tire

Abstract

To provide a tire which improves total performances of a grip performance during turning.SOLUTION: The tire comprises a tread part, a side wall, a carcass, and a strip apex, wherein the strip apex is present inside in a tire axial direction of the side wall or inside in a tire axial direction of a winding / returning part of the carcass, and the tread part, the side wall, and the strip apex are constituted of a rubber composition including rubber constituents. When a land ratio of the tire is L, L is 0.60 or more, the rubber composition which constitutes the tread part contains an organic cross-linking agent, and when an acetone extraction amount of the rubber composition which constitutes the tread part is AE1 (mass %), an acetone extraction amount of the rubber composition which constitutes the side wall is AE2 (mass %), and an acetone extraction amount of the rubber composition which constitutes the strip apex is AE3 (mass %), AE1>AE2>AE3.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a tire. [Background technology]

[0002] In recent years, with the advancement of vehicle performance, there has been a demand for improved grip performance during cornering in tires for four-wheeled vehicles as well. For example, Patent Document 1 describes that a rubber composition containing a polymer modified with a dihydric phenol compound and silica improves the fuel economy and wet grip performance of tires. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-155706 Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 does not take into consideration grip performance during cornering.

[0005] An object of the present invention is to provide a tire that improves grip performance during cornering. [Means for solving the problem]

[0006] The present invention provides A tire having a tread portion, a sidewall, a carcass, and a strip apex, the strip apex is located on the axially inner side of the sidewall or the axially inner side of the carcass turnup portion, the tread portion, the sidewall, and the strip apex are made of a rubber composition containing a rubber component, When the land ratio of the tire is L, L is 0.60 or more, the rubber composition constituting the tread portion contains an organic crosslinking agent, The acetone extractable amount of the rubber composition constituting the tread portion is AE1 (mass%), The acetone extractable amount of the rubber composition constituting the sidewall is AE2 (mass%), When the acetone extractable amount of the rubber composition constituting the strip apex is AE3 (mass%), AE1>AE2>AE3 This is about tires. [Effects of the Invention]

[0007] According to the present invention, a tire is provided that has improved grip performance during cornering. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a tire according to an embodiment of the present invention, taken along the tire rotation axis. [Figure 2] 1 is a schematic development view of a tread portion showing one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] One embodiment of the present invention relates to a tire having a tread portion, sidewalls, a carcass, and a strip apex, wherein the strip apex is located axially inward of the sidewall or axially inward of the carcass turnup portion, the tread portion, the sidewalls, and the strip apex are made of a rubber composition containing a rubber component, and when the land ratio of the tire is L, L is 0.60 or more, the rubber composition constituting the tread portion contains an organic crosslinking agent, and when the acetone extractable amount of the rubber composition constituting the tread portion is AE1 (mass %), the acetone extractable amount of the rubber composition constituting the sidewall is AE2 (mass %), and the acetone extractable amount of the rubber composition constituting the strip apex is AE3 (mass %), the relationship AE1>AE2>AE3.

[0010] The reason why the grip performance during cornering is improved in the tire of this embodiment is thought to be, for example, as follows, although it is not intended to be bound by theory.

[0011] First, (1) when the steering wheel is turned while a load is applied to the tire, strain is transmitted from the rim to the sidewall and from the sidewall to the tread. Because there is a large difference in rigidity between the rim and the sidewall made of a rubber composition, strain from the rim is not easily transmitted to the sidewall, resulting in poor ground contact in the tread. Therefore, the presence of a strip apex made of a rubber composition on the axially inner side of the sidewall or the axially inner side of the carcass turnup portion is thought to make it easier for strain from the rim to be transmitted to the sidewall.

[0012] In addition, (2) by setting the tire's land ratio L to 0.60 or more, it is believed that the contact of the tread with the road surface is improved, contributing to improved grip performance during cornering.

[0013] Furthermore, (3) by compounding an organic cross-linking agent into the rubber composition that makes up the tread, the reinforcement between polymer chains is improved through the incorporation of carbon bonds, ensuring appropriate rigidity against heat and distortion generated during driving, which is thought to improve the tire's ability to follow the road surface and contribute to improved grip performance.

[0014] (4) By setting the rubber composition constituting the sidewall to an appropriate rigidity, the sidewall flexes when the vehicle is running, which is thought to contribute to improving the ground contact of the tread. In this embodiment, by making the rigidity of the tread lower than that of the sidewall, AE1>AE2, the ground contact of the tread is ensured, which is thought to contribute to improving grip performance during cornering.

[0015] Furthermore, (5) by making the order AE1>AE2>AE3, strain can be transmitted in stages from the rim to the sidewall and from the sidewall to the tread, which is thought to efficiently deform the tread and contribute to improved grip performance during cornering.

[0016] It is believed that the above (1) to (5) work together to achieve the remarkable effect of improving grip performance during cornering.

[0017] The land ratio L is preferably 0.70 or more, and more preferably 0.80 or more, because it is believed that the contact of the tread portion with the road surface improves, further improving grip performance during cornering.

[0018] The product (Hs×L) of the rubber hardness Hs and L of the rubber composition constituting the tread portion is preferably less than 49.

[0019] By setting Hs × L to less than 40, the rubber hardness of the tread area can be appropriately reduced relative to the land ratio, reducing the difference in rigidity with the sidewall and strip apex, which is thought to further improve grip performance during cornering.

[0020] The complex modulus of elasticity at 30°C of the rubber composition constituting the tread portion is 30°C E* T (MPa), 30℃E* T and L (30°C E* T ×L) is preferably less than 20.

[0021] 30°C* T By setting ×L to less than 20, the rigidity of the tread portion relative to the land ratio can be appropriately reduced, and the difference in rigidity with the sidewall and strip apex can be reduced, which is thought to further improve grip performance during cornering.

[0022] The product of AE3 and L (AE3×L) is preferably greater than 3.5.

[0023] By making AE3×L greater than 3.5, the rigidity of the strip apex relative to the land ratio can be increased appropriately, reducing the difference in rigidity with the rim, which is thought to further improve grip performance during cornering.

[0024] The complex modulus of elasticity at 70°C of the rubber composition constituting the sidewall is 70°C E* S (MPa), 70℃E* S and L (70℃E* S ×L) is preferably greater than 5.0.

[0025] 70°C E* S By making ×L greater than 5.0, it is possible to increase the rigidity of the sidewall appropriately relative to the land ratio, reducing the difference in rigidity with the strip apex, making it easier to transmit strain to the tread portion, and it is thought that this will further improve grip performance during cornering.

[0026] The organic crosslinking agent is preferably a dithiocarbamic acid compound.

[0027] By including a dithiocarbamic acid compound in the rubber composition that makes up the tread, cleavage due to heat and strain during driving is less likely to occur, the reinforcement between polymer chains is improved, appropriate rigidity can be ensured against heat and strain generated during driving, road conformity is improved, and grip performance is thought to be further improved.

[0028] The rubber composition constituting the sidewall preferably contains 20% by mass or more of butadiene rubber in the rubber component.

[0029] By including a certain amount of butadiene rubber in the sidewall, the glass transition temperature (Tg) of the rubber composition does not become too low, and a certain level of heat buildup can be achieved even when cornering, which is thought to further improve grip performance when cornering.

[0030] The rubber composition constituting the sidewall preferably contains a resin component, which is believed to further improve grip performance during cornering.

[0031] The total styrene content in the rubber component of the rubber composition constituting the tread portion is preferably 20% by mass or more. By setting the total styrene content in the rubber component within this range, the styrene groups increase, improving heat buildup, and is therefore thought to further improve grip performance.

[0032] In the tread portion, when the land ratio of the contact surface of the outer tread portion constituting the vehicle outer end side with respect to the tire equator is Lo and the land ratio of the contact surface of the inner tread portion constituting the vehicle inner end side is Li, it is preferable that the absolute value of the difference between Lo and Li (Lo-Li) is greater than 0 and less than 0.2.

[0033] When the absolute value of Lo-Li is greater than 0 and less than 0.2, the difference in land ratio between the inner tread and the outer tread is small, and the contact area of ​​the tread surface during cornering is large, which is thought to improve grip performance during cornering.

[0034] AE3 is preferably 4.0% by mass or more.

[0035] By having a certain level of acetone extractable amount of the rubber composition that makes up the strip apex, it is possible to moderately increase the rigidity of the strip apex and reduce the difference in rigidity with the rim, which is thought to further improve grip performance during cornering.

[0036] AE1×L is preferably equal to or greater than 14.0. Even when the amount of acetone extracted from the tread portion is small, it is believed that grip performance can be ensured by increasing the land ratio L.

[0037] The rubber composition constituting the tread portion preferably contains carbon black having an average primary particle size of 30 nm or less. By containing carbon black with a small particle size, high heat buildup can be achieved through friction between particles, which is thought to further improve wet grip performance.

[0038] [Definition] "Normal condition" refers to a condition in which the tire is mounted on a normal rim and filled with air at normal internal pressure, with no load applied.

[0039] Unless otherwise specified, the "dimensions of each part of the tire" are values ​​that are specified when they appear on the outer surface of the tire in a normal state, while those that exist inside the tire or on a cut surface of the tire are values ​​that are specified when, for example, the tire is cut along a plane that includes the tire rotation axis and the cut tire piece is maintained at the rim width of a normal rim.

[0040] "Genuine rim" refers to the rim specified for each tire in the standard system that includes the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Manufacturers Association), it refers to the "standard rim" for the applicable size listed in the "Jatma Year Book," in the case of ETRTO (The European Tyre and Rim Technical Organization), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and in the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." JATMA, ETRTO, and TRA are referenced in that order, and if an applicable size is available at the time of reference, that standard is followed. In the case of tires not specified in the above standards, it refers to the narrowest rim among the smallest diameter rims that can be mounted on the rim and can maintain internal pressure (i.e., no air leaks from between the rim and tire).

[0041] "Normal internal pressure" refers to the air pressure specified for each tire in the standard system that includes 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 follow the standard if there is an applicable size at the time of reference. In the case of tires not specified in the standard, it refers to the normal internal pressure (250kPa or more) of another tire size (defined in the standard) that is specified using the regular rim as the standard rim. If there are multiple normal internal pressures of 250kPa or more listed, it refers to the smallest value among them.

[0042] "Normal load" refers to the load specified for each tire in the standard system that includes the standard on which the tire is based. 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 normal rims and normal internal pressures, JATMA, ETRTO, and TRA should be referenced in that order, and if there is an applicable size at the time of reference, that standard should be followed. For tires not specified in the above standards, the maximum load capacity W calculated separately should be used. L is the normal load.

[0043] "Maximum load capacity W L " is calculated using the following formula: "V" is the virtual volume of the tire (mm 3), "Dt" is the outer diameter (mm) of the tire in its normal state, "Ht" is the tire's cross-sectional height (mm) in the tire's radial direction in a cross section of the tire taken along a plane including the tire's rotation axis, and "Wt" is the tire's cross-sectional width (mm) in its normal state. Ht can be calculated by (Dt-R) / 2, where R is the tire rim diameter. Wt is the value obtained by excluding any patterns or letters on the tire sidewall. Note that maximum load capacity is synonymous with the normal load mentioned above.

[0044]

number

[0045] The "contact area" is the area of ​​the tread obtained from the outline of the tire when pressed against the ground. It is obtained by mounting the tire on a standard rim, inflating it to the standard internal pressure, and leaving it at 25°C for 24 hours, then applying ink to the tire tread surface, and applying a standard load (a load equal to the maximum load capacity) to the tire and pressing it vertically against cardboard (camber angle 0°) to transfer the ink. The area of ​​the contact area is called the total contact area. The total contact area can be calculated by rotating the tire 72° and performing the above transfer process at a total of five locations, then averaging the five areas obtained.

[0046] The "effective contact area" is the area of ​​the tread that comes into contact with the tire when it is pressed against the ground. It is obtained by mounting the tire on a standard rim, inflating it to the standard internal pressure, leaving it at 25°C for 24 hours, then applying ink to the surface of the tire tread, and applying a standard load (a load equal to the maximum load capacity) to the tire and pressing it perpendicularly onto cardboard (camber angle 0°) to transfer the ink. The area of ​​the effective contact area is called the effective contact area. The effective contact area can be calculated by rotating the tire 72° each time and performing the above transfer process at a total of five locations, then averaging the five areas obtained.

[0047] The "land ratio L" is calculated from the total ground contact area of ​​the ground contact region and the effective ground contact area of ​​the effective ground contact region by the following formula, and is expressed as 0 to 1.0. Land ratio L = (effective contact area / total contact area)

[0048] The "tread portion" refers to a component that includes the portion that forms the tire's contact surface, and in the case where the tire is provided with components that form the tire skeleton from steel or textile materials, such as a belt layer, a belt reinforcing layer, and a carcass, the "tread portion" is a component that is located radially outward of these components in the tire radial cross section.

[0049] The term "sidewall" refers to a component that includes a portion that forms the side surface of a tire, and is positioned radially inward of the tread portion and radially outward of the bead portion.

[0050] "Carcass" refers to the component containing the rubber-coated cord layers that form the skeleton of the tire.

[0051] "Acetone extractables (AE)" is a value calculated in accordance with JIS K 6229 by immersing each vulcanized rubber test piece in acetone at room temperature (approximately 25°C) for 72 hours to extract the soluble components, measuring the mass of each test piece before and after extraction, and then using the following formula. Acetone extractable amount (mass%) = {(mass of rubber test piece before extraction - mass of rubber test piece after extraction) / (mass of rubber test piece before extraction)} × 100

[0052] The "hardness of the rubber composition" is the Shore hardness (Hs) measured at a temperature of 23°C using a Type A durometer in accordance with JIS K 6253-3:2012. When a measurement sample is prepared from the tread portion of a tire, the rubber composition is cut out from the surface side that forms the tire's contact patch so that the thickness direction is the tire radial direction, and the Type A durometer is pressed against the sample from the contact patch side to measure.

[0053] The "loss tangent and complex modulus of a rubber composition" refer to the loss tangent (tanδ) and complex modulus E* (MPa) measured under various conditions in extension mode using a dynamic viscoelasticity measuring device (e.g., the Iplexer series manufactured by GABO). The sample used for dynamic viscoelasticity measurement is a rubber composition measuring 20 mm in length, 4 mm in width, and 1 mm in thickness. When preparing a sample by cutting it out of a tire, if the component from which the sample is prepared is the tread portion, belt reinforcing layer, belt layer, or inner liner, the length direction of the sample should be aligned with the tire circumferential direction, and the thickness direction of the sample should be aligned with the tire radial direction. If the component from which the sample is prepared is the sidewall, clinch portion, bead apex, or strip apex, the length direction of the sample should be aligned with the tangent direction to the tire circumference, and the thickness direction of the sample should be aligned with the tire width direction. In either case, the sample is prepared with dimensions as close to the specified dimensions as possible. This is because the strain applied to the sample is normalized with respect to the length, and both tan δ and E* measured are normalized with respect to the width and thickness of the sample, and therefore it is considered that there is no effect due to the size of the sample. If the sample cannot be prepared by cutting it out from the tire, the unvulcanized rubber composition obtained by kneading can be vulcanized to prepare a test rubber sheet, and the sample can be cut out from the rubber sheet.

[0054] "30°C E*" is the complex modulus E* (MPa) measured 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 an extension mode.

[0055] "70°C E*" is the complex modulus E* (MPa) measured under the conditions of a temperature of 70°C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±1%, and an extension mode.

[0056] The "total styrene content in the rubber component" refers to the total content (mass%) of styrene moieties in 100% by mass of the rubber component. This is calculated by multiplying the styrene content (mass%) of each rubber component by the mass fraction in the rubber component, and then adding up the resulting values. Specifically, it is calculated as Σ(styrene content (mass%) of each styrene-containing rubber × content (mass%) of each styrene-containing rubber in the rubber component / 100). For example, if the rubber component consists of 30% by mass of a first SBR (styrene content: 25% by mass), 60% by mass of a second SBR (styrene content: 27.5% by mass), and 10% by mass of BR, the total styrene content (S) in 100% by mass of the rubber component is 24.0% by mass (= 25 × 30 / 100 + 27.5 × 60 / 100 + 0 × 10 / 100).

[0057] The "rubber component of the rubber composition" is a component that contributes to crosslinking within the rubber composition, and generally has a weight average molecular weight (Mw) of 10,000 or more.

[0058] The "land portion" refers to the portion of the tread that comes into contact with the ground when the tire is pressed against the ground, and is the portion of the tread that constitutes the effective contact area.

[0059] "Styrene content" is 1 This is a value calculated by H-NMR measurement, and is applied to rubber components having repeating units derived from styrene (styrene unit-containing rubber), such as SBR.

[0060] The "vinyl content (amount of 1,2-bonded butadiene units)" is a value calculated by infrared absorption spectroscopy in accordance with JIS K 6239-2:2017, and applies to rubber components having repeating units derived from butadiene, such as SBR and BR.

[0061] The "cis content (amount of cis-1,4-bonded butadiene units)" is a value calculated by infrared absorption spectroscopy in accordance with JIS K 6239-2:2017, and applies to rubber components having repeating units derived from butadiene, such as BR.

[0062] The "weight average molecular weight (Mw)" can be determined by converting the measured value into standard polystyrene equivalents using gel permeation chromatography (GPC) (for example, a GPC-8000 series manufactured by Tosoh Corporation, a differential refractometer as the detector, and a TSKgel SuperMultipore HZ-M column manufactured by Tosoh Corporation). This applies to, for example, SBR, BR, plasticizers, etc.

[0063] The "nitrogen adsorption specific surface area (N2SA) of carbon black" is measured in accordance with JIS K 6217-2:2017. The "nitrogen adsorption specific surface area (N2SA) of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0064] The "average primary particle size" is calculated by photographing particles with a transmission or scanning electron microscope and taking the arithmetic average of the particle sizes of 400 particles. If the particle shape is nearly circular, the diameter of the circle is used as the particle size; if it is needle-like or rod-like, the minor axis is used as the particle size; otherwise, the equivalent circle diameter is calculated from the electron microscope image. The equivalent circle diameter is calculated as the positive square root of [4 x (particle area) / π]. The average primary particle size applies to silica, carbon black, etc.

[0065] The "plasticizer content" includes the amount of plasticizer contained in an extended rubber component that has been previously extended with a plasticizer such as oil, a resin component, or a liquid rubber component. The same applies to the oil content, the resin component content, and the liquid rubber content. For example, if the extended component is oil, the extended oil is included in the oil content.

[0066] The "softening point of the resin component" is the softening point specified in JIS K 6220-1:2015 7.7 measured using a ring and ball softening point tester, and is the temperature at which the ball drops.

[0067] [tire] A tire according to an embodiment of the present invention will be described below with reference to the drawings. Note that the embodiment described below is merely an example, and the tire according to the present embodiment is not limited to the following embodiment.

[0068] Fig. 1 illustrates an example of a tire according to one embodiment of the present invention. Fig. 1 shows a portion of a cross section of the tire taken along a plane including the tire rotation axis. In Fig. 1, the up-down direction is the tire's radial direction, the left-right direction is the tire's axial direction, and the direction perpendicular to the paper surface is the tire's circumferential direction. In Fig. 1, a dashed line CL represents the tire equator.

[0069] The tire in Fig. 1 has a tread portion 1 that comes into contact with the ground during running, a sidewall 2 that extends radially outward in the tire direction, a bead portion 3, a carcass 4, and a strip apex 5. The strip apex 5 is located axially inward of the sidewall 2.

[0070] As shown in FIG. 1 , a belt layer 16 is provided on the radially inner side of the tread portion 1. A carcass 4 and an inner liner 7 are laminated below the belt layer 16. A band layer 6 may also be present between the tread portion 1 and the belt layer 16. The bead portion 3 includes a bead core 14 and a bead apex 13 extending from the core radially outward in the tire direction. The bead apex 13 tapers radially outward in the tire direction. In the bead portion 3, a clinch portion 10 is provided on the outer side of the carcass 4, which contacts the rim 8 when the rim 8 is mounted thereon, and the clinch portion 10 is made of a rubber composition containing a rubber component. A rim chafer 9 may also be present between the clinch portion 10 and the rim 8.

[0071] <Tread> The tread portion 1 is made of a rubber composition containing a rubber component and an organic crosslinking agent. The tread portion 1 may include a single rubber layer or two or more rubber layers. When the tread portion includes two or more rubber layers, the physical properties of the rubber composition constituting the tread portion, such as the AE amount and rubber hardness, may be satisfied by any of the rubber layers, but it is preferable that the layer (cap rubber layer) that constitutes the outer surface of the tread surface satisfy these properties.

[0072] From the viewpoint of the effects of the present invention, the acetone extractable amount AE1 of the rubber composition constituting the tread portion is larger than the acetone extractable amount AE2 of the rubber composition constituting the sidewall, and specifically, it is preferably 12.0% by mass or more, more preferably 15.0% by mass or more, even more preferably 17.0% by mass or more, still more preferably 20.0% by mass or more, still more preferably 22.0% by mass or more, still more preferably 25.0% by mass or more, still more preferably 27.0% by mass or more, and particularly preferably 30.0% by mass or more. Also, from the viewpoint of fuel economy and heat buildup reduction, AE1 is preferably 40.0% by mass or less, more preferably 38.0% by mass or less, and still more preferably 35.0% by mass or less.

[0073] The acetone extractables (AE) can be adjusted by changing the types and amounts of chemicals added to the rubber composition. For example, the acetone extractables can be increased by increasing the oil content.

[0074] From the viewpoint of the effects of the present invention, the hardness Hs of the rubber composition constituting the tread portion is preferably 40 or more, more preferably 50 or more, even more preferably 55 or more, and particularly preferably 60 or more. From the viewpoint of grip performance, the hardness Hs is preferably 100 or less, more preferably 90 or less, and even more preferably 80 or less.

[0075] The rubber hardness of the rubber composition can be adjusted by conventional methods in the tire industry, specifically by changing the types and amounts of chemicals (e.g., rubber components, fillers, resin components, sulfur, vulcanization accelerators, silane coupling agents, etc.) compounded in the rubber composition. For example, increasing the oil content can lower the rubber hardness, and conversely, decreasing the oil content can increase the rubber hardness. Therefore, those skilled in the art can adjust the rubber hardness as appropriate.

[0076] The complex modulus of elasticity at 30°C of the rubber composition that constitutes the tread (30°C E* T) is preferably 8.0 MPa or more, more preferably 10.0 MPa or more, even more preferably 15.0 MPa or more, and particularly preferably 19.0 MPa or more. T is preferably 45.0 MPa or less, more preferably 40.0 MPa or less, and even more preferably 38.0 MPa or less.

[0077] The 30°C E* and 70°C E* can be adjusted appropriately by changing the types and amounts of the rubber components, fillers, plasticizers, vulcanizing agents, vulcanization accelerators, etc., which will be described later. For example, increasing the total amount of styrene in the rubber components tends to increase the E* value. In addition, increasing the amount of fillers (especially carbon black) and resin components tends to increase the E* value.

[0078] The total styrene content in the rubber component of the rubber composition constituting the tread portion is preferably 8.0% by mass or more, more preferably 15.0% by mass or more, and even more preferably 30.0% by mass or more. There is no particular upper limit to the total styrene content, but it can be, for example, 60.0% by mass or less, 50.0% by mass or less, etc.

[0079] <Sidewall> In Fig. 1, the sidewall 2 extends substantially radially inward from the end of the tread 1. The radially outer portion of the sidewall 2 is joined to the tread 1. The radially outer end of the sidewall 2 may terminate radially inward of the tread 1 as shown in Fig. 1, or may terminate radially outward of the tread 1 so as to overlap the tread 1.

[0080] The radially inner portion of the sidewall 2 is joined to the clinch portion 10. The radially inner end portion of the sidewall 2 may be exposed on the tire surface side, or may not be exposed on the tire surface so as to be recessed inside the clinch portion 10 in the tire width direction.

[0081] The sidewall 2 may be formed from two or more rubber layers, with one layer being partially or completely hidden from the tire surface. When the sidewall 2 includes two or more rubber layers, it is sufficient that any one of the rubber layers satisfy the physical properties, such as the AE amount and rubber hardness, of the rubber composition constituting the sidewall. The partially hidden layer may be a rubber layer colored other than black for aesthetic reasons. The sidewall 2 may also have periodic irregularities for aesthetic reasons. The irregularities may include decorative features such as letters and patterns, as well as serrations that obscure irregularities caused by the joints of internal components, or minute protrusions that are finer than serrations and are designed to optically increase the blackness. Furthermore, an electronic tag or the like that enables communication with the outside may be embedded inside the sidewall 2.

[0082] From the viewpoint of the effects of the present invention, the acetone extractable amount AE2 of the rubber composition constituting the sidewall is larger than the acetone extractable amount AE3 of the rubber composition constituting the strip apex, specifically, preferably 5.0 mass% or more, more preferably 6.0 mass% or more, even more preferably 7.0 mass% or more, and particularly preferably 8.0 mass% or more. AE2 is smaller than AE1, specifically, preferably 12.0 mass% or less, more preferably 10.0 mass% or less, and even more preferably 9.0 mass% or less.

[0083] The complex modulus of elasticity at 70°C of the rubber composition that makes up the sidewall (70°C E* S ) is preferably 2.0 MPa or more, more preferably 3.0 MPa or more, and even more preferably 4.0 MPa or more. S is preferably 12.0 MPa or less, more preferably 10.0 MPa or less, and even more preferably 8.0 MPa or less.

[0084] <Strip Apex> The tire according to this embodiment includes a strip apex 5 made of a rubber composition on the axially inner side of the sidewall or on the axially inner side of the turnup portion of the carcass.

[0085] In Figure 1, the strip apex 5 is not completely covered by the turnaround portion of the carcass 4, and its upper portion is in contact with the sidewall, but this is not limited to this embodiment, and the strip apex 5 may be completely covered by the carcass 4 as long as it is located axially inside the turnaround portion of the carcass. The strip apex 5 is preferably located axially inside the sidewall, and more preferably has a portion in contact with the sidewall. By configuring the upper portion of the strip apex 5 to be in contact with the sidewall as shown in Figure 1, strain can be transmitted in stages from the rim to the sidewall, which is thought to further improve wet grip performance during cornering.

[0086] From the viewpoint of the effects of the present invention, the acetone extractable amount AE3 of the rubber composition constituting the strip apex is preferably 3.0% by mass or more, more preferably 4.0% by mass or more, and even more preferably 5.0% by mass or more. AE3 is smaller than AE2, specifically, preferably 9.0% by mass or less, more preferably 8.0% by mass or less, and even more preferably 7.0% by mass or less.

[0087] The complex modulus of elasticity at 70°C (70°C E* A ) is preferably 3.0 MPa or more, more preferably 5.0 MPa or more, and even more preferably 8.0 MPa or more. A is preferably 15.0 MPa or less, more preferably 12.0 MPa or less, and even more preferably 10.0 MPa or less. A is 70℃E* S Greater than 70°C E* is preferable. AWhen it is not possible to prepare a measurement sample by cutting it out from the tire, the unvulcanized rubber composition for the strip apex obtained by kneading can be vulcanized to form a test rubber sheet, and a sample can be cut out from the rubber sheet to be used as the measurement sample.

[0088] <Tread pattern> Fig. 2 shows a tread pattern of a tire according to one embodiment of the present invention, but the tread pattern of the tire according to this embodiment is not limited to Fig. 2. In Fig. 2, CL is the tire equator.

[0089] From the viewpoint of improving the contact of the tread portion with the road surface and improving the grip performance during cornering, the land ratio L is 0.60 or more, preferably 0.65 or more, more preferably 0.70 or more, still more preferably 0.80 or more, and particularly preferably 0.84 or more. There is no particular upper limit to the land ratio L, but for passenger car tires, it is usually 0.95 or less, preferably 0.90 or less.

[0090] 30°C* T ×L is preferably less than 30, more preferably less than 25, even more preferably less than 20, and particularly preferably less than 17. T ×L is preferably greater than 4, more preferably greater than 6, and even more preferably greater than 8.

[0091] AE1×L is preferably 14.0 or more, more preferably 16.5 or more, and is preferably 30.0 or less.

[0092] AE2×L is preferably greater than 4.0, more preferably greater than 4.5, and even more preferably greater than 5.0, and is preferably less than 11.0, and more preferably less than 10.0.

[0093] AE3×L is preferably greater than 3.0, more preferably greater than 3.5, even more preferably greater than 4.0, and particularly preferably greater than 4.5. AE3×L is preferably less than 10.0, more preferably less than 8.0, and even more preferably less than 7.0.

[0094] 70°C E* S ×L is preferably greater than 2.5, more preferably greater than 3.5, even more preferably greater than 4.0, and particularly preferably greater than 5.0. S ×L is preferably less than 15.0, more preferably less than 12.0, and even more preferably less than 10.0.

[0095] The product (Hs × L) of the hardness of the rubber composition constituting the tread portion and L is preferably less than 70, more preferably less than 65, even more preferably less than 60, still more preferably less than 55, and particularly preferably less than 49. Hs × L is preferably greater than 10, more preferably greater than 15, and even more preferably greater than 20.

[0096] In Figure 2, the tread portion has an outer tread edge To and an inner tread edge Ti. The outer tread edge To is located on the outer side of the vehicle (on the right side in Figure 2) when mounted on the vehicle. The inner tread edge Ti is located on the inner side of the vehicle (on the left side in Figure 2) when mounted on the vehicle. Each tread edge To, Ti is the outermost contact point in the tire width direction W (left-right direction in Figure 2; hereinafter simply referred to as the width direction W) when a normal load is applied to a tire in a normal state and the tire contacts a flat surface with a camber angle of 0°.

[0097] In FIG. 2, the tread pattern of the tread portion is formed in an asymmetric shape with respect to the tire equator.

[0098] When the land ratio of the contact patch of the outer tread portion o constituting the vehicle outer end side centered on the tire equator CL is Lo and the land ratio of the contact patch of the inner tread portion i constituting the vehicle inner end side is Li, the absolute value of the difference between Lo and Li (Lo-Li) is preferably greater than 0, more preferably greater than 0.05. Also, the absolute value of Lo-Li is preferably less than 0.2.

[0099] In Fig. 1, the tread portion has a plurality of circumferential grooves 15 extending continuously in the circumferential direction C. In Fig. 2, three circumferential grooves 20, 21, 22 are provided. However, the number of circumferential grooves is not particularly limited and may be, for example, two to five. Furthermore, in this embodiment, the circumferential grooves 20, 21, 22 extend linearly along the circumferential direction C, but are not limited to this form and may extend, for example, in a wave-like, sinusoidal, zigzag, or other shape along the circumferential direction C.

[0100] In Fig. 2, circumferential narrow grooves 25 are formed on the land portions 23 of the inner tread portion and the outer tread portion. The circumferential narrow grooves contribute to improving drainage, and therefore contribute to improving the wet grip performance of the tire.

[0101] 2, the tread portion has a plurality of lateral grooves 24 extending in the tire width direction, and further, lateral narrow grooves 26 are formed on the land portions 23 of the inner tread portion and the outer tread portion. Also, in FIG. 2, the tread portion is provided with inclined grooves 27 that extend in a curved manner.

[0102] [Rubber composition] The rubber compositions constituting the tread portion, sidewalls, and strip apex according to the present embodiment (hereinafter referred to as the rubber composition according to the present embodiment) can be produced using the raw materials described below in accordance with the required amount of acetone extraction, etc., as will be described in detail below.

[0103] <Rubber component> The rubber composition according to the present embodiment contains a rubber component. Any rubber component conventionally used in the tire industry can be suitably used as the rubber component. Examples include isoprene-based rubbers, including natural rubber (NR) and polyisoprene rubber (IR), diene-based rubbers, such as styrene-butadiene rubber (SBR), butadiene rubber (BR), styrene-isoprene rubber (SIR), styrene-isoprene butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR), and butyl-based rubbers, such as halogenated butyl rubbers, including butyl rubber (IIR), brominated butyl rubber (Br-IIR), chlorinated butyl rubber (Cl-IIR), and fluorinated butyl rubber (F-IIR). These rubber components may be used alone or in combination of two or more.

[0104] The rubber composition constituting the tread preferably contains SBR, but may contain a rubber component consisting solely of SBR.

[0105] The rubber composition constituting the sidewall preferably contains one or more rubber components selected from the group consisting of isoprene-based rubber, SBR, and BR, more preferably contains either an isoprene-based rubber or BR, and even more preferably contains an isoprene-based rubber and BR. The rubber composition constituting the sidewall may contain a rubber component consisting only of an isoprene-based rubber and BR.

[0106] The rubber composition constituting the strip apex preferably contains an isoprene-based rubber. The rubber composition constituting the strip apex may contain a rubber component consisting of only an isoprene-based rubber.

[0107] (SBR) The SBR is not particularly limited, and examples thereof include solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR). Modified SBRs include SBRs whose ends and / or main chains are modified, and modified SBRs (condensates, those having a branched structure, etc.) coupled with tin, silicon compounds, etc. Furthermore, hydrogenated products of these SBRs (hydrogenated SBRs) can also be used. These SBRs may be used alone or in combination of two or more.

[0108] As the SBR, either oil-extended or non-oil-extended SBR can be used. In this specification, commercially available SBRs from JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Corporation, Asahi Kasei Corporation, ZS Elastomers Co., Ltd., ARLANXEO, etc. can be used.

[0109] From the viewpoint of grip performance during cornering, the styrene content of SBR is preferably more than 20% by mass, more preferably more than 30% by mass, and even more preferably more than 35% by mass. On the other hand, the styrene content of SBR is preferably less than 70% by mass, more preferably less than 60% by mass, and even more preferably less than 50% by mass. If the styrene content of SBR exceeds 70% by mass, styrene groups will be adjacent, the polymer will become too hard, and crosslinking will tend to be non-uniform, which may worsen blowability during high-temperature driving. In addition, temperature dependency will increase, and performance changes with temperature changes will become greater, making it difficult to obtain stable grip performance during driving. In this specification, the styrene content of SBR is measured by the above-mentioned measurement method.

[0110] The vinyl content of SBR is preferably more than 20 mol%, more preferably more than 30 mol%, and even more preferably more than 35 mol%. The vinyl content of SBR is preferably less than 70 mol%, more preferably less than 65 mol%, and even more preferably less than 60 mol%. In this specification, the vinyl content of SBR is measured by the above-mentioned measurement method.

[0111] From the viewpoint of the effects of the present invention, the content of SBR in the rubber component of the rubber composition constituting the tread portion is preferably more than 15% by mass, more preferably more than 20% by mass, even more preferably more than 50% by mass, even more preferably more than 80% by mass, and particularly preferably more than 90% by mass. The content of SBR in the rubber component of the rubber composition constituting the tread portion may be 100% by mass. The content of SBR in the rubber component of the rubber composition constituting the sidewall and strip apex is not particularly limited, and the rubber composition may not contain SBR.

[0112] (Isoprene rubber) Examples of isoprene-based rubbers that can be used include those commonly used in the tire industry, such as isoprene rubber (IR) and natural rubber. Natural rubber includes unmodified natural rubber (NR) as well as modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), highly purified natural rubber, and grafted natural rubber. These isoprene-based rubbers may be used alone or in combination of two or more.

[0113] The NR is not particularly limited, and those commonly used in the tire industry can be used, such as SIR20, RSS#3, and TSR20.

[0114] From the viewpoint of the effects of the present invention, the content of the isoprene-based rubber in the rubber component of the rubber composition constituting the strip apex is preferably more than 50% by mass, more preferably more than 80% by mass, and even more preferably more than 90% by mass. The content of the isoprene-based rubber in the rubber component of the rubber composition constituting the strip apex may be 100% by mass.

[0115] The content of the isoprene-based rubber in the rubber component of the rubber composition constituting the sidewall is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, from the viewpoint of the effects of the present invention. Also, from the viewpoint of compounding other rubber components, 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] The content of isoprene-based rubber in the rubber component of the rubber composition constituting the tread portion is not particularly limited, and the rubber composition may not contain isoprene-based rubber.

[0117] (BR) The BR is not particularly limited, and can be one commonly used in the tire industry, such as BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare earth butadiene rubber (rare earth BR) synthesized using a rare earth catalyst, BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc. These BRs may be used alone or in combination of two or more.

[0118] As the high-cis BR, for example, commercially available products from Zeon Corporation, UBE Corporation, JSR Corporation, etc. can be used. The inclusion of high-cis BR can improve low-temperature properties and wear resistance. The cis content of the high-cis BR is preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably more than 97 mol%. The cis content of BR is measured by the above-mentioned measurement method.

[0119] The rare earth BR is synthesized using a rare earth catalyst and has a vinyl content of preferably less than 1.8 mol%, more preferably less than 1.6 mol%, and even more preferably 1.5 mol% or less, and a cis content of preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably 97 mol% or more. As the rare earth BR, for example, commercially available products from LANXESS K.K. can be used.

[0120] The SPB-containing BR is not simply 1,2-syndiotactic polybutadiene crystals dispersed in the BR, but is dispersed after being chemically bonded to the BR. As such SPB-containing BR, commercially available products from UBE Corporation and the like can be used.

[0121] Examples of modified BR include BR modified with functional groups similar to those described above for SBR, and also preferably used are modified butadiene rubbers (modified BRs) whose terminals and / or main chains are modified with functional groups containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen.

[0122] Other examples of modified BR include tin-modified BR, which is obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and in which the terminals of the modified BR molecule are further bonded with a tin-carbon bond (tin-modified BR).Modified BR may be either non-hydrogenated or hydrogenated.

[0123] The content of BR in the rubber component of the rubber composition constituting the sidewall is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0124] The content of BR in the rubber component of the rubber composition constituting the tread portion and the strip apex is not particularly limited, and BR may not be contained.

[0125] (Other rubber components) The rubber component may contain a rubber component other than the 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, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. These other rubber components may be used alone or in combination of two or more. In addition to the above rubber components, a known thermoplastic elastomer may or may not be contained.

[0126] (Rubber components synthesized from recycled and biomass-derived raw materials) The raw materials (monomers) for synthetic rubbers such as SBR and BR may be derived from underground resources such as petroleum and natural gas, or may be recycled from rubber products such as tires or non-rubber products such as polystyrene. Monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl include, but are not limited to, styrene. Among these, it is preferable to use recycled polyisoprene (recycled isoprene), butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0127] The method for producing the recycled monomer is not particularly limited, and examples thereof include synthesis from recycled naphtha obtained by decomposing rubber products such as tires. The method for producing recycled naphtha is also not particularly limited, and examples thereof include decomposing rubber products such as tires under high temperature and pressure, decomposing with microwaves, or mechanically crushing and then extracting.

[0128] Furthermore, the raw materials (monomers) of synthetic rubbers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to materials derived from natural resources such as plants. Examples of biomass include, but are not limited to, agricultural, forestry, and fishery products, sugar, wood chips, plant residues after useful components have been extracted, plant-derived ethanol, and biomass naphtha.

[0129] Monomers derived from biomass (biomass monomers) are not particularly limited and include biomass-derived butadiene and biomass-derived aromatic vinyl. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyls include, but are not limited to, styrene. The method for producing biomass monomers is not particularly limited and includes, for example, biological and / or chemical and / or physical conversion of animals and plants. A representative example of biological conversion is fermentation by microorganisms, and examples of chemical and / or physical conversion include catalytic conversion, high heat conversion, high pressure conversion, electromagnetic wave conversion, critical fluid conversion, and combinations thereof.

[0130] The polymer synthesized from a biomass monomer component (biomass polymer) is not particularly limited, and examples thereof include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymer synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0131] Whether the raw material for a polymer is derived from biomass can be determined by the pMC (percent modern carbon) measured in accordance with ASTM D6866-10.

[0132] pMC is the modern standard reference 14 of sample against C concentration 14 This is the ratio of C concentrations and is a value used as an index of the biomass ratio of a compound. The significance of this value is explained below.

[0133] 1 mole of carbon atoms (6.02 × 10 23 ) contains approximately 6.02 × 10 atoms, which is about one trillionth of the number of ordinary carbon atoms. 11 pieces 14C exists. 14 The half-life of C is 5730 years, 14 Therefore, in the case of fossil fuels such as coal, oil, and natural gas, which are thought to have been absorbed and fixed by plants and other organisms more than 226,000 years ago, carbon dioxide was included in these when they were first fixed. 14 All C elements have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas contain 14 Therefore, chemicals produced from these fossil fuels do not contain any C element. 14 It does not contain any C elements.

[0134] on the other hand, 14 C is constantly produced by cosmic rays undergoing nuclear reactions in the atmosphere. 14 The amount of C is balanced between radioactive decay and nuclear reaction, and in the Earth's atmospheric environment, 14 Therefore, the amount of carbon derived from biomass resources currently circulating in the environment is constant. 14 As mentioned above, the C concentration is approximately 1 × 10 -12 The value is approximately mol %. Therefore, the biomass ratio in a compound can be calculated by using the difference between these values.

[0135] this 14 C is typically measured using accelerator mass spectrometry based on a tandem accelerator. 13 C concentration ( 13 C / 12 C). 14 C concentration ( 14 C / 12 C) Take measurements. 14 The modern standard reference for the C concentration is the carbon circulating in nature as of 1950. 14The specific standard substance used is the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific activity of carbon in this oxalic acid (per gram of carbon) is 14 The radioactivity of C is separated into carbon isotopes, 13 The standard value is the value corrected for decay from 1950 to the measurement date. 14 This is used as the C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value.

[0136] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, it will show a value of approximately 110 pMC, as it is currently often not 100 under normal conditions. (Currently, it is often not 100 under normal conditions.) On the other hand, for chemical substances derived from petroleum and other fossil fuels, 14 When the carbon concentration is measured, it will show a value of about 0 pMC (for example, 0.3 pMC), which corresponds to the biomass ratio of 0% mentioned above.

[0137] From the above, it is preferable in terms of environmental protection to use a material such as rubber having a high pMC value, that is, a material such as rubber having a high biomass ratio, in a rubber composition.

[0138] [Filler] The rubber composition according to the present embodiment preferably contains silica and / or carbon black as a filler, but the filler may be composed only of carbon black and silica.

[0139] The rubber composition constituting the tread preferably contains silica or carbon black as a filler, and the rubber composition constituting the sidewall and strip apex preferably contains carbon black as a filler.

[0140] <Silica> The silica is not particularly limited, and can be, for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrated silica), or other silica commonly used in the tire industry. The raw material for silica is also not particularly limited, and can be, for example, a mineral-derived raw material such as quartz, a biological raw material such as rice husk (for example, silica made from biomass materials such as rice husk), or silica recycled from silica-containing products. Among these, hydrated silica prepared by a wet method is preferred because it contains a large number of silanol groups. These silicas can be used alone or in combination of two or more types.

[0141] Silica made from biomass materials can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then reacting the silicate with sulfuric acid in the same manner as conventional wet-process silica to produce a silicon dioxide precipitate, which is then filtered, washed with water, dried, and pulverized.

[0142] Silica recycled from silica-containing products can be, for example, silica recovered from products containing silica, such as electronic components such as semiconductors, tires, desiccants, and filtering materials such as diatomaceous earth. The recovery method is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from electronic components such as semiconductors or tires is preferred.

[0143] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and duration, the crystallization of silica in rice husk ash can be suppressed (see, for example, JP 2009-2594 A, Akita Prefectural University Web Journal B / 2019, vol. 6, pp. 216-222). Amorphous silica extracted from rice husks can be commercially available from Wilmar, Inc.

[0144] The nitrogen adsorption specific surface area (N2SA) of silica is 110m from the viewpoint of reinforcement. 2 / g or more is preferable, and 130m 2 / g is more preferable, and 150m 2 / g or more is more preferable, and 170m 2 From the viewpoint of heat buildup and processability, it is particularly preferable that the tensile strength is more than 220m / g. 2 / g is preferable, and 200m 2 / g is more preferable, and 180m 2 / g or less is more preferable. The N2SA of silica is measured by the above-mentioned measurement method.

[0145] From the viewpoint of the effects of the present invention, the average primary particle diameter of silica is preferably more than 10 nm, more preferably more than 12 nm, and even more preferably more than 14 nm. The average primary particle diameter is preferably less than 20 nm, more preferably less than 19 nm, and even more preferably less than 18 nm. The average primary particle diameter of silica is measured by the above-mentioned measurement method.

[0146] When the rubber composition constituting the tread contains silica, the content of silica per 100 parts by mass of the rubber component is preferably more than 90 parts by mass, more preferably 95 parts by mass or more, and even more preferably more than 100 parts by mass. In this case, the content of silica per 100 parts by mass of the rubber component is preferably less than 200 parts by mass, more preferably less than 180 parts by mass, and even more preferably less than 150 parts by mass. However, the rubber composition constituting the tread does not have to contain silica.

[0147] The silica content of the rubber composition constituting the sidewall and strip apex is not particularly limited, and the rubber composition may not contain silica.

[0148] <Silane coupling agent> Silica is preferably used in combination with a silane coupling agent.Silane coupling agent is not particularly limited, but for example, sulfide-based silane coupling agent such as bis(3-triethoxysilylpropyl) disulfide, bis(3-triethoxysilylpropyl) tetrasulfide; mercapto-based silane coupling agent such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agent such as vinyltriethoxysilane, vinyltrimethoxysilane; 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane Examples of suitable silane coupling agents include amino-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferred. Examples of suitable silane coupling agents include those commercially available from Evonik Degussa GmbH and Momentive GmbH. These silane coupling agents may be used alone or in combination.

[0149] The content of the silane coupling agent per 100 parts by mass of the rubber component (the total amount when multiple silane coupling agents are used) is preferably more than 5.0 parts by mass, more preferably more than 8.0 parts by mass, and even more preferably more than 10.0 parts by mass from the viewpoint of improving the dispersibility of silica, and is preferably less than 25 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 15 parts by mass from the viewpoint of preventing a decrease in abrasion resistance.

[0150] <Carbon black> The carbon black is not particularly limited, and those commonly used in the tire industry, such as GPF, FEF, HAF, ISAF, and SAF, can be used. Specifically, N110, N115, N120, N125, N134, N135, N219, N220, N231, N234, N293, N299, N326, N330, N339, N343, and N344 can be used. Suitable carbon blacks include N47, N351, N356, N358, N375, N539, N550, N582, N630, N642, N650, N660, N683, N754, N762, N765, N772, N774, N787, N907, N908, N990, and N991. In addition, proprietary synthetic carbon blacks can also be used. The raw material for carbon black may be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by pyrolysis of waste tires. Furthermore, carbon black can be produced by combustion, such as in a furnace, hydrothermal carbonization (HTC), or thermal decomposition of methane, such as in a thermal black process. 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 Co., Ltd., etc. These may be used alone or in combination of two or more.

[0151] In addition to the above, from the viewpoint of life cycle assessment, carbon black may be made from a biomass material such as lignin, or recycled carbon black obtained by pyrolysis and purification of a product containing carbon black, such as a tire.

[0152] As used herein, "recycled carbon black" refers to carbon black obtained by crushing used tires or other products containing carbon black and calcining the crushed material, and refers to carbon black in which, when subjected to oxidative combustion by heating in air as measured by thermogravimetry in accordance with JIS K 6226-2:2003, the proportion of the mass of ash (ash content), which is the non-combustible component, is 13% by mass or more. In other words, the proportion of the mass (carbon content) of the recycled carbon black lost due to oxidative combustion is 87% by mass or less. Recycled carbon black is sometimes expressed as rCB.

[0153] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975, citing "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, describes the carbon black as being obtained by 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 typically lacks functional groups on its surface, as mentioned in

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

[0154] The recycled carbon black may lack functional groups on its surface, or may have been 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. Furthermore, 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 or disulfide group to obtain surface-activated carbon black. The recycled carbon black according to this embodiment also includes carbon black that has been treated to include functional groups on its surface. Commercially available recycled carbon blacks from Strable Green Carbon, LD Carbon, and other companies can be used.

[0155] In the rubber composition constituting the tread portion, the average primary particle diameter of the carbon black is preferably 30 nm or less, more preferably 25 nm or less, even more preferably 20 nm or less, and particularly preferably 18 nm or less. The average primary particle diameter is preferably greater than 8 nm, more preferably greater than 10 nm, even more preferably greater than 12 nm, and particularly preferably greater than 14 nm. The average primary particle diameter of the carbon black is measured by the above-mentioned measurement method.

[0156] In the rubber composition constituting the sidewall and strip apex, the average primary particle diameter of the carbon black is preferably greater than 50 nm, more preferably greater than 60 nm, even more preferably greater than 70 nm, and particularly preferably greater than 80 nm, and is preferably 120 nm or less, more preferably 110 nm or less, and even more preferably 100 nm or less.

[0157] In the rubber composition that constitutes the tread portion, the nitrogen adsorption specific surface area (N2SA) of the carbon black is set to 50m from the viewpoint of reinforcement and grip performance. 2 / g or more is preferable, and 70m 2 / g or more is more preferable, and 100m 2 / g or more is more preferable, and 120m 2 / g or more is particularly preferable. 2 / g or less is preferable, and 220m 2 / g or less is more preferable. The N2SA of carbon black is measured by the above-mentioned measurement method.

[0158] In the rubber composition that constitutes the sidewall and strip apex, the nitrogen adsorption specific surface area (N2SA) of the carbon black is 20m from the viewpoint of reinforcement and grip performance. 2 / g or more is preferable, and 30m 2 / g or more is more preferable, and 40m 2 / g or more is more preferable. 2 / g or less is preferable, and 60m 2 / g or less is more preferable, and 50m 2 / g or less is more preferable.

[0159] When the rubber composition constituting the tread contains carbon black, the content per 100 parts by mass of the rubber component is preferably more than 5 parts by mass, more preferably more than 60 parts by mass, even more preferably more than 80 parts by mass, still more preferably more than 100 parts by mass, and particularly preferably more than 110 parts by mass. In this case, the content of carbon black per 100 parts by mass of the rubber component is preferably less than 200 parts by mass, more preferably less than 180 parts by mass, and even more preferably less than 150 parts by mass. However, when the rubber composition constituting the tread contains silica as a filler, the content of carbon black per 100 parts by mass of the rubber component is preferably less than 30 parts by mass, more preferably less than 20 parts by mass.

[0160] The amount of carbon black per 100 parts by mass of the rubber component of the rubber composition constituting the sidewall and strip apex is preferably more than 30 parts by mass, more preferably more than 40 parts by mass, and even more preferably more than 50 parts by mass, and is preferably less than 100 parts by mass, more preferably less than 80 parts by mass, and even more preferably less than 75 parts by mass.

[0161] <Other fillers> The filler may contain fillers other than silica and carbon black. The other fillers are not particularly limited, but may include, for example, fillers that have been commonly used in the tire industry, such as aluminum hydroxide, calcium carbonate, alumina, clay, and talc.

[0162] The total amount of filler per 100 parts by mass of the rubber component of the rubber composition constituting the tread portion is preferably more than 80 parts by mass, more preferably more than 90 parts by mass, and even more preferably more than 100 parts by mass.

[0163] In one embodiment of the rubber composition constituting the tread portion, the filler may be made of carbon black alone, and the tread portion of this embodiment is suitably used in, for example, racing tires.

[0164] In one embodiment of the rubber composition constituting the tread portion, the filler may contain more than 100 parts by mass of silica per 100 parts by mass of the rubber component, and the tread portion of this embodiment is suitable for use in, for example, passenger car tires.

[0165] [Other compounding agents] In addition to the rubber component and filler, the rubber composition according to the present embodiment may contain compounding agents that are conventionally commonly used in the tire industry, such as plasticizers, vulcanized rubber particles, processing aids, wax, stearic acid, zinc oxide, antioxidants, crosslinking agents, and vulcanization accelerators, as appropriate.

[0166] <Plasticizer> A plasticizer is a material that imparts plasticity to rubber components and encompasses both plasticizers that are liquid at 25°C and plasticizers that are solid at room temperature (25°C). Examples of plasticizers include resin components, oils, liquid polymers, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, biomass-derived materials, or naphtha recycled from rubber and non-rubber products. Low-molecular-weight hydrocarbon components obtained by pyrolysis and extraction of used tires and other products containing various components may also be used as plasticizers. These plasticizers may be used alone or in combination.

[0167] (resin component) The rubber composition constituting the tread portion and the rubber composition constituting the sidewall preferably contain a resin component among the other compounding ingredients. The resin component is not particularly limited, but resin components commonly used in the tire industry can be used, such as aromatic vinyl resins, dicyclopentadiene resins, C9 resins, C5 resins, C5C9 resins, terpene resins, rosin resins, and phenolic resins. Of these, petroleum resins, aromatic vinyl resins, dicyclopentadiene resins, C9 resins, and terpene resins are preferred. The resin component may be used alone or in combination of two or more.

[0168] <Aromatic vinyl resin> The term "aromatic vinyl resin" refers to a resin containing at least one aromatic vinyl compound selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc., as the monomer component with the largest content, preferably at least 50 mol %, and may be hydrogenated or modified. As the aromatic vinyl resin, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, because they are economical, easy to process, and have excellent heat generation properties. As the aromatic vinyl resin, commercially available products from, for example, Kraton, Eastman Chemical, Mitsui Chemicals, Inc., etc. can be used. The resin component may be used alone or in combination of two or more types.

[0169] <Dicyclopentadiene resin> The term "dicyclopentadiene-based resin" refers to a resin containing dicyclopentadiene (DCPD) as the monomer component with the highest content, and may be a hydrogenated or modified resin. Examples of dicyclopentadiene-based resins include DCPD / C9 resins obtained by copolymerizing dicyclopentadiene with the C9 fraction, with DCPD / C9 resins being preferred. Examples of DCPD resins that can be used include those commercially available from ExxonMobil Corporation, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., and the like.

[0170] <C9 resin> The term "C9 resin" refers to a resin obtained by polymerizing a C9 fraction. It may be a C9 fraction polymerized alone or a copolymer obtained by copolymerizing a C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) with a C9 fraction is called a DCPD / C9 resin. It may also be a hydrogenated or modified version of such a resin. Examples of C9 fractions include at least one petroleum fraction having 8 to 10 carbon atoms selected from the group consisting of vinyltoluene, alkylstyrene, coumarone, indene, methylindene, dicyclopentadiene, etc. Specific examples of C9 resins include coumarone-indene resin, coumarone resin, and indene resin. The resin components may be used alone or in combination.

[0171] <C5 resin> "C5 resin" refers to a resin obtained by polymerizing a C5 fraction other than dicyclopentadiene, and may be a hydrogenated or modified version of such a resin. Examples of C5 fractions other than dicyclopentadiene include at least one petroleum fraction having 4 to 5 carbon atoms selected from the group consisting of cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, pentadiene, etc. The resin component may be used alone or in combination of two or more.

[0172] <C5C9 resin> The term "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified resin. Examples of C5C9 petroleum resins that can be used include those commercially available from Tosoh Corporation, Luhua, and the like. The resin components may be used alone or in combination of two or more.

[0173] <Terpene resin> The term "terpene resin" refers to a resin containing at least one terpene compound selected from the group consisting of α-pinene, β-pinene, limonene, dipentene, etc., as the largest content of the monomer component, and may be hydrogenated or modified. Specific examples of terpene resins include polyterpene resins containing only one or more of the terpene compounds as monomer components; aromatic-modified terpene resins containing the terpene compound and an aromatic compound as monomer components; and terpene phenolic resins containing the terpene compound and a phenolic compound as monomer components. Examples of aromatic compounds that serve as monomer components for aromatic-modified terpene resins include at least one selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. Examples of phenolic compounds that serve as monomer components for terpene phenolic resins include at least one selected from the group consisting of phenol, bisphenol A, cresol, xylenol, etc. These resin components may be used alone or in combination.

[0174] <Rosin-based resin> The rosin-based resin refers to a resin containing at least one rosin acid compound selected from the group consisting of abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc., and may be a hydrogenated or modified version of such a rosin-based resin. Examples of the rosin-based resin include, but are not limited to, natural rosin and rosin-modified resins obtained by modifying rosin through hydrogenation, disproportionation, dimerization, esterification, etc. The resin component may be used alone or in combination of two or more.

[0175] <Phenol-based resin> The phenolic resin refers to a resin containing a phenolic compound such as phenol or cresol as the monomer component with the highest content. Examples of the phenolic resin include, but are not limited to, phenol-formaldehyde resin, alkylphenol-formaldehyde resin, alkylphenol-acetylene resin, and oil-modified phenol-formaldehyde resin. The resin component may be used alone or in combination of two or more.

[0176] ≪Softening point≫ From the viewpoint of grip performance, the softening point of the resin component is preferably 60° C. or higher, more preferably 70° C. or higher, and even more preferably 80° C. or higher. From the viewpoint of processability and improving the dispersibility of the rubber component and the filler, the softening point 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 is measured by the above-mentioned measurement method.

[0177] ≪Content≫ When a resin component is contained, the content per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 8 parts by mass or more from the viewpoint of grip performance, while 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 from the viewpoint of suppressing heat buildup.

[0178] (oil) Examples of oils include mineral oil, vegetable oil, animal oil, etc. From the viewpoint of life cycle assessment, waste oils used in rubber mixers or engines, or refined waste cooking oils used in restaurants may also be used.

[0179] As used herein, examples of vegetable oils include 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 Japan wax. Further examples of vegetable oils include refined oils (such as salad oil) obtained by refining the above-mentioned oils, interesterified oils obtained by interesterifying the above-mentioned oils, hardened oils obtained by hydrogenating the above-mentioned oils, thermally polymerized oils obtained by thermally polymerizing the above-mentioned oils, oxidatively polymerized oils obtained by oxidizing the above-mentioned oils, and waste edible oils recovered from edible oils and the like. Vegetable oils may be liquid or solid at room temperature (25°C). These vegetable oils may be used alone or in combination of two or more.

[0180] As used herein, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oil (mineral oil), naphthenic oil, and aromatic oil. Specific examples of mineral oil include mild extracted solvate (MES), distillate aromatic extract (DAE), treated distillate aromatic extract (TDAE), treated residual aromatic extract (TRAE), and residual aromatic extract (RAE). Furthermore, as an environmental measure, oils with a low content of polycyclic aromatic compounds (PCA) can also be used. Examples of low PCA oils include MES, TDAE, and heavy naphthenic oil.

[0181] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin is ester-bonded to a fatty acid. 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 (trimer or higher). Dimer or higher acylglycerols can be obtained by thermal polymerization, oxidative polymerization, or the like. Furthermore, the acylglycerol may be liquid or solid at room temperature (25°C).

[0182] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, but may be any of the following: 1 For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at room temperature (25°C) for 24 hours, and after removing the rubber composition, the rubber composition is immersed in deuterated chloroform at room temperature. 1 When H-NMR was measured, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm when the signal of tetramethylsilane (TMS) was set at 0.00 ppm. These signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atoms of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0183] The fatty acid is not particularly limited and may be either an unsaturated fatty acid or a saturated fatty acid. 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.

[0184] Among these, it is desirable that the fatty acid contains a fatty acid with few double bonds, i.e., a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As a vegetable oil containing such a fatty acid, for example, vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or vegetable oil modified by ester exchange or the like may be used. Furthermore, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by breeding, genetic modification, or the like.

[0185] As the vegetable oil, for example, commercially available products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., Fuji Kosan Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0186] Examples of animal oils include fish oil, beef tallow, and oleyl alcohol derived from these.

[0187] In the rubber composition constituting the tread portion, when oil is contained, the content per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 40 parts by mass or more, from the viewpoint of the effects of the present invention. Also, from the viewpoint of wear resistance, the content is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 80 parts by mass or less.

[0188] When the rubber composition constituting the sidewall and strip apex contains oil, the amount of oil per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less.

[0189] (liquid rubber) The liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at room temperature (25°C), and examples thereof 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. These liquid rubbers may be used alone or in combination of two or more.

[0190] When the rubber composition constituting the tread portion contains liquid rubber, the content thereof per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. The content of the liquid rubber is not particularly limited, but can be, for example, 30 parts by mass or less, 20 parts by mass or less.

[0191] (ester plasticizer) Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelate (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). One type of ester-based plasticizer may be used alone, or two or more types may be used in combination.

[0192] (vulcanized rubber particles) The 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 standpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. These may be used alone or in combination of two or more types.

[0193] The vulcanized rubber particles are not particularly limited, and may be unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0194] As commercially available vulcanized rubber particles, for example, products from Lehigh Corporation, Muraoka Rubber Industries Co., Ltd., etc. can be used.

[0195] (processing aids) 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. These processing aids may be used alone or in combination of two or more. Examples of processing aids that can be used include those commercially available from Schill + Seilacher, Performance Additives, etc.

[0196] When a processing aid is contained, the content thereof per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of improving processability, and is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of abrasion resistance and breaking strength.

[0197] (wax) The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used. Examples include 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. Waxes that can be used include those commercially available from, for example, Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., Ltd., etc. These waxes may be used alone or in combination of two or more.

[0198] When wax is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of weather resistance of the rubber, and is preferably less than 10 parts by mass, more preferably less than 7.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of preventing whitening of the tire due to bloom.

[0199] (stearic acid) When stearic acid is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of processability, and is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of vulcanization rate.

[0200] (zinc oxide) When zinc oxide is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of processability, and preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of abrasion resistance.

[0201] (anti-aging agent) The antioxidant is not particularly limited, and examples thereof include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants 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'-ditolyl-p-phenylenediamine. p-phenylenediamine antioxidants such as N-isopropyl-N'-phenyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol 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 that can be used include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, etc.

[0202] When an antioxidant is contained, the content per 100 parts by mass of the rubber component is preferably more than 1.0 part by mass, more preferably more than 1.5 parts by mass, and even more preferably more than 1.8 parts by mass from the viewpoint of ozone crack resistance of the rubber, and is preferably less than 4.0 parts by mass, more preferably less than 3.0 parts by mass, and even more preferably less than 2.5 parts by mass from the viewpoint of abrasion resistance and wet grip performance.

[0203] <Crosslinking agent> The rubber composition constituting the tread portion preferably contains an organic cross-linking agent as a cross-linking agent, and preferably contains both the organic cross-linking agent and sulfur.The rubber composition constituting the sidewall and the strip apex preferably contains sulfur as a cross-linking agent.

[0204] (organic crosslinking agent) The organic cross-linking agent is not particularly limited as long as it can form a cross-linked chain other than a polysulfide bond. Examples of the organic cross-linking agent include alkylphenol-sulfur chloride condensation products, 1,6-hexamethylene-sodium dithiosulfate dihydrate, dithiocarbamic acid compounds, and dicumyl peroxide. Among these, dithiocarbamic acid compounds are preferred.

[0205] The dithiocarbamic acid compound is a compound having dithiocarbamic acid, and examples thereof include 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, with 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane being preferred.

[0206] The content of the organic crosslinking agent per 100 parts by mass of the rubber component is preferably more than 1.0 part by mass, more preferably more than 2.0 parts by mass, and even more preferably more than 2.5 parts by mass from the viewpoint of the effects of the present invention, and is preferably less than 8.0 parts by mass, more preferably less than 6.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of preventing deterioration.

[0207] (sulfur) As the sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, etc. can be used.

[0208] When sulfur is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.5 parts by mass, even more preferably more than 2.0 parts by mass, and particularly preferably more than 2.5 parts by mass, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, the content is preferably less than 8.0 parts by mass, more preferably less than 6.0 parts by mass, and even more preferably less than 5.0 parts by mass. When oil-containing sulfur is used as the vulcanizing agent, the content of the vulcanizing agent is the total content of pure sulfur contained in the oil-containing sulfur.

[0209] (Vulcanization accelerator) The vulcanization accelerator is not particularly limited, but examples thereof include sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, guanidine vulcanization accelerators, thiuram vulcanization accelerators, thiourea vulcanization accelerators, dithiocarbamate vulcanization accelerators, aldehyde-amine vulcanization accelerators, aldehyde-ammonia vulcanization accelerators, imidazoline vulcanization accelerators, xanthate vulcanization accelerators, and caprolactam disulfide. These vulcanization accelerators may be used alone or in combination of two or more. Among them, one or more vulcanization accelerators selected from the group consisting of sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, and guanidine vulcanization accelerators are preferred, as they more suitably achieve the desired effects.

[0210] Examples of sulfenamide vulcanization accelerators include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS).

[0211] Examples of thiazole vulcanization accelerators include 2-mercaptobenzothiazole (MBT) or a salt thereof, di-2-benzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, and 2-(2,6-diethyl-4-morpholinothio)benzothiazole.

[0212] Examples of guanidine vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatechol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine.

[0213] Examples of thiuram vulcanization accelerators include tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetramethylthiuram monosulfide (TMTM), dipentamethylene thiuram disulfide, and dipentamethylene thiuram tetrasulfide.

[0214] Examples of the thiourea vulcanization accelerator include thiourea compounds such as thiacarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea and diorthotolylthiourea, N,N'-diphenylthiourea, trimethylthiourea and N,N'-diethylthiourea.

[0215] Examples of dithiocarbamate vulcanization accelerators include piperidinium pentamethylenedithiocarbamate (PPDC), zinc dimethyldithiocarbamate (ZnMDC), zinc diethyldithiocarbamate (ZnEDC), zinc dibutyldithiocarbamate (ZnBDC), zinc dibenzyldithiocarbamate (ZDBzC), zinc N-ethyl-N-phenyldithiocarbamate (ZnEPDC), zinc N-pentamethylenedithiocarbamate (ZnPDC), sodium dibutyldithiocarbamate (NaBDC), copper dimethyldithiocarbamate (CuMDC), iron dimethyldithiocarbamate (FeMDC), and tellurium diethyldithiocarbamate (TeEDC).

[0216] When a vulcanization accelerator is contained, the content (total amount when multiple vulcanization accelerators are used) per 100 parts by mass of the rubber component is preferably more than 1.0 part by mass, more preferably more than 1.5 parts by mass, and even more preferably more than 2.0 parts by mass. The content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably less than 10 parts by mass, more preferably less than 8 parts by mass, and even more preferably less than 6 parts by mass.

[0217] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. As a method for obtaining a blend of the various materials from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0218] [Manufacturing] The rubber composition according to the present embodiment can be produced by a known method, for example, by kneading the above-described components using a rubber kneading device such as an open roll or an internal kneader (such as a Banbury mixer or kneader).

[0219] The kneading process may include, for example, a base kneading process in which compounding ingredients and additives other than the vulcanizing agent and vulcanization accelerator are kneaded, and a final kneading (F kneading) process in which the vulcanizing agent and vulcanization accelerator are added to the kneaded product obtained in the base kneading process and kneaded. Furthermore, the base kneading process may be divided into multiple processes as desired. When the base kneading process is divided, the method may be (1) a method in which some of the compounding ingredients and additives are pre-mixed to form a masterbatch, and then the remaining compounding ingredients and additives are added to the resulting masterbatch and kneaded, or (2) a method in which all of the compounding ingredients and additives to be kneaded in the base kneading process are kneaded at once, and then the kneaded product is remilled one or more times. In the above method (1), the number of masterbatches is not limited and may be two or more. Furthermore, when the number of masterbatches is two or more, all of the compounding ingredients and additives used in the base kneading process may be allocated to one of the masterbatches.

[0220] The kneading conditions are not particularly limited, but examples include a method in which the base kneading step involves kneading for 3 to 10 minutes at a discharge temperature of 150 to 170°C, and a method in which the final kneading step involves kneading for 1 to 5 minutes at 70 to 110°C. The vulcanization conditions are not particularly limited, but examples include a method in which vulcanization is carried out for 10 to 30 minutes at 150 to 200°C.

[0221] The tire of this embodiment, which has a tread portion, sidewalls, and strip apex made from the rubber composition of this embodiment, can be manufactured by a conventional method. That is, the tire can be manufactured by extruding an unvulcanized rubber composition prepared by blending the above-mentioned components with the rubber component as needed to form the shapes of the tread portion, sidewalls, and strip apex, and then laminating and molding the resulting components together with other tire components in a tire building machine by a conventional method to form an unvulcanized tire. The unvulcanized tire thus obtained can then be heated and pressurized in a vulcanizer. The vulcanization conditions are not particularly limited, and examples include vulcanization at 150 to 200°C for 10 to 30 minutes.

[0222] [Application] The tire of this embodiment can be used for any purpose, regardless of whether it is a pneumatic tire or a non-pneumatic tire, and can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a racing tire, a motorcycle tire, a heavy-duty tire, or a run-flat tire. Passenger car tires are tires designed to be mounted on four-wheeled vehicles and have a maximum load capacity of less than 1,400 kg. Heavy-duty tires are tires with a maximum load capacity of 1,400 kg or more. The tire of this embodiment can be used as an all-season tire, a summer tire, or a winter tire such as a studless tire. [Example]

[0223] The following examples (working examples) are considered to be preferable for carrying out the present invention, but the scope of the present invention is not limited to these examples. Tires having tread portions, sidewalls, and strip apexes manufactured using rubber compositions obtained by varying the formulation according to Table 1 using the various chemicals shown below were examined, and the results calculated based on the following evaluation methods are shown in Tables 2 and 3. <Various chemicals> NR:TSR20 SBR: HP755 manufactured by Asahi Kasei Corporation (S-SBR, styrene content: 39.5% by mass, vinyl content: 38.2 mol%, oil content: 37.5 parts by weight per 100 parts by weight of rubber component) BR: UBEPOL BR (registered trademark) 150B (cis content: 97 mol%) manufactured by UBE Corporation Carbon Black 1: Prototype (N2SA: 180m 2 / g, average primary particle diameter: 16nm) Carbon black 2: Show Black N220 (N2SA: 110m) manufactured by Cabot Japan Co., Ltd. 2 / g, average primary particle diameter: 22nm) Carbon black 3: Diablack (registered trademark) E (FEF, N550, N2SA: 40 m) manufactured by Mitsubishi Chemical Corporation 2 / g, average primary particle diameter: 81nm) Silica: Ultrasil VN3 (N2SA: 175 ml) manufactured by Evonik Degussa 2 / g, average primary particle diameter: 17nm) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Oil: H&R VivaTec 500 (TDAE oil) Liquid rubber: L-SBR-820 (liquid SBR) manufactured by Kuraray Co., Ltd. Resin component 1: Nitto Chemical Co., Ltd.'s Knit Resin Kumarone V-120 (cumarone-indene resin, softening point: 120°C) Resin component 2: Petrotack 100V manufactured by Tosoh Corporation (C5C9 resin, copolymer of C5 fraction and C9 fraction, softening point: 96°C) Antioxidant: Antigen 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Wax: Sunnock N manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: Camellia stearic acid beads manufactured by NOF Corporation Zinc oxide: Zinc oxide type 2 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd. Organic crosslinker: VULCUREN® KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by LANXESS Vulcanization accelerator 1: Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccelaer D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0224] Examples and Comparative Examples According to the formulation shown in Table 1, a 1.7 L internal Banbury mixer was used to mix all the chemicals except for the sulfur, organic crosslinking agent, and vulcanization accelerator at a discharge temperature of 160°C for 4 minutes to obtain a kneaded mixture. Next, using an open roll, the sulfur, organic crosslinking agent, and vulcanization accelerator were added to the resulting mixture, and the mixture was mixed for 4 minutes until the temperature reached 105°C to obtain an unvulcanized rubber composition. The resulting unvulcanized rubber composition was molded to fit the shapes of the tread, sidewall, and strip apex, and then bonded together with other tire components to produce unvulcanized tires. These were then vulcanized at 170°C to obtain test tires (size: 205 / 65R15, rim: 15x6JJ, internal pressure: 230 kPa).

[0225] <Measurement of acetone extractables AE> Rubber test specimens were cut out from the tread, sidewall, and strip apex of each test tire and immersed in acetone for 72 hours at room temperature (around 25°C) in accordance with JIS K 6229:2015 to extract the soluble components. The mass of each rubber test specimen was measured before and after extraction, and the amount of acetone extracted was calculated using the following formula. (Amount of acetone extracted (mass%)) = {(mass of rubber test piece before extraction - mass of rubber test piece after extraction) / (mass of rubber test piece before extraction)} × 100

[0226] <30°C E* T Measurement of Each vulcanized rubber test piece is cut out from inside each rubber layer in the tread portion of each test tire, measuring 20 mm in length, 4 mm in width, and 1 mm in thickness, with the long side aligned in the tire circumferential direction and the thickness direction aligned in the tire radial direction.The complex modulus of elasticity E* of each test piece is measured using a dynamic viscoelasticity measuring device (Iplexer series manufactured by GABO) 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 an extension mode.

[0227] <70°C E* S Measurement of Each vulcanized rubber test piece is cut out from the sidewall of each test tire to a length of 20 mm, width of 4 mm, and thickness of 1 mm, so that the tangent to the tire circumferential direction is the long side and the tire width direction (normal direction to the sidewall surface) is the thickness direction.The complex modulus of elasticity E* of each test piece is measured using a dynamic viscoelasticity measuring device (Iplexer series manufactured by GABO) under the conditions of a temperature of 70°C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±1%, and an extension mode.

[0228] <Grip performance when turning> The test tires were fitted to all wheels of a domestically produced FR vehicle (2000cc), and the vehicle was driven 10 laps on a test course with a dry asphalt surface. While driving on a straight line at 100 km / h, the test driver sensorily evaluated the stability of control when braking and entering a corner. The evaluation was performed using an integer value of 1 to 5, with a higher score indicating better control stability during steering. The total score of the 20 test drivers was calculated based on this evaluation standard. Two control tires were used to evaluate cornering grip performance, depending on the formulation of the rubber composition that makes up the tread. The control tires are Comparative Example 1 in Table 2 and Comparative Example 4 in Table 3. The total score of each control tire was converted to a reference value (100), and the evaluation results of each test tire were displayed as an index proportional to the total score. A higher value indicates better cornering grip performance.

[0229] [Table 1]

[0230] [Table 2]

[0231] [Table 3]

[0232] <Embodiment> Examples of embodiments of the present invention are given below. [1] A tire having a tread portion, a sidewall, a carcass, and a strip apex, the strip apex is located on the axially inner side of the sidewall or the axially inner side of the carcass turnup portion, the tread portion, the sidewall, and the strip apex are made of a rubber composition containing a rubber component, When the land ratio of the tire is L, L is 0.60 or more, the rubber composition constituting the tread portion contains an organic crosslinking agent, The acetone extractable amount of the rubber composition constituting the tread portion is AE1 (mass%), The acetone extractable amount of the rubber composition constituting the sidewall is AE2 (mass%), When the acetone extractable amount of the rubber composition constituting the strip apex is AE3 (mass%), AE1>AE2>AE3 That is, tires. [2] The tire according to [1] above, wherein L is 0.70 or more. [3] The tire according to [1] or [2] above, wherein L is 0.80 or more. [4] The tire according to any one of the above [1] to [3], wherein the product (Hs×L) of rubber hardness Hs and L of the rubber composition constituting the tread portion is less than 49. [5] The complex modulus of elasticity at 30 ° C. of the rubber composition constituting the tread portion is 30 ° C. E* T (MPa), 30℃E* Tand L (30°C E* T The tire according to any one of the above [1] to [4], wherein the value of the axial length (L) is less than 20, preferably less than 17. [6] The tire according to any one of the above [1] to [5], wherein the product of AE3 and L (AE3×L) exceeds 3.5. [7] The complex modulus of elasticity at 70 ° C. of the rubber composition constituting the sidewall is 70 ° C. E* S (MPa), 70℃E* S and L (70℃E* S The tire according to any one of the above [1] to [6], wherein the value of the axial length (L) is greater than 5.0. [8] The tire according to any one of the above [1] to [7], wherein the organic crosslinking agent is a dithiocarbamic acid compound. [9] The tire according to any one of the above [1] to [8], wherein the rubber composition constituting the sidewall contains 20% by mass or more of butadiene rubber in the rubber component.

[10] The tire according to any one of the above [1] to [9], wherein the rubber composition constituting the sidewall contains a resin component.

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

[10] , wherein the total amount of styrene in the rubber component of the rubber composition constituting the tread portion is 20% by mass or more.

[12] In the tread portion, the land ratio of the contact surface of the outer tread portion constituting the vehicle outer end side with respect to the tire equator is L0, When the land ratio of the contact surface of the inner tread portion that constitutes the vehicle inner end side is Li, The tire according to any one of the above [1] to

[11] , wherein the absolute value of the difference between Lo and Li (Lo-Li) is greater than 0 and less than 0.2, preferably greater than 0.05 and less than 0.2.

[13] The tire according to any one of the above [1] to

[12] , wherein AE3 is 4.0% by mass or more, preferably 5.0% by mass or more.

[14] The tire according to any one of the above [1] to

[13] , wherein AE1×L is 14.0 or more, preferably 16.5 or more.

[15] The tire according to any one of the above [1] to

[14] , wherein the rubber composition constituting the tread portion contains carbon black having an average primary particle diameter of 30 nm or less, preferably 25 nm or less, and more preferably 20 nm or less, per 100 parts by mass of the rubber component. [Explanation of symbols]

[0233] 1 Tread section 2 Sidewall 3 Bead section 4. Carcass 5 Strip Apex 6 Band Layer 7 Inner liner 8 rims 9 Rim Chafer 10 Clinch Section 13 Bead Apex 14 Bead core 15 Circumferential groove 16 Belt Layer CL Tire Equator Tо Outer tread edge Ti inner tread edge W Tire width direction C Circumferential direction of tire Outer tread area i Inner tread 20 Circumferential groove 21 Circumferential groove 22 Circumferential groove 23 Land 24 Yokomizo 25 Circumferential thin groove 26 Transverse groove 27 Slant groove

Claims

1. A tire having a tread portion, a sidewall, a carcass, and a strip apex, the strip apex is located on the axially inner side of the sidewall or the axially inner side of the carcass turnup portion, the tread portion, the sidewall, and the strip apex are made of a rubber composition containing a rubber component, When the land ratio of the tire is L, L is 0.60 or more, the rubber composition constituting the tread portion contains an organic crosslinking agent, The acetone extractable amount of the rubber composition constituting the tread portion is AE1 (mass%), The acetone extractable amount of the rubber composition constituting the sidewall is AE2 (mass%), When the acetone extractable amount of the rubber composition constituting the strip apex is AE3 (mass%), AE1>AE2>AE3 That is, tires.

2. 2. The tire of claim 1, wherein L is 0.70 or greater.

3. 3. The tire according to claim 1, wherein L is 0.80 or greater.

4. The tire according to claim 1 or 2, wherein the product (Hs×L) of rubber hardness Hs and L of the rubber composition constituting the tread portion is less than 49.

5. The complex modulus of elasticity at 30°C of the rubber composition constituting the tread portion is 30°C E* T (MPa), 30°C E* T and L (30°C E* T 3. The tire according to claim 1, wherein the axial length (L) of the tire is less than 20.

6. The tire according to claim 1 or 2, wherein the product of AE3 and L (AE3 x L) is greater than 3.

5.

7. The complex modulus of elasticity at 70°C of the rubber composition constituting the sidewall is 70°C E* S (MPa), 70°C E* S and L (70°C E* S 3. The tire according to claim 1 or 2, wherein the ratio of the axial length of the tire to the longitudinal length of the tire is 1.

0.

8. The tire according to claim 1 or 2, wherein the organic cross-linking agent is a dithiocarbamic acid compound.

9. The tire according to claim 1 or 2, wherein the rubber composition constituting the sidewall contains 20% by mass or more of butadiene rubber in the rubber component.

10. The tire according to claim 1 or 2, wherein the rubber composition constituting the sidewall contains a resin component.

11. The tire according to claim 1 or 2, wherein the total amount of styrene in the rubber component of the rubber composition constituting the tread portion is 20% by mass or more.

12. In the tread portion, the land ratio of the contact surface of the outer tread portion constituting the vehicle outer end side with respect to the tire equator is L0, When the land ratio of the contact surface of the inner tread portion that constitutes the vehicle inner end side is Li, The tire according to claim 1 or 2, wherein the absolute value of the difference between Lo and Li (Lo-Li) is greater than 0 and less than 0.

2.

13. The tire according to claim 1 or 2, wherein AE3 is 4.0 mass% or more.

14. The tire according to claim 1 or 2, wherein AE1×L is 14.0 or greater.

15. The tire according to claim 1 or 2, wherein the rubber composition constituting the tread portion contains carbon black having an average primary particle diameter of 30 nm or less.

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