TIRES

Abstract

pneumatic tire, which includes a tread section, wherein the tread section is composed of a rubber composition comprising 50 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, where the total styrene content in the rubber component is 25% by mass or less, where A BR A represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: A BR × L > 3000, where the carbon black content is less than 30 parts by mass, based on 100 parts by mass of the rubber component, and where the glass transition temperature of the rubber composition is lower than -30 °C.

Description

TECHNICAL AREA

[0001] The present invention relates to a tire. STATE OF THE ART

[0002] Various methods for improving wet grip performance and abrasion resistance have been investigated to date. For example, patent literature 1 discloses a rubber composition for tires comprising a diene-based rubber (A) comprising a predetermined amount of a specific conjugated diene-based rubber represented by a predetermined formula, silicon dioxide whose specific CTAB adsorption surface area lies within a predetermined range, and a silane coupling agent represented by a predetermined formula, and a pneumatic tire that uses the rubber composition for a tire tread.Patent literature 2 discloses a tire comprising a tread section, wherein the tread section has a loft ratio of 64% and consists of a rubber composition comprising 100 parts by mass silicon dioxide based on 100 parts by mass of the rubber component, wherein the rubber component contains 50% by mass of a butadiene rubber and 50% by mass of a styrene-butadiene rubber containing 37% by mass of styrene. QUOTE LIST PATENT LITERATURE Patent Literature 1: JP 2017-141405 A Patent literature 2: EP 4 169 739 A1 Patent literature 3: EP 4 296 082 A1 (republished) SUMMARY OF THE INVENTIONAL PROBLEM

[0003] Since wet adhesion performance and abrasion resistance are fundamentally contradictory, it is difficult to improve both performances simultaneously, and therefore further improvements are needed to achieve both performances.

[0004] One object of the present invention is to provide a tire that can achieve both wet grip performance during high-speed running and abrasion resistance at a low temperature. SOLUTION TO THE PROBLEM

[0005] The present invention relates to a tire according to claim 1: pneumatic tire, which includes a tread section, wherein the tread section is composed of a rubber composition comprising 50 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, where the total styrene content in the rubber component is 25% by mass or less, where A BRA represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: ABR×L>3000, where the carbon black content is less than 30 parts by mass, based on 100 parts by mass of the rubber component, and where the glass transition temperature of the rubber composition is lower than -30 °C.

[0006] The present invention also relates to a tire according to claim 2: pneumatic tire, which includes a tread section, wherein the tread section is composed of a rubber composition comprising 70 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, where the total styrene content in the rubber component is 25% by mass or less, where A BR A represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: ABR×L>3000, and where the glass transition temperature of the rubber composition is lower than -30 °C.

[0007] The present invention also relates to a tire according to claim 3: pneumatic tire, which includes a tread section, wherein the tread section is composed of a rubber composition comprising 50 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, where the total styrene content in the rubber component is less than 10% by mass, where A BR A represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: ABR×L>3000, and where the glass transition temperature of the rubber composition is lower than -30 °C.

[0008] The present invention also relates to a tire according to claim 4: pneumatic tire, which includes a tread section, wherein the tread section is composed of a rubber composition comprising 50 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, where the total styrene content in the rubber component is 25% by mass or less, where A BR A represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: ABR×L>3000, where the survey ratio L is 61% or more, and where the glass transition temperature of the rubber composition is lower than -30 °C.

[0009] The present invention also relates to a tire according to claim 5: pneumatic tire, which includes a tread section, wherein the tread section is composed of a rubber composition comprising 50 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, where the total styrene content in the rubber component is 25% by mass or less, where A BR A represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: ABR×L>3000, and where the glass transition temperature of the rubber composition is lower than -42 °C. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0010] According to the present invention, a tire can be provided that can achieve both wet grip performance during high-speed running and abrasion resistance at a low temperature. BRIEF DESCRIPTION OF THE FIGURES Fig. Figure 1 is a view that schematically represents the entire ground contact area of ​​a tread surface. Fig. Figure 2 is a flattened view of part of a tire tread with small holes in shoulder areas. Fig. Figure 3 is a flattened view of part of a tire tread with narrow circumferential grooves in shoulder areas. Fig.Figure 4 is a flattened view of part of a tire tread with widened circumferential grooves in rib sections closest to a tire centerline. Fig. Figure 5 is a view showing a cross-section of the widened circumferential groove in Fig. 4 along a plane passing through a tire rotation axis. DESCRIPTION OF EXECUTION FORMS

[0011] The tire, which is an embodiment of the present invention, is a pneumatic tire comprising a tread section, wherein the tread section is composed of a rubber composition comprising 50 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, wherein the total amount of styrene in the rubber component is 25% by mass or less, and where A BR A represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: ABR×L>3000.

[0012] Although it is not intended to be bound to theory, the following can be regarded in the present invention as a mechanism by which both wet adhesion performance during high-speed running and abrasion resistance at a low temperature can be achieved.

[0013] This means that (1) in the rubber composition forming the tread section, abrasion resistance is improved by using butadiene rubber (BR) as a major polymer of the rubber component; (2) the tread section's ability to follow a road surface is improved by incorporating a certain amount or more of silicon dioxide, thereby improving wet grip performance; (3) by further incorporating styrene-butadiene rubber (SBR) in the rubber component and adjusting the total styrene content of the rubber component to a certain value or less, the SBR is made readily compatible with the BR, and SBR domains in which silicon dioxides are readily dispersed are dispersed in a BR phase, effectively reinforcing the BR to maintain abrasion resistance and improving wet grip performance; (4) the rubber composition,(1) The rubber component, which includes a low total styrene content, has a low glass transition temperature, and therefore temperature dependence is reduced, and grip performance when the tire heats up due to high-speed running, and abrasion resistance during a period of low temperature are less likely to decrease, and (5) a road contact area is increased by maintaining a high tread surface elevation ratio, thereby dispersing abrasion energy introduced from the road surface to the tread surface, so that tread abrasion is thought to be suppressed. It is thought that the combined action of (1) to (5) will achieve both wet grip performance during high-speed running and abrasion resistance at low temperatures.

[0014] If A STY representing a total amount of styrene in mass %, fulfill ABR , L and A STY prefers the following inequality: (ABR / ASTY)×L>130

[0015] Since A BR , L and A STY Since they are restricted in an increase direction, in an increase direction and in a decrease direction, they are assumed to be advantageous for both wet adhesion performance during high-speed running and abrasion resistance at low temperatures.

[0016] It is preferred that the rubber composition comprises at least one type of hydrocarbon resin and that the hydrocarbon resin content in the rubber composition is 5% by mass or more.

[0017] Hydrocarbon resins, like silicon dioxide, are easily dispersed in the SBR domains, and therefore, by further combining a certain amount or more of hydrocarbon resin, the SBR domains, in which it is easy to disperse hydrocarbon resins, are dispersed in the BR phase, which is considered advantageous for both wet adhesion performance and abrasion resistance.

[0018] The silicon dioxide content, based on 100 parts by mass of the rubber component, is preferably 100 parts by mass or more.

[0019] It is assumed that the tracking ability towards a road surface of the tread section derived from silicon dioxide will be further improved, and wet grip performance will be improved.

[0020] The glass transition temperature of the rubber composition described above is preferably lower than -30 °C.

[0021] This is because it is assumed that the temperature dependence of the rubber composition is reduced, and that grip performance is less likely to decrease when the tire heats up due to high-speed running, and abrasion resistance is less likely to decrease during a period of low temperature.

[0022] The right-hand side of inequality (1) is preferably 3250, more preferably 3500.

[0023] It is assumed that improvements in abrasion resistance can be expected by increasing the butadiene rubber content and the spacing ratio of a product.

[0024] A salary A BR The proportion of butadiene rubber in the rubber component is preferably less than 70% by mass.

[0025] As the butadiene rubber content in the rubber component increases, abrasion resistance at low temperatures tends to improve, but as the temperature decreases, so does a loss in a temperature range (0 °C-tanδ) that is generally thought to contribute to wet adhesion, thus disrupting the balance with wet adhesion performance during high-speed running, and it is therefore considered necessary to adjust the content to less than 70 wt% in order to achieve both performance levels.

[0026] The glass transition temperature of the styrene-butadiene rubber is preferably lower than -30 °C.

[0027] It is assumed that the glass transition temperature of the rubber composition will be lowered, and adhesion performance will be less likely to decrease when the tire heats up due to high-speed running, and abrasion resistance will be less likely to decrease further during a period of low temperature.

[0028] It is preferred that the tread surface has two or more main circumferential grooves extending in a tire circumferential direction and rib sections separated by the main circumferential grooves, and, if a pair of rib sections located on an outermost side in a tire width direction of the rib sections are defined as shoulder rib sections, the shoulder rib sections have one or more small holes, each with an opening area greater than 0.1 mm. 2 and smaller than 15 mm 2 exhibit.

[0029] Since the small holes contribute to improved drainage performance, drainage performance in a shoulder area is improved, so it is assumed that wet adhesion performance is improved.

[0030] It is preferred that the tread surface has two or more main circumferential grooves extending in the tire circumferential direction and rib sections separated by the main circumferential grooves and, if a pair of rib sections located on the outermost side in the tire width direction of the rib sections are defined as shoulder rib sections, the shoulder rib sections have at least one or more narrow circumferential grooves.

[0031] Since the narrow circumferential grooves contribute to improved drainage performance, drainage performance in the shoulder area is improved, so it is assumed that wet grip performance is improved.

[0032] The tread surface has widened circumferential grooves, the groove width of which widens towards the inside in the tire radial direction.

[0033] Since the width of the widened circumferential groove increases as the tread section wears down, drainage performance improves after tire wear, so it is assumed that wet grip performance improves.

[0034] The widened circumferential groove is preferably located on a rib section that lies on a tire centerline, or, if a main circumferential groove is present on the tire centerline, on a rib section that is closest to the tire centerline.

[0035] It is assumed that drainage performance improves after tire wear in a central section in the tire width direction, thus improving wet grip performance. [Definitions]

[0036] A "standardized condition" is a condition in which a tire is mounted on a standardized rim, filled with a standardized internal pressure, and no load is applied.

[0037] Unless otherwise specified, a “dimension of each part of the tire” is a value specified in a standardized condition for one occurring on the outer surface of the tire, while a value for one within the tire is specified in a condition in which the tire is cut along a plane containing a tire axis of rotation and the cut piece of tire is held to a rim width of a standardized rim.

[0038] A "standardized rim" is a rim within a standard system that includes a standard on which the tire is based, and which is defined by the standard for each tire. For example, "standardized rim" refers to a standard rim of an applicable size described in the "Jatma Year Book" of JATMA (The Japan Automobile Tire Manufacturers Association, Inc.), a "Measuring Rim" described in the "STANDARDS MANUAL" of ETRTO (The European Tyre and Rim Technical Organisation), or a "Design Rim" described in the "YEAR BOOK" of TRA (The Tire and Rim Association, Inc.), referenced in that order, and if an applicable size exists at the time of reference, the rim conforms to its standard.Furthermore, in the case of tires not defined by the standard, the "standardized rim" refers to a rim that can be mounted and maintain internal pressure, that is, one that, among rims that do not cause air leakage between the rim and the tire, has the smallest rim diameter and, secondly, the narrowest rim width.

[0039] A “standardized internal pressure” is an air pressure in a standard system containing a standard on which the tire is based, defined by the standard for each tire. It refers, for example, to a “MAXIMUM AIR PRESSURE” in JATMA, “INFLATION PRESSURE” in ETRTO, or a maximum value described in the “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” table in TRA, to which reference is made in that order, as in the case of the standardized rim, and if there is an applicable size at the time of reference, the standardized internal pressure conforms to its standard.Furthermore, in the case of tires not defined by the standard, the standardized internal pressure should refer to a standardized internal pressure (250 kPa or more) of another tire size (specified in the standard) for which the standardized rim is described as a standard rim, and if several standardized internal pressures of 250 kPa or more are described, it should refer to a minimum value below that.

[0040] A "standardized load" is a load within a standard system that includes a standard on which the tire is based. This load is defined by the standard for each tire, for example, a "MAXIMUM LOAD CAPACITY" for JATMA, a "LOAD CAPACITY" for ETRTO, or a maximum value described in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table for TRA. Reference is made to this load in that order, as in cases of a standardized rim and standardized inflation pressure. If an applicable size exists at the time of reference, the load conforms to its standard. Then, in the case of tires not defined by the standard, a standardized load WL is calculated using the following equations. Furthermore, in this description, "maximum load capacity" has the same meaning as the standardized load described above. WL=0.000011×V+175 V=[(Dt / 2)2−(Dt / 2−Ht)2]×π×Wt V virtual volume of tires (mm) 3 ) Tire outer diameter (mm) Tire cross-sectional height (mm) Wt tire cross-sectional width (mm)

[0041] A “lift ratio L (%)” is calculated from a total ground contact area and an effective ground contact area of ​​a tire using the following equation: Elevation ratio L(%)=(effective ground contact area / gemsated ground contact area)×100.

[0042] The "total contact area" is the area of ​​a tire's tread as it would appear when a tire is pressed against the ground. The total contact area can be obtained by mounting a tire on a standardized rim, inflating it to a standardized pressure, and leaving it at 25°C for 24 hours. This is followed by coating the tire tread surface with ink, applying a standardized load (the maximum load capacity) to the tire to press it vertically against a piece of cardboard (at a camber angle of 0°), and transferring the ink. The total contact area is determined as the average of five areas obtained by performing the transfer process described above at five different locations, rotating the tire by 72° each time.

[0043] The "effective contact patch" is the area of ​​a tire's tread where it makes contact with the ground when pressed against it. The effective contact patch can be obtained by mounting a tire on a standardized rim, inflating it to a standardized pressure, and leaving it at 25°C for 24 hours. This is followed by coating the tire tread surface with ink, applying a standardized load (the maximum load capacity) to the tire to press it vertically against a piece of cardboard (at a camber angle of 0°), and transferring the ink. The effective contact patch is determined as the average of five areas obtained by performing the transfer process described above at five different locations, rotating the tire 72° each time.

[0044] A “total styrene content (mass %)” is a total content of styrene particles contained in a total quantity of rubber components, which can be calculated by Σ(styrene content (mass %) in each rubber component × content (mass %) of each rubber component in total quantity of rubber components / 100). For example, if 100 wt% of a rubber component consists of 85 wt% of a styrene-butadiene rubber with 40 wt% styrene content, 5 wt% of a styrene-butadiene rubber with 25 wt% styrene content and 10 wt% of a butadiene rubber with 0 wt% styrene content, the total amount of styrene in the rubber component is 35.25 wt% (= 40 × 85 / 100 + 25 × 5 / 100 + 0 × 10 / 100).

[0045] A “carbon resin content” refers to the total content of all at least one type of carbon resin contained in a rubber composition.

[0046] A "plasticizer content" also includes the amount of a plasticizer in a rubber component extended by the plasticizer. Similarly, an "oil content" also includes the amount of oil contained in the oil-extended rubber.

[0047] A "major circumferential groove" refers to a circumferential groove that has a groove width of 4 mm or more in one direction of the tire's width on a tread surface, among circumferential grooves that extend continuously in one direction of the tire's circumference. The major circumferential groove may extend linearly along the circumference or may extend in a wavy, sinusoidal, or zigzag pattern along the circumference. However, widened circumferential grooves, which are described later, are not included.

[0048] A "strip section" is an area on a tread surface defined by a major circumferential groove, and it is the section where a tire contacts a road surface. Among strip sections, a pair of strip sections located on the outermost side in the tire's width direction are called shoulder strip sections, and a strip section located in an area sandwiched between the shoulder strip sections is called a center strip section. If there is a major circumferential groove, only shoulder strip sections are present, and no center strip section is present.

[0049] A "small hole" is a small hole present on a tread surface, extending from an inner edge of the tread and opening onto the tread surface. Small holes exist independently and do not interact with circumferential grooves, lateral grooves, or similar features.

[0050] A "narrow circumferential groove" refers to a circumferential groove with a width of less than 4 mm in one direction along the tire's circumference, as opposed to circumferential grooves that extend continuously in one direction. The narrow circumferential groove may extend linearly along the circumference or may extend in a wavy, sinusoidal, or zigzag pattern. However, wider circumferential grooves, which are described later, are not included.

[0051] A "widened circumferential groove" is a groove configured such that its width is minimal in one direction across the tire's width on the tread surface and widens towards the inside in a radial direction beneath circumferential grooves that extend continuously in one direction around the tire. The widened circumferential groove may extend linearly along the circumference or may extend in a wavy, sinusoidal, or zigzag pattern along the circumference. [Measurement method]

[0052] A “styrene content (mass %)” is determined by 1 Calculated H-NMR measurement.

[0053] A “vinyl content (1,2-bonded butadiene unit amount) (mol-%)” is calculated by infrared absorption spectrometry according to JIS K 6239-2:2017.

[0054] A “cis content (cis-1,4-bound butadiene unit amount) (mol-%)” is calculated by infrared absorption spectrometry according to JIS K 6239-2:2017.

[0055] A "glass transition temperature (Tg) (°C)" is measured by measuring the temperature while it is increased at a rate of 10 °C / min using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan Inc. according to JIS K 7121. In the present invention, the Tg of a styrene-butadiene rubber, a butadiene rubber, and the like is measured in particular.

[0056] A "glass transition temperature (Tg) of a rubber composition" is a temperature corresponding to a maximum value (tanδ peak temperature) within a range of -60 °C or higher and 40 °C or lower, based on a temperature distribution curve of tanδ obtained by measurement under conditions of a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ± 0.5%, and a temperature rise rate of 2 °C / min using a dynamic viscosity measuring device (e.g., EPLEXOR series, manufactured by gabo Systemtechnik GmbH). Furthermore, when measured in the range of -60 to 40 °C, if the tanδ value continues to gradually increase or decrease as the temperature rises, the glass transition temperature of the rubber composition should be 40 °C or -60 °C, respectively.Furthermore, in the range of -60 °C or higher and 40 °C or lower, if there are two or more points indicating the maximum value, the point with the lowest temperature shall be a glass transition temperature.

[0057] A “weight-mean molecular weight (Mw)” can be calculated in relation to a standard polystyrene based on measurements obtained by gel permeation chromatography (GPC) (e.g., GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0058] The "N2SA of soot" is measured according to JIS K 2.

[0059] The “N2SA of silicon dioxide” is measured by the BET method according to ASTM D3037-93.

[0060] An "average primary particle size" is calculated as the arithmetic mean of the particle sizes of 400 particles photographed with a transmission or scanning electron microscope. Regarding particle size, in cases where the particle is substantially circular, the diameter of the circle is defined as the particle size; in cases where it is needle- or rod-shaped, the minor axis is defined as the particle size; and in other cases, an equivalent circular diameter calculated from an electron micrograph is defined as the particle size. The equivalent circular diameter is calculated as "the positive square root of 4 × (particle area) / π". The average primary particle size is applied to silicon dioxide, carbon black, etc.

[0061] A “softening point” is specified as a temperature at which a ball falls when the softening point defined in JIS K 6220-1:2001 is measured using a ring-and-ball softening point measuring device. [Tires]

[0062] The pneumatic tire of the present invention is suitably described below with reference to the drawings. However, the drawings are merely illustrative, and the present invention should not be interpreted as limited on the basis of the drawings.

[0063] The pneumatic tire of the present invention is a tire comprising a tread section, wherein the tread section is composed of a predetermined rubber composition and wherein, in the rubber composition, when A BRA represents a mass-% content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface in the tread section. BR and L satisfy the following inequality: ABR×L>3000. <Ungleichung (1)>

[0064] In the pneumatic tire of the present invention, a tread surface elevation ratio L in % is defined as described above and is calculated from a total ground contact area and an effective ground contact area of ​​the tire.

[0065] Fig.Figure 1 shows a tread area for calculating the total ground contact area obtained from a contour when the tire is pressed against the ground. As described above, the contour can be obtained by mounting a tire on a standardized rim, applying a standardized internal pressure, and leaving the tire at 25°C for 24 hours. This is followed by coating the tire tread surface with ink, applying a standardized load (the maximum load capacity) to the tire to press it vertically against a piece of cardboard (a camber angle of 0°), and transferring the ink. Fig. 1 is CL a tire center line.

[0066] The survey ratio is preferably 60% or more, further preferably 61% or more, even more preferably 62% or more, even more preferably 63% or more, even more preferably 64% or more, and even more preferably 65% ​​or more. Furthermore, the survey ratio is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less.

[0067] The right-hand side of inequality (1) is preferably 3250, further preferably 3500, even more preferably 3750, and still more preferably 4000. On the other hand, there is an upper limit to the value of A. BR × L is not particularly restricted, but could be, for example, 6500, 6000 or 5000. <Ungleichung (2)>

[0068] The pneumatic tire of the present invention fulfills the requirements when A STY represents the total amount of styrene in mass % in the rubber component contained in the rubber composition, A BR , L and ASTY prefers the following inequality: (ABR / ASTY)×L>130.

[0069] The right-hand side of inequality (2) is preferably 200, more preferably 300, even more preferably 360, even more preferably 450, even more preferably 550, and even more preferably 600. On the other hand, there is an upper bound on the value of (A BR / A STY ) × L is not particularly restricted, but could be, for example, 750, 700 or 650. <Glasübergangstemperatur von Kautschukzusammensetzung>

[0070] In the rubber composition that forms the tread section of the pneumatic tire of the present invention, the glass transition temperature in °C of the rubber composition is lower than -30 °C.

[0071] To reduce the temperature dependence of the rubber composition, the glass transition temperature is preferably lower than -33 °C, more preferably lower than -37 °C, even more preferably lower than -40 °C, and still more preferably lower than -42 °C. On the other hand, a lower limit for the glass transition temperature is not particularly restricted, but may, for example, be higher than -50 °C, higher than -47 °C, or higher than -45 °C.

[0072] The glass transition temperature can be appropriately adjusted depending on the type and quantity of the rubber component that forms the rubber composition and on the type and quantity of additives other than the rubber component. <Kleines Loch>

[0073] In the pneumatic tire of the present invention, it is preferred that the tread surface has two or more main circumferential grooves extending in a tire circumferential direction and rib sections separated by the main circumferential grooves, and among the rib sections, a pair of rib sections located on an outermost side in a tire width direction is referred to as shoulder rib sections, the shoulder rib sections having one or more small holes, each with an opening area greater than 0.1 mm. 2 and smaller than 15 mm 2 exhibit.

[0074] Fig. Figure 2 represents an embodiment in which the pneumatic tire of the present invention has the small holes described above. Fig.2. Small holes 4 are formed on the pair of rib sections 3 located in the shoulder area of ​​the tread surface. Since the small holes contribute to improved drainage, drainage in the shoulder area is enhanced, which in turn improves wet grip. For example, in actual use, even if a shoulder rib section or middle rib section is preferably worn down on one side and the remaining shoulder rib section hardens over time, it is assumed that the small holes will ensure drainage and slightly improve wet grip after wear. The opening area of ​​the small hole to the tread surface is preferably larger than 0.1 mm². 2 , preferably larger than 0.5 mm 2 , preferably larger than 1.0 mm 2 and especially preferably larger than 1.5 mm 2Furthermore, the opening area of ​​the small hole in relation to the running surface is preferably less than 15 mm. 2 , preferably smaller than 10 mm 2 , preferably smaller than 7.0 mm 2 and especially preferably smaller than 5.0 mm 2 The depth of the deepest part of the small hole is preferably 3% or more, and further preferably 5% or more, of the depth of the deepest part of the main circumferential groove. Furthermore, the depth of the deepest part of the small hole is preferably 80% or less, more preferably 60% or less, and still more preferably 40% or less, of the depth of the deepest part of the main circumferential groove. <Schmale Umfangsrille>

[0075] In the pneumatic tire of the present invention, it is preferred that the tread surface has two or more main circumferential grooves extending in the tire circumferential direction and rib sections separated by the main circumferential grooves, and, if a pair of rib sections located on the outermost side in the tire width direction of the rib sections are defined as shoulder rib sections, the shoulder rib sections have at least one or more narrow circumferential grooves.

[0076] Fig. Figure 3 represents an embodiment in which the pneumatic tire of the present invention has the narrow circumferential grooves described above. Fig.Narrow circumferential grooves 5 are formed on the pair of rib sections 3, which are present in the shoulder area of ​​the tread surface. Since the narrow circumferential grooves contribute to improved drainage performance, drainage performance in the shoulder area is improved, which contributes to improved wet grip performance. <Verbreiterte Umfangsrille>

[0077] In the pneumatic tire of the present invention, the tread surface has widened circumferential grooves, the groove width of which widens towards the inside in the tire radial direction.

[0078] Fig. Figure 4 represents an embodiment in which the pneumatic tire of the present invention has the widened circumferential grooves described above. Fig.4 are linear widened circumferential grooves 6 formed on two rib sections 3 that abut a main circumferential groove 2 running along the tire centerline. The widened circumferential groove can, for example, extend along the circumferential direction in a wave shape, a sinusoidal shape, or a zigzag shape. Furthermore, the rib sections on which the widened circumferential grooves are formed are not particularly restricted, but the widened circumferential grooves are preferably formed on rib sections located on the tire centerline or, more preferably, on a rib section closest to the tire centerline, as the widened circumferential grooves 6 in Fig.4, if a major circumferential groove is present on the tire centerline. Additionally, the rib section closest to the tire centerline is a rib section where the distance between the end on the inside of the rib section in the tire width direction and the tire centerline is minimal.

[0079] Fig. Figure 5 represents a cross-section of the widened circumferential groove 6. Fig. 5. The groove width of the widened circumferential groove increases uniformly towards the inside in the tire radial direction, but the increase in groove width is not limited to such an aspect, and the groove width may, for example, increase while small increases and decreases are repeated in a curved or stepped shape. [Rubber composition]

[0080] The rubber composition forming the tread section of the pneumatic tire of the present invention is described below.

[0081] The rubber composition according to the present invention comprises 50 parts by mass or more of silicon dioxide based on 100 parts by mass of the rubber component. <kautschukkomponente>

[0082] The rubber component comprises more than 50% by weight of butadiene rubber (BR) and styrene-butadiene rubber (SBR). Furthermore, the rubber component may include other rubber components besides BR and SBR, such as isoprene-based rubber (IR-based rubber). Additionally, the rubber component may consist of more than 50% by weight of BR and SBR. (SBR)

[0083] The SBR is not particularly restricted; examples include solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), modified SBRs (a modified S-SBR, a modified E-SBR), and the like. Examples of modified SBR include SBR modified at its end and / or main chain, modified SBR coupled with tin, a silicon compound, etc. (a modified SBR of condensate or with a branched structure, etc.), and the like. Among these, S-SBR and modified SBR are preferred. Furthermore, hydrogenated versions of these SBRs (hydrogenated SBRs) and the like may also be used. The SBR may be used alone, or two or more may be used in combination.

[0084] Examples of S-SBR that can be used in the present invention include S-SBRs manufactured and sold by JSR Corporation, Sumitomo Chemical Co., Ltd., Ube Industries, Ltd., Asahi Kasei Corporation, ZS Elastomer Co., Ltd., etc.

[0085] To suppress temperature dependence of the rubber composition, the styrene content of an SBR is preferably low, for example, less than 40 wt%, more preferably less than 30 wt%, more preferably 20 wt% or less, and even more preferably 15 wt% or less. A lower limit for the styrene content is not particularly restricted, but is normally approximately greater than 1 wt%, greater than 3 wt%, or greater than 5 wt%. Furthermore, the styrene content of the SBR is measured using the measurement method described above.

[0086] To ensure reactivity with silicon dioxide, wet adhesion performance, rubber strength, and abrasion resistance, the vinyl content of the SBR is preferably greater than 10 mol%, more preferably greater than 13 mol%, and even more preferably greater than 15 mol%. Furthermore, to prevent an increase in temperature dependence, elongation at break, and abrasion resistance, the vinyl content of the SBR is preferably less than 50 mol%, more preferably less than 40 mol%, and even more preferably less than 30 mol%. The vinyl content of the SBR (unit amount of 1,2-bonded butadiene) is also measured using the method described above.

[0087] To suppress the temperature dependence of the rubber composition, the glass transition temperature (Tg) of an SBR is preferably lower than -30 °C. The Tg of the SBR is preferably lower than -40 °C, more preferably lower than -50 °C, and even more preferably lower than -55 °C. Furthermore, the Tg is typically higher than -80 °C, higher than -70 °C, or higher than -65 °C. The Tg of the SBR is also measured using the measurement method described above.

[0088] The weight-average molecular weight (Mw) of an SBR is preferably greater than 200,000, more preferably greater than 250,000, and even more preferably greater than 300,000, from the perspective of wet adhesion performance. Furthermore, from the perspective of crosslinking uniformity, the weight-average molecular weight is preferably less than 2,000,000, more preferably less than 1,800,000, and even more preferably less than 1,500,000. The weight-average molecular weight of the SBR is also measured using the measurement method described above.

[0089] From the perspective of wet adhesion performance, the SBR content in the rubber component is preferably more than 25% by mass, more preferably more than 30% by mass, and even more preferably 35% by mass or more. On the other hand, from the perspective of the effects of the invention, the SBR content in the rubber component is preferably 50% by mass or less, more preferably less than 48% by mass, and even more preferably 45% by mass or less. (BR)

[0090] The type of rubber (BR) is not particularly restricted, and those commonly used in the tire industry can be employed, such as a BR with a cis content of less than 50 mol% (a cis-poor BR), a BR with a cis content of more than 90 mol% (a cis-rich BR), a rare-earth-based butadiene rubber synthesized using a rare-earth-based catalyst (a rare-earth-based BR), a BR containing a syndiotactic polybutadiene crystal (an SPB-containing BR), a modified BR (a modified cis-rich BR, a modified cis-poor BR), and the like. Examples of modified BR include BRs modified with similar functional groups to those described above for the SBR, and the like. Among these, the modified BR is preferred. A BR can be used alone, or two or more can be used in combination.

[0091] For example, cis-rich butadiene alloys (BRs) from Zeon Corporation, Ube Industries, Ltd., JSR Corporation, etc., can be used. When the BRs are compounded with cis-rich BRs, low-temperature properties and abrasion resistance can be improved. The cis content is preferably greater than 95 mol%, more preferably greater than 96 mol%, and even more preferably 97 mol% or more. Furthermore, in this description, the cis content (cis-1,4-bonded butadiene unit quantity) is a value calculated by infrared absorption spectrometry.

[0092] The rare-earth-based BR comprises those synthesized using a rare-earth-element-based catalyst and having a vinyl content 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 preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably 97 mol% or more. For example, those commercially available from LANXESS, etc., can be used as the rare-earth-based BR.

[0093] Examples of BR containing SPB include those in which a 1,2-syndiotactic polybutadiene crystal is chemically bonded and dispersed in the BR, but not those in which the crystal is simply dispersed in the BR. BRs commercially available from Ube Industries, Ltd., etc., can be considered as such SPB-containing BRs.

[0094] Modified butadiene rubber (modified BR) can be used appropriately if it is modified at its end and / or main chain with a functional group containing at least one element selected from the group consisting of silicon, nitrogen and oxygen.

[0095] Examples of other modified BRs include those obtained by adding a tin compound after polymerizing 1,3-butadiene with a lithium initiator, with the end further bonded by a tin-carbon bond (tin-modified BR), and the like. Furthermore, the modified BR can be either non-hydrogenated or hydrogenated.

[0096] The weight-average molecular weight (Mw) of BR is preferably greater than 300,000, more preferably greater than 350,000, and even more preferably greater than 400,000, with regard to abrasion resistance. Furthermore, with regard to crosslink uniformity, etc., it is preferably less than 2,000,000, more preferably less than 1,000,000, and even more preferably less than 500,000. The Mw can also be calculated using the measurement method described above.

[0097] The rubber component according to the present invention comprises more than 50% by mass of a BR. A content A BR The BR content in the rubber component, from the perspective of abrasion resistance, is preferably more than 51 wt%, more preferably more than 53 wt%, and even more preferably 55 wt% or more. Furthermore, A BR In one embodiment, the wet adhesion performance is preferably less than 90% by mass, more preferably less than 85% by mass, even more preferably less than 80% by mass, and even more preferably less than 75% by mass. Furthermore, A is BR In another embodiment, preferably less than 70% by mass, more preferably less than 65% by mass, and even more preferably less than 60% by mass. (Other rubber components)

[0098] The rubber component according to the present invention can comprise rubber components other than SBR and BR. Other rubber components that can be used include crosslinkable rubber components commonly used in the tire industry, such as isoprene-based rubber (IR-based rubber), styrene-isoprene-butadiene copolymer rubber (SIBR), styrene-isobutylene-styrene block copolymer (SIBS), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), hydrogenated nitrile rubber (HNBR), butyl rubber (IIR), ethylene propylene rubber, polynorbornene rubber, silicone rubber, polyethylene chloride rubber, fluororubber (FKM), acrylic rubber (ACM), hydrin rubber, and the like. Other rubber components can be used alone, or two or more of them can be used in combination.

[0099] Examples of isoprene-based rubbers used in the tire industry include isoprene rubber (IR), natural rubber, and similar types. Natural rubbers include unreformed natural rubber (NR), refined natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), ultrapure natural rubber, grafted natural rubber, and similar types. Isoprene-based rubbers can be used alone, or two or more can be used in combination.

[0100] The NR is not particularly restricted, and those commonly used in the tire industry can be used, examples of which include SIR20, RSS#3, TSR20 and the like.

[0101] From the perspective of the effects of the present invention, the content of the other rubber components, when combined, in the rubber component is preferably less than 15 wt%, more preferably 10 wt% or less, and even more preferably less than 5 wt%. On the other hand, a lower limit for the content of the other rubber components in the rubber component is not particularly restricted and can be 0 wt%, but can also be, for example, greater than 1 wt%, greater than 2 wt%, or greater than 3 wt%. (Total amount of styrene)

[0102] A total amount of styrene (A STY ) is the total mass percent content of styrene components contained in a total quantity of rubber components, as defined above. In the present invention, the total amount of styrene in the rubber component is 25% by mass or less. The total amount of styrene is preferably less than 20% by mass, more preferably less than 15% by mass, and even more preferably less than 10% by mass. Furthermore, the total amount of styrene is typically about 3% by mass or more, 4% by mass or more, or 5% by mass or more. <Füllstoff>

[0103] The rubber composition forming the side wall according to the present invention comprises 50 parts by mass or more of silicon dioxide based on 100 parts by mass of the rubber component as a filler.

[0104] The rubber composition according to the present invention can comprise carbon black as a filler in addition to silicon dioxide. The rubber composition preferably comprises silicon dioxide and carbon black as fillers, and one filler can be one consisting of silicon dioxide and carbon black. (Silicon dioxide)

[0105] Silicon dioxide is not particularly restricted, and those commonly used in the tire industry can be employed, such as silicon dioxide produced by a dry process (anhydrous silicon dioxide), silicon dioxide produced by a wet process (hydrous silicon dioxide), and the like. Furthermore, from an environmental impact standpoint, silicon dioxide derived from biomass (for example, amorphous silicon dioxide purified from rice husks) can be used. Among these, hydrous silicon dioxide produced by a wet process is preferred because it contains many silanol groups. Silicon dioxide can be used alone, or two or more types can be used in combination.

[0106] Silicon dioxide from a biomass material can be obtained, for example, by burning rice hulls to obtain rice hull ash, extracting silicate from the rice hull ash using a sodium hydroxide solution, generating silicon dioxide by reacting the silicate with sulfuric acid in the same way as for conventional wet silicon dioxide, and filtering, washing with water, drying, and pulverizing the silicon dioxide precipitate. When silicon dioxide crystallizes, it is insoluble in water, and silicic acid, which is a component of it, cannot be used. Crystallization of silicon dioxide in rice hull ash can be suppressed by controlling the burning temperature and duration (JP 2009-2594 A, Akita Prefectural University Web Journal B / 2019, vol. 6, pp. 216-222, etc.). Amorphous silicon dioxide extracted from rice hulls can be used, such as that produced by Wilmar, etc.are commercially available.

[0107] A specific nitrogen adsorption surface area (N2SA) of silicon dioxide is preferably greater than 140 m² from the perspectives of fuel efficiency and abrasion resistance. 2 / g, preferably larger than 150 m 2 / g, preferably larger than 160 m 2 / g and even more preferably 175 m 2 / g or greater. Furthermore, from the perspectives of fuel efficiency and processability, it is preferably less than 350 m³. 2 / g, preferably less than 300 m 2 / g and even more preferably less than 250 m 2 / g. In addition, the N2SA of silicon dioxide is measured using the measurement method described above.

[0108] The average primary particle size of silicon dioxide is preferably greater than 10 nm, more preferably greater than 12 nm, and even more preferably greater than 14 nm. Furthermore, the average primary particle size is preferably less than 26 nm, more preferably less than 24 nm, and even more preferably 22 nm or less. The average primary particle size of silicon dioxide is also measured using the measurement method described above.

[0109] From the perspective of wet adhesion performance, the silicon dioxide content, based on 100 parts by mass of the rubber component, is preferably greater than 70 parts by mass, more preferably 80 parts by mass or more, still more preferably greater than 90 parts by mass, and still more preferably 100 parts by mass or more. Furthermore, from the perspective of abrasion resistance, it is preferably less than 200 parts by mass, more preferably less than 150 parts by mass, and still more preferably less than 130 parts by mass. (Soot)

[0110] Suitable carbon blacks include those commonly used in the tire industry, such as GPF, FEF, HAF, ISAF, SAF, and the like. In addition to the carbon blacks mentioned above, carbon black derived from lignin or recovered carbon black obtained through pyrolysis or similar processes from a product containing carbon black, such as a tire, can also be used from a life cycle assessment perspective. Carbon black can be used alone, or two or more types can be used in combination.

[0111] A specific nitrogen adsorption surface area (N2SA) of carbon black is preferably greater than 10 m² from the perspective of its amplifying properties. 2 / g, preferably larger than 30 m 2 / g and preferably larger than 50 m 2 / g. Furthermore, from the perspectives of fuel efficiency and processability, it is preferably less than 200 m³. 2 / g, preferably less than 175 m 2 / g and even more preferably less than 150 m 2 / g. Furthermore, the N2SA of soot is measured using the measurement method described above.

[0112] The average primary particle size of soot is preferably greater than 10 nm, more preferably greater than 12 nm, and even more preferably greater than 14 nm. Furthermore, the average primary particle size is preferably less than 26 nm, more preferably less than 24 nm, and even more preferably 22 nm or less. The average primary particle size of soot is also measured using the measurement method described above.

[0113] The carbon black content, when combined, based on 100 parts by mass of the rubber component, is preferably more than 1 part by mass, more preferably more than 3 parts by mass, and even more preferably 5 parts by mass or more, from the perspective of abrasion resistance and wet grip performance. Furthermore, from the perspective of fuel efficiency, it is preferably less than 50 parts by mass, more preferably less than 30 parts by mass, and even more preferably less than 10 parts by mass.

[0114] When both silicon dioxide and carbon black are combined, a silicon dioxide content is preferably higher than a carbon black content to achieve a balance between fuel efficiency, wet grip performance, and abrasion resistance. The ratio of silicon dioxide content to the total silicon dioxide and carbon black content is preferably more than 80% by weight, more preferably more than 90% by weight, and even more preferably more than 95% by weight. (Other fillers)

[0115] In addition to carbon black and silicon dioxide, other fillers can also be used. There are no particular restrictions on the choice of filler; for example, any filler commonly used in the tire industry can be used, such as aluminum hydroxide, aluminum oxide, calcium carbonate, magnesium sulfate, talc, clay, biochar, and the like. Other fillers can be used alone, or two or more can be used in combination.

[0116] From the perspective of abrasion resistance, the total filler content based on 100 parts by mass of the rubber component is preferably more than 40 parts by mass, further preferably more than 60 parts by mass, and even more preferably more than 80 parts by mass. Furthermore, from the perspective of fuel efficiency and elongation at break, it is preferably less than 250 parts by mass, further preferably less than 200 parts by mass, and even more preferably less than 150 parts by mass. (Silane coupling agent)

[0117] Silicon dioxide is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly restricted, and any silane coupling agent conventionally used in the tire industry in combination with silicon dioxide may be used, examples of which include thioester-based silane coupling agents such as 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, 3-octanoylthio-1-propyltrimethoxysilane, and the like; mercapto-based silane coupling agents such as those shown below in the following chemical formulas, and the like; sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl)disulfide, bis(3-triethoxysilylpropyl)tetrasulfide, and the like; and vinyl-based silane coupling agents such as vinyltriethoxysilane, vinyltrimethoxysilane, and the like.Silane coupling agents of an amino base, such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, and the like; glycydoxy-based silane coupling agents, such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and the like; nitro-based silane coupling agents, such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, and the like; chlorine-based silane coupling agents, such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, and the like; and the like. Thioester-based and / or sulfide-based silane coupling agents are preferred. The silane coupling agent may be used alone, or two or more may be used in combination.

[0118] It is preferred that the mercapto-based silane coupling agent is a compound represented by the following chemical formula (1), and / or a compound comprising a bonding unit A represented by the following chemical formula (2) and a bonding unit B represented by the following chemical formula (3). (where R 101 , R 102 and R 103 each independently an alkyl with 1 to 12 carbon atoms, an alkoxy with 1 to 12 carbon atoms, or a group consisting of -O-(R 111 - O) z -R 112 (z pieces of R 111 Each independently represents a divalent hydrocarbon group with 1 to 30 carbon atoms; R 112 represents an alkyl with 1 to 30 carbon atoms, an alkenyl with 2 to 30 carbon atoms, an aryl with 6 to 30 carbon atoms, or an aralkyl with 7 to 30 carbon atoms; and z represents an integer from 1 to 30). 104 an alkylene with 1 to 6 carbon atoms.) (where x represents an integer of 0 or more; y represents an integer of 1 or more; R 201 hydrogen atom or an alkyl with 1 to 30 carbon atoms, an alkenyl with 2 to 30 carbon atoms or an alkynyl with 2 to 30 carbon atoms, which are optionally replaced by a halogen atom, hydroxyl or carboxyl; and R 202 an alkylene with 1 to 30 carbon atoms, an alkenylene with 2 to 30 carbon atoms, or an alkynylene with 2 to 30 carbon atoms; where R 201 and R 202 together they can form a ring structure.)

[0119] Examples of the compound represented by chemical formula (1) include, for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, a compound represented by the following chemical formula (4) (Si363, manufactured by Evonik Degussa GmbH), and the like. Among these, the compound represented by chemical formula (4) may be suitable for use. They may be used individually, or two or more of them may be used in combination.

[0120] Examples of the compound containing bonding unit A represented by chemical formula (2) and bonding unit B represented by chemical formula (3) include, for example, those manufactured and sold by Momentive Performance Materials etc.

[0121] The content of the silane coupling agent, when combined, based on 100 parts by mass of the rubber component (a total of all silane coupling agents when used in combination), is preferably greater than 0.5 parts by mass, more preferably greater than 1.0 parts by mass, still more preferably greater than 2.0 parts by mass, and still more preferably greater than 4.0 parts by mass, with the aim of enhancing the dispersibility of silicon dioxide. Furthermore, with the aim of preventing a decrease in abrasion resistance, it is preferably less than 20 parts by mass, more preferably less than 12 parts by mass, still more preferably less than 10 parts by mass, and still more preferably less than 9.0 parts by mass.

[0122] The content of the silane coupling agent, based on 100 parts by mass of silicon dioxide, is preferably greater than 1.0 parts by mass, more preferably greater than 3.0 parts by mass, and even more preferably greater than 5.0 parts by mass, from the perspective of enhancing the dispersibility of silicon dioxide. Furthermore, from the perspectives of cost and processability, it is preferably less than 20 parts by mass, more preferably less than 15 parts by mass, and even more preferably less than 12 parts by mass. <plastifizierungsmittel>

[0123] The rubber composition relating to the present invention preferably comprises a plasticizing agent. Examples of the plasticizing agent include, for example, a hydrocarbon resin, oil, liquid rubber, an ester-based plasticizing agent, and the like. (hydrocarbon resin)

[0124] A hydrocarbon resin refers to a polymer with a skeleton formed from a hydrocarbon that is solid at 25°C. The hydrocarbon resin may generally include an oxygen element derived from a carboxyl group, a hydroxyl group, coumaron, or similar compounds. The term "hydrocarbon resin" is not particularly limited, and examples include petroleum-based resins, terpene-based resins, rosin-based resins, phenol-based resins, and similar compounds commonly used in the tire industry. Examples of hydrocarbon resins include those produced by Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Kraton Corporation, Eastman Chemical Company, Nitto Chemical Co., Ltd., Zibo Luhua Hongjin New Material Group Co., Ltd., and Nippon Shokubai Co., Ltd.The hydrocarbon resin is commercially available from ENEOS Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Co., Ltd., etc. It can be used alone, or two or more can be used in combination. <<Erdölharz> >

[0125] The petroleum resin used can be a C5-based petroleum resin, an aromatic petroleum resin, a C5 / C9-based petroleum resin, and the like. The petroleum resin can be used alone, or two or more can be used in combination.

[0126] A C5-based petroleum resin refers to a resin obtained by polymerizing a C5 fraction. Examples of the C5 fraction include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, isoprene, and the like, and can be obtained by hydrogenation or modification thereof. A dicyclopentadiene resin (DCPD resin) is suitable for use as a C5-based petroleum resin.

[0127] Aromatic petroleum resin refers to a resin obtained by polymerizing a C9 fraction and may be hydrogenated or modified. Examples of the C9 fraction include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, methylindene, and the like. Specific examples of aromatic petroleum resins include coumaron-indene resin, coumaron resin, indene resin, and aromatic vinyl-based resins.

[0128] As the aromatic vinyl-based resin, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is further preferred because it is economical, easy to process and excellent in terms of heat generation.

[0129] A C5 / C9-based petroleum resin refers to a resin obtained by polymerizing the C5 and C9 fractions and may be hydrogenated or modified. Examples of the C5 and C9 fractions include the petroleum fractions described above. <<Harz auf Terpen-Basis> >

[0130] Examples of terpene-based resins include a polyterpene resin composed of at least one terpene compound selected from those such as α-pinene, β-pinene, limonene, dipentene, and the like; an aromatically modified terpene resin made from a terpene compound from those described above and an aromatic compound; a terpenophenolic resin made from a terpene compound and a phenol-based compound; and those in which these terpene-based resins are hydrogenated (hydrogenated terpene-based resins). Examples of aromatic compounds used as raw materials for aromatically modified terpene resins include, for example, styrene, α-methylstyrene, vinyltoluene, divinyltoluene, and the like.Examples of phenol-based compounds used as raw materials for terpene phenol resin include phenol, bisphenol A, cresol, xylenol, and the like. The terpene-based resin can be used alone, or two or more can be used in combination. <<Harz auf Kolophonium-Basis> >

[0131] Examples of a rosin-based resin include, but are not limited to: a natural resin rosin; and a rosin-modified resin obtained by modifying it through hydrogenation, disproportionation, dimerization, esterification, or the like; etc. The rosin-based resin may be used alone, or two or more of them may be used in combination. <<Harz auf Phenol-Basis> >

[0132] Examples of phenol-based resins include, but are not limited to, phenol-formaldehyde resins, alkylphenol-formaldehyde resins, alkylphenol-acetylene resins, oil-modified phenol-formaldehyde resins, and the like. The phenol-based resin can be used alone, or two or more can be used in combination. < <erweichungspunkt>>

[0133] From the perspective of wet adhesion performance, the softening point of the hydrocarbon resin is preferably higher than 60 °C, more preferably higher than 70 °C, and even more preferably higher than 80 °C. Furthermore, from the perspective of processability and improved dispersibility of a rubber component with a filler, it is preferably lower than 150 °C, more preferably lower than 140 °C, and even more preferably lower than 130 °C. The softening point is also measured using the measurement method described above. <<Glasübergangstemperatur (Tg)> >

[0134] The thermal conductivity (Tg) of the hydrocarbon resin is preferably 110 °C or lower, more preferably 105 °C or lower, and even more preferably 100 °C or lower, for excellent compatibility with the rubber component. Furthermore, the thermal conductivity (Tg) is preferably -35 °C or higher, more preferably 0 °C or higher, and even more preferably 30 °C or higher, for excellent compatibility with the rubber component. The thermal conductivity (Tg) is also measured using a differential scanning calorimeter, as described above. <<Gewichtsmittleres Molekulargewicht (Mw)> >

[0135] The molecular weight (Mw) of the hydrocarbon resin is preferably greater than 500, more preferably greater than 600, and even more preferably greater than 650, considering the advantages of lower volatilization and good adhesion. Furthermore, considering that the hydrocarbon resin readily binds to a polymer and dissolves less from it, thus exhibiting excellent dry adhesion, the Mw is preferably less than 15,000, more preferably less than 13,000, and even more preferably less than 11,000. If the Mw is within the ranges described above, the resulting rubber composition exhibits excellent processability and may display improved heat generation and elongation at break. The Mw is also measured using the method described above. < <gehalt>>

[0136] The rubber composition according to the present invention preferably comprises at least one type of hydrocarbon resin, with regard to wet adhesion performance, etc. In the rubber composition of the present invention, the hydrocarbon resin content is preferably 5% by mass or more. The resin content in the rubber composition is further preferably more than 6% by mass, more preferably more than 7% by mass, more preferably more than 10% by mass, and more preferably more than 12% by mass. Furthermore, the hydrocarbon resin content in the rubber composition is also considered to have the following properties with regard to heat suppression, etc.preferably less than 100% by mass, further preferably less than 80% by mass, even more preferably less than 60% by mass, particularly preferably less than 50% by mass, most particularly preferably less than 35% by mass and most preferably less than 25% by mass. (Oil)

[0137] Examples of oil include process oil, vegetable fats and oils, animal fats and oils, and the like. Examples of process oil include paraffin-based process oil, naphthene-based process oil, aromatic-based process oil, and the like. Additionally, as an environmental measure, a process oil with a low polycyclic aromatic compound (PCA) content may be used. Examples of low PCA process oils include mild extraction solvents (MES), treated distillate aromatic extracts (TDAE), heavy naphthenic oils, and the like. Oils may be used alone, or two or more may be used in combination.

[0138] The oil content, when combined, based on 100 parts by mass of the rubber component, is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, and even more preferably more than 15 parts by mass, from the perspective of processability. Furthermore, from the perspective of abrasion resistance, it is preferably less than 120 parts by mass, more preferably less than 80 parts by mass, and even more preferably less than 40 parts by mass. In addition, the oil content in this description also includes any amount of oil contained in an oil-extended rubber. (Liquid rubber)

[0139] Liquid rubber is not particularly restricted as long as it is a polymer in a liquid state at normal temperature (25 °C). Examples include liquid butadiene rubber (liquid BR), liquid styrene-butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene-isoprene rubber (liquid SIR), liquid farnesene rubber, and the like. The liquid rubber can be used alone, or two or more can be used in combination.

[0140] The liquid rubber content, when combined, based on 100 parts by mass of the rubber component, is preferably greater than 1 part by mass, more preferably greater than 2 parts by mass, still more preferably greater than 3 parts by mass, and still more preferably greater than 5 parts by mass. Furthermore, the liquid rubber content is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, and still more preferably less than 20 parts by mass. (Ester-based plasticizer)

[0141] Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), bis(2-ethylhexyl) azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), and the like. Ester-based plasticizers can be used alone, or two or more can be used in combination. (Plasticizing agent content)

[0142] The content of a plasticizing agent based on 100 parts by mass of the rubber component is, from the perspective of wet adhesion performance, preferably greater than 5 parts by mass, more preferably greater than 10 parts by mass, and even more preferably greater than 15 parts by mass. Furthermore, from the perspective of processability, it is preferably less than 120 parts by mass, more preferably less than 80 parts by mass, and even more preferably less than 60 parts by mass. (Other connecting means)

[0143] The rubber composition according to the present invention may, in addition to the components described above, suitably comprise bonding agents that are conventionally and commonly used in the tire industry, for example processing aids, zinc oxide, stearic acid, wax, an antioxidant, a vulcanizing agent, a vulcanization accelerator and the like. (Processing aids)

[0144] Examples of processing aids include, for example, a fatty acid metal salt, a fatty acid amide, an amide ester, a silicon dioxide surface activator, a fatty acid ester, a mixture of a fatty acid metal salt and an amide ester, a mixture of a fatty acid metal salt and a fatty acid amide, and the like. Processing aids can be used alone, or two or more can be used in combination. Examples of processing aids that can be used include those commercially available from Schill+Seilacher GmbH, Performance Additives, etc.

[0145] The amount of processing aids, when combined, based on 100 parts by mass of the rubber component, is preferably greater than 0.5 parts by mass, more preferably greater than 1 part by mass, and still more preferably greater than 1.5 parts by mass, in order to demonstrate an effect of improving processability. Furthermore, in order to improve abrasion resistance and fracture toughness, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and still more preferably less than 5.0 parts by mass. (Zinc oxide)

[0146] The zinc oxide content, when combined, based on 100 parts by mass of the rubber component, is preferably more than 0.5 parts by mass, more preferably more than 1.0 parts by mass, and even more preferably more than 1.5 parts by mass, from the point of view of processability. Furthermore, from the point of view of abrasion resistance, it is preferably less than 10 parts by mass, more preferably less than 7 parts by mass, and even more preferably less than 5 parts by mass. (Stearic acid)

[0147] The stearic acid content, when combined, based on 100 parts by mass of the rubber component, is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more, from the point of view of processability. Furthermore, from the point of view of vulcanization rate, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less. (Wax)

[0148] The wax content, when combined, based on 100 parts by mass of the rubber component, is preferably more than 0.5 parts by mass, more preferably more than 1.0 parts by mass, and even more preferably more than 1.3 parts by mass, from the perspective of improving the weather resistance of the rubber. Furthermore, from the perspective of preventing the whitening of a tire due to blooming, it is preferably less than 10 parts by mass, more preferably less than 7.0 parts by mass, and even more preferably less than 5.0 parts by mass. (Antioxidants)

[0149] Examples of the antioxidant include, but are not particularly limited to, for example, compounds based on amines, quinolines, quinones, phenols and imidazoles, a carbamic acid metal salt and the like, preferably antioxidants based on phenylenediamines, such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine and the like, and antioxidants based on quinoline, such as 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline and the like. The antioxidant can be used alone, or two or more of them can be used in combination.

[0150] The content of the antioxidant, when combined, based on 100 parts by mass of the rubber component, is preferably greater than 0.5 parts by mass, more preferably greater than 1.0 parts by mass, and still more preferably greater than 1.5 parts by mass, with regard to the ozone crack resistance of the rubber. Furthermore, with regard to abrasion resistance and wet adhesion performance, it is preferably less than 10 parts by mass, more preferably less than 7 parts by mass, and still more preferably less than 5 parts by mass. (Vulcanizing agent)

[0151] Sulfur is suitable for use as a vulcanizing agent. Suitable forms of sulfur include powdered sulfur, oil-processing sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and the like. The vulcanizing agent can be used alone, or two or more can be used in combination.

[0152] When combined as a vulcanizing agent, the sulfur content, based on 100 parts by mass of the rubber component, is preferably greater than 0.1 parts by mass, more preferably greater than 0.3 parts by mass, and even more preferably greater than 0.5 parts by mass, to ensure a sufficient vulcanization reaction. Furthermore, to prevent deterioration, it is preferably less than 5.0 parts by mass, more preferably less than 4.0 parts by mass, and even more preferably less than 3.0 parts by mass. Additionally, when an oil-based sulfur is used as the vulcanizing agent, the content of the vulcanizing agent should be the total content of pure sulfur contained in the oil-based sulfur.

[0153] Examples of vulcanizing agents other than sulfur include, for example, an alkylphenol-sulfur chloride condensate, sodium hexamethylene 1,6-bisthiosulfate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, and the like. These alternative vulcanizing agents include those commercially available from Taoka Chemical Co., Ltd., LANXESS, Flexsys, etc. (Vulcanization accelerator)

[0154] Examples of vulcanization accelerators include those based on sulfenamides, thiazoles, thiurams, thioureas, guanidines, dithiocarbamic acid, aldehyde-amines, aldehydes-ammonia, imidazolines, xantah, and the like. A vulcanization accelerator can be used alone, or two or more can be used in combination.

[0155] This includes one or more vulcanization accelerators selected from the group consisting of sulfenamide-based, guanidine-based and thiazole-based vulcanization accelerators, preferably combined, and the vulcanization accelerator further preferably consists of a sulfenamide-based vulcanization accelerator and a guanidine-based vulcanization accelerator.

[0156] Examples of sulfenamide-based vulcanization accelerators include, for example, N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), and the like. Of these, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) is preferred.

[0157] Examples of guanidine-based vulcanization accelerators include, for example, 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatechol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, and the like. Among these, 1,3-diphenylguanidine (DPG) is preferred.

[0158] Examples of thiazole-based vulcanization accelerators include, for example, 2-mercaptobenzothiazole, a cyclohexylamine salt of 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and the like. Among these, 2-mercaptobenzothiazole is preferred.

[0159] The vulcanization accelerator content, when combined, based on 100 parts by mass of the rubber component, is preferably greater than 1 part by mass, more preferably greater than 1.5 parts by mass, and still more preferably greater than 2 parts by mass. Furthermore, the vulcanization accelerator content, based on 100 parts by mass of the rubber component, is preferably less than 8 parts by mass, more preferably less than 7 parts by mass, and still more preferably less than 6 parts by mass. When the vulcanization accelerator content is within the ranges described above, fracture toughness and elongation tend to be ensured. [Production]

[0160] Each of the rubber compositions according to the present invention can be produced by a known method. For example, it can be produced by kneading each of the components described above using a rubber kneading device, such as an open roller, a closed-type kneader (Bunbury mixer, kneader, etc.), and the like.

[0161] The kneading step includes, for example, a basic kneading step involving the kneading of bonding agents and additives other than vulcanizing agents and vulcanization accelerators, and a final kneading step (F-kneading) involving the addition of vulcanizing agents and vulcanization accelerators to the kneaded product obtained by the basic kneading step, and the kneading of this product. Furthermore, the basic kneading step can be subdivided into several steps if desired.

[0162] A kneading condition is not particularly restricted. Examples of kneading include, for instance, a process of kneading at a discharge temperature of 150 to 170 °C for 3 to 10 minutes for the basic kneading step, and a process of kneading at 70 to 110 °C for 1 to 5 minutes for the final kneading step.

[0163] The pneumatic tire of the present invention can be manufactured by a conventional method using the unvulcanized rubber composition described above. That is, the pneumatic tire of the present invention can be manufactured by extruding an unvulcanized rubber composition into a mold of a predetermined tread shape using an extruder equipped with a die of a predetermined shape, assembling it with other tire elements on a tire forming machine, and forming it by a conventional method to create an unvulcanized tire, followed by heating and pressurizing this unvulcanized tire in a vulcanizing machine. The vulcanization conditions are not particularly restricted. Examples of vulcanization include, for instance, a process of vulcanizing at 150 to 200 °C for 10 to 30 minutes. [Application]

[0164] The pneumatic tire of the present invention can be used for any application, for example, as a tire for a passenger car, a tire for a large passenger car, a tire for a light truck, a tire for a large SUV, a racing tire, or a motorcycle tire. Among these, a tire for a passenger car and a tire for a light truck are preferred. Here, the tire for a passenger car is a tire mounted on a four-wheeled vehicle and refers to one with a maximum load capacity of 1,000 kg or less, while the tire for a light truck refers to one with a maximum load capacity of less than 1,400 kg.

[0165] Furthermore, the tire of the present invention can be used as a summer tire, a winter tire, or a studless tire for each of the tires described above. Among these, a winter tire and a studless tire, which are used at low temperatures, are preferred. EXAMPLES

[0166] Although the present invention is described on the basis of examples, it is not limited to the examples. [Various chemicals]

[0167] Various chemicals used in examples and comparisons are shown collectively below. NR: TSR20 SBR1: SLR6430, manufactured by Trinseo PLC (S-SBR, styrene content: 40 wt%, vinyl binding amount: 24 mol%, Tg: -30 °C, Mw: 1,010,000, oil-extended product comprising 37.5 wt parts of oil content based on 100 wt parts of rubber component) SBR2: Styrene-butadiene rubber, synthesized in production example 1 below (modified S-SBR, styrene content: 20 wt%, vinyl content: 20 mol%, Tg: - 60 °C, Mw: 800,000) SBR3: Styrene-butadiene rubber, synthesized in production example 2 below (modified S-SBR, styrene content: 15 wt%, vinyl content: 30 mol%, Tg: - 60 °C, Mw: 800,000) BR1: Ubepol BR (registered trademark) 150B, manufactured by Ube Industries, Ltd. (Vinyl content: 1.5 mol%, cis content: 97 mol%, Tg: -108 °C, Mw: 440,000) BR2: ASAPRENE N103, manufactured by Asahi Kasei Corporation (modified BR, the end of which is modified with a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane and its oligomer component, vinyl content: 12 mol%, cis content: 36 wt%, Tg: -90 °C, Mw: 550,000) CB (soot): Show Black N134, manufactured by Cabot Japan KK (N2SA: 148 m 2 / g, average primary particle size: 18 nm) Silicon dioxide: Ultrasil (registered trademark) VN3, manufactured by Evonik Degussa GmbH (N2SA: 175 m 2 / g, average primary particle size: 18 nm) Coupling agent (silane coupling agent): Si266, manufactured by Evonik Degussa GmbH (Bis(3-triethoxysilylpropyl)disulfide) Oil: VivaTec 500, manufactured by H&R Group (TDAE oil) Hydrocarbon resin 1: Sylvatraxx 4401, manufactured by Kraton Corporation (aromatic vinyl-based resin (copolymer of styrene and α-methylstyrene), Mw: 700, softening point: 85 °C, Tg: 34 °C) Hydrocarbon resin 2: PR395, manufactured by Exxon Mobil Corporation (resin based on C5 / C9, Mw: 880, softening point 117.8 °C, Tg: 68 °C) Zinc oxide: Zinc oxide No. 2, manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Stearic acid “CAMELLIA”, manufactured by NOF CORPORATION Wax: SUNNOC N, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant 1: Antigen 6C, manufactured by Sumitomo Chemical Co., Ltd. (6PPD, N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine) Antioxidant 2: Nocrac 224, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (TMQ, 2,2,4-Trimethyl-1,2-dihydroquinoline polymer) Sulfur: Powdered sulfur, manufactured by Karuizawa Sulfur Co, Ltd. Vulcanization accelerator 1: Nocceler CZ, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (CBS, N-Cyclohexyl-2-benzothiazolylsulfenamide) Vulcanization accelerator 2: Nocceler D, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (DPG, 1,3-Diphenylguanidine) [Production Examples] Production Example 1: Synthesis of SBR2

[0168] A ratio of styrene to 1,3-butadiene is adjusted to achieve a styrene content of 20 wt% in the target product. Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are loaded 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 is carried out under adiabatic conditions, and when a polymerization conversion rate of 99% is reached, 1,3-butadiene is added. Following further polymerization, methyltriethoxysilane is added as a modifier to perform a modification reaction. After completion of the reaction, 2,6-ditert-butyl p-cresol is added. The mixture is then subjected to solvent removal by steam stripping and dried by a heat roller at a temperature adjusted to 110 °C to obtain SBR2. Production example 2: Synthesis of SBR3

[0169] A ratio of styrene to 1,3-butadiene is adjusted to achieve a styrene content of 15 wt% in the target product. Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are loaded 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 is carried out under adiabatic conditions, and when a polymerization conversion rate of 99% is reached, 1,3-butadiene is added. Following further polymerization, 3-[bis-(trimethylsilyl)amino]propyltriethoxysilane is added as a modifier to perform a modification reaction. After completion of the reaction, 2,6-ditert-butyl p-cresol is added. Next, the mixture is subjected to solvent removal by steam stripping and dried by a heat roller whose temperature is adjusted to 110 °C to obtain SBR3. [Examples and comparisons]

[0170] According to the compound formulations shown in each table, using a closed 1.7-liter Banbury mixer, all chemicals other than sulfur and vulcanization accelerator are kneaded for 1 to 10 minutes until a discharge temperature of 150°C to 160°C is reached to obtain a kneaded product. Next, using an open twin-screw mixer, sulfur and vulcanization accelerator are added to the resulting kneaded product, and the mixture is kneaded for 4 minutes until the temperature reaches 105°C to obtain an unvulcanized rubber composition.The resulting unvulcanized rubber composition is formed into a predetermined tread shape according to each table and joined with other tire elements, producing an unvulcanized tire, followed by press vulcanization under a temperature of 170 °C for 12 minutes to obtain each test tire (Tire 1: 225 / 60R16 98H, Tire 2: 275 / 55R20 117T XL).

[0171] The tread surface of each test tire has at least major circumferential grooves and lateral grooves. There are three major circumferential grooves, one of which runs along the tire's centerline, and the remaining two are located at evenly spaced positions on the outer edge of the tire in the direction of its width. Furthermore, the tread surface has no small holes, narrow circumferential grooves, or widely spaced circumferential grooves. <bewertung>

[0172] For each test tire, results measured using the following procedure are also described in the corresponding columns of the tables below. (Survey ratio)

[0173] For each test tire, a total ground contact area and an effective ground contact area, as defined above, are determined by calculating a lift ratio (%). (Wet grip performance at high speed)

[0174] Each test tire is mounted on all wheels of a vehicle (Tire 1: domestic FF vehicle, 2000 cc engine; Tire 2: domestic 4WD vehicle, 3000 cc engine) driven at 100 km / h on a wet asphalt test track. Grip performance during driving is rated by 20 test drivers on a scale of 1 to 5, with an overall score calculated. The results are presented as indicators, with 100 as the reference point. The results show that the higher the indicator, the better the steering stability during driving and the better the wet grip performance at high speed. (Abrasion resistance at low temperatures)

[0175] Each test tire is mounted on all wheels of a vehicle (Tire 1: domestic FF vehicle, 2000 cc engine capacity; Tire 2: domestic 4WD vehicle, 3000 cc engine capacity) driven on an asphalt road surface on a test track for 20,000 km at an ambient air temperature of 10°C or below. The amount of tread thickness reduction is measured from the start of driving. The results are presented as indicators, with a reference value of 100. The results show that the higher the indicator, the lower the reduction and the better the low-temperature wear resistance. Table 1 (Tire 1: 225 / 60R16 98H) Example 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9 Compound quantity (mass fraction) NR - - - - - - - - 10 SBR1 - - - - - - - - - SBR2 45 45 45 45 - 45 45 35 35 SBR3 - - - - 45 - - - - BR1 55 55 55 - 55 55 55 65 55 BR2 - - - 55 - - - - - (Expanding oil) (0) (0) (0) (0) (0) (0) (0) (0) (0) CB 5 5 5 5 5 5 5 5 5 silicon dioxide 80 80 80 80 80 100 80 100 80 Clutching device 6, 4 6, 4 6, 4 6, 4 6, 4 8 6, 4 8 6, 4 Öl 10 - - - - 25 10 15 - Hydrocarbon resin 1 20 30 - 30 30 20 20 30 30 Hydrocarbon resin 2 - - 30 - - - - - - zinc oxide 3 3 3 3 3 3 3 3 3 Stearic acid 3 3 3 3 3 3 3 3 3 (Continued on the next page) Example 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9 wax 1,5 1,5 1,5 1,5 1,5 1,5 1,5 1,5 1,5 Antioxidant 1 2 2 2 2 2 2 2 2 2 Antioxidants 2 1 1 1 1 1 1 1 1 1 sulfur 1,5 1,5 1,5 1,5 1,5 1,5 1,5 1,5 1,5 Vulcanization accelerator 1 2 2 2 2 2 2 2 2 2 Vulcanization accelerator 2 1,8 1,8 1,8 1,8 1,8 2,2 1,8 2,2 1,8 Salary to the works council (mass %) (A BR ) 55 55 55 55 55 55 55 65 55 Total styrene content (mass %) (A sty ) 9,0 9,0 9,0 9,0 6,8 9,0 9,0 7,0 7,0 Survey ratio (%) (L) 60 60 60 60 60 60 65 65 60 Hydrocarbon resin content (mass %) 8 13 13 13 13 7 8 11 13 Tg of rubber composition (°C) -43 -38 -38 -34 -38 -43 -43 -41 -35 Inequality (1) A BR × L 3300 3300 3300 3300 3300 3300 3575 4225 3300 Inequality (2) (A BR / A sty ) × L 367 367 367 367 489 367 397 604 471 Wet adhesion performance at high speed, abrasion resistance at low temperature, overall performance 108 110 112 114 112 116 108 118 106 Abrasion resistance at low temperature 112 112 112 110 112 112 114 117 112 Total performance 220 222 224 224 224 228 222 235 218 (Continued on the next page) Comparative example 1-1 1-2 1-3 1-4 1-5 1-6 1-7 Compound quantity (mass fraction) NR - - - - - - 45 SBR1 96,25 96,25 - - 72,88 - - SBR2 - - 70 70 - 45 - SBR3 - - - - - - - BR1 30 30 30 30 47 55 55 BR2 - - - - - - - (Expanding oil) (26,25) (26,25) (0) (0) (19,88) (0) (0) CB 5 5 5 5 5 55 5 silicon dioxide 80 80 80 80 80 30 80 Clutching device 6, 4 6, 4 6, 4 6, 4 6, 4 2, 4 6, 4 Öl 10 10 30 20 30 30 10 Hydrocarbon resin 1 - - - 10 - - - Hydrocarbon resin 2 - - - - - - - zinc oxide 3 3 3 3 3 3 3 Stearic acid 3 3 3 3 3 3 3 wax 1,5 1,5 1,5 1,5 1,5 1,5 1,5 Antioxidant 1 2 2 2 2 2 2 2 Antioxidants 2 1 1 1 1 1 1 1 (Continued on the next page) Comparative example 1-1 1-2 1-3 1-4 1-5 1-6 1-7 sulfur 1,5 1,5 1,5 1,5 1,5 1,5 1,5 Vulcanization accelerator 1 2 2 2 2 2 2 2 Vulcanization accelerator 2 1,8 1,8 1,8 1,8 1,8 1,8 1,8 Salary to the works council (mass %) (A BR ) 30 30 30 30 47 55 55 Total styrene content (mass %) (A sty ) 28,0 28,0 14,0 14,0 21,2 9,0 - Survey ratio (%) (L) 57 60 57 57 65 60 60 Hydrocarbon resin content (mass %) 0 0 0 4 0 0 0 Tg of rubber composition (°C) -23 -23 -47 -43 -28 -53 -48 Inequality (1) A BR × L 1710 1800 1710 1710 3055 3300 3300 Inequality (2) (A BR / A sty ) × L 61 64 122 122 144 367 - Wet grip performance at high speed 100 100 102 104 102 90 86 Abrasion resistance at low temperature 100 102 103 103 105 108 109 Total performance 200 202 205 207 207 198 195 Table 2 (Tire 2: 275 / 55R20 117T XL) Example 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 2-9 Compound quantity (mass fraction) NR - - - - - - - - 10 SBR1 - - - - - - - - - SBR2 45 45 45 45 - 45 45 35 35 SBR3 - - - - 45 - - - - BR1 55 55 55 - 55 55 55 65 55 BR2 - - - 55 - - - - - (Expanding oil) (0) (0) (0) (0) (0) (0) (0) (0) (0) CB 5 5 5 5 5 5 5 5 5 silicon dioxide 80 80 80 80 80 100 80 100 80 Clutching device 6,4 6,4 6,4 6,4 6,4 8 6,4 8 6,4 Öl 10 - - - - 25 10 15 - Hydrocarbon resin 1 20 30 - 30 30 20 20 30 30 Hydrocarbon resin 2 - - 30 - - - - - - zinc oxide 3 3 3 3 3 3 3 3 3 Stearic acid 3 3 3 3 3 3 3 3 3 (Continued on the next page) Example 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 2-9 wax 1,5 1,5 1,5 1,5 1,5 1,5 1,5 1,5 1,5 Antioxidant 1 2 2 2 2 2 2 2 2 2 Antioxidants 2 1 1 1 1 1 1 1 1 1 sulfur 1,5 1,5 1,5 1,5 1,5 1,5 1,5 1,5 1,5 Vulcanization accelerator 1 2 2 2 2 2 2 2 2 2 Vulcanization accelerator 2 1,8 1,8 1,8 1,8 1,8 2,2 1,8 2,2 1,8 Salary to the works council (mass %) (A BR ) 55 55 55 55 55 55 55 65 55 Total styrene content (mass %) (A sty ) 9,0 9,0 9,0 9,0 6,8 9,0 9,0 7,0 7,0 Survey ratio (%) (L) 60 60 60 60 60 60 65 65 60 Hydrocarbon resin content (mass %) 8 13 13 13 13 7 8 11 13 Tg of rubber composition (°C) -43 -38 -38 -34 -38 -43 -43 -41 -35 Inequality (1) A BR × L 3300 3300 3300 3300 3300 3300 3575 4225 3300 Inequality (2) (A BR / A sty ) × L 367 367 367 367 489 367 397 604 471 Wet grip performance at high speed 108 110 112 114 112 116 108 118 106 Abrasion resistance at low temperature 112 112 112 110 112 112 114 117 112 Total performance 220 222 224 224 224 228 222 235 218 (Continued on the next page) Comparative example 2-1 2-2 2-3 2-4 2-5 2-6 2-7 Compound quantity (mass fraction) NR - - - - - - 45 SBR1 96,25 96,25 - - 72,88 - - SBR2 - - 70 70 - 45 - SBR3 - - - - - - - BR1 30 30 30 30 47 55 55 BR2 - - - - - - - (Expanding oil) (26,25) (26,25) (0) (0) (19, 88) (0) (0) CB 5 5 5 5 5 55 5 silicon dioxide 80 80 80 80 80 30 80 Clutching device 6, 4 6, 4 6, 4 6, 4 6, 4 2, 4 6, 4 Öl 10 10 30 20 30 30 10 Hydrocarbon resin 1 - - - 10 - - - Hydrocarbon resin 2 - - - - - - - zinc oxide 3 3 3 3 3 3 3 Stearic acid 3 3 3 3 3 3 3 wax 1,5 1,5 1,5 1,5 1,5 1,5 1,5 Antioxidant 1 2 2 2 2 2 2 2 Antioxidants 2 1 1 1 1 1 1 1 (Continued on the next page) Comparative example 2-1 2-2 2-3 2-4 2-5 2-6 2-7 sulfur 1,5 1,5 1,5 1,5 1,5 1,5 1,5 Vulcanization accelerator 1 2 2 2 2 2 2 2 Vulcanization accelerator 2 1,8 1,8 1,8 1,8 1,8 1,8 1,8 Salary to the works council (mass %) (A BR ) 30 30 30 30 47 55 55 Total styrene content (mass %) (A sty ) 28,0 28,0 14,0 14,0 21,2 9,0 - Survey ratio (%) (L) 57 60 57 57 65 60 60 Hydrocarbon resin content (mass %) 0 0 0 4 0 0 0 Tg of rubber composition (°C) -23 -23 -47 -43 -28 -53 -48 Inequality (1) A BR × L 1710 1800 1710 1710 3055 3300 3300 Inequality (2) (A BR / A sty ) × L 61 64 122 122 144 367 - Wet grip performance at high speed 100 100 102 104 102 90 86 Abrasion resistance at low temperature 100 102 103 103 105 108 109 Total performance 200 202 205 207 207 198 195 [Versions]

[0176] Preferred embodiments are shown below.

[0177] [1] A pneumatic tire comprising a tread section, wherein the tread section is composed of a rubber composition comprising 50 parts by mass or more, preferably 70 parts by mass or more, further preferably 80 parts by mass or more and even more preferably 90 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, wherein the total amount of styrene in the rubber component is 25% by mass or less, and where A BR A represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: ABR×L>3000.

[0178] [2] The pneumatic tire of [1], wherein, if A STY represents the total amount of styrene in mass %, A BR , L and A STY satisfy the following inequality: (ABR / ASTY)×L>130, where the right-hand side of inequality (2) is preferably 200, further preferably 300, even more preferably 360, even more preferably 450, even more preferably 550 and even more preferably 600.

[0179] [3] The pneumatic tire of [1] or [2], wherein the rubber composition comprises at least one type of hydrocarbon resin and wherein the hydrocarbon resin content in the rubber composition is 5 wt% or more, preferably more than 6 wt%, further preferably more than 7 wt%, even more preferably more than 10 wt% and even more preferably more than 12 wt%.

[0180] [4] The pneumatic tire of one of [1] to [3], wherein the silicon dioxide content based on 100 parts by mass of the rubber component is more than 70 parts by mass, preferably 80 parts by mass or more, further preferably more than 90 parts by mass and even more preferably 100 parts by mass or more.

[0181] [5] The pneumatic tire of one of [1] to [4], wherein a glass transition temperature of the rubber composition is lower than -30 °C, preferably lower than -33 °C, more preferably lower than -37 °C, more preferably lower than -40 °C and more preferably lower than -42 °C.

[0182] [6] The pneumatic tire of one of [1] to [5], where the right side of the inequality (1) is 3250.

[0183] [7] The pneumatic tire of one of [1] to [5], wherein the right-hand side of inequality (1) is 3500, preferably 3750 and further preferably 4000.

[0184] [8] The pneumatic tire of one of [1] to [7], wherein the content A BR the butadiene rubber content in the rubber component is less than 70 wt%, preferably less than 65 wt% and further preferably less than 60 wt%.

[0185] [9] The pneumatic tire of one of [1] to [8], wherein a glass transition temperature of the styrene-butadiene rubber is lower than -30 °C, preferably lower than -40 °C, more preferably lower than -50 °C and still more preferably lower than -55 °C.

[0186]

[10] The pneumatic tire of one of [1] to [9], wherein the tread surface has two or more main circumferential grooves extending in a tire circumferential direction, and rib sections separated by the main circumferential grooves, and wherein, if a pair of rib sections located on an outermost side in a tire width direction are defined as shoulder rib sections below the rib sections, the shoulder rib sections have one or more small holes, each with an opening area greater than 0.1 mm 2 and smaller than 15 mm 2 , preferably larger than 0.5 mm 2 and smaller than 10 mm 2 , preferably larger than 0.5 mm 2 and smaller than 7.0 mm 2 and even more preferably larger than 1.0 mm 2 and smaller than 5.0 mm 2 exhibit, exhibit.

[0187]

[11] The pneumatic tire of one of [1] to

[10] , wherein the tread surface has two or more main circumferential grooves extending in a tire circumferential direction and rib sections separated by the main circumferential grooves, and where, if a pair of rib sections located on an outermost side in a tire width direction are defined as shoulder rib sections among the rib sections, the shoulder rib sections shall have at least one or more narrow circumferential grooves.

[0188]

[12] The pneumatic tire of one of [1] to

[11] , wherein the tread surface has widened circumferential grooves, the groove width of which widens towards an inside in a tire radial direction.

[0189]

[13] The pneumatic tire of

[12] , wherein the widened circumferential groove is located on a rib section that is on a tire centerline or, if a main circumferential groove is located on the tire centerline, on a rib section that is closest to the tire centerline. REFERENCE MARK LIST CL. Tire center line Te. Tread end W Tire width direction C Tire circumference direction 1 tire 2 Main circumferential groove 3 Bridge section 4 small holes 5 narrow circumferential grooves 6 widened circumferential groove< / bewertung> < / gehalt> < / erweichungspunkt> < / plastifizierungsmittel> < / kautschukkomponente>

Claims

[1] Pneumatic tire, which includes a tread section, wherein the tread section is composed of a rubber composition comprising 50 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, where the total styrene content in the rubber component is 25% by mass or less, where A BR A represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: ABR×L>3000, where the carbon black content is less than 30 parts by mass, based on 100 parts by mass of the rubber component, and where the glass transition temperature of the rubber composition is lower than -30 °C. [2] Pneumatic tire, which includes a tread section, wherein the tread section is composed of a rubber composition comprising 70 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, where the total styrene content in the rubber component is 25% by mass or less, where A BR A represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: ABR×L>3000, and where the glass transition temperature of the rubber composition is lower than -30 °C. [3] Pneumatic tire, which includes a tread section, wherein the tread section is composed of a rubber composition comprising 50 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, where the total styrene content in the rubber component is less than 10% by mass, and where A BR A represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: ABR×L>3000, and where the glass transition temperature of the rubber composition is lower than -30 °C. [4] Pneumatic tire, which includes a tread section, wherein the tread section is composed of a rubber composition comprising 50 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, where the total styrene content in the rubber component is 25% by mass or less, where A BR A represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: ABR×L>3000, where the survey ratio L is 61% or more, and where the glass transition temperature of the rubber composition is lower than -30 °C. [5] Pneumatic tire, which includes a tread section, wherein the tread section is composed of a rubber composition comprising 50 parts by mass or more of silicon dioxide based on 100 parts by mass of a rubber component, wherein the rubber component comprises more than 50 wt% of a butadiene rubber and a styrene-butadiene rubber, where the total styrene content in the rubber component is 25% by mass or less, where A BR A represents a mass % content of butadiene rubber in the rubber component, and L represents a percentage elevation of a tread surface of the tread section. BR and L satisfy the following inequality: ABR×L>3000, and where the glass transition temperature of the rubber composition is lower than -42 °C. [6] Pneumatic tires according to any one of claims 1 to 5, wherein, if A STY represents the total amount of styrene in mass %, A BR , L and A STY satisfy the following inequality: (ABR / ASTY)×L>130. [7] Pneumatic tires according to any one of claims 1 to 6, wherein the rubber composition comprises at least one type of hydrocarbon resin, and where the hydrocarbon resin content in the rubber composition is 5% by mass or more. [8] Pneumatic tire according to any one of claims 1 to 7, wherein the silicon dioxide content is 100 parts by mass or more, based on 100 parts by mass of the rubber component. [9] Pneumatic tire according to any one of claims 1 to 8, wherein the right-hand side of the inequality (1) is 3250. [10] Pneumatic tire according to any one of claims 1 to 9, wherein the right-hand side of the inequality (1) is 3500. [11] Pneumatic tire according to any one of claims 1 to 10, wherein the content A BR the butadiene rubber content in the rubber component is less than 70% by mass. [12] Pneumatic tires according to any one of claims 1 to 11, wherein the glass transition temperature of the styrene-butadiene rubber is lower than -30 °C. [13] Pneumatic tires according to any one of claims 1 to 12, wherein the tread surface has two or more main circumferential grooves extending in a tire circumferential direction, and rib sections separated by the main circumferential grooves, and wherein, if a pair of rib sections located on an outermost side in a tire width direction are defined as shoulder rib sections below the rib sections, the shoulder rib sections have one or more small holes, each with an opening area greater than 0.1 mm 2 and smaller than 15 mm 2 exhibit, exhibit. [14] Pneumatic tires according to any one of claims 1 to 13, wherein the tread surface has two or more main circumferential grooves extending in a tire circumferential direction, and rib sections separated by the main circumferential grooves, and where, if a pair of rib sections located on an outermost side in a tire width direction are defined as shoulder rib sections among the rib sections, the shoulder rib sections shall have at least one or more narrow circumferential grooves. [15] Pneumatic tire according to any one of claims 1 to 14, wherein the tread surface has widened circumferential grooves, the groove width of which widens towards an inside in a tire radial direction. [16] Pneumatic tire according to claim 15, wherein the widened circumferential groove is located on a rib section that is on a tire centerline or, if a main circumferential groove is located on the tire centerline, on a rib section that is closest to the tire centerline.

Images