tire

Abstract

To provide a tire capable of improving aesthetic performance after traveling at high speed.SOLUTION: Provided is a tire with a tread part and a clinch part, in which a ratio (G / WL) of a tire weight G(kg) to a maximum load capacity WL(kg) of the tire is 0.0150 or less, the clinch part is composed of a rubber composition containing a rubber constituent and a filler, a tanδ (70°C tanδC) of the rubber composition at 70°C constituting the clinch part is 0.11 or less, and the product (70°C E*C×G / WL) of a complex elastic modulus (MPa)(70°C E*C) of the rubber composition at 70°C constituting the clinch part and the G / WL is 0.075 or more.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Recent advancements in tire tread rubber have been remarkable, and along with improvements in the low heat generation properties of tread rubber, the contributions of other tire components to heat generation are also being actively investigated. Patent Document 1 describes that the rolling resistance of a tire can be reduced by providing a rubber chafer portion (clinch portion) formed from a specific rubber composition. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2019 / 045062 [Overview of the project] [Problems that the invention aims to solve]

[0004] On the other hand, with the recent development of expressways and other infrastructure, it is no longer uncommon for drivers to drive at high speeds, and the aesthetic appearance of tires is also becoming increasingly important. In this context, there is concern that if the appearance of tires is compromised during vehicle inspections or other maintenance, tires may be replaced even if their quality performance is guaranteed. Therefore, there is room for improvement in the aesthetic performance of tires after repeated high-speed driving.

[0005] The present invention aims to improve the aesthetic performance after high-speed driving. [Means for solving the problem]

[0006] The present invention relates to a tire comprising a tread portion and a clinch portion, wherein the maximum load capacity of the tire is W L Ratio of tire weight G (kg) to (kg) (G / W L) is 0.0150 or less, the clinch portion is composed of a rubber composition containing a rubber component and a filler, and the tanδ (70°C tanδ C ) of the rubber composition constituting the clinch portion at 70°C is 0.11 or less, and the product of the complex elastic modulus (MPa) (70°C E* C ) and G / W L (70°C E* C × G / W L ) is 0.075 or more. The present invention relates to a tire.

Effect of the Invention

[0007] According to the present invention, it is possible to improve the aesthetic performance after high-speed driving.

Brief Description of the Drawings

[0008] [Figure 1] It is a schematic diagram of the contact surface of the tire when the tread is pressed against a flat surface. [Figure 2] It is a schematic partial cross-sectional view of a tire according to an embodiment of the present invention. [Figure 3] It is a view showing the tire cross-sectional width Wt, the tire cross-sectional height Ht, and the tire outer diameter Dt in the cross-section of the tire.

Mode for Carrying Out the Invention

[0009] A tire according to an embodiment of the present invention is a tire provided with a tread portion and a clinch portion, and the ratio of the tire weight G (kg) to the maximum load capacity W L (kg) of the tire (G / W L ) is 0.0150 or less, the clinch portion is composed of a rubber composition containing a rubber component and a filler, and the tanδ (70°C tanδ C ) of the rubber composition constituting the clinch portion at 70°C is 0.11 or less, and the product of the complex elastic modulus (MPa) (70°C E* C ) and G / W L (70°C E* C×G / W L These are tires with a coefficient of 0.075 or higher.

[0010] When the tire weight relative to the tire's maximum load capacity and the viscoelastic properties of the rubber composition constituting the clinch section satisfy the above requirements, the resulting tire exhibits significantly improved aesthetic performance after high-speed driving. While not intended to be constrained by theory, the reason for this is thought to be as follows.

[0011] The weight-to-maximum load capacity ratio of the tire of the present invention is 0.015 or less, resulting in a lighter tire compared to conventional tires. From this, (1) as each component becomes thinner due to the weight reduction, heat generated during high-speed driving is more easily dissipated to the outside, making it less likely to cause excessive temperature rise, and thus making it easier to suppress the migration and precipitation of wax components contained in the rubber composition, such as the clinch section, due to thermal diffusion. Also, (2) the loss tangent tanδ of the clinch section at high temperatures is reduced, and heat generation in the clinch section is suppressed, thereby preventing the migration of wax inside the rubber. On the other hand, when the ratio of tire weight to maximum load capacity becomes small, there is a concern that the amount of deformation in the clinch section will increase and cracks may occur, but (3) by increasing the stiffness of the clinch section at high temperatures (complex modulus of elasticity E*) relative to the ratio of tire weight to maximum load capacity, deformation of the clinch section during rolling is suppressed, and it is thought that cracks on the surface and internal heat generation associated with deformation can be suppressed. Based on the above, the clinch section is designed to easily dissipate heat and reduce heat generation, while also minimizing deformation. This suppresses the migration and precipitation of wax within the rubber and inhibits the occurrence of cracks due to deformation. As a result, it is believed that a remarkable effect is achieved: a significant improvement in aesthetic performance even after high-speed driving.

[0012] Golden Week L It is preferably 0.0140 or less, and more preferably 0.0135 or less.

[0013] Golden Week LBy setting the range as described above and reducing the tire weight relative to the tire's maximum load capacity, it is thought that heat inside the tire can be more easily dissipated, further improving the aesthetic performance after high-speed driving.

[0014] 70℃E* C It is preferable that the pressure be 10.0 MPa or higher.

[0015] 70℃E* C By setting the range to the aforementioned extent, it is believed that the amount of deformation in the clinch portion can be reduced, making it easier to suppress the occurrence of cracks.

[0016] The modulus (M100) of the rubber composition constituting the clinch section at 100% stretch at 23°C C The pressure is preferably 5.0 MPa or higher.

[0017] By increasing not only the low-distortion rigidity (E*) but also the high-distortion rigidity (M100) of the clinch section, heat generation can be suppressed in response to inputs from a wide range of road surfaces, which is expected to further improve the aesthetic performance after high-speed driving.

[0018] 70℃ tanδ C It is preferable that it be 0.065 or less.

[0019] By reducing the heat generation of the rubber in the clinch section, it is thought that heat generation during high-speed driving can be suppressed, and heat diffusion due to wax and other factors can be more easily controlled.

[0020] When the cross-sectional width of the tire is Wt (mm) and the outer diameter is Dt (mm), it is preferable that Wt and Dt satisfy the following formula (1). 1800≦(Dt 2 ×π / 4) / Wt ≤ 2827.4 ···(1)

[0021] For a tire's cross-sectional width Wt, the area of ​​the tire when viewed from the side [i.e., (Dt / 2)] 2 ×π=Dt 2By increasing the [xπ / 4] factor, heat dissipation from the side sections is improved, which is expected to further enhance the aesthetic performance after high-speed driving.

[0022] The virtual volume of space occupied by the tire is V(mm²). 3 When this is the case, it is preferable that V and Wt satisfy the following formula (2). [(V+1.5×10 7 ) / Wt] ≤ 2.88 × 10 5 ...(2)

[0023] By reducing the virtual volume V of the space occupied by the tire in accordance with the decrease in the tire's cross-sectional width Wt, and thereby reducing the volume of the tire itself, it is possible to reduce the outer diameter growth rate due to centrifugal force, and thus reduce the amount of deformation of the sidewall.

[0024] The total content of isoprene-based rubber and butadiene rubber in the rubber components constituting the clinch portion is preferably more than 80% by mass.

[0025] By setting the total content of isoprene-based rubber and butadiene rubber in the rubber component to the aforementioned range, it is believed that a phase separation structure can be formed inside the rubber, dispersing the force due to deformation at the interface between the phases and making it easier to suppress cracking.

[0026] Preferably, the total content of filler in the rubber composition constituting the clinch portion is less than 65 parts by mass per 100 parts by mass of rubber component.

[0027] By setting the total filler content in the rubber composition within the aforementioned range, it is possible to suppress heat generation due to friction between the rubber component and the filler, thereby improving the aesthetic performance after high-speed driving.

[0028] The rubber composition constituting the clinch portion preferably contains 35 parts by mass or more of carbon black with an average primary particle diameter of 40 nm or more, per 100 parts by mass of rubber component.

[0029] By including carbon black having a predetermined average primary particle size, the number of rubber molecules bound by the carbon black is minimized, allowing for greater flexibility and movement. This is thought to relieve stress on the polymer molecular chains in response to input, thereby improving aesthetic performance after high-speed driving.

[0030] 70℃E* C 70°C tanδ (MPa) C Ratio (70℃ tanδ C / 70℃E* C ) is preferably 0.004 or more and 0.020 or less.

[0031] 70℃ tanδ C / 70℃E* C By setting the range as described above, it is possible to suppress the heat generated when the tire rolls, which in turn makes it easier to suppress the deposition of wax and other substances, and also makes it easier to suppress the occurrence of cracks due to high temperatures, which can reduce the strength of the clinch section.

[0032] When the maximum thickness of the clinch section is T (mm), T and 70°C tanδ C The product of (T × 70°C tanδ) C ) is preferably less than 0.50.

[0033] T×70℃ tanδ C By setting the range to the aforementioned extent, it is possible to suppress heat generation in the clinch section and improve heat dissipation, which is thought to make it easier to improve the aesthetic performance after high-speed driving.

[0034] T and M100 C Product of (MPa) and (T × M100) C ) is preferably greater than 15.0.

[0035] T×M100 C By setting the range to the aforementioned extent, it is thought that deformation at the clinch portion can be more easily suppressed.

[0036] The tanδ(30°C tanδ) of the rubber composition constituting the tread at 30°C T ) is preferably 0.18 or less.

[0037] By suppressing heat generation in the tread area, the temperature rise of the tire during high-speed driving can be reduced. As a result, deformation of the clinch area can be suppressed, and it is thought that the aesthetic performance after high-speed driving can be improved.

[0038] 30°C tanδ relative to tire weight G (kg) T Ratio (30℃ tanδ T The value of / G) is preferably greater than 0.010.

[0039] As tire weight decreases, the impact from road surface irregularities is less effectively absorbed, and deformation tends to be greater when impact is applied than during rolling. 30℃tanδ T By setting / G within the aforementioned range, the heat generation of the tread rubber is increased in proportion to the tire weight. As a result, it is thought that the tread rubber will be able to absorb energy more easily, deformation at the clinch section can be reduced, and the aesthetic performance after high-speed driving will be improved.

[0040] In the tread portion of the present invention, the total area of ​​the land portion is Sr, and the total area of ​​the center land portion is S ce When S ce The value of / Sr is preferably between 0.35 and 0.80.

[0041] S ce By setting / Sr within the range described above, the rigidity in the center region of the tread is optimized, allowing the tread to absorb impacts when they are transmitted, and suppressing excessive deformation in the clinch area.

[0042] At least one land area has an opening area of ​​0.1 mm² to the tread surface. 2 15mm or more 2 It is preferable to have one or more of the following small holes.

[0043] By providing the aforementioned small holes, it is possible to increase the surface area of ​​the tread portion without adversely affecting other performance aspects. This is expected to improve heat dissipation in the tread portion and suppress temperature rise in the side and clinch portions.

[0044] <Definition> A "standard rim" is the rim specified for each tire in the standardization system that the tire is based on. For example, it is a "standard rim" for JATMA, a "design rim" for TRA, and a "measuring rim" for ETRTO. In the case of tires whose size is not specified in the aforementioned standardization system, it refers to the narrowest rim with the smallest diameter that can be mounted on that tire without causing air leakage between the rim and the tire.

[0045] "Regular internal pressure" refers to the air pressure specified for each tire in the tire standard system, including the standard on which the tire is based. For example, it is the "maximum air pressure" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO. For tires of sizes not specified in the aforementioned standard system, the regular internal pressure is set at 250 kPa.

[0046] "Normal condition" refers to a tire that is mounted on a normal rim, filled to the normal internal pressure, and under no load. In the case of a tire size not specified in the aforementioned standard system, it refers to a tire that is mounted on the smallest rim, filled to 250 kPa, and under no load.

[0047] "The tire weight G (kg) is the weight of the tire alone, excluding the weight of the rim. Furthermore, if sound-dampening material, sealant, sensors, etc., are installed in the tire cavity, G will include the weight of these components."

[0048] "Maximum load capacity (W L "(kg)" is a value calculated by the following formulas (3) and (4), where Wt (mm) is the tire section width measured under normal conditions, Ht (mm) is the tire section height, and Dt (mm) is the tire outer diameter. 3 ) is the virtual volume of space occupied by the tire. The tire section width Wt is the maximum width between the outer surfaces of the sidewalls in the above state, excluding any patterns or letters on the tire sidewall. The tire section height Ht is the distance from the bottom surface of the bead to the outermost surface of the tread, and is half the difference between the outer diameter of the tire and the nominal rim diameter. V = {(Dt / 2)} 2 -(Dt / 2-Ht) 2} × π × Wt ···(3) W L = 0.000011 × V + 100 ... (4)

[0049] The "maximum thickness of the clinch portion" is the maximum thickness T (mm) measured along the normal L to the inner interface of the clinch portion 4 in the tire width direction (see Figure 2). The "maximum thickness of the clinch portion" is measured when the tire is cut along the plane including the tire rotation axis, and the width of the bead portion is matched to the width of the regular rim. Furthermore, if the clinch portion is in contact with another component on the inner side in the tire width direction and a step is created due to the shape of the other component, the length at the location of the step shall be excluded. For example, if the reversal portion of the carcass layer overlaps with the clinch portion, the thickness at the end of the reversal portion of the carcass layer shall be excluded.

[0050] A "groove," including circumferential grooves and lateral grooves, refers to a recess with a width of at least 2.0 mm. On the other hand, a "sipe" refers to a narrow cut with a width of 2.0 mm or less, preferably 0.5 to 1.5 mm.

[0051] A "small hole" refers to a hole that extends from within the tread and opens onto the tread surface.

[0052] "Plasticizer content" includes the amount of plasticizer contained in the extensible rubber component that has been pre-stretched with plasticizers such as oil, resin components, and liquid rubber. The same applies to the oil content, resin component content, and liquid rubber content; for example, if the extensible component is oil, the extensible oil is included in the oil content.

[0053] <Measurement method> "70℃tanδ" is the loss loss tangent measured under the conditions of a temperature of 70℃, initial strain of 10%, dynamic strain of 1%, frequency of 10Hz, and extension mode. The sample for measuring 70℃tanδ is a vulcanized rubber composition with dimensions of 20mm in length, 4mm in width, and 1mm in thickness. When preparing the sample by cutting it from a tire, it is cut from the clinch portion 4 of the tire such that the tangential direction to the tire's circumferential direction is the longer side, and the normal direction to the inner interface of the clinch portion 4 in the tire's width direction is the thickness direction.

[0054] "70℃E*" is the complex modulus (MPa) measured under the conditions of 70℃ temperature, 10% initial strain, 1% dynamic strain, 10Hz frequency, and extension mode. Samples for 70℃E* measurement are prepared in the same manner as for 70℃tanδ.

[0055] "M100" is the 100% elongation stress (MPa) obtained when a tensile test is performed in a 23°C atmosphere at a tensile speed of 3.3 mm / second, according to JIS K 6251 "Vulcanized rubber and thermoplastic rubber - Method for determining tensile test properties", using a 1 mm thick, No. 7 dumbbell-shaped test piece cut from the clinch portion of each test tire so that the tangential direction to the tire's circumferential direction is the tensile direction.

[0056] "30℃tanδ" is the loss loss tangent measured under the conditions of a temperature of 30℃, initial strain of 5%, dynamic strain of 1%, frequency of 10Hz, and extension mode. The sample for measuring 30℃tanδ is a vulcanized rubber composition with dimensions of 20mm in length, 4mm in width, and 1mm in thickness. When preparing the sample by cutting it from a tire, it is cut from the tire's tread portion 2 (or the rubber layer constituting the tread surface if the tread portion consists of two or more rubber layers) such that the tangential direction to the tire's circumferential direction is the longer side and the tire's width direction is the thickness direction.

[0057] The area of ​​the openings on the tread surface of the small holes, the total area of ​​the land portion Sr, and the total area of ​​the center land portion S. ce The contact patch area is calculated from the tire's contact patch shape. The contact patch shape is obtained by mounting the tire to a standard rim, applying standard internal pressure, letting it stand at 25°C for 24 hours, then applying ink to the tire tread surface, applying a load of the maximum load capacity, pressing it onto cardboard (camber angle 0°), and transferring the shape to the paper. The tire is then rotated 72° in the circumferential direction, and the shape is transferred at 5 locations. In other words, the contact patch shape is obtained 5 times. The actual contact patch area is determined by the average of the areas of the ink-covered areas at 5 locations. From the obtained contact patch shape, the total area of ​​the shoulders is calculated by summing the areas of the shoulders with all lateral grooves and sipes crossing the shoulders, and including any small holes, filled in. The total area of ​​the center is calculated by summing the areas of the center with all lateral grooves and sipes crossing the center, and including any small holes, filled in. The sum of the total areas of the shoulders and the center is calculated as the total area of ​​the entire land area.

[0058] "Styrene content" is, 1 This value is calculated by 1H-NMR measurement and applies, for example, to rubber components having repeating units derived from styrene, such as SBR. "Cis content (amount of cis-1,4-bonded butadiene units)" is a value calculated by infrared absorption spectroscopy in accordance with JIS K 6239-2:2017 and applies, for example, to rubber components having repeating units derived from butadiene, such as BR.

[0059] The average primary particle size of carbon black can be determined by observing it with a transmission or scanning electron microscope, measuring 400 or more primary particles of carbon black observed within the field of view, and averaging the results. The specific surface area (N2SA) of nitrogen adsorption of carbon black is measured in accordance with JIS K 6217-2:2017. The average primary particle size of silica can be determined by observing it with a transmission or scanning electron microscope, measuring 400 or more primary particles of silica observed within the field of view, and averaging the results. The specific surface area (N2SA) of nitrogen adsorption of silica is measured by the BET method in accordance with ASTM D3037-93.

[0060] The procedure for manufacturing a tire, which is one embodiment of the present invention, will be described in detail below. However, the following description is illustrative for explaining the present invention and is not intended to limit the technical scope of the present invention to this scope only.

[0061] <Tires> The tire of the present invention has a maximum load capacity W L Ratio of tire weight G (kg) to (kg) (G / W L From the viewpoint of the effects of the present invention, the value of G / W is 0.0150 or less, preferably 0.0145 or less, more preferably 0.0140 or less, even more preferably 0.0135 or less, and particularly preferably 0.0133 or less. L The lower limit is not particularly limited, but for example, it can be 0.0080 or higher, 0.0090 or higher, 0.0100 or higher, 0.0110 or higher, 0.0115 or higher, or 0.0120 or higher. The tire weight G can be varied by conventional methods, that is, it can be increased by increasing the specific gravity of the tire or by increasing the thickness of each component of the tire, and vice versa.

[0062] Maximum load capacity W L From the viewpoint of better demonstrating the effects of the present invention, the (kg) is preferably 300 or more, more preferably 350 or more, even more preferably 400 or more, and particularly preferably 450 or more. Also, the maximum load capacity W LThe (kg) can be, for example, 1300 or less, 1200 or less, 1100 or less, 1000 or less, 900 or less, 800 or less, 700 or less, or 650 or less, from the viewpoint of better demonstrating the effects of the present invention. L This can be increased by increasing the virtual volume V of the space occupied by the tire, and conversely, it can be decreased by increasing it.

[0063] In the present invention, when the tire is measured under normal conditions, Wt (mm) is the cross-sectional width of the tire and Dt (mm) is the outer diameter, and it is preferable that Wt and Dt satisfy the following formula (1). 1800≦(Dt 2 ×π / 4) / Wt ≤ 2827.4 ···(1)

[0064] For a tire's cross-sectional width Wt, the area of ​​the tire when viewed from the side [i.e., (Dt / 2)] 2 ×π=Dt 2 By increasing [×π / 4], the heat dissipation from the side is improved, which is expected to further enhance fuel efficiency.

[0065] Here, as Dt increases, the value of equation (1) increases, and conversely, as Dt decreases, the value decreases. Conversely, as Wt increases, the value of equation (1) decreases, and conversely, as Wt decreases, the value increases. Therefore, by focusing on this point and adjusting Dt and Wt, it is possible to adjust Dt and Wt so that they satisfy equation (1). The value of equation (1) is preferably 1850 or more, and more preferably 1900 or more. Furthermore, the value of equation (1) is preferably 2800 or less, more preferably 2700 or less, even more preferably 2600 or less, and particularly preferably 2500 or less.

[0066] Examples of tire sizes that satisfy equation (1) include 125 / 65R19, 145 / 60R18, 145 / 60R19, 155 / 55R18, 155 / 55R19, 155 / 70R17, 155 / 70R19, 165 / 55R20, 165 / 55R21, 165 / 60R19, 165 / 65R19, 165 / 70R18, 175 / 55R19, 175 / 55R20, 175 / 55R22, 175 / 60R18, 185 / 55R19, 185 / 60R20, 195 / 50R20, 195 / 55R20, etc.

[0067] The aspect ratio of the tire is preferably 40% or more, more preferably 45% or more, even more preferably 50% or more, and particularly preferably 55% or more. By having an aspect ratio within the above range, the height of the tire's sidewall can be increased, suppressing local deformation of the tire, and thus further improving the tire's durability. The aspect ratio (%) is calculated from the tire's cross-sectional height Ht (mm) and cross-sectional width Wt (mm) at normal internal pressure using the formula (Ht / Wt) × 100.

[0068] The tire outer diameter Dt is preferably 515 mm or more, more preferably 558 mm or more, even more preferably 585 mm or more, and particularly preferably 630 mm or more. Furthermore, the tire outer diameter Dt is preferably less than 843 mm, more preferably less than 725 mm, even more preferably less than 707 mm, even more preferably less than 685 mm, and particularly preferably less than 655 mm.

[0069] The tire section width Wt is preferably 115 mm or more, more preferably 125 mm or more, even more preferably 150 mm or more, and particularly preferably 170 mm or more. Furthermore, the tire section width Wt is preferably less than 305 mm, more preferably less than 245 mm, even more preferably less than 210 mm, and particularly preferably less than 200 mm.

[0070] The tire section height Ht is preferably 37 mm or more, more preferably 60 mm or more, and even more preferably 80 mm or more. Furthermore, the tire section height Ht is preferably less than 180 mm, more preferably less than 152 mm, even more preferably less than 130 mm, and particularly preferably less than 115 mm.

[0071] The virtual volume V of the space occupied by the tire is 1.2 × 10⁻⁶. 7 mm 3 The above is preferable, 1.6 × 10 7 mm 3 The above is more preferable, 2.0 × 10 7 mm 3 The above is even more preferable. On the other hand, the virtual volume V is 8.8 × 10 7 mm 3 Less than 6.6 × 10 7 mm 3 Less than 4.4 × 10 7 mm 3 Less than 3.9 × 10 7 mm 3 Less than is particularly preferable.

[0072] The virtual volume V of the space occupied by the tire and the cross-sectional width Wt of the tire preferably satisfy the following equation (2). [(V+1.5×10 7 ) / Wt] ≤ 2.88 × 10 5 ...(2)

[0073] By reducing the virtual volume V of the space occupied by the tire in accordance with the decrease in the tire's cross-sectional width Wt, and thereby reducing the volume of the tire itself, it is possible to reduce the outer diameter growth rate due to centrifugal force, and thus reduce the amount of deformation of the sidewall.

[0074] The value of equation (2) is 2.85 × 10 5 The following is preferable: 2.80 × 10 5 The following is more preferable: 2.75 × 10 5 The following is even more preferable. Also, the value of equation (2) is 2.00 × 10 5 The above is preferable, 2.10 × 10 5The above is more preferable, 2.20 × 10 5 The above is even more preferable.

[0075] Figure 1 shows a schematic diagram of the contact surface when the tread is pressed against a flat surface, but the present invention is not limited to this embodiment. In Figure 1, the tread portion 2 has circumferential grooves 9 that extend continuously in the tire circumferential direction C, and transverse grooves 21 and sipes 22, 23 that extend in the width direction.

[0076] In Figure 1, three circumferential grooves 9 are provided, but the number of circumferential grooves is not particularly limited and may be, for example, two to five. Also, in this invention, the circumferential grooves 9 extend linearly along the circumferential direction, but are not limited to this configuration and may extend in a wavy, sinusoidal, or zigzag pattern along the circumferential direction, for example.

[0077] The tread portion 2 has a land area 10 separated by a plurality of circumferential grooves 9 in the tire width direction W. The shoulder land area 11 is a pair of land areas formed between the circumferential grooves 9 and the tread edge Te. The center land area 12 is a land area formed between the pair of shoulder land areas 11. In Figure 1, there are two center land areas 12, but the number of center land areas is not particularly limited and may be, for example, one to five.

[0078] It is preferable that the land portion 10 is provided with transverse grooves (widthwise grooves) and / or sipes. In Figure 1, the shoulder land portion 11 is provided with a plurality of shoulder transverse grooves 21 whose ends open into the circumferential grooves 9 and a plurality of shoulder sipes 22 whose one end opens into the circumferential grooves 1, and the center land portion 12 is provided with a plurality of center sipes 23 whose one end opens into the circumferential grooves 9.

[0079] The land part 10 preferably has one or more small holes. In FIG. 1, in the center land part 12, two small holes 24 are provided in the land part surrounded by the tire width direction part and the tire circumferential direction part of the center sipe 23 and the center sipe 23 adjacent to the center sipe 23 in the tire circumferential direction. The opening area of the small hole on the tread surface is 0.1 mm 2 or more is preferable, 0.5 mm 2 or more is more preferable, 1.0 mm 2 or more is even more preferable, 1.5 mm 2 or more is particularly preferable. Also, the opening area of the small hole on the tread surface is preferably 15 mm 2 or less, more preferably 10 mm 2 or less, even more preferably 7.0 mm 2 or less, particularly preferably 5.0 mm 2 or less. By providing small holes having the above opening area, it is possible to increase the surface area of the tread part without adversely affecting other performances, so that the heat dissipation property in the tread part is improved and the temperature rise in the tire and the side part can be suppressed.

[0080] The depth of the deepest part of the circumferential groove 9 is preferably 3.0 mm or more, more preferably 4.0 mm or more, and even more preferably 5.0 mm or more. Also, the depth of the deepest part of the circumferential groove 9 is preferably 10.0 mm or less, more preferably 9.0 mm or less, and even more preferably 8.0 mm or less.

[0081] The depth of the deepest part of the small hole 24 is preferably 3% or more, more preferably 5% or more, of the depth of the deepest part of the circumferential groove 9. Also, the depth of the deepest part of the small hole 24 is preferably 80% or less, more preferably 60% or less, and even more preferably 40% or less, of the depth of the deepest part of the circumferential groove 9.

[0082] In the tread part 2, when the total area of the land part is Sr and the total area of the center land part is S ce , S ce / Sr is preferably 0.35 or more, more preferably 0.40 or more, even more preferably 0.42 or more, and particularly preferably 0.44 or more. Also, S ce / Sr is preferably 0.80 or less, more preferably 0.70 or less, still more preferably 0.60 or less, and particularly preferably 0.55 or less. S ce By setting S / Sr within the above range, the rigidity in the center region of the tread portion is optimized, and it is considered that the impact can be absorbed in the tread portion even when an impact is transmitted, and excessive deformation in the side portion is suppressed.

[0083] From the viewpoint of the effects of the present invention, the maximum thickness T (mm) of the clinch portion 4 is preferably 2.0 mm or more, more preferably 2.5 mm or more, still more preferably 3.0 mm or more, and particularly preferably 3.5 or more. Further, from the viewpoint of the effects of the present invention, the maximum thickness T (mm) of the clinch portion 4 is preferably 10.0 mm or less, more preferably 8.0 mm or less, still more preferably 7.0 mm or less, and particularly preferably 6.0 mm or less.

[0084] The tanδ (tanδ at 70°C) of the rubber composition constituting the clinch portion C is 0.11 or less from the viewpoint of heat generation, preferably 0.10 or less, more preferably 0.09 or less, and still more preferably 0.08 or less. Further, tanδ at 70°C C is preferably 0.02 or more, more preferably 0.03 or more, and still more preferably 0.04 or more. Note that tanδ at 70°C C is measured by the above measurement method.

[0085] Tanδ at 70°C C can be appropriately adjusted according to the types and blending amounts of fillers, plasticizers, vulcanizing agents, vulcanization accelerators, etc. For example, when the blending amount of a filler (particularly carbon black) is decreased, tanδ at 70°C C tends to decrease.

[0086] The complex elastic modulus (E* at 70°C) of the rubber composition constituting the clinch portion at 70°C CFrom the viewpoint of suppressing deformation of the clinch portion, the pressure is preferably 5.0 MPa or higher, more preferably 7.0 MPa or higher, even more preferably 8.0 MPa or higher, even more preferably 9.0 MPa or higher, and particularly preferably 10.0 MPa or higher. Also, 70℃E* C The pressure is preferably 20.0 MPa or less, more preferably 18.0 MPa or less, even more preferably 16.0 MPa or less, and particularly preferably 14.0 MPa or less. C This is measured by the measurement method described above.

[0087] 70℃E* C This can be appropriately adjusted by changing the type and amount of fillers, plasticizers, vulcanizing agents, vulcanization accelerators, etc. For example, increasing the amount of vulcanizing agent (especially sulfur) or vulcanization accelerator will result in a temperature of 70°C E* C It tends to rise.

[0088] The modulus (M100) of the rubber composition constituting the clinch section at 100% stretch at 23°C C From the viewpoint of the effects of the present invention, a pressure of 4.0 MPa or higher is preferred, 4.2 MPa or higher is more preferred, 4.6 MPa or higher is even more preferred, and 5.0 MPa or higher is particularly preferred. C There is no particular upper limit, but it is usually less than 10 MPa. C This is measured by the measurement method described above.

[0089] M100 C This can be appropriately adjusted, for example, by changing the type and amount of fillers, plasticizers, vulcanizing agents, vulcanization accelerators, etc.

[0090] 70℃E* C and Golden Week L The product of (70℃E* C ×G / W L From the viewpoint of the effects of the present invention, the value of ) is 0.075 or higher, preferably 0.090 or higher, more preferably 0.100 or higher, even more preferably 0.110 or higher, and particularly preferably 0.120 or higher. Also, 70℃E* C ×G / W LPreferably, the value is 0.350 or less, more preferably 0.300 or less, even more preferably 0.250 or less, and particularly preferably 0.200 or less.

[0091] 70°C tanδ relative to 70°C E* C Ratio (70℃ tanδ C / 70℃E* C ) is preferably 0.004 or higher, more preferably 0.005 or higher, and even more preferably 0.006 or higher. Also, 70℃ tanδ C / 70℃E* C The value is preferably 0.020 or less, more preferably 0.018 or less, even more preferably 0.016 or less, even more preferably 0.014 or less, even more preferably 0.012 or less, even more preferably 0.010 or less, and particularly preferably 0.008 or less. 70℃ tanδ C / 70℃E* C By setting * to the aforementioned range, it is possible to suppress the heat generated when the tire rolls, and as a result, it is thought that the effects of the present invention can be more easily obtained.

[0092] Maximum thickness T (mm) of the clinch section and 70°C tanδ C The product of (T × 70°C tanδ) C ) is preferably less than 0.50, more preferably less than 0.45, and even more preferably less than 0.40. By setting T×70℃tanδ within the above range, it is possible to suppress heat generation in the clinch section and improve heat dissipation, and it is thought that the aesthetic performance after high-speed driving can be easily improved. C Preferably, the value is greater than 0.10, more preferably greater than 0.15, and even more preferably greater than 0.20.

[0093] Maximum thickness T (mm) of the clinch section and M100 C Product of (MPa) and (T × M100) C ) is preferably greater than 15.0, more preferably greater than 16.0, even more preferably greater than 17.0, even more preferably greater than 18.0, even more preferably greater than 19.0, and particularly preferably greater than 20.0. T×M100 CBy setting the range as described above, it is thought that deformation of the clinch section during driving can be suppressed and durability can be improved. Also, T×M100 C Preferably, it is less than 60.0, more preferably less than 50.0, and even more preferably less than 40.0.

[0094] The tanδ(30°C tanδ) of the rubber composition constituting the tread at 30°C T ) is preferably 0.22 or less, more preferably 0.20 or less, and even more preferably 0.18 or less. By suppressing heat generation in the tread area, the temperature rise of the tire during high-speed driving can be suppressed. As a result, deformation of the clinch area can be suppressed, and it is thought that durability performance during high-speed driving can be easily improved. Also, 30℃ tanδ T From the viewpoint of wet grip performance, a value of 0.08 or higher is preferred, 0.10 or higher is more preferred, and 0.12 or higher is even more preferred. T This is measured by the measurement method described above.

[0095] 30°C tanδ relative to tire weight G (kg) T Ratio (30℃ tanδ T From the viewpoint of aesthetic performance after high-speed driving, the value of / G) is preferably greater than 0.010, more preferably greater than 0.014, even more preferably greater than 0.018, and particularly preferably greater than 0.022. Also, 30℃ tanδ T / G is preferably less than 0.050, more preferably less than 0.045, and even more preferably less than 0.040.

[0096] [Rubber composition] The present invention enables a more effective improvement in aesthetic performance after high-speed driving through the cooperation of the tire weight relative to the tire's maximum load capacity and the viscoelastic properties of the rubber composition constituting the clinch portion.

[0097] <Rubber components> The rubber composition constituting the clinch portion of the present invention (hereinafter referred to as the rubber composition of the present invention unless otherwise specified) preferably uses diene rubber as the rubber component. Examples of diene rubber include isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR). These rubber components may be used individually or in combination of two or more. Furthermore, these rubber components may be stretched rubber that has been pre-stretched with oil, resin, liquid rubber components, etc.

[0098] The content of diene rubber in the rubber component is preferably more than 70% by mass, more preferably more than 80% by mass, even more preferably more than 90% by mass, and particularly preferably more than 95% by mass. Alternatively, the rubber component may consist solely of diene rubber.

[0099] The rubber composition of the present invention preferably contains at least one selected from the group consisting of isoprene rubber, styrene-butadiene rubber (SBR), and butadiene rubber (BR) as a rubber component, more preferably contains isoprene rubber, even more preferably contains isoprene rubber and BR, and may consist only of isoprene rubber and BR.

[0100] (Isoprene rubber) As isoprene-based rubbers, for example, isoprene rubber (IR) and natural rubber, which are common in the tire industry, can be used. Natural rubber includes not only unmodified natural rubber (NR), but also modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, and grafted natural rubber. These isoprene-based rubbers may be used individually or in combination of two or more types.

[0101] NR is not particularly limited and can be any tire that is common in the tire industry, such as SIR20, RSS#3, and TSR20.

[0102] The isoprene-based rubber content in the rubber component is preferably 1% by mass or more, more preferably more than 5% by mass, even more preferably more than 10% by mass, even more preferably more than 20% by mass, and particularly preferably more than 30% by mass. On the other hand, the isoprene-based rubber content in the rubber component is preferably less than 80% by mass, more preferably less than 70% by mass, even more preferably less than 65% by mass, even more preferably less than 60% by mass, even more preferably less than 55% by mass, and particularly preferably 50% by mass or less.

[0103] (BR) BR is not particularly limited, and for example, BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare-earth butadiene rubber synthesized using a rare-earth element catalyst (rare-earth BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc., which are common in the tire industry, can be used. These BRs may be used individually or in combination of two or more types.

[0104] High-cis BR can be commercially available from companies such as Nippon Zeon Co., Ltd., Ube Industries, Ltd., and JSR Corporation. Including high-cis BR can improve low-temperature properties and wear resistance. The cis content of high-cis BR is preferably 95 mol% or more, more preferably 96 mol% or more, and even more preferably 97 mol% or more. The cis content of BR is measured by the measurement method described above.

[0105] When BR is included, its content in the rubber component is preferably 1% by mass or more, more preferably more than 5% by mass, even more preferably more than 10% by mass, even more preferably more than 20% by mass, even more preferably more than 30% by mass, and particularly preferably more than 40% by mass. On the other hand, when BR is included, its content in the rubber component is preferably less than 85% by mass, more preferably less than 80% by mass, even more preferably less than 75% by mass, even more preferably less than 70% by mass, and particularly preferably 65% ​​by mass or less.

[0106] The total content of isoprene-based rubber and BR in the rubber component is preferably more than 60% by mass, more preferably more than 70% by mass, even more preferably more than 80% by mass, even more preferably 85% by mass or more, even more preferably more than 90% by mass, and even more preferably more than 95% by mass. The rubber component may consist only of isoprene-based rubber and BR.

[0107] (SBR) There are no particular limitations on SBR, and examples include unmodified solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR). Modified SBRs include SBRs with modified terminals and / or main chains, and modified SBRs coupled with tin, silicon compounds, etc. (condensates, those with branched structures, etc.). Among these, S-SBR and modified SBRs are preferred. Furthermore, hydrogenated versions of these SBRs (hydrogenated SBRs) can also be used. These SBRs may be used individually or in combination of two or more types.

[0108] As the SBR, either oil-expanded SBR or non-oil-expanded SBR may be used. When oil-expanded SBR is used, the amount of oil expanded in the SBR, that is, the amount of oil-expanded oil contained in the SBR, is preferably 10 to 50 parts by mass per 100 parts by mass of rubber solids in the SBR.

[0109] The styrene content of SBR is preferably less than 40% by mass, more preferably less than 36% by mass, even more preferably less than 32% by mass, and particularly preferably less than 28% by mass. Furthermore, the styrene content of SBR is preferably more than 5% by mass, more preferably more than 7% by mass, even more preferably more than 10% by mass, even more preferably more than 13% by mass, and particularly preferably more than 16% by mass. The styrene content of SBR is measured by the measurement method described above.

[0110] When SBR is included, its content in the rubber component is preferably less than 20% by mass, more preferably less than 15% by mass, and even more preferably less than 10% by mass, from the viewpoint of the effects of the present invention. On the other hand, the lower limit of the SBR content in the rubber component is not particularly limited and may be 0 parts by mass, or it may be greater than 0%, greater than 1%, greater than 3%, or greater than 5% by mass.

[0111] (Other rubber components) The rubber component may contain other rubber components besides diene rubber, as long as they do not affect the effects of the present invention. Examples of other rubber components besides diene rubber include crosslinkable rubber components commonly used in the tire industry, such as butyl rubber (IIR), halogenated butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, polyethylene chloride rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. These other rubber components may be used individually or in combination of two or more. Furthermore, known thermoplastic elastomers may or may not be included in addition to the above-mentioned rubber components.

[0112] <Filler> The rubber composition according to the present invention preferably contains carbon black as a filler, and may further contain silica. Alternatively, the filler may consist solely of carbon black.

[0113] (Carbon Black) The carbon black used is not particularly limited; for example, common types used in the tire industry such as GPF, FEF, HAF, ISAF, and SAF can be used. In addition to carbon black produced by burning common mineral oil, carbon black made from biomass materials such as lignin may also be used. These carbon blacks may be used individually or in combination of two or more types.

[0114] From the viewpoint of durability, the average primary particle diameter of carbon black is preferably greater than 20 nm, more preferably greater than 25 nm, even more preferably greater than 30 nm, even more preferably greater than 35 nm, and particularly preferably 40 nm or more. On the other hand, from the viewpoint of obtaining reinforcing properties, the average primary particle diameter is preferably less than 90 nm, more preferably less than 75 nm, even more preferably less than 60 nm, and particularly preferably 55 nm or less. The average primary particle diameter of carbon black is measured by the measurement method described above.

[0115] The nitrogen adsorption specific surface area (N2SA) of carbon black is 90 m², from the viewpoint of the effects of the present invention. 2 Less than / g is preferable, 80m 2 Less than / g is more preferable, 70m 2 Less than / g is even more preferable, 60m 2 A value of less than / g is particularly preferred. On the other hand, the N2SA is 10m 2 Preferably more than / g, 20m 2 More preferably than / g, 30m 2 A value greater than / g is even more preferable. The N2SA of carbon black is measured by the measurement method described above.

[0116] When carbon black is included, the content per 100 parts by mass of the rubber component is preferably 25 parts by mass or more, preferably 30 parts by mass or more, more preferably 35 parts by mass or more, even more preferably 40 parts by mass or more, and particularly preferably 45 parts by mass or more, from the viewpoint of the effects of the present invention. Furthermore, from the viewpoint of obtaining flexibility and relieving stress, it is preferably less than 90 parts by mass, more preferably less than 80 parts by mass, even more preferably less than 75 parts by mass, even more preferably less than 70 parts by mass, even more preferably 65 parts by mass or less, even more preferably less than 65 parts by mass, and particularly preferably 62 parts by mass or less.

[0117] (silica) The silica used is not particularly limited, and common silica used in the tire industry can be used, such as silica prepared by the dry method (anhydrous silica) or silica prepared by the wet method (hydrated silica). Among these, hydrated silica prepared by the wet method is preferred because it contains a large number of silanol groups. In addition to the silica mentioned above, silica made from biomass materials such as rice husks may also be used as appropriate. These silicas may be used individually or in combination of two or more types.

[0118] From the viewpoint of the effects of the present invention, the average primary particle diameter of silica is preferably 16 nm or more, more preferably 17 nm or more, and even more preferably 18 nm or more. On the other hand, the average primary particle diameter is preferably 30 nm or less, and more preferably 25 nm or less. The average primary particle diameter of silica is measured by the measurement method described above.

[0119] The specific surface area (N2SA) of silica for nitrogen adsorption is 220 m², from the viewpoint of the effects of the present invention. 2 Less than / g is preferable, 200m 2 Less than / g is more preferable, 180m 2 It is even more preferable that the amount be less than / g. On the other hand, the N2SA is 100m 2 Preferably more than / g, 120m 2 More preferably than / g, 140m 2 A value greater than / g is even more preferable. The N2SA of silica is measured by the measurement method described above.

[0120] When silica is included, the amount of silica per 100 parts by mass of rubber component is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 8 parts by mass or more, from the viewpoint of obtaining reinforcing properties. Furthermore, from the viewpoint of obtaining flexibility and relieving stress, it is preferably 35 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 20 parts by mass or less.

[0121] (Other fillers) Other fillers besides silica and carbon black are not particularly limited and can include, for example, aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, magnesium sulfate, talc, clay, biochar, and other materials commonly used in the tire industry. These other fillers may be used individually or in combination of two or more.

[0122] The total content of fillers (preferably the total content of carbon black and silica) per 100 parts by mass of rubber component is preferably 25 parts by mass or more, preferably 30 parts by mass or more, more preferably 35 parts by mass or more, even more preferably 40 parts by mass or more, and particularly preferably 45 parts by mass or more. Furthermore, from the viewpoint of the effects of the present invention, it is preferably less than 90 parts by mass, more preferably less than 80 parts by mass, even more preferably less than 75 parts by mass, even more preferably less than 70 parts by mass, even more preferably 65 parts by mass or less, even more preferably less than 65 parts by mass, and particularly preferably 62 parts by mass or less.

[0123] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited, and any silane coupling agent that has conventionally been used in combination with silica in the tire industry can be used, for example: mercapto-type silane coupling agents such as 3-mercaptopropyltrimethoxysilane, Momentive's NXT-Z100, NXT-Z45, and NXT; sulfide-type silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; and thioester-type silane coupling agents such as 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, and 3-octanoylthio-1-propyltrimethoxysilane. Examples of coupling agents include: vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; 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 chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferred, and sulfide-based silane coupling agents are more preferred. These silane coupling agents may be used individually or in combination of two or more.

[0124] From the viewpoint of improving silica dispersibility, the content of the silane coupling agent per 100 parts by mass of silica is preferably more than 1 part by mass, more preferably more than 3 parts by mass, even more preferably more than 5 parts by mass, and particularly preferably more than 8 parts by mass. Furthermore, from the viewpoint of cost and processability, it is preferably less than 20 parts by mass, more preferably less than 18 parts by mass, and even more preferably less than 16 parts by mass.

[0125] <Other compounding agents> In addition to the components mentioned above, the rubber composition according to the present invention may appropriately contain compounding agents commonly used in the tire industry, such as plasticizers, waxes, stearic acid, zinc oxide, antioxidants, vulcanizing agents, and vulcanization accelerators.

[0126] Examples of plasticizers include resin components, oils, and liquid rubber.

[0127] The resin components are not particularly limited, but examples include petroleum resins, terpene resins, rosin resins, and phenolic resins commonly used in the tire industry. These resin components may be used individually or in combination of two or more.

[0128] When a resin component is included, the content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 3 parts by mass, and even more preferably more than 5 parts by mass. Furthermore, from the viewpoint of suppressing heat generation, it is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, and even more preferably less than 30 parts by mass.

[0129] Examples of oils include paraffinic process oils (mineral oil), naphthenic process oils, aromatic process oils, vegetable oils, and animal oils. Specific examples of process oils include MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Furthermore, for environmental reasons, process oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of low-PCA process oils include MES, TDAE, and heavy naphthenic oils. Additionally, from a life cycle assessment perspective, refined waste oil from rubber mixers and engines, or waste cooking oil used in restaurants, may be used.

[0130] When oil is included, the content of oil per 100 parts by mass of rubber component is preferably more than 1 part by mass, more preferably more than 3 parts by mass, and even more preferably more than 5 parts by mass, from the viewpoint of processability. Furthermore, from the viewpoint of wear resistance, it is preferably less than 90 parts by mass, more preferably less than 70 parts by mass, even more preferably less than 50 parts by mass, and particularly preferably less than 30 parts by mass.

[0131] Liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at room temperature (25°C), but examples include liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-butadiene copolymer (liquid SBR), liquid styrene-isoprene copolymer (liquid SIR), and polymers containing myrcene or farnesene. These liquid rubbers may be used individually or in combination of two or more.

[0132] When liquid rubber is included, the content of the rubber component per 100 parts by mass is preferably more than 1 part by mass, more preferably more than 3 parts by mass, and even more preferably more than 5 parts by mass. Furthermore, the content of the liquid polymer is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, and even more preferably less than 30 parts by mass.

[0133] The content of plasticizer per 100 parts by mass of rubber component (total amount if multiple plasticizers are used in combination) is preferably more than 1 part by mass, more preferably more than 3 parts by mass, and still more preferably more than 5 parts by mass. Furthermore, the content is preferably less than 90 parts by mass, more preferably less than 70 parts by mass, still more preferably less than 50 parts by mass, and particularly preferably less than 30 parts by mass.

[0134] The wax is not particularly limited; for example, petroleum-based waxes, mineral-based waxes, synthetic waxes, and other waxes commonly used in the tire industry can be used. Examples of petroleum-based waxes include paraffin wax and microcrystalline wax. These waxes may be used individually or in combination of two or more types.

[0135] When wax is included, the amount of wax per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, and more preferably more than 0.8 parts by mass, from the viewpoint of weather resistance of the rubber. Furthermore, from the viewpoint of preventing whitening of the tire due to bloom, it is preferably less than 10 parts by mass, and more preferably less than 5.0 parts by mass.

[0136] While not particularly limited, examples of anti-aging agents include amine-based, quinoline-based, quinone-based, phenol-based, and imidazole-based compounds, as well as metal carbamate salts. Phenylenediamine-based anti-aging agents such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, and N-cyclohexyl-N'-phenyl-p-phenylenediamine are preferred, as are quinoline-based anti-aging agents such as 2,2,4-trimethyl-1,2-dihydroquinoline polymer and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline. These anti-aging agents may be used individually or in combination of two or more.

[0137] When an anti-aging agent is included, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 2.0 parts by mass, from the viewpoint of the rubber's resistance to ozone cracking. Furthermore, from the viewpoint of wear resistance, it is preferably less than 10 parts by mass, and more preferably less than 5.0 parts by mass.

[0138] When stearic acid is included, its content per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass, from the viewpoint of processability. Furthermore, from the viewpoint of vulcanization rate, it is preferably less than 10 parts by mass, and more preferably less than 5.0 parts by mass.

[0139] When zinc oxide is included, its content per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass, from the viewpoint of processability. Furthermore, from the viewpoint of wear resistance, it is preferably less than 10 parts by mass, and more preferably less than 5.0 parts by mass.

[0140] Sulfur is preferably used as a vulcanizing agent. Suitable sulfur varieties include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.

[0141] When sulfur is included as a vulcanizing agent, the amount of sulfur per 100 parts by mass of rubber component is preferably more than 0.1 parts by mass, more preferably more than 0.5 parts by mass, and even more preferably more than 1.0 part by mass, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, it is preferably less than 5.0 parts by mass, more preferably less than 4.0 parts by mass, and even more preferably less than 3.5 parts by mass. When oil-containing sulfur is used as the vulcanizing agent, the amount of vulcanizing agent is the total amount of pure sulfur contained in the oil-containing sulfur.

[0142] Examples of vulcanizing agents other than sulfur include alkylphenol-sulfur chloride condensates, 1,6-hexamethylene-dithiosulfate sodium dihydrate, and 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane. These non-sulfur vulcanizing agents can be purchased commercially from companies such as Taoka Chemical Industries, Ltd., Lanxess Corporation, and Flexis.

[0143] Examples of vulcanization accelerators include sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiram-based vulcanization accelerators, dithiocarbamate-based vulcanization accelerators, and caprolactam disulfide. These vulcanization accelerators may be used individually or in combination of two or more. Among these, one or more vulcanization accelerators selected from the group consisting of sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, and guanidine-based vulcanization accelerators are preferred, with sulfenamide-based vulcanization accelerators being more preferred, as they more favorably yield the desired effect.

[0144] Examples of sulfenamide-based vulcanization accelerators include N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide (DCBS). Among these, N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS) and N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS) are preferred.

[0145] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salts of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine. Among these, 1,3-diphenylguanidine (DPG) is preferred.

[0146] Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, and di-2-benzothiazolyl disulfide. Among these, 2-mercaptobenzothiazole is preferred.

[0147] When a vulcanization accelerator is included, its content per 100 parts by mass of rubber component is preferably more than 1.0 part by mass, more preferably more than 1.5 parts by mass, and even more preferably more than 2.0 parts by mass. Furthermore, the content of the vulcanization accelerator per 100 parts by mass of rubber component is preferably less than 8.0 parts by mass, more preferably less than 6.0 parts by mass, and even more preferably less than 4.0 parts by mass. By keeping the content of the vulcanization accelerator within the above range, it tends to be possible to ensure fracture strength and elongation.

[0148] <Manufacturing> The rubber composition according to the present invention can be manufactured by known methods. For example, it can be manufactured by kneading each of the above components using a rubber kneading device such as an open roll or a closed kneader (Banbury mixer, kneader, etc.).

[0149] The mixing process includes, for example, a base mixing process in which compounding agents and additives other than the vulcanizing agent and vulcanization accelerator are mixed, and a final mixing (F mixing) process in which the vulcanizing agent and vulcanization accelerator are added to the mixture obtained in the base mixing process and mixed. Furthermore, the base mixing process can be divided into multiple processes as desired.

[0150] There are no particular limitations on the mixing conditions, but for example, in the base mixing process, mixing is performed at a discharge temperature of 150-170°C for 3-10 minutes, and in the final mixing process, mixing is performed at 70-110°C for 1-5 minutes. There are no particular limitations on the vulcanization conditions, but for example, vulcanization is performed at 150-200°C for 10-30 minutes.

[0151] The tire of the present invention, which has a clinch portion made of the aforementioned rubber composition, can be manufactured by conventional methods. That is, an unvulcanized rubber composition, in which the above components are blended with the rubber component as needed, is extruded to match the shape of the clinch portion, bonded together with other tire components on a tire molding machine, and molded in a conventional method to form an unvulcanized tire. This unvulcanized tire is then heated and pressurized in a vulcanizing machine to manufacture the tire. The vulcanization conditions are not particularly limited, and for example, a method of vulcanization at 150 to 200°C for 10 to 30 minutes can be used.

[0152] <Application> The tire of the present invention can be suitably used for passenger car tires, truck and bus tires, motorcycle tires, and racing tires, and is particularly preferred for use in passenger car tires. A passenger car tire is defined as a tire intended for use on a four-wheeled vehicle, with a maximum load capacity of 1000 kg or less. Furthermore, the tire of the present invention can be used for all-season tires, summer tires, and winter tires such as studless tires. [Examples]

[0153] The following examples (implementations) are considered preferable for implementation, but the scope of the present invention is not limited to these examples.

[0154] Assuming a tire comprising a clinch section made of a rubber composition obtained according to Table 1 using the various chemicals listed below, and a tread section having a 30°C tanδ as described in Table 1, the results calculated based on the evaluation method below are shown in Tables 1 to 4.

[0155] The various chemicals used in the examples and comparative examples are summarized below. NR:TSR20 BR: UBEPOL BR (registered trademark) 150B (cis content: 97 mol%) manufactured by Ube Industries, Ltd. SBR: SBR1502 (E-SBR, styrene content: 23.5% by mass) manufactured by JSR Corporation. Carbon Black: Seast SO (FEF, N550, N2SA) manufactured by Tokai Carbon Co., Ltd.: 42m 2 / g, average primary particle size: 43nm) Silica: ULTRASIL VN3 (N2SA: 175m) manufactured by Evonik Degussa. 2 / g, average primary particle diameter: 18nm) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa. Oil: VivaTec500 (TDAE oil) manufactured by H&R Co., Ltd. Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. Anti-aging agent 1: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Anti-aging agent 2: Nocrack RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: Beads of stearic acid manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (5% oil-containing powdered sulfur) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator: Noxellar CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0156] (Examples and Comparative Examples) According to the formulation shown in Tables 1 to 4, using a 1.7 L closed Banbury mixer, chemicals other than sulfur and vulcanization accelerators are kneaded for 5 minutes until the discharge temperature reaches 170°C to obtain a kneaded product. Next, using a two-roll open mill, sulfur and vulcanization accelerators are added to the obtained kneaded product and kneaded for 4 minutes until it reaches 105°C to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is extruded into the shape of the clinch portion using an extruder equipped with a die of a predetermined shape, and laminated together with the tread and other tire members to form an unvulcanized tire, and each test tire is manufactured by press vulcanization at 170°C for 12 minutes.

[0157] <Measurement of tanδ at 70°C and E* at 70°C> Each vulcanized rubber test piece is cut out to a size of 20 mm in length × 4 mm in width × 1 mm in thickness from the clinch portion of each test tire so that the tangential direction with respect to the tire circumferential direction is the long side and the normal direction with respect to the interface inside the tire width direction of the clinch portion is the thickness direction. For each rubber test piece, using an Implex series manufactured by GABO, tanδ and complex elastic modulus (E*) are measured under the conditions of a temperature of 70°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, and an elongation mode.

[0158] <Measurement of tanδ at 30°C> Each vulcanized rubber test piece is cut out to a size of 20 mm in length × 4 mm in width × 1 mm in thickness from the tread portion of each test tire so that the tangential direction with respect to the tire circumferential direction is the long side and the tire width direction is the thickness direction. For each rubber test piece, using an Implex series manufactured by GABO, tanδ is measured under the conditions of a temperature of 30°C, an initial strain of 5%, a dynamic strain of 1%, a frequency of 10 Hz, and an elongation mode.

[0159] <Measurement of M100> A 1mm thick, No. 7 dumbbell-shaped test specimen was prepared by cutting from the clinch section of each test tire so that the tangential direction to the tire's circumferential direction was the tensile direction. A tensile test was then performed in a 23°C atmosphere at a tensile speed of 3.3 mm / second in accordance with JIS K 6251 "Vulcanized rubber and thermoplastic rubber - Method for determining tensile test properties," and the stress at 100% elongation (M100) (MPa) was determined.

[0160] <Aesthetic performance after high-speed driving> Prototype tires, mounted on standard rims and filled to standard pressure, were fitted to all wheels of a domestically produced passenger car. After driving 10,000 km at 100 km / h, the aesthetic appearance of the tire's clinch area was evaluated in terms of color and the amount of cracking. The evaluation was performed using an integer value from 1 to 5 points, with higher scores indicating better aesthetic performance after high-speed driving. The total scores of 20 evaluators were calculated. The total scores of the control tires (Comparative Example 4 in Tables 1 and 2; Comparative Example 9 in Tables 3 and 4) were converted to a baseline value (100), and the evaluation results of each test tire were indexed and displayed in proportion to the total score.

[0161] [Table 1]

[0162] [Table 2]

[0163] [Table 3]

[0164] [Table 4]

[0165] <Embodiment> Examples of embodiments of the present invention are shown below.

[0166] [1] A tire having a tread portion and a clinch portion, wherein the maximum load capacity of the tire W L Ratio of tire weight G (kg) to (kg) (G / W L The tanδ(70°C tanδ) of the rubber composition constituting the clinch portion is 0.0150 or less, the clinch portion is made of a rubber composition containing rubber components and fillers, and the C The coefficient of elasticity (MPa) of the rubber composition constituting the clinch portion is 0.11 or less, and the complex modulus of elasticity (MPa) at 70°C (70°C E*) is 0.11 or less. C ) and Golden Week L The product of (70℃E* C ×G / W L A tire with a coefficient of 0.075 or higher. [2] G / W L The tire described in [1] above, wherein the ratio is 0.0140 or less. [3] Golden Week L The tire described in [1] above, wherein the ratio is 0.0135 or less. [4] 70℃E* C A tire as described in any of the above [1] to [3], having a pressure of 10.0 MPa or higher. [5] The modulus (M100) of the rubber composition constituting the clinch portion when stretched to 100% at 23°C C A tire as described in any of the above [1] to [4], having a pressure of 5.0 MPa or higher. [6] 70℃ tanδ C A tire as described in any of the above [1] to [5], wherein the ratio is 0.065 or less. [7] A tire according to any of [1] to [6] above, wherein when the cross-sectional width of the tire is Wt (mm) and the outer diameter is Dt (mm), Wt and Dt satisfy the following formula (1). 1800≦(Dt 2 ×π / 4) / Wt ≤ 2827.4 ···(1) [8] The virtual volume of the space occupied by the tire is V (mm²) 3 When V and Wt satisfy the following formula (2), the tire is one of the tires described in any of [1] to [7] above. [(V+1.5×10 7 ) / Wt] ≤ 2.88 × 10 5...(2) [9] The tire according to any one of [1] to [8] above, wherein the total content of isoprene-based rubber and butadiene rubber in the rubber component constituting the clinch portion is 80% by mass or more.

[10] The total content of filler in the rubber composition constituting the clinch portion is less than 65 parts by mass per 100 parts by mass of rubber component. A tire containing any of the above [1] to [9].

[11] The tire according to any one of [1] to

[10] above, wherein the rubber composition constituting the clinch portion contains 35 parts by mass or more of carbon black with an average primary particle diameter of 40 nm or more, per 100 parts by mass of rubber components.

[12] 70℃E* C 70°C tanδ (MPa) C Ratio (70℃ tanδ C / 70℃E* C A tire as described in any of the above [1] to

[11] , wherein the ratio is 0.004 or more and 0.008 or less.

[13] When the maximum thickness of the clinch portion is T (mm), T and 70°C tanδ C The product of (T × 70°C tanδ) C A tire as described in any of the above [1] to

[12] , wherein the ratio is less than 0.50.

[14] When the maximum thickness of the clinch portion is T (mm), T and M100 C Product of (MPa) and (T × M100) C A tire as described in any of the above [1] to

[13] , whose value is greater than 15.0.

[15] The tanδ(30℃tanδ) of the rubber composition constituting the tread portion at 30℃ T A tire as described in any of the above [1] to

[14] , wherein the ratio is 0.18 or less.

[16] 30°C tanδ relative to tire weight G (kg) T Ratio (30℃ tanδ T A tire as described in any of the above [1] to

[15] , wherein the / G) is greater than 0.010.

[17] The tread portion has a pair of shoulder land portions separated by a pair of outermost grooves located at the outermost end in the tire width direction, and one or more center land portions located between the pair of shoulder land portions, Sr is the total area of ​​the aforementioned land area, and S is the total area of ​​the aforementioned center land area. ce When S ce A tire as described in any of the above [1] to

[16] , wherein the / Sr is 0.35 or more and 0.80 or less.

[18] The tread portion has a pair of shoulder land portions separated by a pair of outermost grooves located at the outermost end in the tire width direction and one or more center land portions located between the pair of shoulder land portions, and at least one of the land portions has an opening area to the tread surface of 0.1 mm 2 15mm or more 2 A tire as described in any of the above [1] to

[17] , having one or more of the following small holes. [Explanation of symbols]

[0167] 1 tire 2 Tread section 3. Sidewall section 4. Clinch Section 5 Bead core 6 Bead Apex 7. Circuit breaker 8 rims 9 Circumferential groove 10 Land 11 Shoulder Track and Field Club 12 Center Track and Field Club 21 Shoulder lateral groove 22 Shoulder Sipes 23 Center Sipe 24 Small hole L Clinch section normal to the inner surface of the tire in the axial direction Wt Tire section width Ht Tire section height DT Tire Outer Diameter

Claims

1. A tire comprising a tread section and a clinch section, The maximum load capacity of the tire W L Ratio of tire weight G (kg) to (kg) (G / W) L ) is 0.0140 or less, The clinch portion is made of a rubber composition containing rubber components and fillers. The tanδ of the rubber composition constituting the clinch portion at 70°C (70°C tanδ C ) is 0.11 or less, The complex modulus of elasticity (MPa) at 70°C (70°C E*) of the rubber composition constituting the clinch portion C ) and G / W L The product of (70°C E*) C ×G / W L A tire in which the ratio is 0.075 or greater [wherein the above WL is a value calculated by the following formulas (3) and (4), where Wt (mm) is the tire section width measured in normal conditions, Ht (mm) is the tire section height, and Dt (mm) is the tire outer diameter. V (mm³) is the virtual volume of space occupied by the tire. The above tire section width Wt is the maximum width between the outer surfaces of the sidewalls in the above conditions, excluding patterns or letters on the tire sidewall if such patterns or letters are present. The aforementioned tire section height Ht is the distance from the bottom surface of the bead to the outermost surface of the tread, and is half the difference between the tire's outer diameter and the nominal rim diameter. V={(Dt / 2) 2 -(Dt / 2-Ht) 2}×π×Wt...(3) W L =0.000011×V+100 (4)

2. The aforementioned G / W L The tire according to claim 1, wherein the coefficient is 0.0135 or less.

3. The 70°C E* C is 10.0 MPa or more, the tire according to claim 1.

4. The modulus (M100) of the rubber composition constituting the clinch portion at 100% stretch at 23°C C A tire according to any one of claims 1 to 3, wherein the pressure is 5.0 MPa or more.

5. The 70°C tanδ C A tire according to any one of claims 1 to 3, wherein the ratio is 0.065 or less.

6. The tire according to any one of claims 1 to 3, wherein when the cross-sectional width of the tire is Wt (mm) and the outer diameter is Dt (mm), Wt and Dt satisfy the following formula (1). 1800≦(Dt 2 ×π / 4) / Wt≦2827.4 ・・・(1)

7. The virtual volume of the space occupied by the tire is V (mm²). 3 The tire according to any one of claims 1 to 3, wherein when V and Wt satisfy the following formula (2). [(V+1.5×10) 7 ) / Wt]≦2.88×� 5 ・・・(2)

8. The tire according to any one of claims 1 to 3, wherein the total content of isoprene-based rubber and butadiene rubber in the rubber component constituting the clinch portion is 80% by mass or more.

9. The total content of filler in the rubber composition constituting the clinch portion is less than 65 parts by mass relative to 100 parts by mass of rubber component. The tire according to any one of claims 1 to 3.

10. The tire according to any one of claims 1 to 3, wherein the rubber composition constituting the clinch portion contains 35 parts by mass or more of carbon black with an average primary particle diameter of 40 nm or more, per 100 parts by mass of rubber components.

11. The 70°C E* C (MPa) and the 70°C tanδ C Ratio (70°C tanδ C / 70℃E* C A tire according to any one of claims 1 to 3, wherein the coefficient of force is 0.004 or more and 0.008 or less.

12. When the maximum thickness of the clinch portion is T (mm), T and the 70°C tanδ C The product of (T × 70°C tanδ) C A tire according to any one of claims 1 to 3, wherein the coefficient of force is less than 0.

50.

13. When the maximum thickness of the clinch portion is T (mm), T and the M100 C Product of (MPa) and (T × M100) C The tire according to claim 4, wherein the ratio is greater than 15.

0.

14. The tanδ of the rubber composition constituting the tread portion at 30°C (30°C tanδ T A tire according to any one of claims 1 to 3, wherein the coefficient of force is 0.18 or less.

15. The 30°C tanδ relative to the tire weight G (kg) T Ratio (30°C tanδ T The tire according to claim 14, wherein the ratio of / G) is greater than 0.

010.

16. The tread portion has a pair of shoulder land portions separated by a pair of outermost grooves located at the outermost edge in the tire width direction, and one or more center land portions located between the pair of shoulder land portions. Sr is the total area of ​​the aforementioned land area, and S is the total area of ​​the aforementioned center land area. ce When this is the case, S ce A tire according to any one of claims 1 to 3, wherein Sr is 0.35 or more and 0.80 or less.

17. The tread portion has a pair of shoulder land portions separated by a pair of outermost grooves located at the outermost edge in the tire width direction, and one or more center land portions located between the pair of shoulder land portions. In at least one of the aforementioned land portions, the opening area to the tread surface is 0.1 mm 2 15mm or more 2 A tire according to any one of claims 1 to 3, having one or more of the following small holes.

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