tire

Abstract

To provide a tire that can improve grip performance when driving on uneven terrain. [Solution] A tire having a plurality of blocks on the tread portion, wherein the tread portion is made of a rubber composition containing rubber components, the land ratio of the tread portion is L (%), the tanδ of the rubber composition at 70°C is 70°Ctanδ, and the modulus of the rubber composition at 300% stretch at 75°C is 75°CM 300 When expressed as (MPa), L is less than 30 and 75℃M 300 The ratio is 5.0 or higher, and L, 70°C tanδ, and 75°C M 300 A tire that satisfies the following equation (1). (L 0.5 ×70℃ tanδ) / 75℃ M 300 ≥0.13 ···(1)

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] In Patent Document 1, a motorcycle tire having slits provided in crown blocks has been proposed in order to enhance grip performance during rough terrain driving.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, there is still room for improvement in grip performance during rough terrain driving.

[0005] An object of the present invention is to provide a tire capable of improving grip performance during rough terrain driving.

Means for Solving the Problems

[0006] The present invention relates to a tire having a tread portion, the tread portion being provided with a plurality of blocks, the tread portion being composed of a rubber composition containing a rubber component, the land ratio of the tread portion being L (%), the tan δ of the rubber composition at 70 ° C being 70 ° C tan δ, and the modulus at 300% elongation of the rubber composition at 75 ° C being 75 ° C M 300 (MPa), when L is less than 30, 75 ° C M 300 is 5.0 or more, and L, 70 ° C tan δ, and 75 ° C M 300 relate to a tire that satisfies the following formula (1). (L 0.5 × 70 ° C tan δ) / 75 ° C M 300≥0.13 ···(1)

Advantages of the Invention

[0007] According to the present invention, there is provided a tire capable of improving grip performance during travel on uneven ground.

Brief Description of the Drawings

[0008] [Figure 1] It is a tire meridian cross-sectional view according to an embodiment of the present invention. [Figure 2] It is a developed view of the tread portion according to this embodiment. [Figure 3] It is a cross-sectional view of the middle block and the shoulder block. [Figure 4] It is a perspective view of the block.

Mode for Carrying Out the Invention

[0009] A tire which is an embodiment of the present invention is a tire provided with a plurality of blocks in a tread portion, the tread portion is composed of a rubber composition containing a rubber component, the land ratio of the tread portion is L (%), the tanδ at 70°C of the rubber composition is 70°C tanδ, and the modulus at 300% elongation at 75°C of the rubber composition is 75°C M 300 (MPa), when L is less than 30, and 75°C M 300 is 5.0 or more, and L, 70°C tanδ, and 75°C M 300 is a tire that satisfies the following formula (1). (L 0.5 × 70°C tanδ) / 75°C M 300 ≥0.13 ···(1)

[0010] Although not intended to be bound by theory, in the tire of the present invention, as a mechanism for improving grip performance during travel on uneven ground, for example, it can be considered as follows.

[0011] (A) By setting the land ratio of the tread to less than 30%, it is possible to prevent a decrease in anchor friction caused by mud getting stuck in the gaps between the blocks. From this, it is thought that the overall grip can be improved by balancing anchor friction and hysteresis friction.

[0012] (B) Rubber composition constituting the tread section at 75°C 300 By setting the pressure to 5.0 MPa or higher, it is believed that anchor friction can be ensured.

[0013] (C) On the other hand, the rubber composition constituting the tread portion is 75°C M 300 When the value of is small, the blocks on the tread surface themselves can move flexibly during driving. This allows the blocks to follow the road surface, increasing hysteresis friction. Therefore, the land ratio R, the 70°C tanδ of the rubber composition constituting the tread, and the 75°C M of the rubber composition constituting the tread are considered. 300 It is thought that hysteresis friction can be increased by satisfying equation (1).

[0014] The cooperation of (A), (B), and (C) above makes it possible to achieve both anchor friction and hysteresis friction, thus improving grip performance on both soft and hard surfaces, and thus achieving the remarkable effect of improving grip performance on uneven surfaces.

[0015] When the height of the block is H (mm), it is preferable that H / 70℃tanδ is less than 95.

[0016] If the block height is high, external forces such as braking and driving can cause the blocks to tilt, reducing the contact area of ​​the block tread and raising concerns about a decrease in hysteresis friction. By setting H / 70°Ctanδ within the aforementioned range, and when the block height H is large, it is thought that the hysteresis necessary for grip can be secured by increasing the 70°Ctanδ value of the tread rubber.

[0017] The rubber composition preferably contains 50 parts by mass or more of silica per 100 parts by mass of rubber component.

[0018] By setting the silica content within the aforementioned range, it is believed that not only can grip performance on dry surfaces be improved, but a decrease in grip performance on wet surfaces can also be suppressed.

[0019] In this embodiment, when the crown portion is defined as 30% of the contact surface width of the tread portion with respect to the tire equator, it is preferable that the tire has 25 or more blocks on the circumference of the tire, where part or all of the blocks are located in the crown portion.

[0020] Increasing the number of blocks in the crown area is thought to increase the number of times the block edges scratch the road surface, making it easier to generate anchor friction.

[0021] The total amount of styrene in the aforementioned rubber component is preferably 30% by mass or more, from the viewpoint of promoting heat generation in the tread rubber and further improving grip performance.

[0022] The total amount of filler in the aforementioned rubber composition relative to 100 parts by mass of rubber component is preferably 100 parts by mass or more, from the viewpoint of promoting heat generation of the tread rubber and further improving grip performance.

[0023] The content of the resin component in the aforementioned rubber composition relative to 100 parts by mass of the rubber component is preferably 30 parts by mass or more, from the viewpoint of promoting heat generation of the tread rubber and further improving grip performance.

[0024] The amount of acetone extracted from the rubber composition is preferably 28% by mass or more, from the viewpoint of improving grip performance on uneven surfaces by increasing the proportion of softeners and other components in the rubber composition, which makes it easier for the tread rubber to follow the road surface.

[0025] The ash content of the aforementioned rubber composition is preferably 15% by mass or more, from the viewpoint of promoting heat generation of the tread rubber by increasing the proportion of fillers and other materials in the rubber composition, thereby further improving grip performance.

[0026] In this embodiment, the tire comprises a plurality of blocks including a plurality of shoulder blocks that form the tread edge and a plurality of middle blocks adjacent to the inner side of the shoulder blocks in the tire axial direction, and preferably, in a meridional cross-section including the tire rotation axis, the inner edge of the shoulder block protrudes radially outward from the virtual profile obtained by extending the profile of the tread surface of the middle block to the shoulder block. This is because the inner edge of the shoulder block can exert greater grip force.

[0027] When the protrusion amount of the inner edge is P (mm), the length of the tread surface of the shoulder block in the tire circumferential direction is A (mm), and the rubber hardness of the rubber composition constituting the shoulder block at 50°C is Hs, it is preferable that P × A × Hs is greater than 800.

[0028] By setting P×L×Hs within the aforementioned range, the shoulder block can deform appropriately. As a result, a large amount of ground pressure acts on the outer edge of the middle block in the tire axial direction, and it is believed that the middle block can also provide sufficient grip.

[0029] From the viewpoint of increasing frictional force against the road surface, it is preferable that a pair of sipes extending without intersecting each other are formed on the tread surface of any one of the aforementioned blocks.

[0030] The tire according to this embodiment is suitably used as a tire for motorcycles.

[0031] <Definition> The "tread portion" is the part that forms the contact surface of the tire, and in the radial cross-section of the tire, if the tire has components that form the tire skeleton using steel or textile materials such as belt layers, belt reinforcement layers, and carcass layers, the tread portion is the component that is radially outward from these components.

[0032] "Standard condition" refers to a state of no load where the tire is mounted on a standard rim and filled with air at the standard internal pressure. Unless otherwise specified, tires in the standard condition should be used.

[0033] Unless otherwise specified, the "dimensions of each part of the tire" refer to values ​​that are determined in the normal state for those visible on the outer surface of the tire, while those located inside the tire or on the cut surface of the tire refer to values ​​that are determined, for example, by cutting the tire in a plane including the tire's axis of rotation and holding the cut tire piece within the rim width of the normal rim.

[0034] A "standard rim" refers to the rim specified for each tire within the standards system that the tire is based on. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." Refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. In the case of a tire not specified in the above standards, it refers to the narrowest rim width among the smallest diameter rims that can be mounted on that tire and that can maintain internal pressure (i.e., do not cause air leakage between the rim and tire).

[0035] "Regular internal pressure" refers to the air pressure specified for each tire in the standards system, including the standard on which the tire is based. For example, for JATMA it refers to "maximum air pressure," for ETRTO it refers to "INFLATION PRESSURE," and for TRA it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims, refer to JATMA, ETRTO, and TRA in that order, and if there is an applicable size at the time of reference, follow that standard. In the case of tires not specified in the above standards, it refers to the regular internal pressure (but at least 250kPa) of another tire size (but specified in the standard) that is listed with the aforementioned regular rim as the standard rim. If multiple regular internal pressures of 250kPa or higher are listed, refer to the lowest value among them.

[0036] "Regular load (kg)" refers to the load specified for each tire in the standard system that the tire is based on. For example, for JATMA it is "Maximum Load Capacity," for ETRTO it is "LOAD CAPACITY," and for TRA it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims and regular in-tire pressure, refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. For tires not specified in the above standards, the maximum load capacity (kg) is calculated separately. L This is considered the normal load.

[0037] "Maximum load capacity W L The weight (kg) is calculated using the following formula: "V" is the virtual volume of the tire (mm²). 3), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the height of the tire's cross-section in the radial direction in a plane containing the tire's axis of rotation (mm), and "Wt" is the width of the tire's cross-section in the normal state (mm). Ht can be calculated by (Dt-R) / 2, where R is the rim diameter of the tire. Wt is the value obtained by removing any patterns or letters on the tire's sidewall. Note that the maximum load capacity is synonymous with the normal load mentioned above.

number

[0038] In the present invention, "block" refers to a region demarcated by a plurality of grooves formed in the tread portion, or a region closed by a plurality of grooves formed in the tread portion and the tread contact edge. Here, in the present invention, "groove" refers to a groove formed in the tread portion on the tread surface with an opening width greater than 5.0 mm.

[0039] The "Land ratio L(%)" is calculated using the following formula. (Land ratio L) = [(Surface area of ​​the block tread) / {(Arc length of the tread in the tire axis direction) × (Circumferential length of the tire centerline)}] × 100

[0040] The "circumferential length of the tire's centerline" is measured, for example, by placing a measuring tape along the tire's centerline.

[0041] The "arc length of the tread in the tire axial direction" is the arc length between the pair of tread contact edges Te in Figure 1. The arc length of the tread in the tire axial direction can be calculated, for example, by rotating the tire 72 degrees at a time and measuring at a total of five locations, and then taking the average of the obtained arc lengths.

[0042] If the inner edge of a shoulder block protrudes radially outward from a virtual profile obtained by extending the profile of the middle block's tread surface to the shoulder block, the arc length of the tread portion in the tire axial direction can be calculated, for example, as follows: First, measure the distance from the outer edge of the tread surface of one middle block in the tire axial direction to the outer edge of the tread surface of the other middle block in the tire axial direction. Next, create a pair of virtual profiles by extending the profiles of the middle block's tread surfaces to a pair of tread contact points Te such that they have the same radius of curvature as the distance between the outer edges of the tread surfaces of the middle blocks in the tire axial direction, and calculate the length of each virtual profile. Then, by adding the distance between the outer edges of the tread surfaces of the middle blocks in the tire axial direction and the length of the virtual profiles, the arc length of the tread portion in the tire axial direction can be calculated.

[0043] In this invention, "sipe" refers to a recessed portion formed on the tread surface of a tire block, extending inward in the radial direction of the tire, with a width of less than 5.0 mm perpendicular to the longitudinal direction of the groove on the tread surface of the block. The "surface area of ​​the block tread" does not include sipes.

[0044] "Block height H" is calculated by determining the deepest groove depth of the grooves that demarcate each block and taking the average value.

[0045] The "crown section" is the area that covers 30% of the contact patch width of the tread, centered on the tire's equator.

[0046] The "number of blocks present in the crown area" refers to the total number of blocks, some or all of which are present in the crown area, on the circumference of the tire. In Figure 2, not only the crown black 13 but also the middle block 12 can be considered blocks present in the crown area.

[0047] "The length L of the tread surface of the shoulder block in the tire circumference direction" refers to the maximum length of the tread surface of the shoulder block in the tire circumference direction.

[0048] "Rubber components of a rubber composition" refer to components that contribute to crosslinking within a rubber composition, and generally have a weight-average molecular weight (Mw) of 10,000 or more.

[0049] A "plasticizer" is a material that imparts plasticity to rubber components and is extracted from rubber compositions using acetone. This definition includes both liquid plasticizers at 25°C and solid plasticizers at 25°C. However, it excludes waxes and stearic acid commonly used in the tire industry.

[0050] "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 components. 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.

[0051] <Measurement method> "70℃tanδ" is the loss tangent measured using a dynamic viscoelasticity measuring instrument (e.g., GABO's Iplexer series) under the conditions of a temperature of 70℃, a frequency of 10Hz, an initial strain of 10%, a dynamic strain of ±1%, and the extension mode. The sample used for this measurement is a vulcanized rubber composition measuring 20mm in length, 4mm in width, and 1mm in thickness. When preparing the sample by cutting it from a tire, it should be cut from the tread portion so that the tire circumference is the longer side and the tire radius is the thickness direction.

[0052] "75℃M 300 " is the modulus (tensile stress) at 300% stretch in the grain direction (the rolling direction when forming a rubber sheet by extrusion or shearing), measured under conditions of 3.3 mm / second at a tensile speed in a 75°C atmosphere, in accordance with JIS K 6251:2017, and is measured in MPa. The sample used for this measurement is a 1 mm thick, dumbbell-shaped No. 7 vulcanized rubber test piece. When preparing by cutting from a tire, cut from the tire tread so that the tire circumference is the tensile direction and the tire radius is the thickness direction.

[0053] "Rubber hardness Hs at 50°C" is Shore hardness measured at 50°C using a durometer type A, in accordance with JIS K 6253-3:2012. Each test specimen is prepared by cutting from the shoulder block so that the tire radius direction is the thickness direction, and the measurement is performed by pressing the measuring instrument against the sample from the tire contact surface side of each test specimen.

[0054] The "Acetone Extraction Amount (AE)" is calculated by immersing each vulcanized rubber test piece in acetone for 72 hours in accordance with JIS K 6229 to extract soluble components, measuring the mass of each test piece before and after extraction, and using the following formula. Acetone extraction amount (mass %) = {(mass of rubber test piece before extraction - mass of rubber test piece after extraction) / (mass of rubber test piece before extraction)} × 100

[0055] "Ash content" refers to the ratio of the total mass of non-combustible components (ash) in the rubber composition to the total mass of the rubber composition. "Ash content" can be determined by heating each test specimen in a nitrogen atmosphere at 650°C for 4 hours in accordance with JIS K 6226-1:2003, measuring the mass of each test specimen before and after heating, and using the following formula. (Ash content (mass %)) = (Mass of test specimen after heating / Mass of test specimen before heating) × 100

[0056] The glass transition temperature (Tg) of SBR is determined in accordance with JIS K 6229:2015 by removing the spreading oil using acetone, and then determining the pure SBR content by differential scanning calorimetry (DSC) in accordance with JIS K 7121:2012.

[0057] "Styrene content" can be determined by pyrolysis gas chromatography or NMR measurement. 1 H-NMR and 13It is calculated by 13C-NMR. Unlike physical properties such as the complex modulus (E*), the amount of components such as "styrene content" has a true value that does not depend on the measurement method, so it is preferable to use a measurement method that is as accurate as possible. In this specification, "pyrolysis gas chromatography" refers to a method in which a sample is heated by a pyrolysis apparatus, the individual components contained in the gas phase components produced by this heating are separated by a separation column, and each isolated component is analyzed. Styrene content is applied to rubber components that have repeating units (styrene units) derived from styrene, such as SBR.

[0058] "Vinyl content (amount of 1,2-bonded butadiene units)" can be determined by pyrolysis gas chromatography or NMR measurement. 1 H-NMR and 13 It is calculated by 13C-NMR. Similar to "styrene content," a true value exists for "vinyl content" that is independent of the measurement method, so it is preferable to use a measurement method that is as accurate as possible. Vinyl content is applied to rubber components having repeating units derived from butadiene, such as SBR and BR.

[0059] "Cis content (amount of cis-1,4-bonded butadiene units)" is determined by infrared absorption spectroscopy or NMR measurement in accordance with JIS K 6239-2:2017. 1 H-NMR and 13 This value is measured by 13C-NMR and is applied to rubber components having repeating units derived from butadiene, such as BR. Similar to "styrene content," a true value exists for "cis content" that is independent of the measurement method; therefore, it is preferable to use the most accurate measurement method possible. Cis content is applied to rubber components having repeating units derived from butadiene, such as SBR and BR.

[0060] "Total styrene content in rubber components" refers to the total amount of styrene units contained in 100% by mass of the rubber components (by mass%). For each rubber component, the value obtained by multiplying the styrene content (by mass%) by the mass fraction in the rubber components is calculated, and these values ​​are then summed up. Specifically, it is calculated using Σ(styrene content (by mass%) of each styrene-containing rubber × content (by mass%) of each styrene-containing rubber in the rubber components / 100). For example, if the rubber components consist of a first SBR (styrene content: 25% by mass) at 20% by mass, a second SBR (styrene content: 27.5% by mass) at 30% by mass, and BR at 50% by mass, the total styrene content in the rubber components is approximately 13.3% by mass (= (25 × 20 / 100) + (27.5 × 30 / 100) + (0 × 10 / 100)).

[0061] The "weight-average molecular weight (Mw)" can be determined by converting the measured value using gel permeation chromatography (GPC) (for example, the GPC-8000 series manufactured by Tosoh Corporation, with a differential refractometer as the detector and TSKgel® SuperMultiporeHZ-M column manufactured by Tosoh Corporation) to a standard polystyrene equivalent. This method is applicable, for example, to SBR, BR, plasticizers, etc.

[0062] The nitrogen adsorption specific surface area (N2SA) of carbon black is measured in accordance with JIS K 6217-2:2017.

[0063] The nitrogen adsorption specific surface area (N2SA) of silica is measured by the BET method in accordance with ASTM D3037-93.

[0064] The "average primary particle diameter" is a value determined by photographing particles with a transmission or scanning electron microscope and taking the arithmetic mean of the particle diameters of 400 particles. If the particle is spherical, the diameter of the sphere is used as the particle diameter; if it is not spherical, the equivalent diameter of a circle (the positive square root of {4 × (particle area) / π}) is calculated from the microscope image and used as the particle diameter. The average primary particle diameter is applied to silica, carbon black, and other materials.

[0065] The "softening point of the resin component" is the temperature at which the sphere descends when the softening point specified in JIS K 6220-1:2015 7.7 is measured using a ring-type softening point measuring device.

[0066] 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.

[0067] [tire] The tire according to this embodiment has a tread portion made of the rubber composition described below, and the tread portion is provided with a plurality of blocks. The tire according to one embodiment of the present invention will be described below with reference to the drawings, but the drawings are for illustrative purposes only. Furthermore, the embodiments shown below are merely examples.

[0068] Figure 1 is a meridian cross-sectional view of the tire 1 according to this embodiment, including the tire rotation axis. As shown in Figure 1, the tire 1 comprises a tread portion 2, a sidewall portion 3, a bead portion 4, a carcass layer 6, and a belt layer 7. The bead portion 4 includes a bead core 5. The tread portion 2 may be a tread portion consisting of a single rubber layer, or it may be a tread portion having a cap rubber layer that constitutes the tread surface, and one or more rubber layers existing between the cap rubber layer and the belt layer 7.

[0069] The outer surface between the two tread contact edges Te of the tread section 2 is curved in an arc shape, convex outward in the radial direction of the tire, and is provided with multiple blocks 10 that rise from the groove bottom surface 9.

[0070] The block height H is preferably 5 mm or more, preferably 8 mm or more, more preferably 11 mm or more, and particularly preferably 14 mm or more. Furthermore, the block height H is preferably 50 mm or less, more preferably 45 mm or less, and even more preferably 40 mm or less.

[0071] Figure 2 is an unfolded view of the tread portion 2. As shown in Figure 2, the block 10 includes, for example, a shoulder block 11, a middle block 12, and a crown block 13, but is not limited to this configuration. The crown block 13 is located on the crown portion. The shoulder block 11 forms the tread contact end Te. The middle block 12 is adjacent to the shoulder block 11 on the axial side of the tire.

[0072] The shape of the block's tread is not limited to a rectangle as shown in Figure 2; it may also be a polygon other than a rectangle. Furthermore, the shape of the block's tread may include curves.

[0073] The number of blocks present in the crown portion is preferably 15 or more, more preferably 20 or more, even more preferably 25 or more, and particularly preferably 28 or more. On the other hand, the number of blocks present in the crown portion is preferably 50 or less, more preferably 45 or less, even more preferably 40 or less, and particularly preferably 35 or less.

[0074] The length A of the tread surface of the shoulder block 11 in the tire circumferential direction is preferably 8.0 mm or more, more preferably 10 mm or more, even more preferably 12 mm or more, and particularly preferably 14 mm or more. Furthermore, A is preferably 20 mm or less, and more preferably 18 mm or less.

[0075] The land ratio R of the tread portion 2 is less than 30%, preferably less than 28%, more preferably less than 26%, more preferably less than 24%, and particularly preferably less than 22%. The land ratio L is preferably greater than 10%, more preferably greater than 12%, even more preferably greater than 14%, and particularly preferably greater than 16%.

[0076] From the viewpoint of increasing frictional force against the road surface, it is preferable that a pair of sipes extending without intersecting each other be formed on the tread surface of one of the multiple blocks. In Figure 2, a pair of sipes extending without intersecting each other are formed on the tread surface of the shoulder block 11. The sipes 14 extend in a straight line, but are not limited to this configuration, and may extend in a sinusoidal or zigzag shape, for example.

[0077] In Figure 2, the length of the shoulder block 11 in the tire circumferential direction gradually increases toward the inward direction in the tire axial direction. As a result, the shoulder block 11 has a trapezoidal tread surface.

[0078] It is preferable that the width W1 of the tread surface of the shoulder block 11 in the axial direction of the tire is smaller than the width W2 of the tread surface of the middle block 12 in the axial direction of the tire. By setting W2 > W1, the shoulder block 11 becomes more easily deformable, and it is thought that the contact pressure acting on the middle block 12 can be increased.

[0079] Figure 3 is an enlarged cross-sectional view of the middle block 12 and the shoulder block 11. In Figure 3, the tread profile of the middle block 12 is an arc shape that is convex outward in the radial direction of the tire. The inner edge 20 of the tread of the shoulder block 11 in the axial direction of the tire protrudes radially outward more than the virtual profile 18 obtained by extending the tread profile of the middle block 12 to the shoulder block 11. This is thought to allow the inner edge 20 of the shoulder block 11 to exert greater grip force.

[0080] The amount P of the inner edge 20 protruding from the virtual profile 18 is preferably 0.5 mm or more, more preferably 1.0 mm or more, and even more preferably 1.5 mm or more. On the other hand, P is preferably 5.0 mm or less, more preferably 4.5 mm or less, even more preferably 4.0 mm or less, and particularly preferably 3.5 mm or less.

[0081] The rubber hardness Hs of the rubber composition constituting the shoulder block 11 at 50°C is preferably 45 or higher, more preferably 48 or higher, even more preferably 50 or higher, and particularly preferably 53 or higher. On the other hand, Hs is preferably 80 or lower, more preferably 75 or lower, and even more preferably 70 or lower. The rubber hardness Hs can be appropriately adjusted depending on the type and content of the rubber components, fillers, plasticizers, vulcanizing agents, vulcanization accelerators, etc., as described below. For example, it tends to increase by increasing the filler content.

[0082] The product of P, AL, and Hs (P × A × Hs) is preferably greater than 600, more preferably greater than 700, even more preferably greater than 800, even more preferably greater than 850, even more preferably greater than 900, and particularly preferably greater than 950. By setting P × L × Hs within the above range, the shoulder block 11 can be deformed appropriately. As a result, a large contact pressure acts on the outer edge 21 in the tire axial direction of the tread surface of the middle block 12, and it is thought that the middle block 12 can also exhibit sufficient grip. On the other hand, the upper limit of P × A × Hs is not particularly limited, but it is preferably less than 5000, more preferably less than 4000, even more preferably less than 3000, and particularly preferably less than 2000.

[0083] Figure 4 shows a perspective view of the crown block 13 as an example of the configuration of block 10. The crown block 13 includes a tread surface 29 and side surfaces 30. The side surfaces 30 include, for example, a first side surface 31 located on the leading side of the tread surface 29 in the tire rotation direction RD, a second side surface 32 located on one side of the tread surface 29 in the tire axial direction, a third side surface 33 located on the other side of the tread surface 29 in the tire axial direction, and a fourth side surface 34 located on the trailing side of the tread surface 9 in the tire rotation direction RD. A similar configuration can also be adopted for the middle block 12.

[0084] The amount of acetone extracted from the rubber composition constituting the tread portion is preferably 20% by mass or more, more preferably 22% by mass or more, even more preferably 24% by mass or more, even more preferably 26% by mass or more, and particularly preferably 28% by mass or more. On the other hand, the amount of acetone extracted is preferably 45% by mass or less, more preferably 42% by mass or less, even more preferably 39% by mass or less, and particularly preferably 37% by mass or less. When the tread portion 2 consists of two or more layers, "rubber composition constituting the tread portion" refers to the rubber composition constituting the cap rubber layer (the same applies hereinafter).

[0085] The ash content of the rubber composition constituting the tread portion is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, even more preferably 1.5% by mass or more, even more preferably 5.0% by mass or more, even more preferably 10% by mass or more, and particularly preferably 15% by mass or more. On the other hand, the ash content is preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less.

[0086] From the viewpoint of grip performance, the 70°C tanδ of the rubber composition constituting the tread portion is preferably 0.20 or higher, more preferably 0.25 or higher, even more preferably 0.30 or higher, and particularly preferably 0.33 or higher. On the other hand, from the viewpoint of durability performance, it is preferably 0.60 or lower, more preferably 0.55 or lower, even more preferably 0.50 or lower, and particularly preferably 0.45 or lower.

[0087] In this embodiment, 70°C tanδ is an indicator of the exothermic properties of the rubber composition. 70°C tanδ can be appropriately adjusted depending on the type and content of the rubber components, fillers, plasticizers, vulcanizing agents, vulcanization accelerators, etc., as described below. For example, it tends to increase with increasing the content of fillers (carbon black, silica, etc.) and plasticizers.

[0088] The rubber composition constituting the tread section is 75°M 300From the viewpoint of ensuring anchor friction, the pressure should be 5.0 MPa or higher, preferably 5.5 MPa or higher, more preferably 6.0 MPa or higher, even more preferably 6.5 MPa or higher, even more preferably 7.0 MPa or higher, even more preferably 7.5 MPa or higher, and particularly preferably 8.0 MPa or higher. On the other hand, 75°C M 300 From the viewpoint of ensuring anchor friction, a pressure of 16.0 MPa or less is preferred, 15.0 MPa or less is more preferred, 14.0 MPa or less is even more preferred, and 13.0 MPa or less is particularly preferred.

[0089] Note: 75℃M 300 and 100℃M 300 This can be adjusted as appropriate by varying the types and amounts of rubber components, fillers, plasticizers, vulcanizing agents, vulcanization accelerators, etc., as described below. For example, it tends to increase when the amount of fillers or vulcanizing agents is increased.

[0090] The tire according to this embodiment has the above-mentioned R, 70°C tanδ, and 75°C M 300 * satisfies equation (1) below. (R 0.5 ×70℃ tanδ) / 75℃ M 300 ≥0.13 ···(1)

[0091] In this embodiment, (R 0.5 ×70℃ tanδ) / 75℃ M 300 The value of is preferably 0.14 or higher, and more preferably 0.15 or higher. On the other hand, (R 0.5 ×70℃ tanδ) / 75℃ M 300 There is no particular upper limit to the value of , but it is preferably 1.50 or less, more preferably 1.20 or less, even more preferably 1.00 or less, even more preferably 0.80 or less, even more preferably 0.60 or less, and particularly preferably 0.40 or less.

[0092] From the viewpoint of the effects of the present invention, H / 70℃tanδ is preferably less than 105, more preferably less than 95, even more preferably less than 85, even more preferably less than 75, even more preferably less than 70, and particularly preferably less than 65. On the other hand, the lower limit of H / 70℃tanδ is not particularly limited, but is preferably greater than 10, more preferably greater than 15, and even more preferably greater than 20.

[0093] [Rubber composition] The rubber composition constituting the tread portion according to this embodiment (hereinafter referred to as the rubber composition according to this embodiment) contains rubber components, and all of them use the raw materials described below to obtain the required 70°C tanδ and 75°C M 300 It can be manufactured according to the above. The rubber composition according to this embodiment will be described below.

[0094] <Rubber components> The rubber component according to this embodiment preferably contains a diene rubber such as styrene-butadiene rubber (SBR), and may further contain a diene rubber other than SBR, such as butadiene rubber (BR). Alternatively, the rubber component may consist solely of SBR.

[0095] Examples of diene rubbers other than SBR include isoprene rubber, butadiene rubber (BR), styreneisoprene rubber (SIR), styreneisoprenebutadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). These diene rubbers may be modified rubbers treated with modifying groups that can interact with fillers such as carbon black or silica, or they may be hydrogenated rubbers in which some of the unsaturated bonds have been hydrogenated. Diene rubbers may be used alone or in combination of two or more. Furthermore, as the diene rubber, stretched rubber that has been pre-stretched using the plasticizers described later may be used.

[0096] The content of diene rubber in the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Alternatively, the rubber component may consist solely of diene rubber.

[0097] (SBR) SBR is not particularly limited, but 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, branched structures, etc.). 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.

[0098] As for SBR, oil-expanded SBR can be used, or non-oil-expanded SBR can be used. When oil-expanded SBR is used, the amount of oil expanded in the SBR, that is, the amount of oil-expanding oil contained in the SBR, is preferably 10 to 50 parts by mass per 100 parts by mass of rubber solids in the SBR.

[0099] Examples of SBRs that can be used in this embodiment include those commercially available from companies such as JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Corporation, Asahi Kasei Corporation, ZS Elastomers Co., Ltd., and ARLANXEO.

[0100] From the viewpoint of the effects of the present invention, the styrene content of SBR is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, even more preferably 35% by mass or more, and particularly preferably 39% by mass or more. On the other hand, the styrene content of SBR is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. The styrene content of SBR is measured by the measurement method described above.

[0101] From the viewpoint of the effects of the present invention, the vinyl content of SBR is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more. Furthermore, the vinyl content of SBR is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less. The vinyl content of SBR is measured by the measurement method described above.

[0102] From the viewpoint of the effects of the present invention, the glass transition temperature (Tg) of SBR is preferably -50°C or higher, more preferably -40°C or higher, and even more preferably -30°C or higher. Furthermore, the Tg of SBR is preferably 10°C or lower, more preferably 0°C or lower, and even more preferably -10°C or lower. The Tg of SBR is measured by the measurement method described above.

[0103] From the viewpoint of grip performance, the weight-average molecular weight (Mw) of SBR is preferably 200,000 or more, more preferably 250,000 or more, and even more preferably 300,000 or more. Furthermore, from the viewpoint of crosslinking uniformity, the Mw of SBR is preferably 2,000,000 or less, more preferably 1,800,000 or less, and even more preferably 1,500,000 or less. The Mw of SBR is measured by the measurement method described above.

[0104] From the viewpoint of the effects of the present invention, the SBR content in the rubber component is preferably more than 40% by mass, more preferably more than 50% by mass, even more preferably more than 60% by mass, even more preferably more than 70% by mass, and particularly preferably more than 80% by mass. On the other hand, there is no particular upper limit to the content.

[0105] (BR) While there are no particular limitations on the type of BR used, common types used in the tire industry can be used, such as 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), and modified BR (high-cis modified BR, low-cis modified BR). These BRs may be used individually or in combination of two or more types.

[0106] High-cis BR can be commercially available from companies such as Nippon Zeon Co., Ltd., UBE Corporation, and JSR Corporation. Including high-cis BR can improve low-temperature properties and wear resistance. The cis content of high-cis BR is preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably more than 97 mol%. The cis content of BR is measured by the measurement method described above.

[0107] From the viewpoint of wear resistance, the weight-average molecular weight (Mw) of BR is preferably 300,000 or more, more preferably 350,000 or more, and even more preferably 400,000 or more. From the viewpoint of crosslinking uniformity, it is preferably 2,000,000 or less, and more preferably 1,000,000 or less. The Mw of BR is measured by the measurement method described above.

[0108] From the viewpoint of the effects of the present invention, the BR content in the rubber component is preferably less than 50% by mass, more preferably less than 40% by mass, even more preferably less than 30% by mass, even more preferably less than 20% by mass, and even more preferably less than 10% by mass. A rubber component without BR is also acceptable.

[0109] (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.

[0110] NR is not particularly limited and can be any that is common in the tire industry, such as SIR20, RSS#3, TSR20, etc.

[0111] From the viewpoint of the effects of the present invention, the content of isoprene-based rubber in the rubber component is preferably less than 350% by mass, more preferably less than 40% by mass, even more preferably less than 30% by mass, even more preferably less than 20% by mass, and even more preferably less than 10% by mass. The rubber component may also be one that does not contain isoprene-based rubber.

[0112] From the viewpoint of heat generation, the total styrene content in the rubber component is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, even more preferably 35% by mass or more, and particularly preferably 39% by mass or more. Furthermore, the total styrene content in the rubber component is preferably 55% by mass or less, more preferably 52% by mass or less, and even more preferably 48% by mass or less.

[0113] (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. Other rubber components besides diene rubber can 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. In addition to the above rubber components, known thermoplastic elastomers may or may not be included. Other rubber components may be used individually or in combination of two or more.

[0114] (Rubber components synthesized from recycled and biomass-derived raw materials) Monomers, which are the constituent units of synthetic rubbers such as IR, SBR, and BR, may be derived from underground resources such as petroleum and natural gas, or they may be recycled from rubber products such as tires or non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, but include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl compounds. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds are not particularly limited, but include styrene. In particular, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0115] The method for producing recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Furthermore, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and pressure, decomposed by microwaves, or extracted after mechanical grinding.

[0116] Furthermore, the monomers that make up polymers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural, forestry, and fishery products, sugars, wood chips, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha.

[0117] The biomass-derived monomer (biomass monomer) is not particularly limited and includes biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. Examples of the aromatic vinyl compound are not particularly limited but include styrene. Furthermore, the method for producing the biomass monomer is not particularly limited and includes, for example, biological and / or chemical and / or physical transformations of plants and animals. Typical biological transformations include fermentation by microorganisms, while chemical and / or physical transformations include those by catalysts, high heat, high pressure, electromagnetic waves, critical liquids, and combinations thereof.

[0118] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compounds. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0119] Whether the raw materials for a polymer are biomass-derived can be determined by measuring pMC (percent Modern Carbon) according to ASTM D6866-10. pMC refers to the percentage of modern standard reference carbon. 14 Sample relative to C concentration 14 This is a ratio of C concentrations and is used as an indicator of the biomass ratio of a compound. The significance of this value is described below.

[0120] 1 mole of carbon atoms (6.02 × 10⁻¹⁰) 23 (Each) contains approximately 6.02 × 10¹⁶ atoms, which is about one trillionth of the amount of carbon atoms in a normal atom. 11 individual 14 C exists. 14The half-life of C is 5730 years. 14 C is decreasing regularly. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been fixed after more than 226,000 years have passed since atmospheric carbon dioxide was taken in and fixed by plants, etc., C was initially included in these as well. 14 All elements of C have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas are no longer viable. 14 It contains absolutely no element C. Therefore, chemical substances produced using these fossil fuels as raw materials also contain C. 14 It contains absolutely no element C.

[0121] on the other hand, 14 C is continuously produced when cosmic rays undergo nuclear reactions in the atmosphere. Therefore, 14 In the Earth's atmospheric environment, carbon (C) is produced in a state where its decrease due to radioactive decay and its production through nuclear reactions are in equilibrium. 14 The amount of C is constant. Therefore, the amount of biomass resource-derived substances currently circulating in the environment 14 As mentioned above, the carbon concentration is approximately 1 × 10¹⁶ of the total carbon atoms. -12 These values ​​are approximately in mole percent. Therefore, the difference between these values ​​can be used to calculate the biomass ratio in a given compound.

[0122] this 14 C is typically measured as follows: Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 Perform measurement C). In the measurement, 14 As a modern standard reference for the concentration of C, the amount of cyclic carbon in nature as of 1950 14The C concentration will be used. The specific standard material will be the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific radioactivity of carbon in this oxalic acid (per gram of carbon) will be used. 14 The radioactivity intensity of C is separated by carbon isotope, 13 The standard value is obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date. 14 This value is used as the C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0123] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal conditions it will often not reach 100, and will show a value of approximately 110 pMC. On the other hand, regarding chemical substances derived from fossil fuels such as petroleum, 14 When the C concentration is measured, it will show a value of approximately 0 pMC (for example, 0.3 pMC). This value corresponds to the aforementioned biomass ratio of 0%.

[0124] Based on the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in rubber compositions is preferable from an environmental protection standpoint.

[0125] <Filler> The rubber composition according to this embodiment preferably contains a filler. The filler preferably contains carbon black, and more preferably contains carbon black and silica. Furthermore, the filler may consist solely of carbon black, or solely of carbon black and silica.

[0126] (Carbon Black) The carbon black used is not particularly limited and includes N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw materials for carbon black may be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by thermal decomposition of waste tires. The manufacturing method for carbon black may be combustion such as the furnace method, hydrothermal carbonization (HTC), or thermal decomposition of methane such as the thermal black method. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbia Carbon Corporation, etc. Carbon black may be used alone or in combination of two or more types.

[0127] In addition to the above, from the perspective of life cycle assessment, carbon black made from biomass materials such as lignin, or recycled carbon black refined by thermal decomposition of carbon black-containing products such as tires, may also be used as carbon black.

[0128] In this specification, "recycled carbon black" refers to carbon black obtained by crushing used tires and other products containing carbon black, and calcining the crushed material, wherein, according to the thermogravimetric method compliant with JIS K 6226-2:2003, when oxidative combustion occurs by heating in air, the proportion of the mass of ash (ash content), which is the component that does not burn, is 13% by mass or more. In other words, the proportion of the mass (carbon content) lost due to the aforementioned oxidative combustion of recycled carbon black is 87% by mass or less. Recycled carbon black may also be represented as rCB.

[0129] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975, which refers to "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, states that it can be obtained by the pyrolysis of organic materials at 550-800°C in the absence of oxygen, or by vacuum pyrolysis at relatively low temperatures (

[0027] ). Carbon black obtained from such pyrolysis processes usually lacks functional groups on its surface, as referred to in

[0004] of Japanese Patent Publication No. 6856781 (Comparison of Surface Morphology and Chemistry of Pyrolysis Carbon Black and Commercial Carbon Black, Powder Technology 160 (2005) 190-193).

[0130] Recycled carbon black may lack functional groups on its surface, or it may be treated to include functional groups on its surface. Treatment to include functional groups on the surface of recycled carbon black can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. In addition, in Japanese Patent Publication No. 6856781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes carbon black treated to include functional groups on its surface.

[0131] Recycled carbon black can be purchased from companies such as Strable Green Carbon and LD Carbon.

[0132] The nitrogen adsorption specific surface area (N2SA) of carbon black is 50m² from the perspective of reinforcing properties. 2 Preferably 80m / g or more.2 More preferably 100m / g or more, 2 More preferably 110m / g or more. 2 A value exceeding / g is particularly preferred. Furthermore, from the viewpoint of heat generation and processability, 250m 2 Preferably less than / g, 220m 2 More preferably less than / g, 190m 2 A value of less than / g is even more preferable. The N2SA of carbon black is measured by the measurement method described above.

[0133] The average primary particle diameter of carbon black is preferably 36 nm or less, more preferably 32 nm or less, even more preferably 28 nm or less, and particularly preferably 24 nm or less. The lower limit of the average primary particle diameter is not particularly limited, but is preferably 5 nm or more, more preferably 8 nm or more, and even more preferably 10 nm or more.

[0134] From the viewpoint of the effects of the present invention, the carbon black content per 100 parts by mass of rubber component is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and particularly preferably 50 parts by mass or more. Furthermore, the content is preferably 150 parts by mass or less, more preferably 140 parts by mass or less, even more preferably 130 parts by mass or less, and particularly preferably 120 parts by mass or less.

[0135] (silica) The silica used is not particularly limited, and common silica used in the tire industry can be used, such as silica prepared by a dry process (anhydrous silica) or silica prepared by a wet process (hydrated silica). The raw material for silica is not particularly limited, and may be a mineral-derived raw material such as quartz, or a biological-derived raw material such as rice husks (for example, silica made from biomass materials such as rice husks), or silica recycled from silica-containing products may be used. Among these, hydrated silica prepared by a wet process is preferred because it contains a large number of silanol groups. Silica may be used alone or in combination of two or more types.

[0136] Silica derived from biomass materials can be obtained, for example, by extracting silicates from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then using these silicates to react with sulfuric acid in the same way as conventional wet silica, the precipitate of silicon dioxide is filtered, washed with water, dried, and pulverized.

[0137] The silica recycled from silica-containing products can be, for example, silica recovered from products containing silica such as semiconductors and other electronic components, tires, desiccants, and diatomaceous earth and other filter materials. The recovery method is not particularly limited and can include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from semiconductors and other electronic components or tires is preferred.

[0138] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol.6, pp.216-222, etc.). Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0139] The nitrogen adsorption specific surface area (N2SA) of silica is 110 m², from the perspective of low fuel consumption and wear resistance. 2 Preferably 130m / g or more. 2 More preferably 150m / g or more, 2 More preferably 170m / g or more. 2 A value of 350m or more is particularly preferred. Furthermore, from the viewpoint of low fuel consumption and processability, 350m 2 Preferably less than / g, 300m 2 More preferably less than / g, 250m 2 A value of less than / g is even more preferable. The N2SA of silica is measured by the measurement method described above.

[0140] The average primary particle diameter of silica is preferably 24 nm or less, more preferably 22 nm or less, even more preferably 20 nm or less, and particularly preferably 18 nm or less. The lower limit of the average primary particle diameter is not particularly limited, but from the viewpoint of silica dispersibility, it is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 5 nm or more. The average primary particle diameter of silica is measured by the measurement method described above.

[0141] When silica is included, its content per 100 parts by mass of the rubber component is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 50 parts by mass or more, from the viewpoint of the effects of the present invention. Furthermore, the content is preferably 110 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 90 parts by mass or less, and particularly preferably 80 parts by mass or less.

[0142] From the viewpoint of the effects of the present invention, the total content of filler per 100 parts by mass of rubber component is preferably 70 parts by mass or more, more preferably 80 parts by mass or more, even more preferably 90 parts by mass or more, even more preferably 100 parts by mass or more, and particularly preferably 105 parts by mass or more. Furthermore, from the viewpoint of low fuel consumption performance and elongation at break, it is preferably 150 parts by mass or less, more preferably 140 parts by mass or less, and even more preferably 130 parts by mass or less.

[0143] (Other fillers) Other fillers besides silica and carbon black are not particularly limited and may include those commonly used in the tire industry, such as aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, magnesium sulfate, talc, and clay. These other fillers may be used individually or in combination of two or more.

[0144] (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 used in combination with silica in the tire industry can be used, but examples include mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; and 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, and 3-octanoylthio-1-propyltrimethoxysilane. Examples include thioester-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. In particular, it is preferable to contain a sulfide-based silane coupling agent and / or a mercapto-based silane coupling agent. As silane coupling agents, for example, those commercially available from Evonik Industries, Momentive, etc., can be used. The silane coupling agent may be used alone or in combination of two or more types.

[0145] From the viewpoint of improving silica dispersibility, the content of the silane coupling agent per 100 parts by mass of silica is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, and even more preferably 5.0 parts by mass or more. Furthermore, from the viewpoint of cost and processability, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 12 parts by mass or less.

[0146] <Plasticizer> The rubber composition according to this embodiment preferably contains a plasticizer. This plasticizer is a material that imparts plasticity to the rubber component and is a concept that includes both liquid plasticizers at 25°C and solid plasticizers at 25°C. Examples of plasticizers include resin components, oils, liquid rubber, ester-based plasticizers, etc. These plasticizers may be derived from mineral resources such as petroleum and natural gas, from biomass, or from naphtha recycled from rubber or non-rubber products. In addition, low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may be used as plasticizers. The plasticizer may be used alone or in combination of two or more types.

[0147] (Resin components) The rubber composition according to this embodiment may also contain a resin component. The resin component that can be used in this embodiment is not particularly limited, but resins commonly used in the tire industry can be used, such as C9 resins, C5 resins, C5C9 resins, dicyclopentadiene resins, aromatic vinyl resins, coumarone resins, indene resins, terpene resins, rosin resins, phenolic resins, etc. These resin components may be used individually or in combination of two or more. Each resin component may also be used individually or in combination of two or more.

[0148] ≪C9 series resin≫ A "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a polymer obtained by polymerizing the C9 fraction alone, or a copolymer obtained by copolymerizing the C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) and a C9 fraction is called a DCPD / C9 resin. Furthermore, the C9 resin may be a hydrogenated or modified version of these resins. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene. As for C9 resins, commercially available products from companies such as BASF, Zeon Corporation, and ENEOS Corporation can be used.

[0149] ≪C5 series resin≫ "C5 resins" refer to resins obtained by polymerizing C5 fractions, and may be hydrogenated or modified resins. Examples of C5 fractions other than dicyclopentadiene include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, isoprene, piperylene, 2-methyl-1-butene, 2-methyl-2-butene, and 1-pentene. As C5 resins, commercially available products from companies such as Structol, Nippon Zeon Co., Ltd., and ENEOS Corporation can be used.

[0150] ≪C5C9 resin≫ "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified. As C5C9 petroleum resin, commercially available products from companies such as Tosoh Corporation and LUHUA can be used.

[0151] <Dicyclopentadiene resins> A "dicyclopentadiene-based resin" refers to a resin in which cyclopentadiene (CPD) and / or dicyclopentadiene (DCPD) are the most abundant monomer components, and these may be hydrogenated or modified resins. Preferred dicyclopentadiene-based resins include polymers obtained by polymerizing only dicyclopentadiene as a monomer, and copolymers (DCPD / C9 resins) obtained by copolymerizing dicyclopentadiene with the C9 fraction. Commercially available dicyclopentadiene-based resins from companies such as ExxonMobil, ENEOS Corporation, Nippon Zeon Corporation, and Maruzen Petrochemical Co., Ltd. can be used.

[0152] Aromatic vinyl resin "Aromatic vinyl resin" refers to a resin in which aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-chlorostyrene are the most abundant monomer components, and these may be hydrogenated or modified. As aromatic vinyl resins, α-methylstyrene or a homopolymer of styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, for reasons of being economical, easy to process, and having excellent heat generation properties. As aromatic vinyl resins, commercially available products from companies such as Kraton, Eastman Chemical Company, and Mitsui Chemicals, Inc. can be used.

[0153] Coumaron-based resin "Coumarone-based resin" refers to a resin containing coumarone as a monomer component, and may be hydrogenated or modified. Preferred coumarone-based resins include, for example, coumarone resin, which is a polymer with coumarone as the monomer component; coumarone-indene resin, which is a copolymer with coumarone and indene as monomer components; and coumarone-indene-styrene resin, which is a copolymer with coumarone, indene, and styrene as monomer components. As coumarone-based resins, commercially available products from companies such as Rutgers, Nippon Paint Chemical Co., Ltd., and Mitsui Chemicals, Inc. can be used.

[0154] Indene resin "Indene-based resin" refers to a resin containing indene as a monomer component, and may be hydrogenated or modified resins. Preferred indene-based resins include, for example, coumarone-indene resin, which is a copolymer of coumarone and indene as monomer components, and coumarone-indene-styrene resin, which is a copolymer of coumarone, indene, and styrene as monomer components. Commercially available indene-based resins from companies such as Rutgers, Nippon Paint Chemical Co., Ltd., and Mitsui Chemicals, Inc. can be used.

[0155] Terpene resins "Terpene resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, and dipentene as monomer components, and may be hydrogenated or modified. Preferred terpene resins include, for example, polyterpene resins, which are polymers in which one or more of the aforementioned terpene compounds are used as monomer components; aromatically modified terpene resins, which are copolymers in which the aforementioned terpene compounds and aromatic compounds are used as monomer components; and terpene phenol resins, which are copolymers in which the aforementioned terpene compounds and phenol compounds are used as monomer components. Examples of aromatic compounds that serve as monomer components in aromatically modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenol compounds that serve as monomer components in terpene phenol resins include phenol, bisphenol A, cresol, and xylenol. As terpene resins, commercially available products from companies such as Yasuhara Chemical Co., Ltd., Arakawa Chemical Industries, Ltd., and Nippon Terpene Chemical Co., Ltd. can be used.

[0156] ≪Rosin-based resin≫ "Rosin-based resin" refers to a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palastic acid, and isopimal acid, and may be hydrogenated or modified. Rosin-based resins are not particularly limited, but examples include natural resin rosin and rosin-modified resins obtained by hydrogenating, disproportionating, dimerizing, esterifying, etc. As rosin-based resins, commercially available products from companies such as Harima Chemical Industries, Ltd., Arakawa Chemical Industries, Ltd., and IREC Co., Ltd. can be used.

[0157] Phenolic resins "Phenol-based resins" refer to resins containing phenol compounds such as phenol and cresol as monomer components, and may also be hydrogenated or modified resins. Phenolic resins are not particularly limited, but examples include phenol-formaldehyde resins, alkylphenol-formaldehyde resins, alkylphenol-acetylene resins, oil-modified phenol-formaldehyde resins, and terpene-phenol resins. Phenolic resins that are commercially available from companies such as Sumitomo Bakelite Co., Ltd., DIC Corporation, and Asahi Organic Materials Co., Ltd. can be used.

[0158] From the viewpoint of grip performance, the softening point of the resin component is preferably 60°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher. Furthermore, from the viewpoint of processability and improved dispersibility between the rubber component and filler, it is preferably 150°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower. The softening point of the resin component is measured by the measurement method described above.

[0159] From the viewpoint of the effects of the present invention, the content of the resin component per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, and particularly preferably 30 parts by mass or more. On the other hand, the content is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less.

[0160] (oil) Examples of oils include mineral oil, vegetable oil, and animal oil. Furthermore, from a life cycle assessment perspective, waste oil from rubber mixers and engines, or refined waste cooking oil from restaurants, may also be used. Oils may be used individually or in combination of two or more types.

[0161] In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oils (mineral oil), naphthenic oils, and aromatic oils. Specific examples of mineral oil include MES (Mild Extracted Solvate), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Furthermore, for environmental reasons, oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of low-PCA oils include MES, TDAE, and heavy naphthenic oils. Mineral oil may be used alone or in combination of two or more types.

[0162] In this specification, vegetable oils include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and wood wax. Furthermore, vegetable oils may also include refined oils (such as salad oil) obtained by refining the above oils, transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidized polymerized oils obtained by oxidizing the above oils, and waste cooking oils recovered from use as edible oils. Note that vegetable oils may be liquid or solid at 25°C. Vegetable oils may be used individually or in combination of two or more types.

[0163] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer of three or more. Note that acylglycerols of two or more forms can be obtained by thermal polymerization, oxidative polymerization, etc. Also, the acylglycerol may be a liquid or a solid at 25°C.

[0164] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, 1 This can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours, and after removing the rubber composition, it is measured at room temperature. 1When 1H-NMR was measured and the tetramethylsilane (TMS) signal was set to 0.00 ppm, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm. These signals are presumed to originate from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0165] The aforementioned fatty acids are not particularly limited and may be unsaturated or saturated fatty acids. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0166] In particular, it is desirable that the fatty acid contains fatty acids with few double bonds, i.e., saturated fatty acids or monounsaturated fatty acids, and oleic acid is preferred. As a vegetable oil containing such fatty acids, for example, a vegetable oil containing saturated fatty acids or monounsaturated fatty acids may be used, or a vegetable oil that has been modified by transesterification or other means may be used. Furthermore, in order to produce a vegetable oil containing such fatty acids, plants may be improved by breeding, genetic modification, genome editing, etc.

[0167] As for vegetable oils, commercially available products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used.

[0168] Examples of animal oils include fish oil, beef tallow, whale oil, or oleyl alcohol which can be derived from them.

[0169] When oil is included, the content of oil per 100 parts by mass of rubber component is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 35 parts by mass or more. Furthermore, the content is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 80 parts by mass or less.

[0170] (Liquid rubber) Liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at 25°C, but examples include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), and liquid farnesene rubber. These liquid rubbers may be used individually or in combination of two or more.

[0171] (Ester-based plasticizers) Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelaate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), and trixylenyl phosphate (TXP). Ester-based plasticizers may be used individually or in combination of two or more.

[0172] From the viewpoint of the effects of the present invention, the content of plasticizer per 100 parts by mass of rubber component (total amount if multiple plasticizers are used in combination) is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, and particularly preferably 60 parts by mass or more. Furthermore, the content is preferably 120 parts by mass or less, more preferably 110 parts by mass or less, and even more preferably 100 parts by mass or less.

[0173] <Other compounding agents> In addition to rubber components, fillers, and plasticizers, the rubber composition according to this embodiment may appropriately contain compounding agents commonly used in the tire industry, such as vulcanized rubber particles, processing aids, waxes, antioxidants, stearic acid, zinc oxide, vulcanizing agents, and vulcanization accelerators.

[0174] Vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the viewpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. One type of vulcanized rubber particle may be used alone, or two or more types may be used in combination.

[0175] The vulcanized rubber particles are not particularly limited and may be either unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0176] Commercially available vulcanized rubber products can be used, such as those from Lehigh, Muraoka Rubber Industries, and others.

[0177] When vulcanized rubber particles are included, the content per 100 parts by mass of the rubber component can be appropriately adjusted, for example, within a range of more than 1 part by mass and less than 80 parts by mass.

[0178] Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. These processing aids may be used individually or in combination of two or more. Examples of processing aids that can be used are those commercially available from companies such as Schill+Seilacher and Performance Additives.

[0179] When processing aids are included, the content per 100 parts by mass of rubber components is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, even more preferably 2.0 parts by mass or more, even more preferably 3.0 parts by mass or more, and particularly preferably 4.0 parts by mass or more, from the viewpoint of the effects of the present invention. Furthermore, from the viewpoint of abrasion resistance and fracture strength, it is preferably 10 parts by mass or less, and more preferably 8.0 parts by mass or less.

[0180] The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used, such as mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. The wax can be commercially available from companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Paramelt Co., Ltd. These waxes may be used individually or in combination of two or more types.

[0181] When wax is included, the amount of wax per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, 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 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0182] The anti-aging agents are not particularly limited, but include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditril-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as amines (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products include those from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis. These antioxidants may be used individually or in combination of two or more.

[0183] When an anti-aging agent is included, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of the rubber's resistance to ozone cracking. Furthermore, from the viewpoint of wear resistance and wet grip performance, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0184] When stearic acid is included, its content per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of vulcanization rate, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0185] When zinc oxide is included, its content per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of wear resistance, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0186] Sulfur is preferably used as a vulcanizing agent. Suitable sulfurs include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. The vulcanizing agent may be used alone or in combination of two or more types.

[0187] When sulfur is included as a vulcanizing agent, the amount of sulfur per 100 parts by mass of rubber component is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.7 parts by mass or more, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, even more preferably 3.0 parts by mass or less, and particularly preferably 2.5 parts by mass or less. 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.

[0188] As a vulcanizing agent other than sulfur, known organic crosslinking agents can also be used. The organic crosslinking agent is not particularly limited as long as it can form crosslinking chains other than polysulfide bonds, but examples include alkylphenol-sulfur chloride condensates, 1,6-hexamethylene-dithiosulfate sodium dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, and dicumyl peroxide. These organic crosslinking agents can be commercially available from companies such as Taoka Chemical Industries, Ltd., Lanxess Corporation, and Flexis.

[0189] The vulcanization accelerator is not particularly limited, but examples include sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiram-based vulcanization accelerators, thiourea-based vulcanization accelerators, dithiocarbamate-based vulcanization accelerators, aldehyde-amine-based vulcanization accelerators, aldehyde-ammonia-based vulcanization accelerators, imidazoline-based vulcanization accelerators, xanthate-based vulcanization accelerators, caprolactam disulfide, and the like. 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 because they more favorably produce the desired effect.

[0190] 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, TBBS and CBS are preferred.

[0191] Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole (MBT) or its salts, di-2-benzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, and 2-(2,6-diethyl-4-morpholinothio)benzothiazole. Among these, MBTS and MBT are preferred.

[0192] 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, DPG is preferred.

[0193] When a vulcanization accelerator is included, its content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 0.7 parts by mass or more, and even more preferably 1.0 part by mass or more, from the viewpoint of ensuring a sufficient vulcanization rate. Furthermore, from the viewpoint of suppressing blooming, the content of the vulcanization accelerator is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0194] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin components, vulcanization accelerators, antioxidants, surfactants, etc.) may be derived from atmospheric carbon dioxide. Methods for obtaining these materials from carbon dioxide include directly converting carbon dioxide, or converting methane obtained through a methanation process in which methane is synthesized from carbon dioxide.

[0195] [Manufacturing of rubber compositions and tires] The rubber composition according to this embodiment 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.). The kneading process includes, for example, a base kneading step in which compounding agents and additives other than the vulcanizing agent and vulcanization accelerator are kneaded, and a final kneading (F kneading) step in which the vulcanizing agent and vulcanization accelerator are added to the kneaded product obtained in the base kneading step and kneaded. Furthermore, the base kneading step can be divided into multiple steps if desired.

[0196] 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.

[0197] A tire according to this embodiment, which has a tread portion made of the aforementioned rubber composition, can be manufactured by conventional methods using the corresponding rubber composition. That is, an unvulcanized rubber composition corresponding to the tread portion obtained by the aforementioned method is extruded in an extruder equipped with a die of a predetermined shape to match the shape of the tread 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 can be manufactured by heating and pressurizing it in a vulcanizing machine to produce the tire according to this embodiment. The vulcanization conditions are not particularly limited, and for example, a method of vulcanizing at 150 to 200°C for 10 to 30 minutes can be cited.

[0198] [Tire Uses] The tire according to this embodiment can be used for passenger car tires, heavy-duty tires, large SUV tires, motorcycle tires, etc., and is preferably used as a motorcycle tire. When used as a motorcycle tire, the type is not particularly limited and may be either a pneumatic tire or a solid tire, but it is preferable to use it as a pneumatic tire. It can also be used for various applications such as on-road tires, off-road tires, and racing tires, and is suitably used as a motorcycle tire for rough terrain driving. [Examples]

[0199] The following examples (case studies) are considered preferable for implementation, but the scope of the present invention is not limited to these examples. Using the various chemicals shown below, we examined tires having tread sections obtained according to the formulations in Tables 1, 2, and 3, and the results calculated based on the evaluation method described below are shown in Tables 1, 2, and 3.

[0200] The various chemicals used in the examples and comparative examples are summarized below. SBR1: Nipol NS522 manufactured by ZS Elastomer Co., Ltd. (S-SBR, styrene content: 39% by mass, vinyl content: 40 mol%, Tg: -25℃, Mw: 1.2 million, contains 37.5 parts by mass of oil-expanding oil per 100 parts by mass of rubber solids) SBR2: Toughden 4850 manufactured by Asahi Kasei Corporation (unmodified S-SBR, styrene content: 40% by mass, vinyl content: 46 mol%, Tg: -25℃, Mw: 950,000, contains 50 parts by mass of oil-expanding oil per 100 parts by mass of rubber solids) Carbon Black: Show Black N220 (N2SA: 111m) manufactured by Cabot Japan Co., Ltd. 2 / g, average primary particle diameter: 22nm) Silica: ULTRASIL VN3 (N2SA: 175m) manufactured by Evonik Industries. 2 / g, average primary particle diameter: 18nm) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Industries. Resin component: Nitto Chemical Co., Ltd.'s Nitto Chemical Co., Ltd. Wax: Nippon Seiro Co., Ltd. Ozo Ace 0355 (paraffin wax) Anti-aging agent 1: Antigen 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical 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: Ginrei R manufactured by Toho Zinc Co., Ltd. Sulfur: HK-200-5 (5% oil-containing powdered sulfur) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator: Noxellar NS-G (N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0201] (Examples and Comparative Examples) According to the formulations shown in Tables 1, 2, and 3, the chemicals other than sulfur and vulcanization accelerator are mixed in a 1.7 L sealed Banbury mixer for 1 to 10 minutes until the discharge temperature reaches 150 to 160°C to obtain a mixture. Next, sulfur and vulcanization accelerator are added to the mixture using a twin-screw open roll mixer and mixed for 4 minutes until the temperature reaches 105°C to obtain an unvulcanized rubber composition. Using this unvulcanized rubber composition, it is molded to the shape of the tread section and bonded together with other tire components to produce an unvulcanized tire, which is then vulcanized at 170°C to obtain the test tires (tire size: 120 / 90-19) listed in Table 1. The test tires shall have the basic structure shown in Figure 1, the tread pattern shown in Figure 2, and be manufactured according to the specifications in Table 1.

[0202] <Measurement of Acetone Extraction Volume (AE)> The amount of air-extraction (AE) is measured for each test specimen, which is prepared by cutting it from the tread of each test tire. The amount of AE is determined by immersing each vulcanized rubber test specimen in acetone for 72 hours in accordance with JIS K 6229 to extract soluble components, measuring the mass of each test specimen before and after extraction, and calculating the value using the following formula. Acetone extraction amount (mass %) = {(mass of rubber test piece before extraction - mass of rubber test piece after extraction) / (mass of rubber test piece before extraction)} × 100

[0203] <Measurement of ash content> The ash content of each test specimen, prepared by cutting from the tread of each test tire, is measured. The ash content is calculated by heating each test specimen at 650°C under a nitrogen atmosphere for 4 hours in accordance with JIS K 6226-1:2003, measuring the mass of each test specimen before and after heating, and using the following formula. (Ash content (mass %)) = (Mass of test specimen after heating / Mass of test specimen before heating) × 100

[0204] <Measurement of 70 tanδ> Each test specimen, cut from the tread of each test tire to a length of 20 mm, width of 4 mm, and thickness of 1 mm, with the tire circumference being the longer side and the tire radius being the thickness direction, will have its loss tangent tanδ measured using a dynamic viscoelasticity measuring device (GABO's Iplexer series) under the conditions of a temperature of 70°C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±1%, and extension mode.

[0205] <75℃M 300 Measurement > For each test tire, a dumbbell-shaped No. 7 test specimen, cut to a thickness of 1 mm from the tread portion such that the tire circumference is the tensile direction and the tire radius is the thickness direction, was subjected to a tensile test in accordance with JIS K 6251:2017, under conditions of a 75°C atmosphere and a tensile speed of 3.3 mm / sec. The modulus M at 300% elongation was then determined. 300 Measure (MPa).

[0206] <Measurement of rubber hardness Hs at 50℃> For each test specimen, cut from the shoulder block of each test tire so that the tire radius is oriented in the thickness direction, the Shore hardness is measured using a durometer type A in accordance with JIS K6253-3:2012, under conditions of 50°C. The measurement is performed by pressing the measuring instrument against the sample from the tire contact surface side of each test specimen.

[0207] <Grip performance> Each test tire is mounted on a standard rim and fitted to a test vehicle under standard internal pressure conditions. Test riders then subjectively evaluate the stability of the control while driving the test vehicle on an uneven surface test course at a predetermined speed. The evaluation is based on an integer score from 1 to 10, with higher scores indicating superior steering control stability. The total scores of the 10 test riders are calculated. The total score of the control tire (Comparative Example 3) is converted to a baseline value (100), and the evaluation results of each test tire are indexed and displayed in proportion to the total score. A higher numerical value indicates better grip performance.

[0208] [Table 1]

[0209] [Table 2]

[0210] [Table 3]

[0211] <Embodiment> Examples of embodiments of the present invention are shown below.

[0212] [1] A tire having a plurality of blocks in the tread portion, wherein the tread portion is made of a rubber composition containing rubber components, the land ratio of the tread portion is L (%), the tanδ of the rubber composition at 70°C is 70°Ctanδ, and the modulus of the rubber composition at 300% stretch at 75°C is 75°CM 300 When (MPa), L is less than 30, preferably less than 28, more preferably less than 26, and even more preferably less than 24, and 75℃M 300 The ratio is 5.0 or higher, preferably 6.0 or higher, more preferably 7.0 or higher, and even more preferably 8.0 or higher, and L, 70°C tanδ, and 75°C M 300 A tire that satisfies the following equation (1). (L 0.5×70℃ tanδ) / 75℃ M 300 ≥0.13 ···(1) [2] The tire according to [1] above, wherein when the height of the block is H (mm), H / 70℃tanδ is less than 95, preferably less than 85, and more preferably less than 75. [3] The tire according to [1] or [2] above, wherein the rubber composition contains 50 parts by mass or more of silica per 100 parts by mass of rubber component. [4] A tire according to any of [1] to [3] above, wherein, when the crown portion is defined as 30% of the contact surface width of the tread portion with the tire equator as the center, the tire has 25 or more blocks on the circumference of the tire in which part or all of the blocks are located in the crown portion. [5] A tire according to any one of [1] to [4] above, wherein the total amount of styrene in the rubber component is 30% by mass or more. [6] The tire according to any one of [1] to [5] above, wherein the total content of filler in the rubber composition is 100 parts by mass or more per 100 parts by mass of rubber component. [7] The tire according to any one of [1] to [6] above, wherein the content of the resin component in the rubber composition is 30 parts by mass or more per 100 parts by mass of the rubber component. [8] The tire according to any one of [1] to [7] above, wherein the amount of acetone extracted from the rubber composition is 28% by mass or more. [9] The tire according to any one of [1] to [8] above, wherein the ash content of the rubber composition is 15% by mass or more.

[10] The plurality of blocks include a plurality of shoulder blocks that form the tread edge and a plurality of middle blocks adjacent to the inner side of the shoulder block in the tire axial direction, A tire according to any one of [1] to [9] above, wherein, in a meridional cross-section including the tire rotation axis, the inner edge of the shoulder block protrudes radially outward from the virtual profile obtained by extending the tread profile of the middle block to the shoulder block.

[11] The tire according to

[10] above, wherein P (mm) is the amount of protrusion of the inner edge, A (mm) is the length of the tread surface of the shoulder block in the tire circumferential direction, and Hs is the rubber hardness of the rubber composition constituting the shoulder block at 50°C, and P × A × Hs is greater than 800, preferably greater than 850 and less than 5000.

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

[11] above, wherein a pair of sipes extending without intersecting each other are formed on the tread surface of any of the plurality of blocks.

[13] A tire for a motorcycle, as described in any of [1] to

[12] above. [Explanation of Symbols]

[0213] 1 tire 2 Tread section 3. Sidewall section 4. Bead section 5 Bead core 6. Carcass layer 7 Belt layer 9 Groove bottom surface 10 blocks 11 Shoulder Block 12 Middle Block 13 Crown Block 14 sipes 18 Virtual Profiles 20. Inner edge of the tread surface of the shoulder block in the direction of the tire axis. 21. Outer edge of the tire axial direction on the tread surface of the middle block. 29 Tread 30 Side view 31 First aspect 32 Second aspect 33 Third aspect 34 Fourth aspect 40 recess 40d Bottom surface of the recess 41 Concave curved surface C Tire equator (tire centerline) W1 Shoulder block tread width in the tire axis direction W2 Middle block tread width in the tire axis direction L Shoulder block tread length in the tire circumferential direction P: Amount of protrusion of the inner edge RD Tire rotation direction

Claims

1. A tire having multiple blocks on the tread, The tread portion is made of a rubber composition containing rubber components, The land ratio of the tread portion is L (%), the tanδ of the rubber composition at 70°C is 70°C tanδ, and the modulus of the rubber composition at 300% stretch at 75°C is 75°C M 300 When using (MPa), L is less than 30, and 75°C M 300 The ratio is 5.0 or higher, and L, 70°C tanδ, and 75°C M 300 A tire that satisfies the following equation (1). (L 0.5 ×70℃tanδ) / 75℃M 300 ≧0.13 ・・・(1)

2. The tire according to claim 1, wherein, when the height of the block is H (mm), H / 70°C tanδ is less than 95.

3. The tire according to claim 1 or 2, wherein the rubber composition contains 50 parts by mass or more of silica per 100 parts by mass of rubber component.

4. The tire according to claim 1 or 2, wherein, when the crown portion is defined as 30% of the contact surface width of the tread portion with respect to the tire equator, the tire has 25 or more blocks on its circumference in which part or all of the blocks are located in the crown portion.

5. The tire according to claim 1 or 2, wherein the total amount of styrene in the rubber component is 30% by mass or more.

6. The tire according to claim 1 or 2, wherein the total content of filler relative to 100 parts by mass of rubber component in the rubber composition is 100 parts by mass or more.

7. The tire according to claim 1 or 2, wherein the content of the resin component in the rubber composition is 30 parts by mass or more relative to 100 parts by mass of the rubber component.

8. The tire according to claim 1 or 2, wherein the amount of acetone extracted from the rubber composition is 28% by mass or more.

9. The tire according to claim 1 or 2, wherein the ash content of the rubber composition is 15% by mass or more.

10. The plurality of blocks include a plurality of shoulder blocks that form the tread edge and a plurality of middle blocks adjacent to the shoulder blocks on the tire axial side, The tire according to claim 1 or 2, wherein, in a meridional cross-section including the tire rotation axis, the inner edge of the shoulder block protrudes radially outward from the virtual profile obtained by extending the tread profile of the middle block to the shoulder block.

11. The tire according to claim 10, wherein P (mm) is the amount of protrusion of the inner edge, A (mm) is the length of the tread surface of the shoulder block in the tire circumferential direction, and Hs is the rubber hardness of the rubber composition constituting the shoulder block at 50°C, and P × A × Hs is greater than 800.

12. The tire according to claim 1 or 2, wherein a pair of sipes extending without intersecting each other are formed on the tread surface of any of the aforementioned plurality of blocks.

13. A tire for a motorcycle, as described in claim 1 or 2.

Images