tire

Abstract

To provide a tire that can be improved in integrated performance of wear resistance performance and wet grip performance.SOLUTION: A tire comprises a tread part. The tread part has one or more circumferential grooves, and the tread part is constituted of rubber compositions containing rubber constituents and silica. The rubber constituents contain isoprene rubber and styrene-butadiene rubber. Contents of the isoprene rubber in the rubber constituents are 40 mass% or more. Styrene contents S1 (mass%) of the styrene-butadiene rubber are 30 or less. Contents of the silica with respect to 100 parts by mass of the rubber constituents are 80 parts by mass or more. Acetone extracted volumes AE (mass%) of the rubber compositions are more than 17.0 mass%. A half-width value of a peak in a range of -20°C to -70°C in a tanδ temperature distribution curve of the rubber compositions is 35°C or higher. When a complex elastic modulus at 30°C of the rubber compositions is defined as 30°CE* and a groove depth of a deepest part of the circumferential groove is defined as H (mm), 30°CE* / H is equal to 1.30 or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] Patent Document 1 describes that a tire tread and a tire with improved balance of wet grip performance, low rolling resistance, etc. are provided by a rubber composition for a tire containing a rubber component containing a conjugated diene polymer modified with a functional group having a skeleton derived from hexamethyleneimine and a modifier containing a specific compound, and a filler.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, further improvement in the wear resistance and wet grip performance of tires has been desired.

[0005] An object of the present invention is to provide a tire capable of improving the overall performance of wear resistance and wet grip performance.

Means for Solving the Problems

[0006] The present invention is a tire having a tread portion, wherein the tread portion has one or more circumferential grooves, the tread portion is composed of a rubber composition containing a rubber component and silica, the rubber component contains an isoprene-based rubber and a styrene-butadiene rubber, the content of the isoprene-based rubber in the rubber component is 40% by mass or more, The styrene content S1 (mass %) of the styrene-butadiene rubber is 30 or less, the content of the silica is 80 parts by mass or more with respect to 100 parts by mass of the rubber component, the acetone extraction amount AE (mass %) of the rubber composition is more than 17.0 mass %, the half-value width of the peak in the range of -20°C to -70°C in the tanδ temperature distribution curve of the rubber composition is 35°C or more, relates to a tire in which when the complex elastic modulus at 30°C of the rubber composition is 30°C E* and the groove depth at the deepest part of the circumferential groove is H (mm), 30°C E* / H is 1.30 or more.

Advantages of the Invention

[0007] According to the present invention, it is possible to improve the overall performance of wear resistance performance and wet grip performance.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0009] A tire according to an embodiment of the present invention is a tire having a tread portion. The tread portion has one or more circumferential grooves, and the tread portion is composed of a rubber composition containing a rubber component and silica. The rubber component contains an isoprene-based rubber and a styrene-butadiene rubber. The content of the isoprene-based rubber in the rubber component is 40% by mass or more. The styrene content S1 (% by mass) of the styrene-butadiene rubber is 30 or less. The content of the silica is 80 parts by mass or more with respect to 100 parts by mass of the rubber component. The acetone extraction amount AE (% by mass) of the rubber composition is more than 17.0% by mass. The half-value width of the peak in the range of -20°C to -70°C in the tanδ temperature distribution curve of the rubber composition is 35°C or more. When the complex elastic modulus at 30°C of the rubber composition is 30°C E* and the groove depth at the deepest part of the circumferential groove is H (mm), 30°C E* / H is 1.30 or more. This is the tire.

[0010] Regarding the reason why the overall performance of the wear resistance performance and the wet grip performance is improved in the tire of the present invention, although it is not intended to be restricted by theory, it is considered as follows.

[0011] The rubber composition constituting the tread portion of the tire of the present invention is as follows: (1) Since the content of the isoprene-based rubber is 40% by mass or more, a phase of the isoprene-based rubber having a certain size or more is formed in the rubber matrix, and an interface with the phases of other rubber components is generated, so that the input from the road surface during running can be relaxed, which contributes to the improvement of the wear resistance performance. Also, (2) By setting the styrene content S1 (% by mass) of the styrene-butadiene rubber to 30 or less, minute styrene domains are formed in the rubber matrix, and the minute domains move flexibly, so that the mobility of the entire polymer in the rubber composition is improved, and the followability of the rubber composition to the road surface is improved, thus improving the wet grip performance and the wear resistance performance. Also, (2) By setting the content of silica to 30 parts by mass or more, silica aggregates in the polymer phase, contributing to further improvement of the wet grip performance.

[0012] Further, in the rubber composition constituting the tread portion of the tire of the present invention, by setting the acetone extraction amount AE of the rubber composition to more than 17.0% by mass, a certain amount of plasticizer is contained in the rubber composition, the dispersibility of the filler is improved, and the distribution of the filler proceeds efficiently, so that the abrasion resistance performance and the wet grip performance are improved. Also, by setting the half-value width of the peak in the range of -20°C to -70°C in the tanδ temperature distribution curve to 35°C or more, energy loss can occur in a wide frequency band, and the input from the road surface can be released as heat even in the deformation speed region of the rubber crack pieces, so that crack growth can be suppressed and the abrasion resistance performance is improved. Furthermore, since energy loss can occur widely in the frequency band during wet braking, it contributes to further improvement of the wet grip performance.

[0013] In the tire of the present invention, by setting (6) 30°C E* / H to 1.30 or more, the block rigidity of the tread pattern becomes a certain level or more, which contributes to further improvement of the abrasion resistance performance. And it is considered that the above (1) to (6) cooperate to achieve the remarkable effect that the comprehensive performance of the abrasion resistance performance and the wet grip performance is improved.

[0014] The average primary particle diameter of the silica is preferably 18 nm or less. By reducing the particle diameter of the silica, the flexibility of the styrene domain is further improved, and it is considered that the wet grip performance and the abrasion resistance performance are further improved.

[0015] The rubber composition preferably contains a resin component containing dicyclopentadiene, styrene, and indene as monomer components. By containing the above resin component, the compatibility between the resin component and the isoprene-based rubber or styrene-butadiene rubber is improved, the dispersibility of the resin component in the polymer is improved, and it is considered that the abrasion resistance performance is further improved.

[0016] 30℃E* is preferably 8.0 MPa or more from the viewpoint of wear resistance. By setting 30℃E* within the above range, the rigidity of the rubber itself can be ensured to be a certain level or more, so it is considered that the wear resistance is further improved.

[0017] 30℃E* / H is preferably 1.30 or more from the viewpoint of wear resistance. By setting 30℃E* / H within the above range, the block rigidity of the tread pattern becomes a certain level or more, so it is considered that the wear resistance is further improved.

[0018] The total styrene amount S2 (mass%) in the rubber component is preferably 15 or less. By setting the total styrene amount S2 to 15 mass% or less, minute styrene domains are formed in the rubber matrix, and since these minute domains have flexibility, the mobility of the polymer is improved, the followability of the rubber composition to the road surface is improved, and it is considered that the comprehensive performance of wet grip performance and wear resistance is further improved.

[0019] When the total thickness of the tread part is T (mm), 30℃tanδ×T is preferably 2.5 or more and 4.5 or less. By setting 30℃tanδ×T within the above range, the hysteresis friction due to the deformation of the entire tread part is improved, so it is considered that the wet grip performance is further improved.

[0020] The rubber composition preferably contains 20 parts by mass or more of carbon black with respect to 100 parts by mass of the rubber component. By containing 20 parts by mass or more of carbon black, the filler and the polymer in the rubber component are firmly bonded, the polymer and the filler are fixed in the rubber composition, and the energy loss is reduced, so it is considered that the wear resistance is further improved.

[0021] It is preferable that S1×R be 11.0 or more. By setting S1×R to 11.0 or more, fine styrene domains formed are formed to a certain extent or more, the mobility of the entire polymer in the rubber composition is improved, and the followability of the road surface rubber composition to the road surface is improved. Therefore, it is considered that the overall performance of wet grip performance and wear resistance performance is further improved.

[0022] When the tire weight is G (kg), it is preferable that S1 / G be 3.0 or less. As the tire becomes lighter, the force pressing the tread portion against the road surface becomes smaller. Therefore, as the tire becomes lighter, even a slight aggregation of the styrene portion has a greater impact on the tread surface. It is considered that by reducing S1 as the tire weight decreases, stress concentration can be suppressed by the aggregation of the styrene portion, and the wear resistance performance can be improved.

[0023] The tread portion has a tread block defined by the one or more circumferential grooves, and the tread block has a lateral groove extending toward the inner side in the tire radial direction. It is preferable that at least one of the lateral grooves has a groove width wider than the groove width on the tread surface at the inner side in the tire radius direction.

[0024] By disposing the lateral grooves in the tread block, it is considered that an increase in compression rigidity can be suppressed even when wear progresses, and wet grip performance can be ensured.

[0025] On the tread surface of the tread portion, when a region of 30% of the tread contact width centered on the tire equator is defined as the center region, and regions on both outer sides of the center region and within the tread contact width are defined as a pair of shoulder regions, it is preferable that the groove depth at the deepest part of the circumferential grooves existing in the shoulder regions be 6.0 mm or more.

[0026] With the above configuration, drainage performance can be enhanced, which is considered to contribute to an improvement in wet grip performance.

[0027] When the thickness of the layer whose outer surface constitutes the tread surface of the tread part is t1 (mm) and the thickness of the belt layer is B (mm), it is preferable that B is 0.9 or more and 1.2 or less, and t1 / B is 7.0 or less.

[0028] By setting the thickness B of the belt layer to 0.9 mm or more, the rigidity of the tire is improved, so the wear resistance performance can be further improved. By setting it to 1.2 mm or less, the tire weight can be reduced, so it is considered that the low fuel consumption performance can be improved. By setting t1 / B to 7.0 or less, the thickness of the layer whose outer surface constitutes the tread surface can be made thinner, the rolling resistance can be reduced, and the grip performance can be improved.

[0029] [Definition] "Styrene content S1 (mass%) of styrene-butadiene rubber" is the styrene content (mass%) of styrene-butadiene rubber (SBR). When SBR is contained alone in the rubber component, it is the styrene content of that SBR. When a plurality of SBRs are contained in the rubber component, it is obtained by the sum of the product of the styrene content of each SBR and the blending amount (mass%) of that SBR when the total SBR is 100 mass%.

[0030] For example, when the rubber component consists of 20 mass% of the first SBR (styrene content: 25 mass%), 30 mass% of the second SBR (styrene content: 27.5 mass%), and 50 mass% of BR, the styrene content S1 of the styrene-butadiene rubber is 26.5 mass% (=(25×40 / 100)+(27.5×60 / 100)).

[0031] "Total styrene amount S2 (mass%) in the rubber component" is the total content (mass%) of the styrene part contained in 100 mass% of the rubber component. For each rubber component, a value obtained by multiplying the styrene content (mass%) by the mass fraction in the rubber component is calculated, and the sum of these values. Specifically, it is calculated by Σ (styrene content (mass%) of each styrene-containing rubber × content (mass%) of each styrene-containing rubber in the rubber component / 100).

[0032] For example, when the rubber component consists of 20% by mass of a first SBR (styrene content: 25% by mass), 30% by mass of a second SBR (styrene content: 27.5% by mass), and 50% by mass of BR, the total styrene amount S2 in 100% by mass of the rubber component is approximately 13.3% by mass (= (25 × 20 / 100) + (27.5 × 30 / 100) + (0 × 10 / 100)).

[0033] The "acetone extraction (AE) amount" is a value obtained by immersing each vulcanized rubber test piece in acetone at room temperature (around 25°C) for 72 hours in accordance with JIS K 6229:2015 to extract soluble components, measuring the mass of each test piece before and after extraction, and calculating using the following formula. Acetone extraction amount (mass%) = {(mass of rubber test piece before extraction - mass of rubber test piece after extraction) / (mass of rubber test piece before extraction)} × 100

[0034] The "half-width of the peak in the range of -20°C to -70°C in the tanδ temperature distribution curve of the rubber composition (half-width of the tanδ peak)" can be obtained from the temperature distribution curve of tanδ measured by the method disclosed in JP-A-2021-54377. That is, each vulcanized test piece is measured using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO) under the conditions of a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±0.5%, and a temperature increase rate of 2°C / min in the temperature range from -20°C to -70°C to measure the temperature distribution curve of tanδ, and a temperature dispersion curve with temperature on the X-axis and tanδ on the Y-axis is obtained. Let the tanδ at the peak position of the obtained temperature distribution curve be A, the intersection of the straight line parallel to the Y-axis passing through A and the X-axis be B, the midpoint of the line segment AB be C, the straight line parallel to the X-axis passing through C be D, and the two intersections of D and the temperature distribution curve be E and F. Then it is defined as the absolute value of the temperature difference between E and F.

[0035] "The tanδ at the peak position within the range of -20°C to -70°C in the tanδ temperature distribution curve of the rubber composition" can be obtained from the temperature distribution curve of tanδ measured by the method disclosed in Japanese Patent Application Laid-Open No. 2021-54377. That is, each vulcanized test piece is measured using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO) under the 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 in the temperature range from -20°C to -70°C. It is the tanδ at the peak position of the temperature dispersion curve with temperature on the X-axis and tanδ on the Y-axis.

[0036] "The glass transition temperature (Tg) of the rubber composition" means the temperature (tanδ peak temperature) corresponding to the maximum value within the range of -60°C or higher and 40°C or lower of the obtained temperature distribution curve by measuring the temperature distribution curve of tanδ using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO) under the 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. In the measurement within the range of -60 to 40°C, when the tanδ value continuously increases or decreases with the increase in temperature, the glass transition temperature of the rubber composition is 40°C or -60°C, respectively. Also, when there are two or more points showing a maximum value within the range of -60°C or higher and 40°C or lower, the point with the lowest temperature is taken as the glass transition temperature.

[0037] "The tanδ at 30°C" is the loss tangent measured under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and an elongation mode using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO). The sample for measuring the tanδ at 30°C is a vulcanized rubber composition with a length of 20 mm × a width of 4 mm × a thickness of 1 mm. When it is prepared by cutting from a tire, it is cut out from the tread part such that the tire circumferential direction is the long side and the tire radial direction is the thickness direction.

[0038] "30°C E*" is the complex elastic modulus measured under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and an elongation mode using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO). The sample for this measurement is prepared in the same manner as in the case of 30°C tanδ.

[0039] The "tread portion" is the portion that forms the ground contact surface of the tire. In the radial cross-section of the tire, when it includes members that form the tire skeleton with steel or textile materials such as a belt layer, a belt reinforcing layer, and a carcass layer, it is the member on the outer side in the tire radial direction of those.

[0040] The "normal state" is a no-load state in which the tire is mounted on a normal rim and filled with air at a normal internal pressure.

[0041] The "dimensions of each part of the tire" are, unless otherwise specified, values specified in the normal state for those that appear on the outer surface of the tire. On the other hand, those existing inside the tire or on the tire cut surface are values specified in a state where the cut tire piece is held in the rim width of the normal rim, for example, by cutting the tire with a plane including the tire rotation axis.

[0042] The "regular rim" is the rim defined for each tire in the standard system including the standards on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it refers to the "standard rim" in the applicable sizes described in the "Jatma Year Book"; in the case of ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" described in the "STANDARDS MANUAL"; in the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" described in the "YEAR BOOK". Refer to JATMA, ETRTO, and TRA in this order, and follow the relevant standard if there is an applicable size during the reference. In the case of a tire not defined in the above standards, it refers to the rim with the narrowest width among the rims with the minimum diameter that can be assembled with the tire and can maintain the internal pressure (i.e., does not cause air leakage between the rim and the tire).

[0043] The "regular inflation pressure" is the air pressure defined for each tire in the standard system including the standards on which the tire is based. For example, in the case of JATMA, it refers to the "maximum air pressure"; in the case of ETRTO, it refers to the "INFLATION PRESSURE"; in the case of TRA, it refers to the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Similar to the case of the regular rim, refer to JATMA, ETRTO, and TRA in this order, and follow the relevant standard if there is an applicable size during the reference. In the case of a tire not defined in the above standards, it refers to the regular inflation pressure (but not less than 250 kPa) of another tire size described with the regular rim as the standard rim (however, it must be defined in the standard), and if there are multiple regular inflation pressures not less than 250 kPa, it refers to the minimum value among them.

[0044] The "normal load" is the load defined for each tire in a standard system including the standards on which the tire is based. For example, in the case of JATMA, it is the "maximum load capacity"; in the case of ETRTO, it is the "LOAD CAPACITY"; in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Refer to JATMA, ETRTO, and TRA in this order, similar to the case of the normal rim and normal internal pressure, and follow the relevant standard if there is an applicable size during the reference. For tires not defined in the above standards, the maximum load capacity W L calculated separately is taken as the normal load.

[0045] The "maximum load capacity W L " is calculated by the following formula. "V" is the virtual volume of the tire (mm 3 ), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the cross-sectional height of the tire in the cross-section of the tire by the plane including the tire rotation axis, in the tire radial direction (mm), and "Wt" is the cross-sectional width of the tire in the normal state (mm). When R is the rim diameter of the tire, Ht can be obtained by (Dt - R) / 2. Wt is the value obtained after excluding patterns or characters on the tire sidewall. Note that the maximum load capacity is synonymous with the above normal load.

[0046]

Equation

[0047] The "contact area" is the area of the tread obtained from the contour when the tire is pressed against the ground. Assemble the tire on the normal rim, apply the normal internal pressure, let it stand for 24 hours at 25°C, then paint ink on the tire tread surface, apply the normal load (maximum load capacity) to the tire and press it vertically against thick paper (the camber angle is 0°) to transfer the ink. The area of the contact area is called the total contact area. The total contact area can be calculated as the average value of the five areas obtained by performing the above transfer operation while rotating the tire by 72 degrees each time for a total of five locations.

[0048] The "effective contact area" is the area of the tread that comes into contact with the ground when the tire is pressed against the ground. It is obtained by assembling the tire onto a standard rim, applying the standard internal pressure, allowing it to stand for 24 hours at 25°C, then painting ink on the tire tread surface, applying the standard load (maximum load capacity) to the tire and pressing it vertically against thick paper (the camber angle is 0°) to transfer the ink. The area of the effective contact area is referred to as the effective contact area. The effective contact area can be calculated as the average value of the five areas obtained by performing the above transfer operation while rotating the tire by 72 degrees each time and performing it at a total of five locations.

[0049] The "land ratio R" is calculated by the following formula from the total contact area of the contact area and the effective contact area of the effective contact area. Land ratio = (Effective contact area / Total contact area)

[0050] A "groove" refers to a recessed portion formed on the tread surface of the tire and extending inward in the radial direction of the tire radius, where the groove width (opening width) on the tread surface is 2.0 mm or more. Those less than 2.0 mm are referred to as "sipes". A recessed portion that extends inward in the radial direction of the tire radius and has a groove width (opening width) on the tread surface of 2.0 mm or more. Those less than 2.0 mm are referred to as "sipes".

[0051] A "circumferential groove" refers to a groove that extends continuously in the circumferential direction of the tire. The circumferential groove may extend linearly along the circumferential direction, or may extend in a wave shape, a sine shape, or a zigzag shape along the circumferential direction.

[0052] The "groove depth H (mm) at the deepest part of the circumferential groove" refers to the linear distance between the straight line connecting the ends of the groove on the tread surface and the lowest part of the groove in the radial direction of the tire in the cross-section of the tire by a plane including the tire rotation axis. When the groove depth of the groove varies in the tire width direction and / or the circumferential direction, the maximum value of the said linear distance is taken as the groove depth of the groove. In addition, the depth at a point where three or more grooves intersect is excluded from the definition of the groove depth in this specification.

[0053] "Groove width" means the distance between groove walls. The groove width can be recognized at each position along the extending direction of the groove from the tread surface to the groove bottom.

[0054] "Widened groove" refers to a groove whose groove width is wider in the inner side in the tire radial direction than the groove width (opening width) at the tread surface.

[0055] "Total thickness T (mm) of the tread portion" is the thickness of the tread portion measured along the normal line at the tire equator in the cross-section of the tire by a plane including the tire rotation axis. When there are circumferential grooves on the tire equator, it is the thickness measured along the normal line on the central portion in the tire width direction of the land portion closer to the tire equator among the land portions existing on both sides in the tire width direction of the groove. Note that the total thickness T of the tread portion is the average value of the thicknesses of the tread portion obtained at five positions by rotating the tire by 72° in the circumferential direction.

[0056] "Thickness t1 (mm) of the layer whose outer surface constitutes the tread surface" is the thickness of the rubber layer whose outer surface constitutes the tread surface measured along the normal line at the tire equator in the cross-section of the tire by a plane including the tire rotation axis. When there are circumferential grooves on the tire equator, it is the thickness measured along the normal line on the central portion in the tire width direction of the land portion closer to the tire equator among the land portions existing on both sides in the tire width direction of the groove. Note that t1 is the average value of the tread thicknesses obtained at five positions by rotating the tire by 72° in the circumferential direction.

[0057] "Thickness B (mm) of the belt layer" is the thickness in the tire radial direction per layer of the belt layer at the tire equator in the cross-section of the tire by a plane including the tire rotation axis. When the belt layer does not exist on the equator, it is the thickness in the tire radial direction per layer at the central position of the belt layer where the central portion in the tire width direction of the belt layer is closer to the tire equator.

[0058] "The weight G (kg) of the tire" refers to the weight of the tire alone, excluding the weight of the rim. On the other hand, when the inner cavity of the tire is provided with a member made of sponge or sealant, or a sensor member, etc., the weight including them shall be used.

[0059] "The land portion" is the portion of the tread where the tire contacts the ground when the tire is pressed against the ground, and is the portion of the tread that constitutes the effective contact area.

[0060] "The rubber component of the rubber composition" is a component that contributes to crosslinking within the rubber composition, and generally has a weight average molecular weight (Mw) of 10,000 or more.

[0061] "The glass transition temperature (Tg) of the rubber component" is 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.).

[0062] "The styrene content" is 1 a value calculated by 1H-NMR measurement, and is applied to rubber components (styrene unit-containing rubbers) having repeating units derived from styrene such as SBR, for example.

[0063] "The vinyl content (amount of 1,2-bonded butadiene units)" is a value calculated by infrared absorption spectrum analysis in accordance with JIS K 6239-2:2017, and is applied to rubber components having repeating units derived from butadiene such as SBR and BR, for example.

[0064] "The cis content (amount of cis-1,4-bonded butadiene units)" is a value calculated by infrared absorption spectrum analysis in accordance with JIS K 6239-2:2017, and is applied to rubber components having repeating units derived from butadiene such as BR, for example.

[0065] "Weight-average molecular weight (Mw)" can be determined by standard polystyrene conversion based on the measured values obtained by gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation). For example, it is applicable to SBR, BR, plasticizers, etc.

[0066] "Nitrogen adsorption specific surface area (N2SA) of carbon black" is measured in accordance with JIS K 6217-2:2017. "Nitrogen adsorption specific surface area (N2SA) of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0067] "Average primary particle diameter" is determined by photographing the particles with a transmission or scanning electron microscope and calculating the arithmetic mean of 400 particle diameters. When the shape of the particle is approximately circular, the diameter of the circle is taken as the particle diameter; when it is needle-shaped or rod-shaped, the minor axis is taken as the particle diameter; in other cases, the equivalent circle diameter is calculated from the electron microscope image and taken as the particle diameter. The equivalent circle diameter is obtained as the positive square root of [4 × (area of the particle) / π]. The average primary particle diameter is applicable to silica, carbon black, etc.

[0068] "Content of plasticizer" includes the amount of plasticizer contained in the extended rubber component previously extended with a plasticizer such as oil, resin component, liquid rubber component, etc. The same applies to the content of oil, resin component, and liquid rubber. For example, when the extended component is oil, the extended oil is included in the content of oil.

[0069] "Softening point of resin component" is measured with a ring and ball softening point measuring device at the temperature at which the ball drops, which is defined in JIS K 6220-1:2015 7.7.

[0070] [Tire] Hereinafter, with reference to the drawings, the tire according to this embodiment will be described. Note that the following embodiment is merely an example, and the tire according to this embodiment is not limited to the following embodiment.

[0071] FIG. 1 illustrates a tire according to the present embodiment. FIG. 1 shows a part of a cross section when the tire is cut along a plane including the tire rotation axis. In FIG. 1, the vertical direction is the radial direction of the tire, the horizontal direction is the axial direction of the tire, and the direction perpendicular to the paper surface is the circumferential direction of the tire. In FIG. 1, the dashed-dotted line CL represents the tire equator.

[0072] The tire of FIG. 1 has a tread portion 1 that contacts the ground during running, a pair of sidewall portions 2 that extend outward in the radial direction of the tire, and a pair of bead portions 3.

[0073] As shown in FIG. 1, a belt layer 5 is provided inside the tread portion 1 in the radial direction of the tire. Below the belt layer 5, a carcass 4 and an inner liner 7 are laminated. Also, a band layer 6 may be present between the tread portion 1 and the belt layer 5. The bead portion 3 includes a bead core 14 and a bead apex 13 that extends outward in the radial direction of the tire from this core. The bead apex 13 tapers outward in the radial direction of the tire. In the bead portion 3, a clinch portion 10 that contacts the rim 8 when the rim 8 is mounted is provided outside the carcass 4, and the clinch portion 10 is composed of a rubber composition containing a rubber component. A rim chafer 9 may be present between the clinch portion 10 and the rim 8.

[0074] The tread portion according to the present embodiment may be a tread portion composed of a single rubber layer, or may be a tread portion having a layer (cap rubber layer) whose outer surface constitutes the tread surface and one or more rubber layers (inner rubber layers) present between the cap rubber layer and the belt layer. In FIG. 1, a cap rubber layer 11 and a base rubber layer 12 laminated outside the belt layer 5 in the radial direction of the tire are provided. The double-headed arrow t1 is the thickness of the cap rubber layer 11, and the double-headed arrow t2 is the thickness of the base rubber layer 12.

[0075] The thickness t1 of the cap rubber layer is not particularly limited, but is preferably 3.0 mm or more, more preferably 4.0 mm or more, still more preferably 5.0 mm or more, and particularly preferably 6.0 mm or more. Also, t1 is preferably 10.0 mm or less, more preferably 9.5 mm or less, still more preferably 9.0 mm or less, and particularly preferably 8.5 mm or less.

[0076] The thickness t2 of the base rubber layer is not particularly limited, but is preferably 0.8 mm or more, more preferably 1.0 mm or more, still more preferably 1.2 mm or more, and particularly preferably 1.4 mm or more. Also, t2 is preferably 5.0 mm or less, more preferably 4.0 mm or less, still more preferably 3.0 mm or less.

[0077] The total thickness T (t1 + t2 in FIG. 1) of the tread portion is preferably 6.0 mm or more, more preferably 6.5 mm or more, still more preferably 7.0 mm or more, further more preferably 7.5 mm or more, and particularly preferably 8.0 mm or more. On the other hand, the upper limit value of T is not particularly limited, but is preferably 11.0 mm or less, more preferably 10.5 mm or less, still more preferably 10.0 mm or less, and particularly preferably 9.5 mm or less.

[0078] The thickness B of the belt layer 5 is preferably 0.6 mm or more, more preferably 0.7 mm or more, still more preferably 0.8 mm or more, and particularly preferably 0.9 mm or more. Also, the thickness B of the belt layer 5 is preferably 1.6 mm or less, more preferably 1.4 mm or less, still more preferably 1.2 mm or less, and particularly preferably 1.1 mm or less.

[0079] From the viewpoint of reducing rolling resistance and improving grip performance, t1 / B is preferably 8.0 or less, more preferably 7.5 or less, still more preferably 7.0 or less. Also, t1 / B is preferably 2.0 or more, more preferably 2.5 or more, still more preferably 3.0 or more, and particularly preferably 3.5 or more.

[0080] ≪Tread portion≫ FIG. 2 is a cross-sectional view showing a cross-section passing through the tire rotation axis of the tread portion of the tire. In FIG. 2, the vertical direction is the tire radial direction, the left-right direction is the tire width direction, and the direction perpendicular to the paper surface is the tire circumferential direction. In FIG. 2, the midpoint of the land portion 20 in the tire width direction is shown as symbol P. The straight line indicated by symbol N passes through point P and is a straight line (normal line) perpendicular to the tangent plane at this point P.

[0081] The tread portion according to this embodiment has at least one or more circumferential grooves 15. The tread portion has land portions 20 partitioned by the circumferential grooves 15 in the tire width direction.

[0082] The groove depth H at the deepest part of the circumferential groove 15 refers to the linear distance in FIG. 2 between the straight line 17 connecting the ends of the circumferential grooves on the tread surface 16 and the extension line of the lowest part of the groove in the tire radial direction. Note that when there are a plurality of circumferential grooves 15, for example, the groove depth H can be the linear distance between the straight line 17 and the extension line 19 of the lowest part of the circumferential groove 15 having the deepest groove depth among the plurality of circumferential grooves 15 (the left circumferential groove 15 in FIG. 1).

[0083] From the viewpoint of wear resistance performance, the groove depth H at the deepest part in the circumferential direction is preferably 4.5 mm or more, more preferably 5.0 mm or more, still more preferably 5.5 mm or more, and particularly preferably 6.0 mm or more. Also, from the viewpoint of wet grip performance, the groove depth H at the deepest part of the circumferential groove is preferably 10.0 mm or less, more preferably 9.5 mm or less, still more preferably 9.0 mm or less, and particularly preferably 8.5 mm or less.

[0084] As shown in FIGS. 1 and 2, the tread portion may have a layer (cap rubber layer 11) whose outer surface constitutes the tread surface 16, and a base rubber layer 12 adjacent to the inner side in the radial direction of the cap rubber layer 11. One of the circumferential grooves 15 shown on the left side of FIG. 2 is formed such that the deepest part of the groove bottom of the circumferential groove 15 is located on the inner side in the tire radial direction with respect to the outer surface of the base rubber layer 12. Specifically, the base rubber layer 12 has a recess recessed inward in the tire radial direction with respect to the outer surface, and a part of the cap rubber layer 11 is formed in the recess of the base rubber layer 12 with a predetermined thickness. The circumferential groove 15 is formed so as to enter the inside of the recess of the base rubber layer 12 beyond the outer surface of the base rubber layer 12. Note that the circumferential groove 15 may be formed with a groove depth that does not reach the outer surface of the base rubber layer 12, such as the circumferential groove 15 shown on the right side of FIG. 2.

[0085] In this specification, the "rubber composition constituting the tread portion" refers to the rubber composition constituting the cap rubber layer when the tread portion is composed of two or more layers.

[0086] The acetone extraction amount AE of the rubber composition constituting the tread portion is more than 17.0% by mass, preferably more than 20.0% by mass, more preferably 22.0% by mass, and even more preferably more than 23.0% by mass from the viewpoint of improving the efficiency of filler dispersion and distribution and reducing the rigidity at low temperatures. Also, from the viewpoint of wear resistance performance, the acetone extraction amount (AE) is preferably less than 35.0% by mass, more preferably less than 33.0% by mass, and even more preferably less than 30.0% by mass.

[0087] AE×H is 140.0 or more, preferably 142.0 or more, and more preferably 145.0 or more from the viewpoint of wet grip performance. Also, AE×H is preferably 210.0 or less, more preferably 200.0 or less, and even more preferably 190.0 or less from the viewpoint of wear resistance performance.

[0088] From the perspective of the effects of the present invention, the tanδ at the peak position within the range of -20°C to -70°C in the tanδ temperature distribution curve of the rubber composition constituting the tread portion is preferably 0.40 or more, more preferably 0.44 or more, and even more preferably 0.48 or more.

[0089] The half-width at half maximum of the peak (half-width at half maximum of the tanδ peak) is 35°C or more, preferably 36°C or more, more preferably 37°C or more, even more preferably 38°C or more, and particularly preferably 40°C or more. When the half-width at half maximum of the peak is 35°C or more, energy loss can occur in a wide frequency band, and the input from the road surface can be released as heat even in the deformation speed region of the rubber cracks, so that crack growth can be suppressed, wear resistance performance can be improved, and energy loss can occur widely in the frequency band during wet braking, so that wet grip performance can be improved. It should be noted that the temperature distribution curve of tanδ may have multiple peak tops. In that case, for at least one peak (curve), the half-width at half maximum of the peak only needs to be within the above range.

[0090] From the perspective of the effects of the present invention, the 30°C E* of the rubber composition constituting the tread portion is preferably 6.0 MPa or more, more preferably 6.5 MPa or more, even more preferably 7.0 MPa or more, still more preferably 7.5 MPa or more, and particularly preferably 8.0 MPa or more. Also, from the perspective of noise suppression of the tire pattern, it is preferably 14.0 MPa or less, more preferably 13.0 MPa or less, and even more preferably 12.0 MPa or less.

[0091] From the perspective of wear resistance performance, 30°C E* / H is preferably 1.25 or more, more preferably 1.28 or more, even more preferably 1.30 or more, and particularly preferably 1.32 or more. The upper limit value of 30°C E* / H is not particularly limited, but is preferably 2.00 or less, more preferably 1.95 or less, and even more preferably 1.90 or less.

[0092] The tanδ at 30°C of the rubber composition constituting the tread portion is preferably 0.20 or more, more preferably 0.25 or more, still more preferably 0.30 or more, and particularly preferably 0.35 or more from the viewpoint of wet grip performance. Further, from the viewpoint of low fuel consumption performance, it is preferably 0.55 or less, more preferably 0.50 or less, and still more preferably 0.45 or less.

[0093] 30°C tanδ × T is preferably 2.5 or more, more preferably 2.8 or more, and still more preferably 3.0 or more from the viewpoint of wet grip performance. The upper limit value of 30°C tanδ × T is not particularly limited, but is preferably 6.0 or less, more preferably 5.5 or less, still more preferably 5.0 or less, and particularly preferably 4.5 or less.

[0094] The glass transition temperature (Tg) of the rubber composition constituting the tread portion is preferably above -36°C, more preferably above -34°C, and still more preferably above -32°C from the viewpoint of the effects of the present invention. Further, from the viewpoint of abrasion resistance performance, it is preferably less than -16°C, more preferably less than -18°C, and still more preferably less than -20°C.

[0095] In addition, each physical property such as the tanδ at 30°C and E* at 30°C of the rubber composition can be appropriately adjusted by the types and blending amounts of the rubber component, filler, plasticizer, etc. described later. For example, the tanδ at 30°C can be adjusted according to the type of resin component.

[0096] ≪Tread Pattern≫ FIG. 3 shows the tread pattern of a tire according to an embodiment of the present invention. However, the tread pattern of the tire according to this embodiment is not limited to FIG. 3. In FIG. 3, the tread surface has three circumferential grooves extending continuously in the tire circumferential direction. The circumferential groove located at the center (central circumferential groove) extends in a zigzag shape, but is not limited to such a form, and the central circumferential groove may be linear. Also, a pair of circumferential grooves (a pair of outermost circumferential grooves) located on both sides thereof extend linearly, but are not limited to such a form, and the outermost circumferential groove may be linear. These circumferential grooves demarcate a pair of center land portions 21 and a pair of shoulder land portions 22. In the center land portion 21, transverse grooves 31 extending toward the inner side in the tire radial direction are arranged, and in the shoulder land portion 22, transverse grooves 32 extending toward the inner side in the tire diameter direction are arranged. The transverse groove 31 is a widened groove having a portion where the groove width widens in a cross section perpendicular to the extending direction, compared to the groove width on the tread surface. On the other hand, the transverse groove 32 has a constant groove width in a cross section perpendicular to the extending direction and is not a widened groove. Both ends of the transverse groove 31 are not in communication with the circumferential groove, but are not limited to such a form, and at least one of both ends may be in communication with the circumferential groove. One end of the transverse groove 32 is in communication with the circumferential groove, and the other end extends to the tread grounding end Te, but is not limited to such an aspect. However, from the viewpoint of drainage, it is preferable that, like the transverse groove 32, one end is in communication with the circumferential groove and the other end extends to the tread grounding end Te.

[0097] The tread portion of the tire according to this embodiment preferably has two or more land portions demarcated by one or more circumferential grooves, and preferably has a plurality of transverse grooves extending toward the inner side in the tire radial direction in at least one of the land portions, and at least one of the transverse grooves is preferably a widened groove.

[0098] FIG. 4 shows a cross-sectional view taken along line C-C of the transverse groove 31 shown in FIG. 3. The cross section is a cross section perpendicular to the extending direction of the transverse groove 31 extending toward the inner side in the tire diameter direction.

[0099] The form of the widened part of the widened groove is not particularly limited as long as the drainage performance can be improved according to the wear of the tire, thereby improving the grip performance. For example, in the widened lateral grooves 31 in FIGS. 3 and 4, the width of the widened part expands uniformly from the tread surface to the groove bottom along the tire radius direction, that is, the widest groove width is at the groove bottom. Therefore, the drainage performance increases as the tire wears.

[0100] In FIG. 4, the groove walls 42 on both sides of the lateral groove 31, which is a widened groove, are recessed from the groove edges of the tread surface to the groove bottom, and the amount of the recess is represented by C1 and C2. C1 and C2 are preferably each independently 0.05 times or more, more preferably 0.07 times or more, and still more preferably 0.10 times or more with respect to the groove width (groove width on the tread surface, opening width) W1, which is the distance between the groove edges of the lateral groove. On the other hand, the value is preferably 0.45 times or less, more preferably 0.40 times or less, and still more preferably 0.35 times.

[0101] From the viewpoint of the effects of the present invention, the land ratio R of the tire according to the present embodiment is preferably 0.80 or less, more preferably 0.75 or less, and still more preferably 0.70 or less. Also, from the viewpoint of wear resistance performance, the land ratio R is preferably 0.50 or more, more preferably 0.55 or more, and still more preferably 0.60 or more.

[0102] In FIG. 3, the central circumferential groove is present within the center region, which is a region of 30% of the tread contact width centered on the tire equator on the tread surface, and its shape is a zigzag shape in which straight grooves are repeatedly bent. It is preferable that the tread portion of the tire according to the present embodiment has a circumferential groove in the center region, which is a region of 30% of the tread contact width centered on the tire equator on the tread surface.

[0103] In the tire tread portion according to this embodiment, when a region of 30% of the tread contact width centered on the tire equator on the tread surface is defined as the center region, and regions on both outer sides of the center region and within the tread contact width are defined as a pair of shoulder regions, it is preferable that circumferential grooves also exist in the shoulder regions. When circumferential grooves exist in the shoulder regions, the groove depth at the deepest part of the circumferential grooves is preferably 4.5 mm or more, more preferably 5.0 mm or more, still more preferably 5.5 mm or more, and particularly preferably 6.0 mm or more. With the above configuration, drainage performance can be enhanced, and it is considered to contribute to the improvement of wet grip performance. On the other hand, the groove depth at the deepest part of the circumferential grooves existing in the shoulder regions is preferably 10.0 mm or less, more preferably 9.5 mm or less, still more preferably 9.0 mm or less, and particularly preferably 8.5 mm or less.

[0104] The circumferential grooves existing in the shoulder regions are the circumferential grooves on the tread surface other than the circumferential grooves existing in the above-mentioned center region. That is, even if the grooves existing in the shoulder regions straddle both the center region and the shoulder regions, more than half of the grooves are the circumferential grooves existing in the shoulder regions. Further, the groove depth at the deepest part of the circumferential grooves existing in the shoulder regions means the groove depth of the circumferential groove having the deepest groove depth when there are a plurality of circumferential grooves existing in the shoulder regions. Note that the groove depth at the deepest part of the circumferential grooves existing in the shoulder regions here refers to the groove depth of the circumferential grooves when circumferential grooves exist in the shoulder regions, and is different from the deepest groove depth H (mm) which refers to the groove depth of the circumferential groove having the deepest groove depth among all the circumferential grooves.

[0105] The weight G of the tire according to this embodiment is preferably 8.0 kg or more, more preferably 8.5 kg or more, still more preferably 9.0 kg or more, and particularly preferably 9.5 kg or more. The upper limit value of the tire weight G is not particularly limited, but is usually 100 kg or less, and can be, for example, 80 kg or less, 60 kg or less, 40 kg, 20 kg, 15 kg or less, etc.

[0106] [Rubber Composition] The rubber composition (hereinafter referred to as the rubber composition according to the present embodiment) constituting the tread portion of the tire according to the present embodiment includes a rubber component containing isoprene rubber and styrene-butadiene rubber, and silica, and all can be manufactured using the raw materials described below. Hereinafter, the rubber composition according to the present embodiment will be described.

[0107] [Rubber Component] In the rubber composition according to the present embodiment, a diene rubber is preferably used as the rubber component. Examples of the diene rubber include isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and the like. These diene rubbers may be modified rubbers treated with a modifying group capable of interacting with fillers such as carbon black and silica, or may be hydrogenated rubbers in which a part of the unsaturated bonds is hydrogenated. The diene rubber may be used alone or in combination of two or more. Further, as the diene rubber, an extended rubber preliminarily extended using a plasticizer described later may be used.

[0108] The content of the diene rubber in the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Further, the rubber component may be composed only of the diene rubber.

[0109] The rubber component according to the present embodiment includes isoprene rubber and styrene-butadiene rubber, and preferably contains isoprene rubber, styrene-butadiene rubber, and butadiene rubber. Further, the rubber component according to the present embodiment can be a rubber component composed only of isoprene rubber and styrene-butadiene rubber, or can be a rubber component composed only of isoprene rubber, styrene-butadiene rubber, and butadiene rubber.

[0110] [Isoprene Rubber] As the isoprene rubber, for example, those commonly used in the tire industry such as isoprene rubber (IR) and natural rubber can be used. Natural rubber includes, in addition to unmodified natural rubber (NR), modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, and grafted natural rubber. These isoprene rubbers may be used alone or in combination of two or more.

[0111] NR is not particularly limited, and those commonly used in the tire industry can be used, for example, SIR20, RSS#3, TSR20, etc.

[0112] From the viewpoint of the effects of the present invention, the content of the isoprene rubber in the rubber component is 40% by mass or more, preferably more than 40% by mass, more preferably 45% by mass or more, and still more preferably 50% by mass or more. Also, the content of the isoprene rubber is preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 75% by mass or less, and particularly preferably 70% by mass or less.

[0113] (SBR) SBR is not particularly limited, and examples include solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR). Examples of the modified SBR include SBR modified at the terminal and / or main chain with a compound (modifying agent) having the following functional group; modified SBR coupled with tin, silicon compound, etc. (condensate, those having a branched structure, etc.). Furthermore, hydrogenated products of these SBRs (hydrogenated SBR) can also be used. These SBRs may be used alone or in combination of two or more.

[0114] As the functional group of the modifier, a functional group containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen is preferable. Examples of such functional groups include, for example, amino group, amide group, silyl group, alkoxysilyl group, isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, oxycarbonyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), hydroxyl group, oxy group, epoxy group, etc. An amino group and / or an alkoxysilyl group is preferable. As the amino group, an amino group substituted with 1 to 2 alkyl groups having 1 to 6 carbon atoms is preferable. Specific examples of alkoxysilyl include, for example, trimethoxysilyl, triethoxysilyl, triisopropoxysilyl, dimethoxymethylsilyl, diethoxymethylsilyl, dimethylmethoxysilyl, dimethylethoxysilyl, etc.

[0115] As the SBR, oil-extended SBR can be used, or non-oil-extended SBR can be used. As the SBR that can be used in this embodiment, those commercially available from JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Industries, Ltd., Asahi Kasei Corporation, ZS Elastomers Co., Ltd., ARLANXEO, etc. can be used.

[0116] From the viewpoint of the effects of the present invention, the styrene content S1 of the SBR is 30% by mass or less, preferably 28% by mass or less, more preferably 25% by mass or less, and even more preferably 22% by mass or less. Also, from the viewpoint of grip performance, S1 is preferably 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more.

[0117] From the viewpoint of ensuring reactivity with silica and abrasion resistance performance, the vinyl content of SBR is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more. Further, from the viewpoint of wet grip performance, the vinyl content of SBR is preferably 45 mol% or less, more preferably 40 mol% or less, and even more preferably 35 mol% or less. In the present specification, the vinyl content of SBR is measured by the above measurement method.

[0118] From the viewpoint of the effects of the present invention, S1×R is preferably 10.0 or more, more preferably 11.0 or more, even more preferably 12.0 or more, and particularly preferably 13.0 or more. Further, S1×R is preferably 20.0 or less, more preferably 18.0 or less, and even more preferably 17.0 or less.

[0119] From the viewpoint of the effects of the present invention, S1 / G is preferably 1.2 or more, more preferably 1.5 or more, and even more preferably 1.8 or more. Further, S1 / G is preferably 4.0 or less, more preferably 3.5 or less, even more preferably 3.0 or less, and particularly preferably 2.7 or less.

[0120] From the viewpoint of the effects of the present invention, the glass transition temperature (Tg) of SBR is preferably -40°C or lower, more preferably -45°C or lower, even more preferably -50°C or lower, and particularly preferably -55°C or lower. Further, from the viewpoint of abrasion resistance performance, it is preferably -90°C or higher, more preferably -80°C or higher, and even more preferably -70°C or higher.

[0121] From the viewpoint of the effects of the present invention, the weight average molecular weight (Mw) of SBR is preferably more than 80,000, more preferably more than 100,000, even more preferably more than 150,000, and particularly preferably more than 500,000. Further, from the viewpoint of crosslinking uniformity and the like, Mw is preferably less than 2,000,000, more preferably less than 1,500,000, and even more preferably less than 1,100,000. In the present specification, the Mw of SBR is measured by the above measurement method.

[0122] From the perspective of the effects of the present invention, the content in the rubber component of SBR is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 25% by mass or more, still more preferably 30% by mass or more, and particularly preferably 35% by mass or more. Also, the content in the rubber component of SBR is preferably 60% by mass or less, more preferably 55% by mass or less, still more preferably 50% by mass or less, and particularly preferably 45% by mass or less.

[0123] (BR) BR is not particularly limited. For example, BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare-earth-based butadiene rubber synthesized using a rare-earth element-based catalyst (rare-earth-based BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc., which are common in the tire industry, can be used. These BRs can be used alone or in combination of two or more.

[0124] As high-cis BR, for example, those commercially available from Nippon Zeon Co., Ltd., UBE Industries, Ltd., JSR Corporation, etc. can be used. By containing high-cis BR, the low-temperature properties and abrasion resistance can be improved. The cis content of high-cis BR is preferably more than 95 mol%, more preferably more than 96 mol%, and still more preferably more than 97 mol%. The cis content of BR is measured by the above measurement method.

[0125] As rare-earth-based BR, it is synthesized using a rare-earth element-based catalyst, and the vinyl content is preferably less than 1.8 mol%, more preferably less than 1.6 mol%, still more preferably 1.5 mol% or less, and the cis content is preferably more than 95 mol%, more preferably more than 96 mol%, and still more preferably 97 mol% or more. As rare-earth-based BR, for example, those commercially available from Lanxess Co., Ltd., etc. can be used.

[0126] In the case of the SPB-containing BR, the 1,2-syndiotactic polybutadiene crystals are not merely dispersed in the BR but are dispersed after being chemically bonded to the BR. As such SPB-containing BR, those commercially available from UBE Industries, Ltd. and the like can be used.

[0127] Examples of the modified BR include BR modified with the same functional groups as those described for the SBR above, and modified butadiene rubber (modified BR) modified with a functional group containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen at the terminal and / or in the main chain can also be preferably used.

[0128] Other modified BRs include those obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and in which the terminals of the modified BR molecules are bonded by tin-carbon bonds (tin-modified BR), etc. The modified BR may be either unhydrogenated or hydrogenated.

[0129] From the viewpoint of abrasion resistance performance, 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 viewpoints of crosslinking uniformity, etc., it is preferably less than 2,000,000, more preferably less than 1,000,000, and even more preferably less than 500,000. Note that Mw can be determined by the above method.

[0130] The content in the rubber component of the BR is not particularly limited, but is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and particularly preferably 15% by mass or more. Also, the content in the rubber component of the BR is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less.

[0131] From the perspective of the effects of the present invention, the total styrene content S2 in the rubber component is preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less. Also, S2 is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more.

[0132] (Other rubber components) The rubber component may contain a rubber component other than the diene rubber (non-diene rubber) as long as it does not affect the effects of the present invention. As the non-diene rubber, rubber components generally used in the tire industry can be used. For example, butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), hydrin rubber, etc. can be mentioned. These non-diene rubbers may be used alone or in combination of two or more. Also, in addition to the above rubber components, a known thermoplastic elastomer may or may not be contained.

[0133] (Rubber components synthesized from recycled and biomass-derived raw materials) The monomers that are the constituent units of synthetic rubbers such as IR, BR, and SBR may be derived from underground resources such as petroleum and natural gas, or may be recycled from rubber products such as tires and non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled polyisoprene, recycled butadiene, recycled aromatic vinyl compounds, etc. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl compound is not particularly limited, and examples include styrene. Among them, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and recycled styrene (recycled styrene) as raw materials.

[0134] The method for producing the recycled monomer is not particularly limited. For example, it can be synthesized from naphtha derived from recycling obtained by decomposing rubber products such as tires. Also, the method for producing naphtha derived from recycling is not particularly limited. For example, rubber products such as tires may be decomposed under high temperature and high pressure, decomposed by microwaves, or extracted after mechanical pulverization.

[0135] Furthermore, the monomers that are constituent units of synthetic rubbers such as IR, BR, and SBR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural and forestry products, sugars, wood chips, plant residues after obtaining useful components, ethanol derived from plants, biomass naphtha, and the like.

[0136] The biomass-derived monomers (biomass monomers) are not particularly limited, and examples include biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl compound is not particularly limited, and examples include styrene. Also, the method for producing biomass monomers is not particularly limited, and examples include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical of biological conversion, and chemical and / or physical conversion includes those by catalysts, high heat, high pressure, electromagnetic waves, supercritical fluids, and combinations thereof.

[0137] The polymers synthesized from biomass monomer components (biomass polymers) are not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compounds. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0138] Whether the raw material of the polymer is derived from biomass can be determined by pMC (percent Modern Carbon) measured in accordance with ASTM D6866-10.

[0139] pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the modern standard reference, and is a value used as an indicator showing the biomass ratio of a compound. The meaning of this value will be described below.

[0140] In one mole (6.02×10 23 pieces) of carbon atoms, there are approximately 6.02×10 11 pieces of 14 C, which is about one trillionth of ordinary carbon atoms. 14 The half-life of 14 C is 5730 years, and 14 C decreases regularly. Therefore, in fossil fuels such as coal, oil, and natural gas, which are considered to have passed more than 226,000 years after carbon dioxide in the atmosphere was taken up and fixed by plants, etc., all of the 14 C elements contained in them at the beginning of fixation have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain any 14 C elements at all. Therefore, chemical substances produced from these fossil fuels as raw materials also do not contain any

[0141] On the other hand, 14 C is constantly generated by cosmic rays undergoing nuclear reactions in the atmosphere. From this, 14 C is in balance between the decrease due to radioactive decay and the generation due to nuclear reactions, and in the earth's atmospheric environment, the amount of 14 C is a certain amount. Therefore, the 14 C concentration of substances derived from biomass resources circulating in the current environment is about 1×10 with respect to the entire carbon atoms as described above. -12It becomes a value of about mol%. Therefore, by utilizing the difference between these values, the biomass ratio in a certain compound can be calculated.

[0142] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 C) is measured. In the measurement, 14 As a modern standard reference for the concentration of 14 C, the concentration of 14 C in the circulating carbon in nature in 1950 is adopted. As a specific reference material, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific activity of carbon in this oxalic acid (the radioactivity intensity of 13 C per gram of carbon) is fractionated for each carbon isotope, 14 C is corrected to a constant value, and the value obtained by applying the decay correction from 1950 AD to the measurement date is used as the value of the standard

[0143] Therefore, if the rubber is made of 100% biomass-derived materials, although there are regional differences and so on, it often does not reach 100 under normal conditions at present, so it will show a value of about 110 pMC. On the other hand, for chemical substances derived from fossil fuels such as petroleum, when this

[0144] 14C concentration is measured, it will show a value of about 0 pMC (for example, 0.3 pMC). This value corresponds to the biomass ratio of 0% mentioned above.

[0145] From the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in the rubber composition is suitable from the perspective of environmental protection.[Filler] The rubber composition according to this embodiment contains silica as a filler, and more preferably contains silica and carbon black. Further, the filler may be a filler consisting only of carbon black and silica.

[0146] [Silica] The silica is not particularly limited, and for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), etc., which are common in the tire industry, can be used. The raw material of silica is not particularly limited, and for example, it may be a raw material derived from minerals such as quartz, or a raw material derived from organisms such as rice husks (for example, silica using biomass materials such as rice husks as raw materials), or silica recycled from products containing silica may be used. Among them, hydrous silica prepared by a wet method is preferable because it has many silanol groups. These silicas may be used alone or in combination of two or more.

[0147] Silica using biomass materials as raw materials can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to precipitate silicon dioxide, followed by filtration, washing with water, drying, and pulverization.

[0148] Silica recycled from products containing silica can be used, for example, silica recovered from products containing silica such as electronic components such as semiconductors, tires, desiccants, and filter materials such as diatomaceous earth. Further, the recovery method is not particularly limited, and examples include pyrolysis and decomposition by electromagnetic waves. Among them, silica recovered from electronic components such as semiconductors or tires is preferable.

[0149] When silica crystallizes, it does not dissolve in water and the silicic acid that is its component cannot be utilized. By controlling the combustion temperature and combustion time, crystallization of silica in rice husk ash can be suppressed (see, for example, JP-A-2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.).

[0150] Amorphous silica extracted from rice husks can be those commercially available from Wilmar Co., Ltd. and others.

[0151] From the viewpoint of reinforcement, the nitrogen adsorption specific surface area (N2SA) of silica is preferably more than 110 m 2 / g, more preferably more than 130 m 2 / g, even more preferably more than 150 m 2 / g, particularly preferably more than 170 m 2 / g. Also, from the viewpoints of exothermic property and processability, it is preferably less than 220 m 2 / g, more preferably less than 200 m 2 / g, even more preferably less than 180 m 2 / g. Note that the N2SA of silica is measured by the above measurement method.

[0152] From the viewpoint of the effects of the present invention, the average primary particle diameter of silica is preferably more than 10 nm, more preferably more than 12 nm, and even more preferably more than 14 nm. Also, the average primary particle diameter is preferably less than 20 nm, more preferably less than 18 nm, and even more preferably less than 17 nm. Note that the average primary particle diameter of silica is measured by the above measurement method.

[0153] From the viewpoint of the effects of the present invention, the content of silica with respect to 100 parts by mass of the rubber component is 80 parts by mass or more, preferably more than 80 parts by mass, more preferably 85 parts by mass or more, and even more preferably 90 parts by mass or more. Also, from the viewpoint of compatibility with isoprene rubber, it is preferably 140 parts by mass or less, more preferably 130 parts by mass or less, even more preferably 120 parts by mass or less, and particularly preferably 110 parts by mass or less.

[0154] From the viewpoint of the effects of the present invention, the content of silica in the filler is preferably 55% by mass or more, more preferably 65% by mass or more, even more preferably 75% by mass or more, and particularly preferably 80% by mass or more. Also, from the viewpoint of wear resistance performance, it is preferably 95% by mass or less, more preferably 92% by mass or less, and even more preferably 90% by mass or less.

[0155] <Carbon black> The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw material of the carbon black may be a biomass material such as lignin or vegetable oil, or may be a pyrolysis oil obtained by pyrolyzing waste tires. Further, the manufacturing method of the carbon black may be by combustion such as the furnace method, may be by hydrothermal carbonization (HTC), or may be by thermal decomposition of methane such as the thermal black method. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbian Carbon Co., etc. can be used. These carbon blacks may be used alone or in combination of two or more.

[0156] In addition to the above, from the perspective of life cycle assessment, etc., carbon black made from biomass materials such as lignin as a raw material, or recycled carbon black obtained by pyrolyzing and purifying products containing carbon black such as tires may also be used.

[0157] In this specification, "recycled carbon black" refers to carbon black obtained by pulverizing used products such as tires containing carbon black and firing the pulverized product, and when oxidized and burned by heating in air by a thermogravimetric method conforming to JIS K 6226-2:2003, it refers to carbon black in which the ratio of the mass of the component that does not burn (ash content) is 13% by mass or more. That is, the ratio of the mass of the weight loss component (carbon amount) due to the oxidation combustion of the recycled carbon black is 87% by mass or less. Recycled carbon black may also be represented by rCB.

[0158] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975 refers to "Rubber Chemistry and Technology", Vol. 85, No. 3, pages 408 - 449 (2012), especially pages 438, 440, 442, and describes that it can be obtained by pyrolysis of organic materials at 550 - 800 °C with oxygen excluded, or by vacuum pyrolysis at relatively low temperatures (

[0027] ). The carbon black obtained from such a pyrolysis process usually lacks functional groups on its surface, as mentioned in

[0004] of Patent No. 6856781 (Comparison of the surface morphology and chemistry of pyrolytic carbon black and commercially available carbon black, Powder Technology 160 (2005) 190 - 193).

[0159] Recycled carbon black may lack functional groups on its surface, or may be treated to contain functional groups on its surface. The treatment to make the recycled carbon black contain functional groups on its surface can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Also, in Patent No. 6856781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes such carbon black treated to contain functional groups on its surface.

[0160] Recycled carbon black commercially available from companies such as Strable Green Carbon and LDCarbon can be used.

[0161] From the perspective of reinforcement, the nitrogen adsorption specific surface area (N2SA) of carbon black is preferably more than 70 m 2 / g, and preferably 100 m2 / g or more is more preferable, 120 m 2 / g or more is even more preferable, 140 m 2 / g or more is particularly preferable. Further, from the viewpoints of heat generation property and processability, less than 250 m 2 / g is preferable, less than 220 m 2 / g or less is more preferable, less than 190 m 2 / g or less is even more preferable. The N2SA of the carbon black is measured by the above-mentioned measuring method.

[0162] The average primary particle diameter of the carbon black is preferably less than 32 nm, more preferably less than 28 nm, even more preferably less than 24 nm, even more preferably less than 20 nm, and particularly preferably less than 18 nm. Further, the average primary particle diameter is preferably more than 8 nm, more preferably more than 10 nm, even more preferably more than 12 nm, and particularly preferably more than 14 nm. The average primary particle diameter of the carbon black is measured by the above-mentioned measuring method.

[0163] From the viewpoint of wear resistance performance, the content of carbon black with respect to 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more. Further, the content is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0164] <Other fillers> The filler may contain other fillers other than silica and carbon black. The other fillers are not particularly limited, but for example, those commonly used in the tire industry such as aluminum hydroxide, calcium carbonate, alumina, clay, talc, etc. can be blended.

[0165] The total content of the filler relative to 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, still more preferably 60 parts by mass or more, and particularly preferably 70 parts by mass or more. Also, the content is preferably 140 parts by mass or less, more preferably 130 parts by mass or less, and still more preferably 120 parts by mass or less.

[0166] <Silane coupling agent> Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited. For example, sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, etc. are mentioned. Among them, it is preferable to contain a sulfide-based silane coupling agent and / or a mercapto-based silane coupling agent. As the silane coupling agent, for example, those commercially available from Evonik Degussa, Momentive, etc. can be used. These silane coupling agents may be used alone or in combination of two or more.

[0167] The content of the silane coupling agent with respect to 100 parts by mass of the rubber component (when a plurality of silane coupling agents are used in combination, the total amount of all of them) is preferably more than 3.0 parts by mass, more preferably more than 5.0 parts by mass, and even more preferably 6.0 parts by mass or more from the viewpoint of enhancing the dispersibility of silica. Further, from the viewpoint of preventing a decrease in abrasion resistance performance, it is preferably less than 15 parts by mass, more preferably less than 10 parts by mass, and even more preferably less than 8.0 parts by mass.

[0168] [Other compounding agents] In the rubber composition according to the present embodiment, in addition to the rubber component and the filler, compounding agents generally used in the conventional tire industry, for example, plasticizers, vulcanized rubber particles, processing aids, waxes, anti-aging agents, stearic acid, zinc oxide, vulcanizing agents, vulcanization accelerators, etc. can be appropriately contained.

[0169] [Plasticizer] A plasticizer is a material that imparts plasticity to the rubber component, and is a concept including both plasticizers that are liquid at 25°C and plasticizers that are solid at normal temperature (25°C). Examples of plasticizers include resin components, oils, liquid rubbers, ester-based plasticizers, etc. These plasticizers may be derived from mineral resources such as petroleum and natural gas, may be derived from biomass, or may be derived from naphtha recycled from rubber products and non-rubber products. Further, low-molecular-weight hydrocarbon components obtained by pyrolyzing and extracting used tires and products containing various components may be used as plasticizers. These plasticizers may be used alone or in combination of two or more.

[0170] (Resin component) The resin component is not particularly limited, and resin components commonly used in the tire industry can be used. For example, tacky resins such as dicyclopentadiene resins, aromatic vinyl resins, C9 resins, C5 resins, C5-C9 resins, coumarone resins, indene resins, terpene resins, rosin resins, and phenolic resins can be mentioned. These resin components may be used alone or in combination of two or more. The rubber composition according to this embodiment preferably contains one or more resin components selected from the group consisting of dicyclopentadiene resins, aromatic vinyl resins, and terpene resins, more preferably contains a dicyclopentadiene resin, and even more preferably contains a resin component containing dicyclopentadiene, styrene, and indene as monomer components.

[0171] ≪Dicyclopentadiene Resin≫ The "dicyclopentadiene resin" refers to a resin containing cyclopentadiene (CPD) or dicyclopentadiene (DCPD) as monomer components, and those obtained by hydrogenating or modifying them may also be used. Examples of the dicyclopentadiene resin include DCPD / C9 resins containing dicyclopentadiene and the C9 fraction described below as monomer components (the DCPD / C9 resin may be hydrogenated or modified), DCPD / C9 resins containing dicyclopentadiene and styrene as monomer components are preferred, and DCPD / C9 resins containing dicyclopentadiene, styrene, and indene as monomer components are more preferred. As the dicyclopentadiene resin, for example, those commercially available from ExxonMobil, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., etc. can be used. These dicyclopentadiene resins may be used alone or in combination of two or more.

[0172] ≪Aromatic Vinyl Resin≫ The term "aromatic vinyl resin" refers to a resin containing an aromatic vinyl compound such as styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc. as the monomer component with the highest content, and those obtained by hydrogenating or modifying them may also be used. As the aromatic vinyl resin, due to economic reasons, easy processing, and excellent heat generation properties, 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. As the aromatic vinyl resin, for example, those commercially available from companies such as Kreton, Eastman Chemical, and Mitsui Chemicals, Inc. can be used. These aromatic vinyl resins may be used alone or in combination of two or more.

[0173] ≪C9 resin≫ The term "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, which may be a polymer of the C9 fraction alone or a copolymer obtained by copolymerizing the C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) and a C9 fraction is called a DCPD / C9 resin. Also, those obtained by hydrogenating or modifying them may be used. Examples of the C9 fraction include petroleum fractions corresponding to 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene. These C9 resins may be used alone or in combination of two or more.

[0174] ≪C5 resin≫ The term "C5 resin" refers to a resin obtained by polymerizing a C5 fraction, and those obtained by hydrogenating or modifying them may also be used. Examples of the C5 fraction include petroleum fractions corresponding to 4 to 5 carbon atoms such as cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, and pentadiene. These C5 resins may be used alone or in combination of two or more.

[0175] ≪C5C9 resin≫ The "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and it may be hydrogenated or modified. As the C5C9 petroleum resin, for example, those commercially available from Tosoh Corporation, LUHUA Co., Ltd., etc. can be used. These C5C9 resins may be used alone or in combination of two or more.

[0176] ≪Coumarone resin≫ The "coumarone resin" refers to a resin containing coumarone as a monomer component, and it may be hydrogenated or modified. Examples of the coumarone resin include coumarone-indene resin containing coumarone and indene as monomer components, coumarone-indene-styrene resin containing coumarone, indene, and styrene as monomer components, etc. These coumarone resins may be used alone or in combination of two or more.

[0177] ≪Indene resin≫ The "indene resin" refers to a resin containing indene as a monomer component, and it may be hydrogenated or modified. Examples of the indene resin include coumarone-indene resin containing coumarone and indene as monomer components, coumarone-indene-styrene resin containing coumarone, indene, and styrene as monomer components, etc. These indene resins may be used alone or in combination of two or more.

[0178] ≪Terpene resin≫ The term "terpene resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, dipentene, etc. as the monomer component with the highest content, and those obtained by hydrogenating or modifying them may also be included. Specific examples of terpene resins include, for example, polyterpene resins containing only one or more of the above terpene compounds as monomer components; aromatic-modified terpene resins containing the terpene compounds and aromatic compounds as monomer components; terpene-phenol resins containing the terpene compounds and phenolic compounds as monomer components, and the like. Examples of aromatic compounds serving as monomer components of aromatic-modified terpene resins include styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. Examples of phenolic compounds serving as monomer components of terpene-phenol resins include phenol, bisphenol A, cresol, xylenol, etc. These terpene resins may be used alone or in combination of two or more.

[0179] ≪Rosin resin≫ The term "rosin resin" refers to a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc., and those obtained by hydrogenating or modifying them may also be included. Rosin resins are not particularly limited, and examples include natural resin rosin, rosin-modified resins obtained by modifying it by hydrogenation, disproportionation, dimerization, esterification, etc. These rosin resins may be used alone or in combination of two or more.

[0180] ≪Phenolic resin≫ The term "phenolic resin" refers to a resin containing phenolic compounds such as phenol, cresol, etc. as the monomer component with the highest content. Phenolic resins are not particularly limited, and examples include phenol-formaldehyde resins, alkylphenol-formaldehyde resins, alkylphenol-acetylene resins, oil-modified phenol-formaldehyde resins, etc. These phenolic resins may be used alone or in combination of two or more.

[0181] ≪Softening point≫ From the viewpoint of wet grip performance, the softening point of the resin component is preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher. Further, from the viewpoints of processability and improvement in the dispersibility of the rubber component and the filler, it is preferably 150°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower. The softening point of the resin is measured by the above measurement method.

[0182] ≪Content≫ The total content of the resin component with respect to 100 parts by mass of the rubber component is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, still more preferably 30 parts by mass or more, and particularly preferably 35 parts by mass or more. On the other hand, from the viewpoint of suppressing heat generation, the content is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and even more preferably 60 parts by mass or less.

[0183] (Oil) Examples of the oil include mineral oil, vegetable oil, animal oil, etc. Further, from the viewpoint of life cycle assessment, waste oil used in a rubber mixer or an engine, or refined waste cooking oil used in a cooking shop may be used.

[0184] In this specification, the mineral oil refers to an oil derived from mineral resources such as petroleum and natural gas. Examples of the mineral oil include paraffinic oil (mineral oil), naphthenic oil, aromatic oil, etc. Specific examples of the mineral oil include, for example, MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. Further, an oil with a low content of polycyclic aromatic (PCA) compounds can also be used for environmental measures. Examples of the low PCA content oil include MES, TDAE, heavy naphthenic oil, etc.

[0185] In this specification, the "vegetable oil" includes, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grape seed oil, wood wax, etc. Further, as the vegetable oil, there may be mentioned refined oils (such as salad oil) obtained by refining the above oils, transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, heat-polymerized oils obtained by heat-polymerizing the above oils, oxidation-polymerized oils obtained by oxidizing the above oils, waste cooking oils recovered from those used as edible oils, etc. Note that the vegetable oil may be liquid or solid at normal temperature (25°C). These vegetable oils may be used alone or in combination of two or more.

[0186] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxy group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited, and may be any of 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, and triacylglycerol. Further, the acylglycerol may be a monomer, a dimer, or a multimer of three or more. Note that acylglycerols of two or more can be obtained by heat polymerization, oxidation polymerization, etc. Also, the acylglycerol may be liquid or solid at normal temperature (25°C).

[0187] The method for confirming whether the above acylglycerol is contained in the rubber composition is not particularly limited, but for example, the following 1 can be confirmed by 1H-NMR measurement. Specifically, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at normal temperature (25°C) for 24 hours. After removing the rubber composition, at room temperature 1When measuring 1H-NMR and setting the signal of tetramethylsilane (TMS) to 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm were observed, and these signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" means a range of ±0.10 ppm.

[0188] The fatty acid is not particularly limited and may be 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.

[0189] Among them, as the fatty acid, it is desirable to contain a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As the vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or a vegetable oil subjected to modification such as transesterification may be used. In addition, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by variety improvement, genetic recombination, etc.

[0190] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0191] Examples of animal oils include fish oil, beef tallow, or oleyl alcohol that can be derived therefrom.

[0192] From the viewpoint of the effects of the present invention, the content of the oil based on 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more. Also, the content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less.

[0193] (Liquid rubber) The liquid rubber is not particularly limited as long as it is a polymer in a liquid state at normal temperature (25°C). Examples include liquid butadiene rubber (liquid BR), liquid styrene-butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene-isoprene rubber (liquid SIR), liquid farnesene rubber, etc. These liquid rubbers may be used alone or in combination of two or more.

[0194] (Ester plasticizer) Examples of the ester plasticizer include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), bis(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), trixylenyl phosphate (TXP), etc. The ester plasticizer may be used alone or in combination of two or more.

[0195] The content of the plasticizer with respect to 100 parts by mass of the rubber component (the total amount of all when using a plurality of plasticizers in combination) is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, further preferably 40 parts by mass or more, and particularly preferably 50 parts by mass or more from the viewpoint of wet grip performance. From the viewpoint of processability, it is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, further preferably 80 parts by mass or less, and particularly preferably 70 parts by mass or less.

[0196] (Vulcanized rubber particles) The vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder etc. specified in JIS K 6316:2017 can be used. From the viewpoints of environmental consideration and cost, recycled rubber powder produced from crushed waste tires etc. is preferred. These may be used alone or in combination of two or more kinds.

[0197] The vulcanized rubber particles are not particularly limited, and may be non-modified vulcanized rubber particles or modified vulcanized rubber particles. As commercially available products of vulcanized rubber, for example, products of Lehigh, Murakami Rubber Industry Co., Ltd. etc. can be used.

[0198] When containing vulcanized rubber particles, the content relative to 100 parts by mass of the rubber component can be appropriately adjusted, for example, in the range of more than 1 part by mass and less than 80 parts by mass.

[0199] (Processing aid) Examples of the processing aid include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, mixtures of fatty acid metal salts and fatty acid amides etc. As the processing aid, for example, those commercially available from Schill+Seilacher, Performance Additives etc. can be used. These processing aids may be used alone or in combination of two or more kinds.

[0200] When containing the processing aid, from the viewpoint of exerting the effect of improving processability, the content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1 part by mass, and even more preferably more than 1.5 parts by mass. Also, from the viewpoints of abrasion resistance and breaking strength, it 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.

[0201] (Wax) The wax is not particularly limited, and any wax commonly used in the tire industry can be preferably used. Examples include mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among them, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, candelilla wax, etc. Examples of mineral waxes include paraffin wax, microcrystalline wax, and their selected special waxes, etc., and paraffin wax is preferred. Note that the wax according to this embodiment does not contain stearic acid. As the wax, for example, those commercially available from Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramoelt Co., etc. can be used. These waxes may be used alone or in combination of two or more.

[0202] When containing wax, the content based on 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 part by mass from the viewpoint of the weather resistance of the rubber. Also, from the viewpoint of preventing the whitening of the tire due to blooming, it is preferably less than 10 parts by mass, more preferably less than 7.0 parts by mass, and even more preferably less than 5.0 parts by mass.

[0203] (Antioxidant) The anti-aging agent is not particularly limited, but examples include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based anti-aging agents such as 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), N,N'-ditoly-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bis, tris, polyphenol-based anti-aging agents such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercial products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys Co., etc. can be used. These anti-aging agents may be used alone or in combination of two or more kinds.

[0204] When containing an anti-aging agent, the content per 100 parts by mass of the rubber component (the total amount of all when using a plurality of anti-aging agents in combination) is preferably more than 1.0 part by mass, more preferably more than 2.0 part by mass, and even more preferably more than 2.5 part by mass from the viewpoint of ozone crack resistance of the rubber. Also, from the viewpoints of abrasion resistance performance and wet grip performance, it 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.

[0205] (Stearic acid) When containing stearic acid, the content with respect to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and still more preferably more than 1.5 parts by mass from the viewpoint of processability. Also, from the viewpoint of vulcanization rate, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and still more preferably less than 5.0 parts by mass.

[0206] (Zinc oxide) When containing zinc oxide, the content with respect to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and still more preferably more than 1.5 parts by mass from the viewpoint of processability. Also, from the viewpoint of abrasion resistance performance, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and still more preferably less than 5.0 parts by mass.

[0207] (Vulcanizing agent) As the vulcanizing agent, sulfur is preferably used. As sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, etc. can be used.

[0208] When containing sulfur as the vulcanizing agent, the content with respect to 100 parts by mass of the rubber component is preferably more than 0.1 part by mass, more preferably more than 0.5 part by mass, and still more preferably more than 1.0 part by mass from the viewpoint of ensuring a sufficient vulcanization reaction. Also, from the viewpoint of deterioration prevention, it is preferably less than 5.0 parts by mass, more preferably less than 3.0 parts by mass, and still more preferably less than 2.0 parts by mass. In addition, when using oil-containing sulfur as the vulcanizing agent, the content of the vulcanizing agent is the total content of pure sulfur contained in the oil-containing sulfur.

[0209] As a vulcanizing agent other than sulfur, known organic crosslinking agents can also be used. The organic crosslinking agent is not particularly limited as long as it can form a crosslinking chain other than a polysulfide bond. For example, alkylphenol-sulfur chloride condensates, sodium 1,6-hexamethylene-dithiolsulfate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, dicumyl peroxide, etc. can be mentioned, and 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane is preferred. These organic crosslinking agents can be those commercially available from Taoka Chemical Industry Co., Ltd., Rancess Co., Ltd., Flexsys Co., etc.

[0210] (Vulcanization accelerator) The vulcanization accelerator is not particularly limited. For example, sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiuram-based vulcanization accelerators, thiourea-based vulcanization accelerators, dithiocarbamate-based vulcanization accelerators, aldehyde-amine-based vulcanization accelerators, aldehyde-ammonia-based vulcanization accelerators, imidazoline-based vulcanization accelerators, xanthate-based vulcanization accelerators, caprolactam disulfide, etc. can be mentioned. These vulcanization accelerators can be used alone or in combination of two or more. Among them, from the viewpoint of more suitably obtaining the desired effect, one or more vulcanization accelerators selected from the group consisting of sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, and guanidine-based vulcanization accelerators are preferred.

[0211] Examples of the sulfenamide-based vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), etc.

[0212] Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole (MBT) or its salts, di-2-benzothiazolyldisulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio)benzothiazole, and the like.

[0213] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, the di-o-tolylguanidine salt of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, and the like.

[0214] Examples of thiuram-based vulcanization accelerators include tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetramethylthiuram monosulfide (TMTM), dipentamethylenethiuram disulfide, dipentamethylenethiuram tetrasulfide, and the like.

[0215] Examples of thiourea-based vulcanization accelerators include thiourea compounds such as thiocarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea, diorthotolylthiourea, N,N'-diphenylthiourea, trimethylthiourea, N,N'-diethylthiourea, and the like.

[0216] 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), tellurium diethyldithiocarbamate (TeEDC), and the like.

[0217] When containing a vulcanization accelerator, the content with respect to 100 parts by mass of the rubber component (the total amount of all when using a plurality of vulcanization accelerators in combination) is preferably more than 3.0 parts by mass, more preferably more than 4.0 parts by mass, and even more preferably 5.0 parts by mass or more. Also, the content of the vulcanization accelerator with respect to 100 parts by mass of the rubber component is preferably less than 8.0 parts by mass, more preferably less than 7.0 parts by mass, and even more preferably less than 6.0 parts by mass.

[0218] In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, anti-aging agent, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the various materials from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process of synthesizing methane from carbon dioxide may be converted.

[0219] [Manufacturing] The rubber composition according to this embodiment can be manufactured by a known method. For example, it can be manufactured by kneading the above-mentioned respective components using a rubber kneading device such as an open roll, a closed kneader (Banbury mixer, kneader, etc.).

[0220] The kneading process includes, for example, a base kneading process of kneading compounding agents and additives other than vulcanizing agents and vulcanization accelerators, and a final kneading (F kneading) process of adding and kneading vulcanizing agents and vulcanization accelerators to the kneaded product obtained in the base kneading process. Further, the base kneading process can be divided into a plurality of processes if desired. When dividing the base kneading process, the method may be (1) a method in which a part of the compounding agents and additives is kneaded in advance to form a masterbatch, and then the remaining compounding agents and additives are added to the obtained masterbatch and kneaded, or (2) a method in which all the compounding agents and additives kneaded in the base kneading process are kneaded at once, and then the mill of the kneaded product is performed one or more times. In the method (1) above, the number of masterbatches is not limited and may be two or more. Further, when the number of masterbatches is two or more, all the compounding agents and additives used in the base kneading process may be allocated to any one of the masterbatches.

[0221] The kneading conditions are not particularly limited. For example, in the base kneading process, kneading is performed at a discharge temperature of 150 to 170°C for 3 to 10 minutes, and in the final kneading process, kneading is performed at 70 to 110°C for 1 to 5 minutes. The vulcanization conditions are not particularly limited. For example, a method of vulcanizing at 150 to 200°C for 10 to 30 minutes can be mentioned.

[0222] The tire according to this embodiment having a tread portion composed of the above rubber composition can be manufactured by a normal method. That is, the tire is obtained by extruding an unvulcanized rubber composition prepared by blending the above components with the rubber component as needed into the shape of the tread portion, and then laminating and molding the obtained tread portion together with other tire members on a tire molding machine by a normal method to form an unvulcanized tire, and the unvulcanized tire thus obtained can be manufactured by heating and pressurizing it in a vulcanizer. The vulcanization conditions are not particularly limited. For example, a method of vulcanizing at 150 to 200°C for 10 to 30 minutes can be mentioned.

[0223] [Use] The tire according to this embodiment can be used for any application, 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, a run-flat tire. Note that a passenger car tire is a tire assumed to be mounted on an automobile that runs on four wheels and has a maximum load capacity of less than 1400 kg. Also, a heavy-duty tire refers to a tire with a maximum load capacity of 1400 kg or more. Further, the tire according to this embodiment can be used for all-season tires, summer tires, and winter tires such as studless tires in addition to these.

Examples

[0224] Hereinafter, examples (Examples) considered to be preferable in implementation are shown, but the scope of the present invention is not limited to the Examples. Using the various chemicals shown below, the tires obtained according to Table 1 or Table 2 were examined, and the results calculated based on the following evaluation methods are shown in Tables 1 to 2.

[0225] <Various Chemicals> NR: TSR20 SBR1: SBR manufactured according to the following Production Example 1 (S-SBR, Tg: -50°C, styrene content: 25% by mass, vinyl content: 25 mol%, Mw: 1 million, non-oil extended) SBR2: SBR manufactured according to the following Production Example 2 (S-SBR, Tg: -60°C, styrene content: 20% by mass, vinyl content: 20 mol%, Mw: 700,000, non-oil extended) SBR3: Toughlene 3830 manufactured by Asahi Kasei Corporation (unmodified S-SBR, Tg: -35°C, styrene content: 36% by mass, vinyl content: 31 mol%, Mw: 420,000, containing 37.5 parts by mass of oil-extended oil per 100 parts by mass of rubber solids) BR: UBEPOL BR (registered trademark) 150B manufactured by UBE Industries, Ltd. (unmodified BR, cis content: 97% by mass, Mw: 440,000) Carbon Black: Prototype Carbon Black (N2SA: 180m 2 / g, Average primary particle size: 16 nm) Silica 1: Ultrasil VN3 manufactured by Evonik Degussa (N2SA: 175 m 2 / g, Average primary particle size: 15 nm) Silica 2: Ultrasil 9100GR manufactured by Evonik Degussa (N2SA: 230 m 2 / g, Average primary particle size: 15 nm) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Resin component 1: SYLVATRAXX 4401 manufactured by Cray Valley (α-methylstyrene resin, softening point: 85 °C) Resin component 2: SYLVATRAXX 4150 manufactured by Cray Valley (polyt terpene resin, softening point: 115 °C) Resin component 3: Oppera PR395 manufactured by ExxonMobil (hydrogenated DCPD / C9 resin, resin containing dicyclopentadiene, styrene, and indene as monomer components, softening point: 118 °C) Oil: VivaTec 500 (TDAE oil) manufactured by H&R Co., Ltd. Wax: Oz Ace 0355 (paraffin wax) manufactured by Nippon Seiro Co., Ltd. Antioxidant 1: No Crack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant 2: No Crack RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: Tsubaki Bead Stearic Acid manufactured by NOF Corporation Zinc oxide: Zinc White No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (5% oil-containing powdered sulfur) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Nozeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Nozeller D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0226] (Production Example 1: Production of SBR1) Charge a nitrogen-substituted autoclave reactor with cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene. Adjust the ratio of styrene and 1,3-butadiene so that the styrene content is 25% by mass. After adjusting the temperature of the reactor contents to 20°C, add n-butyllithium to initiate polymerization. Polymerize under adiabatic conditions, and the maximum temperature reaches 80°C. After confirming the formation of a polymer with Mw of 1 million by GPC, pour the polymerization solution into 4 L of ethanol and recover the precipitate. After drying the obtained precipitate by blowing air, perform vacuum drying at 80°C / 10 Pa or less until the mass loss on drying becomes 0.1% to obtain SBR1.

[0227] (Production Example 2: Production of SBR2) Charge a nitrogen-substituted autoclave reactor with cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene. Adjust the ratio of styrene and 1,3-butadiene so that the styrene content is 20% by mass. After adjusting the temperature of the reactor contents to 20°C, add n-butyllithium to initiate polymerization. Polymerize under adiabatic conditions, and the maximum temperature reaches 80°C. After confirming the formation of a polymer with Mw of 700,000 by GPC, pour the polymerization solution into 4 L of ethanol and recover the precipitate. After drying the obtained precipitate by blowing air, perform vacuum drying at 80°C / 10 Pa or less until the mass loss on drying becomes 0.1% to obtain SBR2.

[0228] (Examples and Comparative Examples) According to the formulation shown in Table 1 or Table 2, using a 1.7L sealed Banbury mixer, chemicals other than sulfur and vulcanization accelerators are kneaded at a discharge temperature of 160°C for 4 minutes to obtain a kneaded product. Next, using an open roll, sulfur and vulcanization accelerators are added to the obtained kneaded product and kneaded until it reaches 105°C for 4 minutes to obtain an unvulcanized rubber composition. Using the obtained unvulcanized rubber composition, it is molded according to the shape of the tread portion and bonded together with other tire members to produce an unvulcanized tire, which is vulcanized at 170°C to obtain each test tire (size: 205 / 65R15, rim: 15×6JJ, internal pressure: 230 kPa). The thickness t1 of the cap rubber layer is 6.5 mm, the thickness B of the belt layer is 1.0 mm, and the groove depth at the deepest part of the circumferential groove existing in the shoulder region is 6.0 mm. The transverse groove existing in the center region is a widened groove having the cross-sectional shape shown in FIG. 4.

[0229] <Measurement of Acetone Extraction Amount (AE)> Regarding the rubber test pieces prepared by cutting from the tread portion of each test tire, the AE amount of each is measured. The AE amount can be obtained by immersing each rubber test piece in acetone at room temperature (around 25°C) for 24 hours to extract the soluble components, measuring the mass of each test piece before and after extraction, and using the following formula. Acetone extraction amount (mass%) = {(mass of the vulcanized rubber test piece before extraction - mass of the vulcanized rubber test piece after extraction) / (mass of the rubber test piece before extraction)} × 100

[0230] <Temperature Distribution Curve of tanδ> Regarding each rubber test piece prepared by cutting from the tread portion of each test tire with a length of 20 mm × width of 4 mm × thickness of 1 mm such that the tire circumferential direction is the long side and the tire radial direction is the thickness direction, using a dynamic viscoelasticity measuring device (Iplexer series manufactured by GABO), under the 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, in the temperature range from -20°C to 70°C, the temperature distribution curve of tanδ is measured. Then, based on the obtained temperature distribution curve of tanδ, the tanδ and the half-width at the peak position within the range of -20°C to -70°C are measured.

[0231] <Measurement of tanδ at 30°C and E* at 30°C> For each rubber test piece prepared by cutting out from the tread part of each test tire with a length of 20 mm × width of 4 mm × thickness of 1 mm such that the tire circumferential direction is the long side and the tire radial direction is the thickness direction, using a dynamic viscoelasticity measuring device (Implex series manufactured by GABO), the loss tangent tanδ and the complex elastic modulus E* are measured under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and an elongation mode.

[0232] <Measurement of glass transition temperature (Tg) of rubber composition> For each rubber test piece prepared by cutting out from the tread part of each test tire with a length of 20 mm × width of 4 mm × thickness of 1 mm such that the tire circumferential direction is the long side and the tire radial direction is the thickness direction, using a dynamic viscoelasticity measuring device (Implex series manufactured by GABO), the temperature distribution curve of tanδ in the range of -60°C to 40°C is measured under the 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 the temperature (tanδ peak temperature) corresponding to the largest tanδ value in the obtained temperature distribution curve is determined as the Tg of the rubber composition.

[0233] <Abrasion resistance performance> For each vulcanized rubber test piece prepared by cutting out a test piece with a length of 20 mm × width of 4 mm × thickness of 1 mm from the tread part of each test tire such that the tire circumferential direction is the long side, using a LAT tester (Laboratory Abrasion and Skid Tester), the volume loss amount of each test piece is measured under the conditions of a load of 100 N, a speed of 20 km / h, and a slip angle of 6°, and the abrasion resistance performance of each tire is expressed as an index by the following calculation formula. The larger the index, the better the abrasion resistance performance. Abrasion resistance performance = (Volume loss amount of Comparative Example 3) / (Volume loss amount of each test piece) × 100

[0234] <Wet grip performance> Each test tire is mounted on each of the four wheels of a FF passenger car with a displacement of 2000 cc, and on a wet asphalt road surface, the braking distance from the point where the brakes are applied at a speed of 100 km / h is measured. Taking the braking distance of the test tire of Comparative Example 3 as 100, the wet grip performance of each tire is expressed as an index according to the following calculation formula. The larger the index, the better the wet grip performance is indicated. (Wet grip performance index) = (Braking distance of the tire of Comparative Example 3) / (Braking distance of each test tire) × 100

[0235] <Overall performance> The total value of the above abrasion resistance performance and wet grip performance is shown as the overall performance index.

[0236]

Table 1

[0237]

Table 2

[0238] <Embodiment> Examples of embodiments of the present invention are shown below.

[0239] 〔1〕A tire having a tread portion, wherein the tread portion has one or more circumferential grooves, the tread portion is composed of a rubber composition containing a rubber component and silica, the rubber component contains an isoprene-based rubber and a styrene-butadiene rubber, the content of the isoprene-based rubber in the rubber component is 40% by mass or more, the styrene content S1 (% by mass) of the styrene-butadiene rubber is 30 or less, the content of the silica with respect to 100 parts by mass of the rubber component is 80 parts by mass or more, the acetone extraction amount AE (% by mass) of the rubber composition is more than 17.0% by mass, the half-value width of the peak in the range of -20°C to -70°C in the tanδ temperature distribution curve of the rubber composition is 35°C or more, when the complex elastic modulus at 30°C of the rubber composition is 30°C E* and the groove depth at the deepest part of the circumferential groove is H (mm), 30°C E* / H is 1.30 or more. 〔2〕The tire according to the above 〔1〕, wherein S1 is 22 or less. 〔3〕The tire according to the above 〔1〕 or 〔2〕, wherein the average primary particle diameter of the silica is 18 nm or less. 〔4〕The tire according to any one of the above 〔1〕 to 〔3〕, wherein the rubber composition contains one or more resin components selected from the group consisting of terpene resins, C9 resins, dicyclopentadiene resins, and aromatic vinyl resins. 〔5〕The tire according to any one of the above 〔1〕 to 〔4〕, wherein the rubber composition contains a resin component containing dicyclopentadiene, styrene, and indene as monomer components. 〔6〕The tire according to any one of the above 〔1〕 to 〔5〕, wherein 30°C E* is 8.0 MPa or more. 〔7〕The tire according to any one of the above 〔1〕 to 〔6〕, wherein 30°C E* / H is 1.30 or more. 〔8〕The tire according to any one of the above 〔1〕 to 〔7〕, wherein the total styrene amount S2 (% by mass) in the rubber component is 15 or less. 〔9〕The tire according to any one of the above 〔1〕 to 〔8〕, when the tanδ at 30°C of the rubber composition is 30°C tanδ and the total thickness of the tread portion is T (mm), 30°C tanδ × T is 2.5 or more and 4.5 or less. 〔10〕The tire according to any one of the above 〔1〕 to 〔9〕, wherein the rubber composition contains 20 parts by mass or more of carbon black with respect to 100 parts by mass of the rubber component. 〔11〕The tire according to any one of the above 〔1〕 to 〔10〕, wherein when the land ratio of the tread portion is R, S1 × R is 11.0 or more. 〔12〕The tire according to any one of the above 〔1〕 to 〔11〕, wherein when the tire weight is G (kg), S1 / G is 3.0 or less. 〔13〕The tread portion has a land portion partitioned by the one or more circumferential grooves, the land portion has a lateral groove extending toward the inner side in the tire radial direction, and at least one of the lateral grooves has a groove width wider than the groove width on the tread surface at the inner side in the tire radial direction. The tire according to any one of the above 〔1〕 to 〔12〕. 〔14〕On the tread surface of the tread portion, when a region of 30% of the tread contact width centered on the tire equator is defined as the center region, and regions on both outer sides of the center region and within the tread contact width are defined as a pair of shoulder regions, the groove depth at the deepest part of the circumferential groove existing in the shoulder region is 6.0 mm or more. The tire according to any one of the above 〔1〕 to 〔13〕. 〔15〕The tire according to any one of the above 〔1〕 to 〔14〕, wherein when the thickness of the layer whose outer surface constitutes the tread surface in the tread portion is t1 (mm) and the thickness of the belt layer is B (mm), B is 0.9 or more and 1.2 or less, and t1 / B is 7.0 or less.

Explanation of reference numerals

[0240] 1 Tread portion 2 Sidewall portion 3 Bead portion 4 Carcass 5 Belt layer 6 Band layer 7 Inner liner 8 Rim 9 Rim chafer 10 Clinch portion 11 Layer whose outer surface constitutes the tread surface (cap rubber layer) 12 Base rubber layer 13 bead apex 14 bead core CL tire equator H groove depth at the deepest part of the circumferential groove P midpoint in the tire width direction N line perpendicular to the tangent plane at point P T total thickness of the tread portion B thickness of the belt layer t1 thickness of the layer (cap rubber layer) whose outer surface forms the tread surface t2 thickness of the base rubber layer 15 circumferential groove 16 tread surface 17 straight line connecting the ends of the circumferential groove 18 extension line of the outer surface of the base rubber layer 19 extension line of the lowest part of the circumferential groove 20 land portion 21 center land portion 22 shoulder land portion 31 lateral groove 32 lateral groove TW tread contact width CR center region SR shoulder region Te tread contact end 40 groove bottom 41 groove edge 42 groove wall W1 opening width (groove width at the tread surface) C1 amount of indentation from the groove edge at the groove bottom C2 amount of indentation from the groove edge at the groove bottom

Claims

1. A tire having a tread portion, wherein the tread portion has one or more circumferential grooves, the tread portion is composed of a rubber composition containing a rubber component and silica, the rubber component contains an isoprene-based rubber and a styrene-butadiene rubber, the content of the isoprene-based rubber in the rubber component is 40% by mass or more, the styrene content S1 (% by mass) of the styrene-butadiene rubber is 30 or less, the content of the silica is 80 parts by mass or more with respect to 100 parts by mass of the rubber component, the acetone extraction amount AE (% by mass) of the rubber composition is more than 17.0% by mass, the half-value width of the peak in the range of -20°C to -70°C in the tanδ temperature distribution curve of the rubber composition is 35°C or more, when the complex elastic modulus of the rubber composition at 30°C is 30°C E*, and the groove depth at the deepest part of the circumferential groove is H (mm), 30°C E* / H is 1.30 or more, a tire.

2. The tire according to claim 1, wherein S1 is 22 or less.

3. The tire according to claim 1 or 2, wherein the average primary particle diameter of the silica is 18 nm or less.

4. The tire according to claim 1 or 2, wherein the rubber composition contains one or more resin components selected from the group consisting of terpene resins, C9 resins, dicyclopentadiene resins, and aromatic vinyl resins.

5. The tire according to claim 1 or 2, wherein the rubber composition contains a resin component containing dicyclopentadiene, styrene, and indene as monomer components.

6. The tire according to claim 1 or 2, wherein 30°C E* is 8.0 MPa or more.

7. The tire according to claim 1 or 2, wherein 30°C E* / H is 1.30 or more.

8. The tire according to claim 1 or 2, wherein the total styrene amount S2 (% by mass) in the rubber component is 15 or less.

9. The tire according to claim 1 or 2, when the tanδ of the rubber composition at 30°C is 30°C tanδ and the total thickness of the tread portion is T (mm), 30°C tanδ × T is 2.5 or more and 4.5 or less.

10. The tire according to claim 1 or 2, wherein the rubber composition contains 20 parts by mass or more of carbon black with respect to 100 parts by mass of the rubber component.

11. The tire according to claim 1 or 2, when the land ratio of the tread portion is R, S1 × R is 11.0 or more.

12. The tire according to claim 1 or 2, wherein when the tire weight is G (kg), S1 / G is 3.0 or less.

13. The tread portion has land portions partitioned by the one or more circumferential grooves, the land portions have lateral grooves extending toward the inner side in the tire radial direction, the tire according to claim 1 or 2, wherein at least one of the lateral grooves has a groove width wider than the groove width on the tread surface at the inner side in the tire radial direction.

14. When, on the tread surface of the tread portion, a region of 30% of the tread contact width centered on the tire equator is defined as a center region, and regions outside both sides of the center region and within the tread contact width are defined as a pair of shoulder regions, the depth of the deepest part of the circumferential grooves present in the shoulder regions is 6.0 mm or more. The tire according to claim 1 or 2.

15. The tire according to claim 1 or 2, wherein when the thickness of the layer whose outer surface constitutes the tread surface of the tread portion is t1 (mm) and the thickness of the belt layer is B (mm), B is 0.9 or more and 1.2 or less, and t1 / B is 7.0 or less.

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