tire

Abstract

We provide tires that offer improved overall performance in terms of fuel efficiency, wet grip performance, and quietness. [Solution] A tire having a tread portion, wherein the tread portion has two or more ribs partitioned by one or more circumferential grooves, at least one of the ribs is provided with two or more lateral grooves, the length of the widthwise component of the two or more lateral grooves is 20% or more of the width of the rib, at least a portion of the circumferential component of adjacent lateral grooves overlaps, the tread portion is composed of a rubber composition containing a rubber component and a plasticizer, the rubber component contains one or more selected from the group consisting of styrene-butadiene rubber and isoprene-based rubber, the plasticizer contains a copolymer resin containing styrene and cyclopentadiene as monomer components, and when the groove depth of the deepest part of the two or more lateral grooves is H (mm) and the total amount of styrene in the rubber composition is S (mass%), the H / S ratio is less than 5.0.

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] In recent years, improvement of the wet grip performance of tires has been desired. For example, Patent Document 1 describes using a tire rubber composition containing a predetermined conjugated diene rubber and a conjugated diene polymer as rubber components, and further containing a predetermined silica and a predetermined tetrazine compound, thereby improving the wet grip performance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, performance other than wet grip performance is not considered. Tires are required to improve low - fuel - consumption performance by reducing rolling resistance. Also, when driving on rough roads in vehicles such as SUVs, interior noise is likely to occur due to sounds such as sand splashing, and quiet performance of the tire is also required.

[0005] An object of the present invention is to provide a tire in which the overall performance of low - fuel - consumption performance, wet grip performance, and quiet performance is improved.

Means for Solving the Problems

[0006] The present invention relates to the following tire. A tire having a tread portion, wherein the tread portion has two or more ribs partitioned by one or more circumferential grooves, At least one of the ribs is provided with two or more lateral grooves, The length of the width direction component of the two or more lateral grooves is 20% or more of the width of the rib, In the two or more lateral grooves, at least a part of the circumferential direction component of adjacent lateral grooves overlaps, The tread portion is composed of a rubber composition containing a rubber component and a plasticizer, The rubber component contains one or more selected from the group consisting of styrene butadiene rubber and isoprene rubber, The plasticizer contains a copolymer resin containing styrene and cyclopentadiene as monomer components, Let the groove depth at the deepest part of the two or more lateral grooves be H (mm), When the total styrene amount in the rubber composition is S (mass%), A tire in which H / S is less than 5.0.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a tire in which the overall performance of low fuel consumption performance, wet grip performance and quiet performance is improved.

Brief Description of the Drawings

[0008] [Figure 1] It is a diagram schematically showing a tread pattern of a tire according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view taken along the line X-X of FIG. 1.

Mode for Carrying Out the Invention

[0009] The following describes a tire that is one embodiment of the present invention. The tire of this embodiment is a tire having a tread portion, the tread portion having two or more ribs partitioned by one or more circumferential grooves, at least one of the ribs having two or more lateral grooves, the length of the widthwise component of the two or more lateral grooves being 20% ​​or more of the width of the rib, at least a portion of the circumferential component of adjacent lateral grooves overlapping, the tread portion being composed of a rubber composition containing a rubber component and a plasticizer, the rubber component containing one or more selected from the group consisting of styrene-butadiene rubber and isoprene-based rubber, the plasticizer containing a copolymer resin containing styrene and cyclopentadiene as monomer components, and when the groove depth of the deepest part of the two or more lateral grooves is H (mm) and the total amount of styrene in the rubber composition is S (mass%), the H / S ratio is less than 5.0.

[0010] While not intended to be constrained by theory, the following are possible reasons why the overall performance of fuel efficiency, wet grip performance, and quietness is improved in this invention.

[0011] Specifically, (1) the tread portion has two or more ribs separated by one or more circumferential grooves, and at least one of the ribs is provided with two or more transverse grooves, and the length of the widthwise component of the two or more transverse grooves is 20% or more of the width of the rib, which is thought to help to remove water from the road surface and thus contribute to improved wet grip performance. (2) Since at least a portion of the circumferential component of adjacent transverse grooves overlaps, pitch noise is reduced, which is thought to contribute to improved quietness.

[0012] (3) Copolymer resins containing styrene and cyclopentadiene as monomer components are bulky. Therefore, by including this in the rubber composition, flexibility is imparted without impairing the reinforcing effect, which is thought to contribute to maintaining the wet grip performance of the tire. Furthermore, because the cyclopentadiene and / or dicyclopentadiene portion (DCPD portion) of the copolymer resin has high compatibility with styrene-butadiene rubber and isoprene-based rubber, it is less likely to leach from the rubber component, and the 30°C tanδ of the rubber composition is lower, which is thought to contribute to achieving both fuel efficiency and wet grip performance. In addition, because the styrene component of the copolymer resin softens during vehicle operation, noise at tire contact can be reduced, which is thought to contribute to improved quietness. And, (4) by having an H / S of less than 5.0, fuel efficiency is improved without impairing wet grip performance and quietness, and the overall performance of fuel efficiency, wet grip performance and quietness is improved. Furthermore, it is believed that the combined efforts of (1) to (4) above will improve overall performance in terms of fuel efficiency, wet grip performance, and quietness.

[0013] The tread portion preferably has two or more circumferential grooves.

[0014] The presence of two or more circumferential grooves makes it easier to remove water from the road surface, which is expected to further improve wet grip performance.

[0015] The tread portion has five ribs separated by four circumferential grooves, and it is preferable that at least a portion of the circumferential component of an adjacent transverse groove overlaps in any of the five ribs.

[0016] The rubber composition preferably contains 50 parts by mass or more of silica per 100 parts by mass of rubber component.

[0017] By including 50 parts by mass or more of silica, the interaction between the silanol groups of silica and moisture on the road surface improves the tread's ability to follow the road surface, thus further enhancing wet grip performance.

[0018] When the tanδ of the rubber composition at 0°C is 0°Ctanδ and the complex modulus of elasticity of the rubber composition at 0°C is 0°CE* (MPa), it is preferable that 0°Ctanδ / 0°CE* × 1000 is greater than 65.

[0019] It is believed that the effects of the present invention are further enhanced if 0℃tanδ / 0℃E*×1000 falls within the aforementioned range.

[0020] When the tanδ of the rubber composition at 30°C is 30°Ctanδ and the complex modulus of elasticity at 30°C is 30°CE* (MPa), it is preferable that 30°Ctanδ × 30°CE* × 100 is less than 60.

[0021] It is believed that the effects of the present invention are further enhanced if 30°C tanδ × 30°C E* × 100 falls within the aforementioned range.

[0022] When the complex modulus of elasticity of the rubber composition at 30°C is 30°CE* (MPa), it is preferable that 30°CE* / H is 0.50 or less.

[0023] It is believed that the effects of the present invention are further enhanced when the temperature is within the aforementioned range of 30℃E* / H.

[0024] It is preferable that the total length of the overlapping portion of the circumferential components of the two or more lateral grooves relative to the entire circumference of the tire is 5.0% or more.

[0025] It is believed that the noise reduction performance will be further improved if the total length of the overlapping portion of the circumferential component of the lateral grooves relative to the entire circumference of the tire is within the aforementioned range.

[0026] The tire according to this embodiment is preferably for use with an SUV.

[0027] [Definition] "Standard condition" refers to a state of no load where the tire is mounted on a standard rim and filled with air at the standard internal pressure. Unless otherwise specified, tires in the standard condition should be used.

[0028] Unless otherwise specified, the "dimensions of each part of the tire" refer to values ​​that are determined in the normal state for those visible on the outer surface of the tire, while those located inside the tire or on the cut surface of the tire refer to values ​​that are determined, for example, by cutting the tire in a plane including the tire's axis of rotation and holding the cut tire piece within the rim width of the normal rim.

[0029] A "standard rim" refers to the rim specified for each tire within the standards system that the tire is based on. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." Refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. In the case of a tire not specified in the above standards, it refers to the narrowest rim width among the smallest diameter rims that can be mounted on that tire and that can maintain internal pressure (i.e., do not cause air leakage between the rim and tire).

[0030] "Regular internal pressure" refers to the air pressure specified for each tire in the standards system, including the standard on which the tire is based. For example, for JATMA it refers to "maximum air pressure," for ETRTO it refers to "INFLATION PRESSURE," and for TRA it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims, refer to JATMA, ETRTO, and TRA in that order, and if there is an applicable size at the time of reference, follow that standard. In the case of tires not specified in the above standards, it refers to the regular internal pressure (but at least 250kPa) of another tire size (but specified in the standard) that is listed with the aforementioned regular rim as the standard rim. If multiple regular internal pressures of 250kPa or higher are listed, refer to the lowest value among them.

[0031] "Regular load (kg)" refers to the load specified for each tire in the standard system that the tire is based on. For example, for JATMA it is "Maximum Load Capacity," for ETRTO it is "LOAD CAPACITY," and for TRA it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims and regular in-tire pressure, refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. For tires not specified in the above standards, the maximum load capacity (kg) is calculated separately. L This is considered the normal load.

[0032] "Maximum load capacity W L The weight (kg) is calculated using the following formula: "V" is the virtual volume of the tire (mm²). 3), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the height of the tire's cross-section in the radial direction in a plane containing the tire's axis of rotation (mm), and "Wt" is the width of the tire's cross-section in the normal state (mm). Ht can be calculated by (Dt-R) / 2, where R is the rim diameter of the tire. Wt is the value obtained by removing any patterns or letters on the tire's sidewall. Note that the maximum load capacity is synonymous with the normal load mentioned above.

[0033]

number

[0034] The "tread portion" is a component that includes the part that forms the contact surface of the tire, and in the radial cross-section of the tire, if the tire has components that form the tire skeleton using steel or textile materials such as belt layers, belt reinforcement layers, and carcass layers, the tread portion is a component that is positioned radially outward from these components.

[0035] "Total styrene content S in the rubber composition" refers to the total amount of styrene (mass%) in the rubber composition, assuming the mass of the rubber component is 100% by mass. This is the sum of the styrene content in the rubber component and the styrene content in the compounding agents other than the rubber component. The styrene content is not particularly limited as long as it is a group having a styrene structure, but examples include styrene, α-methylstyrene, vinyltoluene, chlorostyrene, etc.

[0036] Specifically, first, for each rubber component, a value is calculated by multiplying the styrene content (mass%) by the mass fraction in the rubber component, and these values ​​are added together to obtain a total value (mass%). Next, for each styrene-containing compound other than the rubber component contained in the rubber composition, a value is calculated by multiplying the styrene content (mass%) of each styrene-containing compound by the mass fraction relative to 100 mass parts of the rubber component, and these values ​​are added together to obtain a total value (mass%). The sum of these two total values ​​is then taken as the total styrene amount S (mass%). Therefore, it is calculated using {Σ(styrene content (mass%) of each styrene-containing rubber × styrene content in the rubber component of each styrene-containing rubber (mass%) / 100) + Σ(styrene content (mass%) of each styrene-containing compound other than the rubber component × amount of each styrene-containing compound relative to 100 mass parts of the rubber component (mass parts) / 100)}. In this specification, if the "styrene portion" is styrene (for example, if the styrene portion-containing rubber is styrene-butadiene rubber), the "styrene portion content" may be expressed as "styrene content."

[0037] For example, if the rubber component consists of 30% by mass of a first SBR (styrene content: 25% by mass), 60% by mass of a second SBR (styrene content: 27.5% by mass), and 10% by mass of BR, and the rubber composition further contains, in addition to the rubber component, 20 parts by mass of a first resin component having a styrene portion (styrene content: 5% by mass) per 100 parts by mass of the rubber component, and 10 parts by mass of a second resin component having a styrene portion (styrene content: 1% by mass) per 100 parts by mass of the rubber component, then the total amount of styrene St in the rubber composition relative to 100% by mass of the rubber component is 25.1% by mass = {(25 × 30 / 100 + 27.5 × 60 / 100 + 0 × 10 / 100) + (5 × 20 / 100 + 1 × 10 / 100)}.

[0038] In this specification, "circumferential groove" refers to a groove that extends continuously in the circumferential direction of the tire. The circumferential groove may extend in a straight line along the circumferential direction, or it may extend in a wavy, sinusoidal, or zigzag pattern.

[0039] The "land area" refers to the part of the tire tread that makes contact with the ground when the tire is pressed against it, and is the part of the tread that constitutes the effective contact area.

[0040] A "rib" is a land area separated by two circumferential grooves, or a land area separated by a circumferential groove and the tire contact edge. The groove depth formed in this land area is shallower than the groove depth of the deepest part of the circumferential groove.

[0041] In this specification, "lateral groove" refers to a groove with a groove width of 20% or more of the rib's lateral width (tire axial length). Sipes are also included.

[0042] "Groove width" refers to the maximum distance between groove edges on the tread surface in a direction perpendicular to the groove's extension direction.

[0043] "Groove depth" refers to the distance between a straight line connecting the ends of the groove on the tread surface and the lowest point of the groove in the tire's radial direction, in a cross-section of the tire cut perpendicular to the groove's extension direction. If the groove depth varies in the tire's width direction and / or circumferential direction, the maximum value of the aforementioned straight-line distance shall be considered the groove depth.

[0044] "The groove depth H of the deepest part of two or more adjacent transverse grooves" refers to the groove depth of the groove with the deepest groove depth among two or more adjacent transverse grooves.

[0045] The "effective contact area" is the area of ​​the tire tread that makes contact with the ground when the tire is pressed against it. It is obtained by mounting the tire to a standard rim, filling it to the standard internal pressure, letting it stand at 25°C for 24 hours, then applying ink to the surface of the tire tread, applying a standard load (a load equal to the maximum load capacity) to the tire, pressing it perpendicularly to cardboard (camber angle of 0°), and transferring the ink.

[0046] A "plasticizer" is a material that imparts plasticity to rubber components and is extracted from rubber compositions using acetone. This definition includes both liquid plasticizers at 25°C and solid plasticizers at 25°C. However, it excludes waxes and stearic acid commonly used in the tire industry.

[0047] The "loss tangent and complex modulus of the rubber composition" are the loss tangent (tanδ) and complex modulus E* (MPa) measured in extension mode under various conditions using a dynamic viscoelasticity measuring device (e.g., GABO's Iplexer series). The sample used for dynamic viscoelasticity measurement is a vulcanized rubber composition measuring 20 mm in length, 4 mm in width, and 1 mm in thickness. When creating a sample by cutting from a tire, if the component used to create the sample is the tread, belt layer, or inner liner, the length of the sample should coincide with the tire's circumferential direction, and the thickness of the sample should coincide with the tire's radial direction. If the component used to create the sample is the sidewall, clinch, bead apex, or side reinforcement layer, the length of the sample should coincide with the tangential direction to the tire's circumference, and the thickness of the sample should coincide with the tire's width direction. In all cases, the sample should be prepared to be as close as possible to the specified dimensions. The strain applied to the sample is normalized with respect to length, and both the measured tanδ and E* are normalized with respect to the width and thickness of the sample; therefore, it is considered that there is no influence from the size of the sample.

[0048] "0℃tanδ" and "0℃E*" are the loss tangent (tanδ) and complex modulus E* (MPa), respectively, measured under conditions of 0℃ temperature, 10Hz frequency, 10% initial strain, ±2.5% dynamic strain, and extension mode.

[0049] "30℃tanδ" and "30℃E*" are the loss tangent (tanδ) and complex modulus E* (MPa), respectively, measured under conditions of 30℃ temperature, 10Hz frequency, 5% initial strain, ±1% dynamic strain, and extension mode.

[0050] The "rubber component of the rubber composition" is a component that contributes to crosslinking within the rubber composition and generally has a weight average molecular weight (Mw) of 10,000 or more.

[0051] The "glass transition temperature of the rubber component" is the static glass transition temperature of each rubber component determined by a differential scanning calorimeter (for example, Q200 manufactured by TA Instruments Japan Co., Ltd.).

[0052] The "content of the styrene portion" is calculated by thermal decomposition gas chromatography or NMR measurement ( 1 1H-NMR and 13 13C-NMR). Component amounts such as the "content of the styrene portion" are different from physical property values such as the complex elastic modulus (E*). Since there is a true value that does not depend on the measurement method, it is preferable to use a measurement method with as high precision as possible. In this specification, "thermal decomposition gas chromatography" refers to a method in which a sample is heated by a thermal decomposition device, the individual components contained in the gas-phase components generated by this heating are separated by a separation column, and each isolated component is analyzed.

[0053] The "vinyl content (amount of 1,2-bonded butadiene units)" is calculated by thermal decomposition gas chromatography or NMR measurement ( 1 1H-NMR and 13 13C-NMR). Similar to the "content of the styrene portion", since there is a true value that does not depend on the measurement method for the "vinyl content", it is preferable to use a measurement method with as high precision as possible.

[0054] The "cis content (amount of cis-1,4-bonded butadiene units)" is a value measured by infrared absorption spectrometry or NMR measurement ( 1 1H-NMR and 13 13C-NMR) in accordance with JIS K 6239-2:2017, and is applied to rubber components having repeating units derived from butadiene such as BR, for example. Similar to the "content of the styrene portion", since there is a true value that does not depend on the measurement method for the "cis content", it is preferable to use a measurement method with as high precision as possible.

[0055] The "weight-average molecular weight (Mw)" can be determined by converting the measured value using gel permeation chromatography (GPC) (for example, the GPC-8000 series from Tosoh Corporation, with a differential refractometer as the detector and TSKgel SuperMultipore HZ-M column from Tosoh Corporation) to a standard polystyrene equivalent. This method is applicable, for example, to SBR, BR, plasticizers, etc.

[0056] The nitrogen adsorption specific surface area (N2SA) of carbon black is measured in accordance with JIS K 6217-2:2017.

[0057] The nitrogen adsorption specific surface area (N2SA) of silica is measured by the BET method in accordance with ASTM D3037-93.

[0058] The "average primary particle diameter" is a value obtained by photographing particles with a transmission or scanning electron microscope and calculating the arithmetic mean of the particle diameters of 400 particles. If the particle is spherical, the diameter of the sphere is used as the particle diameter; if it is not spherical, the equivalent diameter of a circle (the positive square root of {4 × (particle area) / π}) is calculated from the microscope image and used as the particle diameter.

[0059] The "softening point of the resin component" is the temperature at which the sphere descends when the softening point specified in JIS K 6220-1:2015 7.7 is measured using a ring-type softening point measuring device.

[0060] [tire] A tire according to one embodiment of the present invention will be described below with reference to the drawings. The tire according to this embodiment has a tread portion, the tread portion has two or more ribs partitioned by one or more circumferential grooves, at least one of the ribs is provided with two or more lateral grooves, the length of the widthwise component of the two or more lateral grooves is 20% or more of the width of the rib, in the two or more lateral grooves, at least a portion of the circumferential component of adjacent lateral grooves overlaps, the tread portion is made of a predetermined rubber composition, and when the groove depth of the deepest part of the two or more lateral grooves is H (mm) and the total amount of styrene in the rubber composition constituting the tread portion is S (mass%), H / S is less than 5.0. Note that the embodiments shown below are merely examples, and the tire according to this embodiment is not limited to the embodiments shown below.

[0061] Figure 1 is a schematic representation of the tread pattern of a tire according to one embodiment of the present invention. In Figure 1, W represents the tire width direction, C represents the tire circumferential direction, Te represents the tire contact edge, and CL represents the tire equator.

[0062] The tread portion 1 of the tire according to this embodiment has two or more ribs 2, 3 that are demarcated by one or more circumferential mains 4. In Figure 1, two circumferential grooves 4 are provided on the tread surface. The number of circumferential grooves 4 in the tread portion 1 according to this embodiment is one or more, preferably two or more, more preferably three or more, and even more preferably four or more. Furthermore, it is preferable that the tread portion 1 has five ribs that are demarcated by four circumferential grooves.

[0063] At least one of the ribs 2, 3 is provided with two or more lateral grooves 5, 6 having a widthwise component of 20% or more of the rib's widthwise component. The lateral grooves 5, 6 have a widthwise component lw and a circumferential component lc. In the tire according to this embodiment, in two or more lateral grooves 5, at least a portion of the circumferential component lc of adjacent lateral grooves 5 overlaps.

[0064] In Figure 1, both the rib 2 located at the tire equator CL and the rib 3, which is demarcated by the tire contact end Te and the circumferential groove 4, are provided with lateral grooves having a component of 20% or more of the tire width direction. However, the tire according to this embodiment is not limited to this configuration, and the rib 2 located at the tire equator CL does not have lateral grooves, or it may have lateral grooves with a component of less than 20% of the tire width direction of the rib. In Figure 1, the lateral groove 6 provided on the rib 2 located at the tire equator CL does not have an overlapping circumferential component with adjacent lateral grooves 6.

[0065] In Figure 1, the lateral groove 6 provided on the rib 2 located at the tire equator CL has one end in communication with the circumferential groove 4. However, the lateral groove 6 in this embodiment is not limited to this configuration, and can also be a closed lateral groove that does not open to either the circumferential groove 4 or the tire contact end Te. Also, in Figure 1, the lateral groove 5 provided on the rib 3 separated by the tire contact end Te and the circumferential groove 4 is a closed lateral groove that does not open to either the circumferential groove 4 or the tire contact end Te. However, the lateral groove in this embodiment is not limited to this configuration, and may open to the circumferential groove and / or the tire contact end.

[0066] The tread portion according to this embodiment has five ribs separated by four circumferential grooves, and it is preferable that at least a portion of the circumferential component of adjacent transverse grooves overlaps in any of the five ribs.

[0067] In Figure 1, both circumferential grooves 4 extend linearly along the circumferential direction. However, the circumferential grooves in this embodiment are not limited to such configurations and may extend in a wavy, sinusoidal, or zigzag pattern along the circumferential direction, for example.

[0068] In Figure 1, the overlapping portion of the circumferential component lc of two or more transverse grooves 5 in the left rib 3 is indicated by L.

[0069] The total length of the overlapping portion L of the circumferential components of the two or more lateral grooves relative to the entire circumference of the tire is preferably 3.0% or more, more preferably 5.0% or more, even more preferably 8.0% or more, and particularly preferably 10.0% or more.

[0070] Figure 2 is a cross-sectional view along line XX in Figure 1. This cross-section is obtained by cutting in a direction perpendicular to the extension direction of two adjacent lateral grooves 5. Figure 2 shows a straight line 7 connecting the ends of the lateral grooves on the tread surface 9, and an extension line 8 of the lowest part of the lateral groove in the tire radial direction. "Groove depth H (mm) of two or more lateral grooves" refers to the depth of the groove with the deepest groove depth among the two or more lateral grooves.

[0071] In Figure 2, the groove depths of the two lateral grooves are different, with the left groove being deeper than the right groove. The two or more lateral grooves in this embodiment are not limited to this configuration, and the groove depths of the two or more lateral grooves may be the same. In the tire according to this embodiment, it is preferable that the groove depth at the deepest part of all lateral grooves is the same.

[0072] From the viewpoint of the effects of the present invention, the groove depth H of the deepest part of two or more lateral grooves is preferably 3.0 mm or more, more preferably 3.2 mm or more, even more preferably 3.5 mm or more, and even more preferably 4.0 mm or more. Furthermore, the groove depth H of the deepest part of two or more lateral grooves is preferably 12.0 mm or less, more preferably 10.0 mm or less, and even more preferably 8.0 mm or less.

[0073] The total styrene content S in the rubber composition constituting the tread portion according to this embodiment is preferably 0.6% by mass or more, more preferably 5.0% by mass or more, even more preferably 8.0% by mass or more, and particularly preferably 10.0% by mass or more. Furthermore, the total styrene content S in the rubber composition constituting the tread portion is preferably 25.0% by mass or less, more preferably 20.0% by mass or less, and even more preferably 15.0% by mass or less.

[0074] The H / S ratio is less than 5.0, preferably less than 3.0, more preferably less than 1.0, even more preferably less than 0.80, even more preferably less than 0.60, and particularly preferably less than 0.50. Furthermore, the H / S ratio is preferably greater than 0.10, more preferably greater than 0.20, and even more preferably greater than 0.30.

[0075] The tanδ (0°C tanδ) of the rubber composition constituting the tread portion at 0°C is preferably 0.35 or higher, more preferably 0.40 or higher, and even more preferably 0.45 or higher. Furthermore, the 0°C tanδ is preferably 0.60 or lower, more preferably 0.55 or lower, and even more preferably 0.50 or lower.

[0076] The complex modulus of elasticity (0°C E*) at 0°C of the rubber composition constituting the tread portion is preferably 4.5 MPa or higher, more preferably 5.0 MPa or higher, even more preferably 5.5 MPa or higher, and particularly preferably 6.0 MPa or higher. Furthermore, the 0°C E* is preferably 9.0 MPa or lower, more preferably 8.5 MPa or lower, and even more preferably 8.0 MPa or lower.

[0077] The tanδ (30°C tanδ) of the rubber composition constituting the tread portion at 30°C is preferably 0.15 or higher, more preferably 0.18 or higher, and even more preferably 0.20 or higher. Furthermore, the 30°C tanδ is preferably 0.30 or lower, more preferably 0.28 or lower, and even more preferably 0.25 or lower.

[0078] The complex modulus of elasticity (30°C E*) of the rubber composition constituting the tread portion at 30°C is preferably 1.8 MPa or higher, more preferably 2.0 MPa or higher, and even more preferably 2.2 MPa or higher. Furthermore, the 30°C E* is preferably 3.5 MPa or lower, more preferably 3.0 MPa or lower, and even more preferably 2.8 MPa or lower.

[0079] The 0℃tanδ / 0℃E*×1000 is preferably greater than 55, more preferably greater than 60, even more preferably greater than 65, even more preferably greater than 67, and particularly preferably greater than 68, from the viewpoint of achieving both low fuel consumption and wet grip performance. Furthermore, the 0℃tanδ / 0℃E*×1000 is preferably less than 100, more preferably less than 91, and even more preferably less than 80.

[0080] From the viewpoint of the effects of the present invention, 30℃tanδ × 30℃E* × 100 is preferably less than 65, more preferably less than 60, and even more preferably less than 55. Furthermore, 30℃tanδ × 30℃E* × 100 is preferably greater than 30, more preferably greater than 40, and even more preferably greater than 50.

[0081] From the viewpoint of the effects of the present invention, a 30℃E* / H of 0.65 or less is preferred, more preferably 0.60 or less, even more preferably 0.55 or less, and particularly preferred 0.50 or less. Furthermore, a 30℃E* / H of 0.30 or more is preferred, more preferably 0.35 or more, and even more preferably 0.40 or more.

[0082] Furthermore, the physical properties of the rubber composition, such as tanδ and E*, can be appropriately adjusted depending on the type and amount of rubber components, fillers, plasticizers, etc., as described below. For example, 30°C tanδ can be adjusted depending on the type of resin component.

[0083] When the tread portion consists of two or more layers, it is preferable that at least one layer constituting the tread portion satisfies the aforementioned physical properties, and it is more preferable that, among the two or more rubber layers constituting the tread portion, the cap rubber layer constituting the tread surface satisfies the aforementioned physical properties.

[0084] [Rubber composition] The rubber composition constituting the tread portion according to this embodiment will be described below. In this embodiment, the rubber composition includes a rubber component and a plasticizer.

[0085] <Rubber components> The rubber component contains one or more selected from the group consisting of styrene-butadiene rubber (SBR) and isoprene-based rubber, preferably containing SBR and isoprene-based rubber, and more preferably containing SBR, isoprene-based rubber and butadiene rubber (BR).

[0086] (SBR) There are no particular limitations on SBR, and examples include solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR). Modified SBRs include SBRs in which the terminals and / or main chain are modified, and modified SBRs coupled with tin, silicon compounds, etc. (condensates, those with branched structures, etc.). Furthermore, hydrogenated versions of these SBRs (hydrogenated SBRs) can also be used. These SBRs may be used individually or in combination of two or more types.

[0087] As the SBR, either oil-expanded SBR or non-oil-expanded SBR can be used. In this specification, as the SBR, commercially available products from JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Corporation, Asahi Kasei Corporation, ZS Elastomer Corporation, ARLANXEO, etc. can be used.

[0088] From the viewpoint of compatibility with copolymer resins containing styrene and cyclopentadiene as monomer components, the styrene content of SBR is preferably more than 10% by mass, more preferably more than 15% by mass, and even more preferably more than 18% by mass. On the other hand, the styrene content of SBR is preferably less than 55% by mass, more preferably less than 50% by mass, and even more preferably less than 45% by mass. If the styrene content of SBR exceeds 55% by mass, the styrene groups become adjacent, the polymer becomes too hard, crosslinking tends to become uneven, the performance changes with temperature changes become large, and stable grip performance tends not to be obtained well. The styrene content of SBR is measured by the measurement method described above.

[0089] The vinyl content of SBR is preferably more than 10 mol%, more preferably more than 15 mol%, and even more preferably more than 18 mol%. Furthermore, the vinyl content of SBR is preferably less than 70 mol%, more preferably less than 65 mol%, and even more preferably less than 60 mol%. In this specification, the vinyl content of SBR is measured by the measurement method described above.

[0090] From the viewpoint of wet grip performance, the glass transition temperature (Tg) of SBR is preferably -80°C or higher, more preferably -70°C or higher, and even more preferably -65°C or higher. From the viewpoint of fuel efficiency, the Tg of SBR is preferably -55°C or lower. The Tg of SBR is measured by the measurement method described above.

[0091] The weight-average molecular weight (Mw) of SBR is preferably greater than 200,000, more preferably greater than 300,000, even more preferably greater than 400,000, and particularly preferably greater than 500,000. Furthermore, from the viewpoint of crosslinking uniformity, the Mw is preferably less than 2,000,000, more preferably less than 1,500,000, and even more preferably less than 1,000,000. The Mw of SBR is measured by the measurement method described above.

[0092] The content of SBR in the rubber component (total content if 2 or more are present) is preferably more than 30% by mass, more preferably more than 40% by mass, even more preferably more than 50% by mass, and particularly preferably more than 55% by mass, from the viewpoint of compatibility with copolymer resins containing styrene and cyclopentadiene as monomer components. Furthermore, the content of SBR in the rubber component is preferably less than 80% by mass, and more preferably less than 75% by mass.

[0093] (Isoprene rubber) As isoprene-based rubbers, for example, isoprene rubber (IR) and natural rubber, which are common in the tire industry, can be used. Natural rubber includes not only unmodified natural rubber (NR), but also 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-based rubbers may be used individually or in combination of two or more types.

[0094] NR is not particularly limited and can be any that is common in the tire industry, such as SIR20, RSS#3, TSR20, etc.

[0095] The content of isoprene-based rubber in the rubber component is preferably more than 10% by mass, more preferably more than 15% by mass, even more preferably more than 20% by mass, and particularly preferably more than 25% by mass. Furthermore, the content of isoprene-based rubber in the rubber component is preferably less than 60% by mass, more preferably less than 50% by mass, and even more preferably less than 40% by mass.

[0096] (Diene-based rubber) As rubber components other than SBR and isoprene-based rubbers, diene-based rubbers other than SBR and isoprene-based rubbers are preferably used. Examples include butadiene rubber (BR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR). These diene-based rubbers may be modified rubbers treated with modifying groups that can interact with fillers such as carbon black and silica, or they may be hydrogenated rubbers in which some of the unsaturated bonds have been hydrogenated. Diene-based rubbers may be used alone or in combination of two or more. Furthermore, as the diene-based rubber, stretched rubber that has been pre-stretched using a plasticizer described later may be used.

[0097] The content of diene rubber in the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Alternatively, the rubber component may consist solely of diene rubber.

[0098] The rubber composition according to this embodiment contains one or more diene rubbers selected from the group consisting of SBR and isoprene rubbers, preferably containing SBR and isoprene rubber, and more preferably containing SBR, isoprene rubber and BR.

[0099] (BR) BR is not particularly limited, and 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 butadiene rubber synthesized using a rare-earth element catalyst (rare-earth BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc., which are common in the tire industry, can be used. These BRs may be used individually or in combination of two or more types.

[0100] High-cis BR can be commercially available from companies such as Nippon Zeon Co., Ltd., UBE Corporation, and JSR Corporation. Including high-cis BR can improve low-temperature properties and wear resistance. The cis content of high-cis BR is preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably more than 97 mol%. The cis content of BR is measured by the measurement method described above.

[0101] Rare earth-based BR is synthesized using a rare earth element catalyst, and has a vinyl content of preferably less than 1.8 mol%, more preferably less than 1.6 mol%, and even more preferably 1.5 mol% or less, and a cis content of preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably 97 mol% or more. As rare earth-based BR, commercially available products from companies such as Lanxess can be used.

[0102] SPB-containing BR refers to a type in which 1,2-syndiotactic polybutadiene crystals are not simply dispersed in BR, but are chemically bonded to and dispersed in BR. Such SPB-containing BR can be commercially available from companies such as UBE Corporation.

[0103] Examples of modified BR include BR modified with functional groups similar to those described for SBR above, as well as modified butadiene rubber (modified BR) in which the terminal and / or main chain is modified with functional groups containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen.

[0104] Other modified BRs include those obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and in which the ends of the modified BR molecule are linked by a tin-carbon bond (tin-modified BR). Furthermore, the modified BR may be either unhydrogenated or hydrogenated.

[0105] From the viewpoint of wear resistance, the weight-average molecular weight (Mw) of BR is preferably over 300,000, more preferably over 350,000, and even more preferably over 400,000. Furthermore, from the viewpoint of crosslinking uniformity, it is preferably less than 2,000,000, more preferably less than 1,000,000, and even more preferably less than 500,000. The Mw of BR can be determined by the method described above.

[0106] The content of BR in the rubber component is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. Furthermore, the content of BR in the rubber component is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0107] (Other rubber components) The rubber component may contain rubber components other than diene rubber (non-diene rubber) to the extent that it does not affect the effects of the present invention. As non-diene rubber, rubber components commonly used in the tire industry can be used, such as butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, polyethylene chloride rubber, fluororubber (FKM), acrylic rubber (ACM), hydrin rubber, etc. These other rubber components may be used individually or in combination of two or more. In addition to the above rubber components, known thermoplastic elastomers may or may not be included.

[0108] (Rubber components synthesized from recycled and biomass-derived raw materials) Monomers, which are the constituent units of synthetic rubbers such as IR, SBR, and BR, may be derived from underground resources such as petroleum and natural gas, or they may be recycled from rubber products such as tires or non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, but include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl compounds. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds are not particularly limited, but include styrene. In particular, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0109] The method for producing recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Furthermore, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and pressure, decomposed by microwaves, or extracted after mechanical grinding.

[0110] Furthermore, the monomers that make up polymers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural, forestry, and fishery products, sugars, wood chips, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha.

[0111] The biomass-derived monomer (biomass monomer) is not particularly limited and includes biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. Examples of the aromatic vinyl compound are not particularly limited but include styrene. Furthermore, the method for producing the biomass monomer is not particularly limited and includes, for example, biological and / or chemical and / or physical transformations of plants and animals. Typical biological transformations include fermentation by microorganisms, while chemical and / or physical transformations include those by catalysts, high heat, high pressure, electromagnetic waves, critical liquids, and combinations thereof.

[0112] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compounds. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0113] Whether the raw materials for a polymer are biomass-derived can be determined by measuring pMC (percent Modern Carbon) according to ASTM D6866-10. pMC refers to the percentage of modern standard reference carbon. 14 Sample relative to C concentration 14 This is a ratio of C concentrations and is used as an indicator of the biomass ratio of a compound. The significance of this value is described below.

[0114] 1 mole of carbon atoms (6.02 × 10⁻¹⁰) 23 (Each) contains approximately 6.02 × 10¹⁶ atoms, which is about one trillionth of the amount of carbon atoms in a normal atom. 11 individual 14 C exists. 14The half-life of C is 5730 years. 14 C is decreasing regularly. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been fixed after more than 226,000 years have passed since atmospheric carbon dioxide was taken in and fixed by plants, etc., C was initially included in these as well. 14 All elements of C have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas are no longer viable. 14 It contains absolutely no element C. Therefore, chemical substances produced using these fossil fuels as raw materials also contain C. 14 It contains absolutely no element C.

[0115] on the other hand, 14 C is continuously produced when cosmic rays undergo nuclear reactions in the atmosphere. Therefore, 14 In the Earth's atmospheric environment, carbon (C) is produced in a state where its decrease due to radioactive decay and its production through nuclear reactions are in equilibrium. 14 The amount of C is constant. Therefore, the amount of biomass resource-derived substances currently circulating in the environment 14 As mentioned above, the carbon concentration is approximately 1 × 10¹⁶ of the total carbon atoms. -12 These values ​​are approximately in mole percent. Therefore, the difference between these values ​​can be used to calculate the biomass ratio in a given compound.

[0116] this 14 C is typically measured as follows: Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 Perform measurement C). In the measurement, 14 As a modern standard reference for the concentration of C, the amount of cyclic carbon in nature as of 1950 14The C concentration will be used. The specific standard material will be the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific radioactivity of carbon in this oxalic acid (per gram of carbon) will be used. 14 The radioactivity intensity of C is separated by carbon isotope, 13 The standard value is obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date. 14 This value is used as the C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0117] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal conditions it will often not reach 100, and will show a value of approximately 110 pMC. On the other hand, regarding chemical substances derived from fossil fuels such as petroleum, 14 When the C concentration is measured, it will show a value of approximately 0 pMC (for example, 0.3 pMC). This value corresponds to the aforementioned biomass ratio of 0%.

[0118] For the reasons stated above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in rubber compositions is preferable from an environmental protection standpoint.

[0119] [Filler] The rubber composition according to this embodiment preferably contains a filler, preferably silica as the filler, and more preferably carbon black and silica. Alternatively, the filler may consist only of carbon black and silica.

[0120] <Silica> The silica used is not particularly limited, and common silica used in the tire industry can be used, such as silica prepared by a dry process (anhydrous silica) or silica prepared by a wet process (hydrated silica). The raw material for silica is not particularly limited, and may be a mineral-derived raw material such as quartz, or a biological-derived raw material such as rice husks (for example, silica made from biomass materials such as rice husks), or silica recycled from silica-containing products may be used. Among these, hydrated silica prepared by a wet process is preferred because it contains a large number of silanol groups. Silica may be used alone or in combination of two or more types.

[0121] Silica derived from biomass materials can be obtained, for example, by extracting silicates from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then using these silicates to react with sulfuric acid in the same way as conventional wet silica, the precipitate of silicon dioxide is filtered, washed with water, dried, and pulverized.

[0122] The silica recycled from silica-containing products can be, for example, silica recovered from products containing silica such as semiconductors and other electronic components, tires, desiccants, and diatomaceous earth and other filter materials. The recovery method is not particularly limited and can include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from semiconductors and other electronic components or tires is preferred.

[0123] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol.6, pp.216-222, etc.). Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0124] The nitrogen adsorption specific surface area (N2SA) of silica is considered to be 100m² from the perspective of reinforcing properties. 2 Preferably more than / g, 150m 2 More preferably than / g, 170m2 A value greater than / g is even more preferable. Also, from the viewpoint of heat generation and processability, 250m 2 Less than / g is preferable, 200m 2 Less than / g is more preferable, 180m 2 A value of less than / g is even more preferable. The N2SA of silica is measured by the measurement method described above.

[0125] From the viewpoint of reinforcing properties, the average primary particle diameter of silica is preferably greater than 10 nm, more preferably greater than 12 nm, and even more preferably greater than 15 nm. Furthermore, the average primary particle diameter is preferably less than 25 nm, and more preferably less than 20 nm. The average primary particle diameter of silica is measured by the measurement method described above.

[0126] The silica content in the filler is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. Furthermore, the silica content in the filler is preferably 95% by mass or less, and more preferably 90% by mass or less.

[0127] From the viewpoint of wet grip performance, the silica content per 100 parts by mass of rubber component is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, even more preferably 55 parts by mass or more, and particularly preferably 60 parts by mass or more. Furthermore, the silica content per 100 parts by mass of rubber component is preferably less than 120 parts by mass, more preferably less than 100 parts by mass, and even more preferably less than 80 parts by mass.

[0128] <Silane coupling agent> Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited, but examples include: sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; and 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane. Examples of silane coupling agents include amino-based silane coupling agents such as 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; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, it is preferable to contain a sulfide-based silane coupling agent and / or a mercapto-based silane coupling agent. As silane coupling agents, for example, those commercially available from Evonik Industries, Momentive, etc., can be used. These silane coupling agents may be used individually or in combination of two or more.

[0129] From the viewpoint of improving silica dispersibility, the silane coupling agent content is preferably more than 5 parts by mass, and more preferably more than 7 parts by mass, per 100 parts by mass of silica. Furthermore, from the viewpoint of cost and processability, it is preferably less than 15 parts by mass, more preferably less than 10 parts by mass, and even more preferably less than 9 parts by mass.

[0130] The content of the silane coupling agent per 100 parts by mass of the rubber component (total amount if multiple silane coupling agents are used in combination) is preferably more than 2 parts by mass, more preferably more than 3 parts by mass, and even more preferably more than 4 parts by mass, from the viewpoint of improving silica dispersibility. Furthermore, from the viewpoint of preventing a decrease in wear resistance, it is preferably less than 12 parts by mass, more preferably less than 10 parts by mass, and even more preferably less than 8 parts by mass.

[0131] <Carbon Black> The carbon black used is not particularly limited and includes N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw materials for carbon black may be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by thermal decomposition of waste tires. The manufacturing method for carbon black may be combustion such as the furnace method, hydrothermal carbonization (HTC), or thermal decomposition of methane such as the thermal black method. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbia Carbon Corporation, etc. Carbon black may be used alone or in combination of two or more types.

[0132] In addition to the above, from the perspective of life cycle assessment, carbon black made from biomass materials such as lignin, or recycled carbon black refined by thermal decomposition of carbon black-containing products such as tires, may also be used as carbon black.

[0133] In this specification, "recycled carbon black" refers to carbon black obtained by crushing used tires and other products containing carbon black, and calcining the crushed material, wherein, according to the thermogravimetric method compliant with JIS K 6226-2:2003, when oxidative combustion occurs by heating in air, the proportion of the mass of ash (ash content), which is the component that does not burn, is 13% by mass or more. In other words, the proportion of the mass (carbon content) lost due to the aforementioned oxidative combustion of recycled carbon black is 87% by mass or less. Recycled carbon black may also be represented as rCB.

[0134] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975, which refers to "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, states that it can be obtained by the pyrolysis of organic materials at 550-800°C in the absence of oxygen, or by vacuum pyrolysis at relatively low temperatures (

[0027] ). Carbon black obtained from such pyrolysis processes usually lacks functional groups on its surface, as referred to in

[0004] of Japanese Patent Publication No. 6856781 (Comparison of Surface Morphology and Chemistry of Pyrolysis Carbon Black and Commercial Carbon Black, Powder Technology 160 (2005) 190-193).

[0135] Recycled carbon black may lack functional groups on its surface, or it may be treated to include functional groups on its surface. Treatment to include functional groups on the surface of recycled carbon black can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. In addition, in Japanese Patent Publication No. 6856781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes carbon black treated to include functional groups on its surface.

[0136] Recycled carbon black can be purchased from companies such as Strable Green Carbon and LD Carbon.

[0137] The nitrogen adsorption specific surface area (N2SA) of carbon black is 80 m² from the perspective of reinforcing properties. 2 Preferably more than / g, 90m 2 More preferably than / g, 100m 2 More preferably than / g, 110m 2 A value exceeding / g is particularly preferred. Furthermore, from the viewpoint of heat generation and processability, 200m 2 Preferably less than / g, 150m 2 Less than / g is more preferable, 120m 2 A value of less than / g is even more preferable. The N2SA of carbon black is measured by the measurement method described above.

[0138] The average primary particle diameter of the carbon black is preferably greater than 15 nm, more preferably greater than 18 nm, and even more preferably greater than 20 nm. Furthermore, the average primary particle diameter is preferably less than 50 nm, more preferably less than 40 nm, and even more preferably less than 30 nm. The average primary particle diameter of the carbon black is measured by the measurement method described above.

[0139] The carbon black content per 100 parts by mass of rubber component is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more. Furthermore, the carbon black content per 100 parts by mass of rubber component is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less.

[0140] <Other fillers> The filler may contain other fillers besides silica and carbon black. These other fillers are not particularly limited, but may include, for example, aluminum hydroxide, calcium carbonate, alumina, clay, talc, and other fillers commonly used in the tire industry.

[0141] <Plasticizer> The rubber composition according to this embodiment contains a plasticizer, and as the plasticizer, it contains a copolymer resin containing styrene and cyclopentadiene as monomer components.

[0142] A plasticizer is a material that imparts plasticity to rubber components, and the concept includes both liquid and solid plasticizers at 25°C. Examples of plasticizers include resin components, oils, liquid rubber, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, from biomass, or from naphtha recycled from rubber or non-rubber products. Low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may also be used as plasticizers. Plasticizers may be used individually or in combination of two or more types.

[0143] <Copolymer resin containing styrene and cyclopentadiene as monomer components> The copolymer resin containing styrene and cyclopentadiene as monomer components is not particularly limited as long as it contains styrene and cyclopentadiene as monomer components, and may further contain other monomer components as listed below. Furthermore, these resins may be hydrogenated or modified. The "styrene" constituting the monomer component may be any compound having a styrene structure other than styrene, such as styrene, α-methylstyrene, vinyltoluene, and chlorostyrene.

[0144] Other monomer components besides styrene and cyclopentadiene are not particularly limited, but monomer components commonly used in petroleum resins are preferred, the C9 fractions listed below are more preferred, and indene is even more preferred.

[0145] The copolymer resin is preferably a copolymer resin containing styrene, cyclopentadiene and / or dicyclopentadiene, or indene as monomer components, and may be a hydrogenated or modified copolymer resin.

[0146] As the copolymer resin, for example, commercially available products from ExxonMobil, ENEOS Corporation, Zeon Corporation, Maruzen Petrochemical Co., Ltd., etc., can be used. The resin may be used alone or in combination of two or more types.

[0147] From the viewpoint of the effects of the present invention, the styrene content of the copolymer resin is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and even more preferably 1.0% by mass or more. Furthermore, there is no particular upper limit to the styrene content, but it can be, for example, less than 50% by mass, less than 40% by mass, less than 30% by mass, 10% by mass or less, 5% by mass or less, 3% by mass or less, etc.

[0148] From the viewpoint of the effects of the present invention, the softening point of the copolymer resin is preferably above 70°C, more preferably above 80°C, even more preferably above 90°C, and particularly preferably above 100°C. Furthermore, from the viewpoint of processability and improved dispersibility between the rubber component and the filler, it is preferably below 150°C, more preferably below 140°C, and even more preferably below 130°C. The softening point of the resin is measured by the measurement method described above.

[0149] The content of the copolymer resin per 100 parts by mass of the rubber component is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, even more preferably more than 15 parts by mass, and even more preferably more than 19 parts by mass. Furthermore, from the viewpoint of processability, the content is preferably less than 100 parts by mass, more preferably less than 80 parts by mass, even more preferably less than 60 parts by mass, and particularly preferably less than 40 parts by mass.

[0150] (Other resin components) The rubber composition according to this embodiment may contain resin components other than copolymer resins containing styrene and cyclopentadiene as monomer components. The other resin components are not particularly limited, but resins commonly used in the tire industry can be used, such as C9 resins, C5 resins, C5C9 resins, dicyclopentadiene resins, aromatic vinyl resins, coumarone resins, indene resins, terpene resins, rosin resins, and phenolic resins. These resin components may be used individually or in combination of two or more. Each resin component may also be used individually or in combination of two or more.

[0151] ≪C9 series resin≫ A "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a polymer obtained by polymerizing the C9 fraction alone, or a copolymer obtained by copolymerizing the C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) and a C9 fraction is called a DCPD / C9 resin. Furthermore, the C9 resin may be a hydrogenated or modified version of these resins. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene. As for C9 resins, commercially available products from companies such as BASF, Zeon Corporation, and ENEOS Corporation can be used.

[0152] ≪C5 series resin≫ "C5 resins" refer to resins obtained by polymerizing C5 fractions, and may be hydrogenated or modified resins. Examples of C5 fractions other than dicyclopentadiene include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, isoprene, piperylene, 2-methyl-1-butene, 2-methyl-2-butene, and 1-pentene. As C5 resins, commercially available products from companies such as Structol, Nippon Zeon Co., Ltd., and ENEOS Corporation can be used.

[0153] ≪C5C9 resin≫ "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified. As C5C9 petroleum resin, commercially available products from companies such as Tosoh Corporation and LUHUA can be used.

[0154] <Dicyclopentadiene resins> A "dicyclopentadiene-based resin" refers to a resin in which cyclopentadiene (CPD) and / or dicyclopentadiene (DCPD) are the most abundant monomer components, and these may be hydrogenated or modified resins. Preferred dicyclopentadiene-based resins include polymers obtained by polymerizing only dicyclopentadiene as a monomer, and copolymers (DCPD / C9 resins) obtained by copolymerizing dicyclopentadiene with the C9 fraction. Commercially available dicyclopentadiene-based resins from companies such as ExxonMobil, ENEOS Corporation, Nippon Zeon Corporation, and Maruzen Petrochemical Co., Ltd. can be used.

[0155] Aromatic vinyl resin "Aromatic vinyl resin" refers to a resin in which aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-chlorostyrene are the most abundant monomer components, and these may be hydrogenated or modified. As aromatic vinyl resins, α-methylstyrene or a homopolymer of styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, for reasons of being economical, easy to process, and having excellent heat generation properties. As aromatic vinyl resins, commercially available products from companies such as Kraton, Eastman Chemical Company, and Mitsui Chemicals, Inc. can be used.

[0156] Coumaron-based resin "Coumarone-based resin" refers to a resin containing coumarone as a monomer component, and may be hydrogenated or modified. Preferred coumarone-based resins include, for example, coumarone resin, which is a polymer with coumarone as the monomer component; coumarone-indene resin, which is a copolymer with coumarone and indene as monomer components; and coumarone-indene-styrene resin, which is a copolymer with coumarone, indene, and styrene as monomer components. As coumarone-based resins, commercially available products from companies such as Rutgers, Nippon Paint Chemical Co., Ltd., and Mitsui Chemicals, Inc. can be used.

[0157] Indene resin "Indene-based resin" refers to a resin containing indene as a monomer component, and may be hydrogenated or modified resins. Preferred indene-based resins include, for example, coumarone-indene resin, which is a copolymer of coumarone and indene as monomer components, and coumarone-indene-styrene resin, which is a copolymer of coumarone, indene, and styrene as monomer components. Commercially available indene-based resins from companies such as Rutgers, Nippon Paint Chemical Co., Ltd., and Mitsui Chemicals, Inc. can be used.

[0158] Terpene resins "Terpene resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, and dipentene as monomer components, and may be hydrogenated or modified. Preferred terpene resins include, for example, polyterpene resins, which are polymers in which one or more of the aforementioned terpene compounds are used as monomer components; aromatically modified terpene resins, which are copolymers in which the aforementioned terpene compounds and aromatic compounds are used as monomer components; and terpene phenol resins, which are copolymers in which the aforementioned terpene compounds and phenol compounds are used as monomer components. Examples of aromatic compounds that serve as monomer components in aromatically modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenol compounds that serve as monomer components in terpene phenol resins include phenol, bisphenol A, cresol, and xylenol. As terpene resins, commercially available products from companies such as Yasuhara Chemical Co., Ltd., Arakawa Chemical Industries, Ltd., and Nippon Terpene Chemical Co., Ltd. can be used.

[0159] ≪Rosin-based resin≫ "Rosin-based resin" refers to a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palastic acid, and isopimal acid, and may be hydrogenated or modified. Rosin-based resins are not particularly limited, but examples include natural resin rosin and rosin-modified resins obtained by hydrogenating, disproportionating, dimerizing, esterifying, etc. As rosin-based resins, commercially available products from companies such as Harima Chemical Industries, Ltd., Arakawa Chemical Industries, Ltd., and IREC Co., Ltd. can be used.

[0160] Phenolic resins "Phenol-based resins" refer to resins containing phenol compounds such as phenol and cresol as monomer components, and may also be hydrogenated or modified resins. Phenolic resins are not particularly limited, but examples include phenol-formaldehyde resins, alkylphenol-formaldehyde resins, alkylphenol-acetylene resins, oil-modified phenol-formaldehyde resins, and terpene-phenol resins. Phenolic resins that are commercially available from companies such as Sumitomo Bakelite Co., Ltd., DIC Corporation, and Asahi Organic Materials Co., Ltd. can be used.

[0161] ≪Softening point≫ From the viewpoint of wet grip performance, the softening point of the resin component is preferably above 80°C, more preferably above 90°C, and even more preferably above 100°C. Furthermore, from the viewpoint of processability and improved dispersibility between the rubber component and filler, it is preferably below 150°C, more preferably below 140°C, and even more preferably below 130°C. The softening point of the resin component is measured by the measurement method described above.

[0162] (Plasticizers other than resin components) This section explains plasticizers other than resin components, such as oils, liquid rubbers, and ester-based plasticizers.

[0163] (oil) Examples of oils include mineral oil, vegetable oil, and animal oil. Furthermore, from a life cycle assessment perspective, waste oil from rubber mixers and engines, or refined waste cooking oil from restaurants, may also be used. Oils may be used individually or in combination of two or more types.

[0164] In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oils (mineral oil), naphthenic oils, and aromatic oils. Specific examples of mineral oil include MES (Mild Extracted Solvate), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Furthermore, for environmental reasons, oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of such low-PCA oils include MES, TDAE, and heavy naphthenic oils.

[0165] In this specification, vegetable oils include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and wood wax. Furthermore, vegetable oils may also include refined oils (such as salad oil) obtained by refining the aforementioned oils, transesterified oils obtained by transesterifying the aforementioned oils, hydrogenated oils obtained by hydrogenating the aforementioned oils, thermally polymerized oils obtained by thermally polymerizing the aforementioned oils, oxidized polymerized oils obtained by oxidizing the aforementioned oils, and waste cooking oils recovered from use as edible oils. Note that vegetable oils may be liquid or solid at 25°C.

[0166] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer of three or more. Note that acylglycerols of two or more forms can be obtained by thermal polymerization, oxidative polymerization, etc. Also, the acylglycerol may be a liquid or a solid at 25°C.

[0167] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, 1 This can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours, and after removing the rubber composition, it is measured at room temperature. 1 When 1H-NMR was measured and the tetramethylsilane (TMS) signal was set to 0.00 ppm, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm. These signals are presumed to originate from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0168] The aforementioned fatty acids are not particularly limited and may be unsaturated or saturated fatty acids. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0169] In particular, it is desirable that the fatty acid contains fatty acids with few double bonds, i.e., saturated fatty acids or monounsaturated fatty acids, and oleic acid is preferred. As a vegetable oil containing such fatty acids, for example, a vegetable oil containing saturated fatty acids or monounsaturated fatty acids may be used, or a vegetable oil that has been modified by transesterification or other means may be used. Furthermore, in order to produce a vegetable oil containing such fatty acids, plants may be improved by breeding, genetic modification, or other means.

[0170] As for vegetable oils, commercially available products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used.

[0171] Examples of animal oils include fish oil, beef tallow, or oleyl alcohol which can be derived from them.

[0172] When oil is included, from the viewpoint of processability, the oil content per 100 parts by mass of rubber component is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and even more preferably 10 parts by mass or more. Furthermore, from the viewpoint of the effects of the present invention, the oil content is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 30 parts by mass or less.

[0173] (Liquid rubber) Liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at room temperature (25°C), but examples include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), liquid farnesene rubber, etc. Liquid rubber may be used alone or in combination of two or more types.

[0174] (Ester-based plasticizers) Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelaate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), and trixylenyl phosphate (TXP). Ester-based plasticizers may be used individually or in combination of two or more.

[0175] [Other compounding agents] In addition to rubber components, fillers, and plasticizers, the rubber composition according to this embodiment may appropriately contain compounding agents commonly used in the tire industry, such as processing aids, vulcanized rubber particles, waxes, stearic acid, zinc oxide, antioxidants, vulcanizing agents, and vulcanization accelerators.

[0176] (Processing aid) Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. These processing aids may be used individually or in combination of two or more. Examples of processing aids that can be used are those commercially available from companies such as Schill+Seilacher and Performance Additives.

[0177] When processing aids are included, the content per 100 parts by mass of rubber components is preferably more than 0.5 parts by mass, more preferably more than 1 part by mass, and even more preferably more than 1.5 parts by mass, from the viewpoint of exhibiting an effect of improving processability. Furthermore, from the viewpoint of abrasion resistance and fracture strength, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass.

[0178] (Vulcanized rubber particles) Vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the viewpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. One type of vulcanized rubber particle may be used alone, or two or more types may be used in combination.

[0179] The vulcanized rubber particles are not particularly limited and may be either unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0180] Commercially available vulcanized rubber products can be used, such as those from Lehigh, Muraoka Rubber Industries, and others.

[0181] (wax) The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used, such as mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. The wax can be commercially available from companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Paramelt Co., Ltd. The wax may be used alone or in combination of two or more types.

[0182] When wax is included, the amount of wax per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass, from the viewpoint of weather resistance of the rubber. Furthermore, from the viewpoint of preventing whitening of the tire due to bloom, it is preferably less than 10 parts by mass, more preferably less than 7.0 parts by mass, and even more preferably less than 5.0 parts by mass.

[0183] (Stearic acid) When stearic acid is included, its content per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass, from the viewpoint of processability. Furthermore, from the viewpoint of vulcanization rate, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass.

[0184] (Zinc oxide) When zinc oxide is included, its content per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass, from the viewpoint of processability. Furthermore, from the viewpoint of wear resistance, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass.

[0185] (Anti-aging agent) While not particularly limited, the following are examples of anti-aging agents: naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditril-p-phenyl Examples include p-phenylenediamine-based antioxidants such as diamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flexis, and others. The antioxidant may be used alone or in combination of two or more.

[0186] When an anti-aging agent is included, the content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 2 parts by mass, and even more preferably more than 3 parts by mass, from the viewpoint of the rubber's resistance to ozone cracking. Furthermore, from the viewpoint of wear resistance and wet grip performance, it is preferably less than 10 parts by mass, more preferably less than 8 parts by mass, and even more preferably less than 5 parts by mass.

[0187] (Vulcanizing agent) Sulfur is preferably used as a vulcanizing agent. Suitable sulfurs include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. The vulcanizing agent may be used alone or in combination of two or more types.

[0188] When sulfur is included as a vulcanizing agent, the amount of sulfur per 100 parts by mass of rubber component is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. When oil-containing sulfur is used as the vulcanizing agent, the amount of vulcanizing agent is the total amount of pure sulfur contained in the oil-containing sulfur.

[0189] Examples of vulcanizing agents other than sulfur include alkylphenol-sulfur chloride condensates, 1,6-hexamethylene-dithiosulfate sodium dihydrate, and 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane). These non-sulfur vulcanizing agents can be commercially available from companies such as Taoka Chemical Industries, Ltd., Lanxess Corporation, and Flexis. The vulcanizing agent may be used alone or in combination of two or more types.

[0190] (Vulcanization accelerator) Examples of vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamate, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Among these, sulfenamide, thiazole, and guanidine vulcanization accelerators are preferred. The vulcanization accelerator may be used alone or in combination of two or more types.

[0191] Examples of sulfenamide-based vulcanization accelerators include N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide (DCBS). Among these, N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS) is preferred.

[0192] Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, and di-2-benzothiazolyl disulfide. Among these, 2-mercaptobenzothiazole is preferred.

[0193] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salts of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine. Among these, 1,3-diphenylguanidine (DPG) is preferred.

[0194] When a vulcanization accelerator is included, its content per 100 parts by mass of the rubber component is preferably 1 part by mass or more, and more preferably 1.5 parts by mass or more. Furthermore, the content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably 8 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 6 parts by mass or less. By keeping the content of the vulcanization accelerator within the above range, it tends to be possible to ensure fracture strength and elongation.

[0195] <Various materials containing carbon atoms> In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin components, vulcanization accelerators, antioxidants, surfactants, etc.) may be derived from atmospheric carbon dioxide. Methods for obtaining these materials from carbon dioxide include directly converting carbon dioxide, or converting methane obtained through a methanation process in which methane is synthesized from carbon dioxide.

[0196] [Manufacturing method] Rubber compositions can be manufactured by known methods. For example, they can be manufactured by mixing each of the above components using rubber mixing equipment such as an open roll or closed-type kneader (Banbury mixer, kneader, etc.).

[0197] The mixing process includes, for example, a base mixing process in which compounding agents and additives other than the vulcanizing agent and vulcanization accelerator are mixed, and a final mixing (F mixing) process in which the vulcanizing agent and vulcanization accelerator are added to the mixture obtained in the base mixing process and mixed. Furthermore, the base mixing process can be divided into multiple processes as desired. When dividing the base mixing process, the method may be (1) a method in which some of the compounding agents and additives are mixed in advance to form a masterbatch, and then the remaining compounding agents and additives are added to the resulting masterbatch and mixed, or (2) a method in which all the compounding agents and additives to be mixed in the base mixing process are mixed at once, and then the mixture is remilled one or more times. In the method of (1) above, the number of masterbatches is not limited and may be two or more. Also, when the number of masterbatches is two or more, all the compounding agents and additives used in the base mixing process may be allocated to one of the masterbatches.

[0198] There are no particular limitations on the mixing conditions, but for example, in the base mixing process, mixing is performed at a discharge temperature of 150-170°C for 3-10 minutes, and in the final mixing process, mixing is performed at 70-110°C for 1-5 minutes. There are no particular limitations on the vulcanization conditions, but for example, vulcanization is performed at 150-200°C for 10-30 minutes.

[0199] The tire according to this embodiment can be manufactured by conventional methods using the rubber composition. Specifically, the unvulcanized rubber composition is extruded to match the shape of the tread portion, the unvulcanized tread portion is bonded together with other tire components on a tire molding machine by conventional methods and molded to form an unvulcanized tire, and the resulting unvulcanized tire is then heated and pressurized in a vulcanizing machine to manufacture the tire. The vulcanization conditions are not particularly limited, and for example, a method of vulcanizing at 150 to 200°C for 10 to 30 minutes can be used.

[0200] [Application] In this specification, tires include pneumatic tires and non-pneumatic tires, but pneumatic tires are preferred. Pneumatic tires can be used for passenger car tires, large passenger car tires, large SUV tires, small SUV tires, heavy-duty tires, small truck tires, motorcycle tires, racing tires, etc. In particular, they can be suitably used as SUV tires, and are optimally suited for large SUV tires. In this specification, heavy-duty tires refer to tires intended to be mounted on four-wheeled vehicles, with a maximum load capacity of 1000 kg or more.

[0201] The following examples (case studies) are shown as preferred for implementation, but the scope of the present invention is not limited to these examples. Table 1 shows the results calculated based on the evaluation method below, after examining rubber compositions and tires obtained according to Table 1 using the various chemicals listed below.

[0202] <Various chemicals> The chemicals used in the examples and comparative examples are summarized below. NR:TSR20 SBR1: SBR produced by the following manufacturing example 1 (S-SBR, Tg: -66℃, styrene content: 19% by mass, vinyl content: 19 mol%, non-oil-based) SBR2: SBR produced by the following manufacturing example 2 (S-SBR, Tg: -24℃, styrene content: 25% by mass, vinyl content: 61 mol%, non-oil-based) BR: UBEPOL BR (registered trademark) 150B manufactured by UBE Corporation (unmodified BR, cis content: 97 mol%, Mw: 440,000) Carbon Black: Tokai Carbon Co., Ltd.'s Seast N220 (N2SA: 114m 2 / g, average primary particle diameter: 22nm) Silica: UltraSil VN3 (N2SA: 175m) manufactured by Evonik Industries. 2 / g, average primary particle diameter: 18nm) Silane coupling agent: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Oil: VivaTec500 (TDAE oil) manufactured by H&R Co., Ltd. Resin component 1: ExxonMobil Oppera PR383 (hydrogenated DCPD-C9 resin, containing styrene and cyclopentadiene as monomer components, Mw: 770, softening point: 103°C, styrene content: 1.78% by mass) Resin component 2: SYLVATARAXX4150 manufactured by Kraton (polyterpene resin, Mw: 2500, softening point: 115℃) Wax: Ozoace Wax (paraffin wax) manufactured by Nippon Seiro Co., Ltd. Stearic acid: Beads of stearic acid manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Anti-aging agent 1: Nocrack 6C (6PPD) (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Anti-aging agent 2: Nocrack RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Sulfur: HK-200-5 (5% oil-containing powdered sulfur) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noxellar CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noxellar D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0203] Manufacturing Example 1: Manufacturing of SBR1 Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium is added to start polymerization. Polymerization proceeds under adiabatic conditions, reaching a maximum temperature of 85°C. When the polymerization conversion rate reaches 99%, 1,3-butadiene is added and polymerization is continued for another 5 minutes, after which N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane is added as a modifier to carry out the reaction. After the polymerization reaction is complete, 2,6-di-tert-butyl-p-cresol is added. Then, the solvent is removed by steam stripping and dried on a heated roller at 110°C to obtain SBR1.

[0204] Manufacturing Example 2: Manufacturing of SBR2 Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium is added to initiate polymerization. Polymerization proceeds under adiabatic conditions, reaching a maximum temperature of 85°C. When the polymerization conversion rate reaches 99%, 1,3-butadiene is added, and polymerization is continued for another 5 minutes. Then, a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane (monomer) and the oligomer component is added as a modifier to carry out the reaction. After the polymerization reaction is complete, 2,6-di-tert-butyl-p-cresol is added. Subsequently, the solvent is removed by steam stripping, and the mixture is dried on a heated roller at 110°C to obtain SBR2.

[0205] (Examples and Comparative Examples) According to the formulation shown in Table 1, chemicals other than sulfur and vulcanization accelerator were mixed in a 1.7 L closed Banbury mixer for 1 to 10 minutes until the discharge temperature reached 150 to 160°C to obtain a mixture. Next, sulfur and vulcanization accelerator were added to the mixture using a twin-screw open roll mixer and mixed for 4 minutes until the temperature reached 105°C to obtain an unvulcanized rubber composition. Using this unvulcanized rubber composition, it was extruded to match the shape of the tread section using an extruder equipped with a die of a predetermined shape, and bonded together with other tire components to produce an unvulcanized tire. The tire was then vulcanized at 170°C to obtain each test tire (size: 235 / 70R16). The tread pattern for all tires is as shown in Figure 1. In addition, the groove depth at the deepest part of the lateral groove was the same for all test tires. In all tires, the total length of the overlapping portion L of the circumferential component with respect to the entire circumference of the tire was 8.3%.

[0206] <Measurement of tanδ and E* at 0°C> Rubber test specimens are prepared by cutting out pieces from the tread of each test tire, with dimensions of 20 mm in length, 4 mm in width, and 1 mm in thickness, such that the tire circumference is the longer side and the tire radius is the thickness direction. For each rubber test specimen, the loss tangent (tanδ) and complex modulus E* (MPa) are measured using a GABO Iplexer series under the conditions of 0°C, 10 Hz frequency, 10% initial strain, ±2.5% dynamic strain, and extension mode.

[0207] <Measurement of tanδ and E* at 30°C> Rubber test specimens measuring 20 mm in length, 4 mm in width, and 1 mm in thickness are prepared by cutting from the tread of each test tire, with the tire circumference being the longer side and the tire radius being the thickness direction. For each rubber test specimen, the loss tangent (tanδ) and complex modulus E* (MPa) are measured using a GABO Iplexer series under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±1%, and the extension mode.

[0208] <Fuel efficiency> Using a rolling resistance tester, the rolling resistance of each test tire is measured when driven under a load of 3.43 kN and at a speed of 80 km / h. The reciprocal of this resistance is expressed as an index with the reference comparison set to 100. A higher index indicates lower rolling resistance and superior fuel efficiency. The reference comparison is Comparative Example 1.

[0209] <Wet grip performance> Each test tire is mounted on all wheels of a vehicle (domestic FF 2000cc), and the braking distance from an initial speed of 100 km / h is measured on a wet asphalt surface. The measurement results are expressed as an index using the following formula. A higher index indicates a shorter braking distance and superior wet grip performance. For the wet grip performance index, Comparative Example 1 is used as the standard comparative example. (Wet grip performance index) = (Braking distance of the reference comparison) / (Braking distance of each test tire) × 100

[0210] <Quietness Performance> Each test tire is mounted on all wheels of a vehicle (domestic FF 2000cc) and driven for 10 laps on a dry asphalt test course at approximately 80 km / h. During this test, 20 test drivers subjectively evaluate the quietness in the following frequency ranges: 40 Hz to 80 Hz (resonance range), 100 Hz to 160 Hz (low frequency range), 250 Hz to 400 Hz (mid frequency range), and 630 Hz to 1250 Hz (high frequency range). The evaluation is given as an integer value from 1 to 5 points (higher scores indicate better quietness), and the total scores of the 20 test drivers are calculated. The total score of the benchmark comparison (Comparative Example 1) is converted to a baseline value (100), and the evaluation results of each test tire are indexed and displayed in proportion to the total score. A higher number indicates better quietness performance.

[0211] <Overall Performance> The sum of the fuel efficiency index, wet grip performance index, and quietness performance index is displayed as the overall performance index.

[0212] [Table 1]

[0213] <Embodiment> Examples of embodiments of the present invention are shown below. [1] A tire having a tread portion, The tread portion has two or more ribs separated by one or more circumferential grooves, At least one of the aforementioned ribs is provided with two or more transverse grooves. The length of the widthwise component of the two or more transverse grooves is 20% or more of the width of the rib. In the two or more transverse grooves, at least a portion of the circumferential component of adjacent transverse grooves overlaps. The tread portion is composed of a rubber composition containing rubber components and a plasticizer. The rubber component contains one or more selected from the group consisting of styrene-butadiene rubber and isoprene-based rubber. The aforementioned plasticizer contains a copolymer resin comprising styrene and cyclopentadiene as monomer components. The groove depth of the deepest part of the two or more transverse grooves is H (mm). When the total amount of styrene in the rubber composition is S (mass%), Tires with an H / S rating of less than 5.0. [2] The tire according to [1] above, wherein the tread portion has two or more, preferably three or more, and more preferably four or more circumferential grooves. [3] The tread portion has five ribs separated by four circumferential grooves, The tire according to [1] or [2] above, wherein at least a portion of the circumferential component of adjacent lateral grooves overlaps in any of the five ribs. [4] The tire according to any one of [1] to [3] above, wherein the rubber composition contains 50 parts by mass or more, preferably 55 parts by mass or more, and more preferably 60 parts by mass or more of silica per 100 parts by mass of rubber component. [5] When the tanδ of the rubber composition at 0°C is 0°Ctanδ and the complex modulus of the rubber composition at 0°C is 0°CE*(MPa), A tire according to any one of the above [1] to [4], wherein 0℃tanδ / 0℃E*×1000 is greater than 65, preferably greater than 67, and more preferably greater than 68. [6] When the tanδ of the rubber composition at 30°C is 30°Ctanδ and the complex modulus of the rubber composition at 30°C is 30°CE*(MPa), A tire according to any one of the above [1] to [5], wherein 30℃tanδ × 30℃E* × 100 is less than 60, preferably less than 58, and more preferably less than 55. [7] The tire according to any one of [1] to [6] above, wherein when the complex modulus of elasticity of the rubber composition at 30°C is 30°CE* (MPa), 30°CE* / H is 0.50 or less, preferably 0.48 or less, and more preferably 0.45 or less. [8] The tire according to any one of [1] to [7] above, wherein the total length of the overlapping portion of the circumferential components of the two or more lateral grooves relative to the entire circumference of the tire is 5.0% or more, preferably 6.0% or more, and more preferably 8.0% or more. [9] The tire according to any one of [1] to [8] above, wherein the H / S is less than 1.0, preferably less than 0.80, and more preferably less than 0.60.

[10] A tire for SUVs, as described in any of [1] to [9] above. [Explanation of Symbols]

[0214] W (Tire width direction) C Tire circumferential direction CL Tire Equator lw lateral groove tire width direction component LC lateral groove tire circumferential component Te tire contact point Overlapping portion length of the circumferential component of transverse grooves L2 or greater 1. Tread section 2 ribs 3 Ribs 4 Circumferential groove 5 Yokomizo 6 Yokomizo 7. A straight line connecting the ends of the lateral grooves on the tread surface. 8. Extension of the lowest point of the lateral groove in the tire's radial direction. 9. Tread surface Groove depth at the deepest part of the transverse grooves of H 2 or higher

Claims

1. A tire having a tread portion, The tread portion has two or more ribs separated by one or more circumferential grooves, At least one of the ribs is provided with two or more transverse grooves. The length of the widthwise component of the two or more transverse grooves is 20% or more of the width of the rib. In the two or more transverse grooves, at least a portion of the circumferential component of adjacent transverse grooves overlaps. The tread portion is composed of a rubber composition containing rubber components and a plasticizer. The rubber component contains one or more selected from the group consisting of styrene-butadiene rubber and isoprene-based rubber. The aforementioned plasticizer contains a copolymer resin comprising styrene and cyclopentadiene as monomer components. Let H (mm) be the groove depth of the deepest part of the two or more transverse grooves. When the total amount of styrene in the rubber composition is S (mass%), Tires with an H / S rating of less than 5.

0.

2. The tire according to claim 1, wherein the tread portion has two or more circumferential grooves.

3. The tread portion has five ribs separated by four circumferential grooves. The tire according to claim 1 or 2, wherein at least a portion of the circumferential component of adjacent lateral grooves overlaps in any of the five ribs.

4. The tire according to claim 1 or 2, wherein the rubber composition contains 50 parts by mass or more of silica per 100 parts by mass of rubber component.

5. When the tanδ of the rubber composition at 0°C is 0°C tanδ and the complex modulus of the rubber composition at 0°C is 0°C E* (MPa), A tire according to claim 1 or 2, wherein 0°C tanδ / 0°C E* × 1000 is greater than 65.

6. When the tanδ of the rubber composition at 30°C is 30°C tanδ and the complex modulus of the rubber composition at 30°C is 30°C E* (MPa), A tire according to claim 1 or 2, wherein 30°C tanδ × 30°C E* × 100 is less than 60.

7. The tire according to claim 1 or 2, wherein, when the complex modulus of elasticity of the rubber composition at 30°C is 30°CE* (MPa), 30°CE* / H is 0.50 or less.

8. The tire according to claim 1 or 2, wherein the total length of the overlapping portion of the circumferential components of the two or more transverse grooves relative to the entire circumference of the tire is 5.0% or more.

9. The tire according to claim 1 or 2, wherein the H / S is less than 1.

0.

10. A tire according to claim 1 or 2, for use in SUVs.

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