rubber component. The loss tangent (30°C tan δ) of this rubber composition 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% is greater than 0.20. It is. Moreover, the thickness of the tread portion is 10 mm or more and 20 mm or less.

Note that the cap rubber layer referred to herein is not limited to the cap rubber layer that forms the outermost layer of the tread portion, but if there are two or more layers within 5 mm inward from the tread surface, at least one of the layers is It is sufficient as long as it satisfies the requirements for the rubber composition.

By having these characteristics, it is possible to improve the wet grip performance during high-speed driving, as will be described later.

2. Mechanism of the effect exerted in the tire according to the present invention The mechanism of the above-mentioned effect exerted in the tire according to the present invention is considered as follows.

As described above, the cap rubber layer of the tire according to the present invention contains SBR with a styrene content of 25% by mass or less in 100 parts by mass of the rubber component, and 80 parts by mass or more and 100 parts by mass or less in 100 parts by mass of the rubber component. It is formed from a rubber composition containing 100 parts by mass or more of silica.

SBR with a small amount of styrene, specifically, 25% by mass or less of styrene, has a low glass transition temperature (Tg), so it is contained in 80 parts by mass or more and 100 parts by mass or less in 100 parts by mass of the rubber component. By forming the majority of the cap rubber layer, the Tg of the entire rubber composition can be lowered, the softness of the rubber can be maintained even at low temperatures, and the followability to the road surface can be improved.

SBR, which has a small amount of styrene, forms minute styrene domains within the rubber matrix, increasing the mobility of the polymer and allowing it to move flexibly. As a result, the contact area between the road surface and the polymer can be increased. Furthermore, since the minute styrene domains can also provide a scratching effect on the road surface, the grip performance on the tread surface can be improved, and the wet grip performance during high-speed running can be improved.

In addition, the minute styrene domains that move flexibly rub against each other, making it easier to generate heat, which further promotes the movement of the minute styrene domains, further improving wet grip performance during high-speed driving. Can be done.

In addition, the amount of styrene described above is more preferably 20% by mass or less, and even more preferably 15% by mass or less. On the other hand, the lower limit is preferably 4% by mass or more, more preferably 5% by mass or more, and even more preferably 6% by mass or more.

In the present invention, "containing 80 parts by mass or more and 100 parts by mass or less of SBR with an amount of styrene of 25 parts by mass or less in 100 parts by mass of the rubber component" means that the amount of SBR in 100 parts by mass of the rubber component is The amount is 80 parts by mass or more and 100 parts by mass or less, indicating that the amount of styrene in the entire SBR is 25% by mass or less.

That is, when a styrene-containing polymer (SBR) is contained alone in the rubber component, it indicates that the amount of styrene is 25% by mass or less, and if the rubber component contains multiple styrene-containing polymers (SBR). , the amount of styrene determined by the sum of the products of the amount of styrene (% by mass) in each polymer and the amount (parts by mass) of that polymer per 100 parts by mass of the rubber component is 25% by mass. It shows that:

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

In addition, in the rubber composition after vulcanization, the amount of styrene contained in the rubber component after acetone extraction can also be determined by solid-state nuclear magnetic resonance (solid-state NMR) or Fourier transform infrared spectrophotometer (FTIR). It is possible to calculate.

In the present invention, silica is further contained in an amount equal to or greater than the rubber component, that is, 100 parts by mass or more per 100 parts by mass of the rubber component. By including a large amount of silica in this way, it becomes easier for the silica to generate friction between the flexibly moving minute styrene domains, which further increases heat generation and improves the wet grip performance of the tread surface. It is thought that this will become possible. It is more preferably 120 parts by mass or more, and even more preferably 130 parts by mass or more. The upper limit of the silica content is not particularly limited, but in consideration of the kneading processability and molding processability of the rubber composition, it is preferably 180 parts by mass or less, more preferably 160 parts by mass or less, and 150 parts by mass or less. More preferably, it is less than parts by mass.

In the present invention, the loss tangent (loss tangent ( 30° C. tan δ) is greater than 0.20.

The loss tangent tan δ is a viscoelastic parameter indicating energy absorption performance, and the larger the value, the more energy can be absorbed and converted into heat. In the present invention, since the tan δ at 30°C near normal temperature is set to exceed 0.20, it is possible to sufficiently absorb energy and convert it into heat, and energy loss due to conversion to heat in the entire tread rubber. It is thought that the wet grip performance during high-speed driving can be improved. It is more preferably 0.30 or more, and even more preferably 0.45 or more. The upper limit of tan δ at 30° C. is not particularly limited, but is preferably 0.60 or less, more preferably 0.50 or less, and even more preferably 0.45 or less.

In the above, the loss tangent (tan δ) can be measured, for example, using a viscoelasticity measuring device such as “Iprexor (registered trademark)” manufactured by GABO.

Further, in the tire according to the present invention, as described above, the thickness of the tread portion is set to be 10 mm or more and 20 mm or less. This makes it easier for the entire tread portion to bend and deform, improving ground contact, which is thought to improve wet grip performance during high-speed running. It is more preferably 12 mm or more and 18 mm or less, and even more preferably 14 mm or more and 16 mm or less.

The thickness of the tread section mentioned above refers to the thickness of the tread section on the tire equatorial plane in the tire radial cross section, and when the tread section is formed of a single rubber composition, the thickness of the rubber composition. In the case of a laminated structure of a plurality of rubber compositions described below, it refers to the total thickness of these layers.

When the tire has a groove on the equatorial plane, it refers to the thickness from the intersection of the tire equatorial plane with a straight line connecting the outermost end points of the groove in the tire radial direction to the innermost interface in the tire radial direction of the tread portion.

Note that the tread portion refers to a member in a region that forms the ground contact surface of the tire, and refers to a portion outside in the tire radial direction from members including fiber materials such as the carcass, belt layer, and belt reinforcing layer. The thickness of the tread portion described above can be measured by aligning the bead portion with the regular rim width in a cross section cut out of the tire in the radial direction.

In addition, "regular rim" is a rim specified for each tire by the standard in the standard system that includes the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it is specified in "JATMA YEAR BOOK". If it is a standard rim in the applicable size listed, ETRTO (The European Tire and Rim Technical Organization), "Measuring Rim" listed in "STANDARDS MANUAL", TRA (The Tire and Rim Association, Inc.) For example, it refers to "Design Rim" described in "YEAR BOOK", and refers to JATMA, ETRTO, and TRA in this order, and if there is an applicable size at the time of reference, that standard is followed. In the case of a tire that is not specified by the standard, the rim that can be assembled into a rim and that can maintain internal pressure, that is, the rim that does not cause air leakage between the rim and the tire, has the smallest diameter, and then the rim. Refers to the narrowest width.

As described above, in the tire according to the present invention, both the grip property on the tread surface and the heat generation property inside the tread part can be improved, so that the wet grip performance during high-speed running can be sufficiently improved. It is thought that it can be done.

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

1. Relationship between the glass transition temperature (Tg) of the cap rubber layer and 30°C tan δ When the cap rubber layer is formed using a rubber composition with a high glass transition temperature (Tg), the tread portion becomes hard near the running temperature. Therefore, the ability to follow the road surface may deteriorate. For this reason, it is possible to plasticize the surface of the tread portion during driving by providing sufficient heat generation properties relative to the glass transition temperature (Tg) of the rubber composition, thereby improving the ability to follow the road surface. preferable.

That is, in order to maintain wet grip performance during high-speed running, it is preferable that the glass transition temperature Tg (° C.) of the cap rubber layer and 30° C. tan δ satisfy a certain relationship. As a result of experiments and studies regarding this preferable relationship, the present inventor found that if the following formula is satisfied, the ability to follow the road surface is improved and wet grip performance can be preferably maintained during high-speed driving. .
30℃tanδ≧Tg×0.0036+0.4595

The above-mentioned glass transition temperature (Tg) of the rubber composition can be determined from the tan δ temperature distribution curve measured using a viscoelasticity measuring device such as the "Iplexer (registered trademark)" series manufactured by GABO. . Specifically, the temperature distribution curve of tan δ was measured under the conditions of a frequency of 10 Hz, an initial strain of 10%, an amplitude of ±0.5%, and a temperature increase rate of 2°C/min. As described above, the temperature corresponding to the largest tan δ value in the range of 40° C. or lower is defined as the glass transition temperature (Tg). Note that if there are two or more points with the highest tan δ value within the range of −60° C. or higher and 40° C. or lower, the point with the lowest temperature is taken as Tg. For example, in the present invention, if the tan δ peak is within the range of −60° C. or higher and 40° C. or lower, the peak temperature becomes the glass transition temperature (Tg) according to the above definition. Furthermore, for example, if a temperature distribution curve is obtained in which the peak of tan δ exists in a region below -60°C and tan δ gradually decreases as the temperature rises in the range from -60°C to 40°C, the above By definition, the glass transition temperature (Tg) is -60°C.

2. Relationship between the 30°C tan δ of the cap rubber layer and the thickness of the tread portion The present inventor has determined that the above-mentioned 30° C. tan δ of the cap rubber layer and the thickness (mm) of the tread portion are important for improving wet grip performance during high-speed running. We believed that there was a favorable relationship between the two, and conducted further experiments and studies. As a result, it was found that if (30° C. tan δ ÷ overall tread thickness) > 0.03 was satisfied, the wet grip performance during high-speed running was further improved.

In other words, due to this relationship, the 30°C tan δ of the cap rubber layer is made sufficiently high relative to the thickness of the tread portion, and the cap rubber layer is sufficient for the force transmission distance to the inside of the tire. It is thought that wet grip performance during high-speed driving will be further improved.

3. Modulus of the cap rubber layer Tires deform while in contact with the road surface while driving, but in areas where the amount of deformation is large, the rubber can tear due to wear, resulting in a rough and uneven tread surface. This may result in poor contact with the ground, leading to deterioration of wet grip performance.

The inventor conducted experiments and studies and found that in order to prevent the occurrence of such defects, the modulus at 300% elongation (M300: MPa) and the modulus at 100% elongation (M300: MPa) at 23°C of the cap rubber layer are If the ratio (M300/M100) of M100:MPa) is 3.8 or more, the rubber will be difficult to tear even in areas with large amounts of deformation, and wear resistance will improve, so the tread will remain stable even during high-speed running. It was found that the surface was less likely to become rough, ensuring stable ground contact, and further improving wet grip performance during high-speed driving. In addition, it is more preferable that it is 4.0 or more, and it is still more preferable that it is 4.2 or more.

4. Multi-layering of the tread portion In the present invention, the tread portion may be formed of only one layer of the cap rubber layer, or may be formed of two layers by providing a base rubber layer inside the cap rubber layer. , or may have three layers, or four or more layers. In this case, the thickness of the cap rubber layer over the entire tread portion is preferably 10% or more. As a result, even when driving at high speeds, it is possible to generate sufficient friction between the tread surface and the road surface and sufficiently transmit frictional force to the inside of the tire, further improving wet grip performance. can be done. In addition, in consideration of the occurrence of friction between the tread surface and the road surface, the thickness of the cap rubber layer is more preferably 70% or more.

As described above, the thickness of the cap rubber layer and the thickness of the base rubber layer can be calculated by summing 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 that the 30° C. tan δ of the base rubber layer be smaller than the 30° C. tan δ of the cap rubber layer. This makes it possible to reduce the phase difference between the wet grip performance generated by the cap rubber layer and the response inside the tire, improving responsiveness, resulting in excellent wet grip performance during high-speed driving. is considered to be obtained.

In the case of a multi-layered tread part, the complex elastic modulus of the base rubber layer measured at a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode: elongation is similarly measured. The complex modulus of elasticity of the cap rubber layer is preferably smaller than that of the cap rubber layer. Note that these complex moduli of elasticity can be measured, for example, using a viscoelasticity measuring device such as "Iprexor (registered trademark)" manufactured by GABO.

The complex modulus of elasticity 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 deforms from the inside when driving, and the road surface It is believed that this allows the tread surface to contact the ground almost uniformly, improving ground contact and providing excellent wet grip performance.

The tan δ at each temperature of the cap rubber layer and the base rubber layer can be adjusted as appropriate by the amount and type of compounding materials described below. For example, increasing the styrene content in the rubber component or increasing the SBR content in the rubber component It can be increased by 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. On the contrary, reduce the styrene content in the rubber component, reduce the SBR content in the rubber component, reduce the styrene content in the SBR component, reduce the content of fillers such as silica and carbon black, and reduce the content of fillers such as silica and carbon black. It is possible to lower the content by reducing the content.

5. Particle size of silica contained in cap rubber layer In the present invention, the particle size (average primary particle size) of silica contained in the cap rubber layer is 17 nm, considering ease of friction with the polymer described above. It is preferable that it is below.

The average primary particle diameter is determined by directly observing silica taken out from a rubber composition cut from a tire using an electron microscope (TEM), etc., and calculating the equal cross-sectional area diameter from the area of each silica particle obtained. It can be calculated by calculating and finding the average value.

6. Containment of Resin Component in Cap Rubber Layer In the present invention, it is preferable that the rubber composition forming the cap rubber layer contains a resin component.

It is thought that by containing the resin component in the rubber composition, wet grip on the road surface can be ensured due to the adhesiveness of the resin component even during high-speed running.

Preferred resin components include rosin resins, styrene resins, coumaron resins, terpene resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, which will be described later. Among these, α-methylstyrene, etc. More preferred are styrenic resins. The content per 100 parts by mass of the rubber component is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and even more preferably 35 parts by mass or more.

7. Acetone extract (AE) of cap rubber layer
In the present invention, the acetone extractable content (AE) of the cap rubber layer is preferably 19% by mass or more, and more preferably 21% by mass or more, from the viewpoint of exhibiting stable wet grip performance during high-speed running. It is preferably 23% by mass or more, and more preferably 23% by mass or more. On the other hand, the upper limit is not particularly limited, but is preferably 30% by mass or less, more preferably 27% by mass or less, and even more preferably 25% by mass or less.

Acetone extractables (AE) can be considered as an indicator of the amount of a softener or the like in a rubber composition, and can also be considered as an indicator of the softness of a rubber composition. For this reason, as mentioned above in the cap rubber layer, if the amount of AE is increased to a certain extent, it is possible to secure a sufficient area where the tire contacts the road surface and stably exhibit wet grip performance during high-speed driving. Conceivable.

Note that the acetone extractables (AE) can be measured in accordance with JIS K 6229:2015. Specifically, 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 reduction rate (%) of the test piece. .

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

Moreover, the acetone extract described above can be changed as appropriate by changing the blending ratio of the plasticizer in the rubber composition.

8. Land Ratio In the tire according to the present invention, the land ratio in the tread portion of the tire that is assembled into a regular rim and has a regular internal pressure 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 ground contact surface to the virtual ground contact surface that fills all the grooves arranged on the surface of the tread. If the land ratio is large, the area in contact with the road surface becomes large, so it is sufficient to It is thought that it is possible to stably obtain good wet grip performance.

Note that 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-mentioned land ratio can be determined from the ground contact shape under normal rim, normal internal pressure, and normal load conditions.

Specifically, the tire was assembled on a regular rim, the regular internal pressure was applied, and the tire was left to stand at 25°C for 24 hours.The tire tread surface was then painted with black ink, and the regular load was applied and the tire was pressed against cardboard (the camber angle was 0°). ), the ground contact shape can be obtained by transferring it to paper, so the tire is rotated by 72° in the circumferential direction and transferred at five locations. That is, the ground contact shape is obtained five times. At this time, for the five ground contact shapes, the interrupted portions of the contours of the ground contact shapes are smoothly connected by grooves, and the resulting shape is defined as a virtual ground contact surface.

The land ratio can be calculated from (average area of the five ground contact shapes (black portion) transferred to the cardboard/average area of the virtual contact surface obtained from the five ground contact shapes) x 100 (%). can.

In addition, "regular internal pressure" is the air pressure specified for each tire by the above standard, and for JATMA it is the maximum air pressure, for ETRTO it is "INFLATION PRESSURE", and for TRA it is the air pressure shown in the table "TIRE LOAD LIMITS AT VARIOUS COLD". JATMA, ETRTO, and TRA are referred to in that order, and the standards are followed, as in the case of the "regular rim." In the case of a tire that is not specified in the standard, it refers to the normal internal pressure (250 KPa or more) of another tire size (specified in the standard) in which the regular rim is described as a standard rim. In addition, when multiple normal internal pressures of 250 KPa or more are listed, it refers to the minimum value among them.

In addition, "regular load" is the load specified for each tire by each standard in the standard system, including the standards on which the above-mentioned tires are based, and refers to the maximum mass that is allowed to be loaded on the tire. For JATMA, it refers to the maximum load capacity, for ETRTO, it refers to "LOAD CAPACITY", for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and the above-mentioned "regular rim" and As in the case of "regular internal pressure", refer to JATMA, ETRTO, and TRA in that order and follow their standards. In the case of tires that are not specified by the standard, the normal load _WL is determined by the following calculation.
V={(Dt/2) ² - (Dt/2-Ht) ² }×π×Wt
W _L =0.000011×V+175
W _L : Regular load (kg)
V: Virtual volume of tire (mm ³ )
Dt: Tire outer diameter Dt (mm)
Ht: Tire cross-sectional height (mm)
Wt: Tire cross-sectional width (mm)

At this time, the ratio of the content (parts by mass) of styrene-butadiene rubber (SBR) having 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 (styrene content 25% by mass) When the SBR amount (mass parts)/land ratio (%) is 1.8 or less, the effects of the network of styrene domains work together to further improve wet grip performance. Note that the lower limit is not particularly limited, but is preferably 1.2 or more.

9. Oblateness As described later, the oblateness is the cross-sectional height of the tire relative to its cross-sectional width.The smaller this ratio is, the smaller the proportion of the portion that deforms in the width direction of the tire against the friction obtained in the tread, and the more force is exerted. It is thought that it will be easier to communicate. For this reason, stability and responsiveness are increased during high-speed driving, and the steering becomes sharper, which is thought to improve wet grip performance during high-speed driving. On the other hand, when the aspect ratio decreases, the amount of deflection at the side portions decreases, which may lead to deterioration in ride comfort.

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

In addition, the above-mentioned aspect ratio (%) is based on the cross-sectional height Ht (mm) of the tire, the cross-sectional width Wt (mm), the tire outer diameter Dt (mm), and the rim diameter R (mm) when the internal pressure is 250 kPa. It can be calculated using the following formula.
Oblateness (%) = (Ht/Wt) x 100 (%)
Ht=(Dt-R)/2

At this time, the ratio of the silica content (parts by mass) to the flatness (%) (silica content (parts by mass)/oblateness (%)) with respect to 100 parts by mass of the rubber component is 1.7 or more. If so, it is thought that the effects of the silica network work together to further improve wet grip performance. More preferably, it is 2.2 or more. The upper limit is not particularly limited, but is preferably 3.0 or less, more preferably 2.5 or less.

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

1. Rubber Composition In the tire according to the present invention, the rubber composition forming the cap rubber layer includes various compounding materials such as the rubber component, filler, softener, vulcanizing agent, and vulcanization accelerator described below. It can be obtained by adjusting the type and amount as appropriate.

(1) Compounded materials (a) Rubber component The rubber component is not particularly limited, and may include isoprene rubber, diene rubber such as butadiene rubber (BR), styrene butadiene rubber (SBR), nitrile rubber (NBR), butyl rubber, etc. Rubbers (polymers) commonly used in tire manufacturing can be used, such as thermoplastic elastomers such as butyl rubber, 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, the rubber component contains any one of styrene-based polymers such as SBR, SBS, and SB, and preferably contains SBR. Further, these styrene polymers may be used in combination with other rubber components. For example, it is preferable to use SBR and BR in combination, or to use SBR, BR, and isoprene rubber in combination.

(b) SBR
The weight average molecular weight of 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 SBR is, for example, more than 5% by mass and less than 70% by mass. Note that the vinyl content of SBR refers to the 1,2-bonded butadiene content relative to the entire butadiene moiety in the SBR component. Further, structural identification of SBR (measurement of styrene content and vinyl content) can be performed using, for example, a JNM-ECA series device manufactured by JEOL Ltd.

The content of SBR in 100 parts by mass of the rubber component is preferably 80 parts by mass or more, more preferably 85 parts by mass or more, and even more preferably 90 parts by mass or more.

The SBR is not particularly limited, and for example, emulsion polymerized styrene butadiene rubber (E-SBR), solution polymerized styrene butadiene rubber (S-SBR), etc. can be used. SBR may be either non-denatured SBR or modified SBR. Further, hydrogenated SBR obtained by hydrogenating the butadiene part in SBR may be used, and hydrogenated SBR may be obtained by subsequently hydrogenating the BR part in SBR, and styrene, ethylene, and butadiene can be hydrogenated. A similar structure may be obtained by copolymerization.

The modified SBR may be any SBR that has a functional group that interacts with a filler such as silica; for example, an end-modified SBR in which at least one end of the SBR is modified with a compound (modifier) having the above-mentioned functional group. SBR (terminally modified SBR having the above functional group at the end), main chain modified SBR having the above functional group in the main chain, main chain terminal modified SBR having the above functional group in the main chain and the end (e.g. The main chain end-modified SBR which has the above-mentioned functional group and has at least one end modified with the above-mentioned modifier, or is modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule, and has a hydroxyl group. and terminal-modified SBR into which an epoxy group has been introduced.

Examples of the above 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, and disulfide groups. group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group, etc. . Note that these functional groups may have a substituent.

Furthermore, as the modified SBR, for example, SBR modified with a compound (modifier) represented by the following formula can be used.

In the formula, R ¹ , R ² and R ³ are the same or different and each represents an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH) or a derivative thereof. represent. 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 combined to form a ring structure together with the nitrogen atom. n represents an integer.

The modified SBR modified with the compound (modifier) represented by the above formula includes a solution polymerized styrene butadiene rubber (S-SBR) whose polymerized end (active end) is modified with the compound represented by the above formula. SBR (modified SBR described in JP-A No. 2010-111753, etc.) can be used.

An alkoxy group is suitable as R ¹ , R ² and R ³ (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms). As R ⁴ and R ⁵ , an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is suitable. n is preferably 1 to 5, more preferably 2 to 4, and still more preferably 3. Furthermore, when R ⁴ and R ⁵ combine to form a ring structure together with a nitrogen atom, it is preferably a 4- to 8-membered ring. Note that the alkoxy group also includes a cycloalkoxy group (cyclohexyloxy group, etc.) and an aryloxy group (phenoxy group, benzyloxy group, etc.).

Specific examples of the above modifier include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltriethoxysilane, Examples include methoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. These may be used alone or in combination of two or more.

Furthermore, as the modified SBR, modified SBR modified with the following compound (modifier) can also be used. Examples of modifiers include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; two or more of diglycidylated bisphenol A, etc. Polyglycidyl ethers of aromatic compounds having phenol groups; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; 4,4'-diglycidyl-diphenyl Epoxy group-containing tertiary amines such as methylamine, 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl orthotoluidine, tetraglycidyl metaxylene diamine , diglycidylamino compounds such as tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; bis-(1-methylpropyl)carbamic acid chloride; Amino group-containing acid chlorides such as 4-morpholine carbonyl chloride, 1-pyrrolidine carbonyl chloride, N,N-dimethylcarbamate acid chloride, N,N-diethylcarbamate acid chloride; 1,3-bis-(glycidyloxypropyl)-tetra Epoxy group-containing silane compounds such as methyldisiloxane, (3-glycidyloxypropyl)-pentamethyldisiloxane; (trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl) propyl] sulfide, (trimethylsilyl) [3-(tripropoxysilyl) propyl] sulfide, (trimethylsilyl) [3-(tributoxysilyl) propyl] sulfide, (trimethylsilyl) [3-(methyldimethoxysilyl) propyl] sulfide, ( Sulfide groups such as (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide, etc. Containing silane compounds; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3- Alkoxysilanes such as aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, 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 substituted amino group such as bis(diphenylamino)benzophenone, N,N,N',N'-bis-(tetraethylamino)benzophenone; 4-N,N-dimethylamino Benzaldehyde compounds having an amino group and/or substituted amino group such as benzaldehyde, 4-N,N-diphenylaminobenzaldehyde, 4-N,N-divinylaminobenzaldehyde; N-methyl-2-pyrrolidone, N-vinyl-2- N-substituted pyrrolidone such as pyrrolidone, N-phenyl-2-pyrrolidone, N-t-butyl-2-pyrrolidone, N-methyl-5-methyl-2-pyrrolidone, N-methyl-2-piperidone, N-vinyl-2 - N-substituted piperidones such as piperidone, N-phenyl-2-piperidone; N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurirolactam, N-vinyl-ω-lau N-substituted lactams such as lilolactam, 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), tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-triones, N,N-diethyl Acetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl- 2-imidazolidinone, 4-N,N-dimethylaminoacetophene, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino) -4-heptanone and the like can be mentioned. Note that modification with the above compound (modifier) can be carried out by a known method.

As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., 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, BR may be further included if necessary. In this case, the content of BR in 100 parts by mass of the rubber component is preferably 10 parts by mass or more, more preferably 13 parts by mass or more. On the other hand, it is preferably 20 parts by mass or less, and more preferably less than 17 parts by mass.

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

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

As the BR, for example, products manufactured by Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

(c) Isoprene rubber The present invention may further contain isoprene rubber, if necessary. In this case, the content of the isoprene rubber in 100 parts by mass of the rubber component is preferably 10 parts by mass or more, more preferably 13 parts by mass or more. On the other hand, it is preferably 20 parts by mass or less, and more preferably less than 17 parts by mass.

Isoprene rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, and the like.

As the NR, for example, those commonly used in the tire industry, such as SIR20, RSS#3, and TSR20, can be used. The IR is not particularly limited, and for example, one commonly used in the tire industry, such as IR2200, can be used. Modified NR includes deproteinized natural rubber (DPNR), high purity natural rubber (UPNR), etc.; modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of the 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.

(d) Other rubber components In addition, other rubber components may include rubbers (polymers) commonly used in tire manufacturing such as nitrile rubber (NBR).

(b) Compounded materials other than rubber components (a) Filler In this embodiment, the rubber composition contains silica as a filler, but other fillers may include carbon black, graphite, It may also contain calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, and the like.

(i-1) Silica The BET specific surface area of 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 running, it is preferably less than 300 m ² /g, more preferably less than 250 m ² /g, and even more preferably less than 220 m ² /g. Note that the BET specific surface area described above is the value of N ₂ SA measured by the BET method according to ASTM D3037-93.

In the present invention, it is preferable to use silica with a particle size of 17 nm or less in the rubber composition forming the outer cap rubber layer, and by using silica with a small particle size, contact with the polymer (styrene domain) By increasing the frequency, wet grip performance during high-speed driving can be improved. Although the lower limit is not particularly limited, it is preferably 10 nm or more from the viewpoint of dispersibility during mixing.

The content of silica is 100 parts by mass or more based on 100 parts by mass of the rubber component. As described above, in consideration of the kneading processability and molding processability of the rubber composition, the amount is preferably 180 parts by mass or less, and more preferably 150 parts by mass or less.

Examples of the silica include dry process silica (anhydrous silica), wet process silica (hydrated silica), and the like. Among these, wet process silica is preferred because it has a large number of silanol groups. Furthermore, silica made from hydrous glass or the like, silica made from biomass materials such as rice husks, etc. may be used.

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

(i-2) Silane coupling agent In the present invention, the rubber composition forming the cap rubber layer 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-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3- Sulfide types such as triethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, mercapto types such as NXT and NXT-Z manufactured by Momentive, vinyltriethoxysilane, and vinyl triethoxysilane. Vinyl types such as methoxysilane, amino types such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane, and glycidoxy types such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. , 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, and other nitro types, and 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, and other chloro types. These may be used alone or in combination of two or more.

As the silane coupling agent, for example, products manufactured by Evonik Industries, Momentive, Shin-Etsu Silicone, Tokyo Kasei Kogyo, Azumax, Dow Corning Toray, etc. can be used.

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

(ii) Carbon black In the present invention, each rubber composition contains carbon black from the viewpoint of improving rigidity during high-speed running, improving responsiveness, and improving wet grip performance during high-speed running. It is preferable.

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

Carbon black is not particularly limited, and includes furnace black (furnace carbon black) 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; 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 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, more preferably 200 m ² /g or less. Note that the CTAB specific surface area is a value measured in accordance with ASTM D3765-92.

Specific carbon blacks are not particularly limited, and include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, and the like. Commercially available products include, for example, products from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Nippon Kaya Carbon Co., Ltd., and Columbia Carbon Co., Ltd. can be used. These may be used alone or in combination of two or more.

(iii) Other fillers In addition to the above-mentioned silica and carbon black, the rubber composition may optionally include fillers such as graphite, calcium carbonate, talc, alumina, etc., which are commonly used in the tire industry. It may further contain fillers such as clay, aluminum hydroxide, and mica. The content of these is, for example, more than 0.1 part by mass and less than 200 parts by mass based on 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, which soften the rubber. Note that the plasticizer component is a component that can be extracted from the vulcanized rubber with acetone. The total content of the plasticizer component is preferably 50 parts by mass or more, more preferably 55 parts by mass or more, based on 100 parts by mass of the rubber component. On the other hand, it is preferably 80 parts by mass or less, more preferably 75 parts by mass or less. Note that when oil-extended rubber is used as the rubber component, the amount of oil-extended oil is also included in the oil content.

(i) Oil Oils include, for example, mineral oils (generally referred to as process oils), vegetable oils, or mixtures thereof. As the mineral oil (process oil), for example, paraffinic process oil, aromatic process oil, naphthenic process oil, etc. can be used. 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, Examples include 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. Furthermore, from the viewpoint of life cycle assessment, waste oil that has been used as a lubricating oil for rubber mixing mixers, automobile engines, etc., waste cooking oil, etc. may be used as appropriate.

Specific process oils (mineral oils) include, for example, Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., and Showa Shell Sekiyu Co., Ltd. ), Fuji Kosan Co., Ltd., etc. can be used.

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

A farnesene-based polymer is a polymer obtained by polymerizing farnesene, and has a constituent unit based on farnesene. Farnesene includes 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 farnesene homopolymer (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

Examples of liquid diene-based polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), etc. It will be done.

The weight average molecular weight (Mw) of the liquid diene polymer measured by gel permeation chromatography (GPC) in terms of polystyrene is, 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 polystyrene equivalent value measured by gel permeation chromatography (GPC).

The content of liquid rubber (total content of liquid farnesene polymer, liquid diene polymer, etc.) is, for example, more than 1 part by mass and less than 100 parts by mass based on 100 parts by mass of the rubber component.

As the liquid rubber, for example, products manufactured by Kuraray Co., Ltd., Clay Valley Co., Ltd., etc. can be used.

(iii) Resin component The resin component also functions as a tackifying component and may be solid or liquid at room temperature. Specific resin components include rosin resin, styrene resin, etc. , coumarone resin, terpene resin, C5 resin, C9 resin, C5C9 resin, acrylic resin, etc., 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, and more preferably less than 30 parts by mass, based on 100 parts by mass of the rubber component. Note that these resin components may be provided with a modifying group capable of reacting with silica or the like, if necessary.

Rosin resin is a resin whose main component is rosin acid obtained by processing pine resin. This rosin-based resin (rosin) can be classified according to the presence or absence of modification, and can be classified into unmodified rosin (unmodified rosin) and modified rosin (rosin derivative). Examples of unmodified rosin include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. The modified rosin is a modified version of unmodified rosin, and includes rosin esters, unsaturated carboxylic acid-modified rosins, unsaturated carboxylic acid-modified rosin esters, amide compounds of rosin, and amine salts of rosin.

The styrene resin is a polymer using a styrene monomer as a constituent monomer, and includes polymers polymerized with a styrene monomer as a main component (50% by mass or more). Specifically, styrenic monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, Homopolymers of o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.), copolymers of two or more styrene monomers, and styrene monomers. and copolymers of other monomers that can be copolymerized therewith.

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

Among coumaron-based resins, coumaron indene resin is preferred. Coumarone indene resin is a resin containing coumaron and indene as monomer components constituting the skeleton (main chain) of the resin. In addition to coumaron and indene, monomer components contained in the skeleton include styrene, α-methylstyrene, methylindene, and vinyltoluene.

The content of the coumaron indene resin is, for example, more than 1.0 parts by mass and less than 50.0 parts by mass based on 100 parts by mass of the rubber component.

The hydroxyl value (OH value) of the coumaron 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 required to neutralize acetic acid bonded to hydroxyl groups when acetylating 1 g of resin, expressed in milligrams, and is determined by potentiometric titration method (JIS K 0070: (1992).

The softening point of the coumaron indene resin is, for example, higher than 30°C and lower 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 measuring device.

Examples of terpene resins include polyterpenes, terpene phenols, aromatic modified terpene resins, and the like. Polyterpenes are resins obtained by polymerizing terpene compounds and hydrogenated products thereof. Terpene compounds are hydrocarbons and their oxygen-containing derivatives represented by the composition (C ₅ H ₈ ) _n , including monoterpenes (C ₁₀ H ₁₆ ), sesquiterpenes (C ₁₅ H ₂₄ ), and diterpenes (C ₂₀ H _{32 )} . ) and other compounds whose basic skeletons are terpenes, such as α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, and terpinolene. , 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, and the like.

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 hydrogen obtained by hydrogenating the terpene resin. Also included are added terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the above-mentioned terpene compounds and phenolic compounds, and resins obtained by hydrogenating the above-mentioned resins. Examples include resin. Note that examples of the phenolic compound include phenol, bisphenol A, cresol, xylenol, and the like. Examples of aromatic modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the resins. The aromatic compound is not particularly limited as long as it has an aromatic ring, but examples include phenol compounds such as phenol, alkylphenol, alkoxyphenol, and unsaturated hydrocarbon group-containing phenol; naphthol, alkylnaphthol, alkoxynaphthol, Naphthol compounds such as unsaturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; coumaron, indene, and the like.

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

"C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a hydrogenated or modified resin. Examples of the C9 fraction include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. As specific examples, for example, coumaron indene resin, coumaron resin, indene resin, and aromatic vinyl resin are preferably used. As the aromatic vinyl resin, α-methylstyrene, a styrene homopolymer, or a copolymer of α-methylstyrene and styrene is preferred because it is economical, easy to process, and has excellent heat generation properties. , a copolymer of α-methylstyrene and styrene is more preferred. As the aromatic vinyl resin, for example, those commercially available from Clayton Co., Eastman Chemical Co., etc. can be used.

"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 the C5 fraction and C9 fraction include the petroleum fractions described above. As the C5C9 resin, for example, those commercially available from Tosoh Corporation, LUHUA, etc. can be used.

Although the acrylic resin is not particularly limited, for example, a solvent-free acrylic resin can be used.

Solvent-free acrylic resins are produced using a high-temperature continuous polymerization method (high-temperature continuous bulk polymerization method) (U.S. Patent No. 4,414,370), which uses as little as possible the use of auxiliary materials such as polymerization initiators, chain transfer agents, and organic solvents. specification, JP-A-59-6207, JP-A-5-58005, JP-A-1-313522, US Patent No. 5,010,166, Toagosei Research Annual Report TREND 2000 No. 3 p42 Examples include (meth)acrylic resins (polymers) synthesized by the method described in -45, etc. Note that in the present invention, (meth)acrylic means methacryl and acrylic.

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

In addition, as monomer components constituting the above acrylic resin, in addition to (meth)acrylic acid and (meth)acrylic acid derivatives, styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinylnaphthalene, etc. aromatic vinyl may be used.

The acrylic resin may be a resin composed only of a (meth)acrylic component, or a resin containing components other than the (meth)acrylic component. Further, the acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

Examples of resin components include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Co., Ltd., Nichiro Kagaku Co., Ltd. ) Products from Nippon Shokubai, ENEOS Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry 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 based on 100 parts by mass of the rubber component. As the stearic acid, conventionally known ones can be used, and for example, products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used.

(d) Anti-aging agent In the present invention, the rubber composition preferably contains an anti-aging agent. The content of the anti-aging agent is, for example, more than 0.5 parts by mass and less than 10 parts by mass, and more preferably 1 part by mass or more, based on 100 parts by mass of the rubber component.

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

As the anti-aging agent, for example, products manufactured by Seiko Kagaku Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Kagaku Kogyo Co., Ltd., Flexis Co., Ltd., etc. can be used.

(e) Wax In the present invention, the rubber composition preferably contains wax. The content of wax is, for example, 0.5 to 20 parts by weight, preferably 1.0 to 15 parts by weight, and more preferably 1.5 to 10 parts by weight, based on 100 parts by weight of the rubber component.

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

As the wax, for example, products manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., Seiko Kagaku 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 based on 100 parts by mass of the rubber component. As zinc oxide, conventionally known ones can be used, such as products from Mitsui Kinzoku Kogyo 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 based on 100 parts by mass of the rubber component.

Sulfur includes powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc. commonly used in the rubber industry. These may be used alone or in combination of two or more.

As the sulfur, for example, products manufactured by Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis, Nippon Karidome Kogyo Co., Ltd., Hosoi Chemical Co., Ltd., etc. can be used. .

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

Preferably, the rubber composition 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 based on 100 parts by mass of the rubber component.

Examples of vulcanization accelerators include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; tetramethylthiuram disulfide (TMTD); ), thiuram-based vulcanization accelerators such as tetrabenzylthiuram disulfide (TBzTD), tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); N-cyclohexyl-2-benzothiazolesulfenamide, N-t-butyl- Sulfenamide vulcanization accelerators such as 2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N,N'-diisopropyl-2-benzothiazolesulfenamide; diphenylguanidine; Examples include guanidine-based vulcanization accelerators such as di-ortho-tolyl guanidine and ortho-tolyl 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 contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, organic peroxides, and reversion (reversion). ) An inhibitor or the like may be further added as necessary. The content of these additives is, for example, more than 0.1 part by mass and less than 200 parts by mass based on 100 parts by mass of the rubber component.

(2) Preparation of rubber composition The rubber composition forming the cap rubber layer is prepared by appropriately adjusting the above-mentioned various compounding materials and kneading the rubber component and filler such as carbon black using a general method. It is produced by a manufacturing method including a base kneading step and a finishing kneading step of kneading the kneaded material obtained in the base kneading step and a crosslinking agent.

Kneading can be performed using a known (closed type) kneader 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 process, in addition to the above ingredients, compounding agents conventionally used in the rubber industry, such as softeners such as oil, zinc oxide, anti-aging agents, wax, and vulcanization accelerators, are added as necessary. , may be kneaded.

In the final kneading step, the kneaded material obtained in the base kneading step and a crosslinking agent are kneaded. 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, higher than 1 minute and shorter than 15 minutes. In the finishing kneading step, in addition to the above-mentioned components, a vulcanization accelerator, zinc oxide, etc. may be appropriately added and kneaded as necessary.

2. Manufacture of Tire The tire according to the present invention is produced by molding the rubber composition obtained above as a cap rubber layer into a tread rubber having a predetermined shape, and then molding the rubber composition along with other tire members on a tire molding machine using a normal method. By molding it, it is possible to produce an unvulcanized tire.

In addition, when making the tread part a multilayer structure with the base rubber layer, basically, by using the above-mentioned rubber components and compounding materials, changing the compounding amounts appropriately, and kneading in the same manner. , a rubber composition forming a base rubber layer can be obtained. Then, after extruding it together with the cap rubber layer and molding it into a tread rubber of a predetermined shape, it can be manufactured as an unvulcanized tire by molding it together with other tire components using a normal method on a tire molding machine. .

Specifically, on the forming drum, there is an inner liner as a member to ensure airtightness of the tire, a carcass as a member to withstand the load, impact, and filling air pressure that the tire receives, and a carcass that is tightly tightened to increase the rigidity of the tread. After winding a belt member as a lifting member, fixing both ends of the carcass to both side edges, and arranging a bead part as a member for fixing the tire to the rim, forming it into a toroid shape, An unvulcanized tire is produced by laminating a tread in the center and a sidewall on the outside in the radial direction to form a side part.

Thereafter, a tire is obtained by heating and pressurizing the produced unvulcanized tire in a vulcanizer. The vulcanization process can be carried out by applying known vulcanization means. The vulcanization temperature is, for example, more than 120°C and less than 200°C, and the vulcanization time is, for example, more than 5 minutes and less than 15 minutes.

The tires according to the present invention are not particularly limited in category, and include tires for passenger cars, tires for large passenger cars, tires for large SUVs, tires for trucks and buses, tires for motorcycles, tires for competitions, and studless tires (winter tires). It can be used as an all-season tire, a run-flat tire, an aircraft tire, a mining tire, a non-pneumatic tire, etc., but it is preferably used as a passenger car tire. Moreover, it is preferable to use a pneumatic tire.

In the following, examples (examples) that are considered preferable for implementation will be shown, but the scope of the present invention is not limited to these examples. In the examples, a pneumatic tire (tire size 205/55R16, flatness: 55%, land ratio: 65%) was manufactured from a composition obtained by changing the formulation according to each table using the various chemicals shown below. ) and calculated based on the following evaluation method are shown in Tables 2 and 3.

1. Production of rubber composition forming cap rubber layer (1) Compounding materials (a) Rubber component (a) NR: TSR20
(b) 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: SLR6430 (S-SBR) manufactured by Trinseo
(Styrene content: 40% by mass, vinyl content: 24% by mass)
(d) SBR-3: HPR840 (S-SBR) manufactured by JSR Corporation
(Styrene content: 10% by mass, vinyl content: 42% 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)

(Manufacture of SBR-1)
The above SBR-1 is produced 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 head, equipped with a stirrer and a jacket were connected in series as reactors, and butadiene, styrene, and cyclohexane were mixed in a predetermined ratio. do. This mixed solution is passed through a dehydration column packed with activated alumina, 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 were continuously supplied from the bottom of the first reactor at a predetermined rate, and the internal temperature of the reactor was brought to 95%. Keep at ℃. The polymer solution is continuously extracted from the head of the reactor and supplied to the second reactor. The temperature of the second reactor was maintained at 95°C, and a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane (monomer) as a modifier and the oligomer component was diluted 1000 times with cyclohexane at a predetermined rate. The denaturation reaction is carried out by continuously adding as follows. This polymer solution is continuously extracted from the reactor, an antioxidant is continuously added using a static mixer, and then the solvent is removed to obtain the desired modified diene polymer (SBR-1).

The vinyl content (unit: mass %) of the SBR-1 was determined from the absorption intensity near 910 cm ⁻¹ , which is the absorption peak of vinyl groups, by infrared spectroscopy. Moreover, the amount of styrene (unit: mass %) is determined from the refractive index according to JIS K6383 (1995).

(b) Compounding materials other than rubber components (a) Carbon black: Showblack N134 manufactured by Cabot Japan Co., Ltd.
(CTAB specific surface area: 135m ² /g)
(b) Silica: Ultrasil VN3 manufactured by Evonik Industries
(N ₂ SA: 175 m ² /g)
(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: Diana Process AH-24 (aroma oil) manufactured by Idemitsu Kosan Co., Ltd.
(F) Zinc oxide: Type 2 zinc oxide manufactured by Mitsui Mining & Mining Co., Ltd. (G) Anti-aging agent-1: 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
(li) Wax: Sunnock N manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
(nu) Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. (contains 5% oil)
(l) Vulcanization accelerator: Noxeler CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
(N-cyclohexyl-2-benzothiazylsulfenamide (CBS))

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

Next, sulfur and a vulcanization accelerator are added to the kneaded product, and kneaded using open rolls at 80° C. for 5 minutes to obtain a rubber composition for forming a cap rubber layer.

2. Rubber Composition Forming the Base Rubber Layer In parallel, a rubber composition forming the base rubber layer was prepared based on the formulation shown in Table 1 in the same manner as in the production of the rubber composition forming the cap rubber layer. A rubber composition forming a layer is obtained.

3. Manufacture of pneumatic tires Using each rubber composition, (thickness of cap rubber layer/thickness of base rubber layer) = 90/10, the tread is extruded into a predetermined shape with the total thickness shown in Tables 2 and 3. Manufacture parts.

Thereafter, an unvulcanized tire was formed by bonding it together with other tire members, and press vulcanization was performed for 10 minutes at 170°C. Comparative Examples 1 to 5 (test tires) shown in Table 3 are manufactured.

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

(1) 30℃ tan δ
A rubber test piece for measuring viscoelasticity was prepared by cutting out a piece measuring 20 mm long x 4 mm wide x 2 mm thick from the cap rubber layer of the tread of each test tire, with the long side in the tire circumferential direction. Regarding the rubber test piece, the tan δ at 30° C. is measured using the Iplexer series manufactured by GABO under the conditions of a temperature of 30° C., a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain of 1%, with the deformation mode being tensile. Note that the thickness direction of the sample is the tire radial direction. Further, the 30°C tan δ of the base rubber layer is set to 0.07.

(2) Tg
A rubber test piece for measuring viscoelasticity cut out in the same manner from the cap rubber layer was measured using "Iplexer (registered trademark)" manufactured by GABO at a frequency of 10 Hz, an initial strain of 2%, an amplitude of ±1%, and a temperature increase rate of 2. Under the condition of ℃/min, tan δ is measured while changing the temperature from -60 ℃ to 40 ℃, and the temperature (℃) corresponding to the largest tan δ value in the obtained temperature distribution curve is determined as Tg, and further, (Tg×0.0036+0.4595) is calculated.

(3) M300/M100
A No. 7 dumbbell-shaped test piece with a thickness of 1 mm was prepared from a sample taken from the cap rubber layer of each test tire, and a tensile test was conducted at 23°C in accordance with JIS K6251:2010 to determine 100% elongation. The modulus at time (M100: MPa) and the modulus at 300% extension (M300: MPa) are measured, and (M300/M100) is calculated.

(4) Complex modulus of elasticity Rubber test pieces for viscoelasticity measurement prepared by cutting out the cap rubber layer in the same manner were measured at a temperature of 30°C, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain using the Iplexer series manufactured by GABO. The complex modulus of elasticity (MPa) is measured under the condition of 1% in deformation mode: elongation. Note that the complex modulus of the base rubber layer is 12.0 MPa.

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

(6) (SBR content/land ratio), (Silica content/oblateness)
In addition, based on the specifications of each test tire and the formulation content, the content (parts by mass) of styrene-butadiene rubber (SBR) with an amount of styrene of 25% by mass or less in 100 parts by mass of the rubber component and the land in the tread part. Calculate the ratio (SBR content/land ratio) to the ratio (%) and the ratio of the silica content (parts by mass) to 100 parts by mass of the rubber component and the flatness (%) (silica content/flatness) .

5. Performance evaluation test (evaluation of wet grip performance during high-speed driving)
Each test tire was attached to all wheels of a vehicle (domestic front-wheel drive vehicle, displacement 2000cc), filled with air to an internal pressure of 250kPa (regular internal pressure for passenger cars), and then placed on a wet test course. The vehicle was driven at a speed of 100 km/h, and each of the 20 drivers sensory-evaluated the grip performance (wet grip performance) while driving on a five-point scale (the higher the value, the better). Then, the total score of the evaluations by the 20 drivers is calculated.

Next, the result in Example 1 is set as 100, and the result is expressed as an index based on the formula below to evaluate the wet grip performance during high-speed driving on a wet road surface. The larger the value, the better the wet grip performance during high-speed driving.
Wet grip performance during high speed driving
= [(Results of test tire)/(Results of Example 1)] x 100

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

The present invention (1) is
A tire including a tread portion,
The cap rubber layer forming the tread portion is
Containing styrene butadiene rubber (SBR) having a styrene content of 25% by mass or less in 100 parts by mass of the rubber component, and containing 80 parts by mass or more and 100 parts by mass or less,
Containing 100 parts by mass or more of silica with respect to 100 parts by mass of the rubber component,
Formed from a rubber composition whose loss tangent (30°C tan δ) measured under the conditions of temperature 30°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1% in tensile mode is more than 0.20. and
The tire is characterized in that the thickness of the tread portion is 10 mm or more and 20 mm or less.

The present invention (2) is
The tire according to the present invention (1) is characterized in that the amount of styrene in the styrene-butadiene rubber (SBR) is 20% by mass or less.

The present invention (3) is
The tire according to the present invention (2) is characterized in that the amount of styrene in the styrene-butadiene rubber (SBR) is 15% by mass or less.

The present invention (4) is
The tire is characterized in that the content of the silica based on 100 parts by mass of the rubber component is 120 parts by mass or more, and is in any combination with any one of the present inventions (1) to (3).

The present invention (5) is
The tire according to the present invention (4), wherein the content of the silica based on 100 parts by mass of the rubber component is 130 parts by mass or more.

The present invention (6) is
The tire is characterized in that the 30° C. tan δ is 0.30 or more, and is any combination of the present invention (1) to (5).

The present invention (7) is
The tire according to the present invention (6) is characterized in that the 30°C tan δ is 0.45 or more.

The present invention (8) is
A tire of any combination with any one of the present invention (1) to (7), characterized in that the glass transition temperature (Tg) of the cap rubber layer and the 30°C tan δ satisfy the following formula. be.
30℃tanδ≧Tg×0.0036+0.4595

The present invention (9) is
A tire of any combination with any one of the present invention (1) to (8), characterized in that the 30°C tan δ of the cap rubber layer and the thickness (mm) of the entire tread portion satisfy the following formula: It is.
30℃ tan δ ÷ total tread thickness > 0.03

The present invention (10) is
The ratio (M300/M100) of the modulus at 300% elongation (M300: MPa) to the modulus at 100% elongation (M100: MPa) at 23° C. of the cap rubber layer is 3.8 or more. , a tire in any combination with any one of the present inventions (1) to (9).

The present invention (11) is
The tire according to the present invention (10) is characterized in that (M300/M100) is 4.0 or more.

The present invention (12) is
The tread portion is formed of a cap rubber layer forming an outermost layer and a base rubber layer forming an inner layer,
A tire according to any combination of the present invention (1) to (11), characterized in that the thickness of the cap rubber layer is 10% or more and less than 100% of the total thickness of the tread portion. It is.

The present invention (13) is
The land ratio in the tread portion is 55% or more,
, 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 part (SBR with a styrene content of 25% by mass or less) The tire is characterized in that the amount (parts by mass)/land ratio (%)) is 1.8 or less, and is any combination of the present invention (1) to (12).

The present invention (14) is
The flatness is 30% or more and 60% or less,
The ratio of the content of silica (parts by mass) to 100 parts by mass of the rubber component and the oblateness (%) (silica content (parts by mass)/oblateness (%)) is 1.7 or more. This is a tire in any combination with any one of the present inventions (1) to (13).

Claims (14)

A tire including a tread portion,
The cap rubber layer forming the tread portion is
Containing styrene butadiene rubber (SBR) having a styrene content of 25% by mass or less in 100 parts by mass of the rubber component, and containing 80 parts by mass or more and 100 parts by mass or less,
Containing 100 parts by mass or more of silica with respect to 100 parts by mass of the rubber component,
Formed from a rubber composition whose loss tangent (30°C tan δ) measured under the conditions of temperature 30°C, frequency 10Hz, initial strain 5%, and dynamic strain rate 1% in tensile mode is more than 0.20. and
A tire characterized in that the thickness of the tread portion is 10 mm or more and 20 mm or less. The tire according to claim 1, wherein the styrene content in the styrene-butadiene rubber (SBR) is 20% by mass or less. The tire according to claim 2, wherein the styrene content in the styrene-butadiene rubber (SBR) is 15% by mass or less. The tire according to any one of claims 1 to 3, wherein the content of the silica based on 100 parts by mass of the rubber component is 120 parts by mass or more. The tire according to claim 4, wherein the content of the silica based on 100 parts by mass of the rubber component is 130 parts by mass or more. The tire according to any one of claims 1 to 5, wherein the 30°C tan δ is 0.30 or more. The tire according to claim 6, wherein the 30°C tan δ is 0.45 or more. The tire according to any one of claims 1 to 7, wherein the glass transition temperature (Tg) of the cap rubber layer and the 30°C tan δ satisfy the following formula.
30℃tanδ≧Tg×0.0036+0.4595 The tire according to any one of claims 1 to 8, wherein the 30°C tan δ of the cap rubber layer and the thickness (mm) of the entire tread portion satisfy the following formula.
30℃ tan δ ÷ total tread thickness > 0.03 The ratio (M300/M100) of the modulus at 300% elongation (M300: MPa) to the modulus at 100% elongation (M100: MPa) at 23° C. of the cap rubber layer is 3.8 or more. The tire according to any one of claims 1 to 9. The tire according to claim 10, wherein the (M300/M100) is 4.0 or more. The tread portion is formed from a cap rubber layer forming an outermost layer and a base rubber layer forming an inner layer,
The tire according to any one of claims 1 to 11, wherein the thickness of the cap rubber layer is 10% or more and less than 100% of the total thickness of the tread portion. The land ratio in the tread portion is 55% or more,
, 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 part (SBR with a styrene content of 25% by mass or less) The tire according to any one of claims 1 to 12, wherein the amount (parts by mass)/land ratio (%) is 1.8 or less. The flatness is 30% or more and 60% or less,
The ratio of the content of silica (parts by mass) to 100 parts by mass of the rubber component and the oblateness (%) (silica content (parts by mass)/oblateness (%)) is 1.7 or more. The tire according to any one of claims 1 to 13.