tire

Abstract

To provide a tire improved in integrated performance of slow 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. Contents of the silica with respect to 100 parts by mass of the rubber constituents are 70 parts by mass or more. Styrene contents S1 (mass%) of the styrene-butadiene rubber are 30 or less, and acetone extracted volumes AE (mass%) of the rubber compositions are more than 17.0. 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 45°C or higher. When a groove depth of a deepest part of the circumferential groove is defined as H (mm) and tanδ at -10°C of the rubber compositions is defined as -10°Ctanδ, -10°Ctanδ×H is equal to 1.7 or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] Patent Document 1 describes a tire having inclined grooves in a tread portion and having a rubber composition constituting the tread rubber with a parameter obtained by van der Waals force when scanned at a predetermined temperature using an atomic force microscope within a predetermined range, which provides a tire with improved wet grip performance and ice grip performance in a well-balanced manner.

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 snow performance and wet grip performance has been desired.

[0005] An object of the present invention is to provide a tire with improved overall performance of snow performance 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 isoprene rubber and styrene-butadiene rubber, the content of isoprene rubber in the rubber component is 40% by mass or more, The content of the silica is 70 parts by mass or more with respect to 100 parts by mass of the rubber component, the styrene content S1 (mass %) of the styrene-butadiene rubber is 30 or less, the acetone extraction amount AE (mass %) of the rubber composition exceeds 17.0, the half-value width of the peak within the range of -20°C to -70°C in the tanδ temperature distribution curve of the rubber composition is 45°C or more, the groove depth at the deepest part of the circumferential groove is H (mm), when the tanδ at -10°C of the rubber composition is defined as -10°C tanδ, a tire in which -10°C tanδ × H is 1.7 or more.

Advantages of the Invention

[0007] According to the present invention, there is provided a tire with improved overall performance of snow performance and wet grip performance.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

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. 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 content of the silica is 70 parts by mass or more with respect to 100 parts by mass of the rubber component. The styrene content S1 (mass%) of the styrene-butadiene rubber is 30 or less. The acetone extraction amount AE (mass%) of the rubber composition exceeds 17.0. 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 45°C or more. When the groove depth at the deepest part of the circumferential groove is H (mm) and the tanδ at -10°C of the rubber composition is designated as -10°C tanδ, -10°C tanδ × H is 1.7 or more.

[0010] Regarding the reason why the overall performance of the snow performance and the wet grip performance is improved in the tire of the present embodiment, 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 embodiment has the following characteristics: (1) The content of the isoprene rubber is 40% by mass or more, so that a phase of the isoprene rubber with relatively weak interaction with silica is formed in the rubber matrix, and the followability of the rubber composition to the road surface is improved. Further, (2) the content of silica is 70 parts by mass or more with respect to 100 parts by mass of the rubber component, so that the effect of improving the wet grip performance by silica can be obtained, and the tanδ temperature distribution curve can be made gentle. Further, (3) the styrene content S1 (mass%) of the styrene-butadiene rubber is 30 or less, so that minute styrene domains are formed in the rubber matrix, and since the minute domains have flexibility, the mobility of the polymer is improved, and the followability of the rubber composition to the road surface is improved. Also, since the glass transition temperature (Tg) of the rubber composition decreases, the snow performance is improved. Further, (4) the acetone extraction amount AE (mass%) is more than 17.0, so that the efficiency of filler dispersion and distribution is improved, and the rigidity at low temperatures can be lowered. Further, (5) the half-value width of the peak in the range of -20°C to -70°C in the tanδ temperature distribution curve is 45°C or more, so that energy loss can occur in a wide frequency band, and energy loss can also occur widely in the frequency band during braking on snow and wet road surfaces. Further, (6) -10°C tanδ × H is 1.7 or more, so that the hysteresis loss and snow column shear force at low temperatures are improved. And it is considered that the remarkable effect that the overall performance of the snow performance and the wet grip performance is improved is achieved by the cooperation of the above (1) to (6).

[0012] It is preferable that the total styrene amount S2 (mass%) in the rubber component is 15 or less.

[0013] When the total styrene amount S2 is 15% by mass or less, minute styrene domains are formed in the rubber matrix, and since the 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 overall performance of the snow performance and the wet grip performance is further improved.

[0014] The rubber composition preferably contains a resin component containing dicyclopentadiene, styrene, and indene as monomer components.

[0015] By containing the above resin component, the compatibility with isoprene rubber or styrene-butadiene rubber decreases, so the tanδ temperature distribution curve can be made gentle, and it is considered that the overall performance of snow performance and wet grip performance is further improved.

[0016] The tanδ at -10°C of the rubber composition is preferably 0.30 or more. When the tanδ at -10°C is 0.30 or more, it is considered that the snow performance is further improved.

[0017] The tanδ at -10°C × H of the rubber composition is preferably 2.0 or more. When the tanδ at -10°C × H is 2.0 or more, it is considered that the hysteresis loss and snow column shear force at low temperature are further improved.

[0018] The acetone extraction amount of the rubber composition is preferably more than 20.0% by mass. When the acetone extraction amount is more than 20.0% by mass, the efficiency of filler dispersion and distribution becomes better, so the rigidity at low temperature can be further reduced.

[0019] The tanδ at 0°C of the rubber composition is preferably 0.50 or more. When the tanδ at 0°C is 0.50 or more, it is considered that the snow performance is further improved.

[0020] When the total thickness of the tread part is T (mm), the tanδ at -10°C × T is preferably 1.5 or more and 3.5 or less. By setting the tanδ at -10°C × T to 1.5 or more, the hysteresis loss at low temperature is improved, so the snow performance is further improved, and by setting it to 3.5 or less, it is considered that the fuel consumption performance can be ensured.

[0021] Preferably, the rubber composition 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 reinforcing property of the rubber composition is improved, and thus the wear resistance is considered to be further improved.

[0022] When the land ratio of the tread portion is R, it is preferable that S1 × R is 10.0 or more. By S1 × R being 10.0 or more, due to the synergistic effect of the flexibility of the rubber composition and the increase in the ground contact surface of the tread portion, the wet grip performance is considered to be further improved.

[0023] When the tire weight is G (kg), it is preferable that S1 / G is 3.0 or less. As the tire weight decreases, by reducing S1, it becomes easier to improve the handling stability in a low-temperature environment. This is because as the tire becomes lighter, the force pressing the land portion against the road surface becomes smaller, and thus as the tire becomes lighter, even a slight aggregation of the styrene portion has a greater impact on the tread surface.

[0024] The number of the circumferential grooves is 3 or more, and the tread portion has a pair of shoulder land portions partitioned by a pair of outermost circumferential grooves located at the outermost ends in the tire width direction and two or more center land portions located between the pair of shoulder land portions. Preferably, the groove width of at least one of the pair of outermost circumferential grooves is narrower than the groove width of at least one of the circumferential grooves other than the pair of outermost circumferential grooves. Further, at least one of the outermost circumferential grooves having a groove width narrower than at least one of the circumferential grooves other than the outermost circumferential grooves is preferably the outermost circumferential groove on the tread end To side of the pair of outermost circumferential grooves, and more preferably the pair of outermost circumferential grooves on both the tread end To side and the Ti side.

[0025] By dividing the tread portion into four or more parts in the width direction, the load transmitted to each land portion increases, enabling an increase in the pressure with which the rubber surface is pressed against the road surface, and it is considered that the handling stability on snow-covered road surfaces can be further enhanced. Also, when turning, in the tread portion of the tire, the pressure on the outer side in the tire width direction inevitably tends to be high. Therefore, by narrowing the groove width as described above, the reaction force at the shoulder land portion can be increased, and it is considered that it is easier to improve the handling stability on snow-covered road surfaces.

[0026] The rubber composition preferably contains 30 to 70 parts by mass of a softening agent with respect to 100 parts by mass of the rubber component. By containing 30 to 70 parts by mass of the softening agent, the processability of the rubber composition is improved, and the appearance of the tire can also be made good.

[0027] [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%.

[0028] 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)).

[0029] "Total styrene content S2 (mass %) in the rubber component" is the total content (mass %) of the styrene moiety 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 respectively, and the sum of these values is the total styrene content. 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).

[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 total styrene content S2 in 100 mass % of the rubber component is approximately 13.3 mass % (= (25×20 / 100) + (27.5×30 / 100) + (0×10 / 100)).

[0031] "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 according to the following formula. Acetone extraction amount (mass %) = { (mass of the rubber test piece before extraction - mass of the rubber test piece after extraction) / (mass of the rubber test piece before extraction)} × 100

[0032] "The half-width at half maximum of the peak (the half-width at half maximum of the tanδ peak) 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 for the temperature distribution curve of tanδ in the temperature range from -20°C to -70°C 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 using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO), 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. It is defined as the absolute value of the temperature difference between E and F.

[0033] "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 for the temperature distribution curve of tanδ in the temperature range from -20°C to -70°C 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 using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO), and 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.

[0034] "The glass transition temperature (Tg) of the rubber composition" refers to the temperature corresponding to the maximum value within the range of -60°C or higher and 40°C or lower of the temperature distribution curve of tanδ, measured 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 using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO). In the measurement within the range of -60 to 40°C, when the tanδ value continuously increases or decreases with the temperature increase, the glass transition temperature of the rubber composition shall be 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 shall be taken as the glass transition temperature.

[0035] "-10°C tanδ" is the loss tangent (tanδ) measured under the conditions of a temperature of -10°C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±2.5%, and an elongation mode.

[0036] "0°C tanδ" is the loss tangent (tanδ) measured under the conditions of a temperature of 0°C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±2.5%, and an elongation mode.

[0037] The "tread part" is the part that forms the contact surface of the tire. In the radial cross-section of the tire, when it is provided with members that form the tire skeleton by steel or textile materials such as the belt layer, belt reinforcing layer, and carcass layer, it is the member on the outer side in the radial direction of the tire than these.

[0038] The "normal state" refers to a no-load state in which the tire is mounted on a standard rim and filled with air at a standard internal pressure.

[0039] The "dimensions of each part of the tire" are, unless otherwise specified, the values specified in the normal state for those appearing on the outer surface of the tire, while those existing inside the tire are the values specified in the state where the cut tire piece is held in the rim width of the standard rim after cutting the tire with a plane including the tire rotation axis.

[0040] "Normal Rim" refers to the rim defined for each tire in a standard system that includes 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"; and 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 that order, and follow the relevant standards if there are applicable sizes during the reference. In the case of a tire not defined by the above standards, it refers to the rim with the narrowest width among the minimum-diameter rims 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).

[0041] "Normal Internal Pressure" refers to the air pressure defined for each tire in a standard system that includes 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"; and 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 normal rim, refer to JATMA, ETRTO, and TRA in that order, and follow the relevant standards if there are applicable sizes during the reference. In the case of a tire not defined by the above standards, it refers to the normal internal pressure (but not less than 250 kPa) of another tire size described with the normal rim as the standard rim (provided that it is defined by the standards). If there are multiple normal internal pressures not less than 250 kPa, it refers to the minimum value among them.

[0042] The "normal load" refers to the load specified for each tire in a standard system that includes 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"; and 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. When there is an applicable size during the reference, follow the relevant standard. For tires not specified in the above standards, the maximum load capacity W L calculated separately is taken as the normal load.

[0043] The "maximum load capacity W L " is calculated by the following formula. "V" is the virtual volume of the tire (mm 3 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 tire cross-section by a 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 removing patterns or characters on the tire sidewall, etc. Note that the maximum load capacity is synonymous with the above-mentioned normal load.

[0044]

Equation

[0045] A "groove" refers to a recess formed on the tread surface of the tire and extending inward in the tire radial direction, where the groove width (opening width) on the tread surface is 2.0 mm or more. Those less than 2.0 mm are called "sipes".

[0046] A "circumferential groove" refers to a groove that continuously extends in the tire circumferential direction. 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.

[0047] 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 tire radial direction in the cross-section of the tire by the 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 shall be taken as the groove depth of the groove (note that the depth at a point of a three-way intersection or more where a plurality of grooves intersect is excluded from the definition of the groove depth in the present invention).

[0048] The "total thickness T (mm) of the tread portion" is the thickness of the tread portion measured along the normal line on the tire equator in the cross-section of the tire by the plane including the tire rotation axis. When there is a circumferential groove 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 equatorial plane 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 total thicknesses of the tread portion obtained at five positions by rotating the tire by 72° in the circumferential direction.

[0049] 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 a member made of sponge or sealant or a sensor member, etc. is provided in the inner cavity of the tire, the weight including them shall be taken.

[0050] The "contact area" is the area of the tread obtained from the contour when the tire is pressed against the ground. After assembling the tire on a standard rim, applying a standard internal pressure, and leaving it static for 24 hours at 25°C, ink is applied to the tire tread surface, the tire is loaded with a standard load (maximum load capacity) and pressed vertically against thick paper (the camber angle is 0°), and the ink is transferred to obtain it. 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 and performing it at a total of five locations.

[0051] 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 on 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°), and transferring 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 the operation at a total of five locations.

[0052] 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)

[0053] The "land part" is the part of the tread that comes into contact with the ground when the tire is pressed against the ground, and is the part of the tread that constitutes the effective contact area.

[0054] The "tread ends Ti, To" are the outermost contact positions when the maximum load capacity is applied to the tire in its normal state and it contacts the plane at a camber angle of 0 degrees. The tread end Ti represents the tread end that is on the inner side of the vehicle when the tire is mounted on the vehicle, and the tread end To represents the tread end that is on the outer side of the vehicle.

[0055] 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.

[0056] 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.).

[0057] The "styrene content" is 1It is a value calculated by 1H-NMR measurement and is applicable to, for example, a rubber component (styrene unit-containing rubber) having a repeating unit derived from styrene such as SBR.

[0058] The "vinyl content (1,2-bonded butadiene unit amount)" is a value calculated by infrared absorption spectrum analysis in accordance with JIS K 6239-2:2017 and is applicable to, for example, a rubber component having a repeating unit derived from butadiene such as SBR and BR.

[0059] The "cis content (cis-1,4-bonded butadiene unit amount)" is a value calculated by infrared absorption spectrum analysis in accordance with JIS K 6239-2:2017 and is applicable to, for example, a rubber component having a repeating unit derived from butadiene such as BR.

[0060] The "weight average molecular weight (Mw)" can be determined by standard polystyrene conversion based on the measured value 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, softeners, etc.

[0061] The "nitrogen adsorption specific surface area of carbon black (N2SA)" is measured in accordance with JIS K 6217-2:2017. The "nitrogen adsorption specific surface area of silica (N2SA)" is measured by the BET method in accordance with ASTM D3037-93.

[0062] The "average primary particle diameter" is obtained 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×(particle area) / π]. The average primary particle diameter is applicable to silica, carbon black, etc.

[0063] The "content of softening agent" also includes the amount of softening agent contained in the stretched rubber component previously stretched by a softening agent such as oil, resin component, liquid rubber component, etc. The same applies to the content of oil, the content of resin component, and the content of liquid rubber. For example, when the stretching component is oil, the stretched oil is included in the content of oil.

[0064] The "softening point of resin component" is the temperature at which the ball drops, measured by a ring and ball softening point measuring device for the softening point defined in JIS K 6220-1:2015 7.7.

[0065] [Tire] Hereinafter, with reference to the drawings, a tire according to an embodiment of the present invention will be described. Note that the embodiments shown below are merely examples, and the tire of the present invention is not limited to the following embodiments.

[0066] FIG. 1 is a cross-sectional view showing a cross-section passing through the tire rotation axis of the tread portion of the tire. In FIG. 1, 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.

[0067] The tread portion according to the tire of the present invention has at least one or more circumferential grooves 1 (10). The tread portion has land portions 2 partitioned by the circumferential grooves 1 (10) in the tire width direction.

[0068] The groove depth H at the deepest part of the circumferential groove 1 (10) refers to the linear distance between the straight line 4 connecting the ends of the circumferential groove on the tread surface 3 and the extension line 5 of the lowest part of the groove in the tire radial direction. Note that the groove depth H can be, for example, when there are a plurality of circumferential grooves 1 (10), the linear distance between the straight line 4 and the extension line 5 of the lowest part of the circumferential groove 1 (10) (the left circumferential groove 1 in FIG. 1) having the deepest groove depth among the plurality of circumferential grooves 1 (10).

[0069] In the tire of the present invention, it is preferable to dispose a rubber layer made of the above-described predetermined rubber composition in at least a part of the region of the distance H from the tread surface 3 inward in the tire radial direction. The tread portion of the tire according to the present invention has one or more rubber layers, and preferably has two or more rubber layers. When the tread portion has two or more rubber layers, at least one of the two or more rubber layers may be constituted by the above-described predetermined rubber composition.

[0070] In the present invention, from the viewpoint of snow performance, the groove depth H at the deepest part in the circumferential direction is preferably 5.0 mm or more, more preferably 5.5 mm or more, still more preferably 6.0 mm or more, and particularly preferably 6.5 mm or more. Further, 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 8.0 mm or less, still more preferably 7.5 mm or less, and particularly preferably 7.0 mm or less.

[0071] As shown in FIG. 1, the tread portion may have a first layer 6 whose outer surface constitutes the tread surface 3 and a second layer 7 adjacent to the inner side in the radial direction of the first layer 6. One circumferential groove 1(10) shown on the left side of FIG. 1 is formed such that the deepest part of the groove bottom of the circumferential groove 1(10) is located inward in the tire radial direction with respect to the outer surface of the second layer 7. Specifically, the second layer 7 has a recess recessed inward in the tire radial direction with respect to the outer surface, and a part of the first layer 6 is formed in the recess of the second layer 7 with a predetermined thickness. The circumferential groove 1(10) is formed so as to enter the inside of the recess of the second layer 7 beyond the outer surface of the second layer 7. Note that the circumferential groove 1(10) may be formed to have a groove depth that does not reach the outer surface of the second layer 7, like the circumferential groove 1 shown on the right side of FIG. 1.

[0072] In FIG. 1, double-headed arrow t1 is the thickness of the first layer 6, and double-headed arrow t2 is the thickness of the second layer 7. In FIG. 1, the midpoint in the tire width direction of the land portion 2 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.

[0073] The thickness t1 of the first layer 6 is not particularly limited, but is preferably 3.5 mm or more, more preferably 4.2 mm or more, and even more preferably 4.5 mm or more. Also, the thickness t1 of the first layer 6 is preferably 9.0 mm or less, more preferably 7.2 mm or less, and even more preferably 6.3 mm or less.

[0074] The thickness t2 of the second layer 7 is not particularly limited, but is preferably 0.5 mm or more, more preferably 0.6 mm or more, and even more preferably 0.7 mm or more. Also, the thickness t2 of the second layer 7 is preferably 3.0 mm or less, more preferably 2.4 mm or less, and even more preferably 2.1 mm or less.

[0075] In the present invention, the total thickness T (t1 + t2 in FIG. 1) of the tread portion is preferably 4.0 mm or more, more preferably 5.0 mm or more, even more preferably 6.0 mm or more, particularly preferably 7.0 mm or more, and most preferably 8.0 mm or more. On the other hand, although not particularly limited as the upper limit, it is preferably 15.0 mm or less, more preferably 14.0 mm or less, and even more preferably 12.0 mm or less.

[0076] In the present invention, 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, even more preferably more than 25.0% by mass, and particularly preferably more than 27.0% 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 handling stability 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.

[0077] In the present invention, the tan δ at the peak position within the range of -20°C to -70°C in the tan δ temperature distribution curve of the rubber composition constituting the tread portion is preferably -60°C or higher, more preferably -50°C or higher, and even more preferably -45°C or higher from the viewpoint of the effects of the present invention.

[0078] In the present invention, the half-value width of the peak is 45°C or higher, preferably 46°C or higher, more preferably 47°C or higher, and even more preferably 48°C or higher. When the half-value width of the peak is 45°C or higher, energy loss can occur in a wide frequency band, and energy loss can also occur widely in the frequency band during braking on snow and wet road surfaces. Note that the temperature distribution curve of tanδ may have a plurality of peak tops. In that case, for at least one peak (curve), it is sufficient that the half-value width of the peak is within the above range.

[0079] In the present invention, from the viewpoint of snow performance, the -10°C tanδ of the rubber composition constituting the tread portion is preferably more than 0.20, more preferably more than 0.25, and even more preferably more than 0.27. Further, from the viewpoint of low fuel consumption performance, the -10°C tanδ is preferably less than 0.50, more preferably less than 0.45, even more preferably less than 0.40, and particularly preferably less than 0.35.

[0080] In the present invention, from the viewpoint of snow performance, -10°C tanδ × H of the rubber composition constituting the tread portion is 1.7 or more, preferably 1.8 or more, and more preferably 2.0 or more. Further, from the viewpoint of handling stability performance, -10°C tanδ × H is preferably 3.0 or less, more preferably 2.8 or less, even more preferably 2.6 or less, and particularly preferably 2.5 or less.

[0081] In the present invention, from the viewpoint of snow performance, -10°C tanδ × T of the rubber composition constituting the tread portion is preferably 1.5 or more, more preferably 1.8 or more, even more preferably 2.0 or more, particularly preferably 2.2 or more, and most preferably 2.5 or more. Further, from the viewpoint of low fuel consumption performance, -10°C tanδ × T is preferably 4.0 or less, more preferably 3.8 or less, even more preferably 3.5 or less, and particularly preferably 3.1 or less.

[0082] In the present invention, the 0°C tanδ of the rubber composition constituting the tread portion is preferably more than 0.40, more preferably more than 0.45, still more preferably more than 0.50, still more preferably more than 0.55, and particularly preferably more than 0.50 from the viewpoint of snow performance. Further, from the viewpoint of low fuel consumption performance, the 0°C tanδ is preferably less than 0.70, more preferably less than 0.65, and still more preferably less than 0.60.

[0083] In the present invention, the glass transition temperature (Tg) of the rubber composition constituting the tread portion is preferably more than -65°C, more preferably more than -60°C, still more preferably more than -55°C, still more preferably more than -50°C, and particularly preferably more than -45°C from the viewpoint of the effects of the present invention. Further, from the viewpoint of snow performance, it is preferably less than -20°C, more preferably less than -25°C, and still more preferably less than -30°C.

[0084] ≪Tread Pattern≫ FIG. 2 is a developed view of a tread portion showing an embodiment of the present invention. W represents the tire width direction. TW represents the distance in the tire width direction W between the inner tread end Ti and the outer tread end To. In FIG. 2, the tread portion has five circumferential grooves 10. The widest central circumferential groove 11 passes above the tire center line CL, and on the outside thereof, a pair of central circumferential grooves 11 with a slightly narrower width pass, and further on the outside thereof, a pair of outermost circumferential grooves 12 with a narrower width pass. In the shoulder land portion 30, the lateral groove 20 reaches one end to the tread contact end Ti or To and the other end reaches the outermost circumferential groove. In a pair of center land portions 40 in contact with the central circumferential groove 11 passing through the tire center line CL, the lateral grooves (sipes) 21 communicate at both ends with the two central circumferential grooves 11 that define the center land portion. No lateral grooves are formed in a pair of center land portions 41 located further outside the center land portion.

[0085] In the tire of the present invention, the tread portion has one or more circumferential grooves, preferably two or more circumferential grooves, more preferably three or more circumferential grooves, still more preferably four or more circumferential grooves, and particularly preferably five or more circumferential grooves.

[0086] When the number of circumferential grooves is three, the tread portion has a pair of outermost circumferential grooves and a central circumferential groove, and has four land portions composed of a pair of shoulder land portions and a pair of center land portions. When the number of circumferential grooves is four, the tread portion has a pair of outermost circumferential grooves and a pair of central circumferential grooves. When the number of circumferential grooves is five, the tread portion has a pair of outermost circumferential grooves and three central circumferential grooves.

[0087] The tread portion according to the tire of the present embodiment preferably has three or more circumferential grooves 10, and has a pair of shoulder land portions 30 partitioned by a pair of outermost circumferential grooves 12 located at the outermost ends in the tire width direction and two or more center land portions 40 located between the pair of shoulder land portions 30. It is preferable that the groove width of at least one of the pair of outermost circumferential grooves 12 is narrower than the groove width of at least one of the circumferential grooves 11 that are not the pair of outermost circumferential grooves. More preferably, the groove widths of both of the pair of outermost circumferential grooves are narrower than the groove width of the central circumferential groove.

[0088] The tread portion according to the tire according to the present embodiment preferably has a plurality of lateral grooves 20 extending in the tire width direction. The width of the lateral grooves is not particularly limited, but is usually 8 mm or less. The direction of the lateral grooves may have a predetermined angle (θ) with respect to the tire width direction W. The range of θ is, for example, 0° to ±80°. For one lateral groove, θ may be constant at any position in the tire width direction, or θ may change according to the displacement of the position in the tire width direction.

[0089] From the perspective 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 even more preferably 0.70 or less. From the perspective of wear resistance performance, the land ratio R is preferably 0.50 or more, more preferably 0.55 or more, and even more preferably 0.60 or more.

[0090] The weight G of the tire according to the present embodiment is preferably 7.0 kg or more, more preferably 8.0 kg or more, and even more preferably 9.0 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 or less, etc.

[0091] In addition, various physical properties of the rubber composition such as -10°C tanδ and 0°C tanδ can be appropriately adjusted according to the types and blending amounts of the rubber components, fillers, softeners, etc. described later. For example, -10°C tanδ can be adjusted according to the types of rubber components and resin components.

[0092] [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 will be described.

[0093] The rubber composition according to the present embodiment contains a rubber component including an isoprene-based rubber and a styrene-butadiene rubber, and silica. The rubber component according to the present embodiment preferably contains an isoprene-based rubber, a styrene-butadiene rubber, and a butadiene rubber.

[0094] <Rubber Component> (Isoprene-based Rubber) As the isoprene rubber, for example, general ones 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, grafted natural rubber, etc. These isoprene rubbers may be used alone or in combination of two or more.

[0095] NR is not particularly limited, and general ones in the tire industry can be used. For example, SIR20, RSS#3, TSR20, etc. can be mentioned.

[0096] 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. Also, the content of the isoprene rubber is preferably less than 80% by mass, more preferably less than 70% by mass, more preferably less than 60% by mass, and even more preferably 50% by mass or less.

[0097] (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, one 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.

[0098] 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 preferred. 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 preferred. As the amino group, an amino group substituted with 1 to 2 alkyl groups having 1 to 6 carbon atoms is preferred. Specific examples of alkoxysilyl include, for example, trimethoxysilyl, triethoxysilyl, triisopropoxysilyl, dimethoxymethylsilyl, diethoxymethylsilyl, dimethylmethoxysilyl, dimethylethoxysilyl, etc.

[0099] As the SBR, oil-extended SBR 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.

[0100] 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, further preferably 23% by mass or less, still further preferably 20% by mass or less, still further preferably 18% by mass or less, and particularly preferably 15% by mass or less. Also, from the viewpoint of ensuring hysteresis loss, S1 is preferably 5% by mass or more, more preferably 8% by mass or more, and further preferably 10% by mass or more.

[0101] From the perspective of ensuring hysteresis loss, the vinyl content of SBR is preferably more than 15 mol%, more preferably more than 18 mol%, and even more preferably more than 20 mol%. Also, from the perspective of low fuel consumption performance, the vinyl content of SBR is preferably less than 50 mol%, more preferably less than 45 mol%, and even more preferably less than 30 mol%. In this specification, the vinyl content of SBR is measured by the above-mentioned measurement method.

[0102] From the perspective of the effects of the present invention, S1×R is preferably 5.5 or more, more preferably 6.5 or more, even more preferably 10.0 or more, and particularly preferably 12.0 or more. Also, S1×R is preferably 20.0 or less, more preferably 18.0 or less, and even more preferably 17.0 or less.

[0103] From the perspective of the effects of the present invention, S1 / G is preferably 1.60 or more, more preferably 1.80 or more, and even more preferably 2.10 or more. Also, S1 / G is preferably 3.00 or less, more preferably 2.80 or less, and even more preferably 2.70 or less.

[0104] From the perspective of the effects of the present invention, the glass transition temperature (Tg) of SBR is preferably -30°C or lower, more preferably -40°C or lower, even more preferably -50°C or lower, further more preferably -55°C or lower, and particularly preferably -60°C or lower. Also, from the perspective of wear resistance performance, it is preferably -90°C or higher, more preferably -80°C or higher, and even more preferably -70°C or higher.

[0105] From the perspective 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. Also, from the perspective of crosslinking uniformity, etc., 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 addition, the Mw of SBR is measured by the above-mentioned measurement method.

[0106] From the perspective of the effects of the present invention, the content in the rubber component of SBR is preferably 20% by mass or more, more preferably 30% by mass or more, and still more preferably 40% by mass or more. Also, the content in the rubber component of SBR is preferably 60% by mass or less, more preferably less than 60% by mass, and still more preferably 50% by mass or less.

[0107] (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.

[0108] 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-mentioned measurement method.

[0109] 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%, and 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.

[0110] In the case of the BR containing SPB, examples of the 1,2-syndiotactic polybutadiene crystals include those not simply dispersed in BR but dispersed after chemically bonding to BR. As such BR containing SPB, those commercially available from UBE Industries, Ltd. and the like can be used.

[0111] Examples of the modified BR include BR modified with the same functional groups as those described for the above SBR, etc. Further, 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 in the terminal and / or main chain can also be preferably used.

[0112] Examples of other modified BR include those obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and further having the terminal of the modified BR molecule bonded by a tin-carbon bond (tin-modified BR), etc. The modified BR may be either unhydrogenated or hydrogenated.

[0113] From the viewpoint of abrasion resistance performance, the weight average molecular weight (Mw) of BR is preferably more than 300,000, more preferably more than 350,000, and even more preferably more than 400,000. From the viewpoints such as 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.

[0114] From the viewpoint of the effects of the present invention, the content in the rubber component of BR is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more. Also, the content in the rubber component of BR is preferably less than 50% by mass, more preferably less than 40% by mass, and even more preferably less than 30% by mass.

[0115] From the viewpoint of the effects of the present invention, the total styrene amount S2 in the rubber component is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less. Further, S2 is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more.

[0116] (Other rubber components) The rubber component may contain rubber components other than isoprene rubber, SBR, and BR as long as the effects of the present invention are not affected. As the other rubber components, rubber components generally used in the tire industry can be used. For example, ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), hydrin rubber, etc. can be mentioned. These other rubber components may be used alone or in combination of two or more. Further, in addition to the above rubber components, a known thermoplastic elastomer may or may not be contained.

[0117] (Rubber components synthesized from recycled and biomass-derived raw materials) The monomers that are the constituent units of synthetic rubbers such as IR, SBR, and BR may be derived from underground resources such as petroleum and natural gas, or 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, and recycled 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. Among them, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0118] The method for producing recycled monomers 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.

[0119] Furthermore, monomers that are constituent units of polymers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural and forestry products, sugars, wood chips, plant residues after obtaining useful components, ethanol derived from plants, biomass naphtha, and the like.

[0120] Recycled monomers (biomass monomers) are not particularly limited, and examples include butadiene derived from biomass and aromatic vinyl compounds derived from biomass. 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 examples of chemical and / or physical conversion include those by catalysts, high heat, high pressure, electromagnetic waves, supercritical fluids, and combinations thereof.

[0121] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples thereof include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl compound / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compounds. Examples of the aromatic vinyl compound / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0122] 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. pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the standard modern carbon (modern standard reference), and is a value used as an index indicating the biomass ratio of the compound. The significance of this value is described below.

[0123] 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 that were originally contained in them have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain any 14 C elements. Therefore, chemical substances produced from these fossil fuels also do not contain any

[0124] On the other hand, 14C is constantly generated by cosmic rays undergoing nuclear reactions in the atmosphere. Therefore, 14 C reaches an equilibrium between the decrease due to radioactive decay and the generation due to nuclear reactions, and in the Earth's atmospheric environment, 14 the amount of C remains constant. Therefore, for substances derived from biomass resources that are cycling in the current environment, 14 the C concentration is approximately 1×10 -12 mol% with respect to the total number of C atoms as described above. Therefore, by utilizing the difference between these values, the biomass ratio in a certain compound can be calculated.

[0125] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 the C concentration ( 13 C / 12 C), 14 the C concentration ( 14 C / 12 C) is measured. In the measurement, 14 as the modern standard reference for the concentration of C, the concentration of 14 C in the circulating carbon in nature in 1950 is adopted. As a specific standard substance, 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 14 C per gram of carbon) is separated for each carbon isotope, 13 and for 14 C, after correcting to a certain value and applying the decay correction from 1950 to the measurement date, the resulting value is used as the value of the standard

[0126] Therefore, if the rubber is made from 100% biomass-derived substances, although there are regional differences and so on, it usually does not reach 100 under normal current conditions and thus shows a value of approximately 110 pMC. On the other hand, for chemical substances derived from fossil fuels such as petroleum, this 14When measuring the C concentration, 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.

[0127] From the above, using a material such as rubber with a high pMC value, that is, a material such as rubber with a high biomass ratio, in the rubber composition is suitable from the aspect of environmental protection.

[0128] [Filler] The rubber composition according to this embodiment contains silica as a filler. It is more preferable to contain silica and carbon black. Also, the filler may be a filler consisting only of carbon black and silica.

[0129] <Silica> The silica is not particularly limited, and for example, silica prepared by the dry method (anhydrous silica), silica prepared by the wet method (hydrous silica), etc., which are common in the tire industry, can be used. Also, from the perspective of environmental load, silica using a biomass material as a raw material (for example, amorphous silica refined from rice husks) may be used. Among them, hydrous silica prepared by the wet method is preferable because it has many silanol groups. These silicas may be used alone or in combination of two or more.

[0130] Silica using a biomass material as a raw material can be obtained, for example, by extracting a 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. Amorphous silica extracted from rice husks can be those commercially available from Wilmar Co., Ltd. etc.

[0131] Silica recycled from products containing silica can be, for example, silica recovered from products containing silica such as electronic components such as semiconductors, tires, desiccants, and filter materials such as diatomaceous earth. The method of recovery is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among them, silica recovered from electronic components such as semiconductors or tires is preferable.

[0132] 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, Japanese Patent Application Laid-Open No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.). Amorphous silica extracted from rice husks can be those commercially available from companies such as Wilmar.

[0133] From the viewpoint of reinforcing properties, 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, and particularly preferably more than 170 m 2 / g. Also, from the viewpoints of exothermic properties 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. The N2SA of silica is measured by the above measurement method.

[0134] 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. The average primary particle diameter of silica is measured by the above measurement method.

[0135] From the viewpoint of the effects of the present invention, the content of silica relative to 100 parts by mass of the rubber component is preferably more than 60 parts by mass, more preferably more than 70 parts by mass, still more preferably 80 parts by mass or more, and particularly preferably more than 90 parts by mass. Further, from the viewpoint of compatibility with the isoprene-based rubber, the content of silica relative to 100 parts by mass of the rubber component is preferably less than 200 parts by mass, more preferably 110 parts by mass or less, and still more preferably 100 parts by mass or less.

[0136] From the viewpoint of the effects of the present invention, the content of silica in the filler is preferably more than 60% by mass, more preferably more than 70% by mass, still more preferably more than 72% by mass, and particularly preferably more than 75% by mass. Further, from the viewpoint of wear resistance performance, it is preferably less than 95% by mass, more preferably less than 92% by mass, and still more preferably less than 90% by mass.

[0137] <Carbon black> The carbon black is not particularly limited, and those commonly used in the tire industry such as GPF, FEF, HAF, ISAF, SAF, etc. can be used. Specifically, N110, N115, N120, N125, N134, N135, N219, N220, N231, N234, N293, N299, N326, N330, N339, N343, N347, N351, N356, N358, N375, N539, N550, N582, N630, N642, N650, N660, N683, N754, N762, N765, N772, N774, N787, N907, N908, N990, N991, etc. can be preferably used. In addition, self-made products, etc. can also be preferably used. The raw material of the carbon black may be a biomass material such as lignin or vegetable oil, or a pyrolysis oil obtained by pyrolyzing waste tires. Also, the manufacturing method of the carbon black may be by combustion such as the furnace method, by hydrothermal carbonization (HTC), or 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 may be used alone or in combination of two or more.

[0138] In addition to the above, from the perspective of life cycle assessment, etc., carbon black made from biomass materials such as lignin as raw materials, or recycled carbon black obtained by pyrolyzing and purifying products containing carbon black such as tires may also be used as the carbon black.

[0139] As used herein, "recycled carbon black" refers to carbon black obtained by pulverizing products such as used tires containing carbon black and firing the pulverized material, and having a proportion of the mass of ash content (ash amount), which is a non-combustible component, of 13% by mass or more when oxidized and burned by heating in air using a thermogravimetric measurement method conforming to JIS K 6226-2:2003. That is, the proportion of the mass (carbon amount) of the weight loss due to the oxidative combustion of the recycled carbon black is 87% by mass or less. Recycled carbon black may also be represented by rCB.

[0140] Recycled carbon black can be obtained from the thermal decomposition 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 to 449 (2012), particularly pages 438, 440, and 442, and describes that it can be obtained by thermal decomposition of organic materials at 550 to 800°C with oxygen excluded, or by vacuum thermal decomposition at a relatively low temperature (

[0027] ). Carbon black obtained from such a thermal decomposition process usually lacks functional groups on its surface, as mentioned in

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

[0141] 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 surface of recycled carbon black contain functional groups 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 Japanese 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 carbon black treated to contain functional groups on these surfaces.

[0142] Recycled carbon black commercially available from Strable Green Carbon, LDCarbon, etc. can be used.

[0143] From the viewpoint of reinforcing properties, the nitrogen adsorption specific surface area (N2SA) of carbon black is preferably more than 160 m 2 / g, more preferably more than 165 m 2 / g, still more preferably more than 170 m 2 / g, particularly preferably more than 175 m 2 / g. Also, from the viewpoints of heat generation properties and processability, it is preferably less than 200 m 2 / g, more preferably less than 195 m 2 / g, still more preferably less than 190 m 2 / g. The N2SA of carbon black is measured by the above measurement method.

[0144] The average primary particle diameter of the carbon black is preferably less than 100 nm, more preferably less than 50 nm, still more preferably less than 30 nm, further more preferably less than 26 nm, particularly preferably less than 21 nm, and most preferably less than 18 nm. Also, the average primary particle diameter is preferably more than 8 nm, more preferably more than 10 nm, still more preferably more than 12 nm, further more preferably more than 14 nm, and particularly preferably more than 15 nm. Note that the average primary particle diameter of the carbon black is measured by the above measurement method.

[0145] From the viewpoint of wear resistance performance, the content of carbon black relative to 100 parts by mass of the rubber component is preferably more than 10 parts by mass, more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, and particularly preferably more than 25 parts by mass. Also, the content is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, still more preferably 30 parts by mass or less.

[0146] <Other fillers> The filler may include other fillers other than silica and carbon black. The other fillers are not particularly limited, and for example, those commonly used in the tire industry such as aluminum hydroxide, calcium carbonate, alumina, clay, talc, etc. can be blended.

[0147] From the viewpoint of wear resistance performance, the total content of the filler relative to 100 parts by mass of the rubber component is preferably more than 80 parts by mass, more preferably more than 90 parts by mass, still more preferably more than 100 parts by mass, and particularly preferably more than 110 parts by mass. Also, the total content is preferably less than 200 parts by mass, more preferably less than 180 parts by mass, still more preferably less than 160 parts by mass, and particularly preferably less than 150 parts by mass.

[0148] <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. 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 kinds.

[0149] The content of the silane coupling agent with respect to 100 parts by mass of the rubber component (the total amount of all when using a plurality of silane coupling agents in combination) 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. Also, from the viewpoint of preventing a decrease in wear 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.

[0150] [Other compounding agents] In addition to the rubber component and the filler, the rubber composition according to this embodiment may appropriately contain compounding agents generally used in the conventional tire industry, such as softeners, processing aids, waxes, stearic acid, zinc oxide, anti-aging agents, vulcanizing agents, vulcanization accelerators, and the like.

[0151] <Softener> A softener is a material that imparts plasticity to the rubber component, and is a concept that includes both softeners that are liquid at 25°C and softeners that are solid at normal temperature (25°C). Examples of softeners include resin components, oils, liquid rubbers, ester plasticizers, etc. These softeners may be derived from mineral resources such as petroleum and natural gas, or may be derived from biomass. Also, low-molecular-weight hydrocarbon components obtained by pyrolyzing and extracting used tires and products containing various components may be used as softeners. These softeners may be used alone or in combination of two or more.

[0152] (Resin component) The resin component is not particularly limited, but resin components commonly used in the tire industry can be used. For example, tackifying resins such as dicyclopentadiene-based resins, aromatic vinyl-based resins, coumarone-based resins, indene-based resins, C9-based resins, C5-based resins, C5C9-based resins, terpene-based resins, rosin-based resins, and phenol-based 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 a resin component containing dicyclopentadiene, styrene, and indene as monomer components.

[0153] ≪Dicyclopentadiene-based resin≫ The term "dicyclopentadiene-based resin" refers to a resin containing cyclopentadiene (CPD) or dicyclopentadiene (DCPD), which may be hydrogenated or modified. Examples of dicyclopentadiene-based resins include DCPD / C9 resins containing dicyclopentadiene and the C9 fraction described below as monomer components. As the DCPD resin, a DCPD / C9 resin containing dicyclopentadiene and styrene as monomer components is preferable, and a DCPD / C9 resin containing dicyclopentadiene, styrene, and indene as monomer components is particularly preferable. As the DCPD resin, for example, those commercially available from ExxonMobil, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., etc. can be used.

[0154] ≪Aromatic vinyl-based resin≫ The term "aromatic vinyl-based 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, which may be hydrogenated or modified. As the aromatic vinyl-based resin, due to economic reasons, ease of processing, and excellent heat generation properties, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferable, and a copolymer of α-methylstyrene and styrene is more preferable. As the aromatic vinyl-based resin, for example, those commercially available from Creighton, Eastman Chemical, Mitsui Chemicals, Inc., etc. can be used.

[0155] ≪Coumarone-based resin≫ The term "coumarone-based resin" refers to a resin containing coumarone as a monomer component, which may be hydrogenated or modified. Examples of coumarone resins include coumarone-indene resins containing coumarone and indene as monomer components, and coumarone-indene-styrene resins containing coumarone, indene, and styrene as monomer components.

[0156] ≪Indene-based resin≫ The term "indene resin" refers to a resin containing indene as a monomer component, which may be hydrogenated or modified. Examples of coumarone resins include coumarone-indene resins containing coumarone and indene as monomer components, coumarone-indene-styrene resins containing coumarone, indene, and styrene as monomer components, and the like.

[0157] ≪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, they may be hydrogenated or modified. Examples of the C9 fraction include petroleum fractions corresponding to 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene.

[0158] ≪C5 resin≫ The term "C5 resin" refers to a resin obtained by polymerizing a C5 fraction, which may be hydrogenated or modified. 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.

[0159] ≪C5C9 resin≫ The term "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, which 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.

[0160] ≪Terpene resin≫ "Terpene resin" refers to a resin that contains terpene compounds such as α-pinene, β-pinene, limonene, dipentene, etc. as the monomer component with the highest content, and may be hydrogenated or modified thereof. 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 that are monomer components of aromatic modified terpene resins include styrene, α-methylstyrene, vinyltoluene, divinyltoluene, and the like. Examples of phenolic compounds that are monomer components of terpene phenol resins include phenol, bisphenol A, cresol, xylenol, and the like.

[0161] ≪Rosin Resin≫ "Rosin resin" refers to a resin that contains rosin acid compounds such as abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc. as the monomer component with the highest content, and may be hydrogenated or modified thereof. Rosin resins are not particularly limited, and examples thereof include natural resin rosin, rosin modified resins obtained by modifying it by hydrogenation, disproportionation, dimerization, esterification, etc.

[0162] ≪Phenolic Resin≫ "Phenolic resin" refers to a resin that contains phenolic compounds such as phenol, cresol, etc. as the monomer component with the highest content. Phenolic resins are not particularly limited, and examples thereof include phenol formaldehyde resins, alkylphenol formaldehyde resins, alkylphenol acetylene resins, oil-modified phenol formaldehyde resins, and the like.

[0163] ≪Softening Point≫ From the perspective 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 perspectives 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-described measuring method.

[0164] <<Content>> When containing the resin component, the content with respect to 100 parts by mass of the rubber component is preferably more than 10 parts by mass, more preferably more than 20 parts by mass, and even more preferably more than 30 parts by mass. On the other hand, from the perspective of suppressing exothermic properties, the content is preferably less than 100 parts by mass, more preferably less than 80 parts by mass, and even more preferably 45 parts by mass or less.

[0165] (Oil) Examples of the oil include mineral oil, vegetable oil, animal oil, etc. Further, from the perspective of life cycle assessment, it is also possible to use waste oil after being used in a rubber mixer or an engine, or refined waste cooking oil used in a cooking shop.

[0166] 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, it is also possible to use an oil with a low content of polycyclic aromatic (PCA) compounds for environmental measures. Examples of the low PCA content oil include MES, TDAE, heavy naphthenic oil, etc.

[0167] In this specification, vegetable oils include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, wood rosin, etc. Further, as vegetable oils, there are also 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, oxidative polymerized oils obtained by oxidizing the above oils, waste cooking oils recovered from those used as edible oils, etc. Note that vegetable oils may be liquid or solid at normal temperature (25°C). These may be used alone or in combination of two or more. Further, the vegetable oils are components included in the above-mentioned softeners and may be used in combination with other softeners. Also, a part of the softener components in known rubber compositions may be equivalently replaced with these vegetable oils so as to satisfy the relationship of the present invention.

[0168] 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. Acylglycerol is not particularly limited and may be any of 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, and triacylglycerol. Further, acylglycerol may be a monomer, a dimer, or a multimer of trimer or higher. Note that acylglycerol of dimer or higher can be obtained by heat polymerization, oxidative polymerization, etc. Also, acylglycerol may be liquid or solid at normal temperature (25°C).

[0169] The method for confirming whether the acylglycerol is contained in the rubber composition is not particularly limited, but for example, the following 1It can be confirmed by 1H-NMR measurement. Specifically, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at room temperature (25 °C) for 24 hours. After removing the rubber composition, 1 1H-NMR is measured. When the signal of tetramethylsilane (TMS) is set to 0.00 ppm, signals are observed at around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm. 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.

[0170] 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.

[0171] 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.

[0172] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0173] Examples of animal oils include fish oil, beef tallow, or oleyl alcohol that can be derived therefrom.

[0174] When contained, the content relative to 100 parts by mass of the rubber component is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, still more preferably more than 15 parts by mass, and particularly preferably 20 parts by mass or more from the viewpoint of processability. Also, from the viewpoint of abrasion resistance performance, it is preferably less than 100 parts by mass, more preferably less than 50 parts by mass, still more preferably 30 parts by mass or less.

[0175] (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). For example, 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. can be mentioned. These liquid rubbers may be used alone or in combination of two or more.

[0176] (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.

[0177] The content of the softening agent with respect to 100 parts by mass of the rubber component (when a plurality of softening agents are used in combination, the total amount of all) is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, still more preferably 40 parts by mass or more, and particularly preferably more than 50 parts by mass from the viewpoint of snow performance. From the viewpoint of processability, it is preferably less than 110 parts by mass, more preferably less than 100 parts by mass, still more preferably less than 80 parts by mass, and particularly preferably 70 parts by mass or less.

[0178] (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, and the like. These processing aids may be used alone or in combination of two or more. As the processing aid, for example, those commercially available from Schill+Seilacher, Performance Additives, etc. can be used.

[0179] When the processing aid is contained, the content with respect to 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1 part by mass, still more preferably more than 1.5 parts by mass from the viewpoint of exerting the effect of improving processability. 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, still more preferably less than 5.0 parts by mass.

[0180] (Wax) The wax is not particularly limited, and any wax commonly used in the tire industry can be preferably used. For example, mineral waxes, plant-derived waxes, etc. can be mentioned. 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, these 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 Shinko 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.

[0181] When contained, the content of the wax 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 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 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.

[0182] (Stearic acid) When contained, the content of stearic acid 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 even more preferably more than 1.5 part 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 even more preferably less than 5.0 parts by mass.

[0183] (Zinc oxide) When zinc oxide is contained, 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 still more preferably more than 1.5 part by mass from the viewpoint of processability. Further, 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.

[0184] (Antioxidant) The antioxidant is not particularly limited, but naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditoly-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD) and other p-phenylenediamine-based antioxidants; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bis, tris, polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane and the like can be mentioned. Among them, p-phenylenediamine-based antioxidants and quinoline-based antioxidants 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 commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexsys Co., Ltd. and the like can be used. These antioxidants may be used alone or in combination of two or more.

[0185] 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 parts by mass, and even more preferably more than 2.5 parts by mass from the viewpoint of the 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.

[0186] (Vulcanizing agent) As the vulcanizing agent, sulfur is preferably used. As sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, etc. can be used.

[0187] When containing sulfur, the content per 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.5 parts by mass, even more preferably more than 1.0 part by mass, and particularly preferably 1.5 parts by mass or more 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 even 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 the pure sulfur component contained in the oil-containing sulfur.

[0188] 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 condensate, sodium 1,6-hexamethylene-dithiocarbonate 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 use those commercially available from Taoka Chemical Industry Co., Ltd., Rancess Co., Ltd., Flexsys Co., etc.

[0189] (Vulcanization accelerator) The vulcanization accelerator is not particularly limited. For example, sulfenamide - type vulcanization accelerators, thiazole - type vulcanization accelerators, guanidine - type vulcanization accelerators, thiuram - type vulcanization accelerators, thiourea - type vulcanization accelerators, dithiocarbamate - type vulcanization accelerators, aldehyde - amine - type vulcanization accelerators, aldehyde - ammonia - type vulcanization accelerators, imidazoline - type vulcanization accelerators, xanthate - type vulcanization accelerators, caprolactam disulfide, etc. can be mentioned. These vulcanization accelerators may 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 - type vulcanization accelerators, thiazole - type vulcanization accelerators, and guanidine - type vulcanization accelerators are preferred.

[0190] Examples of sulfenamide - type vulcanization accelerators include N - tert - butyl - 2 - benzothiazolylsulfenamide (TBBS), N - cyclohexyl - 2 - benzothiazolylsulfenamide (CBS), N,N - dicyclohexyl - 2 - benzothiazolylsulfenamide (DCBS), etc.

[0191] Examples of thiazole - type 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, etc.

[0192] Examples of guanidine - type vulcanization accelerators include 1,3 - diphenylguanidine (DPG), 1,3 - di - o - tolguanidine, 1 - o - tolbiguanide, di - o - tolguanidine salt of dicatecholborate, 1,3 - di - o - cumenylguanidine, 1,3 - di - o - biphenylguanidine, 1,3 - di - o - cumenyl - 2 - propionylguanidine, etc.

[0193] Examples of thiuram 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.

[0194] Examples of thiourea vulcanization accelerators include thiourea compounds such as thiocarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea, diorthotolylthiourea, N,N'-diphenylthiourea, trimethylthiourea, N,N'-diethylthiourea, and the like.

[0195] 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.

[0196] 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 still 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 still more preferably less than 6.0 parts by mass.

[0197] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the various materials from carbon dioxide, the carbon dioxide may be directly converted, or the methane obtained through the methanation process of synthesizing methane from carbon dioxide may be converted.

[0198] [Manufacture] 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.).

[0199] The kneading process includes, for example, a base kneading process of kneading compounding agents and additives other than the vulcanizing agent and the vulcanization accelerator, and a final kneading (F kneading) process of adding the vulcanizing agent and the vulcanization accelerator to the kneaded product obtained in the base kneading process and kneading them. Further, the base kneading process can be divided into a plurality of processes if desired. In the case of 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 remill 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 2 or more. Also, when the number of masterbatches is 2 or more, all the compounding agents and additives used in the base kneading process may be allocated to any one of the masterbatches.

[0200] The kneading conditions are not particularly limited. For example, in the base kneading process, a method of kneading at a discharge temperature of 150 to 170°C for 3 to 10 minutes, and in the final kneading process, kneading at 70 to 110°C for 1 to 5 minutes can be mentioned. The vulcanization conditions are not particularly limited, and for example, a method of vulcanizing at 150 to 200°C for 10 to 30 minutes can be mentioned.

[0201] The tire of the present embodiment having a tread portion composed of the rubber composition according to the present embodiment can be manufactured by a conventional method. That is, the tire is produced by extruding an unvulcanized rubber composition prepared by blending the above components with the rubber component as required 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 conventional method to form an unvulcanized tire, and then heating and pressurizing the obtained unvulcanized tire in a vulcanizer. The vulcanization conditions are not particularly limited, and for example, a method of vulcanizing at 150 to 200 ° C for 10 to 30 minutes can be mentioned.

[0202] [Use] The tire of the present 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 load tire, a run-flat tire. The passenger car tire is a tire assumed to be mounted on an automobile running on four wheels and having a maximum load capacity of less than 1400 kg. The heavy load tire refers to a tire having a maximum load capacity of 1400 kg or more. The tire of the present embodiment can also be used for winter tires such as studless tires in addition to all-season tires and summer tires.

Examples

[0203] Hereinafter, examples (Examples) considered to be preferable in practice will be 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 method are shown in Tables 1 to 2.

[0204] [Various Chemicals] NR:TSR20 SBR1: SBR produced according to Production Example 1 below (S-SBR, Tg: -50°C, styrene content: 25% by mass, vinyl content: 25 mol%, Mw: 1 million, non-oil extended) SBR2: SBR produced according to Production Example 2 below (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 solid content) SBR4: HPR840 manufactured by JSR Corporation (S-SBR, Tg: -63°C, styrene content: 10% by mass, vinyl content: 42 mol%, Mw: 160,000, non-oil extended) BR: UBEPOL BR (registered trademark) 150B manufactured by UBE Industries, Ltd. (unmodified BR, cis content: 97% by mass, Mw: 440,000) Carbon black: Prototype (N2SA: 180 m 2 / g, average primary particle size: 16 nm) Silica: Ultrasil VN3 manufactured by Evonik Degussa GmbH (N2SA: 175 m 2 / g, average primary particle size: 15 nm) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa GmbH Resin component 1: SYLVATRAXX 4150 manufactured by Kraton Corporation (polyt terpene resin, Mw: 2500, softening point: 115°C) Resin component 2: SYLVATRAXX 4401 manufactured by Kraton Corporation (α-methylstyrene resin, Mw: 700, softening point: 85°C) Resin component 3: Oppera PR-395 manufactured by ExxonMobil Corporation (hydrogenated DCPD / C9 resin, a resin containing dicyclopentadiene, styrene and indene as monomer components, softening point: 118°C) Oil: VivaTec 500 manufactured by H&R Corporation (TDAE oil) Wax: Oz Ace 0355 (paraffin wax) manufactured by Nippon Seiro Co., Ltd. Anti-aging agent 1: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Anti-aging agent 2: Nocrack RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinsei 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 (powder sulfur containing 5% oil) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Nocceler CZ (N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Vulcanization accelerator 2: Nocceler D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

[0205] (Production Example 1: Production of SBR1) Charge cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene into a nitrogen-substituted autoclave reactor. 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 loss on drying becomes 0.1% to obtain SBR1.

[0206] (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 loss on drying becomes 0.1% to obtain SBR2.

[0207] (Examples and Comparative Examples) According to the compounding formulations shown in Table 1 or Table 2, using a 1.7 L sealed Banbury mixer, knead the chemicals other than sulfur and vulcanization accelerators at a discharge temperature of 160°C for 4 minutes to obtain a kneaded product. Next, using an open roll, add sulfur and vulcanization accelerators to the obtained kneaded product and knead until it reaches 105°C for 4 minutes to obtain an unvulcanized rubber composition. Using the obtained unvulcanized rubber composition, mold it according to the shape of the tread part and bond it together with other tire members to produce an unvulcanized tire, and vulcanize it at 170°C to obtain each test tire (size: 205 / 65R15, rim: 15×6JJ, internal pressure: 230 kPa).

[0208] <Measurement of Acetone Extraction Amount (AE)> For the rubber test pieces cut from the tread parts of each test tire, measure the AE amount for each. The AE amount can be determined by immersing each test piece in acetone for 24 hours, extracting the soluble components, measuring the mass of each test piece before and after extraction, and using the following formula. Acetone extraction amount (%) = {(mass of vulcanized rubber test piece before extraction - mass of vulcanized rubber test piece after extraction) / (mass of rubber test piece before extraction)} × 100

[0209] <Temperature Distribution Curve of tanδ> For rubber test pieces cut from the tread portions of each test tire, using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd., measure the temperature distribution curve of tanδ in the temperature range from -20°C to -70°C 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. Then, based on the obtained temperature distribution curve of tanδ, measure the tanδ and the half-width at the peak position within the range of -20°C to -70°C.

[0210] <Measurement of tanδ at 0°C> Cut out from the tread portion of each test tire to produce specimens with a length of 20 mm × width of 4 mm × thickness of 1 mm, with the tire circumferential direction as the long side and the tire radial direction as the thickness direction. For each rubber test piece, use an Implex series manufactured by GABO to measure the loss tangent (tanδ) under the conditions of a temperature of 0°C, a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of ±2.5%.

[0211] <-10°C tanδ> Cut out from the tread portion of each test tire to produce specimens with a length of 20 mm × width of 4 mm × thickness of 1 mm, with the tire circumferential direction as the long side and the tire radial direction as the thickness direction. For each rubber test piece, use an Implex series manufactured by GABO to measure the loss tangent (tanδ) under the conditions of a temperature of -10°C, a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of ±2.5%.

[0212] <Snow Performance> Mount each test tire on the four wheels of a FF passenger car with a displacement of 2000 cc, and measure the braking distance from the point where the brakes are applied at a speed of 15 km / h on a snow-covered road surface. Taking the braking distance of the test tire in the reference comparison example (comparative example 10) as 100, express the snow performance of each tire in terms of an index using the following calculation formula. The larger the index, the better the snow performance. (Snow Performance Index) = (Braking Distance of the Tire in the Reference Comparison Example) / (Braking Distance of Each Test Tire) × 100

[0213] <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 the reference comparative example (Comparative Example 10) as 100, the wet grip performance of each tire is indicated by an index according to the following calculation formula. The larger the index, the better the wet grip performance is shown. (Wet grip performance index) = (Braking distance of the tire of the reference comparative example) / (Braking distance of each test tire) × 100

[0214] <Overall performance> The total value of the above snow performance and wet grip performance is shown as the overall performance index.

[0215]

Table 1

[0216]

Table 2

[0217] <Embodiment> Examples of embodiments of the present invention are shown below. [1] 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 content of the silica with respect to 100 parts by mass of the rubber component is 70 parts by mass or more, The styrene content S1 (% by mass) of the styrene-butadiene rubber is 30 or less, The acetone extraction amount AE (% by mass) of the rubber composition is more than 17.0, 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 45°C or more, The groove depth at the deepest part of the circumferential groove is H (mm), When the tanδ at -10°C of the rubber composition is defined as -10°C tanδ, a tire in which -10°C tanδ × H is 1.7 or more. 〔2〕The tire according to the above 〔1〕, wherein the total styrene amount S2 (mass%) in the rubber component is 15 or less. 〔3〕The tire according to the above 〔1〕 or 〔2〕, wherein the rubber composition contains a resin component containing dicyclopentadiene, styrene, and indene as monomer components. 〔4〕The tire according to any one of the above 〔1〕 to 〔3〕, wherein -10°C tanδ is 0.30 or more. 〔5〕The tire according to any one of the above 〔1〕 to 〔4〕, wherein -10°C tanδ × H is 2.0 or more. 〔6〕The tire according to any one of the above 〔1〕 to 〔5〕, wherein the acetone extraction amount of the rubber composition is more than 20.0 mass%. 〔7〕The tire according to any one of the above 〔1〕 to 〔6〕, wherein the tanδ at 0°C (0°C tanδ) of the rubber composition is 0.50 or more. 〔8〕The tire according to any one of the above 〔1〕 to 〔7〕, when the total thickness of the tread portion is T (mm), -10°C tanδ × T is 1.5 or more and 3.5 or less. 〔9〕The tire according to any one of the above 〔1〕 to 〔8〕, 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. 〔10〕The tire according to any one of the above 〔1〕 to 〔9〕, when the land ratio of the tread portion is R, S1 × R is 10.0 or more. 〔11〕The tire according to any one of the above 〔1〕 to 〔10〕, when the tire weight is G (kg), S1 / G is 3.0 or less. 〔12〕The number of the circumferential grooves is 3 or more, and the tread portion has a pair of shoulder land portions partitioned by a pair of outermost circumferential grooves located at the outermost end in the tire width direction and two or more center land portions located between the pair of shoulder land portions, The tire according to any one of [1] to

[11] , wherein the groove width of at least one of the pair of outermost circumferential grooves is narrower than the groove width of at least one of the circumferential grooves that are not the pair of outermost circumferential grooves. 〔13〕The tire according to any one of [1] to

[12] , wherein the rubber composition contains 30 to 70 parts by mass of a softening agent with respect to 100 parts by mass of the rubber component. 〔14〕The tire according to any one of [1] to

[13] , wherein S1 is 25% by mass or less. 〔15〕The tire according to any one of [1] to

[14] , wherein S1 is 15% by mass or less.

Explanation of symbols

[0218] 2 Tread 3 Tread surface 4 Straight line connecting the ends of the circumferential grooves 5 Extension line of the bottom of the circumferential groove 6 First layer 7 Second layer 8 Extension line of the outer surface of the second layer t1 Thickness of the first layer t2 Thickness of the second layer T Total thickness of the tread part 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 10 Circumferential groove 11 Central circumferential groove 12 Outermost circumferential groove 20 Transverse groove 21 Transverse groove (sip) 30 Shoulder tread 40 Center tread 41 Center tread CL Tire center line Ti Inner tread end To Outer tread end TW Tread width W Tire width direction

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 content of the silica is 70 parts by mass or more with respect to 100 parts by mass of the rubber component, the styrene content S1 (mass%) of the styrene-butadiene rubber is 30 or less, the acetone extraction amount AE (mass%) of the rubber composition exceeds 17.0, 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 45°C or more, the groove depth at the deepest part of the circumferential groove is H (mm), when the tanδ of the rubber composition at -10°C is defined as -10°C tanδ, a tire in which -10°C tanδ × H is 1.7 or more.

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

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

4. The tire according to claim 1 or 2, wherein -10°C tanδ is 0.30 or more.

5. The tire according to claim 1 or 2, wherein -10°C tanδ × H is 2.0 or more.

6. The tire according to claim 1 or 2, wherein the acetone extraction amount of the rubber composition exceeds 20.0% by mass.

7. The tire according to claim 1 or 2, wherein the tanδ (0°C tanδ) of the rubber composition at 0°C is 0.50 or more.

8. The tire according to claim 1 or 2, wherein when the total thickness of the tread portion is T (mm), -10°C tanδ × T is 1.5 or more and 3.5 or less.

9. 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.

10. The tire according to claim 1 or 2, wherein when the land ratio of the tread portion is R, S1 × R is 10.0 or more.

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

12. The number of the circumferential grooves is 3 or more, and the tread portion has a pair of shoulder land portions partitioned by a pair of outermost circumferential grooves located at the outermost ends in the tire width direction and two or more center land portions located between the pair of shoulder land portions. The tire according to claim 1 or 2, wherein the groove width of at least one of the pair of outermost circumferential grooves is narrower than the groove width of at least one of the circumferential grooves that are not the pair of outermost circumferential grooves.

13. The tire according to claim 1 or 2, wherein the rubber composition contains 30 to 70 parts by mass of a softening agent with respect to 100 parts by mass of a rubber component.

14. The tire according to claim 1 or 2, wherein S1 is 25% by mass or less.

15. The tire according to claim 1 or 2, wherein S1 is 15% by mass or less.

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