Tire

Abstract

The wear-resistant tire solves the problem of improving the wear resistance of the tire in the high-speed driving process. The tire includes a tread portion in which: a crown rubber layer forming the tread portion includes at least 80 parts by mass of a styrene-butadiene rubber (SBR) having a styrene content of 25 mass% or less in 100 parts by mass of a rubber component, and includes 100 parts by mass or less of silica with respect to 100 parts by mass of the rubber component; and the crown rubber layer is formed from a rubber composition having a complex elastic modulus (30 DEG C E *) of 8.0 MPa or less as measured in a tensile deformation mode under the conditions of a temperature of 30 DEG C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%; the thickness of the tread portion is 9.0 mm or less.

Description

Technical Field

[0001] The present invention relates to tires. Background Art

[0002] In a tire mounted on a vehicle, as the vehicle travels, the tread portion in contact with the ground wears, and when the wear limit is exceeded, the risk of an accident increases. For this reason, various techniques have been proposed to improve wear resistance (eg, Patent Documents 1 to 4).

[0003] [Prior art literature]

[0004] [Patent Document]

[0005] [Patent Document 1] JP 2018-135412 A

[0006] [Patent Document 2] JP 2018-135500 A

[0007] [Patent Document 3] JP 2019-182982 A

[0008] [Patent Document 4] JP 2021-088676 A Summary of the invention

[0009] [Problems to be solved by the invention]

[0010] However, with the construction of expressways in recent years, the opportunity of high-speed long-distance driving has increased significantly. Under these circumstances, it cannot be said that the wear resistance of the tire manufactured based on the above-mentioned prior art during high-speed driving is still sufficient, and further improvement is urgently needed.

[0011] Therefore, an object of the present invention is to improve the wear resistance of a tire during high-speed running.

[0012] [Methods used to solve the problem]

[0013] The present invention is a tire having a tread portion, wherein:

[0014] The cap rubber layer forming the tread portion contains 80 parts by mass or more of styrene-butadiene rubber (SBR) having a styrene content of 25% by mass or less per 100 parts by mass of the rubber component, and contains 100 parts by mass or less of silica per 100 parts by mass of the rubber component; and

[0015] The crown rubber layer is formed of a rubber composition having a complex elastic modulus (30°C E*) of 8.0 MPa or less measured in a tensile deformation mode at a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5% and a dynamic strain rate of 1%; and

[0016] The tread portion has a thickness of 9.0 mm or less.

[0017] [Effects of the Invention]

[0018] According to the present invention, the wear resistance of the tire during high-speed running can be improved. DETAILED DESCRIPTION

[0019] [1] Features of the tire of the present invention

[0020] First, the features of the tire of the present invention will be described.

[0021] 1. Overview

[0022] The tire of the present invention includes a carcass that is built between one and the other of a pair of bead portions that fit with a wheel rim and serves as a skeleton of the tire; a belt layer that is radially arranged on the carcass; a belt reinforcement layer that is radially arranged on the belt layer; and a tread portion that is radially arranged on these layers. The tread portion includes a crown rubber layer that is radially arranged on the tire and serves as a ground contact surface, and a base rubber layer that is radially arranged on the crown rubber layer, if necessary.

[0023] The crown rubber layer forming the tread portion is formed of a rubber composition, the rubber composition containing 80 parts by mass or more of SBR having a styrene content of 25% or less in 100 parts by mass of the rubber component, and containing 100 parts by mass or less of silica relative to 100 parts by mass of the rubber component. The complex elastic modulus (30°C E*) of the crown rubber layer of the rubber composition measured at a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain rate of 1% and a tensile deformation mode is 8.0 MPa or less. The thickness of the tread portion is 9.0 mm or less.

[0024] The cap rubber layer described herein is not limited to the rubber layer forming the outermost layer of the tread portion, and in the case where two or more layers exist within 5 mm inward from the tread surface, at least one of the layers must satisfy the requirements of the rubber composition.

[0025] As mentioned above, these features can improve the wear resistance of the tire when traveling at high speeds.

[0026] 2. Mechanism of the Effect of the Tire of the Present Invention

[0027] It is believed that the mechanism by which the above-mentioned effects are exhibited in the tire of the present invention is as follows.

[0028] As described above, the crown rubber layer of the tire of the present invention is formed of a rubber composition containing 80 parts by mass or more of SBR having a styrene content of 25% by mass or less per 100 parts by mass of the rubber component, and containing 100 parts by mass or less of silica relative to 100 parts by mass of the rubber component.

[0029] SBR with a low styrene content (specifically 25% by mass or less) has a lower glass transition temperature (Tg). Therefore, by accounting for more than 80 parts by mass in 100 parts by mass of the rubber component and forming the main part of the crown rubber layer, the Tg of the rubber composition as a whole can be reduced, the fluidity of the polymer can be improved, and the flexibility of the rubber can be maintained. This improves road compliance, inhibits the occurrence of slippage, and improves wear resistance during high-speed driving.

[0030] In addition, the small amount of styrene in SBR forms tiny styrene areas in the rubber matrix, which makes it easier to reduce the shear force generated between the tread and the road surface. In addition, the styrene part can increase the modulus of the tread against large deformations and improve the wear resistance during high-speed driving.

[0031] In the crown rubber layer of the tire of the present invention, the content of silica is less than 100 parts by mass relative to 100 parts by mass of the rubber component, that is, it does not exceed the content of the rubber component. This makes it easier to evenly disperse silica in the rubber matrix, homogenize the rubber composition, improve road compliance, and improve wear resistance during high-speed driving. In addition, since a silica network is easily formed in the rubber matrix, the rubber can be effectively reinforced and the wear resistance during high-speed driving can be improved.

[0032] In the present invention, the rubber composition forming the cap rubber layer has a complex elastic modulus (30°C E*) of 8.0 MPa or less measured at a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain rate of 1% and a tensile deformation mode.

[0033] The complex elastic modulus is a parameter indicating the rigidity of the rubber layer. By setting 30°C E* to 8.0 MPa or less, the rubber becomes soft as a whole. Therefore, from a macroscopic perspective, it is possible to provide sufficient road compliance, suppress slippage with the road surface, and improve wear resistance during high-speed driving.

[0034] Furthermore, in the tire of the present invention, the thickness of the tread portion is reduced to 9.0 mm or less. This suppresses the plasticization of the rubber that occurs as the temperature of the rubber increases due to the accumulation of heat generated between the tread portion and the road surface, and sufficiently suppresses the reduction in the strength of the rubber, thereby improving the wear resistance during high-speed running. Furthermore, the degree of deformation applied to the rubber can be reduced, thereby improving the wear resistance during high-speed running.

[0035] As described above, in the tire of the present invention, it is believed that the effects of improving road compliance, reducing the shear force generated between the tread and the road surface, improving the modulus of rubber, reinforcing rubber, suppressing slippage with the road surface (from a macroscopic perspective), and suppressing the reduction in rubber strength all work together to provide sufficiently improved wear resistance during high-speed driving.

[0036] In the present invention, the styrene content is preferably 20% by mass or less, more preferably 15% by mass or less, and the lower limit is preferably 3% by mass or more, more preferably 5% by mass or more, and further preferably 8% by mass or more.

[0037] The phrase "containing 80 parts by mass or more of SBR having a styrene content of 25% 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 80 parts by mass or more and the amount of styrene in the entire SBR is 25% by mass or less.

[0038] In other words, when the rubber component contains only one styrene-containing polymer (SBR), this indicates that the styrene amount is 25% by mass or less; when the rubber component contains multiple styrene-containing polymers (SBR), this indicates that the styrene amount calculated by the sum of the products of the styrene amount (mass %) in each polymer and the mixing amount (mass parts) of the polymer in every 100 parts by mass of the rubber component is 25% by mass or less.

[0039] More specifically, when SBR1 (X1 parts by mass) having a styrene amount of S1% by mass and SBR2 (X2 parts by mass) having a styrene amount of S2% by mass are contained per 100 parts by mass of the rubber component, the amount of styrene calculated by the formula {(S1×X1)+(S2×X2)} / (X1+X2) is 25% by mass or less.

[0040] Furthermore, in the vulcanized rubber composition, the content of styrene can also be calculated by measuring the content of styrene contained in the rubber composition after acetone extraction using solid-state nuclear magnetic resonance (solid-state NMR) or Fourier transform infrared spectrometer (FTIR).

[0041] In the present invention, the content of SBR in 100 parts by mass of the rubber component is more preferably 85 parts by mass or more, and further preferably 90 parts by mass or more.

[0042] The content of silica is more preferably 98 parts by mass or less relative to 100 parts by mass of the rubber component.

[0043] In the present invention, 30°C E *It is more preferably 7.6 MPa or less, further preferably 7.5 MPa or less, further preferably 7.4 MPa or less, further preferably 7.3 MPa or less, further preferably 7.0 MPa or less, and further preferably 6.8 MPa or less. The lower limit is not particularly limited, but is preferably 5.0 MPa or more, more preferably 5.5 MPa or more, and further preferably 6.0 MPa or more.

[0044] Here, the “complex elastic modulus” can be measured using a viscoelasticity measuring device (for example, “Eplexor (registered trademark)” manufactured by GABO Corporation).

[0045] Furthermore, in the present invention, the thickness of the tread portion is more preferably 8.5 mm or less. The lower limit is preferably 7.5 mm or more, and more preferably 8.0 mm or more.

[0046] Here, "the thickness of the tread portion" refers to the thickness of the tread portion on the tire equatorial plane in the radial cross section of the tire. When the tread portion is formed by a single rubber composition, it is the thickness of the rubber composition. When the tread portion is formed by a laminated structure of multiple rubber compositions described later, it is the total thickness of these layers. When the tire has grooves on the equatorial plane, it refers to the thickness from the intersection of the straight line connecting the outermost end points of the grooves in the tire diameter direction and the tire equatorial plane to the innermost interface of the tread portion in the tire diameter direction. The tread portion is a component of the area forming the ground contact surface of the tire, and refers to the part on the outside of the components (such as carcass, belt layer and belt reinforcement layer) containing fiber materials in the tire diameter direction. The thickness of the tread portion can be measured by adjusting the bead portion to the standardized rim width in the cross section cut out in the tire radial direction.

[0047] In the above, the "standardized rim" is a rim specified for each tire in the standard system including the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it is a standard rim of applicable size described in the "JATMA YEAR BOOK"; in the case of ETRTO (The European Tire and Rim Technical Organization), it is a "Measuring Rim" described in the "STANDARDS MANUAL"; in the case of TRA (The Tire and Rim Association, Inc.), it is a "Design Rim" described in the "YEARBOOK". JATMA, ETRTO, and TRA are referenced in sequence, and if there is an applicable size when referencing, the standard is followed. In the case of tires not specified in the standard, it refers to a rim that can be assembled and maintain internal pressure (i.e., a rim that does not cause air leakage from between the rim and the tire) and has the smallest rim diameter and the narrowest rim width.

[0048] [2] More preferred embodiments of the tire of the present invention

[0049] The tire of the present invention can achieve better effects by adopting the following aspects.

[0050] 1. Loss tangent of crown rubber layer (tanδ)

[0051] Loss tangent tan δ is a viscoelastic parameter indicating energy absorption performance. The larger the value, the more energy can be absorbed and converted into heat. There is a concern that it may cause heat generation in the rubber, which may cause deformation and reduce wear resistance.

[0052] For this reason, in the present invention, the loss tangent (30°C tanδ) of the rubber composition forming the crown rubber layer measured in a tensile deformation mode 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% is preferably 0.26 or less, more preferably 0.25 or less, further preferably 0.23 or less, further preferably 0.21 or less, and further preferably 0.20 or less. The lower limit is not particularly limited, but is preferably 0.15 or more, more preferably 0.17 or more, and further preferably 0.19 or more.

[0053] In this way, by setting the upper limit of tan δ at 30° C. close to room temperature to 0.25, heat generation in the tread portion can be suppressed, and it is believed that deformation of the rubber can be suppressed even during high-temperature running, thereby improving wear resistance.

[0054] In the above, the loss tangent (tan δ) can be measured using a viscoelasticity measuring device (for example, “Eplexor (registered trademark)” manufactured by GABO).

[0055] 2. Modulus of the crown rubber layer

[0056] When tires come into contact with the road surface, they deform as they travel. When the amount of deformation becomes large, such as when traveling at high speeds, the rubber may wear and tear due to friction, which may cause deterioration in wear resistance.

[0057] As a result of research to prevent these problems from occurring, the inventors of the present invention have concluded that when the modulus (M100) of the crown rubber layer at 100% elongation at 23°C is 2.3 MPa or more, more preferably 2.4 MPa or more, further preferably 2.5 MPa or more, further preferably 2.6 MPa or more, and further preferably 2.7 MPa or more, the rubber is not easily torn even if the amount of deformation increases, and the wear resistance during high-speed running can be improved. The upper limit of M100 is preferably 3.0 MPa or less, and more preferably 2.8 MPa or less.

[0058] 3. Isoprene rubber content

[0059] In the present invention, the rubber component of the rubber composition forming the cap rubber layer preferably contains an isoprene-based rubber, which provides better reinforcing properties and can further improve wear resistance during high-speed running.

[0060] The content of the isoprene-based rubber in 100 parts by mass of the rubber component is preferably 1 part by mass or more and 9 parts by mass or less, and more preferably 3 parts by mass or more and 7 parts by mass or less.

[0061] 4.Multi-layer tread

[0062] In the present invention, the tread portion may be formed of only one layer of the crown rubber layer, or may be formed of two layers by arranging the base rubber layer inside the crown rubber layer, or may be formed of three layers, or may be formed of four or more layers. In this case, the thickness of the crown rubber layer is preferably 10% or more in the entire tread portion. This can suppress the slip between the surface of the tread portion and the road surface even during high-speed running, thereby further improving the wear resistance. The thickness is more preferably 70% or more.

[0063] As described above, in the case of a laminated structure of multiple rubber compositions, the "thickness of the tread portion" refers to the total thickness of the laminated layers. In the case of a tire having grooves on the equatorial plane of the tire, the "thickness of the tread portion" refers to the thickness from the intersection of the straight line connecting the outermost end points of the grooves in the tire radial direction and the equatorial plane of the tire to the innermost interface of the tread portion in the tire radial direction.

[0064] In this case, it is preferred that the base rubber layer has a 30°C E * and 30℃tanδ is less than 30℃E of the crown rubber layer * and tanδ at 30℃.

[0065] 5. Particle size of silica contained in the crown rubber layer

[0066] In the present invention, from the viewpoint of improving the reinforcing property, the particle diameter (average primary particle diameter) of silica contained in the cap rubber layer is preferably 17 nm or less.

[0067] The average primary particle size can be calculated by directly observing silica particles extracted from a rubber composition cut out from a tire using a transmission electron microscope (TEM) or the like, calculating an equivalent cross-sectional diameter from the area of ​​each silica particle obtained, and calculating an average value.

[0068] 6. Acetone extract of the crown rubber layer (AE)

[0069] In the present invention, the acetone extract (AE) of the crown rubber layer is preferably 15.1% by mass or more, more preferably 16% by mass or more, further preferably 18% by mass or more, further preferably 18.1% by mass or more, further preferably 19.4% by mass or more, and further preferably 20% by mass or more. On the other hand, although there is no specific upper limit, it is preferably 24% by mass or less, more preferably 23% by mass or less, further preferably 22% by mass or less, and further preferably 21.3% by mass or less.

[0070] The acetone extract (AE) can be regarded as an indicator showing the softener content in the rubber composition, and can also be regarded as an indicator showing the flexibility of the rubber composition. Therefore, by controlling the amount of AE in the crown rubber layer as described above, the crown rubber layer can be appropriately deformed and can contact the ground more flexibly on the road surface, so the wear resistance during high-speed driving can be further improved.

[0071] The acetone extract (AE) can be measured in accordance with JIS K 6229: 2015. Specifically, a vulcanized rubber specimen cut out from a measurement site is immersed in acetone for a certain period of time and the mass loss rate (%) of the specimen is measured, thereby obtaining AE (mass %).

[0072] More specifically, each vulcanized rubber specimen was immersed in acetone at room temperature and normal pressure for 72 hours to extract soluble components, the mass of each specimen before and after the extraction was measured, and AE could be calculated according to the following formula.

[0073] Acetone extract (%) = {(mass of rubber sample before extraction - mass of rubber sample after extraction) / mass of rubber sample before extraction} × 100

[0074] The acetone extract content can be appropriately changed by changing the compounding ratio of the plasticizer in the rubber composition.

[0075] 7. Landing rate

[0076] In the tire of the present invention, it is preferred that the ground contact ratio of the tread portion of the tire mounted on a standardized rim and having a standardized internal pressure is 40% or more.

[0077] The "land ratio" is the ratio of the actual contact area to the hypothetical contact area that would fill all the grooves on the tread surface. By setting the land ratio to 40% or more, the contact area with the road surface becomes larger, so that wear resistance during high-speed driving can be stably obtained. On the other hand, it is preferable to set the land ratio to 95% or less. This allows sand and soil to fully enter the grooves of the tread.

[0078] In addition, the product 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 and the ground contact rate (%) of the tread portion is preferably 9000 or less, more preferably 8500 or less, and further preferably 7000 or less. The lower limit is not particularly limited, but is, for example, 4000 or more. This allows the effect of the network of styrene regions to work together, thereby further improving the wear resistance during high-speed running.

[0079] The ground contact ratio can be determined from the ground contact shape under standardized rim, standardized internal pressure and standardized load conditions.

[0080] Specifically, the tire is mounted on a standardized wheel hub, a standardized internal pressure is applied, and the tire is left at rest at 25°C for 24 hours. Then, the ink is applied to the tire tread surface, a standardized load is applied and pressed on a cardboard (camber angle is 0°), and the contact shape is transferred to the cardboard. The tire is rotated 72° in the circumferential direction, and the contact shape is transferred to 5 places. That is, 5 contact shapes are obtained. At this time, the 5 contact shapes are smoothly connected at the part interrupted by the groove in the outline of the contact shape, and the obtained shape is called a virtual contact surface.

[0081] The contact rate can be calculated as follows: (average area of ​​5 contact shapes (black parts) transferred to the cardboard / average area of ​​the virtual contact surface obtained from the 5 contact shapes)×100 (%).

[0082] "Standard internal pressure" refers to the air pressure specified for each tire in the above standards. In the case of JATMA, it refers to the maximum air pressure; in the case of ETRTO, it refers to the "INFLATION PRESSURE" table; in the case of TRA, it refers to the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLDINFLATION PRESSURES" table. As in the case of "standardized rim", it refers to referring to JATMA, ETRTO and TRA in sequence and following these standards. In the case of a tire not specified in the standard, it refers to the standardized internal pressure (above 250 KPa) of another tire size (specified in the standard) that specifies the standardized rim as a standard rim. In the case where multiple standard internal pressures of 250 KPa or more are specified, it refers to the minimum value among them.

[0083] The "standardized load" is a load specified for each tire by each standard in the standard system including the standards 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 "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table. As in the case of the above-mentioned "standardized rim" and "standard internal pressure", refer to JATMA, ETRTO and TRA in sequence and follow their standards. In the case of a tire not specified by the standard, the standardized load W is calculated as follows L .

[0084] V = {(Dt / 2) 2 -(Dt / 2-Ht) 2}×π×Wt

[0085] W L＝ 0.000011×V+175

[0086] W L :Standardized load (kg)

[0087] V: Imaginary volume of the tire (mm 3 )

[0088] Dt: Tire outer diameter Dt (mm)

[0089] Ht: Tire section height (mm)

[0090] Wt: tire section width (mm)

[0091] 8. Flatness

[0092] The aspect ratio refers to the ratio of the cross-sectional height to the cross-sectional width of the tire, and the smaller the ratio, the larger the ground contact area can be ensured, and more sand can enter and be discharged from the tread portion, thereby improving the wear resistance during high-speed driving. In the present invention, the specific aspect ratio is preferably 80% or less.

[0093] The product of the content (parts by mass) of silica relative to 100 parts by mass of the rubber component and the flatness (%) is preferably 7500 or less, more preferably 7000 or less, further preferably 6500 or less, and further preferably 4410 or less. The lower limit is not particularly limited, but is, for example, 1000 or more. This allows the effect of the silica network to work together, thereby further improving the wear resistance during high-speed running.

[0094] The above aspect ratio (%) can be calculated by the following formula using the tire section height Ht (mm), tire section width Wt (mm), tire outer diameter Dt (mm) and rim radius R (mm) when the internal pressure is 250 kPa.

[0095] Flatness (%) = (Ht / Wt) × 100 (%)

[0096] Ht=(Dt-R) / 2

[0097] [3] Implementation Method

[0098] Hereinafter, the present invention will be described in detail according to embodiments.

[0099] 1. Rubber composition

[0100] In the tire of the present invention, the rubber composition forming the cap rubber layer can be obtained by appropriately adjusting the kinds and contents of various compounding materials (eg, rubber component, filler, plasticizer, vulcanizing agent and vulcanization accelerator described below).

[0101] (1) Mixed materials

[0102] (a) Rubber component

[0103] The rubber component is not particularly limited, and rubbers (polymers) commonly used for producing tires, such as isoprene-based rubbers, 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 copolymers (SBS) and styrene-butadiene block copolymers (SB)) can be used.

[0104] In the present invention, among these materials, from the perspective of including styrene in the rubber component, it is preferred to include any one of styrene polymers (e.g., SBR, SBS, and SB), and preferably include SBR. In addition, these styrene polymers are used in combination with other rubber components, for example, a combination of SBR and BR, or a combination of SBR, BR, and isoprene rubber is preferred.

[0105] (i) SBR

[0106] The weight average molecular weight of SBR is, for example, greater 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 less than 25% by mass. The vinyl content (1,2-bonded butadiene content) of SBR is, for example, greater than 5% by mass and less than 70% by mass. The vinyl content of SBR refers to the 1,2-bonded butadiene content relative to the total butadiene part in the SBR component. The structural identification of SBR (the determination of the amount of styrene and the vinyl content) can be carried out using, for example, the JNM-ECA series equipment manufactured by JEOL.

[0107] In the present invention, as described above, the SBR content in 100 parts by mass of the rubber component is 80 parts by mass or more, more preferably 85 parts by mass or more, and further preferably 90 parts by mass or more.

[0108] SBR is not particularly limited, and for example, emulsion polymerization styrene-butadiene rubber (E-SBR), solution polymerization styrene-butadiene rubber (S-SBR) etc. can be used. SBR can be unmodified SBR or modified SBR. In addition, hydrogenated SBR obtained by hydrogenating the butadiene part of SBR. Hydrogenated SBR can be obtained by subsequently hydrogenating the BR part of SBR, or a similar structure can be obtained by copolymerizing styrene, ethylene and butadiene.

[0109] The modified SBR may be any SBR having a functional group that interacts with a filler (e.g., silica), and examples thereof include a terminal-modified SBR in which at least one end of the SBR is modified with a compound (modifier) ​​having a functional group (terminal-modified SBR having a functional group at the terminal); a main chain-modified SBR having a functional group in the main chain; a main chain-terminal-modified SBR having a functional group in the main chain and at least one terminal (e.g., an SBR having a functional group in the main chain and at least one terminal modified by a modifier); and a terminal-modified SBR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and into which a hydroxyl group or an epoxy group is introduced.

[0110] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a thioether group, a disulfide group, a sulfone group, a sulfoxide group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, etc. These functional groups may have a substituent.

[0111] As the modified SBR, for example, SBR modified with a compound (modifier) ​​represented by the following formula can be used.

[0112]

[0113] In the formula, R 1 , R 2 and R 3 are the same or different and represent an alkyl group, an alkoxy group, a silyl group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH) or a derivative thereof. 4 and R 5 are the same or different and represent a hydrogen atom or an alkyl group. 4 and R 5 May bond to form a ring structure together with the nitrogen atom. "n" represents an integer.

[0114] As the SBR modified with the compound (modifier) ​​represented by the above formula, SBR whose polymerization end (active end) of solution-polymerized styrene-butadiene rubber (S-SBR) has been modified with the compound represented by the above formula (for example, modified SBR described in JP-A-2010-111753) can be used.

[0115] R 1 , R 2 and R 3 Preferably it is an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). 4 and R 5It is preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). "n" is preferably 1 to 5, more preferably 2 to 4, and further preferably 3. 4 and R 5 When combined to form a ring structure together with a nitrogen atom, a 4- to 8-membered ring is preferred. The alkoxy group also includes a cycloalkoxy group (cyclohexyloxy group, etc.) and an aryloxy group (phenoxy group, benzyloxy group, etc.).

[0116] Specific examples of the modifier include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane and 3-diethylaminopropyltriethoxysilane. These can be used alone or in combination of two or more.

[0117] As the modified SBR, a modified SBR modified by the following compounds (modifiers) can also be used. Examples of the modifier include: polyglycidyl ethers of polyols, such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenolic groups, such as diglycidyl bisphenol A; polyepoxides, such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; tertiary amines containing epoxy groups, such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylamino compounds, such as diglycidyl Oleyl aniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl o-toluidine, tetraglycidyl m-phenylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides, such as bis(1-methylpropyl)carbamoyl chloride, 4-morpholinylphosgene, 1-pyrrolidinylphosgene, N,N-dimethylcarbamoyl chloride and N,N-diethylcarbamoyl chloride; epoxy group-containing silane compounds, such as 1,3-bis-(glycidyloxypropyl)-tetramethyl Silane compounds containing thioether groups, such as (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, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, ] sulfide, (trimethylsilyl) [3- (methyldipropoxysilyl) propyl] sulfide and (trimethylsilyl) [3- (methyldibutoxysilyl) propyl] sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; alkoxysilanes such as methyltriethoxysilane, N,N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane, N,N-bis (trimethylsilyl) -3-aminopropyltriethoxysilane, N,N-bis (trimethylsilyl) aminoethyltrimethoxysilane and N,N-bis (trimethylsilyl) aminoethyltriethoxysilane;(Thio)benzophenone compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-tert-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone and N,N,N',N'-bis-(tetraethylamino)benzophenone; (thio)benzophenone compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-tert-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone and N,N,N',N'-bis-(tetraethylamino)benzophenone; N-substituted benzaldehyde compounds, such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde and 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones, such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone and N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidones, such as N-methyl-2-piperidone, N-vinyl-2- piperidone and N-phenyl-2-piperidone; lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurolactam, N-vinyl-ω-laurolactam, N-methyl-β-propiolactam and N-phenyl-β-propiolactam; and 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-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone, etc. The modification using the above compounds (modifiers) can be carried out by known methods. ;

[0118] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., ENEOS Materials Co., Ltd., Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used. The SBR can be used alone or in combination of two or more.

[0119] (ii) BR

[0120] In the present invention, the rubber composition may contain BR as required. In this case, the BR content 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, and preferably 20 parts by mass or less, more preferably less than 17 parts by mass.

[0121] The weight average molecular weight of BR is, for example, greater than 100,000 and less than 2,000,000. The vinyl content of BR is, for example, greater than 1% by mass and less than 30% by mass. The cis content of BR is, for example, greater than 1% by mass and less than 98% by mass. The trans content of BR is, for example, greater than 1% by mass and less than 60% by mass.

[0122] BR is not particularly limited, and may be BR with a high cis content (90% or more cis content), BR with a low cis content, or BR containing syndiotactic polybutadiene crystals. BR may be unmodified or modified, and the modified BR may be a modified BR having the above-mentioned functional groups introduced therein. These may be used alone or in combination of two or more. The cis content may be measured by infrared absorption spectroscopy.

[0123] As BR, for example, products of Ube Industries, Ltd., ENEOS Materials Co., Ltd., Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0124] (iii) Isoprene rubber

[0125] In the present invention, the rubber composition may contain isoprene rubber as required. In this case, the content of the isoprene rubber in 100 parts by mass of the rubber component is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and preferably 20 parts by mass or less, more preferably less than 10 parts by mass.

[0126] Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR.

[0127] As NR, for example, SIR20, RSS#3, TSR20, SVR-L, etc., which are generally used in the tire industry, can be used. As IR, there is no particular limitation, and for example, IR2200, which is generally used in the tire industry, etc. can be used. As modified NR, deproteinized natural rubber (DPNR), high purity natural rubber (UPNR), etc. can be mentioned; as modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. can be mentioned; as modified IR, epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. can be mentioned. These can be used alone or in combination of two or more.

[0128] (iv) Other rubber components

[0129] Furthermore, as other rubber components, a rubber (polymer) generally used for manufacturing tires, such as nitrile rubber (NBR), may be contained.

[0130] (b) Compounding materials other than rubber components

[0131] (i) Filling

[0132] In the present invention, as described above, the rubber composition contains silica as a filler, but may contain other fillers. Specific examples of fillers other than silica include carbon black, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica.

[0133] (i-1) Silicon dioxide

[0134] In the present invention, as described above, the content of silica is 100 parts by mass or less, and more preferably 98 parts by mass or less, relative to 100 parts by mass of the rubber component. The lower limit is preferably 85 parts by mass or more, more preferably 90 parts by mass or more, and further preferably 95 parts by mass or more.

[0135] In the present invention, from the viewpoint of obtaining good durability performance, the BET specific surface area of ​​silica contained in the rubber composition is preferably greater than 140 m 2 / g, more preferably greater than 160m 2 / g, and more preferably greater than 180m 2 On the other hand, from the perspective of obtaining good rolling resistance during high-speed running, it is preferably less than 300 m 2 / g. The BET specific surface area is the value of N2 SA measured by the BET method according to ASTM D3037-93.

[0136] In the present invention, as described above, for the rubber composition forming the outer crown rubber layer, it is preferred to use silica having a particle size of 17 nm or less, and by using silica having a smaller particle size, the contact frequency with the polymer (styrene region) can be increased, thereby improving the reinforcing properties. The lower limit is not particularly limited, but from the perspective of dispersibility during mixing, it is preferably 10 nm or more.

[0137] Examples of silicon dioxide include dry silicon dioxide (anhydrous silicon dioxide) and wet silicon dioxide (hydrated silicon dioxide). Among them, wet silicon dioxide is preferred because it has a large number of silanol groups. In addition, silicon dioxide made from hydrated glass or silicon dioxide made from biomass materials (such as rice husks) can also be used.

[0138] As silica, for example, products available from Evonik Industries, Rhodia Corporation, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Co., Ltd., and the like can be used.

[0139] (i-2) Silane coupling agent

[0140] The rubber composition forming the cap rubber layer of the present invention preferably contains a silane coupling agent together with silica.

[0141] The silane coupling agent is not particularly limited. Specific examples of the silane coupling agent include sulfide-based silane coupling agents such as 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)tetrasulfide, 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-dimethylthiocarbamoyl 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z manufactured by Momentive; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino Silane coupling agents of the group consisting of amino-based silane coupling agents such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chlorine-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These may be used alone or in combination of two or more.

[0142] As the silane coupling agent, for example, products available from Evonik Industries, Momentive Corporation, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., AZmax Co., Ltd., Dow Corning Toray Corporation, etc. can be used.

[0143] The content of the silane coupling agent is, for example, greater than 3 parts by mass and less than 25 parts by mass relative to 100 parts by mass of silica.

[0144] (i-3) Carbon black

[0145] In the present invention, the rubber composition preferably contains carbon black from the viewpoint of reinforcement.

[0146] The specific content ratio of carbon black is preferably greater than 5 parts by mass, and more preferably greater than 15 parts by mass, while it is preferably less than 30 parts by mass, and more preferably less than 25 parts by mass, relative to 100 parts by mass of the rubber component.

[0147] Carbon black is not particularly limited, and examples thereof include furnace blacks (furnace blacks), such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black (acetylene carbon black); thermal blacks (thermal blacks), such as FT and MT; and channel blacks (channel blacks), such as EPC, MPC, and CC. These may be used alone or in combination of two or more.

[0148] The CTAB specific surface area (cetyltrimethylammonium bromide) of carbon black is preferably 130 m 2 / g or more, more preferably 160m 2 / g or more, and more preferably 170 m 2 / g or more, on the other hand, it is preferably 250m 2 / g or less, and more preferably 200m 2 The CTAB specific surface area is a value measured according to ASTM D3765-92.

[0149] Specific carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include, for example, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Tanso Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Nippon Steel Carbon Co., Ltd., Columbia Carbon Co., Ltd., etc. These may be used alone or in combination of two or more.

[0150] (i-4) Other fillers

[0151] In addition to the above-mentioned silica and carbon black, the rubber composition may contain fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc., as required. The content of these fillers is, for example, greater than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0152] (ii) Plasticizer component

[0153] Rubber composition can comprise oil (comprising filler oil), liquid rubber and resin as the plasticizer component of softening rubber.Plasticizer component is the component that can be extracted with acetone from vulcanized rubber.Relative to the rubber component of 100 mass parts, the total content of plasticizer component is preferably more than 45 mass parts, more preferably more than 55 mass parts, and further preferably more than 65 mass parts.On the other hand, it is preferably less than 80 mass parts, more preferably less than 75 mass parts, and further preferably less than 70 mass parts.When rubber component is oil-filled rubber component, the amount of filler oil is included in oil content.

[0154] (ii-1) Oil

[0155] The example of oil includes mineral oil (commonly referred to as process oil), vegetable oil and mixture thereof. As mineral oil (process oil), paraffinic process oil, aromatic process oil, cycloparaffinic process oil etc. can be used. The example of vegetable oil includes 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 seed oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil and tung oil. These can be used alone or in combination of two or more. From the perspective of life cycle analysis, waste oil, waste cooking oil etc. used as the lubricant in rubber mixer and automobile engine can be used as suitable material.

[0156] Examples of the process oil (mineral oil) include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., OLISOY Co., Ltd., H&R Co., Ltd., Toyokuni Oil Manufacturing Co., Ltd., Showa Shell Sekiyu Co., Ltd., Fuji Kosan Co., Ltd., and the like.

[0157] (ii-2) Liquid rubber

[0158] The liquid rubber mentioned as the plasticizer is a polymer which is liquid at room temperature (25°C) and is a rubber component which can be extracted with acetone from a vulcanized tire. Examples of the liquid rubber include farnesene polymers, liquid diene polymers and hydrogenated products thereof.

[0159] Farnesene polymers are polymers obtained by polymerizing farnesene and have a farnesene-based structural unit. Farnesene includes isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodetetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene).

[0160] 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).

[0161] Examples of the liquid diene-based polymer include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), and the like.

[0162] The weight average molecular weight (Mw) of the liquid diene polymer measured by gel permeation chromatography (GPC) in terms of polystyrene is, for example, greater 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).

[0163] The content of the liquid rubber (the total content of the liquid farnesene polymer, the liquid diene polymer, etc.) relative to 100 parts by mass of the rubber component is, for example, more than 1 part by mass and less than 100 parts by mass.

[0164] As the liquid rubber, for example, products of Kuraray Co., Ltd. and Cray Valley Corporation can be used.

[0165] (ii-3) Resin component

[0166] The resin component also acts as a tackifier and can be solid or liquid at room temperature. Specific examples of the resin component include resins such as rosin resins, styrene resins, coumarone resins, terpene resins, C5 resins, C9 resins, C5C9 resins, acrylic resins, and two or more thereof can also be used in combination. Relative to 100 parts by mass of the rubber component, the content of the resin component is preferably greater than 2 parts by mass and less than 45 parts by mass. The resin component may have a modified group capable of reacting with silica or the like as required.

[0167] Rosin resin is a resin whose main component is rosin acid obtained by processing rosin. These rosin resins (rosins) can be classified according to whether they are modified, and can be classified into unmodified rosin (non-modified rosin) and modified rosin (rosin derivative). The example of unmodified rosin includes tall oil rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, other chemically modified rosins, etc. Modified rosin is a modified substance of unmodified rosin, and the example of such modified rosin includes rosin ester, unsaturated carboxylic acid modified rosin, unsaturated carboxylic acid modified rosin ester, rosin amide compound and rosin amine salt.

[0168] The styrene resin is a polymer using a styrene monomer as a constituent monomer, and examples thereof include polymers obtained by polymerizing a styrene monomer as a main component (50% by mass or more), etc. Specifically, it includes homopolymers obtained by polymerizing a styrene monomer (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) alone, copolymers obtained by copolymerizing two or more styrene monomers, and further, copolymers obtained by copolymerizing a styrene monomer with other monomers copolymerizable with the styrene monomer.

[0169] Examples of other monomers include acrylonitriles such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate; dienes such as chloroprene, butadiene and isoprene; olefins such as 1-butene and 1-pentene; and α,β-unsaturated carboxylic acids and anhydrides thereof such as maleic anhydride and the like.

[0170] As the benzofuran resin, benzofuran-indene resin is preferably used. Benzene-indene resin is a resin containing benzofuran and indene as monomer components constituting the backbone (main chain) of the resin. Examples of monomer components other than benzofuran and indene contained in the backbone include styrene, α-methylstyrene, methylindene and vinyltoluene, etc.

[0171] The content of the coumarone-based resin is, for example, greater than 1.0 part by mass and less than 50.0 parts by mass relative to 100 parts by mass of the rubber component.

[0172] The hydroxyl value (OH value) of the coumarone-indene resin is, for example, greater 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 the hydroxyl group when 1 g of the resin is acetylated, and is expressed in milligrams. It is a value measured by potentiometric titration (JIS K 0070: 1992).

[0173] The softening point of the coumarone-indene resin is, for example, higher than 30° C. and lower than 160° C. The softening point is a temperature at which a ball falls when the softening point specified in JIS K 6220-1:2001 is measured by a ring and ball softening point measuring apparatus.

[0174] Examples of terpene resins include polyterpene, terpene phenol, and aromatic modified terpene resins. Polyterpene is a resin obtained by polymerizing a terpene compound and its hydrogenate. A terpene compound is a terpene having (C5H8) n A hydrocarbon or an oxygen-containing derivative thereof, which is classified as a monoterpene (C 10 H 16), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ) as a basic skeleton. Examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0175] Examples of polyterpenes include terpene resins made from the above-mentioned terpene compounds, such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin and β-pinene / limonene resin, and hydrogenated terpene resins obtained by hydrogenating the terpene resin. 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 formed by condensing the above-mentioned terpene compounds, phenolic compounds and formaldehyde. Examples of phenolic compounds include phenol, bisphenol A, cresol and xylenol, etc. Examples of aromatic modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the above-mentioned resins. The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring, and examples thereof include phenol compounds such as phenol, alkylphenol, alkoxyphenol and phenol containing an unsaturated hydrocarbon group; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol and naphthol containing an unsaturated hydrocarbon group; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene and styrene containing an unsaturated hydrocarbon group; benzofuran; and indene.

[0176] C5 resin refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions having 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. As the C5-based petroleum resin, dicyclopentadiene resin (DCPD resin) is preferably used.

[0177] C9 resin refers to a resin obtained by polymerizing a C9 fraction, and it can be hydrogenated or modified. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyl toluene, alkyl styrene, indene, methyl indene. As a specific example, it is preferred to use, for example, benzofuran-indene resin, benzofuran resin, indene resin and aromatic vinyl resin. As aromatic vinyl resin, preferably α-methylstyrene or a homopolymer of styrene or a copolymer of α-methylstyrene and styrene, because it is economical, easy to process and excellent in terms of heat generation. More preferably, a copolymer of α-methylstyrene and styrene. As aromatic vinyl resin, aromatic vinyl resins such as those commercially available from Clayton Company, Eastman Chemical Company, etc. can be used.

[0178] C5C9 resin refers to a resin obtained by copolymerizing the above-mentioned C5 fraction and the above-mentioned C9 fraction, and it may be hydrogenated or modified. Examples of C5 fraction and C9 fraction include the above-mentioned petroleum fraction. As C5C9 resin, for example, resins commercially available from Tosoh Corporation, LUHUA Corporation, etc. may be used.

[0179] The acrylic resin is not particularly limited, but for example, a solvent-free type acrylic resin may be used.

[0180] As the solvent-free acrylic resin, there can be mentioned a (meth)acrylic resin (polymer) synthesized by a high temperature continuous polymerization method (high temperature continuous bulk polymerization method, which is a method described in US 4414370 B, JP 84-6207A, JP 93-58805B, JP 89-313522A, US 5010166 B, ToaSynthetic Research Annual Report TREND2000 No.3p42-45, etc.), and a polymerization initiator, a chain transfer agent, an organic solvent, etc. are not used as auxiliary raw materials as much as possible. In the present invention, (meth)acrylic acid refers to methacrylic acid and acrylic acid.

[0181] Examples of monomer components constituting the acrylic resin include (meth)acrylic acid and (meth)acrylic acid derivatives such as (meth)acrylic acid esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, (meth)acrylamide derivatives, and the like.

[0182] In addition, as a monomer component constituting the above acrylic resin, an aromatic vinyl compound such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinylnaphthalene may be used together with (meth)acrylic acid or a (meth)acrylic acid derivative.

[0183] The acrylic resin may be a resin composed of only a (meth)acrylic component or a resin further having a component other than the (meth)acrylic component. In addition, the acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

[0184] As the resin component, for example, products of Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF Corporation, Arizona Chemical Co., Ltd., Nippon Paint Chemicals Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Co., Ltd., Arakawa Chemical Industries, Ltd., Taoka Chemical Industries, Ltd., etc. can be used.

[0185] (iii) Stearic acid

[0186] In the present invention, the rubber composition preferably contains stearic acid. For every 100 parts by mass of the rubber component, the content of stearic acid is, for example, greater than 0.5 parts by mass and less than 10.0 parts by mass. As stearic acid, conventionally known products can be used. For example, products such as NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Co., Ltd., Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used.

[0187] (iv) Anti-aging agents

[0188] In the present invention, the rubber composition preferably contains an anti-aging agent. The content of the anti-aging agent is, for example, greater 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.

[0189] Examples of anti-aging agents include naphthylamine anti-aging agents, such as phenyl-α-naphthylamine; diphenylamine anti-aging agents, such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine 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 anti-aging agents, such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol anti-aging agents, such as 2,6-di-tert-butyl-4-methylphenol, styrenated phenol; bisphenol, triphenol, polyphenol anti-aging agents, such as tetrakis-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane. These can be used alone or in combination of two or more.

[0190] As the anti-aging agent, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flexis Corporation, etc. can be used.

[0191] (v) Wax

[0192] In the present invention, the rubber composition preferably contains wax. The content of the wax is, for example, 0.5 to 20 parts by mass, preferably 1.0 to 15 parts by mass, and more preferably 1.5 to 10 parts by mass per 100 parts by mass of the rubber component.

[0193] 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, synthetic waxes such as polymers of ethylene, propylene, etc. These may be used alone or in combination of two or more.

[0194] As the wax, products available from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., and the like can be used.

[0195] (vi) Zinc oxide

[0196] The rubber composition may contain zinc oxide. The content of zinc oxide is, for example, greater than 0.5 parts by mass and less than 10 parts by mass relative to 100 parts by mass of the rubber component. As zinc oxide, conventionally known products can be used, for example, products of Mitsui Mining and Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0197] (vii) Cross-linking agents and vulcanization accelerators

[0198] The rubber composition preferably contains a crosslinking agent (such as sulfur). The content of the crosslinking agent is, for example, greater than 0.1 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0199] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are generally used in the rubber industry. These may be used alone or in combination of two or more.

[0200] As sulfur, products available from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanryu Industry Co., Ltd., Hosoi Chemical Industry Co., Ltd., and the like can be used.

[0201] Crosslinking agents other than sulfur include vulcanizing agents containing sulfur atoms, such as Tackirol V200 manufactured by Taoka Chemical Industry Co., Ltd. and KA9188 (1,6-bis(N,N′-dibenzylthiocarbamoyldisulfide)hexane) manufactured by LANXESS, and organic peroxides such as dicumyl peroxide.

[0202] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator is, for example, greater than 0.3 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0203] Examples of the vulcanization accelerator include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazolyl sulfenamide; thiuram vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, N-ethylene oxide-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine vulcanization accelerators such as diphenylguanidine, di-o-tolylguanidine, and o-tolylbiguanide. These may be used alone or in combination of two or more.

[0204] (viii) Others

[0205] In addition to the above 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, reversion inhibitors, etc. The content of these additives is, for example, greater than 0.1 parts by mass and less than 50 parts by mass per 100 parts by mass of the rubber component.

[0206] (2) Preparation of rubber composition

[0207] The rubber composition forming the crown rubber layer is prepared by appropriately adjusting the various mixing materials mentioned above and using conventional methods, for example, a manufacturing method including the following steps: a basic mixing step of mixing the rubber component with a filler (such as carbon black), and a refined mixing step of mixing the mixed product obtained in the basic mixing step with a cross-linking agent.

[0208] The kneading can be carried out using a known (closed type) mixer such as a Banbury mixer, a kneader or an open roll mill.

[0209] The mixing temperature in the basic mixing step is, for example, greater than 50° C. and less than 200° C., and the mixing time is, for example, greater than 30 seconds and less than 30 minutes. In the basic mixing step, in addition to the above components, compounding agents commonly used in the rubber industry, such as softeners (e.g., oils), zinc oxide, anti-aging agents, waxes, vulcanization accelerators, etc., may be appropriately added as needed and mixed.

[0210] In the refining and kneading step, the kneaded product obtained in the basic kneading step is kneaded with a crosslinking agent. The kneading temperature in the refining and kneading step is, for example, greater than room temperature and less than 80° C., and the kneading time is, for example, greater than 1 minute and less than 15 minutes. In the refining and kneading step, in addition to the above components, a vulcanization accelerator, zinc oxide, etc. may be appropriately added as needed and kneaded.

[0211] 2. Tire manufacturing

[0212] The tire of the present embodiment can be manufactured as an unvulcanized tire by molding the rubber composition obtained as described above into a tread rubber of a predetermined shape as a cap rubber layer, and then molding it together with other tire components on a tire molding machine in a conventional manner.

[0213] In the case where the tread portion has a multilayer structure provided with a base rubber layer, the rubber composition for forming the base rubber layer can be obtained by kneading the above-mentioned rubber component and compounding materials in the same manner while appropriately changing the compounding amount. Then, the rubber composition for forming the base rubber layer is extruded together with the crown rubber layer to form a tread rubber of a predetermined shape, and then molded on a tire molding machine in a conventional manner together with other tire components to produce an unvulcanized tire.

[0214] Specifically, the inner liner as a component for ensuring the airtightness of the tire, the carcass as a component for bearing the load, impact and filling pressure of the tire, and the belt layer component as a component for clamping the carcass to increase the rigidity of the tread are wound on the forming drum, and the two ends of the carcass are fixed to the edges on both sides, and the bead part as a component for fixing the tire on the rim is arranged and formed into a ring shape. Then, the tread is attached to the central part of the outer circumference, and the sidewall is attached to the radially outer side to form the side portion, thereby producing an unvulcanized tire.

[0215] Then, the unvulcanized tire thus produced is heated and pressurized in a vulcanizer to obtain a tire. The vulcanization step can be performed by applying known vulcanization means. 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.

[0216] As described above, the resulting tire enhances the fluidity of the polymer, which makes it easier to relieve the shear force generated between the tread portion and the road surface, and provides sufficient reinforcement for the rubber. In addition, from a macroscopic perspective, it fully suppresses the slippage with the road surface, and fully suppresses the deterioration of the rubber strength. Therefore, these effects work together to fully improve the wear resistance during high-speed driving.

[0217] The tire of the present invention is not particularly limited in type and can be used as a passenger car tire, a heavy-duty vehicle (such as a truck and bus) tire, a two-wheel vehicle tire, a run-flat tire, a non-pneumatic tire, etc., but is preferably used as a passenger car tire. In addition, it is preferably a pneumatic tire.

[0218] [Example]

[0219] Examples (embodiments) considered to be preferred in the practice of the present invention are shown below, but the scope of the present invention is not limited to these examples. In the examples, pneumatic tires (tire size 225 / 45R17, aspect ratio: 45%) made from compositions obtained by changing the formulations according to the tables using various chemicals were examined, and the results calculated based on the following evaluation method are shown in Tables 2 and 3.

[0220] 1. Rubber composition for forming a crown rubber layer

[0221] (1) Mixed materials

[0222] (a) Rubber component

[0223] (i) SBR-1: Modified S-SBR obtained by the method shown below (Production Example 1)

[0224] (Styrene content: 45% by mass, vinyl content: 35% by mass)

[0225] (ii) SBR-2: Modified S-SBR obtained by the method shown below (Production Example 2)

[0226] (Styrene content: 25 mass%, vinyl content: 25 mass%)

[0227] (iii) SBR-3: HPR840 (S-SBR) manufactured by ENEOS Materials Co., Ltd.

[0228] (Styrene content: 10% by mass, vinyl content: 42% by mass)

[0229] (iv) BR: Ubepol BR150B (Hicis BR) manufactured by Ube Industries, Ltd.

[0230] (cis content 97 mass%, trans content 2 mass%, vinyl content 1 mass%)

[0231] (v)NR:TSR20

[0232] (Production Example 1)

[0233] SBR-1 was prepared according to the following process. Cyclohexane, tetrahydrofuran, styrene and 1,3-butadiene were first charged into a nitrogen-substituted autoclave reactor. The temperature of the reactor contents was adjusted to -20°C, and then n-butyl lithium was added to initiate the reaction. The polymerization was carried out under adiabatic conditions with a maximum temperature of 85°C. When the polymerization conversion reached 99%, butadiene was added, and the polymerization was further carried out for 5 minutes. Thereafter, methyltrimethoxysilane was added as a modifier and the reaction was carried out for 15 minutes. After the polymerization reaction was completed, 2,6-di-tert-butyl-p-cresol was added. Next, the solvent was removed by stripping, and the mixture was dried with a heating roller adjusted to 110°C to obtain SBR-1.

[0234] (Production Example 2)

[0235] SBR-2 was prepared according to the following process. First, two autoclaves with an internal volume of 10L, an inlet at the bottom and an outlet at the top, and equipped with a stirrer and a jacket were connected in series as reactors, and butadiene, styrene and cyclohexane were mixed in a predetermined ratio. The mixed solution was passed through a dehydration column filled with activated alumina, mixed with n-butyl lithium in a static mixer to remove impurities, and then continuously fed from the bottom of the first reactor. In addition, 2,2-bis(2-oxolane)propane as a polar substance and n-butyl lithium as a polymerization initiator were continuously fed from the bottom of the first reactor at a predetermined rate, respectively, and the temperature inside the reactor was maintained at 95°C. The polymer solution was continuously taken out from the head of the reactor and fed into 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 a monomer component was continuously added at a predetermined rate as a 1000-fold diluted cyclohexane solution to carry out a modification reaction. The polymer solution was continuously taken out from the reactor, an antioxidant was continuously added using a static mixer, and then the solvent was removed to obtain SBR-2.

[0236] The vinyl content (unit: mass %) of SBR-1 and SBR-2 was determined by infrared spectroscopy at about 910 cm -1 The absorption intensity at 100 nm (absorption peak of vinyl group) was measured, and the styrene content (unit: mass %) was measured from the refractive index according to JIS K6383:1995.

[0237] (b) Compounding materials other than rubber components

[0238] (i) Silica: Ultrasil VN3 (N2SA: 175m 2 / g, average primary particle size: 15nm)

[0239] (ii) Carbon black: Diablack N220 (N2 SA: 115 m2 / g)

[0240] (iii) Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide) manufactured by Evonik Industries

[0241] (iv) Resin: T-REZ PR801 manufactured by ENEOS Corporation (hydrogenated aromatic-modified alicyclic hydrocarbon resin)

[0242] (v) Oil: VIVATEC 500 (TDAE oil) manufactured by H&R

[0243] (vi) Zinc oxide: Type 2 zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd.

[0244] (vii) Antiaging agent: Antigen 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.

[0245] (viii) Wax: Sannok N (specially selected wax) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0246] (ix) Stearic acid: bead stearic acid "Tsubaki" manufactured by NOF Corporation

[0247] (x) Vulcanization accelerator-1: Nocceler CZ (N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0248] (xi) Vulcanization accelerator-2: Nocceler D (N,N'-diphenylguanidine (DPG) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)

[0249] (xii) Sulfur: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd.

[0250] (2) Rubber composition for forming a crown rubber layer

[0251] According to the formulations shown in Tables 2 and 3, materials other than sulfur and the vulcanization accelerator were kneaded at 150° C. for 5 minutes using a Banbury mixer to obtain kneaded mixtures. Each compounding amount is expressed in parts by mass.

[0252] Next, sulfur and a vulcanization accelerator were added to the kneaded mixture, and the mixture was kneaded at 80° C. for 5 minutes using an open roll mill to obtain a rubber composition for forming a cap rubber layer.

[0253] 2. Rubber composition for forming base rubber layer

[0254] Meanwhile, a rubber composition for forming a base rubber layer was obtained based on the formulation shown in Table 1 in the same manner as in the production of the rubber composition for forming a cap rubber layer.

[0255] [Table 1]

[0256]

[0257] 3. Pneumatic tires

[0258] Each rubber composition was extruded in a predetermined shape so that the ratio of (cap rubber layer / base rubber layer) was 8:2 to form a tread portion having a thickness shown in Tables 2 and 3.

[0259] Thereafter, the tire was bonded together with other tire components to form an unvulcanized tire, and the tire was press-vulcanized at 170° C. for 10 minutes to produce pneumatic tires (test tires) of Examples 1 to 7 and pneumatic tires (test tires) of Comparative Examples 1 to 4 shown in Tables 2 and 3.

[0260] 4. Calculation of parameters

[0261] (1) 30℃E *

[0262] The rubber sample for viscoelasticity measurement was prepared by cutting a piece of rubber with a length of 20 mm, a width of 4 mm, and a thickness of 2 mm (where the long side is in the tire circumferential direction) from the crown rubber layer of the tread portion of each test tire. The 30°C E of each rubber sample was then measured in the tensile deformation mode using the "Eplexor" 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 rate of 1%. * .

[0263] 30℃E of base rubber layer * (MPa) is set to 5MPa.

[0264] (2) tanδ at 30℃

[0265] The rubber sample for viscoelasticity measurement was prepared by cutting a piece of rubber of 20 mm in length × 4 mm in width × 2 mm in thickness (where the long side is in the tire circumferential direction) from the crown rubber layer of the tread portion of each test tire. Then, the 30°C tanδ of each rubber sample was measured using the "Eplexor" series manufactured by GABO under the conditions of temperature 30°C, frequency 10 Hz, initial strain 5%, dynamic strain rate 1% and tensile deformation mode.

[0266] The 30°C tanδ of the base rubber layer was set to 0.07.

[0267] (3)M100

[0268] A No. 7 dumbbell-shaped test piece having a thickness of 1 mm was prepared from a sample taken from the crown rubber layer of each test tire and subjected to a tensile test at 23° C. in accordance with JIS K6251:2010 to measure the modulus at 100% elongation (M100: MPa).

[0269] (4)AE

[0270] Using a vulcanized rubber specimen prepared by cutting out from the cap rubber layer of the tread portion of each test tire, AE (mass %) was measured in accordance with JIS K 6229:2015.

[0271] (5) (SBR content × grounding rate), (silicon dioxide content × flatness rate)

[0272] In addition, based on the specifications and mixing content of each test tire, the product of the SBR content (mass part) with a styrene content of less than 25 mass% and the ground contact rate (%) of the tread portion (SBR content×ground contact rate) and the product of the silica content (mass part) and the aspect ratio (%) (silica content×aspect ratio) were calculated.

[0273] 5. Performance evaluation test (evaluation of wear resistance during high-speed driving)

[0274] Each test tire was mounted on all wheels of a vehicle (a domestic front-engine, front-drive vehicle with a displacement of 2000cc) and filled with air so that the internal pressure was 250kPa (standardized internal pressure for passenger cars). After driving 8000km on the test route at 100km / h, the groove depth of the tread portion was measured and the degree of reduction in the groove depth was calculated. The driving distance corresponding to a 1mm reduction in the groove depth was then calculated.

[0275] Next, the result of Comparative Example 4 was set to 100 and indexed according to the following formula to evaluate the wear resistance during high-speed running. A larger value indicates better wear resistance during high-speed running.

[0276] High-speed wear resistance = [(test tire results) / (comparative example 4 results)] × 100 [Table 2]

[0277]

[0278] [Table 3]

[0279]

[0280] Although the present invention has been described based on the above embodiment, the present invention is not limited to the above embodiment. Various modifications can be made to the above embodiment within the scope of the same and equivalent to the present invention.

[0281] The present invention (1) is a tire having a tread portion, wherein:

[0282] The cap rubber layer forming the tread portion contains 80 parts by mass or more of styrene-butadiene rubber (SBR) having a styrene content of 25% by mass or less per 100 parts by mass of the rubber component, and contains 100 parts by mass or less of silica per 100 parts by mass of the rubber component; and

[0283] The crown rubber layer is formed of a rubber composition having a complex elastic modulus (30°C E*) of 8.0 MPa or less measured at a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain rate of 1% and a tensile deformation mode; and

[0284] The tread portion has a thickness of 9.0 mm or less.

[0285] The present invention (2) is the tire according to the present invention (1), wherein the styrene content in the styrene-butadiene rubber (SBR) is 20% by mass or less.

[0286] The present invention (3) is a tire according to the present invention (1) or (2), wherein 30°C E * Below 7.5MPa.

[0287] The present invention (4) is a tire according to any combination of the present inventions (1) to (3), wherein the thickness of the tread portion is 8.5 mm or less.

[0288] The present invention (5) is a tire as described in any combination of the present inventions (1) to (4), wherein the rubber composition constituting the crown rubber layer has a loss tangent 30°C tanδ measured in a tensile deformation mode 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% of less than 0.25.

[0289] The present invention (6) is the tire according to the present invention (5), wherein tan δ at 30°C is 0.23 or less.

[0290] The present invention (7) is a tire according to any combination of the present inventions (1) to (6), wherein the modulus (M100) of the cap rubber layer at 100% elongation at 23°C is 2.5 MPa or more.

[0291] The present invention (8) is the tire according to any combination of the present inventions (1) to (7), wherein the rubber component of the rubber composition constituting the cap rubber layer contains an isoprene-based rubber.

[0292] The present invention (9) is a tire according to any combination of the present inventions (1) to (8), wherein the thickness of the cap rubber layer accounts for more than 10% of the entire tread portion.

[0293] The present invention (10) is a tire as described in any combination of the present inventions (1) to (9), wherein the ground contact rate of the tread portion is 40% or more, and the product of the content (mass parts) of styrene-butadiene rubber (SBR) having a styrene content of less than 25 mass% in 100 mass parts of the rubber component and the ground contact rate (%) of the tread portion is less than 9000.

[0294] The present invention (11) is a tire as described in any combination of the present inventions (1) to (10), wherein the ground contact rate of the tread portion is 40% or more, and the product of the content (mass parts) of styrene-butadiene rubber (SBR) having a styrene content of less than 25 mass% in 100 mass parts of the rubber component and the ground contact rate (%) of the tread portion is less than 8500.

[0295] The present invention (12) is a tire as described in any combination of the present inventions (1) to (11), wherein the ground contact rate of the tread portion is 40% or more, and the product of the content (mass parts) of styrene-butadiene rubber (SBR) having a styrene content of less than 25 mass% in 100 mass parts of the rubber component and the ground contact rate (%) of the tread portion is less than 7000.

[0296] The present invention (13) is a tire as described in any combination of the present inventions (1) to (12), wherein the aspect ratio is less than 80% and the product of the silica content (parts by mass) and the aspect ratio (%) relative to 100 parts by mass of the rubber component is less than 7500.

[0297] The present invention (14) is a tire as described in any combination of the present inventions (1) to (13), wherein the aspect ratio is less than 80% and the product of the silica content (parts by mass) and the aspect ratio (%) relative to 100 parts by mass of the rubber component is less than 7000.

[0298] The present invention (15) is a tire as described in any combination of the present inventions (1) to (14), wherein the aspect ratio is less than 80% and the product of the silica content (parts by mass) and the aspect ratio (%) relative to 100 parts by mass of the rubber component is less than 6500.

Claims

1. A tire having a tread portion, wherein: The cap rubber layer forming the tread portion contains 80 parts by mass or more of styrene-butadiene rubber (SBR) having a styrene content of 25% by mass or less per 100 parts by mass of the rubber component, and contains 100 parts by mass or less of silica per 100 parts by mass of the rubber component; and The crown rubber layer is formed of a rubber composition having a complex elastic modulus (30°C E*) of 8.0 MPa or less measured at a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain rate of 1% and a tensile deformation mode; and The tread portion has a thickness of 9.0 mm or less.

2. The tire according to claim 1, wherein: The styrene-butadiene rubber (SBR) contains 20% by mass or less of styrene.

3. The tire according to claim 1 or 2, wherein: 30℃E * Below 7.5MPa.

4. The tire according to any one of claims 1 to 3, wherein: The tread portion has a thickness of 8.5 mm or less.

5. The tire according to any one of claims 1 to 4, wherein: The rubber composition constituting the tread cap rubber layer has a loss tangent 30°C tanδ measured in a tensile deformation mode 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% of 0.25 or less.

6. The tire according to claim 5, wherein: The 30°C tanδ is 0.23 or less.

7. The tire according to any one of claims 1 to 6, wherein: The modulus (M100) of the cap rubber layer at 100% elongation at 23° C. is 2.5 MPa or more.

8. The tire according to any one of claims 1 to 7, wherein: The rubber component of the rubber composition constituting the cap rubber layer includes an isoprene-based rubber.

9. The tire according to any one of claims 1 to 8, wherein: The thickness of the crown rubber layer accounts for more than 10% of the entire tread portion.

10. The tire according to any one of claims 1 to 9, wherein: The ground contact rate of the tread portion is 40% or more, and the product of the content (mass parts) of styrene-butadiene rubber (SBR) having a styrene content of 25% or less in 100 parts by mass of the rubber component and the ground contact rate (%) of the tread portion is 9000 or less.

11. The tire according to any one of claims 1 to 10, wherein: The ground contact rate of the tread portion is 40% or more, and the product of the content (mass parts) of styrene-butadiene rubber (SBR) having a styrene content of 25% or less in 100 parts by mass of the rubber component and the ground contact rate (%) of the tread portion is 8500 or less.

12. The tire according to any one of claims 1 to 11, wherein: The ground contact rate of the tread portion is 40% or more, and the product of the content (mass parts) of styrene-butadiene rubber (SBR) having a styrene content of 25% or less in 100 parts by mass of the rubber component and the ground contact rate (%) of the tread portion is 7000 or less.

13. The tire according to any one of claims 1 to 12, wherein: The oblateness is 80% or less, and the product of the content (parts by mass) of silica relative to 100 parts by mass of the rubber component and the oblateness (%) is 7500 or less.

14. The tire according to any one of claims 1 to 13, wherein: The oblateness is 80% or less, and the product of the content (parts by mass) of silica relative to 100 parts by mass of the rubber component and the oblateness (%) is 7000 or less.

15. The tire according to any one of claims 1 to 14, wherein: The oblateness is 80% or less, and the product of the content (parts by mass) of silica relative to 100 parts by mass of the rubber component and the oblateness (%) is 6500 or less.

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