Pneumatic tire

Abstract

Provided is a pneumatic tire having excellent durability during high-speed travel. The pneumatic tire includes a side portion and a belt layer in which a monofilament cord is used as a reinforcing cord, and the number of monofilament cords arranged per 5 cm in the tire width direction e (number of cords / 5 cm) in the tire radial cross section of the belt layer and the tire cross-sectional width Wt (mm) when the tire is mounted on a standard rim and the internal pressure is set to 250 kPa satisfy the following (Formula 1) and (Formula 2): e / (139.5-0.3Wt) > 1 ··· (Formula 1); e / (191.5-0.3Wt) < 1 ··· (Formula 2).

Description

Technical Field

[0001] The present invention relates to a pneumatic tire, and more specifically, to a pneumatic tire having a belt layer. Background Technology

[0002] In recent years, due to increasing concerns about environmental issues and considerations of economic efficiency, there has been a growing demand for improved fuel efficiency of motor vehicles and pneumatic tires (hereinafter referred to as "tires") installed in motor vehicles.

[0003] Tire fuel efficiency can be evaluated by rolling resistance, and it is known that the lower the rolling resistance, the higher the tire fuel efficiency.

[0004] Therefore, solutions have been proposed in the past to reduce rolling resistance by designing the formulation of the rubber composition constituting the tread of the tire (for example, Patent Documents 1-4).

[0005] [Existing Technical Documents]

[0006] [Patent Literature]

[0007] Patent Document 1: JP 2018-178034 A

[0008] Patent Document 2: JP 2019-089911 A

[0009] Patent Document 3: WO 2018 / 186367 A

[0010] Patent Document 4: JP 2019-206643 A Summary of the Invention

[0011] [The problem this invention aims to solve]

[0012] However, with the development of highways in recent years, the opportunities for long-distance travel at high speeds have increased dramatically. Under these circumstances, tires manufactured using the existing technologies mentioned above cannot maintain sufficient durability at high speeds and require further improvement.

[0013] Therefore, the object of the present invention is to provide a pneumatic tire with excellent durability at high speeds.

[0014] [Methods used to solve problems]

[0015] After conducting in-depth research on how to solve the above problems, the inventors discovered that the above problems can be solved through the invention described below, thus completing the present invention.

[0016] The present invention is:

[0017] A pneumatic tire having a sidewall and a belt layer, wherein,

[0018] The belt layer uses monofilament cords as reinforcing cords, and

[0019] The number of monofilament cords e (number of cords / 5cm) arranged in the radial section of the belt layer of the tire in the tire width direction and the tire section width Wt (mm) when the tire is mounted on a standard rim and the internal pressure is set to 250kPa satisfy the following (Equation 1) and (Equation 2).

[0020] e / (139.5 - 0.3Wt)>1····· (Equation 1)

[0021] e / (191.5 - 0.3Wt)<1····· (Equation 2)

[0022] The effects of the invention

[0023] According to the present invention, a pneumatic tire with excellent durability at high speeds can be provided. Detailed Implementation

[0024] [1] Features of the tire of the present invention

[0025] First, the features of the tire of the present invention will be described.

[0026] 1. Overview

[0027] The tire of the present invention is a pneumatic tire having a sidewall and a belt layer, wherein the belt layer uses monofilament cords as reinforcing cords. Then, the number of monofilament cords arranged per 5 cm in the tire width direction in the radial section of the belt layer (hereinafter also referred to as "density (ends)") e (number of cords / 5cm) and the tire section width Wt (mm) when the tire is mounted on a standard rim and the internal pressure is set to 250 kPa satisfy: e / (139.5-0.3Wt)>1 (Equation 1), and e / (191.5-0.3Wt)<1 (Equation 2).

[0028] By having such features, as described later, a pneumatic tire with excellent durability at high speeds can be provided.

[0029] In the above description, the tire cross-section width Wt refers to the width obtained by subtracting all the patterns, characters, etc. on the tire sidewall from the straight distance between the tire sidewalls (the total width of the tire), including all the patterns, characters, etc. on the tire sidewall, when the tire is mounted on a standard rim, the internal pressure is set to 250 kPa, and no load is applied.

[0030] Here, "standard rim" refers to the rim specified for each tire within a standards system, including the standards upon which the tire is based. For example, in the case of JATMA, it refers to the standard rim of the applicable size listed in the "JATMA YEAR BOOK"; in the case of ETRTO (The European Tire and Rim Technical Organization), 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". For tires not specified in the specifications, it refers to the rim that can be assembled with a rim and maintain internal pressure, that is, the rim with the smallest diameter and the narrowest width among rims that will not leak air between the rim and the tire.

[0031] Furthermore, the number of monofilament cords arranged per 5 cm in the tire width direction (density (ends)) e (number of cords / 5cm) can be expressed by measuring the number of monofilament cords within ±2.5 to 5.0 cm of the equatorial plane in the tire cross-section and converting it into the number of cords per 5 cm. Specifically, the number of cords arranged e (number of cords / 5cm) is preferably 55 or more, more preferably 65 or more, even more preferably 68 or more, particularly preferably 75 or more, and especially preferably greater than 80 cords / 5cm. On the other hand, it is preferably less than 150 cords / 5cm, more preferably less than 110 cords / 5cm, even more preferably less than 95 cords / 5cm, and especially preferably less than 85 cords / 5cm.

[0032] The outer diameter d (mm) of the monofilament cord is not particularly limited, but it is preferably 0.1 mm or more, more preferably 0.2 mm or more. On the other hand, it is preferably 0.5 mm or less, more preferably 0.4 mm or less, and particularly preferably 0.3 mm.

[0033] Furthermore, the "cord outer diameter" mentioned above refers to the outer diameter of the cord in the direction parallel to the tire width direction of the monofilament cord in the belt layer of the tire cross section. It can be the average value of the cord outer diameter in the direction parallel to the tire width direction measured when calculating density e (cords / 5cm).

[0034] 2. The mechanism by which the effect of the tire of this invention is manifested.

[0035] The mechanism by which the tire of the present invention exhibits its effect, namely, the mechanism by which it can provide a pneumatic tire with excellent durability at high speeds, is speculated as follows.

[0036] To reduce rolling resistance, one might consider reducing tire weight. As a specific means of doing so, one might consider using monofilament cords as reinforcing cords in the belt layer.

[0037] However, because monofilament cords cannot twist (reverse) and cannot bend, if they are densely packed in a tire with a wide tread width, the tread ring stiffness may become excessively high. Such a tire will experience severe sidewall deformation and tire damage when driving over bumps at high speeds, potentially leading to decreased durability at high speeds. Furthermore, such tires tend to transmit road imperfections more easily, which can result in reduced ride comfort.

[0038] Therefore, as a countermeasure, one could consider sparsely arranging the monofilament cords according to the tread width. By sparsely arranging the monofilament cords, the rigidity of the tread rings will not become too high, and impacts will be more easily absorbed in the tread area. This is believed to reduce deformation of the sidewall, suppress impact damage to the sidewall during high-speed driving, and improve tire durability.

[0039] However, on the other hand, if the arrangement of the monofilament cords becomes too sparse, the tread layer will be less constrained by the belt layer, resulting in greater tread deformation at high speeds and a risk of tread damage. Therefore, as the tread width increases, the number of monofilament cords is increased to prevent the belt layer from becoming too sparse, thereby maintaining the constraint of the belt layer, suppressing tread damage, and thus improving durability at high speeds.

[0040] As described above, the inventors believe that tread width, i.e., tire cross-sectional width Wt (mm), and the number of monofilament cords e (cord number / 5cm) are parameters related to tire durability at high speeds. Experiments and studies were conducted to investigate the favorable relationship between the number of monofilament cords e (cord number / 5cm) and tread width (i.e., tire cross-sectional width Wt (mm)). As a result, the inventors discovered that when the conditions e / (139.5-0.3Wt)>1 (Equation 1) and e / (191.5-0.3Wt)<1 (Equation 2) are met, high-speed durability can be improved, thus completing this invention.

[0041] In this case, as the tire cross-sectional width Wt (tread width) increases, the total number of monofilament cords arranged on the tread surface increases, so it is believed that the density can be gradually reduced.

[0042] In the above description, the specific [e / (139.5-0.3Wt)] is preferably 1.01 or more, more preferably 1.02 or more, further preferably 1.12 or more, particularly preferably 1.14 or more, especially preferably 1.20 or more, even more preferably 1.22 or more, particularly preferably 1.64 or more, and most preferably 1.76 or more.

[0043] Furthermore, the specific [e / (191.5-0.3Wt)] is preferably 0.92 or less, more preferably 0.90 or less, even more preferably 0.67 or less, particularly preferably 0.63 or less, especially preferably 0.62 or less, even more preferably 0.61 or less, especially more preferably 0.59 or less, especially preferably 0.57 or less, and most preferably 0.52 or less.

[0044] As a result of further experiments and research, it was found that the tire cross-section width Wt is preferably 125mm or more and 300mm or less. When the tire cross-section width Wt is 215mm or more, it is preferred that, in addition to satisfying (Equation 1) and (Equation 2), e / (110.84-0.1667Wt)>1 (Equation 3).

[0045] In the above description, the specific tire cross-section width Wt is preferably 216 mm or more, more preferably 217 mm or more, further preferably 218 mm or more, particularly preferably 240 mm or more, especially preferably 241 mm or more, even more preferably 242 mm or more, especially preferably 285 mm or more, especially more preferably 286 mm or more, and most preferably 287 mm or more.

[0046] Specifically, [e / (110.84-0.1667Wt)] is preferably 1.01 or more, more preferably 1.03 or more, even more preferably 1.06 or more, particularly preferably 1.14 or more, especially preferably 1.50 or more, and even more preferably 1.56 or more.

[0047] [2] A more preferred embodiment of the tire of the present invention

[0048] The tire of the present invention can achieve further and greater effects by employing the following methods.

[0049] 1. The relationship between the complex elastic modulus of the tire sidewall rubber composition and the height of the tire sidewall.

[0050] Further experiments and research by the inventors revealed that, in addition to the improvements in the belt layer, the improvement in durability at high speeds is also related to the rigidity of the tire sidewall rubber composition.

[0051] In other words, if the sidewall rubber composition is highly rigid and the sidewall height is low, stress will concentrate on the sidewall when it is subjected to impact from the tread, making it prone to impact rupture. Furthermore, if the sidewall rubber composition is highly rigid, it cannot absorb impact from the tread like a cushioning pad, which may lead to tread damage.

[0052] If the rigidity of the sidewall rubber composition is controlled according to the height of the sidewall, making the sidewall flexible, then even when the sidewall is subjected to force, stress concentration will not occur, and since it can also absorb impact, it is believed that tread damage can be suppressed. Therefore, the inventors conducted experiments and research on the relationship between the complex elastic modulus of the sidewall rubber composition and the height of the sidewall.

[0053] The results showed that when the complex elastic modulus E* (MPa) and the sidewall height T (mm) measured under the conditions of temperature: 70℃, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, and deformation mode: tension, the durability at high speeds was further improved when (E* / T)×100≦3.0 (Equation 4).

[0054] The complex elastic modulus E* of the tire sidewall rubber composition can be measured, for example, using a viscoelasticity measuring device such as the "Eplexor" (registered trademark) manufactured by GABO. The complex elastic modulus E* is preferably 1.5 MPa or more, more preferably 2.0 MPa or more, even more preferably 2.5 MPa or more, and particularly 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, even more preferably 4.1 MPa or less, and particularly preferably 4.0 MPa or less.

[0055] The sidewall height T can be obtained by subtracting the rim diameter R (mm) from dt (mm), where dt (mm) is the outer diameter of the tire mounted on a standard rim, and the internal pressure is set to 250 kPa.

[0056] The specific sidewall height T is preferably 100.0 mm or more, more preferably 128.9 mm or more, and even more preferably 150.8 mm or more.

[0057] In this invention, the specific value of (E* / T)×100 is preferably 2.72 or less, more preferably 2.50 or less, and even more preferably 2.48 or less.

[0058] 2. Angle of the reinforcing cord (monoskeleton cord)

[0059] The angle between the reinforcing cord (monofilament cord) of the belt layer and a straight line parallel to the tire circumference is preferably 10° or more, more preferably 15° or more, even more preferably 20° or more, and particularly preferably 23° or more. On the other hand, it is preferably 35° or less, more preferably 33° or less, and even more preferably 30° or less.

[0060] By arranging the monofilament cords of the belt layer at this angle, a hoop effect can be achieved, firmly restraining almost the entire width of the tread and suppressing tread deformation during rolling. Therefore, it improves durability at high speeds.

[0061] 3. Multilayering of the belt layer

[0062] In this invention, preferably, the belt layer is multi-layered by providing at least two layers, and in at least one group of belt layers adjacent to each other in the radial direction of the tire, the average distance D (mm) between the tread belt layers is 0.5 mm or less. This distance D is more preferably 0.45 mm or less, even more preferably 0.4 mm or less, and particularly preferably 0.22 mm or less.

[0063] The "average distance D between the belt layers" referred to here is the average distance between the monofilaments of the belt layers, which is equal to the distance between the outer surface of the monofilament of the inner belt layer and the inner surface of the monofilament of the outer belt layer on the equatorial plane.

[0064] 4. Belt reinforcement layer

[0065] In this invention, when a belt reinforcement layer is provided on the radially outer side of the tire starting from the belt layer, deformation of the tread area can be further suppressed, and durability at high speeds can be improved, which is therefore preferred. In this case, preferably, the average distance between the monofilament cords in the belt layer and the cords in the belt reinforcement layer is 0.1 mm or more and 0.5 mm or less.

[0066] 5. Grooves in the tire tread

[0067] The tire of the present invention has circumferential grooves extending continuously in the circumferential direction on the tread. Preferably, the groove width L at 80% of the maximum depth of the circumferential groove is... 80 The ratio L to the circumferential groove width L0 at the tread contact surface 80 / L0 is preferably between 0.3 and 0.7. This suppresses movement of the entire landmass on the land surface of the tread, improving durability at high speeds. 80 / L0 is more preferably 0.35 or more, and even more preferably 0.40 or more. On the other hand, it is more preferably 0.65 or less, and even more preferably 0.60 or less.

[0068] The L0 and L 80 These refer to the straight-line distance (L0) between the ends of the grooves on the surface of the circumferential grooves of the tire tread when 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% of the groove depth. 80 Simply put, it can be determined by pressing the bead portion of a section cut radially from the tire with a width of 2 to 4 cm against the rim width.

[0069] Preferably, the tread portion has multiple circumferential grooves, and the total cross-sectional area of ​​the multiple circumferential grooves is 10% or more and 30% or less of the tread portion's cross-sectional area. This suppresses tread portion movement and improves durability at high speeds. More preferably, it is 15% or more, and even more preferably, 18% or more. On the other hand, it is more preferably 27% or less, and even more preferably 25% or less.

[0070] The cross-sectional area of ​​the circumferential groove refers to the total area formed by the straight line connecting the ends of the 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. Simply put, it can be calculated by pressing the bead portion of a radially cut section from the tire (2-4 cm wide) against the rim width.

[0071] The tread cross-sectional area refers to the area on the radial outer side of the tire in a tire radial section mounted on a standard rim under an internal pressure of 250 kPa and no load. This area is separated by a straight line connecting the ends of the circumferential grooves of the tread and by two straight lines parallel to the equatorial plane, passing through the tread surface profile formed by the tread surface and the two widest ends of the belt layer. When a belt reinforcement layer using organic fibers and / or steel cords is configured on the radial outer side of the belt layer, it refers to the area on the radial outer side of the belt reinforcement layer.

[0072] Furthermore, preferably, the tread portion has a plurality of lateral grooves extending axially along the tire, the total volume of which is 2.0% or more and 5.0% or less of the tread portion volume. This can suppress tread portion movement and improve durability at high speeds. More preferably, it is 2.2% or more, further preferably 2.5% or more, and particularly preferably 2.7% or more. On the other hand, more preferably, it is 4.0% or less, further preferably 3.5% or less, and particularly preferably 3.0% or less.

[0073] The volume of the lateral grooves refers to the total volume formed by the surfaces 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. It can be calculated by calculating the volume of each lateral groove and then summing the results. Furthermore, the tread volume can be calculated by multiplying the tread area by the outer diameter and then finding the difference between the product and the lateral groove volume.

[0074] [3] Implementation

[0075] The present invention will be specifically described below based on its implementation methods.

[0076] A. Belt layer

[0077] In the tire of this embodiment, the belt layer is manufactured by coating both sides of monofilament cords arranged at a predetermined density with a rubber composition constituting the belt layer (belt layer rubber composition), and the belt layer is used to manufacture belt components.

[0078] B. Side of the tire

[0079] In the tire of this embodiment, the sidewall portion is manufactured by molding the following sidewall rubber composition into a predetermined shape.

[0080] 1. Sidewall rubber composition

[0081] (1) Compound materials

[0082] The tire sidewall rubber composition can be obtained from the following rubber components and other compounding materials.

[0083] (a) Rubber composition

[0084] In this embodiment, the rubber composition is not particularly limited, and commonly used rubbers (polymers) in tire manufacturing can be used, such as isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), and butyl rubber. However, considering the formation of a phase-separated structure and the reduced likelihood of cracking during deformation, isoprene rubber and butadiene rubber are preferred. It should be noted that SBR and other rubber components can be used together as needed.

[0085] (a-1) Isoprene-based rubber

[0086] From the perspective of exhibiting good tensile strength and being less prone to damage such as cracks caused by deformation, the content (total content) of isoprene-based rubber in 100 parts by weight of the rubber component is preferably 40 parts by weight or more, more preferably 50 parts by weight or more, and even more preferably 55 parts by weight or more. On the other hand, from the perspective of forming a phase-separated structure with other rubber components and preventing the development of internal cracks and fractures in the rubber, it is preferably 90 parts by weight or less, more preferably 80 parts by weight or less, and even more preferably 65 parts by weight or less.

[0087] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR and modified IR, but NR is preferred from the perspective of superior strength.

[0088] For example, NRs commonly used in the tire industry, such as SIR20, RSS#3, and TSR20, can be used. IRs are not particularly limited; for example, IRs commonly used in the tire industry, such as IR2200, can be used. Examples of modified NRs include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Examples of modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These can be used alone or in combination of two or more.

[0089] (a-2)BR

[0090] In this embodiment, BR and NR are preferably used together as rubber components. From the perspective of suppressing crack and fracture development, 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.

[0091] The weight-average molecular weight of BR is, for example, greater than 100,000 and less than 2,000,000. The vinyl bonding content of BR (the amount of 1,2-bonded butadiene units) 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 less than 98% by mass. The trans content of BR is, for example, greater than 1% by mass and less than 60% by mass. The cis content can be determined by infrared absorption spectroscopy.

[0092] There are no particular limitations on BR. BR with high cis content (cis content of 90% or more) or low cis content or containing isotactic polybutadiene crystals can be used. BR can be unmodified or modified. Modified BR can be, for example, S-modified BR modified with a compound (modifier) ​​represented by the following formula.

[0093] [Chemistry 1]

[0094]

[0095] In the formula, R 1 R 2 and R 3 Same or different, indicating alkyl, alkoxy, silyloxy, acetal, carboxyl (-COOH), mercapto (-SH) or their derivatives. R 4 and R 5 Same or different, indicating hydrogen atoms or alkyl groups. R 4 and R 5 It can combine with nitrogen atoms to form a ring structure. n represents an integer.

[0096] Examples of modified BRs modified with compounds (modifiers) represented by the above formula include BRs whose polymer ends (active ends) have been modified with compounds represented by the above formula.

[0097] R 1 R 2 and R 3 Preferably, it is an alkoxy group (preferably an alkoxy group with 1 to 8 carbon atoms, more preferably an alkoxy group with 1 to 4 carbon atoms). As R 4 and R 5 Alkyl groups (preferably alkyl groups with 1 to 3 carbon atoms) are suitable. n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. Furthermore, in R... 4 and R 5 When combined with nitrogen atoms to form a ring structure, it is preferably a 4- to 8-membered ring. Alkoxy groups also include cycloalkoxy groups (such as cyclohexyloxy) and aryloxy groups (such as phenoxy and benzyloxy).

[0098] Specific examples of modifiers include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. These can be used alone or in combination of two or more.

[0099] As a modified BR, modified BR can also be used with the following compounds (modifiers). Examples of modifiers include:

[0100] Polyhydric alcohol polyglycidyl ethers, such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolethane triglycidyl ether and trimethylolpropane triglycidyl ether;

[0101] Polyglycidyl ethers of aromatic compounds having two or more phenolic groups, such as bisphenol A diglycidyl ether;

[0102] Polyepoxides, such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene and polyepoxide liquid polybutadiene;

[0103] Tertiary amines containing epoxy groups, such as 4,4'-diglycidyl diphenylmethylamine and 4,4'-diglycidyl dibenzylmethylamine;

[0104] Diglycidylamino compounds, such as diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl-o-toluidine, tetraglycidyl-m-xylyldiamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-diaminomethylcyclohexane;

[0105] Acyl chlorides containing amino groups, such as bis-(1-methylpropyl)carbamoyl chloride, 4-morpholine carbamoyl chloride, 1-pyrrolidine carbamoyl chloride, N,N-dimethylcarbamoyl chloride, and N,N-diethylcarbamoyl chloride;

[0106] Silane compounds containing epoxy groups, such as 1,3-bis-(glycidoxypropyl)-tetramethyldisiloxane and (3-glycidoxypropyl)-pentamethyldisiloxane;

[0107] Silane compounds containing sulfide groups, such as (trimethylsilyl)[3-(trimethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(tripropoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldipropoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide;

[0108] N-substituted nitrogen-containing heterocyclic propane compounds, such as ethyleneimine and propyleneimine;

[0109] Alkoxysilanes, such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane;

[0110] (Thio)benzophenone compounds having an amino group and / or substituted amino groups, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-tert-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;

[0111] Benzaldehyde compounds having an amino group and / or substituted amino group, such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde;

[0112] N-substituted pyrrolidones, such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone;

[0113] N-substituted piperidinones, such as N-methyl-2-piperidinone, N-vinyl-2-piperidinone, N-phenyl-2-piperidinone; and

[0114] N-substituted lactams, such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurolactam, N-vinyl-ω-laurolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam.

[0115] In addition, examples include N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-triones, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethylidene urea, 1,3-divinylethylidene urea, 1,3-diethyl-2-imidazolinone, 1-methyl-3-ethyl-2-imidazolinone, 4-N,N-dimethylaminoacetophenone, 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.

[0116] As a modified BR, tin-modified BR can also be used, for example. Tin-modified BR is obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound. BR further modified with tin-carbon bond ends is preferred.

[0117] Examples of lithium initiators include lithium compounds such as alkyllithium, aryllithium, vinyllithium, organotin lithium, and organonitrile lithium compounds, as well as lithium metal. By using lithium initiators as initiators for tin-modified BR, tin-modified BR with high vinyl content and low cis content can be produced.

[0118] Examples of tin compounds include tin tetrachloride, butyltin trichloride, dibutyltin dichloride, dioctyltin dichloride, tributyltin chloride, triphenyltin chloride, diphenyl dibutyltin, triphenylethoxytin, diphenyl dimethyltin, xylyltin chloride, diphenyl dioctanoate, divinyl diethyltin, tetrabenzyltin, dibutyl distearate, tetraallyltin, and p-(tributyltin)styrene.

[0119] The tin atom content in the 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.

[0120] Furthermore, the molecular weight distribution (Mw / Mn) of the tin-modified BR is preferably 2 or less, and more preferably 1.5 or less.

[0121] Furthermore, the vinyl bonding content in the tin-modified BR is preferably 5% by mass or more, more preferably 7% by mass or more. On the other hand, the vinyl bonding content in the tin-modified BR is preferably 50% by mass or less, more preferably 20% by mass or less.

[0122] The S-modified BR and tin-modified BR mentioned above can be used alone or in combination of two or more.

[0123] As a BR (Brandinger), products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation can be used.

[0124] (a-3)SBR

[0125] In this embodiment, the rubber component may optionally contain 5 to 25 parts by weight of SBR and NR, or may be used in combination with the above-mentioned BR.

[0126] The weight-average molecular weight of the SBR is, for example, greater than 100,000 and less than 2 million. The styrene content of the SBR is preferably greater than 5% by mass, more preferably greater than 10% by mass, and even more preferably greater 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 vinyl bond content of the SBR is, for example, greater than 5% by mass and less than 70% by mass. The structural identification of the SBR (determination of styrene content and vinyl bond content) can be performed using, for example, a device from the JNM-ECA series manufactured by JEOL Ltd.

[0127] There are no particular limitations on SBR; for example, emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR) can be used. SBR can be unmodified or modified. These can be used alone or in combination of two or more.

[0128] The modified SBR can be any SBR having functional groups that interact with fillers (such as silica). Examples include: end-modified SBRs in which at least one end of an SBR is modified with a compound (modifier) ​​having the aforementioned functional groups (end-modified SBRs with the aforementioned functional groups at the end), main-chain modified SBRs with the aforementioned functional groups in the main chain, and main-chain end-modified SBRs with the aforementioned functional groups in both the main chain and the ends (e.g., main-chain end-modified SBRs with the aforementioned functional groups in the main chain and at least one end modified with the aforementioned modifier), and end-modified SBRs modified (coupled) by a polyfunctional compound having two or more epoxy groups in the molecule and introducing hydroxyl or epoxy groups.

[0129] As an SBR (Self-Borne Technology Reactor), SBRs manufactured and sold by companies such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation can be used. SBRs can be used alone or in combination of two or more types.

[0130] (a-4) Other rubber components

[0131] In addition, as other rubber components, rubber (polymers) commonly used in tire manufacturing, such as nitrile rubber (NBR), may be included as needed.

[0132] (b) Compounds other than rubber components

[0133] (b-1) Packing

[0134] In this embodiment, the tire sidewall rubber composition preferably contains fillers. Specific examples of fillers include silica, carbon black, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. Carbon black is preferably used as a reinforcing agent. Furthermore, silica is preferably used as a reinforcing agent as needed, in which case it is preferably used in conjunction with a silane coupling agent.

[0135] (i) Carbon black

[0136] The sidewall rubber composition preferably contains carbon black. The carbon black content relative to 100 parts by weight of the rubber component is preferably 10 parts by weight or more and 100 parts by weight or less, more preferably 15 parts by weight or more and 60 parts by weight or less, and even more preferably 25 parts by weight or more and 55 parts by weight or less.

[0137] Carbon black is not particularly limited, but examples include: furnace black (furnace black), such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black; thermal cracking black (thermal cracking black), such as FT and MT; and channel black (channel black), such as EPC, MPC, and CC. One of these can be used alone, and two or more can be used in combination.

[0138] The nitrogen adsorption specific surface area (N2SA) of carbon black is, for example, greater than 30 m². 2 / g and less than 250m 2 / g. The dibutyl phthalate (DBP) absorption of carbon black is, for example, greater than 50 ml / 100g and less than 250 ml / 100g. The nitrogen adsorption specific surface area of ​​carbon black was determined according to ASTM D4820-93, and the DBP absorption was determined according to ASTM D2414-93.

[0139] There are no specific limitations on the type of carbon black used, but examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include those from companies such as Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nikka Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These can be used individually or in combination of two or more.

[0140] (ii) Silicon dioxide

[0141] The sidewall rubber composition preferably further contains silica, if desired. From the perspective of obtaining good durability, the BET specific surface area of ​​silica is preferably greater than 140 m². 2 / g, more preferably greater than 160m 2 / g. On the other hand, considering the need for good rolling resistance at high speeds, it is preferable to have less than 250m. 2 / g, more preferably less than 220m 2 / g.

[0142] Furthermore, when not used in combination with a silane coupling agent, the silica content is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, relative to 100 parts by mass of the rubber component. On the other hand, it is preferably 25 parts by mass or less, 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 above-mentioned BET specific surface area is the N2SA value determined by the BET method according to ASTM D3037-93.

[0143] Examples of silica include dry silica (anhydrous silica) and wet silica (hydrated silica). Wet silica is preferred because it has a large number of silanol groups.

[0144] As silica, products from companies such as Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., and Tokuyama Co., Ltd. can be used.

[0145] (iii) Silane coupling agent

[0146] As mentioned above, when using silica, silane coupling agents can be used in conjunction. There are no particular limitations on the silane coupling agent, but examples include sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, and bis(4-triethoxysilylbutyl)tetrasulfide. bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylsulfonium Carbamoyl tetrasulfide, 2-triethoxysilyl ethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilyl propyl methacrylate monosulfide; mercapto-based silane coupling agents, such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z manufactured by Momentive; vinyl-based silane coupling agents, such as vinyltriethoxysilane and vinyltrimethoxysilane. Alkane; amino-based silane coupling agents, such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; epoxypropoxy-based silane coupling agents, such as γ-epoxypropoxypropyltriethoxysilane and γ-epoxypropoxypropyltrimethoxysilane; nitro-based silane coupling agents, such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; chloro(substituted) silane coupling agents, such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These can be used alone or in combination of two or more.

[0147] As silane coupling agents, products from companies such as Degussa, Momentive, Shin-Etsu Silicone, Tokyo Chemical Industries, Azumax, and Toray Corning can be used.

[0148] The content of silane coupling agent is, for example, greater than 3 parts by mass and less than 15 parts by mass relative to 100 parts by mass of silicon dioxide.

[0149] (iv) Other packing materials

[0150] In addition to the aforementioned carbon black and silica, the tire 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 content of these fillers relative to 100 parts by weight of the rubber component is, for example, greater than 0.1 parts by weight and less than 200 parts by weight.

[0151] (b-2) Curing resin components

[0152] As needed, the sidewall rubber composition may contain curing resin components, such as modified resorcinol resin and modified phenolic resin.

[0153] Specific examples of modified resorcinol resins include Sumikanol 620 (modified resorcinol resin) manufactured by Taoka Chemical Industry Co., Ltd., and examples of modified phenolic resins include PR12686 (cashew oil modified phenolic resin) manufactured by Sumitomo Bakelite Co., Ltd.

[0154] For example, from the perspective of fully improving the complex elastic modulus and obtaining a large reaction force during deformation, the content of the curable resin component is preferably 1 part by mass or more, and more preferably 2 parts by mass or more, relative to 100 parts by mass of the rubber component. On the other hand, from the perspective of maintaining the fracture strength, it is preferably 10 parts by mass or less, and more preferably 8 parts by mass or less.

[0155] When using modified resorcinol resin, it is preferable to also contain a methylene donor as a curing agent. Examples of methylene donors include hexamethylenetetramine (HMT), hexamethoxyhydroxymethyl melamine (HMMM), and hexamethyl hydroxymelamine pentamethyl ether (HMMPME). It is preferable to contain, for example, 5 parts by weight or more, up to about 15 parts by weight, relative to 100 parts by weight of the curable resin component. If this amount is too small, sufficient complex modulus of elasticity may not be obtained. On the other hand, if this amount is too large, the viscosity of the rubber may increase, and processability may deteriorate.

[0156] For example, Sumikanol 507 manufactured by Taoka Chemical Co., Ltd. can be used as a specific methylene donor.

[0157] (b-3) Plasticizer components

[0158] The rubber composition may contain oil (including filling oil) as a plasticizer component, liquid rubber, and resin as components that soften the rubber. The plasticizer component is a component that can be extracted from vulcanized rubber using acetone. The total content of the plasticizer component is preferably greater than 5 parts by weight, more preferably greater than 10 parts by weight, relative to 100 parts by weight of the rubber composition. On the other hand, it is preferably less than 70 parts by weight, more preferably less than 50 parts by weight, and even more preferably less than 30 parts by weight. The oil content also includes the amount of oil contained in the rubber (oil-extended rubber).

[0159] (i)Oil

[0160] Examples of oils include mineral oils (commonly referred to as processed oils), vegetable oils, or mixtures thereof. Mineral oils (processed oils) can include, for example, alkane-based processed oils, aromatic processed oils, cycloalkane-based processed oils, etc. 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 bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia oil, tung oil, etc. These can be used alone or in combination of two or more.

[0161] As specific processing oils (mineral oils), products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Oil & Chemical Co., Ltd., Nippon Energy Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Oil Co., Ltd., and Fuji Kosan Co., Ltd. can be used.

[0162] (ii) Liquid rubber

[0163] Liquid rubber, listed as a plasticizer, is a polymer that is liquid at room temperature (25°C) and is a rubber component that can be extracted from vulcanized tires using acetone extraction. Examples of liquid rubber include farnesene-based polymers, liquid diene-based polymers, and their hydrides.

[0164] Farnese polymers are polymers obtained by polymerizing farnese and have farnese-based building blocks. Farnese includes isomers such as α-farnese ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecathetene) and β-farnese (7,11-dimethyl-3-methylene-1,6,10-dodecathetene).

[0165] Farnese polymers can be homopolymers of farnese (farnese homopolymers) or copolymers of farnese and vinyl monomers (farnese-vinyl monomer copolymers).

[0166] 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).

[0167] The weight-average molecular weight (Mw) of polystyrene converted from liquid diene polymers by gel permeation chromatography is, for example, greater than 1.0 × 10⁻⁶. 3 Less than 2.0×10 5 In this specification, the Mw of the liquid diene polymer is a polystyrene conversion value determined by gel permeation chromatography (GPC).

[0168] The content of liquid rubber (the total content of liquid farnesoid polymers, liquid diene polymers, etc.) is, for example, greater than 1 part by mass and less than 100 parts by mass relative to 100 parts by mass of rubber component.

[0169] As a liquid rubber, products from companies such as Kuraray Corporation and Clay Valley can be used.

[0170] (iii) Resin composition

[0171] The resin component also functions as a tackifier and can be solid or liquid at room temperature. Specific examples of resin components include rosin-based resins, styrene-based resins, benzofuran-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, and two or more of them can be used in combination. The content of the resin component is preferably greater than 2 parts by weight and less than 45 parts by weight, more preferably less than 30 parts by weight, relative to 100 parts by weight of the rubber component.

[0172] Rosin-based resins are resins containing rosin acid, obtained from the processing of rosin, as their main component. These rosin-based resins (rosin derivatives) can be classified according to whether they are modified or not, into unmodified rosin and modified rosin derivatives. Unmodified rosin includes tall rosin (also known as tall oil rosin), resin rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosin. Modified rosin derivatives are modifications of unmodified rosin, and examples include rosin esters, unsaturated carboxylic acid-modified rosin derivatives, unsaturated carboxylic acid-modified rosin esters, rosin amide compounds, and rosin amine salts.

[0173] Styrene-based resins are polymers that use styrene-based monomers as constituent monomers. Examples include polymers obtained by polymerizing styrene-based monomers as the main component (50% by mass or more). Specifically, examples include homopolymers obtained by polymerizing styrene-based monomers alone (such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene), copolymers obtained by copolymerizing two or more styrene-based monomers, and copolymers obtained by copolymerizing styrene-based monomers and other monomers that can be copolymerized with styrene-based monomers.

[0174] Examples of other monomers mentioned above include: acrylonitriles, such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids, such as acrylic acid and methacrylic acid; unsaturated carboxylic acid esters, such as methyl acrylate and methyl methacrylate; dienes, such as chloroprene, butadiene and isoprene; alkenes, such as 1-butene and 1-pentene; and α,β-unsaturated carboxylic acids and their anhydrides, such as maleic anhydride.

[0175] Among benzofuran-based resins, benzofuran-indene resins are preferred. Benzofuran-indene resins are resins containing benzofuran and indene as monomeric components constituting the resin's backbone (main chain). Examples of monomeric components included in the backbone other than benzofuran and indene include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0176] The content of benzofuran-indene resin is, for example, greater than 1.0 part by weight and less than 50.0 parts by weight per 100 parts by weight of rubber component.

[0177] The hydroxyl value (OH value) of benzofuran-indene resin is, for example, greater than 15 mg KOH / g and less than 150 mg KOH / g. The OH value is the amount of potassium hydroxide required, expressed in milligrams, to neutralize the acetic acid bound to the hydroxyl groups when 1 g of resin is acetylated. The OH value is determined by potentiometric titration (JIS K 0070:1992).

[0178] The softening point of benzofuran-indene resin is, for example, greater than 30°C and less than 160°C. The softening point is the temperature at which the ball falls when the softening point specified in JIS K 6220-1:2001 is determined using a ring-and-ball softening point tester.

[0179] Examples of terpene resins include polyterpenes, terpenoid phenols, and aromatic modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrides. Terpene compounds are composed of (C5H8) resins. n The composition of hydrocarbons and their oxygen-containing derivatives is represented by the class of monoterpenes (C14-C24-C24-C24). 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 Compounds with terpenes as their basic skeleton, such as α-pinene, β-pinene, dipentene, limonene, myrcene, allociperene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinene oil, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0180] Examples of polyterpenes include terpene resins, such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin made from the aforementioned terpene compounds. Hydrogenated terpene resins obtained by hydrogenating these terpene resins can also be cited as examples. Examples of terpenoids and phenols include resins obtained by copolymerizing the aforementioned terpene compounds with phenolic compounds, and resins obtained by hydrogenating these resins. Specifically, resins obtained by condensing the aforementioned terpene compounds, phenolic compounds, and formalin can be given. Examples of phenolic compounds include phenol, bisphenol A, cresol, xylenol, etc. Examples of aromatic-modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating these resins. Regarding aromatic compounds, there are no particular limitations as long as they are compounds with aromatic rings. Examples include phenolic compounds such as phenol, alkylphenol, alkoxyphenol, and phenol containing unsaturated hydrocarbon groups; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and naphthol containing unsaturated hydrocarbon groups; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and styrene containing unsaturated hydrocarbon groups; benzofuran; indene; etc.

[0181] "C5 resin" refers to resin obtained by polymerizing C5 fractions. 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 preferred as a C5-based petroleum resin.

[0182] "C9 resin" refers to a resin obtained by polymerizing C9 fractions, which can be hydrogenated or modified. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples include benzofuran-indene resins, benzofuran resins, indene resins, and aromatic vinyl resins. As aromatic vinyl resins, homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene, are preferred due to their economy, ease of processing, and excellent exothermic properties. Copolymers of α-methylstyrene and styrene are more preferred. Commercially available products from companies such as Kraton and Eastman Chemical can be used as aromatic vinyl resins.

[0183] "C5C9 resin" refers to a resin obtained by copolymerizing the aforementioned C5 fraction and C9 fraction, which can be hydrogenated or modified. Examples of C5 and C9 fractions include the aforementioned petroleum fractions. Commercially available products from Tosoh Corporation, LUHUA Corporation, etc., can be used as C5C9 resins, for example.

[0184] There are no particular limitations on acrylic resins. For example, solvent-free acrylic resins can be used.

[0185] As a solvent-free acrylic resin, examples include high-temperature continuous polymerization (high-temperature continuous bulk polymerization) with minimal use of auxiliary raw materials such as polymerization initiators, chain transfer agents, and organic solvents.

[0186] (Meth)acrylic resins (polymers) synthesized using methods described in USP4,414,370, JP-A-S59-6207, JP-B-H5-58005, JP-A-H1-313522, USP5,010,166, and the East Asia Synthetic Research Annual Report TREND2000 No. 3, pp. 42-45. It should be noted that in this invention, "(meth)acrylic" refers to both methacrylic and acrylic resins.

[0187] Examples of monomeric components constituting the acrylic resin include (meth)acrylic acid derivatives, such as (meth)acrylic acid, (meth)acrylates (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylamide derivatives.

[0188] As monomer components constituting the acrylic resin, aromatic vinyl monomers (such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinylnaphthalene, etc.) and (meth)acrylic acid and / or (meth)acrylic acid derivatives may be used.

[0189] The acrylic resin may be a resin composed solely of (meth)acrylic acid components, or it may be a resin that also contains components other than (meth)acrylic acid components as constituents. The acrylic resin may contain hydroxyl, carboxyl, silanol, or other groups.

[0190] As a resin component, products from companies such as Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Corporation, Arizona Chemical Co., Ltd., Nippon Paint Co., Ltd., Nippon Shokubai Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., etc. can be used.

[0191] (b-4) Organic cobalt acid

[0192] If necessary, the sidewall rubber composition may contain cobalt organic acid.

[0193] Examples of cobalt organic acids include cobalt stearate, cobalt naphthenate, cobalt neodecanoate, and cobalt boron-3neodecanoate.

[0194] As for the cobalt concentration in the tire sidewall rubber composition, the content of cobalt organic acid is preferably 500 ppm or more, more preferably 700 ppm or more, and even more preferably 900 ppm or more. On the other hand, it is preferably 1500 ppm or less, more preferably 1300 ppm or less.

[0195] (b-5) Anti-reversion agent

[0196] As needed, the tire sidewall rubber composition preferably contains an anti-reversion agent. This can inhibit reversion and improve durability. The content of the anti-reversion agent relative to 100 parts by weight of the rubber component is preferably 0.1 parts by weight or more and 3 parts by weight or less, more preferably 0.2 parts by weight or more and 2.5 parts by weight or less, and even more preferably 0.3 parts by weight or more and 2 parts by weight or less. As a specific anti-reversion agent, for example, Perkalink 900 (1,3-bis(citrconium imide methyl)benzene) manufactured by Flexsys can be used.

[0197] (b-6) Anti-aging agents

[0198] The sidewall rubber composition preferably contains an antioxidant. The antioxidant content, relative to 100 parts by weight of the rubber component, is, for example, greater than 1 part by weight and less than 10 parts by weight.

[0199] Examples of antioxidants include: naphthylamine-based antioxidants, such as phenyl-α-naphthylamine; diphenylamine-based antioxidants, such as octyl diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based antioxidants, such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine; quinoline-based antioxidants, such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants, such as 2,6-di-tert-butyl-4-methylphenol and styreneated phenol; and bisphenol, triphenol, and polyphenol-based antioxidants, such as tetra-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. These can be used alone or in combination of two or more.

[0200] As an anti-aging agent, products from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Co., Ltd., and Flexsys can be used.

[0201] (b-7) Stearic acid

[0202] The tire sidewall rubber composition may contain stearic acid. The stearic acid content, relative to 100 parts by weight of the rubber component, is, for example, greater than 0.5 parts by weight and less than 10.0 parts by weight. As stearic acid, conventionally known stearic acids can be used, such as products from Nippon Oil Co., Ltd., NOF Corporation, Kao Corporation, Fujifilm, and Koh Geny Pharmaceutical Co., Ltd., and Chiba Fatty Acid Co., Ltd., etc.

[0203] (b-8) Zinc oxide

[0204] The tire sidewall rubber composition may contain zinc oxide. The zinc oxide content, relative to 100 parts by weight of the rubber component, is, for example, greater than 0.5 parts by weight and less than 15 parts by weight. Conventionally known zinc oxides can be used as the zinc oxide. For example, products from Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd., etc., can be used.

[0205] (b-9) Crosslinking agents and vulcanization accelerators

[0206] The sidewall rubber composition preferably contains a crosslinking agent, such as sulfur. The content of the crosslinking agent is, for example, greater than 0.1 parts by weight and less than 10.0 parts by weight relative to 100 parts by weight of the rubber component.

[0207] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, and soluble sulfur, which are commonly used in the rubber industry. These can be used alone or in combination of two or more.

[0208] For example, products from companies such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexsys Co., Ltd., Nippon Inkyu Corporation, and Hosoi Chemical Industry Co., Ltd. can be used as sulfur.

[0209] Examples of crosslinking agents other than sulfur include: sulfur-containing vulcanizing agents, such as Tackirol V200 manufactured by Taoka Chemical Industry Co., Ltd., Duralink HTS (sodium 1,6-hexamethylene dithiosulfate dihydrate) manufactured by Flexsys, and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyl dithiohexane)) manufactured by Lanxess; and organic peroxides, such as dicumyl peroxide.

[0210] The sidewall rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator relative to 100 parts by weight of the rubber component is, for example, greater than 0.3 parts by weight and less than 10.0 parts by weight.

[0211] Examples of vulcanization accelerators include: thiazole-based vulcanization accelerators, such as 2-mercaptobenzothiazole, di-2-benzothiazole disulfide, and N-cyclohexyl-2-benzothiazole sulfenamide; thiuram-based vulcanization accelerators, such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetra(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators, such as N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, N-oxoethylene-2-benzothiazole sulfenamide, N-oxoethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators, such as diphenylguanidine, di-o-tolylguanidine, and o-tolyl biguanide. These can be used individually or in combination of two or more.

[0212] (b-10) Other

[0213] In addition to the components mentioned above, the tire sidewall rubber composition may further contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, and organic peroxides. The content of these additives relative to 100 parts by weight of the rubber component is, for example, greater than 0.1 parts by weight and less than 200 parts by weight.

[0214] (2) Preparation of the sidewall rubber composition

[0215] The tire sidewall rubber composition is produced by conventional methods, for example, by a manufacturing method including the following steps: a basic mixing step of mixing the rubber components with fillers (such as carbon black), and a final mixing step of mixing the mixture obtained in the above basic mixing step with a crosslinking agent.

[0216] Mixing can be carried out using known (closed) mixing machines, such as Banbury mixers, kneaders, open rolls, etc.

[0217] The mixing temperature in the basic mixing step is, for example, greater than 50°C and less than 200°C, and the mixing time is, for example, greater than 30 seconds and less than 30 minutes. In addition to the above-mentioned components, commonly used compounding agents in the rubber industry (such as plasticizers (including oils), stearic acid, zinc oxide, antioxidants, waxes, vulcanization accelerators, etc.) may be added as needed during the basic mixing step.

[0218] In the final mixing step, the compound obtained in the basic mixing step is mixed with a crosslinking agent. The mixing temperature in the final mixing step is, for example, above room temperature and below 80°C, and the mixing time is, for example, above 1 minute and below 15 minutes. In addition to the above components, vulcanization accelerators, zinc oxide, etc., may be added as needed in the final mixing step.

[0219] (3) Fabrication of the sidewall

[0220] The sidewall portion can be manufactured by molding the obtained sidewall rubber composition into a predetermined shape.

[0221] C. Tire manufacturing

[0222] The tire of this embodiment can be manufactured as an uncured tire by the following method: on a tire forming machine, the belt component and sidewall portion obtained above are formed together with other tire components by conventional methods.

[0223] Specifically, on the forming drum, the inner liner, which serves as a component to ensure tire air tightness, the tire carcass, which serves as a component to withstand the load, impact, and air pressure of the tire, and the belt component, which serves as a component to strongly fasten the tire carcass and improve the tread rigidity, are wound up. Then, the two ends of the tire carcass are fixed to the two side edges, and the bead portion, which serves as a component to fix the tire to the rim, is formed into a ring. Subsequently, the tread is attached to the center of the outer periphery, and the sidewall is attached to the radially outer side to form the sidewall portion; thus, an uncured tire is produced.

[0224] In this embodiment, as described above, from the perspective of improving the restraint force on the tread during driving and easily suppressing outer diameter growth, the belt layer can be configured as multiple layers. In this case, the average distance D (mm) between the cords of the belt layers in the tread of the vulcanized tire is preferably 0.5 mm or less. Preferably, the angle between the monofilament cord in the tread and the straight line parallel to the tire circumference is 10° or more and 35° or less, and the cords of adjacent belt layers are arranged to intersect each other.

[0225] The angle of the monofilament cord is the angle of the monofilament cord relative to the tire circumference when the tire is not inflated, and can be determined by peeling the tread from the radially outer side of the tire.

[0226] The uncured tires are then heated and pressurized in a vulcanizing machine to obtain a tire. The vulcanization step can be carried out using known vulcanization methods. The vulcanization temperature is, for example, greater than 120°C and less than 200°C, and the vulcanization time is, for example, greater than 5 minutes and less than 15 minutes.

[0227] At this time, when the tire is mounted on a standard rim and has an internal pressure of 250 kPa, it is shaped to satisfy the above (Equation 1) and (Equation 2).

[0228] The specific tires preferably used in this invention include, for example, tires with size markings 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.

[0229] The tire of this embodiment can be used as various types of tires, such as passenger car tires, truck and bus tires, and two-wheeled vehicle tires. However, among tires that satisfy (Formula 1) and (Formula 2), it is preferable to apply them to passenger car tires, that is, tires mounted on four-wheeled vehicles with a maximum load capacity of 1000 kg or less. By satisfying (Formula 1) and (Formula 2), the tire can make a more advantageous contribution to solving the problem of the present invention (that is, providing a pneumatic tire with excellent durability at high speeds).

[0230] The aforementioned maximum load capacity refers to a value approximately 50 to 100 kg smaller than the maximum load capacity specified for each tire within a standard system, including the standard on which the tire is based, such as the load index (LI) specified by the JATMA standard (Japan Motor Vehicle Tire Association standard). Specifically, it is calculated using the following two formulas based on the tire's cross-sectional width Wt (mm), cross-sectional height Ht (mm), and outer diameter Dt (mm) when the tire is mounted on a standard rim with an internal pressure of 250 kPa and no load applied.

[0231] V(mm 3 )={(Dt / 2) 2 -(Dt / 2-Ht) 2}×π×Wt

[0232] WL (kg) = 0.000011 × V + 175

[0233] Here, V is the volume of space occupied by the tire (virtual volume), and (Dt / 2-Ht) is the rim diameter (mm).

[0234] The maximum load capacity is not particularly limited as long as it is below 1000 kg. 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 preferably below 900 kg, more preferably below 800 kg, and even more preferably below 700 kg.

[0235] From the perspective of mitigating the impact transmitted to the tire, the tire weight is preferably less than 20 kg, more preferably less than 15 kg, and even more preferably less than 12 kg, less than 10 kg, or less than 8 kg. The term "tire weight" used here refers to the weight of the entire tire, including components such as sealing materials, sponges, three-dimensional mesh structures, and electronic components disposed on the inner surface of the tire. The tire weight can be appropriately adjusted by the thickness and width of the various components constituting the tire, the specific gravity of the rubber composition, the number of steel cords in the belt reinforcement layer, and the structure of the bead wires.

[0236] [Example]

[0237] The present invention will be described in more detail below through embodiments.

[0238] 1. Fabrication of belt components

[0239] First, prepare 100 parts by weight of NR (RSS3), 55 parts by weight of carbon black (Show Black N326 manufactured by Cabot Japan Co., Ltd.), 0.5 parts by weight of crosslinking agent (Duralink HTS manufactured by Flexsys Co., Ltd.), 3 parts by weight of curing resin (PR12686 manufactured by Sumitomo Bakelite Co., Ltd.), 1.5 parts by weight of cobalt organic acid (DICNATE NBC-2 manufactured by DIC Co., Ltd.), 1.5 parts by weight of curing agent (Sumikanol 507 manufactured by Taoka Chemical Co., Ltd.), 10 parts by weight of zinc oxide (Zinc White No. 1 manufactured by Mitsui Metal Mining Co., Ltd.), 1 part by weight of antioxidant (Nocrac 6C manufactured by Ouchi New Chemical Industry Co., Ltd.), and 0.5 parts by weight of antioxidant (Antage manufactured by Kawaguchi Chemical Co., Ltd.). RD), 1 part by weight of stearic acid ("Tsubaki" manufactured by NOF Corporation), 7 parts by weight of sulfur (powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.) and 1.2 parts by weight of vulcanization accelerator (NOCCELER DZ manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) are used as compounding materials for rubber compositions for belts.

[0240] Next, using a Banbury internal mixer, the materials, except for the curing agent, sulfur, and vulcanization accelerator, are mixed at 150°C for 5 minutes to obtain a compound. Then, the curing agent, sulfur, and vulcanization accelerator are added to the obtained compound, and the mixture is mixed at 80°C for 5 minutes using a two-roll mill to obtain a rubber composition for belts.

[0241] Next, steel cords with the configuration and cord outer diameter (mm) shown in Tables 1 and 2 are arranged according to the density (cords / 5cm) shown in Tables 1 and 2. The aforementioned belt-type rubber composition is then applied to both sides of the steel cords to create a belt-type component. At this point, the steel cords are arranged in the center of the belt-type component in the thickness direction, and the same amount of rubber is applied to its top and bottom. After the tire is vulcanized, the thickness of the belt-type component is appropriately adjusted so that the steel cords between one set of belt layers have an average distance D (mm) as shown in Tables 1 and 2.

[0242] 2. Fabrication of the tire sidewall

[0243] The sidewall rubber composition is used separately to make the sidewall portion of the tire.

[0244] (1) Compounding materials of the tire sidewall rubber composition

[0245] First, prepare the following compounding materials.

[0246] (a) Rubber composition

[0247] (a-1)NR:TSR20

[0248] (a-2)BR: UBEPOL-BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by weight)

[0249] (b) Compounds other than rubber components

[0250] (b-1) Carbon black: Show Black N550 (N2SA: 42m) manufactured by Cabot Japan Co., Ltd. 2 / g, DOP oil absorption: 115ml / 100g)

[0251] (b-2) Oil: Process X-140 manufactured by Nippon Energy Corporation.

[0252] (b-3) Wax: Sunnoc Wax manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0253] (b-4) Antioxidant-1: Nocrac 6C (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0254] (b-5) Antioxidant-2: Antage RD (2,2,4-trimethyl-1,2-dihydroquinoline) manufactured by Kawaguchi Chemical Industry Co., Ltd.

[0255] (b-6) Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Metals Mining Co., Ltd.

[0256] (b-7) Stearic acid: NOF Corporation's stearic acid "Tsubaki"

[0257] (b-8) Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

[0258] (b-9) Vulcanization accelerator: NOCCELERNS (N-tert-butyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0259] (2) Manufacturing of the tire sidewall rubber composition

[0260] According to the formulations shown in Tables 1 and 2, the materials, excluding sulfur and vulcanization accelerator, were mixed for 5 minutes at 150°C using a Banbury internal mixer to obtain the compound. The amounts of each compound are parts by weight.

[0261] Next, sulfur and vulcanization accelerator are added to the obtained compound, and the mixture is kneaded for 5 minutes at 80°C using a two-roll mill to obtain a tire sidewall rubber composition.

[0262] Next, using the obtained sidewall rubber composition, a sidewall portion with a predetermined shape is made.

[0263] 3. Tire manufacturing

[0264] The sidewall portion obtained above and the belt component, which is made by bonding the aforementioned two layers of belt component together such that the steel cords in the component intersect each other at angles shown in Tables 1 to 4 relative to straight lines parallel to the tire circumference, are bonded together with other tire components to form an uncured tire. Then, the uncured tire is pressurized and vulcanized at 170°C for 10 minutes to manufacture various test tires (Examples 1 to 13 and Comparative Examples 1 to 7) with various sizes shown in Tables 1 and 2.

[0265] Among the tested tires, the aforementioned (L) 80 The total cross-sectional area of ​​the circumferential grooves is 22% of the tread cross-sectional area, and the total volume of the transverse grooves is 3.5% of the tread volume.

[0266] 4. Parameter Calculation

[0267] Then, the cross-sectional width Wt (mm) and sidewall height T (mm) of each test tire were determined. Rubber compositions were cut from the sidewall of each test tire to prepare viscoelasticity test pieces with a length of 40 mm and a width of 4 mm. Using the Eplexor series manufactured by GABO, E* (MPa) was measured under the following conditions: temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, deformation mode: elongation. The results are shown in Tables 1 and 2. For tires using the same rubber composition, the viscoelasticity of each specification of rubber composition was measured, and the results are shown as average values.

[0268] Then, using the obtained results, calculate “e / (139.5-0.3Wt)”, “e / (191.5-0.3Wt)”, “e / (110.84-0.1667Wt)”, and “(E* / T)×100”.

[0269] 5. Performance evaluation test (durability performance evaluation)

[0270] All test tires were installed on all wheels of the vehicle (a Japanese-made FF vehicle with a 2000cc engine). After inflating the tires to an internal pressure of 250 kPa, the vehicle was driven 10 times on a dry test track at a speed of 50 km / h under overload conditions. Then, it was driven repeatedly at a speed of 80 km / h on an uneven road surface. The vehicle was then driven laps at 50 km / h again, and the speed was gradually increased. The speed at which the driver felt an abnormality was measured.

[0271] Next, the result from Comparative Example 2 was set to 100, and the result was exponentialized based on the following formula to evaluate the durability performance relatively. The higher the value, the better the durability performance.

[0272] Durability: = [(Result of test tire) / (Result of Comparative Example 2)] × 100

[0273] The evaluation results are shown in Tables 1 and 2.

[0274] [Table 1]

[0275]

[0276] [Table 2]

[0277]

[0278] According to the results shown in Tables 1 and 2, when monofilament cords are used as the belt layer of the reinforcing cord to meet the above (Equation 1) and (Equation 2), a pneumatic tire with excellent durability at high speeds can be provided.

[0279] In addition, it is known that when the density is greater than 80 cords / 5cm, or when the sidewall meets (E* / T)×100≦3.0 (Equation 4), a pneumatic tire with further improved durability at high speeds can be provided.

[0280] Although the present invention has been described above based on embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments within the same and equivalent scope as the present invention.

[0281] The present invention (1) is:

[0282] A pneumatic tire having a sidewall and a belt layer, wherein,

[0283] The belt layer uses monofilament cords as reinforcing cords.

[0284] The number of monofilament cords e (number of cords / 5cm) arranged in the radial section of the tire in the tire width direction and the tire section width Wt (mm) when the tire is mounted on a standard rim with an internal pressure of 250kPa satisfy the following (Equation 1) and (Equation 2).

[0285] e / (139.5-0.3Wt)>1····· (Equation 1)

[0286] e / (191.5-0.3Wt)<1····· (Equation 2)

[0287] The present invention (2) is an inflatable tire according to the present invention (1), wherein the tire cross-sectional width Wt is 125 mm or more and 300 mm or less.

[0288] The present invention (3) is an inflatable tire according to the present invention (1) or (2), wherein the tire cross-sectional width Wt (mm) is 215mm or more, and satisfies the following (Equation 3).

[0289] e / (110.84-0.1667Wt)>1····· (Equation 3)

[0290] The present invention (4) is an inflatable tire according to any one of (1) to (3) of the present invention, wherein the outer diameter of the monofilament cord is 0.1 mm or more and 0.5 mm or less.

[0291] The present invention (5) is an inflatable tire according to any one of (1) to (4) of the present invention, wherein the number of single cords e (number of cords / 5cm) per 5cm in the tire width direction is greater than 80 cords / 5cm.

[0292] The present invention (6) is a pneumatic tire according to any one of (1) to (5) of the present invention, wherein the complex elastic modulus E* (MPa) and the height T (mm) of the sidewall rubber composition in the sidewall portion, measured under the conditions of temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz and deformation mode: elongation, satisfy the following (Equation 4).

[0293] (E* / T)×100≦3.0·····(Equation 4)

[0294] The present invention (7) is a pneumatic tire according to any one of (1) to (6) of the present invention, wherein the angle formed by the reinforcing cord of the belt layer and the straight line parallel to the tire circumference is 10° or more and 35° or less.

[0295] The present invention (8) is a pneumatic tire according to any one of (1) to (7) of the present invention, wherein at least two belt layers are provided, and at least one group of belt layers adjacent to each other in the radial direction of the tire are arranged at a spacing of less than 0.5 mm.

[0296] The present invention (9) is a pneumatic tire according to any one of (1) to (8), wherein the tread has circumferential grooves extending continuously in the tire circumferential direction, and the groove width L of the circumferential grooves at 80% of the maximum depth is... 80 The ratio L to the groove width L0 of the circumferential groove on the contact surface of the tread. 80 / L0 is above 0.3 and below 0.7.

[0297] The present invention (10) is a pneumatic tire according to any one of (1) to (9) of the present invention, wherein the tread has a plurality of circumferential grooves extending continuously in the circumferential direction of the tire, and the total cross-sectional area of ​​the plurality of circumferential grooves is more than 10% and less than 30% of the cross-sectional area of ​​the tread.

[0298] The present invention (11) is a pneumatic tire according to any one of (1) to (10) of the present invention, wherein the tread has a plurality of lateral grooves extending in the axial direction of the tire, and the total volume of the plurality of lateral grooves is more than 2.0% and less than 5.0% of the tread volume.

Claims

1. A pneumatic tire, comprising a sidewall and a belt layer, characterized in that, The tire cross-section width Wt is 285mm or more, and the tire sidewall height T is 100.0mm or more. The belt layer uses monofilament cords as reinforcing cords. In the radial section of the belt-ply tire, the number of monofilament cords arranged per 5cm in the tire width direction, e (cord number / 5cm), and the tire section width Wt in mm when the tire is mounted on a standard rim with an internal pressure of 250kPa, satisfy the following (Equation 1) and (Equation 2): e / (139.5−0.3Wt)>1•••••(Equation 1) e / (191.5−0.3Wt)<1•••••(Equation 2) The complex elastic modulus E* in MPa and the sidewall height T in mm of the sidewall rubber composition in the tire sidewall portion, measured under the conditions of temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, and deformation mode: elongation, satisfy the following (Equation 4): (E* / T)×100≦2.50••••• (Equation 4).

2. The pneumatic tire according to claim 1, characterized in that, The tire cross-section width Wt is less than 300mm.

3. The pneumatic tire according to claim 1 or 2, characterized in that, The outer diameter of the monofilament cord is between 0.1mm and 0.5mm.

4. The pneumatic tire according to any one of claims 1 to 3, characterized in that, The number of monofilament cords arranged per 5cm in the tire width direction, e, i.e., the number of cords / 5cm, is greater than 80 cords / 5cm.

5. The pneumatic tire according to any one of claims 1 to 4, characterized in that, The angle between the reinforcing cords of the belt layer and a straight line parallel to the tire circumference is more than 10° and less than 35°.

6. The pneumatic tire according to any one of claims 1 to 5, characterized in that, The pneumatic tire is provided with at least two belt layers, and at least one group of belt layers adjacent to each other in the radial direction of the tire are arranged at a spacing of less than 0.5 mm.

7. The pneumatic tire according to any one of claims 1 to 6, characterized in that, The tread has circumferential grooves that extend continuously in the tire circumferential direction, and the groove width L at 80% of the maximum depth of the circumferential grooves. 80 The ratio L to the groove width L0 of the circumferential groove on the contact surface of the tread. 80 / L0 is above 0.3 and below 0.

7.

8. The pneumatic tire according to any one of claims 1 to 7, characterized in that, The tread has a plurality of circumferential grooves that extend continuously in the circumferential direction of the tire, wherein the total cross-sectional area of ​​the plurality of circumferential grooves is more than 10% and less than 30% of the cross-sectional area of ​​the tread.

9. The pneumatic tire according to any one of claims 1 to 8, characterized in that, The tread has a plurality of lateral grooves extending axially along the tire, the total volume of which is more than 2.0% and less than 5.0% of the tread volume.

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