Tire

Abstract

Provided is a tire in which the overall performance of wet grip performance is improved. A tire having a tread portion, the tread portion having one or more circumferential grooves, the tread portion comprising a rubber composition containing a rubber component and silica, the rubber component containing an isoprene rubber and a styrene butadiene rubber, the content of the isoprene rubber in the rubber component being 40% by mass or more, and the content of the styrene butadiene rubber in the rubber component being 40% by mass or more. The content of the styrene-butadiene rubber in the rubber component is 40% by mass or more, the content of the silica is 90 parts by mass or more with respect to 100 parts by mass of the rubber component, the styrene content S1 (% by mass) of the styrene-butadiene rubber is 30 or less, and when the ground contact area ratio of the tire is R and the tan [delta] of the rubber composition at 0 DEG C is 0 DEG C tan [delta], 0 DEG C tan [delta] * R is 0.30 or more.

Description

Technical Field

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

[0002] Patent Document 1 discloses: A rubber composition for a tire, which is prepared by compounding 80 to 200 parts by mass of silica having a CTAB specific surface area of 150 to 300 m 2 / g and 0.1 to 5 parts by mass of a specific tetrazine compound with respect to 100 parts by mass of a rubber component containing 60 to 90 parts by mass of a specific conjugated diene rubber and 10 to 40 parts by mass of a conjugated diene polymer. The aromatic vinyl monomer content of the specific conjugated diene rubber is 35 to 45% by mass, and the vinyl bond content is less than 35 mol%. Thereby, the wet grip performance of the tire is improved. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2020-41035 Summary of the Invention [Problems to be Solved by the Invention]

[0004] In recent years, it has been desired to further improve the wet grip performance of tires.

[0005] An object of the present invention is to provide a tire with improved wet grip performance. [Means for Solving the Problems]

[0006] The present invention relates to a tire, characterized in that it 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 rubber and a styrene-butadiene rubber, the content of the isoprene rubber in the rubber component is 40% by mass or more, the content of the styrene-butadiene 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 90 parts by mass or more, the styrene content S1 (mass%) of the styrene-butadiene rubber is 30 or less, when the contact area ratio of the tire is set to R and the tanδ of the rubber composition at 0°C is set to 0°C tanδ, 0°C tanδ × R is 0.30 or more. [Effects of the Invention]

[0007] According to the present invention, a tire with improved wet grip performance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Description of Reference Numerals

[0009] The tire of an embodiment of the present invention is a tire having the following characteristics: It 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 styrene-butadiene rubber in the rubber component is 40% by mass or more, the content of silica relative to 100 parts by mass of the rubber component is 90 parts by mass or more, the styrene content S1 (mass%) of the styrene-butadiene rubber is 30 or less, when the contact area ratio of the tire is set as R and the tanδ of the rubber composition at 0°C is set as 0°C tanδ, 0°C tanδ × R is 0.30 or more.

[0010] In the tire of this embodiment, regarding the reason for the improvement of wet grip performance, although it is not desired to be limited theoretically, the following speculation can be made.

[0011] The rubber composition constituting the tread surface of the tire of the present embodiment, (1) since it contains 40% by mass or more of isoprene rubber, by forming an isoprene rubber phase of a certain size or more, an interface with other rubber phases is generated, and the input to the tire during vehicle driving can be reduced. At the same time, since the interaction between isoprene rubber and silica is relatively weak, the isoprene rubber can move flexibly in the rubber matrix, and since the followability of the tread surface to the road surface is improved, it helps to improve the wet grip performance. In addition, (2) since it contains 40% by mass or more of styrene-butadiene rubber, the proportion of the styrene phase region in the rubber phase increases, and thus heat generation property is easily obtained, which helps to improve the wet grip performance. In addition, (3) since the content of silica is 90 parts by mass or more relative to 100 parts by mass of the rubber component, the proportion of silica present on the tread surface increases, and since an interaction occurs between the hydroxyl groups on the silica surface and the wet road surface, the followability of the tread surface to the road surface is improved, which helps to improve the wet grip performance. In addition, (4) by making the styrene content S1 of the styrene-butadiene rubber 30% by mass or less, minute styrene phase regions are formed in the rubber phase, and the styrene phase regions move flexibly in the rubber phase. As a result, the mobility of the entire polymer present in the rubber phase is improved, the followability of the tread surface to the road surface is improved, and it helps to improve the wet grip performance.

[0012] In addition, for the tread surface of the tire of the present embodiment, (5) by making the product of the 0°C tanδ of the rubber composition constituting the tread surface and the contact area ratio R, that is, 0°C tanδ × R, 0.30 or more, the total heat generation amount of the tread surface at the tread surface can be increased, which helps to improve the wet grip performance. At the same time, it is considered that: based on the synergistic effects of the above (1) to (5), a particularly remarkable effect of significantly improving the wet grip performance can be achieved.

[0013] It is considered that the half-peak width of the tanδ temperature distribution curve of the above rubber composition is preferably 30°C or less in the range of -20°C to -70°C. Since by making the half-peak width smaller, more energy loss occurs in the frequency region during braking on a wet road surface, the wet grip performance is further improved.

[0014] When the acetone extraction amount of the above rubber composition is set to AE (% by mass), AE is preferably 22.0 or more.

[0015] It is considered that by making the acetone extraction amount AE of the rubber composition 22.0% by mass or more, the rubber composition contains a certain amount of plasticizer, the dispersibility of the filler is improved, and the distribution of the filler is efficiently carried out, so that the wet grip performance is further improved.

[0016] From the viewpoint of wet grip performance, 0°C tanδ is preferably 0.45 or more.

[0017] The 0℃ tanδ × H is preferably 3.00 or more. It is considered that this is because when the groove depth of the circumferential groove is relatively shallow, the hysteresis loss increases and the wet grip performance is further improved.

[0018] When the total thickness of the above tread portion is set to T (mm), the 0℃ tanδ × T is preferably 3.50 or more. It is considered that even when the 0℃ tanδ of the rubber composition is low, by ensuring the total thickness of the tread portion, the heat generation property of the tread portion is improved and the wet grip performance is improved.

[0019] The AE amount × H is preferably 140.0 or more. Since the efficiency of dispersion and distribution of the filler is improved, the rigidity of the rubber composition can be reduced, the contact area with the road surface is increased, and the followability of the tread portion to the road surface is improved. Therefore, the wet grip performance is further improved.

[0020] The above rubber composition preferably contains a resin component having dicyclopentadiene, styrene, and indene as monomer components. It is considered that by containing this resin component, the adhesion of the tread portion to the road surface is strengthened, and thus the wet grip performance is improved.

[0021] From the viewpoint of wet grip performance, the above rubber composition preferably contains more than 100 parts by mass of silica relative to 100 parts by mass of the rubber component.

[0022] From the viewpoint of wet grip performance, the above rubber composition preferably contains a mercapto-based silane coupling agent.

[0023] The total styrene amount S2 in the above rubber component is preferably 15% by mass or less. It is considered that by making the total styrene amount S2 15% by mass or less, minute styrene phase regions are formed in the rubber matrix. Since these minute phase regions have flexibility, the mobility of the polymer is improved, the followability of the rubber composition to the road surface is improved, and the wet grip performance is further improved.

[0024] The above tread portion preferably has: two or more grounding portions divided by the above one or more circumferential grooves, and at least one of the above grounding portions has a transverse groove extending radially inward of the tire, and the transverse groove has a portion where the groove width in a cross section perpendicular to the above extending direction is larger than the groove width at the tread surface.

[0025] It is considered that by disposing the above transverse groove in the grounding portion, an increase in the compression rigidity can be suppressed even when wear progresses, and the wet grip performance can be ensured.

[0026] In the tread surface of the above-mentioned tread portion, when a region centered on the tire equator and having a width of 30% of the tread contact width is defined as the central region, and regions on both outer sides of the central region and within the tread contact width are defined as a pair of shoulder regions, the groove depth at the deepest part of the circumferential groove existing in the above-mentioned shoulder region is preferably 6.0 mm or more.

[0027] It is considered that with the above configuration, drainage performance can be improved, which is thus helpful for improving wet grip performance.

[0028] When the tire weight is set to G (kg), S1 / G is preferably 3.0 or less. It is considered that as the tire weight decreases, by reducing S1, the handling stability in a low-temperature environment becomes easier to improve. It is considered that since the lighter the tire becomes, the smaller the force pressing the contact portion against the road surface becomes, thus as the tire becomes lighter, even a small amount of aggregation of the styrene portion will have a greater impact on the tread surface.

[0029] S1×R is preferably 11.0 or more. It is considered that when the tread portion has S1×R of 11.0 or more, the tiny styrene phase regions formed in the rubber phase move flexibly, improving the mobility of the polymer and the followability to the road surface, and increasing the contact area between the tread portion and the road surface, thus further improving the wet grip performance.

[0030] [Definition] "The styrene content S1 (mass%) of styrene-butadiene rubber" is the styrene content (mass%) of styrene-butadiene rubber (SBR). When the rubber component contains a single SBR, it is the styrene content of that SBR. When the rubber component contains multiple SBRs, it can be obtained by the sum of the product of the styrene content of each SBR and the compounding amount (mass%) of that SBR when the total SBR is set to 100 mass%.

[0031] For example, when the rubber component is composed 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)).

[0032] "The total styrene amount S2 (mass%) in the rubber component" is the total content (mass%) of the styrene portion contained in 100 mass% of the rubber component. For each rubber component, it is the value obtained by multiplying the calculated styrene content (mass%) by the mass fraction in the rubber component, and taking the sum of these values. Specifically, it can be calculated by Σ (the styrene content (mass%) of each styrene-containing rubber × the content (mass%) of each styrene-containing rubber in the rubber component / 100).

[0033] For example, when the rubber component is composed of 20% by mass of a first SBR (styrene content: 25% by mass), 30% by mass of a second SBR (styrene content: 27.5% by mass), and 50% by mass of BR, the total styrene amount S2 in 100% by mass of the rubber component is approximately 13.3% by mass (= (25×20 / 100) + (27.5×30 / 100) + (0×50 / 100)).

[0034] "The tanδ at the peak position within the range of -20°C to -70°C of the tanδ temperature distribution curve of the rubber composition" can be obtained from the tanδ temperature distribution curve measured by the method disclosed in Japanese Unexamined Patent Application Publication No. 2021-54377. That is, for each vulcanized test piece, using a dynamic viscoelasticity measuring device (for example, the EPLEXOR series manufactured by GABO), under the conditions of a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±0.5%, and a heating rate of 2°C / minute, the tanδ temperature distribution curve is measured within the temperature range of -20°C to -70°C, and it is the tanδ at the peak position of the temperature dispersion curve with the temperature on the X-axis and tanδ on the Y-axis.

[0035] "The full width at half maximum of the peak within the range of -20°C to -70°C of the tanδ temperature distribution curve of the rubber composition (the full width at half maximum of the tanδ peak)" can be obtained from the tanδ temperature distribution curve measured by the method disclosed in Japanese Unexamined Patent Application Publication No. 2021-54377. That is, for each vulcanized test piece, using a dynamic viscoelasticity measuring device (for example, the EPLEXOR series manufactured by GABO), under the conditions of a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±0.5%, and a heating rate of 2°C / minute, the tanδ temperature distribution curve is measured within the temperature range of -20°C to -70°C to obtain a temperature dispersion curve with the temperature on the X-axis and tanδ on the Y-axis. It is defined as follows: Let the tanδ at the peak position of the obtained temperature distribution curve be A, the intersection of the line passing through A and parallel to the Y-axis with the X-axis be B, the midpoint of the line segment AB be C, the line passing through C and parallel to the X-axis be D, and when the two intersections of D and the temperature distribution curve are E and F, it is the absolute value of the difference in temperature (°C) between E and F.

[0036] The "acetone extraction (AE) amount" is the value obtained by immersing each vulcanized rubber test piece in acetone at room temperature (around 25°C) for 72 hours according to JIS K 6229:2015 to extract soluble components, measuring the mass of each test piece before and after extraction, and calculating using the following formula. Acetone extraction amount (mass%) = {((mass of the rubber test piece before extraction - mass of the rubber test piece after extraction) / (mass of the rubber test piece before extraction))} × 100

[0037] "The glass transition temperature (Tg) of the rubber composition" means: Using a dynamic viscoelasticity measuring device (for example, the EPLEXOR series manufactured by GABO), the temperature distribution curve of tanδ is measured under the conditions of a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±0.5%, and a heating rate of 2 °C / minute. The temperature corresponding to the maximum value (tanδ peak temperature) in the range above -60 °C and below 40 °C of the obtained temperature distribution curve. In addition, in the measurement in the range of -60 to 40 °C, when the tanδ value monotonically increases or decreases with the increase in temperature, the glass transition temperature of the rubber composition is set to 40 °C or -60 °C, respectively. In addition, in the range above -60 °C and below 40 °C, when there are two or more points indicating the maximum value, the point with the lowest temperature is set as the glass transition temperature.

[0038] "tanδ at 0 °C" is the loss tangent (tanδ) measured using a dynamic viscoelasticity measuring device (for example, the EPLEXOR series manufactured by GABO) 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 a tensile mode. The sample for measuring tanδ at 0 °C is a vulcanized rubber composition with a length of 20 mm × a width of 4 mm × a thickness of 1 mm. When cutting and manufacturing from a tire, it is cut from the tread surface with the circumferential direction of the tire as the long side and the radial direction of the tire as the thickness direction.

[0039] "The tread surface" is the part that forms the ground contact surface of the tire. When there are components such as a belt layer or a belt reinforcing layer and a carcass layer formed by steel or textile materials in the radial cross-section of the tire, it refers to the component located more outside the tire in the radial direction than these components.

[0040] "The normal state" means: A state without load that is assembled on a normal rim and filled with air at a normal internal pressure.

[0041] "The dimensions of each part of the tire": Unless otherwise specified, the "dimensions of each part of the tire" that appear on the outer surface of the tire are values specified in the normal state. On the other hand, for the "dimensions of each part of the tire" existing inside the tire, they are values specified in the state where the cut tire piece holds the rim width of the normal rim after cutting the tire with a plane including the tire rotation axis.

[0042] "Regular rim" means: in the standard system including the standards on which the tire is based, the rim specified by the standard for each tire. For example, it refers to the standard rim in the applicable sizes recorded in the "JATMA YEAR BOOK" of JATMA (Japan Automobile Tire Manufacturers Association), the "Measuring Rim" recorded in the "STANDARDS MANUAL" of ETRTO (The European Tyre and Rim Technical Organisation), and the "Design Rim" recorded in the "YEAR BOOK" of TRA (The Tire and Rim Association, Inc.). Refer to them in the order of JATMA, ETRTO, and TRA. When there are applicable sizes during the reference, follow their standards. In addition, for a tire not specified in the above standards, it refers to the rim with the smallest width among the rims with the minimum diameter that can assemble and maintain the internal pressure (i.e., no air leakage occurs between the rim and the tire).

[0043] "Regular internal pressure" means: in the standard system including the standards on which the tire is based, the air pressure specified by the standard for each tire. For example, it refers to the "maximum air pressure" of JATMA, the "INFLATION PRESSURE" of ETRTO, and the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" of TRA. Similar to the case of the regular rim, refer to them in the order of JATMA, ETRTO, and TRA. When there are applicable sizes during the reference, follow their standards. In addition, for a tire not specified in the above standards, it refers to the regular internal pressure (where it is 250 kPa or more) of other tire sizes (where the tire is specified in the standard) with the above regular rim as the standard rim. When there are multiple regular internal pressures of 250 kPa or more, it refers to the minimum value among them.

[0044] "Normal load" refers to the load specified for each tire in the standard system that includes the standard on which the tire is based. For example, it refers to the maximum value recorded in the "Maximum Load Capacity" of JATMA, the "LOAD CAPACITY" of ETRTO, and the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" of TRA. Similar to the case of the normal rim and normal internal pressure, it is referenced in the order of JATMA, ETRTO, and TRA. When referencing, if there are applicable dimensions, the standards thereof shall be followed. At the same time, for a tire not specified in the above standards, the maximum load capacity W calculated separately shall be used as the normal load. L It is set as the normal load.

[0045] "Maximum load capacity W L " is calculated by the following formula. "V" is the virtual volume of the tire (mm 3 ), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the cross-sectional height of the tire in the radial direction of the cross-section of the tire based on the plane including the tire rotation axis (mm), and "Wt" is the cross-sectional width of the tire in the normal state (mm). When the rim diameter of the tire is set as R, Ht can be obtained by (Dt - R) / 2. When there are patterns or letters on the tire sidewall, Wt is the value obtained by removing these. In addition, the maximum load capacity has the same meaning as the above normal load.

[0046]

Mathematical formula 1

[0047] The "contact area" is the area of the tread obtained from the contour when the tire is pressed on the ground. It can be obtained by assembling the tire on the normal rim, applying the normal internal pressure, leaving it to stand at 25°C for 24 hours, then coating the surface of the tire tread with ink, loading the tire with the normal load (maximum load capacity) and pressing it vertically on cardboard (the camber angle is 0°) to transfer the ink. The area of the contact area refers to the total contact area. The total contact area can be calculated by rotating the tire by 72 degrees in sequence, performing the above transfer operation at a total of 5 locations, and taking the average of the 5 obtained areas.

[0048] The "effective contact area region" refers to the region of the tread of the tire that comes into contact with the ground when the tire is pressed on the ground. It can be obtained by assembling the tire on a regular rim, filling it with the regular internal pressure, leaving it standing at 25°C for 24 hours, then coating the surface of the tire tread with ink, loading the tire with the regular load (maximum load capacity), and vertically pressing it on cardboard (camber angle is 0°) to transfer the ink. The area of the effective contact area region refers to the effective contact area. The effective contact area can be calculated by rotating the tire 72 degrees successively, performing the above transfer operation at a total of 5 positions, and taking the average of the 5 obtained areas.

[0049] The "contact area ratio R" is calculated by the following formula using the total contact area of the above contact area region and the effective contact area of the above effective contact area region. The result is expressed as 0 to 1.0. Contact area ratio = (Effective contact area / Total contact area)

[0050] A "groove" refers to a recess formed on the surface of the tire tread that extends radially inward of the tire, and refers to a recess with a groove width (opening width) of 2.0 mm or more at the surface of the tread. Similarly, those less than 2.0 mm are called "sipe".

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

[0052] The "groove depth H (mm) at the deepest part of the circumferential groove" refers to, in the cross-section of the tire based on the plane containing the tire rotation axis, the straight-line distance between the straight line connecting the ends of the groove in the tread surface and the straight line at the lowest part of the groove in the tire radial direction. When the groove depth of the groove varies in the tire width direction and / or circumferential direction, the maximum value of the above straight-line distance is set as the groove depth of the groove (in addition, the depth at positions above a three-way intersection or more where multiple grooves intersect is excluded from the object of the definition of the groove depth in this specification).

[0053] The "groove width" refers to the distance between the groove walls. The groove width can be confirmed at each position along the extension direction of the groove from the tread surface to the groove bottom.

[0054] A "widened groove" refers to a groove where the groove width on the inner side in the tire radial direction becomes larger than the groove width (opening width) at the tread surface.

[0055] "Total thickness T (mm) of the tread surface" refers to the thickness of the tread surface measured along the normal line at the tire equator in the cross-section of the tire based on the plane containing the tire rotation axis. When there is a circumferential groove at the tire equator, it is the thickness measured along the normal line at the center of the tire width direction of the ground contact portion that is closer to the tire equator among the ground contact portions on both lateral sides in the tire width direction of the groove. In addition, the total thickness T of the tread surface is the average value of the total thicknesses of the tread surface obtained by rotating the tire 72° sequentially in the circumferential direction and measuring at 5 positions.

[0056] "Weight G (kg) of the tire" means the weight of the tire alone without the rim. On the other hand, when there are components such as those made of sponge and sealant or sensor components in the inner cavity of the tire, it is assumed to include the weight of these.

[0057] "Ground contact portion" refers to the portion of the tread surface of the tire that comes into contact with the ground when the tire is pressed on the ground, and the portion of the tread surface that constitutes the above-mentioned effective contact area.

[0058] "Groove depth at the deepest part in the circumferential direction in the shoulder area" means: when the area centered on the tire equator on the tread surface is set as the central area, and the areas on both outer sides of the central area and within the ground contact width of the tread surface are set as a pair of shoulder areas, the groove depth at the deepest part of the circumferential groove in the shoulder area.

[0059] "Rubber component of the rubber composition" refers to the component that participates in cross-linking within the rubber composition, usually a component with a weight average molecular weight (Mw) of 10,000 or more.

[0060] "Glass transition temperature (Tg) of the rubber component" refers to the static glass transition temperature of each rubber component that can be obtained by a differential scanning calorimeter (for example, Q200 manufactured by TA Instruments Japan).

[0061] "Styrene content" is the value calculated by 1 1H-NMR measurement, and is applicable to rubber components (rubbers containing styrene units) having repeating units derived from styrene such as SBR, for example.

[0062] "Vinyl content (amount of 1,2-bonded butadiene units)" is the value calculated by infrared absorption spectroscopy in accordance with JIS K 6239-2:2017, and is applicable to rubber components having repeating units derived from butadiene such as SBR and BR, for example.

[0063] "Cis content (amount of cis-1,4-bonded butadiene units)" is the value calculated by infrared absorption spectroscopy in accordance with JIS K 6239-2:2017, and is applicable to rubber components having repeating units derived from butadiene such as BR, for example.

[0064] The "weight-average molecular weight (Mw)" is obtained by conversion with reference to standard polystyrene based on the measured values according to gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation). For example, it is applicable to SBR, BR, plasticizers, etc.

[0065] The "nitrogen adsorption specific surface area of carbon black (N2SA)" is measured according to JIS K 6217-2:2017. The "nitrogen adsorption specific surface area of silica (N2SA)" is measured by the BET method according to ASTM D3037-93.

[0066] The "average primary particle size" is obtained by taking a photograph of the particles with a transmission or scanning electron microscope and calculating the arithmetic average of the particle sizes of 400 particles. For the particle size, when the shape of the particle is approximately circular, the diameter of the circle is defined as the particle size; when it is needle-shaped or rod-shaped, the minor axis is defined as the particle size; in other cases, the equivalent circle diameter calculated from the electron microscope image is defined as the particle size. The equivalent circle diameter can be obtained as the positive square root of "[4 × (area of the particle) / π]". The average primary particle size is applicable to silica, carbon black, etc.

[0067] The "content of plasticizer" also includes the amount of plasticizer contained in the oil-extended rubber component in which the plasticizer has been previously increased by oil, resin component, liquid rubber component, etc. In addition, the same applies to the content of oil, resin component, and liquid rubber. For example, when the extender component is oil, the extended oil is included in the content of oil.

[0068] The "softening point of resin component" is the temperature at which the ball drops when measuring the softening point specified in JIS K 6220-1:2015 7.7 using a ring-and-ball softening point measuring device.

[0069] [Tire] Hereinafter, a tire according to an embodiment of the present invention will be described with reference to the accompanying drawings. In addition, the embodiment shown below is only an example, and the tire of this embodiment is not limited to the following embodiment.

[0070] Figure 1 A tire according to an embodiment of the present invention is illustrated. Figure 1 shows a part of the cross-section when the tire is cut by a plane including the tire rotation axis. Figure 1 In this figure, the up-down direction is the tire radial direction, the left-right direction is the tire axial direction, and the direction perpendicular to the paper surface is the tire circumferential direction. Figure 1 In this figure, the dotted line CL represents the tire equator.

[0071] Figure 1The tire has a tread surface portion 1 that contacts the ground during driving, a pair of sidewall portions 2 that extend radially outward of the tire, and a pair of bead portions 3.

[0072] As Figure 1 shown, a belt layer 5 is provided on the radially inner side of the tread surface portion 1 of the tire. A carcass 4 and an inner liner layer 7 are laminated below the belt layer 5. In addition, a belt strip layer 6 may also be present between the tread surface portion 1 and the belt layer 5. The bead portion 3 includes a bead core 14 and a bead filler 13 that extends radially outward from the core. The bead filler 13 tapers gradually at the radially outer end of the tire. In the bead portion 3, a lapping portion 10 that abuts against the rim 8 when the rim 8 is mounted is provided outside the carcass 4, and the lapping portion 10 is composed of a rubber composition containing a rubber component. A rim bead wrapper 9 may also be present between the lapping portion 10 and the rim 8.

[0073] The tread surface portion is composed of a rubber composition containing a rubber component and silica. The tread surface portion 1 may include a single rubber layer or two or more rubber layers. Among them, it is preferably provided with a layer (tread rubber layer 11) whose outer surface constitutes the tread surface and a base rubber layer 12 on the radially outer side of the belt layer 5. One or more intermediate rubber layers may further exist between the tread rubber layer 11 and the base rubber layer 12. When the tread surface portion includes two or more rubber layers, each physical property value such as the 0°C tanδ of the rubber composition constituting the tread surface portion only needs to satisfy the physical property value in any rubber layer, and it is preferably the layer (tread rubber layer) whose outer surface constitutes the tread surface that satisfies the physical property value.

[0074] Figure 1 In, the double arrow t1 is the thickness of the layer (tread rubber layer 11) whose outer surface constitutes the tread surface 16, and the double arrow t2 is the thickness of the base rubber layer 12.

[0075] The total thickness T of the tread surface portion ( Figure 1 t1 + t2 in) is preferably 4.0 mm or more, more preferably 5.0 mm or more, further 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, there is no particular limitation as the upper limit, and it is preferably 15.0 mm or less, more preferably 14.0 mm or less, further preferably 12.0 mm or less, particularly preferably 10.0 mm or less.

[0076] 《Tread Surface Portion》 Figure 2 is a cross-sectional view showing a cross-section of the tread surface portion of the tire passing through the tire rotation axis. Figure 2 In, the up-down 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. Figure 2In this case, the midpoint in the tire width direction of the grounding portion 20 is represented by symbol P. A 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.

[0077] The tread surface portion according to the present embodiment has at least one or more circumferential grooves 15. The tread surface portion has a grounding portion 20 divided by the circumferential grooves 15 in the tire width direction.

[0078] The groove depth H of the deepest part of the circumferential groove 15 refers to: Figure 2 In this case, the straight-line distance between the straight line 17 connecting the ends of the circumferential grooves in the tread surface 16 and the extension line of the lowest part in the tire radial direction of this groove. In addition, for example, when there are a plurality of circumferential grooves 15, the groove depth H refers to: the straight line 17 and the extension line 19 of the lowest part in the tire radial direction of the circumferential groove 15 ([ Figure 2 In this case, the left circumferential groove 15) among the plurality of circumferential grooves 15.

[0079] From the viewpoint of wear resistance, the groove depth H of the deepest part in the circumferential direction is preferably 5.0 mm or more, more preferably 5.5 mm or more, further preferably 6.0 mm or more, further preferably 6.5 mm or more, and particularly preferably 7.0 mm or more. In addition, from the viewpoint of wet grip performance, the groove depth H of the deepest part of the circumferential groove is preferably 10.0 mm or less, more preferably 8.0 mm or less, and further preferably 7.5 mm or less.

[0080] The tread surface portion may also include, as shown in Figure 1 and Figure 2 : a layer (running surface rubber layer 11) whose outer surface constitutes the tread surface 16 and a base rubber layer 12 adjacent to the radially inner side of the running surface rubber layer 11. Figure 2 One circumferential groove 15 shown on the left side of [[ ]] is formed such that the deepest part of the groove bottom of the circumferential groove 15 is located on the radially inner side of the tire with respect to the outer surface of the base rubber layer 12. Specifically, the base rubber layer 12 has a concave portion that is recessed radially inward with respect to the outer surface, and a part of the running surface rubber layer 11 is formed with a prescribed thickness within this concave portion of the base rubber layer 12. The circumferential groove 15 is formed so as to extend beyond the outer surface of the base rubber layer 12 and enter the inside of the concave portion of the base rubber layer 12. In addition, the circumferential groove 15 may also be formed in the same way as the circumferential groove 15 shown on the right side of [[ ]] Figure 2 with a groove depth that does not reach the outer surface of the base rubber layer 12.

[0081] From the viewpoints of improving the efficiency of dispersion and distribution of the filler and reducing the rigidity at low temperatures, the acetone extraction amount AE of the rubber composition constituting the tread portion is preferably 20.0% by mass or more, more preferably 22.0% by mass or more, and further preferably 23.0% by mass or more. Further, from the viewpoint of durability performance, the acetone extraction amount (AE) is preferably less than 35.0% by mass, more preferably less than 33.0% by mass, and further preferably less than 30.0% by mass.

[0082] From the viewpoint of wet grip performance, AE×H is preferably 140.0 or more, more preferably 142.0 or more, and further preferably 145.0 or more. Further, from the viewpoint of durability performance, AE×H is preferably 210.0 or less, more preferably 190.0 or less, further preferably 170.0 or less, and further preferably 160.0 or less.

[0083] From the viewpoint of the effects of the present invention, the tanδ at the peak position in the range of -20°C to -70°C of the tanδ temperature distribution curve of the rubber composition constituting the tread portion is preferably -60°C or more, more preferably -50°C or more, and further preferably -40°C or more.

[0084] From the viewpoint of generating energy loss in the frequency region during braking on a wet road surface and further improving wet grip performance, the half-peak width of the above-mentioned peak (half-peak width of the tanδ peak) is preferably 45°C or less, more preferably 40°C or less, further preferably 35°C or less, and particularly preferably 30°C or less. Further, since the half-peak width of the tanδ peak can generate energy loss in a relatively wide frequency region, even in the deformation speed region of the rubber crack piece, since the input from the road surface can be released as heat, crack growth can be suppressed. From the viewpoint of improving wear resistance performance, it is preferably 20°C or more, more preferably 22°C or more, and further preferably 23°C or more. In addition, there may be multiple peaks in the tanδ temperature distribution curve. At this time, for at least one peak (curve), the half-peak width of the peak is within the above range.

[0085] From the viewpoint of wet grip performance, the 0°C tanδ of the rubber composition constituting the tread portion is preferably greater than 0.40, more preferably greater than 0.45, further preferably 0.50, further preferably 0.55, and particularly preferably greater than 0.60. 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 further preferably less than 0.60.

[0086] From the viewpoint of wet grip performance, 0℃ tanδ × H is preferably greater than 2.80, more preferably 3.00 or more, still more preferably greater than 3.10, still more preferably greater than 3.20, and particularly preferably greater than 3.30. Further, from the viewpoint of durability performance, 0℃ tanδ × H is preferably less than 5.00, more preferably less than 4.50, still more preferably less than 4.10.

[0087] From the viewpoint of wet grip performance, 0℃ tanδ × T is preferably greater than 3.20, more preferably 3.50 or more, still more preferably greater than 3.70, still more preferably greater than 3.80, and particularly preferably greater than 3.90. Further, from the viewpoint of low fuel consumption performance, 0℃ tanδ × T is preferably less than 5.00, more preferably 4.50 or less, still more preferably 4.00 or less.

[0088] From the viewpoint of the effects of the present invention, the glass transition temperature (Tg) of the rubber composition constituting the tread surface is preferably greater than -70°C, more preferably greater than -60°C, still more preferably greater than -50°C, still more preferably greater than -40°C, and particularly preferably greater than -30°C. Further, from the viewpoint of low temperature embrittlement, it is preferably less than 0°C, more preferably less than -10°C, still more preferably less than -20°C.

[0089] In addition, various physical properties such as 0℃ tanδ of the rubber composition can be appropriately adjusted according to the types and compounding amounts of the following rubber components, fillers, plasticizers, etc. For example, 0℃ tanδ can be adjusted according to the type of resin component.

[0090] 《Tread Pattern》 Figure 3 The tread pattern of the tire according to one embodiment of the present invention is shown, but the tread pattern of the tire according to this embodiment is not limited to Figure 3 . Figure 3In this case, the tread surface has three circumferential grooves that continuously extend in the tire circumferential direction. Although the central circumferential groove (the central circumferential groove) extends in a zigzag shape, it is not limited to such a manner, and the central circumferential groove can also be linear. In addition, although a pair of circumferential grooves (a pair of outermost circumferential grooves) on both sides thereof extend in a linear shape, it is not limited to such a manner, and the outermost circumferential groove can also be zigzag. Through these circumferential grooves, a pair of central grounding portions 21 and a pair of shoulder grounding portions 22 are demarcated. In the central grounding portion 21, a transverse groove 31 that extends radially inward of the tire is arranged, and in the shoulder grounding portion 22, a transverse groove 32 that extends radially inward of the tire is arranged. The transverse groove 31 is a widened groove that has a portion with a groove width greater than the groove width on the tread surface in a cross-section perpendicular to the above-mentioned extending direction. On the other hand, the groove width of the transverse groove 32 in a cross-section perpendicular to the above-mentioned extending direction is constant and is not a widened groove. The transverse groove 31 does not communicate with the circumferential groove at both of its ends, but it is not limited to such a manner, and at least one side of its two ends can also communicate with the circumferential groove. One end of the transverse groove 32 communicates with the circumferential groove, and the other end extends to the tread grounding end Te, but it is not limited to such a manner. Among them, from the viewpoint of drainage performance, a manner like the transverse groove 32 where one end communicates with the circumferential groove and the other end extends to the tread grounding end Te is preferred.

[0091] The tread portion of the tire according to the present embodiment preferably has two or more grounding portions demarcated by one or more circumferential grooves, preferably at least one grounding portion has a plurality of transverse grooves that extend radially inward of the tire, and at least one of the transverse grooves is preferably a widened groove.

[0092] Figure 4 Indicates Figure 3 A cross-sectional view of the C-C line of the shown transverse groove 31. This cross-section is a cross-section perpendicular to the extending direction of the transverse groove 31 that extends radially inward of the tire.

[0093] The manner of the widened portion of the widened groove is not particularly limited as long as it improves the drainage performance with the wear of the tire and can improve the grip performance. For example, Figure 3 And Figure 4 For the widened portion of the widened transverse groove 31, the groove width increases monotonically along the tire radial direction from the tread surface to the groove bottom, that is, the maximum groove width is at the groove bottom. Therefore, the more the tire wears, the more the drainage performance improves.

[0094] Figure 4In this case, the groove walls 42 on both sides of the transverse groove 31 that serves as the groove for widening are recessed from the groove edges on the tread surface toward the groove bottom, and the amounts of recess are represented by C1 and C2. C1 and C2 are each independently preferably 0.05 times or more, more preferably 0.07 times or more, and further preferably 0.10 times or more, relative to the groove width (the groove width at the tread surface, the opening width) W1 of the distance between the groove edges of the transverse groove. On the other hand, this value is preferably 0.45 times or less, more preferably 0.40 times or less, and further preferably 0.35 times.

[0095] From the viewpoint of the effects of the present invention, the contact area ratio R of the tire according to the present embodiment is preferably 0.80 or less, more preferably 0.75 or less, and further preferably 0.70 or less. In addition, from the viewpoint of wear resistance, the contact area ratio R is preferably 0.50 or more, more preferably 0.55 or more, and further preferably 0.60 or more.

[0096] From the viewpoint of the effects of the present invention, 0℃ tanδ × R is 0.30 or more, preferably 0.31 or more, more preferably 0.32 or more, further preferably 0.33 or more, particularly preferably 0.34 or more, and most preferably 0.35 or more. In addition, 0℃ tanδ × R is preferably 0.42 or less, more preferably 0.40 or less, further preferably 0.39 or less, and particularly preferably 0.38 or less.

[0097] Figure 3 In this case, the central circumferential groove exists in the tread surface within the central region, which is a region of 30% of the tread contact width centered on the tire equator. Its shape is a zigzag in which straight grooves are repeated. The tread portion of the tire according to the present embodiment preferably has a circumferential groove in the central region, which is a region of 30% of the tread contact width centered on the tire equator in the tread.

[0098] (Groove depth of the circumferential groove in the shoulder region) The tread portion of the tire according to the present embodiment is preferably such that when the central region is a region of 30% of the tread contact width centered on the tire equator in the tread surface, and the regions on both outer sides of the central region and within the tread contact width are a pair of shoulder regions, a circumferential groove also exists in the shoulder region. When a circumferential groove exists in the shoulder region, the groove depth at the deepest part of the circumferential groove is preferably 4.8 mm or more, more preferably 5.0 mm or more, further preferably 5.5 mm or more, and particularly preferably 6.0 mm or more. It is considered that by the above configuration, drainage performance can be improved, which thus helps to improve wet grip performance.

[0099] The circumferential groove present in the shoulder region means: among the circumferential grooves present on the tread surface, the circumferential grooves other than those present in the above-mentioned central region. That is, the circumferential groove present in this shoulder region can refer to a circumferential groove that, even if the groove straddles both the central region and the shoulder region, more than half of it is present in the shoulder region. In addition, the groove depth at the deepest part of the circumferential groove present in the shoulder region means: when there are multiple circumferential grooves present in the shoulder region, the groove depth of the circumferential groove with the deepest groove depth. In addition, the groove depth at the deepest part of the circumferential groove present in the shoulder region as mentioned here means: when there is a circumferential groove in the shoulder region, it refers to the groove depth of this circumferential groove, which is different from the groove depth H (mm) at the deepest part that refers to the groove depth of the circumferential groove with the deepest groove depth among all circumferential grooves.

[0100] The weight G of the tire is preferably 5.0 kg or more, more preferably 6.0 kg or more, and further preferably 7.0 kg or more. The upper limit value of the tire weight G is not particularly limited and is usually 100 kg or less. For example, it can be 80 kg or less, 60 kg or less, 40 kg or less, etc.

[0101] [Rubber composition] The rubber composition constituting the tread portion of the tire according to the present embodiment (hereinafter referred to as the rubber composition according to the present embodiment) will be described.

[0102] The rubber composition according to the present embodiment contains an isoprene rubber and a styrene-butadiene rubber. Among the rubber components according to the present embodiment, as the rubber component, it is preferably further contains a butadiene rubber, and more preferably contains an isoprene rubber, a styrene-butadiene rubber, and a butadiene rubber. The rubber component according to the present embodiment can be a rubber component composed only of an isoprene rubber and a styrene-butadiene rubber, or can be a rubber component composed of three components of an isoprene rubber, a styrene-butadiene rubber, and a butadiene rubber.

[0103] [Rubber component] (Isoprene rubber) As the isoprene rubber, for example, substances commonly used in the tire industry such as isoprene rubber (IR) and natural rubber can be used. Among natural rubbers, in addition to non-modified natural rubber (NR), it also includes modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, and grafted natural rubber. These isoprene rubbers can be used alone or in combination of two or more.

[0104] As for NR, there is no particular limitation, and substances commonly used in the tire industry can be used. For example, SIR20, RSS#3, TSR20, etc. can be listed.

[0105] 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, and more preferably 45% by mass or more. Further, 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 still more preferably 50% by mass or less.

[0106] (SBR) There is no particular limitation on the SBR, and examples thereof include solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs (modified S-SBR, modified E-SBR) thereof. As the modified SBR, examples include SBR modified at the terminal and / or main chain with a compound (modifying agent) having the following functional groups; modified SBR coupled with tin, silicon compounds, etc. (condensates, substances having a branched structure, etc.). Further, hydrides of these SBRs (hydrogenated SBR) can also be used. These SBRs can be used alone or in combination of two or more.

[0107] As the functional group of the above-mentioned modifying agent, a functional group containing at least one element selected from silicon, nitrogen, and oxygen is preferred. As such a functional group, 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, thioether group, disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazine bridge 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. are exemplified, and an amino group and / or an alkoxysilyl group are preferred. As the amino group, an amino group substituted with 1 to 2 alkyl groups having 1 to 6 carbon atoms is preferred. As specific examples of the alkoxysilane, for example, trimethoxysilane, triethoxysilane, triisopropoxysilyl, dimethoxymethylsilane, diethoxymethylsilane, dimethylmethoxysilane, dimethylethoxysilane, etc. are exemplified.

[0108] As the SBR, oil-extended SBR or non-oil-extended SBR can be used. As the SBR that can be used in the present embodiment, commercially available substances from JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Industries, Ltd., Asahi Kasei Corporation, ZSELASTOMERS Co., Ltd., ARLANXEO Corporation, etc. can be used.

[0109] From the viewpoint of the effects of the present invention, the styrene content S1 of 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, further preferably 20% by mass or less, further preferably 18% by mass or less, and particularly preferably 15% by mass or less. In addition, from the viewpoint of wet grip performance, S1 is preferably 5% by mass or more, more preferably 8% by mass or more, and further preferably 10% by mass or more.

[0110] From the viewpoint of wet grip performance, the vinyl content of SBR is preferably greater than 15 mol%, more preferably greater than 18 mol%, and further preferably greater than 20 mol%. In addition, from the viewpoint of low fuel consumption performance, the vinyl content of SBR is preferably less than 50 mol%, more preferably less than 45 mol%, and further preferably less than 30 mol%. In addition, in this specification, the vinyl content of SBR is measured by the above-mentioned measurement method.

[0111] From the viewpoint of the effects of the present invention, S1×R is preferably 10.0 or more, more preferably 11.0 or more, further preferably 12.0 or more, and particularly preferably 13.0 or more. In addition, S1×R is preferably 20.0 or less, more preferably 18.0 or less, and further preferably 17.5 or less.

[0112] From the viewpoint of the effects of the present invention, S1 / G is preferably 1.0 or more, more preferably 1.5 or more, and further preferably 2.0 or more. In addition, S1 / G is preferably 6.0 or less, more preferably 5.0 or less, and further preferably 4.0 or less.

[0113] From the viewpoint of the effects of the present invention, the glass transition temperature (Tg) of SBR is preferably -40°C or lower, more preferably -45°C or lower, further preferably -50°C or lower, further preferably -55°C or lower, and particularly preferably -60°C or lower. In addition, from the viewpoint of abrasion resistance performance, it is preferably -90°C or higher, more preferably -80°C or higher, and further preferably -70°C or higher.

[0114] From the viewpoint of the effects of the present invention, the weight average molecular weight (Mw) of SBR is preferably greater than 80,000, more preferably greater than 100,000, further preferably greater than 150,000, and particularly preferably greater than 500,000. In addition, from the viewpoints of crosslinking uniformity, etc., Mw is preferably less than 2,000,000, more preferably less than 1,500,000, and further preferably less than 1,100,000. In addition, the Mw of SBR is measured by the above-mentioned measurement method.

[0115] From the viewpoint of the effects of the present invention, the content of SBR in the rubber component is 40% by mass or more, preferably more than 40% by mass, more preferably more than 42% by mass, still more preferably 45% by mass or more, and particularly preferably 48% by mass or more. In addition, the content of SBR in the rubber component is preferably 60% by mass or less, more preferably less than 60% by mass, and still more preferably 55% by mass or less.

[0116] (BR) There is no particular limitation on BR. 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 series butadiene rubber synthesized with a rare earth element series catalyst (rare earth series BR), BR containing syndiotactic polybutadiene crystals (BR containing SPB), modified BR (high-cis modified BR, low-cis modified BR), etc., which are commonly used in the tire industry, can be used. These BRs can be used alone or in combination of two or more.

[0117] As the high-cis BR, for example, commercially available products from Zeon Corporation, UBE Industries, Ltd., JSR Corporation, etc. can be used. By containing high-cis BR, the low-temperature characteristics and abrasion resistance can be improved. The cis content of the high-cis BR is preferably more than 95 mol%, more preferably more than 96 mol%, and still more preferably more than 97 mol%. In addition, the cis content of BR is measured by the above-mentioned measurement method.

[0118] As the rare earth series BR, it is synthesized with a rare earth element series catalyst, 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 the rare earth series BR, for example, commercially available products from Lanxess Corporation, etc. can be used.

[0119] Examples of the BR containing SPB include substances in which 1,2-syndiotactic polybutadiene crystals are not simply dispersed in BR, but the crystals are dispersed by chemical bonding with BR. As such a BR containing SPB, commercially available products from UBE Industries, Ltd., etc. can be used.

[0120] As the modified BR, in addition to BR modified with the same functional groups as those described in the above SBR, etc., modified butadiene rubber (modified BR) modified at the terminal and / or main chain with a functional group containing at least one element selected from silicon, nitrogen, and oxygen can also be preferably used.

[0121] As other modified BRs, those obtained by polymerizing 1,3-butadiene using a lithium initiator and then adding a tin compound can be cited. Further, modified BRs in which the ends of the modified BR molecules are bonded by tin-carbon bonds (tin-modified BRs) and the like can be cited. In addition, the modified BR can be either an unhydrogenated modified BR or a hydrogenated modified BR.

[0122] From the viewpoint of abrasion resistance, the weight-average molecular weight (Mw) of BR is preferably greater than 300,000, more preferably greater than 350,000, and further preferably greater than 400,000. In addition, from the viewpoints of crosslinking uniformity and the like, it is preferably less than 2,000,000, more preferably less than 1,000,000, and further preferably less than 500,000. In addition, Mw can be determined by the above method.

[0123] The content of BR in the rubber component is not particularly limited, and is preferably 1% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, further preferably 15% by mass or more, and particularly preferably 19% by mass or more. In addition, the content of BR in the rubber component is preferably 20% by mass or less, more preferably less than 20% by mass, and further preferably 15% by mass or less.

[0124] 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 12% by mass or less, and further preferably 10% by mass or less. In addition, S2 is preferably 3% by mass or more, more preferably 5% by mass or more, and further preferably 7% by mass or more.

[0125] (Other rubber components) Within a range that does not affect the effects of the present invention, the rubber component may further contain rubber components other than isoprene-based rubber, SBR, and BR. As other rubber components, rubber components commonly 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), chlorinated ether rubber, and the like can be cited. These other rubber components can be used alone or in combination of two or more. In addition, in addition to the above rubber components, known thermoplastic elastomers may or may not be contained.

[0126] (Rubber components synthesized from recycled / biomass-derived raw materials) The monomers that are the constituent units of synthetic rubbers such as IR, SBR, and BR can be substances derived from underground resources such as petroleum and natural gas, or substances recovered from rubber products such as tires or non-rubber products such as polystyrene. As the monomers obtained by recovery (recovered monomers), there is no particular limitation, and examples include recovered polyisoprene, recovered butadiene, recovered aromatic vinyl compounds, etc. As the above-mentioned butadiene, 1,2-butadiene and 1,3-butadiene can be cited. As the above-mentioned aromatic vinyl compound, there is no particular limitation, and examples include styrene, etc. Among them, it is preferable to use recovered polyisoprene (recovered isoprene), recovered butadiene, and / or recovered styrene (recovered styrene) as raw materials.

[0127] As the method for producing the recovered monomer, there is no particular limitation. For example, it can be cited as being synthesized from recovered naphtha obtained by cracking rubber products such as tires. In addition, as the method for producing the recovered naphtha, there is no particular limitation. For example, rubber products such as tires can be cracked under high temperature and high pressure, or cracked by microwave, or extracted after mechanical pulverization.

[0128] Furthermore, the monomers that are the constituent units of polymers such as IR, SBR, and BR can also be substances derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. As the biomass, there is no particular limitation, and examples include substances derived from agricultural, forestry, and fishery products or sugars, wood chips, plant residues after obtaining useful components, ethanol of plants, biomass naphtha, etc.

[0129] As the monomers derived from biomass (biomass monomers), there is no particular limitation, and examples include butadiene derived from biomass, aromatic vinyl compounds derived from biomass, etc. As the above-mentioned butadiene, 1,2-butadiene and 1,3-butadiene can be cited. As the above-mentioned aromatic vinyl compound, there is no particular limitation, and examples include styrene, etc. In addition, the method for producing the monomers derived from biomass is not particularly limited. For example, substances obtained by biological and / or chemical and / or physical conversion of animals and plants can be cited. As the biological conversion, fermentation based on microorganisms is representative. As the chemical and / or physical conversion, conversions based on catalysts, conversions based on high heat, conversions based on high pressure, conversions based on electromagnetic waves, conversions based on supercritical fluids, and combinations thereof can be cited.

[0130] As the polymer synthesized from biomass monomer components (biomass polymer), there is no particular limitation, and examples thereof include polybutadiene rubber synthesized from biomass-derived butadiene, aromatic vinyl / butadiene copolymer synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compound, etc. As the above-mentioned aromatic vinyl / butadiene copolymer, for example, styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene can be mentioned.

[0131] Whether the raw material of the polymer is derived from biomass can be judged by pMC (percent Modern Carbon) measured according to ASTM D6866-10. pMC means: the 14 C concentration of the sample relative to that of the 14 modern standard reference of C, which is a value used as an index indicating the biomass ratio of the compound. The meaning of this value will be described below.

[0132] In 1 mole (6.02×10 23 pieces) of carbon atoms, there is about one trillionth of the normal carbon atoms, that is, about 6.02×10 11 pieces 14 of 14 C. 14 The half-life of 14 C is 5730 years, and 14 C decreases regularly. Therefore, it is considered that after carbon dioxide in the atmosphere, etc. is absorbed and immobilized by plants, etc., in fossil fuels such as coal, oil, and natural gas that have experienced more than 226,000 years, all of the 14 C elements contained therein at the time of initial immobilization have decayed. Therefore, in the 21st century today, coal, oil, natural gas and other fossil fuels contain no 14 14 C elements at all. Therefore, the chemical substances produced using these fossil fuels as raw materials also contain no 14 C elements at all. 14 On the other hand, -12 C is continuously generated by nuclear reactions in the atmosphere through cosmic rays. Therefore, 14 C reaches an equilibrium between the decrease due to radioactive decay and the generation due to nuclear reactions, and in the atmospheric environment of the earth, 13 the amount of 13 12 C is a constant amount. Therefore, in the current environment, the14 C is measured as described below. Using accelerator mass spectrometry based on a tandem accelerator, 13 the concentration of 13 C / 12 C), 14 the concentration of 14 C / 12 C) is measured. When measuring, as the standard modern carbon which is the reference for the concentration of 14 C, the 14 C concentration in the circulating carbon in nature in 1950 is adopted. As a specific reference material, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. Classify the specific radioactivity of carbon in this oxalic acid (the radioactivity intensity of 14 C per 1 g of carbon) according to each carbon isotope, correct 13 C to a fixed value, and use the value after applying the decay correction from 1950 AD to the measurement date as the standard 14 C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value.

[0135] Therefore, if the rubber is made of 100% biomass-derived substances, although there are regional differences, etc., since it is mostly not 100 under normal conditions now, it is expected to show a value of about 110 pMC. On the other hand, for chemical substances derived from fossil fuels such as petroleum, when measuring the 14 C concentration, a value of about 0 pMC (for example, 0.3 pMC) is shown. This value corresponds to a biomass ratio of 0%.

[0136] In summary, it is environmentally preferable to use materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in the rubber composition.

[0137] [Filler] The rubber composition according to this embodiment contains silica as a filler, and more preferably contains silica and carbon black. In addition, the filler can also be a filler composed only of carbon black and silica.

[0138] [Silica] ​As silicon dioxide, there is no particular limitation, for example, silicon dioxide (anhydrous silicon dioxide) prepared by a dry method, silicon dioxide (hydrous silicon dioxide) prepared by a wet method, and other silicon dioxide commonly used in the tire industry can be used. As the raw material of silicon dioxide, there is no particular limitation, for example, it can be a raw material derived from minerals such as quartz, it can also be a raw material derived from organisms such as rice husks (for example, silicon dioxide using biomass materials such as rice husks as raw materials, etc.), and silicon dioxide recovered from products containing silicon dioxide can also be used. Among them, due to the large number of silanol groups, hydrous silicon dioxide prepared by a wet method is preferred. These silicon dioxides can be used alone or in combination of two or more.

[0139] Silica made from biomass materials can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks with a sodium hydroxide solution, filtering the silicate in the same manner as conventional wet silica to form a silica precipitate by reacting with sulfuric acid, washing with water, drying, and pulverizing.

[0140] Silica recovered from products containing silica, for example, silica recovered from electronic components such as semiconductors, tires, desiccants, diatomaceous earth and other filter materials containing silica can be used. In addition, the recovery method is not particularly limited, and thermal cracking, electromagnetic wave cracking, etc. can be cited. Among them, silica recovered from electronic components such as semiconductors or tires is preferred.

[0141] If silicon dioxide is crystallized, it will not dissolve in water, and the silicic acid as its component cannot be used. By controlling the combustion temperature and combustion time, the crystallization of silicon dioxide in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Online Journal B (Akita Prefectural University ウェブジャーナルB) / 2019, vol. 6, p. 216-222, etc.).

[0142] Amorphous silica extracted from rice husks may be used as commercially available silica from Wilmar Corporation or the like.

[0143] From the viewpoint of reinforcement, the nitrogen adsorption specific surface area (N2SA) of silica is preferably greater than 110 m 2 / g, more preferably greater than 130m 2 / g, more preferably greater than 150m 2 / g, particularly preferably greater than 170m 2 / g. In addition, from the viewpoint of heat generation and processability, it is preferably less than 220m 2 / g, more preferably less than 200m 2 / g, more preferably less than 180m 2 / g. In addition, the N2SA of silica is measured by the above-mentioned measurement method.

[0144] From the viewpoint of the effects of the present invention, the average primary particle diameter of the silica is preferably greater than 10 nm, more preferably greater than 12 nm, and still more preferably greater than 14 nm. In addition, the average primary particle diameter is preferably less than 20 nm, more preferably less than 18 nm, and still more preferably less than 17 nm. In addition, the average primary particle diameter of the silica is measured by the above-described measurement method.

[0145] 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 90 parts by mass or more, preferably greater than 90 parts by mass, and more preferably 95 parts by mass or more. In addition, the content of silica relative to 100 parts by mass of the rubber component is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and still more preferably 110 parts by mass or less.

[0146] From the viewpoint of the effects of the present invention, the content of silica in the filler is preferably greater than 60% by mass, more preferably greater than 70% by mass, still more preferably greater than 72% by mass, and particularly preferably greater than 75% by mass. In addition, from the viewpoint of abrasion resistance performance, it is preferably 95% by mass or less, more preferably 92% by mass or less, and still more preferably 90% by mass or less.

[0147] <Carbon black> As the carbon black, there is no particular limitation, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw material of the carbon black may be a biomass material such as lignin or vegetable oil, or may be a pyrolysis oil obtained by thermally cracking waste tires. In addition, the manufacturing method of the carbon black may be a combustion-based method such as a furnace method, a method based on hydrothermal carbonization (HTC), or a method based on thermal cracking of methane derived from a thermal cracking carbon 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., Columbia Carbon Company, etc. can be used. These carbon blacks may be used alone or in combination of two or more.

[0148] In addition, as the carbon black, in addition to the above, from the viewpoint of life cycle assessment, etc., recycled carbon black obtained by thermally cracking and refining carbon black using a biomass material such as lignin as a raw material or products containing carbon black such as tires may also be used.

[0149] In this specification, "regenerated carbon black" refers to carbon black obtained by crushing used tires and other products containing carbon black and burning the crushed products, and the mass ratio of the unburned component, i.e., ash (ash content) is 13% by mass or more when heated in air to oxidatively burn using the thermogravimetric method based on JIS K 6226-2:2003. In other words, the mass ratio of the reduced amount (carbon content) of the regenerated carbon black based on the above-mentioned oxidative combustion is 87% by mass or less. Regenerated carbon black is sometimes also represented by rCB.

[0150] Regenerated carbon black can be obtained by thermal cracking of used pneumatic tires. For example, European Patent Application Publication No. 3427975 states that Rubber Chemistry and Technology, Vol. 85, No. 3, pp. 408-449 (2012), especially pp. 438, 440, 442, states that it can be obtained by thermal cracking of organic materials at 550-800°C after removing oxygen, or by vacuum thermal cracking at relatively low temperatures (

[0027] ). The carbon black obtained by such a thermal cracking process is generally a regenerated carbon black lacking functional groups on its surface, as mentioned in

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

[0151] Regenerated carbon black may be carbon black lacking functional groups on its surface, or may be carbon black treated so that its surface contains functional groups. The treatment to make the surface of the recycled carbon black contain functional groups can be implemented by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black containing hydroxyl and / or carboxyl groups on its surface is obtained by treating the carbon black obtained by the thermal cracking process with potassium permanganate under acidic conditions. In addition, in Patent No. 6856781, the carbon black obtained by the thermal cracking process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain a carbon black whose surface is activated. The regenerated carbon black involved in this embodiment includes these carbon blacks treated to make the surface contain functional groups.

[0152] As the regenerated carbon black, commercially available products such as Strable Green Carbon and LD Carbon can be used.

[0153] From the perspective of reinforcement, the nitrogen adsorption specific surface area (N2SA) of carbon black is preferably greater than 70 m 2 / g, more preferably greater than 100m 2 / g, more preferably greater than 120m 2 / g, particularly preferably greater than 140m2 / g. Further, from the viewpoints of heat generation and processability, it is preferably less than 250 m 2 / g, more preferably less than 220 m 2 / g, still more preferably less than 190 m 2 / g. In addition, the N2SA of the carbon black is measured by the above-mentioned measurement method.

[0154] The average primary particle diameter of the carbon black is preferably less than 32 nm, more preferably less than 28 nm, still more preferably less than 24 nm, still more preferably less than 20 nm, particularly preferably less than 21 nm, and most preferably less than 18 nm. In addition, the average primary particle diameter is preferably greater than 8 nm, more preferably greater than 10 nm, still more preferably greater than 12 nm, and particularly preferably greater than 14 nm. In addition, the average primary particle diameter of the carbon black is measured by the above-mentioned measurement method.

[0155] From the viewpoint of abrasion resistance, the content of the carbon black relative to 100 parts by mass of the rubber component is preferably greater than 1 part by mass, more preferably 5 parts by mass or more, still more preferably 8 parts by mass or more, and particularly preferably greater than 9 parts by mass. In addition, 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.

[0156] <Other fillers> The filler may further contain other fillers other than silica and carbon black. There is no particular limitation on the other fillers. For example, substances commonly used in the tire industry in the past, such as aluminum hydroxide, calcium carbonate, alumina, clay, and talc, can be compounded.

[0157] The total content of the filler relative to 100 parts by mass of the rubber component is preferably greater than 90 parts by mass, more preferably greater than 95 parts by mass, still more preferably greater than 100 parts by mass. In addition, 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.

[0158] <Silane coupling agent> Silica is preferably used in combination with a silane coupling agent. There is no particular limitation on the silane coupling agent. For example, sulfur-containing silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide can be cited; 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; chlorine-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, etc. Among them, sulfur-containing silane coupling agents and / or mercapto-based silane coupling agents are preferred. As the silane coupling agent, for example, commercially available substances from Evonik Degussa GmbH, Momentive Performance Materials Inc., etc. can be used. These silane coupling agents can be used alone or in combination of two or more.

[0159] From the viewpoint of improving the dispersibility of silica, the content of the silane coupling agent relative to 100 parts by mass of the rubber component (the total amount when multiple silane coupling agents are used in combination) is preferably greater than 3.0 parts by mass, more preferably greater than 5.0 parts by mass, and further preferably 6.0 parts by mass or more. In addition, from the viewpoint of preventing the reduction of abrasion resistance, it is preferably less than 15 parts by mass, more preferably less than 10 parts by mass, and further preferably less than 8.0 parts by mass.

[0160] [Other compounding agents] In the rubber composition according to this embodiment, in addition to the rubber component and the filler, compounding agents commonly used in the tire industry in the past can be appropriately contained, such as plasticizers, vulcanized rubber particles, processing aids, waxes, stearic acid, zinc oxide, anti-aging agents, vulcanizing agents, vulcanization accelerators, etc.

[0161] [Plasticizer] A plasticizer refers to a material that imparts plasticity to the rubber component, and is a concept including both plasticizers that are liquid at 25°C and plasticizers that are solid at normal temperature (25°C). Examples of plasticizers include resin components, oils, liquid rubbers, ester-based plasticizers, etc. These plasticizers can be substances derived from mineral resources such as petroleum and natural gas, or substances derived from biomass. In addition, low-molecular-weight hydrocarbon components obtained by thermally cracking and extracting used tires and products containing various components can also be used as plasticizers. These plasticizers can be used alone or in combination of two or more.

[0162] (Resin component) The resin component is not particularly limited, and resin components commonly used in the tire industry can be used. For example, adhesive 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 phenolic-based resins can be cited. These resin components can be used alone or in combination of two or more. The rubber composition according to the present embodiment preferably contains a resin component containing dicyclopentadiene, styrene, and indene as monomer components.

[0163] 《Dicyclopentadiene-based resin》 "Dicyclopentadiene-based resin" refers to a resin containing cyclopentadiene (CPD) or dicyclopentadiene (DCPD) as monomer components, and may also be their hydrogenated products or modified products. As dicyclopentadiene-based resins, for example, DCPD / C9 resins containing dicyclopentadiene and the following C9 fraction as monomer components can be cited (the DCPD / C9 resin may also be their hydrogenated products or modified products), preferably DCPD / C9 resins containing dicyclopentadiene and styrene as monomer components, and particularly preferably DCPD / C9 resins containing dicyclopentadiene, styrene, and indene as monomer components. As dicyclopentadiene-based resins, for example, commercially available substances from ExxonMobil, ENEOS Corporation, Zeon Corporation, Maruzen Petrochemical Co., Ltd., etc. These dicyclopentadiene-based resins can be used alone or in combination of two or more.

[0164] 《Aromatic vinyl-based resin》 "Aromatic vinyl-based resin" refers to a resin containing aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-chlorostyrene as the monomer component with the largest content, and may also be their hydrogenated products or modified products. As aromatic vinyl-based resins, due to economic efficiency, easy processing, and excellent heat generation properties, homopolymers of α-methylstyrene or styrene or copolymers of α-methylstyrene and styrene are preferred, and copolymers of α-methylstyrene and styrene are more preferred. As aromatic vinyl-based resins, for example, commercially available substances from Kraton Corporation, Eastman Chemical Company, Mitsui Chemicals, Inc., etc. These aromatic vinyl-based resins can be used alone or in combination of two or more.

[0165] 《Coumarone-based resin》 "Coumarone resin" refers to: a resin containing coumarone as a monomer component, which may also be its hydrogenated product or modified product. As coumarone resin, for example, coumarone / indene resin containing coumarone and indene as monomer components, coumarone / indene / styrene resin containing coumarone, indene and styrene as monomer components, etc. can be cited. These coumarone resins can be used alone, or two or more of them can be used in combination.

[0166] "Indene resin" "Indene resin" refers to: a resin containing indene as a monomer component, which may also be its hydrogenated product or modified product. As indene resin, for example, coumarone / indene resin containing coumarone and indene as monomer components, coumarone / indene / styrene resin containing coumarone, indene and styrene as monomer components, etc. can be cited. These indene resins can be used alone, or two or more of them can be used in combination.

[0167] "C9 resin" "C9 resin" refers to: a resin obtained by polymerizing C9 fraction, which may be a resin obtained by polymerizing C9 fraction alone, or a copolymer obtained by copolymerizing C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) with C9 fraction is called DCPD / C9 resin. In addition, it may also be its hydrogenated product or modified product. As C9 fraction, for example, petroleum fractions having 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, dicyclopentadiene, etc. can be cited. These C9 resins can be used alone, or two or more of them can be used in combination.

[0168] "C5 resin" "C5 resin" refers to: a resin obtained by polymerizing C5 fraction, which may also be its hydrogenated product or modified product. As C5 fraction, for example, petroleum fractions having 4 to 5 carbon atoms such as cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, pentadiene, etc. can be cited. These C5 resins can be used alone, or two or more of them can be used in combination.

[0169] "C5C9 resin" "C5C9 resin" refers to: a resin obtained by copolymerizing the above C5 fraction with the above C9 fraction, which may also be its hydrogenated product or modified product. As C5C9 petroleum resin, for example, substances commercially available from Tosoh Corporation, LUHUA Company, etc. These C5C9 resins can be used alone, or two or more of them can be used in combination.

[0170] "Terpene resin" "Terpene resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, dipentene, etc. as the monomer component with the highest content, and may also be their hydrogenated products or modified products. As specific examples of terpene resin, for example, polyterpene resin containing only one or more of the above terpene compounds as monomer components can be cited; aromatic modified terpene resin containing the above terpene compounds and aromatic compounds as monomer components; terpene phenol resin containing the above terpene compounds and phenolic compounds as monomer components, etc. As the monomer component of aromatic modified terpene resin, that is, aromatic compounds, for example, styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. can be cited. As the monomer component of terpene phenol resin, that is, phenolic compounds, for example, phenol, bisphenol A, cresol, xylenol, etc. can be cited. These terpene resins can be used alone or in combination of two or more.

[0171] "Rosin Resin" "Rosin resin" refers to a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc., and may also be their hydrogenated products or modified products. As rosin resin, there is no particular limitation, for example, natural resin rosin, rosin modified resin obtained by hydrogenating, disproportionating, dimerizing, esterifying, etc. of rosin can be cited. These rosin resins can be used alone or in combination of two or more.

[0172] "Phenolic Resin" "Phenolic resin" refers to a resin containing phenolic compounds such as phenol, cresol, etc. as the monomer component with the highest content. As phenolic resin, there is no particular limitation, and examples include phenol formaldehyde resin, alkylphenol formaldehyde resin, alkylphenol acetylene resin, oil-modified phenol formaldehyde resin, etc. These phenolic resins can be used alone or in combination of two or more.

[0173] "Softening Point" From the viewpoint of wet grip performance, the softening point of the resin component is preferably 80 °C or higher, more preferably 90 °C or higher, and further preferably 100 °C or higher. In addition, from the viewpoints of improving processability and the dispersibility of the rubber component and the filler, it is preferably 150 °C or lower, more preferably 140 °C or lower, and further preferably 130 °C or lower. In addition, the softening point of the resin is measured by the above-mentioned measurement method.

[0174] "Content" The total content of the resin component relative 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, still more preferably more than 24 parts by mass, and particularly preferably more than 30 parts by mass. On the other hand, from the viewpoint of suppressing heat generation, the content is preferably less than 100 parts by mass, more preferably less than 80 parts by mass, and still more preferably 45 parts by mass or less.

[0175] The content of the dicyclopentadiene-based resin relative to 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, and particularly preferably 25 parts by mass or more. On the other hand, from the viewpoint of suppressing heat generation, the content is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and still more preferably 45 parts by mass or less.

[0176] (Oil) Examples of the oil include mineral oil, vegetable oil, animal oil, etc. In addition, from the viewpoint of life cycle assessment, an oil refined from waste oil used in a rubber mixer or an engine or waste cooking oil used in a restaurant can also be used.

[0177] In this specification, 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 MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. In addition, due to environmental measures, an oil with a low content of polycyclic aromatic (polycyclic aromatic compound: PCA) compounds can also be used. Examples of the oil with a low PCA content include MES, TDAE, and heavy naphthenic oil.

[0178] "Vegetable oil" in this specification refers to, 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, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grape seed oil, candelilla wax, etc. Further, as vegetable oils, there may also be mentioned refined oils (such as salad oil) obtained by refining the above oils, transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidatively polymerized oils obtained by oxidizing the above oils, waste cooking oils obtained by recovering the oils used as cooking oils, etc. In addition, vegetable oils can be liquid or solid at normal temperature (25°C). These can be used alone, or two or more of them can be used in combination. In addition, the above vegetable oils are components included in the aforementioned plasticizers and can also be used in combination with other plasticizers. In addition, a part of the plasticizer components in a known rubber composition can be equivalently replaced with these vegetable oils to satisfy the relationship of the present invention.

[0179] The vegetable oil related to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In addition, in this specification, acylglycerol refers to a compound in which the hydroxyl group of glycerol forms an ester bond with a fatty acid. As acylglycerol, there is no particular limitation, and it can be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Further, acylglycerol can be a monomer, a dimer, or a polymer of trimer or higher. In addition, acylglycerols of dimer or higher can be obtained by thermal polymerization, oxidative polymerization, etc. In addition, acylglycerol can be liquid or solid at normal temperature (25°C).

[0180] As a method for confirming whether acylglycerol is contained in a rubber composition, there is no particular limitation, and it can be confirmed by 1 1H-NMR measurement. Specifically, the rubber composition compounded with triacylglycerol is immersed in deuterated chloroform at normal temperature (25°C) for 24 hours. After removing the rubber composition, 1H-NMR is measured at room temperature. 1 When the signal of tetramethylsilane (TMS) is set to 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm can be observed. It is speculated that these signals are signals from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group, and it can be confirmed that acylglycerol is contained. In addition, "around" here refers to a range of ±0.10 ppm.

[0181] As the above fatty acids, there is no particular limitation, and they can be unsaturated fatty acids or saturated fatty acids. As unsaturated fatty acids, monounsaturated fatty acids such as oleic acid or polyunsaturated fatty acids such as linoleic acid and linolenic acid can be cited. In addition, as saturated fatty acids, butyric acid, lauric acid, etc. can be cited.

[0182] Among them, as the above fatty acids, those containing fewer double bonds, that is, saturated fatty acids or monounsaturated fatty acids, are preferably oleic acid. As such vegetable oils containing fatty acids, for example, vegetable oils containing saturated fatty acids or monounsaturated fatty acids can be used, or modified vegetable oils such as those obtained by transesterification can also be used. In addition, in order to produce such vegetable oils containing fatty acids, plants can also be improved through variety improvement, genetic modification, etc.

[0183] As vegetable oils, for example, commercially available substances from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0184] As animal oils, fish oil, beef tallow, or oil alcohols derived therefrom can be cited.

[0185] When containing oil, from the viewpoint of processability, its 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, further preferably more than 15 parts by mass, and particularly preferably 20 parts by mass or more. In addition, from the viewpoint of wear resistance, it is preferably less than 100 parts by mass, more preferably less than 50 parts by mass, and further preferably 30 parts by mass or less.

[0186] (Liquid rubber) 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 cited. These liquid rubbers can be used alone or in combination of two or more.

[0187] (Ester plasticizer) As ester plasticizers, for example, dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), dilauryl 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. can be cited. The ester plasticizers can be used alone or in combination of two or more.

[0188] From the viewpoint of wet grip performance, the content of the plasticizer relative to 100 parts by mass of the rubber component (the total amount when using multiple plasticizers) is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, further preferably 40 parts by mass or more, and particularly preferably more than 50 parts by mass. In addition, from the viewpoint of processability, it is preferably less than 110 parts by mass, more preferably less than 100 parts by mass, further preferably less than 80 parts by mass, and particularly preferably 70 parts by mass or less.

[0189] (Vulcanized rubber particles) Vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder specified in JIS K 6316:2017 can be used. From the viewpoints of environmental consideration and cost, recycled rubber powder made from crushed waste tires, etc. is preferably used. These can be used alone or in combination of two or more.

[0190] As the vulcanized rubber particles, there is no particular limitation, and they can be unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0191] As commercially available products of vulcanized rubber, for example, products of Lehigh Company, Murakami Rubber Industry Co., Ltd., etc. can be used.

[0192] (Processing aids) As processing aids, for example, fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, mixtures of fatty acid metal salts and fatty acid amides, etc. can be cited. These processing aids can be used alone or in combination of two or more. As processing aids, for example, substances commercially available from Schill+Seilacher Company, Performance-Additives Company, etc. can be used.

[0193] When a processing aid is contained, from the viewpoint of exerting the improvement effect of processability, its content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1 part by mass, and still more preferably more than 1.5 parts by mass. In addition, from the viewpoints of abrasion resistance and breaking strength, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and still more preferably less than 5.0 parts by mass.

[0194] (Wax) The wax is not particularly limited, and any one of the substances commonly used in the tire industry can be preferably used. For example, mineral waxes, waxes derived from plants, etc. can be cited. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Waxes derived from plants refer to waxes derived from natural resources such as plants. Among them, mineral waxes are preferred. As waxes derived from plants, for example, rice bran wax, carnauba wax, candelilla wax, etc. can be cited. As mineral waxes, for example, paraffin wax, microcrystalline wax, selected special waxes thereof, etc. can be cited, and paraffin wax is preferred. In addition, the wax involved in the present embodiment is a wax not containing stearic acid. The wax can be, for example, a commercially available substance from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., etc. These waxes can be used alone or in combination of two or more.

[0195] When wax is contained, from the viewpoint of the weather resistance of the rubber, its content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and still more preferably more than 1.5 parts by mass. In addition, from the viewpoint of preventing the whitening of the tire caused by blooming, it is preferably less than 10 parts by mass, more preferably less than 7.0 parts by mass, and still more preferably less than 5.0 parts by mass.

[0196] (Stearic acid) When stearic acid is contained, from the viewpoint of processability, its content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and still more preferably more than 1.5 parts by mass. In addition, from the viewpoint of vulcanization rate, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and still more preferably less than 5.0 parts by mass.

[0197] (Zinc oxide) When zinc oxide is contained, from the viewpoint of processability, its content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and still more preferably more than 1.5 parts by mass. In addition, 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.

[0198] (Antioxidant) As the anti-aging agent, there is no particular limitation, and examples thereof include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine, 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based anti-aging agents such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-dimethylxylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-tert-butyl-4-methylphenol, styrenated phenol; bis-, tri-, polyphenol-based anti-aging agents such as tetrakis[methylene-3-(3,5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industrial Co., Ltd., Flexis Co., etc. can be used. These anti-aging agents can be used alone or in combination of two or more kinds.

[0199] When containing the anti-aging agent, from the viewpoint of ozone crack resistance of the rubber, its content relative to 100 parts by mass of the rubber component (when multiple anti-aging agents are used in combination, it is the total amount of all) is preferably greater than 1.0 part by mass, more preferably greater than 2.0 part by mass, and further preferably greater than 2.5 part by mass. In addition, from the viewpoints of abrasion resistance and wet grip performance, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and further preferably less than 5.0 parts by mass.

[0200] (Vulcanizing agent) As the vulcanizing agent, sulfur can be preferably used. As sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, etc. can be used.

[0201] When containing sulfur, from the viewpoint of ensuring sufficient vulcanization reaction, its content relative to 100 parts by mass of the rubber component is preferably greater than 0.5 part by mass, more preferably greater than 1.5 part by mass, further preferably greater than 1.0 part by mass, and particularly preferably 1.5 part by mass or more. In addition, from the viewpoint of preventing deterioration, it is preferably less than 5.0 parts by mass, more preferably less than 3.0 parts by mass, and further preferably less than 2.0 parts by mass. In addition, when using sulfur containing oil as the vulcanizing agent, the content of the vulcanizing agent is set as the total content of the pure sulfur component contained in the sulfur containing oil.

[0202] As a vulcanizing agent other than sulfur, known organic crosslinking agents can be used. As the organic crosslinking agent, as long as it is a substance capable of forming a crosslinked chain other than a polysulfide bond, there is no particular limitation. For example, alkylphenol / sulfur chloride condensates, sodium 1,6-hexamethylenedithiocarbamate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, dicumyl peroxide, etc. can be cited, and 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane is preferred. These organic crosslinking agents can use commercially available substances from companies such as Taoka Chemical Industry Co., Ltd., Lanxess Corporation, and Flexis Corporation.

[0203] (Vulcanization accelerator) As the vulcanization accelerator, there is no particular limitation. For example, sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiuram-based vulcanization accelerators, thiourea-based vulcanization accelerators, dithiocarbamate-based vulcanization accelerators, aldehyde-amine-based vulcanization accelerators, aldehyde-ammonia-based vulcanization accelerators, imidazoline-based vulcanization accelerators, xanthate-based vulcanization accelerators, caprolactam disulfide, etc. can be cited. These vulcanization accelerators can be used alone or in combination of two or more. Among them, from the point of view of better obtaining the desired effect, one or more vulcanization accelerators selected from sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, and guanidine-based vulcanization accelerators are preferred.

[0204] As the sulfenamide-based vulcanization accelerator, for example, N-tert-butyl-2-benzothiazole sulfenamide (TBBS), N-cyclohexyl-2-benzothiazole sulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazole sulfenamide (DCBS), etc. can be cited.

[0205] As the thiazole-based vulcanization accelerator, for example, 2-mercaptobenzothiazole (MBT) or its salt, bis-2-benzothiazole disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio)benzothiazole, etc. can be cited.

[0206] As the guanidine-based vulcanization accelerator, for example, 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenyl guanidine, 1,3-di-o-cumenyl-2-propionylguanidine, etc. can be cited.

[0207] As thiuram vulcanization accelerators, for example, tetra(2-ethylhexyl)thiuram disulfide (TOT-N), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetramethylthiuram monosulfide (TMTM), dipentamethylenethiuram disulfide, dipentamethylenethiuram tetrasulfide, etc. can be cited.

[0208] As thiourea vulcanization accelerators, for example, thiourea compounds such as thiocarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea, di-o-tolylthiourea, etc., N,N'-diphenylthiourea, trimethylthiourea, N,N'-diethylthiourea, etc. can be cited.

[0209] As dithiocarbamate vulcanization accelerators, for example, 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), etc. can be cited.

[0210] When a vulcanization accelerator is contained, its content relative to 100 parts by mass of the rubber component (when a plurality of vulcanization accelerators are used in combination, it is the total amount of all) is preferably more than 3.0 parts by mass, more preferably more than 4.0 parts by mass, and further preferably 5.0 parts by mass or more. In addition, the content of the vulcanization accelerator relative 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 further preferably less than 6.0 parts by mass.

[0211] In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may also be derived from carbon dioxide in the atmosphere. As a method for obtaining the various materials from carbon dioxide, carbon dioxide can be directly converted, or methane obtained through a methanation process of synthesizing methane from carbon dioxide can be converted.

[0212] [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 mill, a closed kneader (Banbury mixer, kneader, etc.).

[0213] The kneading process, for example, includes the following basic kneading processes: kneading compounding agents and additives other than vulcanizing agents and vulcanization accelerators, and a final kneading process (F kneading): adding vulcanizing agents and vulcanization accelerators to the kneaded material obtained in the basic kneading process and kneading. Further, the above basic kneading process can also be decomposed into multiple processes as needed. When decomposing the basic kneading process, the method can be: (1) a method of pre-kneading a part of the compounding agents and additives, making them into master batches, and then adding the remaining compounding agents and additives to the obtained master batches and kneading, or it can be: (2) a method of kneading all the compounding agents and additives kneaded in the basic kneading process once and then remilling the kneaded material more than once, etc. In the method of (1) above, the number of master batches is not limited, and it can also be two or more. In addition, when the number of master batches is two or more, it can be a method in which all the compounding agents and additives used in the basic kneading process are distributed in any master batch.

[0214] As the kneading conditions, there are no particular limitations. For example, a method can be cited in which in the basic kneading process, kneading is carried out at a discharge temperature of 150 to 170 °C for 3 to 10 minutes, and in the final kneading process, kneading is carried out at 70 to 110 °C for 1 to 5 minutes. As the vulcanization conditions, there are no particular limitations. For example, a method can be cited in which vulcanization is carried out at 150 to 200 °C for 10 to 30 minutes.

[0215] The tire of this embodiment having a tread portion composed of the rubber composition according to this embodiment can be manufactured by a conventional method. That is, the tire can be manufactured by: compounding the above components as needed with respect to the rubber component, extruding and processing the prepared unvulcanized rubber composition in accordance with the shape of the tread portion, laminating the obtained tread portion with other tire components on a tire building machine by a conventional method, forming an unvulcanized tire by forming, and heating and pressurizing the obtained unvulcanized tire in a vulcanizer. As the vulcanization conditions, there are no particular limitations. For example, a method can be cited in which vulcanization is carried out at 150 to 200 °C for 10 to 30 minutes.

[0216] [Use] The tire of this embodiment can be used for any application, whether it is a pneumatic tire or a non-pneumatic tire, and can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a racing tire, a motorcycle tire, a heavy-duty tire, and a run-flat tire. In addition, a passenger car tire refers to a tire with a maximum load capacity of less than 1400 kg on the premise of being installed on a four-wheeled vehicle. In addition, a heavy-duty tire refers to a tire with a maximum load capacity of 1400 kg or more. In addition, the tire of this embodiment can be used for winter tires such as studless tires in addition to all-season tires and summer tires.

Example

[0217] The following shows examples (embodiments) considered to be preferable during implementation, but the scope of the present invention is not limited to the embodiments. Using various drugs shown below, the tires obtained according to Table 1 or Table 2 were studied, and the results calculated based on the following evaluation methods are shown in Tables 1 to 2.

[0218] <Various drugs> NR: TSR20 SBR1: SBR manufactured by the following Production Example 1 (S-SBR, Tg: -50°C, styrene content: 25% by mass, vinyl content: 25 mol%, Mw: 1 million, non-oil-extended) SBR2: SBR manufactured by the following Production Example 2 (S-SBR, Tg: -36°C, styrene content: 38% by mass, vinyl content: 31 mol%, Mw: 1.127 million, non-oil-extended) SBR3: 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%, 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: 17 nm) Silane coupling agent 1: Si266 manufactured by Evonik Degussa GmbH (bis(3-triethoxysilylpropyl) disulfide) Silane coupling agent 2: NXT manufactured by Momentive Performance Materials Inc. (3-octanoylthiopropyltriethoxysilane) Resin component 1: SYLVATRAXX 4401 manufactured by Kraton Corporation (α-methylstyrene resin, softening point: 85°C) Resin component 2: SYLVATRAXX 4150 manufactured by Kraton Corporation (polyterpene resin, softening point: 115°C) Resin component 3: Oppera PR-395 manufactured by ExxonMobil Chemical Company (hydrogenated DCPD / C9 resin, resin containing dicyclopentadiene, styrene, and indene as monomer components, softening point: 118°C) Oil: VivaTec500 manufactured by H&R Co., Ltd. (TDAE oil) Wax: OZOACE 0355 manufactured by Nippon Seiro Co., Ltd. (paraffin wax) Antioxidant 1: NOCRAC 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. Antioxidant 2: NOCRAC RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. Stearic acid: Stearic acid beads "TSUBAKI" manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (powdered sulfur containing 5% oil) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator 1: NOCCELLER CZ (N-cyclohexyl-2-benzothiazolesulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. Vulcanization accelerator 2: NOCCELLER D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.

[0219] (Production Example 1: Production of SBR1) Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were added to a nitrogen-purged autoclave reactor. The ratio of styrene to 1,3-butadiene was adjusted so that the styrene content was 25% by mass. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium was added to start the polymerization. The polymerization was carried out under adiabatic conditions, and the maximum temperature reached 80°C. After confirming the formation of a polymer with an Mw of 1 million by GPC, 4 L of ethanol was injected into the polymerization solution to recover the precipitate. The obtained precipitate was dried by blowing air and then dried under reduced pressure at 80°C / 10 Pa or less until the loss on drying was 0.1% to obtain SBR1.

[0220] (Production Example 2: Production of SBR2) Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were added to a nitrogen-purged autoclave reactor. The ratio of styrene to 1,3-butadiene was adjusted so that the styrene content was 20% by mass. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium was added to start the polymerization. The polymerization was carried out under adiabatic conditions, and the maximum temperature reached 80°C. After confirming the formation of a polymer with an Mw of 700,000 by GPC, 4 L of ethanol was injected into the polymerization solution to recover the precipitate. The obtained precipitate was dried by blowing air and then dried under reduced pressure at 80°C / 10 Pa or less until the loss on drying was 0.1% to obtain SBR2.

[0221] (Examples and Comparative Examples) According to the compounding recipe shown in Table 1 or Table 2, using a 1.7L enclosed Banbury mixer, the reagents other than sulfur and vulcanization accelerators were kneaded for 4 minutes at a discharge temperature of 160°C to obtain a kneaded product. Then, using an open mill, sulfur and vulcanization accelerators were added to the obtained kneaded product and kneaded for 4 minutes until it reached 105°C to obtain an unvulcanized rubber composition. Using the obtained unvulcanized rubber composition, it was shaped according to the shape of the tread portion and adhered together with other tire components to produce an unvulcanized tire, which was vulcanized at 170°C to obtain each test tire (size: 205 / 65R15, rim: 15×6JJ, internal pressure: 230 kPa). The tread pattern of the tire with a ground contact area ratio of 0.68 is as Figure 3 shown (the groove depth at the deepest part of the circumferential groove existing in the shoulder area is set to 6.0 mm).

[0222] <Determination of acetone extraction amount (AE)> For the rubber test pieces made by cutting from the tread portions of each test tire, the AE amount was measured respectively. The AE amount can be obtained by immersing each rubber test piece in acetone at room temperature (about 25°C) for 24 hours, extracting the 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 vulcanized rubber test piece before extraction - mass of the vulcanized rubber test piece after extraction) / (mass of the rubber test piece before extraction)} × 100

[0223] <Temperature distribution curve of tanδ> For each rubber test piece made by cutting from the tread portion of each test tire with the tire circumference as the long side and the tire radial direction as the thickness direction, with a length of 20 mm × width of 4 mm × thickness of 1 mm, using a dynamic viscoelasticity measuring device (EPLEXOR series manufactured by GABO), under the conditions of a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±0.5%, and a heating rate of 2°C / minute, the temperature distribution curve of tanδ was measured in the temperature range from -20°C to 70°C. At the same time, based on the obtained temperature distribution curve of tanδ, the tanδ at the peak position and the half-peak width in the range of -20°C to -70°C were measured.

[0224] <Measurement of tanδ at 0°C> For each rubber test piece made by cutting from the tread portion of each test tire with the tire circumference as the long side and the tire radial direction as the thickness direction, with a length of 20 mm × width of 4 mm × thickness of 1 mm, using a dynamic viscoelasticity measuring device (EPLEXOR series manufactured by GABO), the loss tangent tanδ was 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 a tensile mode.

[0225] <Measurement of the glass transition temperature (Tg) of the rubber composition> For each rubber test piece cut from the tread surface of each test tire with the circumferential direction of the tire as the long side and the radial direction of the tire as the thickness direction, having a length of 20 mm × width of 4 mm × thickness of 1 mm, using a dynamic viscoelasticity measuring device (EPLEXOR series manufactured by GABO), under the conditions of a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±0.5%, and a heating rate of 2°C / minute, the temperature distribution curve of tanδ in the range of -60°C to 40°C was measured, and the temperature (tanδ peak temperature) corresponding to the maximum tanδ value in the obtained temperature distribution curve was determined as the Tg of the rubber composition.

[0226] <Wet grip performance> Each test tire was respectively mounted on the four wheels of a FF passenger car with a displacement of 2000 cc, and on a wet asphalt road surface, the braking distance starting from the braking point at a speed of 100 km / h was measured. Taking the braking distance of the test tire of the reference comparative example (Comparative Example 2) as 100, according to the following calculation formula, the wet grip performance of each tire was expressed by an index. The larger the index, the more excellent the wet grip performance. (Wet grip performance index) = (Braking distance of the tire of the reference comparative example) / (Braking distance of each test tire) × 100

[0227]

Table 1

[0228]

Table 2

[0229] <Embodiment> An embodiment of the present invention is as shown below. [1] A tire, characterized in that it is a tire having a tread surface, the tread surface has one or more circumferential grooves, the tread surface is composed of a rubber composition containing a rubber component and silica, the rubber component contains an isoprene rubber and a styrene-butadiene rubber, the content of the isoprene rubber in the rubber component is 40% by mass or more, the content of the styrene-butadiene rubber in the rubber component is 40% by mass or more, the content of the silica relative to 100 parts by mass of the rubber component is 90 parts by mass or more, the styrene content S1 (% by mass) of the styrene-butadiene rubber is 30 or less, When the ground contact area ratio of the tire is set as R and the tanδ of the rubber composition at 0°C is set as 0°C tanδ, 0°C tanδ × R is 0.30 or more. 〔2〕The tire according to the above 〔1〕, wherein the half-width at half maximum of the peak in the range of -20°C to -70°C of the tanδ temperature distribution curve of the rubber composition is 30°C or less. 〔3〕The tire according to the above 〔1〕 or 〔2〕, wherein when the acetone extraction amount of the rubber composition is set as AE (mass %), AE is 22.0 or more. 〔4〕The tire according to any one of the above 〔1〕 to 〔3〕, wherein 0°C tanδ is 0.45 or more. 〔5〕The tire according to any one of the above 〔1〕 to 〔4〕, wherein when the groove depth at the deepest part of the circumferential groove is set as H (mm), 0°C tanδ × H is 3.00 or more. 〔6〕The tire according to any one of the above 〔1〕 to 〔5〕, wherein when the total thickness of the tread portion is set as T (mm), 0°C tanδ × T is 3.50 or more. 〔7〕The tire according to any one of the above 〔1〕 to 〔6〕, wherein when the groove depth at the deepest part of the circumferential groove is set as H (mm) and the acetone extraction amount of the rubber composition is set as AE (mass %), AE × H is 140.0 or more. 〔8〕The tire according to any one of the above 〔1〕 to 〔7〕, wherein the rubber composition contains a resin component including dicyclopentadiene, styrene, and indene as monomer components. 〔9〕The tire according to any one of the above 〔1〕 to 〔8〕, wherein the rubber composition contains more than 100 parts of silica relative to 100 parts by mass of the rubber component. 〔10〕The tire according to any one of the above 〔1〕 to 〔9〕, wherein the rubber composition contains a mercapto-based silane coupling agent. 〔11〕The tire according to any one of the above 〔1〕 to 〔10〕, wherein the tread portion has two or more ground contact portions divided by the one or more circumferential grooves, and at least one of the ground contact portions has a transverse groove extending radially inward of the tire, and the transverse groove has a portion where the groove width is larger than the groove width at the tread surface in a cross section perpendicular to the extending direction. 〔12〕The tire according to any one of the above 〔1〕 to 〔11〕, wherein in the tread, when a region of 30% of the tread ground contact width centered on the tire equator is set as the central region and regions on both outer sides of the central region and within the tread ground contact width are set as a pair of shoulder regions, the groove depth at the deepest part of the circumferential groove existing in the shoulder region is 6.0 mm or more. 〔13〕The tire according to any one of the above items 〔1〕 to 〔12〕, wherein when the tire weight is set to G (kg), S1 / G is 3.0 or less. 〔14〕The tire according to any one of the above items 〔1〕 to 〔13〕, wherein S1×R is 11.0 or more. 〔15〕The tire according to any one of the above items 〔1〕 to 〔14〕, wherein 0℃tanδ×R is 0.33 or more.

Claims

1. A tire, characterized in that: It 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 isoprene-based rubber and styrene-butadiene rubber. The content of the isoprene-based rubber in the rubber component is 40% by mass or more, The content of styrene butadiene rubber in the rubber component is 40% by mass or more, The content of the silica is 90 parts by mass or more relative to 100 parts by mass of the rubber component. The styrene content S1 of the styrene butadiene rubber is less than 30, and the unit of S1 is mass %. When the contact area ratio of the tire is defined as R and the tan δ of the rubber composition at 0°C is defined as 0°C tan δ, 0°C tanδ×R is 0.30 or more.

2. The tire according to claim 1, wherein: The rubber composition has a tan δ temperature distribution curve in which the half-value width of a peak in the range of -20°C to -70°C is 30°C or less.

3. The tire according to claim 1 or 2, wherein: When the acetone extract amount of the rubber composition is denoted as AE, AE is 22.0 or more, and the unit of AE is mass %.

4. The tire according to claim 1 or 2, wherein: 0°C tanδ is 0.45 or more.

5. The tire according to claim 1 or 2, wherein: When the groove depth of the deepest part of the circumferential groove is defined as H, 0°C tanδ×H is 3.00 or more, and the unit of H is mm.

6. The tire according to claim 1 or 2, wherein: When the total thickness of the tread portion is defined as T, 0°C tanδ×T is equal to or greater than 3.50, where the unit of T is mm.

7. The tire according to claim 1 or 2, wherein: When the groove depth of the deepest part of the circumferential groove is H and the acetone extract amount of the rubber composition is AE, AE×H is 140.0 or more, where the unit of H is mm and the unit of AE is mass %.

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

9. The tire according to claim 1 or 2, wherein: The rubber composition contains more than 100 parts by mass of silica based on 100 parts by mass of the rubber component.

10. The tire according to claim 1 or 2, wherein: The rubber composition contains a mercapto-based silane coupling agent.

11. The tire according to claim 1 or 2, wherein: The tread portion has more than two ground contact portions divided by the one or more circumferential grooves, at least one of the ground contact portions has a lateral groove extending radially inward of the tire, and the lateral groove has a portion in a cross section perpendicular to the extension direction whose groove width is greater than the groove width on the tread surface.

12. The tire according to claim 1 or 2, wherein: In the tread surface, an area of ​​30% of the tread contact width centered on the tire equator is set as a central area, and areas on both sides of the central area outside the tread contact width are set as a pair of shoulder areas, and the groove depth of the deepest part of the circumferential groove in the shoulder area is greater than 6.0 mm.

13. The tire according to claim 1 or 2, wherein: When the tire weight is G, S1 / G is less than or equal to 3.0, and the unit of G is kg.

14. The tire according to claim 1 or 2, wherein: S1×R is 11.0 or more.

15. The tire according to claim 1 or 2, wherein: 0°C tanδ×R is 0.33 or more.

16. The tire according to claim 1 or 2, wherein: 0°C tanδ×R is 0.42 or less.

17. The tire according to claim 1 or 2, wherein: The content of the silica is 150 parts by mass or less based on 100 parts by mass of the rubber component.

Images