pneumatic tires

Abstract

The present invention provides a pneumatic tire having excellent durability when traveling at high speeds. A pneumatic tire includes a side portion and a belt layer. Monofilament cords are used as reinforcing cords in the belt layer, and in a tire-radial-direction cross-section of the belt layer, an array count e of monofilament cords per 5 cm in a tire width direction (cords / 5 cm) and a tire cross-sectional width Wt (mm) when the tire is assembled to a normal rim and an inner pressure is set to 250 kPa satisfy the following (Expression 1) and (Expression 2).　(Expression 1): e / (139.5 - 0.3 Wt) > 1 (Expression 2): e / (191.5 - 0.3 Wt) < 1

Description

Technical Field

[0001] The present disclosure relates to pneumatic tires, and more particularly to pneumatic tires provided with a belt layer.

Background Art

[0002] In recent years, from the viewpoints of growing interest in environmental issues and economy, there has been an increasing demand for reducing fuel consumption of automobiles, and there is also a strong demand for improving the fuel efficiency of pneumatic tires (hereinafter also simply referred to as "tires") mounted on automobiles.

[0003] [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​However, with the recent development of highways, the opportunities for high-speed and long-distance travel have increased exponentially. Under such circumstances, the tires manufactured by the above-mentioned conventional technologies are not yet sufficient in terms of durability during high-speed driving, and further improvement is required.

[0007] Therefore, an object of the present disclosure is to provide a pneumatic tire having excellent durability during high-speed driving.

Means for Solving the Problems

[0008] The present inventors have intensively studied to solve the above problems, and have found that the above problems can be solved by the disclosure described below, and have completed the present disclosure.

[0009] The present disclosure is a pneumatic tire including a side portion and a belt layer, wherein the belt layer uses a monofilament cord as a reinforcing cord, in the tire radial cross-section of the belt layer, the number of arranged monofilament cords e (number / 5 cm) per 5 cm in the tire width direction and the tire cross-sectional width Wt (mm) when incorporated into a normal rim and the internal pressure is 250 kPa satisfy the following (Equation 1) to (Equation 3) And Furthermore, the complex modulus E of the sidewall rubber composition in the side portion was measured under the following conditions: temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, deformation mode: stretching. * The pressure (MPa) and the height T (mm) of the side portion satisfy the following equation (Equation 4): which is a pneumatic tire characterized by the above. e / (139.5 - 0.3Wt) > 1 ····· (Equation 1) e / (191.5 - 0.3Wt) < 1 ····· (Equation 2) e / (110.84 - 0.1667Wt) >1 ····· (Equation 3) (E * / T)×100≦3.0 (Formula 4)

Advantages of the Invention

[0010] According to the present disclosure, a pneumatic tire having excellent durability during high-speed driving can be provided. [Modes for carrying out the invention]

[0011] [1] Characteristics of the tires relating to this disclosure First, we will describe the features of the tire related to this disclosure.

[0012] 1. Overview The tire according to this disclosure is a pneumatic tire having a side section and a belt layer, and monofilament cords are used as reinforcing cords in the belt layer. The number of monofilament cords arranged per 5 cm in the tire width direction in the radial cross section of the belt layer (hereinafter also referred to as "ends") e (corresponds / 5 cm) and the tire cross section width Wt (mm) when assembled on a regular rim and with an internal pressure of 250 kPa are given by e / (139.5 - 0.3 Wt) > 1 (Equation 1) and e / (191.5 - 0.3 Wt) < 1 (Equation 2), and e / (110.84 - 0.1667 Wt). >1 (Equation 3) is satisfied Furthermore, the complex modulus E of the sidewall rubber composition in the side portion was measured under the following conditions: temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, deformation mode: stretching. * (MPa) and the height T (mm) of the side section are equal to (E * / T) × 100 ≤ 3.0 (Equation 4) Yes, they are.

[0013] As a result of these characteristics, it is possible to provide a pneumatic tire with excellent durability at high speeds, as will be described later.

[0014] In the above description, the tire section width Wt refers to the width obtained by subtracting the patterns and lettering on the side of the tire from the straight-line distance between the sidewalls (total width of the tire), which includes all patterns and lettering on the side of the tire, when the tire is mounted on a regular rim, the internal pressure is set to 250 kPa, and there is no load.

[0015] Furthermore, the term "standard rim" refers to the rim specified for each tire within the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," in the case of ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and in the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." In the case of tires not specified in the standard, it refers to the rim with the smallest diameter and the narrowest rim width among rims that can be mounted on and can maintain internal pressure, i.e., rims that do not cause air leakage from between the rim and tire.

[0016] Furthermore, the number of monofilament cords per 5 cm in the tire width direction (ends) e (cords / 5 cm) can be expressed by converting the number of monofilament cords measured in the range of ±2.5 to 5.0 cm with respect to the equatorial plane of the tire cross-section to a value per 5 cm. Specifically, the number of cords e (cords / 5 cm) is preferably 55 cords / 5 cm or more, more preferably 65 cords / 5 cm or more, even more preferably 68 cords / 5 cm or more, even more preferably 75 cords / 5 cm or more, and even more preferably greater than 80 cords / 5 cm. On the other hand, it is preferably less than 150 cords / 5 cm, more preferably 110 cords / 5 cm or less, even more preferably 95 cords / 5 cm or less, and even more preferably 85 cords / 5 cm or less.

[0017] Furthermore, the outer diameter d (mm) of the monofilament cord is not particularly limited, but is preferably 0.1 mm or more, and more preferably 0.2 mm or more. On the other hand, it is preferably 0.5 mm or less, and more preferably 0.4 mm or less. It is particularly preferably 0.3 mm.

[0018] In the above description, "cord outer diameter" refers to the cord outer diameter of the monofilament cords in the belt layer in the tire cross-section, in a direction parallel to the tire width direction. The average value of the cord outer diameter in the direction parallel to the tire width direction measured when calculating the above end e (cords / 5cm) can be used.

[0019] 2. Mechanism of effect in the tire relating to this disclosure The mechanism by which the tire described herein exhibits its effects, that is, the mechanism by which a pneumatic tire with superior durability at high speeds can be provided, is presumed to be as follows.

[0020] To reduce rolling resistance, reducing tire weight is a possible solution, and one specific method for achieving this is to use monofilament cords for the reinforcing cords in the belt layer.

[0021] However, monofilament cords are not twisted and cannot bend. Therefore, if monofilament cords are densely arranged in a tire with a wide tread, the rigidity of the tread ring may become too high. When such a tire goes over a bump at high speed, significant deformation may occur in the sidewall, damaging the tire and potentially reducing its durability at high speeds. At the same time, such tires may also transmit road surface irregularities more easily, potentially leading to a deterioration in ride comfort.

[0022] Therefore, one possible solution is to make the arrangement of monofilament cords sparser according to the tread width. By making the arrangement of monofilament cords sparser, the rigidity of the tread ring will not become too high, and impact will be more easily absorbed in the tread area. This is thought to reduce deformation that occurs in the side, suppress the occurrence of impact damage in the side at high speeds, and improve the durability of the tire.

[0023] However, if the arrangement of monofilament cords becomes too sparse, the restraining force of the tread by the belt layer decreases, which can lead to greater deformation of the tread during high-speed driving and potentially cause damage to the tread. Therefore, as the width of the tread increases, increasing the number of monofilament cords in the arrangement prevents it from becoming too sparse. This maintains the restraining force of the belt layer, suppresses damage to the tread, and improves durability during high-speed driving.

[0024] As stated above, the Discloser considers that the tread width, i.e., the tire section width Wt (mm), and the number of monofilament cords arranged e (cords / 5cm) are parameters related to the durability of the tire during high-speed driving. Therefore, the Discloser conducted experiments and studies to determine the favorable relationship between the number of monofilament cords arranged e (cords / 5cm) and the tread width, i.e., the tire section width Wt (mm). As a result, the Discloser found that when the above-mentioned e / (139.5-0.3Wt)>1 (Equation 1) and e / (191.5-0.3Wt)<1 (Equation 2) are satisfied, the durability during high-speed driving can be improved, and thus completed this Disclosure.

[0025] In this case, as the tire section width Wt (tread width) increases, the total number of monofilament cords arranged on the tread surface increases, so it is considered acceptable to gradually reduce the number of ends.

[0026] In addition, in the above description, the specific value of [e / (139.5-0.3Wt)] is preferably 1.01 or higher, more preferably 1.02 or higher, even more preferably 1.12 or higher, even more preferably 1.14 or higher, even more preferably 1.20 or higher, even more preferably 1.22 or higher, even more preferably 1.64 or higher, and even more preferably 1.76 or higher.

[0027] Furthermore, the specific value of [e / (191.5-0.3Wt)] is preferably 0.92 or less, more preferably 0.90 or less, even more preferably 0.67 or less, even more preferably 0.63 or less, even more preferably 0.62 or less, even more preferably 0.61 or less, even more preferably 0.59 or less, even more preferably 0.57 or less, and even more preferably 0.52 or less.

[0028] Further experiments and studies revealed that it is preferable for the tire section width Wt to ​​be between 125 mm and 300 mm, and even more preferable if, when the tire section width Wt is 215 mm or more, in addition to (Equation 1) and (Equation 2), e / (110.84-0.1667Wt)>1 (Equation 3) is also satisfied.

[0029] In addition, in the above description, the specific tire section width Wt is preferably 216 mm or more, more preferably 217 mm or more, even more preferably 218 mm or more, even more preferably 240 mm or more, even more preferably 241 mm or more, even more preferably 242 mm or more, even more preferably 285 mm or more, even more preferably 286 mm or more, and even more preferably 287 mm or more.

[0030] Specifically, the value of [e / (110.84-0.1667Wt)] is preferably 1.01, more preferably 1.03 or higher, even more preferably 1.06 or higher, even more preferably 1.14 or higher, even more preferably 1.50 or higher, and even more preferably 1.56 or higher.

[0031] [2] More preferred embodiments of the tire relating to the present disclosure The tire relating to this disclosure can achieve even greater effects by adopting the following configurations.

[0032] 1. Relationship between the complex modulus of elasticity of the sidewall rubber composition and the height of the sidewall. Further experiments and investigations by the Disclosing Company revealed that the improvement in durability during high-speed driving is related not only to the improvement of the belt layer described above, but also to the rigidity of the sidewall rubber composition.

[0033] In other words, if the rigidity of the sidewall rubber composition is high, and the height of the side section is low, stress concentration will occur in the side section when an impact is applied to the side section from the tread section, making impact failure more likely. Furthermore, the high rigidity of the sidewall rubber composition means that it cannot absorb the impact applied to the tread section like a cushion, which may lead to damage to the tread section.

[0034] Therefore, by controlling the rigidity of the sidewall rubber composition in accordance with the height of the side section, it is thought that if the side section can be made flexible, stress concentration will not occur when an input is applied to the side section, and impact absorption will also be possible, thereby suppressing the occurrence of damage to the tread section. Experiments and investigations were conducted on the relationship between the complex modulus of elasticity of the sidewall rubber composition and the height of the side section.

[0035] As a result, the complex modulus E of the sidewall rubber composition was measured under the following conditions: temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, deformation mode: stretching. * (MPa) and the height T (mm) of the side section are equal to (E * It was found that durability during high-speed driving is further improved if the condition / T) × 100 ≤ 3.0 (Equation 4) is satisfied.

[0036] Furthermore, in the above, the complex modulus E of the sidewall rubber composition * This can be measured using a viscoelasticity measuring device such as GABO's "Iplexer®," and the specific complex modulus E *For example, it is preferably 1.5 MPa or more, more preferably 2.0 MPa or more, still more preferably 2.5 MPa or more, and still more preferably 3.2 MPa or more. On the other hand, it is preferably 6.0 MPa or less, more preferably 5.0 MPa or less, still more preferably 4.1 MPa or less, and still more preferably 4.0 MPa or less.

[0037] And the height T of the side portion can be obtained by subtracting the rim diameter R (mm) from the outer diameter dt (mm) of the tire when incorporated into a standard rim and the internal pressure is 250 kPa.

[0038] In addition, as the specific height T of the side portion, it is preferably 100.0 mm or more, more preferably 128.9 mm or more, and still more preferably 150.8 mm or more.

[0039] And in the present disclosure, specific (E * / T) × 100 is preferably 2.72 or less, more preferably 2.50 or less, and still more preferably 2.48 or less.

[0040] 2. Angle of the reinforcing cord (monofilament cord) The angle formed by the reinforcing cord (monofilament cord) of the belt layer and a straight line parallel to the tire circumferential direction is preferably 10° or more, more preferably 15° or more, still more preferably 20° or more, and still more preferably 23° or more. On the other hand, it is preferably 35° or less, more preferably 33° or less, and still more preferably 30° or less.

[0041] By arranging the monofilament cord of the belt layer at such an angle, a hoop effect can be obtained, and almost the entire width of the tread portion can be firmly constrained, suppressing the deformation amount of the tread portion during rolling, so that the durability during high-speed driving can be improved. [[ID=,25]]

[0042] <000023 3. Multi-layerization of the belt layer In this disclosure, the belt layer is multilayered by providing at least two layers, and in at least one pair of adjacent belt layers in the radial direction of the tire, the average distance D (mm) between each belt layer in the tread portion is preferably 0.5 mm or less, more preferably 0.45 mm or less, even more preferably 0.4 mm or less, and even more preferably 0.22 mm or less.

[0043] By arranging a set of belt layers at such an average distance D, each belt layer cooperates with the others to restrain the tread and suppress the amount of deformation in the tread, thereby improving durability during high-speed driving.

[0044] The "average distance D between belt layers" referred to here is the average distance between monofilament cords in a belt layer, and is the distance between the inner surface of the monofilament cords in the outer belt layer and the outer surface of the monofilament cords in the inner belt layer on the equatorial plane of two overlapping belt layers.

[0045] 4. Belt reinforcement layer In this disclosure, it is considered preferable that the belt reinforcement layer is provided radially outward of the tire from the belt layer, as this further suppresses deformation of the tread and improves durability during high-speed driving. In this case, it is preferable that the average distance between the monofilament cords in the belt layer and the cords in the belt reinforcement layer be 0.1 mm or more and 0.5 mm or less.

[0046] 5. Grooves in the tread The tire according to this disclosure has circumferential grooves in the tread portion that extend continuously in the circumferential direction of the tire, and the groove width L at a depth of 80% of the maximum depth of the circumferential groove relative to the groove width L0 of the circumferential groove at the contact surface of the tread portion 80 Ratio (L 80 It is preferable that / L0) is between 0.3 and 0.7. This suppresses the movement of the entire tread surface at the bottom of the tread, thereby improving durability during high-speed driving. 80 / L0 is more preferably 0.35 or higher, and even more preferably 0.40 or higher. On the other hand, it is more preferably 0.65 or lower, and even more preferably 0.60 or lower.

[0047] The above L0 and L 80 This refers to the straight-line distance (L0) between the groove ends on the tread surface of the circumferential grooves of a tire mounted on a standard rim, with an internal pressure of 250 kPa, and under no load, and the minimum distance (L) between the groove walls at 80% groove depth. 80 This refers to the bead width, which can be simply determined by cutting a section of the tire radially with a width of 2-4 cm and pressing the bead portion of the section down to match the rim width.

[0048] Furthermore, it is preferable that the tread portion has multiple circumferential grooves, and that the sum of the cross-sectional areas of the multiple circumferential grooves is 10% or more and 30% or less of the cross-sectional area of ​​the tread portion. This suppresses the movement of the tread portion and improves durability during high-speed driving. It is more preferable that it is 15% or more, and even more preferable that it is 18% or more. On the other hand, it is more preferable that it is 27% or less, and even more preferable that it is 25% or less.

[0049] The cross-sectional area of ​​the circumferential grooves described above refers to the total area formed by the straight lines connecting the ends of the tread's circumferential grooves and the groove walls in a tire mounted on a standard rim with an internal pressure of 250 kPa and under no load. In simple terms, this can be determined by cutting a section of the tire radially with a width of 2 to 4 cm and pressing the bead portion of the section against the rim width.

[0050] Furthermore, the cross-sectional area of ​​the tread refers to the area radially outside the belt layer of the tire, in the radial cross-section of a tire mounted on a standard rim, with an internal pressure of 250 kPa and under no load. This area is defined by a straight line connecting the ends of the circumferential grooves of the tread, and two straight lines parallel to the equatorial plane that pass through both ends of the widest part of the tread surface profile and belt layer formed by the tread surface. If there is a belt reinforcement layer made of organic fibers and / or steel cords radially outside the belt layer, the cross-sectional area of ​​the tread refers to the area radially outside the belt reinforcement layer.

[0051] Furthermore, the tread portion has multiple lateral grooves extending in the axial direction of the tire, and it is preferable that the total volume of the multiple lateral grooves is 2.0% or more and 5.0% or less of the volume of the tread portion. This suppresses the movement of the tread portion and improves durability during high-speed driving. It is more preferable that it is 2.2% or more, even more preferable that it is 2.5% or more, and particularly preferable that it is 2.7% or more. On the other hand, it is more preferable that it is 4.0% or less, even more preferable that it is 3.5% or less, and particularly preferable that it is 3.0% or less.

[0052] The volume of the lateral grooves described above refers to the total volume formed by the surface connecting the ends of the lateral grooves and the groove walls in a tire mounted on a standard rim, with an internal pressure of 250 kPa, and under no load. This volume can be determined by calculating the volume of each individual lateral groove and then summing them up. The volume of the tread can be calculated by determining the area of ​​the tread and multiplying it by the outer diameter, and then finding the difference between this and the volume of the lateral grooves.

[0053] [3] Embodiment The present disclosure will be described in detail below based on embodiments.

[0054] A. Belt layer In the tire according to this embodiment, the belt layer is made by coating both sides of monofilament cords arranged at predetermined ends with a rubber composition constituting the belt layer (belt layer rubber composition), and a belt member is manufactured using this.

[0055] B. Side section In the tire according to this embodiment, the side portion is manufactured by molding it into a predetermined shape using the sidewall rubber composition shown below.

[0056] 1. Sidewall rubber composition (1) Compounding materials The sidewall rubber composition can be obtained from the rubber components and other compounding materials described below.

[0057] (a) Rubber component In this embodiment, the rubber component is not particularly limited, and any rubber (polymer) commonly used in tire manufacturing can be used, such as isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), and butyl rubber. Among these, isoprene rubber and butadiene rubber are preferred from the viewpoint of forming a phase-separated structure and being less prone to cracking during deformation. SBR and other rubber components may also be used in combination as needed.

[0058] (i) Isoprene rubber The content of isoprene-based rubber (total content) in 100 parts by mass of rubber components is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 55 parts by mass or more, from the viewpoint of exhibiting good tensile strength and making it difficult for damage such as cracks to occur due to deformation. On the other hand, from the viewpoint of forming a phase separation structure with other rubber components and preventing the propagation of cracks and fractures inside the rubber, it is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 65 parts by mass or less.

[0059] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR, but NR is preferred due to its superior strength.

[0060] For NR, common types used in the tire industry can be used, such as SIR20, RSS#3, and TSR20. For IR, there are no particular limitations, and common types used in the tire industry can be used, such as IR2200. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used individually or in combination of two or more types.

[0061] (b)BR In this embodiment, it is preferable to use BR together with NR as the rubber component. From the viewpoint of suppressing the propagation of cracks and fractures, the BR content is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 35 parts by mass or more. On the other hand, it is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 45 parts by mass or less.

[0062] The weight-average molecular weight of BR is, for example, greater than 100,000 and less than 2,000,000. The vinyl bond content (amount of 1,2-bonded butadiene units) of BR is, for example, greater than 1% by mass and less than 30% by mass. The cis content of BR is, for example, greater than 1% by mass and 98% by mass or less. The trans content of BR is, for example, greater than 1% by mass and less than 60% by mass. The cis content can be measured by infrared absorption spectroscopy.

[0063] The BR is not particularly limited, and can be high-cis content BR (cis content of 90% or more), low-cis content BR, or BR containing syndiotactic polybutadiene crystals. The BR can be either unmodified or modified, and as modified BR, for example, S-modified BR modified with a compound (modifying agent) represented by the following formula can be used.

[0064] [ka]

[0065] Note that in the formula, R 1 , R 2 and R 3 R represents, either identical or distinct, an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or a derivative thereof. 4 and R 5 R represents a hydrogen atom or an alkyl group, either identical or different. 4 and R 5 These atoms may bond to form a ring structure with the nitrogen atom. n represents an integer.

[0066] Modified BR, which has been modified by the compound (modifying agent) represented by the above formula, is an example of BR in which the polymerization end (active end) has been modified by the compound represented by the above formula.

[0067] R 1 , R 2 and R 3 A suitable alkoxy group is used (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). 4 and R 5 A suitable alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is used. n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. Also, R 4 and R 5When the alkoxy group is bonded to form a ring structure with the nitrogen atom, it is preferably a 4- to 8-membered ring. Note that the alkoxy group also includes cycloalkoxy groups (such as cyclohexyloxy group) and aryloxy groups (such as phenoxy group and benzyloxy group).

[0068] Specific examples of the above-mentioned denaturing agents include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. These may be used individually or in combination of two or more.

[0069] Furthermore, modified BR can also be modified using the following compounds (modifying agents): For example, polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups such as diglycidyl bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxy-modified liquid polybutadiene; epoxy-group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, Diglycidylamino compounds such as diglycidyl orthotoluidine, tetraglycidylmetoxylendiamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamate chloride, 4-morpholine carbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamate chloride, and N,N-diethylcarbamate chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane;(Trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldipropoxysilyl)propyl]sulfide Sulfide group-containing silane compounds such as [sisilyl)propyl]sulfide and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyl Alkoxysilanes such as tiltriethoxysilane; (thio)benzophenone compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, and N,N,N',N'-bis-(tetraethylamino)benzophenone; 4-N,N- Benzaldehyde compounds having an amino group and / or a substituted amino group, such as dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, and N-phenyl-2-piperidone;In addition to N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurylolactam, N-vinyl-ω-laurylolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam, other examples include N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), and tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-triones. Examples include N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophene, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, and 1,7-bis(methylethylamino)-4-heptanone. Modification using the above compounds (modifiers) can be carried out by known methods.

[0070] For example, tin-modified BR can be used. Tin-modified BR is obtained by polymerizing 1,3-butadiene with a lithium initiator, followed by the addition of a tin compound, and it is preferable that the terminal ends of the tin-modified BR molecule are linked by tin-carbon bonds.

[0071] Examples of lithium initiators include lithium-based compounds such as alkyllithium, aryllithium, vinyllithium, organotinlithium, and organonitrogenlithium compounds, as well as lithium metal. By using the aforementioned lithium initiator as the initiator for tin-modified BR, tin-modified BR with high vinyl and low cis content can be produced.

[0072] Examples of tin compounds include tin tetrachloride, butyltin trichloride, dibutyltin dichloride, dioctyltin dichloride, tributyltin chloride, triphenyltin chloride, diphenyldibutyltin, triphenyltin ethoxide, diphenyldimethyltin, dityltin chloride, diphenyltin dioctanoate, divinyldiethyltin, tetrabenzyltin, dibutyltin distearate, tetraalyltin, and p-tributyltin styrene.

[0073] Furthermore, the tin atom content in tin-modified BR is preferably 50 ppm or more, more preferably 60 ppm or more. On the other hand, it is preferably 3000 ppm or less, more preferably 2500 ppm or less, and even more preferably 250 ppm or less.

[0074] Furthermore, the molecular weight distribution (Mw / Mn) of tin-modified BR is preferably 2 or less, and more preferably 1.5 or less.

[0075] Furthermore, the amount of vinyl bonded in tin-modified BR is preferably 5% by mass or more, and more preferably 7% by mass or more. On the other hand, the amount of vinyl bonded in tin-modified BR is preferably 50% by mass or less, and more preferably 20% by mass or less.

[0076] The S-modified BR and tin-modified BR mentioned above may be used individually or in combination of two or more types.

[0077] For example, products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used as BRs.

[0078] (H) SBR Furthermore, in this embodiment, the rubber component may, if necessary, be 5 to 25 parts by mass of SBR together with NR, or it may be used in combination with the BR described above.

[0079] The weight-average molecular weight of SBR is, for example, more than 100,000 and less than 2,000,000. The styrene content of SBR is preferably more than 5% by mass, more preferably more than 10% by mass, and even more preferably more than 20% by mass. On the other hand, it is preferably less than 50% by mass, more preferably less than 40% by mass, and even more preferably less than 35% by mass. The amount of vinyl bonded material in SBR is preferably more than 5% by mass and less than 70% by mass. The structural identification of SBR (measurement of styrene content and vinyl bonded material) can be performed, for example, using an instrument from JEOL Ltd.'s JNM-ECA series.

[0080] The SBR is not particularly limited, and for example, emulsion polymerized styrene-butadiene rubber (E-SBR), solution polymerized styrene-butadiene rubber (S-SBR), etc. can be used. The SBR may be either unmodified SBR or modified SBR, and these may be used alone or in combination of two or more types.

[0081] Modified SBRs can be any SBR having a functional group that interacts with a packing material such as silica. Examples include terminally modified SBRs (terminally modified SBRs having the functional group at the terminal) in which at least one end of the SBR is modified with a compound having the functional group (modifying agent), main-chain modified SBRs having the functional group in the main chain, main-chain terminally modified SBRs having the functional group in both the main chain and the terminal (for example, main-chain terminally modified SBRs having the functional group in the main chain and at least one end modified with the modifying agent), and terminally modified SBRs that are modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule, and in which hydroxyl groups or epoxy groups are introduced.

[0082] For example, SBR manufactured and sold by companies such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Co., Ltd. can be used. SBR may be used alone or in combination of two or more types.

[0083] (ii) Other rubber components In addition, other rubber components may include, if necessary, nitrile rubber (NBR) or other rubbers (polymers) commonly used in tire manufacturing.

[0084] (b) Compounding materials other than rubber components (i) Filling agent In this embodiment, the sidewall rubber composition preferably contains a filler. Specific fillers include, for example, carbon black, silica, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. Among these, carbon black is preferably used as a reinforcing agent. Silica may also be used as a reinforcing agent if necessary, but in this case, it is preferable to use it in combination with a silane coupling agent.

[0085] (i) Carbon Black The sidewall rubber composition preferably contains carbon black. The carbon black content is preferably, for example, 10 parts by mass or more and 100 parts by mass or less, more preferably 15 parts by mass or more and 60 parts by mass or less, and even more preferably 25 parts by mass or more and 55 parts by mass or less, per 100 parts by mass of the rubber component.

[0086] Carbon black is not particularly limited and can include furnace blacks (furnace carbon blacks) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black (acetylene carbon black); thermal blacks (thermal carbon blacks) such as FT and MT; and channel blacks (channel carbon blacks) such as EPC, MPC, and CC. These may be used individually or in combination of two or more types.

[0087] The specific surface area (N2SA) of carbon black for nitrogen adsorption is, for example, 30 m². 2 / g, 250m 2The amount is less than / g. The amount of dibutyl phthalate (DBP) absorbed by carbon black is, for example, greater than 50 ml / 100g and less than 250 ml / 100g. The specific surface area for nitrogen adsorption of carbon black is measured according to ASTM D4820-93, and the amount of DBP absorbed is measured according to ASTM D2414-93.

[0088] There are no specific limitations on the carbon black used, but examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nippon Chemical Carbon Co., Ltd., and Columbia Carbon Corporation. These can be used individually or in combination of two or more types.

[0089] (ii) Silica The sidewall rubber composition preferably further contains silica, if necessary. The BET specific surface area of ​​silica is 140 m² from the viewpoint of obtaining good durability. 2 Preferably more than / g, 160m 2 A value greater than / g is preferable. On the other hand, from the viewpoint of obtaining good low rolling resistance, 250m 2 Preferably less than / g, 220m 2 It is more preferable that the value be less than / g.

[0090] Furthermore, the silica content per 100 parts by mass of rubber component is preferably 3 parts by mass or more, and more preferably 5 parts by mass or more, when not used in combination with a silane coupling agent. On the other hand, it is preferably 25 parts by mass or less, and more preferably 15 parts by mass or less. When used in combination with a silane coupling agent, it is preferably 25 parts by mass or more. On the other hand, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. The BET specific surface area mentioned above is the N2SA value measured by the BET method in accordance with ASTM D3037-93.

[0091] Examples of silica include dry-process silica (anhydrous silica) and wet-process silica (hydrated silica). Of these, wet-process silica is preferred because it contains a large number of silanol groups.

[0092] For example, silica products from companies such as Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., and Tokuyama Corporation can be used.

[0093] (iii) Silane coupling agents As mentioned above, when using silica, it is also possible to use a silane coupling agent in combination. The silane coupling agent is not particularly limited and includes, for example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl) trisulfide, bis(4-trimethoxysilylbutyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthioca Examples include sulfide compounds such as rubamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z from Momentive; vinyl compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These may be used individually or in combination of two or more.

[0094] Examples of silane coupling agents that can be used include products from companies such as Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Toray Dow Corning Co., Ltd.

[0095] The silane coupling agent content is, for example, more than 3 parts by mass and less than 15 parts by mass per 100 parts by mass of silica.

[0096] (iv) Other fillers In addition to the carbon black and silica mentioned above, the sidewall rubber composition may further contain fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. The amount of these fillers is, for example, more than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0097] (b) Curable resin components The sidewall rubber composition may optionally contain curable resin components such as modified resorcinol resin or modified phenolic resin.

[0098] Specific examples of modified resorcinol resins include, for instance, Sumikanol 620 (modified resorcinol resin) manufactured by Taoka Chemical Industries, Ltd., and for example, PR12686 (cashew oil modified phenol resin) manufactured by Sumitomo Bakelite Co., Ltd.

[0099] The content of the curable resin component is preferably 1 part by mass or more, and more preferably 2 parts by mass or more, per 100 parts by mass of the rubber component, from the viewpoint of sufficiently improving the complex modulus of elasticity and obtaining a large reaction force during deformation. On the other hand, from the viewpoint of maintaining the breaking strength, it is preferably 10 parts by mass or less, and more preferably 8 parts by mass or less.

[0100] When using modified resorcinol resin, it is preferable to include a methylene donor as a curing agent. Examples of methylene donors include hexamethylenetetramine (HMT), hexamethoxymethylolmelamine (HMMM), and hexamethylenemelamine pentamethyl ether (HMMPME), and it is preferable that they be included in an amount of, for example, 5 to 15 parts by mass per 100 parts by mass of the curable resin component. If the amount is too small, a sufficient complex modulus may not be obtained. On the other hand, if the amount is too large, the viscosity of the rubber may increase, and the processability may deteriorate.

[0101] As a specific methylene donor, for example, Sumikanol 507 manufactured by Taoka Chemical Industries, Ltd. can be used.

[0102] (h) Plasticizer components The rubber composition may contain oil (including spreading oil), liquid rubber, and resin as plasticizer components to soften the rubber. The plasticizer components are those that can be extracted from vulcanized rubber with acetone. The total content of the plasticizer components is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, per 100 parts by mass of the rubber component. On the other hand, it is preferably less than 70 parts by mass, more preferably less than 50 parts by mass, and even more preferably less than 30 parts by mass. The oil content also includes the amount of oil contained in the rubber (oil-spreading rubber).

[0103] (i) oil Examples of oils include mineral oil (generally called process oil), vegetable oils, or mixtures thereof. Examples of mineral oils (process oils) include paraffinic process oil, aromatic process oil, and naphthenic process oil. Examples of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These may be used individually or in combination of two or more.

[0104] Specific examples of process oils (mineral oils) that can be used include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoy Inc., H&R Inc., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and others.

[0105] (ii) Liquid rubber The liquid rubber mentioned as a plasticizer is a polymer that is in a liquid state at room temperature (25°C) and is a rubber component that can be extracted from vulcanized tires by acetone extraction. Examples of liquid rubber include farnesene polymers, liquid diene polymers, and their hydrogenated derivatives.

[0106] Farnesene polymers are polymers obtained by polymerizing farnesene and have constituent units based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene).

[0107] The farnesene polymer may be a farnesene homopolymer (farnesene homopolymer) or a farnesene-vinyl monomer copolymer (farnesene-vinyl monomer copolymer).

[0108] Examples of liquid diene polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene-isoprene copolymer (liquid SIR).

[0109] The liquid diene polymer has a weight-average molecular weight (Mw) on a polystyrene basis, measured by gel permeation chromatography (GPC), for example, 1.0 × 10⁻⁶. 3 Super, 2.0×10 5 It is less than. In this specification, the Mw of the liquid diene polymer is the polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0110] The liquid rubber content (total content of liquid farnesene polymers, liquid diene polymers, etc.) is, for example, more than 1 part by mass and less than 100 parts by mass per 100 parts by mass of rubber components.

[0111] As for liquid rubber, products from companies such as Kuraray Co., Ltd. and Clay Valley Corporation can be used.

[0112] (iii) Resin components The resin component also functions as a tackifying agent and may be solid or liquid at room temperature. Specific resin components include, for example, rosin resins, styrene resins, coumarone resins, terpene resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, and two or more may be used in combination. The resin component content is preferably more than 2 parts by mass and less than 45 parts by mass, and more preferably less than 30 parts by mass, per 100 parts by mass of the rubber component.

[0113] Rosin resins are resins whose main component is rosin acid, obtained by processing pine resin. These rosin resins (rosins) can be classified according to whether or not they are modified, and can be classified into unmodified rosin and rosin derivatives. Examples of unmodified rosin include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionate rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. Rosin derivatives are modified forms of unmodified rosin and include rosin esters, unsaturated carboxylic acid-modified rosins, unsaturated carboxylic acid-modified rosin esters, rosin amide compounds, and rosin amine salts.

[0114] Styrene resins are polymers that use styrene monomers as constituent monomers, and include polymers polymerized with styrene monomers as the main component (50% by mass or more). Specifically, examples include homopolymers obtained by polymerizing styrene monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) individually, copolymers obtained by copolymerizing two or more styrene monomers, and copolymers of styrene monomers and other monomers that can copolymerize with them.

[0115] Examples of the aforementioned other monomers include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene and butadiene isoprene, olefins such as 1-butene and 1-pentene; and α,β-unsaturated carboxylic acids such as maleic anhydride or their acid anhydrides.

[0116] Among coumarone-based resins, coumarone-indene resin is preferred. Coumarone-indene resin is a resin that contains coumarone and indene as monomer components that constitute the resin's backbone (main chain). Other monomer components that can be included in the backbone besides coumarone and indene include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0117] The coumaron indene resin content is, for example, more than 1.0 part by mass and less than 50.0 parts by mass per 100 parts by mass of rubber component.

[0118] The hydroxyl value (OH value) of coumarone indene resin is, for example, greater than 15 mg KOH / g and less than 150 mg KOH / g. The OH value is expressed in milligrams as the amount of potassium hydroxide required to neutralize the acetic acid bonded to the hydroxyl groups when acetylating 1 g of resin, and is measured by potentiometric titration (JIS K 0070:1992).

[0119] The softening point of coumaron indene resin is, for example, above 30°C and below 160°C. The softening point is determined by measuring the softening point as specified in JIS K 6220-1:2001 using a ring-type softening point measuring device, and it is the temperature at which the sphere descends.

[0120] Examples of terpene resins include polyterpenes, terpene phenols, and aromatically modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenated products. Terpene compounds are (C5H8) n A hydrocarbon represented by the following composition and its oxygen-containing derivative, a monoterpene (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpene (C 20 H 32 These are compounds with a terpene as their basic skeleton, classified as such, and examples include α-pinene, β-pinene, dipentene, limonene, myrcene, allocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0121] Polyterpenes include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin, which are made from the terpene compounds mentioned above, as well as hydrogenated terpene resins obtained by hydrogenating these terpene resins. Terpene phenols include resins obtained by copolymerizing the above terpene compounds with phenolic compounds, and resins obtained by hydrogenating these resins. Specifically, resins obtained by condensing the above terpene compounds, phenolic compounds, and formalin are included. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Aromatically modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating these resins. The aromatic compounds are not particularly limited as long as they are compounds having an aromatic ring, but examples include phenol compounds such as phenol, alkylphenol, alkoxyphenol, and phenol containing an unsaturated hydrocarbon group; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and naphthol containing an unsaturated hydrocarbon group; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and styrene containing an unsaturated hydrocarbon group; coumarone, indene, and others.

[0122] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferably used as a C5-based petroleum resin.

[0123] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be hydrogenated or modified. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples include coumarone indene resin, coumarone resin, indene resin, and aromatic vinyl resins, which are suitably used. As aromatic vinyl resins, homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene are preferred, and copolymers of α-methylstyrene and styrene are more preferred, due to their economical nature, ease of processing, and excellent heat generation properties. Aromatic vinyl resins that are commercially available from companies such as Kraton and Eastman Chemical can be used.

[0124] "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified. Examples of the C5 and C9 fractions include the petroleum fractions mentioned above. As for the C5C9 resin, commercially available products from companies such as Tosoh Corporation and LUHUA can be used.

[0125] While there are no particular limitations on the acrylic resin used, for example, a solvent-free acrylic resin can be used.

[0126] Solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized by high-temperature continuous polymerization (high-temperature continuous mass polymerization) (methods described in U.S. Patent No. 4,414,370, Japanese Patent Publication No. 59-6207, Japanese Patent Publication No. 5-58005, Japanese Patent Publication No. 1-313522, U.S. Patent No. 5,010,166, Toa Gosei Research Annual Report TREND2000 No. 3 pp. 42-45, etc.) with minimal use of polymerization initiators, chain transfer agents, organic solvents, etc. as auxiliary raw materials. In this disclosure, (meth)acrylic means methacrylic and acrylic.

[0127] Examples of monomer components constituting the above-mentioned acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylic acid derivatives such as (meth)acrylamide derivatives.

[0128] Furthermore, as monomer components constituting the above-mentioned acrylic resin, aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene may be used along with (meth)acrylic acid and (meth)acrylic acid derivatives.

[0129] The above-mentioned acrylic resin may be a resin composed solely of (meth)acrylic components, or a resin that also contains components other than (meth)acrylic components. Furthermore, the above-mentioned acrylic resin may have hydroxyl groups, carboxyl groups, silanol groups, etc.

[0130] As resin components, products from companies such as Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JX Energy Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Industries, Ltd. can be used.

[0131] (ii) Cobalt organic acid The sidewall rubber composition may optionally contain cobalt organic acid.

[0132] Examples of organic cobalt acids include cobalt stearate, cobalt naphthenate, cobalt neodecanoate, and cobalt boron-3 neodecanoate.

[0133] The organic cobalt content is preferably 500 ppm or more, more preferably 700 ppm or more, and even more preferably 900 ppm or more, as a cobalt concentration in the sidewall rubber composition. On the other hand, it is preferably 1500 ppm or less, and more preferably 1300 ppm or less.

[0134] (e) Reversion (vulcanization reversal) The sidewall rubber composition preferably contains a reversion (vulcanization reversal) inhibitor as needed. This suppresses reversion and improves durability. The content of the reversion inhibitor is preferably 0.1 parts by mass or more and 3 parts by mass or less, more preferably 0.2 parts by mass or more and 2.5 parts by mass or less, and even more preferably 0.3 parts by mass or more and 2 parts by mass or less, per 100 parts by mass of the rubber component. As a specific reversion inhibitor, for example, Parkalink 900 (1,3-bis(citraconimidomethyl)benzene) manufactured by Flexis can be used.

[0135] (h) Anti-aging agents The sidewall rubber composition preferably contains an anti-aging agent. The amount of anti-aging agent is, for example, more than 1 part by mass and less than 10 parts by mass per 100 parts by mass of the rubber component.

[0136] Examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4′-bis(α,α′-dimethylbenzyl)diphenylamine; N-isopropyl-N′-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, and N,N′-di-2-naphthyl-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers and other quinoline-based antioxidants; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane. These may be used individually or in combination of two or more types.

[0137] Furthermore, as an anti-aging agent, products from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis Co., Ltd. can be used.

[0138] (to)stearic acid The sidewall rubber composition may contain stearic acid. The stearic acid content is, for example, more than 0.5 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component. Conventional known stearic acid can be used, such as products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acid Co., Ltd., etc.

[0139] (C) Zinc oxide The sidewall rubber composition may contain zinc oxide. The zinc oxide content is, for example, more than 0.5 parts by mass and less than 15 parts by mass per 100 parts by mass of the rubber component. Conventional known zinc oxides can be used, such as products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc.

[0140] (i) Crosslinking agents and vulcanization accelerators The sidewall rubber composition preferably contains a crosslinking agent such as sulfur. The crosslinking agent content is, for example, more than 0.1 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0141] Examples of sulfur commonly used in the rubber industry include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur. These may be used individually or in combination of two or more types.

[0142] For sulfur, products from companies such as Tsurumi Chemical Industries, Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Co., Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., and Hosoi Chemical Industries, Ltd. can be used.

[0143] Other crosslinking agents besides sulfur include, for example, sulfur-containing vulcanizing agents such as Takkirol V200 manufactured by Taoka Chemical Industries, Ltd., Duralink HTS (1,6-hexamethylene-dithiosulfate sodium dihydrate) manufactured by Flexis, and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by Lanxess, as well as organic peroxides such as dicumyl peroxide.

[0144] The sidewall rubber composition preferably contains a vulcanization accelerator. The vulcanization accelerator content is, for example, more than 0.3 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0145] Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diortotrilguanidine, and orthotrilbiguanidine. These can be used individually or in combination of two or more.

[0146] (Nu) Other In addition to the above-mentioned components, the sidewall rubber composition may further contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylate metal salts, and organic peroxides. The content of these additives is, for example, more than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0147] (2) Preparation of sidewall rubber composition The sidewall rubber composition is manufactured by a general method, for example, a manufacturing method that includes a base mixing step of mixing a rubber component with a filler such as carbon black, and a finish mixing step of mixing the mixture obtained in the base mixing step with a crosslinking agent.

[0148] Mixing can be carried out using known (closed) mixers such as Banbury mixers, kneaders, and open roll mixers.

[0149] The mixing temperature in the base mixing process is, for example, more than 50°C and less than 200°C, and the mixing time is, for example, more than 30 seconds and less than 30 minutes. In the base mixing process, in addition to the above components, compounding agents conventionally used in the rubber industry, such as plasticizer components such as oil, stearic acid, zinc oxide, antioxidants, waxes, and vulcanization accelerators, may be added and mixed as needed.

[0150] In the final mixing step, the mixture obtained in the base mixing step and the crosslinking agent are mixed together. The mixing temperature in the final mixing step is, for example, above room temperature but below 80°C, and the mixing time is, for example, more than 1 minute but less than 15 minutes. In the final mixing step, in addition to the above components, vulcanization accelerators, zinc oxide, etc., may be added and mixed as needed.

[0151] (3) Fabrication of the side section The sidewall rubber composition obtained can be used to create a side section by molding it into a predetermined shape.

[0152] C. Tire Manufacturing The tire according to this embodiment can be manufactured as an unvulcanized tire by molding the belt member and side portion obtained above together with other tire members on a tire molding machine in a conventional manner.

[0153] Specifically, an inner liner (a component to ensure the airtightness of the tire), a carcass (a component to withstand the load, impact, and air pressure of the tire), and a belt (a component to tightly fasten the carcass and increase the rigidity of the tread) are wound onto a molding drum. The ends of the carcass are fixed to both side edges, and a bead (a component to fix the tire to the rim) is placed to form a toroid shape. After forming the toroid, the tread is attached to the center of the outer circumference, and the sidewall is attached to the radially outward side to form the side section, thereby creating an unvulcanized tire.

[0154] In this embodiment, the belt layer may be provided in multiple layers, as described above, from the viewpoint of increasing the restraining force on the tread during driving and making it easier to suppress the growth of the outer diameter. In this case, it is preferable that the average distance D (mm) between the cords of each belt layer in the tread portion of the vulcanized tire is 0.5 mm or less. Furthermore, it is preferable that the angle between the monofilament cords in the tread portion and the straight line parallel to the circumferential direction of the tire is 10° or more and 35° or less, and that the cords of adjacent belt layers are arranged to intersect each other.

[0155] The angle of the monofilament cord is the angle of the monofilament cord with respect to the circumferential direction of the tire when the tire is not inflated with air, and can be confirmed by peeling off the tread portion of the tire from the radially outer side.

[0156] Subsequently, the prepared unvulcanized tire is heated and pressurized in a vulcanizing machine to obtain a tire. The vulcanization process can be carried out by applying known vulcanization methods. The vulcanization temperature is, for example, above 120°C and below 200°C, and the vulcanization time is, for example, above 5 minutes and below 15 minutes.

[0157] At this time, the tire is assembled onto a regular rim and molded to satisfy the above-mentioned equations (1) and (2) when the internal pressure is set to 250 kPa.

[0158] Specific tires to which this disclosure is preferably applied include, for example, tires with size designations such as 145 / 60R18, 145 / 60R19, 155 / 55R18, 155 / 55R19, 155 / 70R17, 155 / 70R19, 165 / 55R20, 165 / 55R21, 165 / 60R19, 165 / 65R19, 165 / 70R18, 175 / 55R19, 175 / 55R20, 175 / 55R22, 175 / 60R18, 185 / 55R19, 185 / 60R20, 195 / 50R20, and 195 / 55R20.

[0159] In this embodiment, the tire can be used for various types of tires, including passenger car tires, truck and bus tires, and motorcycle tires. Among tires that satisfy (Equation 1) and (Equation 2), it is preferable to apply it to passenger car tires, that is, tires mounted on automobiles that travel on four wheels and have a maximum load capacity of 1000 kg or less. By satisfying (Equation 1) and (Equation 2), it is possible to more favorably contribute to solving the problem in this disclosure, which is to provide a pneumatic tire with excellent durability at high speeds.

[0160] The maximum load capacity mentioned above is approximately 50 to 100 kg smaller than the maximum load capacity specified for each tire in the standard system on which the tire is based, for example, the maximum load capacity based on the load index (LI) specified in the JATMA standard (Japan Automobile Tire Manufacturers Association standard). Specifically, it is calculated using the following two formulas based on the tire section width Wt (mm), tire section height Ht (mm), and tire outer diameter Dt (mm) when the tire is mounted on a regular rim and the internal pressure is 250 kPa under no load. Note that V is the volume of space occupied by the tire (virtual volume), and (Dt / 2-Ht) is the rim diameter (mm). V(mm 3 ) = {(Dt / 2) 2 -(Dt / 2-Ht) 2} × π × Wt WL(kg) = 0.000011 × V + 175

[0161] The maximum load capacity mentioned above is not particularly limited as long as it is 1000 kg or less. However, generally, as the maximum load capacity increases, the tire weight tends to increase and the impact transmitted to the tire tends to increase as well. Therefore, it is preferable that the maximum load capacity be 900 kg or less, more preferably 800 kg or less, and even more preferably 700 kg or less.

[0162] Here, the tire weight is preferably 20 kg or less, more preferably 15 kg or less, and even more preferably 12 kg or less, 10 kg or less, or 8 kg or less, from the viewpoint of mitigating the impact transmitted to the tire. The tire weight referred to here is the weight of the entire tire, and if the tire's inner surface is equipped with sealant, sponge, three-dimensional mesh structure, electronic components, etc., then the weight includes these components. Furthermore, the tire weight can be appropriately adjusted by the thickness and width of each component constituting the tire, the specific gravity of the rubber composition, the number of steel cords arranged in the belt reinforcement layer, the configuration of the bead wire, etc. [Examples]

[0163] The present disclosure will be further described below with reference to examples.

[0164] 1. Manufacturing of belt components First, the compounding materials for the belt rubber composition are: 100 parts by mass of NR (RSS3), 55 parts by mass of carbon black (Show Black N326 manufactured by Cabot Japan Co., Ltd.), 0.5 parts by mass of crosslinking aid (Duralink HTS manufactured by Flexis Corporation), 3 parts by mass of curable resin component (PR12686 manufactured by Sumitomo Bakelite Co., Ltd.), and organic cobalt acid (DICNATE manufactured by DIC Corporation). The following ingredients were prepared: 1.5 parts by mass of NBC-2, 1.5 parts by mass of curing agent (Sumikanol 507 manufactured by Taoka Chemical Industries, Ltd.), 10 parts by mass of zinc oxide (Zinc Oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd.), 1 part by mass of antioxidant (Nocrac 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), 0.5 parts by mass of antioxidant (Antage RD manufactured by Kawaguchi Chemical Industry Co., Ltd.), 1 part by mass of stearic acid (Stearic Acid "Tsubaki" manufactured by NOF Corporation), 7 parts by mass of sulfur (powdered sulfur manufactured by Tsurumi Chemical Industries, Ltd.), and 1.2 parts by mass of vulcanization accelerator (Noxellar DZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd.).

[0165] Next, using a Banbury mixer, the materials other than the curing agent, sulfur, and vulcanization accelerator were kneaded at 150°C for 5 minutes to obtain a mixture. Then, the curing agent, sulfur, and vulcanization accelerator were added to the mixture and kneaded using an open roll at 80°C for 5 minutes to obtain a rubber composition for belts.

[0166] Next, steel cords with the configuration and cord outer diameter (mm) shown in Tables 1 and 2 were arranged at the ends (cords / 5cm) shown in Tables 1 and 2, and then the belt rubber composition obtained above was applied to both sides to produce a belt member. At this time, equal amounts of rubber were applied to the top and bottom so that the steel cords were positioned in the center of the thickness direction of the belt member, and the thickness was appropriately adjusted so that the steel cords between a pair of belt layers in the vulcanized tire were at the average distance D (mm) shown in Tables 1 and 2.

[0167] 2. Fabrication of the side section The side sections were fabricated separately using a sidewall rubber composition.

[0168] (1) Compounding materials for sidewall rubber composition First, the following ingredients were prepared.

[0169] (a) Rubber component (i) NR: TSR20 (b) BR: UBEPOL-BR150B manufactured by Ube Industries, Ltd. (Cis content: 97% by mass)

[0170] (b) Compounding materials other than rubber components (i) Carbon Black: Show Black N550 manufactured by Cabot Japan Co., Ltd. (N2SA:42m 2 / g, DOP oil absorption: 115ml / 100g) (b) Oil: Process X-140 manufactured by Japan Energy Co., Ltd. (H) Wax: Sunnock wax manufactured by Ouchi Shinko Chemical Co., Ltd. (ii) Anti-aging agent-1: Nocrack 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) (e) Anti-aging agent-2: Anti-aging agent manufactured by Kawaguchi Chemical Industry Co., Ltd. (2,2,4-trimethyl-1,2-dihydroquinoline) (H) Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. (T) Stearic acid: Stearic acid "Tsubaki" manufactured by NOF Corporation (C) Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industries, Ltd. (R) Vulcanization accelerator: Noxellar NS manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-tert-butyl-2-benzothiazolyl sulfenamide)

[0171] (2) Manufacture of sidewall rubber composition According to the formulations shown in Tables 1 and 2, the materials other than sulfur and vulcanization accelerator were mixed in a Banbury mixer for 5 minutes under conditions of 150°C to obtain a mixture. The amounts of each ingredient are in parts by mass.

[0172] Next, sulfur and a vulcanization accelerator were added to the resulting mixture, and the mixture was kneaded using an open roll at 80°C for 5 minutes to obtain a sidewall rubber composition.

[0173] Next, a side section of a predetermined shape was fabricated using the obtained sidewall rubber composition.

[0174] 3. Tire manufacturing The side portion obtained above and a belt member made by bonding two layers of belt members together so that the steel cords in the belt member intersect each other at angles shown in Tables 1 to 4 with respect to a straight line parallel to the tire circumference, were bonded together with other tire members to form an unvulcanized tire. The tire was then press-vulcanized at 170°C for 10 minutes to produce test tires of the sizes shown in Tables 1 and 2 (Examples 1 to 13 and Comparative Examples 1 to 7).

[0175] Furthermore, for each test tire, the above-mentioned (L 80 The ratio of L0 was set to 0.5, the sum of the cross-sectional areas of the circumferential grooves was set to 22% of the cross-sectional area of ​​the tread, and the sum of the volumes of the transverse grooves was set to 3.5% of the volume of the tread.

[0176] 4. Calculation of parameters Subsequently, the cross-sectional width Wt (mm) and side height T (mm) of each test tire were determined. In addition, rubber composition was cut from the side of each test tire to prepare viscoelasticity test pieces measuring 40 mm in length and 4 mm in width. These were then measured using a GABO Iplexer series under the following conditions: temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, deformation mode: stretching. * The viscoelasticity (MPa) was measured. The results are shown in Tables 1 and 2. For products using the same rubber composition, the viscoelasticity of the rubber composition was measured from each specification, and the average value is shown.

[0177] Then, using the obtained results, "e / (139.5-0.3Wt)", "e / (191.5-0.3Wt)", "e / (110.84-0.1667Wt)", "(E * The calculation was performed using " / T) × 100".

[0178] 5. Performance evaluation test (evaluation of durability) Each test tire was mounted on all wheels of a vehicle (a domestically produced front-wheel-drive car with a 2000cc engine), and after inflating them to an internal pressure of 250kPa, the vehicle was overloaded and driven 10 laps at a speed of 50km / h on a dry test course, repeatedly driving over bumps and uneven surfaces at a speed of 80km / h. Then, the vehicle was driven again at a speed of 50km / h, and after that, the speed was gradually increased until the driver noticed something unusual, at which point the speed was measured.

[0179] Next, the results in Comparative Example 2 were set to 100, and the durability performance was relatively evaluated by indexing them based on the following formula. A higher numerical value indicates better durability performance. Durability performance = [(Results of test tire) / (Results of comparative example 2)] × 100

[0180] The evaluation results are shown in Tables 1 and 2.

[0181] [Table 1]

[0182] [Table 2]

[0183] The results shown in Tables 1 and 2 indicate that when a belt layer using monofilament cords as reinforcing cords satisfies the above-mentioned equations (1) and (2), it is possible to provide a pneumatic tire with excellent durability at high speeds.

[0184] And, if the ends are 80 pieces / 5cm or more, or if the side part is (E * When the condition / T)×100≦3.0 (Equation 4) is satisfied, it can be seen that a pneumatic tire with further improved durability at high speeds can be provided.

[0185] Although the present disclosure has been described above based on embodiments, the present disclosure is not limited to the embodiments described above. Various modifications can be made to the embodiments described above within the same and equivalent scope as the present disclosure.

[0186] This disclosure (1) is, A pneumatic tire having side sections and a belt layer, The aforementioned belt layer uses monofilament cord as a reinforcing cord. The number of monofilament cords e (cords / 5cm) per 5cm in the tire width direction in the radial cross-section of the belt layer, and the tire cross-sectional width Wt (mm) when assembled on a regular rim with an internal pressure of 250kPa, satisfy the following equations (Equation 1) to (Equation 3). And Furthermore, the complex modulus E of the sidewall rubber composition in the side portion was measured under the following conditions: temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, deformation mode: stretching. * (MPa) and the height T (mm) of the side portion are given by the following equation (Equation 4) This is a pneumatic tire characterized by satisfying the following conditions. e / (139.5-0.3Wt)>1 (Formula 1) e / (191.5-0.3Wt)<1 (Formula 2) e / (110.84-0.1667Wt) >1 ...(Formula 3) (E * / T)×100≦3.0 (Formula 4)

[0187] This disclosure (2) is, The tire is characterized in that the tire section width Wt is 125 mm or more and 300 mm or less, and is a pneumatic tire as described in disclosure (1).

[0188] This disclosure (3) is, If the tire section width Wt (mm) is 215 mm or more be The present invention is characterized by being a pneumatic tire as described in (1) or (2) of this disclosure. 。

[0189] This disclosure (4) is, The aforementioned monofilament cord is characterized in that the cord outer diameter is 0.1 mm or more and 0.5 mm or less, and is a pneumatic tire in any combination with any of (1) to (3) of this disclosure.

[0190] This disclosure (5) is, The present invention provides a pneumatic tire characterized in that the number of monofilament cords arranged per 5 cm in the tire width direction e (cords / 5 cm) is greater than 80 cords / 5 cm, and is in any combination with any of (1) to (4) of this disclosure.

[0192] This disclosure ( 6 )teeth, The angle between the reinforcing cord of the belt layer and a straight line parallel to the circumferential direction of the tire is 10° or more and 35° or less, as described in this disclosure (1) to ( 5 It is a pneumatic tire in any combination of any of the following:

[0193] This disclosure ( 7 )teeth, The belt layer is provided in at least two layers, The present disclosure (1) to ( 6It is a pneumatic tire in any combination of any of the following:

[0194] This disclosure ( 8 )teeth, The tread portion has circumferential grooves that extend continuously in the circumferential direction of the tire. The groove width L at a depth of 80% of the maximum depth of the circumferential groove relative to the groove width L0 of the circumferential groove on the contact surface of the tread portion. 80 Ratio (L 80 The characteristics of / L0) are that it is 0.3 or more and 0.7 or less, and the disclosure(1) to ( 7 It is a pneumatic tire in any combination of any of the following:

[0195] This disclosure ( 9 )teeth, The tread portion has multiple circumferential grooves that extend continuously in the circumferential direction of the tire. The present disclosure (1) to ( 8 It is a pneumatic tire in any combination of any of the following:

[0196] This disclosure ( 10 )teeth, The tread has multiple lateral grooves that extend in the axial direction of the tire. The present disclosure (1) to ( 9 It is a pneumatic tire in any combination of any of the following:

Claims

1. A pneumatic tire having side sections and a belt layer, The aforementioned belt layer uses monofilament cord as a reinforcing cord. The number of monofilament cords arranged per 5 cm in the tire width direction in the radial cross-section of the belt layer, e (cords / 5 cm), and the tire cross-sectional width Wt (mm) when assembled on a regular rim and with an internal pressure of 250 kPa, satisfy the following equations (Equation 1) to (Equation 3): Furthermore, the pneumatic tire is characterized in that the complex modulus E* (MPa) of the sidewall rubber composition in the side portion, measured under the conditions of temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, deformation mode: stretching, and the height T (mm) of the side portion satisfy the following equation (Equation 4). e / (139.5-0.3Wt)>1...(Formula 1) e / (191.5-0.3Wt)<1...(Formula 2) e / (110.84-0.1667Wt)>1...(Formula 3) (E* / T)×100≦3.0 (Formula 4)

2. The pneumatic tire according to claim 1, characterized in that the tire cross-sectional width Wt is 125 mm or more and 300 mm or less.

3. The pneumatic tire according to claim 1 or 2, characterized in that the tire cross-sectional width Wt (mm) is 215 mm or more.

4. The pneumatic tire according to any one of claims 1 to 3, characterized in that the outer diameter of the monofilament cord is 0.1 mm or more and 0.5 mm or less.

5. The pneumatic tire according to any one of claims 1 to 4, characterized in that the number of monofilament cords arranged per 5 cm in the tire width direction e (cords / 5 cm) is greater than 80 cords / 5 cm.

6. The pneumatic tire according to any one of claims 1 to 5, characterized in that the angle between the reinforcing cord of the belt layer and a straight line parallel to the circumferential direction of the tire is 10° or more and 35° or less.

7. The belt layer is provided in at least two layers, The pneumatic tire according to any one of claims 1 to 6, characterized in that at least one pair of adjacent belt layers in the radial direction of the tire are arranged at a distance of 0.5 mm or less.

8. The tread portion has circumferential grooves that extend continuously in the circumferential direction of the tire. The groove width L of the circumferential groove on the contact surface of the tread portion. ０ The groove width L at a depth of 80% of the maximum depth of the circumferential groove relative to the groove width L ８０ Ratio (L ８０ / L ０ A pneumatic tire according to any one of claims 1 to 7, characterized in that the ratio is 0.3 or more and 0.7 or less.

9. The tread portion has multiple circumferential grooves that extend continuously in the circumferential direction of the tire. The pneumatic tire according to any one of claims 1 to 8, characterized in that the sum of the cross-sectional areas of the plurality of circumferential grooves is 10% or more and 30% or less of the cross-sectional area of ​​the tread portion.

10. The tread has multiple lateral grooves that extend in the axial direction of the tire. The pneumatic tire according to any one of claims 1 to 9, characterized in that the total volume of the plurality of lateral grooves is 2.0% or more and 5.0% or less of the volume of the tread portion.

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