Tire

Abstract

To provide a tire excellent in total performance of low fuel consumption performance and riding comfort performance.SOLUTION: A tire comprising a tread portion and a pair of sidewalls, wherein a rubber composition constituting the tread portion comprises a rubber component containing a styrene-butadiene rubber in an amount of 50% by mass or more based on 100% by mass of the rubber component, and comprises 50 parts by mass or more of silica based on 100 parts by mass of the rubber component, and when a total vinyl content (mol%) in the rubber component is Y, a thickness (mm) of the sidewall is W, and a tire outer diameter (mm) of the tire is Dt, Y ≤ 30 and W ≤ 4.0, and W, Y, and Dt satisfy the relationship of the formula (1): Y * W / Dt * 100 ≤ 15 (1) SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] To improve fuel efficiency, studies are underway to reduce the weight of tires by reducing rubber volume, but reducing rubber volume poses the problem of making it difficult to achieve satisfactory ride comfort.Patent Document 1 describes a lightweight tire in which the ratio of tire weight to maximum load capacity is set to a predetermined value or less, and the thickness of the tread rubber and the thickness of the sidewall rubber are adjusted, and further, a predetermined amount of thermoplastic elastomer is blended into the rubber composition that makes up the tread rubber, thereby improving ride comfort while maintaining light weight. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-24298 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a tire that is excellent in overall performance, including fuel economy and ride comfort. [Means for solving the problem]

[0005] The present invention relates to the following tire. A tire having a tread portion and a pair of sidewalls, The rubber composition constituting the tread portion includes a rubber component containing 50% by mass or more of styrene-butadiene rubber in 100% by mass of the rubber component, and includes 50 parts by mass or more of silica per 100 parts by mass of the rubber component, The total vinyl content (mol%) in the rubber component is Y, The thickness (mm) of the sidewall is W, When the tire outer diameter (mm) of the tire is Dt, A tire in which Y≦30, W≦4.0, and W, Y, and Dt satisfy the relationship of formula (1). (1) Y×W / Dt×100≦15 [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a tire that is excellent in overall performance in terms of fuel economy and ride comfort.

[0007] While not intending to be bound by theory, the following is believed to be the mechanism by which the overall performance of fuel economy and ride comfort is improved in the present invention. Specifically, (A) by setting the total vinyl content of the rubber component contained in the rubber composition constituting the tread portion to a predetermined amount or less, minute vinyl domains are formed in the rubber composition. The minute vinyl domains allow the polymer to move more flexibly. It is believed that this flexibility improves the polymer's mobility, improves microscopic road-holding performance, and improves ride comfort. (B) By setting the silica content in the filler to 50% by mass or more, it is believed that the mobility of polymer chains is suppressed, contributing to reduced heat generation in the rubber composition. (C) By setting the styrene-butadiene rubber content to 50% by mass or more, it is believed that the proportion of styrene domains in the rubber component increases, making it easier for the rubber as a whole to absorb impacts generated during driving. (D) It is believed that by setting the sidewall thickness to a predetermined value or less, longitudinal rigidity and heat storage capacity are reduced. Furthermore, it is believed that rolling resistance can be reduced by balancing the sidewall thickness, the total vinyl content in the rubber component of the rubber composition that makes up the tread, and the tire outer diameter so as to satisfy formula (E) (1).These factors (A) to (E) work together to influence the heat generated by the movement of polymer chains in the tread and the heat storage and release in the sidewalls, resulting in overall improvements in fuel economy and ride comfort. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a tire according to an embodiment of the present invention taken along a plane including a tire rotation axis. [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

[0009] Hereinafter, a tire according to one embodiment of the present invention will be described. The tire according to this embodiment has a tread portion and a pair of sidewalls, and the rubber composition constituting the tread portion includes a rubber component containing 50% by mass or more of styrene-butadiene rubber per 100% by mass of the rubber component, and also includes 50 parts by mass or more of silica per 100 parts by mass of the rubber component, and the total vinyl content (mol %) of the rubber component is Y, the thickness (mm) of the sidewall is W, and the outer diameter (mm) of the tire of the tire is Dt, where Y≦30 and W≦4.0, and W, Y, and Dt satisfy the relationship of formula (1). (1) Y×W / Dt×100≦15

[0010] The rubber composition preferably contains 30% by mass or more, and more preferably 40% by mass or more, of isoprene-based rubber in 100% by mass of the rubber component.

[0011] Silica has a weak interaction with isoprene rubber, and it is thought that including a certain amount of isoprene rubber increases the polymer phase, which has a weak interaction with silica. As a result, the polymer phase becomes more flexible, improving microscopic road conformity and ride comfort.

[0012] The rubber composition further comprises a compound represented by general formula (I) [ka] (In the formula, R 1 represents a hydrocarbon group, and R 2 and R 3 is one of which is -(AO) n -H group (wherein n is an integer of 1 or more, and AO is an oxyalkylene group having 2 or more carbon atoms), and the other is a hydrogen atom, a hydrocarbon group, or -(AO) n -H group (where the symbols have the same meanings as above), and R 2 and R 3 Together - (AO) n When they are —H groups, they may be the same or different. It is preferred that the compound contains a compound represented by the formula:

[0013] It is believed that the inclusion of the compound represented by the above formula (I) improves the dispersibility of silica and improves the compatibility between silica and polymer, thereby improving fuel economy.

[0014] The amount of silica is preferably 70 parts by mass or more, and more preferably 100 parts by mass or more, per 100 parts by mass of the rubber component.

[0015] It is believed that the silica content of the rubber composition is sufficient to suppress heat buildup and improve fuel economy, and that a high silica content can improve wet grip performance in addition to the effects of the present invention.

[0016] The acetone extractable amount of the rubber composition is preferably 20% by mass or more, and more preferably 30% by mass or more.

[0017] If the amount of acetone extraction is a predetermined amount, it is believed that the dispersibility of silica in rubber is improved by the organic low molecular weight compound in the plasticizer contained in the rubber composition, contributing to improved fuel economy.

[0018] The right side of formula (1) is preferably 8, more preferably 3, and even more preferably 2.

[0019] Tires that satisfy stricter conditions in formula (1) are thought to have even better fuel economy and ride comfort.

[0020] The rubber composition preferably contains a silane coupling agent having a mercapto group.

[0021] It is believed that the inclusion of a specific silane coupling agent in the rubber composition improves the dispersion of silica, and the increased reinforcing properties contribute to improved fuel economy.

[0022] The total amount of styrene in the rubber component is preferably 10% by mass or less.

[0023] It is believed that by keeping the total amount of styrene in the rubber component below a predetermined amount, energy loss during driving is reduced, contributing to improved fuel economy.

[0024] The sidewall preferably has a micro-ridge formation portion in which a plurality of micro-ridges are formed on the outer surface.

[0025] The presence of the micro-ridge formation portion can suppress stress concentration on the outer surface of the sidewall, which is thought to contribute to improved fuel economy and ride comfort.

[0026] The shape of the micro-protrusions is preferably columnar, frustum or rib-like.

[0027] By providing the micro-ridges with these predetermined shapes, stress concentration on the outer surface of the sidewall can be suppressed, which is thought to contribute to improved fuel economy and ride comfort.

[0028] 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.

[0029] By keeping the size of the micro-ridges within these predetermined ranges, stress concentration on the outer surface of the sidewall can be suppressed, which is thought to contribute to improved fuel economy and ride comfort.

[0030] The maximum width of the micro-protuberances is preferably 0.03 mm or more and 5.0 mm or less.

[0031] 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 fuel economy and ride comfort.

[0032] 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.

[0033] 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 fuel efficiency and ride comfort.

[0034] In this specification, the upper and lower limit values ​​of "greater than or equal to" and "less than or equal to" in describing a numerical range can be arbitrarily combined, and in addition, numerical values ​​in the examples can be combined with the upper and lower limit values. Furthermore, in this specification, a numerical range indicated as including both end values ​​is understood to simultaneously indicate a numerical range excluding either end value, or even a numerical range excluding both end values, as long as it does not contradict the spirit of the present invention.

[0035] [Definition] The "tread portion" refers to a component that includes the portion that forms the tread surface of the tire, and in the case where components that reinforce and form the tire frame, such as a reinforcing layer or carcass, are provided on the tire radially inner side in the tire cross section, the "tread portion" refers to a component that is located on the tire radially outer side of these components.

[0036] "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.

[0037] Unless otherwise specified, the "dimensions of each part of the tire" are values ​​that are specified when they appear on the outer surface of the tire in a normal state, while those that exist inside the tire or on a cut surface of the tire are values ​​that are specified when, for example, the tire is cut along a plane that includes the tire rotation axis and the cut tire piece is maintained at the rim width of a normal rim.

[0038] "Genuine rim" refers to the rim specified for each tire by the standard system, including 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 tires 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).

[0039] "Normal internal pressure" refers to the air pressure specified for each tire in the standard system that includes the standard on which the tire is based. For example, for JATMA, it refers to "Maximum Air Pressure," for ETRTO, it refers to "INFLATION PRESSURE," and for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims, refer to JATMA, ETRTO, and TRA in that order, and follow 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. If multiple normal internal pressures of 250kPa or more are listed, it refers to the smallest value among them.

[0040] "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.

[0041] "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 radial direction of the tire 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. Maximum load capacity is synonymous with the normal load.

[0042]

number

[0043] The "total vinyl content (mol%) Y of the rubber component" is the sum of all the values ​​calculated by multiplying the vinyl content (mol%) derived from 1,2-butadiene bonds of each rubber constituting the entire rubber component (100% by mass) by its content in the entire rubber component.

[0044] The "total styrene content in the rubber component" refers to the sum of the styrene content (mass%) of each rubber constituting the entire rubber component (100% by mass), multiplied by its styrene content in the entire rubber component. Specifically, it is calculated as Σ (styrene content (mass%) of each styrene-containing rubber × content (mass%) of each styrene-containing rubber in the rubber component / 100). For example, if the rubber component consists of 30% by mass of a first SBR (styrene content: 25% by mass), 60% by mass of a second SBR (styrene content: 27.5% by mass), and 10% by mass of BR, the total styrene content (S) in 100% by mass of the rubber component is 24.0% by mass (= 25 × 30 / 100 + 27.5 × 60 / 100 + 0 × 10 / 100).

[0045] "Sidewall thickness W (mm)" refers to the thickness (mm) of the sidewall rubber at the widest point of the tire, measured by cutting the tire on a plane including the tire's rotation axis and holding the cut at the standard rim width. For example, this corresponds to W in Figure 1. "Sidewall thickness" is the average value of the values ​​measured on a cross section of the tire taken along a plane including the tire's rotation axis at five locations after rotating the tire 72 degrees each time. Measurements can be performed by creating a cross section of the tire taken along a plane including the tire's rotation axis and holding the section so that the distance between the beads is aligned with the standard rim width.

[0046] "Plasticizer" is a material that imparts plasticity to the rubber component and is a component that is extracted from the rubber composition using acetone. Plasticizers include plasticizers that are liquid (liquid state) at 25°C and plasticizers that are solid at 25°C. However, this does not include wax and stearic acid, which are commonly used in the tire industry.

[0047] The "plasticizer content" also includes the amount of plasticizer in the rubber component extended by the plasticizer.

[0048] [Measurement method] "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.

[0049] "Vinyl content (amount of 1,2-bonded butadiene units)" can be measured by pyrolysis gas chromatography or NMR measurement ( 1 H-NMR and 13It 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.

[0050] "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.

[0051] The "glass transition temperature (Tg) of a rubber composition" is determined by measuring a temperature distribution curve of tan δ using a dynamic viscoelasticity measuring device (e.g., an Iplexer series manufactured by GABO) under conditions of a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±0.5%, and a heating rate of 2°C / min, and is the temperature (tan δ peak temperature) corresponding to the maximum value in the temperature distribution curve obtained within a range of -60°C to 40°C. Note that, in measurements within the range of -60 to 40°C, if the tan δ value continues to gradually increase or decrease with increasing temperature, the glass transition temperature of the rubber composition is determined to be 40°C or -60°C, respectively. Furthermore, if there are two or more points showing maximum values ​​within the range of -60°C to 40°C, the lowest temperature point is determined to be the glass transition temperature.

[0052] The "glass transition temperature of the rubber component" refers to the static glass transition temperature of each rubber component determined by a differential scanning calorimeter (for example, Q200 manufactured by TA Instruments Japan Co., Ltd.).

[0053] The "weight average molecular weight (Mw)" can be determined by converting the measured value into standard polystyrene equivalents using gel permeation chromatography (GPC) (for example, a GPC-8000 series manufactured by Tosoh Corporation, a differential refractometer as the detector, and a TSKgel SuperMultipore HZ-M column manufactured by Tosoh Corporation). This applies to, for example, SBR, BR, etc.

[0054] The "nitrogen adsorption specific surface area (N2SA) of carbon black" is measured in accordance with JIS K 6217-2:2017.

[0055] The "nitrogen adsorption specific surface area (N2SA) of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0056] The "average primary particle size" is calculated by photographing particles with a transmission or scanning electron microscope and taking the arithmetic average of the particle sizes of 400 particles. If the particle shape is nearly circular, the diameter of the circle is used as the particle size; if it is needle-like or rod-like, the minor axis is used as the particle size; otherwise, the equivalent circle diameter is calculated from the electron microscope image. The equivalent circle diameter is calculated as the positive square root of [4 x (particle area) / π]. The average primary particle size applies to silica, carbon black, etc.

[0057] "Acetone extractables (AE)" is a value calculated in accordance with JIS K 6229 by immersing each vulcanized rubber test piece in acetone at room temperature (approximately 25°C) for 72 hours to extract the soluble components, measuring the mass of each test piece before and after extraction, and then using the following formula. Acetone extractable amount (mass%) = {(mass of rubber test piece before extraction - mass of rubber test piece after extraction) / (mass of rubber test piece before extraction)} × 100

[0058] [tire] A tire according to one embodiment of the present invention will be described below with reference to the accompanying drawings. However, the drawings used merely illustrate one embodiment, and the present invention is not limited to these drawings.

[0059] The tire according to this embodiment is a tire comprising a tread portion having a rubber layer made of a predetermined rubber composition and a pair of sidewalls, wherein W is the thickness (mm) of the sidewall, Y is the total vinyl content (mol%) in the rubber component, and Dt is the tire outer diameter (mm) of the tire, and W≦4.0, Y≦30, and W, Y, and Dt satisfy the relationship of formula (1). (1) Y×W / Dt×100≦15

[0060] 1 is a cross-sectional view of a tire 1 according to this embodiment, taken along a plane including the tire rotation axis. The tire 1 has a tread portion 2 and a pair of sidewalls 3 disposed on both sides of the tread portion 2. The thickness W of the sidewalls is measured at the maximum tire width position. CL represents the tire centerline.

[0061] <Formula (1)> The right side of formula (1) is preferably 13, more preferably 10, even more preferably 8, even more preferably 7, even more preferably 6, even more preferably 4, even more preferably 3, even more preferably 2.

[0062] Regarding formula (1), Y can be adjusted by increasing or decreasing the vinyl content in the rubber component, and W can be adjusted by increasing or decreasing the thickness of the sidewall. Dt can also be adjusted by increasing or decreasing the tire's outer diameter. As Y or W increases, the value of the left side of formula (1) increases, and conversely, as they decrease, the value decreases. As Dt increases, the value of the left side of formula (1) decreases, and conversely, as they decrease, the value increases. By focusing on this relationship and adjusting Y, W, and Dt, the value of the left side of formula (1) can be adjusted.

[0063] Y (mol%) is 30 mol% or less, preferably less than 25 mol%, more preferably less than 20 mol%, even more preferably less than 14 mol%, even more preferably less than 12 mol%, and even more preferably less than 6 mol%. As described above, if the total vinyl content is small, the vinyl domains also become small, allowing the polymer to move flexibly, which is thought to improve microscopic road conformability and ride comfort.

[0064] Dt is preferably 585 mm or more, more preferably 600 mm or more, even more preferably 625 mm or more, and even more preferably 655 mm or more. The tire outer diameter Dt is preferably less than 843 mm, more preferably less than 725 mm, and even more preferably less than 685 mm.

[0065] W is preferably 4.0 mm or less, more preferably 3.8 mm or less, even more preferably 3.5 mm or less, still more preferably 3.2 mm or less, still more preferably 3.0 mm or less, and still more preferably 2.8 mm or less. With regard to the lower limit of W, the necessary thickness is considered to be determined naturally from the viewpoint of the practicality of the tire, but from the viewpoint of durability, it is 1.0 mm or more, preferably 1.2 mm or more, more preferably 1.4 mm or more, even more preferably 1.6 mm or more, still more preferably more than 2.0 mm, and even more preferably more than 2.2 mm.

[0066] (Micro-ridge forming 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.

[0067] 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.

[0068] 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.

[0069] (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 fuel economy or ride comfort of the tire, and specific examples include a columnar shape, a frustum shape, a rib shape (stripe shape), etc. Examples of columnar shapes include cylindrical shapes as well as polygonal prism shapes such as triangular prisms, square prisms, and pentagonal prisms. Examples of frustum shapes include circular frustum shapes as well as 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.

[0070] FIG. 2 shows a portion of a microridge-formed portion in which cylindrical microridges 12 are formed on the sidewall outer surface 11. FIG. 3 shows a portion of a microridge-formed portion in which 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, in which the microridges are 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 in which 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, in which the microridges are 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.

[0071] 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.

[0072] 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 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 5.00 mm or less, and may be 3.00 mm or less, 1.00 mm or less, or 0.50 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 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.

[0073] It is preferable that 20 or more micro-ridges are formed in at least one direction, and the micro-ridge formation portion is 10 mm 2 It is preferable that the area be equal to or larger than this, because this can suppress stress concentration on the outer surface of the sidewall and contribute to improving the crack resistance of the sidewall.

[0074] 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.

[0075] The micro-ridges preferably have arc-shaped depressions on their outermost surfaces, such as micro-ridge 14 shown in Fig. 5. This configuration can prevent air from accumulating in the arc-shaped depressions, thereby preventing the micro-ridges from having poor appearance.

[0076] (tread area) In this embodiment, the tread portion has at least one rubber layer. The rubber layer may be formed of a single rubber layer, or may have one or more rubber layers radially inward of a rubber layer (also referred to as a first layer or a cap rubber layer) whose outer surface constitutes the tread surface. When the tire is formed of two or more rubber layers, it is sufficient that at least one of the two or more rubber layers is formed of the above-mentioned specified rubber composition, and it is preferable to use the above-mentioned specified rubber composition for the cap rubber layer.

[0077] (Total vinyl content in rubber component Y) As described above, Y (mol %) is 30 mol % or less, preferably less than 20 mol %, more preferably less than 14 mol %, even more preferably less than 12 mol %, and even more preferably less than 6 mol %.

[0078] (Total amount of styrene in rubber component) The total styrene content (mass%) of the rubber component is the total content of styrene moieties contained in 100% by mass of the rubber component, and is calculated by multiplying the styrene content (mass%) of each rubber component by the mass fraction in the rubber component, and then adding up the values ​​obtained. In this embodiment, the total styrene content in the rubber component is preferably less than 27% by mass, more preferably less than 23% by mass, even more preferably less than 15% by mass, even more preferably 11% by mass or less, and even more preferably 10% by mass or less.

[0079] (Acetone extractable amount) The acetone extractable amount is an index of the concentration of organic low-molecular-weight compounds in the plasticizer contained in the vulcanized rubber composition. The acetone extractable amount can be determined by the above-mentioned measurement method. The acetone extractable amount of the rubber composition is, for example, preferably 15% by mass, 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, and even more preferably 35% by mass or more. The acetone extractable amount is preferably less than 70% by mass, more preferably less than 65% by mass, even more preferably less than 60% by mass, and even more preferably less than 55% by mass. When the acetone extractable amount is the above-mentioned predetermined amount, the dispersibility of the polymer and silica is improved, and therefore fuel economy is thought to be improved.

[0080] [Rubber composition] The rubber composition includes a rubber component containing 50% by mass or more of styrene-butadiene rubber based on 100% by mass of the rubber component, and also includes 50 parts by mass or more of silica based on 100 parts by mass of the rubber component.

[0081] <Rubber component> The rubber component may contain other rubber components in addition to styrene-butadiene rubber (SBR). Examples of such rubber components include crosslinkable rubber components commonly used in the tire industry, such as diene rubbers (e.g., isoprene-based rubber (IR-based rubber), butadiene rubber (BR), styrene-isoprene-butadiene copolymer rubber (SIBR), styrene-isobutylene-styrene block copolymer (SIBS), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR), as well as non-diene rubbers (e.g., hydrogenated nitrile rubber (HNBR), butyl rubber (IIR), ethylene-propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. These rubber components may be used alone or in combination.

[0082] The rubber component preferably contains at least one of an IR rubber and a BR in addition to SBR, but may also contain an IR rubber and a BR. The rubber component may also consist of SBR, an isoprene rubber, and a BR, or may consist of only SBR.

[0083] (SBR) There are no particular limitations on the SBR, and either solution-polymerized SBR (S-SBR) or emulsion-polymerized SBR (E-SBR) can be suitably used. However, from the viewpoints of fuel economy and ride comfort, S-SBR is preferred. Furthermore, modified SBRs (modified S-SBR, modified E-SBR) can also be used. Examples of modified SBRs include SBRs whose terminals and / or main chains are modified, and modified SBRs (condensates, those with branched structures, etc.) coupled with tin, silicon compounds, etc. One type of SBR may be used alone, or two or more types may be used in combination.

[0084] As the SBR, either oil-extended or non-oil-extended SBR can be used. SBR commercially available from JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Corporation, Asahi Kasei Corporation, ZS Elastomers Co., Ltd., ARLANXEO, LG Chem, etc. can be used.

[0085] From the viewpoint of the effects of the present invention, the styrene content of SBR is preferably more than 5% by mass, more preferably more than 8% by mass, further preferably 10% by mass or more, and even more preferably 15% by mass or more, and is preferably less than 50% by mass, more preferably less than 45% by mass, and further preferably less than 40% by mass. The styrene content of SBR is measured by the above-mentioned measurement method.

[0086] From the viewpoint of the effects of the present invention, the vinyl content of SBR is preferably more than 3 mol%, more preferably more than 5 mol%, even more preferably more than 8 mol%, and preferably 10 mol% or more. Also, it is preferably less than 55 mol%, more preferably less than 50 mol%, and even more preferably less than 45 mol%. The vinyl content of SBR is measured by the above-mentioned measurement method.

[0087] From the viewpoints of fuel economy and ride comfort, the glass transition point (Tg) of SBR is preferably higher than −85° C., more preferably higher than −80° C., and even more preferably higher than −75° C., and is preferably lower than −10° C., more preferably lower than −15° C., and even more preferably lower than −20° C. The Tg of SBR is measured by the above-mentioned measurement method.

[0088] The weight average molecular weight (Mw) of SBR is preferably 100,000 or more, more preferably 150,000 or more, and even more preferably 190,000 or more, from the viewpoint of fuel economy and ride comfort. Furthermore, from the viewpoint of crosslink uniformity, Mw is preferably 2,500,000 or less, and more preferably 2,000,000 or less. The Mw of SBR is measured by the above-mentioned measurement method.

[0089] From the viewpoints of fuel economy and ride comfort, the content of SBR in the rubber component is preferably 50% by mass or more, more preferably more than 55% by mass, and even more preferably 60% by mass or more. The content may be 100% by mass, but is preferably less than 95% by mass, more preferably less than 90% by mass, and even more preferably less than 85% by mass.

[0090] (Isoprene rubber) Examples of isoprene-based rubbers that can be used include those commonly used in the tire industry, such as isoprene rubber (IR) and natural rubber. Natural rubber includes unmodified natural rubber (NR) as well as modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), highly purified natural rubber (UPNR), and grafted natural rubber. These isoprene-based rubbers may be used alone or in combination of two or more.

[0091] The NR is not particularly limited, and those commonly used in the tire industry can be used, such as SIR20, RSS#3, and TSR20.

[0092] The content of the isoprene-based rubber in the rubber component is, for example, 10% by mass or more, preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and still more preferably 40% by mass or more, and preferably less than 80% by mass, more preferably less than 75% by mass, even more preferably less than 70% by mass, and still more preferably less than 65% by mass.

[0093] (BR) The BR is not particularly limited, and can be one commonly used in the tire industry, such as BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare earth butadiene rubber (rare earth BR) synthesized using a rare earth catalyst, BR containing syndiotactic polybutadiene crystals (SPB-containing BR), or modified BR (high-cis modified BR, low-cis modified BR). One type of BR may be used alone, or two or more types may be used in combination.

[0094] As the high-cis BR, for example, commercially available products from Zeon Corporation, UBE Corporation, JSR Corporation, etc. can be used. The inclusion of high-cis BR can improve low-temperature properties and wear resistance. The cis content of the high-cis BR is preferably more than 90 mol%, more preferably more than 95 mol%, and even more preferably 96 mol% or more. The cis content of BR is measured by the above-mentioned measurement method.

[0095] The rare earth BR is synthesized using a rare earth catalyst and has a vinyl content of preferably less than 1.8 mol%, more preferably less than 1.5 mol%, and even more preferably less than 1.2 mol%, and a cis content of preferably more than 90 mol%, more preferably more than 95 mol%, and even more preferably 96 mol% or more. As the rare earth BR, for example, commercially available products from LANXESS K.K. can be used.

[0096] The SPB-containing BR is not simply 1,2-syndiotactic polybutadiene crystals dispersed in the BR, but is dispersed after being chemically bonded to the BR. As such SPB-containing BR, commercially available products from UBE Corporation and the like can be used.

[0097] Examples of modified BR include BR modified with functional groups similar to those described above for SBR, and also preferably used are modified butadiene rubbers (modified BRs) whose terminals and / or main chains are modified with functional groups containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen.

[0098] Other examples of modified BR include tin-modified BR, which is obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and in which the terminals of the modified BR molecule are further bonded with a tin-carbon bond (tin-modified BR).Modified BR may be either non-hydrogenated or hydrogenated.

[0099] The weight-average molecular weight (Mw) of the BR is preferably more than 300,000, more preferably more than 350,000, and even more preferably more than 400,000. From the viewpoint of crosslink uniformity, it is preferably less than 2,000,000, more preferably less than 1,000,000, and even more preferably less than 700,000. The Mw of the BR can be determined by the above-mentioned method.

[0100] The content of BR in the rubber component is not particularly limited, but is preferably more than 3% by mass, more preferably more than 5% by mass, even more preferably more than 7% by mass, and even more preferably 10% by mass or more. The content of BR in the rubber component is preferably less than 50% by mass, more preferably less than 45% by mass, even more preferably less than 40% by mass, and even more preferably less than 35% by mass.

[0101] (Rubber components synthesized from recycled and biomass-derived raw materials) Monomers, which are structural units of synthetic rubbers such as IR, SBR, and BR, may be derived from underground resources such as petroleum and natural gas, or may be recycled from rubber products such as tires or non-rubber products such as polystyrene. Monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl compounds. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds include, but are not limited to, styrene. Among these, recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) are preferably used as raw materials.

[0102] 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.

[0103] Furthermore, the monomers that are the structural units of polymers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to materials derived from natural resources such as plants. Examples of biomass include, but are not limited to, agricultural, forestry, and fishery products, sugar, wood chips, plant residues after useful components have been extracted, plant-derived ethanol, and biomass naphtha.

[0104] Monomers derived from biomass (biomass monomers) are not particularly limited, and examples thereof include biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds include, but are not limited to, styrene. The method for producing biomass monomers is not particularly limited, and examples include biological and / or chemical and / or physical conversion of animals and plants. A representative example of biological conversion is fermentation by microorganisms, and examples of chemical and / or physical conversion include catalytic conversion, high heat conversion, high pressure conversion, electromagnetic wave conversion, critical fluid conversion, and combinations thereof.

[0105] 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 compounds, etc. Examples of the aromatic vinyl / butadiene copolymers include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0106] Whether a polymer's raw material is biomass-derived can be determined by its pMC (percent modern carbon) measured in accordance with ASTM D6866-10. pMC is the modern standard reference carbon. 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.

[0107] 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. 14The half-life of C is 5730 years, 14 C is decreasing regularly. Therefore, in the case of fossil fuels such as coal, oil, and natural gas, which are thought to have been absorbed and fixed by plants and other organisms more than 226,000 years ago, C was also included in these when they were first fixed. 14 All C elements have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas contain 14 Therefore, chemicals produced from these fossil fuels do not contain any C element. 14 It does not contain any C elements.

[0108] on the other hand, 14 C is constantly produced by cosmic rays undergoing nuclear reactions in the atmosphere. 14 The amount of C is balanced between radioactive decay and nuclear reaction, and in the Earth's atmospheric environment, 14 Therefore, the amount of carbon derived from biomass resources currently circulating in the environment is constant. 14 As mentioned above, the C concentration is approximately 1 × 10 -12 The value is approximately mol %. Therefore, the biomass ratio in a compound can be calculated by using the difference between these values.

[0109] 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. 14The specific standard substance used is the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific activity of carbon in this oxalic acid (per gram of carbon) is 14 The radioactivity of C) is separated into carbon isotopes, 13 The standard value is the value corrected for decay from 1950 to the measurement date. 14 This is used as the C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value.

[0110] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, it will usually not reach 100 under normal conditions, so it will show a value of approximately 110 pMC. On the other hand, for chemical substances derived from petroleum and other fossil fuels, 14 When the carbon concentration is measured, it will show a value of about 0 pMC (for example, 0.3 pMC), which corresponds to the biomass ratio of 0% mentioned above.

[0111] 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.

[0112] <Filler> The filler contains silica in an amount of 50 parts by mass or more per 100 parts by mass of the rubber component. The filler may further contain carbon black. The filler may contain fillers other than silica and carbon black, but may also be a filler consisting only of silica and carbon black.

[0113] The fillers other than silica and carbon black are not particularly limited, but may include, for example, aluminum hydroxide, calcium carbonate, alumina, clay, talc, and the like, which have been conventionally used in the tire industry.

[0114] The filler may be used alone or in combination of two or more kinds.

[0115] (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 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 a silica-containing product. Among these, hydrated silica prepared by a wet method is preferred because it contains a large number of silanol groups. Silica can be used alone or in combination of two or more types.

[0116] 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.

[0117] 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.

[0118] 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).

[0119] Amorphous silica extracted from rice husks may be commercially available from Wilmar Co., Ltd., etc.

[0120] The nitrogen adsorption specific surface area (N2SA) of silica is 130m 2 / g or more is preferable, and 150m 2 / g is more preferable, and 170m 2 / g or more is more preferable, and 175m 2 / g or more is more preferable, and 185m 2 / g or more is more preferable, and 195m 2 / g. In addition, from the viewpoint of processability, N2SA is more preferably 500m 2 / g or less is preferable, and 350m 2 / g is more preferable, and 300m 2 / g is more preferable, and 250m 2 / g or less is more preferable. The N2SA of silica is a value measured by the above-mentioned measurement method.

[0121] From the viewpoint of the effects of the present invention, the average primary particle diameter of silica is preferably less than 18 nm, more preferably less than 17 nm, and even more preferably less than 16 nm. Also, from the viewpoint of processability, the average primary particle diameter is preferably greater than 12 nm, more preferably greater than 13 nm, and even more preferably greater than 14 nm. The average primary particle diameter of silica is measured by the above-mentioned measurement method.

[0122] The amount of silica per 100 parts by mass of the rubber component is 50 parts by mass or more, preferably 60 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 75 parts by mass or more, even more preferably 95 parts by mass or more, and still more preferably 100 parts by mass or more. The amount is preferably less than 160 parts by mass, more preferably less than 150 parts by mass, even more preferably less than 130 parts by mass, and still more preferably less than 125 parts by mass.

[0123] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent.Silane coupling agent is not particularly limited, but for example, sulfide-based silane coupling agent such as bis(3-triethoxysilylpropyl) disulfide, bis(3-triethoxysilylpropyl) tetrasulfide; mercapto group-containing silane coupling agent such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agent such as vinyltriethoxysilane, vinyltrimethoxysilane; 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane Examples of suitable silane coupling agents include amino-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, sulfide-based silane coupling agents and / or mercapto-containing silane coupling agents are preferred. Mercapto-containing silane coupling agents are particularly preferred. Examples of suitable silane coupling agents include those commercially available from Evonik Degussa and Momentive. These silane coupling agents may be used alone or in combination.

[0124] The content of the silane coupling agent relative to 100 parts by mass of silica is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and even more preferably 8 parts by mass or more, from the viewpoint of improving the dispersibility of silica. Also, from the viewpoint of cost and processability, it is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and even more preferably 16 parts by mass or less.

[0125] (carbon black) Carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N660, 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 black products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These carbon blacks may be used alone or in combination.

[0126] In addition to the above, from the viewpoint of life cycle assessment, recycled carbon black obtained by pyrolyzing and purifying products containing carbon black, such as tires, may also be used as the carbon black.

[0127] "Recycled carbon black" refers to carbon black obtained by crushing used tires or other products containing carbon black and calcining the crushed material, and refers to carbon black in which, when subjected to oxidative combustion by heating in air as measured by thermogravimetry in accordance with JIS K 6226-2:2003, the proportion of ash (the mass of the non-combustible component) is 13% by mass or more. In other words, the proportion of the mass of the recycled carbon black lost due to oxidative combustion (carbon mass) is 87% by mass or less. Recycled carbon black is also called recovered carbon black and is sometimes expressed as rCB.

[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, in European Patent Application Publication No. 3,173,251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Furthermore, in Japanese Patent Publication No. 6,856,781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol or disulfide group to obtain surface-activated carbon black. The recycled carbon black of this embodiment also includes carbon blacks treated to include functional groups on their surfaces.

[0130] As the recycled carbon black, commercially available products from Strable Green Carbon, LD Carbon, etc. can be used.

[0131] The nitrogen adsorption specific surface area (N2SA) of carbon black is 50m from the viewpoint of weather resistance and reinforcement. 2 / g or more is preferable, and 80m2 / g is more preferable, and 100m 2 In addition, N2SA is more preferably 250m / g or more in terms of dispersibility, fuel efficiency, breakage characteristics and durability. 2 / g or less is preferable, and 220m 2 / g is more preferable, and 180m 2 / g is more preferable, and 150m 2 The N2SA of carbon black is measured by the above-mentioned measurement method.

[0132] From the viewpoints of weather resistance and reinforcing properties, the average primary particle diameter of carbon black is preferably greater than 12 nm, more preferably greater than 15 nm, and even more preferably greater than 17 nm. Furthermore, from the viewpoints of dispersibility, fuel economy, breakage characteristics, and durability, the average primary particle diameter is preferably less than 30 nm, more preferably less than 25 nm, and even more preferably 22 nm or less. The average primary particle diameter of carbon black is measured by the above-mentioned measurement method.

[0133] The amount of carbon black 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 5 parts by mass or more, and is preferably less than 40 parts by mass, more preferably less than 30 parts by mass, even more preferably less than 20 parts by mass, and even more preferably less than 10 parts by mass.

[0134] <Silica dispersant> The rubber composition preferably contains a silica dispersant. Examples of the silica dispersant include a compound represented by the following formula (I). The compound represented by formula (I) may be used alone or in combination of two or more. [ka] (In the formula, the symbols have the same meanings as defined above.)

[0135] R 1 ~R 3The hydrocarbon group may be linear, branched, or cyclic, and examples thereof include aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. Of these, aliphatic hydrocarbon groups are preferred. The number of carbon atoms in the hydrocarbon group is preferably 1 or more, more preferably 5 or more, even more preferably 8 or more, and particularly preferably 12 or more, and is preferably 30 or less, more preferably 25 or less, even more preferably 22 or less, and particularly preferably 20 or less. Within the above ranges, the effects tend to be more favorably obtained.

[0136] Examples of the aliphatic hydrocarbon group include an alkyl group, an alkylene group, an alkenyl group, an alkenylene group, an alkynyl group, and an alkynylene group. Among these, an alkyl group having the above-mentioned number of carbon atoms is preferable. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, and an octadecyl group.

[0137] The alicyclic hydrocarbon group is preferably one having 3 to 8 carbon atoms, and specific examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, and a cyclooctenyl group.

[0138] The aromatic hydrocarbon group preferably has 6 to 10 carbon atoms, and specific examples thereof include a phenyl group, a benzyl group, a phenethyl group, a tolyl group, a xylyl group, a naphthyl group, etc. In the tolyl group and the xylyl group, the substitution position of the methyl group on the benzene ring may be any of the ortho, meta, and para positions.

[0139] R 2 and R 3 In - (AO) nThe -H group (where the symbols have the same meanings as above) AO represents an oxyalkylene group having two or more carbon atoms, which may be linear or branched. The number of carbon atoms in the oxyalkylene group is preferably three or more, and although there is no particular upper limit, it is preferably seven or less, more preferably six or less, and even more preferably five or less. For reasons of more optimally achieving the desired effect, AO is preferably a group in which a hydrocarbon chain having one to six carbon atoms is bonded to an oxyalkylene group having two to three carbon atoms (i.e., an oxyethylene group or an oxypropylene group).

[0140] n is an integer of 1 or more, preferably 2 or more, and is preferably an integer of 20 or less, more preferably 16 or less, even more preferably 10 or less, even more preferably 5 or less, and even more preferably 3 or less. Within the above range, the effect tends to be more suitably obtained.

[0141] Specific examples of the compound represented by formula (I) include liponols (R 2 -(CH2CH2O) x -H and R 3 -(CH2CH2O) y -H, and x and y are the same or different and are integers of 1 or more). These may be used alone or in combination of two or more. As the compound represented by formula (I), the commercially available products may be used, or a compound produced separately from these commercially available products may be used. As a production method, for example, a method of reacting an alkylene oxide with a polyvalent amine compound in the presence or absence of a catalyst may be considered, but the production method is not limited to this method.

[0142] The content of the compound represented by formula (I) (the total content when two or more types are used in combination) is preferably more than 0.1 part by mass, more preferably more than 0.5 part by mass, even more preferably more than 1.0 part by mass, and still more preferably more than 2.0 parts by mass, per 100 parts by mass of the rubber component. Furthermore, the content is preferably less than 10.0 parts by mass, more preferably less than 8.0 parts by mass, and still more preferably less than 6.0 parts by mass, per 100 parts by mass of the rubber component. When the content is within the above range, the effects can be more suitably obtained.

[0143] <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.

[0144] 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.

[0145] (resin) Among the other compounding ingredients, the rubber composition preferably contains a resin. The resin is not particularly limited, but examples include adhesive resins commonly used in the tire industry, such as dicyclopentadiene-based resins, aromatic vinyl-based resins, dicyclopentadiene-based resins, C9-based resins, C5-based resins, C5C9-based resins, terpene-based resins, rosin-based resins, and phenol-based resins. Of these, aromatic vinyl-based resins, dicyclopentadiene-based resins, C9-based resins, and terpene-based resins are preferred. The resins may be used alone or in combination of two or more.

[0146] <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.

[0147] <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.

[0148] <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.

[0149] <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.

[0150] <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.

[0151] <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.

[0152] <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.

[0153] <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.

[0154] ≪Content≫ The amount of resin per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 5 parts by mass, and even more preferably 5 parts by mass or more, while from the viewpoint of suppressing heat buildup, the amount is preferably less than 60 parts by mass, more preferably less than 30 parts by mass, and even more preferably less than 20 parts by mass.

[0155] (Plasticizers other than resins) Plasticizers other than resins, such as oil, liquid rubber, and ester-based plasticizers, will now be explained.

[0156] <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.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] Examples of animal oils include fish oil, beef tallow, whale oil, and oleyl alcohol derived from these.

[0165] When oil is contained, the content per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, from the viewpoint of processability. Also, from the viewpoints of fuel economy and ride comfort, the content is preferably 100 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 30 parts by mass or less. The oil content includes the amount of oil contained in the oil-extended rubber.

[0166] <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.

[0167] When liquid rubber is contained, the content per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. The content of liquid rubber is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 10 parts by mass or less. The content of liquid rubber includes the amount of extended liquid rubber used to extend the rubber component.

[0168] <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.

[0169] When an ester plasticizer is contained, the content per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. The content of the liquid rubber is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 10 parts by mass or less. The content of the ester plasticizer includes the amount of the extending ester plasticizer used to extend the rubber component.

[0170] <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. One type of vulcanized rubber particle may be used alone, or two or more types may be used in combination.

[0171] The vulcanized rubber particles are not particularly limited and may be unmodified or modified. Commercially available vulcanized rubber products include those from Lehigh Industries, Muraoka Rubber Industries, and the like.

[0172] When vulcanized rubber particles are contained, the content thereof relative to 100 parts by mass of the rubber component can be appropriately adjusted, for example, within the range of more than 1 part by mass and less than 80 parts by mass.

[0173] (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.

[0174] 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.

[0175] (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.

[0176] When wax is contained, the content thereof per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass and more preferably more than 1.0 part by mass from the viewpoint of weather resistance of the rubber, and is preferably less than 10 parts by mass and more preferably less than 5.0 parts by mass from the viewpoint of preventing whitening of the tire due to bloom.

[0177] (stearic acid) When stearic acid is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of processability, and is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of vulcanization rate.

[0178] (zinc oxide) When zinc oxide is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of processability, and is preferably less than 8.0 parts by mass, more preferably less than 5.0 parts by mass, and even more preferably 4.5 parts by mass or less, and even more preferably 4.0 parts by mass or less from the viewpoint of abrasion resistance.

[0179] (anti-aging agent) The antioxidant is not particularly limited, and examples thereof include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditolyl-p-phenylenediamine. p-phenylenediamine antioxidants such as N-isopropyl-N'-phenyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products that can be used include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and Flexis Co., Ltd. One type of antioxidant may be used alone, or two or more types may be used in combination.

[0180] When an antioxidant is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, from the viewpoint of ozone crack resistance of the rubber, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoint of abrasion resistance and wet grip performance.

[0181] (vulcanizing agent) Sulfur is preferably used as the vulcanizing agent. Examples of sulfur that can be used include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. The vulcanizing agent may be used alone or in combination of two or more.

[0182] When sulfur is contained as a vulcanizing agent, the content per 100 parts by mass of the rubber component is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, the content is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. When oil-containing sulfur is used as the vulcanizing agent, the content of the vulcanizing agent is the total content of pure sulfur contained in the oil-containing sulfur.

[0183] Known organic crosslinking agents can also be used as vulcanizing agents other than sulfur. The organic crosslinking agent is not particularly limited as long as it can form crosslinked chains other than polysulfide bonds. Examples of the organic crosslinking agent include alkylphenol-sulfur chloride condensate, sodium 1,6-hexamethylene-dithiosulfate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, and dicumyl peroxide. 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane is preferred. These organic crosslinking agents can be commercially available from Taoka Chemical Co., Ltd., Lanxess K.K., Flexis, and other companies. The vulcanizing agent may be used alone or in combination of two or more kinds.

[0184] (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.

[0185] Examples of sulfenamide vulcanization accelerators include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), etc. Among these, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) is preferred.

[0186] 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.

[0187] 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, 1,3-di-o-cumenyl-2-propionylguanidine, etc. Among these, 1,3-diphenylguanidine (DPG) is preferred.

[0188] 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.

[0189] 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.

[0190] 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).

[0191] When a vulcanization accelerator is contained, the content thereof per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more. The content thereof per 100 parts by mass of the rubber component is preferably 8 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 6 parts by mass or less. By setting the content of the vulcanization accelerator within the above range, breaking strength and elongation tend to be ensured.

[0192] <Various materials containing carbon atoms> In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. The various materials may be obtained from carbon dioxide by directly converting carbon dioxide or by converting methane obtained through a methanation process in which methane is synthesized from carbon dioxide.

[0193] [Manufacturing method] The rubber composition can be produced by a known method, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll or an internal kneader (such as a Banbury mixer or kneader).

[0194] The kneading step includes, for example, a base kneading step in which compounding ingredients and additives other than the vulcanizing agent and vulcanization accelerator are kneaded, and a final kneading (F kneading) step in which the vulcanizing agent and vulcanization accelerator are added to the kneaded product obtained in the base kneading step and kneaded. Furthermore, the base kneading step can be divided into multiple steps as desired.

[0195] The kneading conditions are not particularly limited, but examples include a method in which the base kneading step involves kneading for 3 to 10 minutes at a discharge temperature of 150 to 170°C, and in the final kneading step, kneading for 1 to 5 minutes at 70 to 110°C.

[0196] The tire according to the present embodiment can be manufactured by a conventional method using the rubber composition. That is, the unvulcanized rubber composition is extruded to match the shape of the tread using an extruder equipped with a die of a predetermined shape, and then laminated together with other tire components in a tire building machine while adjusting to obtain a predetermined tire structure, and molded by a conventional method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in a vulcanizer, whereby the tire can be manufactured. The vulcanization conditions are not particularly limited, and examples thereof include a method of vulcanizing at 140 to 170°C for 10 to 40 minutes.

[0197] [Application] In this specification, the term "tire" refers to a tire that can be used for any purpose, regardless of whether it is a pneumatic tire or a non-pneumatic tire, and can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a racing tire, a motorcycle tire, a heavy-duty tire, or a run-flat tire. Passenger car tires are tires designed to be mounted on four-wheeled vehicles and have a maximum load capacity of less than 1,400 kg. Heavy-duty tires are tires with a maximum load capacity of 1,400 kg or more. In this specification, the term "tire" refers to all-season tires, summer tires, and winter tires such as studless tires. [Example]

[0198] Below, examples (working examples) that are considered preferable for carrying out the present invention are shown, but the scope of the present invention is not limited to these working examples. According to each table, rubber layers including tread surfaces obtained using the various chemicals shown below, and tires having tire structures were examined, and the results calculated based on the evaluation methods below are shown at the bottom of each table.

[0199] [Various medicines] The various chemicals used in the examples and comparative examples are listed below. NR:TSR20 SBR1: SBR produced by Production Example 1 below (styrene content: 38% by mass, vinyl content: 31% by mole, Tg: −25° C., Mw: 2,000,000, non-oil extended) SBR2: HPR840 manufactured by JSR Corporation (S-SBR, styrene content: 10% by mass, vinyl content: 41% by mole, Tg: -60°C, non-oil extended) SBR3: F1810 manufactured by LG Chem (S-SBR, styrene content: 18% by mass, vinyl content: 10% by mole, Tg: -73°C, non-oil extended) BR: UBEPOL-BR360B (high cis BR, cis 1,4-bond content: 98%, Mw: 570,000) manufactured by UBE Corporation Silica dispersant: Liponol HT / 14 manufactured by Lion Specialty Chemicals Co., Ltd. CB (carbon black): Diablack N220 (N2SA114m) manufactured by Mitsubishi Chemical Corporation 2 / g, average primary particle diameter 22nm) Silica 1: Ultrasil VN3 (N2SA: 175 ml) manufactured by Evonik Degussa 2 / g, average primary particle diameter: 18nm) Silica 2: Ultrasil 9100GR (N2SA: 230 ml) manufactured by Evonik Degussa 2 / g, average primary particle diameter: 15nm) Coupling agent 1 (silane coupling agent): Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Coupling agent 2 (silane coupling agent): NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Antioxidant 1: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant 2: Nocrac RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Oil: NH70S (process oil) manufactured by Idemitsu Kosan Co., Ltd. Wax: Ozoace 0355 (paraffin wax) manufactured by Nippon Seiro Co., Ltd. Resin 1: Syltraxx 4401 (α-methylstyrene resin, softening point 85°C) manufactured by Arizona Chemical Company Resin 2: CSR6383 (DCPD / C9 resin) manufactured by CHEESHIN Stearic acid: Camellia stearic acid beads manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (powdered sulfur containing 5% oil) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccelaer D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0200] (Production Example 1: Production of SBR1) A nitrogen-purged autoclave reactor was charged with 600 mL of hexane, 75 g of 1,3-butadiene, 25 g of styrene, and 60 mL of tetrahydrofuran, and the mixture was stirred at 40°C. After adding 0.5 mL of a 0.1 mol / L n-butyllithium / hexane solution in 0.5 mL increments for scavenging, 4 mL of a 0.1 mol / L n-butyllithium / hexane solution was added, and the stirring speed was increased to 130 rpm and the jacket temperature to 80°C. GPC confirmed the formation of a polymer with a Mw of 2 million, and the solvent was removed by steam stripping. The mixture was then dried on a heated roll heated to 110°C to obtain SBR1.

[0201] [Examples and Comparative Examples] According to the compounding recipes shown in each table (Tables 2-1 to 3-2), chemicals other than sulfur and vulcanization accelerators were mixed in a 1.7 L closed-type Banbury mixer for 1 to 10 minutes until the discharge temperature reached 150 to 160°C, yielding a kneaded mixture. Next, sulfur and vulcanization accelerators 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 105°C, yielding an unvulcanized rubber composition. The resulting unvulcanized rubber composition was extruded using an extruder equipped with a predetermined die to conform to the shape of the rubber layer, including the tread surface. The resulting unvulcanized rubber composition was then bonded with other tire components while adjusting to obtain the desired tire structure, yielding an unvulcanized tire. The unvulcanized tire was then press-vulcanized for 35 minutes at 150°C to produce test tires (tire sizes: 245 / 45R18 (tire outer diameter Dt: 675 mm) and 225 / 60R18 (tire outer diameter Dt: 725 mm)).

[0202] Additionally, micro-ridges having the shape shown in Table 1 are provided on the outer surface of the sidewall. In the micro-ridge columns of Tables 2-1 to 3-2 below, "present" indicates that micro-ridges are provided on the outer surface of the sidewall. The micro-ridges are formed during press vulcanization using a mold equipped with side plates on which an engraving for forming the micro-ridges is engraved on the surface facing the micro-ridge forming portion. The shape of the micro-ridges is as follows: The height h (mm) is the height of the micro-ridge at the maximum width position of the tire.

[0203] [Table 1]

[0204] [evaluation] The results of measurements for each test tire by the following methods are recorded in the corresponding columns of the table below. Unless otherwise specified, each test tire is used after being brought into normal condition.

[0205] <Low fuel consumption performance> Using a rolling resistance tester, the rolling resistance coefficient (RRC) of each test tire is measured when it is run on a drum at a speed of 80 km / h with an internal pressure of 230 kPa and a load of 3.43 kN. The results are expressed as an index, with the reference comparative example being set at 100. The higher the value, the lower the rolling resistance of the tire.

[0206] (Ride comfort performance) Each new test tire is mounted on a designated vehicle and the vehicle is driven on a test course with a dry asphalt surface. The test driver evaluates ride comfort performance based on the feeling when driving straight, changing lanes, and accelerating and decelerating while driving at 80 km / h. The evaluation is performed using an integer value of 1 to 5, with a higher score indicating better ride comfort performance, and the total score of the 20 test drivers is calculated based on the evaluation criteria. The evaluation results of each test tire are expressed as an index, with the total score of the reference comparison example being 100. The higher the number, the better the ride comfort.

[0207] [Table 2]

[0208] [Table 3]

[0209] [Table 4]

[0210] [Table 5]

[0211] [Embodiment] Examples of embodiments of the present invention are given below.

[0212] [1] A tire having a tread portion and a pair of sidewalls, the rubber composition constituting the tread portion includes a rubber component containing 50% by mass or more of styrene-butadiene rubber in 100% by mass of the rubber component, and includes 50 parts by mass or more, preferably 60 parts by mass or more, of silica per 100 parts by mass of the rubber component; The total vinyl content (mol%) in the rubber component is Y, The thickness (mm) of the sidewall is W, When the tire outer diameter (mm) of the tire is Dt, A tire in which Y≦30, W≦4.0, and W, Y, and Dt satisfy the relationship of formula (1). (1) Y×W / Dt×100≦15 Here, the right side of formula (1) is preferably 13, and more preferably 10. [2] The tire according to [1], wherein the rubber composition contains 30% by mass or more of isoprene-based rubber in 100% by mass of the rubber component. [3] The rubber composition further comprises a compound represented by general formula (I) [ka] (In the formula, R 1 represents a hydrocarbon group, and R 2 and R 3 is one of which is -(AO) n -H group (wherein n is an integer of 1 or more, and AO is an oxyalkylene group having 2 or more carbon atoms), and the other is a hydrogen atom, a hydrocarbon group, or -(AO) n -H group (where the symbols have the same meanings as above), and R 2 and R 3 Together - (AO) nWhen they are H groups, they may be the same or different. The tire according to [1] or [2], comprising a compound represented by the formula: [4] The tire according to any one of [1] to [3], wherein the content of the silica per 100 parts by mass of the rubber component is 70 parts by mass or more, preferably 75 parts by mass or more, and more preferably 95 parts by mass or more. [5] The tire according to any one of [1] to [4], wherein the acetone extractable amount of the rubber composition is 20% by mass or more, preferably 25% by mass or more. [6] The tire according to any one of [1] to [5], wherein the right side of formula (1) is 8, preferably 7, more preferably 6, and even more preferably 4. [7] The tire according to any one of [1] to [5], wherein the right side of formula (1) is 3. [8] The tire according to any one of [1] to [5], wherein the right side of formula (1) is 2. [9] The tire according to any one of [1] to [8], wherein the rubber composition contains silica in an amount of 100 parts by mass or more per 100 parts by mass of the rubber component.

[10] The tire according to any one of [1] to [9], wherein the rubber composition contains a silane coupling agent having a mercapto group.

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

[10] , wherein the rubber composition contains 40% by mass or more of an isoprene-based rubber relative to 100% by mass of the rubber component.

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

[11] , wherein the acetone extractable amount of the rubber composition is 30% by mass or more, preferably 35% by mass or more.

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

[12] , wherein the total amount of styrene in the rubber component is less than 27% by mass, preferably less than 23% by mass, more preferably less than 15% by mass, even more preferably 11% by mass or less, and even more preferably 10% by mass or less.

[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 5.0 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]

[0213] 1 tire 2 Tread section 3 Sidewall CL Tire centerline (equator) Dt Tire outer diameter W Sidewall thickness R rim 11 Sidewall outer surface 12 Microprotuberance 13 Microprotuberance 14 Microprotuberance w Maximum width of the micro-ridge d Micro-ridge spacing h Micro-ridge height

Claims

1. A tire having a tread portion and a pair of sidewalls, the rubber composition constituting the tread portion includes a rubber component containing 50% by mass or more of styrene-butadiene rubber per 100% by mass of the rubber component, and includes 50 parts by mass or more of silica per 100 parts by mass of the rubber component; The total vinyl content (mol%) in the rubber component is represented by Y, The thickness (mm) of the sidewall is W, When the tire outer diameter (mm) of the tire is Dt, A tire in which Y≦30, W≦4.0, and W, Y, and Dt satisfy the relationship of formula (1). (1) Y x W / Dt x 100 ≦ 15

2. The tire according to claim 1, wherein the rubber composition contains 30% by mass or more of an isoprene-based rubber based on 100% by mass of the rubber component.

3. The rubber composition further comprises a compound represented by general formula (I) 【Chemistry 1】 (In the formula, R 1 represents a hydrocarbon group, and R 2 and R 3 is one of which is -(AO) n -H group (wherein n is an integer of 1 or more, and AO is an oxyalkylene group having 2 or more carbon atoms), and the other is a hydrogen atom, a hydrocarbon group, or -(AO) n -H group (where the symbols have the same meanings as above), and R 2 and R 3 Together - (AO) n When they are —H groups, they may be the same or different.) 3. The tire of claim 1, comprising a compound represented by the formula:

4. The tire according to claim 1 or 2, wherein the content of the silica is 70 parts by mass or more per 100 parts by mass of the rubber component.

5. The tire according to claim 1 or 2, wherein the rubber composition has an acetone extractable amount of 20% by mass or more.

6. The tire according to claim 1 or 2, wherein the right side of formula (1) is 8.

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

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

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

10. The tire according to claim 1 or 2, wherein the rubber composition contains a silane coupling agent having a mercapto group.

11. The tire according to claim 1, wherein the rubber composition contains 40% by mass or more of an isoprene-based rubber relative to 100% by mass of the rubber component.

12. The tire according to claim 1 or 2, wherein the rubber composition has an acetone extractable amount of 30% by mass or more.

13. The tire according to claim 1 or 2, wherein the total amount of styrene in the rubber component is 10% by mass or less.

14. 3. The tire according to claim 1, 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 0.03 mm or greater and 5.0 mm or less.

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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