pneumatic tires

Abstract

In pneumatic tires equipped with carcass cords whose stretch direction changes, the reduction in wear resistance is suppressed. [Solution] The cap tread comprises a carcass, a reinforcing layer, and a cap tread, the cap tread having a plurality of circumferential main grooves extending continuously in the circumferential direction of the tire, and a plurality of land portions separated by the circumferential main grooves and the contact end, the angle at which the extension direction of the carcass cords inclinates from the circumferential direction of the tire at the position of the tire centerline is A1 (°), the angle at which the extension direction of the carcass cords inclinates from the circumferential direction of the tire at the position of the tire's maximum width is A2 (°), the land portion width of the land portion closest to the tire centerline is W1 (mm), the land portion width of the land portion adjacent to the axially oriented side of the land portion closest to the tire centerline is W2 (mm), and the complex modulus of elasticity of the cap tread at 30°C is 30°E * A pneumatic tire that satisfies the following equation, where c is a constant and K is a constant. |A2-A1|>0; W1 / W2>0.30; and 30℃E * c > K / {|A2 - A1| × (W1 - 0.3 × W2)} (where K is 410)

Description

Technical Field

[0001] The present invention relates to pneumatic tires.

Background Art

[0002] The carcass ply forms the framework of a pneumatic tire. Organic fiber cords or steel cords are used for the carcass cords that make up the carcass ply, and the carcass ply greatly affects the durability, rigidity, etc. of the pneumatic tire. Patent Document 1 and Patent Document 2 describe pneumatic tires in which the carcass cords are bent by controlling the direction in which the carcass cords extend.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in such pneumatic tires, there is a concern that the outer diameter grows due to a change in the stretching direction of the carcass cords during driving, and the wear resistance performance of the tire deteriorates.

[0005] An object of the present invention is to suppress a decrease in wear resistance performance in a pneumatic tire provided with a carcass cord whose stretching direction changes.

Means for Solving the Problems

[0006] The present invention relates to a pneumatic tire comprising a carcass, a reinforcing layer disposed radially outside the carcass, and a cap tread disposed radially outside the reinforcing layer, wherein the cap tread has a plurality of circumferential main grooves extending continuously in the circumferential direction of the tire, and a plurality of land portions separated by the circumferential main grooves and the contact edge, the cap tread is made of a rubber composition containing a rubber component, the carcass is made of at least one carcass ply comprising a plurality of carcass cords and a topping rubber covering the carcass cords, and the reinforcing layer comprises a plurality of reinforcing layer cords and front The carcass tread is composed of at least one reinforcing layer ply comprising a topping rubber covering the reinforcing layer cord, wherein the angle at which the extension direction of the carcass cord of at least one of the carcass plies is inclined from the tire circumferential direction at the position of the tire centerline is A1(°), the angle at which it is inclined from the tire circumferential direction at the position of the tire's maximum width is A2(°), the width of the land portion of the land portion closest to the tire centerline is W1(mm), the width of the land portion adjacent to the land portion closest to the tire centerline on the tire axial side is W2(mm), and the complex modulus of elasticity of the rubber composition constituting the cap tread at 30°C is 30°E * c, If the constant is K, then A1, A2, W1, W2, 30℃E * The present invention relates to a pneumatic tire in which c and K satisfy the following equations (1), (2), and (3). (1)|A2-A1|>0 (2) W1 / W2 > 0.30 (3) 30℃E * c>K / {|A2-A1|×(W1-0.3×W2)} (However, K is 410) [Effects of the Invention]

[0007] According to the present invention, in a pneumatic tire equipped with carcass cords whose stretching direction changes, a decrease in wear resistance can be suppressed. [Brief explanation of the drawing]

[0008] [Figure 1]This is a cross-sectional view of a pneumatic tire according to one embodiment of the present invention, passing through the tire rotation axis. [Figure 2] This is a schematic diagram of the contact surface of a tire when the tread is pressed against a flat surface. [Figure 3] This is an example of an unfolded diagram showing the angle between the extension direction and the tire circumferential direction of a carcass cord constituting a carcass ply of a pneumatic tire according to one embodiment of the present invention. [Figure 4] This is a modified example of an unfolded diagram showing the angle between the stretching direction and the tire circumferential direction of a carcass cord constituting a carcass ply of a pneumatic tire according to one embodiment of the present invention. [Figure 5] This is a schematic diagram showing a preferred range of angles between the stretching direction and the tire circumferential direction for carcass cords constituting the carcass ply of a pneumatic tire according to one embodiment of the present invention. [Modes for carrying out the invention]

[0009] The following describes a pneumatic tire according to one embodiment of the present invention. The pneumatic tire of this embodiment comprises a carcass, a reinforcing layer disposed on the radially outer side of the carcass, and a cap tread disposed on the radially outer side of the reinforcing layer, wherein the cap tread has a plurality of circumferential main grooves extending continuously in the circumferential direction of the tire, and a plurality of land portions separated by the circumferential main grooves and the contact end, the cap tread is made of a rubber composition containing a rubber component, the carcass is made of at least one carcass ply comprising a plurality of carcass cords and a topping rubber covering the carcass cords, and the reinforcing layer comprises a plurality of reinforcing layers The carcass tread is composed of at least one reinforcing layer ply comprising a cord and a topping rubber covering the reinforcing layer cord, wherein the angle at which the extension direction of the carcass cord of at least one of the carcass plies is inclined from the tire circumferential direction at the position of the tire centerline is A1(°), the angle at which it is inclined from the tire circumferential direction at the position of the tire's maximum width is A2(°), the width of the land portion of the land portion closest to the tire centerline is W1(mm), the width of the land portion adjacent to the land portion closest to the tire centerline on the tire axial side is W2(mm), and the complex modulus of elasticity of the rubber composition constituting the cap tread at 30°C is 30°CE * c, If the constant is K, then A1, A2, W1, W2, 30℃E * The pneumatic tire is such that c and K satisfy the following equations (1), (2), and (3). (1)|A2-A1|>0 (2) W1 / W2 > 0.30 (3) 30℃E * c>K / {|A2-A1|×(W1-0.3×W2)} (However, K is 410)

[0010] While not intended to be constrained by theory, the reason for suppressing the decrease in wear resistance in this invention is thought to be as follows. In other words, in this invention, by ensuring the width of the land area closest to the tire centerline, where outer diameter growth is likely to occur during driving, the rigidity of the land area is increased, and outer diameter growth can be suppressed. Furthermore, the complex modulus of elasticity of the rubber composition constituting the cap tread is adjusted to satisfy a predetermined relational equation according to the stretching direction of the carcass cords, the width of the land area closest to the tire centerline, and the width of the land area adjacent to the axially oriented side of the land area closest to the tire centerline. This is thought to suppress the decrease in the wear resistance of the tire.

[0011] From the viewpoint of improving wear resistance, the rubber component constituting the cap tread preferably includes isoprene-based rubber.

[0012] From the viewpoint of improving wear resistance, the rubber composition constituting the cap tread preferably contains silica with an average primary particle diameter of 18 nm or less.

[0013] The rubber composition constituting the cap tread preferably contains resin.

[0014] It is believed that the complex modulus of elasticity of the cap tread at 30°C is appropriately adjusted, further improving wear resistance.

[0015] It is preferable that A1, A2, W1, and W2 satisfy the following formula (4). (4)(W1-0.3×W2) / |A2-A1|>0.30

[0016] By setting the value of equation (4) within the aforementioned range, an appropriate difference in the width of the land portion is set according to the difference in the stretching direction of the carcass cord, from the viewpoint of suppressing outer diameter growth, and it is believed that the wear resistance performance of the tire will be further improved.

[0017] In at least one of the reinforcing layer plies, the angle A inclined by the extension direction of the reinforcing layer cord from the tire circumferential direction.RF It is preferable that (°) is different from the said A1(°).

[0018] A1 and A RF By being different from each other, it is considered that the twist of the carcass ply arranged by controlling its stretching direction inside the tire radial direction of the tread can be relaxed.

[0019] The said A RF The inclination direction from the tire circumferential direction of is preferably the opposite direction to the inclination direction from the tire circumferential direction of the said A1.

[0020] A1 and A RF By the inclination directions of being opposite to each other, it is considered that the twist of the carcass ply arranged by bias inside the tire radial direction of the tread can be canceled.

[0021] The reinforcing layer ply including the reinforcing layer cord whose stretching direction is inclined from the tire circumferential direction at an angle of A RF (°) is preferably composed of a single reinforcing layer ply.

[0022] By suppressing the number of reinforcing layer plies, it is considered that the tire can be lightened.

[0023] The reinforcing layer ply in which the stretching direction of the reinforcing layer cord is inclined from the tire circumferential direction at an angle of A RF (°) is preferably a belt ply.

[0024] By being a belt ply, it is considered that the number of reinforcing layer plies can be minimized.

[0025] ​​​​​​​​​The carcass is preferably composed of a single carcass ply.

[0028] It is believed that reducing the number of carcass plies can make the tire lighter.

[0029] A2 is preferably between +70° and +90°, or between -70° and -90°.

[0030] It is believed that the effects of the present invention can be improved by defining the range of A2 as described above.

[0031] <Definition> "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.

[0032] 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.

[0033] 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).

[0034] "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.

[0035] "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.

[0036] "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.

[0037]

number

[0038] The "tread" is a component that includes the part that forms the contact surface of the tire. In the cross-section of the tire, which is a plane containing the tire's axis of rotation, it is a component that is positioned radially outward from other components such as the reinforcing layer and carcass. The "bead" is the part of the tire that contacts the rim, maintains internal pressure, and transmits drive and braking forces.

[0039] The "contact area" is the tread area obtained from the contour when the tire is pressed against the ground. It is obtained by mounting the tire on a standard rim, filling it with standard internal pressure, letting it stand at 25°C for 24 hours, then applying ink to the surface of the tire tread, applying a standard load (a load equal to the maximum load capacity) to the tire, pressing it perpendicularly to cardboard (camber angle of 0°), and transferring the ink.

[0040] "Tread contact edge" refers to the outermost edge in the tire width direction within the contact area. In this embodiment, the tread contact edge on the outer side in the vehicle direction is denoted as To, and the tread contact edge on the inner side in the vehicle direction is denoted as Ti.

[0041] "Tread contact width" refers to the distance along the tread surface between the tread contact edges To and Ti.

[0042] A "carcass" is a component that forms the tire's skeletal structure, and is composed of at least one carcass ply comprising multiple carcass cords and a topping rubber covering the carcass cords. Internal components exist on the radially inward side of the carcass. Examples of such internal components include an inner liner and insulation.

[0043] "Tire maximum width position" refers to the position of the maximum width within the tire's cross-section measured under normal conditions. In each drawing, this is indicated by P.

[0044] The "R1 region" refers to the region on the tire centerline where the inclination angle of the carcass cord, A1, is within a predetermined range of variation. The permissible range of variation for the inclination angle of the carcass cord in the R1 region is between -10% and 5% of the absolute value of A1 (|A1|). The R1 region straddles the tire centerline and does not include the tire's maximum width position, which is the measurement position of A2.

[0045] "A1" refers to the angle (°) at which the extension direction of the carcass cords slopes relative to the tire's circumferential direction at the tire's centerline. When viewed from the inner side of the tire, a downward slope to the right relative to the tire's circumferential direction is considered positive (+), and an upward slope to the right is considered negative (-), with the value expressed in the range of greater than -90° and less than or equal to +90°. If there are multiple applicable carcass plies, it is preferable to measure at the outermost carcass ply in the tire's radial direction. Figure 3 shows the case where A1 is positive (+). Note that the "+" symbol may be omitted when the value is positive.

[0046] "A2" refers to the angle (°) at which the extension direction of the carcass cords slopes relative to the tire's circumferential direction at the tire's maximum width. When viewed from the inner side of the tire, a downward slope to the right relative to the tire's circumferential direction is considered positive (+), and an upward slope to the right is considered negative (-), with the value expressed in the range of greater than -90° and less than or equal to +90°. If there are multiple applicable carcass plies, it is preferable to measure the outermost carcass ply in the tire's radial direction. Figure 3 shows the case where A2 is positive (+). Furthermore, if the carcass has both a main body and a winding section at the tire's maximum width, the carcass cords of the main body are the measurement target. Note that the "+" symbol may be omitted when the value is positive.

[0047] A "carcass cord whose direction of extension changes" is a carcass cord that satisfies equation (1) above, that is, |A2-A1|>0.

[0048] A "reinforcement layer" is a component provided radially outside the carcass and radially inside the tread, which has the effect of suppressing tire protrusion due to internal pressure and rotation, and receiving and mitigating input from the road surface. The reinforcement layer consists of at least one reinforcement layer ply comprising multiple reinforcement layer cords and a topping rubber covering the reinforcement layer cords. In this specification, the reinforcement layer ply that is positioned furthest in the tire radial direction among the at least one reinforcement layer ply is called the inner reinforcement layer ply. Specific examples of reinforcement layers include belts and bands.

[0049] A "belt" is one of the reinforcing layers and consists of at least one belt ply. The multiple belt cords that make up the belt ply are arranged approximately parallel to each other, and the direction of extension of the belt cords is inclined at an angle of 10° or more with respect to the tire circumferential direction. The belt has joints on the circumference of the tire. Here, "approximately parallel" means that the angle difference between the direction of extension of each belt cord and the tire circumferential direction is within ±3°.

[0050] A "band" is a reinforcing layer, consisting of at least one band ply. The band cords that make up the band ply are arranged in a spiral shape around the tire's circumference, and the direction of extension of the band cords is kept within a 5° inclination relative to the tire's circumference. The band does not have any joints around the circumference of the tire. There are two types of bands: full bands that cover the entire tread and edge bands that cover only the edges of the tread.

[0051] "A RF " is the angle (°) at which the extension direction of the reinforcing layer cord of the reinforcing layer ply is inclined relative to the tire circumferential direction. When viewed from the inner side of the tire, a downward slope to the right relative to the tire circumferential direction is considered positive (+), and an upward slope to the right is considered negative (-), and it is expressed in the range of greater than -90° and less than or equal to +90°. In Figure 3, A RF The case where the value is negative (-) is shown. Note that the "+" symbol may be omitted when the value is positive.

[0052] A "groove" refers to a recessed area formed on the tire tread surface (extending inward in the radial direction of the tire) with an opening width of 2.0 mm or more on the tread surface. Those with an opening width of less than 2.0 mm are called "sipes".

[0053] A "circumferential main groove" refers to a groove that extends continuously in the circumferential direction of the tire and whose maximum groove width is 2.5% or more of the tread contact width, and the land portion of the tread is separated by the circumferential main groove. The circumferential main groove may extend in a straight line along the circumferential direction, or it may extend in a wavy, sinusoidal, or zigzag pattern along the circumferential direction.

[0054] The "land area" refers to the part of the tire's tread that makes contact with the ground when the tire is pressed against it, and is the part of the tread that constitutes the contact area.

[0055] The term "land area" refers to the region of the tread separated by the tread contact edge Te and multiple circumferential main grooves that extend continuously in the circumferential direction of the tire. For example, if there are two circumferential main grooves, the land area is divided into a pair of shoulder land areas and a single center land area sandwiched between them. If there are three circumferential main grooves, the center land area is further divided into a land area that faces the inside of the vehicle when mounted on the vehicle and a land area that faces the outside of the vehicle.

[0056] The term "shoulder land area" refers to a pair of land areas formed between the circumferential main groove located on the outermost side of the tire axis W from the tire centerline CL and the contact edge Te of each tread.

[0057] The "center track area" refers to all the track areas sandwiched between the aforementioned pair of shoulder track areas.

[0058] "The land area closest to the tire centerline" refers to the land area located on the tire centerline CL if there is no circumferential main groove on the tire centerline CL, and, if there is a circumferential main groove on the tire centerline CL, it refers to the land area with the groove edge closest to the tire centerline CL among the groove edges of the circumferential main groove located on the tire centerline CL. If there are land areas with the groove edge closest to the tire centerline CL on both sides of the tire axial direction, the one with the larger width in the tire axial direction shall be considered "the land area closest to the tire centerline". If there are land areas with the groove edge closest to the tire centerline CL on both sides of the tire axial direction, and the width of those land areas in the tire axial direction is the same, then the land area on the outer side in the vehicle direction shall be considered "the land area closest to the tire centerline".

[0059] "The land area adjacent to the outer side of the axial direction of the land area closest to the tire centerline" refers to the land area with the smaller axial width among the two land areas adjacent to the outer sides of the axial direction of the land area closest to the tire centerline CL, if the land area closest to the tire centerline CL is located on the tire centerline CL. If the two land areas adjacent to the outer sides of the axial direction of that land area have the same axial width, the land area on the outer side in the vehicle direction among those land areas shall be considered "the land area adjacent to the outer side of the axial direction of the land area closest to the tire centerline". When the circumferential main groove is located on the tire centerline CL, if the "land area closest to the tire centerline" according to the above definition is located on the outer side in the vehicle direction relative to the tire centerline CL, then the land area adjacent to the outer side in the vehicle direction of that land area shall be considered "the land area adjacent to the outer side of the axial direction of the land area closest to the tire centerline".

[0060] "The width W1 of the land area closest to the tire centerline" and "the width W2 of the land area adjacent to the land area closest to the tire centerline on the outer side in the tire axis direction" refer to the maximum width in the tire axis direction of the "land area closest to the tire centerline" and "land area adjacent to the land area closest to the tire centerline on the outer side in the tire axis direction," as defined above.

[0061] The "rubber component of the rubber composition" refers to a component that contributes to crosslinking within the rubber composition, and generally has a weight-average molecular weight (Mw) of 10,000 or more. The Mw of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more. Furthermore, the Mw of the rubber component is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less.

[0062] 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.

[0063] "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.

[0064] <Measurement method> "30℃E * "c" is the complex modulus (MPa) of the rubber composition constituting the cap tread at 30°C, and is measured using a dynamic viscoelasticity measuring device (e.g., GABO's Iplexer series) under the conditions of 30°C, 10Hz frequency, 5% initial strain, ±1% dynamic strain, and extension mode. The sample is a vulcanized rubber composition with dimensions of 20mm length × 4mm width × 1mm thickness. When preparing a sample by cutting it from a tire, the length direction of the sample should coincide with the tire's circumferential direction, and the thickness direction of the sample should coincide with the tire's radial direction.

[0065] "A1" and "A2" are determined by averaging the angles measured using four different cords. The selection of the four cords is preferably arbitrary, and more preferably, they are four cords spaced approximately 90° apart in the circumferential direction of the tire. In this case, the cords used for measurement of A1 and A2 do not need to be the same, but it is even more preferable that the cords used for measurement of A1 and A2 are the same.

[0066] "A RF The angle is determined by averaging the angles measured with four different cords. The selection of the four cords is preferably any four, and more preferably four cords that are spaced approximately 90° apart in the circumferential direction of the tire.

[0067] "Styrene content" can be determined by pyrolysis gas chromatography or NMR measurement. 1 H-NMR and 13 It is calculated using ¹¹C-NMR. The amount of components such as "styrene content" is calculated using the complex modulus (E). *Unlike physical properties such as ), there exists a true value that is independent of 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.

[0068] "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.

[0069] "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, for example, 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, so it is preferable to use the most accurate measurement method possible.

[0070] 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.

[0071] The nitrogen adsorption specific surface area (N2SA) of carbon black is measured in accordance with JIS K 6217-2:2017.

[0072] The nitrogen adsorption specific surface area (N2SA) of silica is measured by the BET method in accordance with ASTM D3037-93.

[0073] The "average primary particle diameter" is a value obtained 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 shape 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.

[0074] 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.

[0075] The embodiments will be described in further detail below. However, the following description is illustrative for explaining the present invention, and the present invention is not limited to these. Drawings will be used as appropriate, but the drawings are for illustrative purposes only.

[0076] <Tires> The tire in Figure 1 consists of a tread 1, a sidewall 2, and a bead section 3, and includes a cap tread 5, a base tread 6, a carcass 7, and a reinforcing layer 10. The bead section includes a bead apex 3a and a bead core 3b. The reinforcing layer 10 consists of a belt 8 and a band 9. The carcass 7 consists of a single carcass ply comprising multiple carcass cords and a topping rubber covering the carcass cords. The belt 8 consists of a single belt ply comprising multiple belt cords and a topping rubber covering the belt cords. The band 9 consists of a single band ply comprising multiple band cords and a topping rubber covering the band cords. In this tire, the belt ply constituting the belt 8 is the inner reinforcing layer ply. The tire's maximum width position is indicated by P.

[0077] In the tire shown in Figure 1, the carcass 7 may be composed of multiple carcass plies, but from the viewpoint of reducing tire weight, it is preferable that it be composed of fewer carcass plies, and more preferably that it be composed of one carcass ply. The belt 8 may be composed of multiple belt plies, but from the viewpoint of reducing tire weight, it is preferable that it be composed of fewer belt plies, and more preferably that it be composed of one belt ply. The band 9 may be composed of multiple band plies, but from the viewpoint of reducing tire weight, it is preferable that it be composed of fewer band plies, and more preferably that it be composed of one band ply. Both the belt 8 and the band 9 constitute the reinforcing layer 10. The reinforcing layer 10 may be composed of multiple reinforcing layer plies, but from the viewpoint of reducing tire weight, it is preferable that it be composed of fewer reinforcing layer plies, and it is preferable that the reinforcing layer 10 is composed of one reinforcing layer ply.

[0078] In the tire of this embodiment, the reinforcing layer may include both a belt and a band, or it may consist only of a belt or a band. Of these, it is preferable that the reinforcing layer consists only of a belt.

[0079] Figure 2 is a schematic diagram of the tire contact surface when the tread 1 according to this embodiment is pressed against a flat surface. The tread 1 has three circumferential main grooves 11, 12, and 13 that extend continuously in the circumferential direction of the tire, but the number of circumferential main grooves is not particularly limited and may be, for example, 2 to 5. Also, the circumferential main grooves 11, 12, and 13 extend in a straight line along the circumferential direction, but are not limited to this configuration and may extend in a wavy, sinusoidal, zigzag, or the like along the circumferential direction. Preferably, the circumferential main grooves include a pair of shoulder circumferential main grooves located on both sides of the tire axial direction, straddling the tire centerline.

[0080] Preferably, the shoulder land portions 16, 17 and the center land portions 18, 19 are provided with transverse grooves and / or sipes that cross the land portions. In Figure 2, for example, the shoulder land portions 16, 17 are provided with a plurality of shoulder transverse grooves 21 whose ends open into the circumferential main grooves 11, 12, and a plurality of shoulder sipes 22 whose one end opens into the circumferential main grooves 11, 12, while the center land portions 18, 19 are provided with a plurality of center sipes 23 whose one end opens into the circumferential main grooves 11, 13.

[0081] In Figure 2, the groove edges of the circumferential main grooves 13 located on the tire centerline CL are equidistant from the tire centerline CL, and the maximum widths in the tire axial direction of the center land portions 18 and 19 are the same. Therefore, in this embodiment, the "land portion closest to the tire centerline" is the center land portion 18 located outward in the vehicle direction from the tire centerline CL in Figure 2, and the maximum width in the tire axial direction of the center land portion 18 becomes the land portion width W1 of the land portion closest to the tire centerline.

[0082] In this embodiment, the "land area adjacent to the outer side of the land area closest to the tire centerline in the tire axial direction" is, in Figure 2, the shoulder land area 16 adjacent to the outer side of the center land area 18 in the vehicle direction, and the minimum width of the shoulder land area 16 in the tire axial direction is the width W2 of the land area adjacent to the outer side of the land area closest to the tire centerline in the tire axial direction.

[0083] When a tire has a circumferential main groove on the tire centerline CL, and the width of the land area of ​​the other land area that was not selected as the "land area closest to the tire centerline" from the two land areas existing on either side of the tire centerline is W3, then W3 / W1 is preferably greater than 0.5, more preferably greater than 0.6, and even more preferably greater than 0.7. Furthermore, W3 / W1 is preferably less than 1.5, preferably less than 1.4, and even more preferably less than 1.3.

[0084] From the viewpoint of the effects of the present invention, W1 is preferably 6.0% or more, more preferably 8.0% or more, and even more preferably 10.0% or more relative to the tread contact width. Furthermore, W1 is preferably 21.0% or less, more preferably 19.0% or less, and even more preferably 17.0% or less.

[0085] From the viewpoint of the effects of the present invention, W2 is preferably 9.0% or more, more preferably 11.0% or more, and even more preferably 13.0% or more relative to the tread contact width. Furthermore, W2 is preferably 39.0% or less, more preferably 37.0% or less, and even more preferably 35.0% or less.

[0086] Figure 3 shows an unfolded view of the carcass cords constituting the carcass ply, showing the angle between their extension direction and the tire circumferential direction as seen from the inner surface of the tire. In Figure 3, the left-right direction W represents the tire width direction, and the up-down direction C represents the tire circumferential direction. The carcass ply comprises multiple carcass cords and a topping rubber covering the carcass cords, and in Figure 3, these multiple carcass cords are shown as solid lines. In Figure 3, the angle at which the extension direction of the carcass cords slopes from the tire circumferential direction is A2 at one tire maximum width position P, then bends to A1 at the tire centerline position, then bends again in the opposite direction to A2 at the other tire maximum width position P. The dotted line indicates an inner reinforcing layer ply comprising multiple reinforcing layer cords and a topping rubber covering the reinforcing layer cords, specifically a belt ply.

[0087] The angle at which the carcass cord's extension direction slopes from the tire's circumferential direction at the tire's centerline is shown as A1(°), and the angle at which it slopes from the tire's circumferential direction at the tire's maximum width is shown as A2(°). Both A1 and A2 have positive (+) values ​​because they slope downward to the right with respect to the tire's circumferential direction when viewed from the inner surface of the tire. On the other hand, the angle at which the reinforcing layer cord's extension direction slopes from the tire's circumferential direction is A RF (°) is indicated. RF Because it slopes upward to the right relative to the tire's circumferential direction when viewed from the inner side of the tire, it has a negative (-) value.

[0088] Figure 4 is an unfolded view of the carcass cords constituting the carcass ply, showing the angle between their extension direction and the tire circumferential direction as seen from the inner surface of the tire. This is a modified version of Figure 3. The carcass cords in Figure 3 are shown from one maximum tire width position to the other. Their extension direction begins at an angle A2 inclined from the tire circumferential direction at one maximum tire width position P, changes smoothly along the way, and ends at an angle A2 inclined from the tire circumferential direction at the other maximum tire width position P. Otherwise, it is the same as in Figure 3.

[0089] In the tire of this embodiment, the width of the R1 region, where the inclination angle of the carcass cord A1 on the tire centerline is within a predetermined range of variation, is preferably 30% or more of the tread contact width. More preferably, the width of the R1 region is 50% or more, even more preferably 70% or more, and even more preferably 90% or more of the tread contact width. On the other hand, the width of the R1 region is preferably 100% or less of the tread contact width.

[0090] The materials of the carcass cord and reinforcing layer cord are not particularly limited and include, for example, metal cords (such as steel cords), organic fiber cords, inorganic fiber cords (excluding metal cords), etc.

[0091] The metal cord may be a single-wire monofilament cord (i.e., a cord consisting of one filament having a 1x1 structure), or it may have multiple filaments. If a single metal cord has multiple filaments, it is preferable that the metal cord has a twisted structure in which the filaments are twisted together along its longitudinal direction. The twisted structure is not particularly limited and can be, for example, a single-strand metal cord with a 1xN structure or a layered metal cord with an N+M structure.

[0092] The filaments constituting the organic fiber cord are not particularly limited, but examples include polyester fibers, nylon fibers, aramid fibers, polyketone fibers, poly(p-phenylenenium) acrylate fibers, polyacrylate fibers, rayon fibers, cellulose fibers, carbon fibers, etc., with polyester fibers being preferred. These organic fibers may be made from synthetic fibers, biomass-derived fibers, recycled / regenerated fibers, etc. These organic fibers may be used individually or in combination of two or more types. The organic fiber cord can be made by twisting together multiple yarns, each made by twisting together multiple filaments.

[0093] Examples of inorganic fiber cords other than metal cords include carbon fiber cords and glass fiber cords.

[0094] (Formula (1)) In this embodiment, the value on the right-hand side of equation (1) is greater than 0. That is, in the tire of this embodiment, A1 and A2 are at least different, so |A2-A1|>0 is satisfied. In this embodiment, there are no other particular restrictions on the value of |A2-A1| as long as it is greater than 0, but the value is usually less than 60°, may be less than 50°, may be less than 40°, may be less than 30°, may be less than 20°, may be less than 15°, or may be 10° or less. On the other hand, the value is preferably greater than 1°, more preferably greater than 3°, and even more preferably 5° or more.

[0095] Furthermore, it is preferable that A2 is between +70° and +90°, or between -70° and -90°. Figure 5 shows a schematic diagram of the preferred range of angles between the extension direction and the tire circumferential direction of the carcass cords constituting the carcass ply, as seen from the inner surface of the tire. When A2 is between +70° and +90°, or between -70° and -90°, it means that the extension direction of the carcass cords is within the range of the arc-shaped double arrows in Figure 4. It is believed that the effects of the present invention can be improved by setting the range of A2 as described above. For A2 between +70° and +90°, the lower limit is more preferably 75° or more, even more preferably 80° or more, while the upper limit is more preferably 85° or less. For A2 between -70° and -90°, the upper limit is more preferably -75° or less, even more preferably -80° or less, while the lower limit is more preferably -85° or more.

[0096] (Formula (2)) In this embodiment, W1 / W2 is greater than 0.30. From the viewpoint of the effects of the present invention, W1 / W2 is preferably greater than 0.40, more preferably greater than 0.50, even more preferably greater than 0.60, and particularly preferably greater than 0.70. On the other hand, there is no particular limit on the upper limit of W1 / W2, but it is preferably less than 3.00, more preferably less than 2.50, even more preferably less than 2.00, and particularly preferably less than 1.50.

[0097] (Formula (3)) 30℃E * In c>K / {|A2-A1|×(W1-0.3×W2)}, the value of K is 410, preferably 415, more preferably 430, even more preferably 450, even more preferably 475, and particularly preferably 500. On the other hand, there is no particular upper limit to the value of K, but it is usually around 5000, or around 2500, or around 1250.

[0098] (Formula (4)) (W1 - 0.3 × W2) / |A2 - A1| is preferably greater than 0.30, more preferably greater than 0.50, even more preferably greater than 0.70, even more preferably greater than 0.90, and particularly preferably greater than 1.1. On the other hand, there is no particular limit on the upper limit of this value, but it is preferably less than 15.0, more preferably less than 10.0, even more preferably less than 5.0, and particularly preferably less than 3.5.

[0099] (30℃E * c) The complex modulus of elasticity at 30°C of the rubber composition constituting the cap tread is 30°CE. * c is not particularly limited as long as it satisfies formula (3), but is preferably 2.5 MPa or higher, more preferably 3.0 MPa or higher, even more preferably 3.5 MPa or higher, even more preferably 4.0 MPa or higher, and particularly preferably 4.0 MPa or higher. On the other hand, 30℃E * c is preferably 20.0 MPa or less, more preferably 15.0 MPa or less, and even more preferably 13.0 MPa or less.

[0100] Note: 30℃E * c can be adjusted as appropriate depending on the type and amount of rubber components, fillers, plasticizers, etc. described below. For example, 30℃E * c tends to increase with increasing filler content in the rubber composition.

[0101] (A RF ) In at least one of the reinforcing layer plies, A is the angle at which the extension direction of the reinforcing layer cord is inclined from the tire circumferential direction. RF It is preferable that it is different from A1, and in particular A RF Preferably, the inclination direction of A1 from the tire circumferential direction is opposite to that of A1 from the tire circumferential direction. This is because it can counteract the twisting of the carcass ply that is bias-positioned on the inner side of the tread in the tire radial direction.

[0102] The angle at which the extension direction of the reinforcing layer cord is inclined from the tire circumferential direction is A. RFThe reinforcing layer, which includes a reinforcing layer ply of (°), is preferably composed of a single reinforcing layer ply, or is preferably a belt ply.

[0103] [Rubber composition that makes up the cap tread] The rubber composition constituting the cap tread of the pneumatic tire according to this embodiment (hereinafter referred to as the rubber composition according to this embodiment) will now be described. If the tread includes a base tread on the radially inner side of the cap tread, the rubber composition constituting the base tread can be created by appropriately blending the rubber components, fillers, plasticizers, and other compounding agents described below, and appropriately adjusting their amounts.

[0104] <Rubber components> The rubber component constituting the cap tread preferably includes a diene rubber. Any diene rubber commonly used in the tire industry can be suitably used. Specifically, examples include isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), etc. The diene rubber may be used alone or in combination of two or more types. The rubber component according to this embodiment preferably contains isoprene rubber, more preferably contains isoprene rubber and SBR, even more preferably contains isoprene rubber, SBR and BR, and particularly preferably consists only of isoprene rubber, SBR and BR.

[0105] The content of diene rubber in the rubber component constituting the cap tread 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.

[0106] (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. Isoprene-based rubbers may be used alone or in combination of two or more types.

[0107] NR is not particularly limited and can be any that is common in the tire industry, such as SIR20, RSS#3, TSR20, etc.

[0108] The isoprene-based rubber content in the rubber components constituting the cap tread is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, the content is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0109] (SBR) There are no particular limitations on the type of SBR used; solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), etc., can be used. Of these, S-SBR is preferred. Modified SBR (modified S-SBR, modified E-SBR), etc., can also be used. Modified SBRs include SBRs in which the terminals and / or main chain are modified with a compound having the following functional groups (modifying agent); modified SBRs coupled with tin, silicon compounds, etc. (condensates, branched structures, etc.). Furthermore, hydrogenated versions of these SBRs (hydrogenated SBRs), etc., can also be used. SBRs may be used alone or in combination of two or more types.

[0110] The functional group of the modifying agent is preferably a functional group containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen. Examples of such functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups (preferably alkoxy groups having 1 to 6 carbon atoms), hydroxyl groups, oxy groups, epoxy groups, etc., with amino groups and / or alkoxysilyl groups being preferred. As for amino groups, amino groups substituted with 1 to 2 alkyl groups having 1 to 6 carbon atoms are preferred. Specific examples of alkoxysilyls include, for example, trimethoxysilyl, triethoxysilyl, triisopropoxysilyl, dimethoxymethylsilyl, diethoxymethylsilyl, dimethylmethoxysilyl, and dimethylethoxysilyl.

[0111] For the SBR, either oil-expanded SBR or non-oil-expanded SBR can be used. SBRs that can be used in this embodiment are commercially available from companies such as JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Corporation, Asahi Kasei Corporation, ZS Elastomer Corporation, and ARLANXEO.

[0112] The styrene content of SBR is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 25% by mass or more. Furthermore, the styrene content of SBR is preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. The styrene content of SBR is measured by the measurement method described above.

[0113] From the viewpoint of ensuring hysteresis loss, the vinyl content of SBR is preferably more than 40 mol%, more preferably more than 45 mol%, and even more preferably more than 55 mol%. Furthermore, from the viewpoint of low fuel consumption performance, the vinyl content of SBR is preferably less than 75 mol%, more preferably less than 70 mol%, and even more preferably less than 60 mol%. The vinyl content of SBR is measured by the measurement method described above.

[0114] From the viewpoint of the effects of the present invention, the weight-average molecular weight (Mw) of SBR is preferably greater than 80,000, more preferably greater than 100,000, even more preferably greater than 150,000, and particularly preferably greater than 500,000. Furthermore, from the viewpoint of crosslinking uniformity, the Mw is preferably less than 2,000,000, more preferably less than 1,500,000, and even more preferably less than 1,100,000. The Mw of SBR is measured by the measurement method described above.

[0115] The SBR content in the rubber component constituting the cap tread is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 70% by mass or more. Furthermore, the content is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less.

[0116] (BR) BR is not particularly limited, and for example, BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare-earth butadiene rubber synthesized using a rare-earth element catalyst (rare-earth BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc., which are common in the tire industry, can be used. These BRs may be used individually or in combination of two or more types.

[0117] 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 90 mol%, more preferably more than 95 mol%, and even more preferably 96 mol% or more. The cis content of BR is measured by the measurement method described above.

[0118] Rare-earth BR is synthesized using a rare-earth element catalyst, and the vinyl content of the rare-earth BR is preferably less than 1.8 mol%, more preferably less than 1.6 mol%, and even more preferably 1.5 mol% or less. The cis content of the rare-earth BR is preferably greater than 95 mol%, more preferably 96 mol% or more, and even more preferably 97 mol% or more. As the rare-earth BR, commercially available products from companies such as Lanxess can be used.

[0119] SPB-containing BR refers to a type in which 1,2-syndiotactic polybutadiene crystals are not simply dispersed in BR, but are chemically bonded to and dispersed in BR. Such SPB-containing BR can be commercially available from companies such as UBE Corporation.

[0120] Examples of modified BR include BR modified with functional groups similar to those described for SBR above, as well as modified butadiene rubber (modified BR) in which the terminal and / or main chain is modified with functional groups containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen.

[0121] Other modified BRs include those obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and in which the ends of the modified BR molecule are linked by a tin-carbon bond (tin-modified BR). Furthermore, the modified BR may be either unhydrogenated or hydrogenated.

[0122] From the viewpoint of wear resistance, the weight-average molecular weight (Mw) of BR is preferably over 300,000, more preferably over 350,000, and even more preferably over 400,000. From the viewpoint of crosslinking uniformity, it is preferably less than 2,000,000, more preferably less than 1,000,000, and even more preferably less than 700,000. Mw can be determined by the method described above.

[0123] The BR content in the rubber component constituting the cap tread is preferably 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more. Furthermore, the content is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0124] (Other rubber components) The rubber component may include rubber components other than diene rubber (non-diene rubber) to the extent that it does not affect the effects of the invention. Examples of non-diene rubbers include rubber components commonly used in the tire industry, such as butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, polyethylene chloride rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. Other rubber components may be used individually or in combination of two or more. Furthermore, known thermoplastic elastomers may or may not be included in addition to the above-mentioned rubber components.

[0125] (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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] on the other hand, 14 C is continuously produced by cosmic rays undergoing 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.

[0133] 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 value obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date is the standard value. 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.

[0134] 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%.

[0135] 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.

[0136] <Filler> The rubber composition according to this embodiment preferably contains a filler. The filler preferably contains silica, and more preferably contains carbon black and silica. Alternatively, the filler may consist solely of carbon black and silica.

[0137] (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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] The nitrogen adsorption specific surface area (N2SA) of silica is 100m² from the perspective of reinforcing properties. 2 Preferably more than / g, 150m 2 More preferably than / g, 170m2 A value greater than / g is even more preferable. Also, from the viewpoint of heat generation and processability, 250m 2 Less than / g is preferable, 200m 2 Less than / g is more preferable, 180m 2 A value of less than / g is even more preferable. The N2SA of silica is measured by the measurement method described above.

[0142] From the viewpoint of reinforcing properties, the average primary particle diameter of silica is preferably greater than 10 nm, more preferably greater than 12 nm, and even more preferably greater than 15 nm. Furthermore, the average primary particle diameter is preferably less than 25 nm, and more preferably less than 20 nm. The average primary particle diameter of silica is measured by the measurement method described above.

[0143] From the viewpoint of wet grip performance, the silica content per 100 parts by mass of rubber component is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 70 parts by mass or more. Furthermore, the silica content per 100 parts by mass of rubber component is preferably less than 150 parts by mass, more preferably less than 120 parts by mass, and even more preferably less than 110 parts by mass.

[0144] The silica content in the filler is preferably more than 50% by mass, more preferably more than 60% by mass, even more preferably more than 70% by mass, and particularly preferably more than 80% by mass. Furthermore, there is no particular upper limit to the silica content in the filler, but from the viewpoint of blending carbon black and the like, it is preferably less than 98% by mass, and more preferably less than 96% by mass.

[0145] (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.

[0146] 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.

[0147] 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.

[0148] 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).

[0149] 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.

[0150] Recycled carbon black can be purchased from companies such as Strable Green Carbon and LD Carbon.

[0151] The nitrogen adsorption specific surface area (N2SA) of carbon black is 80 m² from the perspective of reinforcing properties. 2 Preferably more than / g, 90m2 More preferably than / g, 100m 2 More preferably than / g, 110m 2 A value exceeding / g is particularly preferred. Furthermore, from the viewpoint of heat generation and processability, 200m 2 Preferably less than / g, 150m 2 Less than / g is more preferable, 120m 2 A value of less than / g is even more preferable. The N2SA of carbon black is measured by the method described above.

[0152] The average primary particle diameter of the carbon black is preferably 15 nm or more, more preferably 18 nm or more, and even more preferably 20 nm or more. Furthermore, the particle diameter is preferably 80 nm or less, more preferably 50 nm or less, and even more preferably 40 nm or less. The average primary particle diameter of the carbon black is measured by the method described above.

[0153] From the viewpoint of reinforcing properties, the carbon black content is preferably more than 3 parts by mass, more preferably more than 5 parts by mass, and even more preferably more than 9 parts by mass, per 100 parts by mass of rubber component. Furthermore, from the viewpoint of processability, the carbon black content is preferably less than 40 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 15 parts by mass.

[0154] (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, clay, and biochar. These other fillers may be used individually or in combination of two or more.

[0155] 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 50 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 90 parts by mass or more, and particularly preferably 100 parts by mass or more. Furthermore, the content 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.

[0156] (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.

[0157] 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.

[0158] <Other compounding agents> In addition to the components mentioned above, the rubber composition according to this embodiment may also contain, as appropriate, compounding agents commonly used in the tire industry, such as plasticizers, vulcanized rubber particles (rubber powder), antioxidants, waxes, processing aids, stearic acid, zinc oxide, vulcanizing agents, and vulcanization accelerators.

[0159] In this specification, "plasticizer" refers to a material that imparts plasticity to rubber components, 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, and ester-based plasticizers. 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. Plasticizers may be used alone or in combination of two or more types.

[0160] (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.

[0161] ≪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.

[0162] ≪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.

[0163] ≪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.

[0164] <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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] ≪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.

[0170] 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.

[0171] The softening point of the resin component is preferably 35°C or higher, more preferably 50°C or higher, and even more preferably 65°C or higher. Furthermore, from the viewpoint of processability and improved dispersibility between the rubber component and the 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.

[0172] When a resin component is included, its content per 100 parts by mass of the rubber component is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 8 parts by mass or more. On the other hand, the content is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less.

[0173] (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.

[0174] 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.

[0175] 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.

[0176] 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.

[0177] 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. 1 When 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] Examples of animal oils include fish oil, beef tallow, whale oil, or oleyl alcohol which can be derived from them.

[0182] When oil is included, the oil content per 100 parts by mass of rubber component is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, even more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more. Furthermore, the oil content is preferably less than 80 parts by mass, more preferably less than 60 parts by mass, and even more preferably 40 parts by mass or less. Note that the oil content includes the amount of oil contained in the rubber component as an oil-expanding oil, as well as the amount of oil contained in other components such as sulfur.

[0183] (Liquid rubber) The 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), liquid farnesene rubber, etc. The liquid rubber may be used alone or in combination of two or more types.

[0184] The weight-average molecular weight (Mw) of liquid rubber is usually less than 10,000, preferably 9,000 or less, more preferably 6,000 or less, and even more preferably 4,500 or less. Furthermore, the Mw of liquid rubber is preferably 100 or more, more preferably 500 or more, even more preferably 1,000 or more, and particularly preferably 2,000 or more. When the Mw of liquid rubber is within the above range, the effects of the present invention tend to be better obtained. Note that in this specification, liquid rubber is not included in the above rubber components.

[0185] (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.

[0186] From the viewpoint of the effects of the present invention, the content of plasticizers per 100 parts by mass of rubber component (total amount if multiple plasticizers are used in combination) is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 35 parts by mass or more. Furthermore, the total content of plasticizers per 100 parts by mass of rubber component is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 60 parts by mass or less.

[0187] 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.

[0188] The vulcanized rubber particles are not particularly limited and may be either unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0189] Commercially available vulcanized rubber products can be used, such as those from Lehigh, Muraoka Rubber Industries, and others.

[0190] 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 Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flexis, and others. The antioxidant may be used alone or in combination of two or more.

[0191] 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, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0192] 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. The wax may be used alone or in combination of two or more types.

[0193] 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, and more preferably 0.8 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.

[0194] Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. 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.

[0195] 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.

[0196] When zinc oxide is included, its content per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, and more preferably 1.0 part 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.

[0197] 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.

[0198] 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, and even more preferably 0.5 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.

[0199] 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.

[0200] 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. The vulcanization accelerator may be used alone 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. The vulcanization accelerator may be used alone or in combination of two or more.

[0201] 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).

[0202] 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. Of these, MBTS and MBT are preferred, with MBTS being more preferred.

[0203] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt 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. However, when the rubber composition constituting the topping rubber contains a guanidine-based vulcanization accelerator, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or less, more preferably 0.3 parts by mass or less, even more preferably 0.1 parts by mass or less, and particularly preferably no guanidine-based vulcanization accelerator is contained, from the viewpoint of the effects of the present invention.

[0204] 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 1.0 part by mass or more, and even more preferably 1.5 parts 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.

[0205] 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.

[0206] <Manufacturing> 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.).

[0207] The mixing process includes, for example, a base mixing process in which compounding agents and additives other than the vulcanizing agent and vulcanization accelerator are mixed, and a final mixing (F mixing) process in which the vulcanizing agent and vulcanization accelerator are added to the mixture obtained in the base mixing process and mixed. Furthermore, the base mixing process can be divided into multiple processes as desired. When dividing the base mixing process, the method may be (1) a method in which some of the compounding agents and additives are mixed in advance to form a masterbatch, and then the remaining compounding agents and additives are added to the resulting masterbatch and mixed, or (2) a method in which all the compounding agents and additives to be mixed in the base mixing process are mixed at once, and then the mixture is remilled one or more times. In the method of (1) above, the number of masterbatches is not limited and may be two or more. Also, when the number of masterbatches is two or more, all the compounding agents and additives used in the base mixing process may be allocated to one of the masterbatches.

[0208] While there are no particular limitations on the mixing conditions, one example is to mix the base mixture at a discharge temperature of 150-170°C for 3-10 minutes, and then mix the final mixture at 70-110°C for 1-5 minutes.

[0209] The pneumatic tire according to this embodiment can be manufactured by conventional methods using the unvulcanized rubber composition obtained above. Specifically, first, the unvulcanized rubber composition is extruded to match the shape of the cap tread to obtain an unvulcanized cap tread. The unvulcanized cap tread thus obtained is bonded together with other tire components such as the base tread on a tire molding machine by conventional methods to form an unvulcanized tire. At this time, the structure of Ga, Gb and the carcass cord is made to be predetermined. Also, if necessary, the reinforcing layer is made to be made to be predetermined. The pneumatic tire according to this embodiment can be manufactured by heating and pressurizing the unvulcanized tire thus obtained in a vulcanizing machine. The vulcanization conditions are not particularly limited, and for example, a method of vulcanization at 150 to 200°C for 10 to 40 minutes can be cited.

[0210] <Application> The pneumatic tire according to this embodiment can be used for any application, including passenger car tires, large passenger car tires, large SUV tires, racing tires, motorcycle tires, heavy-duty tires, and run-flat tires. A passenger car tire refers to a tire intended for use on a four-wheeled vehicle with a maximum load capacity of less than 1400 kg. A heavy-duty tire refers to a tire with a maximum load capacity of 1400 kg or more. Furthermore, in this specification, the tire can be used as an all-season tire, a summer tire, or a winter tire such as a studless tire. [Examples]

[0211] The following examples (case studies) are shown as preferred for implementation, but the scope of the present invention is not limited to these examples. According to each table, we examined cap treads and tires having tire structures obtained using the various chemicals shown below, and the results calculated based on the evaluation method described below are shown at the bottom of each table.

[0212] <Various chemicals> The chemicals used in the examples and comparative examples are described below. IR-type rubber: NR (TSR20) SBR: HPR850 manufactured by ENEOS Material Co., Ltd. (Tg: -25℃, Styrene content: 26% by mass, Vinyl content: 59 mol%, Mw: 190,000, Non-oil product) BR: UBEPOL BR150B manufactured by UBE Elastomer Co., Ltd. (Unmodified BR, cis content: 96 mol%, Mw: 440,000) Carbon Black: Show Black N220 (N2SA: 111m) manufactured by Cabot Japan Co., Ltd. 2 / g, average primary particle diameter: 22nm) Silica: Ultrazil VN3 (N2SA: 175m) manufactured by Evonik Industries. 2 / g, average primary particle diameter: 18nm) Coupling agent (silane coupling agent): Si266 (bis(3-triethoxysilylpropyl) disulfide) from Evonik Industries. Resin component: Clayton's SYLVATRAXX4401 (aromatic vinyl resin (polymer of α-methylstyrene and styrene), softening point: 85°C) Oil: VivaTec500 (TDAE oil) manufactured by H&R Co., Ltd. Wax: Ozoace 0355 (paraffin wax) manufactured by Nippon Seiro Co., Ltd. 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 1: Noxellar D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noxellar CZ-G (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0213] <Examples and Comparative Examples> According to the formulations shown in each table, the chemicals other than sulfur and vulcanization accelerator are mixed in a 1.7L Banbury mixer for 5 minutes until the discharge temperature reaches 160°C to obtain a mixture. Next, sulfur and vulcanization accelerator are added to the mixture and mixed in a twin-screw open roll for 4 minutes until the temperature reaches 105°C to obtain an unvulcanized rubber composition for cap treads.

[0214] Using the obtained unvulcanized rubber composition, it is extruded to match the shape of the cap tread using an extruder equipped with a die of a predetermined shape, and bonded together with other tire components while adjusting to form a predetermined tire structure to produce an unvulcanized tire. Each test tire (tire size: 245 / 45R18) is then manufactured by press vulcanization at 150°C for 35 minutes.

[0215] <Measurement of 30℃E*> Each vulcanized rubber test piece, cut from the cap 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 complex modulus E* measured using a dynamic viscoelasticity measuring device (GABO's Iplexer series) under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and the extension mode.

[0216] The tire structure in each table is explained below. In the tire in Table 1, the inclination angles of the carcass cords are +75° for A1 and +85° for A2, and the maximum width of the land portion is 20 mm for W1 and 28 mm for W2. Therefore, for equation (1), |A2-A1|=10°, for equation (2), W1 / W2=0.71, and for equation (4), (W1-0.3×W2) / |A2-A1|=1.1. Also, in the tire in Table 2, the inclination angles of the carcass cords are +75° for A1 and +80° for A2, and the maximum width of the land portion is 20 mm for W1 and 20 mm for W2. Therefore, for equation (1), |A2-A1|=5°, for equation (2), W1 / W2=1.0, and for equation (4), (W1-0.3×W2) / |A2-A1|=2.8. Note that the tires in Tables 1 and 2 have the tread pattern shown in Figure 2, and the carcass cords are polyester cords.

[0217] In each table, the 30°CE related to formula (3) * The value of c × |A2 - A1| × (W1 - 0.3 × W2) can be compared with the constant K. That is, if this value is greater than the constant K, then equation (3) is satisfied.

[0218] <Wear resistance> Each test tire was mounted on all wheels of a vehicle (domestic FF 2000cc), and the tread groove depth was measured after 15,000 kilometers of driving on paved roads. The distance traveled when the groove depth decreased by 1 mm was calculated. The distance traveled by the control tire (Comparative Example 1 in Table 1, Comparative Example 2 in Table 2) was set to 100, and the wear resistance performance of each tire was expressed as an index using the following formula. A higher index indicates better wear resistance. (Wear resistance index) = (Distance traveled by each test tire) / (Distance traveled by the control tire) × 100

[0219] [Table 1]

[0220] [Table 2]

[0221] <Embodiment> Examples of embodiments of the present invention are shown below.

[0222] [1] A pneumatic tire comprising a carcass, a reinforcing layer disposed radially outward of the carcass, and a cap tread disposed radially outward of the reinforcing layer, wherein the cap tread has a plurality of circumferential main grooves extending continuously in the circumferential direction of the tire, and a plurality of land portions separated by the circumferential main grooves and the contact end, the cap tread is made of a rubber composition containing a rubber component, the carcass is made of at least one carcass ply comprising a plurality of carcass cords and a topping rubber covering the carcass cords, and the reinforcing layer comprises a plurality of reinforcing layer cords and a topping rubber covering the reinforcing layer cords, Each is composed of a single reinforcing layer ply, and the stretching direction of the carcass cords of at least one of the carcass plies, preferably the stretching direction of the carcass cords of the outermost carcass ply in the tire radial direction, is defined as the angle at which it is inclined from the tire circumferential direction at the position of the tire centerline, the angle at which it is inclined from the tire circumferential direction at the position of the tire's maximum width, the width of the land portion closest to the tire centerline of the land portion, the width of the land portion adjacent to the land portion closest to the tire centerline on the tire axial side, and the complex modulus of elasticity of the rubber composition constituting the cap tread at 30°C is defined as 30°CE * c, If the constant is K, then A1, A2, W1, W2, 30℃E * A pneumatic tire in which c and K satisfy the following equations (1), (2), and (3). (1)|A2-A1|>0 (2) W1 / W2 > 0.30 (3) 30℃E * c>K / {|A2-A1|×(W1-0.3×W2)} (However, K is 410) [2] The pneumatic tire described in [1] above, wherein the constant K in formula (2) is 500. [3] The pneumatic tire according to [1] or [2] above, wherein the rubber component constituting the cap tread includes isoprene rubber. [4] The pneumatic tire according to any one of [1] to [3] above, wherein the rubber composition constituting the cap tread contains silica having an average primary particle diameter of 18 nm or less. [5] The pneumatic tire according to any one of [1] to [4] above, wherein the rubber composition constituting the cap tread contains a resin component. [6] The pneumatic tire according to any one of [1] to [5] above, wherein A1, A2, W1, and W2 satisfy the following formula (4). (4) (W1 - 0.3×W2) / |A2 - A1| > 0.30 [7] In at least one of the reinforcing layer plies, the angle A RF (°) by which the extending direction of the reinforcing layer cord inclines from the tire circumferential direction is different from A1 (°), the pneumatic tire according to any one of [1] to [6] above. [8] The inclination direction of A RF from the tire circumferential direction is opposite to the inclination direction of A1 from the tire circumferential direction, the pneumatic tire according to [7] above. [9] The reinforcing layer including a reinforcing layer ply in which the angle by which the extending direction of the reinforcing layer cord inclines from the tire circumferential direction is A RF (°) is composed of a single reinforcing layer ply, the pneumatic tire according to [7] or [8] above.

[10] The reinforcing layer ply in which the angle by which the extending direction of the reinforcing layer cord inclines from the tire circumferential direction is A RF (°) is a belt ply, the pneumatic tire according to any one of [7] to [9] above.

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

[10] above, wherein the at least one reinforcing layer consists only of a belt.

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

[11] above, wherein the carcass is composed of a single carcass ply.

[13] A2 is +70° or more and +90° or less, preferably +75° or more and +85° or less, more preferably +80° or more and +85° or less, or -70° or less and more than -90°, preferably -75° or less and -85° or more, more preferably -80° or less and -85° or more. The pneumatic tire according to any one of the above [1] to

[12] .

Explanation of symbols

[0223] 1 Tread 2 Sidewall 3 Bead part 3a Bead apex 3b Bead core 5 Cap tread 6 Base tread 7 Carcass 8 Belt 9 Band 10 Reinforcement layer 11, 12, 13 Circumferential main grooves 16, 17 Shoulder land 18, 19 Center land 21 Shoulder transverse groove 22 Shoulder sip 23 Center sip CL Tire center line Tо, Ti Tread grounding end W Tire width direction W1 Width of the land closest to the tire center line W2 Width of the land adjacent to the outside in the tire axial direction of the land closest to the tire center line P Tire maximum width position A1 Angle at which the extension direction of the carcass cord inclines from the tire circumferential direction at the position of the tire center line A2 Angle at which the extension direction of the carcass cord inclines from the tire circumferential direction at the tire maximum width position A RF Angle at which the extension direction of the reinforcement layer cord inclines from the tire circumferential direction

Claims

1. A pneumatic tire comprising a carcass, a reinforcing layer positioned radially outward of the carcass, and a cap tread positioned radially outward of the reinforcing layer, The cap tread has a plurality of circumferential main grooves that extend continuously in the circumferential direction of the tire, and a plurality of land portions separated by the circumferential main grooves and the contact edge. The aforementioned cap tread is made of a rubber composition containing rubber components, The carcass is composed of at least one carcass ply comprising a plurality of carcass cords and a topping rubber covering the carcass cords. The reinforcing layer is composed of at least one reinforcing layer ply comprising a plurality of reinforcing layer cords and a topping rubber covering the reinforcing layer cords. Among the carcass plies, for at least any one of the carcass plies, the angle A at which the extending direction of the carcass cord inclines from the tire circumferential direction at the position of the tire center line 1 (°), and the angle A at which the extending direction of the carcass cord inclines from the tire circumferential direction at the position of the maximum tire width 2 (°), the tread width W of the tread closest to the tire center line among the tread portions 1 (mm), the tread width W of the tread portion adjacent to the outside in the tire axial direction of the tread portion closest to the tire center line 2 (mm), the complex elastic modulus at 30°C of the rubber composition constituting the cap tread is 30°C E * c, when the constant is K, an air-filled tire in which A 1 , A 2 , W 1 , W 2 , 30°C E * c and K satisfy the following formulas (1), (2) and (3). (1)|A 2 -A 1 |>0 (2)W 1 / W 2 >0.30 (3)30℃E * c>K / {|A 2 -A 1 |×(W 1 -0.3×W 2 )} (However, K is 410)

2. The pneumatic tire according to claim 1, wherein the constant K in formula (2) is 500.

3. The pneumatic tire according to claim 1 or 2, wherein the rubber component constituting the cap tread includes isoprene-based rubber.

4. The pneumatic tire according to claim 1 or 2, wherein the rubber composition constituting the cap tread contains silica with an average primary particle diameter of 18 nm or less.

5. The pneumatic tire according to claim 1 or 2, wherein the rubber composition constituting the cap tread includes a resin component.

6. A 1 , A 2 , the aforementioned W 1 , and the W 2 A pneumatic tire according to claim 1 or 2, wherein the following formula (4) is satisfied. (4)(W 1 -0.3×W 2 ) / |A 2 -A 1 |>0.30

7. In at least one of the reinforcing layer plies, the angle A inclined by the extension direction of the reinforcing layer cord from the tire circumferential direction. RF (°) is the above A 1 A pneumatic tire according to claim 1 or 2, which is different from (°).

8. A RF The inclination direction from the tire circumferential direction is the A 1 The pneumatic tire according to claim 7, wherein the direction of inclination is opposite to the direction of inclination from the circumferential direction of the tire.

9. The angle at which the extension direction of the reinforcing layer cord is inclined from the tire circumferential direction is A. RF The pneumatic tire according to claim 7, wherein the reinforcing layer, which includes a reinforcing layer ply that is (°), is composed of a single reinforcing layer ply.

10. The angle at which the extension direction of the reinforcing layer cord is inclined from the tire circumferential direction is A. RF The pneumatic tire according to claim 7, wherein the reinforcing layer ply, which is (°), is a belt ply.

11. The pneumatic tire according to claim 1 or 2, wherein the at least one reinforcing layer consists only of a belt.

12. The pneumatic tire according to claim 1 or 2, wherein the carcass is composed of a single carcass ply.

13. A 2 A pneumatic tire according to claim 1 or 2, wherein the angle is +70° or more and +90° or less, or -70° or less and greater than -90°.

Images