pneumatic tires

Abstract

Provided is a pneumatic tire that sufficiently achieves both low rolling resistance and noise performance during high-speed travel. The present invention is a pneumatic tire comprising a tread section and a belt layer, wherein monofilament cords are used as reinforcing cords in the belt layer, and an arranged number e of the monofilament cords per 5 cm in the tire-width direction (cords / 5 cm) in a tire radial direction cross-section of the belt layer, and a tire cross-sectional width Wt (mm), incorporated in a regulation rim and with an internal pressure of 250 kPa, satisfy (formula 1) and (formula 2) below.　(Formula 1): e / (0.31 Wt + 14.35) > 1; (Formula 2): e / (0.31 Wt + 56.45) < 1

Description

[Technical Field]

[0001] The present disclosure relates to a pneumatic tire, and more particularly to a pneumatic tire having a belt layer. [Background technology]

[0002] In recent years, there has been a growing demand for automobiles to be more fuel efficient due to growing concerns about environmental issues and economic reasons, and there is also a strong demand for improved fuel efficiency in the pneumatic tires (hereinafter simply referred to as "tires") that are fitted to automobiles.

[0003] The fuel economy of a tire can be evaluated by its rolling resistance, and it is known that the smaller the rolling resistance, the more fuel-efficient the tire.

[0004] Therefore, it has been proposed to reduce the rolling resistance by devising the compounding of the rubber composition that constitutes the tread portion of the tire (for example, Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-178034 [Patent Document 2] Japanese Patent Application Publication No. 2019-089911 [Patent Document 3] WO2018 / 186367 publication [Patent Document 4] Japanese Patent Application Publication No. 2019-206643 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the construction of expressways in recent years, opportunities for traveling long distances at high speeds have increased dramatically. In this situation, tires manufactured using the above-mentioned conventional technologies are not sufficient in terms of low rolling resistance and noise performance when traveling at high speeds, and further improvements are required.

[0007] Therefore, an object of the present disclosure is to provide a pneumatic tire that satisfactorily achieves both low rolling resistance and noise performance during high-speed driving. [Means for solving the problem]

[0008] The present inventors have conducted extensive research into solving the above problems, and have found that the above problems can be solved by the disclosure described below, leading to the completion of the present disclosure.

[0009] The present disclosure provides: A pneumatic tire having a tread portion and a belt layer, The belt layer uses a monofilament cord as a reinforcing cord, The number e (pieces / 5 cm) of the monofilament cords arranged per 5 cm in the tire width direction in the tire radial cross section of the belt layer and the tire cross section width Wt (mm) when the tire is mounted on a regular rim and the internal pressure is set to 250 kPa satisfy the following (Equation 1) and (Equation 2): And, Furthermore, in the belt layer, the rubber composition covering the reinforcing cords is measured under the conditions of temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: tension, and the loss tangent (tanδ) and the average distance L (mm) between two adjacent monofilament cords in the width direction of the tread portion satisfy the following (Equation 5): The pneumatic tire is characterized by the above. e / (0.31Wt+14.35)>1 (Formula 1) e / (0.31Wt+56.45)<1 (Formula 2) L×tanδ>0.017 (Formula 5) [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a pneumatic tire that satisfactorily achieves both low rolling resistance and noise performance during high-speed driving. DETAILED DESCRIPTION OF THE INVENTION

[0011] [1] Characteristics of the tire according to the present disclosure First, the features of the pneumatic tire (hereinafter also simply referred to as "tire") according to the present disclosure will be described.

[0012] 1. Overview The tire according to the present disclosure is a pneumatic tire including a tread portion and a belt layer, and the belt layer uses monofilament cords as reinforcing cords. The number of monofilament cords arranged per 5 cm in the tire width direction (hereinafter also referred to as "ends") e (ends / 5 cm) in the radial cross section of the belt layer and the tire cross-sectional width Wt (mm) when mounted on a regular rim and internally pressurized to 250 kPa satisfy e / (0.31Wt+14.35)>1 (Formula 1) and e / (0.31Wt+56.45)<1 (Formula 2).

[0013] By having such characteristics, it is possible to provide a tire that satisfactorily achieves both low rolling resistance and noise performance during high-speed running, as will be described later.

[0014] In the above description, the tire cross-sectional width Wt is the width obtained by excluding the patterns, letters, etc. on the side of the tire from the straight-line distance between the sidewalls (total width of the tire) including all patterns, letters, etc. on the side of the tire when the tire is mounted on a regular rim, the internal pressure is set to 250 kPa, and the tire is under no load.

[0015] The term "genuine rim" refers to a rim specified for each tire by a standard system that includes the standard on which the tire is based, such as the standard rim for the applicable size listed in the "JATMA YEAR BOOK" for the JATMA, the "Measuring Rim" listed in the "STANDARDS MANUAL" for the ETRTO (The European Tyre and Rim Technical Organization), or the "Design Rim" listed in the "YEAR BOOK" for the TRA (The Tire and Rim Association, Inc.). For tires not specified by a standard, this refers to a rim that can be mounted on a rim and can maintain internal pressure, i.e., the rim with the smallest rim diameter and the next narrowest rim width, among rims that do not leak air between the rim and tire.

[0016] The number of monofilament cords arranged per 5 cm in the tire width direction (ends) can be expressed by converting the number of monofilament cords measured within a range of ±2.5 to 5.0 cm from the equatorial plane of the tire cross section into a number per 5 cm.

[0017] 2. Mechanism of effect manifestation in tires according to the present disclosure The mechanism by which the tire according to the present disclosure exhibits its effects, that is, the mechanism by which both low rolling resistance and noise performance during high-speed driving are sufficiently achieved, is presumed to be as follows.

[0018] One way to reduce rolling resistance is to reduce the tire weight, and a specific means for achieving this is to use monofilament cords as reinforcing cords for the belt layers.

[0019] However, since monofilament cords are not twisted, it is thought that it is difficult for vibrations to be absorbed within the monofilament cord itself. When monofilament cords are densely arranged in a tire with a narrow tread width, resonance is likely to occur between adjacent monofilament cords, and as the distance between the monofilament cords becomes shorter, resonance at high frequencies is also likely to occur, raising concerns about a deterioration in noise performance, particularly during high-speed driving.

[0020] Therefore, as a countermeasure, if the arrangement of the monofilament cords is made sparser and the distance between the monofilament cords is increased as the tread width becomes narrower, it is thought that this will prevent resonance between the monofilament cords and enable improvement in noise performance.

[0021] However, on the other hand, if the monofilament cords are arranged too sparsely, the tread restraint provided by the belt layer will be reduced, which may cause the tread to round during high-speed driving, increasing the amount of deformation and resulting in a deterioration in rolling resistance during high-speed driving. In particular, tires with a wide tread width require a stronger restraint force because the internal pressure exerts a greater force on the tread to expand and deform. Therefore, it is conceivable to increase the number of monofilament cords arranged as the tread width increases.

[0022] Based on these ideas, the present inventors conducted experiments and studies on the preferable relationship between the number of monofilament cords arranged, e (cords / 5 cm), and the tread width, i.e., the tire cross-sectional width, Wt (mm). As a result, they found that when the above-mentioned e / (0.31Wt+14.35)>1 (Equation 1) and e / (0.31Wt+56.45)<1 (Equation 2) are satisfied, it is possible to achieve both low rolling resistance, e / (0.31Wt+56.45), and noise performance during high-speed driving, and have thus completed the present disclosure.

[0023] That is, as the tire cross-sectional width (tread width) narrows, the number of arranged monofilament cords can be reduced and made sparser, as shown in (Equation 2), thereby increasing the distance between the monofilament cords and suppressing resonance between the monofilament cords, thereby improving noise performance. On the other hand, as the tire cross-sectional width (tread width) widens, the lower limit of the number of arranged monofilament cords can be increased (the number of arranged monofilament cords can be increased), as shown in (Equation 1), thereby maintaining the restraining force of the belt layer and improving low rolling resistance during high-speed driving. Furthermore, by satisfying (Equation 1) and (Equation 2), it is possible to sufficiently achieve both low rolling resistance and noise performance during high-speed driving.

[0024] In the present disclosure, the specific e / (0.31Wt+14.35) is preferably 1.01 or more, more preferably 1.04 or more, even more preferably 1.05 or more, even more preferably 1.07 or more, even more preferably 1.09 or more, even more preferably 1.12 or more, even more preferably 1.19 or more, even more preferably 1.21 or more, even more preferably 1.23 or more, even more preferably 1.24 or more, even more preferably 1.30 or more, even more preferably 1.41 or more, and even more preferably 1.42 or more.

[0025] Furthermore, the specific value of e / (0.31Wt+56.45) is preferably 0.95 or less, more preferably 0.94 or less, even more preferably 0.80 or less, even more preferably 0.79 or less, even more preferably 0.75 or less, even more preferably 0.69 or less, even more preferably 0.68 or less, even more preferably 0.67 or less, even more preferably 0.66 or less, even more preferably 0.65 or less, even more preferably 0.64 or less, and even more preferably 0.63 or less.

[0026] Further experiments and studies revealed that when the tire cross-sectional width Wt is less than 200 mm, it is even more preferable to satisfy e / (0.1924Wt+37.88)>1 (Equation 3) or e / (0.1335Wt+49.644)>1 (Equation 4).

[0027] In this case, the specific value of e / (0.1924Wt+37.88) is preferably 1.01 or more, more preferably 1.02 or more, even more preferably 1.03 or more, even more preferably 1.05 or more, even more preferably 1.16 or more, and even more preferably 1.22 or more. The specific value of e / (0.1335Wt+49.644)>1 is preferably 1.01 or more, more preferably 1.03 or more, even more preferably 1.15 or more, and even more preferably 1.19 or more.

[0028] The lower limit of the tire cross-sectional width Wt is not particularly limited, but considering that it is an automobile tire, it is preferably 125 mm or more, and more preferably 175 mm or more.The upper limit is not particularly limited, but it is preferably 300 mm or less, and more preferably 250 mm or less.

[0029] The number e (cords / 5 cm) of monofilament cords arranged per 5 cm in the tire width direction is not particularly limited, but is preferably more than 80 cords / 5 cm, more preferably 82 cords / 5 cm or more, even more preferably 85 cords / 5 cm or more, and even more preferably 95 cords / 5 cm or more. On the other hand, it is preferably less than 150 cords / 5 cm, and more preferably 120 cords / 5 cm or less.

[0030] The outer diameter d (mm) of the monofilament cord is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.2 mm or more, and is preferably 0.5 mm or less, more preferably 0.4 mm or less.

[0031] The "outer diameter of the cord" in the above description refers to the outer diameter of the monofilament cord of the belt layer in a direction parallel to the tire width direction in the tire cross section, and the average value of the outer diameter of the cord in a direction parallel to the tire width direction measured when calculating the above-mentioned ends e (pieces / 5 cm) can be used.

[0032] [2] More preferred embodiments of the tire according to the present disclosure The tire according to the present disclosure can achieve even greater effects by adopting the following aspects.

[0033] 1. Relationship between the physical properties of the coating rubber composition and the distance between the reinforcing cords As mentioned above, when the distance between the monofilament cords is shortened, resonance at high frequencies is more likely to occur, and there is concern that noise performance may deteriorate during high-speed driving.

[0034] The present inventors have focused on the loss tangent tanδ of the rubber composition coating the reinforcing cords as a parameter that suppresses the occurrence of such resonance between the monofilament cords. That is, the loss tangent tanδ is a parameter that indicates the energy absorption performance, and it is believed that the larger the value, the more energy can be absorbed. Therefore, even if the distance between the monofilament cords is shortened and resonance occurs at high frequencies, it is believed that the rubber composition can absorb the vibration energy and suppress deterioration of noise performance during high-speed driving.

[0035] As a result of experiments and investigations, it was found that deterioration of noise performance during high-speed driving can be sufficiently suppressed if the loss tangent (tanδ) of the rubber composition coating the reinforcing cords in the belt layer when measured under the conditions of temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: tensile, and the average distance L (mm) between two adjacent monofilament cords in the width direction in the tread portion satisfy L × tanδ > 0.017 (Equation 5).

[0036] That is, it was found that by increasing the lower limit of tan δ (coating with a rubber composition with a large tan δ) as the average distance between the monofilament cords becomes smaller, deterioration of noise performance during high-speed driving can be suppressed.

[0037] In the above, the tan δ of the rubber composition can be measured using a viscoelasticity measuring device such as the "IPLEXER (registered trademark)" manufactured by GABO Corp. The average distance L (mm) between two adjacent monofilament cords can be calculated from the following formula based on the outer cord diameter d (mm) and ends e (cords / 5 cm) of the monofilament cord. L = {50-(d×e)} / (e-1)

[0038] In the present disclosure, the specific L×tanδ is preferably 0.018 or more, more preferably 0.020 or more, even more preferably 0.022 or more, even more preferably 0.026 or more, even more preferably 0.027 or more, even more preferably 0.028 or more, and even more preferably 0.029 or more.

[0039] 2. Angle of the reinforcing cord (monofilament cord) The angle formed by the reinforcing cords (monofilament cords) of the belt layer and a line parallel to the tire circumferential direction is preferably 10° or more, more preferably 15° or more, even more preferably 20° or more, and even more preferably 23° or more, while it is preferably 35° or less, more preferably 33° or less, and even more preferably 30° or less.

[0040] By arranging the monofilament cords of the belt layer at such an angle, a hoop effect is achieved, which firmly restrains almost the entire width of the tread portion and reduces the amount of deformation of the tread portion during rolling, thereby achieving both low rolling resistance and noise performance when traveling at high speeds.

[0041] 3.Multi-layered belt In the present disclosure, at least two belt layers are provided to form a multi-layer structure, and in at least one pair of belt layers adjacent in the tire radial direction, the average distance D (mm) between the belt layers in the tread portion is preferably 0.5 mm or less, more preferably 0.45 mm or less, and even more preferably 0.22 mm or less.

[0042] By arranging a set of belt layers at such an average distance D, the belt layers cooperate with each other to restrain the tread portion and reduce the amount of deformation of the tread portion, thereby achieving both low rolling resistance and noise performance during high-speed driving.

[0043] The "average distance D between belt layers" referred to here is the average distance between the monofilament cords of the belt layers, and is the distance between the inner surface of the monofilament cord of the belt layer on the surface side on the equator plane of two overlapping belt layers and the outer surface of the monofilament cord of the inner belt layer.

[0044] In the case where the belt layers are multi-layered, it is sufficient that at least one belt layer satisfies the above-mentioned relationship of "L×tan δ".

[0045] 4. Belt reinforcement layer In the present disclosure, it is preferable that a belt reinforcing layer is provided radially outward of the belt layer, since this further suppresses deformation of the tread portion and more satisfactorily achieves both low rolling resistance and noise performance during high-speed running. In this case, it is preferable that the average distance between the monofilament cords in the belt layer and the cords in the belt reinforcing layer is 0.1 mm or more and 0.5 mm or less.

[0046] 5. Tread grooves The tire according to the present disclosure has a circumferential groove in the tread portion that extends continuously in the tire circumferential direction, and the groove width L at a depth that is 80% of the maximum depth of the circumferential groove with respect to the groove width L0 of the circumferential groove in the contact surface of the tread portion is 80 The ratio (L 80 / L0) is preferably 0.3 or more and 0.7 or less. This makes it possible to suppress the movement of the entire land portion at the bottom surface of the land portion of the tread portion, thereby achieving both low rolling resistance and noise performance during high-speed driving. 80 / L0 is more preferably 0.35 or more, and even more preferably 0.40 or more, and more preferably 0.65 or less, and even more preferably 0.60 or less.

[0047] The above L0 and L 80 The tire is mounted on a standard rim, the internal pressure is set to 250 kPa, and the tire is unloaded. The linear distance (L0) between the groove ends on the tread surface of the circumferential grooves in the tread and the minimum distance (L) between the groove walls at 80% of the groove depth are measured. 80 ) and can be calculated simply by cutting a section of the tire radially, 2 to 4 cm wide, and pressing the space between the beads to match the rim width.

[0048] It is preferable that the tread portion has a plurality of circumferential grooves, the total cross-sectional area of ​​which is 10% to 30% of the cross-sectional area of ​​the tread portion. This suppresses movement of the tread portion, achieving both low rolling resistance and noise performance during high-speed driving. It is more preferable that the total cross-sectional area be 15% or more, and even more preferable that the total cross-sectional area be 18% or more. On the other hand, it is more preferable that the total cross-sectional area be 27% or less, and even more preferable that the total cross-sectional area be 25% or less.

[0049] The cross-sectional area of ​​the circumferential grooves mentioned above refers to the total area formed by the straight lines connecting the ends of the tread circumferential grooves and the groove walls when the tire is mounted on a regular rim, the internal pressure is set to 250 kPa, and the tire is in an unloaded state. Simply put, this can be determined by cutting out a section of the tire in the radial direction with a width of 2 to 4 cm and pressing the space between the bead portions to match the width of the rim.

[0050] The cross-sectional area of ​​the tread portion refers to the area radially outward of the belt layer in a region bounded by a straight line connecting the ends of the circumferential grooves of the tread portion and two straight lines parallel to the equatorial plane, passing through both ends of the widest one of the tread surface profile formed by the tread surface and the belt layer, in a radial cross section of a tire mounted on a regular rim with an internal pressure of 250 kPa and no load. Note that if a belt reinforcing layer made of organic fiber and / or steel cord is present radially outward of the belt layer, the cross-sectional area refers to the area radially outward of the belt reinforcing layer.

[0051] Furthermore, it is preferable that the tread portion has a plurality of lateral grooves extending in the tire axial direction, and 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. This suppresses the movement of the tread portion, thereby achieving both low rolling resistance and noise performance 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 mentioned above refers to the total volume formed by the surfaces connecting the ends of the lateral grooves and the groove walls when the tire is mounted on a regular rim, the internal pressure is 250 kPa, and the tire is in an unloaded state. It can be obtained by calculating the volumes of the individual lateral grooves and adding them up. The volume of the tread portion can be calculated by calculating the area of ​​the tread portion from the section, multiplying it by the outer diameter, and then calculating the difference between the volume of the lateral grooves.

[0053] [3] Implementation form Hereinafter, the present disclosure will be specifically described based on embodiments.

[0054] 1. Rubber composition constituting the belt layer (1) Compounding materials In the belt layer of the tire according to the present disclosure, the rubber composition coated on the monofilament cord can be obtained from the rubber component described below and other compounding materials.

[0055] (a) Rubber component In the present embodiment, the rubber component is not particularly limited, and rubbers (polymers) commonly used in tire manufacturing can be used, such as diene rubbers such as isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), and nitrile rubber (NBR), and butyl rubbers such as butyl rubber. Among these, isoprene rubber is preferred, and it is preferable to use NR because the cis structure of polyisoprene is nearly 100% and its tensile strength is superior to other rubber components. BR and SBR may also be used together as needed.

[0056] (a) Isoprene rubber The amount (total amount) of the isoprene-based rubber in 100 parts by mass of the rubber component is preferably 60 parts by mass or more, more preferably 80 parts by mass or more, and even more preferably 90 parts by mass or more.

[0057] Examples of isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR, with NR being preferred due to its excellent strength.

[0058] As the NR, for example, SIR20, RSS#3, TSR20, and other commonly used rubbers in the tire industry can be used. As the IR, there are no particular limitations, and for example, IR2200, and other commonly used rubbers in the tire industry can be used. Examples of modified NR include deproteinized natural rubber (DPNR) and highly purified 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 alone or in combination of two or more.

[0059] (b)BR In the present embodiment, the rubber component may contain 5 parts by mass or more and 25 parts by mass or less of BR together with NR, if necessary.

[0060] The weight-average molecular weight of the BR is, for example, more than 100,000 and less than 2,000,000. The vinyl bond content (amount of 1,2-bonded butadiene units) of the BR is, for example, more than 1% by mass and less than 30% by mass. The cis content of the BR is, for example, more than 1% by mass and not more than 98% by mass. The trans content of the BR is, for example, more than 1% by mass and less than 60% by mass. The cis content can be measured by infrared absorption spectroscopy.

[0061] The BR is not particularly limited, and can be a BR with a high cis content (cis content of 90% or more), a BR with a low cis content, a BR containing syndiotactic polybutadiene crystals, etc. The BR can be either unmodified or modified, and the modified BR can be, for example, an S-modified BR modified with a compound (modifier) ​​represented by the following formula:

[0062] [ka]

[0063] In the formula, R 1 , R 2 and R 3 R may be the same or different and represent 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 are the same or different and represent a hydrogen atom or an alkyl group. 4 and R 5 may bond to form a ring structure together with the nitrogen atom, and n represents an integer.

[0064] The modified BR modified with the compound (modifying agent) represented by the above formula includes BR whose polymerization terminal (active terminal) has been modified with the compound represented by the above formula.

[0065] R 1 , R 2 and R 3 R is preferably an alkoxy group (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 is preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. In addition, R 4 and R 5 When the groups bond to form a ring structure together with the nitrogen atom, the ring is preferably a 4- to 8-membered ring. The alkoxy group also includes a cycloalkoxy group (such as a cyclohexyloxy group) and an aryloxy group (such as a phenoxy group or a benzyloxy group).

[0066] Specific examples of the modifying agent include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. These may be used alone or in combination of two or more.

[0067] The modified BR may also be modified with the following compounds (modifiers): Examples of the modifier include 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 diglycidylated bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline; Diglycidyl amino compounds such as diglycidyl orthotoluidine, tetraglycidyl meta-xylenediamine, tetraglycidyl aminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidyl aminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamic acid chloride, and N,N-diethylcarbamic acid 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-(trippropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxy sulfide group-containing silane compounds such as (trimethylsilyl)[3-(methyldibutoxysilyl)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)aminoethyltrimethoxysilane, Alkoxysilanes such as thyltriethoxysilane; (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;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, as well as 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-trione , 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-dimethylaminoacetophen, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone, etc. Modification with the above compounds (modifiers) can be carried out by known methods.

[0068] The modified BR may be, for example, a tin-modified BR, which is obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and which preferably has a tin-carbon bond at the end of the tin-modified BR molecule.

[0069] Examples of the lithium initiator include lithium compounds such as alkyllithium, aryllithium, vinyllithium, organotinlithium, and organonitrogen lithium compounds, as well as lithium metal. By using the lithium initiator as the initiator for the tin-modified BR, a tin-modified BR with a high vinyl and low cis content can be produced.

[0070] Examples of tin compounds include tin tetrachloride, butyltin trichloride, dibutyltin dichloride, dioctyltin dichloride, tributyltin chloride, triphenyltin chloride, diphenyldibutyltin, triphenyltin ethoxide, diphenyldimethyltin, ditolyltin chloride, diphenyltin dioctanoate, divinyldiethyltin, tetrabenzyltin, dibutyltin distearate, tetraallyltin, and p-tributyltin styrene.

[0071] The tin atom content in the tin-modified BR is preferably 50 ppm or more, more preferably 60 ppm or more, and is preferably 3000 ppm or less, more preferably 2500 ppm or less, and even more preferably 250 ppm or less.

[0072] The molecular weight distribution (Mw / Mn) of the tin-modified BR is preferably 2 or less, and more preferably 1.5 or less.

[0073] The vinyl bond content in the tin-modified BR is preferably 5% by mass or more, more preferably 7% by mass or more, while the vinyl bond content in the tin-modified BR is preferably 50% by mass or less, more preferably 20% by mass or less.

[0074] The above-mentioned S-modified BR and tin-modified BR may be used alone or in combination of two or more kinds.

[0075] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0076] (c) SBR In the present embodiment, 5 to 25 parts by mass of SBR may be used in the rubber component together with NR, if necessary, or may be used in combination with the above-mentioned BR.

[0077] 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, for example, 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 vinyl bond content of SBR is, for example, preferably more than 5% by mass and less than 70% by mass. SBR structural identification (measurement of styrene content and vinyl bond content) can be performed using, for example, a JNM-ECA series instrument manufactured by JEOL Ltd.

[0078] The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. The SBR may be either unmodified SBR or modified SBR, and these may be used alone or in combination of two or more types.

[0079] The modified SBR may be any SBR having a functional group that interacts with a filler such as silica, and examples thereof include terminal-modified SBR in which at least one terminal of the SBR has been modified with a compound (modifier) ​​having the above functional group (terminal-modified SBR having the above functional group at the terminal), main-chain-modified SBR in which the main chain has the above functional group, main-chain terminal-modified SBR in which the main chain and terminals have the above functional group (for example, main-chain terminal-modified SBR in which the main chain has the above functional group and at least one terminal has been modified with the above modifier), and terminal-modified SBR in which the SBR has been modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and in which a hydroxyl group or epoxy group has been introduced.

[0080] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used. The SBR may be used alone or in combination of two or more types.

[0081] (d) Other rubber components Furthermore, as other rubber components, rubbers (polymers) that are generally used in the production of tires, such as nitrile rubber (NBR), may be included as necessary.

[0082] (b) Compounding materials other than rubber components (a) Filler In this embodiment, the 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. It is also preferable to use silica as a reinforcing agent as needed, and in this case, it is preferable to use silica in combination with a silane coupling agent.

[0083] (i) Carbon black The rubber composition preferably contains carbon black. The amount of carbon black per 100 parts by mass of the rubber component is, for example, preferably 10 parts by mass to 100 parts by mass, more preferably 40 parts by mass to 70 parts by mass, and even more preferably 50 parts by mass to 60 parts by mass.

[0084] The carbon black is not particularly limited, and examples thereof 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 alone or in combination of two or more.

[0085] The nitrogen adsorption specific surface area (N2SA) of carbon black is, for example, 30m 2 / g, 250m 2The dibutyl phthalate (DBP) absorption of carbon black is, for example, more than 50 ml / 100 g and less than 250 ml / 100 g. The nitrogen adsorption specific surface area of ​​carbon black is measured in accordance with ASTM D4820-93, and the DBP absorption is measured in accordance with ASTM D2414-93.

[0086] Specific carbon blacks are not particularly limited, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available carbon blacks include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These may be used alone or in combination of two or more.

[0087] (ii) Silica The rubber composition preferably further contains silica as needed. The BET specific surface area of ​​the silica is 140 m from the viewpoint of obtaining good durability. 2 / g or more is preferable, and 160m 2 On the other hand, from the viewpoint of obtaining good low rolling resistance, it is more preferable that the rolling resistance is more than 250m 2 / g or less is preferable, and 220m 2 More preferably, it is less than / g.

[0088] Furthermore, when a silane coupling agent is not used in combination, the content of silica per 100 parts by mass of the rubber component is preferably 3 parts by mass or more, more preferably 5 parts by mass or more. On the other hand, it is preferably 25 parts by mass or less, more preferably 15 parts by mass or less. When a silane coupling agent is used in combination, 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.

[0089] Examples of silica include dry process silica (anhydrous silica), wet process silica (hydrated silica), etc. Among these, wet process silica is preferred because it has a large number of silanol groups.

[0090] As silica, for example, products from Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0091] (iii) Silane coupling agent As mentioned above, when using silica, a silane coupling agent can be used in combination. The silane coupling agent is not particularly limited, and examples thereof include 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-dimethylthiocathanide, Examples of such compounds include sulfide-based compounds such as rubamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These compounds may be used alone or in combination of two or more.

[0092] As the silane coupling agent, for example, products from Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Dow Corning Toray Co., Ltd., etc. can be used.

[0093] The content of the silane coupling agent is, for example, more than 3 parts by mass and less than 15 parts by mass relative to 100 parts by mass of silica.

[0094] (iv) Other fillers In addition to the above-mentioned carbon black and silica, the rubber composition may further contain fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc. The content of these fillers is, for example, more than 0.1 part by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0095] (b) Hardening resin component The rubber composition preferably contains a curable resin component such as a modified resorcinol resin or a modified phenolic resin, which improves adhesion to the steel cord without significantly deteriorating heat buildup and elongation at break, making it easier for the rubber and the monofilament cord (e.g., steel cord) to generate a large reaction force.

[0096] Specific examples of modified resorcinol resins include Sumikanol 620 (modified resorcinol resin) manufactured by Taoka Chemical Co., Ltd., and examples of modified phenolic resins include PR12686 (cashew oil modified phenolic resin) manufactured by Sumitomo Bakelite Co., Ltd.

[0097] The content of the curable resin component is, for example, preferably 1 part by mass or more, more preferably 2 parts by mass or more, per 100 parts by mass of the rubber component, from the viewpoint of obtaining a large reaction force during deformation, while the content is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, from the viewpoint of maintaining breaking strength.

[0098] When using a modified resorcinol resin, it is preferable to also contain a methylene donor as a curing agent. Examples of methylene donors include hexamethylenetetramine (HMT), hexamethoxymethylolmelamine (HMMM), and hexamethylolmelamine pentamethyl ether (HMMPME). The methylene donor is preferably contained in an amount of, for example, 5 parts by mass or more, and preferably about 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, resulting in poor processability.

[0099] As a specific methylene donor, for example, Sumikanol 507 manufactured by Taoka Chemical Co., Ltd. can be used.

[0100] (c) Resin component From the viewpoint of processability (imparting tackiness), the rubber composition preferably contains a resin component as needed. The resin component may be solid or liquid at room temperature, and specific examples of the resin component include rosin-based resins, styrene-based resins, coumarone-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, and two or more types may be used in combination. The content of the resin component 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.

[0101] Rosin-based resins are resins whose main component is rosin acid, which is obtained by processing pine resin. These rosin-based resins (rosins) can be classified based on whether they are modified or not, and can be divided into unmodified rosin (unmodified rosin) and modified rosin (rosin derivatives). Examples of unmodified rosins include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. Modified rosin is a modification of unmodified rosin, and examples include rosin esters, unsaturated carboxylic acid-modified rosin esters, unsaturated carboxylic acid-modified rosin esters, rosin amide compounds, and rosin amine salts.

[0102] Styrenic resins are polymers that use styrene monomers as constituent monomers, and examples thereof include polymers obtained by polymerizing styrene monomers as the main component (50% by mass or more).Specific 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 be copolymerized with them.

[0103] Examples of the 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, α,β-unsaturated carboxylic acids such as maleic anhydride or acid anhydrides thereof, and the like.

[0104] Among the coumarone resins, coumarone-indene resins are preferred. Coumarone-indene resins are resins containing coumarone and indene as monomer components that constitute the resin skeleton (main chain). Monomer components contained in the skeleton other than coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0105] The amount of the coumarone-indene resin per 100 parts by mass of the rubber component is, for example, more than 1.0 part by mass and less than 50.0 parts by mass.

[0106] The hydroxyl value (OH value) of the coumarone-indene resin is, for example, more than 15 mgKOH / g and less than 150 mgKOH / g. The OH value is the amount of potassium hydroxide, expressed in milligrams, required to neutralize acetic acid bonded to hydroxyl groups when acetylating 1 g of the resin, and is a value measured by potentiometric titration (JIS K 0070:1992).

[0107] The softening point of the coumarone-indene resin is, for example, more than 30° C. and less than 160° C. The softening point is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point tester.

[0108] Terpene resins include polyterpenes, terpene phenols, and aromatic modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenated products. Terpene compounds are (C5H8) n The hydrocarbons and their oxygen-containing derivatives are represented by the following composition: monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0109] Examples of 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 above-mentioned terpene compounds, as well as hydrogenated terpene resins obtained by hydrogenating the terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the above-mentioned terpene compounds with phenolic compounds, and resins obtained by hydrogenating the above-mentioned resins. Specific examples include resins obtained by condensing the above-mentioned terpene compounds, phenolic compounds, and formalin. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Examples of aromatic-modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the above-mentioned resins. The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring, and examples thereof include phenolic compounds such as phenol, alkylphenol, alkoxyphenol, and unsaturated hydrocarbon group-containing phenol; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and unsaturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; coumarone, indene, and the like.

[0110] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions having 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferably used as a C5 petroleum resin.

[0111] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a hydrogenated or modified version. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of suitable aromatic vinyl resins include coumarone-indene resins, coumarone resins, indene resins, and aromatic vinyl resins. Preferred aromatic vinyl resins are homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene, with copolymers of α-methylstyrene and styrene being more preferred, due to their economical efficiency, ease of processing, and excellent heat generation properties. Examples of aromatic vinyl resins that can be used include those commercially available from Kraton, Eastman Chemical Company, and the like.

[0112] "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified resin. Examples of C5 fractions and C9 fractions include the petroleum fractions mentioned above. As the C5C9 resin, for example, commercially available products from Tosoh Corporation, LUHUA, etc. can be used.

[0113] The acrylic resin is not particularly limited, but for example, a solventless acrylic resin can be used.

[0114] Examples of solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized by high-temperature continuous polymerization (high-temperature continuous bulk polymerization) (methods described in U.S. Pat. No. 4,414,370, JP-A-59-6207, JP-B-5-58005, JP-A-1-313522, U.S. Pat. No. 5,010,166, and Toa Gosei Kenkyusho TREND 2000 Vol. 3, pp. 42-45, etc.), with minimal use of secondary raw materials such as polymerization initiators, chain transfer agents, and organic solvents. In this disclosure, (meth)acrylic refers to both methacrylic and acrylic.

[0115] Examples of the monomer components constituting the 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.

[0116] Furthermore, aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene may be used together with (meth)acrylic acid or a (meth)acrylic acid derivative as a monomer component constituting the acrylic resin.

[0117] The acrylic resin may be a resin composed solely of a (meth)acrylic component, or a resin containing components other than a (meth)acrylic component, and may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

[0118] As the resin component, for example, products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JX Nippon Energy Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Co., Ltd., etc. can be used.

[0119] (D) Organic acid cobalt The rubber composition preferably contains an organic acid cobalt, which serves to crosslink the cord and the rubber, and thus by compounding this component, the adhesion between the cord and the rubber can be improved.

[0120] Examples of organic cobalt salts include cobalt stearate, cobalt naphthenate, cobalt neodecanoate, and boron 3 cobalt neodecanoate.

[0121] The content of the organic cobalt salt is preferably 500 ppm or more, more preferably 700 ppm or more, and even more preferably 900 ppm or more, in terms of the cobalt concentration in the rubber composition. On the other hand, it is preferably 1500 ppm or less, and more preferably 1300 ppm or less. If the content is too low, sufficient adhesion between the plated layer of the steel cord and the rubber may not be ensured. On the other hand, if the content is too high, oxidation degradation of the rubber may become significant, resulting in deterioration of the breaking characteristics.

[0122] (e) Reversion inhibitor The rubber composition preferably contains a reversion (reversion) inhibitor as needed. This inhibits reversion and improves durability. The content of the reversion inhibitor is preferably 0.1 to 3 parts by mass, more preferably 0.2 to 2.5 parts by mass, and even more preferably 0.3 to 2 parts by mass, per 100 parts by mass of the rubber component. Specific examples of the reversion inhibitor include Perkalink 900 (1,3-bis(citraconimidomethyl)benzene) manufactured by Flexis Corporation.

[0123] (f) Antiaging agents The rubber composition preferably contains an antioxidant. The content of the antioxidant 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.

[0124] Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants 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 of antioxidants include p-phenylenediamine antioxidants such as quinolone; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. These antioxidants may be used alone or in combination of two or more.

[0125] As the antioxidant, for example, products available from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, etc. can be used.

[0126] (g) Stearic acid The rubber composition may contain stearic acid. The content of stearic acid 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. As the stearic acid, a conventionally known product can be used, such as products from NOF Corporation, NOF Corporation, Kao Corporation, FUJIFILM Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc.

[0127] (H) Zinc oxide The rubber composition may contain zinc oxide. The content of zinc oxide 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. As the zinc oxide, a conventionally known product 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.

[0128] (i) Crosslinking agents and vulcanization accelerators The rubber composition preferably contains a crosslinking agent such as sulfur, etc. The content of the crosslinking agent 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.

[0129] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. These may be used alone or in combination of two or more.

[0130] As sulfur, for example, products from Tsurumi Chemical Industry Co., Ltd., Karuizawa Iso Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0131] Examples of crosslinking agents other than sulfur include vulcanizing agents containing sulfur atoms, such as Tackirol V200 manufactured by Taoka Chemical Co., Ltd., Duralink HTS (sodium 1,6-hexamethylenedithiosulfate 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.

[0132] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator 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.

[0133] Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; 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-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenyl guanidine, di-orthotolyl guanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more.

[0134] (Ju) Other In addition to the above components, the rubber composition may further contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, organic peroxides, etc. 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.

[0135] (2) Preparation of rubber composition The rubber composition is produced by a general method, for example, a production method including a base kneading step of kneading a rubber component with a filler such as carbon black, and a finish kneading step of kneading the kneaded product obtained in the base kneading step with a crosslinking agent.

[0136] The kneading can be carried out using a known (internal) kneading machine such as a Banbury mixer, a kneader, or an open roll.

[0137] The kneading temperature in the base kneading step is, for example, higher than 50° C. and lower than 200° C., and the kneading time is, for example, higher than 30 seconds and lower than 30 minutes. In the base kneading step, in addition to the above components, compounding agents conventionally used in the rubber industry, for example, softeners such as oil, stearic acid, zinc oxide, antioxidants, waxes, vulcanization accelerators, etc., may be appropriately added and kneaded as needed.

[0138] In the final kneading step, the kneaded product obtained in the base kneading step is kneaded with a crosslinking agent. The kneading temperature in the final kneading step is, for example, higher than room temperature and lower than 80°C, and the kneading time is, for example, longer than 1 minute and shorter than 15 minutes. In the final kneading step, in addition to the above components, a vulcanization accelerator, zinc oxide, etc. may be appropriately added and kneaded as necessary.

[0139] 2. Belt component manufacturing The belt member can be produced by topping the obtained rubber composition on both sides of reinforcing cords (monofilament cords such as steel cords) arranged in parallel at a predetermined interval (50 cords / 5 cm or more).

[0140] 3. Tire manufacturing The tire of the present disclosure can be produced as an unvulcanized tire by molding the belt member obtained above together with other tire components on a tire building machine using a conventional method.

[0141] Specifically, an inner liner as a component for ensuring the airtightness of the tire, a carcass as a component for withstanding the load, impact, and inflation pressure to which the tire is subjected, and a belt component as a component for tightly fastening the carcass and increasing the rigidity of the tread are wound around a forming drum, and both ends of the carcass are fixed to both side edges, and bead portions as components for fixing the tire to the rim are arranged. After forming into a toroidal shape, a tread is attached to the center of the outer periphery and sidewalls are attached to the radially outer sides to form side portions, thereby producing an unvulcanized tire.

[0142] In this embodiment, as described above, the belt layer may be provided in a plurality of layers in order to increase the binding force on the tread during running and to easily suppress growth of the outer diameter. In this case, the average distance D (mm) between the cords of each belt layer in the tread portion of the vulcanized tire is preferably 0.5 mm or less. Furthermore, it is preferable that the angle formed by the monofilament cord in the tread portion with a line parallel to the tire circumferential direction is 10° or more and 35° or less, and that the cords of adjacent belt layers are arranged so as to cross each other.

[0143] The angle of the steel cord is the angle of the steel cord relative 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.

[0144] The unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire. The vulcanization process can be carried out by using a known vulcanization method. 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.

[0145] At this time, the tire is molded so as to satisfy the above-mentioned (Equation 1) and (Equation 2) when mounted on a regular rim and the internal pressure is set to 250 kPa.

[0146] Specific tires to which the present disclosure is preferably applied include tires with size notations 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.

[0147] In this embodiment, the present invention can be used for various tires classified into passenger car tires, truck and bus tires, motorcycle tires, etc., and among tires that can satisfy (Formula 1) and (Formula 2), it is preferable to apply it to passenger car tires, that is, tires that are mounted on automobiles that run on four wheels and have a maximum load capacity of 1000 kg or less. By satisfying (Formula 1) and (Formula 2), the present invention can more suitably contribute to solving the problem in the present disclosure, which is to provide a pneumatic tire that satisfies both low rolling resistance and noise performance when running at high speeds.

[0148] The above-mentioned maximum load capacity is a value that is approximately 50 to 100 kg smaller than the maximum load capacity determined for each tire in a standard system that includes the standard on which the tire is based, for example, the maximum load capacity based on the load index (LI) determined by 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, the internal pressure is set to 250 kPa, and the tire is under no load: V is the volume of the 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

[0149] The above-mentioned maximum load capacity is not particularly limited as long as it is 1000 kg or less. However, since an increase in the maximum load capacity generally tends to increase the tire weight and the impact transmitted to the tire, the maximum load capacity is preferably 900 kg or less, more preferably 800 kg or less, and even more preferably 700 kg or less.

[0150] From the viewpoint of reducing the impact transmitted to the tire, 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. The tire weight here refers to the weight of the entire tire, including sealant, sponge, a three-dimensional mesh structure, electronic components, etc., if any, provided on the tire cavity surface. The tire weight can be adjusted appropriately depending on 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 reinforcing layer, the configuration of the bead wires, etc. [Example]

[0151] Hereinafter, the present disclosure will be described more specifically with reference to examples.

[0152] 1. Production of rubber composition for belts First, a rubber composition for a belt was produced.

[0153] (1) Compounding materials First, the following ingredients were prepared.

[0154] (a) Rubber component NR:RSS3

[0155] (b) Compounding materials other than rubber components (a) Carbon black-1: Show Black N326 manufactured by Cabot Japan Co., Ltd. (N2SA:78m 2 / g) (b) Carbon black-2: Show Black N550 manufactured by Cabot Japan Co., Ltd. (N2SA:42m 2 / g) (c) Curable resin component-1: PR12686 manufactured by Sumitomo Bakelite Co., Ltd. (cashew oil modified phenolic resin) (d) Curable resin component-2: Sumikanol 620 manufactured by Taoka Chemical Co., Ltd. (modified resorcinol resin) (e) Hardener: Sumikanol 507 manufactured by Taoka Chemical Co., Ltd. (methylene donor) (f) Organic cobalt salt: DICNATE NBC-2 manufactured by DIC Corporation (Boron cobalt neodecanoate, cobalt content 22.5% by mass) (g) Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. (H) Anti-aging agent-1: Nocrac 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) (i) Antioxidant-2: Antage RD manufactured by Kawaguchi Chemical Industry Co., Ltd. (2,2,4-trimethyl-1,2-dihydroquinoline) (J) Stearic acid: NOF Corporation's "Tsubaki" stearic acid (K) Crosslinking agents, vulcanization accelerators, and crosslinking aids Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator: Noccela NS-P (NS) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-tert-butyl-2-benzothiazolylsulfenamide) Crosslinking agent: Flexis Duralink HTS

[0156] (2) Production of rubber compositions According to the formulations shown in Tables 1 to 4, materials other than the curing agent, sulfur, and vulcanization accelerator were kneaded for 5 minutes at 150°C using a Banbury mixer to obtain kneaded materials. Each blend amount is in parts by mass.

[0157] Next, a curing agent, sulfur, and a vulcanization accelerator were added to the kneaded mixture, and the mixture was kneaded for 5 minutes at 80°C using an open roll to obtain a rubber composition for a belt.

[0158] 2. Tire manufacturing First, steel cords having the configuration and cord outer diameter (mm) shown in Tables 1 to 4 were arranged in the ends (pieces / 5 cm) shown in Tables 1 to 4, and then the previously obtained rubber composition for belts was coated on both sides to produce a belt member. At this time, the same amount of rubber was topped on the top and bottom so that the steel cords were arranged in the center in the thickness direction of the belt member, and the thickness was appropriately adjusted so that the steel cords would be spaced at an average distance D (mm) shown in Tables 1 to 4 between one pair of belt layers in the vulcanized tire.

[0159] Thereafter, two layers of the belt member were bonded together with other tire components so that the steel cords in the belt member intersected each other at angles shown in Tables 1 to 4 with respect to a straight line parallel to the tire circumferential direction, to form an unvulcanized tire, which was press-vulcanized for 10 minutes under a condition of 170°C to produce test tires of the sizes and weights shown in Tables 1 to 4. Tables 1 and 2 list tires with a tire section width Wt of more than 200 mm (Examples 1-1 to 1-12 and Comparative Examples 1-1 to 1-7), while Tables 3 and 4 list tires with a tire section width Wt of 200 mm or less (Examples 2-1 to 2-12 and Comparative Examples 2-1 to 2-7).

[0160] In addition, for each test tire, the above-mentioned (L 80 / L0) was 0.5, the total cross-sectional area of ​​the circumferential grooves was 22% of the cross-sectional area of ​​the tread, and the total volume of the lateral grooves, including those with a groove width / groove depth of 0.65, was 3.5% of the volume of the tread.

[0161] 3. Calculation of parameters The cross-sectional width Wt (mm) of each test tire was then determined, and "0.31Wt + 14.35" and "0.31Wt + 56.45" were calculated. The average distance L (mm) between two adjacent steel cords was then calculated based on the outer cord diameter (mm) and ends e (cords / 5 cm) of the two adjacent steel cords.

[0162] Additionally, a rubber composition was cut out from between the belt layers of each test tire to prepare a 40 mm long, 4 mm wide rubber test piece for measuring viscoelasticity. Tan δ was measured using a GABO Iplexer series tire runner under the following conditions: temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: tension. The distance between the band and belt cords and the results for the belt-to-belt relationship are also shown in Tables 1 to 4. For tires using the same rubber composition, the viscoelasticity of the rubber composition was measured for each specification, and the average value was calculated.

[0163] Then, using the obtained results, "L×tanδ," "e / (0.31Wt+14.35)," and "e / (0.31Wt+56.45)" were calculated. Note that for each test tire shown in Tables 3 and 4, whose tire section width Wt was less than 200 mm, "e / (0.1924Wt+37.88)" and "e / (0.1335Wt+49.644)" were also calculated. The results are shown in Tables 1 to 4.

[0164] 4. Performance evaluation test (1) Evaluation of rolling resistance during high-speed driving Each test tire was fitted to all wheels of a vehicle (a domestically produced FF vehicle with an engine displacement of 2000cc) and inflated to an internal pressure of 250kPa. The vehicle was then driven around a test course on a dry road surface for 10km at a speed of 100km / h, after which the accelerator was released and the distance from when the accelerator was turned off until the vehicle came to a stop was measured as rolling resistance.

[0165] Next, the rolling resistance was evaluated relatively by indexing the results of Comparative Examples 1-7 in Tables 1 and 2, and the results of Comparative Examples 2-7 in Tables 3 and 4, using the results as 100, according to the formula below. The larger the value, the longer the distance from when the accelerator was released until the vehicle came to a stop, the smaller the rolling resistance in the steady state, and the better the fuel economy. Rolling resistance = [(Test tire results) / (Comparative example 1-7 or Comparative example 2-7 results)] ×100

[0166] (2) Evaluation of noise performance during high-speed driving Each test tire was fitted to all wheels of a vehicle (a domestically produced FF vehicle with an engine displacement of 2000cc) and the vehicle was driven on a test course with a dry road surface at a speed of 100 km / h, with the driver standing by the window conducting a sensory test on noise on a five-point scale.

[0167] The evaluations by 20 drivers were totaled, and the results of Comparative Examples 1-4 in Tables 1 and 2, and Comparative Examples 2-4 in Tables 3 and 4 were indexed to 100, and the evaluation was carried out using the reciprocal of that index. A larger index indicates better noise performance during high-speed driving. Noise performance = [(Results of Comparative Examples 1-4 or 2-4) / (Results of Test Tires)] ×100

[0168] (3) Overall evaluation The evaluation results of (1) and (2) above were summed up to form an overall evaluation.

[0169] (4) Evaluation results The results of each evaluation are shown in Tables 1 to 4.

[0170] [Table 1]

[0171] [Table 2]

[0172] [Table 3]

[0173] [Table 4]

[0174] The results shown in Tables 1 to 4 show that when a monofilament cord is used as the reinforcing cord and e / (0.31Wt+14.35)>1 (Equation 1) and e / (0.31Wt+56.45)<1 (Equation 2) are satisfied, a pneumatic tire can be obtained that satisfies both low rolling resistance and noise performance during high-speed driving.

[0175] Furthermore, it can be seen that when the ends are more than 80 cords / 5 cm, when L×tanδ>0.017 (Equation 5) is satisfied, and when the angle between the monofilament cord and a line parallel to the tire circumferential direction is 10° or more and 35° or less, a pneumatic tire can be provided that achieves both low rolling resistance and noise performance during high-speed driving.

[0176] Furthermore, when the tire cross-sectional width Wt is less than 200 mm, it is clear that by satisfying e / (0.1924Wt+37.88)>1 (Equation 3) or e / (0.1335Wt+49.644)>1 (Equation 4), it is possible to provide a pneumatic tire that further achieves both low rolling resistance and noise performance during high-speed driving.

[0177] Although the present disclosure has been described above based on the embodiments, the present disclosure is not limited to the above embodiments. Various modifications can be made to the above embodiments within the scope of the same or equivalent to the present disclosure.

[0178] This disclosure (1) A pneumatic tire having a tread portion and a belt layer, The belt layer uses a monofilament cord as a reinforcing cord, The number e (pieces / 5 cm) of the monofilament cords arranged per 5 cm in the tire width direction in the tire radial cross section of the belt layer and the tire cross section width Wt (mm) when the tire is mounted on a regular rim and the internal pressure is set to 250 kPa satisfy the following (Equation 1) and (Equation 2): And, Furthermore, in the belt layer, the rubber composition covering the reinforcing cords is measured under the conditions of temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: tension, and the loss tangent (tanδ) and the average distance L (mm) between two adjacent monofilament cords in the width direction of the tread portion satisfy the following (Equation 5): The pneumatic tire is characterized by the above. e / (0.31Wt+14.35)>1 (Formula 1) e / (0.31Wt+56.45)<1 (Formula 2) L×tanδ>0.017 (Formula 5)

[0179] This disclosure (2) The pneumatic tire according to the present disclosure (1) is characterized in that the tire cross-sectional width Wt is less than 200 mm and satisfies the following (Equation 3): e / (0.1924Wt+37.88)>1 (Equation 3)

[0180] This disclosure (3) The pneumatic tire according to the present disclosure (1) or (2) is characterized in that the tire cross-sectional width Wt is less than 200 mm and satisfies the following (Formula 4): e / (0.1335Wt+49.644)>1...(Equation 4)

[0181] This disclosure (4) The pneumatic tire is characterized in that the number e (pieces / 5 cm) of the monofilament cords arranged per 5 cm in the tire width direction is greater than 80 pieces / 5 cm, and is any combination with any of the present disclosures (1) to (3).

[0183] This disclosure ( 5 )teeth, The angle formed by the reinforcing cord of the belt layer and a line parallel to the tire circumferential direction is 10° or more and 35° or less, and 4 ) and any combination of pneumatic tires.

[0184] This disclosure ( 6 )teeth, At least two belt layers are provided, At least one pair of adjacent belt layers in the tire radial direction is disposed at a distance of 0.5 mm or less, and 5 ) and any combination of pneumatic tires.

[0185] This disclosure ( 7 )teeth, The monofilament cord has an outer diameter of 0.1 mm or more and 0.5 mm or less, and 6 ) and any combination of pneumatic tires.

[0186] This disclosure ( 8 )teeth, The tire has a circumferential groove in the tread portion that extends continuously in the tire circumferential direction, A groove width L at a depth that is 80% of the maximum depth of the circumferential groove relative to a groove width L0 of the circumferential groove in the ground contact surface of the tread portion 80 The ratio (L 80 / L0) is 0.3 or more and 0.7 or less, and 7 ) and any combination of pneumatic tires.

[0187] This disclosure ( 9 )teeth, The tire has a plurality of circumferential grooves in the tread portion that extend continuously in the circumferential direction of the tire, The total cross-sectional area of ​​the plurality of circumferential grooves is 10% or more and 30% or less of the cross-sectional area of ​​the tread portion, 8 ) and any combination of pneumatic tires.

[0188] This disclosure ( 10 )teeth, The tire has a plurality of axially extending lateral grooves in the tread portion, 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, and 9 ) and any combination of pneumatic tires.

Claims

1. A pneumatic tire having a tread portion and a belt layer, The belt layer uses a monofilament cord as a reinforcing cord, the number e (pieces / 5 cm) of arranged monofilament cords per 5 cm in the tire width direction 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 regular rim and the internal pressure is set to 250 kPa satisfy the following (Equation 1) and (Equation 2), The pneumatic tire further comprises a rubber composition covering the reinforcing cords in the belt layer, the rubber composition being measured under the conditions of a temperature of 70°C, an initial strain of 5%, a dynamic strain of ±1%, a frequency of 10 Hz, and a deformation mode of tension, wherein the loss tangent (tanδ) and the average distance L (mm) between two adjacent monofilament cords in the width direction of the tread portion satisfy the following (Equation 5): e / (0.31Wt+14.35)>1 (Formula 1) e / (0.31Wt+56.45)<1...(Formula 2) L×tanδ>0.017 (Formula 5)

2. 2. The pneumatic tire according to claim 1, wherein the tire cross-sectional width Wt is less than 200 mm and satisfies the following (Equation 3): e / (0.1924Wt+37.88)>1...(Formula 3)

3. 3. The pneumatic tire according to claim 1, wherein the tire cross-sectional width Wt is less than 200 mm, and the following formula (4) is satisfied: e / (0.1335Wt+49.644)>1...(Formula 4)

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

5. 5. The pneumatic tire according to claim 1, wherein an angle formed between the reinforcing cord of the belt layer and a line parallel to the tire circumferential direction is 10 degrees or more and 35 degrees or less.

6. At least two belt layers are provided, 6. The pneumatic tire according to claim 1, wherein at least one pair of belt layers adjacent to each other in the tire radial direction is disposed at a distance of 0.5 mm or less.

7. 7. The pneumatic tire according to claim 1, wherein the monofilament cord has an outer cord diameter of 0.1 mm or more and 0.5 mm or less.

8. The tire has a circumferential groove in the tread portion that extends continuously in the tire circumferential direction, The groove width L of the circumferential groove at the ground contact surface of the tread portion ０ The groove width L at a depth of 80% of the maximum depth of the circumferential groove ８０ The ratio (L ８０ / L ０ 8. The pneumatic tire according to claim 1, wherein the ratio of the axial length of the tread to the axial length of the tire is 0.3 or more and 0.7 or less.

9. The tire has a plurality of circumferential grooves in the tread portion that extend continuously in the circumferential direction of the tire, 9. The pneumatic tire according to claim 1, wherein a total cross-sectional area of ​​the plurality of circumferential grooves is 10% to 30% of a cross-sectional area of ​​the tread portion.

10. The tire has a plurality of axially extending lateral grooves in the tread portion, 10. The pneumatic tire according to claim 1, wherein a total volume of the plurality of lateral grooves is 2.0% or more and 5.0% or less of a volume of the tread portion.

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