Tire

Abstract

Provided is a tire having improved overall performance of low fuel consumption performance and wet grip performance. A tire having a tread portion having one or more circumferential grooves, the tread portion comprising a rubber composition containing a rubber component, silica, and a resin component, the rubber component containing an isoprene rubber and a styrene-butadiene rubber, the silica containing at least one of the isoprene rubber and the styrene-butadiene rubber, and the resin component containing at least one of the isoprene rubber and the styrene-butadiene rubber. The content of isoprene rubber in the rubber component is 40 mass% or more, the styrene content S1 (mass%) of the styrene butadiene rubber is 30 or less, the content of silica is 30 parts by mass or more per 100 parts by mass of the rubber component, and the resin component contains a dicyclopentadiene resin. The acetone extraction amount AE (mass%) of the rubber composition is 16.0 or more, the tan [delta] of the rubber composition at 30 DEG C is 30 DEG C tan [delta], when the total thickness of the tread portion is T (mm), 30 DEG C tan [delta] * T is less than 3.0, and when the groove depth of the deepest portion of the circumferential groove is H (mm), AE * H is 100.0 or more.

Description

Technical Field

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

[0002] Generally, tires widely used in passenger cars and the like are required to achieve a high level of balance between low fuel consumption performance and wet grip performance. For example, Patent Document 1 discloses that a rubber composition containing styrene-butadiene rubber having a specific vinyl content in a specific ratio and butadiene rubber having a specific cis-1,4-bond content ratio is used to improve wet braking performance and rolling resistance performance. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-307039 Summary of the Invention [Problems to be Solved by the Invention]

[0004] In recent years, further improvement in low fuel consumption performance and wet grip performance of tires has been desired.

[0005] An object of the present invention is to provide a tire capable of improving the comprehensive performance of low fuel consumption performance and 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, silica, and a resin component, the rubber component contains an isoprene-based rubber and a styrene-butadiene rubber, the content of the isoprene-based rubber in the rubber component is 40% by mass or more, the styrene content S1 (% by mass) of the styrene-butadiene rubber is 30 or less, the content of silica relative to 100 parts by mass of the rubber component is 30 parts by mass or more, the resin component contains a dicyclopentadiene-based resin, the acetone extraction amount AE (% by mass) of the rubber composition is 16.0 or more, when the tanδ of the rubber composition at 30°C is designated as 30°C tanδ and the total thickness of the tread portion is designated as T (mm), 30°C tanδ × T is less than 3.0, when the groove depth at the deepest part of the circumferential groove is designated as H (mm), AE × H is 100.0 or more. [Advantages of the Invention]

[0007] According to the present invention, the comprehensive performance of low fuel consumption performance and wet grip performance can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

DESCRIPTION OF REFERENCE NUMERALS

[0009] A tire according to an embodiment of the present invention is a tire having a tread portion. The tread portion has one or more circumferential grooves. The tread portion is composed of a rubber composition containing a rubber component, silica, and a resin component. The rubber component contains an isoprene-based rubber and a styrene-butadiene rubber. The content of the isoprene-based rubber in the rubber component is 40% by mass or more. The styrene content S1 (% by mass) of the styrene-butadiene rubber is 30 or less. The content of silica relative to 100 parts by mass of the rubber component is 30 parts by mass or more. The resin component contains a dicyclopentadiene-based resin. The acetone extraction amount AE (% by mass) of the rubber composition is 16.0 or more. When the tanδ of the rubber composition at 30°C is set as 30°C tanδ and the total thickness of the tread portion is set as T (mm), 30°C tanδ × T is less than 3.0. When the groove depth at the deepest part of the circumferential groove is set as H (mm), AE × H is 100.0 or more.

[0010] Regarding the reasons for the improvement of the comprehensive performance of wear resistance and wet grip performance in the tire of the present invention, although it is not intended to be limited theoretically, the following speculation can be made.

[0011] The rubber composition constituting the tread portion of the tire of this embodiment, (1) by making the content of the isoprene-based rubber, which has a weak interaction with silica, 40% by mass or more, the polymer phase in the rubber composition can move softly, and the mobility of the polymer is improved. As a result, by improving the followability to the microscopic road surface, it helps to improve the wet grip performance. In addition, (2) by setting the styrene content S1 (% by mass) of the styrene-butadiene rubber to 30 or less, a minute styrene phase region (domin) is formed in the rubber mechanism, and the mobility of the polymer phase in the rubber composition is further improved by the soft movement of this minute phase region. In addition, (3) by setting the content of silica to 30 parts by mass or more, silica aggregates in the polymer phase, which helps to further improve the wet grip performance.

[0012] In addition, in the rubber composition constituting the tread surface of the tire of the present invention, (4) by setting the acetone extraction amount AE of the rubber composition to 16.0% by mass or more, a certain amount of plasticizer is contained in the rubber composition, the dispersibility of silica is improved, and the balance between low fuel consumption performance and wet grip performance is improved. In addition, (5) since the compatibility of the dicyclopentadiene resin with the isoprene-based rubber, styrene, and butadiene rubber is good and the dispersibility of the polymer is improved, the balance between low fuel consumption performance and wet grip performance is improved.

[0013] In the tire of the present invention, (6) by setting 30°C tanδ × T to less than 3.0, thinning the thickness of the tread surface, suppressing heat accumulation, and reducing 30°C tanδ, it is possible to synergistically suppress the heat generation of the tread rubber. In addition, (7) by setting the AE amount × H to 140.0 or more, the efficiency of dispersion and distribution of the filler is improved, the rigidity of the rubber composition can be reduced, and since the dispersibility of the polymer and the filler is improved, the low fuel consumption performance and wet grip performance are improved. It is considered that by the synergistic action of the above (1) to (7), a particularly remarkable effect of improving the comprehensive performance of low fuel consumption performance and wet grip performance can be achieved.

[0014] From the viewpoint of low fuel consumption performance, the above rubber composition preferably contains 1 part by mass or more and 10 parts by mass or less of carbon black with respect to 100 parts by mass of the rubber component.

[0015] From the viewpoint of suppressing the heat generation of the rubber, 30°C tanδ is preferably 0.30 or less.

[0016] From the viewpoints of suppressing heat accumulation and heat generation, 30°C tanδ × T is preferably 3.0 or less.

[0017] The total styrene amount S2 (mass%) in the above rubber component is preferably 15 or less. It is considered that by setting the total styrene amount S2 to 15% by mass or less, minute styrene phase regions are formed in the rubber matrix, and 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.

[0018] From the viewpoint of wet grip performance, 0°C tanδ is preferably 0.45 or more.

[0019] S1 × R is preferably 11.0 or more. It is considered that by setting S1 × R to 11.0 or more, the minute styrene phase regions formed in the rubber phase move flexibly, the mobility of the polymer is improved, the followability of the tread surface to the road surface is improved, the contact area between the tread surface and the road surface is increased, and the wet grip performance is further improved.

[0020] When the tire weight is set to G (kg), S1 / G is preferably 3.0 or less. The lighter the tire, the smaller the force pressing the grounding portion against the road surface becomes. Therefore, as the tire becomes lighter, even a small amount of styrene portion aggregation will have a greater impact on the tread surface. It is considered that as the tire weight decreases, by reducing S1, the heat generation property can be reduced and the low fuel consumption performance can be further improved.

[0021] From the viewpoint of the effects of the present invention, the above dicyclopentadiene-based resin preferably contains a resin having dicyclopentadiene, styrene, and indene as monomer components.

[0022] The above tread portion preferably has a grounding portion divided by the above one or more circumferential grooves, the grounding portion has a transverse groove extending radially inward of the tire, and at least one of the transverse grooves has a groove width greater than the groove width at the tread surface in the radial inner side of the tire.

[0023] It is considered that by disposing the above transverse groove in the grounding portion, even if wear progresses, an increase in compression rigidity can be suppressed, and wet grip performance can be ensured.

[0024] In the tread surface of the above tread portion, when a region of 30% of the tread grounding 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 grounding width are set as a pair of shoulder regions, the groove depth at the deepest part of the circumferential groove existing in the above shoulder region is preferably 6.0 mm or more.

[0025] It is considered that by the above configuration, drainage performance can be improved, and thus it helps to improve wet grip performance.

[0026] In the above tread portion, when the thickness of the layer whose outer surface constitutes the tread surface is set to t1 (mm) and the thickness of the belt layer is set to B (mm), B is 0.9 or more and 1.2 or less, and t1 / B is preferably 7.0 or less.

[0027] It is considered that by setting the thickness B of the belt layer to 0.9 mm or more, rubber breakage can be suppressed, and thus wear resistance can be further improved. By setting it to 1.2 mm or less, rubber heat generation can be suppressed, and thus low fuel consumption performance can be improved. It is considered that by setting t1 / B to 7.0 or less, the thickness of the layer whose outer surface constitutes the tread surface can be thinned, rolling resistance can be reduced, and grip performance can be improved.

[0028] The groove bottom wall thickness (gauge) of the above tread portion is preferably 1.0 mm or more and 4.0 mm or less. It is considered that by setting the groove bottom wall thickness within the above range, heat generation of the tread rubber can be suppressed, which may help to improve low fuel consumption performance.

[0029] [Definition] "Styrene content S1 (mass%) of styrene-butadiene rubber" is the styrene content (mass%) of styrene-butadiene rubber (SBR). When the rubber composition contains one kind of SBR, it is the styrene content of that SBR. When the rubber composition contains multiple kinds of SBR, it can be obtained by the sum of the products of the styrene content of each SBR and the compounding amount (mass%) of that SBR when the total SBR is set to 100 mass%.

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

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

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

[0033] "Acetone extraction (AE) amount" is the value obtained by immersing each vulcanized rubber test piece in acetone at normal temperature (about 25°C) for 72 hours according to JIS K 6229:2015, extracting the 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

[0034] "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 / min. The temperature corresponding to the maximum value in the range above -60 °C and below 40 °C of the obtained temperature distribution curve (tanδ peak temperature). 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.

[0035] "tanδ at 30 °C" is the tangent of the loss angle measured using a dynamic viscoelasticity measuring device (for example, the EPLEXOR series manufactured by GABO) under the conditions of a temperature of 30 °C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and a tensile mode. The sample for measuring tanδ at 30 °C is a vulcanized rubber composition with a length of 20 mm × a width of 4 mm × a thickness of 1 mm. When 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.

[0036] "tanδ at 0 °C" is the tangent of the loss angle 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 this measurement is manufactured in the same way as in the case of tanδ at 30 °C.

[0037] "The tread surface" is the part that forms the 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 compared to these components.

[0038] "Normal state" means: A state without load that is assembled on a normal rim and filled with air at normal internal pressure.

[0039] "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, the "dimensions of each part of the tire" existing inside the tire, for example, are values specified in the state where the tire is cut by a plane including the tire rotation axis and the cut tire piece maintains the rim width of the normal rim.

[0040] "Normal 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 described in the "JATMA YEAR BOOK" of JATMA (Japan Automobile Tire Manufacturers Association), the "Measuring Rim" described in the "STANDARDS MANUAL" of ETRTO (The European Tyre and Rim Technical Organisation), and the "Design Rim" described in the "YEAR BOOK" of TRA (The Tire and Rim Association, Inc.). Refer to them in the order of JATMA, ETRTO, and TRA, and follow the standards of the applicable sizes if any when referring. In addition, for a tire not specified in the above standards, it means 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).

[0041] "Normal 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 described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" of TRA. Similar to the case of the normal rim, refer to them in the order of JATMA, ETRTO, and TRA, and follow the standards of the applicable sizes if any when referring. In addition, for a tire not specified in the above standards, it means the normal internal pressure (where it is 250 kPa or more) of other tire sizes (where the tire is specified in the standards) with the above normal rim as the standard rim. When there are multiple normal internal pressures of 250 kPa or more, it refers to the minimum value among them.

[0042] "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, and when applicable dimensions are available during the reference, the standards thereof shall be followed. Meanwhile, for tires not specified in the above-mentioned standards, the maximum load capacity W calculated separately shall be used as the normal load. L It shall be set as the normal load.

[0043] "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 tire diameter direction in 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 through (Dt - R) / 2. When there are patterns or letters on the tire sidewall, Wt is the value obtained after removing these. In addition, the maximum load capacity has the same meaning as the above-mentioned normal load.

[0044]

Equation 1

[0045] "Contact area" refers to 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 static 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 (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 successively for a total of 5 times to perform the above-mentioned transfer operation and taking the average value of the 5 obtained areas.

[0046] 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 against the ground. It can be obtained by assembling the tire on a standard rim, filling it with the standard internal pressure, leaving it static at 25°C for 24 hours, then applying ink to the surface of the tire tread, loading the tire with the standard load (maximum load capacity), and vertically pressing it onto cardboard (with a camber angle of 0°) to transfer the ink. The area of the effective contact area region is the effective contact area. The effective contact area can be calculated by rotating the tire by 72 degrees successively at a total of 5 positions for the above transfer operation and taking the average of the 5 obtained areas.

[0047] 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. Contact area ratio = (Effective contact area / Total contact area)

[0048] A "groove" refers to a recess formed on the surface of the tire tread that extends radially inward of the tire, and specifically refers to a recess with a groove width (opening width) of 2.0 mm or more at the surface of the tread. Similarly, those smaller than 2.0 mm are called "sipe".

[0049] A "circumferential groove" refers to a groove that continuously extends 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.

[0050] 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 this 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 this groove (in addition, except for the depth at locations such as intersections of multiple grooves with three or more branches in the object of the groove depth definition in this specification).

[0051] The "groove bottom wall thickness" refers to the thickness of the rubber from the deepest part of the circumferential groove to the cord of the belt layer (when the belt protection layer has a cord, it refers to the cord of the belt protection layer). When there are multiple grooves, it refers to the groove with the largest thickness of this rubber.

[0052] 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.

[0053] A "widened groove" refers to a groove whose groove width on the inner side in the tire radial direction is larger than the groove width (opening width) at the tread surface.

[0054] "The total thickness T (mm) of the tread surface" is 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 including 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 grounding part that is closer to the tire equator among the grounding parts 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 successively by 72° in the circumferential direction and measuring at 5 positions.

[0055] "Let the thickness of the layer whose outer surface constitutes the tread surface be t1 (mm)" is the thickness of the rubber layer whose outer surface constitutes the tread measured along the normal line at the tire equator in the cross-section of the tire based on the plane including 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 grounding part that is closer to the tire equator among the grounding parts on both lateral sides in the tire width direction of the groove. In addition, t1 is the average value of the total thicknesses of the tread surface obtained by rotating the tire successively by 72° in the circumferential direction and measuring at 5 positions.

[0056] "The thickness B (mm) of the belt layer" is the thickness in the tire radial direction of each belt layer at the tire equator in the cross-section of the tire based on the plane including the tire rotation axis. When the belt layer does not exist at the above equator, it is the thickness in the tire radial direction of each layer at the position of the center of the tire of the belt layer that is closer to the tire equator at the center of the tire width direction of the belt layer.

[0057] "The weight G (kg) of the tire" means: the weight of the tire alone without including the rim. On the other hand, when there are components such as those composed of sponge and sealant or sensor components in the inner cavity of the tire, it is set to include the weight of these.

[0058] "The grounding part" means: the part of the tread of the tire that touches the ground when the tire is pressed against the ground, and the part of the tread that constitutes the above effective grounding area.

[0059] "The rubber component of the rubber composition" means: the component that contributes to crosslinking in the rubber composition, usually a component with a weight average molecular weight (Mw) of 10,000 or more.

[0060] "The glass transition temperature (Tg) of the rubber component" means: 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] "The styrene content" is by 1The values calculated by 1H-NMR measurement, for example, are applicable to rubber components having repeating units derived from styrene such as SBR (rubber containing styrene units).

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

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

[0064] "Weight-average molecular weight (Mw)" is 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) and can be obtained by conversion with standard polystyrene. For example, it is applicable to SBR, BR, plasticizers, etc.

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

[0066] "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 set as the particle size; when it is needle-shaped or rod-shaped, the short diameter is set as the particle size; in other cases, the equivalent circle diameter calculated from the electron microscope image is set 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] "Content of plasticizer" also includes the amount of plasticizer contained in the oil-extended rubber component in which the plasticizer is 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 is oil, the extended oil is included in the content of oil.

[0068] "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, the 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 the present 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 It shows a part of the cross-section when the tire is cut by a plane including the tire rotation axis. Figure 1 In this, 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, the dotted line CL represents the tire equator.

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

[0072] As Figure 1 shown, a belt layer 5 is provided on the inner side in the tire radial direction of the tread portion 1. A carcass 4 and an innerliner 7 are laminated below the belt layer 5. In addition, a belt layer 6 may also be present between the tread portion 1 and the belt layer 5. The bead portion 3 includes a bead core 14 and a bead filler 13 that extends outward in the tire radial direction from the core. The bead filler 13 tapers gradually toward the outer end in the tire radial direction. In the bead portion 3, a lapping portion 10 that abuts against the rim 8 when the rim 8 is installed 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 portion according to the present embodiment may be a tread portion composed of a single rubber layer, or may be a tread portion having: a layer (tread rubber layer) whose outer surface constitutes the tread surface, and one or more rubber layers (inner rubber layers) present between the tread rubber layer and the belt layer. Figure 1 In this, a tread rubber layer 11 and a base rubber layer 12 laminated on the outer side in the tire radial direction of the belt layer 5 are provided. The double arrow t1 is the thickness of the tread rubber layer 11, and the double arrow t2 is the thickness of the base rubber layer 12.

[0074] The thickness t1 of the tread rubber layer is not particularly limited, and is preferably 3.0 mm or more, more preferably 3.5 mm or more, and further preferably 4.0 mm or more. In addition, t1 is preferably 10.0 mm or less, more preferably 9.5 mm or less, further preferably 9.0 mm or less, and particularly preferably 8.5 mm or less.

[0075] The thickness t2 of the base rubber layer is not particularly limited, preferably 0.8 mm or more, more preferably 1.0 mm or more, further preferably 1.2 mm or more, and particularly preferably 1.4 mm or more. In addition, t2 is preferably 5.0 mm or less, more preferably 4.0 mm or less, and further preferably 3.0 mm or less.

[0076] The total thickness T ( Figure 1 wherein t1 + t2) of the tread portion is preferably 4.5 mm or more, more preferably 5.0 mm or more, further preferably 5.5 mm or more, further preferably 6.0 mm or more, and particularly preferably 6.5 mm or more. On the other hand, the upper limit value of T is not particularly limited, preferably 11.0 mm or less, more preferably 10.5 mm or less, further preferably 10.0 mm or less, and particularly preferably 9.5 mm or less.

[0077] The thickness B of the belt layer 5 is preferably 0.6 mm or more, more preferably 0.8 mm or more, and further preferably 0.9 mm or more. In addition, the thickness B of the belt layer 5 is preferably 1.5 mm or less, more preferably 1.2 mm or less, and further preferably 1.1 mm or less.

[0078] From the viewpoints of reducing rolling resistance and improving grip performance, t1 / B is preferably 8.0 or less, more preferably 7.5 or less, and further preferably 7.0 or less. In addition, t1 / B is preferably 2.0 or more, more preferably 2.5 or more, and further preferably 3.0 or more.

[0079] 《Tread Portion》 Figure 2 is a sectional view showing a cross-section of the tread portion of the tire passing through the tire rotation axis. Figure 2 In it, 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 2 In it, the midpoint of the tire width direction of the grounding portion 20 is represented by the symbol P. The straight line indicated by the symbol N passes through the point P and is a straight line (normal line) perpendicular to the tangent plane at this point P.

[0080] The tread portion according to the present embodiment has at least one or more circumferential grooves 15. The tread portion has a grounding portion 20 divided by the circumferential grooves 15 in the tire width direction.

[0081] The groove depth H of the deepest part of the circumferential groove 15 refers to: Figure 2 In it, the straight-line distance between the straight line 17 connecting the ends of the circumferential groove in the tread surface 16 and the extension line of the lowest part of the groove in the tire radial direction. 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 circumferential groove 15 having the deepest groove depth among the plurality of circumferential grooves 15 ( Figure 2The straight-line distance between the lowest part of the tire in the radial direction of the circumferential groove 15 on the left side.

[0082] From the viewpoint of wear resistance, the groove depth H at the deepest part in the circumferential direction is preferably 4.0 mm or more, more preferably 4.5 mm or more, further preferably 5.0 mm or more, and particularly preferably 5.5 mm or more. In addition, from the viewpoint of wet grip performance, the groove depth H at the deepest part of the circumferential groove is preferably 10.0 mm or less, more preferably 9.5 mm or less, further preferably 9.0 mm or less, and particularly preferably 8.5 mm or less.

[0083] The tread surface, as Figure 1 and Figure 2 shown, may also have 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 Figure 2 is formed such that the deepest part of the groove bottom of the circumferential groove 15 is located radially inside 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 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, like the circumferential groove 15 shown on the right side of

[0084] In this specification, the "rubber composition constituting the tread surface" means: when the tread surface is composed of two or more layers, the rubber composition constituting the running surface rubber layer.

[0085] From the viewpoint of improving the dispersibility of silica, the acetone extraction amount AE of the rubber composition constituting the tread surface is 16.0 mass% or more, preferably 16.5 mass% or more, more preferably 17.0 mass% or more. In addition, from the viewpoint of wear resistance, it is preferably 35.0 mass% or less, more preferably 33.0 mass% or less, further preferably 30.0 mass% or less.

[0086] From the viewpoints of low fuel consumption performance and wet grip performance, AE × H is 100.0 or more, preferably 102.0 or more, further preferably 104.0 or more, and particularly preferably 106.0 or more. In addition, from the viewpoint of wear resistance, AE × H is preferably 200.0 or less, more preferably 180.0 or less, further preferably 160.0 or less, and particularly preferably 140.0 or less.

[0087] From the viewpoint of wet grip performance, the 30°C tanδ of the rubber composition constituting the tread surface is preferably 0.12 or more, more preferably 0.15 or more, still more preferably 0.18 or more, and particularly preferably 0.20 or more. Further, from the viewpoint of suppressing heat generation of the rubber, it is preferably 0.34 or less, more preferably 0.30 or less, and still more preferably 0.26 or less.

[0088] From the viewpoint of wet grip performance, the 0°C tanδ of the rubber composition constituting the tread surface is preferably 0.30 or more, more preferably 0.35 or more, still more preferably 0.40 or more, and particularly preferably 0.45 or more. Further, from the viewpoint of low fuel consumption performance, it is preferably 0.70 or less, more preferably 0.65 or less, and still more preferably 0.60 or less.

[0089] From the viewpoint of wet grip performance, 30°C tanδ × T is preferably 0.5 or more, more preferably 0.8 or more, and still more preferably 1.0 or more. The upper limit value of 30°C tanδ × T is not particularly limited, and is preferably 5.0 or less, more preferably 4.0 or less, and still more preferably 3.0 or less.

[0090] 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 -45°C, more preferably greater than -42°C, and still more preferably greater than -40°C. Further, from the viewpoint of the balance between low fuel consumption performance and wet grip performance, it is preferably less than -20°C, more preferably less than -25°C, and still more preferably less than -30°C.

[0091] In addition, various physical properties such as 30°C tanδ and 0°C tanδ of the rubber composition can be appropriately adjusted by the types and compounding amounts of the following rubber components, fillers, plasticizers, etc. For example, 30°C tanδ can be adjusted according to the type of resin component.

[0092] 《Tread Pattern》 Figure 3 Shows the tread pattern of the tire according to one embodiment of the present invention, 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 (central circumferential groove) extends in a zigzag shape, it is not limited to such a manner, and the central circumferential groove may also be linear. In addition, although a pair of circumferential grooves (a pair of outermost circumferential grooves) on both sides thereof extend linearly, it is not limited to such a manner, and the outermost circumferential groove may also be zigzag. Through these circumferential grooves, a pair of central contact portions 21 and a pair of shoulder contact portions 22 are defined. In the central contact portion 21, a transverse groove 31 that extends radially inward of the tire is arranged, and in the shoulder contact portion 22, a transverse groove 32 that extends radially inward of the tire is arranged. The transverse groove 31 is a widened groove having 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 ends, but it is not limited to such a manner, and at least one side of both ends thereof may 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 contact 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 contact end Te is preferred.

[0093] The tread portion of the tire according to the present embodiment preferably has two or more contact portions divided by one or more circumferential grooves, and preferably at least one of the contact portions 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.

[0094] 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.

[0095] 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.

[0096] Figure 4In this case, the groove walls 42 on both sides of the transverse groove 31 serving as the groove for widening are recessed from the groove edge 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 with respect 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.

[0097] The groove bottom wall thickness of the tread portion 1 is preferably 1.0 to 4.0 mm, more preferably 1.5 to 4.0 mm, and further preferably 2.0 to 3.5 mm. It is considered that by setting the groove bottom wall thickness within the above range, heat generation can be suppressed, which helps to improve the low fuel consumption performance.

[0098] 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 0.90 or less, more preferably 0.85 or less, and further preferably 0.80 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.

[0099] Figure 3 In this case, the central circumferential groove exists in the central region of the tread surface, 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.

[0100] The tread portion of the tire according to the present embodiment is preferably configured 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, the shoulder regions also have circumferential grooves. When the shoulder regions have circumferential grooves, the groove depth at the deepest part of the circumferential grooves is preferably 4.0 mm or more, more preferably 4.5 mm or more, further preferably 5.0 mm or more, and particularly preferably 5.5 mm or more. It is considered that by the above configuration, drainage performance can be improved, which helps to improve wet grip performance.

[0101] The circumferential groove present in the shoulder region means: among the circumferential grooves present on the tread surface, the circumferential groove outside the circumferential groove 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 at the same time, 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 a circumferential groove is present in the shoulder region, it refers to the groove depth of this circumferential groove, which is different from the groove depth H (mm) of the deepest part of the circumferential groove that refers to the groove depth of the circumferential groove with the deepest groove depth among all circumferential grooves.

[0102] The weight G of the tire according to this embodiment is preferably 8.0 kg or more, more preferably 8.5 kg or more, further preferably 9.0 kg or more, and particularly preferably 9.5 kg or more. There is no particular limitation on the upper limit value of the tire weight G, and it is usually 100 kg or less. For example, it can be set to 80 kg or less, 60 kg or less, 40 kg or less, 20 kg or less, 15 kg or less, etc.

[0103] [Rubber composition] The rubber composition constituting the tread surface of the tire according to this embodiment (hereinafter referred to as the rubber composition according to this embodiment) is a composition containing: a rubber component containing an isoprene-based rubber and a styrene-butadiene rubber, silica, and a dicyclopentadiene-based resin, and can be manufactured using any of the raw materials described below. The rubber composition according to this embodiment will be described below.

[0104] [Rubber component] In the rubber composition according to this embodiment, a diene-based rubber is preferably used as the rubber component. As the diene-based rubber, for example, isoprene-based rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), etc. can be cited. These diene-based rubbers can be modified rubbers treated with a modifying group that can interact with fillers such as carbon black and silica, or hydrogenated rubbers obtained by hydrogenating a part of the unsaturated bonds. The diene-based rubber can be used alone or in combination of two or more. In addition, as the diene-based rubber, an oil-extended rubber pre-increased with the following plasticizer can also be used.

[0105] The content of the diene-based rubber in the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and particularly preferably 95% by mass or more. In addition, it can also be set to a rubber component composed only of a diene-based rubber.

[0106] The rubber component involved in this embodiment is a rubber containing isoprene rubber and styrene-butadiene rubber, preferably a rubber containing isoprene rubber, styrene-butadiene rubber and butadiene rubber. In addition, the rubber component involved in this embodiment can also be a rubber component composed only of isoprene rubber and styrene-butadiene rubber, or a rubber component composed only of isoprene rubber, styrene-butadiene rubber and butadiene rubber.

[0107] (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. In natural rubber, 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 two or more of them can be used in combination.

[0108] There is no particular limitation on NR, and substances commonly used in the tire industry can be used. For example, SIR20, RSS#3, TSR20, etc. can be cited.

[0109] From the viewpoint of the effects of the present invention, the content of isoprene rubber in the rubber component is 40% by mass or more, preferably more than 40% by mass, more preferably 45% by mass or more, and further preferably 50% by mass or more. In addition, the content of isoprene rubber is preferably 90% by mass or less, more preferably 80% by mass or less, further preferably 75% by mass or less, and particularly preferably 70% by mass or less.

[0110] (SBR) There is no particular limitation on SBR, and solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), modified SBRs of these (modified S-SBR, modified E-SBR), etc. can be cited. As the modified SBR, SBR modified with a compound (modifying agent) having the following functional groups at the terminal and / or main chain; modified SBR coupled with tin, silicon compounds, etc. (condensates, substances having a branched structure, etc.) can be cited. Further, hydrides of these SBRs (hydrogenated SBRs) can also be used. These SBRs can be used alone, or two or more of them can be used in combination.

[0111] As the functional groups of the above-mentioned modifier, functional groups containing at least one element selected from silicon, nitrogen, and oxygen are preferred. As such functional groups, for example, amino group, amide group, silyl group, alkoxysilyl group, isocyanate group, imino group, imidazole group, ureido 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.

[0112] 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.

[0113] From the viewpoint of the effects of the present invention, the styrene content S1 of the SBR is 30% by mass or less, preferably 28% by mass or less, more preferably 25% by mass or less, and further preferably 22% by mass or less. In addition, from the viewpoint of the 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.

[0114] From the viewpoint of ensuring the reactivity with silica and the abrasion resistance, the vinyl content of the SBR is preferably 5 mol% or more, more preferably 10 mol% or more, and further preferably 15 mol% or more. In addition, from the viewpoint of the elongation at break and the abrasion resistance, the vinyl content of the SBR is preferably 45 mol% or less, more preferably 40 mol% or less, and further preferably 35 mol% or less. In addition, in the present specification, the vinyl content of the SBR is measured by the above-mentioned measurement method.

[0115] From the viewpoint of the effects of the present invention, S1×R is preferably 11.0 or more, more preferably 12.0 or more, further preferably 13.0 or more, and particularly preferably 14.0 or more. In addition, S1×R is preferably 20.0 or less, more preferably 18.0 or less, and further preferably 17.0 or less.

[0116] From the viewpoint of the effects of the present invention, S1 / G is preferably 1.2 or more, more preferably 1.5 or more, and further preferably 1.8 or more. In addition, S1 / G is preferably 4.0 or less, more preferably 3.5 or less, further preferably 3.0 or less, and particularly preferably 2.5 or less.

[0117] 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, and particularly preferably -55°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.

[0118] From the viewpoint of the effects of the present invention, the weight average molecular weight (Mw) of SBR is preferably 100,000 or more, more preferably 200,000 or more, and further preferably 300,000 or more. In addition, from the viewpoint of crosslinking uniformity, the weight average molecular weight is preferably 2,000,000 or less, more preferably 1,800,000 or less, and further preferably 1,500,000 or less. In addition, the weight average molecular weight of SBR is measured by the above-mentioned measurement method.

[0119] From the viewpoint of the effects of the present invention, the content of SBR in the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 25% by mass or more, further preferably 30% by mass or more, and particularly preferably 35% by mass or more. In addition, the content of SBR in the rubber component is preferably 60% by mass or less, more preferably 55% by mass or less, further preferably 50% by mass or less, and particularly preferably 45% by mass or less.

[0120] (BR) As BR, there is no particular limitation. 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 rare earth element series catalysts (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.

[0121] As high cis BR, for example, commercially available products from Zeon Corporation, UBE Corporation, JSR Corporation, etc. in Japan can be used. By containing high cis BR, the low temperature characteristics and abrasion resistance performance can be improved. The cis content of high cis BR is preferably more than 95 mol%, more preferably more than 96 mol%, and further preferably more than 97 mol%. In addition, the cis content of BR is measured by the above-mentioned measurement method.

[0122] As a rare earth series BR, it is synthesized using a rare earth element series catalyst. The vinyl content is preferably less than 1.8 mol%, more preferably less than 1.6 mol%, and further preferably 1.5 mol% or less. The cis content is preferably greater than 95 mol%, more preferably greater than 96 mol%, and further preferably 97 mol% or more. As the rare earth series BR, for example, commercially available substances such as those from Lanxess Corporation can be used.

[0123] Examples of BR containing SPB include substances in which 1,2-syndiotactic polybutadiene crystals are not simply dispersed in BR but are dispersed as crystals by chemical bonding with BR. As such BR containing SPB, commercially available substances such as those from UBE Corporation can be used.

[0124] As 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) in which the terminal and / or main chain is modified with a functional group containing at least one element selected from silicon, nitrogen, and oxygen can also be preferably used.

[0125] As other modified BR, there can be mentioned modified BR (tin-modified BR) obtained by polymerizing 1,3-butadiene using a lithium initiator and then adding a tin compound, and further, the terminal of the modified BR molecule is bonded by a tin-carbon bond. In addition, the modified BR can be an unhydrogenated modified BR or any one of hydrogenated modified BRs.

[0126] From the viewpoint of abrasion resistance performance, 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, etc., 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.

[0127] 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, and particularly preferably 15% by mass or more. In addition, the content of BR in the rubber component is preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, and particularly preferably 25% by mass or less.

[0128] 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.

[0129] (Other rubber components) Within the range that does not affect the effects of the present invention, the rubber component may further contain a rubber component other than the diene-based rubber (non-diene-based rubber). As the non-diene-based rubber, rubber components commonly used in the tire industry can be used. For example, butyl rubber, ethylene-propylene rubber, poly(norbornene) rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), chlorinated ether rubber, etc. can be cited. These non-diene-based rubbers can be used alone or in combination of two or more. In addition, a known thermoplastic elastomer may or may not be contained in addition to the above rubber components.

[0130] (Rubber component synthesized from recycled / biomass-derived raw materials) The monomers that are the constituent units of synthetic rubbers such as IR, BR, and SBR 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 recycling (recycled monomers), there is no particular limitation, and examples include recycled polyisoprene, recycled butadiene, recycled aromatic vinyl compounds, etc. As the above butadiene, 1,2-butadiene and 1,3-butadiene can be cited. As the above aromatic vinyl compound, there is no particular limitation, and examples include styrene, etc. Among them, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and recycled styrene (recycled styrene) as raw materials.

[0131] As the production method of the recycled monomer, there is no particular limitation. For example, it can be synthesized from recycled naphtha obtained by cracking rubber products such as tires. In addition, as the production method of the recycled 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.

[0132] Furthermore, the monomers that are the constituent units of polymers such as IR, BR, and SBR can also be biomass-derived substances. In this specification, biomass refers to substances derived from natural resources such as plants. As the biomass, there is no particular limitation. For example, it can be cited from agricultural, forestry, and fishery products or sugars, wood chips, plant residues after obtaining useful components, ethanol of plants, biomass naphtha, etc.

[0133] As the biomass-derived monomer (biomass monomer), there is no particular limitation, and examples thereof include biomass-derived butadiene, biomass-derived 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 styrene, etc. can be cited. In addition, the method for producing the biomass-derived monomer 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 biological conversion, fermentation based on microorganisms is representative. As chemical and / or physical conversion, conversion based on a catalyst, conversion based on high heat, conversion based on high pressure, conversion based on electromagnetic waves, conversion based on supercritical fluid, and combinations thereof can be cited.

[0134] As the polymer synthesized from the biomass monomer component (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 cited.

[0135] 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.

[0136] pMC means: the 14 C concentration of the sample relative to that of the modern standard reference 14 The ratio of the C concentration is a value used as an index indicating the biomass ratio of the compound. The meaning of this value will be described below.

[0137] 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 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, fossil fuels such as coal, oil, and natural gas do not contain any14 Element C

[0138] On the other hand, 14 C is continuously generated through nuclear reactions of cosmic rays in the atmosphere. Therefore, 14 the decrease of C due to radioactive decay and the generation based on nuclear reactions reach equilibrium. In the atmospheric environment of the earth, 14 the amount of C is a constant. Therefore, in the current environment, the 14 C concentration of the substances in biomass resources derived from the material cycle is, as described above, about 1×10 -12 mol% with respect to all carbon atoms. Therefore, using the difference between these values, the biomass ratio in a certain compound can be calculated.

[0139] Generally, this 14 C is measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, the 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 C) are measured. During the measurement, as the standard modern carbon for the concentration reference of 14 C, the 14 C concentration in the circulating carbon in nature in 1950 is adopted. As a specific standard substance, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific radioactivity of carbon in this oxalic acid (the radioactive intensity of 14 C per 1 g of carbon) is classified according to each carbon isotope, and 13 C is corrected to a fixed value, and the value after applying the decay correction from 1950 AD to the measurement date is used 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.

[0140] 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 the above-mentioned biomass ratio of 0%.

[0141] In summary, it is preferable in terms of environmental protection 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.

[0142] [filler] The rubber composition according to the present embodiment contains silica as a filler, and more preferably contains silica and carbon black. Alternatively, the filler may be a filler consisting only of carbon black and silica.

[0143] <Silicon Dioxide> 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.

[0144] 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.

[0145] 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.

[0146] If silicon dioxide is crystallized, it will not dissolve in water, and its component silicic acid 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.).

[0147] Amorphous silica extracted from rice husks and commercially available products such as Wilmar can be used.

[0148] 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 170 m 2 / g. Further, from the viewpoints of heat generation property and processability, it is preferably less than 220 m 2 / g, more preferably less than 200 m 2 / g, still more preferably less than 180 m 2 / g. In addition, the N2SA of silica is measured by the above-described measurement method.

[0149] From the viewpoint of the effects of the present invention, the average primary particle diameter of silica is preferably greater than 10 nm, more preferably greater than 12 nm, still more preferably greater than 14 nm. Further, the average primary particle diameter is preferably less than 20 nm, more preferably less than 18 nm, still more preferably less than 17 nm. In addition, the average primary particle diameter of silica is measured by the above-described measurement method.

[0150] 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 30 parts by mass or more, preferably greater than 30 parts by mass, more preferably 35 parts by mass or more, still more preferably 40 parts by mass or more, particularly preferably 45 parts by mass or more. Further, from the viewpoint of compatibility with the isoprene-based rubber, the content is preferably 120 parts by mass or less, more preferably 110 parts by mass or less, still more preferably 100 parts by mass or less, particularly preferably 90 parts by mass or less.

[0151] From the viewpoint of the effects of the present invention, the content of silica in the filler is preferably 55% by mass or more, more preferably 65% by mass or more, still more preferably 75% by mass or more, particularly preferably 80% by mass or more. Further, from the viewpoint of abrasion resistance, it is preferably 95% by mass or less, more preferably 92% by mass or less, still more preferably 90% by mass or less.

[0152] <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 production 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. may be used. These carbon blacks may be used alone or in combination of two or more.

[0153] In addition, as carbon black, in addition to the above, from the perspective of life cycle assessment, etc., recycled carbon black obtained by pyrolyzing and refining carbon black made from biomass materials such as lignin and products containing carbon black such as tires can also be used.

[0154] In this specification, "recycled carbon black" refers to carbon black obtained by pulverizing used products such as tires containing carbon black and firing the pulverized material. Using the thermogravimetric method based on JIS K 6226-2:2003, when it is oxidized and burned by heating in air, the proportion of the mass (ash content) of the non-combustible component, i.e., ash, is 13% by mass or more. That is, the proportion of the mass (carbon content) of the reduced part based on the above oxidation combustion of recycled carbon black is 87% by mass or less. Recycled carbon black is sometimes also represented by rCB.

[0155] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975 records that "Rubber Chemistry and Technology", Vol. 85, No. 3, pages 408-449 (2012), especially pages 438, 440, and 442 mention that by removing oxygen and then pyrolyzing organic materials at 550-800 °C, or by vacuum pyrolysis at a relatively low temperature (

[0027] ). The carbon black obtained by such a pyrolysis process is usually recycled carbon black lacking functional groups on its surface as mentioned in

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

[0156] Recycled carbon black can be carbon black lacking functional groups on its surface, or it can also be carbon black that has been treated to make its surface contain functional groups. The treatment to make the surface of the recovered carbon black contain functional groups can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained from the pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl groups and / or carboxyl groups on its surface. In addition, in Patent No. 6856781, carbon black obtained from the pyrolysis process is treated with an amino acid compound containing at least one mercapto group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black involved in this embodiment includes these carbon blacks treated to make their surfaces contain functional groups.

[0157] Recycled carbon black can use commercially available substances such as those from Strable Green Carbon and LDCarbon.

[0158] From the viewpoint of reinforcement, the nitrogen adsorption specific surface area (N2SA) of carbon black is preferably greater than 70 m 2 / g, more preferably greater than 100 m 2 / g, further preferably greater than 120 m 2 / g, particularly preferably greater than 140 m 2 / g. In addition, 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, further preferably less than 190 m 2 / g. In addition, the N2SA of carbon black is measured by the above-mentioned measurement method.

[0159] The average primary particle size of carbon black is preferably less than 32 nm, more preferably less than 28 nm, further preferably less than 24 nm, further preferably less than 20 nm, and particularly preferably less than 18 nm. In addition, the average primary particle size is preferably greater than 8 nm, more preferably greater than 10 nm, further preferably greater than 12 nm, and particularly preferably greater than 14 nm. In addition, the average primary particle size of carbon black is measured by the above-mentioned measurement method.

[0160] From the viewpoint of abrasion resistance, the content of carbon black relative to 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, and further preferably 10 parts by mass or more. In addition, the content is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and further preferably 40 parts by mass or less.

[0161] <Other fillers> The filler may further contain other fillers other than silica and carbon black. There is no particular limitation on other fillers. For example, substances commonly used in the tire industry such as aluminum hydroxide, calcium carbonate, alumina, clay, and talc can be compounded.

[0162] The total content of the filler relative to 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably 45 parts by mass or more, further preferably 50 parts by mass or more, and particularly preferably 55 parts by mass or more. In addition, the content is preferably 140 parts by mass or less, more preferably 120 parts by mass or less, further preferably 100 parts by mass or less, and particularly preferably 90 parts by mass or less.

[0163] <Silane coupling agent> Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited. For example, sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide 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; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, etc. Among them, sulfide-based 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, Momentive, etc. can be used. These silane coupling agents can be used alone or in combination of two or more.

[0164] 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 a decrease in 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.

[0165] [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, anti-aging agents, stearic acid, zinc oxide, vulcanizing agents, vulcanization accelerators, etc.

[0166] [Plasticizer] A plasticizer refers to a material that imparts plasticity to rubber components, and it is a concept that includes both plasticizers that are liquid at 25°C and plasticizers that are solid at normal temperature (25°C). As examples of plasticizers, resin components, oils, liquid rubbers, ester-based plasticizers, etc. can be cited. These plasticizers can be substances derived from mineral resources such as petroleum and natural gas, substances derived from biomass, or substances sourced from naphtha recovered from rubber products and non-rubber products. 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 individually or in combination of two or more.

[0167] (Resin component) The rubber composition according to this embodiment contains a dicyclopentadiene-based resin as a resin component, and other resin components can also be used in combination. The dicyclopentadiene-based resin is preferably a resin containing dicyclopentadiene, styrene, and indene as monomer components.

[0168] 《Dicyclopentadiene-based resin》 "Dicyclopentadiene-based resin" refers to a resin that contains cyclopentadiene (CPD) or dicyclopentadiene (DCPD) as monomer components, and it can also be their hydrogenated products or modified products. As examples of 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 can 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 Corporation, ENEOS Corporation, Zeon Corporation, Maruzen Petrochemical Co., Ltd., etc. can be used. These dicyclopentadiene-based resins can be used individually or in combination of two or more.

[0169] As other resin components, there is no particular limitation, and resin components commonly used in the tire industry can be used. For example, adhesive resins such as aromatic vinyl-based resins, C9-based resins, C5-based resins, C5C9-based resins, coumarone-based resins, indene-based resins, terpene-based resins, rosin-based resins, and phenolic-based resins can be cited. These resin components can be used individually or in combination of two or more.

[0170] 《Aromatic vinyl-based resin》 "Aromatic vinyl resin" refers to a resin containing styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene and other aromatic vinyl compounds as the monomer component with the highest content, and can also be their hydrogenated products or modified products. As the aromatic vinyl resin, 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 the aromatic vinyl resin, for example, commercially available substances from companies such as Kraton Corporation, Eastman Chemical Company, and Mitsui Chemicals, Inc. can be used. These aromatic vinyl resins can be used alone or in combination of two or more.

[0171] 《C9 Resin》 "C9 resin" refers to a resin obtained by polymerizing C9 fraction, which can 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 can also be their hydrogenated products or modified products. As C9 fraction, for example, petroleum fractions with 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene can be listed. These C9 resins can be used alone or in combination of two or more.

[0172] 《C5 Resin》 "C5 resin" refers to a resin obtained by polymerizing C5 fraction, and can also be their hydrogenated products or modified products. As C5 fraction, for example, petroleum fractions with 4 to 5 carbon atoms such as cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, and pentadiene can be listed. These C5 resins can be used alone or in combination of two or more.

[0173] 《C5C9 Resin》 "C5C9 resin" refers to a resin obtained by copolymerizing the above C5 fraction with the above C9 fraction, and can also be their hydrogenated products or modified products. As C5C9 petroleum resin, for example, commercially available substances from companies such as Tosoh Corporation and LUHUA Corporation can be used. These C5C9 resins can be used alone or in combination of two or more.

[0174] 《Coumarone 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 resins, for example, coumarone / indene resins containing coumarone and indene as monomer components, coumarone / indene / styrene resins 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.

[0175] "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 resins, for example, coumarone / indene resins containing coumarone and indene as monomer components, coumarone / indene / styrene resins 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.

[0176] "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, which may also be its hydrogenated product or modified product. As specific examples of terpene resins, for example, polyterpene resins containing only one or more of the above terpene compounds as monomer components can be cited; aromatic modified terpene resins containing the above terpene compounds and aromatic compounds as monomer components; terpene phenolic resins containing the above terpene compounds and phenolic compounds as monomer components, etc. As the monomer component of the aromatic modified terpene resin, that is, the aromatic compound, for example, styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. can be cited. As the monomer component of the terpene phenolic resin, that is, the phenolic compound, for example, phenol, bisphenol A, cresol, xylenol, etc. can be cited. These terpene resins can be used alone, or two or more of them can be used in combination.

[0177] "Rosin Resin" "Rosin resin" refers to: a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc., which may also be its hydrogenated product or modified product. As rosin resins, there is no particular limitation. For example, natural resin rosin, rosin modified resins obtained by modifying it through hydrogenation, disproportionation, dimerization, esterification, etc. can be cited. These rosin resins can be used alone, or two or more of them can be used in combination.

[0178] "Phenolic Resin" "Phenolic resin" means: a resin containing phenolic compounds such as phenol and cresol as the monomer component with the largest content. As the 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.

[0179] "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 processability and improving 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.

[0180] "Content" The total content of the resin component 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, further preferably 15 parts by mass or more, further 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 further preferably 45 parts by mass or less.

[0181] 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, further preferably 15 parts by mass or more, further 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 further preferably 45 parts by mass or less.

[0182] "(Oil)" As the oil, for example, mineral oil, vegetable oil, animal oil, etc. can be cited. In addition, from the viewpoint of life cycle assessment, 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.

[0183] In this specification, mineral oil refers to oils derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffin-based oils (mineral oil), naphthenic oils, and aromatic oils. Specific examples of mineral oil include, for example, MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). In addition, due to environmental measures, oils with a low content of polycyclic aromatic compounds (PCA) can also be used. Examples of such oils with a low PCA content include MES, TDAE, and heavy naphthenic oils.

[0184] In this specification, "vegetable oil" 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, wood wax, etc. Further, as vegetable oils, 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 edible oils obtained by recovering the oils used as edible oils, etc. can also be listed. In addition, vegetable oils can be liquid or solid at room temperature (25°C). These vegetable oils can be used alone or in combination of two or more.

[0185] The vegetable oil involved in 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. There is no particular limitation on acylglycerol, and it can be any one of 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, and triacylglycerol. Further, acylglycerol can be a monomer, a dimer, or a polymer of trimer or higher. In addition, acylglycerol of dimer or higher can be obtained by thermal polymerization, oxidative polymerization, etc. In addition, acylglycerol can be liquid or solid at room temperature (25°C).

[0186] As a method for confirming the presence of acylglycerol in the rubber composition, there is no particular limitation. For example, it can be confirmed by the following 1 1H-NMR measurement. Specifically, the rubber composition compounded with triacylglycerol is immersed in deuterated chloroform at room 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 from the hydrogen atoms bonded to the carbon atoms adjacent to the oxygen atom of the ester group, and the presence of acylglycerol can be confirmed. In addition, "around" here refers to the range of ±0.10 ppm.

[0187] As the above fatty acid, there is no particular limitation. It can be an unsaturated fatty acid or a saturated fatty acid. As the unsaturated fatty acid, monounsaturated fatty acids such as oleic acid or polyunsaturated fatty acids such as linoleic acid and linolenic acid can be cited. In addition, as the saturated fatty acid, butyric acid, lauric acid, etc. can be cited.

[0188] Among them, as the above fatty acid, a fatty acid with fewer double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, is preferably oleic acid. As such a vegetable oil containing fatty acids, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid can be used, or a vegetable oil modified by transesterification or the like can also be used. In addition, in order to produce such a vegetable oil containing fatty acids, plants can also be improved by variety improvement, genetic modification, etc.

[0189] As the vegetable oil, for example, substances commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Company, H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0190] As the animal oil, fish oil, beef tallow, or an oil alcohol derived therefrom, etc. can be cited.

[0191] When oil is contained, from the viewpoint of the effects of the present invention, its content relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and further preferably 7 parts by mass or more. In addition, this content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 30 parts by mass or less.

[0192] (Liquid rubber) The liquid rubber is not particularly limited as long as it is a polymer in a liquid state at normal temperature (25°C). For example, liquid butadiene rubber (liquid BR), liquid styrene-butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene-isoprene rubber (liquid SIR), liquid farnesene rubber, etc. can be cited. These liquid rubbers can be used alone, or two or more of them can be used in combination.

[0193] (Ester plasticizer) As the ester plasticizer, 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 plasticizer can be used alone, or two or more of them can be used in combination.

[0194] From the viewpoint of wet grip performance, the content of the plasticizer relative to 100 parts by mass of the rubber component (when using multiple plasticizers, it is the total amount of all) is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, further preferably 30 parts by mass or more, and particularly preferably 35 parts by mass or more. In addition, from the viewpoint of processability, it is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, further preferably 80 parts by mass or less, and particularly preferably 70 parts by mass or less.

[0195] (Vulcanized rubber particles) The 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 two or more of them can be used in combination.

[0196] As the vulcanized rubber particles, there is no particular limitation, and they can be non-modified vulcanized rubber particles or modified vulcanized rubber particles. As commercially available products of vulcanized rubber, for example, products of Lehigh Company, Murakami Rubber Industry Co., Ltd., etc. can be used.

[0197] When containing vulcanized rubber particles, its content relative to 100 parts by mass of the rubber component can be appropriately adjusted within the range of, for example, more than 1 part by mass and less than 80 parts by mass.

[0198] (Processing aid) As a processing aid, 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. As a processing aid, for example, substances commercially available from companies such as Schill + Seilacher and Performance-Additives can be used. These processing aids can be used alone or in combination of two or more.

[0199] 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 further 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 further preferably less than 5.0 parts by mass.

[0200] (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 free of stearic acid. The wax can be, for example, a substance commercially available 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.

[0201] 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 further 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 further preferably less than 5.0 parts by mass.

[0202] (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'-dimethylxylphenyl-p-phenylenediamine (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-, tris-, and polyphenol-based anti-aging agents such as tetrakis[methylene-3-(3,5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. 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., Ltd., etc. can be used. These anti-aging agents can be used alone in one kind or in combination of two or more kinds.

[0203] 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 a plurality of 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.

[0204] (Stearic acid) When containing stearic acid, from the viewpoint of processability, 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 1.0 part by mass, and further preferably greater than 1.5 part 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 further preferably less than 5.0 parts by mass.

[0205] (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, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and still more preferably less than 5.0 parts by mass.

[0206] (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.

[0207] When sulfur is contained as the vulcanizing agent, from the viewpoint of ensuring sufficient vulcanization reaction, its content relative to 100 parts by mass of the rubber component is preferably more than 0.1 part by mass, more preferably more than 0.5 part by mass, and still more preferably more than 1.0 part by mass. 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 still more 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 to the total content of the pure sulfur component contained in the sulfur containing oil.

[0208] As the 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 crosslinking chain other than a polysulfide bond, there is no particular limitation. For example, alkylphenol / sulfur chloride condensate, 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.

[0209] (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 viewpoint of better obtaining the desired effect, it is preferably one or more vulcanization accelerators selected from sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, and guanidine-based vulcanization accelerators.

[0210] As sulfenamide vulcanization accelerators, for example, N-tert-butyl-2-benzothiazolesulfenamide (TBBS), N-cyclohexyl-2-benzothiazolesulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolesulfenamide (DCBS), etc. can be cited.

[0211] As thiazole vulcanization accelerators, for example, 2-mercaptobenzothiazole (MBT) or its salts, bis(2-benzothiazolyl) disulfide (MBTS), 2-(2,4-dinitrophenyl) mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio) benzothiazole, etc. can be cited.

[0212] As guanidine vulcanization accelerators, 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.

[0213] As thiuram vulcanization accelerators, for example, tetra(2-ethylhexyl) thiuram disulfide (TOT-N), tetramethyl thiuram disulfide (TMTD), tetraethyl thiuram disulfide, tetramethyl thiuram monosulfide (TMTM), bis(pentamethylene) thiuram disulfide, bis(pentamethylene) thiuram tetrasulfide, etc. can be cited.

[0214] As thiourea vulcanization accelerators, for example, thiocarbamide, thiourea compounds such as diethyl thiourea, dibutyl thiourea, trimethyl thiourea, di-o-tolyl thiourea, N,N'-diphenyl thiourea, trimethyl thiourea, N,N'-diethyl thiourea, etc. can be cited.

[0215] As dithiocarbamate vulcanization accelerators, for example, piperidinium pentamethylene dithiocarbamate (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.

[0216] 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.

[0217] 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.

[0218] [Manufacturing] The rubber composition according to this embodiment can be manufactured by a known method. For example, it can be manufactured by kneading the above-mentioned respective components using a rubber kneading device such as an open roll mill, a closed kneader (Banbury mixer, kneader, etc.).

[0219] The kneading process, for example, includes the following basic kneading process: kneading compounding agents and additives other than the vulcanizing agent and the vulcanization accelerator, and a final kneading process (F kneading): adding the vulcanizing agent and the vulcanization accelerator to the kneaded product obtained in the basic kneading process and kneading. Further, the above-mentioned basic kneading process can also be decomposed into a plurality of processes as needed. When decomposing the basic kneading process, the method can be: (1) a method of pre-kneading a part of the compounding agent and the additive to make a master batch, and then adding the remaining compounding agent and additive to the obtained master batch 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 product one or more times. 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 one of the master batches.

[0220] 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.

[0221] The tire of the present embodiment having a tread portion composed of the rubber composition according to the present embodiment can be manufactured by a conventional method. That is, the tire can be manufactured by: compounding the above components as needed with respect to the rubber component, extruding the prepared unvulcanized rubber composition according to the shape of the tread portion, laminating the obtained tread portion together with other tire components on a tire building machine by a conventional method, forming an unvulcanized tire by molding, and heating and pressurizing the obtained unvulcanized tire in a vulcanizer. As the vulcanization conditions, there are no particular limitations, and for example, a method of vulcanizing at 150 to 200 °C for 10 to 30 minutes can be cited.

[0222] [Use] The tire according to the present embodiment can be used for any purpose of pneumatic tires and non-pneumatic tires, 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 means a tire with a maximum load capacity of less than 1400 kg on the premise of being installed on a four-wheel-driving vehicle. In addition, a heavy-duty tire means a tire with a maximum load capacity of 1400 kg or more. In addition, the tire of the present embodiment can be used for winter tires such as studless tires in addition to all-season tires and summer tires.

Examples

[0223] The following shows examples (Examples) considered to be preferable in implementation, but the scope of the present invention is not limited to the Examples. Using the 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.

[0224] The following summarizes and shows the various drugs used in the Examples and Comparative Examples. NR: TSR20 SBR1: SBR (S-SBR, Tg: -60 °C, styrene content: 20% by mass, vinyl content: 20 mol%, Mw: 700,000, non-oil-extended) manufactured by the following Production Example 1 SBR2: TUFDENE 3830 manufactured by Asahi Kasei Corporation (unmodified S-SBR, Tg: -35 °C, styrene content: 36% by mass, vinyl content: 31 mol%, Mw: 420,000, containing 37.5 parts by mass of oil-extended oil with respect to 100 parts by mass of rubber solid components) BR: UBEPOL BR (registered trademark) 150B manufactured by UBE Industries, Ltd. (unmodified BR, cis content: 97%, Mw: 440,000) Carbon black: Prototype carbon black (N2SA: 180m 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: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa GmbH Resin component 1: Oppera PR395 (hydrogenated DCPD / C9 resin, a resin containing dicyclopentadiene, styrene, and indene as monomer components, softening point: 118 °C) manufactured by ExxonMobil Corporation Resin component 2: SYLVATRAXX 4401 (α-methylstyrene resin, softening point: 85 °C) manufactured by Kraton Corporation Oil: VivaTec 500 (TDAE oil) manufactured by H&R Corporation Wax: OZOACE 0355 (paraffin wax) manufactured by Nippon Seiro Co., Ltd. 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 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-benzothiazole sulfenamide (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.

[0225] (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 and 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 7 million by GPC, 4 L of ethanol was injected into the polymerization solution to recover the precipitate. The obtained precipitate was air-dried and then dried under reduced pressure at 80 °C / 10 Pa or less until the loss on drying was 0.1% to obtain SBR1.

[0226] (Examples and Comparative Examples) According to the compounding recipe shown in Table 1 or Table 2, using a 1.7 L 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 roll mill, sulfur and vulcanization accelerators were added to the obtained kneaded product, and kneaded for 4 minutes until it reached 105 °C, and kneaded to obtain an unvulcanized rubber composition. Using the obtained unvulcanized rubber composition, it was formed 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). In addition, the thickness t2 of the base rubber layer was 1.5 mm. The thickness t1 of the tread rubber layer was calculated by (total thickness T of the tread portion in the table) - (thickness t2 of the above base rubber layer). The thickness B of the belt layer was 1.0 mm, and the groove depth at the deepest part of the circumferential groove existing in the shoulder region was consistent with the "groove depth H (mm) at the deepest part of the circumferential groove" in the table. In addition, the transverse groove existing in the center region was a widened groove having a cross-sectional shape as shown in Figure 4 .

[0227] <Determination of Acetone Extract (AE)> For the rubber test pieces cut from the tread portion 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 by the following formula. Acetone extract (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

[0228] <Determination of tanδ at 30 °C and tanδ at 0 °C> For each rubber test piece cut from the tread portion of each test tire with the tire circumferential direction as the long side and the tire radial direction 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), the loss tangent tanδ was measured under the conditions of a temperature of 30 °C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and a tensile mode. In addition, 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.

[0229] <Determination of Glass Transition Temperature (Tg) of Rubber Composition> For each rubber test piece cut from the tread surface of each test tire with the tire circumferential direction as the long side and the tire radial direction 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 corresponding to the maximum tanδ value in the obtained temperature distribution curve (tanδ peak temperature) was determined as the Tg of the rubber composition.

[0230] <Low fuel consumption performance> Using a rolling resistance testing machine, the rolling resistance during driving of each test tire was measured under the conditions of a rim of 15×6JJ, an internal pressure of 230 kPa, a load of 4.24 kN, and a speed of 80 km / h, and the reciprocal thereof was expressed as an index with the tire of Comparative Example 2 set to 100. The larger the value, the smaller the rolling resistance, indicating more excellent low fuel consumption performance.

[0231] <Wet grip performance> Each test tire was respectively installed on the four wheels of an 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. The braking distance of the test tire of Comparative Example 2 was set to 100, and according to the following calculation formula, the wet grip performance of each tire was expressed as an index. The larger the index, the more excellent the wet grip performance. (Wet grip performance index) = (Braking distance of the tire of Comparative Example 2) / (Braking distance of each test tire) × 100

[0232] <Comprehensive performance> The sum of the above low fuel consumption performance and wet grip performance was expressed as a comprehensive performance index.

[0233]

Table 1

[0234]

Table 2

[0235] <Embodiment> An embodiment of the present invention is as shown below.

[0236] 〔1〕A tire, characterized in that it is a tire having a tread surface, the tread surface having one or more circumferential grooves, the tread surface being composed of a rubber composition containing a rubber component, silica, and a resin component, the rubber component containing an isoprene-based rubber and a styrene-butadiene rubber, the content of the isoprene-based rubber in the rubber component being 40% by mass or more, the styrene content S1 (% by mass) of the styrene-butadiene rubber being 30 or less, the content of silica being 30 parts by mass or more relative to 100 parts by mass of the rubber component, the resin component containing a dicyclopentadiene-based resin, the acetone extraction amount AE (% by mass) of the rubber composition being 16.0 or more, when the tanδ of the rubber composition at 30°C is designated as 30°C tanδ and the total thickness of the tread surface is designated as T (mm), 30°C tanδ × T is less than 3.0, and when the groove depth at the deepest part of the circumferential groove is designated as H (mm), AE × H is 100.0 or more. 〔2〕The tire according to the above-mentioned 〔1〕, wherein the content of silica is 60 parts by mass or more relative to 100 parts by mass of the rubber component. 〔3〕The tire according to the above-mentioned 〔1〕 or 〔2〕, wherein the rubber composition contains 1 part by mass or more and 10 parts by mass or less of carbon black relative to 100 parts by mass of the rubber component. 〔4〕The tire according to any one of the above-mentioned 〔1〕 to 〔3〕, wherein the 30°C tanδ of the rubber composition is 0.26 or less. 〔5〕The tire according to any one of the above-mentioned 〔1〕 to 〔4〕, wherein 30°C tanδ × T is 3.0 or less. 〔6〕The tire according to any one of the above-mentioned 〔1〕 to 〔5〕, wherein S1 is 25 or less. 〔7〕The tire according to any one of the above-mentioned 〔1〕 to 〔6〕, wherein the total styrene amount S2 (% by mass) in the rubber component is 15 or less. 〔8〕The tire according to any one of the above-mentioned 〔1〕 to 〔7〕, wherein the tanδ of the rubber composition at 0°C (0°C tanδ) is 0.45 or more. 〔9〕The tire according to any one of the above-mentioned 〔1〕 to 〔8〕, wherein when the contact area ratio of the tread surface is designated as R, S1 × R is 11.0 or more. 〔10〕The tire according to any one of the above-mentioned 〔1〕 to 〔9〕, wherein when the tire weight is designated as G (kg), S1 / G is 3.0 or less. 〔11〕The tire according to any one of the above-mentioned 〔1〕 to 〔10〕, wherein the dicyclopentadiene-based resin is a resin containing dicyclopentadiene, styrene, and indene as monomer components. 〔12〕The tire according to any one of the above-mentioned 〔1〕 to 〔11〕, wherein the tread surface has a grounding portion divided by the one or more circumferential grooves, the grounding portion has a transverse groove extending radially inward of the tire, and at least one of the transverse grooves has a groove width greater than the groove width at the tread surface in the radially inner side of the tire. 〔13〕The tire according to any one of the above-mentioned 〔1〕 to 〔12〕, wherein in the tread surface of the tread portion, when a region of 30% of the tread grounding 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 grounding 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. 〔14〕The tire according to any one of the above-mentioned 〔1〕 to 〔13〕, wherein in the tread portion, when the thickness of the layer whose outer surface constitutes the tread surface is set as t1 (mm) and the thickness of the belt layer is set as B (mm), B is 0.9 or more and 1.2 or less, and t1 / B is 7.0 or less. 〔15〕The tire according to any one of the above-mentioned 〔1〕 to 〔14〕, wherein the groove bottom wall thickness of the tread portion is 1.0 mm or more and 4.0 mm or less.

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, silica and a resin component. 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 styrene content S1 of the styrene butadiene rubber is less than 30, and the unit of S1 is mass %. The content of silica is 30 parts by mass or more relative to 100 parts by mass of the rubber component. The resin component contains a dicyclopentadiene resin, The rubber composition has an acetone extractable amount AE of 16.0 or more, where the unit of AE is mass %. When tanδ of the rubber composition at 30°C is 30°C tanδ and the total thickness of the tread portion is T, 30°C tanδ×T is less than 3.0, where the unit of T is mm, When the groove depth of the deepest part of the circumferential groove is defined as H, AE×H is equal to or greater than 100.0, where the unit of H is mm.

2. The tire according to claim 1, wherein: The content of silica is 60 parts by mass or more based on 100 parts by mass of the rubber component.

3. The tire according to claim 1 or 2, wherein: The rubber composition contains 1 part by mass or more and 10 parts by mass or less of carbon black relative to 100 parts by mass of the rubber component.

4. The tire according to claim 1 or 2, wherein: The rubber composition has a tan δ at 30° C. of 0.26 or less.

5. The tire according to claim 1 or 2, wherein: tanδ×T at 30°C is 3.0 or less.

6. The tire according to claim 1 or 2, wherein: S1 is 25 or less.

7. The tire according to claim 1 or 2, wherein: The total styrene amount S2 in the rubber component is 15 or less, and the unit of S2 is mass %.

8. The tire according to claim 1 or 2, wherein: The rubber composition has a tan δ at 0°C, ie, 0°C tan δ of 0.45 or more.

9. The tire according to claim 1 or 2, wherein: When the contact area ratio of the tread portion is defined as R, S1×R is equal to or greater than 11.

0.

10. 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.

11. The tire according to claim 1 or 2, wherein: The dicyclopentadiene-based resin is a resin containing dicyclopentadiene, styrene, and indene as monomer components.

12. The tire according to claim 1 or 2, wherein: The tread portion has a land portion divided by the one or more circumferential grooves, the land portion has lateral grooves extending radially inwardly of the tire, and at least one of the lateral grooves has a groove width radially inwardly of the tire that is greater than a groove width on the tread surface.

13. The tire according to claim 1 or 2, wherein: In the tread surface of the tread portion, an area of ​​30% of the tread contact width centered on the tire equator is set as a center area, and areas on both sides of the center area outside and within 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.

14. The tire according to claim 1 or 2, wherein: In the tread portion, when the thickness of the layer constituting the tread surface on the outer surface is t1 and the thickness of the belt layer is B, B is 0.9 or more and 1.2 or less, t1 / B is 7.0 or less, and the units of t1 and B are mm.

15. The tire according to claim 1 or 2, wherein: The groove bottom wall thickness of the tread portion is not less than 1.0 mm and not more than 4.0 mm.

16. The tire according to claim 1 or 2, wherein: The content of silica is 120 parts by mass or more based on 100 parts by mass of the rubber component.

17. The tire according to claim 1 or 2, wherein: The rubber composition has an acetone extract amount AE of 35.0 or less, where the unit of AE is mass %.

18. The tire according to claim 1 or 2, wherein: AE×H is less than 200.0.

Images