tire

Abstract

To provide a tire improved in crack resistance.SOLUTION: A tire comprising a carcass cord and at least one tire member composed of a rubber composition containing a regenerated carbon black, wherein when a fineness (dtex) of the carcass cord is F, a maximum load capacity (kg) of the tire is WL, and an elongation at break (%) of the tire member is EB, F is 6000 or more, and F, WL, and EB satisfy the following formulas (1) and (2): F / WL ≥ 5.6 (1) (F / WL) * EB ≥ 840 (2) SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] With the spread of electric vehicles, there is a demand for improving the load-bearing performance (maximum load capacity) of tires. For example, Patent Document 1 describes a tire using an organic fiber carcass cord. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-138435 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a tire with improved crack resistance. [Means for solving the problem]

[0005] The present invention provides a tire having a carcass cord and at least one tire component made of a rubber composition containing recycled carbon black, The fineness (dtex) of the carcass cord is F, and the maximum load capacity (kg) of the tire is W. L and when the breaking elongation (%) of the tire component is EB, F is 6000 or more, and F, W L and EB satisfy the following formulas (1) and (2): (1) F / W L ≧5.6 (2) (Firmware L )×EB≧840 [Effects of the Invention]

[0006] According to the present invention, a tire with improved crack resistance can be provided. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic view showing a portion of a cross section (upper right portion of the cross section) taken along the tire meridian for a tire according to one embodiment of the present invention. [Figure 2] 1 is a schematic diagram of the outer surface of a sidewall on which a plurality of columnar micro-ridges are formed. [Figure 3] 1 is a schematic diagram of the outer surface of a sidewall on which a plurality of small protuberances in the shape of a truncated square pyramid are formed. [Figure 4] XX cross-sectional view of FIG. 3. [Figure 5] 1 is a schematic diagram of the outer surface of a sidewall having a plurality of rib-like micro-ridges formed thereon. [Figure 6] FIG. 6 is a cross-sectional view of FIG. 5 taken along the line Y-Y. DETAILED DESCRIPTION OF THE INVENTION

[0008] A tire according to one embodiment of the present invention is a tire having a carcass cord and at least one tire component made of a rubber composition containing recycled carbon black, wherein the fineness (dtex) of the carcass cord is F and the maximum load capacity (kg) of the tire is W. L and when the breaking elongation (%) of the tire component is EB, F is 6000 or more, and F, W L and EB satisfies the following formulas (1) and (2). (1) F / W L ≧5.6 (2) (Firmware L )×EB≧840

[0009] While not intending to be bound by theory, the reason why crack resistance can be improved in embodiments of the present invention is thought to be as follows. Increasing the fineness of the carcass cord, i.e., thickening the carcass cord, can improve the maximum load capacity of the tire. However, increasing the fineness reduces the contact area between the topping rubber and the carcass cord. This reduces the restraint of the carcass cord, making the topping rubber more mobile, which is thought to worsen the crack resistance of the entire tire. Recycled carbon black is obtained by pyrolysis of waste tires, etc., and its surface is incinerated. Therefore, when recycled carbon black is incorporated into a rubber composition, the bond between the recycled carbon black and the surrounding rubber polymers is weaker than with other carbon blacks. Therefore, rubber compositions containing recycled carbon black have improved elongation and increased flexibility. Therefore, when this rubber composition is used in tire components, it is thought that even tires using carcass cords with a specified fineness range can flexibly respond to tire deformation during driving, improving crack resistance.

[0010] The right side of formula (1) is preferably 7.0, and more preferably 12.0.

[0011] Tires that satisfy stricter conditions of formula (1) are considered to have even better crack resistance.

[0012] The right side of the formula (2) is preferably 1400, and more preferably 2400.

[0013] Tires that satisfy stricter conditions of formula (2) are considered to have even better crack resistance.

[0014] F and W L and 70° C. tan δ preferably satisfy the following formula (3): (3) (Firmware L )×70℃ tanδ≧0.40

[0015] Tires that satisfy formula (3) generate large amounts of heat from the rubber composition and absorb rubber deformation, which is thought to enable them to flexibly respond to tire deformation during driving and lead to further improvements in crack resistance.

[0016] The at least one tire component made of the rubber composition containing recycled carbon black is preferably at least one tire component selected from the group consisting of a clinch apex, a sidewall, an insulation, and an inner liner.

[0017] It is believed that the application of the rubber composition according to the present invention to the above-mentioned members improves the elongation of the rubber composition and increases its flexibility, thereby achieving the effects of the present invention.

[0018] At least one tire component made of a rubber composition containing the recycled carbon black is a clinch apex, and the rubber composition constituting the clinch apex includes a rubber component containing more than 20% by mass and not more than 100% by mass of an isoprene-based rubber, and when the content of the isoprene-based rubber in the rubber component is less than 100% by mass, it is preferable that the rubber component includes at least one of a butadiene rubber and a styrene-butadiene rubber.

[0019] It is believed that by including isoprene-based rubber in the above proportions, the tensile strength of the rubber is improved, making it more resistant to impacts from the road surface, and therefore improving crack resistance.

[0020] It is preferable that at least one tire component made of the rubber composition containing the recycled carbon black is a sidewall, and that the rubber composition constituting the sidewall contains more than 20% by mass but less than 80% by mass of isoprene-based rubber and at least one of butadiene rubber and styrene-butadiene rubber.

[0021] It is believed that by including isoprene-based rubber in the above proportions, the tensile strength of the rubber is improved, making it more resistant to impacts from the road surface, and therefore improving crack resistance.

[0022] At least one tire component made of a rubber composition containing the recycled carbon black is insulation, and the rubber composition constituting the insulation includes a rubber component containing more than 20% by mass and not more than 100% by mass of isoprene-based rubber, and the content of the isoprene-based rubber in the rubber component is less than 100% by mass, it is preferable that the rubber component includes at least one of butadiene rubber and styrene-butadiene rubber.

[0023] It is believed that by including isoprene-based rubber in the aforementioned proportion, the tensile strength of the rubber is improved, making it more resistant to impacts from the road surface and improving crack resistance.

[0024] At least one tire component made of a rubber composition containing the recycled carbon black is an inner liner, and the rubber composition constituting the inner liner contains a rubber component containing more than 70% by mass and not more than 100% by mass of a butyl-based rubber, and when the content of the butyl-based rubber in the rubber component is less than 100% by mass, it is preferable that the rubber component contains an isoprene-based rubber.

[0025] Butyl rubber has excellent air permeation resistance, and is therefore thought to lead to further improvement in air permeation resistance in addition to the effects of the present invention.

[0026] The rubber composition constituting the sidewall preferably contains silica.

[0027] The incorporation of silica is believed to improve the elongation at break (EB) and also reinforce the rubber composition, thereby improving crack resistance.

[0028] The rubber composition contains carbon black, the carbon black contains recycled carbon black, and the content of the carbon black relative to 100 parts by mass of the rubber component is A CB The content of the recycled carbon black is A rCB When A CB and A rCBIt is preferable that the relationship of the following formula (4) is satisfied. (4) A rCB / A CB <0.85

[0029] It is believed that by making the content of recycled carbon black less than a predetermined ratio relative to the total carbon black content, appropriate rubber reinforcement properties can be obtained, and crack resistance performance can be improved.

[0030] The content of recycled carbon black in the rubber composition constituting the sidewall is SW rCB and the content of silica in the rubber composition constituting the sidewall is SW SIL When SW rCB and SW SIL It is preferable that and satisfy the following formula (5). (5) SW SIL / SW rCB <0.70

[0031] By reducing the ratio of the silica content to the recycled carbon black content below a predetermined value so as to satisfy the relationship in equation (5), it is possible to obtain the effect of improving the breaking elongation due to the silica, while also making it easier to obtain the effect of dispersing force due to the recycled carbon black, thereby reinforcing the rubber composition and improving its crack resistance.

[0032] The sidewall preferably has a micro-ridge formation portion in which a plurality of micro-ridges are formed on the outer surface.

[0033] The presence of the micro-ridge formation portion is believed to contribute to improving crack resistance because it can suppress stress concentration on the outer surface of the sidewall.

[0034] The shape of the micro-protrusions is preferably columnar, frustum or rib-like.

[0035] By making the micro-ridges have these predetermined shapes, stress concentration on the outer surface of the sidewall can be suppressed, which is thought to contribute to improved crack resistance.

[0036] The micro-ridges have a height of 0.03 mm or more and 0.50 mm or less, and are formed in at least one direction at intervals of 0.50 mm or less, with 20 or more micro-ridges formed, and the micro-ridge-forming portion is 10 mm 2 It is preferable that the area is equal to or larger than this.

[0037] By keeping the size of the micro-protrusions within these predetermined ranges, stress concentration on the outer surface of the sidewall can be suppressed, which is thought to contribute to improved crack resistance.

[0038] The maximum width of the minute protuberances is preferably 0.03 mm or more and 0.50 mm or less.

[0039] By keeping the maximum width of the micro-ridges within a predetermined range, stress concentration on the outer surface of the sidewall can be suppressed, which is thought to contribute to improved crack resistance.

[0040] It is preferable that the height of the minute protuberances gradually increase from the maximum tire width position toward the outer side in the tire radial direction, and also gradually increase from the maximum tire width position toward the inner side in the tire radial direction.

[0041] Relatively large distortion occurs near the tire's widest point on the sidewall, but by making the height of the micro-bumps lower on the side closer to the tire's widest point, it is thought that this reduces the unevenness in rubber volume around the tire at points where large distortion occurs, avoids stress concentration near the micro-bumps, and contributes to improved crack resistance.

[0042] <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.

[0043] Unless otherwise specified, the "dimensions of each part of the tire" are values ​​that are specified when the tire appears on its outer surface 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 within the rim width of a normal rim.

[0044] "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, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organization), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." 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 a tire not specified in the above standards, it refers to the narrowest rim among the smallest diameter rims that can be mounted on the tire and can maintain internal pressure (i.e., no air leaks from between the rim and tire).

[0045] "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 is "maximum air pressure," for ETRTO, it is "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 that standard if there is an applicable size at the time of reference. In the case of tires not specified in the above standards, 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, and if there are multiple normal internal pressures of 250kPa or more listed, it refers to the smallest value among them.

[0046] "Normal load (kg)" is the load specified for each tire in the standard system including the standard on which the tire is based, for example, "Maximum Load Capacity" for JATMA, "Load Capacity" for ETRTO, and the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA. 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.

[0047] "Maximum load capacity W L (kg)" 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.

[0048]

number

[0049] "Tire outer diameter Dt" refers to the outer diameter of the tire in its normal state.

[0050] "Tire section width Wt" refers to the maximum width between the outer surfaces of the sidewalls in the normal state (excluding any patterns or letters on the side of the tire).

[0051] "Tire cross-sectional height Ht" refers to the radial height of the tire in a cross section of the tire taken along a plane including the tire rotation axis, and corresponds to half the difference between the tire's outer diameter Dt and the rim diameter R, where R is the tire rim diameter. In other words, the cross-sectional height Ht can be calculated by (Dt-R) / 2.

[0052] "Weight of tire" refers to the weight of the tire itself, excluding the weight of the rim. On the other hand, if the tire has components such as sponge or sealant, or sensor components, the weight includes these components.

[0053] "Fineness" (tex) refers to the weight (g) per 1000 m of organic fiber cord. dtex is a unit representing one-tenth of a tex, and corresponds to the weight (g) per 10 km of organic fiber cord. The fineness of the carcass cord is measured in accordance with JIS L1017. In this specification, when the carcass cord is made of two or more twisted single yarns, the fineness F of the carcass cord refers to the total fineness of the individual twisted single yarns.

[0054] The term "micro-bump" refers to a convex protrusion formed on the outer surface of the sidewall, with a height of 0.03 mm to 0.50 mm. The maximum width of the micro-bump is preferably 0.03 mm to 0.50 mm.

[0055] The "micro-ridge formation portion" refers to the portion on the outer surface of the sidewall where the micro-ridges are formed.

[0056] "Recycled carbon black" refers to carbon black obtained from the pyrolysis process of used tires and other products containing carbon black, and refers to carbon black in which, when heated and burned in air by oxidative combustion using a thermogravimetric method in accordance with JIS K 6226-2:2003, the proportion of ash (the mass of the non-burnable component) is 13% by mass or more. In other words, the mass of the weight loss due to oxidative combustion (carbon content) is 87% by mass or less. Recycled carbon black is also called recycled carbon or recycled carbon black, and is sometimes represented by rCB. In this specification, carbon black that is not recycled carbon black is sometimes referred to as regular carbon black to distinguish between the two.

[0057] The "breaking elongation EB of a rubber composition" is the breaking elongation (%) when a 1 mm thick No. 7 dumbbell-shaped test piece is prepared and a tensile test is performed in accordance with JIS K 6251:2017 at a 23°C atmosphere and a tensile speed of 3.3 mm / s. When a measurement sample is prepared from a test tire, the longitudinal and thickness directions are the same as those of the sample used to measure tan δ and E* of the rubber composition. If it is difficult to obtain a sample with a thickness of 1 mm, the sample is obtained as close to 1 mm as possible. This is because the 100% modulus, breaking strength, and breaking elongation are all measured as standardized values, and are therefore not considered to be affected by thickness.

[0058] The "loss tangent of a rubber composition" refers to the loss tangent (tanδ) 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 vulcanized rubber composition measuring 20 mm in length, 4 mm in width, and 1 mm in thickness. The sample used for dynamic viscoelasticity measurement is a vulcanized rubber composition measuring 20 mm in length, 4 mm in width, and 1 mm in thickness. When preparing a sample by cutting it out from a tire, if the component from which the sample is prepared is a tread, belt reinforcing layer, belt layer, insulation, 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 a sidewall, clinch apex, bead apex, or side reinforcing layer, 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 to the length, and the measured tan δ is normalized by the width and thickness of the sample, so it is considered that there is no effect from the size of the sample. In this specification, 70°C tan δ, which is the loss tangent at 70°C, is measured.

[0059] <Measurement method> "70°C tan δ" is the loss tangent (tan δ) 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.

[0060] "Styrene content" is measured by pyrolysis gas chromatography and NMR measurement ( 1 H-NMR and 13 The amount of components such as "styrene content" is calculated by C-NMR. Unlike physical property values ​​such as complex modulus (E*), the amount of components such as "styrene content" has a true value that is independent of the measurement method, so it is preferable to use a measurement method with as high accuracy as possible. In this specification, "pyrolysis gas chromatography" refers to a method in which a sample is heated in a pyrolysis device, the individual components contained in the gas phase components generated by this heating are separated using a separation column, and each isolated component is analyzed.

[0061] "Vinyl bond amount (1,2-bonded butadiene unit amount)" can be measured by pyrolysis gas chromatography or NMR measurement ( 1 H-NMR and 13 It is calculated using C-NMR. As with the "styrene content," there is a true value for the "vinyl content" that is independent of the measurement method, so it is preferable to use a measurement method with as high accuracy as possible.

[0062] "Cis content (cis-1,4-bonded butadiene unit amount)" is measured by infrared absorption spectroscopy or NMR measurement ( 1 H-NMR and 13 This is a value measured by C-NMR and is applied to rubber components that have repeating units derived from butadiene, such as BR. As with the "styrene content," the "cis content" also has a true value that is independent of the measurement method, so it is preferable to use a measurement method with as high accuracy as possible.

[0063] The "ash content of recycled carbon black" is measured by the thermogravimetric method of JIS K 6226-2:2003.

[0064] The "average primary particle size of carbon black" and "average primary particle size of recycled carbon black" are values ​​obtained by photographing particles with a transmission or scanning electron microscope and arithmetically averaging the particle sizes of 400 particles. If the particle shape is spherical, the particle size is the diameter of the sphere; if the particle shape is non-spherical, the particle size is calculated from the microscope image as the circle-equivalent diameter (positive square root of {4 × (particle area) / π}).

[0065] "N2SA of carbon black" is a value determined by JIS K 6217-2:2017.

[0066] "N2SA of silica" is a value measured by the BET method in accordance with ASTM D3037-93.

[0067] In this specification, the configuration of the carcass cord (cord structure) is expressed in accordance with "5.2 Method of expressing cord structure" of JIS L1017. For example, if the carcass cord is formed by twisting together two single yarns each having a fineness of 1400 dtex, the cord structure of this cord is expressed as 1400 dtex / 2. In this case, the fineness F (dtex) of this carcass cord is 2800 dtex, which is the sum of the finenesses (1400 dtex) of the single yarns.

[0068] <Tires> A tire according to one embodiment of the present invention will be described below with reference to the drawings as needed. However, the drawings are merely examples for the purpose of explanation.

[0069] Fig. 1 is a schematic diagram showing a portion of a cross section (upper right portion of the cross section) taken along the tire meridian of a tire according to one embodiment of the present invention. In Fig. 1, the tire 1 includes a pair of sidewalls 3 arranged on both sides of the tire, a clinch apex 2 arranged at the inner end of each sidewall 3 in the tire radial direction, and a carcass 6 arranged on the inner side of each sidewall 3 in the tire rotational axis direction. An inner liner 5 forms the inner surface of the tire 1 and maintains the internal pressure of the tire 1. An insulation 4 is adjacent to the inner liner 5 on the outer side in the tire rotational axis direction, and the inner liner 5 is joined to the carcass 6 via the insulation 4.

[0070] In an embodiment of the present invention, the carcass includes at least one carcass ply, and the carcass ply is composed of carcass cords and topping rubber covering the carcass cords. The carcass cords can be organic fiber cords that are commonly used as reinforcing materials in the tire industry. The carcass cords may be a single cord or may be formed by twisting multiple cords. The carcass cord testing method complies with JIS L1017.

[0071] Examples of organic fibers used in the organic fiber cord include polyester fibers such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); nylon fibers; rayon fibers; vinylon fibers; aramid fibers; and polyurethane fibers. One or more types of organic fiber cords can be used. In this case, a hybrid cord can also be used in which multiple types of organic fiber cords are twisted together.

[0072] In an embodiment of the present invention, the fineness F (dtex) of the carcass cord is not less than 6000. F is preferably not less than 6600, more preferably not less than 7000, even more preferably not less than 7400, and even more preferably not less than 7600. In addition, in this embodiment, the end count of the carcass cord in the carcass can be set appropriately depending on the type of carcass cord, etc., and can be, for example, 20 to 100 cords / 50 mm.

[0073] In an embodiment of the present invention, it is preferable that at least one rubber selected from the group consisting of the clinch apex rubber, the sidewall rubber, the insulation rubber, and the inner liner rubber contains recycled carbon black.

[0074] In a preferred embodiment, the at least one rubber containing recycled carbon black is a clinch apex rubber. In another preferred embodiment, the at least one rubber containing recycled carbon black is a sidewall rubber. In yet another preferred embodiment, the at least one rubber containing recycled carbon black is an insulation rubber. In yet another preferred embodiment, the at least one rubber containing recycled carbon black is an innerliner rubber.

[0075] In a preferred embodiment, the rubber containing recycled carbon black is at least two rubbers selected from the group consisting of a clinch apex rubber, a sidewall rubber, an insulation rubber, and an inner liner rubber, or at least three rubbers selected from the group, or all of the clinch apex rubber, the sidewall rubber, the insulation rubber, and the inner liner rubber.

[0076] The tire according to the embodiment of the present invention has a carcass cord, and the fineness (dtex) of the carcass cord is F, and the maximum load capacity (kg) of the tire is W. L When EB is the breaking elongation (%) of a tire component made of a rubber composition containing recycled carbon black, F is 6000 or more, and further, F, W L , EB simultaneously satisfy the predetermined relationships shown in equations (1) and (2).

[0077] (Regarding formula (1)) Equation (1) is W L The ratio of F (dtex) to (kg) (F / W L) is 5.6 or more. The right side of formula (1) is preferably 6.0, more preferably 7.0, even more preferably 8.0, even more preferably 10.0, even more preferably 12.0, and even more preferably 14.0.

[0078] In an embodiment of the present invention, as described above, F (dtex) is 6000 or more. F is preferably 6600 or more, more preferably 7000 or more, even more preferably 7400 or more, and even more preferably 7600 or more. On the other hand, if F exceeds 14000, the contact area with the rubber decreases, which may result in a decrease in binding force and a deterioration in crack resistance. F can be adjusted by the type and material of the carcass cord used, etc.

[0079] Maximum load capacity W L (kg) is, for example, preferably 450 or more, 500 or more, and more preferably more than 535. L (kg) can be, for example, 1500 or less, preferably 1400 or less. L is a value determined according to the tire section width Wt (mm), tire section height Ht (mm), and tire outer diameter Dt (mm). It can be increased by increasing the virtual volume V of the space occupied by the tire, or conversely, it can be decreased.

[0080] F / W L The value of W L can be reduced by decreasing the value of F relative to the value of W L can be increased by increasing the value of F relative to the value of

[0081] (Regarding formula (2)) Equation (2) is W L The ratio of F (dtex) to (kg) (F / W L) and the breaking elongation EB (%) of the tire component is 840 or more. The right-hand side of formula (2) is preferably 1400, more preferably 2400, even more preferably 2800, even more preferably 4000, even more preferably 5000, and even more preferably 8000. On the other hand, there is no particular upper limit to the value of the left-hand side of formula (2), but it may usually be about 20,000, or about 16,000, or about 10,000.

[0082] F / W L The value of can be adjusted as described above. EB can be adjusted by changing the type and amount of rubber contained in the rubber component, or the type and amount of filler. For example, it tends to increase by increasing the amount of softener or decreasing the amount of filler. This allows the value of formula (2) to be adjusted.

[0083] (Regarding equation (3)) Formula (3) is expressed as follows: When the loss tangent of the rubber composition at 70°C is 70°C tanδ, F, W L and 70°C tan δ must satisfy the following relationship: (3) (Firmware L )×70℃ tanδ≧0.40

[0084] The right side of formula (3) is preferably 1.0, more preferably 1.2, even more preferably 1.4, even more preferably 2.0, even more preferably 2.2, and even more preferably 2.8.

[0085] F / W L The value of can be adjusted as described above. The 70°C tan δ can be adjusted by changing the type and amount of rubber contained in the rubber component, or the type and amount of filler. For example, tan δ tends to decrease by using a softener that is highly compatible with the rubber component, reducing the amount of softener, increasing the amount of sulfur, increasing the amount of vulcanization accelerator, or increasing the amount of silane coupling agent. This allows the value of equation (3) to be adjusted.

[0086] (Regarding equation (4)) Formula (4) expresses the content (parts by mass) of carbon black relative to 100 parts by mass of the rubber component in the rubber composition as A CB The content of recycled carbon black (parts by mass) is A rCB When A CB A against rCB The ratio (A rCB / A CB The right side of formula (4) is preferably 0.80, more preferably 0.70, and even more preferably 0.60.

[0087] The value of formula (4) can be adjusted by changing the carbon black content and the recycled carbon black content in the rubber composition constituting each member.

[0088] (Regarding equation (5)) The rubber composition constituting the sidewall contains recycled carbon black and silica, and the content of recycled carbon black per 100 parts by mass of the rubber component is SW rCB The content of silica per 100 parts by mass of the rubber component is SW SIL When SW rCB SW SIL The ratio (SW SIL / SW rCB ) is less than 0.70.

[0089] When the sidewall portion is made of a rubber composition containing recycled carbon black, the relationship between the recycled carbon black content and the silica content in the sidewall rubber composition is defined by the following formula (5): The right-hand side of formula (5) is preferably 0.65, more preferably 0.60, and even more preferably 0.50.

[0090] (Minor ridge formation part) The tire of the present invention preferably has a micro-ridge-forming portion in which a plurality of micro-ridges are formed on the outer surface of at least one of the pair of sidewalls.

[0091] In the microridge formation portion, the microridges may be arranged in a single row in the tire radial direction or in multiple rows. Here, "single row in the tire radial direction" means that there are no more than two microridges lined up in the tire radial direction. Also, the microridges may be arranged in a single row in the tire circumferential direction or in multiple rows. Here, "single row in the tire circumferential direction" means that there are no more than two microridges lined up in the tire circumferential direction. It is preferable that the microridges be provided in multiple rows in the tire radial direction and multiple rows in the tire circumferential direction.

[0092] The area of ​​the micro-ridge formation is the area defined by the line surrounding the outermost part of the multiple micro-ridges arranged at intervals of 0.50 mm or less when viewed from a direction perpendicular to the tire surface. The area of ​​the micro-ridge formation is 10 mm 2 It is preferable that the above ratio is satisfied. This is because it can suppress stress concentration on the outer surface of the sidewall and contribute to improving the crack resistance of the sidewall. Furthermore, in the microridge formation portion, the group of microridges may be continuous or may be divided. Here, divided means that the spacing between the microridges is greater than 1.0 mm. Therefore, it is sufficient for there to be at least one microridge formation portion on the outer surface of at least one of the pair of sidewalls, and there may be multiple microridge formation portions.

[0093] (minor elevation) The shape of the micro-ridges is not particularly limited as long as it suppresses stress concentration on the outer surface of the sidewall and contributes to improving the crack resistance of the sidewall, and specific examples include a columnar shape, a frustum shape, a rib shape (stripe shape), etc. Examples of columnar shapes include cylindrical shapes and polygonal prism shapes such as triangular prisms, square prisms, and pentagonal prisms. Examples of frustum shapes include circular frustum shapes and polygonal frustum shapes such as triangular frustum shapes, square frustum shapes, and pentagonal frustum shapes. Examples of rib shapes include the shape of a cross section perpendicular to the longitudinal direction of the rib-shaped micro-ridges, and any shape may be included. Examples of the cross-sectional shape include a rectangle or a trapezoid.

[0094] FIG. 2 shows a portion of a microridge-formed portion where cylindrical microridges 12 are formed on the sidewall outer surface 11. FIG. 3 shows a portion of a microridge-formed portion where square-pyramid-shaped microridges 13 are formed on the sidewall outer surface 11. FIG. 4 is a cross-sectional view taken along line XX of FIG. 3, showing the microridges as viewed from a direction perpendicular to a plane including a normal to the sidewall outer surface. FIG. 4 shows the height h of the microridges 13, the maximum width w of the microridges 13, and the spacing d between the microridges 13. FIG. 5 shows a portion of a microridge-formed portion where rib-shaped microridges 14 are formed on the sidewall outer surface 11. FIG. 6 is a cross-sectional view taken along line YY of FIG. 5, showing the microridges as viewed from a direction perpendicular to a plane including a normal to the sidewall outer surface. FIG. 6 shows the height h of the microridges 14, the maximum width w of the microridges 14, and the spacing d between the microridges 14.

[0095] Here, with respect to the microbumps, "height" refers to the maximum height of the microbump measured along a normal line erected on the outer surface of the sidewall, "maximum width" refers to the maximum width of the microbumps on the outer surface of the sidewall measured in one direction in which the microbumps are arranged, and "spacing" refers to the minimum spacing between the microbumps on the outer surface of the sidewall measured in one direction in which the microbumps are arranged. Note that the height, maximum width, and spacing of the microbumps are all measured with the outer surface of the sidewall laid out on a plane.

[0096] The height of the microbumps at the tire's widest point is preferably 0.03 mm or more, and may be 0.05 mm or more, or 0.10 mm or more, while the height is preferably 0.50 mm or less, and may be 0.45 mm or less, or may be 0.40 mm or less. The maximum width of the microbumps is preferably 0.03 mm or more, and may be 0.05 mm or more, or 0.10 mm or more, while the maximum width is preferably 0.50 mm or less, and may be 0.45 mm or less, or may be 0.40 mm or less. Furthermore, the spacing between the microbumps is preferably 1.00 mm or less, and may be 0.70 mm or less, or may be 0.50 mm or less. The spacing between the microbumps may be at least about half the maximum width, or may be about the same as the maximum width. The density of the microbumps (units / cm 2 ) can be roughly calculated from the maximum width and spacing of the micro-protuberances. For example, in the example described below, it is about 700 / cm 2 is.

[0097] It is preferable that 20 or more micro-ridges are formed in at least one direction, because this can suppress stress concentration on the outer surface of the sidewall and contribute to improving the crack resistance of the sidewall.

[0098] The height of the micro-ridges preferably increases gradually from the tire's maximum width position toward the tire's radially outer side and from the tire's maximum width position toward the tire's radially inner side. This is because, although relatively large strain occurs near the tire's maximum width position on the sidewall, decreasing the height of the micro-ridges closer to the tire's maximum width position is thought to reduce non-uniformity in rubber volume in the tire circumferential direction at positions where large strain occurs, avoid stress concentration near the micro-ridges, and contribute to improving the sidewall's crack resistance.

[0099] The micro-ridges preferably have arc-shaped depressions on their outermost surfaces, such as micro-ridge 14 shown in Fig. 5. This is because such a configuration can prevent air from accumulating in the arc-shaped depressions, thereby preventing the micro-ridges from having poor appearance.

[0100] <Rubber composition> The rubber composition used in the tire components constituting the tire according to the present invention will be described. In an embodiment of the present invention, in at least one of the tire components, the rubber composition constituting that component contains recycled carbon black. In a preferred embodiment, tire components made of a rubber composition containing recycled carbon black include a clinch apex, a sidewall, an insulation, and an inner liner. Below, we will explain the case where each rubber composition constituting each of the components, the clinch apex, the sidewall, the insulation, and the inner liner, contains recycled carbon black. In the following explanation, by replacing recycled carbon black with regular carbon black, a rubber composition for each component not containing recycled carbon black can be obtained.

[0101] [Rubber composition for clinch apex] Each component of the rubber composition for the clinch apex will be described.

[0102] <Rubber component> The rubber composition constituting the clinch apex includes a rubber component containing more than 20% by mass and not more than 100% by mass of an isoprene-based rubber. When the content of the isoprene-based rubber in the rubber component is less than 100% by mass, the tire preferably includes at least one of a butadiene rubber and a styrene-butadiene rubber. The rubber component preferably includes an isoprene-based rubber (IR rubber) and a butadiene rubber (BR). In this case, the rubber component may include rubber components other than the IR rubber and the BR. The rubber component may also consist solely of the IR rubber and the BR. The following describes each rubber that can constitute the rubber component.

[0103] (Isoprene rubber) Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of NR include SIR20, RSS#3, TSR20, and SVR-L, which are commonly used in the rubber industry. Examples of IR include IR2200 and other commonly used rubber products. Examples of modified NR include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. Isoprene-based rubbers may be used alone or in combination of two or more.

[0104] The content of the IR rubber in 100% by mass of the rubber component is, for example, more than 10% by mass, preferably more than 20% by mass, more preferably more than 40% by mass, and even more preferably 50% by mass or more. On the other hand, the content is, for example, 100% by mass or less, preferably less than 90% by mass, and more preferably less than 80% by mass. By keeping the content within the above range, the tensile strength of the rubber is improved, and it becomes more resistant to impacts from the road surface, which tends to improve crack resistance.

[0105] (BR) The BR is not particularly limited, and examples include those commonly used in the tire industry, such as BR with a high cis content, BR containing 1,2-syndiotactic polybutadiene crystals (SPB-containing BR), butadiene rubber synthesized using a rare earth catalyst (rare earth BR), tin-modified butadiene rubber modified with a tin compound (tin-modified BR), and other modified butadiene rubbers (modified BR). The modified BR may be any BR having a functional group that interacts with fillers such as silica. Examples include terminal-modified BR (terminal-modified BR having the functional group at the terminal) in which at least one terminal of the BR has been modified with a compound (modifier) ​​having the functional group, main-chain-modified BR having the functional group at the main chain, main-chain terminal-modified BR having the functional group at the main chain and at least one terminal (for example, main-chain terminal-modified BR having the functional group at the main chain and modified with the modifier), and terminal-modified BR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having hydroxyl or epoxy groups introduced therein. Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imido group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, and an epoxy group. These functional groups may have a substituent. Among these, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferred.

[0106] The cis amount (cis content) of BR is preferably more than 90 mol%, more preferably more than 93 mol%, even more preferably more than 95 mol%, and even more preferably 97 mol% or more. The cis amount of BR can be measured by infrared absorption spectroscopy.

[0107] As the BR, for example, products available from UBE Corporation, JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. may be used. One type of BR may be used alone, or two or more types may be used in combination.

[0108] The BR content in 100% by mass of the rubber component is, for example, more than 10% by mass, preferably more than 20% by mass, and more preferably more than 30% by mass. On the other hand, the content is, for example, less than 90% by mass, preferably less than 80% by mass, more preferably less than 70% by mass, and even more preferably less than 60% by mass. By keeping the BR content within the above range, the low-temperature strength of the rubber is improved, making it more resistant to impacts from the road surface even at low temperatures, which tends to improve crack resistance.

[0109] The total content of the IR rubber and BR in 100% by mass of the rubber component is preferably more than 80% by mass, more preferably more than 90% by mass, and even more preferably more than 95% by mass, and may be 100% by mass.

[0110] (SBR) Styrene-butadiene rubber (SBR) is not particularly limited and includes, for example, unmodified emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR), as well as modified SBRs such as modified emulsion-polymerized styrene-butadiene rubber (modified E-SBR) and modified solution-polymerized styrene-butadiene rubber (modified S-SBR). Modified SBRs include SBRs whose terminals and / or main chains are modified, and modified SBRs (condensates, branched structures, etc.) coupled with tin or silicon compounds. SBRs include oil-extended types in which flexibility is adjusted by adding an extender oil, and non-oil-extended types in which no extender oil is added, and either type can be used. Examples of such SBRs include those manufactured by JSR Corporation, Asahi Kasei Chemicals Corporation, Nippon Zeon Corporation, and ZS Elastomers Co., Ltd. SBRs can be used alone or in combination of two or more types.

[0111] The styrene content of SBR is preferably more than 15% by mass, more preferably more than 20% by mass, and even more preferably more than 23% by mass. From the viewpoint of fuel economy, the styrene content is preferably less than 40% by mass, more preferably less than 30% by mass, and even more preferably less than 25% by mass. The styrene content of SBR is 1 This is a value calculated by H-NMR measurement.

[0112] The vinyl content (amount of 1,2-bonded butadiene units) of SBR is preferably more than 10 mol%, more preferably more than 15 mol%, and even more preferably more than 20 mol%. It is also preferably less than 80 mol%, more preferably less than 50 mol%, and even more preferably less than 30 mol%. The vinyl content of SBR is a value measured by infrared absorption spectroscopy.

[0113] When the rubber component contains SBR, the content of SBR in 100% by mass of the rubber component is, for example, more than 10% by mass, preferably more than 20% by mass, more preferably more than 40% by mass, and even more preferably 50% by mass or more. On the other hand, the content is, for example, 100% by mass or less, preferably less than 90% by mass, and more preferably less than 80% by mass. By keeping the content within the above range, processability and fuel economy tend to be improved.

[0114] (Other rubber) The other rubbers that can be used other than those mentioned above are not particularly limited, and rubbers used in the tire field can be used. Examples include diene rubbers such as acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), and styrene-isoprene-butadiene copolymer rubber (SIBR). The other rubbers may be used alone or in combination of two or more.

[0115] (Rubber components synthesized from recycled and biomass-derived raw materials) The raw materials (monomers) of synthetic rubbers such as SBR and BR may be derived from petroleum 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 thereof include 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 particularly limited to, styrene. Among these, it is preferable to use recycled butadiene (recycled butadiene) and / or recycled styrene (recycled styrene) as raw materials.

[0116] 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.

[0117] Furthermore, the raw materials (monomers) of synthetic rubbers such as SBR and BR may be derived from biomass. Examples of biomass-derived monomers (biomass monomers) include, but are not limited to, biomass-derived butadiene and biomass-derived aromatic vinyl. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl include, but are not limited to, styrene. Methods for producing biomass monomers are also not limited, including, for example, biological and / or chemical and / or physical conversion of animals and plants. A typical example of biological conversion is microbial fermentation, while examples of chemical and / or physical conversion include catalytic, high-temperature, high-pressure, electromagnetic, critical fluid, and combinations thereof. Biomass sources for these monomers include sugar, wood, plant residues after useful components have been extracted, plant-derived ethanol, and biomass naphtha.

[0118] Polymers synthesized from biomass monomer components (biomass polymers) are not particularly limited and include polybutadiene rubber synthesized from biomass-derived butadiene, aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl, etc. Examples of the aromatic vinyl / butadiene copolymers include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0119] Whether the raw material for a polymer is biomass-derived can be determined by the pMC (percent modern carbon) measured in accordance with ASTM D6866-10.

[0120] pMC is the modern standard reference 14 of sample against C concentration 14 This is the ratio of the carbon concentration, and this value is used as an index showing the biomass ratio of the compound (rubber). The significance of this value is explained below.

[0121] 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 14 C exists. 14 C is called a radioisotope, and its half-life is 5,730 years, and it decreases regularly. It takes 226,000 years for all of it to decay. Therefore, in 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, C was also included in these when it was 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 element.

[0122] on the other hand, 14 C is produced continuously by nuclear reactions in the atmosphere caused by cosmic rays, and this balances with the decrease due to radioactive decay. 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, by using the difference between these values, it is possible to calculate the ratio (biomass ratio) of compounds derived from natural resources (compounds derived from biomass resources) in a certain compound (rubber).

[0123] 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) is measured. 14 The modern standard reference for the C concentration is the carbon circulating in nature as of 1950. 14 The 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.

[0124] Therefore, if rubber is made from 100% biomass (natural) derived materials, it will show a value of approximately 110 pMC, although there may be regional differences (currently, under normal conditions, it is often not 100). On the other hand, for chemical substances derived from petroleum and other fossil fuels, 14 When the carbon concentration is measured, it will be approximately 0 pMC (for example, 0.3 pMC), which corresponds to the biomass ratio of 0% mentioned above.

[0125] 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.

[0126] <Filler> The filler refers to a reinforcing filler, and in the present invention, includes not only recycled carbon black (rCB) but also ordinary carbon black, silica, and other reinforcing fillers used in the tire industry. When the filler contains silica, it may further contain a silane coupling agent.

[0127] (recycled carbon black) In an embodiment of the present invention, recycled carbon black refers to carbon black obtained from the pyrolysis process of used tires or other products containing carbon black, and which has a mass ratio of ash (ash content), which is an incombustible component, of 13% by mass or more when subjected to oxidative combustion by heating in air, as measured by thermogravimetry in accordance with JIS K 6226-2: 2003. The ash content of recycled carbon black is preferably 14% by mass or more, more preferably 15% by mass or more, even more preferably 16% by mass or more, and even more preferably 17% by mass or more.

[0128] 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).

[0129] Recycled carbon black may lack functional groups on its surface, or may be treated to include functional groups on its surface. Treatment to include functional groups on the surface of recycled carbon black can be carried out by conventional methods. For example, European Patent Application Publication No. 3,173,251 discloses treating carbon black obtained from a pyrolysis process with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Japanese Patent Publication No. 6,856,781 also discloses treating carbon black obtained from a pyrolysis process with an amino acid compound containing at least one thiol or disulfide group to obtain surface-activated carbon black. In an embodiment of the present invention, recycled carbon black also includes carbon blacks that have been treated to include functional groups on their surfaces.

[0130] The average primary particle diameter of recycled carbon black is preferably 20 nm or more, more preferably 25 nm or more, even more preferably 30 nm or more, and particularly preferably 35 nm or more. By setting the average primary particle diameter of carbon black within the above range, it is thought that the rubber molecules bound by the carbon black are minimized, allowing them to move flexibly, thereby enabling the polymer molecular chain to relieve stress in response to input force. On the other hand, the average primary particle diameter is preferably 90 nm or less, more preferably 75 nm or less, and even more preferably 60 nm or less. The average primary particle diameter of carbon black is measured by the above-mentioned measurement method.

[0131] The nitrogen adsorption specific surface area (N2SA) of the recycled carbon black is not particularly limited, but from the viewpoint of obtaining sufficient reinforcement and good abrasion resistance, it is preferred that the N2SA be 30 m 2 / g or more is preferable, and 40m 2 / g is more preferable, and 50m 2 / g or more is more preferable, and 60m 2 / g or more is more preferable, and 70m 2 In addition, from the viewpoint of excellent dispersibility and low heat generation, the N2SA has a viscosity of 300 m / g or more. 2 / g is preferable, and 200m 2 / g is more preferable, and 150m 2 / g is more preferable, and 120m 2 / g is more preferable, and 110m 2 / g is more preferable, and 100m 2 / g is more preferable, and 90m 2 / g or less is more preferable. 2 SA is a value measured in accordance with JIS K 6217-2:2017.

[0132] (Carbon black other than rCB) Carbon black other than recycled carbon black (normal carbon black) is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. The raw material for carbon black may be a biomass material such as lignin or vegetable oil, or pyrolysis oil obtained by pyrolysis of waste tires. Carbon black may be produced by combustion, such as in a furnace process, by hydrothermal carbonization (HTC), or by pyrolysis of methane, such as in a thermal black process. Commercially available carbon blacks 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., and Columbia Carbon Co., Ltd. These may be used alone or in combination.

[0133] The average primary particle diameter of carbon black is preferably 20 nm or more, more preferably 25 nm or more, even more preferably 30 nm or more, and particularly preferably 35 nm or more. By setting the average primary particle diameter of carbon black within the above range, it is thought that the rubber molecules bound by the carbon black are minimized, allowing them to move flexibly, thereby enabling the polymer molecular chain to relieve stress in response to input. Meanwhile, the average primary particle diameter is preferably 90 nm or less, more preferably 75 nm or less, and even more preferably 60 nm or less. The average primary particle diameter of carbon black is measured by the above-mentioned measurement method.

[0134] The nitrogen adsorption specific surface area (N2SA) of the carbon black is not particularly limited, but from the viewpoint of obtaining sufficient reinforcement and good abrasion resistance, it is preferred that the N2SA be 30 m 2 / g or more is preferable, and 40m 2 / g is more preferable, and 50m 2 / g or more is more preferable, and 60m 2 / g or more is more preferable, and 70m 2 In addition, from the viewpoint of excellent dispersibility and low heat generation, the N2SA has a viscosity of 300 m / g or more. 2 / g is preferable, and 200m2 / g is more preferable, and 150m 2 / g is more preferable, and 120m 2 / g is more preferable, and 110m 2 / g is more preferable, and 100m 2 / g is more preferable, and 90m 2 It is more preferable that the N of carbon black in this specification is less than 1 / g. 2 SA is a value measured in accordance with JIS K 6217-2:2017.

[0135] (Carbon black content) When carbon black is contained, the total amount of carbon black including recycled carbon black is, for example, more than 30 parts by mass, preferably more than 40 parts by mass, more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more, per 100 parts by mass of the rubber component. On the other hand, the total amount is preferably less than 150 parts by mass, more preferably less than 110 parts by mass, and even more preferably less than 80 parts by mass. When the carbon black content is within the above range, sufficient reinforcement and good dispersion in the rubber are obtained, and sufficient rubber strength and crack resistance tend to be obtained.

[0136] Carbon black content A CB Recycled carbon black content A rCB As shown in formula (4), the value of the ratio is less than 0.85, preferably 0.80, more preferably 0.70, and even more preferably 0.60.

[0137] (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.

[0138] 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.

[0139] 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.

[0140] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and duration, it is possible to suppress the crystallization of silica in rice husk ash (see, for example, JP 2009-2594 A and Akita Prefectural University Web Journal B / 2019, vol. 6, pp. 216-222).

[0141] Amorphous silica extracted from rice husks may be commercially available from Wilmar Co., Ltd., etc.

[0142] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 50 m 2 / g, more preferably 100m 2 / g, more preferably 150m 2 / g, particularly preferably 170m 2 The upper limit of the N2SA of silica is not particularly limited, but is preferably 350 m 2 / g, more preferably less than 250m 2 / g, more preferably less than 200m 2 / g. By keeping it within the above range, cut resistance tends to be improved. The N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0143] (Silica content) When silica is contained, the content per 100 parts by mass of the rubber component is not particularly limited, but from the viewpoint of ensuring fuel economy and ride comfort, it is preferably more than 1 part by mass, more preferably more than 5 parts by mass, more preferably more than 10 parts by mass, and even more preferably more than 20 parts by mass. Also, from the viewpoint of dispersibility and processability of the silica, the content is preferably less than 150 parts by mass, more preferably less than 100 parts by mass, even more preferably less than 50 parts by mass, and even more preferably less than 30 parts by mass.

[0144] (Silane coupling agent) When silica is used as the filler, it is preferable to further contain a silane coupling agent. The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthio Examples of such compounds include sulfide-based compounds such as carbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products that can be used include those from Evonik Degussa, Momentive, Shin-Etsu Silicones Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Dow Corning Toray Co., Ltd. These may be used alone or in combination of two or more.

[0145] (Silane coupling agent content) When containing silane coupling agent, the content of silane coupling agent is preferably more than 1 part by mass, more preferably more than 3 parts by mass, even more preferably more than 5 parts by mass, and even more preferably more than 7 parts by mass, based on 100 parts by mass of silica.On the other hand, the content is preferably less than 20 parts by mass, more preferably less than 18 parts by mass, even more preferably less than 16 parts by mass, and even more preferably less than 14 parts by mass.By making it within the above range, the dispersibility of silica tends to improve.

[0146] (Other fillers) The other fillers are not particularly limited, and materials known in the field of the tire industry can be used, including, for example, inorganic fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica, etc. These may be used alone or in combination of two or more.

[0147] <Other compounding agents> In addition to the rubber component and filler, the rubber composition may contain, as appropriate, compounding agents that are generally used in the tire industry, such as plasticizers, processing aids, vulcanized rubber particles, wax, stearic acid, zinc oxide, antioxidants, vulcanizing agents, and vulcanization accelerators.

[0148] (plasticizer) A plasticizer is a material that imparts plasticity to rubber components and encompasses both liquid and solid plasticizers at 25°C. Examples of plasticizers include resins, oils, liquid rubbers, 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 or products containing various components may also be used as plasticizers. Plasticizers may be used singly or in combination.

[0149] (resin) Of the other compounding ingredients, the rubber composition preferably contains a resin. The resin is not particularly limited, but resins 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, aromatic vinyl resins, dicyclopentadiene resins, C9 resins, and terpene resins are preferred. These resins may be used alone or in combination of two or more.

[0150] <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 most abundant monomer component, 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 available from, for example, Kraton, Eastman Chemical, Mitsui Chemicals, Inc., etc., can be used. These aromatic vinyl resins may be used alone or in combination of two or more.

[0151] <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. These dicyclopentadiene-based resins may be used singly or in combination of two or more.

[0152] <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. These resins may also be hydrogenated or modified. 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, and dicyclopentadiene. Specific examples of C9 resins include coumarone-indene resin, coumarone resin, and indene resin. These C9 resins may be used alone or in combination.

[0153] <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. These C5 resins may be used alone or in combination of two or more.

[0154] <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. As the C5C9 resin, for example, commercially available resins from Tosoh Corporation, LUHUA, etc. may be used. These C5C9 resins may be used alone or in combination of two or more.

[0155] <Terpene resin> Terpene resins refer to resins containing at least one terpene compound selected from the group consisting of α-pinene, β-pinene, limonene, dipentene, etc., as the most abundant monomer component, preferably at least 50 mol %, 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 terpene resins may be used alone or in combination.

[0156] <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., preferably as the monomer component with the largest content, more preferably at least 50 mol %, and may be hydrogenated or modified. The rosin-based resin is not particularly limited, but examples include natural rosin and rosin-modified resins obtained by modifying natural rosin through hydrogenation, disproportionation, dimerization, esterification, etc. These rosin-based resins may be used alone or in combination of two or more.

[0157] <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 largest content, preferably 50 mol% or more. 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. These phenolic resins may be used alone or in combination of two or more.

[0158] When a resin is contained, the content per 100 parts by mass of the rubber component is preferably more than 2 parts by mass, more preferably more than 3 parts by mass, and even more preferably more than 4 parts by mass, while the content is preferably less than 20 parts by mass, more preferably less than 15 parts by mass, and even more preferably less than 10 parts by mass.

[0159] (Plasticizers other than resins) Plasticizers other than resins, such as oil, liquid rubber, and ester-based plasticizers, will now be explained.

[0160] <Oil> Examples of oils include mineral oil, vegetable oil, and animal oil. From the viewpoint of life cycle assessment, waste oils used in rubber mixers and engines, and refined waste cooking oils used in restaurants may also be used. One type of oil may be used alone, or two or more types may be used in combination.

[0161] 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, oils with a low content of polycyclic aromatic compounds (PCA) can also be used as an environmentally friendly measure. Examples of low PCA oils include MES, TDAE, and heavy naphthenic oil. Mineral oils may be used singly or in combination.

[0162] 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 oils, interesterified oils obtained by interesterifying the above oils, hardened oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidatively polymerized oils obtained by oxidizing the above oils, and waste edible oils recovered from edible oils and the like. Vegetable oils may be liquid or solid at 25°C. One vegetable oil may be used alone, or two or more may be used in combination.

[0163] 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 esterified with 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. The acylglycerol may be liquid or solid at 25°C.

[0164] 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 25°C for 24 hours, and after removing the rubber composition, the 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.

[0165] 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.

[0166] Among these, it is desirable that the fatty acid contains a fatty acid with few double bonds, i.e., saturated fatty acid or monounsaturated fatty acid, and oleic acid is preferred. As a vegetable oil containing such a fatty acid, for example, vegetable oil containing saturated fatty acid or monounsaturated fatty acid may be used, or vegetable oil modified by ester exchange or the like may be used. Furthermore, in order to produce vegetable oil containing such a fatty acid, plants may be improved by breeding, genetic modification, genome editing, or the like.

[0167] 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.

[0168] Examples of animal oils include fish oil, beef tallow, whale oil, and oleyl alcohol derived from these.

[0169] The oil content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 3 parts by mass, and even more preferably more than 5 parts by mass. The content is preferably less than 20 parts by mass, more preferably less than 15 parts by mass, and even more preferably less than 10 parts by mass. The oil content includes the amount of oil contained in the rubber component as an extender oil and the amount of oil contained in other components such as sulfur.

[0170] <Liquid rubber> The liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at 25° C., 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. One type of liquid rubber may be used alone, or two or more types may be used in combination.

[0171] <Ester-based plasticizers> 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.

[0172] (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.

[0173] The vulcanized rubber particles are not particularly limited, and may be unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0174] As commercially available vulcanized rubber, for example, products from Lehigh, Muraoka Rubber Industries, Ltd., etc. can be used.

[0175] (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.

[0176] 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.

[0177] (wax) The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used, such as mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. Waxes commercially available from, for example, Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., Ltd., etc. can be used. One type of wax may be used alone, or two or more types may be used in combination.

[0178] When the wax is contained, the amount thereof per 100 parts by mass of the rubber component is preferably more than 0.3 parts by mass, more preferably more than 0.7 parts by mass, and even more preferably more than 1.0 part by mass, while the amount 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.

[0179] (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 0.7 parts by mass, and even more preferably 1.0 part by mass or more from the viewpoint of processability, while the content is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, and even more preferably less than 3 parts by mass from the viewpoint of vulcanization rate.

[0180] (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 0.7 parts by mass, and even more preferably more than 1 part by mass from the viewpoint of processability, while the content is preferably 10 parts by mass or less, more preferably less than 7 parts by mass, and even more preferably 5 parts by mass or less from the viewpoint of abrasion resistance.

[0181] (anti-aging agent) The antioxidant is not particularly limited, but 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-based antioxidants such as diphenyl ether diphenyl ether (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products that can be used include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and Flexis Co., Ltd. One type of antioxidant may be used alone, or two or more types may be used in combination.

[0182] When an antioxidant 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 0.8 parts by mass, and even more preferably more than 1.0 part by mass, while the content is preferably less than 7.0 parts by mass, more preferably less than 5.0 parts by mass, and even more preferably 3.0 parts by mass or less.

[0183] (vulcanizing agent) The vulcanizing agent is not particularly limited, and known vulcanizing agents can be used, such as organic peroxides, sulfur-based vulcanizing agents, resin vulcanizing agents, and metal oxides such as magnesium oxide. Of these, sulfur-based vulcanizing agents are preferred. Examples of sulfur-based vulcanizing agents that can be used include sulfur and sulfur donors such as morpholine disulfide. Of these, sulfur is preferred. One or more types of vulcanizing agents can be used in combination.

[0184] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur (oil-treated sulfur, special sulfur treated with a dispersant, masterbatch-type sulfur, etc.), and insoluble sulfur (oil-treated insoluble sulfur, etc.), all of which are preferably used. Among these, powdered sulfur is preferred. Examples of sulfur that can be used include those manufactured and sold by Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanritsu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc.

[0185] When a vulcanizing agent is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.4 parts by mass, more preferably more than 0.5 parts by mass, even more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass. On the other hand, the content is preferably less than 6.0 parts by mass, more preferably 5.0 parts by mass or less, and even more preferably less than 4.0 parts by mass. When the content of the vulcanizing agent is within the above range, an appropriate reinforcing effect tends to be obtained, and the effects of the present invention tend to be more effectively exhibited. Note that when the vulcanizing agent contains components other than sulfur, such as oil-treated sulfur, the content of the vulcanizing agent refers to the content of the sulfur component itself.

[0186] (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. The vulcanization accelerators may be used alone or in combination of two or more.

[0187] Examples of sulfenamide vulcanization accelerators include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS).

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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).

[0193] The content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably more than 0.3 parts by mass, more preferably more than 0.4 parts by mass, and even more preferably more than 0.5 parts by mass. On the other hand, the content is preferably less than 4.0 parts by mass, more preferably less than 3.0 parts by mass, and even more preferably less than 2.0 parts by mass. When the content of the vulcanization accelerator is within the above range, breaking strength and elongation tend to be ensured, and the effects of the present invention tend to be more favorably exhibited.

[0194] [Sidewall rubber composition] Each component of the rubber composition for a sidewall will be described.

[0195] <Rubber component> The rubber component is described below and is also as described for the rubber composition for the clinch apex. The rubber composition constituting the sidewall preferably contains more than 20% by mass and less than 80% by mass of isoprene-based rubber and at least one of butadiene rubber and styrene-butadiene rubber. It is more preferable that the rubber composition contains isoprene-based rubber (IR rubber) and butadiene rubber (BR). In this case, the rubber component may contain rubber components other than the IR rubber and the BR. The rubber component may also consist solely of rubber selected from the IR rubber and the BR.

[0196] (Content) The content of the rubber component is as described in the section on the rubber composition for clinch apex, and the content of the IR rubber in 100% by mass of the rubber component is, for example, more than 10% by mass, preferably more than 20% by mass, more preferably more than 40% by mass, and even more preferably 50% by mass or more. Meanwhile, the content is, for example, 100% by mass or less, preferably less than 90% by mass, and more preferably less than 80% by mass. By keeping the content within the above range, the tensile strength of the rubber is improved, making it more resistant to impacts from the road surface, and therefore crack resistance tends to be improved.

[0197] The BR content in 100% by mass of the rubber component is, for example, more than 10% by mass, preferably more than 20% by mass, and more preferably more than 30% by mass. On the other hand, the content is, for example, less than 90% by mass, preferably less than 80% by mass, more preferably less than 70% by mass, and even more preferably less than 60% by mass. By keeping the BR content within the above range, the low-temperature strength of the rubber is improved, making it more resistant to impacts from the road surface even at low temperatures, which tends to improve crack resistance.

[0198] The total content of the IR rubber and BR in 100% by mass of the rubber component is preferably more than 80% by mass, more preferably more than 90% by mass, and even more preferably more than 95% by mass, and may be 100% by mass.

[0199] When the rubber component contains SBR, the content of SBR in 100% by mass of the rubber component is, for example, more than 10% by mass, preferably more than 20% by mass, and more preferably more than 30% by mass. On the other hand, the content is, for example, less than 90% by mass, preferably less than 80% by mass, more preferably less than 70% by mass, and even more preferably less than 60% by mass. By keeping the content within the above range, processability and fuel economy tend to be improved.

[0200] <Filler> The filler may contain recycled carbon black (rCB), carbon black other than rCB, or silica. Preferably, it contains silica. When the filler contains silica, it may further contain a silane coupling agent. The filler may further contain other fillers other than carbon black and silica. The components that may constitute the filler are described below, and are also described in the section on the rubber composition for clinch apex.

[0201] (Carbon black content) When carbon black is contained, the total amount of carbon black including recycled carbon black is, for example, more than 30 parts by mass, preferably more than 40 parts by mass, more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more, per 100 parts by mass of the rubber component. On the other hand, the total amount is preferably less than 150 parts by mass, more preferably less than 110 parts by mass, and even more preferably less than 80 parts by mass. When the carbon black content is within the above range, sufficient reinforcement and good dispersion in the rubber are obtained, and sufficient rubber strength and crack resistance tend to be obtained.

[0202] Carbon black content A CB Recycled carbon black content A rCB As shown in formula (4), the value of the ratio is less than 0.85, preferably 0.80, more preferably 0.70, and even more preferably 0.60.

[0203] In addition, for carbon black (including recycled carbon black), the explanation given for the rubber composition for the clinch apex can be similarly applied.

[0204] (Silica content) When silica is contained, the content per 100 parts by mass of the rubber component is not particularly limited, but from the viewpoint of ensuring fuel economy and ride comfort, it is preferably more than 1 part by mass, preferably 5 parts by mass or more, more preferably more than 10 parts by mass, and even more preferably more than 20 parts by mass. Also, from the viewpoint of dispersibility and processability of the silica, the content is preferably less than 150 parts by mass, more preferably less than 100 parts by mass, even more preferably less than 50 parts by mass, and even more preferably less than 30 parts by mass.

[0205] (Relationship between silica content and rCB content) If the rubber composition for sidewalls contains recycled carbon black, the content of the recycled carbon black is rCB The silica content of the rubber composition for the sidewall is expressed as SW SIL When expressed as SW rCB and SW SIL It is preferable that satisfies the following formula (5). (5) SW SIL / SW rCB <0.70

[0206] The right side of equation (5) is preferably 0.65, and more preferably 0.60.

[0207] (Silane coupling agent content) When a silane coupling agent is contained, the content of the silane coupling agent can be similarly applied to the explanation given for the rubber composition for the clinch apex.

[0208] (Other compounding agents) For other details than those mentioned above, the explanation given for the rubber composition for the clinch apex is similarly applicable.

[0209] [Rubber composition for insulation] Each component of the rubber composition for insulation will be described below.

[0210] <Rubber component> The rubber component is described below and is the same as that described for the rubber composition for a clinch apex. The rubber component includes a rubber component containing more than 20% by mass and not more than 100% by mass of isoprene-based rubber. When the content of the isoprene-based rubber in the rubber component is less than 100% by mass, the rubber component preferably includes at least one of butadiene rubber and styrene-butadiene rubber. More preferably, the rubber component includes IR rubber and SBR, but in this case, rubber components other than IR rubber and SBR may also be included. The rubber component may also consist solely of rubber selected from IR rubber and SBR.

[0211] (Content) The content of the IR rubber in 100% by mass of the rubber component is, for example, more than 10% by mass, preferably more than 20% by mass, more preferably more than 40% by mass, and even more preferably 50% by mass or more, while the content is, for example, 100% by mass or less, preferably less than 90% by mass, and more preferably less than 80% by mass.

[0212] The amount of SBR in 100% by mass of the rubber component is, for example, more than 10% by mass, preferably more than 20% by mass, and more preferably more than 30% by mass, while the amount is, for example, less than 90% by mass, preferably less than 80% by mass, more preferably less than 70% by mass, and even more preferably less than 60% by mass.

[0213] The total content of the IR rubber and SBR in 100% by mass of the rubber component is preferably more than 80% by mass, more preferably more than 90% by mass, and even more preferably more than 95% by mass, and may be 100% by mass. By keeping the content within the above range, the tensile strength of the rubber is improved, and resistance to impact from the road surface tends to be improved, thereby improving crack resistance.

[0214] <Filler> The filler may include recycled carbon black (rCB), carbon black other than rCB, and silica. When the filler includes silica, it may further include a silane coupling agent. The filler may further include other fillers other than carbon black and silica. The components that may constitute the filler are as described in the section on the rubber composition for the clinch apex.

[0215] (Carbon black content) When carbon black is contained, the total amount of carbon black including recycled carbon black is preferably more than 30 parts by mass, more preferably more than 35 parts by mass, and even more preferably more than 40 parts by mass per 100 parts by mass of the rubber component. On the other hand, the total amount is preferably less than 150 parts by mass, more preferably less than 110 parts by mass, and even more preferably less than 80 parts by mass. When the carbon black content is within the above range, sufficient reinforcement and good dispersion in the rubber are obtained, and sufficient rubber strength and crack resistance tend to be obtained.

[0216] Carbon black content A CB Recycled carbon black content A rCB As shown in formula (4), the value of the ratio is less than 0.85, preferably 0.80, more preferably 0.70, and even more preferably 0.60.

[0217] In addition, for carbon black (including recycled carbon black), the explanation given for the rubber composition for the clinch apex can be similarly applied.

[0218] (Silica content) When silica is contained, the same explanation as given for the rubber composition for the clinch apex can be applied to the content of silica.

[0219] (Silane coupling agent content) When a silane coupling agent is contained, the content of the silane coupling agent can be similarly applied to the explanation given for the rubber composition for the clinch apex.

[0220] (Other compounding agents) For other details than those mentioned above, the explanation given for the rubber composition for the clinch apex is similarly applicable.

[0221] [Rubber composition for inner liner] Each component of the rubber composition for an inner liner will be described.

[0222] <Rubber component> The rubber component is described below and is also as described for the rubber composition for a clinch apex. The rubber composition for an inner liner includes a rubber component containing more than 70% by mass and not more than 100% by mass of a butyl-based rubber. When the content of the butyl-based rubber in the rubber component is less than 100% by mass, the rubber component may contain a rubber component other than the butyl-based rubber. In this case, it is preferable that the rubber component contains an isoprene-based rubber. The rubber component may consist solely of a butyl-based rubber.

[0223] (butyl rubber) The butyl rubber is preferably a polymer containing an isobutylene unit and an isoprene unit as a repeating unit, and a derivative thereof. Examples of such a butyl rubber include butyl rubber (IIR); halogenated butyl rubbers such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR). Among these, halogenated butyl rubber is preferred, and brominated butyl rubber and chlorinated butyl rubber are more preferred, from the viewpoint of achieving a balanced improvement in sheet processability and air barrier properties. These may be used alone or in combination.

[0224] As for butyl rubber, in addition to regular butyl rubber (butyl rubber other than recycled butyl rubber), recycled butyl rubber can be used in combination. Recycled butyl rubber usually has a high content of non-halogenated butyl rubber (regular butyl rubber), so by using it in combination with halogenated butyl rubber, good air barrier properties and vulcanization speed can be ensured. Recycled butyl rubber can be used alone or in combination of two or more types.

[0225] The rubber component may contain other rubber components in addition to the butyl rubber. Examples include diene rubbers such as isoprene rubber (IR rubber), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). The same explanations as given for the rubber composition for the clinch apex rubber apply to these other rubber components. These other rubber components may be used alone or in combination of two or more.

[0226] (Content) The content of the butyl rubber in 100% by mass of the rubber component is preferably more than 70% by mass, more preferably more than 75% by mass, and even more preferably 80% by mass or more, from the viewpoint of sufficient air barrier properties.

[0227] <Filler> The filler may include recycled carbon black (rCB), carbon black other than rCB, or silica. When the filler includes silica, it may further include a silane coupling agent. The filler may further include other fillers other than carbon black and silica. The components that may constitute the filler are as described in the section on the rubber composition for the clinch apex.

[0228] (Carbon black content) When carbon black is contained, the total amount of carbon black including recycled carbon black is, for example, more than 30 parts by mass, preferably more than 40 parts by mass, more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more, per 100 parts by mass of the rubber component. On the other hand, the total amount is preferably less than 150 parts by mass, more preferably less than 110 parts by mass, and even more preferably less than 80 parts by mass. When the carbon black content is within the above range, sufficient reinforcement and good dispersion in the rubber are obtained, and sufficient rubber strength and crack resistance tend to be obtained.

[0229] Carbon black content ACB Recycled carbon black content A rCB As shown in formula (4), the value of the ratio is less than 0.85, preferably 0.80, more preferably 0.70, and even more preferably 0.60.

[0230] In addition, for carbon black (including recycled carbon black), the explanation given for the rubber composition for the clinch apex can be similarly applied.

[0231] (Silica content) When silica is contained, the same explanation as given for the rubber composition for a clinch apex can be applied to the content thereof per 100 parts by mass of the rubber component.

[0232] (Silane coupling agent content) When a silane coupling agent is contained, the content of the silane coupling agent can be similarly applied to the explanation given for the rubber composition for the clinch apex.

[0233] (Other compounding agents) For other details than those mentioned above, the explanation given for the rubber composition for the clinch apex is similarly applicable.

[0234] The above is an explanation of each component when the tire components are composed of a rubber composition containing recycled carbon black. When the tire components are composed of a rubber composition that does not contain recycled carbon black, as described above, the above explanation can be applied by replacing the recycled carbon black in the above explanation with ordinary carbon black.

[0235] <Other rubber components that make up tires> The tire according to the present invention may include rubber members other than those described above. Such other rubber members are not particularly limited, and various rubber members generally used in tires may be used.

[0236] In the tire according to the present invention, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining compounds 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.

[0237] <Application> The tire according to the present invention can be a pneumatic tire or a non-pneumatic tire, and can be suitably used as a pneumatic tire. Furthermore, in this specification, the tire can be used for various purposes, such as a passenger car tire, a heavy-duty tire for trucks and buses, a motorcycle tire, and a high-performance tire. It can also be used as a tire for electric vehicles.

[0238] <Production method> The tire according to the embodiment of the present invention can be manufactured by a known method.

[0239] (Production of rubber composition) Each of the above rubber compositions can be produced by a known method. For example, they can be produced by kneading the above components using a rubber kneading device such as an open roll or an internal kneader (e.g., a Banbury mixer or kneader). 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 can be divided into multiple processes as desired. The kneading conditions are not particularly limited, but examples include a method in which the base kneading process involves kneading for 3 to 10 minutes at a discharge temperature of 150 to 170°C, and a method in which the final kneading process involves kneading for 1 to 5 minutes at a discharge temperature of 50 to 110°C.

[0240] (tire manufacturing) Each rubber composition obtained above can be extruded in the unvulcanized state to form a desired tire component shape, respectively, into an unvulcanized clinch apex, sidewall, insulation, and inner liner. The tire according to the present embodiment can be produced by molding at least one of the thus obtained clinch apex, sidewall, insulation, and inner liner together with other tire components in a tire building machine using a conventional method to produce an unvulcanized tire. The unvulcanized tire can be obtained by heating and pressurizing (vulcanizing) the tire in a vulcanizer. The vulcanization conditions are not particularly limited, and examples thereof include vulcanization at 150 to 200°C for 5 to 30 minutes. [Example]

[0241] 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. Rubber compositions and tires obtained according to the tables were examined using the various chemicals shown below, and the results calculated based on the evaluation method described below are shown as durability indices at the bottom of each table.

[0242] <Material> The materials used in the examples and comparative examples will be summarized below. Natural rubber: TSR20 BR: UBEPOL BR150B (UBE Corporation, unmodified BR, cis content: 97 mol%, Mw: 440,000) SBR: SBR1502 (manufactured by JSR Corporation, styrene content: 23.5% by mass, vinyl content: 18% by mole, Mw: 500,000) Butyl rubber: Chlorobutyl HT1066 (Exxon Mobil, chlorobutyl rubber) Carbon black 1: Show Black N550 (manufactured by Cabot Japan Co., Ltd., N2SA: 42m 2 / g;Ash content: 1.0% by mass or less) Carbon black 2: Show Black N660 (manufactured by Cabot Japan Co., Ltd., N2SA: 35 m 2 / g;Ash content: 1.0% by mass or less) Carbon black 3: Show Black N330 (manufactured by Cabot Japan Co., Ltd., N2SA: 75 m 2 / g;Ash content: 1.0% by mass or less) Carbon black 4: Show Black N220 (manufactured by Cabot Japan Co., Ltd., N2SA: 114m 2 / g;Ash content: 1.0% by mass or less) Recycled carbon black (rCB): Carbon black obtained from the pyrolysis process of tires (ash content: 17% by mass) Silica: Ultrasil VN3 (manufactured by Evonik Degussa, N2SA: 175 ml 2 / g) Wax: Ozoace 0355 (Nippon Seiro Co., Ltd., paraffin-based) Antioxidant 1: Nocrac 6C (Ouchi Shinko Chemical Industry Co., Ltd., N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) Antioxidant 2: Nocrac RD (Ouchi Shinko Chemical Industry Co., Ltd., poly(2,2,4-trimethyl-1,2-dihydroquinoline)) Oil: Diana Process NH-70S (Idemitsu Kosan Co., Ltd., aromatic process oil) Zinc oxide: Zinc oxide type 2 (manufactured by Mitsui Mining & Smelting Co., Ltd.) Stearic acid: Camellia stearate beads (NOF Corporation) Sulfur: HK-200-5 (Hosoi Chemical Industry Co., Ltd., powdered sulfur, oil content: 5% by mass) Vulcanization accelerator: Noccela CZ (Ouchi Shinko Chemical Industry Co., Ltd., N-cyclohexyl-2-benzothiazole sulfenamide) Carcass cord 1: Polyethylene terephthalate fiber, cord structure 3360dtex / 2 Carcass cord 2: Polyethylene terephthalate fiber, cord structure 1100dtex / 2 Carcass cord 3: Polyethylene terephthalate fiber, cord structure 4500dtex / 2 Carcass cord 4: Polyethylene terephthalate fiber, cord structure 2880dtex / 2

[0243] <Tire using rubber composition for clinch apex> According to the formulations shown in Tables 2-1 and 2-2, a 1.7 L internal Banbury mixer was used to mix all chemicals except sulfur and the vulcanization accelerator for 5 minutes until the discharge temperature reached 170°C, yielding a kneaded mixture. Next, sulfur and the vulcanization accelerator were added to the mixture using a two-screw open roll mill, and the mixture was mixed for 4 minutes until the temperature reached 105°C, yielding an unvulcanized rubber composition. The unvulcanized rubber composition was extruded into the shape of a clinch apex using an extruder equipped with a predetermined die, and then bonded together with other tire components to form an unvulcanized tire. The tire was then press-vulcanized for 12 minutes at 170°C to produce each test tire (Tire 1: 175 / 70R14, Tire 2: 235 / 70R16). The carcass consisted of a single carcass ply containing carcass cords of the desired fineness. The carcass cord placement was 38 cords per 50 mm.

[0244] <Tire using rubber composition for sidewall> According to the formulations shown in Tables 3-1 and 3-2, a 1.7 L internal Banbury mixer was used to mix all chemicals except sulfur and the vulcanization accelerator for 5 minutes until the discharge temperature reached 170°C, yielding a kneaded mixture. Next, sulfur and the vulcanization accelerator were added to the mixture using a two-screw open roll mill, and the mixture was mixed for 4 minutes until the temperature reached 105°C, yielding an unvulcanized rubber composition. The unvulcanized rubber composition was extruded into the shape of a sidewall using an extruder equipped with a predetermined die, and then bonded together with other tire components to form an unvulcanized tire. The tire was then press-vulcanized for 12 minutes at 170°C to produce each test tire (Tire 1: 175 / 70R14, Tire 2: 235 / 70R16). The carcass consisted of a single carcass ply containing carcass cords of the desired fineness. The carcass cord placement was 38 cords per 50 mm.

[0245] <Tire using rubber composition for insulation> According to the compounding recipes shown in Tables 4-1 and 4-2, chemicals other than sulfur and vulcanization accelerators were mixed in a 1.7-liter closed-type Banbury mixer at a discharge temperature of 150°C for 5 minutes. The sulfur and vulcanization accelerator were then added to the resulting mixture, and the mixture was mixed in an open roll for 4 minutes until the temperature reached 105°C, yielding an unvulcanized rubber composition for the inner liner. The unvulcanized rubber composition for the inner liner was molded into a sheet and laminated with other tire components to form an unvulcanized tire. The tire was press-vulcanized for 12 minutes at 170°C to produce each test tire (Tire 1: 175 / 70R14, Tire 2: 235 / 70R16). The carcass consisted of a single carcass ply containing carcass cords of the desired fineness. The carcass cord count was 38 cords / 50 mm.

[0246] <Tire using rubber composition for inner liner> According to the formulations shown in Tables 5-1 and 5-2, a 1.7 L internal Banbury mixer was used to mix all chemicals except sulfur and the vulcanization accelerator for 4 minutes until the discharge temperature reached 160°C, yielding a kneaded mixture. Next, sulfur and the vulcanization accelerator were added to the resulting mixture using a two-screw open roll mill, and the mixture was mixed for 4 minutes until the temperature reached 80°C, yielding an unvulcanized rubber composition. The unvulcanized rubber composition was molded into the shape of an inner liner, bonded together with other tire components, and formed into an unvulcanized tire. The tire was press-vulcanized at 170°C for 12 minutes to produce each test tire (Tire 1: 175 / 70R14, Tire 2: 235 / 70R16). The carcass consisted of a single carcass ply containing carcass cords of the desired fineness. The carcass cord placement was 38 cords per 50 mm.

[0247] Furthermore, the microbumps on the outer surface of the sidewall are formed during press vulcanization using a mold equipped with side plates on which a marking for forming the microbumps is engraved on the surface facing the microbump-forming portion. The shapes of microbumps A and B are as follows: Height h (mm) is the height of the microbump at the tire's maximum width position, height h1 (mm) is the height of the microbump at the tire's radially outermost position, and height h2 (mm) is the height of the microbump at the tire's radially innermost position. When the value of h1 is greater than h, the height of the microbump gradually increases from the tire's maximum width position toward the tire's radially outer side, and when the value of h2 is greater than h, the height of the microbump gradually increases from the tire's maximum width position toward the tire's radially inner side.

[0248] [Table 1]

[0249] <Evaluation> The results of evaluation of each test tire according to the evaluation methods described below are shown in the corresponding columns of the tables below.

[0250] (crack resistance) Using a drum testing machine, each test tire was run 20,000 km under the following test conditions, after which the rim was removed and the tire was visually inspected to evaluate the degree of cracking. Evaluation was performed using an integer value of 1 to 5, with a higher score indicating better crack resistance. A total score was calculated by 20 expert panelists based on this evaluation standard. The total score of the reference comparative example 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. Test conditions (Tire 1: 175 / 70R14, Tire 2: 235 / 70R16) Tire 1: Internal pressure 210kPa, load 4.4kN, speed 80km / h Tire 2: Internal pressure 210kPa, load 7.5kN, speed 80km / h

[0251] [Table 2]

[0252] [Table 3]

[0253] [Table 4]

[0254] [Table 5]

[0255] [Table 6]

[0256] [Table 7]

[0257] [Table 8]

[0258] [Table 9]

[0259] <Embodiment> The following describes a preferred embodiment.

[0260] [1] A tire having a carcass cord and at least one tire component made of a rubber composition containing recycled carbon black, The fineness (dtex) of the carcass cord is F, and the maximum load capacity (kg) of the tire is W. LWhen the breaking elongation (%) of the tire component is EB, F is 6000 or more, preferably 6600 or more, more preferably 7000 or more, even more preferably 7400 or more, and still more preferably 7600 or more, and F, W L and EB satisfies the following formulas (1) and (2), (1) F / W L ≧5.6 (2) (Firmware L )×EB≧840 Preferably, the right side of formula (1) is 6.0. [2] The tire according to [1], wherein the right side of formula (1) is 7.0, preferably 8.0, and more preferably 10.0. [3] The tire according to [1], wherein the right side of formula (1) is 12.0, preferably 14.0. [4] The tire according to any one of [1] to [3], wherein the right side of formula (2) is 1400. [5] The tire according to any one of [1] to [3], wherein the right side of formula (2) is 2400, preferably 2800, more preferably 4000, even more preferably 5000, and still more preferably 8000. [6] The fineness F and the maximum load capacity W L and a loss tangent 70°C tanδ of the rubber composition at 70°C satisfy the following formula (3), (3) (Firmware L )×70℃ tanδ≧0.40 A tire in which the right side of formula (3) is preferably 1.0, more preferably 1.2, even more preferably 1.4, even more preferably 2.0, even more preferably 2.2, and even more preferably 2.8. [7] At least one tire component made of the rubber composition containing the recycled carbon black is a clinch apex, the rubber composition constituting the clinch apex includes a rubber component containing more than 20% by mass and not more than 100% by mass of isoprene-based rubber, The tire according to any one of [1] to [6], wherein when the content of the isoprene-based rubber in the rubber component is less than 100% by mass, the rubber component contains at least one of butadiene rubber and styrene-butadiene rubber. [8] At least one tire component made of the rubber composition containing the recycled carbon black is a sidewall, The tire according to any one of [1] to [6], wherein the rubber composition constituting the sidewall contains more than 20% by mass but less than 80% by mass of an isoprene-based rubber, and at least one of a butadiene rubber and a styrene-butadiene rubber. [9] At least one tire component made of the rubber composition containing the recycled carbon black is insulation, the rubber composition constituting the insulation includes a rubber component containing more than 20% by mass and not more than 100% by mass of isoprene-based rubber, The tire according to any one of [1] to [6], wherein when the content of the isoprene-based rubber in the rubber component is less than 100% by mass, the rubber component contains at least one of butadiene rubber and styrene-butadiene rubber.

[10] At least one tire component made of the rubber composition containing the recycled carbon black is an inner liner, the rubber composition constituting the inner liner includes a rubber component containing more than 70% by mass and not more than 100% by mass of a butyl-based rubber, The tire according to any one of [1] to [6], wherein when the content of the butyl rubber in the rubber component is less than 100% by mass, the rubber component contains an isoprene rubber.

[11] The tire according to [8], wherein the rubber composition constituting the sidewall contains silica.

[12] The rubber composition contains carbon black, the carbon black contains recycled carbon black, and the content of the carbon black relative to 100 parts by mass of the rubber component is A CB The content of the recycled carbon black is A rCB When A CB and A rCBThe tire according to any one of [1] to

[11] , wherein the relationship of the following formula (4) is satisfied: (4) A rCB / A CB <0.85 A tire in which the right side of formula (4) is preferably 0.80, more preferably 0.70, and even more preferably 0.60.

[13] The content of recycled carbon black per 100 parts by mass of the rubber component in the rubber composition constituting the sidewall is SW rCB and the content of silica relative to 100 parts by mass of the rubber component in the rubber composition constituting the sidewall is SW SIL When SW rCB and SW SIL The tire according to any one of [1] to

[12] , wherein the following formula (5) is satisfied: (5) SW SIL / SW rCB <0.70 A tire in which the right side of formula (5) is preferably 0.65, more preferably 0.60, and even more preferably 0.50.

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

[13] , wherein the sidewall has a micro-ridge formation portion in which a plurality of micro-ridges are formed on the outer surface.

[15] The tire according to

[14] , wherein the shape of the micro-protrusions is columnar, frustum or rib-like.

[16] The micro-ridges have a height of 0.03 mm or more and 0.50 mm or less, and are formed in at least one direction with 20 or more micro-ridges spaced 0.50 mm or less apart. 2 The tire according to

[14] or

[15] , having an area of ​​at least 100 mm.

[17] The tire according to any one of

[14] to

[16] , wherein the maximum width of the minute protuberances is 0.03 mm or more and 0.50 mm or less.

[18] A tire according to any one of

[14] to

[17] , wherein the height of the micro-protrusions gradually increases from the maximum tire width position toward the outer side in the tire radial direction, and gradually increases from the maximum tire width position toward the inner side in the tire radial direction. [Explanation of symbols]

[0261] 1 tire 2 Clinch Apex 3 Sidewall 4 Insulation 5 Inner liner 6. Carcass CL Tire equatorial plane R rim 11 Sidewall outer surface 12 Microprotuberance 13 Microprotuberance 14 Microprotuberance w Maximum width of the micro-ridge d Spacing of micro-ridges h Micro-ridge height

Claims

1. A tire having a carcass cord and at least one tire component made of a rubber composition containing recycled carbon black, The fineness (dtex) of the carcass cord is F, and the maximum load capacity (kg) of the tire is W. L and the breaking elongation (%) of the tire component is EB, F is 6000 or more, and F, W L and a tire in which EB satisfies the following formulas (1) and (2). (1) F / W L ≧5.6 (2) (F / W L )×EB≧840

2. 2. The tire according to claim 1, wherein the right side of formula (1) is 7.

0.

3. 2. The tire according to claim 1, wherein the right side of formula (1) is 12.

0.

4. 2. The tire according to claim 1, wherein the right side of formula (2) is 1,400.

5. 2. The tire according to claim 1, wherein the right side of formula (2) is 2,400.

6. The fineness F and the maximum load capacity W L and a loss tangent 70°C tan δ of the rubber composition at 70°C satisfy the following formula (3): (3) (F / W L )×70℃tanδ≧0.40

7. At least one tire component made of the rubber composition containing the recycled carbon black is a clinch apex, the rubber composition constituting the clinch apex includes a rubber component containing more than 20% by mass and not more than 100% by mass of an isoprene-based rubber, The tire according to any one of claims 1 to 5, wherein when the content of the isoprene-based rubber in the rubber component is less than 100% by mass, the rubber component contains at least one of a butadiene rubber and a styrene-butadiene rubber.

8. At least one tire component made of the rubber composition containing the recycled carbon black is a sidewall, The tire according to any one of claims 1 to 5, wherein a rubber composition constituting the sidewall contains more than 20% by mass but less than 80% by mass of an isoprene-based rubber and at least one of a butadiene rubber and a styrene-butadiene rubber.

9. At least one tire component made of the rubber composition containing the recycled carbon black is insulation, the rubber composition constituting the insulation includes a rubber component containing more than 20% by mass and not more than 100% by mass of an isoprene-based rubber, The tire according to any one of claims 1 to 5, wherein when the content of the isoprene-based rubber in the rubber component is less than 100% by mass, the rubber component contains at least one of a butadiene rubber and a styrene-butadiene rubber.

10. At least one tire component made of the rubber composition containing the recycled carbon black is an inner liner, the rubber composition constituting the inner liner includes a rubber component containing more than 70% by mass and not more than 100% by mass of a butyl-based rubber, The tire according to any one of claims 1 to 5, wherein when the content of the butyl-based rubber in the rubber component is less than 100% by mass, the rubber component contains an isoprene-based rubber.

11. 9. The tire according to claim 8, wherein the rubber composition constituting the sidewall contains silica.

12. The rubber composition contains carbon black, the carbon black contains recycled carbon black, and the content of the carbon black relative to 100 parts by mass of the rubber component is A CB The content of the recycled carbon black is A rCB When this is done, A CB and A rCB The tire according to any one of claims 1 to 5, wherein the relationship of the following formula (4) is satisfied: (4) A rCB / A CB <0.85

13. The content of recycled carbon black per 100 parts by mass of the rubber component in the rubber composition constituting the sidewall is SW rCB and the content of silica relative to 100 parts by mass of the rubber component in the rubber composition constituting the sidewall is SW SIL When SW rCB and SW SIL The tire according to claim 11, wherein and satisfy the following formula (5): (5)SW SIL / SW rCB <0.70

14. The tire according to any one of claims 1 to 5, wherein the sidewall has a micro-ridge formation portion in which a plurality of micro-ridges are formed on the outer surface.

15. 15. The tire of claim 14, wherein the microbumps are pillar-shaped, frustum-shaped, or rib-shaped.

16. The micro-ridges have a height of 0.03 mm or more and 0.50 mm or less, and 20 or more are formed at intervals of 0.50 mm or less in at least one direction, and the micro-ridge formation portion is 10 mm 2 15. The tire of claim 14 having an area of ​​at least

17. 15. The tire of claim 14, wherein the maximum width of the microbumps is equal to or greater than 0.03 mm and equal to or less than 0.50 mm.

18. 15. The tire of claim 14, wherein the height of the microbumps increases radially outward from the maximum tire width location and increases radially inward from the maximum tire width location.

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